Sample records for polyethylene glycol-modified proteins

  1. Surface Forces and Protein Adsorption on Dextran- and Polyethylene Glycol-Modified Polydimethylsiloxane

    PubMed Central

    Farrell, Megan; Beaudoin, Stephen

    2010-01-01

    Dextran and polyethylene glycol (PEG) are often covalently bound to the surface of polydimethylsiloxane (PDMS) for the purpose of modifying its hydrophilicity and biocompatibility. In this work, the effects of the dextran and PEG on the morphology, wetting, and surface charge of the resulting surfaces were quantified and correlated with changes in the amount of fibrinogen and albumin adsorbed from aqueous solution. PDMS films were functionalized in a microwave oxygen plasma to create surface hydroxyl groups that were subsequently aminated by incubation in a (3-aminopropyl)trimethoxysilane (APTES) solution. Oxidized dextran and PEG-aldehyde were linked to the surface amines via reductive amination. This process resulted in low surface coverage of immobilized PEG in the end-on conformation and a more uniform and dense distribution of side-on immobilized dextran. The immobilized dextran reduced the contact angle of the PDMS film from 109° to 80° and neutralized the zeta potential over the pH range from 3 to 11. An atomic force microscope was used to measure the interaction force between the modified PDMS and a model hydrophobic surface (polystyrene latex) and a model hydrophilic surface (silica) in both water and electrolyte solutions to show that van der Waals and hydrophobic attractive forces are the dominant forces for protein adsorption in this system. The PEG- and dextran-modified PDMS were exposed to BSA and fibrinogen to test their resistance to protein adsorption. The coatings were ineffective at reducing the adsorption of either molecule, and the dextran-modification of the PDMS caused more BSA to adsorb than in the case of the unmodified PDMS. PMID:20801620

  2. Surface forces and protein adsorption on dextran- and polyethylene glycol-modified polydimethylsiloxane.

    PubMed

    Farrell, Megan; Beaudoin, Stephen

    2010-12-01

    Dextran and polyethylene glycol (PEG) are often covalently bound to the surface of polydimethylsiloxane (PDMS) for the purpose of modifying its hydrophilicity and biocompatibility. In this work, the effects of the dextran and PEG on the morphology, wetting, and surface charge of the resulting surfaces were quantified and correlated with changes in the amount of fibrinogen and albumin adsorbed from aqueous solution. PDMS films were functionalized in a microwave oxygen plasma to create surface hydroxyl groups that were subsequently aminated by incubation in a (3-aminopropyl)trimethoxysilane (APTES) solution. Oxidized dextran and PEG-aldehyde were linked to the surface amines via reductive amination. This process resulted in low surface coverage of immobilized PEG in the end-on conformation and a more uniform and dense distribution of side-on immobilized dextran. The immobilized dextran reduced the contact angle of the PDMS film from 109° to 80° and neutralized the zeta potential over the pH range from 3 to 11. An atomic force microscope was used to measure the interaction force between the modified PDMS and a model hydrophobic surface (polystyrene latex) and a model hydrophilic surface (silica) in aqueous solution to show that van der Waals and hydrophobic attractive forces are the dominant forces for protein adsorption in this system. The PEG- and dextran-modified PDMS were exposed to BSA and fibrinogen to test their resistance to protein adsorption. The coatings were ineffective at reducing the adsorption of either molecule, and the dextran-modification of the PDMS caused more BSA to adsorb than in the case of the unmodified PDMS. PMID:20801620

  3. Surface forces and protein adsorption on dextran- and polyethylene glycol-modified polydimethylsiloxane

    Microsoft Academic Search

    Megan Farrell; Stephen Beaudoin

    2010-01-01

    Dextran and polyethylene glycol (PEG) are often covalently bound to the surface of polydimethylsiloxane (PDMS) for the purpose of modifying its hydrophilicity and biocompatibility. In this work, the effects of the dextran and PEG on the morphology, wetting, and surface charge of the resulting surfaces were quantified and correlated with changes in the amount of fibrinogen and albumin adsorbed from

  4. Novel effects with polyethylene glycol modified pharmaceuticals.

    PubMed

    Yowell, S L; Blackwell, S

    2002-04-01

    Proteins undergo extensive hydrolysis in the gastrointestinal tract and have short circulating half-lives in the blood. For optimal clinical efficacy, therefore, they must be given by daily injections. Attaching a polyethylene glycol (PEG) moiety (pegylation) improves the pharmacokinetic and pharmacodynamic profiles of proteins. Pegfilgrastim (pegylated filgrastim) has a longer half-life than unmodified filgrastim and, when administered as a single dose, has been shown to be at least as efficacious as daily filgrastim. Because of its reduced renal clearance, the elimination of pegfilgrastim is predominantly neutrophil-mediated, so its clearance is self-regulated. In addition, pegfilgrastim can be administered at a fixed dose instead of in weight-based doses. For these reasons, pegfilgrastim can potentially increase patient adherence and acceptance of treatment, thus having a beneficial effect on their quality of life. Furthermore, treatment is likely to cost less because of the reduced need for medical interventions. Similarly, pegylated liposomal doxorubicin has a longer half-life than unmodified doxorubicin and has been shown, because of its reduced reticuloendothelial system clearance, to produce higher concentrations of doxorubicin in tumours and to have greater clinical efficacy than doxorubicin in the treatment of some solid tumours. Pegylated liposomal doxorubicin is also associated with less myelosuppression and febrile neutropenia. PMID:12173408

  5. Surface polyethylene glycol conformation influences the protein corona of polyethylene glycol-modified single-walled carbon nanotubes: potential implications on biological performance.

    PubMed

    Sacchetti, Cristiano; Motamedchaboki, Khatereh; Magrini, Andrea; Palmieri, Graziana; Mattei, Maurizio; Bernardini, Sergio; Rosato, Nicola; Bottini, Nunzio; Bottini, Massimo

    2013-03-26

    Investigation of the nanoparticle protein corona, the shell of plasma proteins formed around nanoparticles immediately after they enter the bloodstream, is a benchmark in the study of the applications of nanoparticles in all fields of medicine, from pharmacology to toxicology. We report the first investigation of the protein corona adsorbed onto single-walled carbon nanotubes modified with 2 kDa molecular weight polyethylene glycol chains [PEG(2k)-modified SWCNTs or PEG2-SWCNTs] by using a large-scale gel-based proteomics method on biological replicates. More than 240 plasma proteins were selected, and their differences were analyzed among PEG2-SWCNTs differing in surface charge and PEG conformation. The protein corona of PEG2-SWCNTs showed that coagulation proteins, immunoglobulins, apolipoproteins, and proteins of the complement system were among the proteins bound by PEG2-SWCNTs and that their recruitment was independent from the isoelectric point, molecular weight, total hydrophobicity, and number of polyaromatic residues of the proteins. Statistical analysis on protein relative abundance revealed that PEG conformation had a higher influence on the PEG2-SWCNTs' protein corona repertoire than nanotube surface charge. PEG conformation also affected the biological performance of PEG2-SWCNTs. A change in PEG conformation from mushroom to mushroom-brush transition affected the competitive adsorption of the major constituents of the protein corona of PEG2-SWCNTs and promoted shorter blood circulation time, faster renal excretion, and higher relative spleen versus liver uptake of PEG2-SWCNTs. Our data suggest that the protein corona, along with steric stabilization, may mediate the action of PEG conformation on the pharmacokinetic profile of PEG-modified SWCNTs. PMID:23413928

  6. Unusual specificity of polyethylene glycol-modified thermolysin in peptide synthesis catalyzed in organic solvents

    Microsoft Academic Search

    Anne Ferjancic; Antoine Puigserver; Hubert Gaertner

    1988-01-01

    Summary Polyethylene glycol-modified thermolysin was found to efficiently catalyze peptide synthesis in organic solvents. As in aqueous media, the reaction occurred through a rapid equilibrium random bireactant mechanism. However, the substrate specificity of modified thermolysin was actually changed since hydrophilic as well as acidic amino acids were better carboxyl group donors than hydrophobic residues, contrary to what is observed in

  7. Polymerization of 10-hydroxydecanoic acid in benzene with polyethylene glycol-modified lipase

    Microsoft Academic Search

    A. Ajima; T. Yoshimoto; K. Takahashi; Y. Tamaura; Y. Saito; Y. Inada

    1985-01-01

    Summary A hydrophobic substrate, 10-hydroxydecanoic acid having two functional groups (-OH and -COOH) in the molecule, was polymerized by ester bond formation with the polyethylene glycol-modified lipase in a transparent benzene solution. The polymer of 10-hydroxydecanoic acid was linearly elongated under a quite mild condition.

  8. Ester-exchange reaction between triglycerides with polyethylene glycol-modified lipase

    Microsoft Academic Search

    Ayako Matsushima; Yoh Kodera; Katsunobu Takahashi; Yuji Saito; Yuji Inada

    1986-01-01

    Summary Polyethylene glycol-modified lipase efficiently catalyzed esterexchange reaction between trilaurin and triolein in the straight hydrophobic substrates. Dilauroyl-monooleoyl-glycerol and monolauroyl-dioleoyl-glycerol were formed from two triglyceride-substrates, trilaurin and triolein, in the presence of the modified lipase at 58°C. Consequently, the melting temperature of the mixture of two substrates was decreased from 33–36°C to 11–13°C. Similar ester-exchange reaction took place between fat

  9. Effect of supercritical carbon dioxide as an exfoliation aid on bio-based polyethylene terephthalate glycol-modified/clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Jang, Kwangho; Lee, Jae Wook; Hong, In-Kwon; Lee, Sangmook

    2013-08-01

    Bio-based PETG (bio-based glycol modified polyethylene terephthalate, Ecozen T95) / clay (organo-modified montmorillonite, OMMT, C10A) nanocomposites were prepared by co-rotating twin screw extruder attached with supercritical carbon dioxide (scCO2) injection system. The effects of nano-clay and scCO2 on the properties of PETG/clay nanocomposites were investigated by measuring thermal, rheological, tensile, impact, and barrier properties. The thermal and mechanical properties decreased with increasing nano-clay content, but they recovered or even exceeded the properties of neat PETG as scCO2 was added. It was verified due to a good dispersion of the nano-clay in PETG matrix for PETG/clay nanocomposites by XRD, SEM, and TEM. It was thought that scCO2 could be an effective exfoliation agent for many nanocomposites systems as well as for bio-based PET/clay nanocomposites.

  10. Poly(ethylene glycol)-modified Nanocarriers for Tumor-targeted and Intracellular Delivery

    Microsoft Academic Search

    Lilian E. van Vlerken; Tushar K. Vyas; Mansoor M. Amiji

    2007-01-01

    The success of anti-cancer therapies largely depends on the ability of the therapeutics to reach their designated cellular\\u000a and intracellular target sites, while minimizing accumulation and action at non-specific sites. Surface modification of nanoparticulate\\u000a carriers with poly(ethylene glycol) (PEG)\\/poly(ethylene oxide) (PEO) has emerged as a strategy to enhance solubility of hydrophobic\\u000a drugs, prolong circulation time, minimize non-specific uptake, and allow

  11. Diabetes insipidus in uricase-deficient mice: a model for evaluating therapy with poly(ethylene glycol)-modified uricase.

    PubMed

    Kelly, S J; Delnomdedieu, M; Oliverio, M I; Williams, L D; Saifer, M G; Sherman, M R; Coffman, T M; Johnson, G A; Hershfield, M S

    2001-05-01

    Uricase-deficient mice develop uric acid nephropathy, with high mortality rates before weaning. Urate excretion was quantitated and renal function was better defined in this study, to facilitate the use of these mice as a model for evaluating poly(ethylene glycol)-modified recombinant mammalian uricases (PEG-uricase) as a potential therapy for gout and uric acid nephropathy. The uric acid/creatinine ratio in the urine of uricase-deficient mice ranges from 10 to >30; on a weight basis, these mice excrete 20- to 40-fold more urate than do human subjects. These mice consistently develop a severe defect in renal concentrating ability, resulting in an approximately sixfold greater urine volume and a fivefold greater fluid requirement, compared with normal mice. This nephrogenic diabetes insipidus leads to dehydration and death of nursing mice but, with adequate water replacement, high urine flow protects adults from progressive renal damage. Treatment of uricase-deficient mice with PEG-uricase markedly reduced urate levels and, when initiated before weaning, preserved the renal architecture (as evaluated by magnetic resonance micros-copy) and prevented the loss of renal concentrating function. PEG-uricase was far more effective and less immunogenic than unmodified uricase. Retention of uricase in most mammals and its loss in humans and some other primates may reflect the evolution of renal function under different environmental conditions. PEG-uricase could provide an effective therapy for uric acid nephropathy and refractory gout in human patients. PMID:11316859

  12. Improved short-term survival with polyethylene glycol modified hemoglobin liposomes in critical normovolemic anemia

    Microsoft Academic Search

    Andreas Pape; Harry Kertscho; Jens Meier; Oliver Horn; Mohamed Laout; Max Steche; Mischa Lossen; Alf Theisen; Bernhard Zwissler; Oliver Habler

    2008-01-01

    Objective  To investigate the efficacy of a polyethylene glycol (PEG) modified formulation of liposome-encapsulated hemoglobin (LEH)\\u000a as an oxygen-carrying blood substitute in the treatment of critical normovolemic anemia.\\u000a \\u000a \\u000a \\u000a Design and setting  Prospective, controlled, randomized experimental study in a university research facility.\\u000a \\u000a \\u000a \\u000a Subjects  14 anesthetized and mechanically ventilated beagle dogs.\\u000a \\u000a \\u000a \\u000a Interventions  Animals were splenectomized and hemodiluted by exchange of whole blood for iso-oncotic hetastarch (HES). Target parameter

  13. Polyethylene glycol-modified arachidyl chitosan-based nanoparticles for prolonged blood circulation of doxorubicin.

    PubMed

    Termsarasab, Ubonvan; Yoon, In-Soo; Park, Ju-Hwan; Moon, Hyun Tae; Cho, Hyun-Jong; Kim, Dae-Duk

    2014-04-10

    Doxorubicin (DOX)-loaded nanoparticles based on polyethylene glycol-conjugated chitosan oligosaccharide-arachidic acid (CSOAA-PEG) were explored for potential application to leukemia therapy. PEG was conjugated with CSOAA backbone via amide bond formation and the final product was verified by (1)H NMR analysis. Using the synthesized CSOAA-PEG, nanoparticles having characteristics of a 166-nm mean diameter, positive zeta potential, and spherical shape were produced for the delivery of DOX. The mean diameter of CSOAA-PEG nanoparticles in the serum solution (50% fetal bovine serum) remained relatively constant over 72 h as compared with CSOAA nanoparticles (changes of 20.92% and 223.16%, respectively). The sustained release pattern of DOX from CSOAA-PEG nanoparticles was displayed at physiological pH, and the release rate increased under the acidic pH conditions. The cytotoxicity of the CSOAA-PEG conjugate was negligible in human leukemia cells (K562) at the concentrations tested (? 100 ?g/ml). The uptake rate of DOX from the nanoparticles by K562 cells was higher than that from the solution. Judging from the results of pharmacokinetic studies in rats, in vivo clearance rate of DOX from the CSOAA-PEG nanoparticle group was slower than other groups, subsequently extending the circulation period. The PEGylated CSOAA-based nanoparticles could represent an effective nano-sized delivery system for DOX which has been used for the treatment of blood malignancies. PMID:24451239

  14. Polyethylene Glycol Modified, Cross-Linked Starch Coated Iron Oxide Nanoparticles for Enhanced Magnetic Tumor Targeting

    PubMed Central

    Cole, Adam J.; David, Allan E.; Wang, Jianxin; Galbán, Craig J.; Hill, Hannah L.; Yang, Victor C.

    2010-01-01

    While successful magnetic tumor targeting of iron oxide nanoparticles has been achieved in a number of models, the rapid blood clearance of magnetically suitable particles by the reticuloendothelial system (RES) limits their availability for targeting. This work aimed to develop a long-circulating magnetic iron oxide nanoparticle (MNP) platform capable of sustained tumor exposure via the circulation and, thus, enhanced magnetic tumor targeting. Aminated, cross-linked starch (DN) and aminosilane (A) coated MNPs were successfully modified with 5 kDa (A5, D5) or 20 kDa (A20, D20) polyethylene glycol (PEG) chains using simple N-Hydroxysuccinimide (NHS) chemistry and characterized. Identical PEG-weight analogues between platforms (A5 & D5, A20 & D20) were similar in size (140–190 nm) and relative PEG labeling (1.5% of surface amines – A5/D5, 0.4% – A20/D20), with all PEG-MNPs possessing magnetization properties suitable for magnetic targeting. Candidate PEG-MNPs were studied in RES simulations in vitro to predict long-circulating character. D5 and D20 performed best showing sustained size stability in cell culture medium at 37°C and 7 (D20) to 10 (D5) fold less uptake in RAW264.7 macrophages when compared to previously targeted, unmodified starch MNPs (D). Observations in vitro were validated in vivo, with D5 (7.29 hr) and D20 (11.75 hr) showing much longer half-lives than D (0.12 hr). Improved plasma stability enhanced tumor MNP exposure 100 (D5) to 150 (D20) fold as measured by plasma AUC0-? Sustained tumor exposure over 24 hours was visually confirmed in a 9L-glioma rat model (12 mg Fe/kg) using magnetic resonance imaging (MRI). Findings indicate that both D5 and D20 are promising MNP platforms for enhanced magnetic tumor targeting, warranting further study in tumor models. PMID:21176955

  15. Adsorption of poly(ethylene glycol)-modified ribonuclease A to a poly(lactide-co-glycolide) surface.

    PubMed

    Daly, Susan M; Przybycien, Todd M; Tilton, Robert D

    2005-06-30

    Protein adsorption is a source of variability in the release profiles of therapeutic proteins from biodegradable microspheres. We employ optical reflectometry and total internal reflection fluorescence to explore the extent and kinetics of ribonuclease A (RNase A) adsorption to spin-cast films of poly(lactide-co-glycolide) (PLG) and, in particular, to determine how covalent grafting of polyethylene glycol (PEG) to RNase A affects adsorption. Adsorption kinetics on PLG surfaces are surface-limited for RNase A but transport-limited for unconjugated PEG homopolymers and for PEG-modified RNase A, indicating that PEG anchors the conjugates to the surface during the transport-limited regime. PEG modification of RNase A decreases the total number of adsorbed molecules per unit area but increases the areal surface coverage because the grafted PEG chains exclude additional surface area. Total internal reflection fluorescence-based exchange measurements show that there is no exchange between adsorbed and solution-phase protein molecules. This indicates an unusually tenacious adsorption. Streaming current measurements indicate that the zeta potential of the PLG surface becomes increasingly negative as the film is exposed to water for several weeks, as expected. Aging of the PLG surface results in increased adsorption of unmodified RNase A but decreased adsorption of unconjugated PEG homopolymers and of PEG-RNase A conjugates, relative to the extent of adsorption on freshly prepared PLG surfaces. Adsorption results correlate well with an increase in the rate, total extent and preservation of bioactivity of RNase A released from PLG microspheres for the PEG-modified version of RNase A. PMID:15841471

  16. Antitumor effects of polyethylene glycol-modified recombinant human interleukin-2 on mouse uterine cervical carcinoma in vivo

    Microsoft Academic Search

    Lifu Wang; Yuxin Wu; Yongping Zhang; Wei Tang; Xinyuan Liu

    1997-01-01

    Polyethylene glycol (PEG-8000)-modified recombinant human interleukin-2 (PEG-rIL-2) is a cytokine with prolonged circulatory\\u000a half-life. In this paper, the antitumor effects of PEG-rIL-2 against mouse uterine cervical carcinoma (U14) transplanted intraperitoneally or subcutaneously is reported. PEG-rIL-2 at different doses was administered intraperitoneally.\\u000a The results showed that PEG-rIL-2 (4500 IU, i.p., QD×5) prolonged survival time of mice bearing ascites tumor as compared

  17. Polyethylene glycol modified magnetic carbon nanotubes as nanosorbents for the determination of methylprednisolone in rat plasma by high performance liquid chromatography.

    PubMed

    Yu, Panfeng; Ma, Hongwei; Shang, Yong; Wu, Ji; Shen, Shun

    2014-06-27

    In this paper, polyethylene glycol modified (PEGylated) magnetic carbon nanotubes were developed as solid-phase extraction nanosorbents for the determination of methylprednisolone in rat plasma. The procedure mainly involved two steps including preparation of PEGylated magnetic nanosorbents and bioanalysis. Monodisperse magnetites (Fe3O4) anchored onto multi-walled carbon nanotubes (MWCNTs) were synthesized by a facile solvothermal synthesis method. The obtained MWCNTs-Fe3O4 nanomaterials were further non-covalently functionalized by a surfactant phospholipids-polyethylene glycol (DSPE-PEG). Owing to dispersibility and high enrichment ability, water-soluble PEGylated MWCNTs-Fe3O4 nanomaterials can provide more efficient way for the extraction of methylprednisolone than only MWCNTs-Fe3O4 used. The methylprednisolone could be easily extracted via ?-? stacking interactions with PEGylated MWCNTs-Fe3O4. The captured methylprednisolone/nanosorbents were isolated from the matrix by placing a magnet, and desorbed by the elution solvent composed of acetonitrile. Extraction conditions such as amount of nanosorbents added, adsorption time, desorption solvent, and desorption time were investigated and optimized. The method recoveries were obtained from 88.2% to 92.9%. Limits of quantification and limits of detection of 0.01 and 0.005?g/mL were acquired, respectively. The precision ranged from 4.2% to 7.8% for within-day measurement, and for between-day variation was in the range of 5.5-9.0%. Moreover, the analytical performance obtained by PEGylated magnetic MWCNTs was compared with that of magnetic MWCNTs. The results indicated that the approach based on PEGylated magnetic MWCNTs was useful for the analysis of methylprednisolone in the complex plasma. PMID:24837418

  18. Comparative studies of irinotecan-loaded polyethylene glycol-modified liposomes prepared using different PEG-modification methods.

    PubMed

    Yoshino, Keisuke; Nakamura, Koji; Terajima, Yoko; Kurita, Akinobu; Matsuzaki, Takeshi; Yamashita, Keiko; Isozaki, Masashi; Kasukawa, Hiroaki

    2012-11-01

    Recently, a polyethylene glycol (PEG)-modification method for liposomes prepared using pH-gradient method has been proposed. The differences in the pharmacokinetics and the impact on the antitumor effect were examined; however the impact of PEG-lipid molar weight has not been investigated yet. The main purpose of this study is to evaluate the impact of PEG-lipid molar weight against the differences in the pharmacokinetics, the drug-release profile, and the antitumor effect between the proposed PEG-modification method, called the post-modification method, and the conventional PEG-modification method, called the pre-modification method. Various comparative studies were performed using irinotecan as a general model drug. The results showed that PEG-lipid degradation could be markedly inhibited in the post-modification method. Furthermore, prolonged circulation time was observed in the post-modification method. The sustained drug-release was observed in the post-modification method by the results of the drug-releasing test in plasma. Moreover, a higher antitumor effect was observed in the post-modification method. It was also confirmed that the same behaviors were observed in all comparative studies even though the PEG molecular weight was lower. In conclusion, the post-modification method has the potential to be a valuable PEG-modification method that can achieve higher preservation stability of PEG-lipid, prolonged circulation time, and higher antitumor effect with only half the amount of PEG-lipid as compared to the pre-modification method. Furthermore, it was demonstrated that PEG(5000)-lipid would be more desirable than PEG(2000)-lipid since it requires much smaller amount of PEG-lipid to demonstrate the same performances. PMID:22828450

  19. Fast Two-Dimensional Ferritin Crystal Formation Realized by Mutant Ferritin and Poly(ethylene glycol) Modified SiO2 Substrate

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Rikako; Igarashi, Makoto; Samukawa, Seiji; Yamashita, Ichiro

    2012-06-01

    The adsorption behavior of mutant ferritins, which have 24 carbonaceous material binding peptides, onto a polymer-coated SiO2 substrate was studied. A SiO2 surface was modified by poly(L-lysine) (PLL) and poly(ethylene glycol) (PEG) and the spin-coating technique was used. The state of the ferritin array on PLL-coated SiO2 was random adsorption, however, many adjacent domains of hexagonal close-packed ferritin arrays about 100-200 nm in diameter were formed on PEG-coated SiO2. PEG and the protein portion of ferritin were removed by heat treatment. The fabricated dispersed hexagonal close packed nanodot arrays on SiO2 substrates can be applied to semiconductor devices.

  20. Chromatographic separation and mass spectrometric identification of positional isomers of polyethylene glycol-modified growth hormone-releasing factor (1-29)

    Microsoft Academic Search

    Yu Seok Youn; Dong Hee Na; Sun Dong Yoo; Soo-Chang Song; Kang Choon Lee

    2004-01-01

    A one-step chromatographic method capable of separating all isomers of polyethylene glycol (PEG)-growth hormone-releasing factor (GRF) (1-29) conjugates was developed. The unmodified GRF (1-29) and seven different isomers of PEG-GRF (1-29) conjugates were separated by using a simple reversed-phase HPLC method depending on the differences of hydrophobicity due to the number and site of PEG attachment. The PEGylation sites of

  1. Polyethylene glycol-conjugated pharmaceutical proteins

    Microsoft Academic Search

    Pascal Bailon; Wolfgang Berthold

    1998-01-01

    Polyethylene glycol (PEG)-conjugated proteins belong to a new class of biomolecules that are neither proteins nor polymers, but which are hybrids of the two. PEG conjugation of biopharmaceuticals is now common practice in efforts to achieve sustained clinical response. However, very little is known about the strategies and criteria used to produce a well-characterized pegylated biomolecule. In this review, the

  2. Protein diffusion in photopolymerized poly(ethylene glycol) hydrogel networks

    Microsoft Academic Search

    Kristin Engberg; Curtis W Frank

    2011-01-01

    In this study, protein diffusion through swollen hydrogel networks prepared from end-linked poly(ethylene glycol)-diacrylate (PEG-DA) was investigated. Hydrogels were prepared via photopolymerization from PEG-DA macromonomer solutions of two molecular weights, 4600 Da and 8000 Da, with three initial solid contents: 20, 33 and 50 wt\\/wt% PEG. Diffusion coefficients for myoglobin traveling across the hydrogel membrane were determined for all PEG

  3. Enzymatic catalysis in organic solvents: Polyethylene glycol modified hydrogenase retains sulfhydrogenase activity in toluene

    SciTech Connect

    Woodward, C.A.; Kaufman, E.N. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States)

    1996-11-05

    Naturally occurring enzymes may be modified by covalently attaching hydrophobic groups that render the enzyme soluble and active in organic solvents, and have the potential to greatly expand applications of enzymatic catalysis. The reduction of elemental sulfur to hydrogen sulfide by a hydrogenase isolated from Pyrococcus furiosus has been investigated as a model system for organic biocatalysis. While the native hydrogenase catalyzed the reduction of sulfur to H{sub 2}S in aqueous solution, no activity was observed when the aqueous solvent was replaced with anhydrous toluene. Hydrogenase modified with PEG p-nitrophenyl carbonate demonstrated its native biocatalytic ability in toluene when the reducing dye, benzyl viologen, was also present. Neither benzyl viologen or PEG p-nitrophenyl carbonate alone demonstrated reducing capability. PEG modified cellulase and benzyl viologen were also incapable of reducing sulfur to H{sub 2}S, indicating that the enzyme itself, and not the modification procedure, is responsible for the conversion in the nonpolar organic solvent. Sulfide production in toluene was tenfold higher than that produced in an aqueous system with equal enzyme activity, demonstrating the advantages of organic biocatalysis. Applications of bioprocessing in nonaqueous media are expected to provide significant advances in the areas of fossil fuels, renewable feedstocks, organic synthesis, and environmental control technology.

  4. Enzymatic catalysis in organic solvents: Polyethylene glycol modified hydrogenase retains sulfhydrogenase activity in toluene

    Microsoft Academic Search

    C. A. Woodward; E. N. Kaufman

    1996-01-01

    Naturally occurring enzymes may be modified by covalently attaching hydrophobic groups that render the enzyme soluble and active in organic solvents, and have the potential to greatly expand applications of enzymatic catalysis. The reduction of elemental sulfur to hydrogen sulfide by a hydrogenase isolated from Pyrococcus furiosus has been investigated as a model system for organic biocatalysis. While the native

  5. Polyethylene glycol-modified lipase catalyzes asymmetric alcoholysis of ?-decalactone in n-decanol

    Microsoft Academic Search

    Takeshi Uemura; Makoto Furukawa; Yoh Kodera; Misao Hiroto; Ayako Matsushima; Hideyuki Kunol; Hajime Matsushita; Katsukiyo Sakurai; Yuji Inada

    1995-01-01

    Lipase from Pseudomonas cepacia was modified with 2,4-bis[O-methoxypoly(ethylene glycol)]-6-chloro-s-triazine(activated PEG2) to form PEG-lipase. The PEG-lipase, soluble and active in organic solvents, catalyzes asymmetric alcoholysis of racemic d-decalactone in alcohols to form (R)-5-hydroxydecanoic acid alkyl esters. The yield was 69% with 83% enantiomeric excess after 3 hr-reaction in n-decanol at 50°C. The advantage of this reaction is that the alcoholysis proceeds

  6. Protein diffusion in photopolymerized poly(ethylene glycol) hydrogel networks.

    PubMed

    Engberg, Kristin; Frank, Curtis W

    2011-10-01

    In this study, protein diffusion through swollen hydrogel networks prepared from end-linked poly(ethylene glycol)-diacrylate (PEG-DA) was investigated. Hydrogels were prepared via photopolymerization from PEG-DA macromonomer solutions of two molecular weights, 4600 Da and 8000 Da, with three initial solid contents: 20, 33 and 50 wt/wt% PEG. Diffusion coefficients for myoglobin traveling across the hydrogel membrane were determined for all PEG network compositions. The diffusion coefficient depended on PEG molecular weight and initial solid content, with the slowest diffusion occurring through lower molecular weight, high-solid-content networks (D(gel) = 0.16 ± 0.02 × 10(-8) cm(2) s(-1)) and the fastest diffusion occurring through higher molecular weight, low-solid-content networks (D(gel) = 11.05 ± 0.43 × 10(-8) cm(2) s(-1)). Myoglobin diffusion coefficients increased linearly with the increase of water content within the hydrogels. The permeability of three larger model proteins (horseradish peroxidase, bovine serum albumin and immunoglobulin G) through PEG(8000) hydrogel membranes was also examined, with the observation that globular molecules as large as 10.7 nm in hydrodynamic diameter can diffuse through the PEG network. Protein diffusion coefficients within the PEG hydrogels ranged from one to two orders of magnitude lower than the diffusion coefficients in free water. Network defects were determined to be a significant contributing factor to the observed protein diffusion. PMID:21873762

  7. Protein adsorption on various plasma-treated polyethylene terephthalate substrates.

    PubMed

    Recek, Nina; Jaganjac, Morana; Kolar, Metod; Milkovic, Lidija; Mozeti?, Miran; Stana-Kleinschek, Karin; Vesel, Alenka

    2013-01-01

    Protein adhesion and cell response to plasma-treated polymer surfaces were studied. The polymer polyethylene terephthalate (PET) was treated in either an oxygen plasma to make the surface hydrophilic, or a tetrafluoromethane CF(4) plasma to make the surface hydrophobic. The plasma source was radiofrequency (RF) discharge. The adsorption of albumin and other proteins from a cell-culture medium onto these surfaces was studied using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The cellular response to plasma-treated surfaces was studied as well using an MTT assay and scanning electron microscopy (SEM). The fastest adsorption rate was found on the hydrophilic oxygen plasma-treated sample, and the lowest was found on the pristine untreated sample. Additionally, the amount of adsorbed proteins was higher for the oxygen-plasma-treated surface, and the adsorbed layer was more viscoelastic. In addition, cell adhesion studies support this finding because the best cell adhesion was observed on oxygen-plasma-treated substrates. PMID:24152668

  8. Plasma proteins adsorption mechanism on polyethylene-grafted poly(ethylene glycol) surface by quartz crystal microbalance with dissipation.

    PubMed

    Jin, Jing; Jiang, Wei; Yin, Jinghua; Ji, Xiangling; Stagnaro, Paola

    2013-06-01

    Protein adsorption has a vital role in biomaterial surface science because it is directly related to the hemocompatibility of blood-contacting materials. In this study, monomethoxy poly(ethylene glycol) (mPEG) with two different molecular weights was grafted on polyethylene as a model to elucidate the adsorption mechanisms of plasma protein through quartz crystal microbalance with dissipation (QCM-D). Combined with data from platelet adhesion, whole blood clotting time, and hemolysis rate, the blood compatibility of PE-g-mPEG film was found to have significantly improved. Two adsorption schemes were developed for real-time monitoring of protein adsorption. Results showed that the preadsorbed bovine serum albumin (BSA) on the surfaces of PE-g-mPEG films could effectively inhibit subsequent adsorption of fibrinogen (Fib). Nonspecific protein adsorption of BSA was determined by surface coverage, not by the chain length of PEG. Dense PEG brush could release more trapped water molecules to resist BSA adsorption. Moreover, the preadsorbed Fib could be gradually displaced by high-concentration BSA. However, the adsorption and displacement of Fib was determined by surface hydrophilicity. PMID:23659226

  9. Immobilization of oriented protein molecules on poly(ethylene glycol)-coated Si(111)

    Microsoft Academic Search

    Taewoon Cha; Athena Guo; Yongseok Jun; Duanquing Pei; Xiao-Yang Zhu

    2004-01-01

    A high-density poly(ethylene glycol) (PEG)-coated Si(111) surface is used for the immobiliza- tion of polyhistidine-tagged protein molecules. This process features a number of properties that are highly desirable for protein microarray technology: (i) minimal nonspecific protein adsorption; (ii) highly uniform surface functionality; (iii) controlled protein orientation; and (iv) highly specific immobilization reaction without the need of protein purification. The high-density

  10. Comparison between Protein-Polyethylene Glycol (PEG) Interactions and the Effect of PEG on Protein-Protein Interactions Using the Liquid-Liquid Phase Transition

    E-print Network

    Annunziata, Onofrio

    Comparison between Protein-Polyethylene Glycol (PEG) Interactions and the Effect of PEG on Protein-ProteinVember 18, 2006 Phase transitions of protein aqueous solutions are important for protein crystallization and biomaterials science in general. One source of thermodynamic complexity in protein solutions and their phase

  11. Effect of Chain Density on Inhibition of Protein Adsorption by Poly(ethylene glycol) Based Coatings

    Microsoft Academic Search

    Martin Malmsten; Ken Emoto; James M. Van Alstine

    1998-01-01

    The effect of interfacial chain density of poly(ethylene glycol) (PEG) on the adsorption of serum proteins was investigated byin situellipsometry. For terminal covalently grafted PEG of molecular weight 5000 an increased grafting density results in decreased serum protein adsorption. At high interfacial chain density (?0.1 chain\\/nm2), efficient protein rejection was observed, irrespective of the coupling chemistry used. Strongly adsorbed PEG-containing

  12. Ultrafast Solvation Dynamics of Subtilisin-Polyethylene Glycol Interaction for Protein Crystallization

    NASA Astrophysics Data System (ADS)

    Ding, Qing; Meng, Geng; Wang, Shu-Feng; Zheng, Xiao-Feng; Yang, Hong; Gong, Qi-Huang

    2011-06-01

    We study the ultrafast solvation dynamics of protein-precipitant complexes. Protein subtilisin carlsberg (SC) was mixed with several polyethylene glycol (PEG) precipitants for protein crystallization. Picosecond-resolved emission spectra from single intrinsic tryptophan residue (Trp-113) are recorded to construct solvation correlation functions. For precipitant concentrations with various crystallization effects, we observe drastically different solvation relaxation processes. These differences in solvation dynamics are correlated with the local protein structural integrity and water-network stability upon interaction with the precipitants. The solvation dynamics at the protein surface is proposed as a new perspective to study precipitant-protein interactions.

  13. Efficient clearance of poly(ethylene glycol)-modified immunoenzyme with anti-PEG monoclonal antibody for prodrug cancer therapy.

    PubMed

    Cheng, T L; Chen, B M; Chern, J W; Wu, M F; Roffler, S R

    2000-01-01

    The F(ab')(2) fragment of the anti-TAG-72 antibody, B72.3, was covalently linked to Escherichia coli-derived beta-glucuronidase that was modified with methoxypoly(ethylene glycol). The conjugate (B72.3-betaG-PEG) localized to a peak concentration in LS174T xenografts within 48 h after injection, but enzyme activity persisted in plasma such that prodrug administration had to be delayed for at least 4 days to avoid systemic prodrug activation and associated toxicity. Conjugate levels in tumors decreased to 36% of peak levels at this time. Intravenous administration of AGP3, an IgM mAb against methoxypoly(ethylene glycol), accelerated clearance of conjugate from serum and increased the tumor/blood ratio of B72. 3-betaG-PEG from 3.9 to 29.6 without significantly decreasing the accumulation of conjugate in tumors. Treatment of nude mice bearing established human colon adenocarcinoma xenografts with B72. 3-betaG-PEG followed 48 h later with AGP3 and a glucuronide prodrug of p-hydroxyaniline mustard significantly (p< or =0.0005) delayed tumor growth with minimal toxicity compared to therapy with a control conjugate or conventional chemotherapy. PMID:10725103

  14. Monoclonal Antibody-Based Quantitation of Poly(ethylene glycol)-Derivatized Proteins, Liposomes, and Nanoparticles

    Microsoft Academic Search

    Tian-Lu Cheng; Chiu-Min Cheng; Bing-Mae Chen; Der-An Tsao; Kuo-Hsiang Chuang; Sheng-Wen Hsiao; Yi-Hung Lin; Steve R. Roffler

    2005-01-01

    Covalent attachment of poly(ethylene glycol) (PEG) molecules to drugs, proteins, and liposomes is a proven technology for improving their bioavailability, safety, and efficacy. Qualitative and quantitative analysis of PEG-derivatized molecules is important for both drug development and clinical applications. We previously reported the development of a monoclonal IgM antibody (AGP3) to PEG. We now describe a new IgG1 monoclonal antibody

  15. New Insight into the Role of Polyethylene Glycol Acting as Protein Release Modifier in Lipidic Implants

    Microsoft Academic Search

    Sandra Herrmann; Silke Mohl; Florence Siepmann; Juergen Siepmann; Gerhard Winter

    2007-01-01

    Purpose  It has recently been shown that the addition of polyethylene glycol 6000 (PEG) to lipidic implants fundamentally affects the\\u000a resulting protein release kinetics and moreover, the underlying mass transport mechanisms (Herrmann, Winter, Mohl, F. Siepmann,\\u000a & J. Siepmann, J. Control. Release, 2007). However, it is yet unclear in which way PEG acts. It was the aim of this study to

  16. Patterning protein molecules on poly(ethylene glycol) coated Si(1 1 1)

    Microsoft Academic Search

    Yongseok Jun; Taewoon Cha; Athena Guo; X.-Y. Zhu

    2004-01-01

    We demonstrate spatially localized immobilization of protein molecules on high-density poly(ethylene glycol) (PEG) coated Si(111). Patterns of HO- and CH3O-terminated PEG regions are formed on silicon surfaces based on soft lithography techniques and an efficient reaction between alcohol functional groups and chlorine-terminated silicon. Activation of the HO-terminated PEG brush is achieved via either partial oxidation to form aldehyde groups or

  17. In vitro and in vivo protein delivery from in situ forming poly(ethylene glycol)–poly(lactide) hydrogels

    Microsoft Academic Search

    Christine Hiemstra; Zhiyuan Zhong; Sophie R. Van Tomme; Mies J. van Steenbergen; John J. L. Jacobs; Willem Den Otter; Wim E. Hennink; Jan Feijen

    2007-01-01

    Previous studies have shown that stereocomplexed hydrogels are rapidly formed in situ by mixing aqueous solutions of eight-arm poly(ethylene glycol)-poly(L-lactide) and poly(ethylene glycol)–poly(D-lactide) star block copolymers (denoted as PEG–(PLLA)8 and PEG–(PDLA)8, respectively). In this study, in vitro and in vivo protein release from stereocomplexed hydrogels was investigated. These hydrogels were fully degradable under physiological conditions. Proteins could be easily loaded

  18. Characterization of Protein Release from Hydrolytically Degradable Poly(ethylene glycol) Hydrogels

    PubMed Central

    Zustiak, Silviya P.; Leach, Jennie B.

    2011-01-01

    We present a novel fully hydrophilic, hydrolytically degradable poly(ethylene glycol) (PEG) hydrogel suitable for soft tissue engineering and delivery of protein drugs. The gels were designed to overcome drawbacks associated with current PEG hydrogels (i.e., reaction mechanisms or degradation products that compromise protein stability): the highly selective and mild cross-linking reaction allowed for encapsulating proteins prior to gelation without altering their secondary structure as shown by circular dichroism experiments. Further, hydrogel degradation and structure, represented by mesh size, were correlated to protein release. It was determined that polymer density had the most profound effect on protein diffusivity, followed by the polymer molecular weight, and finally by the specific chemical structure of the cross-linker. By examining the diffusion of several model proteins, we confirmed that the protein diffusivity was dependent on protein size as smaller proteins (e.g., lysozyme) diffused faster than larger proteins (e.g., Ig). Furthermore, we demonstrated that the protein physical state was preserved upon encapsulation and subsequent release from the PEG hydrogels and contained negligible aggregation or protein-polymer adducts. These initial studies indicate that the developed PEG hydrogels are suitable for release of stable proteins in drug delivery and tissue engineering applications. PMID:20803477

  19. Recombinant Ganoderma lucidum immunomodulatory protein modified with polyethylene glycol.

    PubMed

    Zhang, Xiping; Sun, Fei; Liu, Zhiyi; Zhang, Shuqin; Liang, Chongyang

    2013-03-01

    Recombinant Ganoderma lucidum immunomodu-latory protein (rLZ-8) expressed using the Pichia yeast eukaryotic expression system is a potential new drug for cancer therapy; however, it has a short half-life in the body. In order to optimize the potency and stability of rLZ-8, we modified the recombinant protein chemically using methoxy-PEG-succinimidyl propionate (mPEG-SPA). The results indicated that several parameters, including pH, the molar ratio of rLZ-8 to mPEG-SPA and time, played crucial roles in the modification process. In particular, when the molar ratio of rLZ-8 to mPEG-SPA was 1:1, rLZ-8 was modified by a single mPEG-SPA moiety. In addition, MALDI-TOF/TOF and ESI Q-Trap results revealed that the difference in molecular weight (MW) between the peptide-linked mPEG-SPA and the mPEG-SPA closely matched the MW of a methionine amino acid. Taken together, these data suggest that modification of mPEG-SPA occurred on the N-terminal helix of rLZ-8. This modification method has laid a foundation for the development of long-acting formulations of rLZ-8. PMID:23338950

  20. Fabrication of nanostructures of polyethylene glycol for applications to protein adsorption and cell adhesion

    NASA Astrophysics Data System (ADS)

    Kim, P.; Kim, D. H.; Kim, B.; Choi, S. K.; Lee, S. H.; Khademhosseini, A.; Langer, R.; Suh, K. Y.

    2005-10-01

    A simple method was developed to fabricate polyethylene glycol (PEG) nanostructures using capillary lithography mediated by ultraviolet (UV) exposure. Acrylate-containing PEG monomers, such as PEG dimethacrylate (PEG-DMA, MW = 330), were photo-cross-linked under UV exposure to generate patterned structures. In comparison to unpatterned PEG films, hydrophobicity of PEG nanostructure modified surfaces was significantly enhanced. This could be attributed to trapped air in the nanostructures as supported by water contact angle measurements. Proteins (fibronectin, immunoglobulin, and albumin) and cells (fibroblasts and P19 EC cells) were examined on the modified surfaces to test for the level of protein adsorption and cell adhesion. It was found that proteins and cells preferred to adhere on nanostructured PEG surfaces in comparison to unpatterned PEG films; however, this level of adhesion was significantly lower than that of glass controls. These results suggest that capillary lithography can be used to fabricate PEG nanostructures capable of modifying protein and cell adhesive properties of surfaces.

  1. Size comparison between proteins PEGylated with branched and linear poly(ethylene glycol) molecules.

    PubMed

    Fee, Conan J

    2007-11-01

    Therapeutic proteins conjugated with branched poly(ethylene glycol) (PEG) have extended in vivo circulation half-lives compared to linear PEG-proteins, thought to be due partly to a greater hydrodynamic volume of branched PEG-proteins, which reduces the glomerular sieving coefficient. In this paper, viscosity radii of PEGylated alpha-lactalbumin (M(r) = 14.2 kDa) and bovine serum albumin (M(r) = 67 kDa) prepared with linear and branched PEGs (with nominal molecular weights 5, 10, 20 and 40 kDa) were compared experimentally using size exclusion chromatography (SEC). PEG adduct:protein molecular weight ratios of the PEGylated proteins covered the range 1:12 to 6:1. Direct comparisons of experimentally measured viscosity radii were found to be misleading due to differences between actual and nominal molecular weights of the PEG reagents used. Comparison with predicted viscosity radii shows that there is no significant difference between the viscosity radii of branched and linear PEG-proteins having the same total molecular weight of PEG adducts. Therefore, longer in vivo circulation half-lives of branched PEG-proteins compared to linear PEG-proteins are not explained by size difference. It is also calculated that the molecular size cut-off for glomerular filtration, 60 A for a 30 kDa PEG, matches the 30-50 A size range for the pores of the glomerular basement membrane. Finally, it is confirmed that prediction of PEG-protein viscosity radii should be based upon conservation of the total PEG adduct surface area to volume ratio for both linear and branched PEG-proteins regardless of PEGylation extent. PMID:17461424

  2. No effect of covalently linked poly(ethylene glycol) chains on protein internal dynamics.

    PubMed

    Gonnelli, Margherita; Strambini, Giovanni B

    2009-03-01

    Poly(ethylene glycol) or PEG is a hydrophilic polymer that covalently linked to therapeutical proteins may significantly increase their pharmacological properties. Despite the extensive production of PEG-conjugated proteins the effects of the polymer on the protein structure and dynamics is poorly understood, making the production of active biomaterials a largely unpredictable process. The present investigation examines the effects of 5 k and 20 k PEG on the internal flexibility of Ribonuclease T1, the mutant C112S of azurin from Pseudomonas aeruginosa, alcohol dehydrogenase and alkaline phosphatase, native and Zn-depleted. These systems encompass structural domains that range from rather superficial, flexible sites to deeply buried, rigid cores. The approach is based on three sensitive parameters related to the phosphorescence emission of internal Trp residues, namely, the intrinsic room-temperature phosphorescence lifetime (tau(0)) that reports on the local flexibility of the protein matrix around the chromophore and the bimolecular rate constant (k(q)) for the quenching of phosphorescence by O(2) and by acrylamide in solution, which are related to the diffusion of these solutes through the protein fold. The results obtained by these three independent, intrinsic probes of protein structure-dynamics concur that mono-PEGylation does not detectably perturb the conformation and dynamics of the protein native fold, over a wide temperature range. The implication is that protein motions are essentially not coupled to the polymer and that adverse effects of chemical modification on biological function are presumably owed to steric hindrance by PEG units blocking the access to sites critical for molecular recognition. PMID:19150514

  3. Nanoparticles of poly(lactide)—tocopheryl polyethylene glycol succinate (PLA-TPGS) copolymers for protein drug delivery

    Microsoft Academic Search

    Sie Huey Lee; Zhiping Zhang; Si-Shen Feng

    2007-01-01

    Nanoparticles (NPs) of poly(lactide)-tocopheryl polyethylene glycol succinate (PLA-TPGS) copolymers with various PLA:TPGS component ratios were prepared by the double emulsion technique for protein drug formulation with bovine serum albumin (BSA) as a model protein. Influence of the PLA:TPGS component ratio and the BSA loading level on the drug encapsulation efficiency (EE) and in vitro drug release behavior was investigated. The

  4. Modification of poly(glycidyl methacrylate–divinylbenzene) porous microspheres with polyethylene glycol and their adsorption property of protein

    Microsoft Academic Search

    Renwei Wang; Ying Zhang; Guanghui Ma; Zhiguo Su

    2006-01-01

    Rigid porous poly(glycidyl methacrylate–divinylbenzene) (P(GMA–DVB)) microspheres were synthesized through suspension polymerization with a mixture of isooctane and 4-methyl-2-pentonal as the porogen. The microspheres were intended to use as column packing materials for protein separation. However, irreversible adsorption of protein was found on the polymer microsphere. To circumvent the problem, polyethylene glycol (PEG) was coupled to the microspheres. The coupling reaction

  5. Protein encapsulation within poly(ethylene glycol)-coated nanospheres. II. Controlled release properties.

    PubMed

    Quellec, P; Gref, R; Dellacherie, E; Sommer, F; Tran, M D; Alonso, M J

    1999-12-01

    The development of injectable nanoparticulate "stealth" carriers for protein delivery is a major challenge. The aim of this work was to investigate the possibility of achieving the controlled release of a model protein, human serum albumin (HSA), from poly(ethylene glycol) (PEG)-coated biodegradable nanospheres (mean diameter of about 200 nm) prepared from amphiphilic diblock PEG-poly(lactic acid) (PLA) copolymers. HSA was efficiently incorporated into the nanospheres, reaching loadings as high as 9% (w/w). Results of the in vitro release studies showed that it is possible to control the HSA release by choosing the appropriate nanosphere size, loading, and composition. These results also revealed that, following their release, HSA molecules readsorbed onto the nanospheres surfaces when they were not protected by a PEG coating. We were surprised to observe that in spite of the water uptake of the PLA-PEG nanospheres [11-29% (w/w)], the copolymer did not significantly degrade after a 15-day incubation period. Therefore, we concluded that during this time HSA release from PLA-PEG nanospheres followed a diffusion mechanism where bulk erosion and surface desorption were negligible. PMID:10487891

  6. Monoliths from poly(ethylene glycol) diacrylate and dimethacrylate for capillary hydrophobic interaction chromatography of proteins

    Microsoft Academic Search

    Yuanyuan Li; H. Dennis Tolley; Milton L. Lee

    2010-01-01

    Rigid monoliths were synthesized solely from poly(ethylene glycol) diacrylates (PEGDA) or poly(ethylene glycol) dimethacrylates (PEGDMA) containing different ethylene glycol chain lengths by one-step UV-initiated polymerization. Methanol\\/ethyl ether and cyclohexanol\\/decanol were used as bi-porogen mixtures for the PEGDA and PEGDMA monoliths, respectively. Effects of PEG chain length, bi-porogen ratio and reaction temperature on monolith morphology and back pressure were investigated. For

  7. Effect of salt additives on protein partition in polyethylene glycol-sodium sulfate aqueous two-phase systems.

    PubMed

    Ferreira, Luisa; Madeira, Pedro P; Mikheeva, Larissa; Uversky, Vladimir N; Zaslavsky, Boris

    2013-12-01

    Partitioning of 15 proteins in polyethylene glycol (PEG)-sodium sulfate aqueous two-phase systems (ATPS) formed by PEG of two different molecular weights, PEG-600 and PEG-8000 in the presence of different buffers at pH7.4 was studied. The effect of two salt additives (NaCl and NaSCN) on the protein partition behavior was examined. The salt effects on protein partitioning were analyzed by using the Collander solvent regression relationship between the proteins partition coefficients in ATPS with and without salt additives. The results obtained show that the concentration of buffer as well as the presence and concentration of salt additives affects the protein partition behavior. Analysis of ATPS in terms of the differences between the relative hydrophobicity and electrostatic properties of the phases does not explain the protein partition behavior. The differences between protein partitioning in PEG-600-salt and PEG-8000-salt ATPS cannot be explained by the protein size or polymer excluded volume effect. It is suggested that the protein-ion and protein-solvent interactions in the phases of ATPS are primarily important for protein partitioning. PMID:23920121

  8. Novel monolithic materials using poly(ethylene glycol) as porogen for protein separation

    Microsoft Academic Search

    Julien Courtois; Emil Byström; Knut Irgum

    2006-01-01

    Several recipes are described for the preparation of porous polymeric monoliths in the capillary format, using poly(ethylene glycol) (PEG) as porogen as well as constituent in the monomer mixture. Acrylic or methacrylic monomers with a variety of terminal groups, with and without ethylene glycol links of differing lengths in the side chains, have been used in combination with triethylene glycol

  9. Capture of Magnetic Nanoparticles in Simulated Blood Vessels: Effects of Proteins and Coating with Poly(ethylene glycol)

    NASA Astrophysics Data System (ADS)

    Robertson, Jaimee; Brazel, Christopher

    2012-11-01

    Magnetic nanoparticles (MNPs) have applications in cancer treatment as they can be captured and localized to a diseased site by use of an external magnetic field. After localization, cancer treatments such as magnetically targeted chemotherapy and localized hyperthermia can be applied. Previously, our lab has shown that the percent capture of MNPs is significantly reduced when MNPs are dispersed in protein solutions compared to water or aqueous polymer solutions. The purpose of this study was to determine the effects of proteins on capture efficiency and to investigate the ability of poly(ethylene glycol), PEG, coatings to reduce aggregation of MNPs with proteins, allowing for a greater capture of MNPs in flow. Using Tygon® tubing to simulate blood vessels, a maghemite nanoparticle solution was pumped through a capture zone, where a magnetic field was applied. After passing through the capture zone, the fluid flowed to a spectrophotometer, which measured the absorbance of the solution. The introduction of proteins into the nanoparticle solution reduced the percent capture of MNPs. However, coating the MNPs with PEG aided in preventing aggregation and led to higher capture efficiencies in protein solutions. Additionally, the effects of capture length and protein exposure time were examined. It was found that a higher percent capture is attainable with a longer capture length. Furthermore, on a scale of hours, the percent capture is not affected by the protein exposure time. Funded by NSF REU Grant 1062611 and NIH NCI R21CA 141388.

  10. Capillary isoelectric focusing and fluorometric detection of proteins and microorganisms dynamically modified by poly(ethylene glycol) pyrenebutanoate.

