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1

Poly(ethylene glycol)-modified phospholipids prevent aggregation during covalent conjugation of proteins to liposomes.  

PubMed

Liposome aggregation is a major problem associated with the covalent attachment of proteins to liposomes. This report describes a procedure for coupling proteins to liposomes that results in little or no change in liposome size. This is achieved by incorporating appropriate levels of poly(ethylene glycol)-modified lipids into the liposomes. The studies employed thiolated avidin-D coupled to liposomes containing the thio-reactive lipid N-(4-(p-maleimidophenyl)butyryl)dipalmitoyl phosphatidylethanolamine (1 mol % of total lipid) and various amounts of MePEG-S-POPE (monomethoxypoly(ethylene glycol) linked to phosphatidylethanolamine via a succinate linkage). The influence of PEG chain length and density was also assessed. The presence of PEG on the surface of liposomes is shown to provide an effective method of inhibiting aggregation and the corresponding increase in liposome size during the covalent coupling of avidin-D. A balance between the size of the PEG used and the amount of PEG-lipid incorporated into the liposome had to be achieved in order to maintain efficient coupling. Optimal coupling efficiencies in combination with minimal aggregation effects were achieved using 2 mol % MePEG2000-S-POPE (PEG of 2000 MW) or 0.8 mol % MePEG5000-S-POPE (PEG of 5000 MW). At these levels, the presence of PEG did not affect the biotin binding activity of the covalently attached avidin. The ability of the resulting liposomes to specifically target to biotinylated cells is demonstrated. PMID:7599262

Harasym, T O; Tardi, P; Longman, S A; Ansell, S M; Bally, M B; Cullis, P R; Choi, L S

1995-01-01

2

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

PubMed Central

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

Farrell, Megan; Beaudoin, Stephen

2010-01-01

3

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

PubMed

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

Farrell, Megan; Beaudoin, Stephen

2010-12-01

4

Poly(ethylene glycol)-Modified Ligninase Enhances Pentachlorophenol  

E-print Network

Poly(ethylene glycol)-Modified Ligninase Enhances Pentachlorophenol Biodegradation in Water and stability for the biodegradation of pentachlorophenol (PCP) in the presence of acetonitrile (MeCN), a water: 290­297, 1999.* Keywords: pentachlorophenol; ligninase; poly(ethylene glycol); organic solvent

Wang, Ping

5

Cell separation by immunoaffinity partitioning with polyethylene glycol-modified Protein A in aqueous polymer two-phase systems  

NASA Technical Reports Server (NTRS)

Previous work has shown that polyethylene glycol (PEG)-bound antibodies can be used as affinity ligands in PEG-dextran two-phase systems to provide selective partitioning of cells to the PEG-rich phase. In the present work it is shown that immunoaffinity partitioning can be simplified by use of PEG-modified Protein A which complexes with unmodified antibody and cells and shifts their partitioning into the PEG-rich phase, thus eliminating the need to prepare a PEG-modified antibody for each cell type. In addition, the paper provides a more rigorous test of the original technique with PEG-bound antibodies by showing that it is effective at shifting the partitioning of either cell type of a mixture of two cell populations.

Karr, Laurel J.; Van Alstine, James M.; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

1988-01-01

6

Structure of poly(ethylene glycol)-modified horseradish peroxidase in organic solvents: infrared amide I spectral changes upon protein dehydration are largely caused by protein structural changes and not by water removal per se.  

PubMed Central

Fourier transform infrared (FTIR) spectroscopy has emerged as a powerful tool to guide the development of stable lyophilized protein formulations by providing information on the structure of proteins in amorphous solids. The underlying assumption is that IR spectral changes in the amide I and III region upon protein dehydration are caused by protein structural changes. However, it has been claimed that amide I IR spectral changes could be the result of water removal per se. Here, we investigated whether such claims hold true. The structure of horseradish peroxidase (HRP) and poly(ethylene glycol)-modified HRP (HRP-PEG) has been investigated under various conditions (in aqueous solution, the amorphous dehydrated state, and dissolved/suspended in toluene and benzene) by UV-visible (UV-Vis), FTIR, and resonance Raman spectroscopy. The resonance Raman and UV-Vis spectra of dehydrated HRP-PEG dissolved in neat toluene or benzene were very similar to that of HRP in aqueous buffer, and thus the heme environment (heme iron spin, coordination, and redox state) was essentially the same under both conditions. Therefore, the three-dimensional structure of HRP-PEG dissolved in benzene and toluene was similar to that in aqueous solution. The amide I IR spectra of HRP-PEG in aqueous buffer and of dehydrated HRP-PEG dissolved in neat benzene and toluene were also very similar, and the secondary structure compositions (percentages of alpha-helices and beta-sheets) were within the standard error the same. These results are irreconcilable with recent claims that water removal per se could cause substantial amide I IR spectral changes (M. van de Weert, P.I. Haris, W.E. Hennink, and D.J. Crommelin. 2001. Anal. Biochem. 297:160-169). On the contrary, amide I IR spectral changes upon protein dehydration are caused by perturbations in the secondary structure. PMID:12496131

Al-Azzam, Wasfi; Pastrana, Emil A; Ferrer, Yancy; Huang, Qing; Schweitzer-Stenner, Reinhard; Griebenow, Kai

2002-01-01

7

Transport and functional behaviour of poly(ethylene glycol)-modified nanoporous alumina membranes  

Microsoft Academic Search

The development of hybrid organic–inorganic membranes with a low propensity for protein adsorption and highly uniform nanometre size pores is described. Poly(ethylene glycol) (PEG) monolayers were grafted to nanoporous alumina membranes using covalent silane and physical adsorption poly(ethyleneimine) (PEI) immobilization chemistries. X-ray photoelectron spectroscopy (XPS) and electron microscopy were used to investigate the chemical and physical surface properties of the

Sang Won Lee; Hao Shang; Richard T Haasch; Vania Petrova; Gil U Lee

2005-01-01

8

Poly(Ethylene Glycol)-Modified Thiolated Gelatin Nanoparticles for Glutathione-Responsive Intracellular DNA Delivery  

PubMed Central

Poly(ethylene glycol) (PEG) modified thiolated gelatin nanoparticles (PEG-SHGel) were developed as a long-circulating passively-targeted delivery system that respond to intracellular glutathione concentrations to enhance DNA delivery and transfection. Reporter plasmid expressing enhanced green fluorescent protein (EGFP-N1) was encapsulated in the nanoparticles. DNA-containing gelatin (Gel) and thiolated gelatin (SHGel) nanoparticles were found to have a size range of 220–250 nm, whereas surface modification with PEG resulted in particles with slightly larger size range of 310–350 nm. PEG modification was confirmed by electron spectroscopy for chemical analysis (ESCA), where an increase in the ether peak intensities of the C1s spectra corresponds to the surface presence of ethylene oxide residues. In addition, the PEG-SHGel nanoparticles released encapsulate plasmid DNA in response to varying concentrations of glutathione (0 – 5.0 mM GSH in phosphate buffered saline). The stability of the encapsulated DNA was confirmed by agarose gel electrophoresis. Lastly, from the qualitative and quantitative results of in vitro transfection studies in murine fibroblast cells (NIH-3T3), PEG-Gel and PEG-SHGel nanoparticles afforded the highest transfection efficiency of the reporter plasmid. The results of these studies show that PEG-modified thiolated gelatin nanoparticles could serve as a very efficient nanoparticulate vector for systemic DNA delivery to solid tumors where the cells are known to have significantly higher intracellular glutathione concentrations. PMID:17379167

Kommareddy, Sushma; Amiji, Mansoor

2007-01-01

9

Poly(ethylene glycol)-modified thiolated gelatin nanoparticles for glutathione-responsive intracellular DNA delivery.  

PubMed

Poly(ethylene glycol) (PEG)-modified thiolated gelatin (PEG-SHGel) anoparticles were developed as a long-circulating passively targeted delivery system that responds to intracellular glutathione concentrations to enhance DNA delivery and transfection. Reporter plasmid expressing enhanced green fluorescent protein (EGFP-N1) was encapsulated in the nanoparticles. DNA-containing gelatin (Gel) and thiolated gelatin (SHGel) nanoparticles were found to have a size range of 220 to 250 nm, whereas surface modification with PEG resulted in particles with a slightly larger size range of 310 to 350 nm. PEG modification was confirmed by electron spectroscopy for chemical analysis (ESCA), where an increase in the ether peak intensities of the C1s spectra corresponds to the surface presence of ethylene oxide residues. In addition, the PEG-SHGel nanoparticles released encapsulate plasmid DNA in response to varying concentrations of glutathione (up to 5.0 mM GSH in phosphate-buffered saline, or PBS). The stability of the encapsulated DNA was confirmed by agarose gel electrophoresis. Finally, from the qualitative and quantitative results of in vitro transfection studies in murine fibroblast cells (NIH3T3), PEG-Gel and PEG-SHGel nanoparticles afforded the highest transfection efficiency of the reporter plasmid. The results of these studies show that PEG-modified thiolated gelatin nanoparticles could serve as a very efficient nanoparticulate vector for systemic DNA delivery to solid tumors where the cells are known to have significantly higher intracellular GSH concentrations. PMID:17379167

Kommareddy, Sushma; Amiji, Mansoor

2007-03-01

10

Poly(ethylene glycol)-modified ligninase enhances pentachlorophenol biodegradation in water-solvent mixtures  

SciTech Connect

Polychlorinated hydrocarbons are prevalent environmental contaminants whose rates of biodegradation are limited by their minimal solubilities in aqueous solutions where the biological reactions take place. In this study, ligninase (LiP) from Phanerochaete chrysosporium was modified by poly(ethylene glycol) to enhance its activity and stability for the biodegradation of pentachlorophenol (PCP) in the presence of acetonitrile (MeCN), a water-miscible solvent. The modified enzyme retained 100% of its activity in aqueous solutions and showed enhanced tolerance against the organic solvent. The activity of the modified enzyme was found to be over twice that of the native enzyme in the presence of 10% (v/v) MeCN. The solubility of PCP was enhanced significantly by the addition of MeCN to aqueous solutions, such that it was over 10-fold more soluble in the presence of 15% (v/v) MeCN than in pure aqueous buffer solution. Capitalizing on the enhanced substrate solubility and the increased activity of the modified enzyme, the catalytic efficiency of the modified LiP in solutions containing 15% MeCN was over 11-fold higher than that of the native enzyme in buffer solutions in unoptimized reactor systems. Continued research both in the use of organic solvents to increase the availability of recalcitrant contaminants and in the modification of enzymes to enhance their activity and stability in such solvents promises to dramatically affect their ability to remediate contaminated sites.

Wang, P.; Woodward, C.A.; Kaufman, E.N. (Oak Ridge National Lab., TN (United States). Chemical Technology Div.)

1999-08-05

11

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

PubMed

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

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

2014-04-10

12

Pharmacologic properties of polyethylene glycol-modified Bacillus thiaminolyticus thiaminase I enzyme.  

PubMed

We have previously shown that the bacterial enzyme thiaminase 1 has antitumor activity. In an attempt to make thiaminase I a more effective pharmaceutical agent, we have modified it by adding polyethylene glycol (PEG) chains of various lengths. We were surprised to find that 5k-PEGylation eliminated thiaminase cytotoxic activity in all cell lines tested. Both native thiaminase and 5k-PEGylated thiaminase efficiently depleted thiamine from cell culture medium, and both could use intracellular phosphorylated thiamine as substrates. However, native enzyme more effectively depleted thiamine and thiamine diphosphate in RS4 leukemia cell cytosol, and native thiaminase depressed cellular respiration, whereas PEGylated thiaminase did not. Despite the lack of in vitro cytotoxicity, PEGylation markedly increased the in vivo toxicity of the enzyme. Pharmacokinetic studies revealed that the half-life of native thiaminase was 1.5 h compared with 34.4 h for the 5k-PEGylated enzyme. Serum thiamine levels were depleted by both native and 5k-PEGylated enzyme. Despite superior pharmacokinetics, 5k-PEGylated thiaminase showed no antitumor effect against an RS4 leukemia xenograft, in contrast to native thiaminase, which showed antitumor activity. PEGylation of thiaminase I has demonstrated that depression of mitochondrial function contributes, at least in part, to its anticancer activity. PEGylation also enhances plasma retention time, which increased its vivo toxicity and decreased its activity against a leukemia xenograft, the opposite of the desired effects. These studies suggest that the mechanism of anticancer cytotoxicity of thiaminase requires acute depression of cellular respiration, whereas systemic toxicity is related to the duration of extracellular thiamine depletion. PMID:22431205

Liu, Shuqian; Bae, Younsoo; Leggas, Markos; Daily, Abigail; Bhatnagar, Saloni; Miriyala, Sumitra; St Clair, Daret K; Moscow, Jeffrey A

2012-06-01

13

TUMOR-TARGETED GENE DELIVERY USING POLY(ETHYLENE GLYCOL)-MODIFIED GELATIN NANOPARTICLES: IN VITRO AND IN VIVO STUDIES  

PubMed Central

Purpose To develop safe and effective systemically-administered non-viral gene therapy vectors for solid tumors, DNA-containing poly(ethylene glycol)-modified (PEGylated) gelatin nanoparticles were fabricated and evaluated in vitro and in vivo. Experimental Methods Reporter plasmid DNA encoding for ?-galactosidase (pCMV-?) was encapsulated in gelatin and PEGylated gelatin nanoparticles using a water-ethanol solvent displacement method under controlled pH and temperature. Lewis lung carcinoma (LLC) cells in culture were transfected with the pCMV-? in the control and nanoparticle formulations. Periodically, the expression of ?-galactosidase in the cells was measured quantitatively using an enzymatic assay for the conversion of o-nitrophenyl-?-D-galactopyranoside (ONPG) to o-nitrophenol (ONP). Qualitative expression of ?-galactosidase in LLC cells was observed by staining with 5-bromo-4-chloro-3-indolyl-?-D-galactopyranoside (X-gal®). Additionally, the plasmid DNA-encapsulated gelatin and PEGylated gelatin nanoparticles were administered intravenously (i.v.) and intratumorally (i.t.) to LLC-bearing female C57BL/6J mice. At various time points post-administration, the animals were sacrificed and transgene expression in the tumor and liver was determined quantitatively by the ONPG to ONP enzymatic conversion assay and qualitatively by X-gal staining. Results Almost 100% of the pCMV-? was encapsulated in gelatin and PEGylated gelatin nanoparticles (mean diameter 200 nm) at 0.5% (w/w) concentration. PEGylated gelatin nanoparticles efficiently transfected the LLC cells and the ?-galactosidase expression, as measured by the ONPG to ONP enzymatic conversion assay at 420 nm absorbance, increased starting from 12 hours until 96 hours post-transfection. The efficient expression of LLC cells was also evident by the X-gal staining method that shows blue color formation. The in vivo studies showed significant expression of ?-galactosidase in the tumor following administration of DNA-containing PEGylated gelatin nanoparticles to LLC-bearing mice by both i.v. and i.t. routes. Following i.v. administration of pCMV-? in PEGylated gelatin nanoparticles, for instance, the absorbance at 420 nm per gram of tumor increased from 0.60 after 12 hours to 0.85 after 96 hours of transfection. After i.t. administration, the absorbance values increased from 0.90 after 12 hours to almost 1.4 after 96 hours. Conclusions The in vitro and in vivo results of this study clearly show that a long-circulating, biocompatible and biodegradable, DNA-encapsulating nanoparticulate system would be highly desirable for systemic delivery of genetic constructs to solid tumors. PMID:15948039

KAUL, GOLDIE; AMIJI, MANSOOR

2005-01-01

14

Polyethylene glycol-modified dendrimer-entrapped gold nanoparticles enhance CT imaging of blood pool in atherosclerotic mice  

PubMed Central

We report a new use of dendrimer-entrapped gold nanoparticles (Au DENPs) modified by polyethylene glycol (PEG) with good biocompatibility for in vitro and in vivo imaging of atherosclerotic mice by computed tomography (CT). In this study, Au DENPs were synthesized using poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5.NH2) modified by PEG monomethyl ether (G5.NH2-mPEG20) as templates. In vitro cytotoxicity and flow cytometry assays show that the formed PEGylated Au DENPs have good biocompatibility and are non-cytotoxic at the Au concentration up to 300 ?M. Silver staining and transmission electron microscopy (TEM) further confirm that the Au DENPs are able to be uptaken by macrophages and are located dominantly in the lysosomes of the cells. Importantly, the formed PEGylated Au DENPs are able to be used for CT imaging of murine macrophages in vitro and macrophages in atherosclerotic mice in vivo using apolipoprotein-E-gene-deficient mice as a model. These findings suggest that the formed PEGylated Au DENPs are a promising contrast agent for CT imaging of atherosclerosis. PMID:25288918

2014-01-01

15

Mixed polyethylene glycol-modified breviscapine-loaded solid lipid nanoparticles for improved brain bioavailability: preparation, characterization, and in vivo cerebral microdialysis evaluation in adult Sprague Dawley rats.  

PubMed

Breviscapine is used in the treatment of ischemic cerebrovascular diseases, but it has a low bioavailability in the brain due to its poor physicochemical properties and the activity of P-glycoprotein efflux pumps located at the blood-brain barrier. In the present study, breviscapine-loaded solid lipid nanoparticles (SLN) coated with polyethylene glycol (PEG) derivatives were formulated and evaluated for their ability to enhance brain bioavailability. The SLNs were either coated with polyethylene glycol (40) (PEG-40) stearate alone (Bre-GBSLN-PS) or a mixture of PEG-40 stearate and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-PEG2000 (DSPE-PEG2000) (Bre-GBSLN-PS-DSPE) and were characterized both in vitro and in vivo. The mean particle size, polydispersity index, and entrapment efficiency for Bre-GBSLN-PS and Bre-GBSLN-PS-DSPE were 21.60?±?0.10 and 22.60?±?0.70 nm, 0.27?±?0.01 and 0.26?±?0.04, and 46.89?±?0.73% and 47.62?±?1.86%, respectively. The brain pharmacokinetic parameters revealed that the brain bioavailability of breviscapine from the Bre-GBSLN-PS and Bre-GBSLN-PS-DSPE was significantly enhanced (p?

Liu, Zhidong; Okeke, Chukwunweike Ikechukwu; Zhang, Li; Zhao, Hainan; Li, Jiawei; Aggrey, Mike Okweesi; Li, Nan; Guo, Xiujun; Pang, Xiaochen; Fan, Lili; Guo, Lili

2014-04-01

16

21 CFR 177.1630 - Polyethylene phthalate polymers.  

Code of Federal Regulations, 2014 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT...acid with ethylene glycol, modified with one or more of the following...acid with ethylene glycol, modified with one or more of the following...food-contact surface of the modified polyethylene...

2014-04-01

17

Preparation and evaluation of poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith for protein analysis.  

PubMed

A poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith was prepared by UV-initiated polymerization. Methanol and ethyl ether were selected as porogens from a variety of organic solvents to achieve the desirable characteristics of the monolith. The preparation of the monolith could be achieved within 10 min. The monolith was macroscopically homogeneous, had low flow resistance, and did not swell or shrink significantly in tetrahydrofuran. Inverse size-exclusion data indicate that the monolith had a total porosity of 75.4% and an internal porosity of 9.1%. The monolith could be used for size-exclusion separation of peptides, although it could not separate proteins with molecular masses between 10 and 100 K due to its unique pore size distribution. It was found to resist adsorption of proteins in capillary liquid chromatography when using 100 mM phosphate buffer (pH 7.0) containing 0.5 M NaCl. Complete recovery of both acidic and basic proteins was achieved. The monolith can be used for applications in which inert materials are required for protein analysis. PMID:16038326

Gu, Binghe; Armenta, Jenny M; Lee, Milton L

2005-06-24

18

Why do polyethylene glycols behave as a stabilizer and a destabilizer of protein structure  

SciTech Connect

The ability of organic co-solvents to serve as stabilizer or destabilizer of proteins is the net result of a series of interactions between co-solvents and the native-denatured states of the protein. In an effort to test the applicability of thermodynamic principles governing protein stability, the effects of polyethylene glycols on the stability of bovine serum albumin and chymotrypsinogen were studied. Protein stability was monitored by exposing proteins to guanidine hydrochloride and urea. Results show that these proteins unfold in higher concentrations of denaturant in the presence of polyethylene glycols. These denaturation results are in direct contrast to that of thermal denaturation, which showed that polyethylene glycols destabilize proteins. Polyethylene glycols serve as a stabilizer of proteins towards chemical denaturation because the presence of denaturants has disrupted the hydrophobic interactions between the co-solvent and unfolded state of the protein, an interaction that probably is the dominant factor in thermal denaturation. Thus, the ability of the same co-solvent to serve as a stabilizer or destabilizer of proteins depends on the nature of interactions between co-solvent and protein states under specific environmental conditions.

Shilong Yuan; Lee, Lee, L.L.Y.; Tsang, A.; Lee, J.C. (Univ. of Texas, Galveston (United States))

1991-03-11

19

Preferential hydration and solubility of proteins in aqueous solutions of polyethylene glycol  

Microsoft Academic Search

This paper is focused on the local composition around a protein molecule in aqueous mixtures containing polyethylene glycol (PEG) and the solubility of proteins in water+PEG mixed solvents. Experimental data from literature regarding the preferential binding parameter were used to calculate the excesses (or deficits) of water and PEG in the vicinity of ?-lactoglobulin, bovine serum albumin, lysozyme, chymotrypsinogen and

Ivan L. Shulgin; Eli Ruckenstein

2006-01-01

20

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

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

Annunziata, Onofrio

21

Determination of six polyynes in Oplopanax horridus and Oplopanax elatus using polyethylene glycol modified reversed migration microemulsion electrokinetic chromatography.  

PubMed

A PEG-modified reversed migration MEEKC method was developed for simultaneous determination of six polyynes, including oplopandiol, falcarindiol, oplopandiol acetate, (11S, 16S, 9Z)-9,17-octadecadiene-12,14-diyne-1,11,16-triol,1-acetate, oplopantriol B, and oplopantriol A, in Oplopanax horridus and Oplopanax elatus. The running buffer containing 0.8% v/v ethyl acetate, 3.8% w/v SDS, 6.6% v/v n-butanol in 20 mM phosphate buffer (pH 2.5), followed by mixing with propan-2-ol at 30% v/v and PEG-1000 at 15% w/v, was applied in the analysis. The proposed method was successfully applied to determine the six polyynes in five samples of Oplopanax horridus and one of O. elatus. The result showed that the types and amounts of polyynes present were obviously different when comparing the two herbs. Besides, the developed PEG-modified reversed MEEKC method might be suitable for the analysis of hydrophobic analytes in herbal medicines. PMID:25070635

Yang, Zhong-mei; Zhao, Jing; Lao, Ka-meng; Chen, Xiao-jia; Leong, Fong; Wang, Chong-Zhi; Yuan, Chun-Su; Li, Shao-ping

2014-10-01

22

Efficient Clearance of Poly(ethylene glycol)Modified Immunoenzyme with Anti-PEG Monoclonal Antibody for Prodrug Cancer Therapy  

Microsoft Academic Search

The F(ab')2 fragment of the anti-TAG-72 antibody, B72.3, was covalently linked to Escherichia coli- derived ‚-glucuronidase that was modified with methoxypoly(ethylene glycol). The conjugate (B72.3- ‚G-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

Tian-Lu Cheng; Bing-Mae Chen; Ji-Wang Chern; Ming-Fang Wu; Steve R. Roffler

2000-01-01

23

Design and synthesis of polyethylene glycol-modified biphenylsulfonyl-thiophene-carboxamidine inhibitors of the complement component C1s.  

PubMed

Complement C1s protease inhibitors have potential utility in the treatment of diseases associated with activation of the classical complement pathway such as humorally mediated graft rejection, ischemia-reperfusion injury (IRI), vascular leak syndrome, and acute respiratory distress syndrome (ARDS). The utility of biphenylsulfonyl-thiophene-carboxamidine small-molecule C1s inhibitors are limited by their poor in vivo pharmacokinetic properties. Pegylation of a potent analog has provided compounds with good potency and good in vivo pharmacokinetic properties. PMID:22795627

Subasinghe, Nalin L; Khalil, Ehab; Travins, Jeremy M; Ali, Farah; Ballentine, Shelley K; Hufnagel, Heather R; Pan, Wenxi; Leonard, Kristi; Bone, Roger F; Soll, Richard M; Crysler, Carl S; Ninan, Nisha; Kirkpatrick, Jennifer; Kolpak, Michael X; Diloreto, Karen A; Eisennagel, Stephen H; Huebert, Norman D; Molloy, Christopher J; Tomczuk, Bruce E; Gaul, Michael D

2012-08-15

24

Interfacial Protein-Protein Associations  

PubMed Central

While traditional models of protein adsorption focus primarily on direct protein-surface interactions, recent findings suggest that protein-protein interactions may play a central role. Using high-throughput intermolecular resonance energy transfer (RET) tracking, we directly observed dynamic, protein-protein associations of bovine serum albumin on poly(ethylene glycol) modified surfaces. The associations were heterogeneous and reversible, and associating molecules resided on the surface for longer times. The appearance of three distinct RET states suggested a spatially heterogeneous surface – with areas of high protein density (i.e. strongly-interacting clusters) coexisting with mobile monomers. Distinct association states exhibited characteristic behavior, i.e. partial-RET (monomer-monomer) associations were shorter-lived than complete-RET (protein-cluster) associations. While the fractional surface area covered by regions with high protein density (i.e. clusters) increased with increasing concentration, the distribution of contact times between monomers and clusters was independent of solution concentration, suggesting that associations were a local phenomenon, and independent of the global surface coverage. PMID:24274729

Langdon, Blake B.; Kastantin, Mark; Walder, Robert; Schwartz, Daniel K.

2014-01-01

25

Interfacial protein-protein associations.  

PubMed

While traditional models of protein adsorption focus primarily on direct protein-surface interactions, recent findings suggest that protein-protein interactions may play a central role. Using high-throughput intermolecular resonance energy transfer (RET) tracking, we directly observed dynamic, protein-protein associations of bovine serum albumin on polyethylene glycol modified surfaces. The associations were heterogeneous and reversible, and associating molecules resided on the surface for longer times. The appearance of three distinct RET states suggested a spatially heterogeneous surface - with areas of high protein density (i.e., strongly interacting clusters) coexisting with mobile monomers. Distinct association states exhibited characteristic behavior, i.e., partial-RET (monomer-monomer) associations were shorter-lived than complete-RET (protein-cluster) associations. While the fractional surface area covered by regions with high protein density (i.e., clusters) increased with increasing concentration, the distribution of contact times between monomers and clusters was independent of solution concentration, suggesting that associations were a local phenomenon, and independent of the global surface coverage. PMID:24274729

Langdon, Blake B; Kastantin, Mark; Walder, Robert; Schwartz, Daniel K

2014-01-13

26

Recombinant Ganoderma lucidum immunomodulatory protein modified with polyethylene glycol.  

PubMed

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

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

2013-03-01

27

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

PubMed Central

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

Zustiak, Silviya P.; Leach, Jennie B.

2011-01-01

28

Formation of protein complex with the aid of polyethylene glycol for deproteinized natural rubber latex  

NASA Astrophysics Data System (ADS)

The effect of polyethylene glycol (PEG) as a deproteinizing agent in commercial natural rubber latex (NRL) onto the physicochemical properties of the NRL was investigated. Three types of PEG were used namely PEG200, PEG4000 and PEG20000 (molecular weight of 200, 4000 and 20000 g/mol respectively). The optimum amount of PEG in NRL was determined from viscosity changes, protein content and Fourier Transform Infrared spectroscopy. Level of protein reduction was affected by molecular weight of PEG. The addition of PEG in NRL reduced the protein content of NRL (3.30 %) to the lowest (2.01 %) at 0.40 phr of PEG200 due to more attractive hydrophobic interactions between short chains PEG compared to PEG4000 (2.24%) and PEG20000 (2.15%). This was verified through FTIR spectroscopy analysis by observing the primary and secondary amide peak where PEG4000 has lesser absorption at the region compared to with PEG20000.

Wei, Lim Keuw; Ing, Wong Kwee; Badri, Khairiah Haji; Ban, Wong Chong

2013-11-01

29

Functional gigaporous polystyrene microspheres facilitating separation of poly(ethylene glycol)-protein conjugate.  

PubMed

A novel sulfopropyl gigaporous polystyrene (SP-GP) microsphere enhancing the separation of poly(ethylene glycol)-protein (PEGylated protein) was first presented. The SP-GP microspheres were successfully prepared by introducing sulfopropyl groups into agarose-coated gigaporous polystyrene microspheres and used as chromatography media. Compared with a commercial medium, SP-GP microspheres exhibited improved column efficiency and reduced backpressure with increasing flow velocity, which could ensure its use in high-speed chromatography. Furthermore, a higher protein recovery and purity of the PEGylated protein could be obtained, even when SP-GP was applied at a flow velocity of 1224 cm h(-1). Additionally, the dynamic binding capacity (DBC) of SP-GP was significantly improved, which was higher than 10 mg mL(-1) medium even at a flow velocity of 306 cm h(-1). Further investigation using a laser scanning confocal microscope (LSCM) demonstrated that the static adsorption equilibrium of the PEGylated protein on SP-GP could be completed in 5 min, whereas a much longer period (ca. 60 min) was required for the commercial medium, indicating that the mass transfer of SP-GP was much faster with the gigaporous structure. All of these results strongly support that our developed SP-GP could serve as a promising cation exchange chromatography resin for high-speed separation, especially for biomolecules of high molecular weight. PMID:22177079

Zhai, Yanqin; Zhou, Weiqing; Wei, Wei; Qu, Jianbo; Lei, Jiandu; Su, Zhiguo; Ma, Guanghui

2012-01-27

30

Characterization of protein release from poly(ethylene glycol) hydrogels with crosslink density gradients.  

PubMed

Transplantation of cells within poly(ethylene glycol) (PEG) hydrogel scaffolds as effective immunoisolation barriers is becoming increasingly important strategy for tissue engineering and regenerative medicine. In these applications, crosslink density of these membranes has significant effect on the control of diffusion of many biomolecules such as nutrients, cellular wastes, and hormones. When these networks are designed with crosslink density gradients, alterations in network structure may have an effect on biomolecule diffusivity. The goal of this work was to synthesize PEG hydrogels via surface initiated photopolymerization for use in applications involving physiological protein delivery and cell encapsulation. For this purpose, PEG hydrogels of differing crosslink density gradients were formed via surface initiated photopolymerization, and the diffusion of model proteins with various molecular weights were observed through these PEG hydrogel scaffolds with defined properties. Diffusion coefficients were on the order of 10(-7) -10(-8) cm(2) /s and protein diffusion time scales varied from 5 min to 30 h. The results confirm that synthetic PEG hydrogels with crosslink density gradients are promising for controlled release of bioactive molecules and for covalent incorporation of ligands to support cell viability. PMID:23505227

Bal, Tu?ba; Kepsutlu, Burcu; Kizilel, Seda

2014-02-01

31

The Formation of Protein Concentration Gradients Mediated by Density Differences of Poly(ethylene glycol) Microspheres  

PubMed Central

A critical element in the formation of scaffolds for tissue engineering is the introduction of concentration gradients of bioactive molecules. We explored the use of poly(ethylene glycol) (PEG) microspheres fabricated via a thermally induced phase separation to facilitate the creation of gradients in scaffolds. PEG microspheres were produced with different densities (buoyancies) and centrifuged to develop microsphere gradients. We previously found that the time to gelation following phase separation controlled the size of microspheres in the de-swollen state, while crosslink density affected swelling following buffer exchange into PBS. The principle factors used here to control microsphere densities were the temperature at which the PEG solutions were reacted following phase separation in aqueous sodium sulfate solutions and the length of the incubation period above the ‘cloud point’. Using different temperatures and incubation times, microspheres were formed that self-assembled into gradients upon centrifugation. The gradients were produced with sharp interfaces or gradual transitions, with up to five tiers of different microsphere types. For proof-of-concept, concentration gradients of covalently immobilized proteins were also assembled. PEG microspheres containing heparin were also fabricated. PEG-heparin microspheres were incubated with fluorescently labeled protamine and used to form gradient scaffolds. The ability to form gradients in microspheres may prove to be useful to achieve better control over the kinetics of protein release from scaffolds or to generate gradients of immobilized growth factors. PMID:20719381

Roam, Jacob L.; Xu, Hao; Nguyen, Peter K.; Elbert, Donald L.

2010-01-01

32

Protein and cell patterning in closed polymer channels by photoimmobilizing proteins on photografted poly(ethylene glycol) diacrylate.  

PubMed

Definable surface chemistry is essential for many applications of microfluidic polymer systems. However, small cross-section channels with a high surface to volume ratio enhance passive adsorption of molecules that depletes active molecules in solution and contaminates the channel surface. Here, we present a one-step photochemical process to coat the inner surfaces of closed microfluidic channels with a nanometer thick layer of poly(ethylene glycol) (PEG), well known to strongly reduce non-specific adsorption, using only commercially available reagents in an aqueous environment. The coating consists of PEG diacrylate (PEGDA) covalently grafted to polymer surfaces via UV light activation of the water soluble photoinitiator benzoyl benzylamine, a benzophenone derivative. The PEGDA coating was shown to efficiently limit the adsorption of antibodies and other proteins to <5% of the adsorbed amount on uncoated polymer surfaces. The coating could also efficiently suppress the adhesion of mammalian cells as demonstrated using the HT-29 cancer cell line. In a subsequent equivalent process step, protein in aqueous solution could be anchored onto the PEGDA coating in spatially defined patterns with a resolution of <15??m using an inverted microscope as a projection lithography system. Surface patterns of the cell binding protein fibronectin were photochemically defined inside a closed microfluidic device that was initially homogeneously coated by PEGDA. The resulting fibronectin patterns were shown to greatly improve cell adhesion compared to unexposed areas. This method opens for easy surface modification of closed microfluidic systems through combining a low protein binding PEG-based coating with spatially defined protein patterns of interest. PMID:25587375

Larsen, Esben Kjær Unmack; Mikkelsen, Morten Bo Lindholm; Larsen, Niels B

2014-11-01

33

Site-selective adsorption of protein induced by a metal pattern on a poly(ethylene terephthalate) surface.  

PubMed

A novel technique for inducing site-selective adsorption of protein through constructing metal patterns on flexible poly(ethylene terephthalate) surfaces is presented. The substrates were first modified by vacuum ultraviolet (VUV) irradiation through a photomask to introduce regions with different functional groups. Then the designed metal patterns were constructed on the surfaces of VUV-treated substrates. The surface rearrangement was effectively prevented by constructing silver patterns on poly(ethylene terephthalate) surfaces, thus significantly improving the stability and selectivity of protein adsorption on the surfaces. Moreover, the protein-repulsive layer further reinforced the effect. Finally, protein patterns were successfully obtained. As confirmed by fluorescence microscope, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and static water contact angle measurement, the protein patterns possess both excellent selectivity and high fidelity. Feature size of the protein patterns surrounded by a protein-repulsive layer was exactly the same as that of the photomask. And the grain sizes of silver particles were approximately 50 nm. This work could potentially be used in various fields such as biomedicine, bioelectronic components, and tissue repair and replacement, where selective adsorption of protein is desired. PMID:23856546

Cao, Jiali; Wu, Zhongkui; Li, Shaoying; Tang, Hongxiao; Mei, Qilin

2013-11-01

34

Protein adsorption and cell adhesion on nanoscale bioactive coatings formed from poly(ethylene glycol) and albumin microgels  

PubMed Central

Late-term thrombosis on drug-eluting stents is an emerging problem that might be addressed using extremely thin, biologically-active hydrogel coatings. We report a dip-coating strategy to covalently link poly(ethylene glycol) (PEG) to substrates, producing coatings with protein-resistant layer with a thickness of approximately 75 nm. Atomic force microscopy in buffered water revealed the presence of coalesced spheres of various sizes but with diameters less than about 100 nm. Microgel-coated glass or poly(ethylene terephthalate) exhibited reduced protein adsorption and cell adhesion. Cellular interactions with the surface could be controlled by using different proteins to cap unreacted vinylsulfone groups within the coating. PMID:18771802

Scott, Evan A.; Nichols, Michael D.; Cordova, Lee H.; George, Brandon J.; Jun, Young-Shin; Elbert, Donald L.

2008-01-01

35

Tensile Properties of Extruded Corn Protein Low-Density Polyethylene Films 1  

Microsoft Academic Search

Cereal Chem. 79(2):261-264 The strength of films extruded from powder blends of corn zein or corn gluten meal (CGM) with low-density polyethylene was investigated. Tensile strength, percent elongation at break, and elastic modulus of the extruded films were measured. The tensile strength decreased from 13 MPa to ?10.5 MPa with zein addition, while CGM addition resulted in tensile strength of

Thomas J. Herald; Ersel Obuz; Wesley W. Twombly; Kent D. Rausch

2002-01-01

36

21 CFR 177.1630 - Polyethylene phthalate polymers.  

Code of Federal Regulations, 2012 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED...acid with ethylene glycol, modified with one or more of the following...acid with ethylene glycol, modified with one or more of the...

2012-04-01

37

21 CFR 177.1630 - Polyethylene phthalate polymers.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED...acid with ethylene glycol, modified with one or more of the following...acid with ethylene glycol, modified with one or more of the...

2013-04-01

38

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

PubMed

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

Gavira, Jose A; Cera-Manjarres, Andry; Ortiz, Katia; Mendez, Janet; Jimenez-Torres, Jose A; Patiño-Lopez, Luis D; Torres-Lugo, Madeline

2014-07-01

39

The effect of protein adsorption on the friction behavior of ultra-high molecular weight polyethylene  

Microsoft Academic Search

Medical-grade UHMWPE samples with two different surface finishing treatments, milling and melting\\/reforming were exposed to 10% bovine serum albumin solution and their friction responses were quantified using atomic force microscopy. The observed friction increase upon exposure to proteins was attributed to the formation of a layer of denatured proteins on the surface. Changing the crystallinity and surface energy of UHMWPE

K. S. Kanaga Karuppiah; Sriram Sundararajan; Zhi-Hui Xu; Xiaodong Li

2006-01-01

40

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

Microsoft Academic Search

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

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

2012-01-01

41

Short communication: renal tubular vacuolation in animals treated with polyethylene-glycol-conjugated proteins.  

PubMed

During toxicologic evaluation of a dimeric PEG-linked protein, tumor necrosis factor binding protein (TNF-bp), vacuolation of renal cortical tubular epithelium was seen in male and female Sprague-Dawley rats (200-300 g) given i.v. doses of 40, 20, or 10 mg/kg every other day for 3 months. Tubular lesions in rats treated with 20 or 40 mg/kg for 3 months were only partially reversible after a 2-month recovery period. Despite the presence of marked vacuolation, there were no changes in BUN, creatinine, urinalysis parameters, urinary NAG, urinary B2-microglobulin, or fractional sodium excretion. Single i.v. doses > or = 20 mg/kg TNF-bp caused similar but milder changes. However, equivalent doses of PEG alone or the non-PEG-linked TNF-bp did not cause light microscopic evidence of vacuolation. Treatment of rats with another PEG-linked protein of similar molecular weight resulted in similar changes. Immunostaining for TNF-bp revealed positivity in the apical cytoplasm of renal tubular epithelium within 1 h of i.v. dosing. Immunostaining of kidneys from chronically dosed rats indicated that protein was present in some vacuoles as long as dosing continued; however, kidneys from animals on a reversibility study had vacuoles but no immunostaining for TNF-bp. These results, along with a study that showed more severe lesions with PEG-linked proteins of lower molecular weight and minimal if any lesions with PEG-linked proteins > 70 kDa, suggest that TNF-bp is filtered through the glomerulus and that the protein with attached PEG is reabsorbed by the proximal tubules. Vacuolation may be a result of fluid distension of lysosomes due to the hygroscopic nature of PEG. These studies demonstrated that PEG-linked proteins have the capacity to induce renal tubular vacuolation at high doses. However, the change was not associated with alteration of clinical pathology or functional markers. PMID:9579027

Bendele, A; Seely, J; Richey, C; Sennello, G; Shopp, G

1998-04-01

42

The stability and immunogenicity of a protein antigen encapsulated in biodegradable microparticles based on blends of lactide polymers and polyethylene glycol  

Microsoft Academic Search

Protein-loaded microparticles were produced from blends of poly(ethylene glycol) (PEG) with poly(l-lactide) (PLA) homopolymer or poly(dl-lactide co-glycolide) copolymers (PLG) using a water-in oil-in oil method. The stability of ovalbumin (OVA) associated with microparticles prepared using PEG and 50:50 PLG, 75:25 PLG and PLA, respectively, was analysed by SDS-PAGE and quantified by scanning densitometry following incubation in PBS at 37°C for

E. C Lavelle; M.-K Yeh; A. G. A Coombes; S. S Davis

1999-01-01

43

Polyethylene Glycol Propionaldehydes  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

44

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

PubMed

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

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

2014-03-01

45

POLYETHYLENE ENCAPSULATION.  