    PubMed

    Horka, Marie; Ruzicka, Filip; Horký, Jaroslav; Holá, Veronika; Slais, Karel

    2006-12-15

    The nonionogenic pyrene-based tenside, poly(ethylene glycol) pyrenebutanoate, was prepared and applied in capillary isoelectric focusing with fluorometric detection. This dye was used here as a buffer additive in capillary isoelectric focusing for a dynamic modification of the sample of proteins and microorganisms. The values of the isoelectric points of the labeled bioanalytes were calculated with use of the fluorescent pI markers and were found comparable with pI of the native compounds. The mixed cultures of proteins and microorganisms, Escherichia coli CCM 3954, Staphylococcus epidermidis CCM 4418, Proteus vulgaris, Enterococcus faecalis CCM 4224, and Stenotrophomonas maltophilia, the strains of the yeast cells, Candida albicans CCM 8180, Candida krusei, Candida parapsilosis, Candida glabrata, Candida tropicalis, and Saccharomyces cerevisiae were reproducibly focused and separated by the suggested technique. Using UV excitation for the on-column fluorometric detection, the minimum detectable amount was down to 10 cells injected on the separation capillary. PMID:17165837

  11. Fabrication of nanostructures of polyethylene glycol for applications to protein adsorption and cell adhesion

    Microsoft Academic Search

    P. Kim; D. H. Kim; B. Kim; S. K. Choi; S. H. Lee; A. Khademhosseini; R. Langer; K. Y. Suh

    2005-01-01

    A simple method was developed to fabricate polyethylene glycol (PEG) nanostructures using capillary lithography mediated by ultraviolet (UV) exposure. Acrylate-containing PEG monomers, such as PEG dimethacrylate (PEG-DMA, MW = 330), were photo-cross-linked under UV exposure to generate patterned structures. In comparison to unpatterned PEG films, hydrophobicity of PEG nanostructure modified surfaces was significantly enhanced. This could be attributed to trapped

  12. Grafted poly-(ethylene glycol) on lipid surfaces inhibits protein adsorption and cell adhesion

    Microsoft Academic Search

    Hong Du; Parthapratim Chandaroy; Sek Wen Hui

    1997-01-01

    Monolayers of dipalmitoyl-phosphatidylethanolamine (DPPE) mixing with various mole percentages of distearoyl-phosphatidylethanolamine (DSPE)-conjugated poly-(ethylene glycol) (PEG m.w. 750–5000) were deposited on DPPE-coated glass surfaces by the Langmuir-Blodgett method. Increasing percentages of grafted PEG in these supported lipid surfaces increasingly inhibit the adsorption of bovine serum albumin (BSA), laminin, and fibronectin. Increasing percentages of grafted PEG also inhibit the adhesion of erythrocytes,

  13. Separation and partitioning of Green Fluorescent Protein from Escherichia coli homogenate in poly(ethylene glycol)\\/sodium-poly(acrylate) aqueous two-phase systems

    Microsoft Academic Search

    Hans-Olof Johansson; Marina Ishii; Mariane Minaguti; Eloi Feitosa; Thereza Christina Vessoni Penna; Adalberto Pessoa

    2008-01-01

    The partitioning of Green Fluorescent Protein (GFP) in poly(ethylene glycol)\\/Na-poly(acrylate) aqueous two-phase systems (PEG\\/NaPA-ATPS) has been investigated. The aqueous two-phase systems are formed by mixing the polymers with a salt and a protein solution. The protein partitioning in the two-phase system was investigated at 25°C. The concentration of the GFP was measured by fluorimetry. It was found that the partitioning

  14. Effects of one-seed juniper and polyethylene glycol on intake, rumen fermentation, and plasma amino acids in sheep and goats fed supplemental protein and tannins.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We tested the effect of polyethylene glycol (PEG) on juniper and total intake, rumen fermentation, and plasma amino acids (AA) of 12 does and 12 ewes fed sudangrass and basal diets containing 10% quebracho tannins with no protein supplement (Control; 5% CP) or high rumen degradable (RDP 15% CP) or u...

  15. Physical characterizations of microemulsion systems using tocopheryl polyethylene glycol 1000 succinate (TPGS) as a surfactant for the oral delivery of protein drugs

    Microsoft Academic Search

    Wen-Ting Ke; Shyr-Yi Lin; Hsiu-O Ho; Ming-Thau Sheu

    2005-01-01

    Attempts were to develop microemulsion systems using medium chain triglyceride, deionized water, and TPGS as surfactant for the oral delivery of protein drugs or poorly water-soluble drugs. Phase diagrams were constructed to elucidate the phase behavior of systems composed of Captex 300 and water with d-?-tocopheryl polyethylene glycol 1000 succinate (TPGS) as main surfactant, polysorbates (Tween 20, Tween 40, Tween

  16. Use of Cross-Linked Poly(ethylene glycol)-Based Hydrogels for Protein Crystallization

    PubMed Central

    2015-01-01

    Poly(ethylene glycol) (PEG) hydrogels are highly biocompatible materials extensively used for biomedical and pharmaceutical applications, controlled drug release, and tissue engineering. In this work, PEG cross-linked hydrogels, synthesized under various conditions, were used to grow lysozyme crystals by the counterdiffusion technique. Crystallization experiments were conducted using a three-layer arrangement. Results demonstrated that PEG fibers were incorporated within lysozyme crystals controlling the final crystal shape. PEG hydrogels also induced the nucleation of lysozyme crystals to a higher extent than agarose. PEG hydrogels can also be used at higher concentrations (20–50% w/w) as a separation chamber (plug) in counterdiffusion experiments. In this case, PEG hydrogels control the diffusion of the crystallization agent and therefore may be used to tailor the supersaturation to fine-tune crystal size. As an example, insulin crystals were grown in 10% (w/w) PEG hydrogel. The resulting crystals were of an approximate size of 500 ?m. PMID:25383049

  17. Protein encapsulation into biodegradable microspheres by a novel S/O/W emulsion method using poly(ethylene glycol) as a protein micronization adjuvant.

    PubMed

    Morita, T; Sakamura, Y; Horikiri, Y; Suzuki, T; Yoshino, H

    2000-12-01

    A new method for preparing protein-loaded biodegradable microspheres by a process involving solid-in-oil-in-water (S/O/W) emulsion was established using poly(ethylene glycol) (PEG). In the first step, a protein solution was lyophilized with PEG, which resulted in the formation of spherical protein microparticles, less than 5 microm in diameter, dispersed in a continuous PEG phase. This process was well explained by the aqueous phase separation phenomenon induced by freezing-condensation. Since this lyophilizate could be directly dispersed in an organic phase containing biodegradable polymer by dissolving PEG with methylene chloride, a conventional in-water drying method could be adopted in the second step. Through this S/O/W emulsion process, horseradish peroxidase was effectively entrapped into monolithic-type microspheres of poly(DL-lactic-co-glycolic acid) (PLGA), without significant loss of activity. Bovine superoxide dismutase (bSOD), as another model protein, could be encapsulated into reservoir-type microspheres by the 'polymer-alloys method' using both poly(DL-lactic acid) (PLA) and PLGA. The initial release of bSOD from this reservoir-type microsphere was efficiently reduced. Further, the bSOD release kinetics could be suitably modified by adjusting the loading amounts of PEG or polymer composition. In this study, the multi-functional nature of PEG was successfully utilized in the preparation and designing of protein-loaded microspheres. PMID:11102683

  18. Morphology and Properties of Deoiled Cake (DOC) Isolated Mixed Proteins and Low-Density Polyethylene Blends

    Microsoft Academic Search

    Darshan Patel; S. D. Toliwal; J. V. Patel

    2012-01-01

    Proteins were isolated from deoiled cakes (DOC) of soybean, castor and rapeseed. The isolated proteins were then blended with LDPE in different wt. ratios, using PEG400 as a plasticizer. The morphology of the blends was evaluated by using a scanning electron microscope (SEM). Homogeneous blends were obtained and analyzed for various mechanical properties such as tensile strength, impact strength, hardness

  19. Coat Protein-Dependent Behavior of Poly(ethylene glycol) Tails in Iron Oxide Core Virus-like Nanoparticles.

    PubMed

    Malyutin, Andrey G; Cheng, Hu; Sanchez-Felix, Olivia R; Carlson, Kenneth; Stein, Barry D; Konarev, Petr V; Svergun, Dmitri I; Dragnea, Bogdan; Bronstein, Lyudmila M

    2015-06-10

    Here we explore the formation of virus-like nanoparticles (VNPs) utilizing 22-24 nm iron oxide nanoparticles (NPs) as cores and proteins derived from viral capsids of brome mosaic virus (BMV) or hepatitis B virus (HBV) as shells. To accomplish that, hydrophobic FeO/Fe3O4 NPs prepared by thermal decomposition of iron oleate were coated with poly(maleic acid-alt-octadecene) modified with poly(ethylene glycol) (PEG) tails of different lengths and grafting densities. MRI studies show high r2/r1 relaxivity ratios of these NPs that are practically independent of the polymer coating type. The versatility and flexibility of the viral capsid protein are on display as they readily form shells that exceed their native size. The location of the long PEG tails upon shell formation was investigated by electron microscopy and small-angle X-ray scattering. PEG tails were located differently in the BMV and HBV VNPs, with the BMV VNPs preferentially entrapping the tails in the interior and the HBV VNPs allowing the tails to extend through the capsid, which highlights the differences between intersubunit interactions in these two icosahedral viruses. The robustness of the assembly reaction and the protruding PEG tails, potentially useful in modulating the immune response, make the systems introduced here a promising platform for biomedical applications. PMID:25989427

  20. Hydrogels based on poly(ethylene oxide) and poly(tetramethylene oxide) or poly(dimethyl siloxane): synthesis, characterization, in vitro protein adsorption and platelet adhesion

    Microsoft Academic Search

    Jae Hyung Park; You Han Bae

    2002-01-01

    In vitro protein adsorption, platelet adhesion and activation on new hydrogel surfaces, composed of poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (PTMO) or poly(dimethyl siloxane) (PDMS), were investigated. By varying PEO length (MW=2000 or 3400), hydrophobic components (PTMO or PDMS) or polymer topology (block or graft copolymers), various physical hydrogels were produced. Their structures were verified by 1HNMR and ATR-IR and

  1. The influence of poly(ethylene glycol) on the micelle formation of alkyl maltosides used in membrane protein crystallization.

    PubMed

    Müh, Frank; DiFiore, Dörte; Zouni, Athina

    2015-05-01

    With the aim of better understanding the phase behavior of alkyl maltosides (n-alkyl-?-d-maltosides, CnG2) under the conditions of membrane protein crystallization, we studied the influence of poly(ethylene glycol) (PEG) 2000, a commonly used precipitating agent, on the critical micelle concentration (CMC) of the alkyl maltosides by systematic variation of the number n of carbon atoms in the alkyl chain (n = 10, 11, and 12) and the concentration of PEG2000 (?) in a buffer suitable for the crystallization of cyanobacterial photosystem II. CMC measurements were based on established fluorescence techniques using pyrene and 8-anilinonaphthalene-1-sulfonate (ANS). We found an increase of the CMC with increasing PEG concentration according to ln(CMC/CMC0) = kP?, where CMC0 is the CMC in the absence of PEG and kP is a constant that we termed the "polymer constant". In parallel, we measured the influence of PEG2000 on the surface tension of detergent-free buffer solutions. At PEG concentrations ? > 1% w/v, the surface pressure ?s(?) = ?(0) - ?(?) was found to depend linearly on the PEG concentration according to ?s(?) = ?? + ?s(0), where ?(0) is the surface tension in the absence of PEG. Based on a molecular thermodynamic modeling, CMC shifts and surface pressure due to PEG are related, and it is shown that kP = ?c(n) + ?, where c(n) is a detergent-specific constant depending inter alia on the alkyl chain length n and ? is a correction for molarity. Thus, knowledge of the surface pressure in the absence of a detergent allows for the prediction of the CMC shift. The PEG effect on the CMC is discussed concerning its molecular origin and its implications for membrane protein solubilization and crystallization. PMID:25865704

  2. Rapid protein anchoring into the membranes of Mammalian cells using oleyl chain and poly(ethylene glycol) derivatives.

    PubMed

    Kato, Koichi; Itoh, Chika; Yasukouchi, Tohru; Nagamune, Teruyuki

    2004-01-01

    The cell membrane is an important interface for communication with extracellular events, and incorporation of bioactive substances, such as antibodies and receptors, into the cell membrane may enhance the potential abilities of cells. Gene manipulation, chemical modification of membrane proteins, and cell surface painting using a GPI anchor have been performed to introduce substances into cell membranes. Furthermore, many lipid anchors have also been used to modify lipid membranes such as liposomes. In this study, we have focused on developing an easy and rapid method for anchoring of substances including macromolecular proteins into the membranes of living mammalian cells. We employed a single oleyl chain derivative coupled with hydrophilic poly(ethylene glycol) (PEG90, the ethyleneoxide (EO) unit is 90) to facilitate solubilization in water. This water-soluble derivative was designated Biocompatible Anchor for Membrane (BAM). Some proteins (streptavidin, EGFP and an antibody) were coupled with BAM90 at the distal terminal of PEG and rapidly (within a few minutes) anchored into the membranes of various cells (NIH3T3, 32D, Ba/F3, hybridoma 9E10). However, the anchored BAM90 disappeared from the cell membranes within 4-5 h in serum-free culture media, and moreover, the retention time of anchoring was shortened (1-2 h) in culture medium containing 10% FBS. We further prepared a dioleylphosphatidylethanolamine (DOPE)-PEG derivative (DOPE-BAM80, the EO unit is 80) as a double oleyl chain derivative for comparison with the single oleyl chain derivative, BAM90. The retention time of anchored DOPE-BAM80 was longer than that of BAM90 and more than 8 h in culture media with and without 10% serum. Furthermore, the treatment time of DOPE-BAM80 for anchoring was nearly as short (within a few minutes) as that of BAM90. In addition, both types of BAMs, BAM90 and DOPE-BAM80, showed no cytotoxicity. Therefore, DOPE-BAM80 is useful for protein anchoring to cells. Although the utilization of BAM90 is considered to be limited, it is expected to useful in restricted environments, for example, in tissues such as the cornea, peritoneum, bladder, and various mucosae, which are less exposed to serum. Thus, we suggest the possibility that both types of BAM can be applied to cell surface engineering. PMID:15176897

  3. Studies of protein adsorption on implant materials in relation to biofilm formation I. Activity of Pseudomonas aeruginosa on Polypropylene and High density Polyethylene in presence of serum albumin

    E-print Network

    Sinha, S Dutta; Maity, P K; Tarafdar, S; Moulik, S P

    2014-01-01

    The surface of biomaterials used as implants are highly susceptible to bacterial colonization and subsequent infection. The amount of protein adsorption on biomaterials, among other factors, can affect the nature and quality of biofilms formed on them. The variation in the adsorption time of the protein on the biomaterial surface produces a phenotypic change in the bacteria by alteration of the production of EPS (exoplysaccharide) matrix. Knowledge of the effects of protein adsorption on implant infection will be very useful in understanding the chemistry of the biomaterial surfaces, which can deter the formation of biofilms. It is observed that the adsorption of BSA on the biomaterial surfaces increases with time and concentration, irrespective of their type and the nature of the EPS matrix of the bacterial biofilm is dependent on the amount of protein adsorbed on the biomaterial surface. The adsorption of protein (BSA) on the biomaterials, polypropylene (PP) and high density polyethylene (HDPE) has been stu...

  4. Polyethylene Glycol Propionaldehydes

    NASA Technical Reports Server (NTRS)

    Harris, Joe M.; Sedaghat-Herati, Mohammad R.; Karr, Laurel J.

    1992-01-01

    New class of compounds derived from polyethylene glycol (PEG's) namely, PEG-propionaldehydes, offers two important advantages over other classes of PEG aldehyde derivatives: compounds exhibit selective chemical reactivity toward amino groups and are stable in aqueous environment. PEG's and derivatives used to couple variety of other molecules, such as, to tether protein molecules to surfaces. Biotechnical and biomedical applications include partitioning of two phases in aqueous media; immobilization of such proteins as enzymes, antibodies, and antigens; modification of drugs; and preparation of protein-rejecting surfaces. In addition, surfaces coated with PEG's and derivatives used to control wetting and electroosmosis. Another potential application, coupling to aminated surfaces.

  5. Hydrolytic degradation and protein release studies of thermogelling polyurethane copolymers consisting of poly[( R)-3-hydroxybutyrate], poly(ethylene glycol), and poly(propylene glycol)

    Microsoft Academic Search

    Xian Jun Loh; Suat Hong Goh; Jun Li

    2007-01-01

    This paper reports the hydrolytic degradation and protein release studies for a series of newly synthesized thermogelling tri-component multi-block poly(ether ester urethane)s consisting of poly[(R)-3-hydroxybutyrate] (PHB), poly(propylene glycol) (PPG), and poly(ethylene glycol) (PEG). The poly(PEG\\/PPG\\/PHB urethane) copolymer hydrogels were hydrolytically degraded in phosphate buffer at pH 7.4 and 37°C for a period of up to 6 months. The mass loss

  6. The effects of varying poly(ethylene glycol) hydrogel crosslinking density and the crosslinking mechanism on protein accumulation in three-dimensional hydrogels.

    PubMed

    Lee, Soah; Tong, Xinming; Yang, Fan

    2014-10-01

    Matrix stiffness has been shown to play an important role in modulating various cell fate processes such as differentiation and cell cycle. Given that the stiffness can be easily tuned by varying the crosslinking density, poly(ethylene glycol) (PEG) hydrogels have been widely used as an artificial cell niche. However, little is known about how changes in the hydrogel crosslinking density may affect the accumulation of exogenous growth factors within 3-D hydrogel scaffolds formed by different crosslinking mechanisms. To address such shortcomings, we measured protein diffusivity and accumulation within PEG hydrogels with varying PEG molecular weight, concentration and crosslinking mechanism. We found that protein accumulation increased substantially above a critical mesh size, which was distinct from the protein diffusivity trend, highlighting the importance of using protein accumulation as a parameter to better predict the cell fates in addition to protein diffusivity, a parameter commonly reported by researchers studying protein diffusion in hydrogels. Furthermore, we found that chain-growth-polymerized gels allowed more protein accumulation than step-growth-polymerized gels, which may be the result of network heterogeneity. The strategy used here can help quantify the effects of varying the hydrogel crosslinking density and crosslinking mechanism on protein diffusion in different types of hydrogel. Such tools could be broadly useful for interpreting cellular responses in hydrogels of varying stiffness for various tissue engineering applications. PMID:24887284

  7. Structural features important for differences in protein partitioning in aqueous dextran-polyethylene glycol two-phase systems of different ionic compositions.

    PubMed

    Ferreira, Luisa; Fan, Xiao; Mikheeva, Larissa M; Madeira, Pedro P; Kurgan, Lukasz; Uversky, Vladimir N; Zaslavsky, Boris Y

    2014-03-01

    Partitioning of 15 proteins in dextran-70-polyethylene glycol (PEG)-8000 aqueous two-phase systems (ATPSs) in the presence of 0.01M sodium phosphate buffer, pH7.4 was studied. The effect of salt additives (NaCl, CsCl, Na2SO4, NaClO4 and NaSCN) at different concentrations on the protein partition behavior was examined. The salt effects on protein partitioning were analyzed by using the Collander solvent regression relationship between the protein partition coefficients in ATPSs with and without salt additives. The results obtained show that the presence and concentration of salt additives affect the protein partition behavior. Analysis of ATPSs in terms of the differences between the relative hydrophobicity and electrostatic properties of the phases does not explain the protein partition behavior. The differences between protein partitioning could not be explained by the protein size. The structural signatures for the proteins were constructed from partition coefficient values in four ATPSs with different salt additives, and the structural distances were calculated using cytochrome c as the reference structure. The structural distances for all the examined proteins (except lysozyme) were found to be interrelated. Analysis of about 50 different descriptors of the protein structures revealed that the partition behavior of proteins is determined by the peculiarities of their surfaces (e.g., the number of water-filled cavities and the averaged hydrophobicity of the surface residues) and by the intrinsic flexibility of the protein structure measured in terms of the B-factor (or temperature factor). PMID:24486798

  8. Proteomic analysis of lettuce seed germination and thermoinhibition by sampling of individual seeds at germination and removal of storage proteins by polyethylene glycol fractionation.

    PubMed

    Wang, Wei-Qing; Song, Bin-Yan; Deng, Zhi-Jun; Wang, Yue; Liu, Shu-Jun; Møller, Ian Max; Song, Song-Quan

    2015-04-01

    Germination and thermoinhibition in lettuce (Lactuca sativa 'Jianyexianfeng No. 1') seeds were investigated by a proteomic comparison among dry seeds, germinated seeds at 15°C, at 15°C after imbibition at 25°C for 48 h, or at 25°C in KNO3 (all sampled individually at germination), and ungerminated seeds at 25°C, a thermoinhibitory temperature. Before two-dimensional gel electrophoresis analysis, storage proteins (greater than 50% of total extractable protein) were removed by polyethylene glycol precipitation, which significantly improved the detection of less abundant proteins on two-dimensional gels. A total of 108 protein spots were identified to change more than 2-fold (P<0.05) in abundance in at least one germination treatment. Nineteen proteins increasing and one protein decreasing in abundance during germination had higher abundance in germinated 15°C, 15°C after imbibition at 25°C for 48 h, and 25°C in KNO3 seeds than in ungerminated 25°C seeds. Gene expression of 12 of those proteins correlated well with the protein accumulation. Methionine metabolism, ethylene production, lipid mobilization, cell elongation, and detoxification of aldehydes were revealed to be potentially related to lettuce seed germination and thermoinhibition. Accumulation of three proteins and expression of five genes participating in the mevalonate (MVA) pathway of isoprenoid biosynthesis correlated positively with seed germinability. Inhibition of this pathway by lovastatin delayed seed germination and increased the sensitivity of germination to abscisic acid. MVA pathway-derived products, cytokinins, partially reversed the lovastatin inhibition of germination and released seed thermoinhibition at 25°C. We conclude that the MVA pathway for isoprenoid biosynthesis is involved in lettuce seed germination and thermoinhibition. PMID:25736209

  9. Studies of protein adsorption on implant materials in relation to biofilm formation I. Activity of Pseudomonas aeruginosa on Polypropylene and High density Polyethylene in presence of serum albumin

    E-print Network

    S Dutta Sinha; Susmita Chatterjee; P. K. Maity; S. Tarafdar; S. P. Moulik

    2014-11-19

    The surface of biomaterials used as implants are highly susceptible to bacterial colonization and subsequent infection. The amount of protein adsorption on biomaterials, among other factors, can affect the nature and quality of biofilms formed on them. The variation in the adsorption time of the protein on the biomaterial surface produces a phenotypic change in the bacteria by alteration of the production of EPS (exoplysaccharide) matrix. Knowledge of the effects of protein adsorption on implant infection will be very useful in understanding the chemistry of the biomaterial surfaces, which can deter the formation of biofilms. It is observed that the adsorption of BSA on the biomaterial surfaces increases with time and concentration, irrespective of their type and the nature of the EPS matrix of the bacterial biofilm is dependent on the amount of protein adsorbed on the biomaterial surface. The adsorption of protein (BSA) on the biomaterials, polypropylene (PP) and high density polyethylene (HDPE) has been studied and the formation of the biofilms of Pseudomonas aeruginosa on them has been examined.

  10. Anti-PEG IgM Is a Major Contributor to the Accelerated Blood Clearance of Polyethylene Glycol-Conjugated Protein.

    PubMed

    Mima, Yu; Hashimoto, Yosuke; Shimizu, Taro; Kiwada, Hiroshi; Ishida, Tatsuhiro

    2015-07-01

    Limited therapeutic efficacy of polyethylene glycol-conjugated (PEGylated) protein drugs has been recently reported in animals and human following repeat injections. Since there are reports that an accelerated blood clearance (ABC) phenomenon is caused by repeated injection of PEGylated liposome, there is an assumption that PEGylated proteins lose their long circulating property when they are injected repeatedly due to the induction of anti-PEG antibody. Although induction of anti-PEG antibody by PEGylated protein has been reported, there is little evidence of accelerated blood clearance of PEGylated protein upon repeated injection. Herein, we investigated the blood concentration of PEGylated ovalbumin (PEG-OVA), a model PEGylated protein, upon its repeated injection. A single intravenous administration of PEG-OVA elicited an anti-PEG IgM response but not anti-PEG IgG response, while the administration did not elicit antibody against OVA. At 24 h postinjection of test PEG-OVA, although control mice showed 41.6% dose of PEG-OVA in blood, the mice pretreated with PEG-OVA showed rapid clearance of test PEG-OVA from blood and undetectable level of PEG-OVA. Interestingly, the anti-PEG IgM induced by PEGylated liposome did not affect the blood concentration of subsequent dose of PEG-OVA. Our result suggests that anti-PEG IgM is a major contributor to the accelerated blood clearance of PEG-conjugated protein, but the presence of anti-PEG IgM in blood circulation does not necessarily affect circulating property of entire PEGylated materials. PMID:26070445

  11. ‘Stealth’ corona-core nanoparticles surface modified by polyethylene glycol (PEG): influences of the corona (PEG chain length and surface density) and of the core composition on phagocytic uptake and plasma protein adsorption

    Microsoft Academic Search

    R Gref; M Lück; P Quellec; M Marchand; E Dellacherie; S Harnisch; T Blunk; R. H Müller

    2000-01-01

    Nanoparticles possessing poly(ethylene glycol) (PEG) chains on their surface have been described as blood persistent drug delivery system with potential applications for intravenous drug administration. Considering the importance of protein interactions with injected colloidal dug carriers with regard to their in vivo fate, we analysed plasma protein adsorption onto biodegradable PEG-coated poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) and poly(?-caprolactone) (PCL)

  12. Separating chemical and excluded volume interactions of polyethylene glycols with native proteins: Comparison with PEG effects on DNA helix formation.

    PubMed

    Shkel, Irina A; Knowles, D B; Record, M Thomas

    2015-09-01

    Small and large PEGs greatly increase chemical potentials of globular proteins (?2 ), thereby favoring precipitation, crystallization, and protein-protein interactions that reduce water-accessible protein surface and/or protein-PEG excluded volume. To determine individual contributions of PEG-protein chemical and excluded volume interactions to ?2 as functions of PEG molality m3 , we analyze published chemical potential increments ?23 ?=?d?2 /dm3 quantifying unfavorable interactions of PEG (PEG200-PEG6000) with BSA and lysozyme. For both proteins, ?23 increases approximately linearly with the number of PEG residues (N3 ). A 1 molal increase in concentration of PEG -CH2 OCH2 - groups, for any chain-length PEG, increases ?BSA by ?2.7 kcal/mol and ?lysozyme by ?1.0 kcal/mol. These values are similar to predicted chemical interactions of PEG -CH2 OCH2 - groups with these protein components (BSA ?3.3 kcal/mol, lysozyme ?0.7 kcal/mol), dominated by unfavorable interactions with amide and carboxylate oxygens and counterions. While these chemical effects should be dominant for small PEGs, larger PEGS are expected to exhibit unfavorable excluded volume interactions and reduced chemical interactions because of shielding of PEG residues in PEG flexible coils. We deduce that these excluded volume and chemical shielding contributions largely compensate, explaining why the dependence of ?23 on N3 is similar for both small and large PEGs. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 517-527, 2015. PMID:25924886

  13. Influence of poly(ethylene oxide)-based copolymer on protein adsorption and bacterial adhesion on stainless steel: modulation by surface hydrophobicity.

    PubMed

    Yang, Yi; Rouxhet, Paul G; Chudziak, Dorota; Telegdi, Judit; Dupont-Gillain, Christine C

    2014-06-01

    The aim of the present work is to study the adhesion of Pseudomonas NCIMB 2021, a typical aerobic marine microorganism, on stainless steel (SS) substrate. More particularly, the potential effect on adhesion of adsorbed poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer is investigated. Bacterial attachment experiments were carried out using a modified parallel plate flow chamber, allowing different surface treatments to be compared in a single experiment. The amount of adhering bacteria was determined via DAPI staining and fluorescence microscopy. X-ray photoelectron spectroscopy (XPS) was used to characterize the surface chemical composition of SS and hydrophobized SS before and after PEO-PPO-PEO adsorption. The adsorption of bovine serum albumin (BSA), a model protein, was investigated to test the resistance of PEO-PPO-PEO layers to protein adsorption. The results show that BSA adsorption and Pseudomonas 2021 adhesion are significantly reduced on hydrophobized SS conditioned with PEO-PPO-PEO. Although PEO-PPO-PEO is also found to adsorb on SS, it does not prevent BSA adsorption nor bacterial adhesion, which is attributed to different PEO-PPO-PEO adlayer structures on hydrophobic and hydrophilic surfaces. The obtained results open the way to a new strategy to reduce biofouling on metal oxide surfaces using PEO-PPO-PEO triblock copolymer. PMID:24650936

  14. Specific Adsorption of Histidine-Tagged Proteins on Silica Surfaces Modified with Ni2+:NTA-Derivatized Poly(Ethylene Glycol)

    PubMed Central

    Kang, Eunah; Park, Jin-won; McClellan, Scott; Kim, Jong-Mok; Holland, David; Lee, Gil U.; Franses, Elias; Park, Kinam; Thompson, David H.

    2008-01-01

    Silica surfaces modified with nitrilotriacetic acid (NTA)-polyethylene glycol (PEG) derivatives were used for immobilizing hexahistidine-tagged green fluorescent oprotein (his6-GFP), biotin/streptavidin-AlexaFluor555 (his6-biotin/SA-AF) and gramicidin A-containing vesicles (his6-gA). Three types of surface-reactive PEG derivatives—NTA-PEG3400-Si(OMe)3, NTA-PEG3400-vinylsulfone, and mPEG5000-Si(OMe)3 (control)—were grafted onto silica and tested for their ability to capture his6-tag species via his6:Ni2+:NTA chelation. The composition and thicknesses of the PEG-modified surfaces were characterized using x-ray photoelectron spectroscopy, contact angle, and ellipsometry. Protein capture efficiencies of the NTA-PEG-grafted surfaces were evaluated by measuring fluorescence intensities of these surfaces after exposure to his6-tag species. XPS and ellipsometry data indicate that surface adsorption occurs via specific interactions between the his6-tag and the Ni2+:NTA-PEG-grafted surface. Protein immobilization was most effective for NTA-PEG3400-Si(OMe)3-modified surfaces, with maximal areal densities achieved at 45 pmol/cm2 for his6-GFP and 95 fmol/cm2 for his6-biotin/SA-AF. Lipid vesicles containing his6-gA in a 1:375 gA:lipid ratio could also be immobilized on Ni2+:NTA-PEG3400-Si(OMe)3-modified surfaces at 0.5 mM total lipid. Our results suggest that NTA-PEG-Si(OMe)3 conjugates may be useful tools for immobilizing his6-tag proteins on solid surfaces to produce protein-functionalized surfaces. PMID:17444666

  15. Hydrolytic degradation and protein release studies of thermogelling polyurethane copolymers consisting of poly[(R)-3-hydroxybutyrate], poly(ethylene glycol), and poly(propylene glycol).

    PubMed

    Loh, Xian Jun; Goh, Suat Hong; Li, Jun

    2007-10-01

    This paper reports the hydrolytic degradation and protein release studies for a series of newly synthesized thermogelling tri-component multi-block poly(ether ester urethane)s consisting of poly[(R)-3-hydroxybutyrate] (PHB), poly(propylene glycol) (PPG), and poly(ethylene glycol) (PEG). The poly(PEG/PPG/PHB urethane) copolymer hydrogels were hydrolytically degraded in phosphate buffer at pH 7.4 and 37 degrees C for a period of up to 6 months. The mass loss profiles of the copolymer hydrogels were obtained. The hydrogel residues at different time periods of hydrolysis were visualized by scanning electron microscopy, which exhibited increasing porosity with time of hydrolysis. The degradation products in the buffer were characterized by GPC, (1)H NMR, MALDI-TOF, and TGA. The results showed that the ester backbone bonds of the PHB segments were broken by random chain scission, resulting in a decrease in the molecular weight. In addition, the constituents of degradation products were found to be 3-hydroxybutyric acid monomer and oligomers of various lengths (n=1-5). The protein release profiles of the copolymer hydrogels were obtained using BSA as model protein. The results showed that the release rate was controllable by varying the composition of the poly(ether ester urethane)s or by adjusting the concentration of the copolymer in the hydrogels. Finally, we studied the correlation between the protein release characteristics of the hydrogels and their hydrolytic degradation. This is the first example that such a correlation has been attempted for a biodegradable thermogelling copolymer system. PMID:17573109

  16. Use of site-directed mutagenesis to enhance the epitope-shielding effect of covalent modification of proteins with polyethylene glycol.

    PubMed Central

    Hershfield, M S; Chaffee, S; Koro-Johnson, L; Mary, A; Smith, A A; Short, S A

    1991-01-01

    Modification by covalent attachment of polyethylene glycol (PEG) can reduce the immunogenicity and prolong the circulating life of proteins, but the utility of this approach for any protein is restricted by the number and distribution of PEG attachment sites (e.g., epsilon-amino groups of lysine residues). We have developed a strategy for introducing additional sites for PEG attachment by using site-directed mutagenesis to selectively replace arginine with lysine codons and tested it with purine nucleoside phosphorylase (PNP) from Escherichia coli, an extremely stable but immunogenic enzyme, that could potentially be used to treat an inherited deficiency of PNP. A triple mutant, RK3, possessing three Arg----Lys substitutions was constructed that increased the number of lysines per PNP subunit from 14 to 17, providing an additional 18 potential PEG attachment sites per hexameric enzyme molecule. The wild-type and RK3 enzymes had similar catalytic activity, antigenicity, and immunogenicity. After PEG modification, both enzymes retained catalytic activity, the plasma half-life of both enzymes in mice increased from approximately 4 hr to 4 days, and the binding of both enzymes by antisera raised against each unmodified enzyme was markedly diminished. However, antibody raised against wild-type PEG-PNP did not bind the PEG-RK3 enzyme. PEG-RK3 PNP was also substantially less immunogenic than wild-type PEG-PNP. Accelerated antibody-mediated clearance of PEG-PNP occurred in 2 of 12 mice treated with PEG-RK3 PNP, compared with 10 of 16 mice treated with the modified wild-type enzyme. This combined use of directed mutagenesis and PEG modification is aimed at permitting the widest choice of proteins, including products of genetic and chemical "engineering," to be used for therapy of inherited and acquired disorders. PMID:1714590

  17. Impacts of stereoregularity and stereocomplex formation on physicochemical, protein adsorption and cell adhesion behaviors of star-shaped 8-arms poly(ethylene glycol)–poly(lactide) block copolymer films

    Microsoft Academic Search

    Koji Nagahama; Yoshihiro Nishimura; Yuichi Ohya; Tatsuro Ouchi

    2007-01-01

    Biodegradable stereocomplex film exhibiting soft and stretchy character was prepared by simply blending between enantiomeric 8-arms poly(ethylene glycol)-block-poly(l-lactide) (8-arms PEG-b-PLLA) and 8-arms PEG-b-PDLA copolymers with star-shaped structure. The stereocomplex film exhibited higher Tg and PLA crystallinity than those of original copolymer films. Effects of stereoregularity and stereocomplexation on protein adsorption and L929 cells attachment\\/proliferation behaviors onto the films were analyzed

  18. Measurements of Interbilayer Forces and Protein Adsorption on Uncharged Lipid Bilayers Displaying Poly(ethylene glycol) Chains

    E-print Network

    Leckband, Deborah E.

    and the polymer grafting density independently affect protein adsorption on the coated membranes. Such studies, their use in biomedical applications is limited by their rapid clearance from circulation-24). Although macrophages do not phagocytize the modified liposomes, the grafted PEG decreases the uptake

  19. A functionalized poly(ethylene glycol)-based bioassay surface chemistry that facilitates bio-immobilization and inhibits non-specific protein, bacterial, and mammalian cell adhesion

    PubMed Central

    Harbers, Gregory M.; Emoto, Kazunori; Greef, Charles; Metzger, Steven W.; Woodward, Heather N.; Mascali, James J.; Grainger, David W.; Lochhead, Michael J.

    2008-01-01

    This paper describes a new bioassay surface chemistry that effectively inhibits non-specific biomolecular and cell binding interactions, while providing a capacity for specific immobilization of desired biomolecules. Poly(ethylene glycol) (PEG) as the primary component in nonfouling film chemistry is well-established, but the multicomponent formulation described here is unique in that it (1) is applied in a single, reproducible, solution-based coating step; (2) can be applied to diverse substrate materials without the use of special primers; and (3) is readily functionalized to provide specific attachment chemistries. Surface analysis data are presented, detailing surface roughness, polymer film thickness, and film chemistry. Protein non-specific binding assays demonstrate significant inhibition of serum, fibrinogen, and lysozyme adsorption to coated glass, indium tin oxide, and tissue culture polystyrene dishes. Inhibition of S. aureus and K. pneumoniae microbial adhesion in a microfluidic flow cell, and inhibition of fibroblast cell adhesion from serum-based cell culture is shown. Effective functionalization of the coating is demonstrated by directing fibroblast adhesion to polymer surfaces activated with an RGD peptide. Batch-to-batch reproducibility data are included. The in situ cross-linked PEG-based coating chemistry is unique in its formulation, and its surface properties are attractive for a broad range of in vitro bioassay applications. PMID:18815622

  20. Polyetheylenimine-Polyplexes of Spiegelmer NOX-A50 Directed against Intracellular High Mobility Group Protein A1 (HMGA1) Reduce Tumor Growth in Vivo*

    PubMed Central

    Maasch, Christian; Vater, Axel; Buchner, Klaus; Purschke, Werner G.; Eulberg, Dirk; Vonhoff, Stefan; Klussmann, Sven

    2010-01-01

    High mobility group A1 (HMGA1) proteins belong to a group of architectural transcription factors that are overexpressed in a range of human malignancies, including pancreatic adenocarcinoma. They promote anchorage-independent growth and epithelial-mesenchymal transition and are therefore suggested as potential therapeutic targets. Employing in vitro selection techniques against a chosen fragment of HMGA1, we have generated biostable l-RNA oligonucleotides, so-called Spiegelmers, that specifically bind HMGA1b with low nanomolar affinity. We demonstrate that the best binding Spiegelmers, NOX-A50 and NOX-f33, compete HMGA1b from binding to its natural binding partner, AT-rich double-stranded DNA. We describe a formulation method based on polyplex formation with branched polyethylenimine for efficient delivery of polyethylene glycol-modified Spiegelmers and show improved tissue distribution and persistence in mice. In a xenograft mouse study using the pancreatic cancer cell line PSN-1, subcutaneous administration of 2 mg/kg per day NOX-A50 formulated in polyplexes showed an enhanced delivery of NOX-A50 to the tumor and a significant reduction of tumor volume. Our results demonstrate that intracellular targets can be successfully addressed with a Spiegelmer using polyethylenimine-based delivery and underline the importance of HMGA1 as a therapeutic target in pancreatic cancer. PMID:20961861

  1. Physical characterizations of microemulsion systems using tocopheryl polyethylene glycol 1000 succinate (TPGS) as a surfactant for the oral delivery of protein drugs.

    PubMed

    Ke, Wen-Ting; Lin, Shyr-Yi; Ho, Hsiu-O; Sheu, Ming-Thau

    2005-02-01

    Attempts were to develop microemulsion systems using medium chain triglyceride, deionized water, and TPGS as surfactant for the oral delivery of protein drugs or poorly water-soluble drugs. Phase diagrams were constructed to elucidate the phase behavior of systems composed of Captex 300 and water with D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) as main surfactant, polysorbates (Tween 20, Tween 40, Tween 60 and Tween 80) as adjuvant surfactants, and polyethylene glycols (PEG 400 and PEG 600) and polyols (ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol and glycerin) as cosurfactants. The ratios of TPGS to Tweens, PEGs or polyols (K(m)) were set at 4/1, 2/1, 1/1, 1/2, and 1/4. The phase diagram for H(2)O/Captex 300/TPGS system reveals that when TPGS was used as a sole surfactant, it is not capable of producing isotropic solutions of water and oil over a wide range of the compositions. H(2)O/Captex 300/TPGS/Tweens systems with various K(m), regardless of the adjuvant surfactant used were capable of producing an isotropic phase. The extension of microemulsion phase and the presence and extension of the gel phase were found to be dependent on the surfactant mixture. The phase diagrams of H(2)O/Captex 300/TPGS systems using polyols as cosurfactants demonstrate that the types of polyols have a slight effect on the region of existence of the microemulsions. Comparison between the isotropic regions for the polyols system reveals that as the relative concentration of polyols increase, the isotropic region decrease in size. This decrease is towards the S(mix)-water axis indicating that as the relative concentration of polyols increases the maximum amount of oil solubilized decreases. The gel region decreased in size with the increase of polyols weight ratio. All polyols do not solubilized Captex 300 without using TPGS as surfactant. PMID:15653166

  2. Polyethylene Glycol 3350

    MedlinePLUS

    Polyethylene glycol 3350 comes as a powder to be mixed with a liquid and taken by mouth. It is usually taken once a day as needed for up to ... to produce a bowel movement.To use the powder, follow these steps: If you are using polyethylene ...

  3. Modular Poly(Ethylene Glycol) Scaffolds Provide the Ability to Decouple the Effects of Stiffness and Protein Concentration on PC12 Cells

    PubMed Central

    Scott, Rebecca A.; Elbert, Donald L.; Willits, Rebecca Kuntz

    2011-01-01

    This research focused on developing a modular poly(ethylene glycol) (PEG) scaffold, assembled from PEG microgels and collagen I, to provide an environment to decouple the chemical and mechanical cues within a three dimensional scaffold. We first characterized the microgel fabrication process, examining the size, polydispersity, swelling ratio, mesh size, and storage modulus of the polymer particles. The resulting microgels had a low polydispersity, PDI=1.08, and a diameter of ~1.6 ?m. The mesh size of the microgels, calculated from the swelling ratio, was 47.53 Å. Modular hydrogels (modugels) were then formed by compacting EDC/NHS activated microgels with PEG-4arm-amine and 0, 1, 10, or 100 ?g/mL collagen. Stiffness (G*) of the modugels was not significantly altered with the addition of collagen, allowing for modification of the chemical environment independent from the mechanical properties of the scaffold. PC12 cell aggregation increased in modugels as collagen concentrations increased and cell viability in modugels was improved over bulk PEG hydrogels. Overall, these results indicate that further exploration of modular scaffolds formed from microgels could allow for a better understanding of the relationship between the chemical and mechanical properties and cellular behavior. PMID:21787889

  4. Micromechanical modelling of polyethylene

    NASA Astrophysics Data System (ADS)

    Alvarado Contreras, Jose Andres

    2008-10-01

    The increasing use of polyethylene in diverse applications motivates the need for understanding how its molecular properties relate to the overall behaviour of the material. Although microstructure and mechanical properties of polymers have been the subject of several studies, the irreversible microstructural rearrangements occurring at large deformations are not completely understood. The purpose of this thesis is to describe how the concepts of Continuum Damage Mechanics can be applied to modelling of polyethylene materials under different loading conditions. The first part of the thesis consists of the theoretical formulation and numerical implementation of a three-dimensional micromechanical model for crystalline polyethylene. Based on the theory of shear slip on crystallographic planes, the proposed model is expressed in the framework of viscoplasticity coupled with degradation at large deformations. Earlier models aid in the interpretation of the mechanical behaviour of crystalline polyethylene under different loading conditions; however, they cannot predict the microstructural damage caused by deformation. The model, originally due to Parks and Ahzi (199o), was further developed in the light of the concept of Continuum Damage Mechanics to consider the original microstructure, the particular irreversible rearrangements, and the deformation mechanisms. Damage mechanics has been a matter of intensive research by many authors, yet it has not been introduced to the micromodelling of semicrystalline polymeric materials such as polyethylene. Regarding the material representation, the microstructure is simplified as an aggregate of randomly oriented and perfectly bonded crystals. To simulate large deformations, the new constitutive model attempts to take into account existence of intracrystalline microcracks. The second part of the work presents the theoretical formulation and numerical implementation of a three-dimensional constitutive model for the mechanical behaviour of semicrystalline polyethylene. The model proposed herein attempts to describe the deformation and degradation process in semicrystalline polyethylene following the approach of damage mechanics. Structural degradation, an important phenomenon at large deformations, has not received sufficient attention in the literature. The modifications to the constitutive equations consist essentially of introducing the concept of Continuum Damage Mechanics to describe the rupture of the intermolecular (van der Waals) bonds that hold crystals as coherent structures. In order to model the mechanical behaviour, the material morphology is simplified as a collection of inclusions comprising the crystalline and amorphous phases with their characteristic average volume fractions. In the spatial arrangement, each inclusion consists of crystalline material lying in a thin lamella attached to an amorphous layer. To consider microstructural damage, two different approaches are analyzed. The first approach assumes damage occurs only in the crystalline phase, i.e., degradation of the amorphous phase is ignored. The second approach considers the effect of damage on the mechanical behaviour of both the amorphous and crystalline phases. To illustrate the proposed constitutive formulations, the models were used to predict the responses of crystalline and semicrystalline polyethylene under uniaxial tension and simple shear. The numerical simulations were compared with experimental data previously obtained by Bartczak et al. (1994), G'Sell and Jonas (1981), G'Sell et al. (1983), Hillmansen et al. (2000), and Li et al. (2001). Our model's predictions show a consistently good agreement with the experimental results and a significant improvement with respect to the ones obtained by Parks and Ahzi (1990), Schoenfeld et al. (1995), Yang and Chen (2001), Lee et al. (i993b), Lee et al. (1993a), and Nikolov et al. (2006). The newly proposed formulations demonstrate that these types of constitutive models based on Continuum Damage Mechanics are appropriate for predicting large deformations and

  5. Methoxy-Poly(ethylene glycol) Modified Poly(L-lactide) Enhanced Cell Affinity of Human Bone Marrow Stromal Cells by the Upregulation of 1-Cadherin and Delta-2-catenin

    PubMed Central

    Mao, Xueli; Chen, Zetao; Ling, Junqi; Quan, Jingjing; Peng, Hui; Xiao, Yin

    2014-01-01

    Poly(l-lactide) (PLLA), a versatile biodegradable polymer, is one of the most commonly-used materials for tissue engineering applications. To improve cell affinity for PLLA, poly(ethylene glycol) (PEG) was used to develop diblock copolymers. Human bone marrow stromal cells (hBMSCs) were cultured on MPEG-b-PLLA copolymer films to determine the effects of modification on the attachment and proliferation of hBMSC. The mRNA expression of 84 human extracellular matrix (ECM) and adhesion molecules was analyzed using RT-qPCR to understand the underlying mechanisms. It was found that MPEG-b-PLLA copolymer films significantly improved cell adhesion, extension, and proliferation. This was found to be related to the significant upregulation of two adhesion genes, CDH1 and CTNND2, which encode 1-cadherin and delta-2-catenin, respectively, two key components for the cadherin-catenin complex. In summary, MPEG-b-PLLA copolymer surfaces improved initial cell adhesion by stimulation of adhesion molecule gene expression. PMID:24834434

  6. Solubilization of native integral membrane proteins in aqueous buffer by non-covalent chelation with monomethoxy polyethylene glycol (mPEG) polymers

    PubMed Central

    Janaratne, Thamara K.; Okach, Linda; Brock, Ansgar; Lesley, Scott A.

    2011-01-01

    Highly hydrophobic integral membrane proteins (IMPs) are typically purified in excess detergent media, often resulting in rapid inactivation and denaturation of the protein. One promising approach to solve this problem is to couple hydrophilic polymers, such as monomethoxypolyethylene glycol (mPEG) to IMPs under mild conditions in place of detergents. However, the broad application of this approach is hampered by poor reaction efficiencies, low tolerance of detergent stabilized membrane proteins to reaction conditions and a lack of proper site-specific reversible approaches. Here we have developed a straightforward, efficient and mild approach to site-specific non-covalent binding of long-chain polymers to recombinant IMPs. This method uses the hexa-histidine tag (His-Tag) often used for purification of recombinant proteins as an attachment site for mPEGs. Solubility studies performed using five different IMPs confirmed that all tested mPEG-bound IMPs were completely soluble and stable in detergent free aqueous buffer compared to their precipitated native proteins under the identical circumstances. Activity assays and circular dichroism (CD) spectroscopy confirmed the structural integrity of modified IMPs. PMID:21740061

  7. 21 CFR 177.1620 - Polyethylene, oxidized.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...the mild air oxidation of polyethylene conforming to the density...1520(c). Such oxidized polyethylene has a minimum number average...chapter may be corrected for wax, petrolatum, and mineral...not applicable to oxidized polyethylene used as provided in §§...

  8. 21 CFR 177.1620 - Polyethylene, oxidized.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...the mild air oxidation of polyethylene conforming to the density...1520(c). Such oxidized polyethylene has a minimum number average...chapter may be corrected for wax, petrolatum, and mineral...not applicable to oxidized polyethylene used as provided in §§...

  9. Biodiesel permeability in polyethylene

    NASA Astrophysics Data System (ADS)

    Richaud, Emmanuel; Fayolle, Bruno; Flaconnèche, Bruno; Verdu, Jacques

    2012-07-01

    This paper reports solubility, diffusivity and permeability data for soy and rapeseed methyl esters in polyethylene together with comparisons with methyl oleate and linoleate. The solubility was estimated on the order of 5% in weight at room temperature and increased up to more than 10% at 75°C. Diffusion kinetics obeys Fick's law and measured diffusion coefficient increased from 10-13 at room temperature to 5.10-11 m2 s-1 at 75°C. No significant difference was observed between all methyl esters under study. These data were used to discuss the reliability of predictive models for diffusion and solubility of additive type molecules into semi-crystalline thermoplastic polymers.

  10. Effects of adding protein, condensed tannins, and polyethylene glycol to diets of sheep and goats fed one-seed juniper and low quality roughage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biochemical mechanisms that limit voluntary intake of one-seed juniper by browsing ruminants are not well understood. Twelve Rambouillet ewes (78 ± 2.3 kg BW) and 12 Boer-Spanish does (54 ± 1.4 kg BW) were used in a split-plot sequence design to investigate the effects of adding protein, quebrac...

  11. Thermal features of the bovine serum albumin unfolding by polyethylene glycols

    Microsoft Academic Search

    Beatriz Farruggia; Bibiana Nerli; Hernán Di Nuci; Ruben Rigatusso; Guillermo Picó

    1999-01-01

    Albumin showed very poor affinity for polyethylene glycol molecular weight (Mw) 1000 (30 M?1) and Mw 8000 (400 M?1) (PEG 1000 and PEG 8000). Polyethylene glycol of low Mw favours the ionization of the tyrosine (TYR) residues of albumin. Such variation might be a consequence of the change in dielectric constant at the domain of the protein by PEG binding.

  12. Colonization, biofilm formation and biodegradation of polyethylene by a strain of Rhodococcus ruber.

    PubMed

    Orr, I Gilan; Hadar, Y; Sivan, A

    2004-07-01

    A two-step enrichment procedure led to the isolation of a strain of Rhodococcus ruber (C208) that utilized polyethylene films as sole carbon source. In liquid culture, C208 formed a biofilm on the polyethylene surface and degraded up to 8% (gravimetrically) of the polyolefin within 30 days of incubation. The bacterial adhesion to hydrocarbon assay and the salt aggregation test both showed that the cell-surface hydrophobicity of C208 was higher than that of three other isolates which were obtained from the same consortium but were less efficient than C208 in the degradation of polyethylene. Mineral oil, but not nonionic surfactants, enhanced the colonization of polyethylene and increased biodegradation by about 50%. Fluorescein diacetate (FDA) hydrolysis and protein content analysis were used to test the viability and biomass density of the C208 biofilm on the polyethylene, respectively. Both FDA activity and protein content of the biofilm in a medium containing mineral oil peaked 48-72 h after inoculation and then decreased sharply. This finding apparently reflected rapid utilization of the mineral oil adhering to the polyethylene. The remaining biofilm population continued to proliferate moderately and presumably played a major role in biodegradation of the polyethylene. Fourier transform infrared spectra of UV-photooxidized polyethylene incubated with C208 indicated that biodegradation was initiated by utilization of the carbonyl residues formed in the photooxidized polyethylene. PMID:15221232

  13. Reduction of Non-Specific Protein Adsorption Using Poly(ethylene) Glycol (PEG) Modified Polyacrylate Hydrogels In Immunoassays for Staphylococcal Enterotoxin B Detection

    PubMed Central

    Charles, Paul T.; Stubbs, Veronte R.; Soto, Carissa M.; Martin, Brett D.; White, Brandy J.; Taitt, Chris R.

    2009-01-01

    Three PEG molecules (PEG-methacrylate, -diacrylate and -dimethacrylate) were incorporated into galactose-based polyacrylate hydrogels and their relative abilities to reduce non-specific protein adsorption in immunoassays were determined. Highly crosslinked hydrogels containing amine-terminated functionalities were formed and used to covalently attach antibodies specific for staphylococcal enterotoxin B (SEB). Patterned arrays of immobilized antibodies in the PEG-modified hydrogels were created with a PDMS template containing micro-channels for use in sandwich immunoassays to detect SEB. Different concentrations of the toxin were applied to the hydrogel arrays, followed with a Cy3-labeled tracer antibody specific for the two toxins. Fluorescence laser scanning confocal microscopy of the tracer molecules provided both qualitative and quantitative measurements on the detection sensitivity and the reduction in non-specific binding as a result of PEG incorporation. Results showed the PEG-modified hydrogel significantly reduced non-specific protein binding with a detection limit for SEB of 1 ng/mL. Fluorescence signals showed a 10-fold decrease in the non-specific binding and a 6-fold increase in specific binding of SEB. PMID:22389622

  14. Effects of Biomass in Polyethylene or Polylactic Acid Composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies have shown that compounding Polyethylene (PE) or Polylactic acid (PLA) with a dairy-based bioplastic resulted in composites with good mechanical properties. In this study, mass ratios of a dairy-protein-based material (DBP) ranging from 0, 5, 10 and 20 wt% replaced equivalent masse...

  15. Intracellular measurement of polyethylene particles

    Microsoft Academic Search

    M. von Knoch; G. Buchhorn; F. von Knoch; G. Köster; H.-G. Willert

    2001-01-01

    A histological and histomorphometric study was carried out on pseudo-capsules retrieved from patients during revision surgery\\u000a of cementless total hip replacement. Polyethylene loading and areal polyethylene particle size in different cells of the reticuloendothelial\\u000a cell line were determined within the tissue by histomorphometry. In the reticuloendothelial cell line, foreign-body giant\\u000a cells are considered to be the result of confluence of

  16. Thiolated polyethylene oxide as a non-fouling element for nano-patterned bio-devices

    NASA Astrophysics Data System (ADS)

    Lisboa, Patrícia; Valsesia, Andrea; Colpo, Pascal; Gilliland, Douglas; Ceccone, Giacomo; Papadopoulou-Bouraoui, Andri; Rauscher, Hubert; Reniero, Fabiano; Guillou, Claude; Rossi, François

    2007-03-01

    This work describes the synthesis of a thiolated polyethylene oxide that self-assembles on gold to create a non-fouling surface. Thiolated polyethylene oxide was synthesised by reacting 16-mercaptohexadecanoic acid with polyethylene glycol mono methyl ether. The coverage of the thiolated polyethylene oxide on gold was studied by cyclic voltammetry, and the modified surfaces were characterised by X-ray photoelectron spectroscopy and ellipsometry. Protein resistance was assessed using quartz crystal microbalance. Results showed a non-fouling character produced by the thiolated polyethylene oxide. The synthesised product was used as the passivation layer on nano-patterned surfaces consisting of arrayed nano-spots, fabricated by plasma based colloidal lithography. The specific adsorption of anti-bovine serum albumin in the mercaptohexadecanoic acid spots was verified by atomic force microscopy.

  17. Degradable polyethylene: fantasy or reality.

    PubMed

    Roy, Prasun K; Hakkarainen, Minna; Varma, Indra K; Albertsson, Ann-Christine

    2011-05-15

    Plastic waste disposal is one of the serious environmental issues being tackled by our society today. Polyethylene, particularly in packaging films, has received criticism as it tends to accumulate over a period of time, leaving behind an undesirable visual footprint. Degradable polyethylene, which would enter the eco-cycle harmlessly through biodegradation would be a desirable solution to this problem. However, the "degradable polyethylene" which is presently being promoted as an environmentally friendly alternative to the nondegradable counterpart, does not seem to meet this criterion. This article reviews the state of the art on the aspect of degradability of polyethylene containing pro-oxidants, and more importantly the effect these polymers could have on the environment in the long run. On exposure to heat, light, and oxygen, these polymers disintegrate into small fragments, thereby reducing or increasing the visual presence. However, these fragments can remain in the environment for prolonged time periods. This article also outlines important questions, particularly in terms of time scale of complete degradation, environmental fate of the polymer residues, and possible accumulation of toxins, the answers to which need to be established prior to accepting these polymers as environmentally benign alternatives to their nondegradable equivalents. It appears from the existing literature that our search for biodegradable polyethylene has not yet been realized. PMID:21495645

  18. GAS TRANSMISSION IN IRRADIATED POLYETHYLENE

    Microsoft Academic Search

    Harris J. Bixler; Alan S. Michaels; Morris Salame

    1963-01-01

    The transmission of helium, nitrogen, methane, and propane was studied ; in samples of a high pressure, branched polyethylene (46% crystalline) irradiated ; to a dose in air of 10⁸ roentgens from a Co⁶° source. By using a ; time-lag apparatus the permeability, diffusion, and solubility constants were ; measured in the temperature range 0 to 55 nif- C. These

  19. Isolated Polyethylene Exchange versus Acetabular Revision for Polyethylene Wear

    PubMed Central

    Restrepo, Camilo; Ghanem, Elie; Houssock, Carrie; Austin, Mathew; Parvizi, Javad

    2008-01-01

    Polyethylene wear and osteolysis are not uncommon in THA mid- and long-term. In asymptomatic patients the dilemma faced by the orthopaedic surgeon is whether to revise the cup and risk damage to the supporting columns and even pelvic discontinuity or to perform isolated polyethylene exchange and risk a high rate of postoperative recurrent instability and dislocation that will necessitate further surgery. We retrospectively reviewed 62 patients (67 hips) who underwent revision arthroplasty for polywear and osteolysis. Thirty-six hips had isolated polyethylene exchange, while 31 had full acetabular revision. The minimum followup was 2 years (mean, 2.8 years; range, 2–5 years). Three of 36 hips with a retained cup grafted through the cup holes failed within 5 years due to acetabular loosening. One of 31 hips with full revision underwent re-revision for aseptic cup loosening at 5 months postoperatively. Although we do not recommend prophylactic revision of all cups for polywear and osteolysis, the patient may be warned of the possibility of an approximate 10% failure rate when retaining the acetabular component. We do, however, advocate cup extraction in the following situations: damage to the locking mechanism, erosion of the femoral head through the liner and into the cup damaging the metal, and a malpositioned component that may jeopardize the stability of the revision. Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18846409

  20. Radiolysis effects on polyethylene terephtalate

    NASA Astrophysics Data System (ADS)

    Zaharescu, Traian; Ciuprina, Florin

    2005-07-01

    The effects of high energy exposure of polyethylene terephtalate, the main electrical insulator for the conduction bars in alternative current generators, is presented. For comparison ?-irradiation was performed in distilled water and air at various doses, up to about 200 kGy. The dependencies of current on time for radiation processed PET sheets allow to depict the variation in the resistivity values as a measure of chemical changes in polyethylene terephtalate macromolecules. The comparison between the evolution of currents in irradiated specimens and spectral analysis bring about a light on the accumulation of radiolysis product in PET matrix. The high energy exposure of PET in air causes an increase of final value of current, while similar experiments in water produces a contrary effect. Some considerations of degradation mechanism are presented.

  1. Polyethylene multiwalled carbon nanotube composites

    Microsoft Academic Search

    Tony McNally; Petra Pötschke; Peter Halley; Michael Murphy; Darren Martin; Steven E. J. Bell; Gerard P. Brennan; Daniel Bein; Patrick Lemoine; John Paul Quinn

    2005-01-01

    Polyethylene (PE) multiwalled carbon nanotubes (MWCNTs) with weight fractions ranging from 0.1 to 10wt% were prepared by melt blending using a mini-twin screw extruder. The morphology and degree of dispersion of the MWCNTs in the PE matrix at different length scales was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and wide-angle X-ray diffraction

  2. Poly(ethylene oxide) functionalization

    DOEpatents

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  3. Single electron states in polyethylene

    SciTech Connect

    Wang, Y. [State Key Lab. of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, Shaanxi (China) [State Key Lab. of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, Shaanxi (China); School of Physics and Complex Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4 (Ireland); MacKernan, D. [School of Physics and Complex Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4 (Ireland)] [School of Physics and Complex Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4 (Ireland); Cubero, D., E-mail: dcubero@us.es, E-mail: n.quirke@imperial.ac.uk [State Key Lab. of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, Shaanxi (China); Departmento de Física Aplicada I, Universidad de Sevilla, Calle Virgen de Africa 7, 41011 Seville (Spain); Coker, D. F. [School of Physics and Complex Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4 (Ireland) [School of Physics and Complex Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4 (Ireland); Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States); Quirke, N., E-mail: dcubero@us.es, E-mail: n.quirke@imperial.ac.uk [State Key Lab. of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, Shaanxi (China); Department of Chemistry, Imperial College, London SW7 2AY (United Kingdom)

    2014-04-21

    We report computer simulations of an excess electron in various structural motifs of polyethylene at room temperature, including lamellar and interfacial regions between amorphous and lamellae, as well as nanometre-sized voids. Electronic properties such as density of states, mobility edges, and mobilities are computed on the different phases using a block Lanczos algorithm. Our results suggest that the electronic density of states for a heterogeneous material can be approximated by summing the single phase density of states weighted by their corresponding volume fractions. Additionally, a quantitative connection between the localized states of the excess electron and the local atomic structure is presented.

  4. Diffusion of limonene in polyethylene.

    PubMed

    Limm, W; Begley, T H; Lickly, T; Hentges, S G

    2006-07-01

    Diffusion coefficients of limonene in various linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) resins have been determined from sorption data using a thermogravimetric methodology. From these data, one can determine whether polymer synthesis parameters such as the choice of catalytic process or co-monomer result in substantial differences in how much food packaging additives might migrate to food. For example, LLDPE is currently manufactured using either one of two distinct catalytic processes: Ziegler-Natta (ZN) and metallocene, a single-site catalyst. ZN catalysis is a heterogeneous process that has dominated polyolefin synthesis over the last half-century. It involves a transition metal compound containing a metal-carbon bond that can handle repeated insertion of olefin units. In contrast, metallocene catalysis has fewer than 20 years of history, but has generated much interest due to its ability to produce highly stereospecific polymers at a very high yield. In addition to high stereospecificity, metallocene-catalysed polymers are significantly lower in polydispersity than traditional ZN counterparts. Absorption and desorption testing of heat-pressed films made from LLDPE and LDPE resins of varying processing parameters indicates that diffusion coefficients of limonene in these resins do not change substantially. PMID:16751151

  5. Chemical modification of lipase with polyethylene glycol

    SciTech Connect

    Baillargeon, M.W.; Sonnet, P.E.

    1986-05-01

    Proteins become soluble in selected organic solvents after covalent attachment of polyethylene glycol (PEG) to the free amino groups. A crude Candida rugosa lipase preparation was coupled with activated PEG to yield a PEG-lipase with both hydrolytic and synthetic activity in aqueous and organic media. The coupling step involved a modification of the procedure of Inada et al. To maintain lipase activity, mild reaction conditions were used: pH 7.5 or 8.0 buffer, 20 minutes reaction at room temperature. Up to 87% of the initial activity is retained in PEG-lipase. The PEG-lipase is soluble in aqueous solution, benzene and trichloroethane. The hydrolytic and synthetic activity of PEG-lipase in various organic solvents is compared to that of the native lipase; the PEG-lipase consistently shows higher specific activity, PEG-lipase also shows activity in iso-octane and cyclohexane, in which it is insoluble. The stability of PEG- and native lipase is solvent dependent.

  6. Which polyesters can mimic polyethylene?

    PubMed

    Stempfle, Florian; Ortmann, Patrick; Mecking, Stefan

    2013-01-11

    Self-metathesis of erucic acid by [(PCy(3))(?-C-C(3)H(4)N(2)Mes(2))Cl(2)Ru = CHPh] (Grubbs second- generation catalyst) followed by catalytic hydrogenation and purification via the ester yields 1,26-hexacosanedioate (>99% purity). Polyesterification with 1,26-hexacosanediol, generated from the diester, affords polyester-26,26, which features a T(m) of 114 °C (T(c) = 92 °C, ?H(m) = 160 J g(-1)). Ultralong-chain model polyesters-38,23 (T(m) = 109 °C) and -44,23 (T(m) = 111 °C), generated via multistep procedures including acyclic diene metathesis polymerization, underline that melting points of such aliphatic polyesters do not gradually increase with methylene sequence chain length. Available data suggest that to mimic linear polyethylenes thermal properties, even longer sequences, amounting to at least four times a fatty acid chain, fully incorporated in a linear fashion are required. PMID:23161497

  7. Development and optimization of breakdown strength measurements on polyethylene insulants

    Microsoft Academic Search

    R. Clavreul; J. Berdala

    1995-01-01

    In order to study the ageing phenomena of polyethylene insulants in high voltage cables, we carried out electrical measurements, for example the short time dielectric breakdown field in polyethylene. The decrease of the intrinsic dielectric rigidity of polyethylene may be correlated with ageing. That is why we optimized the short time breakdown field measurements on polyethylene samples between plane surface

  8. COMPATIBILIZATION OF RECYCLED HIGH DENSITY POLYETHYLENE (HDPE)\\/POLYETHYLENE TEREPHTHA- LATE (PET) BLENDS

    Microsoft Academic Search

    Kasama Jarukumjorn; Sukunya Chareunkvun

    2006-01-01

    Immiscible blends of recycled high density polyethylene (HDPE) and polyethylene terephthalate (PET) were compatibilized with maleic anhydride grafted polyethylene (PE-g-MA). The effect of the compatibilizer content on the mechanical, morphological, rheological, and thermal properties of recycled HDPE\\/PET blends was investigated. The blends were prepared in a twin screw extruder. Tensile strength, tensile strain at break, and impact strength improved with

  9. Foreign body reaction due to polyethylene’s wear after implantation of an interspinal segment

    Microsoft Academic Search

    Joerg Jerosch; Mohammed G. Moursi

    2008-01-01

    Different interspinous implants are used as minimal invasive intervention in the management of degenerative disorders of the\\u000a lumbar spine. We present a case with foreign body reaction due to polyethylene’s wear after a device for intervertebral assisted\\u000a motion (DIAM) implantation. We conclude that the polyethylene interspinous devices can cause biological response, therefore;\\u000a the surgeons and the companies should carefully watch

  10. Adhesion improvement of epoxy resin\\/polyethylene joints by plasma treatment of polyethylene

    Microsoft Academic Search

    D. M. Choi; C. K. Park; K. Cho; C. E. Park

    1997-01-01

    Low density polyethylene (LDPE) and high density polyethylene (HDPE) were plasma-treated with N2 and O2 plasma. The wettability and polar component of surface free energy of plasma-treated polyethylene were investigated by contact angle measurement. The concentration of functional groups formed by plasma treatment such as hydroxyl and carbonyl groups was measured using attenuated total reflection Fourier transform infrared spectroscopy (ATR

  11. Development and Characterization of Stable Glycoenzyme Conjugates 

    E-print Network

    Ritter, Dustin W.

    2014-11-07

    approach involves glycosylation site-targeted covalent attachment of poly(ethylene glycol) to glucose oxidase, which improves storage stability by 60%. The second approach builds upon the first, but subsequent modification of the poly(ethylene glycol)-modified...

  12. Bacterial oxidation of polyethylene glycol.

    PubMed Central

    Kawai, F; Kimura, T; Fukaya, M; Tani, Y; Ogata, K; Ueno, T; Fukami, H

    1978-01-01

    The metabolism of polyethylene glycol (PEG) was investigated with a synergistic, mixed culture of Flavobacterium and Pseudomonas species, which are individually unable to utilize PEGs. The PEG dehydrogenase linked with 2,6-dichlorophenolindophenol was found in the particulate fraction of sonic extracts and catalyzed the formation of a 2,4-dinitrophenylhydrazine-positive compound, possibly an an aldehyde. The enzyme has a wide substrate specificity towards PEGs: from diethylene glycol to PEG 20,000 Km values for tetraethylene glycol (TEG), PEG 400, and PEG 6,000 were 11, 1.7, and 15 mM, respectively. The metabolic products formed from TEG by intact cells were isolated and identified by combined gas chromatography-mass spectrometry as triethylene glycol and TEG-monocarboxylic acid plus small amounts of TEG-dicarboxylic acid, diethylene glycol, and ethylene glycol. From these enzymatic and analytical data, the following metabolic pathway was proposed for PEG: HO(CH2CH2O)nCH2CH2OH leads to HO(CH2CH2O)nCH2CHO leads to HO(CH2CH2O)nCH2COOH leads to HO(CH2CH2O)n-1CH2CH2OH. PMID:646355

  13. Radioprotective effect of polyethylene glycol

    SciTech Connect

    Shaeffer, J.; Schellenberg, K.A.; Seymore, C.H.; Schultheiss, T.E.; el-Mahdi, A.M.

    1986-07-01

    Polyethylene glycol of molecular weight 400 (PEG-400) had a radioprotective effect of about 20% against lethality when given ip 20 min prior to single or fractionated X-ray doses to the head and neck. Dose modification factors (DMF) based on LD50/15 values ranged from 1.14 to 1.24. A similar DMF of 1.12 based on LD50/30 values was obtained using single doses of whole-body X irradiation. Mice given head and neck irradiation had significantly reduced rectal temperatures (31.3 +/- 3.0/sup 0/C) 9 days post irradiation compared with unirradiated controls (35.4 +/- 0.6/sup 0/C). No such reduction was observed when PEG-400 was given with radiation (36.3 +/- 0.9/sup 0/C). PEG-400 also lessened, but not significantly, the frequency of shivering in irradiated animals. Histopathologic examination of the oral structures demonstrated only marginal protection by PEG-400. Estimation of the alpha/beta ratio from LD50 data on head and neck-irradiated mice yielded values of 4.4 +/- 1.9 (95% confidence limits) Gy without PEG-400 and 7.9 +/- 1.4 Gy with PEG-400. Since it is a non-thiol radioprotector, PEG-400 may be more useful when combined with more conventional thiol-containing radioprotectors.

  14. 40 CFR 721.10518 - Diethylene glycol, polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...diisocyanatoalkane, polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked (generic...diisocyanatoalkane, polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked (generic...diisocyanatoalkane, polyethylene glycol monomethyl ether- and...

  15. Polymeric compositions incorporating polyethylene glycol as a phase change material

    SciTech Connect

    Salyer, Ival O. (Dayton, OH); Griffen, Charles W. (Mason, OH)

    1989-01-01

    A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the composition is useful in making molded and/or coated materials such as flooring, tiles, wall panels and the like; paints containing polyethylene glycols or end-capped polyethylene glycols are also disclosed.

  16. Interaction of polyethylene glycol-6000 with C 4 phosphoenolpyruvate carboxylase in crude leaf extracts as well as in purified protein form from Amaranthus hypochondriacus L.: evidence for oligomerization of PEPC in vitro and in vivo

    Microsoft Academic Search

    G. Swaminath; Uday K. Avasthi; Agepati S. Raghavendra

    2008-01-01

    The interaction of phosphoenolpyruvate carboxylase (PEPC) with a compatible solute, PEG-6000, was examined using crude leaf\\u000a extracts as well as the purified protein from leaves of Amaranthus hypochondriacus, a NAD-malic enzyme type C4 plant. The inclusion in the assay medium of PEG-6000 stimulated the activity of purified PEPC by about 2.5-fold over control.\\u000a The addition of PEG during both extraction

  17. Protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins are the major structural and functional components of all cells in the body. They are macromolecules that comprise 1 or more chains of amino acids that vary in their sequence and length and are folded into specific 3-dimensional structures. The sizes and conformations of proteins, therefor...

  18. Proteins.

    ERIC Educational Resources Information Center

    Doolittle, Russell F.

    1985-01-01

    Examines proteins which give rise to structure and, by virtue of selective binding to other molecules, make genes. Binding sites, amino acids, protein evolution, and molecular paleontology are discussed. Work with encoding segments of deoxyribonucleic acid (exons) and noncoding stretches (introns) provides new information for hypotheses. (DH)

  19. Proteins

    NSDL National Science Digital Library

    Mowery, Jeanette

    Laboratory manual and supplemental resources that were developed for a college laboratory course in protein purification. The enzyme, Beta-galactosidase, is purified in two steps, with analysis and verification of results. Course materials are divided into four units: Why Proteins, Assays, The Purification Process, and Analysis and Verification. Powerpoint lectures and study guides are provided.

  20. Polymeric compositions incorporating polyethylene glycol as a phase change material

    Microsoft Academic Search

    Ival O. Salyer; Charles W. Griffen

    1989-01-01

    A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal\\/g; the composition is useful in making molded and\\/or coated materials such as flooring, tiles, wall

  1. Fabrication of Poly(ethylene glycol) Hydrogel Microstructures Using Photolithography

    E-print Network

    Revzin, Alexander

    Fabrication of Poly(ethylene glycol) Hydrogel Microstructures Using Photolithography Alexander. A solution containing an acrylated or methacrylated poly(ethylene glycol) derivative and a photoinitiator (2 of poly(ethylene glycol) (PEG) hydrogel mi- crostructures on silicon or glass substrates. PEG

  2. Protein

    MedlinePLUS

    ... for the heart. Alternatively, a cup of cooked lentils provides about 18 grams of protein and 15 ... eating approximately one daily serving of beans, chickpeas, lentils or peas can increase fullness, which may lead ...

  3. Metallic layers added by plasma on polyethylene

    Microsoft Academic Search

    G. J. Cruz; M. G. Olayo; E. Colin; J. C. Palacios; R. López; E. Granda; A. Muñoz; R. Valencia

    2009-01-01

    This work presents a study of the addition of layers composed by different metals on thin films of low-density polyethylene (PE) in order to combine the properties of both components. The process involves the immersion of PE in ionic atmospheres of O, N, Fe, Cr, Ni, and Ti to form layers and agglomerates on the surface of the polymer. As

  4. POLYETHYLENE ENCAPSULATES FOR HAZARDOUS WASTE DRUMS

    EPA Science Inventory

    This capsule report summarizes studies of the use of polyethylene (P.E.) for encapsulating drums of hazardous wastes. Flat PE sheet is welded to roto moded PE containers which forms the encapsulates. Plastic pipe welding art was used, but the prototype welding apparatus required ...

  5. Radiation Induced Conductivity in Polyethylene and Teflon

    Microsoft Academic Search

    R. A. Meyer; F. L. Bouquet; R. S. Alger

    1956-01-01

    The conductivity induced in polyethylene and Teflon by bombardment with x-rays from a 2-Mev Van de Graaff and gamma rays from Co60 has been investigated as a function of time, temperature, geometry, exposure rate, and applied electric field. Within the range of the variables studied, the observed photocurrents were directly proportional to the exposure rate and the applied electric field.

  6. Impact behaviour of polypropylene\\/polyethylene blends

    Microsoft Academic Search

    C. M Tai; Robert K. Y Li; C. N Ng

    2000-01-01

    Due to the large volume consumption of polyolefins, the treatment of the resulting solid waste is becoming a major concern. One possible utilization of the polyolefin wastes is to form blends from recycled polypropylene (PP) and polyethylene (PE). This study is a preliminary investigation on the impact fracture behaviour for the PP\\/PE blends. The impact testing method employed in this

  7. Failure prediction analysis for polyethylene flawed pipes

    Microsoft Academic Search

    Celina Bernal; Hugo López Montenegro; Patricia Frontini

    2003-01-01

    Through this paper limit load analysis and the EPRI\\/GE procedure were applied to predict instability conditions for medium density polyethylene flawed pipes. Predicted values for internally pressurized cylinders with axial cracks and cylinders with circumferential cracks under remote tension were compared to experimental results obtained from tests conducted on full scale structures. For the pipes under internal pressure, both schemes

  8. 21 CFR 177.1610 - Polyethylene, chlorinated.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...chlorination of polyethylene conforming to the density, maximum n- hexane extractable fraction, and maximum xylene soluble fraction...and has a 7.0 percent maximum extractable fraction in n -hexane at 50 °C, as determined by the method described in §...

  9. Evaluation of Paulownia elongata wood polyethylene composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  10. Gas Transport in Thermally Conditioned Linear Polyethylene

    Microsoft Academic Search

    Alan S. Michaels; Harris J. Bixler; Harvey L. Fein

    1964-01-01

    The permeability, diffusion, and solubility constants of helium, argon, and ethane have been measured in a series of linear polyethylene films which had been subjected (1) to various rates of cooling from the melt and (2) to subsequent annealing near the melting temperature. While solubility constants of argon and ethane showed the normal variation with amorphous content of the polymer

  11. Fast crystallization of poly(ethylene terephthalate)

    Microsoft Academic Search

    Mingxin Ye; Xiaohui Wang; Weishi Huang; Jiulan Hu; Haishan Bu

    1996-01-01

    The crystallization of poly(ethylene terephthalate) (PET) was studied in the presence of nucleating agents and promoters. The effect of both by themselves and in concert was investigated using differential scanning calorimetry. The aim of this work is to find conditions of fast crystallization of PET. Sodium benzoate(SB) and Surlyn® (S) substantially increase the crystallization rate of PET at higher temperature

  12. Thermally sprayable polyethylene coatings for marine environment

    Microsoft Academic Search

    S. K. Singh; S. P. Tambe; V. S. Raja; Dhirendra Kumar

    2007-01-01

    Application of organic coatings is one of the methods for protection of mild steel against corrosion. In the present work, low-density polyethylene (LDPE) has been used as binder for development of anticorrosive coating. Since non-polar characteristics of LDPE make its adhesion poor to most substrates, polar groups have been introduced in LDPE by grafting maleic acid (MAc) using reactive extrusion

  13. Ultrasonically enhanced persulfate oxidation of polyethylene surfaces

    Microsoft Academic Search

    Fiona Keen

    1996-01-01

    The ultrasonically enhanced oxidation of polyethylene surfaces by potassium and ammonium persulfates is described. The use of ultrasound allows significant levels of surface modification to be achieved using these oxidizing agents under mild conditions. Changes in the water contact angle and attenuated total reflection infra-red spectra were used to follow the changes in surface chemistry. Variation of conditions such as

  14. Computational method for analysis of polyethylene biodegradation

    NASA Astrophysics Data System (ADS)

    Watanabe, Masaji; Kawai, Fusako; Shibata, Masaru; Yokoyama, Shigeo; Sudate, Yasuhiro

    2003-12-01

    In a previous study concerning the biodegradation of polyethylene, we proposed a mathematical model based on two primary factors: the direct consumption or absorption of small molecules and the successive weight loss of large molecules due to ?-oxidation. Our model is an initial value problem consisting of a differential equation whose independent variable is time. Its unknown variable represents the total weight of all the polyethylene molecules that belong to a molecular-weight class specified by a parameter. In this paper, we describe a numerical technique to introduce experimental results into analysis of our model. We first establish its mathematical foundation in order to guarantee its validity, by showing that the initial value problem associated with the differential equation has a unique solution. Our computational technique is based on a linear system of differential equations derived from the original problem. We introduce some numerical results to illustrate our technique as a practical application of the linear approximation. In particular, we show how to solve the inverse problem to determine the consumption rate and the ?-oxidation rate numerically, and illustrate our numerical technique by analyzing the GPC patterns of polyethylene wax obtained before and after 5 weeks cultivation of a fungus, Aspergillus sp. AK-3. A numerical simulation based on these degradation rates confirms that the primary factors of the polyethylene biodegradation posed in modeling are indeed appropriate.

  15. PEG-proteins: Reaction engineering and separation issues

    Microsoft Academic Search

    Conan J. Fee; James M. Van Alstine

    2006-01-01

    Poly(ethylene glycol)-conjugated (or PEGylated) proteins are an increasingly important class of therapeutic proteins that offer improved in vivo circulation half lives over their corresponding native forms. Their production involves covalent attachment of one or more poly(ethylene glycol) molecules to a native protein, followed by purification. Because of the extremely high costs involved in producing native therapeutic proteins it is important

  16. Structure and properties of compatibilized recycled poly(ethylene terephthalate)\\/linear low density polyethylene blends

    Microsoft Academic Search

    Hongsheng Zhang; Weihong Guo; Yingbo Yu; Binyao Li; Chifei Wu

    2007-01-01

    Blends of recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) were compatibilized with poly(styrene-ethylene\\/butyldiene-styrene) (SEBS) and maleic anhydride-grafted poly(styrene-ethylene\\/butyldiene-styrene) (SEBS-g-MA). Effects of compatilizer were evaluated systematically by study of mechanical, thermal and morphology properties together with crystallization behavior of PET. Tensile properties of the blends were improved effectively by the addition of 10wt% SEBS-g-MA, elongation at break and

  17. Poly(ethylene terephthalate)\\/polyethylene composite based on in-situ microfiber formation

    Microsoft Academic Search

    Z. M. Li; M. B. Yang; R. Huang; W. Yang; J. M. Feng

    2002-01-01

    Poly(ethylene terephthalate) (PET) microfiber was in-situ formed by compounding PET with polyethylene (PE) through a single screw extruder of a Haake rheometer system, where a rod die with comparatively smaller diameter (2.1 mm) was used, and the extrudate was drawn in a certain drawing ratio (3.1:1) and quickly cooled in cold water. Subsequently, the in-situ PET\\/PE composite was injection molded into

  18. Molecular Dynamics Studies of Polyethylene Oxide and Polyethylene Glycol: Hydrodynamic Radius and Shape Anisotropy

    Microsoft Academic Search

    Hwankyu Lee; Richard M. Venable; Alexander D. MacKerell; Richard W. Pastor

    2008-01-01

    A revision (C35r) to the CHARMM ether force field is shown to reproduce experimentally observed conformational populations of dimethoxyethane. Molecular dynamics simulations of 9, 18, 27, and 36-mers of polyethylene oxide (PEO) and 27-mers of polyethylene glycol (PEG) in water based on C35r yield a persistence length ?=3.7Å, in quantitative agreement with experimentally obtained values of 3.7Å for PEO and

  19. The "New Polyethylene Glycol Dilemma": Polyethylene Glycol Impurities and Their Paradox Role in mAb Crystallization.

    PubMed

    Hildebrandt, Christian; Joos, Lea; Saedler, Rainer; Winter, Gerhard

    2015-06-01

    Polyethylene glycols (PEG) represent the most successful and frequently applied class of excipients used for protein crystallization. PEG auto-oxidation and formation of impurities such as peroxides and formaldehydes that foster protein drug degradation is known. However, their effect on mAb crystallization has not been studied in detail before. During the present study, a model IgG1 antibody (mAb1) was crystallized in PEG solutions. Aggregate formation was observed during crystallization and storage that was ascribed to PEG degradation products. Reduction of peroxide and formaldehyde levels prior to crystallization by vacuum and freeze-drying was investigated for its effect on protein degradation. Vacuum drying was superior in removal of peroxides but inferior in reducing formaldehyde residues. Consequently, double purification allowed extensive removal of both impurities. Applying of purified PEG led to 50% lower aggregate fractions. Surprisingly, PEG double purification or addition of methionine prior to crystallization prevented crystal formation. With increased PEG concentration or spiking with peroxides and formaldehydes, crystal formation could be recovered again. With these results, we demonstrate that minimum amounts of oxidizing impurities and thus in consequence chemically altered proteins are vital to initiate mAb1 crystallization. The present study calls PEG as good precipitant for therapeutic biopharmaceuticals into question. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1938-1945, 2015. PMID:25808186

  20. Controlling the Physical Behavior and Biological Performance of Liposome Formulations Through Use of Surface Grafted Poly(ethylene Glycol)

    Microsoft Academic Search

    C. Allen; N. Dos Santos; R. Gallagher; G. N. C. Chiu; Y. Shu; W. M. Li; S. A. Johnstone; A. S. Janoff; L. D. Mayer; M. S. Webb; M. B. Bally

    2002-01-01

    The presence of poly(ethylene glycol) (PEG) at the surface of a liposomal carrier has been clearly shown to extend the circulation lifetime of the vehicle. To this point, the extended circulation lifetime that the polymer affords has been attributed to the reduction or prevention of protein adsorption. However, there is little evidence that the presence of PEG at the surface

  1. Effect of Poly(ethylene glycol) on Separations by Cellulose Acetate\\/poly(ether imide) Blend Membranes

    Microsoft Academic Search

    A. Nagendran; D. Lawrence Arockiasamy; D. Mohan

    2007-01-01

    Ultrafiltration membranes are largely being applied for macromolecular and heavy metal ion separations from aqueous streams. In this study, cellulose acetate (CA) and polyetherimide (PEI) based ultrafiltration blend membranes prepared in the absence and presence of poly(ethylene glycol) 600 (PEG 600) in various compositions were subjected to the separation of macromolecular proteins such as bovine serum albumin (BSA), egg albumin

  2. Electric field induced switching of poly,,ethylene glycol... terminated self-assembled monolayers: A parallel molecular dynamics simulation

    E-print Network

    Southern California, University of

    Electric field induced switching of poly,,ethylene glycol... terminated self-assembled monolayers alkanethiol self-assembled monolayer SAM on gold have been studied using parallel molecular dynamics method protein adsorption.4 Recently poly ethylene glycol PEG termi- nated self-assembled monolayers SAM have

  3. Mechanism of the positive effect of poly(ethylene glycol) addition in enzymatic hydrolysis of steam pretreated lignocelluloses

    Microsoft Academic Search

    Bálint Sipos; Mátyás Szilágyi; Zoltán Sebestyén; Raffaella Perazzini; Dóra Dienes; Emma Jakab; Claudia Crestini; Kati Réczey

    2011-01-01

    The efficiency of enzymatic hydrolysis of lignocellulses can be increased by addition of surfactants and polymers, such as poly(ethylene glycol) (PEG). The effect of PEG addition on the cellulase adsorption was tested on various steam pretreated lignocellulose substrates (spruce, willow, hemp, corn stover, wheat straw, sweet sorghum bagasse). A positive effect of PEG addition was observed, as protein adsorption has

  4. Modifications to a carbon paste glucose-sensing enzyme electrode and a reduction in the electrochemical interference from L-ascorbate

    Microsoft Academic Search

    Soichi Yabuki; Fumio Mizutani

    1995-01-01

    A glucose-sensing enzyme electrode was prepared by incorporating polyethylene glycol-modified glucose oxidase, horseradish peroxidase and 1,1?-dimethylferrocene into a carbon paste. The modification of glucose oxidase with polyethylene glycol was effective for increasing the enzyme activity in the carbon paste owing to the enhanced affinity of the polyethylene glycol-modified enzyme for the hydrophobic carbon paste matrix. In contrast, however, the enzyme

  5. Greater osteoblast and endothelial cell adhesion on nanostructured polyethylene and titanium

    PubMed Central

    Raimondo, Theresa; Puckett, Sabrina; Webster, Thomas J

    2010-01-01

    Mostly due to desirable mechanical properties (such as high durability and low wear), certain synthetic polymers (such as polyethylene) and metals (such as titanium) have found numerous applications in the medical device arena from orthopedics to the vasculature, yet frequently, they do not proactively encourage desirable cell responses. In an effort to improve the efficacy of such traditional materials for various implant applications, this study used electron beam evaporation to create nanostructured surface features that mimic those of natural tissue on polyethylene and titanium. For other materials, it has been shown that the creation of nanorough surfaces increases surface energy leading to greater select protein (such as vitronectin and fibronectin) interactions to increase specific cell adhesion. Here, osteoblast (bone forming cells) and endothelial cell (cells that line the vasculature) adhesion was determined on nanostructured compared to conventional, nano-smooth polyethylene and titanium. Results demonstrated that nanorough surfaces created by electron beam evaporation increased the adhesion of both cells markedly better than conventional smooth surfaces. In summary, this study provided evidence that electron beam evaporation can modify implant surfaces (specifically, polyethylene and titanium) to have nanostructured surface features to improve osteoblast and endothelial cell adhesion. Since the adhesion of anchorage dependent cells (such as osteoblasts and endothelial cells) is a prerequisite for their long-term functions, this study suggests that electron beam evaporation should be further studied for improving materials for various biomedical applications. PMID:20856840

  6. Compatibilization of polyethylene\\/aluminum hydroxide (PE\\/ATH) and polyethylene\\/magnesium hydroxide (PE\\/MH) composites with functionalized polyethylenes

    Microsoft Academic Search

    U Hippi; J Mattila; M Korhonen; J Seppälä

    2003-01-01

    Study was made of the compatibilization of polyethylene\\/aluminum hydroxide (PE\\/ATH) and polyethylene\\/magnesium hydroxide (PE\\/MH) composites with composition 60\\/40wt%. Compatibilizers were hydroxyl or carboxylic acid functionalized copolymers prepared in our laboratory with metallocene catalysts and commercial butyl acrylate, maleic anhydride, epoxy, and acrylic acid functionalized polyethylenes. Comparison was made with stearic acid treatment of the composites. The effect of polymeric compatibilizers

  7. High-pressure vibrational properties of polyethylene

    Microsoft Academic Search

    Luca Fontana; Mario Santoro; Roberto Bini; Diep Q. Vinh; Sandro Scandolo

    2010-01-01

    The pressure evolution of the vibrational spectrum of polyethylene was investigated up to 50 GPa along different isotherms by Fourier-transform infrared and Raman spectroscopy and at 0 K by density-functional theory calculations. The infrared data allow for the detection of the orthorhombic Pnam to monoclinic P21\\/m phase transition which is characterized by a strong hysteresis both on compression and decompression

  8. Cyclic Behavior of High Density Polyethylene (HDPE)

    NASA Astrophysics Data System (ADS)

    Dusunceli, Necmi; Aydemir, Bulent; Terzi, Niyazi U.

    2010-06-01

    This article presents the mechanical behavior of high density polyethylene (HDPE). Samples were prepared by extracting extruded HDPE pipe. Cyclic and strain rate jump behavior of HDPE were studied under uniaxial tensile loading conditions. The strain jump tests indicated that mechanical behavior of HDPE has deformation memory. Further, it was found that increasing cycle number on cyclic loading test increased strain accumulation amount and HDPE exhibited ratcheting behavior at on loading-unloading-reloading at constant stress level.

  9. Evaluation of degradability of biodegradable polyethylene (PE)

    Microsoft Academic Search

    Ignacy Jakubowicz

    2003-01-01

    Thermo-oxidative degradation of polyethylene films containing pro-oxidant has been studied at three temperatures that normally occur during composting conditions. Besides temperature, oxygen concentration was also varied. After various periods, the effects of thermo-oxidation were evaluated by measurements of molecular mass of the materials. It is shown that while temperature is the most important factor influencing the rate of thermo-oxidative degradation

  10. Solution of Gases in Polyethylene Terephthalate

    Microsoft Academic Search

    Alan S. Michaels; Wolf R. Vieth; James A. Barrie

    1963-01-01

    The solubilities of helium, nitrogen, oxygen, argon, methane, carbon dioxide, and ethane in glassy amorphous and crystalline polyethylene terephthalate have been studied by time-lag and?or static sorption methods. Solubilities of all the gases but ethane were also determined in the rubbery crystalline polymer. The only deviations from Henry's law were displayed by ethane at 25°C and carbon dioxide at 25°

  11. Deformation of spherulitic polyethylene thin films

    Microsoft Academic Search

    M. F. BUTLER; A. M. DONALD

    1997-01-01

    Thin spherulitic films of polyethylene (PE), made by casting from xylene solution, were deformed on copper grids and their\\u000a deformation microstructure studied using optical and transmission electron microscopy. A range of molecular weights, branch\\u000a amounts and types, and thermal histories was used to study the influence of sample microstructure on the deformation behaviour.\\u000a The spherulite boundaries were the weakest regions

  12. Polyethylene bags and solar ultraviolet radiation

    SciTech Connect

    Holm-Hansen, O.; Helbling, E.W. (Univ. of California, San Diego, La Jolla (United States))

    1993-01-22

    This technical comment questions the use of polyethylene bags to collect and store samples in a previously reported study on the effects of solar ultraviolet radiation on natural phytoplankton assemblages in Antarctic waters. A significant difference in the photosynthetic rates was noted for samples in glassware as opposed to bags, although the overall conclusions remained similar. A response by the original authors is included. 1 tab.

  13. Thermally Active Fabrics Containing Polyethylene Glycols

    Microsoft Academic Search

    Joseph S. Bruno; Tyrone L. Vigo

    1987-01-01

    Polyethylene glycols (PEG) of low molecular weight (300-1,000) can be durably bound to cotton, cotton-polyester blends, and most commercially available fabrics (such as wool, acrylic and nylon) by a pad-dry-cure method utilizing a polyfunc tional crosslinking agent. The extent to which the PEGs react with and are bonded to the fabrics is dependent on the molecular weight of the polymer,

  14. Pegylation enhances protein stability during encapsulation in PLGA microspheres

    Microsoft Academic Search

    Manish Diwan; Tae Gwan Park

    2001-01-01

    During encapsulation of proteins in biodegradable microspheres, a significant amount of the protein reportedly undergoes denaturation to form irreversible insoluble aggregates. Incomplete in vitro release of proteins from the microspheres is a common observation. An attempt was made to overcome this problem by pegylation of the protein to be encapsulated. Lysozyme, a model protein, was conjugated with methoxy polyethylene glycol

  15. Polyethylene in knee arthroplasty: A review.

    PubMed

    Chakrabarty, Gautam; Vashishtha, Mayank; Leeder, Daniel

    2015-06-01

    Polyethylene (PE) has been used extensively in knee arthroplasty since the mid 20th century. Progress in material manufacturing and processing has led to newer polyethylenes over last few decades with different material properties. It has been established that PE wear in knee arthroplasty causes particle induced osteolysis which is the main reason for late failure and requires revision surgery. Although there are various causes of wear, the properties of PE have long been a matter of investigation as a contributory factor. The advent of newer highly cross linked PE has been shown to improve wear rates in hip arthroplasty but the benefits have not been shown to be of the same degree in knee arthroplasty. The laboratory and clinical studies so far are limited and slightly conflicting in their conclusions. The risks of using highly cross linked PE in knee arthroplasty include tibial post fracture, disruption of locking mechanism, liner fracture which can lead to increased wear and osteolysis. The current evidence suggests that highly cross linked polyethylenes should be used with caution and only considered in younger active patients. The results of a recently completed randomized trial to compare the conventional with high molecular weight PE in knee arthroplasty are awaited. PMID:25983517

  16. The sequential dissociation of protonated polyethylene glycols.

    PubMed

    Hester, Thomas H; McCraney, Kendra K; Castillo, Daniel E; Goebbert, Daniel J

    2013-04-01

    Early investigations of protonated polyethylene glycol fragmentation suggested the dissociation mechanism includes both direct and sequential processes. Experiments designed to study the proposed mechanisms of sequential dissociation are absent from the literature. In order to obtain additional experimental details about the fragmentation reactions, the dissociation of protonated polyethylene glycol was studied by energy-dependent collision-induced dissociation (CID). Key fragment ions were separated by mass differences corresponding to the loss of single monomer units. Several fragment ions were also generated by in-source fragmentation and studied by CID. These experiments indicate the primary ions undergo sequential dissociation by the loss of either one or two monomer units. The results suggest that at least two different mechanisms must be considered to explain the sequential dissociation of protonated polyethylene glycols. The reaction involving the elimination of two subunits suggests the loss of a six-membered 1,4-dioxane product, while the elimination of a single subunit involves the loss of acetaldehyde by a 1,2-hydride shift rearrangement. PMID:23584939

  17. Polyethylene solidification of low-level wastes

    SciTech Connect

    Kalb, P.D.; Colombo, P.

    1985-02-01

    This topical report describes the results of an investigation on the solidification of low-level radioactive waste in polyethylene. Waste streams selected for this study included those which result from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those which remain problematic for solidification using contemporary agents (ion exchange resins). Four types of commercially available low-density polyethylenes were employed which encompass a range of processing and property characteristics. Process development studies were conducted to ascertain optimal process control parameters for successful solidification. Maximum waste loadings were determined for each waste and polyethylene type. Property evaluation testing was performed on laboratory-scale specimens to assess the potential behavior of actual waste forms in a disposal environment. Waste form property tests included water immersion, deformation under compressive load, thermal cycling and radionuclide leaching. Recommended waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash, and 30 wt % ion exchange resins, which are based on process control and waste form performance considerations are reported. 37 refs., 33 figs., 22 tabs.

  18. Extensional Flow Induced Crystallization of Polyethylene

    NASA Astrophysics Data System (ADS)

    Nicholson, David; Locker, C. Rebecca; Tsou, Andy; Rutledge, Gregory

    2014-03-01

    The majority of manufactured polyethylene is used in films mostly through the blown film fabrication process where extensional flow induced crystallization is a critical component in affecting the development of crystalline morphology and amorphous topology. In order to optimize the blown film performance, it is critical to understand the mechanism of extensional flow induced crystallization of polyethylene. Model high density polyethylene with a Mn of 20,000 g/mol and a PDI (polydispersity) of 2 and lower were synthesized by organometallic catalysts. Extensional flow induced crystallization of these materials was measured using the SER (Sentmanat Extensional Rheometer) either at a given rate with varying temperatures or vice versa. A continuum model was applied to analyze the flow induced crystallization data. All samples after extensional flow were quenched in ice water and the resulting morphology was characterized using SAXS and WAXS. The extensional rate was found to be effective in modifying morphology whereas the temperature was not; neither temperature nor strain rate affected the final film crystallinity. With an increase in extensional rate, crystallites became thinner and narrower with potentially higher connectivity which could lead to higher toughness.

  19. Reactive compatibilization and properties of recycled poly(ethylene terephthalate)\\/polyethylene blends

    Microsoft Academic Search

    Mariano Pracella; Federico Pazzagli; Andrzej Galeski

    2002-01-01

    Summary  \\u000a Blends of recycled poly(ethylene terephthalate) (R-PET) and high-density polyethylene (R-PE), obtained from post-consumer\\u000a packaging materials, were prepared both by melt mixing and extrusion processes and compatibilized by addition of various copolymers\\u000a containing functional reactive groups, such as maleic anhydride, acrylic acid and glycidyl methacrylate. The effect of the\\u000a type and concentration of compatibilizer, as well as the mixing conditions,

  20. The Measurement of Creep in Ultrahigh Molecular Weight Polyethylene

    Microsoft Academic Search

    Daniel M. Estok; Charles R. Bragdon; Gordon R. Plank; Anna Huang; Orhun K. Muratoglu; William H. Harris

    2005-01-01

    Quantification of creep of highly cross-linked polyethylene would enable separation of creep from wear when evaluating femoral head penetration into polyethylene. We compared creep magnitude of a highly cross-linked versus conventional polyethylene in the laboratory. Twelve acetabular liners of each material were tested, 6 of which had a 32-mm inner diameter (ID) and 6 had 28-mm ID. Creep was measured

  1. Polyethylene waste form: Evaluation of explosion and fire hazards

    Microsoft Academic Search

    A. Block-Bolten; D. Olson; P. A. Persson; F. Sandstrom

    1991-01-01

    A Proposed polyethylene waste form consists of a hot-extruded, non-porous mix of equal weights of polyethylene and granular sodium nitrate, slightly contaminated with heavy metal salts. The experiments and theoretical analysis detailed in this report were done to evaluate the risks for self-accelerating thermal decomposition, explosion, and detonation of polyethylene mixed with sodium nitrate. The study included the proposed waste

  2. Phase structure and properties of poly(ethylene terephthalate)\\/high-density polyethylene based on recycled materials

    Microsoft Academic Search

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

    2009-01-01

    Blends based on recycled high density polyethylene (R-HDPE) and recycled poly(ethylene tereph- thalate) (R-PET) were made through reactive extrusion. The effects of maleated polyethylene (PE-g-MA), triblock copolymer of styrene and ethylene\\/butylene (SEBS), and 4,40-methylenedi(phenyl isocyanate) (MDI) on blend prop- erties were studied. The 2% PE-g-MA improved the com- patibility of R-HDPE and R-PET in all blends toughened by SEBS. For

  3. 76 FR 9745 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-22

    ...2010, the Department determined that amorphous polyethylene terephthalate (APET) film...Strip from Taiwan: Final Scope Ruling on Amorphous Polyethylene Terephthalate Film...Republic of China: Final Scope Ruling on Amorphous Polyethylene Terephthalate Sheet,...

  4. 40 CFR 721.3900 - Alkyl polyethylene glycol phosphate, potassium salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...polyethylene glycol phosphate, potassium salt. 721.3900 Section 721.3900 ...polyethylene glycol phosphate, potassium salt. (a) Chemical substances and significant...polyethylene glycol phosphate, potassium salt (P-90-481), is subject to...

  5. 40 CFR 721.10546 - Pentenylated polyethylene glycol sulfate salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Pentenylated polyethylene glycol sulfate salt (generic). 721.10546 Section 721...Pentenylated polyethylene glycol sulfate salt (generic). (a) Chemical substance...pentenylated polyethylene glycol sulfate salt (PMN P-04-340) is subject to...

  6. 75 FR 69400 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-12

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip From India: Extension...duty order on polyethylene terephthalate film, sheet and strip from India for the period...2009. See Polyethylene Terephthalate Film, Sheet and Strip from India:...

  7. 75 FR 80457 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ...A-533-824] Polyethylene Terephthalate Film, Sheet and Strip From India: Extension...duty order on polyethylene terephthalate film, sheet and strip from India for the period...2009. See Polyethylene Terephthalate Film, Sheet and Strip from India:...

  8. 75 FR 79336 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-20

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip From India: Extension...duty order on polyethylene terephthalate film, sheet and strip from India for the period...2009. See Polyethylene Terephthalate Film, Sheet and Strip from India:...

  9. 75 FR 65450 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-25

    ...A-533-824] Polyethylene Terephthalate Film, Sheet and Strip From India: Extension...duty order on polyethylene terephthalate film, sheet and strip from India for the period...2009. See Polyethylene Terephthalate Film, Sheet and Strip from India:...

  10. 77 FR 14501 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-12

    ...A-533-824] Polyethylene Terephthalate Film, Sheet and Strip From India: Extension...AD) order on polyethylene terephthalate film, sheet and strip from India covering the...2011. See Polyethylene Terephthalate Film, Sheet and Strip From India:...

  11. 21 CFR 870.3470 - Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...intracardiac patch or pledget made of polypropylene, polyethylene terephthalate,...

  12. 21 CFR 870.3470 - Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...intracardiac patch or pledget made of polypropylene, polyethylene terephthalate,...

  13. 21 CFR 870.3470 - Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...intracardiac patch or pledget made of polypropylene, polyethylene terephthalate,...

  14. 75 FR 36679 - Polyethylene Retail Carrier Bags From China, Malaysia, and Thailand; Determinations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-28

    ...Polyethylene Retail Carrier Bags From China, Malaysia, and Thailand; Determinations On the...polyethylene retail carrier bags from China, Malaysia, and Thailand would be likely to lead...Polyethylene Retail Carrier Bags from China, Malaysia, and Thailand: Investigation...

  15. Electronic conduction through single crystals of polyethylene

    E-print Network

    Samson, Gerald Maurice

    1966-01-01

    ELECTRORIC CO:iC' CTIOE?TEROUCH Sl". , GLE C OISTf~S OF POL" IZLELE A Thesis Gerald Mauri co Samson Submitted to the Graduate College of' the Texas AcM University in partial Wlfillment of' the requirements f' or the degree of' MASTER OF SCIENCE... talc o Polyot! ylone . -y, i'oo Gerald !':cur"' co Samson Directed by: Zr. Joe S. The predominant conduction mechani m through single cryo' mls op polyethylene is shown to be Schott!cy ( hernal) oui "sion . or tompora- o tu. es - bove 0 C. . "or...

  16. Synthesis and elaboration of polyethylene surfaces modified via anionic grafting chemistry

    E-print Network

    Bandella, Ashok Krishangopal

    1996-01-01

    POLYETHYLENE FILMS. . 31 Synthesis and Characterization of Terminally Functionalized Polyethylene Oligomers. . Entrapment Functionalization of Macroinitiators into Virgin Polyethylene and Grafting of tert-butyl Acrylate to the Product Surface... General Pracedure for Grafftng tert-butyl Acrylate on Pyrene Entrapped Polyethylene Film (11). . 76 Page Hydrolysis of I I to Form a Poly(Acrylic Acid) Grafted Polyethylene Film (12) . . 78 Preparation of Polyethylene-b-Poly(rerr-butyl Acrylate) (14...

  17. Fracture mechanics analysis of slow crack growth in polyethylene 

    E-print Network

    Self, Robert Alan

    1997-01-01

    Slow crack growth in polyethylene is often the limiting factor in long-term service of plastic pipe or other structural applications. A new test method and analysis method was developed to study slow crack growth in polyethylene. Two high density...

  18. Preventing oxidation of iron sulfide minerals by polyethylene polyamines

    E-print Network

    Belzile, Nelson

    Preventing oxidation of iron sulfide minerals by polyethylene polyamines Yu-Wei Chen a,*, Yuerong provide an effective protective layer for sulfidic ores and significantly reduce the penetration an important catalyzing role in the oxidation of sulfides and acid mine generation. Polyethylene polyamines

  19. Water treeing in binary linear polyethylene blends: the mechanical aspect

    Microsoft Academic Search

    A. Bulinski; S. Bamji; J. Densleyl; A. Gustafsson; U. W. Gedde

    1994-01-01

    Water treeing tests were performed on low density polyethylene (LDPE) and four different binary blends of sharp linear polyethylene (LPE) fractions (Mw=2500 and 76000), which were either quenched in air from the melt or isothermally crystallised at 123°C. Although the morphology and initial mechanical properties of the materials tested were significantly different, the vented tree growth characteristics were similar for

  20. Original article Effects of polyethylene glycol in concentrate or feed

    E-print Network

    Boyer, Edmond

    Original article Effects of polyethylene glycol in concentrate or feed blocks on carcass -- The influence of concentrate or feed blocks with or without Polyethylene glycol (PEG, molecular weight 4000 groups had free access to urea-containing feed blocks with (BUPEG) or without (BU) PEG. One other

  1. Adsorption of Polypropylene and Polyethylene on Liquid Chromatographic

    E-print Network

    Li, Jing

    Adsorption of Polypropylene and Polyethylene on Liquid Chromatographic Column Packings T. Macko1 tested as column packings for adsorption of isotactic polypropylene and linear polyethylene from dilute been used as the column packing. Polypropylene was fully retained in another type of zeolite with pores

  2. SECURING CONTAINERIZED HAZARDOUS WASTES WITH POLYETHYLENE RESIN AND FIBERGLASS ENCAPSULATES

    EPA Science Inventory

    This study investigates the fabrication and use of polyethylene resin and fiberglass to encapsulate and secure containerized hazardous wastes. Laboratory-scale encapsulates of composite structure were made from powdered, high-density polyethylene (HDPE) and epoxy-resin-wetted fib...

  3. Polyethylene magnetic nanoparticle: a new magnetic material for biomedical applications

    NASA Astrophysics Data System (ADS)

    Chatterjee, Jhunu; Haik, Yousef; Chen, Ching-Jen

    2002-05-01

    Polyethylene magnetic nanoparticles were synthesized by nonsolvent and temperature induced crystallization along with ultrasonication. Low molecular weight polyethylene wax and maghemite were used for forming the composite particles. These particles were further coated with avidin. The nanoparticles are characterized using STEM, AFM and SQUID. Nanomagnetic particles were found to have two distinct morphologies and have superparamagnetic properties.

  4. Nanostructurization and thermal properties of polyethylenes' welds.

    PubMed

    Galchun, Anatoliy; Korab, Nikolay; Kondratenko, Volodymyr; Demchenko, Valeriy; Shadrin, Andriy; Anistratenko, Vitaliy; Iurzhenko, Maksym

    2015-01-01

    As it is known, polyethylene (PE) is one of the common materials in the modern world, and PE products take the major share on industrial and trade markets. For example, various types of technical PE like PE-63, PE-80, and PE-100 have wide industrial applications, i.e., in construction, for pipeline systems etc. A rapid development of plastics industry outstrips detailed investigation of welding processes and welds' formation mechanism, so they remain unexplored. There is still no final answer to the question how weld's microstructure forms. Such conditions limit our way to the understanding of the problem and, respectively, prevent scientific approaches to the welding of more complicated (from chemical point of view) types of polymers than PE. Taking into account state-of-the-art, the article presents results of complex studies of PE weld, its structure, thermophysical and operational characteristics, analysis of these results, and basing on that some hypotheses of welded joint and weld structure formation. It is shown that welding of dissimilar types of polyethylene, like PE-80 and PE-100, leads to the formation of better-ordered crystallites, restructuring the crystalline phase, and amorphous areas with internal stresses in the welding zone. PMID:25897302

  5. Degradation of Green Polyethylene by Pleurotus ostreatus

    PubMed Central

    da Luz, José Maria Rodrigues; Paes, Sirlaine Albino; Ribeiro, Karla Veloso Gonçalves; Mendes, Igor Rodrigues; Kasuya, Maria Catarina Megumi

    2015-01-01

    We studied the biodegradation of green polyethylene (GP) by Pleurotus ostreatus. The GP was developed from renewable raw materials to help to reduce the emissions of greenhouse gases. However, little information regarding the biodegradation of GP discarded in the environment is available. P. ostreatus is a lignocellulolytic fungus that has been used in bioremediation processes for agroindustrial residues, pollutants, and recalcitrant compounds. Recently, we showed the potential of this fungus to degrade oxo-biodegradable polyethylene. GP plastic bags were exposed to sunlight for up to 120 days to induce the initial photodegradation of the polymers. After this period, no cracks, pits, or new functional groups in the structure of GP were observed. Fragments of these bags were used as the substrate for the growth of P. ostreatus. After 30 d of incubation, physical and chemical alterations in the structure of GP were observed. We conclude that the exposure of GP to sunlight and its subsequent incubation in the presence of P. ostreatus can decrease the half-life of GP and facilitate the mineralization of these polymers. PMID:26076188

  6. Self-Healing of Polyethylene Oxide

    NASA Astrophysics Data System (ADS)

    Chipara, Dorina Magdalena; Flores, Maritza; Puente, Nancy; Lozano, Karen

    2011-03-01

    Autonomic self-healing is expected to enhance the lifetime of polymeric materials, resins, and composites subjected to long term mechanical stresses. The self-healing process is initiated by the rupture of some polyurea-formaldehyde microcapsules filled with monomer. The self-healing polymer is actually a compound containing microcapsules filled with monomer and catalyst particles. The monomer released from these broken microcapsules is diffusing within the polymer, reacting with the catalyst and starting a polymerization reaction. This new polymer, growing within the propagating crack, stops the mechanical failure. While the process is pretty slow (timescale of the order of 10 to 100 s), there are many important technological applications that would benefit from the availability of self-healing polymers. We report about the addition of self-healing capabilities to polyethylene oxide by using polyurea formaldehyde microcapsules filled with dicyclopentadiene and first generation Grubbs catalysts. Details regarding the physical and chemical steps used to add self-healing capabilities to polyethylene oxide will be presented. Self-healing efficiency was assessed by fatigues tests.