SciTech Connect

Polyethylene microencapsulation physically homogenizes and incorporates mixed waste particles within a molten polymer matrix, forming a solidified final waste form upon cooling. Each individual particle of waste is embedded within the polymer block and is surrounded by a durable, leach-resistant coating. The process has been successfully applied for the treatment of a broad range of mixed wastes, including evaporator concentrate salts, soil, sludges, incinerator ash, off-gas blowdown solutions, decontamination solutions, molten salt oxidation process residuals, ion exchange resins, granular activated carbon, shredded dry active waste, spill clean-up residuals, depleted uranium powders, and failed grout waste forms. For waste streams containing high concentrations of soluble toxic metal contaminants, additives can be used to further reduce leachability, thus improving waste loadings while meeting or exceeding regulatory disposal criteria. In this configuration, contaminants are both chemically stabilized and physically solidified, making the process a true stabilization/solidification (S/S) technology. Unlike conventional hydraulic cement grouts or thermosetting polymers, thermoplastic polymers such as polyethylene require no chemical. reaction for solidification. Thus, a stable, solid, final waste form product is assured on cooling. Variations in waste chemistry over time do not affect processing parameters and do not require reformulation of the recipe. Incorporation of waste particles within the polymer matrix serves as an aggregate and improves the mechanical strength and integrity of the waste form. The compressive strength of polyethylene microencapsulated waste forms varies based on the type and quantity of waste encapsulated, but is typically between 7 and 17.2 MPa (1000 and 2500 psi), well above the minimum strength of 0.4 MPa (160 psi) recommended by the U.S. Nuclear Regulatory Commission (NRC) for low-level radioactive waste forms in support of 10 CFR 61 (NRC, 1991; 1983) Because polyethylene is a relatively new material, it is difficult to predict its long-term durability. However, prior to scale-up of the microencapsulation process, a study was conducted to evaluate potential degradation mechanisms. The study examined potential effects on mechanical integrity from exposure to chemicals and solvents, thermal cycling, saturated environments, microbial attack, and high gamma-radiation fields (Kalb et al., 1991). At ambient temperatures, polyethylene is relatively inert to most chemicals, including organic solvents, acids, and alkaline solutions. Exposure to changes in temperature or saturated soil conditions have been shown to degrade the mechanical integrity of some waste forms, but had little or no measurable impact on polyethylene waste forms. Low-density polyethylene is not susceptible to growth of microbial organisms, a fact that is evidenced by the lack of plastics decomposition in municipal waste landfills. When exposed to gamma-radiation at total doses of up to lo8 rad, additional cross-linking of the polymer occurs, resulting in increased strength and lower leachability.

KALB, P.

2001-08-22

46

Chemistry and stability of thiol based polyethylene glycol surface coatings on colloidal gold and their relationship to protein adsorption and clearance in vivo  

NASA Astrophysics Data System (ADS)

Nanomaterials have presented a wide range of novel biomedical applications, with particular emphasis placed on advances in imaging and treatment delivery. Of the many particulate nanomaterials researched for biomedical applications, gold is one of the most widely used. Colloidal gold has been of great interest due to its chemical inertness and its ability to perform multiple functions, such as drug delivery, localized heating of tissues (hyperthermia), and imaging (as a contrast agent). It is also readily functionalized through the use of thiols, which spontaneously form sulfur to gold bonds with the surface. Polyethylene glycol (PEG) is the most widely used coating material for these particles as it provides both steric stability to the suspension and protein resistance. These properties extend the circulation time of the particles in blood, and consequently the efficacy of the treatment. Despite widespread use of PEG coated gold particles, the coating chemistry and stability of these particles are largely unknown. The goal of this work was to identify the mechanisms leading to degradation and stability of thiol based polyethylene glycol coatings on gold particles and to relate this behavior to protein adsorption and clearance in vivo. The results indicate that the protective PEG coating is susceptible to sources of oxidation (including dissolved oxygen) and competing adsorbates, among other factors. The quality of commercially available thiolated PEG reagents was also found to play a key role in the quality and protein resistance of the final PEG coating. Analysis of the stability of these coatings indicated that they rapidly degrade under physiological conditions, leading to the onset of protein adsorption when exposed to plasma or blood. Paralleling the protein adsorption behavior and onset of coating degradation observed in vitro, blood clearance of parenterally administered PEG coated particles in mice began after approximately 2h of circulation time. Taken together, the data presented in this work indicates that the stability of the PEG coating and the many factors affecting it represent a fundamental limitation to the use of these particles.

Carpinone, Paul

47

Role of Thermo-responsiveness and Poly(ethylene glycol) Diacrylate Cross-link Density on Protein Release from Poly(N-isopropylacrylamide) Hydrogels.  

PubMed

Thermo-responsive hydrogels have shown promise as injectable materials for local drug delivery. However, the phase-induced changes in polymer properties of N-isopropylacrylamide (NIPAAm) can pose additional challenges for achieving controlled protein release. In this work, thermo-responsive hydrogels derived from NIPAAm and cross-linked with poly(ethylene glycol) diacrylate (PEG-DA) were synthesized via free radical polymerization. The volume phase transition temperature (VPTT) of the hydrogels ranged from 32.9 degrees C to 35.9 degrees C. Below the VPTT, swelling ratios of the hydrogels decreased with cross-linker concentration, and showed a sharp drop (at least 4-fold) upon phase change. Protein encapsulation efficiency was high (84-90%) and decreased with cross-linker concentration. Release of bovine serum albumin, a model protein, at body temperature was significantly higher than at room temperature (67% at 37 degrees C compared to 44% at 23 degrees C after 48 h). The release kinetics of proteins from the hydrogels were initially expected to be a function of cross-link density. However, at the hydrogel compositions explored in this work, protein release did not change significantly with cross-linker mol fraction. The thermo-responsive hydrogels offer a promising platform for the localized delivery of proteins. PMID:20540835

Drapala, Pawel W; Brey, Eric M; Mieler, William F; Venerus, David C; Derwent, Jennifer J Kang; Pérez-Luna, Victor H

2010-06-10

48

Polyethylene Glycol 3350  

MedlinePLUS

Polyethylene glycol 3350 is used to treat occasional constipation. Polyethylene glycol 3350 is in a class of medications ... Polyethylene glycol 3350 comes as a powder to be mixed with a liquid and taken by mouth. ...

49

Polymers for the stabilization and delivery of proteins topically and per os to the insect hemocoel through conjugation with aliphatic polyethylene glycol.  

PubMed

Co-feeding of aliphatic polyethylene glycol (PEG), phospholipase A2, anionic and ionic detergents, and amphipathic glycoside with bovine serum albumin (BSA) as a model protein to fourth stadium tobacco budworms, Heliothis virescens, did not affect the levels of BSA in the hemolymph. Covalent conjugation of small proteins like the decapeptide trypsin modulating oostatic factor (TMOF) to polyethylene glycol was previously shown to protect the peptide from protease attack and enhance its accumulation in the insect hemocoel. Whether this polymer chemistry could do the same for larger proteins was examined. The chemistry for the synthesis of polydispersed aliphatic PEG350-insulin and monodispersed aliphatic PEG333-insulin are described herein. Insulin was used for this synthesis and not BSA to better control conjugation among the available free amine groups. When PEGylated insulin or free insulin were fed in artificial diet to fifth stadium budworms, greater concentrations of insulin using the PEGylated variants were found in the hemolymph than when free insulin was used (a 6.7 and 7.3-fold increase for the PEG350 and PEG333 conjugates, respectively). When insulin is topically applied to the dorsum of H. virescens, no insulin is found in the hemolymph. However, after topical application of the PEGylated insulins, PEG350-insulin and PEG333-insulin were detected in the hemolymph. After injections of insulin into the hemocoel of fourth stadium H. virescens, insulin is completely cleared from the hemolymph in 120min. In comparison, PEG350-insulin and PEG333-insulin were present in the hemolymph for 300 and 240min after injection, respectively, translating to a 3.3 and 2.7-fold increase in the length of time insulin remains in the hemolymph after injection. PMID:25307467

Jeffers, Laura A; Shen, Hongyan; Bissinger, Brooke W; Khalil, Sayed; Gunnoe, T Brent; Roe, R Michael

2014-10-01

50

Interactions between poly(ethylene glycol) and protein in dichloromethane/water emulsions: a study of interfacial properties.  

PubMed

From adsorption kinetics and interfacial rheological studies performed by using a pendant-drop method, i.e. in conditions close to those of the primary emulsion of the water-in-oil-in-water emulsion-encapsulation technique, it was shown that adsorption of the hen egg-white lysozyme (HEWL) at the water/dichloromethane (DCM) interface can be efficiently slowed down by modulating some parameters. It was shown that a decrease of the ionic strength of the aqueous phase, and the optimization of the density of the poly(ethylene glycol) (PEG) adsorbed film by increasing the PEG concentration or by modulating the polymer chain length, can significantly decrease the rate of adsorption of HEWL at the water/DCM interface. Moreover, it was shown that the choice of the dissolution phase of PEG (DCM or water) clearly influences the results. PMID:18374553

Malzert-Fréon, Aurélie; Benoît, Jean-Pierre; Boury, Frank

2008-08-01

51

Application of MS-Based Proteomics to Study Serum Protein Adsorption/Absorption and Complement C3 Activation on Poly(ethylene glycol) Hydrogels  

PubMed Central

Although the interaction between cells and poly(ethylene glycol) (PEG) hydrogels is well documented, there lacks a thorough investigation into the adsorption of blood proteins on these surfaces which dictates the observed cellular and in vivo host response. Thus, a clear understanding of how surface-bound proteins mediate the unique biological property of PEG hydrogels is fundamentally important. The information obtained will also provide insights into future biomaterial design. In this study, several mass-spectrometry-based proteomic tools coupled with complementary immunoassays were employed to survey the complex surface-bound serum proteome. The adsorption of vitronectin, thrombin, fibrinogen and complement component C3 was significantly lower on PEG hydrogels than on tissue culture polystyrene (TCPS). Although PEG hydrogels mediated lower C3 adsorption than TCPS, the extent of C3 activation between the two surfaces was comparable. Adherent monocyte density was also significantly lower on PEG hydrogels as compared to TCPS. Taken together, these results support the critical role of the complement C3 in mediating monocyte adhesion on biomaterials. Thus we conclude that the biocompatibility of PEG hydrogels both in vitro and in vivo can be partly contributed to their limited C3 interaction and monocyte activity. PMID:20594411

Wang, Xintong; Schmidt, David R.; Joyce, Evan J.; Kao, W. John

2013-01-01

52

Two Novel Class II Hydrophobins from Trichoderma spp. Stimulate Enzymatic Hydrolysis of Poly(Ethylene Terephthalate) when Expressed as Fusion Proteins  

PubMed Central

Poly(ethylene terephthalate) (PET) can be functionalized and/or recycled via hydrolysis by microbial cutinases. The rate of hydrolysis is however low. Here, we tested whether hydrophobins (HFBs), small secreted fungal proteins containing eight positionally conserved cysteine residues, are able to enhance the rate of enzymatic hydrolysis of PET. Species of the fungal genus Trichoderma have the most proliferated arsenal of class II hydrophobin-encoding genes among fungi. To this end, we studied two novel class II HFBs (HFB4 and HFB7) of Trichoderma. HFB4 and HFB7, produced in Escherichia coli as fusions to the C terminus of glutathione S-transferase, exhibited subtle structural differences reflected in hydrophobicity plots that correlated with unequal hydrophobicity and hydrophily, respectively, of particular amino acid residues. Both proteins exhibited a dosage-dependent stimulation effect on PET hydrolysis by cutinase from Humicola insolens, with HFB4 displaying an adsorption isotherm-like behavior, whereas HFB7 was active only at very low concentrations and was inhibitory at higher concentrations. We conclude that class II HFBs can stimulate the activity of cutinases on PET, but individual HFBs can display different properties. The present findings suggest that hydrophobins can be used in the enzymatic hydrolysis of aromatic-aliphatic polyesters such as PET. PMID:23645195

Espino-Rammer, Liliana; Ribitsch, Doris; Przylucka, Agnieszka; Marold, Annemarie; Greimel, Katrin J.; Herrero Acero, Enrique; Guebitz, Georg M.; Kubicek, Christian P.

2013-01-01

53

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

PubMed Central

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

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

54

The stability and immunogenicity of a protein antigen encapsulated in biodegradable microparticles based on blends of lactide polymers and polyethylene glycol.  

PubMed

Protein-loaded microparticles were produced from blends of poly(ethylene glycol) (PEG) with poly(L-lactide) (PLA) homopolymer or poly(DL-lactide co-glycolide) copolymers (PLG) using a water-in oil-in oil method. The stability of ovalbumin (OVA) associated with microparticles prepared using PEG and 50:50 PLG, 75:25 PLG and PLA, respectively, was analysed by SDS-PAGE and quantified by scanning densitometry following incubation in PBS at 37 degrees C for up to 1 month. Fragmentation and aggregation of OVA was detected with all 3 formulations. The extent of both processes correlated with the degradation rate of the lactide polymer used and decreased in the order PLA < 75:25 PLG < 50:50 PLG. Extensive degradation of the PLG/PEG microparticles also occurred over 4 weeks whereas the use of PLA/PEG blends resulted in a stable microparticle morphology and much reduced fragmentation and aggregation of the associated protein. Following a single sub-cutaneous immunisation, high levels of specific serum IgG antibody were elicited by OVA associated with the PLA/PEG particles. Injection of OVA associated with the 75:25 PLG/PEG microparticles resulted in very low levels of specific antibody. A higher response was induced by the 50:50 PLG/PEG formulation but there was very large inter-animal variation in this group. Antibody levels elicited by all 3 formulations were significantly higher than those elicited by a single injection of soluble OVA. Analysis of antigen specific IgG1 and IgG2a antibody subtype levels also revealed the greater efficacy of the PLA/PEG microparticles as an adjuvant system. The use of PLA/PEG microparticles shows improved protein loading and delivery capacity while maintaining a high level of stability of the associated protein. These results indicate a strong correlation between the stability of microencapsulated antigen and the magnitude of the immune response following sub-cutaneous immunisation. PMID:10075157

Lavelle, E C; Yeh, M K; Coombes, A G; Davis, S S

1999-02-12

55

[Biodegradation of polyethylene].  

PubMed

Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed. PMID:17633197

Yang, Jun; Song, Yi-ling; Qin, Xiao-yan

2007-05-01

56

Micromechanical modelling of polyethylene  

NASA Astrophysics Data System (ADS)

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

Alvarado Contreras, Jose Andres

2008-10-01

57

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

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

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

2014-01-01

58

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

PubMed Central

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

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

2011-01-01

59

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...

60

Highly Cross-Linked Polyethylenes  

Microsoft Academic Search

\\u000a Osteolysis after total joint replacement using ultra-high molecular weight Polyethylene bearing components has been shown\\u000a to be a major factor for the long-term failure of such components. Highly cross-linked polyethylene has already been introduced\\u000a in the late 1970s and demonstrated to have superior wear resistance compared to non-irradiated and irradiation sterilized\\u000a polyethylene used since 1962. In 1986 irradiation sterilization in

Robert M. Streicher

61

Isolated Polyethylene Exchange versus Acetabular Revision for Polyethylene Wear  

Microsoft Academic Search

Polyethylene wear and osteolysis are not uncommon in THA mid- and long-term. In asymptomatic patients the dilemma faced by\\u000a the orthopaedic surgeon is whether to revise the cup and risk damage to the supporting columns and even pelvic discontinuity\\u000a or to perform isolated polyethylene exchange and risk a high rate of postoperative recurrent instability and dislocation that\\u000a will necessitate further

Camilo Restrepo; Elie Ghanem; Carrie Houssock; Mathew Austin; Javad Parvizi; William J. Hozack

2009-01-01

62

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

NASA Astrophysics Data System (ADS)

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.

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

2007-03-01

63

Profiles in garbage: Polyethylene terephthalate  

SciTech Connect

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

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1997-11-01

64

Profiles in garbage: Polyethylene terephthalate  

Microsoft Academic Search

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks -- along with salad dressing, fruit juices, peanut butter, and other household and consumer products -- use PET bottles. PET also is used for film, sheeting for cups and food trays, oven-safe trays, and other uses. PET is a relatively new packaging resin, first commercialized in

1997-01-01

65

Micropatterning of poly(ethylene glycol) diacrylate hydrogels.  

PubMed

This protocol describes the techniques to synthesize and fabricate micropatterned poly(ethylene glycol) diacrylate-based hydrogels that can be used as substrates in cellular studies and tissue engineering scaffolds. These materials provide an essentially bioinert background material due to the very low protein adsorption characteristics of poly(ethylene glycol), but the materials can be modified with covalently grafted peptides, proteins, or other biomolecules of interest to impart specific biofunctionality to the material. Further, it is possible to use micropatterning technologies to control the localization of such covalent grafting of biomolecules to the hydrogel materials, thus spatially controlling the cell-material interactions. This protocol presents a relatively simple approach for mask-based photolithographic patterning, generally best suited for patterning the surface of hydrogel materials for 2D cell studies. A more sophisticated technique, two-photon laser scanning lithography, is also presented. This technique allows free-form, 3D micropatterning in hydrogels. PMID:24560506

Ali, Saniya; Cuchiara, Maude L; West, Jennifer L

2014-01-01

66

Waste product profile: Polyethylene terephthalate  

SciTech Connect

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

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1996-02-01

67

Polyethylene multiwalled carbon nanotube composites  

Microsoft Academic Search

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

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

68

Electronic structures of polyethylene and polytetrafluoroethylene  

SciTech Connect

Results of first-principles calculations on polyethylene (poly-(CH{sub 2})) and polytetrafluoroethylene (poly-(CF{sub 2})) are reported. We have optimized the carbon-carbon bond lengths for polyethylene, and using the optimized value we have considered structures in which the carbon backbone is assumed helical both for polyethylene and for polytetrafluoroethylene. The calculated bond lengths and valence-band structures are compared with those of other theoretical approaches and with experimental data. It is finally discussed why polyethylene has a planar carbon backbone whereas polytetrafluoroethylene is nonplanar.

Springborg, M. (Nordisk Institut for Teoretisk Atomfysik (NORDITA), Blegdamsvej 17, DK-2100 Kobenhavn O, Denmark (US) Max-Planck-Institut fur Festkorperforschung, Postfach 800665, D-7000 Stuttgart 80, Federal Republic of Germany Center for Materials Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545); Lev, M. (Max-Planck-Institut fur Festkorperforschung, Postfach 800665, D-7000 Stuttgart 80, Federal Republic of Germany)

1989-08-15

69

Single electron states in polyethylene  

SciTech Connect

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.

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

70

Poly(ethylene oxide) functionalization  

DOEpatents

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.

Pratt, Russell Clayton

2014-04-08

71

Light transmission through polyethylene samples  

NASA Astrophysics Data System (ADS)

A spectral calibration Hg(Ar) lamp and a pulsed Nd:YAG laser were employed to study the UV, VIS and IR light transmission through polyethylene samples, as pure and doped with Fe 2O 3 and carbon nanotubes. Optical measurements were performed in the spectral range between 200 nm and 800 nm. Measurements with 0.1% and 1% in weight of filler concentrations were investigated. The polymers' optical absorption coefficients, calculated from the experimental transmitted component, were tabulated at different wavelengths as a function of the analyzed samples. The radiation depth penetration was also evaluated.

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

2012-03-01

72

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2014 CFR

...Polyethylene resins, carboxyl modified. 177.1600 Section 177...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT...Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may...

2014-04-01

73

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2012 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2012-04-01

74

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2010 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2010-04-01

75

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2013 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2013-04-01

76

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2011 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2011-04-01

77

Chemical modification of lipase with polyethylene glycol  

SciTech Connect

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.

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

1986-05-01

78

Ultrasonic Heating of Poly(ethylene terephthalate), Polypropylene, High-Density Polyethylene, and Low-Density Polyethylene Films  

NASA Astrophysics Data System (ADS)

The ultrasonic heating rates of poly(ethylene terephthalate) (PET), polypropylene (PP), high-density polyethylene (HDPE), and low-density polyethylene (LDPE) films are reported. For this measurement, we used an experimental set-up consisting of an ultrasonic vibrator, a horn, and a radiation thermometer. Because the horn did not touch the film surfaces, the temperature increase was only by the ultrasonic vibration transmitted from the horn. The highest and lowest temperature increase were recorded for the PET and LDPE films, respectively. The temperature increase was related with the viscosity of the polymer films.

Murao, Satoshi; Hosokawa, Takehiro; Kajitani, Tsuyoshi

2012-09-01

79

Which polyesters can mimic polyethylene?  

PubMed

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

Stempfle, Florian; Ortmann, Patrick; Mecking, Stefan

2013-01-11

80

Protein  

MedlinePLUS

... gov . Nutrition for Everyone Nutrition Topics Share Compartir Protein What do you think about when you hear ... How much protein do I need? What is Protein? Proteins are part of every cell, tissue, and ...

81

Protein  

NSDL National Science Digital Library

Protein structure: Primary protein structure is a sequence of amino acids. Secondary protein structure occurs when the amino acids in the sequence are linked by hydrogen bonds. Tertiary protein structure occurs when certain attractions are present between alpha helices and pleated sheets. Quaternary protein structure is a protein consisting of more than one amino acid chain.

Darryl Leja (National Human Genome Research Institute REV)

2005-04-04

82

Reduced adhesion of human blood platelets to polyethylene tubing by microplasma surface modification  

E-print Network

Reduced adhesion of human blood platelets to polyethylene tubing by microplasma surface, an in vitro blood-flow loop circulated heparinized human blood through both a plasma-treated and -untreated PE with various cells, proteins, and a range of pH values will be closely related to the nonfouling

von Andrian, Ulrich H.

83

Soluble hyperbranched grafts on polyethylene surfaces  

E-print Network

Here we report two methods to synthesize hyperbranched poly(acrylic acid) grafts on polyethylene films and powders. The previously reported route using ?,[]-diaminopoly(tert-butyl acrylate) was repeated and all previous results were confirmed...

Britton, Danielle M

2002-01-01

84

Reuse of polyethylene waste in road construction.  

PubMed

The cost of construction of flexible pavements depends on thickness of the pavement layers. The thickness of pavement mainly depends on the strength of the subgrade. By suitable improvement to the strength of the subgrade, considerable saving in the scarce resources and economy can be achieved. Because of their lightweight, easy handling, non-breakable and corrosion free nature, polyethylene have surpassed all other materials in utility. But polyethylene waste has been a matter of concern to environmentalists as it is non-biodegradable. In this investigation, an attempt has been made to study the improvement of California Bearing Ratio (CBR) value of soils stabilized with waste polyethylene bags. This alternative material is mixed in different proportions to the gravel and clay to determine the improvement ofCBR value. Use of the waste polyethylene bags observed to have a significant impact on the strength and economy in pavement construction, when these are available locally in large quantities. PMID:18472564

Raju, S S S V Gopala; Murali, M; Rengaraju, V R

2007-01-01

85

Acute polyethylene fracture in an uncemented acetabular cup  

PubMed Central

The smaller acetabular components used in total hip replacement may have a polyethylene liner that is too thin, resulting in higher polyethylene stress and an increased potential for wear. The authors present a case that highlights the problem of acute polyethylene fracture. To compensate for the thinness of the polyethylene, the authors recommend the use of a smaller head size to allow polyethylene thickness of at least 8 mm. PMID:9267302

Gross, Allan E.; Dust, William N.

1997-01-01

86

Osmotic effects of polyethylene glycol.  

PubMed

Polyethylene glycol (PEG) has been used to increase the osmotic pressure of fluids used to cleanse the gastrointestinal tract. However, little is known about its osmotic activity. To investigate this activity systematically, solutions of PEG of differing molecular weights were made and subjected to measurement of osmolality by both freezing point depression and vapor pressure osmometry. Measured osmolality was increasingly greater than predicted from average molecular weight as PEG concentration increased. Measurement of sodium activity in NaCl/PEG solutions by means of an ion-selective electrode suggested that the higher than expected osmolality could be due in part to interactions that, in effect, sequestered water from the solution. Osmolality was consistently greater by freezing point osmometry than by vapor pressure osmometry. To determine which osmometry method reflected biologically relevant osmolality, normal subjects underwent steady-state total gut perfusion with an electrolyte solution containing 105 g/L of PEG 3350. This produced rectal effluent that was hypertonic by freezing point osmometry but isotonic by vapor pressure osmometry. Assuming that luminal fluid reaches osmotic equilibrium with plasma during total gut perfusion, this result suggests that the vapor pressure osmometer accurately reflects the biologically relevant osmolality of intestinal contents. We conclude that PEG exerts more of an osmotic effect than would be predicted from its molecular weight. This phenomenon may reflect interactions between PEG and water molecules that alter the physical chemistry of the solution and sequester water from the solution. PMID:3345895

Schiller, L R; Emmett, M; Santa Ana, C A; Fordtran, J S

1988-04-01

87

Novel method of preparing acellular cardiovascular grafts by decellularization with poly(ethylene glycol).  

PubMed

We have developed a new method of preparing acellular vascular grafts. Cellular components, including cell membranes and proteins in cytosol, were efficiently extracted from the vessels in a concentrated aqueous solution of poly(ethylene glycol), an amphiphilic biocompatible polymer. The residual DNA was digested by deoxyribonuclease I treatment after extraction with poly(ethylene glycol). The two-step extraction process proved quite effective at removing the cellular components while causing little damage to the extracellular matrices. We did not use any detergent that would damage the extracellular matrices. Therefore, vascular endothelial cells grew well on the acellular vessels after recellularization, promising longi-patent cardiovascular grafts. PMID:14613231

Uchimura, Eiichiro; Sawa, Yoshiki; Taketani, Satoshi; Yamanaka, Yuka; Hara, Masayuki; Matsuda, Hikaru; Miyake, Jun

2003-12-01

88

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

Code of Federal Regulations, 2012 CFR

...polyethylene terephthalate, or polytetrafluoroethylene. 870.3470 Section 870...polyethylene terephthalate, or polytetrafluoroethylene. (a) Identification. ...polyethylene terephthalate, or polytetrafluoroethylene is a fabric device placed...

2012-04-01

89

Polymeric compositions incorporating polyethylene glycol as a phase change material  

DOEpatents

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.

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

1989-01-01

90

Introduction to current and future protein therapeutics: A protein engineering perspective  

Microsoft Academic Search

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

Paul J. Carter

2011-01-01

91

76 FR 70965 - Polyethylene Retail Carrier Bags From Thailand: Correction to the Amended Final Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Correction to the Amended...duty order on polyethylene retail carrier bags from Thailand for the period August 1...duty order on polyethylene retail carrier bags from Thailand. See Polyethylene...

2011-11-16

92

The Radiothermoluminescence Of The Chlorinated Polyethylene  

NASA Astrophysics Data System (ADS)

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

Polizov, Hristo T.

2007-04-01

93

Relationship between arterial thrombosis and neutralization of a polyethylene ionomer  

SciTech Connect

The influence of three levels of sodium neutralization of an ethylene/methacrylic acid copolymer on in vivo blood compatibility was studied in a canine arterial model. Effects due to sample fabrication methods were also monitored. Sodium content, sodium release, hydrogen dissociation, and localization of anionic groups were noted. Polymer surface energy, surface morphology, water uptake, and thermal properties were characterized. Material characterization and in vivo implantation disclose the following: (1) thermal pressing generated oxidation degradation products that decreased in vivo blood compatibility. Solution-cast samples adhered and activated fewer blood elements; (2) platelets and leukocytes were sensitive to differences in shear rate in the carotid and femoral arteries, with the femoral site tending toward higher shear, more platelet deposition and fewer leukocytes; (3) the surface properties of the polyethylene control, 0% Na, and 50% Na samples tended to be similar. These properties were different from the 100% Na sample; (4) these differences were manifested in vivo by platelet activation and thrombus development on the polyethylene, 0% Na, and 50% Na implants, while the 100% Na implant surfaces were predominantly covered by singly adherent, unactivated platelets; (5) it is proposed that the improvement in biocompatibility for the 100% Na ionomer is due to the cluster development in the neutralized methacrylic component and that either directly, or through appropriate protein adsorption and/or conformational adjustment to the cluster regions, platelets are not activated and do not initiate the coagulation mechanism.

Goggins, J.A.; Hiltner, A.; Jones, P.K. (Case Western Reserve Univ., Cleveland, OH (United States)); Jones, R.D. (Saint Luke's Hospital, Cleveland, OH (United States))

1993-05-01

94

STRESS CRACK TESTING OF POLYETHYLENE GEOMEMBRANES  

EPA Science Inventory

The sensitivity of high density polyethylene (HDPE) geomembranes to stress cracking is evaluated under accelerated conditions at a constant stress. he test specimens are according to ASTM D-1822, and are of the dumbbell shape with a constant length in the central section. he acce...

95

Electrical conductivity effects in polyethylene terephthalate films  

Microsoft Academic Search

Electrical conductivity effects in biaxially stretched polyethylene terephthalate (PET) films of 6 mum thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 10-2-106 Hz and at temperatures higher than the glass transition temperature (~85 °C) up to 190 °C. The formalisms of complex permittivity, electric modulus, and impedance were employed to

E. Neagu; P. Pissis; L. Apekis

2000-01-01

96

21 CFR 177.1610 - Polyethylene, chlorinated.  

Code of Federal Regulations, 2010 CFR

...and Repeated Use Food Contact Surfaces § 177.1610...components of articles that contact food, except for articles...Materials, 100 Barr Harbor Dr., West Conshohocken...Administration (NARA). For information on the availability...polyethylene may be used in contact with all types of...

2010-04-01

97

Carbon Fibers from Polyethylene-Based Precursors  

Microsoft Academic Search

Polyethylene fibers are attractive as carbon fiber precursors due to their high carbon content and ease of manufacture. Also, highly ordered and oriented fibers with extraordinary physical and mechanical properties are available today. However, being thermoplastic fibers, they soften or melt at a fairly low temperature, losing their fiber form. These precursors have to be stabilized by introducing cross links

Dong Zhang; Gajanan S. Bhat

1994-01-01

98

Cross-Linked Polyethylene for Higher Voltages  

Microsoft Academic Search

The rapid evolution of cross-linked polyethylene for high-voltage cable applications and the factors which promoted this development are discussed in relation to the growing demand for solid-dielectric constructions. Advances in cable design and technology are outlined for this thermally-stable insulation, highlighting the technical advantages of tandem-extruded cross-linked semiconductive shielding.

A. L. Mckean; F. S. Oliver; S. W. Trill

1967-01-01

99

Ultrasonically enhanced persulfate oxidation of polyethylene surfaces  

Microsoft Academic Search

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

Fiona Keen

1996-01-01

100

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 ...

101

Herbicide dissipation from low density polyethylene mulch  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field and laboratory studies were conducted to examine herbicide dissipation when applied to low density polyethylene (LDPE) mulch for dry scenarios vs. washing off with water. In field studies, halosulfuron, paraquat, carfentrazone, glyphosate, and flumioxazin were applied to black 1.25-mil LDPE at...

102

Proteins  

NSDL National Science Digital Library

Paul Anderson explains the structure and importance of proteins. He describes how proteins are created from amino acids connected by dehydration synthesis. He shows the importance of chemical properties in the R-groups of individual amino acids in the polypeptide.

Paul Anderson

2013-03-12

103

Proteins.  

ERIC Educational Resources Information Center

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)

Doolittle, Russell F.

1985-01-01

104

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

Microsoft Academic Search

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

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

105

Structural Development During Thermal Fractionation of Polyethylenes  

Microsoft Academic Search

In this study, the stepwise isothermal crystallization or thermal fractionation of Ziegler—Natta and metallocene based polyethylenes (ZN-PE and m-PE) with two kinds of branch lengths (ethyl and hexyl) and branch compositions were studied using simultaneous synchrotron small-angle X-ray scattering (SAXS)\\/wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The crystal long period and the invariant were determined by SAXS, and

W. Liu; S. Kim; J. Lopez; B. Hsiao; M. Y. Keating; I.-H. Lee; B. Landes; R. S. Stein

2000-01-01

106

Speciation of antimony in polyethylene terephthalate bottles  

SciTech Connect

Antimony contamination has been reported in drinking water from polyethylene terephthalate (PET) bottles. Micro-X-ray fluorescence (XRF) analysis has been used to identify the distribution and chemical form of residual antimony used as a catalyst in the manufacture of PET bottles. The results are consistent with clusters of Sb(III) having dimensions of the order of tens of micrometers, clearly showing the ability of synchrotron radiation analyses to both map elemental distribution and determine oxidation state.

Martin, R.R.; Ablett, J.; Shotyk, W.S.; Naftel, S.; Northrup, P.

2009-12-18

107

Thermophilic microbial degradation of polyethylene succinate  

Microsoft Academic Search

This paper examined the biodegradability of a new aliphatic polyester, polyethylene succinate (PES), at a high incubation temperature of 50°C. The distribution and population of total colonies and of PES degrading micro organisms on polymer-emulsified agar plates were determined using the plate count and clear zone methods. The PES-decomposers were present in six of 10 soil samples and the total

M. L. Tansengco; Y. Tokiwa

1998-01-01

108

Structure and plastic deformation of polyethylene  

Microsoft Academic Search

A review is given of the structure of semi-crystalline polymers and the mechanisms of plastic deformation in them. High-density polyethylene (HDPE) is taken as the specific example because of the large number of detailed studies performed on this material. The early findings are also compared and contrasted with very recent detailed large-strain deformation studies and computer simulations of deformation-induced texture

L. Lin; A. S. Argon

1994-01-01

109

Surface modification of polyethylene by functionalized plasma  

SciTech Connect

The surface of low density polyethylene(PE) has been modified by functionalized plasma-polymerized N-vinyl-2-pyrrolidone (PPNVP) and allyl alcohol(PPAA) thin films, PPNVP and PPAA(approx. 100 nm). The surface structure and functional groups of modified surfaces were characterized by water contact angle, ATR/FTIR and ESCA techniques. Plasma polymer modified PE surfaces exhibited significant water contact angle hysteresis and a much lower value of advancing water contact angle than that of unmodified polyethylene. Reduction of PPNVP and PPAA modified surfaces by sodium borohydride coverted into hydroxyl groups. The determined concentrations of hydroxyl groups on the reduced PPNVP and PPAA modified surfaces by ESCA after gas-phase derivatization with trifluoroacetic anhydride (TFAA) were about 25% and 30% of total oxygen content, respectively. Finally, the amine containing molecules such as amine-terminated polyethylene oxide (PEO) and 3-aminopropyltriethoxysilane (APTS) were coupled to the hydroxylated surfaces. These novel modified PE surfaces are suitable for immobilization of biomolecules.

Yuan, S.; Marchant, R.E. [Case Western Reserve Univ., Cleveland, OH (United States)

1993-12-31

110

Protein  

MedlinePLUS

... juvenile or insulin-dependent diabetes), proteins found in cow’s milk have been implicated in the development of ... O., et al., Removal of Bovine Insulin From Cow’s Milk Formula and Early Initiation of Beta-Cell ...

111

Fabrication and Anti-Fouling Properties of Photochemically and Thermally Immobilized Poly(Ethylene Oxide) and Low Molecular Weight Poly(Ethylene Glycol) Thin Films  

PubMed Central

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 uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2 × 10?4/Å2 and an average distance between grafted chains of 33 Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers. PMID:21044787

Wang, Hui; Ren, Jin; Hlaing, Aye; Yan, Mingdi

2010-01-01

112

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

PubMed

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 uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2×10(-4)Å(-2) and an average distance between grafted chains of 33Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers. PMID:21044787

Wang, Hui; Ren, Jin; Hlaing, Aye; Yan, Mingdi

2011-02-01

113

Preparation of extruded polyethylene/chitosan blends compatibilized with polyethylene-graft-maleic anhydride.  

PubMed

Novel films of polyethylene and chitosan were obtained using extrusion. These polymers have interesting properties, and processing them with methods that are of high use in the industry, such as the extrusion method, can have a significant effect on the potential applications of these materials. The individual materials were thermally characterized; after this, extruded films of low density polyethylene and chitosan mixtures were prepared with the addition of polyethylene-graft-maleic anhydride as a compatibilizer for the blends, and glycerol, as a plasticizer for chitosan. The use of compatibilizer and plasticizer agents improved the processability and compatibility of the mixtures, as well as their mechanical properties, as revealed by mechanical property measurements and scanning electron microscopy. It was possible to prepare blends with a maximum chitosan content of 20 wt%. The material stiffness increased with the increase of chitosan in the sample. FTIR studies revealed the existence of an interaction between the compatibilizer and chitosan. PMID:24299879

Quiroz-Castillo, J M; Rodríguez-Félix, D E; Grijalva-Monteverde, H; Del Castillo-Castro, T; Plascencia-Jatomea, M; Rodríguez-Félix, F; Herrera-Franco, P J

2014-01-30

114

Mechanisms for Covalent Immobilization of Horseradish Peroxidase on Ion-Beam-Treated Polyethylene  

PubMed Central

The surface of polyethylene was modified by plasma immersion ion implantation. Structure changes including carbonization and oxidation were observed. High surface energy of the modified polyethylene was attributed to the presence of free radicals on the surface. The surface energy decay with storage time after treatment was explained by a decay of the free radical concentration while the concentration of oxygen-containing groups increased with storage time. Horseradish peroxidase was covalently attached onto the modified surface by the reaction with free radicals. Appropriate blocking agents can block this reaction. All aminoacid residues can take part in the covalent attachment process, providing a universal mechanism of attachment for all proteins. The native conformation of attached protein is retained due to hydrophilic interactions in the interface region. The enzymatic activity of covalently attached protein remained high. The long-term activity of the modified layer to attach protein is explained by stabilisation of unpaired electrons in sp2 carbon structures. A high concentration of free radicals can give multiple covalent bonds to the protein molecule and destroy the native conformation and with it the catalytic activity. The universal mechanism of protein attachment to free radicals could be extended to various methods of radiation damage of polymers. PMID:24278665

Kondyurin, Alexey V.; Naseri, Pourandokht; Tilley, Jennifer M. R.; Nosworthy, Neil J.; Bilek, Marcela M. M.; McKenzie, David R.

2012-01-01

115

The yield behavior of polyethylene tubes subjected to biaxial loadings  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

116

Patterned functional carbon fibers from polyethylene  

SciTech Connect

Patterned, continuous carbon fibers with controlled surface geometry were produced from a novel melt-processible carbon precursor. This portends the use of a unique technique to produce such technologically innovative fibers in large volume for important applications. The novelties of this technique include ease of designing and fabricating fibers with customized surface contour, the ability to manipulate filament diameter from submicron scale to a couple of orders of magnitude larger scale, and the amenable porosity gradient across the carbon wall by diffusion controlled functionalization of precursor. The geometry of fiber cross-section was tailored by using bicomponent melt-spinning with shaped dies and controlling the melt-processing of the precursor polymer. Circular, trilobal, gear-shaped hollow fibers, and solid star-shaped carbon fibers of 0.5 - 20 um diameters, either in self-assembled bundle form, or non-bonded loose filament form, were produced by carbonizing functionalized-polyethylene fibers. Prior to carbonization, melt-spun fibers were converted to a char-forming mass by optimizing the sulfonation on polyethylene macromolecules. The fibers exhibited distinctly ordered carbon morphologies at the outside skin compared to the inner surface or fiber core. Such order in carbon microstructure can be further tuned by altering processing parameters. Partially sulfonated polyethylene-derived hollow carbon fibers exhibit 2-10 fold surface area (50-500 m2/g) compared to the solid fibers (10-25 m2/g) with pore sizes closer to the inside diameter of the filaments larger than the sizes on the outer layer. These specially functionalized carbon fibers hold promise for extraordinary performance improvements when used, for example, as composite reinforcements, catalyst support media, membranes for gas separation, CO2 sorbents, and active electrodes and current collectors for energy storage applications.

Hunt, Marcus A [ORNL; Saito, Tomonori [ORNL; Brown, Rebecca H [ORNL; Kumbhar, Amar S [University of North Carolina, Chapel Hill; Naskar, Amit K [ORNL

2012-01-01

117

Final report on the safety assessment of polyethylene.  

PubMed

Polyethylene is an ethylene polymer used for a variety of purposes in cosmetics as an abrasive, adhesive, binder or bulking agent, an emulsion stabilizer, a film former, an oral care agent, and as a nonaqueous viscosity-increasing agent. Polyethylene is also used in food packaging materials and medical products, including prosthetics. The molecular weight of Polyethylene as used in cosmetics varies over a wide range. The lowest reported molecular weight is 198 Daltons and the highest is 150,000. In any given polymer preparation, there can be a broad range of molecular weights. Cellular and tissue responses to Polyethylene, determined as part of implant biocompatibility testing, include fibrous connective tissue build-up around the implant material that varies as a function of the physical form of the implant material. Specific assays for osteoblast proliferation and collagen synthesis demonstrated a reduction as a function of exposure to Polyethylene particles that is inversely related to particle size. The effect of Polyurethane particles on monocyte-derived macrophages, however, had a stimulatory effect, prolonging the survival of these cells in culture. The LD50 for Polyethylene, with an average molecular weight of 450, in rats was > 2000 mg/kg. For Polyethylene with an average molecular weight of 655, the LD50 was > 5.0 g/kg. Toxicity testing in rats shows no adverse effects at Polyethylene (molecular weight not given) doses of 7.95 g/kg or at 1.25%, 2.50%, or 5.00% in feed for 90 days. Dermal irritation studies on rabbits in which 0.5 g of Polyethylene (average molecular weight of 450) was administered in 0.5 ml of water caused no irritation or corrosive effects; Polyethylene with an average molecular weight of 655 was a mild irritant. Polyethylene (average molecular weight of 450) did not cause dermal sensitization in guinea pigs tested with 50% Polyethylene (w/w) in arachis oil BP. Polyethylene, with a molecular weight of 450 and a molecular weight of 655, was a mild irritant when tested as a solid material in the eyes of rabbits. Rabbit eyes treated with a solution containing 13% Polyethylene beads produced minimal irritation and no corneal abrasions. No genotoxicity was found in bacterial assays. No chemical carcinogenicity has been seen in implantation studies, although particles from Polyethylene implants can induce so-called solid-state carcinogenicity, which is a physical reaction to an implanted material. Occupational case reports of ocular irritation and systemic sclerosis in workers exposed to Polyethylene have been difficult to interpret because such workers are also exposed to other irritants. Clinical testing of intrauterine devices made of Polyethylene failed to conclusively identify statistically significant adverse effects, although squamous metaplasia was observed. The Cosmetic Ingredient Review (CIR) Expert Panel did not expect significant dermal absorption and systemic exposure to large Polyethylene polymers used in cosmetics. The Panel was concerned that information on impurities, including residual catalyst and reactants from the polymerization process, was not available. The Panel considered that the monomer unit in Polyethylene polymerization is ethylene. In the United States, ethylene is 99.9% pure. The other 0.1% includes ethane, propylene, carbon dioxide, carbon monoxide, sulfur, hydrogen, acetylene, water, and oxygen. The Panel believed that the concentration of these impurities in any final polymer would be so low as to not raise toxicity issues. Safety tests of cosmetic-grade Polyethylene have consistently failed to identify any toxicity associated with residual catalyst. Although it was reported that one process used to cross-link Polyethylene with an organic peroxide, this process is not currently used. In addition, cosmetic-grade Polyethylene is not expected to contain toxic hexanes. The Panel was concerned that the only genotoxicity data available was nonmammalian, but taking this information in concert with the absence of any chemical carcinogenicity in implant studies sugges

2007-01-01

118

DSC Evidence for Microstructure and Phase Transitions in Polyethylene Melts at High Temperatures  

E-print Network

polyethylenes of types HDPE, LDPE, and LLDPE. DSC data were obtained for a range of heating and cooling rates. Also, commercial samples of low-density polyethylene (LDPE) and two linear-low-density polyethylenes

Hussein, Ibnelwaleed A.

119

76 FR 40325 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Preliminary Results...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Polyethylene Terephalate (PET) Film from South Korea,'' which will soon be released...Polyethylene Terephalate (PET) Film from South Korea,'' which will soon be released...Polyethylene Terephalate (PET) Film from South Korea,'' dated June 30, 2011...

2011-07-08

120

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

121

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

Code of Federal Regulations, 2014 CFR

...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...

2014-07-01

122

75 FR 38978 - Polyethylene Retail Carrier Bags From the People's Republic of China, Malaysia, and Thailand...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From the People's Republic of China...duty orders on polyethylene retail carrier bags (PRCBs) from the People's Republic...see also Polyethylene Retail Carrier Bags From China, Malaysia, and...

2010-07-07

123

78 FR 28192 - Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of...duty order on polyethylene retail carrier bags (PRCBs) from Thailand. The review covers...duty order is polyethylene retail carrier bags, which are currently classified...

2013-05-14

124

75 FR 36359 - Polyethylene Retail Carrier Bags From Thailand: Extension of Time Limit for Preliminary Results...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Extension of Time Limit...order on polyethylene retail carrier bags from Thailand. See Antidumping Duty Order: Polyethylene Retail Carrier Bags From Thailand, 69 FR 48204...

2010-06-25

125

76 FR 12700 - Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping...duty order on polyethylene retail carrier bags from Thailand. We gave interested parties...Polyethylene [[Page 12701

2011-03-08

126

75 FR 23673 - Polyethylene Retail Carrier Bags from Thailand: Extension of Time Limit for Preliminary Results...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821 Polyethylene Retail Carrier Bags from Thailand: Extension of Time Limit...order on polyethylene retail carrier bags from Thailand. See Antidumping Duty Order: Polyethylene Retail Carrier Bags From Thailand, 69 FR 48204...

2010-05-04

127

76 FR 30102 - Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of...duty order on polyethylene retail carrier bags (PRCBs) from Thailand. The review covers...Duty Order: Polyethylene Retail Carrier Bags From Thailand, 69 FR 48204 (August...

2011-05-24

128

76 FR 11203 - Polyethylene Retail Carrier Bags From the People's Republic of China: Rescission of Antidumping...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-570-886] Polyethylene Retail Carrier Bags From the People's Republic of China...duty order on polyethylene retail carrier bags (PRCBs) from the People's Republic...Duty Order: Polyethylene Retail Carrier Bags From the People's Republic of...

2011-03-01

129

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Review)] Polyethylene Retail Carrier Bags From China, Malaysia, and Thailand...duty orders on polyethylene retail carrier bags from China, Malaysia, and Thailand would...entitled Polyethylene Retail Carrier Bags from China, Malaysia, and...

2010-06-28

130

78 FR 76280 - Polyethylene Retail Carrier Bags From the People's Republic of China: Affirmative Preliminary...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-570-886] Polyethylene Retail Carrier Bags From the People's Republic of China...unfinished polyethylene retail carrier bags (PRCBs) from the People's Republic...Duty Order: Polyethylene Retail Carrier Bags From the People's Republic of...

2013-12-17

131

75 FR 53953 - Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of...duty order on polyethylene retail carrier bags (PRCBs) from Thailand. The review covers...Duty Order: Polyethylene Retail Carrier Bags From Thailand, 69 FR 48204 (August...

2010-09-02

132

76 FR 68137 - Polyethylene Retail Carrier Bags From Thailand: Amended Final Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Amended Final Results of...published Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping...from the Polyethylene Retail Carrier Bag Committee and its individual...

2011-11-03

133

75 FR 34699 - Polyethylene Retail Carrier Bags from Thailand: Rescission of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags from Thailand: Rescission of Antidumping...duty order on polyethylene retail carrier bags from Thailand. The period of review is...requests from the Polyethylene Retail Carrier Bag Committee and its individual...

2010-06-18

134

75 FR 23670 - Polyethylene Retail Carrier Bags from the Socialist Republic of Vietnam: Countervailing Duty Order  

Federal Register 2010, 2011, 2012, 2013, 2014

...C-552-805) Polyethylene Retail Carrier Bags from the Socialist Republic of Vietnam...duty order on polyethylene retail carrier bags (PRCBs) from the Socialist Republic of...Vietnam. See Polyethylene Retail Carrier Bags from the Socialist Republic of...

2010-05-04

135

78 FR 50376 - Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping...duty order on polyethylene retail carrier bags (PRCBs) from Thailand. The period of...1\\ See Polyethylene Retail Carrier Bags from Thailand: Preliminary Results...

2013-08-19

136

75 FR 16434 - Polyethylene Retail Carrier Bags From the Socialist Republic of Vietnam: Final Determination of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-552-806] Polyethylene Retail Carrier Bags From the Socialist Republic of Vietnam...determined that polyethylene retail carrier bags (``PRCBs'') from the Socialist Republic...the Act. See Polyethylene Retail Carrier Bags From the Socialist Republic of...

2010-04-01

137

75 FR 23667 - Antidumping Duty Orders: Polyethylene Retail Carrier Bags from Indonesia, Taiwan, and the...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Duty Orders: Polyethylene Retail Carrier Bags from Indonesia, Taiwan, and the Socialist...duty orders on polyethylene retail carrier bags (PRCBs) from Indonesia, Taiwan, and...Taiwan. See Polyethylene Retail Carrier Bags from Taiwan: Final Determination of...

2010-05-04

138

75 FR 61128 - Polyethylene Retail Carrier Bags From Malaysia: Final Results of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-557-813] Polyethylene Retail Carrier Bags From Malaysia: Final Results of Antidumping...duty order on polyethylene retail carrier bags (PRCBs) from Malaysia. The review covers...comment. See Polyethylene Retail Carrier Bags From Malaysia: Preliminary Results...

2010-10-04

139

78 FR 88 - Polyethylene Retail Carrier Bags From the People's Republic of China: Rescission of Antidumping...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-570-886] Polyethylene Retail Carrier Bags From the People's Republic of China...duty order on polyethylene retail carrier bags (PRCBs) from the People's Republic...petitioners, the Polyethylene Retail Carrier Bag Committee and its individual...

2013-01-02

140

78 FR 28194 - Polyethylene Retail Carrier Bags From the People's Republic of China: Initiation of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-570-886] Polyethylene Retail Carrier Bags From the People's Republic of China...request from The Polyethylene Retail Carrier Bag Committee and its individual members...unfinished polyethylene retail carrier bags (PRCBs) from the People's...

2013-05-14

141

75 FR 22842 - Polyethylene Retail Carrier Bags From Indonesia, Taiwan, and Vietnam  

Federal Register 2010, 2011, 2012, 2013, 2014

...Final)] Polyethylene Retail Carrier Bags From Indonesia, Taiwan, and Vietnam Determinations...Vietnam of polyethylene retail carrier bags (PRCBs), provided for in subheading...entitled Polyethylene Retail Carrier Bags from Indonesia, Taiwan, and...

2010-04-30

142

75 FR 33772 - Polyethylene Retail Carrier Bags From Malaysia: Preliminary Results of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-557-813] Polyethylene Retail Carrier Bags From Malaysia: Preliminary Results of...duty order on polyethylene retail carrier bags (PRCBs) from Malaysia. The review covers...Duty Order: Polyethylene Retail Carrier Bags From Malaysia, 69 FR 48203 (August...

2010-06-15

143

75 FR 16428 - Polyethylene Retail Carrier Bags from the Socialist Republic of Vietnam: Final Affirmative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...C-552-805] Polyethylene Retail Carrier Bags from the Socialist Republic of Vietnam...exporters of polyethylene retail carrier bags (PRCBs) from the Socialist Republic of...2009. See Polyethylene Retail Carrier Bags from the Socialist Republic of...

2010-04-01

144

77 FR 2959 - Polyethylene Retail Carrier Bags From the People's Republic of China: Rescission of Antidumping...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-570-886] Polyethylene Retail Carrier Bags From the People's Republic of China...duty order on polyethylene retail carrier bags (PRCBs) from the People's Republic...Duty Order: Polyethylene Retail Carrier Bags From the People's Republic of...

2012-01-20

145

76 FR 59999 - Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping Duty Administrative...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Results of Antidumping...duty order on polyethylene retail carrier bags from Thailand. We gave interested parties...published Polyethylene Retail Carrier Bags From Thailand: Preliminary Results...

2011-09-28

146

Correlation in the Auger spectrum of polyethylene  

SciTech Connect

The Auger spectrum of polyethylene has been obtained on an energy scale calibrated relative to the threshold of the valence band and independent of problems associated with energy calibration and charging. The spectrum has a broad, featureless shape which has been previously interpreted in terms of a perturbed self-fold of the density of states. The calibrated C(KVV) spectrum reported here, however, is shifted by at least 10 eV relative to a perturbed self-fold of the density of states. This spectral shift requires a hole-hole correlation energy of at least 10 eV if one assumes that the threshold region reflects normal Auger transitions and >10 eV if the threshold region involves shakeup processes. Similar results are observed for the class of saturated linear alkanes. This behavior is shown to be inconsistent with recently calculated spectra for polyethylene in which small values of U/sub e//sub f//sub f/ (1.2 eV for the C-C subband and 3 eV for the remaining contributions) were used to distort the self-fold of the density of states, and, moreover, inconsistent with any existing theoretical representation of Auger spectra.

Rye, R.R.

1989-05-15

147

Polyethylene nanofibres with very high thermal conductivities.  

PubMed

Bulk polymers are generally regarded as thermal insulators, and typically have thermal conductivities on the order of 0.1 W m(-1) K(-1). However, recent work suggests that individual chains of polyethylene--the simplest and most widely used polymer--can have extremely high thermal conductivity. Practical applications of these polymers may also require that the individual chains form fibres or films. Here, we report the fabrication of high-quality ultra-drawn polyethylene nanofibres with diameters of 50-500 nm and lengths up to tens of millimetres. The thermal conductivity of the nanofibres was found to be as high as approximately 104 W m(-1) K(-1), which is larger than the conductivities of about half of the pure metals. The high thermal conductivity is attributed to the restructuring of the polymer chains by stretching, which improves the fibre quality toward an 'ideal' single crystalline fibre. Such thermally conductive polymers are potentially useful as heat spreaders and could supplement conventional metallic heat-transfer materials, which are used in applications such as solar hot-water collectors, heat exchangers and electronic packaging. PMID:20208547

Shen, Sheng; Henry, Asegun; Tong, Jonathan; Zheng, Ruiting; Chen, Gang

2010-04-01

148

Recycling of irradiated high-density polyethylene  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

149

Study of the Auger line shape of polyethylene and diamond  

Microsoft Academic Search

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

M. Dayan; S. V. Pepper

1984-01-01

150

Original article Effects of polyethylene glycol in concentrate or feed  

E-print Network

in body muscle weight. Indeed, the animals fed A. cyanophylla with feed blocks with PEG and without ureaOriginal 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

Boyer, Edmond

151

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...

152

Atmospheric Dielectric Barrier Discharge Treatments of Polyethylene, Polypropylene, Polystyrene and Poly(ethylene terephthalate) for Enhanced Adhesion  

Microsoft Academic Search

A critical review of published studies investigating the dielectric barrier discharge (DBD) treatment of four polymers widely employed in the packaging sector, namely: polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET) and polystyrene (PS) is presented. The DBD treatment process operates at atmospheric pressure in air, and thereby offers a low cost method of enhancing the surface properties of polymers. The

D. Dixon; B. J. Meenan

2012-01-01

153

Pharmacologically tunable polyethylene-glycol-based cell growth substrate.  

PubMed

Biohybrid materials combining synthetic polymers with biological components are highly suited for tissue engineering in order to emulate the behavior of natural materials such as the extracellular matrix (ECM). In order to allow for an optimal cell-material interplay, the physical and biological parameters of the artificial matrix need to be dynamically remodeled during cultivation. Current tissue engineering concepts are mainly based on passive remodeling mechanisms including the degradation of the hydrogel and the release of incorporated biomolecules and therefore do not enable external adjustment of cultivation conditions. We present a novel hydrogel material that is able to serve as a cell growth matrix, whose degradation and presentation of cell-interacting biomolecules can be externally controlled by the addition of a pharmacological substance. The hydrogel is based on branched polyethylene glycol that is covalently decorated with the aminocoumarin-antibiotic switchable gyrase B protein conferring stimulus-responsive degradation. ECM properties were conferred to the hydrogels with cell attachment motifs and a general approach for the incorporation and inducible release of therapeutic biomolecules. This smart biohybrid material has the potential to serve as a next-generation tissue engineering device which allows for dynamic external adjustment of the physical and biological parameters, resulting in optimally controlled tissue formation. PMID:23684763

Gübeli, Raphael J; Laird, Dougal; Ehrbar, Martin; Ritter, Benjamin S; Steinberg, Thorsten; Tomakidi, Pascal; Weber, Wilfried

2013-09-01

154

Immobilization of silver nanoparticles on polyethylene terephthalate  

PubMed Central

Two different procedures of grafting with silver nanoparticles (AgNP) of polyethylene terephthalate (PET), activated by plasma treatment, are studied. In the first procedure, the PET foil was grafted with biphenyl-4,4?-dithiol and subsequently with silver nanoparticles. In the second one, the PET foil was grafted with silver nanoparticles previously coated with the same dithiol. X-ray photoelectron spectroscopy and electrokinetic analysis were used for characterization of the polymer surface at different modification steps. Silver nanoparticles were characterized by ultraviolet-visible spectroscopy and by transmission electron microscopy (TEM). The first procedure was found to be more effective. It was proved that the dithiol was chemically bonded to the surface of the plasma-activated PET and that it mediates subsequent grafting of the silver nanoparticles. AgNP previously coated by dithiol bonded to the PET surface much less. PMID:24994960

2014-01-01

155

Electrical conductivity effects in polyethylene terephthalate films  

NASA Astrophysics Data System (ADS)

Electrical conductivity effects in biaxially stretched polyethylene terephthalate (PET) films of 6 ?m thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 10-2-106 Hz and at temperatures higher than the glass transition temperature (˜85 °C) up to 190 °C. The formalisms of complex permittivity, electric modulus, and impedance were employed to analyze the experimental data. The results are discussed in terms of dc conductivity, conductivity current relaxation, interfacial Maxwell-Wagner-Sillars polarization, ? peak, space-charge polarization, and electrode polarization. They are compared with the predictions of models for the electrical and dielectric properties of ion-conducting polymers. The dc conductivity values determined from dc measurement, from ac conductivity plots and from complex impedance plots agree well with each other. Their temperature dependence is described by the Vogel-Tammann-Fulcher equation and classifies PET as a fragile system.

Neagu, E.; Pissis, P.; Apekis, L.

2000-03-01

156

Vacuum Outgassing of High Density Polyethylene  

SciTech Connect

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

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

2008-08-11

157

Polyethylene glycolated PAMAM dendrimers-Efavirenz conjugates  

PubMed Central

Aim: The preparation of novel PEGylated PAMAM (poly-amidoamine) dendrimers for delivery of anti-HIV drug Efavirenz is reported. Method and Materials: About 5.0 G PAMAM dendrimers are prepared by ethylene diamine core via Michael addition by divergent method. PEGylation is done by polyethylene glycol 600 using epichlorhydrin as linker. PEGylated 5.0 G PAMAM dendrimers loaded with Efavirenz (EFV) are evaluated for FTIR, DSC, SEM, drug release, and stability studies. Results and Conclusion: From the results it is proved that this method is less time consuming, inexpensive, and reproducible. Drug-release studies indicate, PEGylated 5.0 G PAMAM-EFV dendrimers have shown prolonged drug-release property. PMID:24678457

Pyreddy, Suneela; Kumar, Pandurangan Dinesh; Kumar, Palanirajan Vijayaraj

2014-01-01

158

Effect of pH on Protein Distribution in Electrospun PVA/BSA Composite Nanofibers  

E-print Network

: We examine the protein distribution within an electrospun polymer nanofiber using polyvinyl alcohol with an electrospinnable polymer such as polyvinyl alcohol (PVA) or poly(ethylene oxide) (PEO). Additionally, protein

Khan, Saad A.

159

Myocardial matrix-polyethylene glycol hybrid hydrogels for tissue engineering  

NASA Astrophysics Data System (ADS)

Similar to other protein-based hydrogels, extracellular matrix (ECM) based hydrogels, derived from decellularized tissues, have a narrow range of mechanical properties and are rapidly degraded. These hydrogels contain natural cellular adhesion sites, form nanofibrous networks similar to native ECM, and are biodegradable. In this study, we expand the properties of these types of materials by incorporating poly(ethylene glycol) (PEG) into the ECM network. We use decellularized myocardial matrix as an example of a tissue specific ECM derived hydrogel. Myocardial matrix-PEG hybrids were synthesized by two different methods, cross-linking the proteins with an amine-reactive PEG-star and photo-induced radical polymerization of two different multi-armed PEG-acrylates. We show that both methods allow for conjugation of PEG to the myocardial matrix by gel electrophoresis and infrared spectroscopy. Scanning electron microscopy demonstrated that the hybrid materials still contain a nanofibrous network similar to unmodified myocardial matrix and that the fiber diameter is changed by the method of PEG incorporation and PEG molecular weight. PEG conjugation also decreased the rate of enzymatic degradation in vitro, and increased material stiffness. Hybrids synthesized with amine-reactive PEG had gelation rates of 30 min, similar to the unmodified myocardial matrix, and incorporation of PEG did not prevent cell adhesion and migration through the hydrogels, thus offering the possibility to have an injectable ECM hydrogel that degrades more slowly in vivo. The photo-polymerized radical systems gelled in 4 min upon irradiation, allowing 3D encapsulation and culture of cells, unlike the soft unmodified myocardial matrix. This work demonstrates that PEG incorporation into ECM-based hydrogels can expand material properties, thereby opening up new possibilities for in vitro and in vivo applications.

Grover, Gregory N.; Rao, Nikhil; Christman, Karen L.

2014-01-01

160

Myocardial Matrix-Polyethylene Glycol Hybrid Hydrogels for Tissue Engineering  

PubMed Central

Similar to other protein-based hydrogels, extracellular matrix (ECM) based hydrogels, derived from decellularized tissues, have a narrow range of mechanical properties and are rapidly degraded. These hydrogels contain natural cellular adhesion sites, form nanofibrous networks similar to native ECM, and are biodegradable. In this study, we expand the properties of these types of materials by incorporating poly(ethylene glycol) (PEG) into the ECM network. We use decellularized myocardial matrix as an example of a tissue specific ECM derived hydrogel. Myocardial matrix-PEG hybrids were synthesized by two different methods, cross-linking the proteins with an amine-reactive PEG-star and photo-induced radical polymerization of two different multi-armed PEG-acrylates. We show that both methods allow for conjugation of PEG to the myocardial matrix by gel electrophoresis and infrared spectroscopy. Scanning electron microscopy demonstrated that the hybrid materials still contain a nanofibrous network similar to unmodified myocardial matrix and that the fiber diameter is changed by the method of PEG incorporation and PEG molecular weight. PEG conjugation also decreased the rate of enzymatic degradation in vitro, and increased material stiffness. Hybrids synthesized with amine-reactive PEG had gelation rates of thirty minutes, similar to the unmodified myocardial matrix, and incorporation of PEG did not prevent cell adhesion and migration through the hydrogels, thus offering the possibility to have an injectable ECM hydrogel that degrades more slowly in vivo. The photo-polymerized radical systems gelled in four minutes upon irradiation allowing for 3D encapsulation and culture of cells, unlike the soft unmodified myocardial matrix. This work demonstrates PEG incorporation into ECM-based hydrogels can expand material properties, thereby opening up new possibilities for in vitro and in vivo applications. PMID:24334615

Grover, Gregory N.; Rao, Nikhil

2014-01-01

161

Quantification of branching in model 3-arm star polyethylene Ramnath Ramachandran, Gregory Beaucage*  

E-print Network

-density polyethylene (LDPE) is typically a highly branched structure with broad distributions in branch content, branch polyethylene (HDPE). Higher levels of long-chain branching is seen in low density polyethylene (LDPE). Long properties.1-3 For instance, the presence of long-chain branches in low-density polyethylene (LDPE

Beaucage, Gregory

162

TECHNICAL GUIDANCE DOCUMENT: THE FABRICATION OF POLYETHYLENE FML FIELD SEAMS  

EPA Science Inventory

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

163

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...

164

Temperature-responsive surface-functionalized polyethylene films.  

E-print Network

??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… (more)

Ponder, Bill C.

2012-01-01

165

Extensional viscosity measurements of polyethylene using a melt flow indexer  

E-print Network

The extensional viscosity of polyethylene melts plays and important role in the processability of the resins. Extensional viscosity is important in processing operations such as film blowing, blow molding, and fiber spinning. The processability...

Moffatt, Scott Gordon

1999-01-01

166

Experimental study of rocket engine model with gaseous polyethylene fuel  

NASA Astrophysics Data System (ADS)

Experimental results for liquid rocket engine models with gaseous polyethylene fuel that is hard before its consumption are considered. The possibility of hard design element combustion in a liquid rocket engine is demonstrated.

Yemets, V. V.

167

Long term property prediction of polyethylene nanocomposites  

NASA Astrophysics Data System (ADS)

The amorphous fraction of semicrystalline polymers has long been thought to be a significant contributor to creep deformation. In polyethylene (PE) nanocomposites, the semicrystalline nature of the maleated PE compatibilizer leads to a limited ability to separate the role of the PE in the nanocomposite properties. This dissertation investigates blown films of linear low-density polyethylene (LLDPE) and its nanocomposites with montmorillonite-layered silicate (MLS). Addition of an amorphous ethylene propylene copolymer grafted maleic anhydride (amEP) was utilized to enhance the interaction between the PE and the MLS. The amorphous nature of the compatibilizer was used to differentiate the effect of the different components of the nanocomposites; namely the matrix, the filler, and the compatibilizer on the overall properties. Tensile test results of the nanocomposites indicate that the addition of amEP and MLS separately and together produces a synergistic effect on the mechanical properties of the neat PE. Thermal transitions were analyzed using differential scanning calorimetry (DSC) to determine if the observed improvement in mechanical properties is related to changes in crystallinity. The effect of dispersion of the MLS in the matrix was investigated by using a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical measurements were correlated to the dispersion of the layered silicate particles in the matrix. The nonlinear time dependent creep of the material was analyzed by examining creep and recovery of the films with a Burger model and the Kohlrausch-Williams-Watts (KWW) relation. The effect of stress on the nonlinear behavior of the nanocomposites was investigated by analyzing creep-recovery at different stress levels. Stress-related creep constants and shift factors were determined for the material by using the Schapery nonlinear viscoelastic equation at room temperature. The effect of temperature on the tensile and creep properties of the nanocomposites was analyzed by examining tensile and creep-recovery behavior of the films at temperatures in the range of 25 to -100°C. Within the measured temperature range, the materials showed a nonlinear temperature dependent response. The time-temperature superposition principle was successfully used to predict the long term behavior of LLDPE nanocomposites.

Shaito, Ali Al-Abed

168

Polyethylene/Boron Composites for Radiation Shielding Applications  

NASA Astrophysics Data System (ADS)

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.

Harrison, Courtney; Burgett, Eric; Hertel, Nolan; Grulke, Eric

2008-01-01

169

Rectal absorption of metronidazole from polyethylene glycol suppositories.  

PubMed

The rectal absorption of metronidazole from an aqueous suspension, a fatty suppository and three different polyethylene glycol suppositories was studied in healthy volunteers and compared with absorption from an oral solution. Rectal absorption was found to be rather slow for all suppositories. Of all rectal dosage forms, the polyethylene glycol suppositories gave the highest peak plasma levels and the highest relative bioavailability. Compared with oral administration, a relative bioavailability of 80% could be obtained. PMID:6709483

Vromans, H; Moolenaar, F; Visser, J; Meijer, D K

1984-02-24

170

Polyethylene/Boron Composites for Radiation Shielding Applications  

SciTech Connect

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.

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

171

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

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 ...

Yazdani, Iman

2007-01-01

172

Tribological characteristics of polyethylene glycol (PEG) as a lubricant for wear resistance of ultra-high-molecular-weight polyethylene (UHMWPE ) in artificial knee join.  

PubMed

For the longevity of total knee joint prostheses, we have developed an artificial lubricant using polyethylene glycol (PEG) for the prevention of wear of ultra-high-molecular-weight polyethylene (UHMWPE). In the present study, the lubricative function of this PEG lubricant was evaluated by a wear test using Co-Cr alloy and UHMWPE counter surface samples. As a result, human synovial fluid including the PEG lubricant showed good result regarding the wear volume and a worn surface of UHMWPE. Considering its lubrication mechanism, it is suspected that interaction between the PEG molecules and the proteins in synovial fluid was involved. Since PE molecules are also organic compounds having a hydroxyl group at one or both ends, the albumin and PEG molecule complex would have bound more strongly to the metal oxide surface and UHMWPE surfaces might enhance and stabilize the lubricating film between the contact surfaces under the boundary lubrication. This study suggests that PEG lubricant as an intra-articular viscous supplement has the potential to prevent wear of UHMWPE by mixing with synovial fluid and to contribute to the longevity of knee joint prostheses. PMID:25016174

Kobayashi, Masanori; Koide, Takayuki; Hyon, Suong-Hyu

2014-10-01

173

Poly(ethylene oxide) surfactant polymers  

PubMed Central

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

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

2005-01-01

174

Release characteristics of implantable cylindrical polyethylene matrices.  

PubMed

The geometrical relationship between a hemisphere and a cylinder has been investigated for controlled-release systems. The relationship was tested by comparing dissolution results with results from mathematical calculation based on the principles of diffusion for matrix systems. A procedure has been developed for producing implantable, cylindrical, low-density polyethylene matrices, uncoated or coated with a thin impermeable film and a thick paraffin layer except for a hole on the flat faces of the cylinder. Drug matrices were prepared from a blend of sodium salicylate and polymer compressed in an appropriately designed stainless-steel mould at 150 degrees C. Differential scanning calorimetry revealed that no decomposition product was formed in the matrix. When the surface area and the number of holes is increased, drug release also increases. When density is increased, however, drug release decreases significantly. Zero-order drug release was obtained from high-density covered one-hole and two-hole matrices. The diffusion coefficient was calculated as 0.067 day-1. The study suggested that true zero-order drug release could be obtained by drug diffusion from a hole, rather than from geometric shapes in the matrix systems. In addition, for constant release the diffusion area has to increase by approximately 25 mm2 every day, compared to the area of the previous day, because the diffusion distance increases logarithmically. PMID:9231336

Ertan, G; Karasulu, E; Demirta?, D; Arici, M; Güneri, T

1997-03-01

175

Polyethylene Terephthalate May Yield Endocrine Disruptors  

PubMed Central

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

Sax, Leonard

2010-01-01

176

Entangled Diffusion in Binary Polyethylene Blends  

NASA Astrophysics Data System (ADS)

In continuing support of our Monte-Carlo simulations of self-diffusion in polymers near the entanglement transition we have used the proton pulsed-gradient spin-echo NMR method to augment our previous measurements in n-alkane and polyethylene (PE) melts by studying three series of blends at T = 150 deg. C across the full concentration (c) range. Blends were based on M = 33k PE and contained either n-C50 alkane, M = 1.8k PE, or M = 6.7k PE. The results are again in agreement with our earlier theoretical synthesis(1) involving a smooth transition from Rouse to reptational behavior involving constraint release, accounting for free-volume and tube-constraint host effects which depend on T, M, and c. Tube dilation effects are assumed contained in the constraint-release mechanism; contour-length fluctuations are not considered to affect center-of-mass diffusion. Contrary to our earlier findings, unentangled n-alkanes (n-C50 and even n-C12) do not appear to act as diluents able to delay the onset of entanglements in blends with PE. (1) E. von Meerwall, et al., J. Chem. Phys. 111, 750 (1999); E. von Meerwall, et al., Polymer Prepr. 44, 287 (2003).

Dirama, N.; Mattice, W. L.; von Meerwall, E.

2003-10-01

177

Reaction kinetics of hydrothermal depolymerization of poly(ethylene naphthalate), poly(ethylene terephthalate), and polycarbonate with aqueous ammonia solution  

Microsoft Academic Search

Poly(ethylene naphthalate) (PEN), poly(ethylene terephthalate) (PET) and poly(carbonate) (PC) were depolymerized in a semi-batch reactor with a 0.6M aqueous ammonia solution under hydrothermal conditions, at 433–553K and 10MPa, compared with aqueous alkaline (NaOH and KOH) solutions and water alone. The polymers studied were almost completely converted into monomers in an aqueous ammonia solution as well as aqueous NaOH and KOH

Risa Arai; Kentaro Zenda; Kohei Hatakeyama; Kazuko Yui; Toshitaka Funazukuri

2010-01-01

178

Kinetic approach to radiation-induced grafting in the polyethylene-styrene system. IV. Comparison between high density polyethylene and low density polyethylene. [Gamma radiation  

SciTech Connect

The investigation method reported in earlier articles was applied to preirradiation methods of the reaction of low-density polyethylene (LDPE) in liquid and vapor and compared with high-density polyethylene (HDPE). Monomer concentrations during reactions and monomer feed rates were determined gravimetrically. Increasing patterns of the degree of grafting were obtained and compared. Monomer concentration during the reactions was lower in LDPE than HDPE and radical decay was more rapid in LDPE. A model calculation was applied to this experiment and a schematic explanation was attempted. The differences between the reaction mechanisms of HDPE and LDPE are explained.

Imai, M.

1981-07-01

179

Engineering Poly(ethylene glycol) Materials to Promote Cardiogenesis  

NASA Astrophysics Data System (ADS)

Heart failure is one of the leading causes of death worldwide, and the current costs of treatment put a significant economic burden on our societies. After an infarction, fibrotic tissue begins to form as part of the heart failure cascade. Current options to slow this process include a wide range of pharmaceutical agents, and ultimately the patient may require a heart transplant. Innovative treatment approaches are needed to bring down costs and improve quality of life. The possibility of regenerating or replacing damaged tissue with healthy cardiomyocytes is generating considerable excitement, but there are still many obstacles to overcome. First, while cell injections into the myocardium have demonstrated slight improvements in cardiac function, the actual engraftment of transplanted cells is very low. It is anticipated that improving engraftment will boost outcomes. Second, cellular differentiation and reprogramming protocols have not yet produced cells that are identical to adult cardiomyocytes, and immunogenicity continues to be a problem despite the advent of autologously derived induced pluripotent stem cells. This dissertation will explore biomaterials approaches to addressing these two obstacles. Tissue engineering scaffolds may improve cell engraftment by providing bioactive factors, preventing cell anoikis, and reducing cell washout by blood flow. Poly(ethylene glycol) (PEG) is often used as a coating to reduce implant rejection because it is highly resistant to protein adsorption. Because fibrosis of a material in contact with the myocardium could cause arrhythmias, PEG materials are highly relevant for cardiac tissue engineering applications. In Chapter 2, we describe a novel method for crosslinking PEG microspheres around cells to form a scaffold for tissue engineering. We then demonstrate that HL-1 cardiomyocyte viability and phenotype are retained throughout the fabrication process and during the first 7 weeks of culture. In the third chapter of the dissertation, we demonstrate that the use of PEG cell culture substrates can improve efficiency of direct reprogramming from fibroblasts to cardiomyocytes for cell transplantation. Standard tissue culture plastic adsorbs proteins from the cell media, increasing experimental variability via non-specific signaling. Because of its protein resistant properties, PEG provides cells with highly specific signals. In addition to improving the efficiency, we found that presentation of RGD peptides stimulated proliferation during reprogramming. Combined, the improvements enabled us to approximately double the number of cardiomyocytes produced by the protocol. In Chapter 4, we explore the effects of 3D culture on the direct reprogramming protocol described in Chapter 3. We demonstrate that the variables involved in 3D culture, including scaffold material, diffusion, cellular remodeling, and scaffold topography, have significant effects on reprogramming efficiency. This chapter provides the groundwork for future studies developing 3D microenvironments for efficient and scalable reprogramming to cardiomyocytes.

Smith, Amanda Walker

180

Study on ternary low density polyethylene/linear low density polyethylene/thermoplastic starch blend films.  

PubMed

In this work, low-density polyethylene/linear low-density polyethylene/thermoplastic starch (LDPE/LLDPE/TPS) films are prepared with the aim of obtaining environmentally friendly materials containing high TPS content with required packaging properties. Blending of LDPE/LLDPE (70/30wt/wt) with 5-20wt% of TPS and 3wt% of PE-grafted maleic anhydride (PE-g-MA) is performed in a twin-screw extruder, followed by the blowing process. Differential scanning calorimetric results indicate starch has more pronounced effect on crystallization of LLDPE than LDPE. Scanning electron micrograph shows a fairly good dispersion of TPS in PE matrices. Fourier transfer infrared spectra confirm compatibility between polymers using PE-g-MA as the compatibilizer. Storage modulus, loss modulus and complex viscosity increase with incorporation of starch. Tensile strength and elongation-at-break decrease from 18 to 10.5MPa and 340 to 200%, respectively when TPS increases from 5 to 20%. However, the required mechanical properties for packaging applications are attained when 15wt% starch is added, as specified in ASTM D4635. Finally 12% increase in water uptake is achieved with inclusion of 15wt% starch. PMID:25563952

Sabetzadeh, Maryam; Bagheri, Rouhollah; Masoomi, Mahmood

2015-03-30

181

Chemistry for peptide and protein PEGylation  

Microsoft Academic Search

Poly(ethylene glycol) (PEG) is a highly investigated polymer for the covalent modification of biological macromolecules and surfaces for many pharmaceutical and biotechnical applications. In the modification of biological macromolecules, peptides and proteins are of extreme importance. Reasons for PEGylation (i.e. the covalent attachment of PEG) of peptides and proteins are numerous and include shielding of antigenic and immunogenic epitopes, shielding

M. J. Roberts; M. D. Bentley; J. M. Harris

2002-01-01

182

Delivery of sphingosine 1-phosphate from poly(ethylene glycol) hydrogels  

PubMed Central

While protein growth factors promote therapeutic angiogenesis, delivery of lipid factors such as sphingosine 1-phosphate (S1P) may provide better stabilization of newly formed vessels. We developed a biomaterial for the controlled delivery of S1P, a bioactive lipid released from activated platelets. Multi-arm poly(ethylene glycol)-vinyl sulfone was crosslinked with albumin, a lipid-transporting protein, to form hydrogels. The rate of S1P release from the materials followed Fickian kinetics and was dependent upon the presence of lipid carriers in the release solution. Delivery of S1P from RGD-modified hydrogels increased the cell migration speed of endothelial cells growing on the materials. The materials also induced angiogenesis in the chorioallantoic membrane assay. Our data demonstrate that the storage and release of lipid factors provides a new route for the induction of angiogenesis by artificial materials. PMID:16602758

Wacker, Bradley K.; Scott, Evan A.; Kaneda, Megan M.; Alford, Shannon K.; Elbert, Donald L.

2008-01-01

183

Activation of Cytosolic Pyruvate Kinase by Polyethylene Glycol.  

PubMed

Homogeneous cytosolic pyruvate kinase from endosperm of germinating castor oil (Ricinus communis L. cv Hale) seeds was potently activated by polyethylene glycol. The addition of 5% (w/v) polyethylene glycol to the pyruvate kinase reaction mixture caused a 2.6-fold increase in maximal velocity and 12.5- and 2-fold reductions in Km values for phosphoenolpyruvate and ADP, respectively. Glycerol, ethylene glycol, and bovine serum albumin also enhanced pyruvate kinase activity, albeit to a lesser extent than polyethylene glycol. The addition of 5% (w/v) polyethylene glycol to the elution buffer during high-performance gel filtration chromatography of purified cytosolic pyruvate kinase helped to stabilize the active heterotetrameric native structure of the enzyme. A higher degree of inhibition by MgATP, but lower sensitivity to the inhibitors 3-phosphoglycerate and fructose- 1,6-bisphosphate, was also observed in the presence of 5% (w/v) polyethylene glycol. It is concluded that (a) plant cytosolic pyruvate kinase activity and regulation, like that of other regulatory pyruvate kinases, is modified by extreme dilution in the assay medium, probably as a result of deaggregation of the native tetrameric enzyme, and (b) ATP is probably the major metabolic effector of germinating castor endosperm cytosolic pyruvate kinase in vivo. PMID:12231936

Podesta, F. E.; Plaxton, W. C.

1993-09-01

184

Modeling uptake of hydrophobic organic contaminants into polyethylene passive samplers.  

PubMed

Single-phase passive samplers are gaining acceptance as a method to measure hydrophobic organic contaminant (HOC) concentration in water. Although the relationship between the HOC concentration in water and passive sampler is linear at equilibrium, mass transfer models are needed for nonequilibrium conditions. We report measurements of organochlorine pesticide diffusion and partition coefficients with respect to polyethylene (PE), and present a Fickian approach to modeling HOC uptake by PE in aqueous systems. The model is an analytic solution to Fick's second law applied through an aqueous diffusive boundary layer and a polyethylene layer. Comparisons of the model with existing methods indicate agreement at appropriate boundary conditions. Laboratory release experiments on the organochlorine pesticides DDT, DDE, DDD, and chlordane in well-mixed slurries support the model's applicability to aqueous systems. In general, the advantage of the model is its application in the cases of well-agitated systems, low values of polyethylene-water partioning coefficients, thick polyethylene relative to the boundary layer thickness, and/or short exposure times. Another significant advantage is the ability to estimate, or at least bound, the needed exposure time to reach a desired CPE without empirical model inputs. A further finding of this work is that polyethylene diffusivity does not vary by transport direction through the sampler thickness. PMID:25607420

Thompson, Jay M; Hsieh, Ching-Hong; Luthy, Richard G

2015-02-17

185

Preferential hydration and the exclusion of cosolvents from protein surfaces  

E-print Network

to the structure of the aqueous solution which surrounds the protein.8,9,11 Indeed, assuming that water of proteins in aqueous polyethylene glycol PEG solutions can be ex- plained from the steric exclusion of PEGsPreferential hydration and the exclusion of cosolvents from protein surfaces Seishi Shimizua

Shimizu, Seishi

186

75 FR 75454 - Polyethylene Retail Carrier Bags From Thailand: Extension of Time Limit for the Final Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Extension of Time Limit for...antidumping duty order on polyethylene retail carrier bags from Thailand. See Polyethylene Retail Carrier Bags From Thailand: Preliminary Results of...

2010-12-03

187

75 FR 14569 - Polyethylene Retail Carrier Bags from Taiwan: Final Determination of Sales at Less Than Fair Value  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-583-843] Polyethylene Retail Carrier Bags from Taiwan: Final Determination of Sales...imports of polyethylene retail carrier bags (PRCBs) from Taiwan are being, or are...Taiwan. See Polyethylene Retail Carrier Bags From Taiwan: Preliminary...

2010-03-26

188

78 FR 69817 - Polyethylene Retail Carrier Bags From Thailand: Final Court Decision and Amended Final Results of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Court Decision and...margin for polyethylene retail carrier bags (PRCBs) from Thailand produced or exported...2\\ See Polyethylene Retail Carrier Bags from Thailand: Final Results and...

2013-11-21

189

75 FR 16431 - Polyethylene Retail Carrier Bags From Indonesia: Final Determination of Sales at Less Than Fair...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-560-822] Polyethylene Retail Carrier Bags From Indonesia: Final Determination of...imports of polyethylene retail carrier bags (PRCBs) from Indonesia are being, or...Department published Polyethylene Retail Carrier Bags from Indonesia: Preliminary...

2010-04-01

190

Initial Stages of Pyrolysis of Polyethylene  

NASA Astrophysics Data System (ADS)

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.

Popov, Konstantin V.

191

Injectable silk-polyethylene glycol hydrogels.  