  7. Nanostructurization and thermal properties of polyethylenes' welds

    NASA Astrophysics Data System (ADS)

    Galchun, Anatoliy; Korab, Nikolay; Kondratenko, Volodymyr; Demchenko, Valeriy; Shadrin, Andriy; Anistratenko, Vitaliy; Iurzhenko, Maksym

    2015-03-01

    As it is known, polyethylene (PE) is one of the common materials in the modern world, and PE products take the major share on industrial and trade markets. For example, various types of technical PE like PE-63, PE-80, and PE-100 have wide industrial applications, i.e., in construction, for pipeline systems etc. A rapid development of plastics industry outstrips detailed investigation of welding processes and welds' formation mechanism, so they remain unexplored. There is still no final answer to the question how weld's microstructure forms. Such conditions limit our way to the understanding of the problem and, respectively, prevent scientific approaches to the welding of more complicated (from chemical point of view) types of polymers than PE. Taking into account state-of-the-art, the article presents results of complex studies of PE weld, its structure, thermophysical and operational characteristics, analysis of these results, and basing on that some hypotheses of welded joint and weld structure formation. It is shown that welding of dissimilar types of polyethylene, like PE-80 and PE-100, leads to the formation of better-ordered crystallites, restructuring the crystalline phase, and amorphous areas with internal stresses in the welding zone.

  8. Polyethylene Oxide (PEO) and Polyethylene Glycol (PEG) Polymer Sieving Matrix for RNA Capillary Electrophoresis

    PubMed Central

    Yamaguchi, Yoshinori; Li, Zhenqing; Zhu, Xifang; Liu, Chenchen; Zhang, Dawei; Dou, Xiaoming

    2015-01-01

    The selection of sieving polymer for RNA fragments separation by capillary electrophoresis is imperative. We investigated the separation of RNA fragments ranged from 100 to 10,000 nt in polyethylene glycol (PEG) and polyethylene oxide (PEO) solutions with different molecular weight and different concentration. We found that the separation performance of the small RNA fragments (<1000 nt) was improved with the increase of polymer concentration, whereas the separation performance for the large ones (>4000 nt) deteriorated in PEG/PEO solutions when the concentration was above 1.0%/0.6%, respectively. By double logarithmic plot of mobility and RNA fragment size, we revealed three migration regimes for RNA in PEG (300-500k) and PEO (4,000k). Moreover, we calculated the smallest resolvable nucleotide length (Nmin) from the resolution length analysis. PMID:25933347

  9. The adhesion of oxygen-plasma treated poly(ethylene) and poly(ethylene terephthlate) films

    SciTech Connect

    Holton, S.L.; Kinloch, A.J. [Imperial College of Science Technology and Medicine, London (United Kingdom); Watts, J.F. [Univ. of Surrey (United Kingdom)

    1996-12-31

    The effects of low-pressure oxygen-plasma treatment on the surfaces of poly(ethylene) (PE) and poly(ethylene terephthlate) (PET) films and its influence on the adhesion of PE/PET laminates were assessed. The 90{degree} peel test was used to estimate the adhesive fracture energy, G{sub c} for the laminates. XPS, SEM and AFM were used to analyse the treated films and fracture surfaces. Significant improvements in bond strength occurred within very short treatment times (5s at 50W) with the maximum adhesion occurring after 300s. For longer treatment times the bond strengths decrease slightly. G{sub c} values were found to be low when PET was the peel arm. When PE was the peel arm, the G{sub c} values were substantially larger using the current analysis.

  10. The occurrence, induction, specificity and potential effect of antibodies against poly(ethylene glycol)

    Microsoft Academic Search

    Jonathan K. Armstrong

    Specific antibodies against poly(ethylene glycol) (anti-PEG) were induced in animals following exposure to PEG-conjugated\\u000a proteins and particles, resulting in rapid clearance of PEG-conjugated agents. In humans, induction of anti-PEG was observed\\u000a following exposure to a PEG-conjugated drug, and pre-existing anti-PEG was identified in over 25% the healthy population.\\u000a In clinical studies, the presence of anti-PEG was strongly associated with rapid

  11. Long-term, buffer-less, wet gel storage in non-sealed polyethylene bags.

    PubMed

    Kurien, Biji T; Scofield, R Hal

    2012-01-01

    Electrophoresed gels are normally fixed, stained, destained, and dried. Drying is normally carried out with commercial gel dryers or by drying between two cellophane sheets held together by two acrylic frames. Here, we report that stained and destained gels (7.5, 10, or 15%, denaturing or native gels; 0.4 or 1.5 mm in thickness) could be stored wet, unsealed, and without any storage buffer for several months at room temperature within flexible polyethylene bags without significant shrinking or protein diffusion. The gel remains hydrated because of the de facto sealing achieved by the polyethylene sheets (PS) adhering airtightly to the gel on either sides. The microsaturated environment generated by the thin film of water molecules trapped between the gel and the PS, along with the nonporous nature of the PS, apparently protects the gel from cracking as well as shrinking significantly. The intensity of stained proteins increased during storage probably from the slight gel shrinkage observed. Wet gel storage is useful (a) when low abundance protein spots from multiple two-dimensional electrophoresis gels have to be excised for in-gel tryptic digestion or electroelution and (b) for wet gel autoradiography. In addition to avoiding dryer contamination and saving drying time, these bags prevent the moist gel from sticking to X-ray film. Such storage could also prove useful for electrophoretic transfer of fixed and stained gels. PMID:22585508

  12. Annealing of single lamella nanoparticles of polyethylene

    E-print Network

    Christophe N. Rochette; Sabine Rosenfeldt; Katja Henzler; Frank Polzer; Matthias Ballauff; Qiong Tong; Stefan Mecking; Markus Drechsler; Theyencheri Narayanan; Ludger Harnau

    2011-07-05

    We study the change of the size and structure of freely suspended single lamella nanoparticles of polyethylene during thermal annealing in aqueous solutions. Using small-angle x-ray scattering and cryogenic transmission electron microscopy, it is shown that a doubling of the crystalline lamella sandwiched between two amorphous polymer layers is obtained by annealing the nanoparticles at 125 C. This thickening of the crystalline lamella can be understood in terms of an unlooping of polymer chains within a single nanoparticle. In addition a variation of the annealing temperature from 90 C to 115 C demonstrates that the inverse of the crystalline lamellar thickness increases linearly with the annealing temperatures leading to a recrystallization line in a Gibbs-Thomson graph. Since the nanoparticles consist of about only eight polymer chains, they can be considered as a ideal candidates for the experimental realization of equilibrium polymer crystals.

  13. Viscoplastic tearing of polyethylene thin film

    NASA Astrophysics Data System (ADS)

    Hegyi, Dezso; Pellegrino, Sergio

    2015-03-01

    Recent advances in noncontact strain measurement techniques and large-strain constitutive modeling of the linear low-density polyethylene film used in NASA superpressure balloons StratoFilm 420 are combined to provide a novel measurement technique for the tear propagation critical value of the J-integral. Previously these measurements required complex test configurations and procedures. It is found that the critical value of the J-integral increases by approximately 50 % when the strain rate is decreased from 1.33×10-4 s-1 to 1.33×10-5 s-1. It is shown that there is good correlation between measurements made on uniaxially loaded dogbone samples and circular diaphragms loaded by pressure, both with a 2-mm-wide slit in the middle. This result indicates that more extensive studies of strain-rate dependence may be made with the simpler, uniaxial test configuration.

  14. Polyethylene welding by pulsed visible laser irradiation

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Caridi, F.; Visco, A. M.; Campo, N.

    2011-01-01

    Laser welding of plastics is a relatively new process that induces locally a fast polymer heating. For most applications, the process involves directing a pulsed beam of visible light at the weld joint by going through one of the two parts. This is commonly referred to as “through transmission visible laser welding”. In this technique, the monochromatic visible light source uses a power ns pulsed laser in order to irradiate the joint through one part and the light is absorbed in the vicinity of the other part. In order to evaluate the mechanical resistance of the welded joint, mass quadrupole spectrometry, surface profilometry, microscopy techniques and mechanical shear tests were employed. The welding effect was investigated as a function of the laser irradiation time, nature of the polyethylene materials and temperature.

  15. Viscoplastic tearing of polyethylene thin film

    NASA Astrophysics Data System (ADS)

    Hegyi, Dezso; Pellegrino, Sergio

    2015-05-01

    Recent advances in noncontact strain measurement techniques and large-strain constitutive modeling of the linear low-density polyethylene film used in NASA superpressure balloons StratoFilm 420 are combined to provide a novel measurement technique for the tear propagation critical value of the J-integral. Previously these measurements required complex test configurations and procedures. It is found that the critical value of the J-integral increases by approximately 50 % when the strain rate is decreased from 1.33×10-4 s-1 to 1.33×10-5 s-1. It is shown that there is good correlation between measurements made on uniaxially loaded dogbone samples and circular diaphragms loaded by pressure, both with a 2-mm-wide slit in the middle. This result indicates that more extensive studies of strain-rate dependence may be made with the simpler, uniaxial test configuration.

  16. Simulation of melting in crystalline polyethylene

    NASA Astrophysics Data System (ADS)

    Zubova, E. A.; Balabaev, N. K.; Musienko, A. I.; Gusarova, E. B.; Mazo, M. A.; Manevitch, L. I.; Berlin, A. A.

    2012-06-01

    We carry out a molecular dynamics simulation of the first stages of constrained melting in crystalline polyethylene (PE). When heated, the crystal undergoes two structural phase transitions: from the orthorhombic (O) phase to the monoclinic (M) phase, and then to the columnar (C), quasi-hexagonal, phase. The M phase represents the tendency to the parallel packing of planes of PE zigzags, and the C phase proves to be some kind of oriented melt. We follow both the transitions O?M and M?C in real time and establish that, at their beginning, the crystal tries (and fails) to pass into the partially ordered phases similar to the RI and RII phases of linear alkanes, correspondingly. We discuss the molecular mechanisms and driving forces of the observed transitions, as well as the reasons why the M and C phases in PE crystals substitute for the rotator phases in linear alkanes.

  17. Biomedical coatings on polyethylene terephthalate artificial ligaments.

    PubMed

    Li, Hong; Chen, Shiyi

    2015-02-01

    This review comprehensively covers research conducted to enhance polyethylene terephthalate (PET) artificial ligament osseointegration in the bone tunnel. These strategies, using biocompatible or bioactive coatings, had a positive effect in promoting PET ligament osseointegration by increasing bone formation and decreasing fibrous scar tissue at the ligament-to-bone interface. The improved osseointegration can be translated into a significant increase in the biomechanical pull-out loads. However, the load-to-failure of coated ligament is far lower than that of native ACL. Coatings to promote intra-articular ligamentization are also discussed in this study. Collectively, our investigations may arouse further study of the biological coating of PET artificial ligaments in order to effectively enhance ligament osseointegration and promote artificial ligament ligamentization. PMID:24825100

  18. Influence of Aqueous Electrolytes on Electrical Insulating Properties of Polyethylene

    NASA Astrophysics Data System (ADS)

    Tornheim, Adam; Devine, Tom

    2012-02-01

    Polyethylene is commonly used as electrical insulation in high voltage (3-35 kV), underground electrical distribution cables. During service conditions the insulation ``ages'' and may fail. One method of ageing is a consequence of long-time exposure of the polyethylene to humidity and groundwater. Chemical analyses by other researchers indicated iron was frequently detected in degraded areas of aged cable. In the current research we examine the effect of a ferric chloride electrolyte on the electrical insulating character of polyethylene. In earlier research we discovered that in the presence of high DC voltages (approximately 3kV-6kV) ferric chloride electrolytes markedly enhance electron injection into and subsequent electron transport through polyethylene. The present research shows that ferric chloride complexes in solution are likely responsible for electron injection. The effect of exposure to ferric chloride solution was permanent, causing an increase in current density when the polyethylene was subsequently exposed to other electrolytes. The effect of FeCl3 exposure was observed in additive free polyethylene as well as commercially processed polyethylene.

  19. Influence of tannic acid and polyethylene glycol on the excretion and digestibility of amino acids in gelatin-fed broilers

    Microsoft Academic Search

    B. Mansoori; T. Acamovic

    2009-01-01

    1.?A precision feeding experiment was conducted to evaluate the effects of tannic acid (TA) and polyethylene glycol (PEG) on the excretion of amino acids, and the apparent and true digestibility of gelatin protein in broilers.2.?In a 3 × 2 × 2 factorial design, ninety-six 7-week-old broiler cockerels in 8 replicates of 12 treatments, were fed on warm solution of gelatin

  20. Suspension polymerization of poly(ethylene glycol) methacrylate: a route for swellable spherical gel beads with controlled hydrophilicity and functionality

    Microsoft Academic Search

    A. Tuncel

    2000-01-01

    Spherical and swellable gel beads were obtained by the suspension polymerization of poly(ethylene glycol) methacrylate macromonomer\\u000a (PEG-MA). The average size and size distribution properties, the equilibrium swelling behaviour and the protein adsorption\\u000a characteristics of PEG-MA-based gel beads were determined. In the suspension polymerization system, the organic phase including\\u000a monomer, cross-linker and diluent solution was dispersed in an aqueous medium by

  1. Western blot membrane composed of electrospun polyvinylidene fluoride nanofiber membrane and polyethylene terephthalate sheet.

    PubMed

    Cho, Eugene; Kim, Chan; Hwang, Cheol Ho; Chang, Duck Rye; Kook, Joong-Ki

    2013-06-01

    In a previous study, an electrospun polyvinylidene fluoride (PVDF) nanofiber membrane was developed for Western blotting. The membrane exhibited high sensitivity and high binding capacity for the detection of protein bands that was unlike that observed for conventional, microphase separation-based porous PVDF membranes. Nevertheless, the PVDF nanofiber membrane is quite expensive. The objective of this study was to develop an economical Western blot membrane using a hybrid electrospun PVDF nanofiber and polyethylene terephthalate (PET) sheet. The results showed that the detection sensitivity of the 4 gram per square meter (gsm) membrane was similar to those of the electrospun PVDF nanofiber membrane only, and the 7 gsm PVDF nanofiber membranes on a PET sheet and the electrospun PVDF nanofiber membrane. This means the protein detection sensitivity is not proportional to the thickness of the PVDF nanofiber membrane. The 4 gsm PVDF nanofiber membrane on a PET sheet can be used to detect proteins with high sensitivity and economic efficiency. PMID:23862502

  2. Influence of interaction promoter on the properties of thermoplastic elastomeric blends of natural rubber and polyethylene

    Microsoft Academic Search

    Namita Roy Choudhury; Anil K. Bhowmick

    1988-01-01

    The influence of a third component as interaction promoter on the properties of natural rubber-polyethylene thermoplastic blends, both uncured and cured, has been studied. The third component chosen has some structural similarity with polyethylene and is amorphous in nature. Ethylene propylene diene (EPDM) rubber, chlorinated polyethylene and chlorosulphonated polyethylene have been used as the third component. All the third components

  3. Polyethylene composites containing a phase change material having a C14 straight chain hydrocarbon

    Microsoft Academic Search

    Salyer; Ival O

    1987-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyethylene matrix having a straight chain alkyl hydrocarbon incorporated therein, said polyethylene being crosslinked to such a degree that said polyethylene matrix is form stable and said polyethylene matrix is capable of absorbing at least 10% by weight of said straight chain alkyl hydrocarbon; the composite is

  4. Glycol-modified silanes as versatile precursors in the synthesis of thin periodically organized silica films

    Microsoft Academic Search

    Joachim Köhler; Andrea Feinle; Michael Waitzinger; Nicola Hüsing

    2009-01-01

    Optically transparent, hexagonally organized mesoporous silica films with variable thickness have been synthesized from aqueous\\u000a solutions of tetrakis(2-hydroxyethyl)orthosilicate (EGMS) in the presence of an amphiphilic structure-directing agent (Pluronic\\u000a P123). Two different methods for film formation have been compared: spin coating from a highly concentrated and viscous precursor\\u000a solution comprising EGMS, P123 and water\\/HCl via a direct templating of a preformed

  5. Nonconventional fully developed polyethylene and wood compartment fires

    SciTech Connect

    Bohm, B.; Hadvig, S.

    1982-01-01

    Seventeen experimental fires with polyethylene and wood fuel were carried out in a full-scale compartment. The combustion air was supplied by a fan and the special feature of the compartment was the use of a slit which enabled the vertical position of the neutral plane to be well defined for outside observation. Large vertical and horizontal gradients in the gas temperature were found. In the polyethylene fires the highest mean compartment temperature measured was 1200/degree/C. In the fully developed period all fires were ventilation controlled. Simulations of the experiments were carried out by means of a computer program. A general design model for polyethylene fires is proposed. This model is compared with a similar model for wood fires, and the models are applied to structural design. For wood structures and unprotected or lightly protected steel members the polyethylene fire is the more severe. 19 refs.

  6. An exposure assessment survey of the Mont Belvieu polyethylene plant 

    E-print Network

    Tucker, Thomas Franklin

    1997-01-01

    Evaluation of ever changing, complex workplaces can be accomplished with a sound, logical exposure assessment survey (EAS). An EAS was conducted at a polyethylene plant located in southeast Texas to determine the risk of adverse health effects...

  7. Mechanical Performance of Rotomoulded Wollastonite-Reinforced Polyethylene Composites

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaowen; Easteal, Allan J.; Bhattacharyya, Debes

    This paper describes the development of a new processing technology for rotational moulding of wollastonite microfibre (WE) reinforced polyethylene (PE). Manufacturing wollastonite-polyethylene composites involved blending, compounding by extrusion, and granulating prior to rotational moulding. The properties of the resulting composites were characterised by tensile and impact strength measurements. The results show that tensile strength increases monotonically with the addition of wollastonite fibres, but impact strength is decreased. In addition, the processability is also decreased after adding more than 12 vol% WE because of increased viscosity. The effects of a coupling agent, maleated polyethylene (MAPE), on the mechanical performance and processability were also investigated. SEM analysis reveals good adhesion between the fibre reinforcements and polyethylene matrix at the fracture surface with the addition of MAPE. It is proposed that fillers with small particles with high aspect ratio (such as wollastonite) provide a large interfacial area between the filler and the polymer matrix, and may influence the mobility of the molecular chains.

  8. DISSIPATION OF FIELD APPLIED HERBICIDES FROM LOW DENSITY POLYETHYLENE MULCH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field studies evaluated dissipation of herbicides from low density polyethylene mulch (LDPM). Herbicide dissipation was measured under dry conditions and following irrigation events. Halosulfuron, paraquat, carfentrazone, glyphosate, and oxyfluorfen were applied to black 1.5-mil LDPM at concentrat...

  9. Temperature-responsive surface-functionalized polyethylene films

    E-print Network

    Ponder, Bill C.

    1998-01-01

    PE-PEG-Pyrene cooligomers were used to functionalize the surface of polyethylene films via an entrapment process. The resultant films yield a temperature responsive surface-solvent interface when immersed in water. The responsiveness of these films...

  10. Thermoluminescence and Phosphorescence in Polyethylene Under Ultra-Violet Irradiation

    Microsoft Academic Search

    A. Charlesby; R. H. Partridge

    1965-01-01

    The thermoluminescence of polyethylene induced at low temperature by ultra-violet radiation has been studied and compared with that induced by gamma-radiation. Although considerable similarity exists between these two, the total thermoluminescence output under u.v.irradiation is found to be dose rate dependent, whereas under gamma-irradiation it is independent of dose rate. Study of the low temperature u.v. induced phosphorescence of polyethylene,

  11. Long-term Radiographic Assessment of Cemented Polyethylene Acetabular Cups

    Microsoft Academic Search

    Sophie Williams; Graham Isaac; Neil Porter; John Fisher; John Older

    2008-01-01

    In vitro studies demonstrating excessive wear in polyethylene cups sterilized using gamma irradiation and stored in air led\\u000a to the abandonment of this sterilization technique. We evaluated the clinical wear performance of a metal femoral component\\u000a on a polyethylene cup in a hip prosthesis from a selected subset of implants in a group of patients followed for at least\\u000a 20 years and

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

    NASA Astrophysics Data System (ADS)

    Dauvegis, Raphaël; Rodrigue, Denis

    2015-05-01

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

  13. Simple EOS for branched (low-density) polyethylene

    SciTech Connect

    Dowell, F.

    1982-10-01

    A simple equation of state (EOS) for branched (low-density) polyethylene was generated and added to the T-4 Sesame EOS Library as material number 7171. This EOS is intended to replace an earlier EOS (material number 7170) for this substance. This new EOS for polyethylene reproduces the experimental shock Hugoniot data for the initial state density rho/sub o/ = 0.916 g/cm/sup 3/ or Mg/m/sup 3/.

  14. The Crosslinked Ultrahigh Molecular Weight Polyethylene: Risk and Limitation

    Microsoft Academic Search

    L. Costa; P. Bracco; E. M. Brach Prever

    \\u000a In the past three decades the majority of the implanted orthopedic prostheses included a bearing component made of ultrahigh\\u000a molecular weight polyethylene (UHMWPE) articulating against a femoral metallic or ceramic ball or a metallic tibial plateau.\\u000a Wear of the polyethylene bearing surfaces produces abrasion particles [1], often causing a foreign body response that may lead to bone resorption (osteolysis) and

  15. Polyethylene/Boron Composites for Radiation Shielding Applications

    SciTech Connect

    Harrison, Courtney; Grulke, Eric [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Burgett, Eric; Hertel, Nolan [Neely Nuclear Research Center, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2008-01-21

    Multifunctional composites made with boron are absorbers of low energy nuetrons, and could be used for structural shielding materials. Polyethylene/boron carbide composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. Addition of neat boron carbide (powder and nanoparticles) to an injection molding grade HPDE showed superior mechanical properties compared to neat HDPE. Radiation shielding measurements of a 2 wt% boron carbide composite were improved over those of the neat polyethylene.

  16. Abiotic Oxidation Studies of Oxo-biodegradable Polyethylene

    Microsoft Academic Search

    M. M. Reddy; Rahul K. Gupta; Rakesh K. Gupta; S. N. Bhattacharya; R. Parthasarathy

    2008-01-01

    The best approach to induce oxo-biodegradation in polyethylene is the use of special additives known as pro-oxidants. Pro-oxidants\\u000a accelerate abiotic oxidation and subsequent polymer chain cleavage rendering the product apparently more susceptible to biodegradation.\\u000a In this work, the abiotic oxidation is studied to understand how the addition of nanoclay affects the oxidation rate and the\\u000a degradation mechanism of oxo-biodegradable polyethylene.

  17. Primary radiation defect production in polyethylene and cellulose.

    PubMed

    Polvi, Jussi; Luukkonen, Petri; Nordlund, Kai; Järvi, Tommi T; Kemper, Travis W; Sinnott, Susan B

    2012-11-29

    Irradiation effects in polyethylene and cellulose were examined using molecular dynamics simulations. The governing reactions in both materials were chain scissioning and generation of small hydrocarbon and peroxy radicals. Recombination of chain fragments and cross-linking between polymer chains were found to occur less frequently. Crystalline cellulose was found to be more resistant to radiation damage than crystalline polyethylene. Statistics on radical formation are presented and the dynamics of the formation of radiation damage discussed. PMID:23131061

  18. Simple EOS for branched (low-density) polyethylene

    Microsoft Academic Search

    Dowell

    1982-01-01

    A simple equation of state (EOS) for branched (low-density) polyethylene was generated and added to the T-4 Sesame EOS Library as material number 7171. This EOS is intended to replace an earlier EOS (material number 7170) for this substance. This new EOS for polyethylene reproduces the experimental shock Hugoniot data for the initial state density rho\\/sub o\\/ = 0.916 g\\/cm³

  19. High density polyethylene (HDPE) containers as an alternative to polyethylene terephthalate (PET) bottles for solar disinfection of drinking water in northern region, Ghana

    E-print Network

    Yazdani, Iman

    2007-01-01

    The purpose of this study is to investigate the technical feasibility of high density polyethylene (HDPE) containers as an alternative to polyethylene terephthalate (PET) bottles for the solar disinfection of drinking water ...

  20. Functionalization of Polyethylene with Peroxy-containing Formulations Derived from Resins Modified with Maleic Anhydride. Properties of Blends of Functionalized Polyethylene with Polyamide 6

    Microsoft Academic Search

    Yu. M. Krivoguz; A. P. Yuvchenko; S. S. Pesetskii; M. P. Bei

    2004-01-01

    Peroxy-containing rosin-maleic and rosin-terpene-maleic resins were prepared and grafted to low-density polyethylene macromolecules by reactive extrusion. The morphology and mechanical properties of blends of functionalized polyethylene with polyamide 6 were determined.

  1. High level expression of a hydrophobic poly(ethylene terephthalate)-hydrolyzing carboxylesterase from Thermobifida fusca KW3 in Escherichia coli BL21(DE3)

    Microsoft Academic Search

    Thorsten Oeser; Ren Wei; Thomas Baumgarten; Susan Billig; Christina Föllner; Wolfgang Zimmermann

    2010-01-01

    The gram-positive thermophilic actinomycete Thermobifida fusca KW3 secretes a highly hydrophobic carboxylesterase (TfCa) that is able to hydrolyze poly(ethylene terephthalate). TfCa was produced in the Escherichia coli strain BL21(DE3) as a fusion protein consisting of a pelB leader sequence to ensure periplasmic localization of the protein and a His6 tag for use in its purification. To enhance the recombinant enzyme

  2. Launch Vehicle with Combustible Polyethylene Case Gasification Chamber Design Basis

    NASA Astrophysics Data System (ADS)

    Yemets, V.

    A single-stage launch vehicle equipped with a combustible tank shell of polyethylene and a moving propulsion plant is proposed. The propulsion plant is composed of a chamber for the gasification of the shell, a compressor of pyrolysed polyethylene and a magnetic powder obturator. It is shown that the “dental” structure of the gasification chamber is necessary to achieve the necessary contact area with the polyethylene shell. This conclusion is drawn from consideration of the thermo- physical properties of polyethylene, calculating quasisteady temperature field in the gasification chamber, estimating gasification rate of polyethylene, launch vehicle shortening rate and area of gasification. Experimental determination of the gasification rate is described. The gasification chamber specific mass as well as the propulsion plant weight-to-thrust ratio are estimated under some assumptions concerning the obturator and compressor. Combustible launch vehicles are compared with conventional launch vehicles taking into consideration their payload mass ratios. Combustible launchers are preferable as small launchers for micro and nano satellites. Reusable versions of such launchers seem suitable if polyethylene tank shells filled with metal or metal hydride fine dusts are used.

  3. Poly(ethylene oxide) surfactant polymers

    PubMed Central

    VACHEETHASANEE, KATANCHALEE; WANG, SHUWU; QIU, YONGXING; MARCHANT, ROGER E.

    2005-01-01

    We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously attached to PVAm via reductive amination. Surfactant polymers with different PEO : hexanal ratios and hydrophilic/hydrophobic balances were prepared, and characterized by FT-IR, 1H-NMR and XPS spectroscopies. Surface active properties at the air/water interface were determined by surface tension measurements. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy, showing epitaxially molecular alignment for surfactant polymers adsorbed on highly oriented pyrolytic graphite. The surfactant polymers described in this report can be adapted for simple non-covalent surface modification of biomaterials and hydrophobic surfaces to provide highly hydrated interfaces. PMID:15027845

  4. Rotational molding of pultruded profiles reinforced polyethylene

    NASA Astrophysics Data System (ADS)

    Greco, Antonio; Maffezzoli, Alfonso; Romano, Giorgio

    2014-05-01

    The aim of this paper is the production of fiber reinforced LLDPE components by rotational molding. To this purpose, a process upgrade was developed, for the incorporation of pultruded tapes in the rotational molding cycle. Pultruded tapes, made of 50% by weight of glass fibers dispersed in a high density polyethylene(HDPE) matrix, were glued on the internal surface of a cubic mold, and rotational molding process was run using the same processing conditions used for conventional LLDPE processing. During processing, melting of LLDPE powders and of HDPE allowed to incorporate the tapes inside rotational molded LLDPE. The glass fiber reinforced prototypes were characterized in terms of mechanical properties. Plate bending tests were performed on the square faces extracted from the rotational molded product. The rotational molding products were also subjected to internal hydrostatic pressure tests up to 10 bar. In any case, no failure of the cubic samples was observed. In both cases, it was found that addition of a single pultruded strips, which corresponds to addition of about 0.6% by weight of glass fibers, involved an increase of the stiffness of the faces by about 25%.

  5. Confinement-induced vitrification in polyethylene terephthalate

    SciTech Connect

    Balta Calleja, F. J.; Flores, A. [Instituto de Estructura de la Materia, CSIC, Serrano 119, 28006 Madrid (Spain); Di Marco, G.; Pieruccini, M. [Istituto per i Processi Chimico-Fisici Sezione di Messina, CNR, Via La Farina 237, I-98123 Messina (Italy)

    2007-06-01

    Dynamic mechanical thermal analysis performed on cold-drawn polyethylene terephthalate (PET), cold crystallized (annealed) in the temperature interval 100-140 deg. C, reveals the presence of marginally glassy domains above the annealing temperature T{sub a}. This suggests that the thermodynamic force driving crystallization causes the structural arrest of some noncrystalline domains. The latter thus need a temperature higher than T{sub a} to completely defreeze. Differential scanning calorimetry supports this point of view. Analogous investigations on unoriented PET, cold crystallized in the same conditions, do not show the same peculiarities; thus, chain orientation is relevant to vitrification. This phenomenology is first cast in the language of thermodynamics by introducing an excess chemical potential {delta}{mu} describing the presence of structural constraints in the amorphous domains and the effect of chain orientation. For a first test of this picture, the orientation contribution to {delta}{mu} is calculated by means of the Gaussian chain model (this implicitly assumes that {delta}{mu} is related to the density fluctuations). The resulting expression is then used to discuss the structural differences between cold-drawn and unoriented PET samples reported in the literature.

  6. Polyethylene Terephthalate May Yield Endocrine Disruptors

    PubMed Central

    Sax, Leonard

    2010-01-01

    Background Recent reports suggest that endocrine disruptors may leach into the contents of bottles made from polyethylene terephthalate (PET). PET is the main ingredient in most clear plastic containers used for beverages and condiments worldwide and has previously been generally assumed not to be a source of endocrine disruptors. Objective I begin by considering evidence that bottles made from PET may leach various phthalates that have been putatively identified as endocrine disruptors. I also consider evidence that leaching of antimony from PET containers may lead to endocrine-disrupting effects. Discussion The contents of the PET bottle, and the temperature at which it is stored, both appear to influence the rate and magnitude of leaching. Endocrine disruptors other than phthalates, specifically antimony, may also contribute to the endocrine-disrupting effect of water from PET containers. Conclusions More research is needed in order to clarify the mechanisms whereby beverages and condiments in PET containers may be contaminated by endocrine-disrupting chemicals. PMID:20368129

  7. Melt Rheological Behaviour and Thermal Properties of Low Density Polyethylene\\/Palm Kernel Shell Composites: Effect of Polyethylene Acrylic Acid

    Microsoft Academic Search

    H. Salmah; B. Y. Lim; P. L. Teh

    2012-01-01

    The melt flow behaviour and thermal properties of low density polyethylene (LDPE)\\/palm kernel shell (PKS) composites were studied. Polyethylene acrylic acid (PEAA) was used as compatibilizer in the composites. The results showed that the increasing of PKS loading had decreased MFI values of LDPE\\/PKS composites. The presence of PEAA increased the MFI values of the LDPE\\/PKS composites. The apparent viscosity

  8. Study of the electronic and vibrational properties of poly(ethylene terephthalate) and poly(ethylene naphthalate) films

    Microsoft Academic Search

    A. Laskarakis; S. Logothetidis

    2007-01-01

    We investigate the optical properties of biaxially stretched poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) polymer films by spectroscopic ellipsometry (SE) in a wide spectral region, from the infrared (IR) (900-3500 cm-1) to the vis-far UV (vis-fUV) (1.5-6.5 eV), in terms of their optical, electronic, and vibrational response. The stretching procedure during the fabrication of the films leads to the

  9. Optimizing the surface density of polyethylene glycol chains by grafting from binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Arcot, Lokanathan; Ogaki, Ryosuke; Zhang, Shuai; Meyer, Rikke L.; Kingshott, Peter

    2015-06-01

    Polyethylene glycol (PEG) brushes are very effective at controlling non-specific deposition of biological material onto surfaces, which is of paramount importance to obtaining successful outcomes in biomaterials, tissue engineered scaffolds, biosensors, filtration membranes and drug delivery devices. We report on a simple 'grafting to' approach involving binary solvent mixtures that are chosen based on Hansen's solubility parameters to optimize the solubility of PEG thereby enabling control over the graft density. The PEG thiol-gold model system enabled a thorough characterization of PEG films formed, while studies on a PEG silane-silicon system examined the versatility to be applied to any substrate-head group system by choosing an appropriate solvent pair. The ability of PEG films to resist non-specific adsorption of proteins was quantitatively assessed by full serum exposure studies and the binary solvent strategy was found to produce PEG films with optimal graft density to efficiently resist protein adsorption.

  10. Separation of exenatide analogue mono-PEGylated with 40 kDA polyethylene glycol by cation exchange chromatography.

    PubMed

    Cai, Yongqing; Yue, Peng

    2011-09-28

    Random PEGylation usually resulted in product mixtures composed of mono-PEGylated isomers and multi-PEGylated attachments. Generally in PEGylation research, separation of the mono-PEGylated isomers was the prerequisite for finding the optimal PEGylation site. However, when peptides or proteins were PEGylated with polyethylene glycol as large as 40 kDA, the physicochemical properties like hydrophobicity and molecular size of the isomers would become too similar to make the routine separation methods, like RP-HPLC, size-exclusion chromatography, SDS-PAGE and capillary isoelectric focusing invalid. This article presented a useful method of successfully separating exenatide analogue (an incretin for diabetic therapy) isomers mono-PEGylated with 40 kDA polyethylene glycol by cation exchange chromatography, which would be a powerful tool for the PEGylation research. PMID:21862025

  11. Wear of highly crosslinked polyethylene acetabular components

    PubMed Central

    Callary, Stuart A; Solomon, Lucian B; Holubowycz, Oksana T; Campbell, David G; Munn, Zachary; Howie, Donald W

    2015-01-01

    Background and purpose Wear rates of highly crosslinked polyethylene (XLPE) acetabular components have varied considerably between different published studies. This variation is in part due to the different techniques used to measure wear and to the errors inherent in measuring the relatively low amounts of wear in XLPE bearings. We undertook a scoping review of studies that have examined the in vivo wear of XLPE acetabular components using the most sensitive method available, radiostereometric analysis (RSA). Methods A systematic search of the PubMed, Scopus, and Cochrane databases was performed to identify published studies in which RSA was used to measure wear of XLPE components in primary total hip arthroplasty (THA). Results 18 publications examined 12 primary THA cohorts, comprising only 260 THAs at 2–10 years of follow-up. The mean or median proximal wear rate reported ranged from 0.00 to 0.06 mm/year. However, differences in the manner in which wear was determined made it difficult to compare some studies. Furthermore, differences in RSA methodology between studies, such as the use of supine or standing radiographs and the use of beaded or unbeaded reference segments, may limit future meta-analyses examining the effect of patient and implant variables on wear rates. Interpretation This scoping review confirmed the low wear rates of XLPE in THA, as measured by RSA. We make recommendations to enhance the standardization of reporting of RSA wear results, which will facilitate early identification of poorly performing implants and enable a better understanding of the effects of surgical and patient factors on wear. PMID:25301435

  12. Polyethylene Oxidation in Total Hip Arthroplasty: Evolution and New Advances

    PubMed Central

    Gómez-Barrena, Enrique; Medel, Francisco; Puértolas, José Antonio

    2009-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) remains the gold standard acetabular bearing material for hip arthroplasty. Its successful performance has shown consistent results and survivorship in total hip replacement (THR) above 85% after 15 years, with different patients, surgeons, or designs. As THR results have been challenged by wear, oxidation, and liner fracture, relevant research on the material properties in the past decade has led to the development and clinical introduction of highly crosslinked polyethylenes (HXLPE). More stress on the bearing (more active, overweighted, younger patients), and more variability in the implantation technique in different small and large Hospitals may further compromise the clinical performance for many patients. The long-term in vivo performance of these materials remains to be proven. Clinical and retrieval studies after more than 5 years of in vivo use with HXLPE in THR are reviewed and consistently show a substantial decrease in wear rate. Moreover, a second generation of improved polyethylenes is backed by in vitro data and awaits more clinical experience to confirm the experimental improvements. Also, new antioxidant, free radical scavengers, candidates and the reinforcement of polyethylene through composites are currently under basic research. Oxidation of polyethylene is today significantly reduced by present formulations, and this forgiving, affordable, and wellknown material is still reliable to meet today’s higher requirements in total hip replacement. PMID:20111694

  13. Preventing corona effects: multi-phosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles

    E-print Network

    Torrisi, V; Vitorazi, L; Crouzet, Q; Marletta, G; Loubat, C; Berret, J -F

    2014-01-01

    When disperse in biological fluids, engineered nanoparticles are selectively coated with proteins, resulting in the formation of a protein corona. It is suggested that the protein corona is critical in regulating the conditions of entry into the cytoplasm of living cells. Recent reports describe this phenomenon as ubiquitous and independent of the nature of the particle. For nanomedicine applications however, there is a need to design advanced and cost-effective coatings that are resistant to protein adsorption and that increase the biodistribution in vivo. In this study, phosphonic acid poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide particles. The copolymer composition was optimized to provide simple and scalable protocols as well as long-term stability in culture media. It is shown that polymers with multiple phosphonic acid functionalities and PEG chains outperform other types of coating, including ligands, polyelectrolytes and carboxylic acid functionalized PEG. PEGylated pa...

  14. Versatile ferrofluids based on polyethylene glycol coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Brullot, W.; Reddy, N. K.; Wouters, J.; Valev, V. K.; Goderis, B.; Vermant, J.; Verbiest, T.

    2012-06-01

    Versatile ferrofluids based on polyethylene glycol coated iron oxide nanoparticles were obtained by a facile protocol and thoroughly characterized. Superparamagnetic iron oxide nanoparticles synthesized using a modified forced hydrolysis method were functionalized with polyethylene glycol silane (PEG silane), precipitated and dried. These functionalized particles are dispersable in a range of solvents and concentrations depending on the desired properties. Examples of tunable properties are magnetic behavior, optical and magneto-optical response, thermal features and rheological behavior. As such, PEG silane functionalized particles represent a platform for the development of new materials that have broad applicability in e.g. biomedical, industrial or photonic environments. Magnetic, optical, magneto-optical, thermal and rheological properties of several ferrofluids based on PEG coated particles with different concentrations of particles dispersed in low molecular mass polyethylene glycol were investigated, establishing the applicability of such materials.

  15. Comparison of alumina-polyethylene and metal-polyethylene in clinical trials.

    PubMed

    Zichner, L P; Willert, H G

    1992-09-01

    The dimensional changes of hip sockets of Müller-type total endoprostheses is the subject of this article. Regular anteroposterior roentgenographs of the pelvis were taken to determine the orientation of the center of the prosthetic head in relation to the wire marker of the polyethylene cup. Three different materials used for the femoral balls and matched with polyethylene as socket material were investigated, and the results of the displacement of the ball into the socket were compared. Both creep and wear contribute to the dimensional changes of the hip sockets; the proportional amount of each mechanism is not known. Data from laboratory examinations suggest a relatively high rate of creep in the first six months after implantation. With longer periods, the dimensional changes are predominately caused by wear. In the beginning of joint function, measurements show a high rate of the yearly dimensional changes. The head shifts up to 0.5 mm per year and diminishes after five years to rates of 0.1-0.2 mm, respectively. All dimensional changes that exceed a shift of the head of 0.2 mm per year are considered to be unfavorable and to contribute to loosening of the implants. Using metallic balls (Protasul-2), 64% had a wear rate of less than 0.2 mm; of those using Prostasul-10, 77% had lower rates than 0.2 mm. In patients where ceramic balls were implanted, the displacement rate was below 0.2 mm per year in 95%. Therefore, ceramic seems to be the most favorable material. PMID:1516333

  16. Photochemical modification of polyethylene terephthalate surface

    NASA Astrophysics Data System (ADS)

    Zhu, Zhengmao

    The prospect of obtaining desired surface-mediated characteristics while retaining bulk-mediated physical properties and avoiding potential environmental issues with wet chemical technology lends considerable appeal to photochemical approaches to surface modification. We undertook a combined experimental and computational approach to investigate the effect of deep UV irradiation on the polyethylene terephthalate (PET) surface. Its response to 172 nm UV from a xenon examiner lamp in the absence of oxygen was characterized with X-ray Photoelectron Spectroscopy (XPS), Time of Flight/Secondary Ion Mass Spectrometry (ToF/SIMS), transmission infrared spectroscopy (IR), and Atomic Force Microscopy (AFM). The surface chemistry details suggested that the primary photochemical reactions involved a Norrish type I based decarbonylation and a Norrish type II process yielding terminal carboxylic acid groups, consistent with the possible photochemistry from n-pi* type lowest singlet excited states of PET according to the computational modeling results. By directly populating n-pi* type excited states, 172 nm UV promoted effective surface photochemistry of PET with further helps from the high UV absorptivity and the high surface mobility of the molecules. Utilizing this active surface radical chemistry, a new grafting strategy was developed to impart desirable functional properties to the surface. A broad range of grafting chemicals can be employed in their vapor forms, demonstrated with an alkene or an alkane. Surface analysis with XPS, ToF/SIMS, AFM, and water contact angle measurements confirmed the effectiveness of the approach, supporting the notion of the surface radical initiated processes. A potentially useful anti-stain/soil coating was developed by grafting with a fluorocarbon species. Surface analysis suggested that the grafted fluorocarbon formed a nano-scale self-assembled monolayer. The coating had a similar water contact angle as that of a pure fluoropolymer but a better oil repellency due to the special molecular orientation in the graft layer. A potential antimicrobial application was demonstrated with amine chemicals. Structure characterization and computational modeling results suggested that the photochemistry of the UV active grafting chemicals also played an important role in the grafting process. A double bond structure in the amine species protected the amine functional groups and the resulting coating demonstrated antimicrobial activity against E. coli.

  17. Initial Stages of Pyrolysis of Polyethylene

    NASA Astrophysics Data System (ADS)

    Popov, Konstantin V.

    Combustion and flammability of plastics are important topics of practical interest directly related to fire safety and recycling of polymeric materials; pyrolysis of the solid is the initial step of its combustion. One of the main ways to study such complicated processes is through detailed mechanistic modeling, in which the process is represented by a set of many elementary reactions. Mechanistic modeling of combustion of plastics is considerably hindered by the lack of necessary kinetic data. In virtually all existing models of polymer pyrolysis the majority of kinetic data used are derived from the corresponding gas phase values of smaller species. The use of gas phase rate constants is, generally, not justified without an experimental justification. In the first part of the work the influence of condensed phase on the rate of scission of a carbon-carbon bond (the reaction that initiates pyrolysis and combustion) in polyethylene (PE) was studied using the method of Reactive Molecular Dynamics (RMD). A method based on a two-step kinetic mechanism was developed to decouple the cage effect from the kinetics of the reaction under study. It was observed that under the conditions of condensed phase the rate constant of C-C bond scission in PE decreased by an order of magnitude compared to that obtained in vacuum. It was also shown that under the conditions of polymer melt the rate constant does not depend on the length of the polymer chain. In the second part of the work the kinetics of liquid phase and gas phase products of PE pyrolysis were studied experimentally using Gas Chromatography and Nuclear Magnetic Resonance. Based on the assumption of applicability of gas phase kinetic data for C-C scission reaction and beta-scission reaction under the conditions of polymer melt, rate constants of hydrogen transfer, radical addition to double bonds, and radical recombination were determined via kinetic modeling of the experimental results. The obtained values of the rate constants were found to be in reasonable agreement with the constants of similar reactions of smaller molecules in the gas phase.

  18. 78 FR 45512 - Polyethylene Terephthalate Film from India and Taiwan: Extension of Time Limits for Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ...A-533-824, A-583-837] Polyethylene Terephthalate Film from India and Taiwan: Extension of Time Limits for...antidumping duty (AD) orders on polyethylene terephthalate film (PET Film) from India and Taiwan, pursuant to section...

  19. 76 FR 58244 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, in Part, of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...A-533-824] Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission...AD) order on polyethylene terephthalate film, sheet and strip from India covering the...Garware Polyester Ltd., Jindal Poly Films Limited of India, Polyplex...

  20. 77 FR 9892 - Polyethylene Terephthalate Film, Sheet and Strip from India: Preliminary Intent to Rescind...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip from India: Preliminary...CVD) order on polyethylene terephthalate film, sheet and strip from India covering the...Polyester Ltd. (Garware), Jindal Poly Films Limited of India (Jindal),...

  1. 77 FR 1668 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, in Part, of...

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    2012-01-11

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission...CVD) order on polyethylene terephthalate film, sheet and strip from India covering the...Polyester Ltd. (Garware), Jindal Poly Films Limited of India (Jindal),...

  2. 78 FR 2365 - Polyethylene Terephthalate Film, Sheet and Strip From India: Partial Rescission of Antidumping...

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    2013-01-11

    ...A-533-824] Polyethylene Terephthalate Film, Sheet and Strip From India: Partial...AD) order on polyethylene terephthalate film, sheet and strip from India covering the...SRF Limited (SRF), and Jindal Poly Films Limited of India (Jindal).\\3\\...

  3. 77 FR 19634 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission of Countervailing Duty...

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    2012-04-02

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission...CVD) order on polyethylene terephthalate film, sheet and strip from India covering the...Polyester Ltd. (Garware), Jindal Poly Films Limited of India (Jindal),...

  4. 78 FR 48147 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of...

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    2013-08-07

    ...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results...duty (CVD) order on polyethylene terephthalate film, sheet and strip (PET film) from India for the period of review (POR)...

  5. 78 FR 2369 - Polyethylene Terephthalate Film, Sheet and Strip From India: Partial Rescission of Countervailing...

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    2013-01-11

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip From India: Partial...CVD) order on polyethylene terephthalate film, sheet and strip from India covering the...SRF Limited (SRF), and Jindal Poly Films Limited of India (Jindal). The...

  6. 76 FR 58248 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, In Part, of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...C-533-825] Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission...CVD) order on polyethylene terephthalate film, sheet and strip from India covering the...Garware Polyester Ltd., Jindal Poly Films Limited of India, Polyplex...

  7. 77 FR 3730 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, in Part, of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-25

    ...A-533-824] Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission...AD) order on polyethylene terephthalate film, sheet and strip from India covering the...Polyester Ltd. (Garware), Jindal Poly Films Limited of India (Jindal),...

  8. Synthesis and Characterization of Amphiphilic Poly(ethylene oxide)-block-poly(hexyl methacrylate)

    E-print Network

    Gruner, Sol M.

    Synthesis and Characterization of Amphiphilic Poly(ethylene oxide)-block-poly(hexyl methacrylate University, Ithaca, NY 14853, USA Keywords: amphiphilic block copolymers; anionic polymerization; ATRP; microphase separation Introduction Poly(ethylene oxide) (PEO) based amphiphilic block co- polymers exhibit

  9. 75 FR 25207 - Polyethylene Retail Carrier Bags From Malaysia: Extension of Time Limit for Preliminary Results...

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    2010-05-07

    ...Polyethylene Retail Carrier Bags From Malaysia: Extension of Time Limit for Preliminary...polyethylene retail carrier bags from Malaysia for the period August 1, 2008, through...of the sole respondent, Europlastics Malaysia Sdn. Bhd. Therefore, in...

  10. Irradiation of linear polyethylene - Partitioning between sol and gel.

    NASA Technical Reports Server (NTRS)

    Rijke, A. M.; Mandelkern, L.

    1971-01-01

    Investigation of the importance of chain-scission processes and of the applicability of the general theory of network formation to polyethylene with respect to critical conditions for gelation, using molecular weight fractions of linear polyethylene irradiated at 133 C. The partitioning between sol and gel was found to adhere to the theory just beyond the gel point. Deviations from theory occurred as the irradiation dosage was increased. It was concluded that main-chain scission at the temperatures concerned is not a significant process.

  11. Molecular order, miscibility, and rheology of molten polyethylenes

    NASA Astrophysics Data System (ADS)

    Hussein, Ibnelwaleed Ali

    New evidence of high-temperature transitions and molecular order in molten polyethylenes is presented, and its influence on the miscibility of polyethylenes is discussed. Thermal and rheological techniques were used to investigate commercial HDPE, LDPE and Ziegler-Natta and Metallocene LLDPEs. Adequate amounts of extra antioxidants were added to the polyethylenes during melt conditioning, following a separate investigation. Polystyrene was utilized to demonstrate the typical behavior of isotropic polymer melts. Temperature sweeps during torque measurements in a melt blender, and when using a rheometer and DSC, showed thermal transitions at about 208°C and 227°C. Torque in the blender over the temperature range 208°--227°C showed a flat profile or an increase in torque near 227°C, unique behavior associated with thermotropic liquid crystal polymers (LCP). Additional support for the liquid-state order that agree with theoretical predictions for a LCP is found. These include indications of an approach to a sign change in the first normal stress difference, N1( ? ), at low values of the steady shear rate, ? , and a kink in the non-Newtonian viscosity eta( ? ). A rheological investigation found no evidence of the attainment of the isotropic state at high temperature and suggested the persistence of order above these transitions. However, highly branched metallocene LLDPE ( ˜ 40 CH3/1000 C) did not show transitions or any evidence of molecular order. It is suggested that polyethylenes possess different molecular conformation in the melt state ranging from the chain-folded HDPE to the amorphous highly-branched LLDPE. It is this molecular order and mismatch of the molecular conformations of different polyethylene structures that provide an explanation for the immiscibility of polyethylenes, as revealed by the dependence of their rheological properties on blend composition. The influence of molecular weight, comonomer type, and mixing temperature on the miscibility of LLDPE and LDPE is discussed. Partial miscibility is observed in blends mixed at a temperature below 208°C, whereas blends mixed above that temperature were almost immiscible. Increasing the branch length of the LLDPE from butene to octene increased miscibility slightly. Literature reporting polyethylene melt behavior is critically reviewed over the last four decades and found to contain many anomalies of molecular order and structural transformations. The scientific community and the polyethylene processing industry need to investigate the implications of these findings.

  12. SiO2 - polyethylene reflected critical assembly

    SciTech Connect

    Brewer, R. W. (Roger W.); Sanchez, R. G. (Rene G.)

    2001-01-01

    The Planet universal critical assembly machine was used to perform a series of three critical experiments. This experiment used HEU foils reflected by polyethylene and interleaved with plates of SiO{sub 2} glass and polyethylene. Only the experiment performed using the SiO{sub 2} matrix material is evaluated in this report. The assembly was delayed critical with 33 HEU foils or 17 units (sets of HEU foils). The critical assembly has an intermediate neutron spectrum, with 51.2% of the fissions occurring between 0.625 eV and 100 keV. The calculational results show good agreement with the experimental results.

  13. Polyethylene composites containing a phase change material having a C14 straight chain hydrocarbon

    DOEpatents

    Salyer, Ival O. (Dayton, OH)

    1987-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyethylene matrix having a straight chain alkyl hydrocarbon incorporated therein, said polyethylene being crosslinked to such a degree that said polyethylene matrix is form stable and said polyethylene matrix is capable of absorbing at least 10% by weight of said straight chain alkyl hydrocarbon; the composite is useful in forming pellets or sheets having thermal energy storage characteristics.

  14. 76 FR 69659 - Methacrylic Acid-Methyl Methacrylate-Polyethylene Glycol Monomethyl Ether Methacrylate Graft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ...EPA-HQ-OPP-2011-0583; FRL-8891-4] Methacrylic Acid-Methyl Methacrylate-Polyethylene Glycol...a tolerance for residues of methacrylic acid-methyl methacrylate- polyethylene glycol...permissible level for residues of methacrylic acid-methyl methacrylate-polyethylene...

  15. Monodisperse Nanoparticles of Poly(ethylene glycol) Macromers and N-Isopropyl Acrylamide for Biomedical

    E-print Network

    Peppas, Nicholas A.

    (N-isopropylacrylamide), poly- (ethylene glycol) 400 dimethacrylate, and poly(ethylene gly- col) 1000 methacrylate were preparedMonodisperse Nanoparticles of Poly(ethylene glycol) Macromers and N-Isopropyl Acrylamide; accepted 1 June 2002 ABSTRACT: Poly(ethylene glycol)-based nanoparticles have received significant

  16. Reference standard polyethylene resins and piping materials. Final report, October 1, 1985September 30, 1986

    Microsoft Academic Search

    J. M. Crissman; F. W. Wang; C. M. Guttman; J. R. Maurey; H. L. Wagner

    1987-01-01

    Polyethylene piping is currently in widespread use in gas distribution in the United States, and represents approximately 80% of new installation, Research currently being performed on gas pipes often employs many different polyethylenes selected from the large number of polyethylenes available for this use. The variation in materials makes it difficult to compare results from different research laboratories, or to

  17. [Recombinant granulocyte-colony stimulating factor (filgrastim): optimization of conjugation with polyethylene glycol].

    PubMed

    Puchkov, I A; Kononova, N V; Bobruskin, A I; Bairamashvili, D I; Mart'ianov, V A; Shuster, A M

    2012-01-01

    In order to create an active pharmaceutical substance of the drug with prolonged action the modification of recombinant human granulocyte colony-stimulating factor GCSF (filgrastim) with polyethylene glycol (PEG, M 21.5 kDa) was conducted. A method for preparation of PEG-filgrastim designed for the development and scaling-up of the technological process of production was described. Modification of proteins with PEG was performed by selective covalent attachment of the molecule alpha-methyl-PEG-propionaldehyde to the alpha-amino group of the N-terminal methionine amino acid residue of the recombinant GCSF. The conditions of the reaction, which provide the desired product yield at least 85% of the total protein, also high protein concentration in the reaction mixture (more than 9 mg/mL) and reduce consumption of PEG in terms of terminal alpha-amino group of the protein was chosen. The data of RP HPLC and MALDI-mass spectrometry showed that the produced drug modified by the N-terminal residue and contains no more than 10% of products with a high degree of modification. PMID:23342488

  18. Preventing corona effects: multiphosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles.

    PubMed

    Torrisi, V; Graillot, A; Vitorazi, L; Crouzet, Q; Marletta, G; Loubat, C; Berret, J-F

    2014-08-11

    When dispersed in biological fluids, engineered nanoparticles are selectively coated with proteins, resulting in the formation of a protein corona. It is suggested that the protein corona is critical in regulating the conditions of entry into the cytoplasm of living cells. Recent reports describe this phenomenon as ubiquitous and independent of the nature of the particle. For nanomedicine applications, however, there is a need to design advanced and cost-effective coatings that are resistant to protein adsorption and that increase the biodistribution in vivo. In this study, phosphonic acid poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide particles. The copolymer composition was optimized to provide simple and scalable protocols as well as long-term stability in culture media. It is shown that polymers with multiple phosphonic acid functionalities and PEG chains outperform other types of coating, including ligands, polyelectrolytes, and carboxylic acid functionalized PEG. PEGylated particles exhibit moreover exceptional low cellular uptake, of the order of 100 femtograms of iron per cell. The present approach demonstrates that the surface chemistry of engineered particles is a key parameter in the interactions with cells. It also opens up new avenues for the efficient functionalization of inorganic surfaces. PMID:25046557

  19. Mechanical study of metallized polyethylene terephthalate (PET) films

    Microsoft Academic Search

    Sandhya Gupta; Manasvi Dixit; Kananbala Sharma; N. S. Saxena

    2009-01-01

    Mechanical properties such as Young's modulus (Y), storage modulus (E?), glass transition temperature (Tg), tensile strength (?), and yield strength (?y) of metallized polyethylene terephthalate (PET) films have been measured using Dynamic Mechanical Analyser (DMA). Commercially available PET film thickness of 20?m has been used for metallization. Aluminium (Al) and lead (Pb) have been coated separately on PET films by

  20. Diamond Lattice Model of Semicrystalline Polyethylene in the Amorphous Region

    E-print Network

    Aluffi, Paolo

    Diamond Lattice Model of Semicrystalline Polyethylene in the Amorphous Region Zhong­Hui Duan computed, modeling the chains as random walks on a diamond lattice with two absorbing boundaries four neighbors --- the lattice of the diamond (also silicon) crystal. We shall model the chains

  1. Irradiation effects in high-density polyethylene Jussi Polvia

    E-print Network

    Nordlund, Kai

    medical equipment and preserving food products. Since then, many more practical applications for radiation polymers like polyethylene can be used to produce heat-shrinkable-plastic films for packaging foods irradiation effects in HDPE. 2. Methods Irradiation effects in HDPE were studied using molecular dynamics

  2. Nonconventional fully developed polyethylene and wood compartment fires

    Microsoft Academic Search

    B. Bohm; S. Hadvig

    1982-01-01

    Seventeen experimental fires with polyethylene and wood fuel were carried out in a full-scale compartment. The combustion air was supplied by a fan and the special feature of the compartment was the use of a slit which enabled the vertical position of the neutral plane to be well defined for outside observation. Large vertical and horizontal gradients in the gas

  3. Effect of ?-radiation on the birefringence of stretched polyethylene films

    Microsoft Academic Search

    N. N. Nagib; S. A. Khodeir; A. A. Abd-El-Megeed; H. A. Soliman

    2004-01-01

    The spectral dependences of the birefringence and of the retardance of polyethylene films of thickness 67?m exposed to ?-radiation doses up to 500kGy are studied in the spectral range 400–700nm. It is shown that the characteristics of polymeric polarization elements could be controlled by irradiation processes.

  4. Simple EOS for linear (high-density) polyethylene (Marlex)

    SciTech Connect

    Dowell, F

    1982-11-01

    A simple equation of state (EOS) for linear (high-density) polyethylene (Marlex) was generated and added to the T-4 Sesame EOS Library as material number 7180. This new EOS for Marlex reproduces the experimental shock Hugoniot data for the initial state density rho/sub 0/ = 0.954 g/cm/sup 3/ or Mg/m/sup 3/.

  5. Adsorption of Polyethylene from Solution onto Starch Film Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since starch adsorbs onto polyethylene (PE) surfaces from cooled solutions of jet cooked starch, this study was carried out to determine whether adsorption of PE onto hydrophilic starch film surfaces would also take place if starch films were placed in hot solutions of PE in organic solvents, and th...

  6. Water contamination in a cross-linked polyethylene cable joint

    Microsoft Academic Search

    G. W. Rittmann; S. V. Heyer

    1976-01-01

    An analysis of splice failures on a cross-linked polyethylene (XLPE) insulated cable is performed with particular interest in the effects of contaminants and the adsorption of water on surface track resistance of the splice pencil. Many cable users do not give sufficient consideration to the hygroscopic nature of XLPE surfaces when developing splicing procedures. This paper examines some of the

  7. DUCTILE-TO-BRITTLE TRANSITION TIME IN POLYETHYLENE GEOMEMBRANE SHEET

    EPA Science Inventory

    The susceptibility of polyethylene (PE) geomembranes to stress cracking was evaluated in the laboratory using an accelerated notched constant load testing (NCLT) method. he test specimens were subjected to various stress levels which ranged from 25% to 70% of the yield stress at ...

  8. A lithium battery electrolyte based on gelled polyethylene oxide

    Microsoft Academic Search

    Pier Paolo Prosini; Stefano Passerini

    2002-01-01

    Gel polymer electrolytes (GPEs) were prepared by dipping a polyethylene oxide (PEO)-based solid polymer electrolyte in lithium triflate\\/propylene carbonate (PC) liquid electrolyte solutions. The quantity of the liquid electrolyte gelled in the polymer was monitored as a function of dipping time in several liquid electrolytic solutions characterized by a different salt concentration. The GPE conductivity was measured as a function

  9. Ultrahigh molecular weight polyethylene wear particle effects on bioactivity

    Microsoft Academic Search

    Hsu-Wei Fang

    2003-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) wear particles have been recognized as one of the major causes of aseptic loosening in total joint replacements. Macrophage phagocytosis of wear particles induces human biological\\/physiological responses which eventually lead to bone resorption and osteolysis. However, the dependence of these reactions on the size and shape of the particles has not been elucidated and is

  10. Wear mechanisms and particle generation in ultrahigh molecular weight polyethylene

    Microsoft Academic Search

    J. Lankford; C. R. Blanchard; C. M. Agrawal

    1995-01-01

    The effect of varying the initial surface roughness of ultrahigh molecular weight polyethylene (UHMWPE) tested in reciprocating wear against CoCr pins in bovine serum is investigated. It is found that wear occurs in two distinct stages that appear and disappear cyclically. The low wear phase corresponds to the development of surface deformation features that degenerate into a high amplitude wavelike

  11. The blast erosion behaviour of ultrahigh molecular weight polyethylene

    Microsoft Academic Search

    Y. Q. Wang; L. P. Huang; W. L. Liu; J. Li

    1998-01-01

    The erosive wear behaviour of ultrahigh molecular weight polyethylene (UHMWPE) was tested by an air-borne particle erosion equipment. The effects of impact angle, velocity and the particle hardness on the erosive wear of UHMWPE were demonstrated. By scanning electronic microscopy (SEM), the worn surface morphology was analyzed. The plastic deformation and microcracking are the main erosion mechanisms of UHMWPE under

  12. RESEARCH ARTICLE Biodegradable mulch instead of polyethylene for weed

    E-print Network

    Paris-Sud XI, Université de

    RESEARCH ARTICLE Biodegradable mulch instead of polyethylene for weed control of processing tomato P. Mill.) in Spain achieving a generally high weed control but caus- ing a serious waste problem which should provide high yield, high weed control and be economically available. For 3 years, the same

  13. Luminescence in crosslinked polyethylene of high voltage cables

    Microsoft Academic Search

    S. S. Bamji; A. T. Bulinski

    1997-01-01

    Luminescence can occur in crosslinked polyethylene (XLPE) of underground high voltage cables. Above room temperature XLPE emits thermoluminescence even without voltage application and the intensity of this light depends on the concentration of the crosslinking by-products present in the polymer. Above a certain threshold voltage XLPE, at or above room temperature, emits electroluminescence and the inception voltage of electroluminescence is

  14. Polyethylene/clay nanocomposites prepared by polymerization compounding method.

    PubMed

    Gaboune, Asmaa; Ray, Suprakas Sinha; Ait-Kadi, Abdellatif; Riedl, Bernard; Bousmina, Mosto

    2006-02-01

    A new technique for the preparation of high density polyethylene/clay nanocomposite, "polymerization compounding," is reported. This technique was based on the chemical anchoring of a Ziegler-Natta catalyst on organically modified clay surface containing an ammonium cation bearing primary hydroxyl groups. The polymerization of ethylene was initiated after adequate activation and the growing polyethylene chains are directly adsorbed on to the clay surface through the hydroxyl-functionalized surfactant. Finally, the nanocomposite was prepared by diluting polyethylene adsorbed clay in the high density polyethylene (HDPE) matrix using a batch mixer at 180 degrees C. The as-synthesized nanocomposite was typically characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) that revealed the formation of intercalated nanocomposite. Tensile property measurements exhibit substantial increase in stiffness (approximately 50%) and strength (approximately 20%) of nanocomposite as compared to that of neat HDPE. Dynamic mechanical analysis under molten state revealed 25% increase in storage modulus when compared to that of neat HDPE. PMID:16573056

  15. Poly(ethylene glycol) Self-Assembled Monolayer Island Growth

    E-print Network

    Haviland, David

    Poly(ethylene glycol) Self-Assembled Monolayer Island Growth Jonas Rundqvist, Jan H. Hoh, and David modified with self-assembled monolayers (SAMs) of oligo- (ethylene glycol) (OEG) or PEG can have excellent: January 3, 2005 Here, we report a study of the morphology and growth dynamics of a self-assembled

  16. Mechanical modifications in dense polyethylene induced by energetic electron beams

    Microsoft Academic Search

    L. Torrisi; N. Campo; L. Auditore; R. Barna; D. de Pasquale; A. Italiano; A. Trifirbo; M. Trimarchi; G. di Marco

    2004-01-01

    Effects of radiation damage in ultra high molecular weight polyethylene are investigated by using energetic electron beams. Special attention is devoted to the mechanical characterization of the polymer, before and after the modification induced by 5 MeV electrons, as a function of the absorbed dose. Elastic modules, ultimate tensile and compressive strengths and roughness and hardness, have been measured in

  17. Dynamic tensile testing of aramid and polyethylene fiber composites

    Microsoft Academic Search

    I. S. Chocron Benloulo; J. Rodríguez; M. A. Martínez; V. Sánchez Gálvez

    1997-01-01

    Dynamic properties of materials such as aramid and polyethylene fiber reinforced composites are rarely found in the literature, in spite of their significance in ballistic design. It is also difficult to find detailed descriptions of the testing techniques and procedures to characterize these materials. This paper describes a dynamic tensile testing technique for these composite materials, and discusses problems such

  18. Influence of polystyrene and polyethylene packaging materials on food quality

    Microsoft Academic Search

    J. P. H. Linssen

    1992-01-01

    Polystyrene (PS) and polyethylene (PE) used for packaging of food were studied on their effect on product quality. Different types of PS were tested: General purpose polystyrene (GPPS), high impact polystyrene (HIPS, which contains a dispersed rubber phase) and several blends of these types. PS contains detectable amounts of residual monomer, which has an unpleasant odour and\\/or taste. When the

  19. Fracture mechanics analysis of slow crack growth in polyethylene

    E-print Network

    Self, Robert Alan

    1997-01-01

    polyethylenes were used to evaluate the new test and analysis methods. Static loading of deeply notched three-point bend specimens was conducted at 26.7 'C, 40 'C, and 70 'C on 1.27 cm , 0.953 cm, and 0.635 cm material. The crack length as a function of time...

  20. Dimensionally stable PET fibers for tire reinforcement. [Polyethylene terephthalate (POLYESTERS)

    Microsoft Academic Search

    P. B. Rim; C. J. Nelson

    1991-01-01

    High-modulus, high-tenacity polyethylene terephthalate (PET) fibers have gained wide acceptance in reinforcement for rubber products such as tires and hoses; in geotextiles, and in ropes and cordage. Accordingly, a great deal of fundamental research has been conducted on how the processing and resulting morphology of these thermoplastic fibers affect their physical properties. The translation of these starting fiber properties to

  1. Preparation, microstructure and properties of polyethylene aluminum nanocomposite dielectrics

    Microsoft Academic Search

    Xingyi Huang; Pingkai Jiang; Chonung Kim; Qingquan Ke; Genlin Wang

    2008-01-01

    Linear low density polyethylene (PE) aluminum (Al) nanocomposites were prepared and their morphology and properties were investigated. The particular attention was given to the structure\\/property relationship of the nanocomposites and an equivalent electric circuit model was proposed to interpret the dependences of the dielectric behaviors of the PE\\/Al nanocomposites on the nanoparticle concentration and the measuring frequency. The increase of

  2. Thermoplasticizing Technology for the Recycling of Crosslinked Polyethylene

    Microsoft Academic Search

    Shigeru Tokuda; Sanae Horikawa; Kunio Negishi; Kenji Uesugi; Hiroshi Hirukawa

    2003-01-01

    Because of its outstanding dielectric properties and heat resistance, crosslinked polyethylene (XLPE) is widely used as insulation materials for electric wires and cables. However the three-dimensional lattice structure produced by crosslinking makes it impos- sible to melt it down again for molding. Thus almost all waste XLPE is currently burnt (as a fuel) or disposed of in landfills. In this

  3. Simple EOS for linear (high-density) polyethylene (Marlex)

    Microsoft Academic Search

    Dowell

    1982-01-01

    A simple equation of state (EOS) for linear (high-density) polyethylene (Marlex) was generated and added to the T-4 Sesame EOS Library as material number 7180. This new EOS for Marlex reproduces the experimental shock Hugoniot data for the initial state density rhoâ = 0.954 g\\/cm³ or Mg\\/m³.

  4. SECURING CONTAINERIZED HAZARDOUS WASTES WITH WELDED POLYETHYLENE ENCAPSULATES

    EPA Science Inventory

    Full-scale encapsulation of 208-liter (55-gal) drums was studied as a means for managing corroding containers of hazardous wastes in the field and rendering them suitable for transport and safe deposit within a final disposal site such as a landfill. Polyethylene (PE) receivers w...

  5. Wastewater treatment using activated sludge entrapped in polyethylene glycol prepolymer

    Microsoft Academic Search

    Nobuko Hashimoto; Tatsuo Sumino

    1998-01-01

    Immobilized activated sludge was applied to the treatment of organic wastewater discharged from a semiconductor plant. To enhance the treatment efficiency, the growth characteristics of heterotrophic bacteria and the effect of the BOD loading rate in continuous wastewater treatment by the immobilized activated sludge were investigated. The activated sludge was entrapped in polyethylene glycol (PEG) prepolymer pellets. Wastewater with a

  6. Effects of Electrode Materials on Photocurrents in Polyethylene Terephthalate

    Microsoft Academic Search

    Yoshiaki Takai; Toshifumi Osawa; Kwan Chi Kao; Teruyoshi Mizutani; Masayuki Ieda

    1975-01-01

    A new experimental technique to confirm the photoinjection from metal electrodes (aluminum, indium, copper, silver and gold) and to determine the sign of the injected carriers is developed and applied to a polyethylene terephthalate film in the wavelength region from 400 nm to 320 nm. The dominant carriers injected are electrons for aluminum and copper, and electrons and holes for

  7. The effect of pressure upon the melting transition of polyethylene

    E-print Network

    Mroz, George Joseph

    1961-01-01

    THE EFFECT OF PRESSURE UPON THE MELTING TRANSITION OF POLYETHYLENE o m vS n Z 8 i c6 C 0 A Thesis By George Joseph Nros Approved as to style and content by: C a rman o Comm ttee (Head of Department) August 1961 ACKNOWLEDGEMENT...

  8. Infrared, Raman and INS studies of poly-ethylene oxide oligomers

    NASA Astrophysics Data System (ADS)

    Migliardo, F.; Magazù, S.; Caccamo, M. T.

    2013-09-01

    In the present paper the experimental findings obtained by different spectroscopic techniques on water mixtures of a protein model system, i.e. PolyEthylene Oxide (PEO), are reported. By increasing the polymerization degree m, the D-LAM spectral contribution shows a behavior of the centre frequency and of linewidth which tends to reach a constant value. Also the intramolecular OH stretching contribution, by increasing m, shows a shift which tends to flatten for polymers with molecular weight higher than Mw = 600. These results can be connected with the oligomer-polymer transition, at m = 13. When in aqueous solutions the D-LAM frequency increases towards the value corresponding to that of the crystal phase; similarly one observes also a sharpening of the D-LAM spectral contribution. These evidences suggest the presence of a more ordered conformation of PEO in water in respect to the melt phase.

  9. Poly(ethylene glycol)-Prodrug Conjugates: Concept, Design, and Applications

    PubMed Central

    Banerjee, Shashwat S.; Aher, Naval; Patil, Rajesh; Khandare, Jayant

    2012-01-01

    Poly(ethylene glycol) (PEG) is the most widely used polymer in delivering anticancer drugs clinically. PEGylation (i.e., the covalent attachment of PEG) of peptides proteins, drugs, and bioactives is known to enhance the aqueous solubility of hydrophobic drugs, prolong circulation time, minimize nonspecific uptake, and achieve specific tumor targetability through the enhanced permeability and retention effect. Numerous PEG-based therapeutics have been developed, and several have received market approval. A vast amount of clinical experience has been gained which has helped to design PEG prodrug conjugates with improved therapeutic efficacy and reduced systemic toxicity. However, more efforts in designing PEG-based prodrug conjugates are anticipated. In light of this, the current paper highlights the synthetic advances in PEG prodrug conjugation methodologies with varied bioactive components of clinical relevance. In addition, this paper discusses FDA-approved PEGylated delivery systems, their intended clinical applications, and formulations under clinical trials. PMID:22645686

  10. Polyethylene glycol-mediated transformation of fused egfp-hph gene under the control of gpd promoter in Pleurotus eryngii.

    PubMed

    Yin, Yonggang; Liu, Yu; Jin, Haojie; Wang, Shouxian; Zhao, Shuang; Geng, Xiaoli; Li, Ming; Xu, Feng

    2012-10-01

    Pleurotus eryngii was transformed using a polyethylene glycol-mediated method. A plasmid, pEPUGH, containing a reporter gene (enhanced green fluorescent protein gene, egfp) and a positive selectable marker gene (hygromycin phosphotransferase gene, hph) was constructed. The fused egfp-hph gene was placed under the control of the strong and constitutive native gpd promoter from P. eryngii. The recombinant plasmid was used to transform of P. eryngii protoplasts. Successful transformation was demonstrated by molecular analyses. Moreover, the mycelia of the transformants showed green epipolic dispersion on fluorescence microscopy. About 90-210 transformants were produced per ?g plasmid DNA per 10(7) viable protoplasts. PMID:22763850

  11. Solvent effect in the polyethylene recovery from multilayer postconsumer aseptic packaging.

    PubMed

    Cervantes-Reyes, Alejandro; Núñez-Pineda, Alejandra; Barrera-Díaz, Carlos; Varela-Guerrero, Víctor; Martínez-Barrera, Gonzalo; Cuevas-Yañez, Erick

    2015-04-01

    Polyethylene films were separated and recovered from polyethylene-aluminum composites derived from recycling multilayer postconsumer aseptic packaging. A brief study about the separation process by dissolving PE-aluminum (PE-Al) composites into a series of organic solvents with a combination of time and temperature is presented. Through this procedure, 56% polyethylene is recovered from this kind of composites in optimized conditions. DSC and TGA studies were performed to determine the thermal stability of recovered polyethylene films and to establish a comparison with a PE reference commercial product, demonstrating that recovered polyethylene films kept their thermal properties. PMID:25681948

  12. Pressure effects on viscosity and flow stability of polyethylene melts during extrusion

    Microsoft Academic Search

    Enric Santanach Carreras; Nadia El Kissi; Jean-Michel Piau; Fabrice Toussaint; Sophie Nigen

    2006-01-01

    In the present work, the effects of pressure on the viscosity and flow stability of four commercial grade polyethylenes (PEs)\\u000a have been studied: linear-low-density polyethylene copolymer, high-density polyethylene, metallocene polyethylenes with short-chain\\u000a branches (mPE-SCB), and metallocene polyethylenes with long chain branching (mPE-LCB). The range of shear rates considered\\u000a covers both stable and unstable flow regimes. “Enhanced exit-pressure” experiments have been

  13. Purification and characterization of polyethylene glycol dehydrogenase involved in the bacterial metabolism of polyethylene glycol.

    PubMed Central

    Kawai, F; Kimura, T; Tani, Y; Yamada, H; Kurachi, M

    1980-01-01

    Polyethylene glycol (PEG) dehydrogenase in crude extracts of a PEG 20,000-utilizing mixed culture was purified 24 times by precipitation with ammonium sulfate, solubilization with laurylbetaine, and chromatography with diethylamino-ethyl-cellulose, hydroxylapatite, and Sephadex G-200. The purified enzyme was confirmed to be homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight of the enzyme, which appeared to consist of four identical subunits, was 2.4 X 10(5). The enzyme was stable below 35 degrees C and in the pH range of 7.5 to 9.0. The optimum pH and temperature of the activity were around 8.0 and 60 degrees C, respectively. The enzyme did not require any metal ions for activity and oxidized various kinds of PEGs, among which PEG 6,000 was the most active substrate. The apparent Km values for tetraethylene glycol and PEG 6,000 were about 10.0 and 3.0 mM, respectively. Images PMID:6999995

  14. Proteomic and phosphoproteomic analysis of polyethylene glycol-induced osmotic stress in root tips of common bean (Phaseolus vulgaris L.)

    PubMed Central

    Horst, Walter Johannes

    2013-01-01

    Previous studies have shown that polyethylene glycol (PEG)-induced osmotic stress (OS) reduces cell-wall (CW) porosity and limits aluminium (Al) uptake by root tips of common bean (Phaseolus vulgaris L.). A subsequent transcriptomic study suggested that genes related to CW processes are involved in adjustment to OS. In this study, a proteomic and phosphoproteomic approach was applied to identify OS-induced protein regulation to further improve our understanding of how OS affects Al accumulation. Analysis of total soluble proteins in root tips indicated that, in total, 22 proteins were differentially regulated by OS; these proteins were functionally categorized. Seventy-seven per- cent of the total expressed proteins were involved in metabolic pathways, particularly of carbohydrate and amino acid metabolism. An analysis of the apoplastic proteome revealed that OS reduced the level of five proteins and increased that of seven proteins. Investigation of the total soluble phosphoproteome suggested that dehydrin responded to OS with an enhanced phosphorylation state without a change in abundance. A cellular immunolocalization analysis indicated that dehydrin was localized mainly in the CW. This suggests that dehydrin may play a major protective role in the OS-induced physical breakdown of the CW structure and thus maintenance of the reversibility of CW extensibility during recovery from OS. The proteomic and phosphoproteomic analyses provided novel insights into the complex mechanisms of OS-induced reduction of Al accumulation in the root tips of common bean and highlight a key role for modification of CW structure. PMID:24123251

  15. Universal concept for the implementation of a single cleavable unit at tunable position in functional poly(ethylene glycol)s.

    PubMed

    Dingels, Carsten; Müller, Sophie S; Steinbach, Tobias; Tonhauser, Christine; Frey, Holger

    2013-02-11

    Poly(ethylene glycol) (PEG) with acid-sensitive moieties gained attention particularly for various biomedical applications, such as the covalent attachment of PEG (PEGylation) to protein therapeutics, the synthesis of stealth liposomes, and polymeric carriers for low-molecular-weight drugs. Cleavable PEGs are favored over their inert analogues because of superior pharmacodynamic and/or pharmacokinetic properties of their formulations. However, synthetic routes to acetal-containing PEGs published up to date either require enormous efforts or result in ill-defined materials with a lack of control over the molecular weight. Herein, we describe a novel methodology to implement a single acetaldehyde acetal in well-defined (hetero)functional poly(ethylene glycol)s with total control over its position. To underline its general applicability, a diverse set of initiators for the anionic polymerization of ethylene oxide (cholesterol, dibenzylamino ethanol, and poly(ethylene glycol) monomethyl ether (mPEG)) was modified and used to synthesize the analogous labile PEGs. The polyether bearing the cleavable lipid had a degree of polymerization of 46, was amphiphilic and exhibited a critical micelle concentration of 4.20 mg·L(-1). From dibenzylamino ethanol, three heterofunctional PEGs with different molecular weights and labile amino termini were generated. The transformation of the amino functionality into the corresponding squaric acid ester amide demonstrated the accessibility of the cleavable functional group and activated the PEG for protein PEGylation, which was exemplarily shown by the attachment to bovine serum albumin (BSA). Furthermore, turning mPEG into a macroinitiator with a cleavable hydroxyl group granted access to a well-defined poly(ethylene glycol) derivative bearing a single cleavable moiety within its backbone. All the acetal-containing PEGs and PEG/protein conjugates were proven to degrade upon acidic treatment. PMID:23256621

  16. Gels and foams from ultrahigh-molecular-weight polyethylene

    SciTech Connect

    Hair, L.M.; Letts, S.A. (Lawrence Livermore National Labs., CA (United States))

    1990-01-01

    Crystallization-gelation of ultrahigh-molecular-weight polyethylene (UHMW PE) was used to make stiff gels that were supercritically dried to make low-density, small-cell-size foams. The effects of solvent and cooling conditions on gelation and morphology were investigated. X-ray diffractometry showed that the size of the crystalline lamellae in the finished foam decreased with increased cooling rate for foams made from UHMW PE in tetralin, but not in dodecane or decalin. This difference may be attributable to the greater expansion of the polyethylene chain in tetralin than in dodecane, as revealed by viscometry. However, the superstructure of the foam, which includes the pore sizes and homogeneity, was found to be affected by solvent as well as by cooling conditions.

  17. Study of the Auger line shape of polyethylene and diamond

    NASA Technical Reports Server (NTRS)

    Dayan, M.; Pepper, S. V.

    1984-01-01

    The KVV Auger electron line shapes of carbon in polyethylene and diamond have been studied. The spectra were obtained in derivative form by electron beam excitation. They were treated by background subtraction, integration and deconvolution to produce the intrinsic Auger line shape. Electron energy loss spectra provided the response function in the deconvolution procedure. The line shape from polyethylene is compared with spectra from linear alkanes and with a previous spectrum of Kelber et al. Both spectra are compared with the self-convolution of their full valence band densities of states and of their p-projected densities. The experimental spectra could not be understood in terms of existing theories. This is so even when correlation effects are qualitatively taken into account account to the theories of Cini and Sawatzky and Lenselink.

  18. Dielectric behavior of AC aged polyethylene in humid environment

    SciTech Connect

    Scarpa, P.C.N.; Das-Gupta, D.K. [Univ. of Wales, Bangor (United Kingdom). School of Electronic Engineering and Computer Systems; Bulinski, A.T.; Bamji, S. [National Research Council, Ottawa, Ontario (Canada)

    1996-12-31

    The present paper reports the results of a study of electrical aging of low density polyethylene (LDPE) aged in humid environment (0.1M NaCl) at an AC stress of 6kV/mm, 1kHz, at room temperature (RT) and at 65 C, and cross-linked polyethylene (XLPE) AC aged in humid environment (water) at an AC stress of 6kV/mm, 50Hz, at RT, for an extended period of time. For this study the dielectric spectroscopy data in the frequency range of 10{sup {minus}5}Hz to 10{sup 6}Hz and their comparative analysis, have been used to provide electrical analog models of the aging.

  19. Polyethylene naphthalate as an excellent candidate for ripple nanopatterning

    NASA Astrophysics Data System (ADS)

    Slepi?ka, P.; Ned?la, O.; Sajdl, P.; Kolská, Z.; Švor?ík, V.

    2013-11-01

    The surface of polyethylene naphthalate (PEN) foils was exposed to KrF excimer laser treatment. Due to presence of condensed benzene rings has this polymer better mechanical, chemical and thermal properties in comparison to polyethylene terephthalate, which is widely applicable in electronic devices and also as tissue cell carriers. The influence of laser fluence and number of laser pulses on surface chemistry and morphology was determined. The surface morphology was studied with atomic force microscopy (AFM) in combination with scanning electron microscopy and focused ion beam (FIB-SEM). Surface wettability was characterized by the contact angle measurement. Surface chemistry was evaluated from XPS spectra. The optimal PEN process parameters with the most regular pattern were determined. The foils with optimal ripple pattern were consequently sputtered with gold nanolayers of 100 nm thickness. The parameters of ripple pattern after the metallization were introduced. It was found that the gold nanolayer is formed of electrically continuous wires, the ripple pattern was maintained.

  20. Strength of polyethylene, polypropylene and polystyrene behind a shock front

    SciTech Connect

    Tyler, C. E. [University of Manchester, PO Box 88, Sackville Street, Manchester, M60 1QD (United Kingdom); Bourne, N. K.; Millett, J. C. F. [AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

    2007-12-12

    There is a recent interest in the response of thermoplastics to shock. Previous work on three simple hydrocarbons has indicated that the shear strength increases with the complexity of the side group. Strength values have been calculated using lateral stress measurements with manganin gauges that have been recalibrated for use in the low stress regime. The present work aims to investigate the effect of the configuration of the thermoplastic's chain when side groups are added. Results show that whilst polyethylene has the lowest shear strength, polypropylene and polystyrene have similar values. In all cases the strength of polymer increases with time after the shock has past. As the applied stress increases, polystrene and polypropylene strengthen to a higher degree when compared with polyethylene. Explanations are offered in terms of microstructure and tacticity of the chain.

  1. Hyperthermal atomic oxygen reactions with kapton and polyethylene

    SciTech Connect

    Cross, J.B. (Los Alamos National Lab., NM (USA)); Koontz, S.L. (National Aeronautics and Space Administration, Houston, TX (USA). Lyndon B. Johnson Space Center); Gregory, J.C.; Edgell, M.J. (Alabama Univ., Huntsville, AL (USA). Dept. of Chemistry)

    1990-01-01

    Gas phase reaction products produced by the interaction of high kinetic energy (1--3 eV) {sup 3}P ground state atomic oxygen (AO) with polyethylene and kapton were found to be H{sub 2}, H{sub 2}O, CO, and CO{sub 2} with NO being a possible secondary product from kapton. Hydrogen abstraction at high AO kinetic energy is postulated to be the key reaction controlling the erosion rate of kapton and polyethylene. An Arrhenius-like expression having an activation barrier of 0.4 eV can be fit to the data, which suggests that the rate limiting step in the AO/kapton reaction mechanism can be overcome by translational energy. 16 refs., 13 figs.

  2. Fabrication and anti-fouling properties of photochemically and thermally immobilized poly(ethylene oxide) and low molecular weight poly(ethylene glycol) thin films

    Microsoft Academic Search

    Hui Wang; Jin Ren; Aye Hlaing; Mingdi Yan

    2011-01-01

    Poly(ethylene oxide) (PEO) and low molecular weight poly(ethylene glycol) (PEG) were covalently immobilized on silicon wafers and gold films by way of the CH insertion reaction of perfluorophenyl azides (PFPAs) by either photolysis or thermolysis. The immobilization does not require chemical derivatization of PEO or PEG, and polymers of different molecular weights were successfully attached to the substrate to give

  3. Alkyd resins derived from glycolized waste poly(ethylene terephthalate)

    Microsoft Academic Search

    George P. Karayannidis; Dimitris S. Achilias; Irini D. Sideridou; Dimitris N. Bikiaris

    2005-01-01

    In this investigation the production of secondary value-added products, such as alkyd resins, derived from the glycolysis of poly(ethylene terephthalate) (PET) is examined as an effective way for its recycling. PET was taken from common soft-drink bottles and diethylene glycol (DEG) was used for the depolymerization at several initial molar ratios. The oligomers obtained were analyzed according to their average

  4. The electroluminescence of gamma-irradiated polyethylene at 77K

    Microsoft Academic Search

    A. E. Blake; K. J. Randle

    1977-01-01

    Following gamma -irradiation at 77K, the isothermal luminescence (ITL) exhibited by polyethylene film has been enhanced by the application of an electric field. The effect is not permanent but is correlated with the magnitude of the ITL signal. It has been attributed to the field-assisted thermal detrapping of trapped electrons and subsequent recombination. A simple one-dimensional model accounts for many

  5. Wear characteristics of ultrahigh molecular weight polyethylene (UHMWPE)

    Microsoft Academic Search

    A. El-Domiaty; M. El-Fadaly; A. Es. Nassef

    2002-01-01

    The wear of ultrahigh molecular weight polyethylene (UHMWPE) bearing against 316 stainless steel or cobalt chromium (Co-Cr)\\u000a alloy was measured using a 12-channel wear tester especially developed for the evaluation of candidate materials for prosthetic\\u000a joints. The coefficient of friction and wear rate were determined as a function of lubricant, contact stress, and metallic\\u000a surface roughness in tests lasting 2–3

  6. Molecular dynamics simulation of chains mobility in polyethylene crystal

    E-print Network

    V. I. Sultanov; V. V. Atrazhev; D. V. Dmitriev; S. F. Burlatsky

    2014-01-17

    The mobility of polymer chains in perfect polyethylene (PE) crystal was calculated as a function of temperature and chain length through Molecular dynamics (MD) in united atom approximation. The results demonstrate that the chain mobility drastically increases in the vicinity of the phase transition from the orthorhombic to quasi-hexagonal phase. In the quasi-hexagonal phase, the chain mobility is almost independent on temperature and inversely proportional to the chain length.

  7. Wear performance of ultrahigh molecular weight polyethylene\\/quartz composites

    Microsoft Academic Search

    X. L. Xie; C. Y. Tang; Kathy Y. Y. Chan; X. C. Wu; C. P. Tsui; C. Y. Cheung

    2003-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE)\\/quartz composites were compression molded in the presence of organosiloxane, and then hydrolyzed. The used organosiloxane is vinyl tri-ethyloxyl silane. The gelation, the melting behavior, the crystallinity, the mechanical properties and the wear resistance of UHMWPE\\/quartz composites were investigated. The results showed that organosiloxane can act as a cross-linking agent for UHMWPE matrix and serve as

  8. The Structural Dilemma of Bulk Polyethylene: An Intermediary Structure

    PubMed Central

    Laridjani, Morteza; Leboucher, Pierre

    2009-01-01

    Background The Fourier space (reciprocal space) image of bulk polyethylene consists of lines superimposed on the coherent diffuse background. The mixed character of the image indicates the complex nature of these compounds. The inability in detecting full images of reciprocal space of polymeric substances without Compton radiation and the other undesirable diffuse scatterings has misled the structural analysis (structural characterisation) of these materials. Principal Findings We propose the use of anomalous diffractometry where, it is possible to obtain a real image of reciprocal space without Compton radiation and other undesirable scatterings. By using classical diffractometry techniques this procedure is not possible. This methodology permitted us to obtain the “Direct Delta function”, in the case of polycrystalline substances that was not previously detected. A new procedure was proposed to interpret the image of reciprocal space of bulk polyethylene. The results show the predominance of the geometry of local order determination compared to the crystal unit cell. The analysis of x-ray diffraction images illustrates that the elementary structural unit is a tetrahedron. This structural unit illustrates the atoms in the network scatter in a coherent diffuse manner. Moreover, the interference function derived from the coherent diffuse scattering dampens out quickly and the degree of randomness is superior to a liquid state. The radial distribution function derived from this interference function shows bond shortening in the tetrahedron configuration. It is this particular effect, which stabilises polyethylene. Conclusion Here we show by anomalous diffractometry that the traditional concept of the two-phase or the crystal-defect model is an oversimplification of the complex reality. The exploitation of anomalous diffractometry has illustrated that polyethylene has an intermediate ordered structure. PMID:19597553

  9. EPDM\\/polyamide TPV compatibilized by chlorinated polyethylene

    Microsoft Academic Search

    Xin Liu; Hua Huang; ZhiYun Xie; Yong Zhang; YinXi Zhang; Kang Sun; LiNa Min

    2003-01-01

    A thermoplastic vulcanizate (TPV) of ethylene-propylene-diene (EPDM) and polyamide (PA) with excellent mechanical properties was prepared by dynamic vulcanization. The effects of the vulcanizing agents, compatibilizer, PA content, aging and reprocessing on mechanical properties of EPDM\\/PA thermoplastic vulcanizate were investigated. Experimental results indicate that chlorinated polyethylene has a better effect in compatibilizing the EPDM\\/copolyamide blends compared with the other compatibilizers,

  10. Giant Thermal Rectification from Polyethylene Nanofiber Thermal Diodes

    E-print Network

    Zhang, Teng

    2015-01-01

    The realization of phononic computing is held hostage by the lack of high performance thermal devices. Here we show through theoretical analysis and molecular dynamics simulations that unprecedented thermal rectification factors (as large as 1.20) can be achieved utilizing the phase dependent thermal conductivity of polyethylene nanofibers. More importantly, such high thermal rectifications only need very small temperature differences (highly phase-sensitive and a cross-linked portion which has a stable phase. Nanoscale size effect can be utilized t...

  11. Cytostatic effect of polyethylene glycol on human colonic adenocarcinoma cells

    Microsoft Academic Search

    Géraldine Parnaud; Denis E. Corpet

    2001-01-01

    Polyethylene glycol (PEG 8000) is a potent cancer chemopreventive agent. This osmotic laxative polymer markedly suppresses colon cancer in rats. To explain the mechanism, we have tested the in vitro effect of PEG on four human cell lines. Two poorly differentiated adenocarcinoma lines (HT29 and COLO205), a fetal mucosa line (FHC) and a differentiated line (post-confluent Caco-2) were incubated with

  12. COMPATIBILIZERS FOR LOW DENSITY POLYETHYLENE\\/POLYPROPYLENE BLENDS

    Microsoft Academic Search

    A. G. Andreopoulos; P. A. Tarantili; P. Anastassakis

    1999-01-01

    The role of polyolefin elastomers as compatibilizers in Low Density Polyethylene\\/Polypropylene (LDPE\\/PP) blends, in the presence of di-cumyl peroxide (DCP) has been studied. Mixtures of 90\\/10 LDPE\\/PP ratio, were prepared in a Brabender plasticorder and tested for their mechanical properties and calorimetric response. Then the elastomers ethylene-propylene-diene copolymer (EPDM) and polybutadiene (BR) were added, alone or together with 0.2% DCP

  13. Dielectric properties of zinc oxide\\/low density polyethylene nanocomposites

    Microsoft Academic Search

    J. I. Hong; P. Winberg; L. S. Schadler; R. W. Siegel

    2005-01-01

    ZnO\\/low density polyethylene (LDPE) nanocomposites with either homogeneous or controlled inhomogeneous dispersions of ZnO nanoparticles were prepared. The dielectric constants of the composites with filler concentrations up to 40 vol.% were measured and compared with the dielectric constants of conventional submicron size ZnO filled LDPE composite. The filler particles were coated with silane coupling agents and mixed with LDPE to

  14. Kinetic Parameters of Polyethylene Degradation by the Natural Zeolite Chabazite

    Microsoft Academic Search

    V. J. Fernandes; A. S. Araujo; R. A. Medeiros; J. R. Matos; L. P. Mercuri; A. O. Silva; D. M. A. Melo

    1999-01-01

    High-density polyethylene (PE) was subjected to thermal degradation alone and in the presence of an ammonium-exchanged zeolite\\u000a chabazite (CHA\\/PE). The processes were carried out in a reactor connected online to a gas chromatograph\\/mass spectrometer\\u000a in order to analyse the evolved products. Polymer degradation was also evaluated by thermogravimetry, from room temperature\\u000a up to 800°C, under a dynamic nitrogen atmosphere, with

  15. Packet charge dynamic in thin polyethylene under high dc voltage

    NASA Astrophysics Data System (ADS)

    Gargouri, Amal; Boukhris, Imed; Belgaroui, Ezzeddine; Kallel, Ali

    2013-06-01

    In this paper, we present a bipolar transport model in low-density polyethylene under high direct-current voltage in order to investigate the charge packet dynamic generated under high injection. These charge packets, observed by our model for the first time, have already been seen in some previous experimental works for a long time. Our model results show that applied electric field and sample thickness play important roles on the apparition of space charge packets.

  16. Localised flow-induced crystallisation of a polyethylene melt

    Microsoft Academic Search

    D. G. Hassell; M. R. Mackley

    2008-01-01

    The sensitivity of flow-induced crystallisation (FIC) to the nature of flow type is demonstrated using a high-density polyethylene\\u000a (HDPE) for two different flow geometries. A contraction–expansion slit geometry was used to create a mixed, but primarily\\u000a simple shear flow, while a cross-slot geometry provided a region within the flow of high extension. Flow-induced birefringence\\u000a was captured at a melt processing

  17. Polyethylene Glycol (PEG)-Induced Anaphylactic Reaction During Bowel Preparation

    PubMed Central

    2015-01-01

    Barium enema is used to screen patients with gastrointestinal bleeding who do not want to undergo colonoscopy. Polyethylene glycol (PEG) is usually the bowel preparation of choice. Few allergic reactions from this product have been reported; these include urticaria, angioedema, and anaphylaxis. Reactions are thought to result from a small amount of PEG crossing the intestinal mucosa, which, in some patients, is sufficient to provoke an anaphylactic reaction.

  18. Effect of cenosphere on dielectric properties of low density polyethylene

    NASA Astrophysics Data System (ADS)

    Sharma, Janu; Chand, Navin; Bapat, M. N.

    2012-01-01

    Dielectric characterization of cenosphere filled low density polyethylene composites is reported in this paper. Cenosphere filled low density polyethylene (LDPE) composites with inhomogeneous dispersions of cenosphere were prepared and dielectric measurements have been performed on these composites in the temperature range 34-110 °C in the frequency range 1-10 kHz. The dielectric constants of the composites with filler concentrations 0%, 10%, 15% and 20 vol.% were measured. Effect of temperature and frequency variations on dielectric constant (??), dissipation factor (tan ?) and a.c. conductivity (?a.c.) was also determined. The frequency dependent dielectric and conductivity behaviour of flyash cenosphere filled low density polyethylene (LDPE) polymer composites have been studied. Appearance of peak in the dielectric loss curves for all the concentrations confirms the presence of relaxing dipoles in the cenosphere/LDPE composites. The effect of filler distribution on the dielectric constant is examined and the observed differences are attributed to the differences in two kinds of interfaces present: one formed between the touching cenosphere particles and the other formed between LDPE and cenosphere. With the increase of cenosphere content dielectric constant decreased gradually. Maxwell-Garnett approximation fairly fits for the dielectric data obtained experimentally for these composites.

  19. Wear Analysis in THA Utilizing Oxidized Zirconium and Crosslinked Polyethylene

    PubMed Central

    Garvin, Kevin L.; Mangla, Jimmi; Murdoch, Nathan; Martell, John M.

    2008-01-01

    Oxidized zirconium, a material with a ceramic surface on a metal substrate, and highly cross-linked polyethylene are two materials developed to reduce wear. We measured in vivo femoral head penetration in patients with these advanced bearings. We hypothesized the linear wear rates would be lower than those published for cobalt-chrome and standard polyethylene. We retrospectively reviewed a select series of 56 THAs in a relatively young, active patient population utilizing oxidized zirconium femoral heads and highly cross-linked polyethylene acetabular liners. Femoral head penetration was determined using the Martell computerized edge-detection method. All patients were available for 2-year clinical and radiographic followup. True linear wear was 4 ?m/year (95% confidence intervals, ± 59 ?m/year). The early wear rates in this cohort of relatively young, active patients were low and we believe justify the continued study of these alternative bearing surfaces. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18946711

  20. Reasons of Revision for First-Generation Highly Crosslinked Polyethylenes

    PubMed Central

    Kurtz, Steven M.; Medel, Francisco; MacDonald, Daniel; Parvizi, Javad; Kraay, Matthew; Rimnac, Clare

    2010-01-01

    Over a ten-year period, we prospectively evaluated the reasons for revision for contemporary and highly crosslinked polyethylene formulations in a multicenter retrieval program. 212 consecutive retrievals were classified as conventional gamma-inert sterilized liners (n=37), annealed (Crossfire™, n=72), or remelted (Longevity™, XLPE, Durasul; n=93). The most frequent reasons for revision were loosening (35%), instability (28%) and infection (21%) and were not related to polyethylene formulation (p = 0.17). Annealed and remelted liners had comparable linear penetration rates (0.03 and 0.04 mm/y, respectively, on average) and were significantly lower than conventional retrievals (0.11 mm/y; p ? 0.0005). This retrieval study including first-generation highly crosslinked liners demonstrated lower wear than conventional polyethylene. While loosening remained the most prevalent reason for revision, we could not demonstrate a relationship between wear and loosening. The long-term clinical performance of first-generation highly crosslinked remains promising, based on the mid-term outcomes of the components documented in this study. PMID:20541895

  1. Screening of stabilized crosslinked polyethylene using a novel wear tester.

    PubMed

    Hoffmann, M; Gonzalez-Mora, V; Chiesa, R; Cigada, A; Stroosnijder, M F

    2002-01-01

    A novel pin-on-disk type wear tester is described allowing a rapid screening of different types of polyethylene under both unidirectional and multidirectional sliding motion. The wear of four polyethylene materials sliding against a roughened CoCrMo alloy was evaluated: a non-irradiated UHMWPE, a UHMWPE irradiated with a dose of 25 kGy in air, and two types of crosslinked UHMWPE (100 kGy, air), which were subjected to a stabilization heat treatment in nitrogen at 155 degrees C for 72 hours (XLPE I) and in water at 130 degrees C for 72 hours (XLPE II), respectively.Under multidirectional sliding conditions both types of XLPE exhibited significantly less wear with respect to the 25 kGy irradiated UHMWPE and the non-irradiated UHMWPE, even under the rough counterface conditions applied. Under unidirectional sliding motion both types of XLPE exhibited the highest wear of all materials tested, because the orientation hardening effect acting under linear lubricated condition is less pronounced for crosslinked polyethylene. PMID:12652033

  2. Orbital roof reconstruction using porous polyethylene sheet with embedded titanium.

    PubMed

    Kim, Sang Wha; Han, Hyun Ho; Oh, Deuk Young; Moon, Suk Ho; Lee, Jung Ho; Rhie, Jong Won; Ahn, Sang Tae

    2012-11-01

    Calvarial defects, including the orbital roof defect that occurs after trauma or oncologic resection, require immediate reconstruction to avoid complications such as enophthalmos, diplopia, and transmission of the cerebral pulse to the eye. In these cases, autologous bone grafts or various alloplastic materials have been used.Between January 2010 and December 2010, 5 patients underwent surgery for orbital roof reconstruction using porous polyethylene sheet with embedded titanium, which was developed for reconstruction of inferomedial wall of the orbit. One patient underwent surgery because of tumor excision; the other patients, because of trauma. Two patients had intracranial hemorrhage and 3 patients had a defect in the supraorbital rim. We reconstructed the supraorbital rim and the orbital roof using a combination of calvarial bone graft and the porous polyethylene sheet with embedded titanium. The sheet was bended and trimmed according to the shape of the orbital defect, and it was fixed on the remaining adjacent bone using a microplate.There were no complications during the follow-up period. The patients were satisfied with the external appearance.In conclusion, the orbital roof reconstruction using porous polyethylene sheet with embedded titanium was an easy and a time-efficient procedure with satisfactory results. PMID:23172508

  3. Protein adsorption onto ceramic surfaces.

    PubMed

    Takami, Y; Yamane, S; Makinouchi, K; Otsuka, G; Glueck, J; Benkowski, R; Nosé, Y

    1998-04-01

    Ceramics seldom have been used as blood-contacting materials. However, alumina ceramic (Al2O3) and polyethylene are incorporated into the pivot bearings of the Gyro centrifugal blood pump. This material combination was chosen based on the high durability of the materials. Due to the stagnant flow that often occurs in a continuous flow condition inside a centrifugal pump, pivot bearing system is extremely critical. To evaluate the thombogenicity of pivot bearings in the Gyro pump, this study sought to investigate protein adsorption, particularly albumin, IgG, fibrinogen, and fibronectin onto ceramic surfaces. Al2O3 and silicon carbide ceramic (SiC) were compared with polyethylene (PE) and polyvinylchloride (PVC). Bicinchoninic acid (BCA) protein assay revealed that the amount of adsorbed proteins onto Al2O3 and SiC was significantly less than that on PVC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that numerous proteins adsorbed onto PVC compared to PE, Al2O3, and SiC. Identification of adsorbed proteins by Western immunoblotting revealed that the adsorption of albumin was similar on all four materials tested. Western immunoblotting also indicated lesser amounts of IgG, fibrinogen, and fibronectin on Al2O3 and SiC than on PE and PVC. In conclusion, ceramics (Al2O3 and SiC) are expected to be thromboresistant from the viewpoint of protein adsorption. PMID:9511095

  4. Study of Optical and Structure Properties of Polyester (PET) and Copolyester (PETG) Fibers by Interferometry

    Microsoft Academic Search

    K. A. El-Farahaty; A. M. Sadik; A. M. Hezma

    2007-01-01

    In this article results on the influence of drawing on the optical and structure properties of polyester (polyethylene terephthalate) and copolyester (glycol-modified polyethylene terephthalate) (4 wt% of ethylene glycol) fibers are reported. Refractive indices, intrinsic birefringence, mean polarizability per unit volume, optical orientation function, density, volume fraction of crystalline material, weight fraction crystallinity, and volume fraction of amorphous and work per

  5. Five-year comparative study of highly cross-linked (crossfire) and traditional polyethylene.

    PubMed

    Rajadhyaksha, Amar D; Brotea, Cristian; Cheung, Yeukkei; Kuhn, Courtney; Ramakrishnan, Rama; Zelicof, Steven B

    2009-02-01

    The purpose of this study was to compare the linear penetration rates of a highly cross-linked ultra-high-molecular-weight polyethylene to traditional polyethylene. Twenty-seven highly cross-linked components were matched to 27 traditional polyethylene components with respect to age, sex, body mass index, and activity level. Each group was followed up for a mean of approximately 6 years. Linear penetration was measured using Martell's computerized technique (J Bone Joint Surg Am 1997;79:1635). The mean total penetration was 0.283 mm (SD, 0.253) for the highly cross-linked group. The mean total penetration for the traditional polyethylene was 0.696 mm (SD, 0.402). This difference was highly significant (P < or = .001). Our experience demonstrates a 59% reduction in total penetration of highly cross-linked polyethylene when compared with traditional polyethylene at a minimum of 5 years. PMID:18534491

  6. Visualization of O-GlcNAc Glycosylation Stoichiometry and Dynamics using Resolvable Poly(ethylene glycol) Mass Tags

    PubMed Central

    Clark, Peter M.; Rexach, Jessica E.; Hsieh-Wilson, Linda C.

    2014-01-01

    O -GlcNAc glycosylation is a dynamic protein posttranslational modification with roles in processes such as transcription, cell cycle regulation, and metabolism. Detailed mechanistic studies of O-GlcNAc have been hindered by a lack of methods for measuring O-GlcNAc stoichiometries and the interplay of glycosylation with other posttranslational modifications. We recently developed a method for labeling O-GlcNAc-modified proteins with resolvable poly(ethylene glycol) mass tags. This mass tagging approach enables the direct measurement of glycosylation stoichiometries and the visualization of distinct O-GlcNAc-modified subpopulations. Here, we describe protocols for labeling O-GlcNAc glycoproteins in cell lysates with mass tags. PMID:24391098

  7. Water uptake, transport and structure characterization in poly(ethylene glycol) diacrylate hydrogels

    Microsoft Academic Search

    Yuan-Hsuan Wu; Ho Bum Park; Teruhiko Kai; Benny D. Freeman; Douglass S. Kalika

    2010-01-01

    Crosslinked poly(ethylene glycol) (PEG) free-standing films were prepared by UV-induced photopolymerization of poly(ethylene glycol) diacrylate (PEGDA) crosslinker in the presence of varying amounts of water or monofunctional poly(ethylene glycol) acrylate (PEGA). The crosslinked PEGDA films exhibited polymerization induced phase separation (PIPS) when the water content of the prepolymerization mixture was greater than 60wt%. These phase separated films contain pores that

  8. Synthesis and characterization of novel comb-type amphiphilic graft copolymers containing polypropylene and polyethylene glycol

    Microsoft Academic Search

    Murat Balc?; Abdulkadir All?; Baki Hazer; Olgun Güven; Kevin Cavicchi; Mukerrem Cakmak

    2010-01-01

    Amphiphilic comb-type graft copolymers containing polypropylene (PP) and polyethylene glycol (PEG) have been prepared. Polypropylene-g-polyethylene glycol comb-type thermoplastic amphiphilic copolymers were synthesized by the reaction between chlorinated polypropylene\\u000a and polyethylene glycol in the presence of a base via a “grafting to” technique. A series of graft copolymers containing PEGs\\u000a with molecular weights of 600 and 2,000 Da in the range of

  9. Five-Year Comparative Study of Highly Cross-Linked (Crossfire) and Traditional Polyethylene

    Microsoft Academic Search

    Amar D. Rajadhyaksha; Cristian Brotea; Yeukkei Cheung; Courtney Kuhn; Rama Ramakrishnan; Steven B. Zelicof

    2009-01-01

    The purpose of this study was to compare the linear penetration rates of a highly cross-linked ultra–high-molecular-weight polyethylene to traditional polyethylene. Twenty-seven highly cross-linked components were matched to 27 traditional polyethylene components with respect to age, sex, body mass index, and activity level. Each group was followed up for a mean of approximately 6 years. Linear penetration was measured using

  10. Gas chromatographic study of the volatile products from co-pyrolysis of coal and polyethylene wastes

    Microsoft Academic Search

    A Dom??nguez; C. G Blanco; C Barriocanal; R Alvarez; M. A D??ez

    2001-01-01

    The aim of this study was to determine the volatile products distribution of co-processing of coal with two plastic wastes, low-density polyethylene from agriculture greenhouses and high-density polyethylene from domestic uses, in order to explain the observed decrease in coal fluidity caused by polyethylene waste addition. Polymeric materials, although they are not volatile themselves, may be analysed by gas chromatography

  11. Polyethylene waste form: Evaluation of explosion and fire hazards. Final report

    Microsoft Academic Search

    A. Block-Bolten; D. Olson; P. A. Persson; F. Sandstrom

    1991-01-01

    A Proposed polyethylene waste form consists of a hot-extruded, non-porous mix of equal weights of polyethylene and granular sodium nitrate, slightly contaminated with heavy metal salts. The experiments and theoretical analysis detailed in this report were done to evaluate the risks for self-accelerating thermal decomposition, explosion, and detonation of polyethylene mixed with sodium nitrate. The study included the proposed waste

  12. Viscosity prediction of polyethylene glycol–dextran–water solutions used in aqueous two-phase systems

    Microsoft Academic Search

    Ufuk Gündüz

    2000-01-01

    The dynamic viscosities of aqueous polyethylene glycol and dextran, and poly(ethylene glycol)–dextran–water solutions were measured at temperatures of 30, 50 and 70°C. The poly(ethylene glycol) having a relative molecular mass of 8000, and dextran samples with relative molecular masses of 37?500, 494?000, and 2?000?000 were used. A one-parameter Grunberg-like equation proposed earlier by us was used for estimating the values

  13. The extractability of phenolic antioxidants into water and organic solvents from polyethylene pipe materials – Part I

    Microsoft Academic Search

    K. Thörnblom; M. Palmlöf; T. Hjertberg

    2011-01-01

    Three commercial anti-oxidant systems have been studied regarding migration and chemical reaction in different polyethylene pipe materials during extraction in organic solvents and in hot water, 95–100 °C, under anaerobic and aerobic conditions. Materials made of crosslinked and non-crosslinked high density polyethylene, low density polyethylene and blends thereof were stabilized with different phenolic antioxidants: Irganox 1330, Irganox 1010, and Irganox 1076.