PubMed

Silk hydrogels for tissue repair are usually pre-formed via chemical or physical treatments from silk solutions. For many medical applications, it is desirable to utilize injectable silk hydrogels at high concentrations (>8%) to avoid surgical implantation and to achieve slow in vivo degradation of the gel. In the present study, injectable silk solutions that formed hydrogels in situ were generated by mixing silk with low-molecular-weight polyethylene glycol (PEG), especially PEG300 and 400 (molecular weight 300 and 400gmol(-1)). Gelation time was dependent on the concentration and molecular weight of PEG. When the concentration of PEG in the gel reached 40-45%, gelation time was less than 30min, as revealed by measurements of optical density and rheological studies, with kinetics of PEG400 faster than PEG300. Gelation was accompanied by structural changes in silk, leading to the conversion from random coil in solution to crystalline ?-sheets in the gels, based on circular dichroism, attenuated total reflection Fourier transform infrared spectroscopy and X-ray diffraction. The modulus (127.5kPa) and yield strength (11.5kPa) determined were comparable to those of sonication-induced hydrogels at the same concentrations of silk. The time-dependent injectability of 15% PEG-silk hydrogel through 27G needles showed a gradual increase of compression forces from ?10 to 50N within 60min. The growth of human mesenchymal stem cells on the PEG-silk hydrogels was hindered, likely due to the presence of PEG, which grew after a 5day delay, presumably while the PEG solubilized away from the gel. When 5% PEG-silk hydrogel was subcutaneously injected in rats, significant degradation and tissue in-growth took place after 20days, as revealed by ultrasound imaging and histological analysis. No significant inflammation around the gel was observed. The features of injectability, slow degradation and low initial cell attachment suggests that these PEG-silk hydrogels are of interest for many biomedical applications, such as anti-fouling and anti-adhesion. PMID:25449912

Wang, Xiaoqin; Partlow, Benjamin; Liu, Jian; Zheng, Zhaozhu; Su, Bo; Wang, Yansong; Kaplan, David L

2015-01-15

192

Space radiation transport properties of polyethylene-based composites  

NASA Technical Reports Server (NTRS)

Composite materials that can serve as both effective shielding materials against cosmic-ray and energetic solar particles in deep space, as well as structural materials for habitat and spacecraft, remain a critical and mission enabling component in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density, coupled with high hydrogen content. Polyethylene-fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at the NASA Marshall Space Flight Center and tested against a 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

Kaul, R. K.; Barghouty, A. F.; Dahche, H. M.

2004-01-01

193

Polyethylene Wear in Retrieved Reverse Total Shoulder Components  

PubMed Central

Background Reverse total shoulder arthroplasty has been used to treat rotator cuff tear arthropathy, proximal humeral fractures and for failed conventional total shoulder prostheses. It has been suggested that polyethylene wear is potentially higher in reverse shoulder replacements than in conventional shoulder replacements. The modes and degree of polyethylene wear have not been completely elucidated. The purpose of this study was to evaluate polyethylene wear patterns in seven specimens retrieved at revision arthroplasty and identify factors that may be associated with increased wear. Methods Reverse total shoulder components were retrieved from 7 patients during revision arthroplasty for loosening and/or pain. Pre-operative glenoid tilt and placement, and scapular notching were evaluated using pre-operative radiographs. Polyethylene wear was evaluated using microCT and optical microscopy. Results Wear on the rim of the polyethylene humeral cup, was identified on all retrieved components. The extent of rim wear varied from a penetration depth of 0.1 to 4.7 mm. We could not demonstrate a correlation between scapular notching and rim wear. However, rim wear was more extensive when the inferior screw had made contact with the liner. Metal on metal wear between the humeral component and the inferior screw of one component was also observed. Wear of the intended bearing surface was minimal. Discussion Rim damage was the predominant cause of polyethylene wear in our retrieved specimens. Direct contact between the humeral component and inferior metaglene screws is concerning because this could lead to accelerated UHMWPE wear and also induce mechanical loosening of the glenoid component. PMID:21724419

Day, Judd S; MacDonald, Daniel W; Olsen, Madeline; Getz, Charles; Williams, Gerald R; Kurtz, Steven M

2011-01-01

194

Unexpected shish-kebab structure in a sheared polyethylene melt.  

PubMed

Scanning electron micrographs of a solvent-extracted sheared polyethylene (PE) blend revealed, for the first time, an unexpected shish-kebab structure with multiple shish. The blend contained 2 wt % of crystallizing ultrahigh molecular weight polyethylene (UHMWPE) and 98 wt % of noncrystallizing PE matrix. The formation of multiple shish was attributed to the coil-stretch transition occurring in sections of UHMWPE chains. Synchrotron x-ray data provided clear evidence of the hypothesis that multiple shish originate from stretched chain sections and kebabs originate from coiled chain sections, following a diffusion-controlled crystallization process. PMID:15903890

Hsiao, Benjamin S; Yang, Ling; Somani, Rajesh H; Avila-Orta, Carlos A; Zhu, Lei

2005-03-25

195

Unexpected Shish-Kebab Structure in a Sheared Polyethylene Melt  

NASA Astrophysics Data System (ADS)

Scanning electron micrographs of a solvent-extracted sheared polyethylene (PE) blend revealed, for the first time, an unexpected shish-kebab structure with multiple shish. The blend contained 2 wt % of crystallizing ultrahigh molecular weight polyethylene (UHMWPE) and 98 wt % of noncrystallizing PE matrix. The formation of multiple shish was attributed to the coil-stretch transition occurring in sections of UHMWPE chains. Synchrotron x-ray data provided clear evidence of the hypothesis that multiple shish originate from stretched chain sections and kebabs originate from coiled chain sections, following a diffusion-controlled crystallization process.

Hsiao, Benjamin S.; Yang, Ling; Somani, Rajesh H.; Avila-Orta, Carlos A.; Zhu, Lei

2005-03-01

196

Molecularly uniform poly(ethylene glycol) certified reference material  

NASA Astrophysics Data System (ADS)

A certified reference material (CRM) for poly(ethylene glycol) with no distribution in the degree of polymerization was developed. The degree of polymerization of the CRM was accurately determined to be 23. Supercritical fluid chromatography (SFC) was used to separate the molecularly uniform polymer from a standard commercial sample with wide polydispersity in its degree of polymerization. Through the use of a specific fractionation system coupled with SFC, we are able to obtain samples of poly(ethylene glycol) oligomer with exact degrees of polymerization, as required for a CRM produced by the National Metrology Institute of Japan.

Takahashi, Kayori; Matsuyama, Shigetomo; Kinugasa, Shinichi; Ehara, Kensei; Sakurai, Hiromu; Horikawa, Yoshiteru; Kitazawa, Hideaki; Bounoshita, Masao

2015-02-01

197

Short chain polyethylene glycols unusually assist thermal unfolding of human serum albumin.  

PubMed

In the present study we have investigated the thermal stability of the globular transport protein human serum albumin (HSA), in the presence of two small chain polyethylene glycols (namely PEG 200 and PEG 400). Both near- and far-UV circular dichroism (CD) study reveal that addition of PEG moderately increases the ?-helical content of the protein without abruptly changing its tertiary structure. The hydration structure at the protein surface experiences a notable change at 30% PEG (v/v) concentration as evidenced from compressibility and dynamic light scattering (DLS) measurements. Thermal denaturation of HSA in the presence of PEG has been studied by CD and fluorescence spectroscopy using the intrinsic fluorophore tryptophan and it has been found that addition of PEG makes the protein more prone towards unfolding, which is in contrary to what has been observed in case of larger molecular weight polymers. The energetics of the thermal unfolding process has been obtained using differential scanning calorimetry (DSC) measurements. Our study concludes that both the indirect excluded volume principle as well as interaction of the polymer at the protein surface is responsible for the observed change of the unfolding process. PMID:24911290

Samanta, Nirnay; Mahanta, Debasish Das; Hazra, Soumitra; Kumar, Gopinatha Suresh; Mitra, Rajib Kumar

2014-09-01

198

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

Federal Register 2010, 2011, 2012, 2013, 2014

...administrative review under the countervailing duty (CVD) order on polyethylene terephthalate film...CONTACT: Elfi Blum or Toni Page, AD/CVD Operations, Office 6, Import Administration...Preliminary Results of Countervailing Duty (CVD) Administrative Review: Polyethylene...

2013-08-07

199

76 FR 26241 - Polyethylene Retail Carrier Bags From Thailand: Extension of Time Limit for Preliminary Results...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Extension of Time Limit for Preliminary Results...of the antidumping duty order on polyethylene retail carrier bags from Thailand for the period August 1, 2009, through July...

2011-05-06

200

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration A-557-813 Polyethylene Retail Carrier Bags From Malaysia: Extension of Time Limit for Preliminary Results...of the antidumping duty order on polyethylene retail carrier bags from Malaysia for the period August 1, 2008, through July...

2010-05-07

201

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

E-print Network

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

Gruner, Sol M.

202

Complement activation on poly(ethylene oxide)-like RFGD-deposited surfaces  

PubMed Central

Non-specific protein adsorption, particularly fibrinogen (Fg), is thought to be an initiating step in the foreign body response (FBR) to biomaterials by promoting phagocyte attachment. In previous studies, we therefore prepared radio frequency glow discharge (RFGD) polyethylene oxide (PEO)-like tetraglyme coatings (CH3O(CH2CH2O)4CH3) adsorbing less than 10 ng/cm2 Fg and showed that they had the expected low monocyte adhesion in vitro. However, when these were implanted in vivo, many adherent inflammatory cells and a fibrous capsule were found, suggesting the role of alternative proteins, such as activated complement proteins, in the FBR to these materials. We therefore investigated complement interactions with the tetraglyme surfaces. First, because of its well known role in complement C3 activation, we measured the hydroxyl group (-OH) content of tetraglyme, but found it to be very low. Second, we measured C3 adsorption to tetraglyme from plasma. Low amounts of C3 adsorbed on tetraglyme, though it displayed higher binding strength than the control surfaces. Finally, complement activation was determined by measuring C3a and SC5b-9 levels in serum after incubating with tetraglyme, as well as other surfaces that served as positive and negative controls, namely poly(vinyl alcohol) hydrogels, Silastic sheeting, and poly(ethylene glycol) self-assembled monolayers with different end groups. Despite displaying low hydroxyl group concentration, relatively high C3a and SC5b-9 levels were found in serum exposed to tetraglyme, similar to the values due to our positive control, PVA. Our results support the conclusion that complement activation by tetraglyme is a possible mechanism involved in the FBR to these biomaterials. PMID:21105163

Szott, Luisa Mayorga; Stein, M. Jeanette; Ratner, Buddy D.; Horbett, Thomas A.

2010-01-01

203

Variations in polyethylene glycol brands and their influence on the preparation process of hydrogel microspheres.  

PubMed

Hydrogel microspheres, e.g. for the use as protein carriers, can be prepared without the use of organic solvents via an emulsified aqueous two-phase system (ATPS) that is based on two immiscible polymer solutions. The type and concentration of the polymers can affect the ATPS and finally the distribution of incorporated drugs between the aqueous phases. For the preparation of hydrogel microspheres based on hydroxyethyl starch-hydroxyethyl methacrylate (HES-HEMA), hydroxyethyl starch-methacrylate (HES-MA), and hydroxyethyl starch-polyethylene glycol methacrylate (HES-P(EG)6MA), polyethylene glycol 12,000 (PEG 12,000) was used as second polymer. The particle size distribution and encapsulation efficiency of the microspheres depended dramatically on the type of PEG 12,000 that was used in the second phase of the ATPS. Analysis of different PEG 12,000 brands by various methods revealed differences in the salt composition and molecular weight distribution of the polymers which can explain the effects on the production process. The results illustrate that the range of product specifications may not always be tight enough to avoid variability in pharmaceutical processes like the preparation of hydrogel microspheres by an aqueous two-phase preparation process. PMID:23567486

Wöhl-Bruhn, Stefanie; Bertz, Andreas; Kuntsche, Judith; Menzel, Henning; Bunjes, Heike

2013-11-01

204

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

DOEpatents

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.

Salyer, Ival O. (Dayton, OH)

1987-01-01

205

DELIVERY OF THERAPEUTIC PROTEINS  

PubMed Central

The safety and efficacy of protein therapeutics are limited by three interrelated pharmaceutical issues, in vitro and in vivo instability, immunogenicity and shorter half-lives. Novel drug modifications for overcoming these issues are under investigation and include covalent attachment of poly(ethylene glycol) (PEG), polysialic acid, or glycolic acid, as well as developing new formulations containing nanoparticulate or colloidal systems (e.g. liposomes, polymeric microspheres, polymeric nanoparticles). Such strategies have the potential to develop as next generation protein therapeutics. This review includes a general discussion on these delivery approaches. PMID:20049941

Pisal, Dipak S.; Kosloski, Matthew P.; Balu-Iyer, Sathy V.

2009-01-01

206

On the fracture characteristics of impact tested high density polyethylene–calcium carbonate nanocomposites  

Microsoft Academic Search

The mechanical response of calcium carbonate-reinforced high density polyethylene nanocomposite is investigated and the behavior compared with the unreinforced polyethylene processed under similar conditions. The reinforcement of high density polyethylene with nanocalcium carbonate retains adequately high strength in the temperature range of ?40 to +20°C. The positive influence of reinforcement on the impact strength is reflected in the fracture characteristics

C. Deshmane; Q. Yuan; R. D. K. Misra

2007-01-01

207

77 FR 25684 - Polyethylene Retail Carrier Bags From Thailand: Rescission of Antidumping Duty Administrative Review  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Rescission of Antidumping...duty order on polyethylene retail carrier bags from Thailand. The period of review is...duty order on polyethylene retail carrier bags from Thailand. See Initiation of...

2012-05-01

208

78 FR 46319 - Polyethylene Retail Carrier Bags From Taiwan: Initiation of Anti-Circumvention Inquiry on...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-583-843] Polyethylene Retail Carrier Bags From Taiwan: Initiation of Anti- Circumvention...request from The Polyethylene Retail Carrier Bag Committee and its individual members PCL...unfinished polyethylene retail carrier bags (PRCBs) on a roll from Taiwan are...

2013-07-31

209

21 CFR 178.3750 - Polyethylene glycol (mean molecular weight 200-9,500).  

Code of Federal Regulations, 2010 CFR

... Polyethylene glycol (mean molecular weight 200-9,500). 178.3750 Section... Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol...oxide and water with a mean molecular weight of 200 to 9,500. (b) It...

2010-04-01

210

21 CFR 178.3750 - Polyethylene glycol (mean molecular weight 200-9,500).  

Code of Federal Regulations, 2011 CFR

... Polyethylene glycol (mean molecular weight 200-9,500). 178.3750 Section... Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol...oxide and water with a mean molecular weight of 200 to 9,500. (b) It...

2011-04-01

211

Creep Analysis of Bamboo High-Density Polyethylene Composites: Effect of Interfacial Treatment and Fiber  

E-print Network

of bamboo fiber high-density polyethylene (BF/HDPE) composites was investigated. For single modifier systems used to modify bamboo fiber high-density polyethylene (BF/HDPE) composites. Among them, PECreep Analysis of Bamboo High-Density Polyethylene Composites: Effect of Interfacial Treatment

212

Wood plastic composites based on microfibrillar blends of high density polyethylene/poly(ethylene terephthalate)  

E-print Network

Wood plastic composites based on microfibrillar blends of high density polyethylene January 2010 Keywords: Wood plastic composites Poly(ethylene terephthalate) Polyethylene Extrusion a b into wood plastic composites through a two-step reactive extrusion technology. Wood flour was added into pre

213

Thermal rectification at silicon-amorphous polyethylene interface Ming Hu,1,a  

E-print Network

Thermal rectification at silicon-amorphous polyethylene interface Ming Hu,1,a Pawel Keblinski,1,b heat currents. We estimate that in the limit of large heat currents, the silicon-amorphous polyethylene by amorphous polymer polyethylene PE and silicon crystal. We will also show that the mecha- nism governing

Li, Baowen

214

Polyethylene glycol-coupled IGF1 delays motor function defects in a mouse model of spinal muscular atrophy with respiratory distress type 1.  

PubMed

Spinal muscular atrophy with respiratory distress type 1 is a neuromuscular disorder characterized by progressive weakness and atrophy of the diaphragm and skeletal muscles, leading to death in childhood. No effective treatment is available. The neuromuscular degeneration (Nmd(2J)) mouse shares a crucial mutation in the immunoglobulin mu-binding protein 2 gene (Ighmbp2) with spinal muscular atrophy with respiratory distress type 1 patients and also displays some basic features of the human disease. This model serves as a promising tool in understanding the complex mechanisms of the disease and in exploring novel treatment modalities such as insulin-like growth factor 1 (IGF1) which supports myogenic and neurogenic survival and stimulates differentiation during development. Here we investigated the treatment effects with polyethylene glycol-coupled IGF1 and its mechanisms of action in neurons and muscles. Polyethylene glycol-coupled IGF1 was applied subcutaneously every second day from post-natal Day 14 to post-natal Day 42 and the outcome was assessed by morphology, electromyography, and molecular studies. We found reduced IGF1 serum levels in Nmd(2J) mice 2 weeks after birth, which was normalized by polyethylene glycol-coupled IGF1 treatment. Nmd(2J) mice showed marked neurogenic muscle fibre atrophy in the gastrocnemius muscle and polyethylene glycol-coupled IGF1 treatment resulted in muscle fibre hypertrophy and slowed fibre degeneration along with significantly higher numbers of functionally active axonal sprouts. In the diaphragm with predominant myogenic changes a profound protection from muscle fibre degeneration was observed under treatment. No effects of polyethylene glycol-coupled IGF1 were monitored at the level of motor neuron survival. The beneficial effects of polyethylene glycol-coupled IGF1 corresponded to a marked activation of the IGF1 receptor, resulting in enhanced phosphorylation of Akt (protein kinase B) and the ribosomal protein S6 kinase in striated muscles and spinal cord from Nmd(2J) mice. Based on these findings, polyethylene glycol-coupled IGF1 may hold promise as a candidate for future treatment trials in human patients with spinal muscular atrophy with respiratory distress type 1. PMID:24681663

Krieger, Frank; Elflein, Nicole; Saenger, Stefanie; Wirthgen, Elisa; Rak, Kristen; Frantz, Stefan; Hoeflich, Andreas; Toyka, Klaus V; Metzger, Friedrich; Jablonka, Sibylle

2014-05-01

215

Long-term performance of cables based on chlorosulphonated polyethylene  

Microsoft Academic Search

Cables based on chlorosulphonated polyethylene were aged at different temperatures between 120 and 200 °C and their conditions were assessed by mechanical methods: micro-indenter and tensile testing. Some of the cables were not aged prior to the oven ageing whereas other cables had been exposed to almost 25 years of service at controlled temperatures (30–54 °C) and atmospheres (nitrogen and

M. J. Sandelin; U. W. Gedde

2004-01-01

216

Long Chain Branching in Polyethylene from the Phillips Chromium Catalyst  

Microsoft Academic Search

Supported chromium oxide polymerization catalysts can impart significant levels of long chain branching (LCB) to polyethylene made in a slurry process. LCB often dominates the rheological behavior of the polymer, and is thus responsible for the performance of many HDPE grades during commercial molding operations. LCB is difficult to accurately measure but its presence can be inferred from the visco?elastic

M. P. McDaniel; D. C. Rohlfing; E. A. Benham

2003-01-01

217

Practical applications of modified poly(ethylene oxide) networks  

Microsoft Academic Search

Modified poly(ethylene oxide) (PEO) networks have been studied as phase transfer catalysts, flocculates and solvent-free polymer electrolytes. The activity of the hydrogels has been investigated with respect to the structure and crosslinking density of the networks, their degree of quaternization and amphiphilic properties (hydrophilicity coefficients). It has been found that the microenvironment of the active sites (EO segments and ammonium

Tihomir N Tsanov; Krasimir S Kossev

2002-01-01

218

Use of cotton gin trash and compatibilizers in polyethylene composites  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ginning of cotton produces 15-42% of foreign materials, called “cotton gin trash”, including cotton burr, stems, leaf fragment, and dirt. In this work we examined the mechanical properties of composites of low density polyethylene (LDPE) and cotton burr. The burr was ground into powder, and se...

219

Thermostimulated depolarization currents in thermally aged polyethylene terephthalate (PET) films  

Microsoft Academic Search

Thermal aging of the polyethylene terephthalate film influences its thermostimulated depolarization current spectra. The dynamics of the process was studied. Of the three major relaxation mechanisms occurring, the space charge relaxation, appearing above 380 K, shows a complex and strong dependence on the temperature and time of aging. This dependence can also be related to changes of other macroscopic properties

A. Gubanski; S. M. Gubanski

1988-01-01

220

TSDC study of structural relaxation on polyethylene terephthalate  

Microsoft Academic Search

The influence of physical aging processes on the electrical and thermal properties of amorphous polyethylene terephthalate was investigated by means of the thermally stimulated depolarization current (TSDC), differential scanning calorimetry (DSC) and low frequency dielectric methods. A noticeable decrease in polarization and loss factor corresponding to the main ? relaxation was observed with increasing aging times, especially for aging temperatures

N. Benrekaa; A. Gourari; M. Bendaoud; R. Saoud; C. Guerbi

2006-01-01

221

Electrical breakdown of polyethylene terephthalate under hydrostatic pressure  

NASA Astrophysics Data System (ADS)

Measurements of dc dielectric breakdown strength were made on polyethylene terephthalate films of 50 micrometers in thickness at temperatures of 35, 70, and 100 C under hydrostatic pressure ranging from 50 to 500 bar. It has been found that the electrical breakdown field E(sub b) increases with pressure and decreases with temperature. It is suggested that thermal breakdown is the dominant process.

Zebouchi, N.; Essolbi, R.; Malec, D.; Giam, Hoang The; Ai, Bui; Bendaoud, M.

1994-12-01

222

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...

223

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 ...

224

Polyethylene damage and knee kinematics after total knee arthroplasty.  

PubMed

This study characterizes the relationship between in vivo knee kinematics and polyethylene damage by combining fluoroscopic analysis of tibiofemoral contact during dynamic activities and implant retrieval analysis in the same patients. Six patients (eight knees) underwent posterior cruciate ligament-retaining total knee arthroplasty. All patients participated in fluoroscopic analysis during a stair-rise and descent activity and treadmill gait an average of 18 months after arthroplasty, and articular contact was measured. Subsequently, all polyethylene tibial inserts were retrieved after an average of 26 months in vivo function: three at autopsy and five at revision. There was a statistically significant correlation between the damage location on the retrieved inserts and the articular contact location measured fluoroscopically during the activities. The femoral contact and polyethylene damage occurred predominantly on the posterior half of the tibial articular surface, and the damage pattern was largest in the compartment with the greatest range of in vivo femoral contact for each patient. This study showed that in vivo fluoroscopic analysis can predict the damage location on the polyethylene articular surface. PMID:11716412

Harman, M K; Banks, S A; Hodge, W A

2001-11-01

225

Orthorhombic phase of crystalline polyethylene: A Monte Carlo study  

Microsoft Academic Search

In this paper we present a classical Monte Carlo simulation of the orthorhombic phase of crystalline polyethylene, using an explicit atom force field with unconstrained bond lengths and angles and periodic boundary conditions. We used a recently developed algorithm which apart from standard Metropolis local moves employs also global moves consisting of displacements of the center of mass of the

R. Martonák; W. Paul; K. Binder

1997-01-01

226

Polyethylene wear in prosthetic hips with loose components  

Microsoft Academic Search

We measured in vivo polyethylene wear of acetabular cups in 74 patients (83 hips) with Charnley total hip arthroplasties (THA), revised because of aseptic loosening of either the acetabular or femoral component. We analyzed conventional pelvic radiographs of 42 THAs before revision due to loose acetabular components alone and 41 THAs before revision due to loose femoral components alone. The

Uldis Kesteris; Kevin Hardinge; Thomas Ilchmann; Hans Wingstrand

2003-01-01

227

Accelerated fatigue fracture mechanism of medium density polyethylene pipe material  

Microsoft Academic Search

Fatigue crack propagation studies were performed in medium density polyethylene pipe to elucidate the damage mechanism associated with pipe failure. Past pipe testing methods required up to several years to produce failures which mimicked those observed in the field. However, by fatiguing a specially designed test specimen, brittle failure, resembling that observed under service conditions, was produced in only three

J. J. Strebel; A. Moet

1991-01-01

228

Hybrid Polyethylene Glycol Hydrogels for Tissue Engineering Applications  

E-print Network

surgery and 25% die while waiting for a suitable donor. Tissue engineering (TE) has emerged as an alternative to organ transplant; thus, the aim of the present study was to validate a poly(ethylene glycol) diacrylate (PEG-DA) hydrogel system as a model...

Munoz Pinto, Dany 1981-

2012-07-11

229

Herbicide dissipation from low density polyethylene mulch utilizing analytical techniques  

Technology Transfer Automated Retrieval System (TEKTRAN)

In Georgia, most of the low density polyethylene mulch (LDPM) is laid for spring vegetable production followed by a second crop in the autumn, with a potential third crop the following spring. Between these vegetable plantings, farmers often use contact and residual herbicides to control weeds that ...

230

Polyethylene Terephthalate Waste Recycling and Application Possibilities: a Review  

Microsoft Academic Search

This paper presents a review of works that cover PET post-consumer waste recycling and application during last twenty years. It is shown that physically recycled PET can be used in the blends with other polymers, such as high and low density polyethylene, polycarbonates, polyvinyl chloride, etc. The compatibilizers and other additives often are used to obtain valuable blends of recycled

Gintaras MACIJAUSKAS

231

RESEARCH ARTICLE Biodegradable mulch instead of polyethylene for weed  

E-print Network

of biodegradable plastic mulch, black, 15 m, (6) oxo-degradable plastic mulch, black, 15 m, (7) paper mulch, black.3 to 4.4 t ha-1 for each 10% of efficacy loss. Weed control was high for biodegradable plastics, paper be an alternative. Keywords Polyethylene . Biodegradable mulch . Paper. Barley straw 1 Introduction Weeds

Paris-Sud XI, Université de

232

Crystalline melting of polyethylene as studied by Brillouin spectroscopy  

Microsoft Academic Search

The Brillouin spectrum of polyethylene has been measured as a function of temperature through the crystalline melting range, using a five-pass Fabry-Perot interferometer. Discontinuities have been observed in the Brillouin shift and width and the Landau-Placzek ratio near the melting temperature. The results are discussed in terms of phenomena associated with the process of melting.

S. C. Ng; T. J. C. Hosea; S. H. Goh

1988-01-01

233

Wood-Fiber/High-Density-Polyethylene Composites: Coupling Agent Performance  

E-print Network

Wood-Fiber/High-Density-Polyethylene Composites: Coupling Agent Performance John Z. Lu,1 Qinglin Wu mechanical properties of the resultant wood fiber/high-density polyeth- ylene (HDPE) composites was mainly Periodicals, Inc. J Appl Polym Sci 96: 93­102, 2005 Key words: composites; coupling efficiency; fibers; thermo

234

Polymer geometry and Li+ conduction in poly(ethylene oxide)  

E-print Network

Polymer geometry and Li+ conduction in poly(ethylene oxide) L. Gitelman a , M. Israeli b, , A: Lithium battery Polymer molecule Brownian motion Simulation Conductivity PEO a b s t r a c t We study the effect of molecular shape on Li+ conduction in dilute and concentrated poly- mer electrolytes (Li

Averbuch, Amir

235

Structure and properties of peroxide crosslinked polyethylene tubing after drawing  

Microsoft Academic Search

Crosslinked high-density polyethylene piping is currently in use for carrying pressurized hot water, chemicals, and waste. Hot and cold drawing processes, above and below melting, were studied and compared aiming at improving the pipe's toughness, strength, and creep resistance. Initially, the tensile behavior as function of temperature was investigated, and a transition from a ductile to an elastomeric behavior was

G. Samburski; M. Narkis; A. Siegmann

1996-01-01

236

Oriented and thermal crystallization of poly(ethylene terephthalate)  

Microsoft Academic Search

The oriented and thermal crystallization of amorphous poly(ethylene terephthalate) (PET) films was investigated in terms of the morphological aspects. When the amorphous PET films were stretched up to the desired draw ratios in a hot water bath at 62, 72, and 80 °C, the birefringence of the specimens increased with increasing draw ratio (?). This tendency becomes most significant when the

Tong Xu; Yuezhen Bin; Hiromichi Kurosu; Masaru Matsuo

2003-01-01

237

Diamond Lattice Model of Semicrystalline Polyethylene in the Amorphous Region  

E-print Network

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

Aluffi, Paolo

238

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...

239

Thermal conductivity of boron nitride reinforced polyethylene composites  

Microsoft Academic Search

The thermal conductivity of boron nitride (BN) particulates reinforced high density polyethylene (HDPE) composites was investigated under a special dispersion state of BN particles in HDPE, i.e., BN particles surrounding HDPE particles. The effects of BN content, particle size of HDPE and temperature on the thermal conductivity of the composites were discussed. The results indicate that the special dispersion of

Wenying Zhou; Shuhua Qi; Qunli An; Hongzhen Zhao; Nailiang Liu

2007-01-01

240

Protein assembly mediated by sulfonatocalix[4]arene.  

PubMed

A crystal structure of lysozyme in complex with p-sulfonato-calix[4]arene (sclx4) reveals a linear assembly of protein tetramers glued together by protein-calixarene interactions. One interaction involves encapsulation of the highly exposed C-terminal Arg128. The other involves an intricate protein-bound complex of sclx4, Mg(2+) and a fragment of polyethylene glycol. PMID:25068633

McGovern, Róise E; McCarthy, Andrew A; Crowley, Peter B

2014-09-18

241

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

PubMed

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

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

2014-08-11

242

Tuning the superstructure of ultrahigh-molecular-weight polyethylene/low-molecular-weight polyethylene blend for artificial joint application.  

PubMed

An easy approach was reported to achieve high mechanical properties of ultrahigh-molecular-weight polyethylene (UHMWPE)-based polyethylene (PE) blend for artificial joint application without the sacrifice of the original excellent wear and fatigue behavior of UHMWPE. The PE blend with desirable fluidity was obtained by melt mixing UHMWPE and low molecular weight polyethylene (LMWPE), and then was processed by a modified injection molding technology-oscillatory shear injection molding (OSIM). Morphological observation of the OSIM PE blend showed LMWPE contained well-defined interlocking shish-kebab self-reinforced superstructure. Addition of a small amount of long chain polyethylene (2 wt %) to LMWPE greatly induced formation of rich shish-kebabs. The ultimate tensile strength considerably increased from 27.6 MPa for conventional compression molded UHMWPE up to 78.4 MPa for OSIM PE blend along the flow direction and up to 33.5 MPa in its transverse direction. The impact strength of OSIM PE blend was increased by 46% and 7% for OSIM PE blend in the direction parallel and vertical to the shear flow, respectively. Wear and fatigue resistance were comparable to conventional compression molded UHMWPE. The superb performance of the OSIM PE blend was originated from formation of rich interlocking shish-kebab superstructure while maintaining unique properties of UHMWPE. The present results suggested the OSIM PE blend has high potential for artificial joint application. PMID:22339721

Xu, Ling; Chen, Chen; Zhong, Gan-Ji; Lei, Jun; Xu, Jia-Zhuang; Hsiao, Benjamin S; Li, Zhong-Ming

2012-03-01

243

Different mechanisms of action of poly(ethylene glycol) and arginine on thermal inactivation of lysozyme and ribonuclease A.  

PubMed

Proteins tend to undergo irreversible inactivation through several chemical modifications, which is a serious problem in various fields. We have recently found that arginine (Arg) suppresses heat-induced deamidation and ?-elimination, resulting in the suppression of thermal inactivation of hen egg white lysozyme and bovine pancreas ribonuclease A. Here, we report that poly(ethylene glycol) (PEG) with molecular weight 1,000 acts as a thermoinactivation suppressor for both proteins, especially at higher protein concentrations, while Arg was not effective at higher protein concentrations. This difference suggests that PEG, but not Arg, effectively inhibited intermolecular disulfide exchange among thermally denatured proteins. Investigation of the effects of various polymers including PEG with different molecular weight, poly(vinylpyrolidone) (PVP), and poly(vinyl alcohol) on thermoinactivation of proteins, circular dichroism, solution viscosity, and the solubility of reduced and S-carboxy-methylated lysozyme indicated that amphiphilic PEG and PVP inhibit intermolecular collision of thermally denatured proteins by preferential interaction with thermally denatured proteins, resulting in the inhibition of intermolecular disulfide exchange. These findings regarding the different mechanisms of the effects of amphiphilic polymers--PEG and PVP--and Arg would expand the capabilities of methods to improve the chemical stability of proteins in solution. PMID:22528212

Tomita, Shunsuke; Nagasaki, Yukio; Shiraki, Kentaro

2012-10-01

244

Synergistic effect of polyethylene glycol with arginine on the prevention of heat-induced aggregation of lysozyme  

NASA Astrophysics Data System (ADS)

. Arginine (Arg) is a commonly used additive to prevent protein aggregation and inactivation in denaturing solutions. This paper presents new findings on the synergistic effect on the prevention of heat-induced aggregation of lysozyme using Arg in combination with polyethylene glycol (PEG). The synergistic enhancement was observed in the presence of Arg with amphiphilic polymers, such as PEG6000, PEG20000, and poly(vinyl pyrrolidone), while it was not observed with hydrophilic polymers, such as PEG200, Poly(acrylic acid), poly(vinyl alcohol), dextran, and Ficoll 70.

Tomita, S.; Hamada, H.; Nagasaki, Y.; Shiraki, K.

2008-03-01

245

Solute diffusion and interactions in cross-linked poly(ethylene glycol) hydrogels studied by Fluorescence Correlation Spectroscopy  

PubMed Central

Controlled diffusion and release of soluble molecules is one of the key challenges in developing three-dimensional (3D) scaffolds for tissue engineering and drug delivery applications in part because current methods to measure dynamic transport properties are difficult to perform directly, are strongly affected by the experimental setup, and therefore can be a subject to various artifacts. In this work we present a method for direct measurement of translational diffusion of solutes, namely Fluorescence Correlation Spectroscopy (FCS), by characterizing the diffusion of model proteins through a 3D cross-linked poly(ethylene glycol) (PEG) hydrogel scaffold. We examined both the dynamics of hydrogel structure (e.g., cross-linking and swelling) as well as protein size and their effect on protein diffusivity. For example, we demonstrated that protein diffusivity was closely related to protein size as smaller proteins (e.g., lysozyme) diffused faster than larger proteins (e.g., ?-globulin or Ig). We validated the FCS protein diffusivity results by comparison to standard bulk diffusion assays. Additionally, due to the nature of FCS measurements, we were able to probe for hydrogel–protein interactions during cross-linking that may contribute to the obstructed protein diffusion in the 3D scaffold. We determined that such interactions in this system were not covalent (i.e., were independent of the cross-linking chemistry) but may be due to weaker hydrogen bonding or ionic interactions. Also, these interactions were protein specific and contributed up to 25% of the total decrease in protein diffusivity in the hydrogel as compared to diffusivity in water. Though interactions between various proteins and PEG have been reported, this is the first study that has explored these effects in detail in cross-linked PEG hydrogels using FCS; our findings question the assumption that PEG hydrogels are completely inert to protein interactions when applied as drug delivery matrices and tissue engineering scaffolds. PMID:24282439

Zustiak, Silviya P.; Boukari, Hacene

2013-01-01

246

An improved synthesis of a fluorophosphonate-polyethylene glycol-biotin probe and its use against competitive substrates.  

PubMed

The fluorophosphonate (FP) moiety attached to a biotin tag is a prototype chemical probe used to quantitatively analyze and enrich active serine hydrolases in complex proteomes in an approach called activity-based protein profiling (ABPP). In this study we have designed a novel synthetic route to a known FP probe linked by polyethylene glycol to a biotin tag (FP-PEG-biotin). Our route markedly increases the efficiency of the probe synthesis and overcomes several problems of a prior synthesis. As a proof of principle, FP-PEG-biotin was evaluated against isolated protein mixtures and different rat-tissue homogenates, showing its ability to specifically target serine hydrolases. We also assessed the ability of FP-PEG-biotin to compete with substrates that have high enzyme turnover rates. The reduced protein-band intensities resulting in these competition studies demonstrate a new application of FP-based probes seldom explored before. PMID:23400700

Xu, Hao; Sabit, Hairat; Amidon, Gordon L; Showalter, H D Hollis

2013-01-01

247

Dielectric behavior of AC aged polyethylene in humid environment  

SciTech Connect

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.

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

248

Study of the Auger line shape of polyethylene and diamond  

NASA Technical Reports Server (NTRS)

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.

Dayan, M.; Pepper, S. V.

1984-01-01

249

Polyethylene naphthalate as an excellent candidate for ripple nanopatterning  

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

250

Packet charge dynamic in thin polyethylene under high dc voltage  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

251

Photophysics of poly(ethylene terephthalate): Ultraviolet absorption and emission  

SciTech Connect

Polarized and unpolarized emission spectra for poly(ethylene terephthalate) are presented, and a new phosphorescence peak at 564 nm is reported. The spectroscopically parameterized CNDO/S3 model is used to provide a detailed description of the absorption and monomeric emission. Moreover, preliminary computations on an idealized terephthalate dimer indicate that the 368-nm fluorescence and the newly reported phosphorescence emission may be attributable to an associated ground-state dimer.

LaFemina, J.P. (Pacific Northwest Lab., Richland, WA (USA)); Arjavalingam, G. (IBM Thomas J. Watson Research Center, Yorktown Heights, NY (USA))

1991-01-24

252

Polyethylene and metal wear particles: characteristics and biological effects  

Microsoft Academic Search

This paper first presents a brief overview about the mechanism of wear particle formation as well as wear particle characteristics\\u000a in metal-on-polyethylene and metal-on-metal artificial hip joints. The biological effects of such particles are then described,\\u000a focusing on the inflammatory response induced by each type of particles as well as on how metal wear products may be the source\\u000a of

Isabelle Catelas; Markus A. Wimmer; Sandra Utzschneider

2011-01-01

253

Acetabular Loosening Using an Extended Offset Polyethylene Liner  

Microsoft Academic Search

The use of extended offset femoral components and acetabular liners helps restore preoperative offset during hip arthroplasty.\\u000a We report a relatively high acetabular component aseptic loosening rate with the use of offset polyethylene liners. We reviewed\\u000a 1919 primary and 346 revision total hip arthroplasties (THAs). A 7-mm offset acetabular liner was used in 120 of the primary\\u000a and 100 of

Michael J. Archibeck; Tamara Cummins; Daniel W. Junick; Richard E. White Jr

2009-01-01

254

Using polyethylene glycols as alternative inhibitors in copper electrorefining  

NASA Astrophysics Data System (ADS)

Polyethylene glycols (PEGs) with well-defined molecular weight ranges are interesting alternative additives for copper electrorefining. In comparison to glue, PEGs offer high thermal stability and slow chemical decomposition at higher temperatures, with high cathodic polarization. Thosefactors are advantages for an optimized process control in copper electrorefining. Investigations into cathodic polarization as a function of molecular weight and concentration at 500 A/m2, and also into the half-life of PEGs, were conducted in typical copper electrolyte.

Stelter, Michael; Bombach, Hartmut; Nesterov, Nikolay

2002-04-01

255

Some special features of spinning of polyethylene gel-fibre  

Microsoft Academic Search

Slow heating of the polymer powder in the solvent with intense stirring in an apparatus with self-cleaning surfaces is required for obtaining a homogeneous solution of ultrahigh-molecular-weight polyethylene (UHMPE). In spinning UHMPE gel-fibre by the dry-wet method, it is necessary to use a liquid with a low surface tension coefficient in the cooling bath. When ultrastrong, high-modulus UHMPE fibre is

V. G. Alekseev

1995-01-01

256

Molecular dynamics simulation of chains mobility in polyethylene crystal  

E-print Network

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.

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

2014-01-17

257

Dielectric properities of polyethylene modified by monoesters of maleic acid  

NASA Astrophysics Data System (ADS)

Dielectric properties of low-density polyethylene (LDPE) modified by monoesters of maleic acid have been investigated. The coagent molecules can interact with molecules of LDPE giving rise to cross-linking and changes of degree of crystallinity. Depending on the modifier used, the dielectric losses of modified LDPE at the lower frequencies may change significantly. The dielectric losses of LDPE modified with dodecyl maleate increases by over one order of magnitude.

Swiatek-Prokop, Jozef; Bak, Grzegorz W.; Slusarski, L.

1999-12-01

258

Do Polyethylene Plastic Covers Affect Smoke Emissions from Debris Piles?  

NASA Astrophysics Data System (ADS)

Shrubs and small diameter trees exist in the understories of many western forests. They are important from an ecological perspective; however, this vegetation also presents a potential hazard as “ladder fuels” or as a heat source to damage the overstory during prescribed burns. Cutting and piling of this material to burn under safe conditions is a common silvicultural practice. To improve ignition success of the piled debris, polyethylene plastic is often used to cover a portion of the pile. While burning of piled forest debris is an acceptable practice in southern California from an air quality perspective, inclusion of plastic in the piles changes these debris piles to rubbish piles which should not be burned. With support from the four National Forests in southern California, we conducted a laboratory experiment to determine if the presence of polyethylene plastic in a pile of burning wood changed the smoke emissions. Debris piles in southern California include wood and foliage from common forest trees such as sugar and ponderosa pines, white fir, incense cedar, and California black oak and shrubs such as ceanothus and manzanita in addition to forest floor material and dirt. Manzanita wood was used to represent the debris pile in order to control the effects of fuel bed composition. The mass of polyethylene plastic incorporated into the pile was 0, 0.25 and 2.5% of the wood mass—a range representative of field conditions. Measured emissions included NOx, CO, CO2, SO2, polycyclic and light hydrocarbons, carbonyls, particulate matter (5 to 560 nm), elemental and organic carbon. The presence of polyethylene did not alter the emissions composition from this experiment.