  14. Patterning Functional Proteins with High Selectivity for Biosensor Applications

    Microsoft Academic Search

    Nan Li; Chih-Ming Ho

    2008-01-01

    In this article, two-dimensional hexamethyldisilazane (HMDS) micropatterns were generated on glass substrates using photolithographic techniques for the assembly of functional proteins. The non-HMDS patterned areas were backfilled with poly(ethylene glycol) (PEG) silane to reduce the nonspecific protein adsorption. The hydrophobic methyl-terminated HMDS monolayer was verified to be favorable for physical protein adsorption with bovine serum albumin (BSA). The PEG-silane derivatized

  15. Aspergillus oryzae alpha-amylase partition in potassium phosphate-polyethylene glycol aqueous two-phase systems.

    PubMed

    Porfiri, María Cecilia; Picó, Guillermo; Romanini, Diana; Farruggia, Beatriz

    2011-07-01

    The aim of this work is to study the partitioning of alpha-amylase from Aspergillus oryzae in polyethylene glycol-potassium phosphate systems formed by polymers of different molecular masses with different total concentrations, several NaCl concentrations and different volume ratio between the phases and at different temperatures. The enzyme was partitioned towards the top phase in the 2000-molecular-mass polyethylene glycol systems and towards the bottom phase in the other systems analyzed with higher molecular mass. The protein-medium interaction parameter (A) was determined; it increased in the same way as PEG molecular mass. The enthalpic and entropic changes found, in general, were negative and were shown to be associated by an entropic-enthalpic compensation effect suggesting that the ordered water structure in the chain of polyetyleneglycol plays a role in protein partition. The recovery in each of the phases was calculated in order to choose the best systems to be applied to enzyme isolation either from a polymer-rich or a polymer-poor phase. Enzymatic activity, circular dichroism and fluorescence were studied for the protein alone and in the presence of the different phases of the aqueous two-phase systems (ATPSs) in order to understand how they affect the enzymatic structure and the role of the protein-polymer interaction in the partitioning process. Secondary structure is not affected, in general, by the presence of the phases that do affect the enzymatic activity; therefore, there should be a change in the tertiary structure in the enzyme active site. These changes are more important for PEG 8000 than for PEG 2000 systems according to the results of the quenching of the intrinsic fluorescence. In a bio-separation process, the A. oryzae alpha-amylase could be isolated with ATPSs PEG 2000/Pi or PEG 8000/Pi with a high recovery, in the top or bottom phases, respectively. PMID:21397633

  16. An improved cryosection method for polyethylene glycol hydrogels used in tissue engineering.

    PubMed

    Ruan, Jia-Ling; Tulloch, Nathaniel L; Muskheli, Veronica; Genova, E Erin; Mariner, Peter D; Anseth, Kristi S; Murry, Charles E

    2013-10-01

    The high water content of hydrogels allows these materials to closely mimic the native biological extracellular conditions, but it also makes difficult the histological preparation of hydrogel-based bioengineered tissue. Paraffin-embedding techniques require dehydration of hydrogels, resulting in substantial collapse and deformation, whereas cryosectioning is hampered by the formation of ice crystals within the hydrogel material. Here, we sought to develop a method to obtain good-quality cryosections for the microscopic evaluation of hydrogel-based tissue-engineered constructs, using polyethylene glycol (PEG) as a test hydrogel. Conventional sucrose solutions, which dehydrate cells while leaving extracellular water in place, produce a hydrogel block that is brittle and difficult to section. We therefore replaced sucrose with multiple protein-based and nonprotein-based solutions as cryoprotectants. Our analysis demonstrated that overnight incubation in bovine serum albumin (BSA), fetal bovine serum (FBS), polyvinyl alcohol (PVA), optimum cutting temperature (OCT) compound, and Fisher HistoPrep frozen tissue-embedding media work well to improve the cryosectioning of hydrogels. The protein-based solutions give background staining with routine hematoxylin and eosin, but the use of nonprotein-based solutions PVA and OCT reduces this background by 50%. These methods preserve the tissue architecture and cellular details with both in vitro PEG constructs and in constructs that have been implanted in vivo. This simple hydrogel cryosectioning technique improves the methodology for creation of good-quality histological sections from hydrogels in multiple applications. PMID:23448137

  17. Poly(ethylene glycol) interfaces: an approach for enhanced performance of microfluidic systems.

    PubMed

    Popat, Ketul C; Desai, Tejal A

    2004-04-15

    Microfluidic systems are extensively used platform for analytical and therapeutic applications. One of the major problems encountered in these systems is the loss of material due to non-specific surface interactions. When biological solutions are flowed through microchannels, they tend to adsorb on the surface due to the negative charge of the surface. This results in a reduced efficiency of the system which can be critical in sensitive biological analysis. Poly(ethylene glycol) (PEG) is known to form non-fouling interfaces on silicon and glass which are common materials used in microfluidic systems. The most common approach for modifying silicon/glass with PEG involves a solution phase protocol. Since the micro/nanofluidic systems have channel sizes ranging from hundreds of microns to submicron with variety of complicated network, this surface modification approach is not sufficient in forming uniform, conformal, and ultrathin films on the surface. Due to the enclosed features in these systems, the properties of liquids such as viscosity and surface tension play an important role in the clogging and eventually biofouling of these microchannels. Hence, we have developed a solvent-free vapor deposition protocol for modifying silicon/glass surfaces with PEG. Various concentrations of protein solutions were flowed through unmodified and PEG-modified glass microcapillaries of different lengths at different flow rates. PEG surfaces formed on silicon have shown 80% reduction in protein adsorption in static conditions. PMID:15018959

  18. Polyethylene glycol (PEG)-Poly(N-isopropylacrylamide) (PNIPAAm) based thermosensitive injectable hydrogels for biomedical applications.

    PubMed

    Alexander, Amit; Ajazuddin; Khan, Junaid; Saraf, Swarnlata; Saraf, Shailendra

    2014-11-01

    Protein and peptide delivery by the use of stimuli triggered polymers remains to be the area of interest among the scientist and innovators. In-situ forming gel for the parenteral route in the form of hydrogel and implants are being utilized for various biomedical applications. The formulation of gel depends upon factors such as temperature modulation, pH changes, the presence of ions and ultra-violet irradiation, from which drug is released in a sustained and controlled manner. Among various stimuli triggered factors, thermoresponsive is the most potential one for the delivery of protein and peptides. Poly(ethylene glycol) (PEG) based copolymers play a crucial role as a biomedical material for biomedical applications, because of its biocompatibility, biodegradability, thermosensitivity and easy controlled characters. This review, stresses on the physicochemical property, stability and compositions prospects of smart thermoresponsive polymer specifically, PEG/Poly(N-isopropylacrylamide) (PNIPAAm) based thermoresponsive injectable hydrogels, recently utilized for biomedical applications. PEG-PNIPAAm based hydrogel exhibits good gelling mechanical strength and minimizes the initial burst effect of the drug. In addition, upon changing the composition and proportion of the copolymer molecular weight and ratio, the gelling time can be reduced to a great extent providing better sol-gel transition. The hydrogel formed by the same is able to release the drug over a long duration of time, meanwhile is also biocompatible and biodegradable. Manuscript will give the new researchers an idea about the potential and benefits of PNIPAAm based thermoresponsive hydrogels for the biomedical application. PMID:25092423

  19. Manufacturing, structure and properties of recycled polyethylene terephthalate /liquid crystal polymer/montmorillonite clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Japins, Guntis; Berzina, Rita; Zicans, Janis; Merijs Meri, Remo; Ivanova, Tatjana; Kalkis, Valdis; Reinholds, Ingars

    2013-12-01

    Polyethylene terephthalate (PET)/liquid crystal polymer (LCP)/monthmorillonite clay (MMT) compositions were obtained by melt mixing. Their mechanical, structural, rheological and thermal properties were investigated.

  20. Conserving Waterlogged Rope: A Review of Traditional Methods and Experimental Research with Polyethylene Glycol 

    E-print Network

    McCaskill, Jennifer R.

    2010-01-16

    and Conservation CRL Conservation Research Laboratory DBTDA dibutyltin diacetate EDTA ethylenediaminetetraacetic acid INA Institute of Nautical Archaeology MTMS methyltrimethoxysilane PEG polyethylene glycol PVA polyvinyl acetate PVP polyvinyl pyrrolidone...

  1. Cementitious building material incorporating end-capped polyethylene glycol as a phase change material

    DOEpatents

    Salyer, Ival O. (Dayton, OH); Griffen, Charles W. (Mason, OH)

    1986-01-01

    A cementitious composition comprising a cementitious material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the compositions are useful in making pre-formed building materials such as concrete blocks, brick, dry wall and the like or in making poured structures such as walls or floor pads; the glycols can be encapsulated to reduce their tendency to retard set.

  2. Interaction of proteins with weak amphoteric charged membrane surfaces: effect of pH

    Microsoft Academic Search

    Hidetoshi Matsumoto; Yoshiyuki Koyama; Akihiko Tanioka

    2003-01-01

    Weak amphoteric charged membranes were prepared by the graft copolymerization of poly(ethylene glycol) (PEG) derivatives with pendant ionizable groups onto polyethylene (PE) porous membranes. Two types of weak amphoteric charged membranes and two types of weak single charged membranes were prepared. The pH dependence of the protein (fluorescein isothiocyanate-labeled bovine serum albumin, FITC-BSA) adsorption onto the membranes was investigated by

  3. Catalytic degradation of high density polyethylene using zeolites.

    PubMed

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

    2001-01-01

    Plastic wastes, which cause a serious environmental problem in urban areas, can serve as sources of energy. Catalytic treatment of High Density Polyethylene (HDPE) has shown that the degradation of HDPE resulted in the production of a stream of gaseous hydrocarbons varied in the range C1-C8. The degradation was carried out using diluted forms of zeolites ZSM-5, USY and Mordenite (MORD) using a fluidized bed reactor (FBR). Effect of coke formation on the activity of the catalysts was screened by thermogravimetric (TGA). ZSM-5 showed a significant resistance to deactivation because of the nature of its small pore size compared with USY and MORD. PMID:11382018

  4. Investigation of crosslinking behaviour of silane grafted polyethylene through rheology

    NASA Astrophysics Data System (ADS)

    Obr, Ales; Zatloukal, Martin

    2013-04-01

    In this work the crosslinking behaviour of two silane-grafted polyethylenes was investigated with respect to time and temperature by using dynamic rheological measurements. It has been found that inhomogeneous character of the crosslinking reaction takes place in both tested samples. By utilization of G'-G" crossover method, it has been found that the sample with initially distinct crosslinking state and short critical crosslinking reaction time has high tendency to create small gels during production of hot water pipes. It has also been revealed that the temperature dependence of the critical time, at which the crosslinking speed is the highest, shows an Arrhenius-type behaviour.

  5. Investigation of the fire endurance of borated polyethylene shielding material

    SciTech Connect

    Foote, K.L.

    1988-06-17

    We conducted nine experiments to investigate the fire endurance of a borated polyethylene shielding material to be used in the Engineering Demonstration System. Several chemistry tests were also done. The shielding material was found to melt at 93.5/degree/C, decompose at 230/degree/C, and ignite at 350/degree/C. Five fire tests were done in a realistic configuration and four tests in a pessimistic configuration. The material easily passed all nine tests. In each case, the shielding material never reached ignition temperature and was found acceptable in this proposed application. 7 refs., 10 figs., 3 tabs.

  6. Single-molecule spectroscopy of uniaxially oriented terrylene in polyethylene.

    PubMed

    Butter, Jacqueline Y P; Crenshaw, Brent R; Weder, Christoph; Hecht, Bert

    2006-01-16

    Single terrylene molecules doped into linear low-density polyethylene can be oriented by tensile deformation of the matrix. In measurements on ensembles at ambient and on single terrylene molecules at cryogenic temperature, strong orientation along the stretching direction was observed by polarization-resolved confocal microscopy. At cryogenic temperatures narrow and spectrally stable zero-phonon lines were found. The low saturation intensity of 0.07 W cm(-2) is consistent with an uniaxial orientation of terrylene in the sample plane. PMID:16363013

  7. Calculated minimum critical masses of {sup 239}Pu homogeneously mixed with polyethylene moderator

    SciTech Connect

    Gundy, L.M.; Goslen, A.Q.

    1997-06-01

    The minimum critical masses of Plutonium 239 in a polyethylene moderator were calculated as a function of plutonium density for several polyethylene densities (various void fractions). This study has applications for solid transuranic (TRU) waste and for plutonium scrap dissolving operations where polyethylene bags may be present within the cans to be dissolved. Polyethylene is usually present in TRU waste as a result of glovebox bagout operations and as liners in 55 gallon drums. The methodology utilized the SCALE driver CSAS1X. MCNP4A with ENDF/B-V was also used as an independent check due to the lack of critical experiments for polyethylene moderator. For TRU solid waste, tests with 55 gallon drums indicate that polyethylene bagging cannot be tightly stuffed to a volume fraction greater than 15.5%. To allow for settling, calculations were conducted for 20% and 50% polyethylene volume fractions as well as for full density for comparison. The effects of 10% concrete or steel mixed with 20% polyethylene were also evaluated. Since water egress into underground solid waste containers would be possible, additional calculations evaluated critical masses of water in polyethylene moderator. Calculated critical masses for the various moderators were determined for a range of plutonium concentrations. For full density polyethylene, the minimum critical plutonium mass is about 345 grams (at 30 grams per liter) versus 510 for water. Added concrete substantially decreases the critical mass, and added steel substantially increases the critical mass. This study indicates that in some situations the minimum critical plutonium mass in polyethylene can be less than that of metal in water (about 510 grams). TRU waste fissile limits are usually based on safe masses determined from plutonium in water so that this result has obvious implications on criticality safety. 1 fig.

  8. Improved Adhesion, Growth and Maturation of Vascular Smooth Muscle Cells on Polyethylene Grafted with Bioactive Molecules and Carbon Particles

    PubMed Central

    Parizek, Martin; Kasalkova, Nikola; Bacakova, Lucie; Slepicka, Petr; Lisa, Vera; Blazkova, Martina; Svorcik, Vaclav

    2009-01-01

    High-density polyethylene (PE) foils were modified by an Ar+ plasma discharge and subsequent grafting with biomolecules, namely glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C) or BSA and C (BSA + C). As revealed by atomic force microscopy (AFM), goniometry and Rutherford Backscattering Spectroscopy (RBS), the surface chemical structure and surface morphology of PE changed dramatically after plasma treatment. The contact angle decreased for the samples treated by plasma, mainly in relation to the formation of oxygen structures during plasma irradiation. A further decrease in the contact angle was obvious after glycine and PEG grafting. The increase in oxygen concentration after glycine and PEG grafting proved that the two molecules were chemically linked to the plasma-activated surface. Plasma treatment led to ablation of the PE surface layer, thus the surface morphology was changed and the surface roughness was increased. The materials were then seeded with vascular smooth muscle cells (VSMC) derived from rat aorta and incubated in a DMEM medium with fetal bovine serum. Generally, the cells adhered and grew better on modified rather than on unmodified PE samples. Immunofluorescence showed that focal adhesion plaques containing talin, vinculin and paxillin were most apparent in cells on PE grafted with PEG or BSA + C, and the fibres containing ?-actin, ?-actin or SM1 and SM2 myosins were thicker, more numerous and more brightly stained in the cells on all modified PE samples than on pristine PE. An enzyme-linked immunosorbent assay (ELISA) revealed increased concentrations of focal adhesion proteins talin and vinculin and also a cytoskeletal protein ?-actin in cells on PE modified with BSA + C. A contractile protein ?-actin was increased in cells on PE grafted with PEG or Gly. These results showed that PE activated with plasma and subsequently grafted with bioactive molecules and colloidal C particles, especially with PEG and BSA + C, promotes the adhesion, proliferation and phenotypic maturation of VSMC. PMID:20057950

  9. Temperature and rate dependent finite strain behavior of poly(ethylene terephthalate) and poly(ethylene terephthalate)-glycol above the glass transition temperature

    E-print Network

    Dupaix, Rebecca B. (Rebecca Brown), 1976-

    2003-01-01

    Poly(ethylene terephthalate) is widely used for consumer products such as drawn fibers, stretched films, and soda bottles. Much of its commercial success lies in the fact that it crystallizes at large strains during warm ...

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

    PubMed

    Khorov, O G; Struk, V A; Novoseletski?, V A

    2013-01-01

    The objective of the present study was the comparative assessment of the influence of titanium and high-density ultrahigh molecular weight polyethylene (HDMPE) on the selected biochemical and immunological properties of blood and morphological features of the middle ear tissues in experimental animals. A total of 35 rabbits used were allocated to 3 groups. Groups 1 and 2 included 15 animals each. They were involved in three series of experiments (5 animals per series lasting 15, 60, and 90 days). Group 3 was comprised of 5 animals. Prosthetic treatment of auditory ossicles was performed using implants from modified high-density ultrahigh molecular weight polyethylene (group 1) and titanium implants (group 2). Control animals (group 3) remained intact. There were no significant difference between total bilirubin, AsAT, glucose, creatinine, and total protein levels in blood plasma at different time-points after surgery. HDMPE turned out to have no appreciable effect on immunological characteristics and morphological features of the soft tissues lining tympanic bulla. It is concluded that HDMPE may serve as a material for the fabrication of prostheses of the auditory ossicle chain. PMID:23528461

  11. 75 FR 40776 - Polyethylene Terephthalate Film, Sheet and Strip From the United Arab Emirates: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ...Polyethylene Terephthalate Film, Sheet and Strip From the United Arab Emirates: Extension of Time Limit for Preliminary Results of...polyethylene terephthalate film, sheet and strip from the United Arab Emirates (UAE) for the period November 06, 2008 through...

  12. 76 FR 45508 - Polyethylene Terephthalate Film, Sheet and Strip From the United Arab Emirates: Extension of Time...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-29

    ...Polyethylene Terephthalate Film, Sheet and Strip From the United Arab Emirates: Extension of Time Limit for Preliminary Results of...polyethylene terephthalate film, sheet and strip from the United Arab Emirates (UAE) for the period November 01, 2009,...

  13. 78 FR 14266 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Notice of Correction to the Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Notice of Correction...antidumping duty order on polyethylene terephthalate film, sheet, and strip (PET Film) from Taiwan.\\1\\ The period of review...

  14. 40 CFR 721.10472 - 1,3-Benzenedimethanamine, polymers with epichlorohydrin-polyethylene glycol reaction products.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Uses for Specific Chemical Substances § 721...epichlorohydrin-polyethylene glycol reaction products. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...epichlorohydrin-polyethylene glycol reaction products...

  15. Bisacodyl reduces the volume of polyethylene glycol solution required for bowel preparation

    Microsoft Academic Search

    Warwick J. Adams; Allan P. Meagher; David Z. Lubowski; Denis W. King

    1994-01-01

    PURPOSE: This study was designed to compare the efficacy and patient tolerance of standard orthograde bowel preparation using 4 liters of polyethylene glycol solution with only 2 liters of polyethylene glycol preceded by the stimulant laxative bisacodyl. METHODS: Three hundred eighty-two consecutive patients undergoing outpatient colonoscopy under two surgeons over a six-month period were randomized to receive one of the

  16. Time-Resolved Small-Angle Neutron Scattering Study of Polyethylene Crystallization from Solution

    E-print Network

    Wang, Howard "Hao"

    Time-Resolved Small-Angle Neutron Scattering Study of Polyethylene Crystallization from Solution-resolved small-angle neutron scattering (TR-SANS), the crystal- lization kinetics of polyethylene from deuterated (PE); neutron scattering INTRODUCTION Crystallization of long-chain molecules has been extensively

  17. Evaluation of thermal and mechanical properties of recycled polyethylene modified bitumen

    Microsoft Academic Search

    Cristina Fuentes-Audén; Juan Andrés Sandoval; Abel Jerez; Francisco J. Navarro; Francisco J. Martínez-Boza; Pedro Partal; Críspulo Gallegos

    2008-01-01

    This paper deals with the influence that polymer concentration exerts on the rheological and thermal properties and microstructure of recycled polyethylene modified bitumen. With this aim, a recycled polyethylene was used as modifying agent to improve the mechanical characteristics of a 150\\/200 penetration grade bitumen. The evolution of microstructure and thermal and rheological behaviour of the blends has been followed

  18. MEASUREMENT OF HEAT TRANSFER DURING DROP-WISE CONDENSATION OF WATER ON POLYETHYLENE

    E-print Network

    Khandekar, Sameer

    MEASUREMENT OF HEAT TRANSFER DURING DROP-WISE CONDENSATION OF WATER ON POLYETHYLENE Gagan Deep of Technology Kanpur, Kanpur (UP) India Heat transfer coefficients associated with drop-wise condensation distribution of temperature during drop-wise condensation over a polyethylene substrate was measured using

  19. P-7 / D. R. Cairns P-7: Wear Resistance of Indium Tin Oxide Coatings on Polyethylene

    E-print Network

    Cairns, Darran

    P-7 / D. R. Cairns P-7: Wear Resistance of Indium Tin Oxide Coatings on Polyethylene Terephthalate The wear mechanisms of the Indium Tin Oxide (ITO) coated Polyethylene Terephthalate (PET) topsheet used for resistive touchscreen applications is Indium Tin Oxide (ITO). The TCO layer must have high

  20. Electrical Properties of 10 MeV Electron Beam Irradiated and Aged Low Density Polyethylene

    Microsoft Academic Search

    Farhood Ziaie; Farshid Ziaee

    2011-01-01

    Polymers play a very important role in electrical systems as insulation materials. The microscopic failures occurring in the polymer under working conditions will be important in its required characteristics. In this work we focused on the effects of accelerated aging on the electrical properties of low density polyethylene (LDPE) and crosslinked polyethylene (XLDPE). The samples of LDPE were prepared in

  1. Ageing Effect on the Properties of Tri-Layer Polyethylene Film Used as Greenhouse Roof

    Microsoft Academic Search

    Abdelkader Dehbi; Abdel-Hamid I. Mourad; Amar Bouaza

    2011-01-01

    This work aims at studying the degradable effect of natural and artificial ageing on tri-layer polyethylene films used as greenhouse cover in the North Africa environment. The film was supplied by Agrofilm and made of low density polyethylene (LDPE), containing additives (e.g., color and infrared IR and ultraviolet UV stabilizers). This film was used to build a real greenhouse located

  2. Transferability of ASTM\\/NIST alanine–polyethylene recipe at ISS

    Microsoft Academic Search

    C. De Angelis; P. Fattibene; S. Onori; E. Petetti; A. Bartolotta; A. Sansone Santamaria

    2000-01-01

    Alanine–polyethylene solid state dosimeters were prepared at Istituto Superiore di Sanità (ISS) following the recipe proposed by National Institute of Standards and Technology (NIST) with the goal of testing its transferability. Dosimeters were prepared using 95% alanine and 5% polyethylene, by weight. They are rugged and of increased sensitivity, repeatability and reproducibility as respect to the ISS alanine-paraffin pellets. Reproducibility

  3. Acute Repair of Crushed Guinea Pig Spinal Cord by Polyethylene Glycol

    E-print Network

    Shi, Riyi

    Acute Repair of Crushed Guinea Pig Spinal Cord by Polyethylene Glycol RIYI SHI AND RICHARD B of crushed guinea pig spinal cord by polyethylene glycol. J. Neurophysiol. 81: 2406­2414, 1999. We have studied the responses of adult guinea pig spinal cord white matter to a standardized compression within

  4. Contamination-free system for cross-linked polyethylene cable insulation

    Microsoft Academic Search

    H. Takemori

    1976-01-01

    A contamination-free system which minimizes voids and foreign matter in the final cable product was developed. A consistent exhaustive system from polymerization of polyethylenes to extrusion of foreign matters, such as resins, rusted iron, dust particles and lint was studied and laboratory controls of the processes were implemented. As a result, the quality of the polyethylene raw material has been

  5. Impact of gamma sterilization on clinical performance of polyethylene in the knee

    Microsoft Academic Search

    John P. Collier; Daniel K. Sperling; John H. Currier; Lauren C. Sutula; Kenneth A. Saum; Michael B. Mayor

    1996-01-01

    Damage and rapid wear of the ultrahigh-molecular-weight polyethylene bearings of knee components continue to be major sources of failure of knee prostheses. Despite considerable research into the roles of design, polyethylene thickness and quality, and component alignment, the source of the rapid wear failures has remained a mystery. This study documents elevated oxidation resulting from the use of gamma sterilization

  6. The Effect of Entrapped Bone Particles on the Surface Morphology and Wear of Polyethylene

    Microsoft Academic Search

    Kimberly D. Mimnaugh; Jian Q. Yao; Michel P. Laurent; Roy Crowninshield; James J. Mason; Cheryl Blanchard

    2009-01-01

    Clinically retrieved highly cross-linked ultrahigh molecular weight polyethylene (HXPE) acetabular liners have demonstrated scratching, whereas conventional ultrahigh-molecular-weight polyethylene (UHMWPE) implants show a smoother surface early after implantation. In the present study, the potential of bone particles and soft tissues, rather than cement, to scratch the articular surface of HXPE and UHMWPE (? radiated) acetabular components was evaluated; multiple bone particles

  7. 2006 Otto Aufranc Award Paper: significance of in vivo degradation for polyethylene in total hip arthroplasty.

    PubMed

    Kurtz, Steven M; Hozack, William J; Purtill, James J; Marcolongo, Michele; Kraay, Matthew J; Goldberg, Victor M; Sharkey, Peter F; Parvizi, Javad; Rimnac, Clare M; Edidin, Avram A

    2006-12-01

    Our research group developed an implant retrieval program to study in vivo degradation of polyethylene. We now have evidence to support our hypothesis that degradation of radiation-sterilized polyethylene occurs in the body for not only historical gamma air sterilized liners, but also for conventional gamma inert sterilized (ArCom) and annealed highly crosslinked polyethylene (Crossfire) liners as well. Our research has also led to the discovery that the most severe manifestations of in vivo oxidation typically occur in regions of the liner experiencing minimal wear, such as the rim of the component, where the body fluids (containing oxidizing species) have access to the polyethylene. Our data from historical, ArCom, and Crossfire retrievals all point to a similar scenario in which the femoral head limits the in vivo oxidation of polyethylene at the bearing surface. Consequently, provided rim impingement does not occur, and the polyethylene locking mechanisms remain relatively isolated from oxidizing fluid, in vivo oxidation does not seem to be clinically important in the first 10 years of implantation for conventional gamma sterilized polyethylene. We conclude that in vivo degradation should be included among the list of potential long-term failure modes for modular polyethylene components for total hip arthroplasty. PMID:17031310

  8. Association of hydrophobically-modified poly(ethylene glycol) with fusogenic liposomes

    E-print Network

    Auguste, Debra T.

    Association of hydrophobically-modified poly(ethylene glycol) with fusogenic liposomes Debra T interactions to shield liposomes by incorporating multiple hydrophobic anchoring sites on polyethylene glycol. Fusogenic liposomes prepared from N-C12-DOPE:DOPC 7:3 (mol:mol) were equilibrated with HMPEGs. Affinity

  9. 77 FR 76456 - Polyethylene Terephthalate Film, Sheet and Strip from Taiwan: Partial Rescission of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ...A-583-837] Polyethylene Terephthalate Film, Sheet and Strip from Taiwan: Partial...AD) order on polyethylene terephthalate film, sheet and strip from Taiwan covering...On September 26, 2012, DuPont Teijin Films, one of the petitioners who...

  10. Development of an optimum process for electron beam crosslinking of high density polyethylene pellets

    Microsoft Academic Search

    I. O. Salyer; J. E. Davison

    1982-01-01

    Commercially available high density polyethylene pellets were irradiated to total doses of 2, 4, 6, and 8 megarads in a single pass through an electron beam. Radiation doses of five to six megarads are sufficient to maintain the thermal form stability of high density polyethylene pellets. The enthalpy of fusion at these radiation doses is approximately 90 percent of the

  11. Leaf Area Distribution of Tomato Plants as Influenced by Polyethylene Mulch

    E-print Network

    Decoteau, Dennis R.

    Leaf Area Distribution of Tomato Plants as Influenced by Polyethylene Mulch Surface Color Dennis R of polyethylene (plastic) mulch surface color (white versus black) on leaf area distribution of tomato in a greater axillary:main leaf area ratio for the plants with white mulch. Leaf area for total leaves (main

  12. Antioxidant Content of and Migration from Commercial Polyethylene, Polypropylene, and Polyvinyl Chloride Packages

    Microsoft Academic Search

    M. S. Dopico-García; J. M. López-Vilariñó; M. V. González-Rodríguez

    2007-01-01

    Antioxidants commonly used in polyolefins were studied in commercial food packages made of low- and high-density polyethylene (LDPE and HDPE), polypropylene (PP), polyvinylchloride (PVC), and polyethylene terephtalate (PET) and in a LDPE film extruded at the laboratory. The phenolic antioxidants BHA, BHT, AO 2246, AO 425, Ethanox 330, Irganox 1010, and Irganox 1076 were studied together with the phosphite Irgafos

  13. Effect of thermal modification on rheological properties of polyethylene blends

    SciTech Connect

    Siriprumpoonthum, Monchai; Nobukawa, Shogo; Yamaguchi, Masayuki, E-mail: m-yama@jaist.ac.jp [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Satoh, Yasuo; Sasaki, Hiroko [Packaging and Industrial Materials Laboratory, Prime Polymer Co., Ltd., 3 Chigusa-kaigan, Ichihara, Chiba 299-0108 (Japan)

    2014-03-15

    We examined the effects of thermal modification under flow field on the rheological properties of linear low-density polyethylene (LLDPE) with high molecular weight, low-density polyethylene (LDPE), and their blends, without thermal stabilizer. Although structural changes during processing are not detected by size extrusion chromatography or nuclear magnetic resonance spectroscopy, linear viscoelastic properties changed greatly, especially for the LLDPE. A cross-linking reaction took place, leading to, presumably, star-shaped long-chain branches. Consequently, the modified LLDPE, having high zero-shear viscosity, became a thermorheologically complex melt. Moreover, it should be noted that the drawdown force, defined as the uniaxial elongational force at a constant draw ratio, was significantly enhanced for the blends. Enhancement of elongational viscosity was also detected. The drawdown force and elongational viscosity are marked for the thermally modified blend as compared with those for the blend of thermally modified pure components. Intermolecular cross-linking reactions between LDPE and LLDPE, yielding polymers with more than two branch points per chain, result in marked strain-hardening in the elongational viscosity behavior even at small strain. The recovery curve of the oscillatory modulus after the shear modification is further evidence of a branched structure.

  14. Particle Size Control of Polyethylene Glycol Coated Fe Nanoparticles

    NASA Astrophysics Data System (ADS)

    Srinivasan, B.; Bonder, M. J.; Zhang, Y.; Gallo, D.; Hadjipanayis, G. C.

    2006-03-01

    Recent interest in Fe nanoparticles with high magnetization is driven by their potential use in biomedical applications such as targeted drug delivery, MRI contrast enhancement and hyperthermia treatment of cancer. This study looks at the use of a polyethylene glycol (PEG) solution to mediate the particle size and therefore control the coercivity of the resulting nanoparticles. Iron nanoparticles were synthesized using an aqueous sodium borohydride reduction of ferrous chloride by a simultaneous introduction of reagents in a Y- junction. The resulting product was collected in a vessel containing a 15 mg/ml carboxyl terminated polyethylene glycol (cPEG) in ethyl alcohol solution located under the Y junction. By varying the length of tubing below the Y junction, the particle size was varied from 5-25 nm. X-ray diffraction data indicates the presence of either amorphous Fe-B or crystalline alpha Fe, depending on the molar ratio of reagents. Magnetic measurements indicate the particles are ferromagnetic with values of coercivity ranging from 200-500 Oe and a saturation magnetization in range of 70-110 emu/g. The XRD shows that the particles are not affected by the polymer coating.

  15. Polyethylene encapsulation of single shell tank low-level wastes

    SciTech Connect

    Kalb, P.D.; Fuhrmann, M.; Colombo, P.

    1993-01-01

    Polyethylene encapsulation is being explored for potential use in treating nitrate salts and sludges at US Department of Energy (US DOE) underground storage tank facilities. Some of these wastes contain high concentrations of fission products and are expected to maintain equilibrium temperatures of 50--70[degrees]C for many years. The potential effects of elevated temperature and high radiation conditions on key waste form properties (e.g., mechanical integrity, leachability) are examined. After 6 months of thermal conditioning, waste form tests specimens show no degradation in mechanical integrity. Leaching at elevated temperature resulted in a small increase in leach rate (a factor of less than two), while diffusion remained the dominant mechanism of release. Full-scale polyethylene waste forms containing 50--70 wt % nitrate salt can be expected to leach a total of 5--17% of the original contaminant source term after 300 years of leaching under worst-case conditions (fully saturated at 70[degrees]C).

  16. Polyethylene encapsulation of single shell tank low-level wastes

    SciTech Connect

    Kalb, P.D.; Fuhrmann, M.; Colombo, P.

    1993-04-01

    Polyethylene encapsulation is being explored for potential use in treating nitrate salts and sludges at US Department of Energy (US DOE) underground storage tank facilities. Some of these wastes contain high concentrations of fission products and are expected to maintain equilibrium temperatures of 50--70{degrees}C for many years. The potential effects of elevated temperature and high radiation conditions on key waste form properties (e.g., mechanical integrity, leachability) are examined. After 6 months of thermal conditioning, waste form tests specimens show no degradation in mechanical integrity. Leaching at elevated temperature resulted in a small increase in leach rate (a factor of less than two), while diffusion remained the dominant mechanism of release. Full-scale polyethylene waste forms containing 50--70 wt % nitrate salt can be expected to leach a total of 5--17% of the original contaminant source term after 300 years of leaching under worst-case conditions (fully saturated at 70{degrees}C).

  17. Reduced Water Density in a Poly(ethylene oxide) Brush

    SciTech Connect

    Lee, Hoyoung; Kim, Dae Hwan; Park, Hae-Woong; Mahynski, Nathan A.; Kim, Kyungil; Meron, Mati; Lin, Binhua; Won, You-Yeon (Purdue); (UC)

    2012-09-05

    A model poly(ethylene oxide) (PEO) brush system, prepared by spreading a poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) amphiphilic diblock copolymer onto an air-water interface, was investigated under various grafting density conditions by using the X-ray reflectivity (XR) technique. The overall electron density profiles of the PEO-PnBA monolayer in the direction normal to the air-water interface were determined from the XR data. From this analysis, it was found that inside of the PEO brush, the water density is significantly lower than that of bulk water, in particular, in the region close to the PnBA-water interface. Separate XR measurements with a PnBA homopolymer monolayer confirm that the reduced water density within the PEO-PnBA monolayer is not due to unfavorable contacts between the PnBA surface and water. The above result, therefore, lends support to the notion that PEO chains provide a hydrophobic environment for the surrounding water molecules when they exist as polymer brush chains.

  18. Migration of wear debris of polyethylene depends on bone microarchitecture.

    PubMed

    Libouban, Hélène; Massin, Philippe; Gaudin, Christine; Mercier, Philippe; Baslé, Michel F; Chappard, Daniel

    2009-08-01

    The mechanism of hip arthroplasties loosening is related to the migration of wear debris throughout the implant environment. In vivo, polyethylene particles (PE) were shown to infiltrate the bone implant interface and the medullary spaces of the cancellous bone. Our test hypothesis was that polyethylene particle migration is correlated to bone porosity. Bone samples with a high or low trabecular volume and microarchitecture were harvested in 20 calves and 20 human cadavers. They were extensively washed to remove marrow cells. Bone cylinders were filled with a light-curing monomer having the same viscosity as bone marrow. PE particles (7 and 33 microm) were deposited at the surface of the polymer. The bone cylinders were agitated during 7 days on an orbital shaker and the gel was left to polymerize at day light. X-ray microtomography was performed to characterize bone volume and microarchitecture. Cylinders were sectioned and observed under polarized light. The migration distance and rate were determined. Migration of PE particles strongly depended on trabecular bone volume and microarchitecture. We found a linear relationship (r = 0.61) between speed migration and bone volume and an exponential relationship between speed migration and bone architecture. The present in vitro model confirmed our hypothesis about the key role of bone microarchitecture in the migration of large PE wear particles. This is an explanation for the development of inflammatory reaction at distance from a prosthesis although our study did not include submicron particles. PMID:19235207

  19. Influence of chain extension on the compatibilization and properties of recycled poly(ethylene terephthalate)\\/linear low density polyethylene blends

    Microsoft Academic Search

    Yue Zhang; Weihong Guo; Hongsheng Zhang; Chifei Wu

    2009-01-01

    Polymeric methylene diphenyl diisocyanate (PMDI) was added as chain extender to a blend of recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) with compatibilizer of maleic anhydride-grafted poly(styrene–ethylene\\/butadiene–styrene) (SEBS-g-MA). Hydroxyl end groups of PET can react with both isocyanate groups of PMDI and maleic anhydride groups of SEBS-g-MA, which are competing reactions during reactive extrusion. The compatibility and

  20. Influence of poly(ethylene glycol)-containing additives on the sliding wear of ultrahigh molecular weight polyethylene\\/polypropylene blend

    Microsoft Academic Search

    Meiju Xie; Jinyao Chen; Huilin Li; Meng Li

    2010-01-01

    The influence of poly(ethylene glycol) (PEG)-containing additives on the sliding wear of ultrahigh molecular weight polyethylene\\/polypropylene (UHMWPE\\/PP) blend was investigated in this paper. At low sliding speed (200rpm, 30kg, 30min), the friction property and wear resistance of UHMWPE\\/PP blend can simultaneously be obviously improved by the addition of small amount of PEG (0–2phr) or its hybrids (0–3phr) with diatomite and

  1. Poly(ethylene terephthalate) copolymers with a smaller amount of poly(ethylene glycol)s and poly(butylene glycol)s

    Microsoft Academic Search

    Minoru Nagata

    1995-01-01

    Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess amount of ethylene glycol with 2–20 mol% of poly(ethylene glycol) (E) or poly(butylene glycol) (B), where the molecular weights (MW) of E and B are 200–7500 and 1000–3000, respectively. Reduced specific viscosity of copolymer increased with increasing MW and the content of polyglycol comonomer. Temperatures of glass

  2. Surface modification of polyethersulfone membranes by blending triblock copolymers of methoxyl poly(ethylene glycol)–polyurethane–methoxyl poly(ethylene glycol)

    Microsoft Academic Search

    Jingyun Huang; Jimin Xue; Kewei Xiang; Xu Zhang; Chong Cheng; Shudong Sun; Changsheng Zhao

    2011-01-01

    The surface of polyethersulfone (PES) membrane was modified by blending triblock copolymers of methoxyl poly(ethylene glycol)–polyurethane–methoxyl poly(ethylene glycol) (mPEG-PU-mPEG), which were synthesized through solution polymerization with mPEG Mns of 500 and 2000, respectively. The PES and PES\\/mPEG-PU-mPEG blended membranes were prepared through spin coating coupled with liquid–liquid phase separation. FTIR and 1H NMR analysis confirmed that the triblock copolymers were

  3. Cross-linked poly(ethylene vinyl acetate) (EVA)\\/low density polyethylene (LDPE)\\/metal hydroxides composites for wire and cable applications

    Microsoft Academic Search

    Mohammed A. Bahattab; Jaroslav Mosná?ek; Ahmed A. Basfar; Tariq M. Shukri

    2010-01-01

    Formulations of chemically cross-linked poly(ethylene vinyl acetate) (EVA) and low density polyethylene (LDPE) blends containing\\u000a metal hydroxides flame retardants such as aluminum hydroxide (ATH) and magnesium hydroxide (MH) were prepared. Comparison\\u000a of both type of metal hydroxides in respect of their influence on flammability as well as mechanical, thermal, and electrical\\u000a properties of EVA\\/LDPE composites is presented. Most of the

  4. Optimization of Protein Extraction for Lichen Thalli

    PubMed Central

    Kondratiuk, Anna S.; Savchuk, Oleksiy M.

    2015-01-01

    Lichen-forming fungal proteins have been seldom searched due to many difficulties in their extraction. Phenols, quinones, proteases, and other components released during cell disruption have been known to be the greatest challenges related to protein extraction from lichens. To overcome these problems and maintain good electrophoretic resolution and high protein concentration, an extraction buffer containing polyvinylpolypyrrolidone, ascorbic acid, Triton X-100, polyethylene glycol, proteinase, and oxidase inhibitors in sodium phosphate buffer was developed. This extraction buffer showed high efficiency for all lichen species tested in the study.

  5. Effect of chain architecture on the compression behavior of nanoscale polyethylene particles

    PubMed Central

    2013-01-01

    Polymeric particles with controlled internal molecular architectures play an important role as constituents in many composite materials for a number of emerging applications. In this study, classical molecular dynamics techniques are employed to predict the effect of chain architecture on the compression behavior of nanoscale polyethylene particles subjected to simulated flat-punch testing. Cross-linked, branched, and linear polyethylene chain architectures are each studied in the simulations. Results indicate that chain architecture has a significant influence on the mechanical properties of polyethylene nanoparticles, with the network configuration exhibiting higher compressive strengths than the branched and linear architectures. These findings are verified with simulations of bulk polyethylene. The compressive stress versus strain profiles of particles show four distinct regimes, differing with that of experimental micron-sized particles. The results of this study indicate that the mechanical response of polyethylene nanoparticles can be custom-tailored for specific applications by changing the molecular architecture. PMID:23855722

  6. Partitioning of Individual Flexible Polymers into a Nanoscopic Protein Pore

    Microsoft Academic Search

    Liviu Movileanu; Stephen Cheley; Hagan Bayley

    2003-01-01

    Polymer dynamics are of fundamental importance in materials science, biotechnology, and medicine. However, very little is known about the kinetics of partitioning of flexible polymer molecules into pores of nanometer dimensions. We employed electrical recording to probe the partitioning of single poly(ethylene glycol) (PEG) molecules, at concentrations near the dilute regime, into the transmembrane ?-barrel of individual protein pores formed

  7. 76 FR 1135 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-07

    ...A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of...duty order on polyethylene terephthalate film, sheet, and strip from the Republic of...duty order on polyethylene terephthalate film, sheet, and strip from the Republic...

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

    NASA Astrophysics Data System (ADS)

    Diop, Mirian; Torkelson, John

    2014-03-01

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

  9. Enhancement of the predicted drug hepatotoxicity in gel entrapped hepatocytes within polysulfone-g-poly (ethylene glycol) modified hollow fiber

    SciTech Connect

    Shen Chong [Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang Guoliang [Institute of Biological and Environmental Engineering, Zhejiang University of Technology, Zhejiang 310012 (China); Meng Qin, E-mail: mengq@zju.edu.c [Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2010-12-01

    Collagen gel-based 3D cultures of hepatocytes have been proposed for evaluation of drug hepatotoxicity because of their more reliability than traditional monolayer culture. The collagen gel entrapment of hepatocytes in hollow fibers has been proven to well reflect the drug hepatotoxicity in vivo but was limited by adsorption of hydrophobic drugs onto hollow fibers. This study aimed to investigate the impact of hollow fibers on hepatocyte performance and drug hepatotoxicity. Polysulfone-g-poly (ethylene glycol) (PSf-g-PEG) hollow fiber was fabricated and applied for the first time to suppress the drug adsorption. Then, the impact of hollow fibers was evaluated by detecting the hepatotoxicity of eight selected drugs to gel entrapped hepatocytes within PSf and PSf-g-PEG hollow fibers, or without hollow fibers. The hepatocytes in PSf-g-PEG hollow fiber showed the highest sensitivity to drug hepatotoxicity, while those in PSf hollow fiber and cylindrical gel without hollow fiber underestimated the hepatotoxicity due to either drug adsorption or low hepatic functions. Therefore, the 3D culture of gel entrapped hepatocytes within PSf-g-PEG hollow fiber would be a promising tool for investigation of drug hepatotoxicity in vitro.

  10. Characteristics of Cultured Tomato Cells after Prolonged Exposure to Medium Containing Polyethylene Glycol 1

    PubMed Central

    Handa, Avtar K.; Bressan, Ray A.; Handa, Sangita; Hasegawa, Paul M.

    1982-01-01

    Cell lines of tomato (Lycopersicon esculentum Mill., cv. VFNT-Cherry) have been isolated, which are capable of growing in media containing polyethylene glycol (PEG) 6000 with water potentials as low as ?15 or ?22 bar. After prolonged exposure to media containing PEG, these cell populations have reduced abilities to grow in the absence of PEG. Upon resuspension in PEG-free medium, the cells swell and begin to release metabolites, including protein. Measurement by plasmometry of the osmotic potential of cells selected in medium with ?22 bar water potential indicates that they maintain, at the end of the growth cycle, an osmotic potential of approximately ?26 bar. This is compared to an osmotic potential of ?9 bar for nonselected cells in medium without PEG, having an initial water potential of ?4 bar. Thus, considerable osmotic adjustment occurs as a result of exposure to external low water potential. The results also indicate that PEG does not contribute significantly to osmotic adjustment of the cells. Images PMID:16662239

  11. Efficiency of the Polyethylene-Glycol (PEG) Embedding Medium for Plant Histochemistry.

    PubMed

    Ferreira, Bruno G; Teixeira, Cristiane T; Isaias, Rosy M S

    2014-05-14

    Histochemical analyses in plants are commonly performed on hand-made sections of fresh materials. The disadvantages of embedding in historesin, paraffin or paraplast® are the alterations to cellular contents, the high costs and few evident results, depending on the test. Polyethylene-glycol (PEG), as a low cost, hydrophilic medium that maintains most of the cellular features similar to fresh conditions, may be useful for obtaining good histochemical results in thinner and homogeneous sections. The current study aimed to compare the efficiency of PEG as an embedding medium for histochemical analyses of primary and secondary metabolites accumulation. Using hand-made sections of fresh samples (T1) as a comparison, we tested the influence of the use of Karnovsky's solution as a fixative (T2) versus embedding in PEG (T3). The samples herein analyzed comprise leaves, stems, seeds and insect galls of different plant species. Neither the Karnovsky's fixative nor the embedding in PEG altered the histochemical results for starch, lipids, terpenoids, proteins and reducing sugars in T1, T2, and T3. However, PEG binds to phenols, such as tannins, flavonoids and lignins, thereby presenting false negatives in T3. PMID:24828626

  12. Relevance of the poly(ethylene glycol) linkers in peptide surfaces for proteases assays.

    PubMed

    Trzcinska, Roza; Balin, Katarzyna; Kubacki, Jerzy; Marzec, Magdalena E; Pedrys, Roman; Szade, Jacek; Silberring, Jerzy; Dworak, Andrzej; Trzebicka, Barbara

    2014-05-01

    Poly(ethylene glycol)s (PEGs) with different lengths were used as linkers during the preparation of peptide surfaces for protease detection. In the first approach, the PEG monolayers were prepared using a "grafting to" method on 3-aminopropyltrietoxysilane (APTES)-modified silicon wafers. Protected peptides with a fluorescent marker were synthesized by Fmoc solid phase synthesis. The protected peptide structures enabled their site-specific immobilization onto the PEG surfaces. Alternatively, the PEG-peptide surface was obtained by immobilizing a PEG-peptide conjugate directly onto the modified silicon wafer. The surfaces (composition, grafting density, hydrophilicity, and roughness) were characterized by time-of-flight-secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), contact angle (CA), and atomic force microscopy (AFM). Introducing the PEG linker between the peptide and surface increased their resistance toward nonspecific protein adsorption. The peptide surfaces were examined as analytical platforms to study the action of trypsin as a representative protease. The products of the enzymatic hydrolysis were analyzed by fluorescence spectroscopy, electrospray ionization-mass spectrometry (ESI-MS), and ToF-SIMS. Conclusions about the optimal length of the PEG linker for the analytical application of PEG-peptide surfaces were drawn. This work demonstrates an effective synthetic procedure to obtain PEG-peptide surfaces as attractive platforms for the development of peptide microarrays. PMID:24697681

  13. Elaboration et caracterisation de nanocomposites polyethylene/montmorillonite

    NASA Astrophysics Data System (ADS)

    Stoeffler, Karen

    This research project consists in preparing polyethylene/montmorillonite nanocomposites for film packaging applications. Montmorillonite is a natural clay with an exceptional aspect ratio. In recent years, its incorporation in polymer matrices has attracted great interest. The pioneer work from Toyota on polyamide-6/montmorillonite composites has shown that it was possible to disperse the clay at a nanometric scale. Such a structure, so-called exfoliated, leads to a significant increase in mechanical, barrier and fire retardant properties, even at low volumetric fractions of clay. This allows a valorization of the polymeric material at moderate cost. Due to its high polarity, montmorilloite exfoliation in polymeric matrices is problematic. In the particular case of polyolefin matrices, the platelets dispersion remains limited: most frequently, the composites obtained exhibit conventional structures (microcomposites) or intercalated structures. To solve this problem, two techniques are commonly employed: the surface treatment of the clay, which allows the expansion of the interfoliar gallery while increasing the affinity between the clay and the polymer, and the use of a polar compatibilizing agent (grafted polyolefin). The first part of this thesis deals with the preparation and the characterization of highly thermally stable organophilic montmorillonites. Commercial organophilic montmorillonites are treated with quaternary ammonium intercalating agents. However, those intercalating agents present a poor thermal stability and are susceptible to decompose upon processing, thus affecting the clay dispersion and the final properties of the nanocomposites. In this work, it was proposed to modify the clay with alkyl pyridinium, alkyl imidazolium and alkyl phosphonium intercalating agents, which are more stable than ammonium based cations. Organophilic montmorillonites with enhanced thermal stabilites compared to commercial organoclays (+20°C to +70°C) were prepared. The effect of the chemical structure of the intercalating agent on the capacity of the organoclay to be dispersed in polyethylene matrices was analyzed. In addition, the influence of the dispersion on the thermal stability of the nanocomposites prepared is discussed. In a second part, the effect of the compatibilizing agent characteristics on the quality of the clay dispersion in polyethylene/montmorillonite nanocomposites was analyzed. The mechanical properties and the oxygen permeability of the nanocomposites were evaluated and related to the level of clay delamination and to the strength of the polymer/clay interface, which was evaluated through surface tension measurements.

  14. Hot embossed polyethylene through-hole chips for bead-based microfluidic devices

    PubMed Central

    Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N.; Christodoulides, Nicolaos; McDevitt, John T.

    2013-01-01

    Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications forces cost considerations to be kept low and throughput high. As such, a materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 minutes with the ability to scale up 4x by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby demonstrating the approach is compatible with high performance, real-world clinical measurements in the context of point-of-care testing. PMID:23183187

  15. Hot embossed polyethylene through-hole chips for bead-based microfluidic devices.

    PubMed

    Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N; Christodoulides, Nicolaos; McDevitt, John T

    2013-04-15

    Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications force cost considerations to be kept low and throughput high. As such, materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 min with the ability to scale up 4 times by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby demonstrating that the approach is compatible with high performance, real-world clinical measurements in the context of point-of-care testing. PMID:23183187

  16. Simulation of polyethylene glycol and calcium-mediated membrane fusion

    SciTech Connect

    Pannuzzo, Martina, E-mail: martina.pannuzzo@gmail.com [Department of Computational Biology, Universität Erlangen-Nürnberg, Staudtstr.5-91058, Erlangen (Germany)] [Department of Computational Biology, Universität Erlangen-Nürnberg, Staudtstr.5-91058, Erlangen (Germany); De Jong, Djurre H.; Marrink, Siewert J. [Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen (Netherlands)] [Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen (Netherlands); Raudino, Antonio [Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6-95125, Catania (Italy)] [Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6-95125, Catania (Italy)

    2014-03-28

    We report on the mechanism of membrane fusion mediated by polyethylene glycol (PEG) and Ca{sup 2+} by means of a coarse-grained molecular dynamics simulation approach. Our data provide a detailed view on the role of cations and polymer in modulating the interaction between negatively charged apposed membranes. The PEG chains cause a reduction of the inter-lamellar distance and cause an increase in concentration of divalent cations. When thermally driven fluctuations bring the membranes at close contact, a switch from cis to trans Ca{sup 2+}-lipid complexes stabilizes a focal contact acting as a nucleation site for further expansion of the adhesion region. Flipping of lipid tails induces subsequent stalk formation. Together, our results provide a molecular explanation for the synergistic effect of Ca{sup 2+} and PEG on membrane fusion.

  17. Silk fibroin and polyethylene glycol-based biocompatible tissue adhesives

    PubMed Central

    Serban, Monica A.; Panilaitis, Bruce; Kaplan, David L.

    2012-01-01

    Tissue sealants have emerged in recent years as strong candidates for hemostasis. A variety of formulations are currently commercially available and though they satisfy many of the markets’ needs there are still key aspects of each that need improvement. Here we present a new class of blends, based on silk fibroin and chemically active polyethylene glycols (PEGs) with strong adhesive properties. These materials are cytocompatible, crosslink within seconds via chemical reaction between thiols and maleimides present on the constituent PEGs and have the potential to further stabilize through ?-sheet formation by silk. Based on the silk concentration in the final formulation, the adhesive properties of these materials are comparable or better than the current leading PEG-based sealant. In addition, the silk-PEG based materials show decreased swelling and longer degradation times. Such properties would make them suitable for applications for which the current sealants are contraindicated. PMID:21681949

  18. Conductivity and microviscosity of electrolyte solutions containing polyethylene glycols

    NASA Astrophysics Data System (ADS)

    Stojilkovic, Kosta S.; Berezhkovskii, Alexander M.; Zitserman, Vladimir Yu.; Bezrukov, Sergey M.