Weise, D. R.; Jung, H.; Cocker, D.; Hosseini, E.; Li, Q.; Shrivastava, M.; McCorison, M.

2010-12-01

259

Effect of cenosphere on dielectric properties of low density polyethylene  

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

260

Wear of a sequentially annealed polyethylene acetabular liner  

PubMed Central

Background and purpose We previously reported on a randomized controlled trial (RCT) that examined the effect of adding tobramycin to bone cement after femoral stem migration. The present study examined femoral head penetration into both conventional and highly crosslinked polyethylene acetabular liners in the same group of RCT patients, with a minimum of 5 years of postoperative follow-up. Patients and methods Linear penetration of the femoral head into an X3 (Stryker) crosslinked polyethylene (XLPE) liner was measured in 18 patients (19 hips) using radiostereometric analysis (RSA). Femoral head penetration was also measured in 6 patients (6 hips) with a conventional polyethylene liner (CPE), which served as a control group. Results The median proximal femoral head penetration in the XLPE group after 5.5 years was 0.025 mm with a steady-state penetration rate of 0.001 mm/year between year 1 and year 5. The CPE liner showed a median proximal head penetration of 0.274 mm after 7.2 years, at a rate of 0.037 mm/year. Interpretation The Trident X3 sequentially annealed XLPE liner shows excellent in vivo wear resistance compared to non-crosslinked CPE liners at medium-term implantation. The rate of linear head penetration in the XLPE liners after > 5 years of follow-up was 0.001 mm/year, which is in close agreement with the results of previous studies. PMID:25140986

Gascoyne, Trevor C; Petrak, Martin J; Turgeon, Thomas R; Bohm, Eric R

2014-01-01

261

Polyethylene Wear Is Influenced by Manufacturing Technique in Modular TKA  

PubMed Central

Polyethylene insert backside surface wear is implicated in osteolysis and failure of total knee arthroplasty. Manufacturing and sterilization methods reduce articular-sided wear. We questioned whether manufacturing technique influences the severity of backside wear. We examined 39 explanted tibial bearings in a blinded fashion using visual, stereomicroscopic, and scanning electron microscopic techniques. We examined 26 direct compression molded components and 13 nondirect compression molded components and applied a new backside wear severity score. The score characterized the magnitude of the various modes of wear with severity ranging from 0 (no wear) to 27 (severe wear). Time in vivo, tibial baseplate material, and manufacturing technique were used as variables for comparison. Backside wear was related to polyethylene manufacturing process with direct compression molded implants having a wear score of 2.3 and nondirect compression molded a score of 5.7. Time in vivo influenced backside wear, although direct compression molded predicted decreased backside wear independent of time in vivo. The data suggest manufacturing technique influences backside wear in total knee arthroplasty polyethylene inserts. PMID:18791779

Ellison, Bradley S.; Berend, Keith R.

2008-01-01

262

Stabilization of solid dispersions of nimodipine and polyethylene glycol 2000.  

PubMed

Previous investigations revealed that solid dispersions consisting of 20% (m/m) nimodipine and 80% (m/m) polyethylene glycol 2000 prepared by the melting method, represent supersaturated solid solutions of nimodipine recrystallizing upon storage at +25 degrees C. The objective of this study was the improvement of the storage stability by preventing recrystallization. The first approach in order to prevent recrystallization was the development of thermodynamically stable solid solutions by using solvents aiming to enhance the solubility of nimodipine in the carrier material. As potential solubility enhancing additives, polyethylene glycol 300, poly(ethylene/propylene glycol) copolymer, polypropylene glycol 1020, propylene glycol, glycerol and ethyl acetate were evaluated. The second approach enhancing storage stability was the addition of recrystallization inhibitors to supersaturated solid solutions, thereby delaying the transformation of the metastable supersaturated system to the thermodynamically stable state. Macrogol cetostearyl ether, macrogol glycerol monostearate, polysorbate 60, cetostearyl alcohol, glycerol monostearate and sodium lauryl sulphate as well as hydroxypropylcellulose, butylmethacrylat-(2-dimethylaminoethyl)methacrylat-methylmethacrylat-copolymer, polyacrylic acid, polyvinyl alcohol and povidone K17 were included in the study. It could be shown that povidone K17 effectively prevents recrystallization in solid solutions containing 20% (m/m) of nimodipine during storage at +25 degrees C over silica gel thereby ensuring a substantial increase in the dissolution rate and degree of supersaturation in water. On the contrary, stabilization by solubility enhancement was only successful at drug loadings not exceeding 1% (m/m) using polyethylene glycol 300 as solubility enhancing additive. PMID:16472995

Urbanetz, Nora Anne

2006-05-01

263

Polyethylene macroencapsulation - mixed waste focus area. OST reference No. 30  

SciTech Connect

The lead waste inventory throughout the US Department of Energy (DOE) complex has been estimated between 17 million and 24 million kilograms. Decontamination of at least a portion of the lead is viable but at a substantial cost. Because of various problems with decontamination and its limited applicability and the lack of a treatment and disposal method, the current practice is indefinite storage, which is costly and often unacceptable to regulators. Macroencapsulation is an approved immobilization technology used to treat radioactively contaminated lead solids and mixed waste debris. (Mixed waste is waste materials containing both radioactive and hazardous components). DOE has funded development of a polyethylene extrusion macroencapsulation process at Brookhaven National Laboratory (BNL) that produces a durable, leach-resistant waste form. This innovative macroencapsulation technology uses commercially available single-crew extruders to melt, convey, and extrude molten polyethylene into a waste container in which mixed waste lead and debris are suspended or supported. After cooling to room temperature, the polyethylene forms a low-permeability barrier between the waste and the leaching media.

NONE

1998-02-01

264

Impact resistance and fractography in ultra high molecular weight polyethylenes.  

PubMed

Highly crosslinked ultra high molecular weight polyethylenes (UHMWPE) stabilized by a remelting process or by the addition of an antioxidant are highly wear resistant and chemically stable. However, these polyethylenes currently used in total joint replacements suffer a loss of mechanical properties, especially in terms of fracture toughness. In this study we analyze the impact behavior of different polyethylenes using an instrumented double notch Izod test. The materials studied are three resins: GUR1050, GUR1020 with 0.1wt% of vitamin E, and MG003 with 0.1wt% of vitamin E. These resins were gamma irradiated at 90kGy, and pre and post-irradiation remelting processes were applied to GUR1050 for two different time periods. Microstructural data were determined by means of differential scanning calorimetry and transmission electron microscopy. Fractography carried out on the impact fracture surfaces and images obtained by scanning electron microscopy after etching indicated the existence of a fringe structure formed by consecutive ductile-brittle and brittle-ductile transitions, which is related to the appearance of discontinuities in the load-deflection curves. A correlation has been made of the macroscopic impact strength results and the molecular chain and microstructural characteristics of these aforementioned materials, with a view to designing future resins with improved impact resistance. The use of UHMWPE resins with low molecular weight or the application of a remelting treatment could contribute to obtain a better impact strength behavior. PMID:24275347

Puértolas, J A; Pascual, F J; Martínez-Morlanes, M J

2014-02-01

265

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

PubMed Central

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

Horst, Walter Johannes

2013-01-01

266

Mechanical, rheological, and bioactivity properties of ultra high-molecular-weight polyethylene bioactive composites containing polyethylene glycol and hydroxyapatite.  

PubMed

Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50?phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis. PMID:22666129

Ahmad, Mazatusziha; Uzir Wahit, Mat; Abdul Kadir, Mohammed Rafiq; Mohd Dahlan, Khairul Zaman

2012-01-01

267

Mechanical, Rheological, and Bioactivity Properties of Ultra High-Molecular-Weight Polyethylene Bioactive Composites Containing Polyethylene Glycol and Hydroxyapatite  

PubMed Central

Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50?phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis. PMID:22666129

Ahmad, Mazatusziha; Wahit, Mat Uzir; Abdul Kadir, Mohammed Rafiq; Mohd Dahlan, Khairul Zaman

2012-01-01

268

Adhesion, Growth, and Maturation of Vascular Smooth Muscle Cells on Low-Density Polyethylene Grafted with Bioactive Substances  

PubMed Central

The attractiveness of synthetic polymers for cell colonization can be affected by physical, chemical, and biological modification of the polymer surface. In this study, low-density polyethylene (LDPE) was treated by an Ar+ plasma discharge and then grafted with biologically active substances, namely, glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C), or BSA+C. All modifications increased the oxygen content, the wettability, and the surface free energy of the materials compared to the pristine LDPE, but these changes were most pronounced in LDPE with Gly or PEG, where all the three values were higher than in the only plasma-treated samples. When seeded with vascular smooth muscle cells (VSMCs), the Gly- or PEG-grafted samples increased mainly the spreading and concentration of focal adhesion proteins talin and vinculin in these cells. LDPE grafted with BSA or BSA+C showed a similar oxygen content and similar wettability, as the samples only treated with plasma, but the nano- and submicron-scale irregularities on their surface were more pronounced and of a different shape. These samples promoted predominantly the growth, the formation of a confluent layer, and phenotypic maturation of VSMC, demonstrated by higher concentrations of contractile proteins alpha-actin and SM1 and SM2 myosins. Thus, the behavior of VSMC on LDPE can be regulated by the type of bioactive substances that are grafted. PMID:23586032

Parizek, Martin; Slepickova Kasalkova, Nikola; Bacakova, Lucie; Bacakova, Marketa; Lisa, Vera; Svorcik, Vaclav

2013-01-01

269

Protein adsorption characterization.  

PubMed

Protein adsorption from (aqueous) solutions onto a (solid) surface is a common process that takes place at biological interfaces. This phenomenon, that spontaneously occurs, changes the properties of the surface and can induce structural modifications on proteins. Proteins in solution can be easily identified/quantified using classical biochemical methods. However, adsorbed proteins are more difficult to assess since they are always associated with a substrate. The selection of the analytical method depends on the type of substrate used, the amount of adsorbed protein, the type of solution (single protein solution vs. complex biological media), and the type of information that is demanded (quantification of the adsorbed protein, adsorption kinetics, conformation, and orientation of the adsorbed protein). Until now, none of the techniques available are capable by its own to characterize all the protein adsorption process. Therefore, a multitechnique analysis is required. During this chapter, the methodologies to measure human serum albumin to poly(ethylene terephthalate) using the three different techniques, radiolabeling, ellipsometry, and quartz crystal microbalance with dissipation - QCM-D, are described in detail. The specific preparation of polymeric surfaces to be used with each technique is also presented. PMID:22042678

Martins, M Cristina L; Sousa, Susana R; Antunes, Joana C; Barbosa, Mário A

2012-01-01

270

Vol. 79, No. 2, 2002 261 Tensile Properties of Extruded Corn Protein  

E-print Network

Vol. 79, No. 2, 2002 261 Tensile Properties of Extruded Corn Protein Low-Density Polyethylene Films products, petroleum conservation, and con- servation of landfill space. Research in protein films has focused on the production of solvent- cast films. Corn and wheat protein (Aydt et al 1991; Herald et al

271

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

PubMed Central

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

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

2014-01-01

272

Characterization of a cryptic plasmid, pSM103mini, from polyethylene-glycol degrading Sphingopyxis macrogoltabida strain 103.  

PubMed

A cryptic plasmid, pSM103mini, was found in polyethylene-glycol degrading bacterium Sphingopyxis macrogoltabida, strain 103. The plasmid was 4,328-bp long and its GC content was 57.5%. It contained four open reading frames, but only two of them showed significant similarity to reported proteins. ORF3 and ORF4 were assumed to encode resolvase and replication protein (RepA) respectively. Downstream of ORF4 we found complex repeat sequences. These together with ORF3 and 4 were necessary and sufficient for plasmid maintenance in strain 103, as analyzed by constructing deletion plasmids. The pHSG398-fused plasmid (pHSG-SM103mini) functioned as a shuttle vector between strain 103 and Escherichia coli. The plasmid constructed was maintained in strain 103 and its close relative, S. macrogoltabida strain 203, but not efficiently in PEG-degrading S. terrae. PMID:21307601

Tani, Akio; Tanaka, Akiyuki; Minami, Toshiyuki; Kimbara, Kazuhide; Kawai, Fusako

2011-01-01

273

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

E-print Network

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...

McCaskill, Jennifer R.

2010-01-16

274

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

DOEpatents

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.

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

1986-01-01

275

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

276

Hydrolytically degradable poly(ethylene glycol) hydrogel scaffolds with tunable degradation and mechanical properties  

PubMed Central

The objective of this work was to create three-dimensional (3D) hydrogel matrices with defined mechanical properties, as well as tunable degradability for use in applications involving protein delivery and cell encapsulation. Thus, we report the synthesis and characterization of a novel hydrolytically degradable poly(ethylene glycol) (PEG) hydrogel composed of PEG vinyl sulfone (PEG-VS) cross-linked with PEG-diester-dithiol. Unlike previously reported degradable PEG-based hydrogels, these materials are homogeneous in structure, fully hydrophilic and have highly specific cross-linking chemistry. We characterized hydrogel degradation and associated trends in mechanical properties, i.e., storage modulus (G?), swelling ratio (QM), and mesh size (?). Degradation time and the monitored mechanical properties of the hydrogel correlated with cross-linker molecular weight, cross-linker functionality, and total polymer density; these properties changed predictably as degradation proceeded (G? decreased, whereas QM and ? increased) until the gels reached complete degradation. Balb/3T3 fibroblast adhesion and proliferation within the 3D hydrogel matrices were also verified. In sum, these unique properties indicate that the reported degradable PEG hydrogels are well poised for specific applications in protein and cell delivery to repair soft tissue. PMID:20355705

Zustiak, Silviya P.

2011-01-01

277

Drying and storage effects on poly(ethylene glycol) hydrogel mechanical properties and bioactivity.  

PubMed

Hydrogels based on poly(ethylene glycol) (PEG) are increasingly used in biomedical applications because of their ability to control cell-material interactions by tuning hydrogel physical and biological properties. Evaluation of stability after drying and storage are critical in creating an off-the-shelf biomaterial that functions in vivo according to original specifications. However, there has not been a study that systematically investigates the effects of different drying conditions on hydrogel compositional variables. In the first part of this study, PEG-diacrylate hydrogels underwent common processing procedures (vacuum-drying, lyophilizing, hydrating then vacuum-drying), and the effect of this processing on the mechanical properties and swelling ratios was measured. Significant changes in compressive modulus, tensile modulus, and swelling ratio only occurred for select processed hydrogels. No consistent trends were observed after processing for any of the formulations tested. The effect of storage conditions on cell adhesion and spreading on collagen- and streptococcal collagen-like protein (Scl2-2)-PEG-diacrylamide hydrogels was then evaluated to characterize bioactivity retention after storage. Dry storage conditions preserved bioactivity after 6 weeks of storage; whereas, storage in PBS significantly reduced bioactivity. This loss of bioactivity was attributed to ester hydrolysis of the protein linker, acrylate-PEG-N-hydroxysuccinimide. These studies demonstrate that these processing methods and dry storage conditions may be used to prepare bioactive PEG hydrogel scaffolds with recoverable functionality after storage. PMID:24123725

Luong, P T; Browning, M B; Bixler, R S; Cosgriff-Hernandez, E

2014-09-01

278

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

PubMed

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

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

2014-11-01

279

Mass Spectrometric Mapping of Fibrinogen Conformations at Poly(ethylene terephthalate) Interfaces1  

PubMed Central

We have characterized the adsorption of bovine fibrinogen onto the biomedical polymer polyethylene terephthalate (PET) by performing mass spectrometric mapping with a lysine-reactive biotin label. After digestion with trypsin, MALDI-TOF mass spectrometry was used to detect peptides from biotinylated bovine fibrinogen, with the goal of identifying lysines that were more accessible for reaction with the chemical label after adsorption. Peptides within domains that are believed to contribute to heparin binding, leukocyte activation, and platelet adhesion were found to be biotin labeled only after bovine fibrinogen adsorbed to the PET surface. Additionally, the accessibility of lysine residues throughout the entire molecule was observed to increase as the concentration of the adsorbing bovine fibrinogen solution decreased, suggesting that the proximity of biologically active motifs to hydrophilic residues leads to their exposure. The surface area per adsorbed bovine fibrinogen molecule was quantified on PET using optical waveguide lightmode spectroscopy (OWLS), which revealed higher surface densities for bovine fibrinogen adsorbed from higher concentration solutions. By measuring changes in both the identity and conformation of proteins that adsorb from complex mixtures such as blood or plasma, this technique may have applications in fundamental studies of protein adsorption and may allow for more accurate predictions of the biocompatibility of materials. PMID:17582492

Scott, Evan A.; Elbert, Donald L.

2007-01-01

280

Dielectric relaxation spectroscopy of polyethylene terephthalate (PET) films  

Microsoft Academic Search

The dielectric properties of biaxially stretched polyethylene terephthalate (PET) films of 0022-3727\\/30\\/11\\/003\\/img6 thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 0022-3727\\/30\\/11\\/003\\/img7 Hz and the temperature range 0022-3727\\/30\\/11\\/003\\/img8C. Differencial scanning calorimetry (DSC), in the range 0022-3727\\/30\\/11\\/003\\/img9C, was employed to investigate the thermal properties of the PET samples. Besides measuring the 0022-3727\\/30\\/11\\/003\\/img10

E. Neagu; P. Pissis; L. Apekis; J. L. Gomez Ribelles

1997-01-01

281

Pyrolysis Pathways of Sulfonated Polyethylene, an Alternative Carbon Fiber Precursor  

SciTech Connect

Sulfonated polyethylene is an emerging precursor for the production of carbon fibers. Pyrolysis of sulfonated polyethylene was characterized by thermogravimetric analysis (TGA). n-heptane-4-sulfonic acid (H4S) was selected as a model compound for the study of sulfonated polyethylene. Density functional theory and conventional transition state theory were used to determine the rate constants of pyrolysis for H4S from 300-1000 K. Multiple reaction channels from two different mechanisms were explored: 1) internal five-centered elimination (Ei 5) and 2) radical chain reaction. The pyrolysis of H4S was simulated with kinetic Monte Carlo (kMC) to obtain TGA plots that compared favorably to experiment. We observed that at tem- peratures < 550 K, the radical mechanism was dominant and yielded the trans-alkene, whereas cis-alkene was formed at higher temperatures from the internal elimination. The maximum rates of % mass loss became independent of initial OH radical concentration at 440-480 K. Experimentally, the maximum % mass loss occurred from 440-460 K (heating rate dependent). Activation energies derived from the kMC-simulated TGAs of H4S (26-29 kcal/mol) agreed with experiment for sulfonated polyethylene ( 31 kcal/mol). The simulations revealed that in this region, decomposition of radical HOSO2 became competitive to H abstraction by HOSO2, making OH the carrying radical for the reaction chain. The maximum rate of % mass loss for internal elimination was observed at temperatures > 600 K. Low-scale carbonization utilizes temperatures < 620 K; thus, internal elimination will not be competitive. Ei5 elimination has been studied for sulfoxides and sulfones, but this represents the first study of internal elimination in sulfonic acids. Nonlinear Arrhenius plots were found for all bimolecular reactions. The most significant nonlinear behavior was observed for reactions where the barrier was small. For reactions with low activation barriers, nonlinearity was traced to conflicting trends between the exponential temperature dependence of the energetic term and the temperature dependence of the vibrational partition function of the transitional modes.

Younker, Jarod M [ORNL; Saito, Tomonori [ORNL; Hunt, Marcus A [ORNL; Beste, Ariana [ORNL; Naskar, Amit K [ORNL

2013-01-01

282

Effective UV radiation dose in polyethylene exposed to weather  

NASA Astrophysics Data System (ADS)

In this work we quantified the effective UV radiation dose in orange and colorless polyethylene samples exposed to weather in the city of Aguascalientes, Ags. Mexico. The spectral distribution of solar radiation was calculated using SMART 2.9.5.; the samples absorption properties were measured using UV-Vis spectroscopy and the quantum yield was calculated using samples reflectance properties. The determining factor in the effective UV dose is the spectral distribution of solar radiation, although the chemical structure of materials is also important.

González-Mota, R.; Soto-Bernal, J. J.; Rosales-Candelas, I.; Calero Marín, S. P.; Vega-Durán, J. T.; Moreno-Virgen, R.

2009-09-01

283

Polyethylene glycol-based homologated ligands for nicotinic acetylcholine receptors?  

PubMed Central

A homologous series of polyethylene glycol (PEG) monomethyl ethers were conjugated with three ligand series for nicotinic acetylcholine receptors. Conjugates of acetylaminocholine, the cyclic analog 1-acetyl-4,4-dimethylpiperazinium, and pyridyl ether A-84543 were prepared. Each series was found to retain significant affinity at nicotinic receptors in rat cerebral cortex with tethers of up to six PEG units. Such compounds are hydrophilic ligands which may serve as models for fluorescent/affinity probes and multivalent ligands for nAChR. PMID:19006672

Scates, Bradley A.; Lashbrook, Bethany L.; Chastain, Benjamin C.; Tominaga, Kaoru; Elliott, Brandon T.; Theising, Nicholas J.; Baker, Thomas A.; Fitch, Richard W.

2010-01-01

284

MD Simulation Study of the Influence of Branch Content on Relaxation and Crystallization of Branched Polyethylene Chains with Uniform Branch Distribution  

E-print Network

-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and low-density polyethylene (LDPE). HDPE is made of mainly linear chains, while LDPE is usually made by free radical polymerization and short and long chain

Hussein, Ibnelwaleed A.

285

Analyzing and improving viscoelastic properties of high density polyethylene  

NASA Astrophysics Data System (ADS)

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

Ahmed, Reaj Uddin

2011-12-01

286

Synthesis of poly(ethylene oxide) approaching monodispersity.  

PubMed

Polydispersity in polymers hinders fundamental understanding of their structure-property relationships and prevents them from being used in fields like medicine, where polydispersity affects biological activity. The polydispersity of relatively short-chain poly(ethylene oxide) [(CH2CH2O2)n; PEO] affects its biological activity, for example, the toxicity and efficacy of PEOylated drugs. As a result, there have been intensive efforts to reduce the dispersity as much as possible (truly monodispersed materials are not possible). Here we report a synthetic procedure that leads to an unprecedented low level of dispersity. We also show for the first time that it is possible to discriminate between PEOs differing in only 1 ethylene oxide (EO) unit, essential in order to verify the exceptionally low levels of dispersity achieved here. It is anticipated that the synthesis of poly(ethylene oxide) approaching monodispersity will be of value in many fields where the applications are sensitive to the distribution of molar mass. PMID:24828235

Maranski, Krzysztof; Andreev, Yuri G; Bruce, Peter G

2014-06-16

287

Effect of thermal modification on rheological properties of polyethylene blends  

SciTech Connect

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.

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

288

Preparation and Characterization of Partially Degraded High-Density Polyethylene in an Internal Mixer  

Microsoft Academic Search

The partial degradation of high-density polyethylene was done in an internal mixer for different residence time. The oxidative thermomechanical degradation resulted in the formation of carbonyl groups in the polymer. The carbonyl index values estimated from the FTIR studies indicate the increase of carbonyl groups without any induction time. The common phenomenon during oxidative degradation of polyethylene is the increase

Arunjunai Raj Mahendran; Nicolai Aust; Chinnaswamy Thangavel Vijayakumar; Klaus Lederer

2008-01-01

289

Modification of High-Yield Pulps with Polyethylene Glycols. I. Model Compound and Isolated Lignin Studies  

Microsoft Academic Search

Phenolic hydroxyl groups in three lignin model compounds, guaiacol, acetoguaiacone, and dehydrodiisoeugenol, and in organosolv lignin were blocked by etherification with polyethylene glycol (PEG). Polyethylene glycol modification, even at a low degree of substitution, greatly enhanced the hydrophilicity of the substrate, producing water-soluble substances. When etherified by reaction with PEG-mesylate, the lignin dimer model compound, dehydrodiisoeugenol, was stabilized considerably against

Barbara J. W. Cole; Stacey P. Huth; Pamela S. Runnels

1993-01-01

290

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

E-print Network

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

Wang, Howard "Hao"

291

Transient current generation during wear of high-density polyethylene by a stainless-steel stylus  

E-print Network

Transient current generation during wear of high-density polyethylene by a stainless-steel stylus J force measurements as a stainless-steel stylus is drawn across a high-density polyethylene surface-related features at intervals consistent with the lateral force and current fluctuations. Although average charge

Dickinson, J. Thomas

292

Development of a Remote External Repair Tool for Damaged or Defective Polyethylene (PE) Gas Pipe  

Microsoft Academic Search

Repair methods for polyethylene gas pipe are being investigated at Timberline Tool and Oregon State University under a cooperative agreement with the Department of Energy National Energy Technology Laboratory. Current repair procedures for polyethylene (PE) gas pipe require excavation, isolation, and removal of the damaged section of pipe followed by fusing a new section of pipe into place. The project

Kenneth H. Green; Cheryl Carbone; Ken Cramer; Kevin Harris; John Hunt; Lioubov Kabalnova; Nick Wannamacher

293

Characterization of poly(ethylene terephthalate) used in commercial bottled water  

E-print Network

Characterization of poly(ethylene terephthalate) used in commercial bottled water Cristina Bach1 into drinking water packaged in poly(ethylene terephtalate) bottles and to know the origin of these substances into bottled water. A panel of water bottles has been tested after exposure to extreme conditions

Paris-Sud XI, Université de

294

The influence of soil macroinvertebrates on primary biodegradation of starch-containing polyethylene films  

Microsoft Academic Search

The primary biodegradability of polyethylene (PE) films containing different percentages of cornstarch (0–50%) and other additives (prooxidant, oxidized polyethylene) was tested using four species of earthworms (Eisenia fetida, Lumbricus terrestris, Aporectodea trapezoides, Aporectodea tuberculata), three species of cockroaches (Periplaneta americana, Blaberus sp.,Blattella germanica), termites (Reticulotermes flavipes), sowbugs (Porcellio laevis), and crickets (Acheta domesticus). These studies were conducted to elucidate the

Rong Tsao; Todd A. Anderson; Joel R. Coats

1993-01-01

295

Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate Blends  

E-print Network

Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate of using polyethylene-stearate blends having CaP coatings include: increased surface porosity that can in terms of uniform surface coverage and coating thickness [1]. The temperatures used for plasma spray

Drelich, Jaroslaw W.

296

A COMPARATIVE STUDY OF THE WETTABILITY OF STEEL, CARBON, AND POLYETHYLENE FIBERS BY WATER  

E-print Network

A COMPARATIVE STUDY OF THE WETTABILITY OF STEEL, CARBON, AND POLYETHYLENE FIBERS BY WATER W. Lu, X at Buffalo, Buffalo, NY 14260-4400, USA (Received March 9, 1998; in final form April 10, 1998) ABSTRACT The wettability of fibers by water was found to increase in this order: polyethylene fiber, steel fiber

Chung, Deborah D.L.

297

Breakdown phenomenon identification of biodegradable polyethylene film under UV-irradiation environment  

Microsoft Academic Search

Biodegradable polymers are increasingly expected for substitute of present insulating materials in the electrical and electronic devices. However, their electrical properties are not systematically confirmed and need further investigation. In this paper, biodegradable polyethylene (BDPE) films are employed as the specimens and high density polyethylene (HDPE) films are as the reference. The breakdown endurance of BDPE film is examined using

B. X. Du; Yong Liu; Y. S. Xia; B. C. Liu

2008-01-01

298

Accepted Manuscript Kinetic Modelling of High Density PolyEthylene Pyrolysis: Part 1. Comparison of  

E-print Network

Accepted Manuscript Kinetic Modelling of High Density PolyEthylene Pyrolysis: Part 1. Comparison this article as: Gascoin N, Navarro-Rodriguez A, Gillard P, Mangeot A, Kinetic Modelling of High Density PolyEthylene.polymdegradstab.2012.05.008 #12;M ANUSCRIPT ACCEPTED ACCEPTED MANUSCRIPT 1 Kinetic Modelling of High Density PolyEthylene

Paris-Sud XI, Université de

299

Optimum arrangement for the neutron dose rate of an iron-polyethylene shielding system  

SciTech Connect

Integral shielding experiments using iron-polyethylene slab shields were carried out to determine an optimum arrangement for the neutron dose rate. The total thickness of the iron slabs was fixed at 32 cm, while several thicknesses of polyethylene slabs were employed as a parameter. Some measured data were analyzed by the Mone Carlo code MORSE-CG with the splitting technique.

Ueki, K.; Namito, Y.

1987-05-01

300

Microbiology of polyethylene-packaged sliced watermelon (Citrullus lanatus) sold by street vendors in Nigeria  

Microsoft Academic Search

Ten packaged, freshly sliced watermelon were collected from different street vendors to determine their microbiological quality. Eight different microbial isolates were obtained from the sliced watermelon samples, namely Escherichia coli, Klebsiella aerogenes, Proteus mirabilis, Staphylococcus aureus, Lactobacillus spp., Saccharomyces cerevisiae, Rhizopus stolonifer and Mucor spp. The effects of high density polyethylene (HDP) and low density polyethylene (LDP) packaging bags on

E. Nwachukwu; C. F. Ezeama; Michael Okpara

301

Leaf Area Distribution of Tomato Plants as Influenced by Polyethylene Mulch  

E-print Network

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, tomato plants grown with white mulch had more axillary leaves than plants in the black mulch, resulting

Decoteau, Dennis R.

302

Thiol-modified poly(ethylene glycol)-conjugated gold/ superparamagnetic iron oxide nanoparticles  

E-print Network

Thiol-modified poly(ethylene glycol)-conjugated gold/ superparamagnetic iron oxide nanoparticles Chemical name: Thiol-modified poly(ethylene glycol)-conjugated gold/superparamagnetic iron oxide-targeted Target category: Non-targeted Method of detection: Magnetic resonance imaging (MRI) Source of signal

Levin, Judith G.

303

Extended release of a large amount of highly water-soluble diltiazem hydrochloride by utilizing counter polymer in polyethylene oxides (PEO)\\/polyethylene glycol (PEG) matrix tablets  

Microsoft Academic Search

The purpose of this study was to evaluate the feasibility of using a counter polymer in polyethylene oxide (PEO)\\/polyethylene glycol (PEG) polymeric matrices for the sustained release of a large amount of highly water-soluble drug. PEO\\/PEG matrix tablets (CR-A) containing four drugs with different water solubilities were prepared to investigate the effect of drug solubility on the drug-release and diffusion

Hiroyuki Kojima; Keiichi Yoshihara; Toyohiro Sawada; Hiromu Kondo; Kazuhiro Sako

2008-01-01

304

78 FR 72628 - Polyethylene Retail Carrier Bags From Thailand: Notice of Court Decision Not in Harmony With...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-549-821] Polyethylene Retail Carrier Bags From Thailand: Notice of Court Decision...duty order on polyethylene retail carrier bags (PRCBs) from Thailand.\\2\\ Consistent...dumping margins calculated for Thai Plastic Bags Industries Company (TPBI) and...

2013-12-03

305

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

PubMed

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

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

2013-01-01

306

Purification of porcine pancreatic lipase by aqueous two-phase systems of polyethylene glycol and potassium phosphate.  

PubMed

An aqueous two-phase system (ATPS) was applied for the purification of porcine pancreatic lipase (PPL) from crude PPL using polyethylene glycol (PEG) and potassium phosphate. Phase diagrams for polyethylene glycol (PEG) and potassium phosphate dibasic were determined at room temperature to find an operating region to first form the ATPS. The PPL was preferentially partitioned into the PEG-rich phase in systems with molecular weights of 1000 and 1500 and concentrated in the phosphate-rich phase in systems with PEG of 4000. Moreover, instead of tie line length (TLL), we used a stability ratio without NaCl in the system, and we first applied fluorescence spectroscopy for the protein conformational analysis of the ATPS. The molecular weight of the purified lipase was determined to be approximately 52 kDa by SDS-PAGE. The enzyme was efficiently purified in PEG 1500/potassium phosphate (17/13, %) at a pH of 7.0 at 4 °C. This system obtained an enzyme partition coefficient of 12.7, an extraction efficiency of 94.7% and a purification factor of approximately 4. These results demonstrate that the aqueous two-phase system is a highly efficient method for PPL purification. PMID:23562905

Zhou, Yu-Jie; Hu, Cheng-Li; Wang, Na; Zhang, Wei-Wei; Yu, Xiao-Qi

2013-05-01

307

A new method for transfer of polyethylene glycol-embedded tissue sections to silanated slides for immunocytochemistry.  

PubMed

Polyethylene glycol (PEG) is an excellent embedding medium for immunohistochemical studies. It provides structural preservation superior to frozen sections and increased sensitivity of antigen detection compared with paraffin sections. One limitation of PEG embedment is that PEG sections are difficult to handle and adhere poorly to glass slides. Here we present a simple and effective method for embedding tissues in PEG and transferring the resultant sections onto silanated glass slides. In addition, a method for silver enhanced colloidal gold immunostaining was combined with common dye staining to demonstrate the excellent structure preservation and sensitive antigen detection. Bovine chorionic membrane was fixed with Bouin's fixative, embedded in polyethylene glycol (PEG) 1500, cut into 5-microns sections, flattened over agarose blocks (10 x 10 x 2 mm3), and blotted onto Digene silanated slides. Slides were then washed in PBS, which removed the PEG and agarose blocks. Tissue sections were immunocytochemically stained with dilute antiserum raised in a rabbit against purified bovine placental retinol binding protein (bpRBP). Sections were washed and incubated with 1-nm colloidal gold-labeled goat anti-rabbit IgG. The immunogold particles were enhanced by silver staining (IGSS). Specimens were observed and photographed with an Olympus epipolarization microscope. The new method offered excellent morphological preservation of cell structure and the epipolarization microscopy provided high sensitivity for detection of specific immunogold-silver particles. PMID:2005376

Gao, K X; Godkin, J D

1991-04-01

308

Insulin particle formation in supersaturated aqueous solutions of poly(ethylene glycol).  

PubMed

Protein microspheres are of particular utility in the field of drug delivery. A novel, completely aqueous, process of microsphere fabrication has been devised based on controlled phase separation of protein from water-soluble polymers such as polyethylene glycols. The fabrication process results in the formation of spherical microparticles with narrow particle size distributions. Cooling of preheated human insulin-poly(ethylene glycol)-water solutions results in the facile formation of insulin particles. To map out the supersaturation conditions conducive to particle nucleation and growth, we determined the temperature- and concentration-dependent boundaries of an equilibrium liquid-solid phase separation. The kinetics of formation of microspheres were followed by dynamic and continuous-angle static light scattering techniques. The presence of PEG at a pH that was close to the protein's isoelectric point resulted in rapid nucleation and growth. The time elapsed from the moment of creation of a supersaturated solution and the detection of a solid phase in the system (the induction period, t(ind)) ranged from tens to several hundreds of seconds. The dependence of t(ind) on supersaturation could be described within the framework of classical nucleation theory, with the time needed for the formation of a critical nucleus (size <10 nm) being much longer than the time of the onset of particle growth. The growth was limited by cluster diffusion kinetics. The interfacial energies of the insulin particles were determined to be 3.2-3.4 and 2.2 mJ/m(2) at equilibrium temperatures of 25 and 37 degrees C, respectively. The insulin particles formed as a result of the process were monodisperse and uniformly spherical, in clear distinction to previously reported processes of microcrystalline insulin particle formation. PMID:16254391

Bromberg, Lev; Rashba-Step, Julia; Scott, Terrence

2005-11-01

309

Insulin Particle Formation in Supersaturated Aqueous Solutions of Poly(Ethylene Glycol)  

PubMed Central

Protein microspheres are of particular utility in the field of drug delivery. A novel, completely aqueous, process of microsphere fabrication has been devised based on controlled phase separation of protein from water-soluble polymers such as polyethylene glycols. The fabrication process results in the formation of spherical microparticles with narrow particle size distributions. Cooling of preheated human insulin-poly(ethylene glycol)-water solutions results in the facile formation of insulin particles. To map out the supersaturation conditions conducive to particle nucleation and growth, we determined the temperature- and concentration-dependent boundaries of an equilibrium liquid-solid phase separation. The kinetics of formation of microspheres were followed by dynamic and continuous-angle static light scattering techniques. The presence of PEG at a pH that was close to the protein's isoelectric point resulted in rapid nucleation and growth. The time elapsed from the moment of creation of a supersaturated solution and the detection of a solid phase in the system (the induction period, tind) ranged from tens to several hundreds of seconds. The dependence of tind on supersaturation could be described within the framework of classical nucleation theory, with the time needed for the formation of a critical nucleus (size <10 nm) being much longer than the time of the onset of particle growth. The growth was limited by cluster diffusion kinetics. The interfacial energies of the insulin particles were determined to be 3.2–3.4 and 2.2 mJ/m2 at equilibrium temperatures of 25 and 37°C, respectively. The insulin particles formed as a result of the process were monodisperse and uniformly spherical, in clear distinction to previously reported processes of microcrystalline insulin particle formation. PMID:16254391

Bromberg, Lev; Rashba-Step, Julia; Scott, Terrence

2005-01-01

310

Study of the Gelation Process of Polyethylene Oxidea -Polypropylene Oxideb -Polyethylene Oxidea Copolymer (Poloxamer 407) Aqueous Solutions  

PubMed

The gelation process of polyethylene oxidea -polypropylene oxideb -polyethylene oxidea copolymer (poloxamer 407) aqueous solutions is studied by means of FTIR spectroscopy, rheology, and differential scanning calorimetry (DSC). The C-O-C stretching bands of infrared spectra were found to shift toward higher wavenumbers with sol-gel transition, indicating that hydrogen bonding is not the driving force for gelation. Linear viscoelastic data provide an alternative method for gel point determination of these thermoreversible gels. The results obtained with this method are found to coincide with those obtained using DSC. Gel point temperatures determined by these methods are close to 14 degrees C for 25% (w/w) poloxamer 407 solutions and 10 degrees C for 30% (w/w) solutions. In gel state, the elastic modulus (G ') and dynamic viscosity (eta*) are found to be concentration and temperature independent for temperatures ranging from 20 to 35 degrees C. In light of our results, we suggest a mechanism of gelation based on micelles packing and entanglements. PMID:9241171

Cabana; Ait-Kadi; Juhasz

1997-06-15

311

Nd:Yag laser irradiation of single lap joints made by polyethylene and polyethylene doped by carbon nanomaterials  

NASA Astrophysics Data System (ADS)

Thermoplastic polyethylene can be welded by the transmission laser welding technique (TTLW) that exhibits some process related benefits with respect other conventional joining methods. This justifies its large use in wide fields, from the automotive to medical or domestic appliances. In this research, we studied single lap joints made by polyethylene pure and filled with carbon nanomaterials (0.2% in weight) to make the polymer laser absorbent. The joints were irradiated by a Nd:YAG laser operating at 1064 nm (first harmonic) with an intensity of 107 W/cm2 and 1 ÷ 30Hz, a maximum pulse energy of 300mJ and a laser spot of ? 1 cm2 (no focusing lens were employed). The joints were characterized by morphological analysis, mechanical shear tests and calorimetric analysis. The results suggested that the laser exposition time must be opportunely balanced in order to avoid a poor adhesion between the polymer sheets and to realized efficient joints. In particular the mechanical test showed that the laser exposition time of 40 seconds is the best conditions to obtain the highest shear strength of the joints of 140 N. After too prolonged laser exposure times, degrading phenomena starts.

Visco, A. M.; Brancato, V.; Cutroneo, M.; Torrisi, L.

2014-04-01

312

Enhancement of the predicted drug hepatotoxicity in gel entrapped hepatocytes within polysulfone-g-poly (ethylene glycol) modified hollow fiber  

SciTech Connect

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.

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

313

Elaboration et caracterisation de nanocomposites polyethylene/montmorillonite  

NASA Astrophysics Data System (ADS)

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.

Stoeffler, Karen

314

Relevance of the poly(ethylene glycol) linkers in peptide surfaces for proteases assays.  

PubMed

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

Trzcinska, Roza; Balin, Katarzyna; Kubacki, Jerzy; Marzec, Magdalena E; Pedrys, Roman; Szade, Jacek; Silberring, Jerzy; Dworak, Andrzej; Trzebicka, Barbara

2014-05-01

315

Subunit Stabilization and Polyethylene Glycolation of Cocaine Esterase Improves In Vivo Residence Time  

SciTech Connect

No small-molecule therapeutic is available to treat cocaine addiction, but enzyme-based therapy to accelerate cocaine hydrolysis in serum has gained momentum. Bacterial cocaine esterase (CocE) is the fastest known native enzyme that hydrolyzes cocaine. However, its lability at 37 C has limited its therapeutic potential. Cross-linking subunits through disulfide bridging is commonly used to stabilize multimeric enzymes. Herein we use structural methods to guide the introduction of two cysteine residues within dimer interface of CocE to facilitate intermolecular disulfide bond formation. The disulfide-crosslinked enzyme displays improved thermostability, particularly when combined with previously described mutations that enhance stability (T172R-G173Q). The newly modified enzyme yielded an extremely stable form of CocE (CCRQ-CocE) that retained greater than 90% of its activity after 41 days at 37 C, representing an improvement of more than 4700-fold over the wild-type enzyme. CCRQ-CocE could also be modified by polyethylene glycol (PEG) polymers, which improved its in vivo residence time from 24 to 72 h, as measured by a cocaine lethality assay, by self-administration in rodents, and by measurement of inhibition of cocaine-induced cardiovascular effects in rhesus monkeys. PEG-CCRQ elicited negligible immune response in rodents. Subunit stabilization and PEGylation has thus produced a potential protein therapeutic with markedly higher stability both in vitro and in vivo.

Narasimhan, Diwahar; Collins, Gregory T.; Nance, Mark R.; Nichols, Joseph; Edwald, Elin; Chan, Jimmy; Ko, Mei-Chuan; Woods, James H.; Tesmer, John J.G.; Sunahara, Roger K. (Michigan)

2012-03-15

316

Cellular Behavior of Human Adipose-Derived Stem Cells on Wettable Gradient Polyethylene Surfaces  

PubMed Central

Appropriate surface wettability and roughness of biomaterials is an important factor in cell attachment and proliferation. In this study, we investigated the correlation between surface wettability and roughness, and biological response in human adipose-derived stem cells (hADSCs). We prepared wettable and rough gradient polyethylene (PE) surfaces by increasing the power of a radio frequency corona discharge apparatus with knife-type electrodes over a moving sample bed. The PE changed gradually from hydrophobic and smooth surfaces to hydrophilic (water contact angle, 90º to ~50º) and rough (80 to ~120 nm) surfaces as the power increased. We found that hADSCs adhered better to highly hydrophilic and rough surfaces and showed broadly stretched morphology compared with that on hydrophobic and smooth surfaces. The proliferation of hADSCs on hydrophilic and rough surfaces was also higher than that on hydrophobic and smooth surfaces. Furthermore, integrin beta 1 gene expression, an indicator of attachment, and heat shock protein 70 gene expression were high on hydrophobic and smooth surfaces. These results indicate that the cellular behavior of hADSCs on gradient surface depends on surface properties, wettability and roughness. PMID:24477265

Ahn, Hyun Hee; Lee, Il Woo; Lee, Hai Bang; Kim, Moon Suk

2014-01-01

317

Crowning Proteins: Modulating the Protein Surface Properties using Crown Ethers**  

PubMed Central

Crown ethers are small, cyclic polyethers that have found wide-spread use in phase-transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein-crown ether co-crystals grown in the presence of 18-crown-6. We then employed biophysical methods and molecular dynamics simulations to compare these complexes with the corresponding apoproteins and with similar complexes with ring-shaped low-molecular-weight polyethylene glycols. Our studies show that crown ethers can modify protein surface behavior dramatically by stabilizing either intra- or intermolecular interactions. Consequently, we propose that crown ethers can be used to modulate a wide variety of protein surface behaviors, such as oligomerization, domain–domain interactions, stabilization in organic solvents, and crystallization. PMID:25287606

Lee, Cheng-Chung; Maestre-Reyna, Manuel; Hsu, Kai-Cheng; Wang, Hao-Ching; Liu, Chia-I; Jeng, Wen-Yih; Lin, Li-Ling; Wood, Richard; Chou, Chia-Cheng; Yang, Jinn-Moon; Wang, Andrew H-J

2014-01-01

318

Anaphylactic Shock Caused by Ingestion of Polyethylene Glycol  

PubMed Central

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

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

319

Photocarrier transport and trapping processes in doped polyethylene terephthalate films  

SciTech Connect

The radiation-induced conductivity of polyethylene terephthalate film is modified by doping this polymer with electron acceptor molecules. Detailed results of x-ray induced thermally stimulated current and photoconductivity experiments are reported for one dopant, 2, 4, 7-trinitro-9-fluorenone. At dopant concentrations< or approx. =10/sup 19/ molecules/cm/sup 3/, this impurity acts as a deep trap for photocarriers, radically decreasing the radiation-induced conductivity of the doped film. The kinetics of photocarrier trapping in a host material exhibiting dispersive transport is discussed. At dopant concentrations > or approx. =10/sup 20/ molecules/cm/sup 3/, the radiation-induced conductivity increases due to the onset of photocarrier transport among the electron acceptor molecules. Utilizing the physical processes discussed in this work, it is possible to develop dielectric materials displaying selected levels of radiation-induced conductivity.

Kurtz, S.R.; Arnold, C. Jr.

1985-04-01

320

Textural changes in metallurgical coke prepared with polyethylene  

NASA Astrophysics Data System (ADS)

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.

Gornostayev, Stanislav S.; Heino, Jyrki J.; Kokkonen, Tommi M. T.; Makkonen, Hannu T.; Huttunen, Satu M. M.; Fabritius, Timo M. J.

2014-10-01

321

Gels and foams from ultrahigh molecular weight polyethylene  

SciTech Connect

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.

Hair, L.M.; Letts, S.A.; Tillotson, T.

1988-07-01

322

Diplopia following porous polyethylene orbital rim onlay implant.  

PubMed

An 81-year-old man with ocular irritation associated with lower eyelid retraction, horizontal laxity of the lower eyelids, and hypoplastic inferior orbital rims underwent bilateral placement of porous polyethylene orbital rim onlay implants. Two weeks after surgery, he developed vertical binocular diplopia on downgaze. Examination of extraocular motility demonstrated limited infraduction OD. Surgical exploration revealed scarring in the anterior orbit between the inferior rectus pulley and the orbital implant. The orbital implant was found to lie higher than the inferior orbital rim. After surgical lysis of the scar and reduction of the vertical height of the implant, the patient's diplopia resolved. Orbital connective tissues critical to ocular motility may be abnormally superficial in orbital rim hypoplasia. Onlay grafts must be carefully placed so that they do not interfere with these tissues. PMID:12544800

Goldberg, Robert A; Li, Tina G; Demer, Joseph L

2003-01-01

323

The characterisation of two different degradable polyethylene (PE) sacks  

SciTech Connect

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.

Davis, G. [Engineering Management Group, University of Bristol (United Kingdom)]. E-mail: gudavis@cytanet.com.cy

2006-12-15

324

Simulation of polyethylene glycol and calcium-mediated membrane fusion  

SciTech Connect

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.

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

325

Compatibilization of a polyethylene/polyamide 6 blend nanocomposite  

NASA Astrophysics Data System (ADS)

Polymer blends of incompatible components need to be compatibilized to give rise to a blend with good properties. At the same way, polymer/clay nanocomposites show the same problem because of different chemical nature of the polymer matrix and of the clay. Compatibilization is then necessary if an incompatible polymer blend is filled with an organomodified clay. In this work a polyethylene/polyamide 6 blend filled with an organomodified clay has been compatibilized with a maleic anyhidride grafted SEBS (styrene-ethylene-butylene-styrene) copolymer and a glicidylmethacrylate-ethylene copolymer. The results show that compatibilization improves the mechanical properties in terms of elongation at break; furthermore, an unexpected effect has been found, since going from the isotropic to the anisotropic material, a fragile-ductile transition occurs, with a significant increase of the elongation values.

Mistretta, M. C.; Ceraulo, M.; La Mantia, F. P.; Morreale, M.

2014-05-01

326

Multilayer microfluidic poly(ethylene glycol) diacrylate hydrogels.  

PubMed

Development of robust, in vivo like tissues in vitro holds the potential to create regenerative medicine-based therapeutics, provide more physiologically significant preclinical models and supply a pharmacological and toxicological screening platform that reflects in vivo systems in both complexity and function. This protocol describes a simple, robust, multilayer replica molding technique in which poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) diacrylate (PEGDA) are serially replica molded to develop microfluidic PEGDA hydrogel networks embedded within independently fabricated PDMS housings, using a combination of soft and photo-lithography. This work has direct applications toward the development of robust, complex, cell-laden hydrogels for in vitro diagnostics and regenerative medicine applications. PMID:23329455

Cuchiara, Michael P; West, Jennifer L

2013-01-01

327

Polyethylene glycol aggregates in water formed through hydrophobic helical structures.  

PubMed

The present study was aimed at elucidating the mechanism of aggregation in water of hydroxyl-terminated polyethylene glycol (PEG) of low molecular weight (600 g/mol). The results from fluorescence spectroscopy at different temperatures were consistent with surface tension measurements, suggesting aggregate formation. Indeed, the process of aggregation is accompanied by an increase in the fluorescence emission of a hydrophobic probe. So, PEG aggregates in the form of internal hydrated helices covered with CH(2) groups are shown to yield hydrophobic regions. These regions created upon PEG aggregation in water and at a temperature close to 35°C result from a balance between H bonding and entropic effects. By providing the first experimental evidence for hydrophobic mediation of aggregation with OH-terminated oxy-ethylene chains of low molecular weight, this study highlights their surfactant-like behaviour. PMID:22608144

Azri, Aziz; Giamarchi, Philippe; Grohens, Yves; Olier, René; Privat, Mireille

2012-08-01

328

WEAR BEHAVIOR OF CARBON NANOTUBE/HIGH DENSITY POLYETHYLENE COMPOSITES.  

PubMed

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

Johnson, Brian B; Santare, Michael H; Novotny, John E; Advani, Suresh G

2009-10-01

329

Anaphylactic shock caused by ingestion of polyethylene glycol.  

PubMed

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

Lee, Sun Hee; Cha, Jae Myung; 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

330

Improved bowel care with a polyethylene glycol based bisacadyl suppository.  

PubMed

To test its effectiveness for bowel care in myopathy patients, a bisacodyl suppository based in polyethylene glycol (PEGBS) was compared with a conventional bisacodyl suppository based in hydrogenated vegetable oil (HVOBS). Nineteen patients with upper motor neuron paralysis received 57 HVOBS and 114 PEGBS trials in a crossover design. The average time for complete bowel evacuation was 2.4 (range 1.0 to 4.5) hours with HVOBS and 1.1 (range 0.3 to 1.8) hours with PEGBS. Three patients later discontinued the PEGBS because of cramps or fecal incontinence. The remaining 16 patients continued to use PEGBS for three years and 15 reported a sustained savings in time. It is concluded that the replacement of HVOBS with PEGBS will reduce bowel care time in myelopathy patients by about half. PMID:9144613

Frisbie, J H

1997-04-01

331

WEAR BEHAVIOR OF CARBON NANOTUBE/HIGH DENSITY POLYETHYLENE COMPOSITES  

PubMed Central

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

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

2009-01-01

332

Surface Modification of Polyethylene by Heparin for Improvement of Antithrombogenicity  

NASA Astrophysics Data System (ADS)

The purpose of this paper was to enhance blood compatibility of polyethylene (PE) film. PE film pretreated by argon plasma was subjected to ultraviolet (UV) -induced graft polymerization with Acrylic acid(AAc) (AAc-grafted PE films, PE-g-PAAc) without photo-initiator, then heparin was covalently immobilized on the PE surface (PE-g-HPAAc). The surface properties and microstructure of PE-g-PAAc and PE-g-HPAAc were studied by static contact angle measurement, atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and Attenuated total reflectance Fourier transfer infrared spectroscopy (ATR-FTIR). It was confirmed that AAc and heparin were successfully immobilized onto the surface of PE film. Results of platelet adhesion experiments indicated that the antithrombogenicity of the modified PE film was remarkably improved.

Zhao, Guowei; Chen, Yashao; Dong, Tao; Wang, Xiaoli

2007-04-01

333

Horseradish Peroxidase Inactivation: Heme Destruction and Influence of Polyethylene Glycol  

PubMed Central

Horseradish peroxidase (HRP) mediates efficient conversion of many phenolic contaminants and thus has potential applications for pollution control. Such potentially important applications suffer however from the fact that the enzyme becomes quickly inactivated during phenol oxidation and polymerization. The work here provides the first experimental data of heme consumption and iron releases to support the hypothesis that HRP is inactivated by heme destruction. Product of heme destruction is identified using liquid chromatography with mass spectrometry. The heme macrocycle destruction involving deprivation of the heme iron and oxidation of the 4-vinyl group in heme occurs as a result of the reaction. We also demonstrated that heme consumption and iron releases resulting from HRP destruction are largely reduced in the presence of polyethylene glycol (PEG), providing the first evidence to indicate that heme destruction is effectively suppressed by co-dissolved PEG. These findings advance a better understanding of the mechanisms of HRP inactivation. PMID:24185130

Mao, Liang; Luo, Siqiang; Huang, Qingguo; Lu, Junhe

2013-01-01

334

High-density polyethylene damage at extreme tensile conditions  

NASA Astrophysics Data System (ADS)

In-situ and postmortem 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 (>105 s-1) by firing projectiles through a conical die. Postmortem sectioning elucidates a mechanism of internal damage inception and progression. X-ray computed tomography corroborates shear damage with cracks nearly aligned with the extrusion axis but separated by unfailed internal bridges of material. In-situ measurements of damage are made with the impact system for ultrafast synchrotron experiments (IMPULSE) using the advanced imaging X-ray methods available at the Advanced Photon Source. Multiple frame phase-contrast imaging (PCI) elucidates the evolution of damage features in HDPE during Dyn-Ten-Ext loading that is observed in postmortem sectioning and X-ray tomography.

Brown, E. N.; Furmanski, J.; Ramos, K. J.; Dattelbaum, D. M.; Jensen, B. J.; Iverson, A. J.; Carlson, C. A.; Fezzaa, K.; Gray, G. T., III; Patterson, B. M.; Trujillo, C. P.; Martinez, D. T.; Pierce, T. H.

2014-05-01

335

Poly(ethylene glycol) Amphiphilic Copolymer for Anticancer Drugs Delivery.  

PubMed

Poly(ethylene glycol) is a water-soluble polymer. Due to its high safety and biocompatibility, it has been widely used to prepare amphiphilic copolymers for drug delivery. These copolymers can enhance water-solubility of hydrophobic drugs, improve their pharmacokinetic parameters and control their release from corresponding nanocarriers formed by its self-assembly. Anticancer drugs have some shortcoming such as lower water-solubility, bad targeting and some serious side-effects, which limit their applications and are dangerous to patients. So encapsulation of anticancer drugs into nanocarriers originated from its copolymeric derivates can improve their absorption, distribution, metabolism and excretion with better release properties and activities against cancer cells, increase their therapeutic effects, and realize their passive or active target delivery through structure modification. Recent research development of its drug delivery systems for anticancer drugs will be discussed. PMID:25420636

Feng, Runliang; Zhu, Wenxia; Teng, Fangfang; Liu, Na; Yang, Fengying; Meng, Ning; Song, Zhimei

2014-11-23

336

Pyrolysis pathways of sulfonated polyethylene, an alternative carbon fiber precursor.  

PubMed

Polyethylene is an emerging precursor material for the production of carbon fibers. Its sulfonated derivative yields ordered carbon when pyrolyzed under inert atmosphere. Here, we investigate its pyrolysis pathways by selecting n-heptane-4-sulfonic acid (H4S) as a model compound. Density functional theory and transition state theory were used to determine the rate constants of pyrolysis for H4S from 300 to 1000 K. Multiple reaction channels from two different mechanisms were explored: (1) internal five-centered elimination (Ei5) and (2) radical chain reaction. The pyrolysis of H4S was simulated with kinetic Monte Carlo (kMC) to obtain thermogravimetric (TGA) plots that compared favorably to experiment. We observed that at temperatures <550 K, the radical mechanism was dominant and yielded the trans-alkene, whereas cis-alkene was formed at higher temperatures from the internal elimination. The maximum rates of % mass loss became independent of initial ?H radical concentration at 440-480 K. Experimentally, the maximum % mass loss occurred from 440 to 460 K (heating rate dependent). Activation energies derived from the kMC-simulated TGAs of H4S (26-29 kcal/mol) agreed with experiment for sulfonated polyethylene (~31 kcal/mol). The simulations revealed that in this region, decomposition of radical HOS?2 became competitive to ?-H abstraction by HOS?2, making ?H the carrying radical for the reaction chain. The maximum rate of % mass loss for internal elimination was observed at temperatures >600 K. Low-scale carbonization utilizes temperatures <620 K; thus, internal elimination will not be competitive. E(i)5 elimination has been studied for sulfoxides and sulfones, but this represents the first study of internal elimination in sulfonic acids. PMID:23560686

Younker, Jarod M; Saito, Tomonori; Hunt, Marcus A; Naskar, Amit K; Beste, Ariana

2013-04-24

337

Poly(ethylene glycol)-mediated conformational alteration of ?-chymotrypsin prevents inactivation of insulin by stabilizing active intermediates.  

PubMed

Proteolytic enzymes in the gut represent one of the biggest barriers against oral delivery of therapeutic proteins and peptides. In the current study, we explored the effect of poly(ethylene glycol) 400 (PEG 400), a commonly used crowding agent, on insulin degradation mediated by ?-chymotrypsin (?-CT). Without PEG 400, insulin was quickly cleaved by ?-CT to generate inactive degradation products. In comparison, incorporation of PEG 400 resulted in reaction mixtures with retained biological activity. The analysis on the conformation of ?-CT and the local environment of the enzyme's active site unraveled that PEG 400 altered the conformation of ?-CT to prevent the inactivation of insulin via stabilization of active intermediates. These findings indicated that PEG 400 may provide a promising addition toward oral delivery of insulin. PMID:24720816

Yu, Jibing; Wei, Xiuli; Zhang, Li; Fang, Xiaocui; Yang, Tao; Huang, Feng; Liang, Wei

2014-10-01

338

Birefringence dispersion of polyethylene and cellulose triacetate sheets used as photonic wave retarders  

NASA Astrophysics Data System (ADS)

In a wide spectral range of 400 to 1000 nm, the channeled spectra formed from the interference of polarized white light are used to extract the dispersion of phase birefringence ?n(?) of polyethylene and cellulose triacetate (CTA) polymer sheets. The ?n(?) of polyethylene and CTA sheets is fitted to Cauchy dispersion function with relative error of order 1.2 and 4, respectively. The dispersion of group birefringence ?ng(?) of polyethylene and CTA is also calculated and fitted to Ghosh dispersion function with relative error of order 7 and 5, respectively. Furthermore, the phase and group retardations introduced by polyethylene and CTA sheets are also calculated. The amount of phase retardation confirms that polyethylene and CTA sheets can act as multiple order half and quarter wave plates working at many different wavelengths through the spectral range 400 to 1000 nm. For polyethylene and CTA sheets, a large difference between group and phase retardance is observed at a short wavelength (??400 nm), while such difference progressively diminished at a long wavelength (??1000 nm). Finally, a zero order polyethylene quarterwave plate working at 544 nm and dual wavelength CTA quarterwave plate working at 510 and 680 nm are experimentally realized.

Emam-Ismail, Mohamed

2013-05-01

339

Degradation of polyethylene by Trichoderma harzianum--SEM, FTIR, and NMR analyses.  

PubMed

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

Sowmya, H V; Ramalingappa; Krishnappa, M; Thippeswamy, B

2014-10-01

340

Influence of polyethylene glycol-300 addition on nanostructured lead sulfide thin films properties  

NASA Astrophysics Data System (ADS)

The concentration of polyethylene glycol-300 was found to play a crucial role in the formation of nanoparticles in PbS-chemical bath deposition process. We report here an endeavor to set up a relation between the variation of lead sulfide (PbS) nanocrystalline thin film properties, grown by (CBD) process at room temperature on corning glass and Si(100) substrates, with amount fluctuations of polyethylene glycol-300 in the solution. The transmittance of the films, for a fixed reaction time, increased up to ˜ 80% with the increase of % polyethylene glycol-300 in the solution, indicating the formation of very thin films due to the decrease of reaction rate with the increase of the concentration of polyethylene glycol-300. The optical band gaps were found to strongly rely on the composition of the bath deposition and increase with the increase of the polyethylene glycol-300 amount in the solution. Particle sizes between 2.8 and 8.7 nm were obtained by varying the % of polyethylene glycol-300 from 0.2 to 1.5. The concentration of polyethylene glycol-300 not only affects the reaction rate but also the morphology of the obtained films. PbS nanoparticles were found to be oriented preferentially along the < 200> plane. The absorption shifts towards short wavelength indicating a blue-shifting as a consequence of quantum confinement.

Kaci, S.; Keffous, A.; Trari, M.; Menari, H.; Manseri, A.; Mahmoudi, B.; Guerbous, L.

2010-09-01

341

FhuA deletion variant ?1-159 overexpression in inclusion bodies and refolding with Polyethylene-Poly(ethylene glycol) diblock copolymer.  

PubMed

Membrane protein isolation is a challenging problem. In fact especially their extraction from the respective membrane is difficult and often goes along with losses in yield. Usually expensive detergents are needed to extract the target protein from the membrane. Therefore finding an efficient overexpression and extraction method and an alternative to detergents is desirable. In this study we describe a new and fast method to express, extract and purify an engineered variant of the FhuA protein (FhuA ?1-159) that acts as passive diffusion channel, using a diblock copolymer as an alternative to detergents like octyl-POE (n-octylpolyoxyethylene). The N-terminal leader sequence, facilitating the protein's transport to the outer membrane was deleted (FhuA ?1-159 ?signal), resulting in protein accumulation in easy to isolate inclusion bodies. Urea was used to solubilise the unfolded protein and dialysis against phosphate-buffer containing the commercially available diblock copolymer PE-PEG[Polyethylene-Poly(ethyleneglycol)] lead to protein refolding. Circular dichroism spectroscopy revealed a high ?-sheet percentage within the refolded protein secondary structure indicating the successful reconstitution of FhuA ?1-159 ?signal native state. Furthermore the channel functionality of FhuA ?1-159 ?signal was verified by measuring the in and out-flux through the protein when inserted into liposome membrane, using the HRP/TMB (HRP=Horse Radish Peroxidase, TMB=3,3',5,5'-tetramethylbenzidine) assay system. PMID:21168506

Dworeck, Tamara; Petri, Anne-Kathrin; Muhammad, Noor; Fioroni, Marco; Schwaneberg, Ulrich

2011-05-01

342

Hot embossed polyethylene through-hole chips for bead-based microfluidic devices  

PubMed Central

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

Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N.; Christodoulides, Nicolaos; McDevitt, John T.

2013-01-01

343

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

344

Polyethylene glycol versus dual sugar assay for gastrointestinal permeability analysis: is it time to choose?  

PubMed Central

Background Increased intestinal permeability is an important measure of disease activity and prognosis. Currently, many permeability tests are available and no consensus has been reached as to which test is most suitable. The aim of this study was to compare urinary probe excretion and accuracy of a polyethylene glycol (PEG) assay and dual sugar assay in a double-blinded crossover study to evaluate probe excretion and the accuracy of both tests. Methods Gastrointestinal permeability was measured in nine volunteers using PEG 400, PEG 1500, and PEG 3350 or lactulose-rhamnose. On 4 separate days, permeability was analyzed after oral intake of placebo or indomethacin, a drug known to increase intestinal permeability. Plasma intestinal fatty acid binding protein and calprotectin levels were determined to verify compromised intestinal integrity after indomethacin consumption. Urinary samples were collected at baseline, hourly up to 5 hours after probe intake, and between 5 and 24 hours. Urinary excretion of PEG and sugars was determined using high-pressure liquid chromatography-evaporative light scattering detection and liquid chromatography-mass spectrometry, respectively. Results Intake of indomethacin increased plasma intestinal fatty acid-binding protein and calprotectin levels, reflecting loss of intestinal integrity and inflammation. In this state of indomethacin-induced gastrointestinal compromise, urinary excretion of the three PEG probes and lactulose increased compared with placebo. Urinary PEG 400 excretion, the PEG 3350/PEG 400 ratio, and the lactulose/rhamnose ratio could accurately detect indomethacin-induced increases in gastrointestinal permeability, especially within 2 hours of probe intake. Conclusion Hourly urinary excretion and diagnostic accuracy of PEG and sugar probes show high concordance for detection of indomethacin-induced increases in gastrointestinal permeability. This comparative study improves our knowledge of permeability analysis in man by providing a clear overview of both tests and demonstrates equivalent performance in the current setting. PMID:22888267

van Wijck, Kim; Bessems, Babs AFM; van Eijk, Hans MH; Buurman, Wim A; Dejong, Cornelis HC; Lenaerts, Kaatje

2012-01-01

345

Chemical characterization of diaspirin cross-linked hemoglobin polymerized with poly(ethylene glycol).  

PubMed

A lack of specificity associated with chemical modification methods used in the preparation of certain hemoglobin (Hb)-based oxygen carriers (HBOCs) may alter Hb structure and function, as amino acids located in critical regions (e.g., alpha-beta interfaces and the 2,3-DPG binding pocket) may unintentionally be targeted. Hb protein surface modifications with various poly(ethylene glycol) (PEG) derivatives have been used as conjugating and polymerizing agents with the intent of improving reaction site specificity/reproducibility and ultimately reducing the untoward hypertensive response due to nitric oxide scavenging by smaller molecular size tetrameric species (i.e., 64 kDa) in HBOC solutions. Previous experiments performed in our laboratory have evaluated the influence of polymerization of diaspirin alpha-alpha cross-linked Hb (alphaalpha-DBBF-Hb) with a bifunctional modified PEG, bis(maleoylglycylamide) PEG (BMAA-PEG), in terms of oxygen carrying capacity, redox properties, hypertensive response, and renal clearance in rats. The data presented in this paper specifically evaluate the influence of BMAA-PEG on alphaalpha-DBBF-Hb (Poly-alphaalpha-DBBF-Hb) to identify molecular weight distribution, protein conformation, and site-specific modification, as well as to provide insight into the previously determined in vitro and in vivo functional and vasoactive characteristics of this HBOC. Chemical analysis performed herein reveals nonspecific modifications induced by BMAA-PEG that result in the full modification of alphaalpha-DBBF-Hb leaving no tetrameric cross-linked starting material in solution. These data are inconsistent with the continuing assumption that molecular size (i.e., 64 kDa) has a direct influence on HBOC-mediated vasoactivity and that other protective strategies should be considered to control blood pressure imbalances. PMID:16808476

Buehler, Paul W; Boykins, Robert A; Norris, Scott; Alayash, Abdu I

2006-07-01

346

Enhanced resolution of low molecular weight poly(ethylene glycol) in nanopore analysis.  

PubMed

A design with conjugation of DNA hairpin structure to the poly(ethylene glycol) molecule was presented to enhance the temporal resolution of low molecular weight poly(ethylene glycol) in nanopore studies. By the virtue of this design, detection of an individual PEG with molecular weight as low as 140 Da was achieved at the single-molecule level in solution, which provides a novel strategy for characterization of an individual small molecule within a nanopore. Furthermore, we found that the current duration time of poly(ethylene glycol) was scaled with the relative molecular weight, which has a potential application in single-molecule detection. PMID:25457124

Cao, Chan; Ying, Yi-Lun; Gu, Zhen; Long, Yi-Tao

2014-12-16

347

Degradation of fipronil (Termidor) in aqueous solution stored in polyethylene tanks exposed to sunlight or shade.  

PubMed

Pest Management Professionals commonly use polyethylene or fiberglass tanks for mixing and applying termiticides. We investigated the stability of fipronil (Termidor SC) (0.06%, 0.09% and 0.125% active ingredient) in aqueous solutions stored in polyethylene tanks under sun and shade for 2 week. Chemical analysis of tank-mixed solutions sampled at 0, 24, 48, 72, 168 and 336 h indicated that fipronil remained stable. Our data indicated that polyethylene tanks prevent fipronil from photodegradation and these tanks can be safely used for short term storage (up to 2 week) of liquid termiticides. PMID:19156343

Husen, T J; Spomer, N A; Kamble, S T

2009-05-01

348

High electrical field degradation in polymeric dielectrics: Electrical tree formation and growth in polyethylene  

Microsoft Academic Search

Undoped low-density polyethylene conductivity is given by, s=m˙NcN T˙rtot˙e-W\\/ kT˙eEqa\\/2kT where m is carrier mobility, W = 0.87 eV is the trap depth, a = 2.8 nm is the trap site separation. For doped polyethylene and high-density polyethylene, the conductivity is given as, s=2nl NciNT rtoti+Ncd NTr totde- 4+W\\/kT 1Esinh Eql2kT eEqa\\/2kT where W = 0.87 eV, 4 = 0.3

Grace Ge Jiang

1999-01-01

349

Graphite/Ultra-High Modulus Polyethylene Hybrid Fiber Composites with Epoxy and Polyethylene Matrices for Cosmic Radiation Shielding  

NASA Technical Reports Server (NTRS)

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.

2003-01-01

350

Highly crosslinked polyethylene does not reduce the wear in total knee arthroplasty: in vivo study of particles in synovial fluid.  

PubMed

The aim was to assess if the reduction in polyethylene wear with highly crosslinked polyethylene suggested by studies with knee simulators is confirmed in patients with a knee arthroplasty. The use of a conventional or a highly crosslinked polyethylene was randomly assigned intraoperatively. Twelve months after surgery a knee arthrocentesis was performed and the synovial fluid of 17 patients in each group was studied analysing the number, size and shape of the polyethylene particles by scanning electron microscope. We found no significant differences in the concentration, size or morphology of polyethylene particles between groups. The great variability in the number of particles between individuals suggests that in vivo polyethylene wear depends on many factors and probably the type of polyethylene is not the most significant. PMID:23507066

Hinarejos, Pedro; Piñol, Ignasi; Torres, Alberto; Prats, Eva; Gil-Gómez, Gabriel; Puig-Verdie, Lluis

2013-09-01

351

The interfacial diffusion of chromium(III) fumarato coordination compound in the formation of aluminum-polyethylene composite film  

NASA Astrophysics Data System (ADS)

The aqueous solution of chromium(III) fumarato coordination compound (Volan 82) is a coupling agent developed by DuPont in the early 1970's. The application of Volan 82 in the production of aluminum-polyethylene composite film greatly improves the water-resistance and durability of the composite film. Our previous studies demonstrated the chemical bonding between aluminum oxide and chromium(III) fumarato coordination compound. In this paper, AES is reported for the studies of the solvent-resistance of the interfacial polyethylene of the composite film. The AES sputter depth profile of the aluminum-polyethylene interfacial layer demonstrated that the chromium(III) fumarato coupling agent diffused into the interfacial polyethylene layer during the formation of aluminum-polyethylene composite film. This was confirmed by ESCA, when chromium was detected in the interfacial polyethylene layer. The interfacial diffusion of the coupling agent improves the adhesion between aluminum and polyethylene of the composite film.

Yang, Charles Q.; Zhou, Qin-Li

1985-09-01

352

Hemocompatibility and anti-biofouling property improvement of poly(ethylene terephthalate) via self-polymerization of dopamine and covalent graft of zwitterionic cysteine.  

PubMed

Inspired by the composition of adhesive proteins in mussels, we used self-polymerized dopamine to form a thin and surface-adherent polydopamine layer onto poly(ethylene terephthalate) (PET) sheet, followed by covalent grafting cysteine (Cys) to improve hemocompatibility and anti-biofouling property. The obtained surfaces were characterized by water contact angle measurements (WCA), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. The results of platelet adhesion and protein adsorption tests showed that cysteine immobilized PET was endowed with improved resistance to nonspecific protein adsorption and platelet adhesion. The results of hemolysis rate test showed cysteine grafted PET (PET-g-Cys) had low hemolytic ability. Cell assay results showed that PET-g-Cys surface could greatly inhibit HeLa cell adhesion. These works provide an ideal hemocompatible and antifouling surface for biomedical applications. PMID:23735748

Li, Pengfei; Cai, Xianmei; Wang, Ding; Chen, Shuangchun; Yuan, Jiang; Li, Li; Shen, Jian

2013-10-01

353

Quantification of the influence of protein-protein interactions on adsorbed protein structure and bioactivity.  

PubMed

While protein-surface interactions have been widely studied, relatively little is understood at this time regarding how protein-surface interaction effects are influenced by protein-protein interactions and how these effects combine with the internal stability of a protein to influence its adsorbed-state structure and bioactivity. The objectives of this study were to develop a method to study these combined effects under widely varying protein-protein interaction conditions using hen egg-white lysozyme (HEWL) adsorbed on silica glass, poly(methyl methacrylate), and polyethylene as our model systems. In order to vary protein-protein interaction effects over a wide range, HEWL was first adsorbed to each surface type under widely varying protein solution concentrations for 2h to saturate the surface, followed by immersion in pure buffer solution for 15h to equilibrate the adsorbed protein layers in the absence of additionally adsorbing protein. Periodic measurements were made at selected time points of the areal density of the adsorbed protein layer as an indicator of the level of protein-protein interaction effects within the layer, and these values were then correlated with measurements of the adsorbed protein's secondary structure and bioactivity. The results from these studies indicate that protein-protein interaction effects help stabilize the structure of HEWL adsorbed on silica glass, have little influence on the structural behavior of HEWL on HDPE, and actually serve to destabilize HEWL's structure on PMMA. The bioactivity of HEWL on silica glass and HDPE was found to decrease in direct proportion to the degree of adsorption-induce protein unfolding. A direct correlation between bioactivity and the conformational state of adsorbed HEWL was less apparent on PMMA, thus suggesting that other factors influenced HEWL's bioactivity on this surface, such as the accessibility of HEWL's bioactive site being blocked by neighboring proteins or the surface itself. The developed methods provide an effective means to characterize the influence of protein-protein interaction effects and provide new molecular-level insights into how protein-protein interaction effects combine with protein-surface interaction and internal protein stability effects to influence the structure and bioactivity of adsorbed protein. PMID:23751416

Wei, Yang; Thyparambil, Aby A; Latour, Robert A

2013-10-01

354

Improved performance of ultra-high molecular weight polyethylene for orthopedic applications  

E-print Network

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...

Plumlee, Kevin Grant

2009-05-15

355

SCRATCHING VULNERABILITY OF CONVENTIONAL VS. HIGHLY CROSSLINKED POLYETHYLENE LINERS DUE TO LARGE EMBEDDED THIRD BODY PARTICLES  

PubMed Central

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

Heiner, Anneliese D.; Galvin, Alison L.; Fisher, John; Callaghan, John J.; Brown, Thomas D.

2011-01-01

356

75 FR 49900 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Preliminary Results of Antidumping...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Terephthalate Film, Sheet, and Strip From Brazil: Preliminary Results of Antidumping Duty...sheet, and strip (PET film) from Brazil. This administrative review covers one...antidumping duty order on PET film from Brazil. See Polyethylene Terephthalate...

2010-08-16

357

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...

358

A method for using polyethylene passive samplers to measure polycyclic aromatic hydrocarbon chemical activity in sediments  

E-print Network

In order to aid in the determination of the hazards posed by hydrophobic organic compounds (HOCs) in sediment beds, a method for the use of polyethylene (PE) sheets as passive sampling devices for measuring chemical ...

Fernandez, Loretta A. (Loretta Ana)

2005-01-01

359

Methods for increasing the thermal conductivity of ultra-high molecular weight polyethylene (UHMWPE)  

E-print Network

A two-part study was conducted to determine methods for producing ultra-high molecular weight polyethylene with high thermal conductivity by way of polymer chain orientation. The first portion of this report surveys current ...

Miler, Josef L

2006-01-01

360

Fracture of Two Moderately Cross-Linked Polyethylene Tibial Inserts in a TKR Patient  

PubMed Central

Highly cross-linked polyethylene has become the gold standard in total hip replacement for its wear resistance. Moderately crosslinked polyethylene is now available for total knee replacement (TKR), although concerns about reduced mechanical strength have prevented widespread adoption. The purpose of this report is to describe an unusual case where a patient underwent cruciate retaining TKR using a moderately crosslinked polyethylene tibial insert that went on to fracture twice in the same location across the primary and first revision surgery. The first tibial insert was 10?mm thick and was implanted for 16 months. The second tibial insert was 15?mm thick and was implanted for 11 months. Both fractured along the posterior aspect of the medial articular surface. The lack of a specific event leading to these fractures and the fact that they occurred twice in the same location in the same patient suggest that caution is still necessary regarding the introduction of crosslinked polyethylene for TKR surgery. PMID:24511401

Teeter, Matthew G.; McAuley, James P.; Naudie, Douglas D.

2014-01-01

361

21 CFR 878.5000 - Nonabsorbable poly(ethylene terephthalate) surgical suture.  

Code of Federal Regulations, 2014 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.5000 Nonabsorbable poly(ethylene terephthalate) surgical suture. (a)...

2014-04-01

362

21 CFR 878.5000 - Nonabsorbable poly(ethylene terephthalate) surgical suture.  

Code of Federal Regulations, 2012 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.5000 Nonabsorbable poly(ethylene terephthalate) surgical suture. (a)...

2012-04-01

363

21 CFR 878.5000 - Nonabsorbable poly(ethylene terephthalate) surgical suture.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.5000 Nonabsorbable poly(ethylene terephthalate) surgical suture. (a)...

2011-04-01

364

21 CFR 878.5000 - Nonabsorbable poly(ethylene terephthalate) surgical suture.  

Code of Federal Regulations, 2013 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.5000 Nonabsorbable poly(ethylene terephthalate) surgical suture. (a)...

2013-04-01

365

Discrimination of transparent polyethylene films based on identification of inorganic antiblocking agents.  

PubMed

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

Hashimoto, Takashi; Mizuhata, Minoru

2012-05-01

366

Superior thermal conductivity and extremely high mechanical strength in polyethylene chains from ab initio calculation  

NASA Astrophysics Data System (ADS)

The upper limit of the thermal conductivity and the mechanical strength are predicted for the polyethylene chain, by performing the ab initio calculation and applying the quantum mechanical non-equilibrium Green's function approach. Specially, there are two main findings from our calculation: (1) the thermal conductivity can reach a high value of 310 Wm-1 K-1 in a 100 nm polyethylene chain at room temperature and the thermal conductivity increases with the length of the chain; (2) the Young's modulus in the polyethylene chain is as high as 374.5 GPa, and the polyethylene chain can sustain 32.85%±0.05% (ultimate) strain before undergoing structural phase transition into gaseous ethylene.

Jiang, Jin-Wu; Zhao, Junhua; Zhou, Kun; Rabczuk, Timon

2012-06-01

367

Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP)  

Microsoft Academic Search

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

D. S. Achilias; C. Roupakias; P. Megalokonomos; A. A. Lappas; ?. V. Antonakou

2007-01-01

368

Observation of electron transport in polyethylene terephthalate and the radiation hardening of dielectrics  

SciTech Connect

Electron-induced conductivity measurements were performed on polyethylene terephthalate to compare electron and hole contributions to the radiation-induced conductivity. The electron mobility in this material was found to be > or approx. =10/sup 2/ times that of the holes. This result explains an earlier observation that the radiation-induced conductivity of polyethylene terephthalate can be radically reduced by chemically doping this dielectric with electron acceptor molecules.

Kurtz, S.R.

1985-06-01

369

Polyethylene Particle-Induced Bone Resorption in Substance P-Deficient Mice  

Microsoft Academic Search

Aseptic loosening is the major cause of total joint replacement failure. Substance P (SP) is a neurotransmitter richly distributed\\u000a in sensory nerve fibers, bone, and bone-related tissue. The purpose of this study was to investigate the potential impact\\u000a of SP on bone metabolism in polyethylene particle-induced osteolysis. We utilized the murine calvarial osteolysis model based\\u000a on ultrahigh molecular weight polyethylene

C. Wedemeyer; C. Neuerburg; A. Pfeiffer; A. Heckelei; F. von Knoch; G. Hilken; J. Brankamp; F. Henschke; M. von Knoch; F. Löer; G. Saxler

2007-01-01

370

Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements.  

PubMed

Osteolysis induced by ultra high molecular weight polyethylene wear debris is one of the primary factors limiting the lifespan of total hip replacements. Crosslinking polyethylene is known to improve its wear resistance in certain industrial applications, and crosslinked polyethylene acetabular cups have shown improved wear resistance in two clinical studies. In the present study, crosslinked polyethylene cups were produced by two methods. Chemically crosslinked cups were produced by mixing a peroxide with ultra high molecular weight polyethylene powder and then molding the cups directly to shape. Radiation-crosslinked cups were produced by exposing conventional extruded ultra high molecular weight polyethylene bar stock to gamma radiation at various doses from 3.3 to 100 Mrad (1 Mrad = 10 kGy), remelting the bars to extinguish residual free radicals (i.e., to minimize long-term oxidation), and then machining the cups by conventional techniques. In hip-joint simulator tests lasting as long as 5 million cycles, both types of cross-linked cups exhibited dramatically improved resistance to wear. Artificial aging of the cups by heating for 30 days in air at 80 degrees C induced oxidation of the chemically crosslinked cups. However, a chemically crosslinked cup that was aged 2.7 years at room temperature had very little oxidation. Thus, whether substantial oxidation of chemically crosslinked polyethylene would occur at body temperature remains unclear. The radiation-crosslinked remelted cups exhibited excellent resistance to oxidation. Because crosslinking can reduce the ultimate tensile strength, fatigue strength, and elongation to failure of ultra high molecular weight polyethylene, the optimal crosslinking dose provides a balance between these physical properties and the wear resistance of the implant and might substantially reduce the incidence of wear-induced osteolysis with total hip replacements. PMID:10221831

McKellop, H; Shen, F W; Lu, B; Campbell, P; Salovey, R

1999-03-01

371

Fixation of ultrahigh-molecular-weight polyethylene liners to metal-backed acetabular cups  

Microsoft Academic Search

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,

Victor G. Williams; Leo A. Whiteside; Stephen E. White; Daniel S. McCarthy

1997-01-01

372

Fire retardancy of a reactively extruded intumescent flame retardant polyethylene system enhanced by metal chelates  

Microsoft Academic Search

A reactive extrusion technology was adopted to synthesize a flame retardant (ER), based on the esterification of melamine phosphate and pentaerythritol. The ER imparts good flame retardancy and non-dripping for polyethylene (PE) when combined with ammonium polyphosphate to yield an intumescent polyethylene (PE–IFR). The performance of this intumescent system has been enhanced by the addition of small amounts (0.2%) chelated

De-Yi Wang; Yun Liu; Yu-Zhong Wang; C. Perdomo Artiles; T. Richard Hull; Dennis Price

2007-01-01

373

Effect of Polyethylene on Osteocalcin, Alkaline Phosphatase and Procollagen Secretion by Human Osteoblastic Cells  

Microsoft Academic Search

.   We have studied the direct effects of polyethylene particles on osteoblastic function in primary human bone cell cultures.\\u000a The cells were obtained from trabecular bone fragments of patients undergoing knee reconstructive surgery. When the cells\\u000a reached confluency, they were subcultured into two flasks, one untreated (control culture) and the other treated with polyethylene\\u000a particles, and incubated until confluency. Osteoblastic

M. E. Martínez; S. Medina; M. T. del Campo; M. J. Sánchez-Cabezudo; M. Sánchez; L. Munuera

1998-01-01

374

[Microstructural characterization for pyrolysis hydrogenation fragments in polyethylene by pyrolysis hydrogenation gas chromatography/mass spectrometry].  