    2003-10-01

    Electrical conductivity of potassium chloride solutions containing polyethylene glycol (PEG) of different molecular mass was measured in a wide range of the polymer concentration up to 33 wt. % for PEG 300, 600, 2000, 4600, and 10 000. The data were used to find the dependence of microviscosity, ?micro, which characterizes the decrease of the ion mobility compared to that in the polymer-free solution, on the polymer volume fraction, ?. We find that the dependence is well approximated by a simple relation ?micro/?0=exp[k?/(1-?)], where ?0 is viscosity of the polymer-free solution and k is a fitting parameter. Parameter k weakly depends on the polymer molecular mass growing from 2.5 for PEG 300 to its limiting value close to 2.9 for long chains. Using the ?-dependence of microviscosity, we give a practical formula for the conductivity of PEG-containing electrolyte solutions.

  19. Irradiation of linear polyethylene - Partitioning between sol and gel.

    NASA Technical Reports Server (NTRS)

    Rijke, A. M.; Mandelkern, L.

    1971-01-01

    Molecular weight fractions of linear polyethylene were irradiated at 133 C, in the completely molten and highly crystalline states, for the purpose of assessing the importance of chain-scission processes and establishing the critical conditions for gelation. The partitioning between sol and gel in either state was found to adhere to the theory for the intermolecular cross-linking of monodisperse species for dosages just beyond the gel point. Deviations from theory occurred as the dosage was increased further. It was concluded that main-chain scission, at these temperatures, is not a significant process. High molecular weight samples in the completely molten state obeyed the Flory-Stockmayer condition for critical gelation.

  20. Texturation and superhydrophobicity of polyethylene terephthalate thanks to plasma technology

    NASA Astrophysics Data System (ADS)

    Tarrade, Jeanne; Darmanin, Thierry; Taffin de Givenchy, Elisabeth; Guittard, Frédéric; Debarnot, Dominique; Poncin-Epaillard, Fabienne

    2014-02-01

    Anti-bioadhesive surfaces were designed from polyethylene terephthalate (PET) by three steps plasma-treatment. First, the nano-pattern is created by oxygen plasma-treatment with controlled dimensions. Then, the plasma-treated polymeric surface was hydrophobized with a tetrafluorocarbon plasma, allowing to obtain a water contact angle of 145 ± 4°. However, the SEM pictures give evidence to show the degradation of the structuration caused by the CF4-plasma and consequently, the superhydrophobicity was not reached. Thus, a plasma-polypyrrole layer was deposited before the plasma-fluorination, which has a protective role against the degradation generated by fluorinated species, preserving the structuration and improving the fluorination rate. Therefore, the obtained surfaces are superhydrophobic with water contact angle of 157 ± 2° and a hysteresis of 65 ± 3°. The ability of these surfaces to reduce bioadhesion will be performed in further work.

  1. The characterisation of two different degradable polyethylene (PE) sacks

    SciTech Connect

    Davis, G. [Engineering Management Group, University of Bristol (United Kingdom)]. E-mail: gudavis@cytanet.com.cy

    2006-12-15

    The compostability of two different polyethylene (PE) products on the UK market under open-windrow composting conditions is explored within this paper. Chemical analysis of the PE bags has established their constituents in order to examine how the PE bags have an increased degradability depending on additives. Weight loss of the two different PE products within open-windrow composting conditions was recorded in order to establish the percentage weight loss as an indication of the degradability of the two products and their relative suitability for open-windrow composting. Scanning electron microscopy (SEM) of the PE products over the composting duration established the degradation processes for the PE products within the compost. These analyses concluded that one of the PE product mixes was more degradable than the other. However, neither product completed degraded within the timeframe of 12-14 weeks generally accepted for open-windrow composting in the UK.

  2. Textural changes in metallurgical coke prepared with polyethylene

    NASA Astrophysics Data System (ADS)

    Gornostayev, Stanislav S.; Heino, Jyrki J.; Kokkonen, Tommi M. T.; Makkonen, Hannu T.; Huttunen, Satu M. M.; Fabritius, Timo M. J.

    2014-10-01

    The effect of high-density polyethylene (HDPE) on the textural features of experimental coke was investigated using polarized-light optical microscopy and wavelet-based image analysis. Metallurgical coke samples were prepared in a laboratory-scale furnace with 2.5%, 5.0%, 7.5%, 10.0%, and 12.5% HDPE by mass, and one sample was prepared by 100% coal. The amounts and distribution of textures (isotropic, mosaic and banded) and pores were obtained. The calculations reveal that the addition of HDPE results in a decrease of mosaic texture and an increase of isotropic texture. Ethylene formed from the decomposition of HDPE is considered as a probable reason for the texture modifications. The approach used in this study can be applied to indirect evaluation for the reactivity and strength of coke.

  3. Electrospun Polyaniline/Polyethylene Oxide Nanofiber Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    Pinto, N. J.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

    2003-01-01

    We report on the observation of field effect transistor (FET) behavior in electrospun camphorsulfonic acid doped polyaniline(PANi)/polyethylene oxide(PE0) nanofibers. Saturation channel currents are observed at surprisingly low source/drain voltages. The hole mobility in the depletion regime is 1.4 x 10(exp -4) sq cm/V s while the 1-D charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating 1-D polymer FET's.

  4. High-strength welds in metallocene Polypropylene/Polyethylene laminates

    PubMed

    Chaffin; Knutsen; Brant; Bates

    2000-06-23

    Spectacular advances in organometallic chemistry over the past two decades have resulted in single-site catalysts that are revolutionizing production of polyethylene (PE) and isotactic polypropylene (iPP). This report describes an unanticipated benefit of metallocene-catalyzed semicrystalline polyolefins, namely welded joint strengths in PE/iPP laminates that can exceed the cohesive strength of the constituents. We propose that interfacial polymer entanglements, established in the molten state and subsequently anchored in chain-folded lamellae upon crystallization, are responsible for this intrinsic property. The poor adhesion exhibited by traditional Ziegler-Natta-catalyzed polyolefins is shown to derive from the accumulation of amorphous polymer, a by-product of the polymerization reactions, at the interface. These results should facilitate fabrication and improve the properties of composites based on materials that dominate the plastics industry. PMID:10864863

  5. High-Strength Welds in Metallocene Polypropylene/Polyethylene Laminates

    NASA Astrophysics Data System (ADS)

    Chaffin, Kimberly A.; Knutsen, Jeffrey S.; Brant, Patrick; Bates, Frank S.

    2000-06-01

    Spectacular advances in organometallic chemistry over the past two decades have resulted in single-site catalysts that are revolutionizing production of polyethylene (PE) and isotactic polypropylene (iPP). This report describes an unanticipated benefit of metallocene-catalyzed semicrystalline polyolefins, namely welded joint strengths in PE/iPP laminates that can exceed the cohesive strength of the constituents. We propose that interfacial polymer entanglements, established in the molten state and subsequently anchored in chain-folded lamellae upon crystallization, are responsible for this intrinsic property. The poor adhesion exhibited by traditional Ziegler-Natta-catalyzed polyolefins is shown to derive from the accumulation of amorphous polymer, a by-product of the polymerization reactions, at the interface. These results should facilitate fabrication and improve the properties of composites based on materials that dominate the plastics industry.

  6. A Molecular Mechanism of viscoelasticity in aligned polyethylene

    NASA Astrophysics Data System (ADS)

    Hammad, A.; Hasan, H.; Swinburne, T. D.; Khawaja, M.; Del-Rosso, S.; Iannucci, L.; Sutton, A. P.

    2015-03-01

    The key observed property of aligned polyethylene is its viscoelastic behaviour, which is traditionally fitted with Maxwell models. Although these empirical models are successful at reproducing the mechanical response of the material, they fail to capture the underlying molecular mechanisms that lead to the observed viscoelastic behaviour. We explain the observed viscoelastic behaviour in terms of the formation, interaction and movement of solitons, and relate these molecular mechanisms to the semi-crystalline microstructure of the material. Using Molecular Dynamics we demonstrate the following results: (a) The formation of solitons from interfaces between crystalline and amorphous regions (b) The transfer of tensile load between molecular chains (c) the pile-up of solitons in a molecular chain that allows the concentration of stress at particular points (d) The disassociation of solitons into ?-twistons at 300K. European Science Research Council (EPSRC).

  7. Gels and foams from ultrahigh molecular weight polyethylene

    SciTech Connect

    Hair, L.M.; Letts, S.A.; Tillotson, T.

    1988-07-01

    Ultrahigh molecular weight polyethylene (UHMW PE) foams with densities from 0.04 to 0.2 g/cm{sup 3} have routinely been made in our laboratory. First, an entangled solution of UHMW PE is made. Then, the solution is geled by cooling to crystallize the PE. The gel is later dried to a foam by critical point drying. Viscometry and cloud point measurements were used to determine the gelatin point and the critical gelatin concentrations. Polarized light microscopy and differential scanning calorimetry were used to investigate the effects of cooling rate on the gel, while the effects of cooling rate on the foam were investigated via x-ray diffraction and scanning electron microscopy. We found that rapid cooling of 5 wt % UHMW PE/tetralin solutions to {minus}10{degree}c yielded small, uniform structure at the expense of crystallinity and strength; cooling over three days yielded spherulitic structure with strength. 5 refs., 3 figs.

  8. Safety Evaluation of Polyethylene Glycol (PEG) Compounds for Cosmetic Use

    PubMed Central

    Shin, Chan Young; Kim, Kyu-Bong

    2015-01-01

    Polyethylene glycols (PEGs) are products of condensed ethylene oxide and water that can have various derivatives and functions. Since many PEG types are hydrophilic, they are favorably used as penetration enhancers, especially in topical dermatological preparations. PEGs, together with their typically nonionic derivatives, are broadly utilized in cosmetic products as surfactants, emulsifiers, cleansing agents, humectants, and skin conditioners. The compounds studied in this review include PEG/PPG-17/6 copolymer, PEG-20 glyceryl triisostearate, PEG-40 hydrogenated castor oil, and PEG-60 hydrogenated castor oil. Overall, much of the data available in this review are on PEGylated oils (PEG-40 and PEG-60 hydrogenated castor oils), which were recommended as safe for use in cosmetics up to 100% concentration. Currently, PEG-20 glyceryl triisostearate and PEGylated oils are considered safe for cosmetic use according to the results of relevant studies. Additionally, PEG/PPG-17/6 copolymer should be further studied to ensure its safety as a cosmetic ingredient.

  9. Anaphylactic Shock Caused by Ingestion of Polyethylene Glycol

    PubMed Central

    Lee, Sun Hee; Lee, Joung Il; Joo, Kwang Ro; Shin, Hyun Phil; Baek, Il Hyun; Jeon, Jung Won; Lim, Jun Uk; Lee, Jung Lok; Lee, Hyae Min; Cho, Young-Hak

    2015-01-01

    Colonoscopy is the current standard method for evaluation of the colon. The diagnostic accuracy and therapeutic safety of colonoscopy depend on the quality of colonic cleansing and preparation. Generally, all these preparations have been demonstrated to be safe for use in healthy individuals without significant comorbid conditions. Based on safety and efficacy concerns, polyethylene glycol (PEG) is most commonly utilized as a bowel preparation solution for colonoscopy. Adverse events in patients receiving PEG are mostly clinically non-significant. However, fatal adverse events rarely have been shown to occur in the few individuals who experience vomiting or aspiration. Anaphylactic shock associated with ingestion of PEG electrolyte solution is an extremely rare fatal complication, and reported mainly in Western countries. Here, we report the first case of anaphylactic shock following the ingestion of PEG solution in Korea. PMID:25691849

  10. [Analysis of formaldehyde, acetaldehyde and oligomers in recycled polyethylene terephthalate].

    PubMed

    Ohkado, Yuka; Kawamura, Yoko; Mutsuga, Motoh; Tamura, Hiro-omi; Tanamoto, Kenichi

    2005-10-01

    Formaldehyde (FA), acetaldehyde (AA) and oligomers in recycled polyethylene terephthalate (PET) were analyzed by HPLC. All of the physically recycled PET contained detectable levels of FA, AA and oligomers, and the levels were almost the same as in used bottles. Most superclean-like and chemically recycled PET contained lower levels than new pellets. These compounds showed no decrease upon physical recycling, but showed a marked decrease upon superclean-like recycling. In PET sheets made using physically recycled PET, FA was decreased, though AA was increased by the sheeting process as same as new one. FA, AA and oligomers originated from PET resin and their levels in recycled products were almost equivalent to those in new products. It was concluded that there is no particular safety concern about their presence in recycled PET. PMID:16305177

  11. [Analysis of residual volatiles in recycled polyethylene terephthalate].

    PubMed

    Ohkado, Yuka; Kawamura, Yoko; Mutsuga, Motoh; Tamura, Hiro-omi; Tanamoto, Kenichi

    2005-02-01

    The residual volatiles in recycled polyethylene terephthalate (PET) were analyzed using headspace/GC/MS. Recycled PET samples were made from PET bottles used for beverages, alcohol and soy sauce, and they were recycled in physical recycling plants, chemical recycling plants and superclean-like recycling trials. The physically recycled PET flakes contained small amounts of volatiles such as ethanol, limonene, 2-methyl-1,3-dioxolane, acetone, octanal and nonanal. Most of them originated from foods packed in bottles, and only 2-methyl-1,3-dioxolane was derived from polymer impurities. In contrast, the superclean-like or chemically recycled PET contained no detectable volatiles, like new PET pellets. The PET sheets shaped from physically recycled PET had no detectable volatiles. Not only the chemically and superclean-like recycled PET, but also the physically recycled PET contained no hazardous volatiles. It was concluded that there is no safety concern about volatiles in recycled PET, for the present use. PMID:15881250

  12. Preparation of polyethylene sacks for collection of precipitation samples for chemical analysis

    USGS Publications Warehouse

    Schroder, L.J.; Bricker, A.W.

    1985-01-01

    Polyethylene sacks are used to collect precipitation samples. Washing polyethylene with acetone, hexane, methanol, or nitric acid can change the adsorptive characteristics of the polyethylene. In this study, simulated precipitation at pH 4.5 was in contact with the polyethylene sacks for 21 days; subsamples were removed for chemical analysis at 7, 14, and 21 days after intitial contact. Sacks washed with acetone adsorbed iron and lithium; sacks washed with hexane adsorbed barium, iron , and lithium; sacks washed with methanol adsorbed calcium and iron; and sacks washed with 0.30 N nitric acid adsorbed iron. Leaching the plastic sacks with 0.15 N nitric acid did not result in 100-percent recovery of any of the adsorbed metals. Washing polyethylene sacks with dilute nitric acid caused the pH of the simulated precipitation to be decreased by 0.2 pH unit after 1 week of contact with the polyethylene. The specific conductance increased by 10 microsiemens per centimeter. Contamination of precipitation samples by lead was determined to be about 0.1 microgram per liter from contact with precleaned polyethylene sacks. No measurable contamination of precipitation samples by zinc occurred. (USGS)

  13. Degradation of polyethylene by Trichoderma harzianum--SEM, FTIR, and NMR analyses.

    PubMed

    Sowmya, H V; Ramalingappa; Krishnappa, M; Thippeswamy, B

    2014-10-01

    Trichoderma harzianum was isolated from local dumpsites of Shivamogga District for use in the biodegradation of polyethylene. Soil sample of that dumpsite was used for isolation of T. harzianum. Degradation was carried out using autoclaved, UV-treated, and surface-sterilized polyethylene. Degradation was monitored by observing weight loss and changes in physical structure by scanning electron microscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. T. harzianum was able to degrade treated polyethylene (40%) more efficiently than autoclaved (23%) and surface-sterilized polyethylene (13%). Enzymes responsible for polyethylene degradation were screened from T. harzianum and were identified as laccase and manganese peroxidase. These enzymes were produced in large amount, and their activity was calculated using spectrophotometric method and crude extraction of enzymes was carried out. Molecular weight of laccase was determined as 88 kDa and that of manganese peroxidase was 55 kDa. The capacity of crude enzymes to degrade polyethylene was also determined. By observing these results, we can conclude that this organism may act as solution for the problem caused by polyethylene in nature. PMID:25052326

  14. Pyrolysis-gas chromatography-isotope ratio mass spectrometry of polyethylene.

    PubMed

    González-Pérez, J A; Jiménez-Morillo, N T; de la Rosa, J M; Almendros, G; González-Vila, F J

    2015-04-01

    Polyethylene is probably the most used plastic material in daily life and its accurate analysis is of importance. In this communication the chemical structure of polyethylenes is studied in detail using conventional analytical pyrolysis (Py-GC/MS), bulk stable isotopic analysis (IRMS) and pyrolysis compound specific stable isotopic analysis (Py-CSIA) to measure stable isotope proportions (?(13)C, ?(15)N and ?D) of polyethylene pyrolysis compounds. Polyethylene pyrolysis yields triplet peaks of n-alkanes, ?-alkenes and ?,?-alkanedienes. No differences were found for bulk ?(13)C among different polyethylene types. However, conspicuous differences in ?D were evident. It was possible to assign structure ?(13)C and ?D values to specific polyethylene pyrolysis products in the range 12-18 carbon chain length. Conspicuous differences were found for the pyrolysis products with unsaturated moieties showing significant higher ?D values than saturated chains (alkanes) that were deuterium depleted. In addition, a full isotopic fingerprinting (?(13)C, ?(15)N and ?D) for a dye (o-chloroaniline) contained in a polyethylene is reported. To the best of our knowledge this is the first application Py-CSIA to the study of a synthetic polymer. This hyphenated analytical technique is a promising tool to study synthetic materials, providing not only a fingerprinting, but also allowing the traceability of the polymerization process and the origin of the materials. PMID:25725959

  15. Immobilization of Proteins on a Glass Surface at High Density

    NASA Astrophysics Data System (ADS)

    Thomas, Marlon; Wan, Jiandi; Vullev, Valentine I.

    2009-07-01

    We describe a rational molecular-level design of biocompatible surface coatings and immobilization of biological species onto them to produce biofunctional interfaces. Our method adapted a strategy for coating glass and other silica-type substrates with bioinert layers of polyethylene glycol (PEG). The introduction of ?, ?-bifunctional polymers into the coatings allowed for covalent attachment of proteins to the PEGylated surfaces. Spectroscopic studies indicate that the surface-bound proteins had their biological activity preserved.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  17. Analysis of interfacial phenomena of aqueous solutions of polyethylene oxide and polyethylene glycol flowing in hydrophilic and hydrophobic capillary viscometers.

    PubMed

    Cai, Jiali; Bo, Shuqin; Cheng, Rongshi; Jiang, Liansheng; Yang, Yu

    2004-08-01

    Viscosities of aqueous solutions of five polyethylene oxide (PEO) samples with molar masses from 1.5 x 10(5) to 1.0 x 10(6) were carefully measured in a polytetrafluoroethylene (PTFE) capillary Ubbelohde viscometer in the concentration range from dilute down to extremely dilute concentration regions and compared with those of the same sample obtained from a glass capillary viscometer. At the same time, viscosities of aqueous solutions of three PEG samples in glass and paraffin-coated capillary viscosity were measured. The wall effects occurred in viscosity measurements for PEO and PEG aqueous solutions in different capillary viscometers were theoretically analyzed and discussed. It was found that different interfacial behaviors occurred in both hydrophobic and hydrophilic capillary viscometers respectively and the interfacial behaviors also exhibit molar mass dependence. PMID:15219446

  18. Graphite/Ultra-High Modulus Polyethylene Hybrid Fiber Composites with Epoxy and Polyethylene Matrices for Cosmic Radiation Shielding

    NASA Technical Reports Server (NTRS)

    2003-01-01

    One of the most significant technical challenges in long-duration space missions is that of protecting the crew from harmful radiation. Protection against such radiation on a manned Mars mission will be of vital importance both during transit and while on the surface of the planet. The development of multifunctional materials that serve as integral structural members of the space vehicle and provide the necessary radiation shielding for the crew would be both mission enabling and cost effective. Additionally, combining shielding and structure could reduce total vehicle mass. Hybrid laminated composite materials having both ultramodulus polyethylene (PE) and graphite fibers in epoxy and PE matrices could meet such mission requirements. PE fibers have excellent physical properties, including the highest specific strength of any known fiber. Moreover, the high hydrogen (H) content of polyethylene makes the material an excellent shielding material for cosmic radiation. When such materials are incorporated into an epoxy or PE matrix a very effective shielding material is expected. Boron (B) may be added to the matrix resin or used as a coating to further increase the shielding effectiveness due to B s ability to slow thermal neutrons. These materials may also serve as micrometeorites shields due to PE s high impact energy absorption properties. It should be noted that such materials can be fabricated by existing equipment and methods. It is the objective of this work therefore to: (a) perform preliminary analysis of the radiation transport within these materials; (b) fabricate panels for mechanical property testing before and after radiation exposure. Preliminary determination on the effectiveness of the combinations of material components on both shielding and structural efficiency will be made.

  19. Effect of the Dietary Ratio of Digestible Energy to Crude Protein on Growth and Feed Conversion in Juvenile Pacific White Shrimp Litopenaeus vannamei under Similar Levels of Daily Protein Consumption

    Microsoft Academic Search

    Jesus A. Venero; D. Allen Davis; David B. Rouse

    2008-01-01

    We evaluated the effect of the dietary ratio of digestible energy (DE) : Crude protein (CP) on growth performance and nutrient utilization in juvenile Pacific white shrimp Litopenaeus vannamei fed various diets with a constant daily protein input. Juveniles (weight = 0.94 ± 0.04 g [mean ± SE]; n = 30) were stocked in an indoor recirculating-water system (173-L polyethylene

  20. Method To Determine Protein Concentration in the Protein-Nanoparticle Conjugates Aqueous Solution Using Circular Dichroism Spectroscopy.

    PubMed

    Li, Shanghao; Peng, Zhili; Leblanc, Roger M

    2015-07-01

    Considerable efforts have been made to synthesize and characterize protein-nanoparticle conjugates (protein-NPs) for their promising applications in bionanotechnology. However, protein concentration determination in the protein-NPs has so far not been reported. In this Letter, we present a simple and nondestructive approach to quantify the protein concentration in the protein-NPs aqueous solution using circular dichroism (CD) spectroscopy. Carbon dots (?4 nm), gold nanoparticles (?10 nm), and polyethylene glycol (PEG, molecular weight ?3000) were either physically mixed or covalently conjugated (not in the case of gold nanoparticles) with proteins (human transferrin, human serum albumin, and ovalbumin). We were able to quantify the protein concentration in the protein-nanoparticle conjugates using a calibration curve from the CD spectra. PMID:26070096

  1. Improved performance of ultra-high molecular weight polyethylene for orthopedic applications 

    E-print Network

    Plumlee, Kevin Grant

    2009-05-15

    A considerable number of total-joint replacement devices used in orthopedic medicine involve articulation between a metallic alloy and ultra-high molecular weight polyethylene (UHMWPE). Though this polymer has excellent wear resistance, the wear...

  2. Kinetics and microscopic processes of long term fracture in polyethylene piping materials

    NASA Astrophysics Data System (ADS)

    Brown, N.; Lu, X.

    1992-07-01

    The report contains 9 completed works as follows: The Dependence of Slow Crack Growth in a Polyethylene Copolymer on Testing Temperature and Morphology; A Test of Slow Crack Growth Failure of PE Under Constant Load; Effect of Annealing on Slow Crack Growth in an Ethylene-Hexene Copolymer; The Fundamental Material Parameters that Govern Slow Crack Growth in Linear Polyethylene; Slow Crack Growth in Blends of HDPE and UHMWPE; The Mechanism of Fatigue Failure in a Polyethylene Copolymer; PENT Quality Control Test for PE Gas Pipes and Resins; International Round Robin Study of a Fatigue Test Approach to the Ranking of Polyethylene Pipe Material; and Proposed ASTM Specification for ASTM F17.40 Test Methods Committee.

  3. Discrimination of transparent polyethylene films based on identification of inorganic antiblocking agents.

    PubMed

    Hashimoto, Takashi; Mizuhata, Minoru

    2012-05-01

    Several nondestructive and semidestructive analyses were used to discriminate colorless transparent polyethylene bags. Transparent plastic bags made from low-density and linear low-density polyethylene usually contain antiblocking agents to prevent sticking of the film, which makes it difficult to open the mouths of plastic bags. Inorganic antiblocking agents are uniformly dispersed in polyethylene films, so they are easily observed using optical microscopy. The particle size distributions of the antiblocking agents were compared by statistical tests. Particle composition was examined by elemental analysis using energy-dispersive X-ray spectrometry with a scanning electron microscope and by molecular vibration analysis using a sensitive microscopic Raman spectrometer. The compositions could be determined nondestructively on the basis of the results. These data reinforce the morphological discrimination. Morphological discrimination of the dispersed antiblocking agent powders, statistical comparison of particle size distributions, and compositional analysis of the antiblocking agents strengthen the ability to discriminate polyethylene films. PMID:22390790

  4. Polyethylene/Potassium Titanate Separators For Ni/H2 Cells

    NASA Technical Reports Server (NTRS)

    Scott, William E.

    1995-01-01

    Experimental separators fabricated on paper-making machine. Two-layer, paperlike composite of polyethylene fibers and potassium titanate pigment shows promise for replacing asbestos as separator material in nickel/hydrogen electrochemical cells.

  5. Failure mechanisms in blends of linear low-density polyethylene and polystyrene

    SciTech Connect

    Li, T.; Topolkaraev, V.A.; Hiltner, A.; Baer, E. [Case Western Reserve Univ., Cleveland, OH (United States)

    1996-12-31

    Mechanical models which describe the deformation and failure mechanisms for uncompatibilized blends of linear low-density polyethylene and polystyrene are described. A ductile to brittle transition was observed.

  6. Limitations of Reverse Polyethylene Samplers (RePES) for Evaluating Toxicity of Field Contaminated Sediments

    EPA Science Inventory

    Passive samplers are used to measure dissolved nonionic organic contaminants (NOCs) in environmental media. More recently, reverse polyethylene samplers (RePES) have been used with spiked sediments to recreate interstitial water exposure concentrations and observed toxicity. In...

  7. SCRATCHING VULNERABILITY OF CONVENTIONAL VS. HIGHLY CROSSLINKED POLYETHYLENE LINERS DUE TO LARGE EMBEDDED THIRD BODY PARTICLES

    PubMed Central

    Heiner, Anneliese D.; Galvin, Alison L.; Fisher, John; Callaghan, John J.; Brown, Thomas D.

    2011-01-01

    The hypothesis of this study was that acetabular liner vulnerability to scratching from femoral heads, roughened by third bodies embedded in the liner, is not significantly lower for highly crosslinked polyethylene (HXPE) than for conventional polyethylene (CPE). Six CPE and six HXPE acetabular liners were each reproducibly embedded with five CoCrMo beads, then run for 10,000 cycles in a joint simulator. By visual rank-ordering, there was low association between liner scratch severity and polyethylene type. The CPE and HXPE liner scratches were not significantly different in scratch peak-valley height or width, or in liner roughness in the vicinity of the embedded beads. This model indicated that high crosslinking of polyethylene does not offer appreciable protection against severe scratching induced by large embedded third body particles. PMID:22115764

  8. Use of prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent

    NASA Astrophysics Data System (ADS)

    Priyada, P.; Sarkar, P. K.

    2015-06-01

    The possibility of using measured prompt gamma emissions from polyethylene to estimate neutron ambient dose equivalent is explored theoretically. Monte Carlo simulations have been carried out using the FLUKA code to calculate the response of a high density polyethylene cylinder to emit prompt gammas from interaction of neutrons with the nuclei of hydrogen and carbon present in polyethylene. The neutron energy dependent responses of hydrogen and carbon nuclei are combined appropriately to match the energy dependent neutron fluence to ambient dose equivalent conversion coefficients. The proposed method is tested initially with simulated spectra and then validated using experimental measurements with an Am-Be neutron source. Experimental measurements and theoretical simulations have established the feasibility of estimating neutron ambient dose equivalent using measured neutron induced prompt gammas emitted from polyethylene with an overestimation of neutron dose at very low energies.

  9. 75 FR 22842 - Polyethylene Retail Carrier Bags From Indonesia, Taiwan, and Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ...Polyethylene Retail Carrier Bags From Indonesia, Taiwan, and Vietnam Determinations...material injury by reason of imports from Indonesia, Taiwan, and Vietnam of PRCBs that...by Commerce that imports of PRCBs from Indonesia, Taiwan, and Vietnam were being...

  10. [Effect of physicochemical properties of polyethylene glycol derivatives on drug release from wax matrices].

    PubMed

    Dredán, J; Zelkó, R; Bihari, E; Rácz, I

    1998-07-01

    The purpose of the present study was to investigate the effect of the various types and amounts of polyethylene glycols on the potassium chloride release from wax matrices. Potassium chloride as a highly water-soluble model drug was embedded into wax containing surfactants to produce sustained release dosage form. Various kinds of polyethylene glycols were chosen to control the dissolution profile. The dissolution profile of the matrix samples was characterized by the Weibull distribution. The physico-chemical characteristics--surface tension, HLB value, refractive index--of the aqueous solutions of the polyethylene glycols were also determined. On the basis of the examined physicochemical characteristics of various polyethylene glycols it is possible to select the optimal concentration of surfactant to formulate matrix dosage forms of required dissolution profile. PMID:9737020

  11. Ultrafiltration of pegylated proteins

    NASA Astrophysics Data System (ADS)

    Molek, Jessica R.

    There is considerable clinical interest in the use of "second-generation" therapeutics produced by conjugation of a native protein with various polymers including polyethylene glycol (PEG). PEG--protein conjugates, so-called PEGylated proteins, can exhibit enhanced stability, half-life, and bioavailability. One of the challenges in the commercial production of PEGylated proteins is the purification required to remove unreacted polymer, native protein, and in many cases PEGylated proteins with nonoptimal degrees of conjugation. The overall objective of this thesis was to examine the use of ultrafiltration for the purification of PEGylated proteins. This included: (1) analysis of size-based separation of PEGylated proteins using conventional ultrafiltration membranes, (2) use of electrically-charged membranes to exploit differences in electrostatic interactions, and (3) examination of the effects of PEGylation on protein fouling. The experimental results were analyzed using appropriate theoretical models, with the underlying physical properties of the PEGylated proteins evaluated using size exclusion chromatography, capillary electrophoresis, dynamic light scattering, and reverse phase chromatography. PEGylated proteins were produced by covalent attachment of activated PEG to a protein via primary amines on the lysine residues. A simple model was developed for the reaction kinetics, which was used to explore the effect of reaction conditions and mode of operation on the distribution of PEGylated products. The effective size of the PEGylated proteins was evaluated using size exclusion chromatography, with appropriate correlations developed for the size in terms of the molecular weight of the native protein and attached PEG. The electrophoretic mobility of the PEGylated proteins were evaluated by capillary electrophoresis with the data in good agreement with a simple model accounting for the increase in protein size and the reduction in the number of protonated amine groups in the PEGylated proteins. Ultrafiltration experiments were performed using PEGylated alpha-lactalbumin, ovalbumin, and bovine serum albumin. In contrast to the size exclusion chromatography data, the sieving coefficient of the PEGylated proteins depended upon both the number and size of the attached PEG chains due to the elongation or deformation of the PEG associated with the filtrate flux. Sieving coefficients at low filtrate flux were in good agreement with predictions of available hydrodynamic models, with significant elongation occurring when the Deborah number for the PEG chain exceeded 0.001. The effects of electrostatic interactions on the ultrafiltration of PEGylated proteins were examined using electrically-charged membranes generated by covalent attachment of sulphonic acid groups to the base cellulosic membrane. Transmission of PEGylated proteins through charged membranes was dramatically reduced at low ionic strength due to strong electrostatic interactions, despite the presence of the neutral PEG. The experimental results were in good agreement with model calculations developed for the partitioning of charged spheres into charged cylindrical pores. The experimental and theoretical results provide the first quantitative analysis of the effects of PEGylation on transport through semipermeable ultrafiltration membranes. The results from small-scale ultrafiltration experiments were used to develop a two-stage diafiltration process to purify PEGylated alpha-lactalbumin. The first-stage used a neutral membrane to remove the unreacted protein by exploiting differences in size. The second stage used a negatively-charged membrane to remove hydrolyzed PEG, with the PEGylated product retained by strong electrostatic interactions. This process provided a purification factor greater than 1000 with respect to the unreacted protein and greater than 20-fold with respect to the PEG with an overall yield of PEGylated alpha-lactalbumin of 78%. These results provide the first demonstration of the potential of using ultrafiltration for the purificatio

  12. Effects of weekly administration of pegylated recombinant human OB protein on appetite profile and energy metabolism in obese men

    Microsoft Academic Search

    Margriet S Westerterp-Plantenga; Wim HM Saris; Chris J Hukshorn; L Arthur Campfield

    2001-01-01

    Background: Results of leptin administration in mice, rats, and humans provide a rationale for therapeutic augmentation of cir- culating leptin (OB protein) concentrations in obese humans; this may reduce food intake, increase metabolic rate, and lower body mass. Objective: We assessed the effects of weekly subcutaneous pegylated polyethylene glycol (PEG)-OB protein administration on appetite and energy metabolism in obese men.

  13. A sliding-distance-coupled finite element formulation for polyethylene wear in total hip arthroplasty

    Microsoft Academic Search

    Tina A. Maxian; Thomas D. Brown; Douglas R. Pedersen; John J. Callaghan

    1996-01-01

    A three-dimensional, nonlinear contact finite element (FE) model of total hip replacement, linked to a sliding-distance-coupled wear algorithm, was used to study polyethylene wear rates for three different femoral head sizes. Hip resultant loads from a validated gait analysis model were used in the FE model to determine contact stress distributions on the polyethylene bearing surface, for 16 discrete instants

  14. Synthesis, Characterization, and Photocrosslinking of Acrylated and Methacrylated Polyethylene Diepoxymethylene Tartramides

    Microsoft Academic Search

    N. Rajeswari; E. R. Nagarajan; D. Kumar

    2004-01-01

    Polyethylene tartramide (PT) containing free hydroxyl groups was prepared by the reaction of diethyl tartrate (DT) with the diamine, 1,2?diaminoethane at room temperature without the use of any solvent or catalyst. The reaction of PT with epichlorohydrin produces polyethylene diepoxymethylene tartramide (PDT). The photocrosslinkable acrylated and methacrylated monomers namely, poly[N?aminoethyl?(di???hydroxy???acryloyl)tartramide] (APDT) and poly[N?aminoethyl?(di???hydroxy???methacryloyl)tartramide] (MAPDT) were synthesized by the ring?opening reaction

  15. Biphasic hydroformylation of olefins using a novel water soluble rhodium polyethylene glycolate catalyst

    Microsoft Academic Search

    Thomas Borrmann; Herbert W. Roesky; Uwe Ritter

    2000-01-01

    The highly reactive water-soluble hydroformylation catalyst, rhodium polyethylene glycolate (Rh(PEG)x), prepared by the reaction of polyethylene glycol and rhodium trichloride hydrate, was used as a catalyst for hydroformylation reactions of olefins, such as dodec-1-ene, 2.4.4-trimethylpent-1-ene and styrene, in biphasic systems. The reactions were done in a broad temperature range and at a pressure range from 7 to 12 MPa. Turnover

  16. Rheological, thermal, and mechanical properties of poly(ethylene naphthalate)\\/poly(ethylene terephthalate) blends

    Microsoft Academic Search

    Mutsumasa Kyotani; Wiwik Pudjiastuti; Akhtar Saeed

    1999-01-01

    Structural, Theological, thermal, and mechanical properties of blends of poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) obtained by melt blending were investigated using capillary rheometry, differential scanning calorimetry (DSC), scanning electron microscopic (SEM) observation, tensile testing. X-ray diffraction, and H nuclear magnetic resonance (NMR) measurements. The melt Theological behavior of the PEN\\/PET blends was very similar to that of the

  17. Infrared characterization of complex sandwich structures: Heparin immobilized on polyethylene surfaces

    Microsoft Academic Search

    Lars Bertilsson; Hans Elwing; Bo Liedberg; Olle Larm; Johan Risenfeld; Elisabeth Scholander

    1991-01-01

    Surface modification to provide, e.g., a biocompatible surface is an important molecular engineering method. As an example the FTIR-Attenuated Total Reflection (ATR) method has been applied to follow the different steps in the immobilization process of heparin on polyethylene (PE). This chemical multicomponent modification process is based on van der Waals and electrostatic interaction between alternating layers of cross-linked polyethylene

  18. Molecular modelling of the elastic behaviour of poly(ethylene terephthalate) network chains

    Microsoft Academic Search

    J. I. Cail; R. F. T. Stepto

    2003-01-01

    The Monte-Carlo (MC) method developed to model the elastomeric stress–strain behaviour of polyethylene (PE) and poly(dimethyl siloxane) (PDMS) networks and the stress–optical behaviour of PE networks is now applied to the stress–strain behaviour of poly(ethylene terephthalate) (PET) networks. In keeping with the previous results for PE and PDMS networks, increases in the proportions of fully extended chains with macroscopic deformation

  19. High pressure crystallized poly(ethylene terephthalate): high crystallinity and large extended-chain crystals

    Microsoft Academic Search

    Li Liangbin; Huang Rui; Lu Ai; Nie Fude; Hong Shiming; Wang Chunmei; Zhong Yuemao; Wang Dong

    2000-01-01

    High-pressure crystallized poly(ethylene terephthalate) samples were investigated with differential scanning calorimetry and scanning electron microscopy. Poly(ethylene terephthalate) (PET) extended-chain crystals with thickness up to 6?m were formed under high pressure. Calorimetric measurements showed that the highest melting point of these samples was 553.13K without superheating, and the melting enthalpy was up to 138.2J\\/g, higher than the value of ideal PET

  20. THA with Highly Cross-linked Polyethylene in Patients 50 Years or Younger

    Microsoft Academic Search

    Derek S. Shia; John C. Clohisy; Mark F. Schinsky; John M. Martell; William J. Maloney

    2009-01-01

    Highly cross-linked polyethylene has been associated with low in vitro wear, but also has decreased in vitro ultimate yield\\u000a strength. We therefore asked whether highly cross-linked polyethylene would result in lower outcome scores, wear, or early\\u000a failure in a young patient population. Seventy THAs in 64 patients were performed using a highly cross-linked (electron beam-irradiated\\u000a to 9 Mrads) acetabular liner

  1. A study on sliding wear mechanism of ultrahigh molecular weight polyethylene\\/polypropylene blends

    Microsoft Academic Search

    Gongde Liu; Yingzi Chen; Huilin Li

    2004-01-01

    This paper explores anti-wear properties and wear mechanism for ultrahigh molecular weight polyethylene (UHMWPE) and ultrahigh molecular weight polyethylene\\/polypropylene (UHMWPE\\/PP) blends, which were prepared by melt extruding through a single-screw extruder, and were conducted sliding wear tests with MM-200 wear tester by sliding against 45# steel ring of a surface roughness about 0.015?m. Results show that anti-wear properties of UHMWPE

  2. Use of ultrahigh-molecular-weight polyethylene for bearing materials on a steel substrate

    Microsoft Academic Search

    V. N. Kornopol’tsev; D. M. Mognonov; I. A. Farion; V. E. Nikitin; V. A. Zakharov

    2009-01-01

    The paper presents results on the usage of ultrahigh-molecular-weight polyethylene for manufacture of antifrictional materials\\u000a on a steel substrate. Hot molding regimes are determined for the production of polymeric components. The optimum degree of\\u000a ultrahigh-molecular-weight polyethylene filling with graphite is determined (about 50 mass %) for the purpose of achieving\\u000a perfect triboengineering parameters of sheet antifrictional materials during operation against

  3. Fixation of ultrahigh-molecular-weight polyethylene liners to metal-backed acetabular cups

    Microsoft Academic Search

    Victor G. Williams; Leo A. Whiteside; Stephen E. White; Daniel S. McCarthy

    1997-01-01

    Locking mechanisms and metal-liner interface surfaces of six modular acetabular systems were evaluated to determine their effect on micromotion and backside wear of the polyethylene liner. Rotational and axial motion between the metal shell and polyethylene liner was measured in the Duraloc (DePuy, Warsaw, IN), Harris-Galante (Zimmer, Warsaw, IN), Impact (Biomet, Warsaw, IN), Lip Loc (Biomet). Precision Osteoloc (Howmedica, Rutherford,

  4. Partial-Discharge Phenomena and the Effect of Their Constituents on Polyethylene

    Microsoft Academic Search

    Christian Mayoux

    1976-01-01

    A method of investigating partial-discharge phenomena andtheir effect on polyethylene is described. A physical study was carriedout with air at atmospheric pressure and gaps between 2 and 14 mm.It is shown, that with this range of gaps and with dielectric walls, astreamer process appears as in the case of a positive point and a metallicplane.The evolution of the polyethylene samples

  5. A transparent, hazy, and strong macroscopic ribbon of oriented cellulose nanofibrils bearing poly(ethylene glycol).

    PubMed

    Tang, Hu; Butchosa, Núria; Zhou, Qi

    2015-03-25

    A macroscopic ribbon of oriented cellulose nanofibrils bearing polyethylene glycol is fabricated by stretching the cellulose nanofibrils network structure in the hydrogel state. The covalently grafted polyethylene glycol on the nanofibril surface facilitates the alignment and compartmentalization of individual nanofibrils in the ribbon. The ribbon has ultrahigh tensile strength (576 ± 54 MPa), modulus (32.3 ± 5.7 GPa), high transparency, and haze. PMID:25665182

  6. Structure and morphology of ionic polymer networks modified with poly(ethylene glycol)

    Microsoft Academic Search

    Petr Bures

    2001-01-01

    Copolymer networks of poly(acrylic acid) (PAA) grafted with poly(ethylene glycol) (PEG) were synthesized by UV initiated free-radical solution polymerization using tetraethylene glycol dimethacrylate as a crosslinking agent. Methacrylates of poly(ethylene glycol) 2000 and 5000 were synthesized by the dicyclohexylcarbodiimide method to allow for a greater control of the molecular architecture of the copolymer networks. The fraction of ionic groups in

  7. Microgels of polyaspartamide and poly(ethylene glycol) derivatives obtained by ?-irradiation

    Microsoft Academic Search

    Giovanna Pitarresi; Mariano Licciardi; Emanuela Fabiola Craparo; Elio Calderaro; Giuseppe Spadaro; Gaetano Giammona

    2002-01-01

    The copolymer PHG based on ?,?-poly(N-2-hydroxyethyl)-dl-aspartamide (PHEA) functionalized with glycidyl methacrylate has been exposed in aqueous solution to a ?-ray source at different irradiation doses (2, 2.5 and 3.5kGy), alone or in combination with poly(ethylene glycol)dimethacrylate (PEGDMA) or poly(ethylene glycol)diacrylate (PEGDA). The irradiation produces microgel systems that have been characterized by viscosity measurements. Lyophilization of microgels gives rise to samples

  8. Multiple Ion Implantation Effects on Wear and Wet Ability of Polyethylene Based Polymers

    Microsoft Academic Search

    L. Torrisi; A. M. Visco; N. Campo

    2004-01-01

    Polyethylene based polymers were ion implanted with multiple irradiations of different ions (N+, Ar+ and Kr+) at energies between 30 keV and 300 keV and doses ranging between 1013 and 1016 ions\\/cm2. The ion implantation dehydrogenises the polyethylene inducing cross-link effects in the residual polymer carbons. At high doses the irradiated surface show properties similar to graphite surfaces. The depth

  9. Effect of long chain branching on rheological properties of metallocene polyethylene

    Microsoft Academic Search

    D. Yan; W.-J. Wang; S. Zhu

    1999-01-01

    Polyethylenes (PE) with long chain branching (LCB) densities up to 0.44 carbons\\/10?000 carbons and narrow molecular weight distributions were synthesized using a continuous stirred-tank reactor (CSTR) with the Dow Chemical's constrained geometry catalyst system, CGC-Ti\\/TPFPB\\/MMAO, in Isopar E solution at 500psig and 140–190°C. Rheological properties of these metallocene polyethylenes (mPE) were evaluated and correlated to the LCB density. Measurements included

  10. Polyethylene pyrolysis: Theory and experiments for molecular-weight-distribution kinetics

    Microsoft Academic Search

    Naime A. Sezgi; Wang S. Cha; J. M. Smith; Ben J. McCoy

    1998-01-01

    A novel reactor for pyrolysis of a polyethylene melt stirred by bubbles of flowing nitrogen gas at atmospheric pressure permits uniform-temperature depolymerization. Sweep-gas experiments at temperatures 370--410 C allowed pyrolysis products to be collected separately as reactor residue (solidified polyethylene melt), condensed vapor, and uncondensed gas products. Molecular-weight distributions (MWDs) determined by gel permeation chromatography indicated that random scission and

  11. Thermal properties and degradation characteristics of polylactide, linear low density polyethylene, and their blends

    Microsoft Academic Search

    Gursewak Singh; Haripada Bhunia; Anita Rajor; Veena Choudhary

    2011-01-01

    Melt blending of linear low density polyethylene (LLDPE) and polylactide (PLLA) was performed in an extrusion mixer with post\\u000a extrusion blown film attachment with and without compatibilizer-grafted low density polyethylene maleic anhydride. The blend\\u000a compositions were optimized for tensile properties as per ASTM D 882-91. Based on this, LLDPE 80 (80 wt% LLDPE & 20 wt% PLLA)\\u000a and M-g-L 80\\/4 (80 wt% LLDPE,

  12. Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP)

    Microsoft Academic Search

    D. S. Achilias; C. Roupakias; P. Megalokonomos; A. A. Lappas; ?. V. Antonakou

    2007-01-01

    The recycling of either model polymers or waste products based on low-density polyethylene (LDPE), high-density polyethylene (HDPE) or polypropylene (PP) is examined using the dissolution\\/reprecipitation method, as well as pyrolysis. In the first technique, different solvents\\/non-solvents were examined at different weight percent amounts and temperatures using as raw material both model polymers and commercial products (packaging film, bags, pipes, food-retail

  13. Long range inspection of polyethylene coated steel pipes by using guided waves

    Microsoft Academic Search

    Hyeon Jae Shin; Sung-Jin Song; Joon Soo Park

    2001-01-01

    Ultrasonic guided waves were explored to apply for the long range inspection of polyethylene coated steel gas pipes. The dimensions of the steel pipe are 190.7 mm outside diameter and 5.3 mm thick. The outside surface of the pipe is coated by a polyethylene layer of 1.9±0.5 mm thick. Non-axisymmetric guided waves were excited on the outside surface of the

  14. Long range inspection of polyethylene coated steel pipes by using guided waves

    Microsoft Academic Search

    Hyeon Jae Shin; Sung-Jin Song; Joon Soo Park

    2001-01-01

    Ultrasonic guided waves were explored to apply for the long range inspection of polyethylene coated steel gas pipes. The dimensions of the steel pipe are 190.7 mm outside diameter and 5.3 mm thick. The outside surface of the pipe is coated by a polyethylene layer of 1.9+\\/-0.5 mm thick. Non-axisymmetric guided waves were excited on the outside surface of the

  15. Multicolor Upconversion Nanoparticles for Protein Conjugation

    PubMed Central

    Wilhelm, Stefan; Hirsch, Thomas; Patterson, Wendy M.; Scheucher, Elisabeth; Mayr, Torsten; Wolfbeis, Otto S.

    2013-01-01

    We describe the preparation of monodisperse, lanthanide-doped hexagonal-phase NaYF4 upconverting luminescent nanoparticles for protein conjugation. Their core was coated with a silica shell which then was modified with a poly(ethylene glycol) spacer and N-hydroxysuccinimide ester groups. The nanoparticles were characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and dynamic light scattering. The N-hydroxysuccinimide ester functionalization renders them highly reactive towards amine nucleophiles (e.g., proteins). We show that such particles can be conjugated to proteins. The protein-reactive UCLNPs and their conjugates to streptavidin and bovine serum albumin display multicolor emissions upon 980-nm continuous wave laser excitation. Surface plasmon resonance studies were carried out to prove bioconjugation and to compare the affinity of the particles for proteins immobilized on a thin gold film. PMID:23606910

  16. The use of poly(ethylene glycol)-block-poly(lactic acid) derived copolymers for the rapid creation of biomimetic surfaces.

    PubMed

    Tessmar, Jörg; Mikos, Antonios; Göpferich, Achim

    2003-11-01

    For many tissue engineering applications biomimetic or bioactive polymers would allow for a more precise control of cell behavior in growing tissues than has so far been possible. For this application recently developed amine reactive diblock copolymers (N-succinimidyl tartrate monoamine poly(ethylene glycol)-block-poly(D,L-lactic acid) [ST-NH-PEGxPLAy]) were investigated concerning their reactivity in binding model substances. Their ability to covalently immobilize proteins on their surfaces was examined using polymer films with amine reactive surfaces. Furthermore, thiol reactive polymers were obtained by attaching N-succinimidyl 3-maleinimido propionate, a thiol reactive linker to monoamine poly(ethylene glycol)-block-poly(D,L-lactic acid) [H2N-PEGxPLAy]. This allowed the immobilization of proteins carrying free thiol groups. The amine and thiol reactive polymers were characterized by 1H-NMR spectroscopy and gel permeation chromatography (GPC). Investigation of glass transitions temperatures using modulated differential scanning calorimetry proved suitability for the fabrication of polymeric scaffolds for tissue engineering applications. The functionality of the polymers was demonstrated by investigating their ability to bind model amines, like the fluorescent dye EDANS. Moreover, insulin and somatostatin were covalently attached to the active linker groups via amine and thiol groups. The polymers will permit covalently attaching different bioactive molecules, such as growth and differentiation factors, with fast and gentle procedures securing their biological activity. PMID:12922157

  17. High-density Polyethylene Damage at Extreme Tensile Conditions

    NASA Astrophysics Data System (ADS)

    Brown, Eric; Furmanski, Jevan; Ramos, Kyle; Dattelbaum, Dana; Jensen, Brian; Iverson, Adam; Carlson, Carl; Fezzaa, Kamel; Trujillo, Carl; Martinez, Daniel; Gray, George; Patterson, Brian

    2013-06-01

    In situ and post mortem observations of the dynamic tensile failure and damage evolution of high-density polyethylene (HDPE) are made during Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) loading. The Dyn-Ten-Ext technique probes the tensile response of materials at large strains (>1) and high strain-rates (>10,000/s) by firing projectiles through a conical die. Depending on the extrusion ratios and velocities, HDPE damage varies from gross deformation with substantial internal damage, to a stable jet with finite particulation, to catastrophic fragmentation. Postmortem sectioning elucidates a mechanism of internal damage inception and progression oblique to the extrusion axis. X-ray computed tomography corroborates a shear damage mechanism with an internal damage zone aligned with the extrusion axis. In situ measurements of damage are made with the impact system for ultrafast synchrotron experiments (IMPULSE) designed for using the advanced imaging and X-ray methods available at the Advanced Photon Source. Time resolved phase-contrast imaging elucidates the evolution of damage features during dynamic loading that is observed in post mortem sectioning and tomography.

  18. Cell adhesion and proliferation on polyethylene grafted with Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Kasálková, N. Slepi?ková; Slepi?ka, P.; Kolská, Z.; Sajdl, P.; Ba?áková, L.; Rimpelová, S.; Švor?ík, V.

    2012-02-01

    Plasma treatment and subsequent Au nano-particles grafting of polyethylene (PE) lead to changes in surface morphology, roughness and wettability, significantly increasing the attractiveness of the material for cells. The PE samples were exposed to argon plasma. Plasma modified PE was chemically grafted by immersion to biphenyldithiol and consequently into solution of Au nano-particles. Changes in chemical structure of the modified PE were studied using X-ray Photoelectron Spectroscopy (XPS) and electrokinetic analysis ( ?-potential). The surface wettability of the modified PE samples was examined by measurement of the contact angle by standard goniometry. The surface morphology of the plasma modified PE and that grafted with Au nano-particles was studied by Atomic Force Microscopy (AFM). The modified PE samples were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation were studied. Chemically bounded biphenyldithiol increases the number of the incorporated gold nano-particles and changes sample surface properties. The presence of the biphenyldithiol and the gold nano-particles on the PE surface influences dramatically adhesion and proliferation of VSMCs.

  19. Analysis of functionalized polyethylene terephthalate with immobilized NTPDase and cysteine.

    PubMed

    Muthuvijayan, Vignesh; Gu, Jun; Lewis, Randy S

    2009-11-01

    Polyethylene terephthalate (PET) was functionalized to introduce carboxyl groups onto its surface by a carboxylation technique. Surface and bulk properties, such as possible surface deterioration, surface roughness and the mechanical strength of the carboxylated polymers, were studied and compared with those of aminolyzed and hydrolyzed PET. Atomic force microscopy studies showed that unlike aminolysis and hydrolysis, which increased the surface roughness significantly due to cracking and pitting, the surface roughness of unmodified and carboxylated PET were comparable. While hydrolysis and aminolysis of PET resulted in significant loss of strength, tensile testing revealed that unmodified and carboxylated polymers had similar strength. The development of mechanically stable, functionalized PET would vastly improve the biomedical applications of this polymer. To understand the potential for improving biomedical applications, biologically active molecules, namely nucleoside triphosphate diphosphohydrolase (NTPDase) and cysteine, were immobilized on the carboxylated PET using amide bonds. NTPDase was also immobilized to aminolyzed PET using imine bonds, while cysteine was immobilized on aminolyzed PET using both imine and amide bonds. Attachment of NTPDase and cysteine was verified by analyzing the NTPDase activity and the cysteine surface concentration. The stability of these immobilizations was also studied. PMID:19477307

  20. Safety Evaluation of Polyethylene Glycol (PEG) Compounds for Cosmetic Use.

    PubMed

    Jang, Hyun-Jun; Shin, Chan Young; Kim, Kyu-Bong

    2015-06-01

    Polyethylene glycols (PEGs) are products of condensed ethylene oxide and water that can have various derivatives and functions. Since many PEG types are hydrophilic, they are favorably used as penetration enhancers, especially in topical dermatological preparations. PEGs, together with their typically nonionic derivatives, are broadly utilized in cosmetic products as surfactants, emulsifiers, cleansing agents, humectants, and skin conditioners. The compounds studied in this review include PEG/PPG-17/6 copolymer, PEG-20 glyceryl triisostearate, PEG-40 hydrogenated castor oil, and PEG-60 hydrogenated castor oil. Overall, much of the data available in this review are on PEGylated oils (PEG-40 and PEG-60 hydrogenated castor oils), which were recommended as safe for use in cosmetics up to 100% concentration. Currently, PEG-20 glyceryl triisostearate and PEGylated oils are considered safe for cosmetic use according to the results of relevant studies. Additionally, PEG/PPG-17/6 copolymer should be further studied to ensure its safety as a cosmetic ingredient. PMID:26191379

  1. Displacement of poly(ethylene oxide) from layered nanocomposites

    SciTech Connect

    Oriakhi, C.O.; Lerner, M.M. [Oregon State Univ., Corvallis, OR (United States)

    1996-12-31

    The reaction of tetraethylammonium salt with the nanocomposites K{sub 0.2}(C{sub 2}H{sub 4}O){sub 2.3}M{sub 0.9}PS{sub 3} (M = Mn, Cd) under ambient conditions results in the rapid and quantitative displacement of the polymer to form the alkylammonium intercalate. The displacement reactions go to completion with no polymer degradation after initial formation of the nanocomposite. Pseudo-reaction rates (0.0 to 7.8 min{sup {minus}1}) are obtained using temporal XRD studies for different cations, concentrations, and polymer molecular weights. A strong rate dependence is observed for alkylammonium concentration, and displacement occurs very slowly, or only to a limited extent, for tetramethylammonium, tetrapropylammonium, and tetrabutylammonium salts. Rapid displacement is also reported for other layered nanocomposites containing poly(ethylene oxide), including those with Li{sub x}MoS{sub 2}, Na-montmorillonite, and Li{sub x}MoO{sub 3}.