PubMed

The microstructural characterization of 47 samples, respectively of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), copolymer of ethylene and alpha-olefins, was performed by pyrolysis hydrogenation gas chromatography/mass spectrometry (Py-H-GC/MS) with 10% Pt on 80-100 mesh Diasolid H as a hydrogenation catalyst. The samples were obtained from 12 domestic plants and 12 plants abroad as well. The sample sizes ranging from 30 to 80 microg were pyrolyzed at 770 degrees C in a flow of hydrogen carrier gas. It was found that short methyl branches as the characteristic isoalkanes of pyrolysis hydrogenation in polyethylene would be related closely to the different classes of polyethylene. The microstructural characterization has been carried out by means of Py-H-GC/MS, according to the relative amount of the four short methyl branches, 5-methyldodecane (5-MC12), 4-methyldodecane (4-MC12), 2-methyldodecane (2-MC12) and 3-methyldodecane (3-MC12) existed in C12-C13 isoalkanes. The Py-H-GC/MS technique will be providing further scientific evidences for the characterization of polyethylene plastics in forensic science. PMID:17165536

Ding, Junkai; Song, Ming; Huang, Li

2006-09-01

375

Utility of high density porous polyethylene implants in maxillofacial surgery.  

PubMed

The aim of this paper was to determine the utility of high density porous polyethylene implants (HDPE) in a variety of facial skeletal deformities. Sixteen patients (age range 14-28 years) with facial deformities requiring skeletal defect reconstruction or augmentation, treated between January 2008 and December 2010. The follow-up of the patients ranged from 6 months to 2 years.The types of deformities and defects treated include: one patient each with hemifacial microsomia and nasal tip correction, two patients each with malar deformities and orbital floor reconstruction, three patients with paranasal deformities and mandibular hypoplasia and four patients with chin augmentation. A total of 24 implants were placed. The complications included infection and wound dehiscence in one patient. The implants were palpable extraorally in two patients. It is concluded that HDPE is an excellent alternative to autogenous grafts for facial skeletal augmentation. Its porous nature, excellent soft tissue growth and coverage are the advantages and disadvantages include its rigidity and sometimes it is palpable extraorally. PMID:24644395

Rai, Anshul; Datarkar, Abhay; Arora, Aakash; Adwani, D G

2014-03-01

376

Dielectric relaxation spectroscopy of polyethylene terephthalate (PET) films  

NASA Astrophysics Data System (ADS)

The dielectric properties of biaxially stretched polyethylene terephthalate (PET) films of 0022-3727/30/11/003/img6 thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 0022-3727/30/11/003/img7 Hz and the temperature range 0022-3727/30/11/003/img8C. Differencial scanning calorimetry (DSC), in the range 0022-3727/30/11/003/img9C, was employed to investigate the thermal properties of the PET samples. Besides measuring the 0022-3727/30/11/003/img10 relaxation associated with the glass transition and the secondary 0022-3727/30/11/003/img11 relaxation, special attention has been paid to the investigation of DC-conductivity-related effects. They give rise to high dielectric permittivity values and dielectric losses at low frequencies and high temperatures. The results are analysed within the complex permittivity formalism and discussed in terms of interfacial Maxwell - Wagner - Sillars polarization, the 0022-3727/30/11/003/img12 peak, conductivity relaxation, space-charge polarization, electrode polarization and DC conductivity. DC conductivity values determined from frequency plots of the AC conductivity follow the Vogel - Tamman - Fulcher equation at temperatures higher than the glass transition temperature, indicating that the charge-carrier transport mechanism is governed by the motion of the polymeric chains. On the basis of the temperature dependence of the DC conductivity PET is classified as a fragile system.

Neagu, E.; Pissis, P.; Apekis, L.; Gomez Ribelles, J. L.

1997-06-01

377

Evaluation of the Refractive Index of Thin Transparent Polyethylene Terephthalatefilms  

NASA Astrophysics Data System (ADS)

The properties of refractive index and thickness in thin transparent films were evaluated many years ago utilizing various optical techniques. Many of the more modern techniques involved the measurement of various film properties using interferometry. Until the early 1980s, interferometers were generally prohibited from routinely operating in the visible light region due to the requirements for exacting alignment of many of the optical components. Despite the wealth of literature, the alignment of films with the dielectric axes for measurements of the refractive index and also polarized vibrational analysis, have not been considered. Additionally, most of these publications assume either a film thickness or a refractive index referenced from others work. The work presented herein details several methods that can be used to determine both the film thickness and the refractive indices of polyethylene terephthalate films. Results indicate that the polarization axes only coincidentally lie along the draw axis; no film studied in this work had an axis along the draw axis. The refractive indices for the minor and major axes were found to be 1.61 and 1.63, respectively.

Brangan, James R.

378

Surface modification of polypropylene membrane by polyethylene glycol graft polymerization.  

PubMed

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

Abednejad, Atiye Sadat; Amoabediny, Ghasem; Ghaee, Azadeh

2014-09-01

379

Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate  

PubMed Central

Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example. PMID:24357897

Rogers, Chad I.; Oxborrow, Joseph B.; Anderson, Ryan R.; Tsai, Long-Fang; Nordin, Gregory P.; Woolley, Adam T.

2013-01-01

380

Biphasic liquid mixtures of ionic liquids and polyethylene glycols.  

PubMed

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

Rodríguez, Héctor; Francisco, María; Rahman, Mustafizur; Sun, Ning; Rogers, Robin D

2009-12-14

381

Mesophases in polyethylene, polypropylene, and poly(1-butene)  

SciTech Connect

This paper contains new views about the amorphous and partially ordered phases of the three polymers listed in the title. The discussion is based on information on structure, thermodynamic stability, and large-amplitude molecular motion. Polyethylene is the basic backbone of all alkene polymers, and the other two are the first members of the vinyl polymers which have stereospecifically placed alkyl side chains. Their multiphase structures consist of metastable crystals, mesophases, and surrounding rigid and mobile amorphous fractions. All these phases have sizes ranging from micrometer dimensions down to nanometers. Besides the phase structures, information about the molecular coupling between the phases must be considered. Depending on temperature, the polymer phases can vary from solid (rigid) to liquid (mobile). New knowledge is also gained by cross-comparison of the title polymers. The experimental information was gained from (a) various forms of slow, fast, and temperature-modulated thermal analysis to identify equilibrium and non-equilibrium states, (b) measurement of structure and morphology at various length scales, and (c) tracing of the large-amplitude molecular motion, the kinetics of order/disorder changes, and the liquid/solid transitions (glass transitions). It is shown that much more needs to be known about the various phases and their coupling to characterize a given polymer and to fine-tune its properties for a given application.

Androsch, Rene J [ORNL; Di Lorenzo, Maria [ORNL; Schick, Christoph [Rostock University, Rostock, Germany; Wunderlich, Bernhard {nmn} [ORNL

2010-01-01

382

High Speed Deformation of the Poly(Ethylene Terephthalate)  

NASA Astrophysics Data System (ADS)

Mechanical behaviour of amorphous and semi-crystalline polyethylene terephthalate films is studied over five decades of strain rates, at temperatures below and above the glass transition. The data were obtained by combining measurements from conventional Instron machine with data from a high-speed tensile machine. The activation parameters are determined and compared with the activation process of the ? relaxation. Different modes of failure have been identified and the occurrence of an intermediate mode between ductile and brittle failure is shown. The brittle-ductile transition is estimated for each testing conditions and compared to the adiabatic-isothermal transition. Le comportement mécanique du Poly(éthylène téréphthalate) amorphe et semi-cristallin est étudié sur plus de cinq ordres de grandeurs de vitesse de déformation, de part et d'autre de la température de transition vitreuse. Les mesures expérimentales sont réalisées à l'aide d'une machine de traction Instron, pour les faibles vitesses de déformation, et d'une machine servo-hydraulique pour les grandes vitesses. Les paramètres d'activation sont déterminés et comparés à ceux de la relaxation secondaire basse température ?. Différents modes de rupture sont identifiés; entre une rupture typiquement ductile et une rupture fragile, un mode de rupture intermédiaire est mis en évidence. La transition ductile-fragile est estimée pour chaque condition d'essai, et comparée à la transition isotherme-adiabatique.

Ladouce, L.; Perez, J.; Vassoille, R.

1996-01-01

383

Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate.  

PubMed

Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example. PMID:24357897

Rogers, Chad I; Oxborrow, Joseph B; Anderson, Ryan R; Tsai, Long-Fang; Nordin, Gregory P; Woolley, Adam T

2014-02-01

384

Polyethylene sebacate-doxorubicin nanoparticles for hepatic targeting.  

PubMed

The present study discusses polyethylene sebacate (PES)-doxorubicin (DOX) nanoparticles (PES-DOX NP) using pullulan as asialoglycoprotein receptor (ASGPR) ligand for hepatic targeting. Pullulan, a hydrophilic polymer served as ligand and as stealth agent. PES-DOX NP were prepared by modified nanoprecipitation using PES and Gantrez AN 119 (Gantrez), as complexing agent in the organic phase, while DOX was dissolved in the aqueous phase. Pullulan was adsorbed on the formed nanoparticles (PES-DOX-PUL). Intimate association of PES and Gantrez, and ionic complexation of DOX with Gantrez (confirmed by FTIR), coupled with rapidity of nanoprecipitation resulted in nanoparticles with high entrapment efficiency and high drug loading. Nanoparticles were successfully freeze dried. Drug release from PES NP followed zero order kinetics. PES-DOX NP and PES-DOX-PUL exhibited low hemolytic potential and good serum stability. Comparative biodistribution study in rats using (99m)Tc labeled formulations revealed higher blood concentration and lower liver concentration of PES-DOX-PUL, confirming the long circulating nature of PES-DOX-PUL, and thereby the possibility of improved targeting to hepatocytes. Nanoparticles revealed lower DOX concentration in the heart suggestive of low cardiotoxicity. Our study presents a radically different yet simple approach for the design of PES-DOX nanoparticles with high drug loading for improved therapy in hepatic cancer. PMID:20854883

Guhagarkar, Swati A; Gaikwad, Rajiv V; Samad, Abdul; Malshe, Vinod C; Devarajan, Padma V

2010-11-30

385

Polyethylene glycol influences microbial interactions with intestinal epithelium.  

PubMed

There is emerging evidence that polyethylene glycol (PEG), widely used as a bowel preparation before surgery, may protect the intestinal epithelium from microbial invasion. Experiments were designed to study the effects of both low-molecular-weight (LMW; 3.35 kd) and high-molecular-weight (HMW; 15-20 kd) PEG on interactions of Escherichia coli, Candida albicans, and Candida glabrata with intestinal epithelium (these three intestinal microbes are frequently involved in systemic infection in shock and trauma patients.) In vitro experiments studied the effects of PEG on mature Caco-2 enterocytes. Using the gentamicin protection assay, both HMW and LMW PEG inhibited E. coli internalization by Caco-2 enterocytes. Using an immunosorbent assay, both HMW and LMW PEG inhibited C. albicans and C. glabrata adherence to Caco-2 enterocytes. Scanning electron micrographs of Caco-2 cells incubated in HMW or LMW PEG showed globular material distributed randomly over the epithelial surface, and apical microvilli seemed distorted. As an in vivo correlate to these experiments, separate groups of antibiotic-treated mice were orally associated with either E. coli, C. albicans, or C. glabrata, and cohort groups were given drinking water containing 5% HMW or 5% LMW PEG. Cecal colonization of E. coli was decreased in mice given HMW but not LMW PEG. Cecal colonization with C. albicans or C. glabrata was decreased in mice given either HMW or LMW PEG. These data provide further evidence that PEG may decrease microbial colonization and microbial interactions with intestinal epithelium. PMID:18665048

Henry-Stanley, Michelle J; Wells, Carol L

2009-04-01

386

Simulation of polyethylene-moderated plutonium neutron multiplicity measurements  

NASA Astrophysics Data System (ADS)

Neutron multiplicity measurements are a useful technique for the characterization of special nuclear material. This technique relies on the detection of correlated neutrons from fission events. As correlated events are detected it is possible to determine the neutron multiplicity distribution for the sample. This distribution is useful for identifying the material and estimating the mass. This work focuses on the ability of the Monte Carlo code MCNP-PoliMi to simulate measured distributions. The experiment used as the basis of comparison consisted of a 4.5 kg plutonium metal sphere surrounded by up to 6 in. of polyethylene. A bank of 15 3He detectors was used to detect the correlated neutron events. MCNP-PoliMi was used to simulate the particle transport and a post-processing algorithm was developed to apply detector deadtime effects and to determine the neutron multiplicity distributions. These simulated distributions were then compared to the measured results. The simulation provided an adequate estimation of the measured data. However, we observed a systematic over-prediction in both the mean and the variance of the measured distribution.

Miller, E. C.; Dennis, B.; Clarke, S. D.; Pozzi, S. A.; Mattingly, J. K.

2011-10-01

387

Calvarial reconstruction using high-density porous polyethylene cranial hemispheres  

PubMed Central

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

Mokal, Nitin J.; Desai, Mahinoor F.

2011-01-01

388

The application of polyethylene glycol (PEG) to electron microscopy  

PubMed Central

The cytoplasm of cells from a variety of tissues has been viewed in sections (0.25-1 micrometers) devoid of any embedding resin. Glutaraldehyde- and osmium tetroxide-fixed tissues were infiltrated and embedded in a water-miscible wax, polyethylene glycol (PEG), and subsequently sectioned on dry glass or diamond knives. The PEG matrix was removed and the sections were placed on Formvarcarbon-polylysine- coated grids, dehydrated, dried by the critical-point method, and observed in either the high- or low-voltage electron microscope. Stereoscopic views of cells devoid of embedding resin present an image of cell utrastructure unobscured by electron-scattering resins similar to the image of whole, unembedded critical-point-dried or freeze-dried cultured cells observed by transmission electron microscopy. All organelles, including the cytoskeletal structures, are identified and appear not to have been damaged during processing, although membrane components appear somewhat less distinct. The absence of an embedding matrix eliminates the need for additional staining to increase contrast, unlike the situation with specimens embedded in standard electron-scattering resins. The PEG technique thus appears to be a valuable adjunct to conventional methods for ultrastructural analysis. PMID:7400222

1980-01-01

389

Diffusion in Binary Polyethylene Blends: Role of Constraint Release  

NASA Astrophysics Data System (ADS)

In support of our Monte-Carlo simulations, we have used the proton pulsed-gradient NMR method to augment our earlier diffusion measurements in n-alkane and polyethylene (PE) melts and blends with three series of blends at T = 150 deg. C across the full concentration (c) range. Blends were based on M = 33k PE and contained either n-C50 alkane, M = 1.8k PE, or M = 6.7k PE. The results again agree with our theoretical synthesis(1) involving a smooth transition from Rouse to reptational behavior including constraint release (CR) and free-volume host effects which depend on T, M, and c. Tube dilation is assumed contained in the CR mechanism; contour length fluctuations are not considered to affect center-of-mass diffusion. The generalized CR term not only reproduces the c- and M-dependences of the self-diffusion of both species in fully entangled blends, but also supplants entanglement dilution in blends of PE with (unentangled) n-C50 and n-C12 (our earlier work), thus shifting from spatial to temporal constraint at all M in homologous blends. (1) E. von Meerwall, et al., J. Chem. Phys. 111, 750 (1999); E. von Meerwall, et al., Polymer Prepr. 44, 287 (2003).

von Meerwall, E. D.; Dirama, N.; Mattice, W. L.

2004-03-01

390

Physicochemical characterization of nimodipine-polyethylene glycol solid dispersion systems.  

PubMed

This study investigates the solid-solid interactions between nimodipine (NIM) and polyethylene glycol (PEG) of different mean molecular weights (PEG 2000, 4000 and 6000), in solid dispersion systems, applying differential scanning calorimetry (DSC), Fourier-Transform infrared spectroscopy, powder X-ray diffraction (PXRD), hot stage microscopy (HSM) and theoretical modeling by the Flory-Huggins (FH) solution theory. Phase diagrams constructed with the aid of DSC and FH solution theory showed sensitivity on the estimated values of the FH interaction parameter (?). When ? is considered a constant number (??=??, ????0), formation of a eutectic mixture is predicted in the 70-80% w/w PEG concentration region, while when ? was considered as a function of concentration and temperature (??=?f(?,?)), the model predicts the formation of monotectic systems. Construction of more precise phase diagrams by HSM to the aid of Kofler's "contact preparation" method confirmed the monotectic nature of the examined systems. Studies on NIM's re-crystallization process in the solid dispersions revealed a strong dependence of the crystallization rate, as well as the resulting crystal form, on the mean molecular weight and concentration of PEG: NIM crystallization rates decrease as PEG's MW increases, while NIM mod II crystals predominate in dispersions prepared at temperatures above NIM's liquidus and growth of NIM mod I prevailing in PEG-rich samples. PMID:23611475

Barmpalexis, Panagiotis; Kachrimanis, Kyriakos; Georgarakis, Emanouil

2014-07-01

391

Conversion of post consumer polyethylene to the biodegradable polymer polyhydroxyalkanoate.  

PubMed

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

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

392

A New Polyethylene Scattering Law Determined Using Inelastic Neutron Scattering  

SciTech Connect

Monte Carlo neutron transport codes such as MCNP rely on accurate data for nuclear physics cross-sections to produce accurate results. At low energy, this takes the form of scattering laws based on the dynamic structure factor, S (Q, E). High density polyethylene (HDPE) is frequently employed as a neutron moderator at both high and low temperatures, however the only cross-sections available are for T =300 K, and the evaluation has not been updated in quite some time. In this paper we describe inelastic neutron scattering measurements on HDPE at 5 and 300 K which are used to improve the scattering law for HDPE. We describe the experimental methods, review some of the past HDPE scattering laws, and compare computations using these models to the measured S (Q, E). The total cross-section is compared to available data, and the treatment of the carbon secondary scatterer as a free gas is assessed. We also discuss the use of the measurement itself as a scattering law via the 1 phonon approximation. We show that a scattering law computed using a more detailed model for the Generalized Density of States (GDOS) compares more favorably to this experiment, suggesting that inelastic neutron scattering can play an important role in both the development and validation of new scattering laws for Monte Carlo work.

Lavelle, Christopher M [ORNL; Liu, C [Oak Ridge National Laboratory (ORNL); Stone, Matthew B [ORNL

2013-01-01

393

Coarse-grained models for aqueous polyethylene glycol solutions.  

PubMed

A new coarse-grained force field is developed for polyethylene glycol (PEG) in water. The force field is based on the MARTINI model but with the big multipole water (BMW) model for the solvent. The polymer force field is reparameterized using the MARTINI protocol. The new force field removes the ring-like conformations seen in simulations of short chains with the MARTINI force field; these conformations are not observed in atomistic simulations. We also investigate the effect of using parameters for the end-group that are different from those for the repeat units, with the MARTINI and BMW/MARTINI models. We find that the new BMW/MARTINI force field removes the ring-like conformations seen in the MARTINI models and has more accurate predictions for the density of neat PEG. However, solvent-separated-pairs between chain ends and slow dynamics of the PEG reflect its own artifacts. We also carry out fine-grained simulations of PEG with bundled water clusters and show that the water bundling can lead to ring-like conformations of the polymer molecules. The simulations emphasize the pitfalls of coarse-graining several molecules into one site and suggest that polymer-solvent systems might be a stringent test for coarse-grained force fields. PMID:24350686

Choi, Eunsong; Mondal, Jagannath; Yethiraj, Arun

2014-01-01

394

Incipient and Progressive Damage in Polyethylene Under Extreme Tensile Conditions  

SciTech Connect

The Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) test was developed at LANL by Gray and coworkers to probe the tensile response of materials at large strains (>1) and high strain-rates (>1000/s) by firing projectiles through a conical die at 300-700 m/s. This technique has recently been applied to various polymers, such as the fluoropolymers PTFE (Teflon) and the chemically similar PCTFE, which respectively exhibited catastrophic fragmentation and distributed dynamic necking. This work details investigations of the Dyn-Ten-Ext response of high density polyethylene, both to failure and sub-critical conditions. At large extrusion ratios ({approx}7.4) and high velocities, such as those previously employed, HDPE catastrophically fragmented in a craze-like manner in the extruded jet. At more modest extrusion ratios and high velocities the specimen extruded a stable jet that ruptured cleanly, and at lower velocities was recovered intact after sustaining substantial internal damage. Thermomechanical finite element simulations showed that the damage corresponded to a locus of shear stress in the presence of hydrostatic tension. X-ray computed tomography corroborated the prediction of a shear damage mechanism by finding the region of partially damaged material to consist of macroscopic shear-mode cracks nearly aligned with the extrusion axis, originating from the location of damage inception.

Furmanski, Jevan [Los Alamos National Laboratory; Brown, Eric [Los Alamos National Laboratory; Trujillo, Carl P. [Los Alamos National Laboratory; Martinez, Daniel Tito [Los Alamos National Laboratory; Gray, George T. III [Los Alamos National Laboratory

2012-06-07

395

Nondestructive inspection of heat fusion joints in polyethylene piping  

SciTech Connect

Polyethylene (PE) piping has found wide use in chemical processing, water transportation, and gas distribution applications because it is lightweight, corrosion resistant, and easy to join in the field. Common joining methods include electrofusion and butt fusion. The mechanical integrity of joints is highly dependent upon the installation parameters; including cleanliness of the pipe face, pipe end alignment, pressure applied during fusion, and temperature of the ends during fusion. Typical installation defects can include foreign debris in the weld, e.g. grass, grease, dirt; weak welds; and debonds. Many times, visual inspection of the weld will not detect these defects, and the cost of repairing a joint after it is placed in service is exorbitant. This has generated interest in developing a nondestructive evaluation (NDE) method that can detect defects during installation. This paper reviews several NDE methods that have been applied to inspection of PE butt welds. Specially designed NDE equipment is also discussed. This overview paper addresses NDE techniques for inspection of butt welds in PE piping during installation. Several NDE approaches are evaluated for applicability to this inspection. Factors evaluated include time duration of test and ability to detect various defects.

Austin, R.K. [Texas Research Institute Austin, Inc., TX (United States)

1997-12-01

396

Mechanical and swelling characterization of poly(N-isopropyl acrylamide -co- methoxy poly(ethylene glycol) methacrylate) sol-gels.  

PubMed

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

Pollock, Jacob F; Healy, Kevin E

2010-04-01

397

Physicochemical and biomechanical examination of surfaces of retrieved polyethylene heads from total hip prostheses with rotating polyethylene head system.  

PubMed

In order to assess whether hydrodynamic lubrication occurs in total hip prostheses with a rotating polyethylene (PE) head system (R-THP), several physicochemical, morphological, and biomechanical tests were carried out. R-THPs have been used in more than 1000 patients since 1970, and 12 PE heads, retrieved from 10 patients after an average of 24.5 years since total hip arthroplasty (THA), were employed for the tests. The weight-bearing area of the PE surface was light yellow in color and considerably oxidized, but no wear scars were observed. In the non-weight-bearing area, in contrast, discoloration and oxidation were hard to detect. The weight-bearing surface of the PE head became smoother with time after THA, and the friction coefficient did not differ significantly from that of an unused PE head. The radial clearance between head and socket decreased at a temperature of 17 degrees C, which is equivalent to the difference between room temperature and the temperature of the human body. Scanning electron microscopy showed a fine undulating pattern, which suggested that hydrodynamic lubrication could occur in the rotating PE head system. PMID:11793172

Katayama, K; Maezawa, H; Uesato, N; Sasada, T

2001-01-01

398

Study on the synthesis and properties of mussel mimetic poly(ethylene glycol) bioadhesive.  

PubMed

The catecholic amino acid 3,4-Dihydroxyphenyl-l-alanine (DOPA) is believed to be responsible for the water-resistant adhesive characteristics of mussel adhesive proteins (MAPs). In this paper, the synthesis of three-armed poly(ethylene glycol)s with dopamine endgroups (PEG-DOPAs) using acylation reaction and Michael addition reaction was described, and PEG-DOPAs was used as bioadhesive under the UV irradiation. The structures of PEG-DOPAs were characterized by FTIR, (1)H NMR spectroscopy. The adhesion properties of PEG-DOPAs were investigated and results were significantly superior to 0.05MPa of the commercially available fibrin adhesives. Moreover, the adhesive strength of PEG-DOPAs (Mw 3000) increased from 0.587MPa to 1.82MPa, PEG-DOPAs (Mw 20,000) increased from 0.338MPa to 1.92MPa with the elongation of the binding time, severally. The photopolymerization kinetic study was taken to evaluate gelation time of bioadhesive indirectly. The cytotoxicity of photocured PEG-DOPAs hydrogels for L929 cells was evaluated by the fluorescence microscopy and MTT (3-[4-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; Thiazolyl blue) assay, respectively. The results showed that PEG-DOPAs were biocompatible and less cytotoxicity toward the growth of L929 cells. The swelling properties of PEG-DOPAs hydrogels were also tested. PEG-DOPAs (3000) reached swelling equilibrium within 2h at 37°C, and PEG-DOPAs (20,000) within 6h at 37°C. PMID:23266052

Ai, Yufei; Wei, Yaohua; Nie, Jun; Yang, Dongzhi

2013-03-01

399

Synthesis and gelation of DOPA-modified poly(ethylene glycol) hydrogels.  

PubMed

3,4-Dihydroxyphenylalanine (DOPA) residues are known for their ability to impart adhesive and curing properties to mussel adhesive proteins. In this paper, we report the preparation of linear and branched DOPA-modified poly(ethylene glycol)s (PEG-DOPAs) containing one to four DOPA endgroups. Gel permeation chromatography-multiple-angle laser light scattering analysis of methoxy-PEG-DOPA in the presence of oxidizing reagents (sodium periodate, horseradish peroxidase, and mushroom tyrosinase) revealed the formation of oligomers of methoxy-PEG-DOPA, presumably resulting from oxidative polymerization of DOPA endgroups. In the case of PEG-DOPAs containing two or more DOPA endgroups, oxidative polymerization resulted in polymer network formation and rapid gelation. The amount of time required for gelation of aqueous PEG-DOPA solutions was found to be as little as 1 min and was dependent on the polymer architecture as well as the type and concentration of oxidizing reagent used. Analysis of reaction mixtures by UV-vis spectroscopy allowed the identification of reaction intermediates and the elucidation of reaction pathways. On the basis of the observed reaction intermediates, oxidation of the catechol side chain of DOPA resulted in the formation of highly reactive DOPA-quinone, which further reacted to form cross-linked products via one of several pathways, depending on the presence or absence of N-terminal protecting groups on the PEG-DOPA. N-Boc protected PEG-DOPA cross-linked via phenol coupling and quinone methide tanning pathways, whereas PEG-DOPA containing a free amino group cross-linked via a pathway that resembled melanogenesis. Similar differences were observed for the rate of gel formation as well as the molecular weight between cross-links ((-)M(c)), calculated using equilibrium swelling and the Flory-Rehner equation. PMID:12217051

Lee, Bruce P; Dalsin, Jeffrey L; Messersmith, Phillip B

2002-01-01

400

Structure and conservation of a polyethylene glycol-degradative operon in sphingomonads.  

PubMed

Sphingopyxis terrae, and Sphingopyxis macrogoltabida strains 103 and 203, can degrade polyethylene glycols (PEGs). They differ in the following respects: (i) different substrate specificities (chain length) of assimilable PEG, (ii) PEG-inducible or constitutive PEG-degradative proteins, and (iii) symbiotic or axenic degradation of PEG. S. terrae was able to incorporate PEG 6000, but strain 103 could not incorporate more than PEG 4000, suggesting that the difference in assimilable PEG chain length depends on the ability to take up substrate. PEG-degradative genes (pegB, C, D, A, E and R) from these strains were cloned. Their primary structures shared a high homology of more than 99 %. The peg genes encode a TonB-dependent receptor (pegB), a PEG-aldehyde dehydrogenase (pegC), a permease (pegD), a PEG dehydrogenase (pegA) and an acyl-CoA ligase (pegE), and in the opposite orientation, an AraC-type transcription regulator (pegR). The peg operon was flanked by two different sets of transposases. These three strains contained large plasmids and the operon was located in one of the large plasmids in S. terrae. The peg genes could be detected in other PEG-degrading sphingomonads. These results suggest that the peg genes have evolved in a plasmid-mediated manner. An insertion of a transposon gene (pegF) between pegD and pegA in strain 203 was found, which caused the constitutive expression of pegA in this strain. PMID:17259605

Tani, Akio; Charoenpanich, Jittima; Mori, Terumi; Takeichi, Mayuko; Kimbara, Kazuhide; Kawai, Fusako

2007-02-01

401

Preparation of poly(ethylene glycol)/polylactide hybrid fibrous scaffolds for bone tissue engineering  

PubMed Central

Polylactide (PLA) electrospun fibers have been reported as a scaffold for bone tissue engineering application, however, the great hydrophobicity limits its broad application. In this study, the hybrid amphiphilic poly(ethylene glycol) (PEG)/hydrophobic PLA fibrous scaffolds exhibited improved morphology with regular and continuous fibers compared to corresponding blank PLA fiber mats. The prepared PEG/PLA fibrous scaffolds favored mesenchymal stem cell (MSC) attachment and proliferation by providing an interconnected porous extracellular environment. Meanwhile, MSCs can penetrate into the fibrous scaffold through the interstitial pores and integrate well with the surrounding fibers, which is very important for favorable application in tissue engineering. More importantly, the electrospun hybrid PEG/PLA fibrous scaffolds can enhance MSCs to differentiate into bone-associated cells by comprehensively evaluating the representative markers of the osteogenic procedure with messenger ribonucleic acid quantitation and protein analysis. MSCs on the PEG/PLA fibrous scaffolds presented better differentiation potential with higher messenger ribonucleic acid expression of the earliest osteogenic marker Cbfa-1 and mid-stage osteogenic marker Col I. The significantly higher alkaline phosphatase activity of the PEG/PLA fibrous scaffolds indicated that these can enhance the differentiation of MSCs into osteoblast-like cells. Furthermore, the higher messenger ribonucleic acid level of the late osteogenic differentiation markers OCN (osteocalcin) and OPN (osteopontin), accompanied by the positive Alizarin red S staining, showed better maturation of osteogenic induction on the PEG/PLA fibrous scaffolds at the mineralization stage of differentiation. After transplantation into the thigh muscle pouches of rats, and evaluating the inflammatory cells surrounding the scaffolds and the physiological characteristics of the surrounding tissues, the PEG/PLA scaffolds presented good biocompatibility. Based on the good cellular response and excellent osteogenic potential in vitro, as well as the biocompatibility with the surrounding tissues in vivo, the electrospun PEG/PLA fibrous scaffolds could be one of the most promising candidates in bone tissue engineering. PMID:22163160

Ni, PeiYan; Fu, ShaoZhi; Fan, Min; Guo, Gang; Shi, Shuai; Peng, JinRong; Luo, Feng; Qian, ZhiYong

2011-01-01

402

Local effect of IL-4 delivery on polyethylene particle induced osteolysis in the murine calvarium  

PubMed Central

Wear particles generated with use of total joint replacements incite a chronic macrophage-mediated inflammatory reaction, which leads to implant failure. Macrophage activation may be polarized into two states, with an M1 proinflammatory state dominating an alternatively activated M2 anti-inflammatory state. We hypothesized that IL-4, an activator of M2 macrophages, could modulate polyethylene (PE) particle-induced osteolysis in an experimental murine model. Four animal groups included (a) calvarial saline injection with harvest at 14 days (b) single calvarial injection of PE particles subcutaneously (SC) without IL-4 (c) PE particles placed as in (b), then IL-4 given SC for 14 consecutive days and (d) PE particles as in (b) then IL-4 beginning 7 days after particle injection for 7 days. The calvarial bone volume to total tissue volume was measured using microCT and histomorphometry. Calvaria were cultured for 24 h to assess release of RANKL, OPG, TNF-?, and IL-1ra and isolation and identification of M1 and M2 specific proteins. MicroCT and histomorphometric analysis showed that bone loss was significantly decreased following IL-4 administration to PE treated calvaria for both 7 and 14 days. Western blot analysis showed an increased M1/M2 ratio in the PE treated calvaria, which decreased with addition of IL-4. Cytokine analysis showed that the RANKL/OPG ratio and TNF-?/IL-1ra ratio decreased in PE-treated calvaria following IL-4 addition for 14 days. IL-4 delivery mitigated PE particle-induced osteolysis through macrophage polarization. Modulation of macrophage polarization is a potential treatment strategy for wear particle induced periprosthetic osteolysis. PMID:23225668

Rao, Allison J.; Nich, Christophe; Dhulipala, Lakshmi S.; Gibon, Emmanuel; Valladares, Roberto; Zwingenberger, Stefan; Smith, R. Lane; Goodman, Stuart B.

2014-01-01

403

Clinical performance of a highly cross-linked polyethylene at two years in total hip arthroplasty: a randomized prospective trial  

Microsoft Academic Search

We report the 2-year results for a prospective randomized trial comparing highly cross-linked with standard polyethylene in total hip replacements. In our study, 46 hips were available for radiographic analysis at 2- and 3-year follow-up. Femoral bearings were 28-mm cobalt chrome with the polyethylene insert randomly selected at the time of implantation to be highly cross-linked polyethylene (Crossfire; Stryker Howmedica

John M Martell; James J Verner; Stephen J Incavo

2003-01-01

404

The morphology of blends of linear and branched polyethylenes  

SciTech Connect

The state of mixing in blends of high density (HD), low density (LD) and linear low density (LLD) polyethylenes (PE) in the melt and solid states has been examined by small-angle x-ray and neutron scattering (SAXS and SANS). In the melt, SANS results indicate that HDPE/LDPE mixtures (with 1-2 branches/100 C) form a single phase. HDPE/LLDPE blends are also homogeneous when the branch content is low, but phase separate as the branching increases. In the solid state, after slow-cooling from the melt, the HDPE/LDPE system segregates into domains {approximately}10{sup 2} in size. For high concentrations of linear polymer ({phi} {ge} 0.5), there are separate stacks of HDPE and LDPE lamellae, and the measured SANS cross section agrees closely with the theoretical calculation based on the assumption of complete phase separation of the components. For predominantly branched blends ({phi} < 0.5), the phase segregation is less complete, and the components are separated within the same lamellar stack. Moreover, the phases no longer consist of the pure components, and the HDPE lamellae contain up to 15% LDPE. The segregation of components in the solid state is a consequence of crystallization mechanisms and the blend morphology is a strong function of the cooling rate. Rapid quenching to -78{degrees}C produces only one lamellar stack and these blends show extensive cocrystallization. Samples quenched less rapidly (e.g., into water at 23{degrees}C) show a similar structure to slowly cooled samples. The solid state morphology also depends on the type of branching and differences between HDPE/LDPE and HDPE/LLDPE blends will be reviewed.

Wignall, G.D.; Londono, J.D. [Oak Ridge National Labs., TN (United States); Alamo, R.G.; Mandelkern, L. [Florida State Univ., Tallahassee, FL (United States)

1995-12-31

405

Various-sourced pectin and polyethylene oxide electrospun fibers.  

PubMed

Pectin, a naturally occurring and biorenewable polysaccharide, is derived from plant cell wall tissue and used in applications ranging from food processing to biomedical engineering. Due to extraction methods and source variation, there is currently no consensus in literature as to the exact structure of pectin. Here, we have studied key material properties of electrospun pectin blends with polyethylene oxide (PEO) (1:1, v/v) in order to demonstrate the fabrication of a fibrous and less toxic material system, as well as to understand the effects of source variability on the resulting fibrous mats. The bulk pectin degree of esterification (DE) estimated using FTIR (bulk apple pomace (AP)=28%, bulk citrus peel (CP)=86% and bulk sugar beet pulp (SBP)=91%) was shown to inversely correlate with electrospun fiber crystallinity determined using XRD (PEO-AP=37%, PEO-CP=28% and PEO-SBP=23%). This in turn affected the trend observed for the mean fiber diameter (n=50) (PEO-AP=124 ± 26 nm, PEO-CP=493 ± 254 nm and PEO-SBP=581 ± 178 nm) and elastic tensile moduli (1.6 ± 0.2 MPa, 4.37 ± 0.64 MPa and 2.49 ± 1.46 MPa, respectively) of the fibrous mats. Electrospun fibers containing bulk AP had the lowest DE, highest crystallinity, smallest mean fiber diameter, and lowest tensile modulus compared to either the bulk CP or bulk SBP. Bound water in PEO-CP fiber and bulk pectin impurities in PEO-SPB were observed to influence fiber branching and mean diameter distributions, which in turn influenced the fiber tensile properties. These results indicate that pectin, when blended with PEO in water, produces submicron fibrous mats with pectin influencing the blend fiber properties. Moreover, the source of pectin is an important variable in creating electrospun blend fibrous mats with desired material properties. PMID:24702925

Rockwell, Pamela L; Kiechel, Marjorie A; Atchison, Jennifer S; Toth, Laura J; Schauer, Caroline L

2014-07-17

406

SANS study of highly resilient poly(ethylene glycol) hydrogels.  

PubMed

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

Saffer, Erika M; Lackey, Melissa A; Griffin, David M; Kishore, Suhasini; Tew, Gregory N; Bhatia, Surita R

2014-03-28

407

Robust Identification of Polyethylene Terephthalate (PET) Plastics through Bayesian Decision  

PubMed Central

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

Zulkifley, Mohd Asyraf; Mustafa, Mohd Marzuki; Hussain, Aini; Mustapha, Aouache; Ramli, Suzaimah

2014-01-01

408

Permeation Resistance of Chlorinated Polyethylene Against Hydrazine Fuels  

NASA Technical Reports Server (NTRS)

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.

Waller, J. M.; Williams, J. H.

1999-01-01

409

Polyethylene glycol induced mouse model of retinal degeneration.  

PubMed

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness. This study was done to characterize dry AMD-like changes in mouse retinal pigment epithelium (RPE) and retina after polyethylene glycol (PEG) treatment. We injected male C57BL/6 mice subretinally with PBS, 0.025, 0.25, 0.5 and 1.0 mg of PEG-400 and the animals were sacrificed on day 5. Eyes were harvested and processed for histological analysis. In all other experiments 0.5 mg PEG was injected and animals were sacrificed on days 1, 3, 5 or 14. Paraffin, 5 ?m and plastic, 1 ?m and 80 nm sections were used for further analysis. Subretinal injection of 0.5 mg PEG induced a 32% reduction of outer nuclear layer (ONL) thickness, 61% decrease of photoreceptor outer and inner segment length, 49% decrease of nuclear density in the ONL and 31% increase of RPE cell density by day 5 after injection. The maximum level of TUNEL positive nuclei in the ONL (6.8 + 1.99%) was detected at day 5 after PEG injection and co-localized with Casp3act. Histological signs of apoptosis were observed in the ONL by light or electron microscopy. Degeneration of RPE cells was found in PEG injected eyes. Gene expression data identified several genes reported to be involved in human AMD. C3, Cfi, Serping1, Mmp9, Htra1 and Lpl were up-regulated in PEG injected eyes compared to PBS controls. PEG leads to morphological and gene expression changes in RPE and retina consistent with dry AMD. This model will be useful to investigate dry AMD pathogenesis and treatment. PMID:25088354

Lyzogubov, Valeriy V; Bora, Nalini S; Tytarenko, Ruslana G; Bora, Puran S

2014-10-01

410

Polyacrylamide gel miniaturization improves protein visualization and autoradiographic detection  

SciTech Connect

Polyacrylamide gels shrink to one-quarter of their original area when soaked in a 50% (w/v) solution of polyethylene glycol. Gel miniaturization improves the contrast of protein bands, with four valuable consequences. (i) A 5- to 10-fold increase in sensitivity for Coomassie blue is observed. (ii) Gels are more durable; i.e., they resist tearing when wet and they do not crack during drying under vacuum. (iii) Shrunken gels give sharper photographic images and provide better interlane protein band comparisons. (iv) Condensed protein bands lead to an increased sensitivity for detecting low-abundance, radioactively-labeled proteins by fluorography.

Mohamed, M.A.; Lerro, K.A.; Prestwich, G.D.

1989-03-01

411

Inspection of the Engineered FhuA DC/D4L Protein Nanopore by Polymer David J. Niedzwiecki,  

E-print Network

Inspection of the Engineered FhuA DC/D4L Protein Nanopore by Polymer Exclusion David J. Niedzwiecki Extensive engineering of protein nanopores for biotechnological applications using native scaffolds requiresA DC/D4L nanopore. We employed water-soluble poly(ethylene glycols) and dextran polymers to examine

Movileanu, Liviu

412

Isolation and characterization of a gene encoding a polyethylene glycol-induced cysteine protease in common wheat.  