  2. Molecular Dynamics Study of Stiffness in Polystyrene and Polyethylene

    E-print Network

    Hamed Nazarpourfard; Mahdi Ahmadi Borji

    2015-04-26

    In this paper, we have studied polystyrene (PS) and polyethylene (PE) stiffness by 3-dimensional Langevin Molecular Dynamics simulation. Hard polymers have a very small bending, and thus, their end-to-end distance is more than soft polymers. Quantum dot lasers can be established as colloidal particles dipped in a liquid and grafted by polymer brushes to maintain the solution. Here by a study on molecular structures of PS and PE, we show that the principle reason lies on large phenyl groups around the backbone carbons of PS, rather than a PE with Hydrogen atoms. Our results show that the mean radius of PS random coil is more than PE which directly affects the quantum dot maintenance. In addition, effect of temperature increase on the mean radius is investigated. Our results show that by increasing temperature, both polymers tend to lengthen, and at all temperatures a more radius is predicted for PS rather than PE, but interestingly, with a difference in short and long chains. We show that stiffness enhancement is not the same at short and long polymers and the behavior is very different. Our results show a good consonance with both experimental and theoretical studies.

  3. Short-term isothermal annealing of polyethylene single crystals

    NASA Astrophysics Data System (ADS)

    Grubb, David T.; Liu, J. Jui-Hsiang

    1985-10-01

    Polyethylene single-crystal mats 20 ?m thick were heated to the annealing temperatures (120-132 °C) in less than 1 s. The Cornell High Energy Synchrotron Source (CHESS) and a TV detector system were used to obtain wide- and small-angle x-ray scattering patterns from these mats during annealing with a time resolution of 0.3 s. Both whole polymer and a molecular weight fraction showed rapid melting and recrystallization, with a minimum crystallinity at 2-4 s after reaching the annealing temperature. Recrystallization was essentially complete in 60-90 s and most curves could be fitted to the Johnson-Mehl-Avrami equation with exponent n=1. Two-thirds of the material could be molten before there was any loss of the original crystal orientation. The increase in long period was discontinuous at high annealing temperature. The original small-angle long-spacing peak quickly lost intensity as crystallinity fell and a new peak appeared at larger long spacing. This new long spacing increased with time for the whole polymer and was constant for the fractionated material. At lower annealing temperatures the amount melting was small and the small-angle intensity and long period increased continuously.

  4. Synthesis and properties of oligodeoxyribonucleotide-polyethylene glycol conjugates.

    PubMed

    Jäschke, A; Fürste, J P; Nordhoff, E; Hillenkamp, F; Cech, D; Erdmann, V A

    1994-11-11

    Pools of oligonucleotide conjugates consisting of 10-400 different molecular species were synthesized. The conjugates contained a varying number of ethylene glycol units attached to 3'-terminal, 5'-terminal and internal positions of the oligonucleotides. Conjugate synthesis was performed by phosphoramidite solid phase chemistry using suitably protected polyethylene glycol phosphoramidites and PEG-derivatized solid supports containing polydisperse PEGs of various molecular weight ranges. The pools were analyzed and fractionated by chromatographic and electrophoretic techniques, and the composition of isolated conjugates was revealed by matrix-assisted laser desorption/ionization mass spectrometry. The number and attachment sites of coupled ethylene glycol units greatly influence the hydrophobicity of the conjugates, as well as their electrophoretic mobilities. Conjugation had little effect on the hybridization behavior of oligonucleotide conjugates with unmodified complementary oligonucleotide strands. Melting temperatures were between 67 and 73 degrees C, depending on the size and number of coupled PEG chains, compared to 68 degrees C for the unmodified duplex. Conjugates with PEG coupled to both 3'- and 5'-terminal positions showed a more than 10-fold increase in exonuclease stability. PMID:7984434

  5. Surface modification of polypropylene membrane by polyethylene glycol graft polymerization.

    PubMed

    Abednejad, Atiye Sadat; Amoabediny, Ghasem; Ghaee, Azadeh

    2014-09-01

    Polypropylene hollow fiber microporous membranes have been used in a wide range of applications, including blood oxygenator. The hydrophobic feature of the polypropylene surface causes membrane fouling. To minimize fouling, a modification consisting of three steps: surface activation in H2 and O2 plasma, membrane immersion in polyethylene glycol (PEG) and plasma graft polymerization was performed. The membranes were characterized by contact angle measurement, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Oxygen transfer of modified membranes was also tested. The stability of grafted PEG was measured in water and in phosphate buffer saline (PBS) at 37°C. Blood compatibility of modified surfaces was evaluated by the platelet adhesion method. Water contact angel reduction from 110° to 72° demonstrates the enhanced hydrophilicity, and XPS results verify the presence of oxygenated functional groups due to the peak existence in 286 eV as a result of PEG grafting. The results clearly indicate that plasma graft-polymerization of PEG is an effective way for antifouling improvement of polypropylene membranes. Also, the results show that oxygen transfer changes in PEG grafted membranes are not significant. PMID:25063140

  6. Evaluation of hybrid rubber-polyethylene industrial battery separators

    NASA Astrophysics Data System (ADS)

    Wimberly, Rick; Miller, Jamie; Brilmyer, George

    Antimonial lead alloys continue to play a key role in the overall success of the lead-acid battery in deep cycle applications. In markets such as motive power and golf car, these alloys have long been known to assist the performance of the positive plate by promoting a healthy, grid-active material interface. Antimony, on the other hand, is a well-established poison to the negative plate and ultimately leads to gassing, water-loss and cell failure. Reports in the literature indicate that specific battery separator materials may be used to delay the onset of gassing by suppressing the effects of antimony. Literature findings also suggest that the suppression effect may be due to a combination of the chemical make-up of the separator and its physical attributes. It is the intention of this paper to introduce a novel method for evaluating battery separator materials in terms of their ability to suppress the deleterious effects of antimony. Results presented here indicate that the chemical composition of the separator is a controlling factor in suppressing the influence of antimony in the lead-acid battery. Initial information on the characteristics of a new hybrid rubber-polyethylene battery separator is also presented.

  7. Small-angle neutron scattering study of dynamically polarized polyethylenes

    NASA Astrophysics Data System (ADS)

    Noda, Yohei; Kumada, Takayuki; Hashimoto, Takeji; Koizumi, Satoshi

    2009-09-01

    We carried out a small-angle neutron scattering (SANS) study of dynamically polarized polyethylene (PE) samples doped with 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). The transmission of the PE with almost fully polarized neutrons (98.5%) increased with increasing the proton polarization, P. The incoherent scattering cross section decreased with increasing P. The effect of P on the polarized neutrons’ transmission and the incoherent scattering cross section agreed well with the theory. The q-dependence of the coherent scattering, which reflects a two-phase structure of PE composed of crystalline and amorphous domains, was kept unchanged by the proton polarization, but the intensity increased by a factor of 3 and 6 for P=+23% and -23%, respectively. The results mean that the contrast between the two phases was successfully enhanced by a dynamic nuclear polarization (DNP) technique. However, the enhancement is only 1/13-1/16 of the enhancement calculated by assuming a homogeneous polarization through the PE sample. The discrepancy suggests that P in amorphous domains (25%) should be higher than that in crystalline domains (22%) by 3%, which in turn may suggest the partial depolarization of proton spins on the way of the spin diffusion from amorphous domains, where TEMPO radicals localize, to crystalline domains.

  8. Polyethylene glycol protects primary hepatocytes during supercooling preservation.

    PubMed

    Puts, C F; Berendsen, T A; Bruinsma, B G; Ozer, Sinan; Luitje, Martha; Usta, O Berk; Yarmush, M L; Uygun, K

    2015-08-01

    Cold storage (at 4°C) offers a compromise between the benefits and disadvantages of cooling. It allows storage of organs or cells for later use that would otherwise quickly succumb to warm ischemia, but comprises cold ischemia that, when not controlled properly, can result in severe damage as well by both similar and unique mechanisms. We hypothesized that polyethylene glycol (PEG) 35kDa would ameliorate these injury pathways and improve cold primary hepatocyte preservation. We show that reduction of the storage temperature to below zero by means of supercooling, or subzero non-freezing, together with PEG supplementation increases the viable storage time of primary rat hepatocytes in University of Wisconsin (UW) solution from 1day to 4days. We find that the addition of 5% PEG 35kDa to the storage medium prevents cold-induced lipid peroxidation and maintains hepatocyte viability and functionality during storage. These results suggest that PEG supplementation in combination with supercooling may enable a more optimized cell and organ preservation. PMID:25936340

  9. Polymeric cracking of waste polyethylene terephthalate to chemicals and energy.

    PubMed

    Brems, Anke; Baeyens, Jan; Vandecasteele, Carlo; Dewil, Raf

    2011-07-01

    Polyethylene terephthalate (PET) is a widely used thermoplastic. PET residues represent on average 7.6 wt% of the different polymer wastes in Europe. Pyrolysis of these wastes is attracting increasing interest, and PET is a potential candidate for this thermal process. The paper measures and discusses the kinetics of the pyrolysis reaction in terms of the reaction rate constants as determined by dynamic thermogravimetric analysis, with special emphasis on the required heating rate to obtain relevant results. The product yields and compositions are also determined. Gaseous products represent 16-18 wt%. The amounts of condensables and carbonaceous residue are a function of the operating mode, with slow pyrolysis producing up to 24 wt% of carbonaceous residue. Major condensable components are benzoic acid, monovinyl terephthalate, divinyl terephthalate, vinyl benzoate, and benzene. The present paper complements previous literature findings by (1) the study of the influence of the heating rate on the reaction kinetics in dynamic pyrolysis tests, (2) the isothermal investigation in a fluidized bed reactor to pyrolyze PET, and (3) the assessment of upgrading and recovery of the products. The paper concludes with a proposed reactor recommendation for PET pyrolysis, in either the bubbling or circulating fluidized bed operating mode. PMID:21850826

  10. Delamination toughness of ultra high molecular weight polyethylene (UHMWPE) composites

    NASA Astrophysics Data System (ADS)

    Porras, A.; Tellez, J.; Casas-Rodriguez, J. P.

    2012-08-01

    Ultra high molecular weight polyethylene (UHMWPE) fibre reinforced composites are an important group of material for armours solutions, where their unique combination of properties could be utilized. A commonly observed failure mode in this kind of unidirectional laminated composites under impact ballistic is delamination between the composite layers. In the present study, an investigation on the delamination toughness behaviour exhibited by UHMWPE composites laminated was made. The interlaminar Mode II critical strain energy release rates of (UHMWPE) fibre reinforced composites were characterized using the End Notch Flexural (ENF) test. Critical strain energy release rate was obtained from the load - deflection test data using the beam theory expression. It was found that the energy release rate of the composite exhibited a very low value of around 60J/m2 using a moulding pressure of approximately 1200 psi. In order to analyse the delamination resistance of composite, the effects of changing the manufacture process variables and the use of a thermoplastic adhesive film in the composites were investigated. The composite laminates were produced by hot compressing moulding using a film-stacking procedure. It was found that the damage resistance of the UHMWPE composite was influenced by the manufacture method, which affects the Mode II interlaminar fracture toughness and the ballistic response of composites.

  11. Conversion of post consumer polyethylene to the biodegradable polymer polyhydroxyalkanoate.

    PubMed

    Guzik, Maciej W; Kenny, Shane T; Duane, Gearoid F; Casey, Eoin; Woods, Trevor; Babu, Ramesh P; Nikodinovic-Runic, Jasmina; Murray, Michael; O'Connor, Kevin E

    2014-05-01

    A process for the conversion of post consumer (agricultural) polyethylene (PE) waste to the biodegradable polymer medium chain length polyhydroxyalkanoate (mcl-PHA) is reported here. The thermal treatment of PE in the absence of air (pyrolysis) generated a complex mixture of low molecular weight paraffins with carbon chain lengths from C8 to C32 (PE pyrolysis wax). Several bacterial strains were able to grow and produce PHA from this PE pyrolysis wax. The addition of biosurfactant (rhamnolipids) allowed for greater bacterial growth and PHA accumulation of the tested strains. Some strains were only capable of growth and PHA accumulation in the presence of the biosurfactant. Pseudomonas aeruginosa PAO-1 accumulated the highest level of PHA with almost 25 % of the cell dry weight as PHA when supplied with the PE pyrolysis wax in the presence of rhamnolipids. The change of nitrogen source from ammonium chloride to ammonium nitrate resulted in faster bacterial growth and the earlier onset of PHA accumulation. To our knowledge, this is the first report where PE is used as a starting material for production of a biodegradable polymer. PMID:24413975

  12. Crystal ageing in irradiated ultra high molecular weight polyethylene.

    PubMed

    Barron, D; Collins, M N; Flannery, M J; Leahy, J J; Birkinshaw, C

    2008-06-01

    Medical grade ultra high molecular weight polyethylene (UHMWPE) of two molecular weights has been gamma irradiated in air to give received doses of 3.5 and 10 Mrad and aged in air for 25 months. Differential scanning calorimetry and wide and small angle X-ray diffraction (WAX and SAX) techniques and transmission electron microscopy have been used to characterize the materials. Polymer from an orthopaedic component, retrieved 10 years after implantation, has been subjected to the same analytical programme. The X-ray diffraction data shows that following irradiation two events occur with time, first a crystal refinement process, indicated by pronounced sharpening of the SAX peak, and secondly growth of a new crystal population of reduced lamellae thickness compared to the original crystal structures, shown by the development of a bimodal SAX pattern. Following irradiation crystallinity increases with time and this second crystal population makes a significant contribution to that increase. The retrieved component shows full development of these processes. It is considered that these crystallographic changes with time are responsible for the observed time dependent changes in the mechanical properties of air irradiated UHMWPE. PMID:18071874

  13. High sensitivity of positron annihilation to thermal oxidation of polyethylene

    NASA Astrophysics Data System (ADS)

    Ito, Kenji; Kobayashi, Yoshinori; Nanasawa, Atsushi

    2003-01-01

    We demonstrate the high sensitivity of positron annihilation to compositional changes related to the thermal degradation of polyethylene (PE). Positron annihilation ?-ray and lifetime measurements were conducted for PE films with and without antioxidant (1000-ppm Ciba® IRGANOX® 1076), subjected to heat treatment at 100 °C for different periods, to a maximum of 30 days. For the film without antioxidant, the positron Doppler parameter (S) and ortho-positronium formation probability (Io-Ps) appreciably decreased with increased heat treatment times, whereas they barely changed for the film with antioxidant. This, together with the Fourier transform infrared measurements, demonstrated that the variations of S and Io-Ps are caused by the thermal oxidation of PE. The S parameter was found to be sensitive to the early stage of degradation, where the carbonyl concentration is inferred to be lower than 100 ppm. The high sensitivity results from the large positron mobility in PE and from the high positron affinity of oxygen-containing polar groups. This work provides the basis for an application of positron annihilation to sensitive detection of the initial degradation of PE and other nonpolar polymers.

  14. Biphasic liquid mixtures of ionic liquids and polyethylene glycols.

    PubMed

    Rodríguez, Héctor; Francisco, María; Rahman, Mustafizur; Sun, Ning; Rogers, Robin D

    2009-12-14

    We have found that 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) can form immiscible liquid mixtures with some polyethylene glycols (PEGs). Binary mixtures of 1-ethyl-3-methylimidazolium chloride with PEG of molecular weight 1500, 2000, or 3400 g mol(-1), or of 1-butyl-3-methylimidazolium chloride with PEG of molecular weight 2000 or 3400 g mol(-1), have been found to give rise to entirely liquid, stable biphasic systems over a significant temperature range (from 333.15 K to 413.15 K), while mixtures of 1-ethyl-3-methylimidazolium chloride with PEG-1000 and 1-butyl-3-methylimidazolium chloride with PEG-1000 and PEG-1500 are miscible. The mutual immiscibility of the IL and the PEG increases as the temperature increases. The evolution of the composition of the phases in equilibrium with the molecular weight of the PEG, or with the variation of the length of the alkyl substituent chain of the imidazolium cation of the IL, has been explored. The trends observed are explained through the complexity of interactions present within the binary system. A thermodynamic analysis of the liquid-liquid equilibrium data indicates negative values for the change of enthalpy and entropy of mixing. The potential application of these biphasic, entirely liquid systems, with low volatility and good solvation properties, for the dissolution and separation of cellulose and lignin at elevated temperature has been preliminarily explored, although only modest results have been achieved to date. PMID:19924326

  15. Mechanical and swelling characterization of poly(N-isopropyl acrylamide -co- methoxy poly(ethylene glycol) methacrylate) sol-gels.

    PubMed

    Pollock, Jacob F; Healy, Kevin E

    2010-04-01

    The dimensional stability and rheological properties of a series of comb-like copolymers of N-isopropyl acrylamide (NIPAAm) and methoxy poly(ethylene glycol) methacrylate (mPEGMA), poly(NIPAAm-co-mPEGMA), with varying poly(ethylene glycol) (PEG) graft densities and molecular weights were studied. The thermoresponsive character of the copolymer solutions was investigated by kinetic and equilibrium swelling, as well as by static and dynamic mechanical analysis. Surface response mapping was employed to target particular compositions and concentrations with excellent dimensional stability and a relatively large change in dynamic mechanical properties upon thermoreversible gelation. The mechanical characteristics of the gels depended strongly upon concentration of total polymer and less so upon copolymer ratio. Increased PEG graft density was shown to slow the deswelling rate and increase the equilibrium water content of the gels. Upon gelation at sol concentrations of 1-20 wt.% the materials underwent no deswelling or syneresis and maintained stable gels with a large elastic regime and high yield strain (i.e. elastic and soft but tough), even within the Pascal range of complex shear moduli. These materials are unique in that they maintained a physiologically useful lower critical solution temperature (approximately 33 degrees C), despite having a high PEG content. Copolymers with a high PEG content and low polymer fraction were conveniently transparent in the gel phase, allowing visualization of cellular activity without disrupting the microenvironment. Mesenchymal stem cells showed good viability and proliferation in three-dimensional culture within the gels, despite the lack of ligand incorporation to promote cellular interaction. Multi-component matrices can be created through simple mixing of copolymer solutions and peptide-conjugated linear polymers and proteins to produce combinatorial microenvironments with the potential for use in cell biology, tissue engineering and medical applications. PMID:19941981

  16. Dielectric relaxations in poly(ethylene terephthalate), poly(ethylene 2,6-naphthalate) and their copolymers

    NASA Astrophysics Data System (ADS)

    Bravard, Shelly Packer

    Dielectric spectroscopy was performed on poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN), and their copolymers. Although PET and PEN have very similar chemical structure, their dielectric relaxation signatures are significantly different. PET has one subglass relaxation, beta, whereas PEN has two, beta and beta*. The beta relaxation in both polymers falls in the same frequency-temperature domain. The beta* relaxation in PEN falls between the beta and alpha relaxations. To determine the source of the beta* relaxation, copolymers of varying PET and PEN content were synthesized. Dielectric spectroscopy was performed on the copolymers, and the data for the copolymers were compared to that of PEN and PET. PEN and the copolymers all showed two subglass relaxations, beta and beta*. The beta relaxation was determined to be composed of two overlapping processes. Therefore, the beta relaxation was fit using a Composite Cole - Cole (CCC) equation. The CCC consists of two Cole Cole equations added together. The process occurring at higher frequency was called process 1 and the other process 2. Meanwhile, the beta* process was fit using a single Cole Cole equation. PET exhibited only a beta relaxation that was broader than the beta relaxation for PEN and the copolymers. The beta relaxation in PET was fit by adding three Cole - Cole equations together. The two higher frequency processes were similar in nature to the two processes used to fit the beta relaxation in the other polymers. The third and lower frequency or higher temperature process was similar to the beta* process in the other polymers. In all of the polymers, processes I and 2 are attributed to motions around the C - O ether bond and the C - C bond, respectively. Meanwhile, movement around the C(aromatic) C(carbonyl) bond is responsible for the beta* relaxation. In PET this involves the benzene ring while in PEN it involves the naphthalate group. Because the naphthalate group is so much bulkier than the benzene ring this motion has a higher activation energy in PEN than in PET. Therefore, in PEN and the copolymers, the beta* relaxation is resolved as a separate peak, while in PET it is the third component of a composite beta relaxation.

  17. Preparation and performance of form-stable polyethylene glycol\\/silicon dioxide composites as solid–liquid phase change materials

    Microsoft Academic Search

    Weilong Wang; Xiaoxi Yang; Yutang Fang; Jing Ding

    2009-01-01

    This work mainly involved the preparation and characterization of form-stable polyethylene glycol (PEG)\\/silicon dioxide (SiO2) composite as a novel solid–liquid phase change material (PCM). In this study, the polyethylene glycol\\/silicon dioxide composites as form-stable, solid–liquid phase change material (PCM) was prepared. In this new material, the polyethylene glycol acts as the latent heat storage material and silicon dioxide serves as

  18. Polyethylene glycol 4000 as a continuously administered non-absorbable faecal marker for metabolic balance studies in human subjects

    PubMed Central

    Wilkinson, R.

    1971-01-01

    The use of polyethylene glycol 4000 as a non-absorbable, continuously fed faecal marker is described. The intestinal handling and transit of polyethylene glycol is compared with that of chromium sesquioxide and barium sulphate. Polyethylene glycol is an acceptable non-absorbable faecal marker for calcium, phosphorus, and fatty acids, and has several features which commend its use in preference to insoluble chromium sesquioxide and barium sulphate particularly when marking water-soluble dietary constituents. PMID:18668835

  19. Self-assembly of silanated poly(ethylene glycol) on silicon and glass surfaces for improved haemocompatibility

    NASA Astrophysics Data System (ADS)

    Guo, Zhang; Meng, Sheng; Zhong, Wei; Du, Qiangguo; Chou, Laisheng L.

    2009-05-01

    Surface immobilization of poly(ethylene glycol) (PEG) is an effective method to produce a material surface with protein repulsive property. This property could be made permanent by using covalent grafting of the PEG molecules onto material surfaces. In this study, self-assembled monolayers (SAMs) of PEG on silicon-containing materials (silicon chip and glassplate) were obtained through a one-step coating procedure of one kind of silanated PEG molecules made through the reaction between monomethoxy PEG and 3-isocyanatopropyltriethoxysilane. Atomic force microscopy (AFM) and water static contact angle measurement were employed to investigate the surface topography and wettability of the PEGylated material surfaces. The changes in the topography and the water contact angle of the surfaces with time of incubation in PBS solution were also measured. The results revealed that stable and uniform self-assembled monolayers of PEG could be formed on silicon or glass surfaces by simply soaking the substrates in the solution of silanated PEGs. The covalent coupling of PEGs to the substrates was also confirmed. In order to evaluate the stability of the SAMs, blood compatibility of the modified glassplate surface was evaluated by measuring full blood activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT), as well as by scanning electron microscopy (SEM) analysis of the appearance of adherence and denaturation of blood platelets onto the glassplate. The silanated PEGs were shown to have good effect on the protein-repulsion as well as haemocompatibility of the substrates.

  20. A comparison of the wear and physical properties of silane cross-linked polyethylene and ultra-high molecular weight polyethylene.

    PubMed

    Sakoda, H; Voice, A M; McEwen, H M; Isaac, G H; Hardaker, C; Wroblewski, B M; Fisher, J

    2001-12-01

    Cross-linked polyethylenes are being introduced widely in acetabular cups in hip prostheses as a strategy to reduce the incidence of wear debris-induced osteolysis. It will be many years before substantial clinical data can be collected on the wear of these new materials. Silane cross-linked polyethylene (XLPE) was introduced into clinical practice in a limited series of acetabular cups in 1986 articulating against 22.225-mm alumina ceramic femoral heads and showed reduced wear rates compared with conventionally sterilized (gamma irradiation in air) ultra-high molecular weight polyethylene (UHMWPE). We compared the wear of XLPE manufactured in 1986 with the wear of UHMWPE manufactured in 1986 in nonirradiated and irradiated forms. In the nonirradiated forms, the wear of XLPE was 3 times less than UHWMPE when articulating against smooth counterfaces. The nonirradiated materials did not show signs of oxidation. In the irradiated forms, only UHMWPE showed high levels of oxidation, and this caused a substantial increase in wear. Antioxidants added to XLPE during processing gave resistance to oxidative degradation. When sliding against scratched counterfaces, the wear of UHMWPE increased by a factor of 2 to 3 times. Against the same scratched counterfaces, the wear of XLPE increased dramatically by 30 to 200 times. This difference may be attributed to the reduction in toughness of XLPE. Clinically, XLPE has been articulated against damage-resistant ceramic heads, and this probably has been an important factor in contributing to reduced wear. New cross-linked polyethylenes differ considerably from XLPE. This study indicates that it is prudent to examine the wear of new polyethylenes under a range of conditions that may occur in vivo. PMID:11740757

  1. Enhancement of the anti-tumor effect of DNA vaccination using an ultrasound-responsive mannose-modified gene carrier in combination with doxorubicin-encapsulated PEGylated liposomes.

    PubMed

    Yoshida, Mitsuru; Kawakami, Shigeru; Kono, Yusuke; Un, Keita; Higuchi, Yuriko; Maruyama, Kazuo; Yamashita, Fumiyoshi; Hashida, Mitsuru

    2014-11-20

    A method involving the use of doxorubicin-loaded polyethylene-glycol-modified liposomes and transfection using mannose-modified bubble lipoplexes in combination with ultrasound irradiation may be a promising approach to cancer treatment; it could not only suppress early-stage tumor growth but also enhance transfection efficacy in antigen-presenting cells, thus enhancing the therapeutic potential of a DNA vaccine. However, to date only limited research has been carried out regarding this combination DNA vaccination method for use in cancer therapy. In this study, we examined the anti-tumor effect of DNA vaccination using an ultrasound-responsive mannose-modified gene carrier combined with doxorubicin-encapsulated polyethylene-glycol-modified liposomes. Doxorubicin-encapsulated PEGylated liposomes activated transcriptional factors, such as nuclear factor-?B and AP-1 in the spleen; subsequently pUb-M, ubiquitylated melanoma-related antigen encoding plasmid DNA expression in splenic cells was significantly enhanced. Moreover, effective cytotoxic T-lymphocyte activities were stimulated by DNA vaccination combined with the administration of doxorubicin-encapsulated polyethylene-glycol-modified liposomes. Furthermore, potent DNA vaccine effects against established solid tumor and metastatic tumor derived from B16BL6 melanoma were observed. These results suggest that the combined use of DNA vaccination with doxorubicin-encapsulated polyethylene-glycol-modified liposomes could be an effective method for the treatment of melanoma using immunotherapy. PMID:25218184

  2. Permeation Resistance of Chlorinated Polyethylene Against Hydrazine Fuels

    NASA Technical Reports Server (NTRS)

    Waller, J. M.; Williams, J. H.

    1999-01-01

    The permeation resistance of chlorinated polyethylene (CPE) used in chemical protective clothing against the aerospace fuels hydrazine, monomethylhydrazine (MMH), and uns-dimethylhydrazine (UDMH) was determined by measuring breakthrough times and time-averaged vapor transmission rates using an ASTM F 739 permeation cell. Two exposure scenarios were simulated: a 2 hour (h) fuel vapor exposure, and a liquid fuel "splash" followed by a 2 h vapor exposure. To simulate internal suit pressure during operation, a positive differential pressure of 0.3 in. water (75 Pa) on the collection side of the permeation apparatus was used. Breakthrough was observed after exposure to liquid MMH, and to vapor and liquid UDMH. No breakthrough was observed after exposure to vapor and liquid hydrazine, or vapor MMH. A model was then used to calculate propellant concentrations inside a totally encapsulating chemical protective suit based on the ASTM permeation data obtained in the present study. Concentrations were calculated under conditions of fixed vapor transmission rate, variable breathing air flow rate, and variable splash exposure area. Calculations showed that the maximum allowable permeation rates of hydrazine fuels through CPE were of the order of 0.05 to 0.08 ng sq cm/min for encapsulating suits with low breathing air flow rates (of the order of 5 scfm or 140 L/min). Above these permeation rates, the 10 parts per billion (ppb) threshold limit value time - weighted average could be exceeded for chemical protective suits having a CPE torso. To evaluate suit performance at ppb level concentrations, use of a sensitive analytical method such as cation exchange high performance liquid chromatography with amperometric detection was found to be essential.

  3. A course-grained model for polyethylene glycol polymer

    SciTech Connect

    Nicholson, Don M [ORNL; Wang, Qifei [ORNL; Keffer, David J [ORNL

    2011-01-01

    A coarse-grained (CG) model of polyethylene glycol (PEG) was developed and implemented in CG molecular dynamics (MD) simulations of PEG chains with degree of polymerization (DP) 20 and 40. In the model, two repeat units of PEG are grouped as one CG bead. Atomistic MD simulation of PEG chains with DP = 20 was first conducted to obtain the bonded structural probability distribution functions (PDFs) and nonbonded pair correlation function (PCF) of the CG beads. The bonded CG potentials are obtained by simple inversion of the corresponding PDFs. The CG nonbonded potential is parameterized to the PCF using both an inversion procedure based on the Ornstein-Zernike equation with the Percus-Yevick approximation (OZPY{sup -1}) and a combination of OZPY{sup -1} with the iterative Boltzmann inversion (IBI) method (OZPY{sup -1}+IBI). As a simple one step method, the OZPY{sup -1} method possesses an advantage in computational efficiency. Using the potential from OZPY{sup -1} as an initial guess, the IBI method shows fast convergence. The coarse-grained molecular dynamics (CGMD) simulations of PEG chains with DP = 20 using potentials from both methods satisfactorily reproduce the structural properties from atomistic MD simulation of the same systems. The OZPY{sup -1}+IBI method yields better agreement than the OZPY{sup -1} method alone. The new CG model and CG potentials from OZPY{sup -1}+IBI method was further tested through CGMD simulation of PEG with DP = 40 system. No significant changes are observed in the comparison of PCFs from CGMD simulations of PEG with DP = 20 and 40 systems indicating that the potential is independent of chain length.

  4. Drop-on-demand drop formation of polyethylene oxide solutions

    NASA Astrophysics Data System (ADS)

    Yan, Xuejia; Carr, Wallace W.; Dong, Hongming

    2011-10-01

    The dynamics of drop-on-demand (DOD) drop formation for solutions containing polyethylene oxide (PEO) have been studied experimentally. Using a piezoelectrical actuated inkjet printhead with the nozzle orifice diameter of 53 ?m, experiments were conducted for a series of PEO aqueous solutions with molecular weights ranging from 14 to 1000 kg/mol, polydispersity from 1.02 to 2.5, and concentrations from 0.005 to 10 wt. %. The addition of a small amount of PEO can have a significant effect on the DOD drop formation process, increasing breakup time, decreasing primary drop speed, and decreasing the number of satellite drops in some cases. The effects depend on both molecular weight and concentration. At lower molecular weights (14 and 35 kg/mol), the effect of PEO over the dilute solution regime is insignificant even at concentrations large enough that the solution does not fall in the dilute regime. As PEO molecular weight increased, the effects became significant. For monodispersed PEO solutions, breakup time and primary drop speed closely correlated with effective relaxation time but not for polydispersed PEO. Effective relaxation time depended greatly on molecular weight distribution. Viscosity-average molecular weight, used in calculating effective relaxation time for polydispersed PEO solutions, did not adequately account for high molecular fractions in the molecular weight distribution of the polydispersed PEOs. A mixture rule was developed to calculate the effective relaxation times for aqueous solutions containing mixtures of monodispersed PEO, and breakup times and primary drop speeds correlated well with effective relaxation times. For our experiments, DOD drop formation was limited to Deborah number ? 23.

  5. Highly hydrated deformable polyethylene glycol-tethered lipid bilayers.

    PubMed

    Hertrich, Samira; Stetter, Frank; Rühm, Adrian; Hugel, Thorsten; Nickel, Bert

    2014-08-12

    The realization of a solid-supported lipid bilayer acting as a workbench for the study of membrane processes is a difficult task. For robustness, the bilayer has to be tethered to the substrate. At the same time, diffusion of the lipids and plastic deformations of the membrane should not be obstructed. Furthermore, a highly hydrated surrounding is mandatory. Here, we show that grafting of a polyethylene glycol-lipid construct (PEG2000-DSPE) to a silicon oxide surface via multiple-step silane chemistry and subsequent deposition of lipids by spin-coating result in a cushioned membrane that has the desired properties. Neutron and X-ray reflectometry measurements are combined to access thickness, density, and hydration of the bilayer and the PEG cushion. We observe a spacer of 55 Å thickness between lipid bilayer and silicon-oxide surface with a rather high hydration of up to 90 ± 3% water. While 11.5 ± 3% of the lipids are grafted to the surface, as determined from the neutron data, the diffusion constant of the lipids, as probed by diffusion of 0.5% Texas Red labeled lipids, remains rather large (D = 2.1 ± 0.1 ?m(2)/s), which is a reduction of only 12% compared to a supported lipid bilayer reference without immobilized lipids. Finally, AFM indentation confirms the plastic behavior of the membrane against deformation. We show that rupture of the bilayer does not occur before the deformation exceeds 40 Å. Altogether, the presented PEG-tethered lipid bilayer mimics the deformability of natural cell membranes much better than standard solid-supported lipid bilayers. PMID:25046694

  6. Robust Identification of Polyethylene Terephthalate (PET) Plastics through Bayesian Decision

    PubMed Central

    Zulkifley, Mohd Asyraf; Mustafa, Mohd Marzuki; Hussain, Aini; Mustapha, Aouache; Ramli, Suzaimah

    2014-01-01

    Recycling is one of the most efficient methods for environmental friendly waste management. Among municipal wastes, plastics are the most common material that can be easily recycled and polyethylene terephthalate (PET) is one of its major types. PET material is used in consumer goods packaging such as drinking bottles, toiletry containers, food packaging and many more. Usually, a recycling process is tailored to a specific material for optimal purification and decontamination to obtain high grade recyclable material. The quantity and quality of the sorting process are limited by the capacity of human workers that suffer from fatigue and boredom. Several automated sorting systems have been proposed in the literature that include using chemical, proximity and vision sensors. The main advantages of vision based sensors are its environmentally friendly approach, non-intrusive detection and capability of high throughput. However, the existing methods rely heavily on deterministic approaches that make them less accurate as the variations in PET plastic waste appearance are too high. We proposed a probabilistic approach of modeling the PET material by analyzing the reflection region and its surrounding. Three parameters are modeled by Gaussian and exponential distributions: color, size and distance of the reflection region. The final classification is made through a supervised training method of likelihood ratio test. The main novelty of the proposed method is the probabilistic approach in integrating various PET material signatures that are contaminated by stains under constant lighting changes. The system is evaluated by using four performance metrics: precision, recall, accuracy and error. Our system performed the best in all evaluation metrics compared to the benchmark methods. The system can be further improved by fusing all neighborhood information in decision making and by implementing the system in a graphics processing unit for faster processing speed. PMID:25485630

  7. Electrospun polyethylene oxide (PEO) nanofibers containing cyclodextrin inclusion complex.

    PubMed

    Uyar, Tamer; Hacaloglu, Jale; Besenbacher, Flemming

    2011-05-01

    In this study, we obtained functional electrospun nanofibers containing stable fragrance/flavor molecule facilitated by cyclodextrin inclusion complexation. Menthol was used as a model fragrance/flavor molecule and we have electrospun poly(ethylene oxide) (PEO) nanofibers containing cyclodextrin-menthol inclusion complexes (CD-menthol-IC). We used two different solvent systems; water and water:ethanol and three types of CDs; alpha-CD, beta-CD and gamma-CD in order to find the optimal performance for the stabilization of menthol at high temperatures. We observed that the solvent system used for electrospinning process and the types of CDs (alpha-CD, beta-CD and gamma-CD) are very important to obtain CD-menthol-IC which ultimately determines the durability and temperature stability of menthol in the PEO nanofibrous web. We found out that it is better to use water rather than the water:ethanol solvent system for the inclusion complexation and additionally beta-CD and gamma-CD are most favorable choices since they are able to form complexation with menthol in the water solvent system. Despite the high volatility nature of menthol, our results demonstrated that the stability and temperature release of menthol was sustained to a very high and a broad temperature range (100 degrees C-250 degrees C) for PEO nanowebs containing CD-menthol-IC whereas the PEO nanofibers without CD and without CD-menthol complex could not preserve menthol even during storage. In brief, the results are very encouraging and open up for a variety of new exciting possibilities for the development of multi-functional electrospun nanofibers containing cyclodextrin inclusion complexes. PMID:21780391

  8. Surface pre-treatment for barrier coatings on polyethylene terephthalate

    NASA Astrophysics Data System (ADS)

    Bahre, H.; Bahroun, K.; Behm, H.; Steves, S.; Awakowicz, P.; Böke, M.; Hopmann, Ch; Winter, J.

    2013-02-01

    Polymers have favourable properties such as light weight, flexibility and transparency. Consequently, this makes them suitable for food packaging, organic light-emitting diodes and flexible solar cells. Nonetheless, raw plastics do not possess sufficient barrier functionality against oxygen and water vapour, which is of paramount importance for most applications. A widespread solution is to deposit thin silicon oxide layers using plasma processes. However, silicon oxide layers do not always fulfil the requirements concerning adhesion and barrier performance when deposited on films. Thus, plasma pre-treatment is often necessary. To analyse the influence of a plasma-based pre-treatment on barrier performance, different plasma pre-treatments on three reactor setups were applied to a very smooth polyethylene terephthalate film before depositing a silicon oxide barrier layer. In this paper, the influence of oxygen and argon plasma pre-treatments towards the barrier performance is discussed examining the chemical and topological change of the film. It was observed that a short one-to-ten-second plasma treatment can reduce the oxygen transmission rate by a factor of five. The surface chemistry and the surface topography change significantly for these short treatment times, leading to an increased surface energy. The surface roughness rises slowly due to the development of small spots in the nanometre range. For very long treatment times, surface roughness of the order of the barrier layer's thickness results in a complete loss of barrier properties. During plasma pre-treatment, the trade-off between surface activation and roughening of the surface has to be carefully considered.

  9. Alteration of electroosmotic volume flow through skin by polyethylene glycols.

    PubMed

    Lee, Seung Yeon; Oh, Seaung Youl

    2014-10-21

    We have studied the effect of polyethylene glycols (PEGs) on the iontophoretic flux of acetaminophen (AAP) using conventional in vitro iontophoresis methodology. A series of PEGs with average molecular weight (MW) ranging from about 100 to 1,500 was studied. The results were analyzed to explain how PEGs affect the electroosmosis and flux through skin. As a marker molecule for the direction and magnitude of electroosmotic volume flow (EVF), AAP was used. PEG decreased both anodal and cathodal AAP flux markedly. The magnitude of this decrease in flux increased as the MW and the concentration of PEG increased. From the Helmholtz-Smoluchowski equation, it was expected that the increase in viscosity and the decrease in dielectric constant are thought to be the main reason for the decrease in EVF and the flux. The large increase in solubility of AAP in PEG solution may also play an important role, because this increase lowers the partition of AAP into the stratum corneum. When 30 % diethylene glycol solution was used, the magnitude of EVF was estimated to be about 1.5 ?l/cm(2) h, and it decreased as the MW of the PEG increased. These results and discussions clearly suggest that the incorporation of organic solubilizers and penetration enhancers into the iontophoretic formulation should be carefully decided after a thorough understanding of their effect on flux. Overall, these results provide further mechanistic insights into the role of electroosmosis in flux through skin, and how they can be modulated by PEG and their MW. PMID:25331332

  10. SANS Study of Highly Resilient Poly(ethylene glycol) Hydrogels

    PubMed Central

    Saffer, Erika M.; Lackey, Melissa A.; Griffin, David M.; Kishore, Suhasini; Tew, Gregory N.; Bhatia, Surita R.

    2014-01-01

    Polymer networks are critically important for numerous applications including soft biomaterials, adhesives, coatings, elastomers, and gel-based materials for energy storage. One long-standing challenge these materials present lies in understanding the role of network defects, such as dangling ends and loops, developed during cross-linking. These defects can negatively impact the physical, mechanical, and transport properties of the gel. Here we report chemically cross-linked poly(ethylene glycol) (PEG) gels formed through a unique cross-linking scheme designed to minimize defects in the network. The highly resilient mechanical properties of these systems (discussed in a previous publication1), suggests that this cross-linking technique yields more homogeneous network structures. Four series of gels were formed based on chains of 35,000 g/mol, (35K), 12,000 g/mol (12K) g/mol, 8,000 g/mol (8K) and 4,000 g/mol (4K) PEG. Gels were synthesized at five initial polymer concentrations ranging from 0.077 g/mL to 0.50 g/mL. Small-angle neutron scattering (SANS) was utilized to investigate the network structures of gels in both D2O and d-DMF. SANS results show the resulting network structure is dependent on PEG length, transitioning from a more homogeneous network structure at high molecular weight PEG to a two phase structure at the lowest molecular weight PEG. Further investigation of the transport properties inherent to these systems, such as diffusion, will aid to further confirm the network structures. PMID:24652367

  11. SANS study of highly resilient poly(ethylene glycol) hydrogels.

    PubMed

    Saffer, Erika M; Lackey, Melissa A; Griffin, David M; Kishore, Suhasini; Tew, Gregory N; Bhatia, Surita R

    2014-03-28

    Polymer networks are critically important for numerous applications including soft biomaterials, adhesives, coatings, elastomers, and gel-based materials for energy storage. One long-standing challenge these materials present lies in understanding the role of network defects, such as dangling ends and loops, developed during cross-linking. These defects can negatively impact the physical, mechanical, and transport properties of the gel. Here we report chemically cross-linked poly(ethylene glycol) (PEG) gels formed through a unique cross-linking scheme designed to minimize defects in the network. The highly resilient mechanical properties of these systems (discussed in a previous publication) [J. Cui, M. A. Lackey, A. E. Madkour, E. M. Saffer, D. M. Griffin, S. R. Bhatia, A. J. Crosby and G. N. Tew, Biomacromolecules, 2012, 13, 584-588], suggests that this cross-linking technique yields more homogeneous network structures. Four series of gels were formed based on chains of 35,000 g mol(-1), (35k), 12,000 g mol(-1) (12k) g mol(-1), 8000 g mol(-1) (8k) and 4000 g mol(-1) (4k) PEG. Gels were synthesized at five initial polymer concentrations ranging from 0.077 g mL(-1) to 0.50 g mL(-1). Small-angle neutron scattering (SANS) was utilized to investigate the network structures of gels in both D2O and d-DMF. SANS results show the resulting network structure is dependent on PEG length, transitioning from a more homogeneous network structure at high molecular weight PEG to a two phase structure at the lowest molecular weight PEG. Further investigation of the transport properties inherent to these systems, such as diffusion, will aid to further confirm the network structures. PMID:24652367

  12. Polyethylene recycling: Waste policy scenario analysis for the EU-27.

    PubMed

    Andreoni, Valeria; Saveyn, Hans G M; Eder, Peter

    2015-08-01

    This paper quantifies the main impacts that the adoption of the best recycling practices together with a reduction in the consumption of single-use plastic bags and the adoption of a kerbside collection system could have on the 27 Member States of the EU. The main consequences in terms of employment, waste management costs, emissions and energy use have been quantified for two scenarios of polyethylene (PE) waste production and recycling. That is to say, a "business as usual scenario", where the 2012 performances of PE waste production and recycling are extrapolated to 2020, is compared to a "best practice scenario", where the best available recycling practices are modelled together with the possible adoption of the amended Packaging and Packaging Waste Directive related to the consumption of single-use plastic bags and the implementation of a kerbside collection system. The main results show that socio-economic and environmental benefits can be generated across the EU by the implementation of the best practice scenario. In particular, estimations show a possible reduction of 4.4 million tonnes of non-recycled PE waste, together with a reduction of around €90 million in waste management costs in 2020 for the best practice scenario versus the business as usual scenario. An additional 35,622 jobs are also expected to be created. In environmental terms, the quantity of CO2 equivalent emissions could be reduced by around 1.46 million tonnes and the net energy requirements are expected to increase by 16.5 million GJ as a consequence of the reduction in the energy produced from waste. The main analysis provided in this paper, together with the data and the model presented, can be useful to identify the possible costs and benefits that the implementation of PE waste policies and Directives could generate for the EU. PMID:25976302

  13. Quantitation of employee exposure to emission products generated by commercial-scale processing of polyethylene.

    PubMed

    Tikuisis, T; Phibbs, M R; Sonnenberg, K L

    1995-08-01

    Although considerable research has been performed on the thermal degradation products of polyethylene, no data that can be compared to occupational exposure limits have been reported on the exposure of workers in commercial polyethylene extrusion operations. In this study, the actual airborne concentrations of previously identified analytes were measured during the commercial-scale processing of polyethylene resins. Nine polyethylene resins, spanning LDPE, LLDPE, and HDPE product slates were processed under commercial-scale conditions appropriate to their application: blown film, extrusion coating, blow molding, pipe extrusion, and rotational molding. Air samples were taken from operator breathing zones and of representative workplace air and contained air (inside film bubbles and molded parts) using recognized occupational health and safety protocols. The compounds selected for monitoring consisted of aldehydes (formaldehyde, acetaldehyde, acrolein, butyraldehyde, crotonaldehyde, and benzaldehyde), aromatics (benzene, toluene, xylenes, and styrene), formic and acetic acids, furan and tetrahydrofuran, and acetone. Airborne particulates also were measured. Of the 450 concentration measured from workplace air and operator breathing zones, 440 were below detection limits. Nine of the remaining ten concentrations were < 10% of the established exposure limits, while one particulate measurement was < 50% of the established exposure limit. As well, 180 contained-air samples were taken. Off-gases trapped inside film bubbles and molded parts accumulated to concentrations above those measured in the ambient air. It was concluded that polyethylene extrusion presents minimal inhalation hazards in a moderately ventilated environment. PMID:7653436

  14. Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings.

    PubMed

    Duong, Tu Van; Van Humbeeck, Jan; Van den Mooter, Guy

    2015-07-01

    The reproducibility and consistency of physicochemical properties and pharmaceutical performance are major concerns during preparation of solid dispersions. The crystallization kinetics of drug/polyethylene glycol solid dispersions, an important factor that is governed by the properties of both drug and polymer has not been adequately explored, especially in systems containing high drug loadings. In this paper, by using standard and modulated differential scanning calorimetry and X-ray powder diffraction, we describe the influence of drug loading on crystallization behavior of dispersions made up of indomethacin and polyethylene glycol 6000. Higher drug loading increases the amorphicity of the polymer and inhibits the crystallization of PEG. At 52% drug loading, polyethylene glycol was completely transformed to the amorphous state. To the best of our knowledge, this is the first detailed investigation of the solubilization effect of a low molecular weight drug on a semicrystalline polymer in their dispersions. In mixtures containing up to 55% indomethacin, the dispersions exhibited distinct glass transition events resulting from amorphous-amorphous phase separation which generates polymer-rich and drug-rich domains upon the solidification of supercooled polyethylene glycol, whereas samples containing at least 60% drug showed a single amorphous phase during the period in which crystallization normally occurs. The current study demonstrates a wide range in physicochemical properties of drug/polyethylene glycol solid dispersions as a result of the complex nature in crystallization of this system, which should be taken into account during preparation and storage. PMID:26056715

  15. OBT analysis method using polyethylene beads for limited quantities of animal tissue.

    PubMed

    Kim, S B; Stuart, M

    2015-08-01

    This study presents a polyethylene beads method for OBT determination in animal tissues and animal products for cases where the amount of water recovered by combustion is limited by sample size or quantity. In the method, the amount of water recovered after combustion is enhanced by adding tritium-free polyethylene beads to the sample prior to combustion in an oxygen bomb. The method reduces process time by allowing the combustion water to be easily collected with a pipette. Sufficient water recovery was achieved using the polyethylene beads method when 2 g of dry animal tissue or animal product were combusted with 2 g of polyethylene beads. Correction factors, which account for the dilution due to the combustion water of the beads, are provided for beef, chicken, pork, fish and clams, as well as egg, milk and cheese. The method was tested by comparing its OBT results with those of the conventional method using animal samples collected on the Chalk River Laboratories (CRL) site. The results determined that the polyethylene beads method added no more than 25% uncertainty when appropriate correction factors are used. PMID:25913056

  16. Oxidation and Wear of 100-Mrad Cross-linked Polyethylene Shelf-aged for 30 Years

    PubMed Central

    Oonishi, Hironobu; Kim, Sok Chol; Oonishi, Hiroyuki; Kyomoto, Masayuki

    2008-01-01

    Some previous studies suggest that aging influences wear and oxidatively degraded nonsterilized ultra-high-molecular-weight polyethylene (UHMWPE) exhibits decreased wear resistance. We therefore asked whether shelf-aging storage conditions influenced degradation and wear resistance of gamma-irradiated UHMWPE. We examined oxidation and wear of 100-Mrad gamma-irradiated UHMWPE (100-Mrad polyethylene) cups shelf-aged for 30 years without (n = 2) or with (n = 2) packages. The oxidation index of the unpackaged 100-Mrad polyethylene surface (4) was higher than that of the packaged one (2.7). The packaged 100-Mrad polyethylene cup exhibited a high wear resistance with a steady wear rate of 0.5 mg/106 cycles. In contrast, the unpackaged 100-Mrad polyethylene exhibited an extremely high initial wear rate of 187.9 mg/106 cycles over the first 0.25 × 106 cycles with a subsequently reduced wear rate of 5 mg/106 cycles after 5 × 106 cycles. Packaging over long periods inhibits surface oxidation and maintains the wear resistance of gamma-irradiated UHMWPE cups. PMID:18196416

  17. Solid-phase polyethylene glycol conjugation using hydrophobic interaction chromatography.

    PubMed

    Niu, Jianlou; Zhu, Yanlin; Xie, Yaoyao; Song, Lintao; Shi, Lu; Lan, Junjie; Liu, Bailin; Li, Xiaokun; Huang, Zhifeng

    2014-01-31

    PEGylation is a widely applied approach to improve the pharmacokinetic and pharmacodynamic properties of protein therapeutics. The current solution-phase PEGylation protocols often suffer from poor yield of homogeneously PEGylated bioactive products and hence fall short of being commercially attractive. To improve upon these techniques, here we developed a novel, solid-phase PEGylation methodology using a hydrophobic interaction chromatography (HIC) resin. Two variations of the HIC-based PEGylation are described that are tailored towards conjugation of proteins with hydrophobicity index above (lysozyme) and below (fibroblast growth factor 1, FGF-1) that of the mPEG-butyraldehyde (mPEG) chain used. In the case of lysozyme, the protein was first immobilized on the HIC, and the HIC-bound protein was then conjugated by passing over the column. In the case of FGF-1, the mPEG solution was first immobilized on the HIC, and the FGF-1 solution was then passed through the column. Circular dichroism (CD) spectroscopy demonstrated HIC-based PEGylation almost retained the secondary structures of proteins. Bioactivity assay showed that the recovery of activity of HIC-based PEGylated rhFGF-1 (i.e. 92%) was higher than that of liquid-phase PEGylated rhFGF-1 (i.e. 61%), while HIC-based PEGylated lysozyme showed the same activity recovery (i.e. 7%) as the liquid-phase PEGylated form. For specific proteins, the HIC-based solid-phase PEGylation maybe offer a more promising alternative than the current PEGylation methods and is expected to have a major impact in the area of protein-based therapeutics. PMID:24411087

  18. Introduction to current and future protein therapeutics: A protein engineering perspective

    SciTech Connect

    Carter, Paul J., E-mail: pjc@gene.com

    2011-05-15

    Protein therapeutics and its enabling sister discipline, protein engineering, have emerged since the early 1980s. The first protein therapeutics were recombinant versions of natural proteins. Proteins purposefully modified to increase their clinical potential soon followed with enhancements derived from protein or glycoengineering, Fc fusion or conjugation to polyethylene glycol. Antibody-based drugs subsequently arose as the largest and fastest growing class of protein therapeutics. The rationale for developing better protein therapeutics with enhanced efficacy, greater safety, reduced immunogenicity or improved delivery comes from the convergence of clinical, scientific, technological and commercial drivers that have identified unmet needs and provided strategies to address them. Future protein drugs seem likely to be more extensively engineered to improve their performance, e.g., antibodies and Fc fusion proteins with enhanced effector functions or extended half-life. Two old concepts for improving antibodies, namely antibody-drug conjugates and bispecific antibodies, have advanced to the cusp of clinical success. As for newer protein therapeutic platform technologies, several engineered protein scaffolds are in early clinical development and offer differences and some potential advantages over antibodies.

  19. Controlled activation of protein rotational dynamics using smart hydrogel tethering.

    PubMed

    Beech, Brenda M; Xiong, Yijia; Boschek, Curt B; Baird, Cheryl L; Bigelow, Diana J; McAteer, Kathleen; Squier, Thomas C

    2014-09-24

    Stimulus-responsive hydrogel materials that stabilize and control protein dynamics have the potential to enable a range of applications that take advantage of the inherent specificity and catalytic efficiencies of proteins. Here we describe the modular construction of a hydrogel using an engineered calmodulin (CaM) within a poly(ethylene glycol) (PEG) matrix that involves the reversible tethering of proteins through an engineered CaM-binding sequence. For these measurements, maltose binding protein (MBP) was isotopically labeled with (13)C and (15)N, permitting dynamic structural measurements using TROSY-HSQC NMR spectroscopy. The protein dynamics is suppressed upon initial formation of hydrogels, with a concomitant increase in protein stability. Relaxation of the hydrogel matrix following transient heating results in enhanced protein dynamics and resolution of substrate-induced large-amplitude domain rearrangements. PMID:25190510

  20. FUNCTIONALIZED PEG-BRUSH LAYER FOR CONTROLLING PROTEIN AND CELL INTERACTIONS

    Microsoft Academic Search

    H. Otsuka; T. Satomi; J. H. Itadani; Y. Nagasaki; T. Okano; Y. Horiike; K. Kataoka

    INTRODUCTION: A poly(ethylene glycol) (PEG) coating has most widely been used to minimize non- specific fouling of the device surface with biocomponents, including plasma proteins. Although the PEG coating can be performed by a variety of methods, most of the PEG- coated surfaces so far reported possess no reactive group on the PEG chain end. To provide the further functionality