PubMed

Plant cysteine protease (CP) genes are induced by abiotic stresses such as drought, yet their functions remain largely unknown. We isolated the full-length cDNA encoding a Triticum aestivum CP gene, designated TaCP, from wheat by the rapid amplification of cDNA ends (RACE) method. Sequence analysis revealed that TaCP contains an open reading frame encoding a protein of 362 amino acids, which is 96% identical to barley cysteine protease HvSF42. The TaCP transcript level in wheat seedlings was upregulated during polyethylene glycol (PEG) stress, with a peak appearing around 12 h after treatment. TaCP expression level increased rapidly with NaCl treatment at 48 h. TaCP responded strongly to low temperature (4 degree C) treatment from 1 h post-treatment and reached a peak of about 40-fold at 72 h. However, it showed only a very slight response to abscisic acid (ABA). More than one copy of TaCP was present in each of the three genomes of hexaploid wheat and its diploid donors. TaCP fused with green fluorescent protein (GFP) was located in the plasma membrane of onion epidermis cells. Transgenic Arabidopsis plants overexpressing TaCP showed stronger drought tolerance and higher CP activity under water-stressed conditions than wild-type Arabidopsis plants. The results suggest that TaCP plays a role in tolerance to water deficit. PMID:20826947

Zang, Qing-Wei; Wang, Cai-Xiang; Li, Xu-Yan; Guo, Zhi-Ai; Jing, Rui-Lian; Zhao, Jun; Chang, Xiao-Ping

2010-09-01

413

Comparison of the binding mode of plasmid DNA to allylamine plasma polymer and poly(ethylene glycol) surfaces  

NASA Astrophysics Data System (ADS)

Concomitant with the development of advanced biomaterials and other biodevices, the precise control of biomolecule-surface interactions is becoming increasingly important. Of particular interest are devices presenting functional DNA either for hybridization or for uptake by cells. Such devices are poised to underpin advanced genomic studies and DNA therapy. However, these devices require an in-depth understanding of how specific biomolecules interact with particular surfaces. This report investigates how DNA interacts with two coatings commonly used for the control of protein and cell-surface interactions on biomedical devices, focusing on the nature of the DNA-surface interactions. The coatings were produced by allylamine plasma polymerization (ALAPP) and subsequent high-density grafting of poly(ethylene glycol) (PEG). While the low protein binding nature of such coatings has been shown before, we show here that PEG grafted surfaces also exhibit significantly reduced attachment of double-stranded plasmid DNA with an equilibrium constant of 680 ml/mg as compared with 1600 ml/mg for ALAPP modified surfaces. Given these findings, there is scope to produce two-dimensionally controlled DNA adsorption patterns on spatially patterned ALAPP and PEG chemistries. Significantly, both hydrophobic and electrostatic interactions were shown to contribute to the binding of DNA to the ALAPP film. Finally, the ability to manipulate DNA by applying an electrical bias to these surfaces was also demonstrated.

Hook, Andrew L.; Thissen, Helmut; Quinton, Jamie; Voelcker, Nicolas H.

2008-05-01

414

Polyvinyl alcohol and polyethylene glycol form polymer bodies in the periplasm of Sphingomonads that are able to assimilate them.  

PubMed

Scanning electron microscopy (SEM) shows remarkable morphological surface changes in Sphingopyxis sp. 113P3 cells grown in polyvinyl alcohol (PVA) but not in Luria-Bertani medium (LB) (Hu et al. in Arch Microbiol 188: 235-241, 2007). However, transmission electron microscopy showed no surface changes in PVA-grown cells and revealed the presence of polymer bodies in the periplasm of PVA-grown cells, which were not observed in LB-grown cells. The presence of polymer bodies was supported by low-vacuum SEM observation of PVA- and LB-grown cells of strain 113P3, and the presence of similar polymer bodies was also found when Sphingopyxis macrogoltabida 103 and S. terrae were grown in polyethylene glycol (PEG). The extraction of PVA and PEG from the periplasmic fraction of cells using a modified Anraku and Heppel method and their analysis by MALDI-TOF mass spectrometry strongly suggested that the polymer bodies are composed of PVA and PEG, respectively, in Sphingopyxis sp. 113P3 (PVA degrader) and Sphingopyxis macrogoltabida 103 or S. terrae (PEG degraders). PEG-grown S. macrogoltabida 103 and S. terrae showed higher transport of (14)C-PEG 4000 than LB-grown cells. Recombinant PegB (TonB-dependent receptor-like protein consisting of a barrel structure) interacted with PEG 200, 4000 and 20000, suggesting that the barrel protein in the outer membrane contributes to the transport of PEG into the periplasm. PMID:23263333

Kawai, Fusako; Kitajima, Sakihito; Oda, Kenji; Higasa, Takahiko; Charoenpanich, Jittima; Hu, Xiaoping; Mamoto, Rie

2013-02-01

415

[Growth of microfungi on the external polyethylene anticorrosive coating of oil-gas pipes].  

PubMed

The authors have studied the resistance of external anticorrosive polyethylene coat of oil-gas pipes (based on the high-density polyethylene, HDPE) to the action of microfungi, natural contamination, fungistatic and fungicide activity. It was found that the intensity of growth of standard test cultures on the surface of polyethylene coat increases in terms which imitate mineral and organic contaminations, and this results in the decrease of the index of its resistance to the action of microfungi. The microfungi, found in the process of study of natural contamination of polyethylene coat and its components, are presented by six species, Alternaria sp. most frequently occurring among them. The presence of admixtures of nitrogenic and phosphoric organic substances in chemical composition of control standards of adhesive and HDPE, which were not exposed to the influence of microfungi, was established by the method of IR spectroscopy. Changes of the IR spectra were noticed in the surface layer of high density polyethylene pellets under the influence of Penicillium funiculosum 171703 that evidences for the process of its slow oxidation. It is assumed that the damaging of the coating components is due to the presence in their chemical composition of impurities of nitrogen- and phosphorus-containing compounds that are easily absorbed by microscopic fungi. PMID:24800514

Subbota, A G; Chuenko, A I; Ostapiuk, S N

2014-01-01

416

Quantitation of employee exposure to emission products generated by commercial-scale processing of polyethylene.  

PubMed

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

Tikuisis, T; Phibbs, M R; Sonnenberg, K L

1995-08-01

417

Tribology, UV degradation, and structure-property-processing relationships of detonation nanodiamond-polyethylene nanocomposites  

NASA Astrophysics Data System (ADS)

Nanoscale reinforcements offer the possibility of coupling the already proven high strength to weight properties of polymer matrix composites with additional multifunctional properties such as electrical conductivity, thermal conductivity, unique optics, UV/IR radiation absorption, and enhanced wear resistance. This work presents materials based on detonation nanodiamonds dispersed in two types of polyethylene. The work begins with an understanding of nucleation phenomena. It was discovered through isothermal kinetics using differential scanning calorimetry that nanodiamonds act as nucleating agents during polyethylene crystallization. A processing technique to disperse nanodiamonds into very viscous ultra-high molecular weight polyethylene was developed and analyzed. These composites were further studied using dynamic mechanical analysis which showed increases in both stiffness and energy absorbing modes over unfilled UHMWPE. Exposure to UV degradation caused a failure of the polymer microstructure which was found to be caused by residual tensile stresses between the polymer particles formed during processing. These high stress regions were more prone to photo oxidation even though the nanodiamond particles were shown to decrease surface oxidation. Additionally, the tribological properties of UHMWPE/nanodiamond composites were investigated. Ultra-high molecular weight polyethylene is an already proven ultra tough and wear resistant polymer that is used in many high performance thermoplastic applications such as bearings, surfaces (skids/wheels), ropes/nets, and orthopedic implants. This work showed that UHMWPE loaded with 5.0wt% nanodiamonds might be a candidate to replace the currently used crosslinked polyethylene material used in orthopedic implants.

Tipton, John

418

Association between dislocation, impingement, and articular geometry in retrieved acetabular polyethylene cups.  

PubMed

We used a novel analysis technique and retrieved acetabular polyethylene liners to investigate relationships between impingement damage, dislocation history, and polyethylene liner geometry. Forty-eight polyethylene liners with neutral rim elevation were visually assessed for peripheral rim damage consistent with impingement between the liner rim and femoral component. Liner articular geometry was measured using a digital stylus, and the geometric relationships between the liner rim and center of the femoral head were characterized by lip height, head center inset, and head penetration into the polyethylene liner. Thirteen (27%) retrieved liners had rim impingement damage and 12 (25%) had a history of dislocation. The proportion of liners with impingement was not significantly different among dislocated and stable liners. Lip height, head center inset, and head penetration were not significantly different between liners with and without impingement damage. Dislocated liners had a significantly shorter head center inset, with significantly less head penetration because of shorter functional duration. Designing polyethylene liners with a sufficiently deep articular surface that exceeds 0.95 mm may prove beneficial for decreasing the prevalence of early dislocation, independent of impingement damage. PMID:17471491

Tanino, Hiromasa; Harman, Melinda K; Banks, Scott A; Hodge, W Andrew

2007-11-01

419

Solid-phase polyethylene glycol conjugation using hydrophobic interaction chromatography.  

PubMed

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

Niu, Jianlou; Zhu, Yanlin; Xie, Yaoyao; Song, Lintao; Shi, Lu; Lan, Junjie; Liu, Bailin; Li, Xiaokun; Huang, Zhifeng

2014-01-31

420

Co-immobilized poly(ethylene glycol)-block-polyamines promote sensitivity and restrict biofouling on gold sensor surface for detecting factor IX in human plasma.  

PubMed

In order to detect an extremely low amount of human coagulation factor IX (FIX), poly(ethylene glycol) (PEG)/aptamer co-immobilized surface was constructed using original PEG-polyamine surface modification agents on surface plasmon resonance (SPR) sensor chip. Initially, a gold (Au) sensor chip of SPR was modified using poly(ethylene glycol)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] (PEG-b-PAMA) followed by treatment with SH-dT20 and was duplexed with anti-FIX aptamer extended using A24. Furthermore, the co-immobilization of pentaethylenehexamine-terminated poly(ethylene glycol) (N6-PEG) on the sensing surface completely quenched bio-fouling. On this dual tethered PEG-surface, we determined that the dissociation constant for FIX-aptamer interaction was 37 ± 10 pM, and the sensitivity of detection could reach up to 800 fM on using aptamer-FIX-antibody sandwich pattern detected by gold nanoparticle-conjugated anti-mouse antibody. We could detect FIX in the presence of abundant albumin. Furthermore, to mimic the actual detection of FIX in clinical samples, we demonstrated our experimental results with human blood plasma instead of FIX. Higher-sensitivity was attained because of dual polymers immobilized on Au surface, and this can emerge as a common strategy for any aptamer-protein interactions. The selective binding of aptamer in human blood plasma described here indicates the suitability of the present strategy for detection in clinically relevant samples. PMID:24922332

Lakshmipriya, Thangavel; Horiguchi, Yukichi; Nagasaki, Yukio

2014-08-21

421

Tribological Evaluation of Nanostructured Diamond Coatings and CoCr against Ultra-High Molecular Weight Polyethylene  

PubMed Central

Background Some loss of joint prostheses has been attributed to osteolytic phenomena leading to loosening and associated with debris from wear of polyethylene articulating against metal alloys. Reduced polyethylene wear has been reported with ceramics serving as an alternative counterface. Methods Nanostructured Diamond (NSD) coatings were deposited onto Ti6A14V by microwave plasma-assisted chemical vapor deposition, with both hydrogen-rich (H-NSD) and helium-rich (He-NSD) feedgas mixtures. Pin-on-disk wear tests of polyethylene against NSD and CoCr were performed in serum lubrication at body temperature. Scanning electron microscopy was used to examine surface morphology, and nanoindentation was used to determine hardness and modulus of the polyethylene pins. Raman spectroscopy, surface roughness, and wettability analyses of NSD coatings were performed. Results Raman spectroscopy confirmed sp2 and sp3 bonded carbon. No significant differences in wear factors were found between polyethylene on H-NSD, He-NSD, and CoCr, despite higher roughness and friction coefficient for the He-NSD and H-NSD coatings, compared to CoCr. Contact angles for the diamond coatings were reduced following the wear tests, indicating that these surfaces became more hydrophilic. Multiple pimples were observed on pins articulated against CoCr, and a single, large protuberance was observed in polyethylene-on-NSD These features were conjectured to be re-consolidated polyethylene particles. Nanoindentation modulus and hardness of the worn polyethylene surfaces were lower for polyethylene-on-diamond than for polyethylene-on-CoCr. Conclusions As a counterface to polyethylene, the NSD coatings produced wear factors comparable to CoCr in the present pin-on-disk tests. Thus, NSD-coated Ti6A14V shows promise for use in joint replacement bearing applications. PMID:17853416

Hill, Michael R.; Catledge, Shane A.; Konovalov, Valeriy; Clem, William C.; Chowdhury, Shafiul A.; Etheridge, Brandon S.; Stanishevsky, Andrei; Lemons, Jack E.; Vohra, Yogesh K.; Eberhardt, Alan W.

2008-01-01

422

FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers  

NASA Technical Reports Server (NTRS)

A family of experimental highly miniaturized field-effect transistors (FETs) is based on exploitation of the electrical properties of nanofibers of polyaniline/ polyethylene oxide (PANi/PEO) doped with camphorsulfonic acid. These polymer-based FETs have the potential for becoming building blocks of relatively inexpensive, low-voltage, highspeed logic circuits that could supplant complementary metal oxide/semiconductor (CMOS) logic circuits. The development of these polymerbased FETs offers advantages over the competing development of FETs based on carbon nanotubes. Whereas it is difficult to control the molecular structures and, hence, the electrical properties of carbon nanotubes, it is easy to tailor the electrical properties of these polymerbased FETs, throughout the range from insulating through semiconducting to metallic, through choices of doping levels and chemical manipulation of polymer side chains. A further advantage of doped PANi/PEO nanofibers is that they can be made to draw very small currents and operate at low voltage levels, and thus are promising for applications in which there are requirements to use many FETs to obtain large computational capabilities while minimizing power demands. Fabrication of an experimental FET in this family begins with the preparation of a substrate as follows: A layer of silicon dioxide between 50 and 200 nm thick is deposited on a highly doped (resistivity 0.01 W.cm) silicon substrate, then gold electrodes/contact stripes are deposited on the oxide. Next, one or more fibers of camphorsulphonic acid-doped PANi/PEO having diameters of the order of 100 nm are electrospun onto the substrate so as to span the gap between the gold electrodes (see Figure 1). Figure 2 depicts measured current-versus-voltage characteristics of the device of Figure 1, showing that saturation channel currents occur at source-todrain potentials that are surprisingly low, relative to those of CMOS FETs. The hole mobility in the depletion regime in this transistor was found to be 1.4 10(exp -4) sq cm/(V.s), while the one-dimensional charge density at zero gate bias was estimated to be approximately one 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 of the fibers is expected to enhance the properties of future versions of this transistor.

Theofylaktos, Noulie; Robinson, Daryl; Miranda, Felix; Pinto, Nicholas; Johnson, Alan, Jr.; MacDiarmid, Alan; Mueller, Carl

2006-01-01

423

Facile construction of well-defined fullerene-dendrimer supramolecular nanocomposites for bioapplications.  

PubMed

Well-defined fullerene-dendrimer supramolecular nanocomposites exhibiting uniform size, controlled morphology, high fullerene inclusion efficiency, excellent water solubility, and non-toxicity were facilely fabricated through complexation of carboxyfullerenes with poly(ethylene glycol)-modified poly(amidoamine) dendrimers. PMID:25580012

Li, Xiaojie; Watanabe, Yasuo; Yuba, Eiji; Harada, Atsushi; Haino, Takeharu; Kono, Kenji

2015-02-01

424

Polyethylene barrier impregnated with lambda-cyhalothrin for exclusion of subterranean termites (Isoptera: Rhinotermitidae) from structures.  

PubMed

Polyethylene film impregnated with lambda-cyhalothrin was placed over a sand plot and covered with a concrete slab to allow insecticide movement into the sand for a period of 5.5 yr. Discs of polyethylene film and sand beneath them were sampled annually for 5 yr and at 5.5 yr for bioassay with the Formosan and eastern subterranean termite. Results demonstrated that sufficient quantities of lambda-cyhalothrin were released from the impregnated polyethylene film into adjacent sand to prevent termite penetration. The impregnated film has less environmental impact than conventional liquid termiticides because the insecticide is held in the polymer. Other advantages include its dual function as a construction moisture barrier and ease in verifying its proper installation. PMID:15154483

Su, Nan-Yao; Ban, Paul; Scheffrahn, Rudolf H

2004-04-01

425

Terahertz absorption spectra of oxidized polyethylene and their analysis by quantum chemical calculations  

NASA Astrophysics Data System (ADS)

Low-density polyethylene, either cross-linked or not, was oxidized and its absorption spectra were measured in the terahertz (THz) range and infrared range. The absorption was increased by the oxidation in the whole THz range. In accord with this, infrared absorption due to carbonyl groups appears. Although these results indicate that the increase in absorption is induced by oxidation, its attribution to resonance or relaxation is unclear. To clarify this point, the vibrational frequencies of three-dimensional polyethylene models with and without carbonyl groups were quantum chemically calculated. As a result, it was clarified that optically inactive skeletal vibrations in polyethylene become active upon oxidation. Furthermore, several absorption peaks due to vibrational resonances are induced by oxidation at wavenumbers from 20 to 100 cm-1. If these absorption peaks are broadened and are superimposed on each other, the absorption spectrum observed experimentally can be reproduced. Therefore, the absorption is ascribable to resonance.

Komatsu, Marina; Hosobuchi, Masashi; Xie, Xiaojun; Cheng, Yonghong; Furukawa, Yukio; Mizuno, Maya; Fukunaga, Kaori; Ohki, Yoshimichi

2014-09-01

426

An atomistic description of the high-field degradation of dielectric polyethylene  

NASA Astrophysics Data System (ADS)

A microscopic mechanism governing the initiating step in the high-field aging of crystalline polyethylene is proposed, based on density functional calculations and ab initio molecular dynamics simulations. It is assumed that electrons, holes, and excitons are present in the system. While the additional individual electrons or holes are not expected to lead to significant degradation, the presence of triplet excitons are concluded to be rather damaging. The electron and hole states of the exciton localize on a distorted region of polyethylene, significantly weakening nearby C-H bonds and facilitating C-H bond scission. The barrier to cleavage of the weakened C-H bonds is estimated and is comparable to the thermal energy, suggesting that this mechanism may be responsible for the degradation of polyethylene when placed under electrical stress, e.g., in high-voltage cables.

Bealing, Clive R.; Ramprasad, R.

2013-11-01

427

Long Circulating Poly(Ethylene Glycol)Decorated Lipid Nanocapsules Deliver Docetaxel to Solid Tumors  

Microsoft Academic Search

\\u000a Purpose  The purpose of this study was to evaluate the ability of poly(ethylene glycol)-coated lipid nanocapsules (LN) to deliver the\\u000a highly potent hydrophobic anticancer drug docetaxel to solid tumors.\\u000a \\u000a \\u000a \\u000a Methods  Docetaxel-loaded nanocapsules (80–120 nm) were produced by a solvent-free phase inversion process and were coated with polyethylene\\u000a glycol distearoylphosphatidylethanolamine conjugate by a postinsertion step. In vivo studies were conducted in mice bearing subcutaneously

Mohamed Nabil Khalid; Pierre Simard; Didier Hoarau; Alice Dragomir; Jean-Christophe Leroux

2006-01-01

428

Effect of radiation cross-linking on the abrasive wear behaviour of polyethylenes  

NASA Astrophysics Data System (ADS)

This study explores the differences in the dry abrasive wear behavior of different polyethylenes, and compares the effect of radiation cross-linking on the wear behavior. Four different types of polyethylenes: LDPE, LLDPE, HDPE and UHMWPE were studied. Cross-linking was carried out by high energy electron beam with radiation dose of 200 kGy. The results show that in unirradiated state UHMWPE has excellent wear resistance, with HDPE showing comparable wear properties; both LDPE and LLDPE exhibit high wear rate. Cross-linking improves wear rate of LDPE and UHMWPE, however, the wear rate of HDPE and LLDPE increases with cross-linking.

Gul, Rizwan M.; Khan, Tahir I.

2014-06-01

429

Enhancing the Dyeability of Polypropylene Fibers by Melt Blending with Polyethylene Terephthalate  

PubMed Central

Attempts were made to modify polypropylene fibers by melt blending with polyethylene terephthalate in order to enhance the dyeability of the resultant fiber. Five blends of polypropylene/polyethylene terephthalate/compatibilizer were prepared and subsequently spun into fibers. Three disperse dyes were used to dye such modified fibers at boiling and 130°C. The dyeing performance of the blend fibers, as well as the morphological, chemical, thermal, and mechanical properties, of the corresponding blends was characterized by means of spectrophotometry, polarized optical microscopy, scanning electron microscopy (SEM), FT-IR spectroscopy, differential scanning calorimetry (DSC), and tensile testing. PMID:24288485

Moradian, Siamak; Ameri, Farhad

2013-01-01

430

Microgels of polyaspartamide and poly(ethylene glycol) derivatives obtained by ?-irradiation  

NASA Astrophysics Data System (ADS)

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 3.5 kGy), 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 able to swell instantaneously in water whereas their treatment with acetone produces swellable microparticles that have been characterized.

Pitarresi, Giovanna; Licciardi, Mariano; Craparo, Emanuela Fabiola; Calderaro, Elio; Spadaro, Giuseppe; Giammona, Gaetano

2002-09-01

431

Polyethylene as a medium for eliminating the solvent perturbation in intramolecular proton transfer systems  

NASA Astrophysics Data System (ADS)

Polyethylene was utilized as a suitable medium for proton transfer systems. A low-temperature fluorescence study of 3-hydroxyflavone was used as a probe of the quality of polyethylene. It was found that perturbations due to H-bonded impurities are largely suppressed in the polymer matrix as compared with other media. As an example we reinvestigated the phenomenon of dual fluorescence of 2,5-bis-(2-benzoxazolyl)-4-methoxyphenol. In this particular proton-transfer system, the intrinsic character of the energy barrier for excited-state proton transfer was confirmed.

Mordzi?ski, Andrzej

1988-11-01

432

Polyethylene as a medium for eliminating the solvent perturbation in intramolecular proton transfer systems  

NASA Astrophysics Data System (ADS)

Polyethylene was utilized as a suitable medium for proton transfer systems. A low-temperature fluorescence study of 3-hydroxy-flavone was used as a probe of the quality of polyethylene. It was found that perturbations due to H-bonded impurities are largely suppressed in the polymer matrix as compared with other media. As an example we reinvestigated the phenomenon of dual fluorescence of 2,5-bis-(2-benzoxazolyl)-4-methoxyphenol. In this particular proton-transfer system, the intrinsic character of the energy barrier for excited-state proton transfer was confirmed.

Mordzi?ski, Andrzej

1988-09-01

433

Capillary Break Beneath a Slab: Polyethylene Sheeting over Aggregate; Southwestern Pennsylvania (Fact Sheet)  

SciTech Connect

This document provides content for three areas of the Building America Solution Center. First, "Insulating Closed Crawlspace Walls and Band Joist Area" describes how to install rigid foam insulation on the interior perimeter walls and band joist area in closed crawlspace foundations of homes. Second, "Removing Construction Debris from Flexible Ducts" describes how to clean flexible ducts after construction or major renovation of a home to remove debris resulting from building materials, particularly airborne dust and particulates. Third, images, CAD drawings, and a case study illustrate right and wrong ways to apply polyethylene sheeting over aggregate. Similarly, a CAD drawing is included that illustrates the use of a concrete slab over polyethylene.

Not Available

2014-07-01

434

Reactive processing of particulate filled polymers: m-phenylene bismaleimide modified polyethylene\\/magnesium hydroxide composites  

Microsoft Academic Search

Summary  \\u000a The influence of processing temperature and the presence of the reactive modifier, m-phenylene bismaleimide (BMI), on the\\u000a formation of highly filled polyethylene\\/Mg(OH)2 composites has been investigated using central composite design methods. Infrared spectroscopic and differential scanning\\u000a calorimetric evidence produced suggests that maleimide C=C bonds are involved in a free radically induced process which leads\\u000a to extended and crosslinked polyethylene

Viera Khunová; Joe Hurst; Chris Liauw

1999-01-01

435

Extrusion of polysaccharide nanocrystal reinforced polymer nanocomposites through compatibilization with poly(ethylene oxide).  

PubMed

Polysaccharide nanocrystals with a rodlike shape but with different dimensions and specific surface area were prepared from cotton and capim dourado cellulose, and with a plateletlike morphology from waxy maize starch granules. The rheological behavior of aqueous solutions of poly(ethylene oxide) (PEO) with different molecular weights when adding these nanoparticles was investigated evidencing specific interactions between PEO chains and nanocrystals. Because PEO also bears hydrophobic moieties, it was employed as a compatibilizing agent for the melt processing of polymer nanocomposites. The freeze-dried mixtures were used to prepare nanocomposite materials with a low density polyethylene matrix by extrusion. The thermal and mechanical behavior of ensuing nanocomposites was studied. PMID:24840363

Pereda, Mariana; El Kissi, Nadia; Dufresne, Alain

2014-06-25

436

Neutronic performance on a mixed cold moderator of polyethylene particles and liquid hydrogen  

SciTech Connect

We measured the neutronic performance of a mixed moderator of polyethylene particles plus liquid hydrogen as the first test of a mixed type moderator. The energy spectrum from the mixed moderator looks like a linear combination of each spectrum from the polyethylene particles and from liquid hydrogen. We obtained 1.2~1.4 times higher cold neutron intensity, but with a longer pulse width than a decoupled liquid hydrogen moderator in the cold neutron region. In the slowing-down region it gave much higher intensity with almost the same pulse width. We found that this type of moderator exhibits better characteristics as a narrow pulse thermal neutron source.

Ogawa, Y.; Kiyanagi, Y.; Watanabe, N.

1997-09-01

437

The effects of pulsed fluid irrigation on bony ingrowth in porous polyethylene implants.  

PubMed

Twelve adult dogs were used to evaluate the effect of pulsed isotonic saline irrigation on bony ingrowth. The distal supracondylar ridge of the knee was transected. Six dogs had the area irrigated with a pulsed lavage system for 15 sec and six dogs did not. A porous piece of polyethylene was then stapled to the cancellous surface. Three of each were evaluated histologically at 3 weeks and 6 weeks. The pulsed irrigation significantly decreased the depth of bone penetration into the sections of polyethylene. PMID:3562349

Ritter, M A; Sieber, J M

1987-02-01

438

Patch expansion of purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) with and without polyethylene mulch  

Microsoft Academic Search

Purple and yellow nutsedge are the most troublesome weeds of vegetable crops in the southeast United States. Elimination of methyl bromide use will require alter- native management programs to suppress nutsedge growth and interference in veg- etables. Polyethylene mulch is an effective barrier for most weeds; however, nutsedges can proliferate in beds covered with polyethylene mulch. The influence of polyeth-

Theodore M. Webster

2005-01-01

439

Quantitative Evaluation of Radiation Damage to Polyethylene Terephthalate by Soft X-rays and High-energy Electrons  

E-print Network

Quantitative Evaluation of Radiation Damage to Polyethylene Terephthalate by Soft X-rays and High to polyethylene terephthalate (PET) caused by soft X-rays and energetic electrons have been measured using a scanning transmission X-ray microscope (STXM). Electron beam damage at two different dose rates and a range

Hitchcock, Adam P.

440

Oxo-biodegradable full carbon backbone polymers – biodegradation behaviour of thermally oxidized polyethylene in an aqueous medium  

Microsoft Academic Search

Several demonstrations of the effective biodegradation in soil of pro-oxidant activated polyethylene (PE) have been reported recently. Nevertheless a comprehensive understanding of the ultimate fate in the environment of the oxidized fragments of oxo-biodegradable polyethylene materials needs the extension of the studies to other natural environments and in particular to aqueous media (river, lake, brackish and marine waters) where accidental

Emo Chiellini; Andrea Corti; Salvatore D'Antone

2007-01-01

441

Wear and toughness of crosslinked polyethylene for total knee replacements: a study using a simulator and small-punch testing.  

PubMed

Severe loading and complex kinematics in total knee replacement make wear performance and toughness of the polyethylene in tibial inserts important. We investigated wear of crosslinked polyethylene using a knee simulator and measured toughness using small-punch testing. GUR1050 rods were gamma-irradiated in air at doses from 0 to 200 kGy, annealed in nitrogen, and machined into tibial inserts. The simulator was run to 4 million cycles, and wear rates determined from weight loss. Wear rate decreased by 54, 78, and 95% as radiation dose increased from 50 to 75 to 100 kGy, respectively. At every dose, toughness was significantly less after simulator testing, but the difference between control and wear-tested polyethylene, considered to be due to fatigue damage accumulation, was smallest at 50 kGy. The simulator-tested polyethylene that received 35 to 75 kGy had slightly higher toughness than equivalent material that received no irradiation. However, the toughness of simulator-tested polyethylene that received 150 and 200 kGy was lower than that of the simulator-tested polyethylene that received no irradiation. Our results suggest that an optimal irradiation dose may exist for crosslinked polyethylene for use in TKR and that the optimum dose would be less than the 100 kGy or more that are used in some current crosslinked polyethylene for hip replacement. PMID:16894591

Akagi, Masao; Asano, Taiyo; Clarke, Ian C; Niiyama, Norio; Kyomoto, Masayuki; Nakamura, Takashi; Hamanishi, Chiaki

2006-10-01

442

Morphology changes during radiation-thermal degradation of polyethylene and an EPDM copolymer by 13C NMR spectroscopy  

Microsoft Academic Search

The ? radiation induced degradation of an EPDM copolymer was compared to that of a 13C enriched polyethylene at exposure temperatures of 22 and 80°C. Morphological changes were measured by MAS 13C NMR spectroscopy and DSC. By first examining the high quality and less complex spectra of 13C enriched polyethylene, a protocol for the interpretation and deconvolution of the more

Roger A. Assink; Mathew Celina; Kenneth T. Gillen; Roger L. Clough; Todd M. Alam

2001-01-01

443

Star poly(ethylene glycol) as a tunable scaffold for neural tissue engineering  

NASA Astrophysics Data System (ADS)

The primary focus of this work was to develop a novel synthetic hydrogel scaffold as an in vitro model to enable future detailed studies of how neurons grow in environments with controllable diffusion profiles of soluble cues and tunable neuronmatrix interactions. The development of in vitro models that enable elucidation of the mechanisms of system performance is a recently emerging goal of tissue engineering. The design of three-dimensional (3D) scaffolds in particular, is motivated by the need to develop model systems that better mimic native tissue as compared to conventional two-dimensional (2D) cell culture substrates. An ideal scaffold is degradable, porous, biocompatible, with mechanical properties to match those of the tissues of interest and with a suitable surface chemistry for cell attachment, proliferation, and differentiation. Although naturally derived materials are more versatile in providing complex biological cues, synthetic polymers are preferable for the design of in vitro models as they provide wider range of properties, controllable degradation rates, and easier processing. Most importantly, their mechanical properties can be decoupled from their biological properties, a crucial issue in interpreting cell responses. The synthetic material provides the structural backbone of the scaffold while biochemical function is added via incorporation of ligands or proteins aimed at triggering specific cell behaviors. As presented in this dissertation, we have developed and characterized a new synthetic 3D hydrogel scaffold from cross-linked poly(ethylene glycol) (PEG). PEG was selected because it is hydrophilic, non-toxic, biocompatible, and inert to protein adhesion. The chosen cross-linking chemistry was a highly specific reaction that occurred under physiological conditions so that cells could be embedded within the gel prior to cross-linking. Controllable degradability was imparted via series of hydrolytically degradable PEG cross-linkers. Thorough analysis demonstrated the independent tuning of the mechanical, biochemical and biological properties of the developed hydrogel. Because soluble cues such as neurotrophic factors are an effective means for promoting nerve regeneration, the diffusion of biomolecules through the PEG hydrogel were also explored in depth via two methods: fluorescence correlation spectroscopy (FCS) and bulk diffusion experiments. This is the first demonstration of FCS to delineate protein diffusivity within a cross-linked synthetic hydrogel and describe local and dynamic protein-polymer interactions that occur within these systems. Further, since PEG is inert, short ligands such as RGD were used to promote cell adhesion and new insights into how these ligands impact hydrogel mechanical and transport properties were established. Finally, to test the utility of the developed material as an in vitro model, neuronal cell-matrix interactions were studied by tuning hydrogel properties and assessing cell viability and neurite outgrowth. We believe that this work is major step in building an in vitro model for gaining an understanding of the key parameters that guide nerve regeneration and have the potential to lead to the development of better strategies to treat peripheral nerve injuries.

Zustiak, Silviya Petrova

444

Effect of nano-fibers on the stress-strain behavior of semi-crystalline poly(ethylene terephthalate) at different strain rates  

E-print Network

Uniaxial compression tests were performed on amorphous poly(ethylene terephthalate) (PET), amorphous poly(ethylene terephthalate)- glycol (PETG), semi-crystalline PET, and semicrystalline PET with various amounts of ...

Cohen, Ellann

2008-01-01

445

Optimization of Serine Protease Purification from Mango (Mangifera indica cv. Chokanan) Peel in Polyethylene Glycol/Dextran Aqueous Two Phase System  

PubMed Central

Mango peel is a good source of protease but remains an industrial waste. This study focuses on the optimization of polyethylene glycol (PEG)/dextran-based aqueous two-phase system (ATPS) to purify serine protease from mango peel. The activity of serine protease in different phase systems was studied and then the possible relationship between the purification variables, namely polyethylene glycol molecular weight (PEG, 4000–12,000 g·mol?1), tie line length (?3.42–35.27%), NaCl (?2.5–11.5%) and pH (4.5–10.5) on the enzymatic properties of purified enzyme was investigated. The most significant effect of PEG was on the efficiency of serine protease purification. Also, there was a significant increase in the partition coefficient with the addition of 4.5% of NaCl to the system. This could be due to the high hydrophobicity of serine protease compared to protein contaminates. The optimum conditions to achieve high partition coefficient (84.2) purification factor (14.37) and yield (97.3%) of serine protease were obtained in the presence of 8000 g·mol?1 of PEG, 17.2% of tie line length and 4.5% of NaCl at pH 7.5. The enzymatic properties of purified serine protease using PEG/dextran ATPS showed that the enzyme could be purified at a high purification factor and yield with easy scale-up and fast processing. PMID:22489172

Mehrnoush, Amid; Mustafa, Shuhaimi; Sarker, Md. Zaidul Islam; Yazid, Abdul Manap Mohd

2012-01-01

446

40 CFR 721.4040 - Glycols, polyethylene-, 3-sulfo-2-hydroxypropyl-p-(1,1,3,3-tetra-methylbutyl)phenyl ether, sodium...  

Code of Federal Regulations, 2011 CFR

...polyethylene-, 3-sulfo-2-hydroxypropyl-p-(1,1,3,3-tetra-methylbutyl...polyethylene-, 3-sulfo-2-hydroxypropyl-p -(1,1,3,3-tetra-methylbutyl...polyethylene-, 3-sulfo-2-hydroxypropyl-p -(1,1,3,3-tetramethyl...

2011-07-01

447

40 CFR 721.4040 - Glycols, polyethylene-, 3-sulfo-2-hydroxypropyl-p-(1,1,3,3-tetra-methylbutyl)phenyl ether, sodium...  

Code of Federal Regulations, 2012 CFR

...polyethylene-, 3-sulfo-2-hydroxypropyl-p-(1,1,3,3-tetra-methylbutyl...polyethylene-, 3-sulfo-2-hydroxypropyl-p -(1,1,3,3-tetra-methylbutyl...polyethylene-, 3-sulfo-2-hydroxypropyl-p -(1,1,3,3-tetramethyl...

2012-07-01

448

Proteomic approaches to identify cold-regulated plasma membrane proteins.  

PubMed

Plasma membrane is the primary determinant of freezing tolerance in plants because of its central role in freeze-thaw cycle. Changes in the plasma membrane proteins have been one of the major research areas in plant cold acclimation. To obtain comprehensive profiles of the plasma membrane proteomes and their changes during the cold acclimation process, a plasma membrane purification method using a dextran-polyethylene glycol two polymer system and a mass spectrometry-based shotgun proteomics method using nano-LC-MS/MS for the plasma membrane proteins are described. The proteomic results obtained are further applied to label-free protein semiquantification. PMID:24852635

Takahashi, Daisuke; Nakayama, Takato; Miki, Yushi; Kawamura, Yukio; Uemura, Matsuo

2014-01-01

449

The effect of the presence of globular proteins and elongated polymers on enzyme activity  

Microsoft Academic Search

We have studied the effect of a crowded (macromolecular) solution on reaction rates of the decarboxylating enzymes urease, pyruvate decarboxylase and glutamate decarboxylase. A variety of crowding agents were used including haemoglobin, lysozyme, various dextrans and polyethylene glycol. Enzyme reaction rates of all three enzymes show two different types of effect that separate the globular proteins from the polysaccharides\\/polymers. Increasing

Barry K. Derham; John J. Harding

2006-01-01

450

Kosmotrope-like hydration behavior of polyethylene glycol from microcalorimetry and binding isotherm measurements.  

PubMed

Polyethylene glycol (PEG) at various molecular weights (MWs) has been regarded as a wonder molecule in biomedical applications. For instance, PEG serves as a unique moiety for pegylation of "biobetter" drug development, PEG provides controlled-release and preserved activity of biologics, and PEG modified surface works as an antibiofouling surface. The primary characteristics of PEG molecules used in relevant applications have been attributed mainly to the hydration behavior in aqueous solutions. However, the effects on the solvation of solutes in solution caused by presenting PEG molecules as a cosolvent, as well as the thermodynamics aspect of the hydration behavior of PEG in solution, have not been well documented. The solvation behavior of solutes, such as protein, with PEG as a cosolvent, indicates the success of PEG applications, such as biofouling and controlled release. In this investigation, we examined the effects of a buffer solution containing PEG molecules on the solution behavior of solute and the interactions between solid surfaces with solutes. We adapted the study by selecting a lysozyme as a solute in a buffer solution with either ammonium sulfate (kosmotrope) or sodium chloride (chaotrope) and anionic resin (SP-Sepharose) as solid surfaces. The experiments primarily involved binding equilibrium measurements and thermodynamics analysis. The results revealed that, in both saline buffers, adding PEG increases the binding affinity between the lysozyme and the resin, similar to kosmotropic salt in the examined salt concentrations. The thermodynamics analyses involving microcalorimetric measurements show that the bindings are mainly driven by enthalpy, indicating that electrostatic interaction was the primary binding force under these experimental conditions. The variations of the enthalpy and entropy of the binding thermodynamics when adding PEG to different salt types in the buffer solution showed opposite behavior, and the results support the concept of kosmotrope-like behavior of PEG. The equilibrium and thermodynamics data demonstrate that PEG has a kosmotrope-like hydration behavior, and the extent of kosmotrope-like behavior depends on the molecular weight of PEG with the outcomes of various molecular weights of PEG being added to the binding solution. The results of this study provide essential knowledge for PEG as an additive (or cosolvent) in various research applications. PMID:23330911

Chen, Wen-Yih; Hsu, Min-Yen; Tsai, Ching-Wei; Chang, Yung; Ruaan, Rouh-Chyu; Kao, Wei-Hung; Huang, E-Wen; Chuan, Hsiao-Yeh-Tzu Chung

2013-04-01

451

Noninvasive detection of passively targeted poly(ethylene glycol) nanocarriers in tumors.  

PubMed

The present studies noninvasively investigate the passive tumor distribution potential of a series of poly(ethylene glycol) (PEG) nanocarriers using a SkinSkan spectrofluorometer and an In Vivo Imaging System (IVIS) 100. Fluorescein conjugated PEG nanocarriers of varying molecular weights (10, 20, 30, 40, and 60 kDa) were prepared and characterized. The nanocarriers were administered intravenously to female balb/c mice bearing subcutaneous 4T1 tumors. Passive distribution was measured in vivo (?(exc), 480 nm; ?(em), 515-520 nm) from the tumor and a contralateral skin site (i.e., control site). The signal intensity from the tumor was always significantly higher than that from the contralateral site. Trends in results between the two methods were consistent with tumor distribution increasing in a molecular weight-dependent manner (10 < 20 < 30 ? 40 ? 60 kDa). The 10 kDa nanocarrier was not detected in tumors at 24 h, whereas 40-60 kDa nanocarriers were detected in tumors for up to 96 h. The 30, 40, and 60 kDa nanocarriers showed 2.1, 5.3, and 4.1 times higher passive distribution in tumors at 24 h, respectively, as compared to the 20 kDa nanocarrier. The 60 kDa nanocarrier exhibited 1.5 times higher tumor distribution than 40 kDa nanocarrier at 96 h. Thus, PEG nanocarriers (40 and 60 kDa) with molecular weights close to or above the renal exclusion limit, which for globular proteins is ?45 kDa, showed significantly higher tumor distribution than those below it. The hydrodynamic radii of PEG polymers, measured using dynamic light scattering (DLS), showed that nanocarriers obtained from polymers with hydrodynamic radii ?8 nm exhibited higher tumor distribution. Ex vivo mass balance studies revealed that nanocarrier tissue distribution followed the rank order tumor > lung > spleen > liver > kidney > muscle > heart, thus validating the in vivo studies. The results of the current studies suggest that noninvasive dermal imaging of tumors provides a reliable and rapid method for the initial screening of nanocarrier tumor distribution pharmacokinetics. PMID:22077582

Singh, Yashveer; Gao, Dayuan; Gu, Zichao; Li, Shike; Stein, Stanley; Sinko, Patrick J

2012-01-01

452

Non-Invasive Detection of Passively Targeted Poly(ethylene glycol) Nanocarriers in Tumors  

PubMed Central

The present studies noninvasively investigate the passive tumor distribution potential of a series of poly(ethylene glycol) [PEG] nanocarriers using a SkinSkan® spectrofluorometer and an In Vivo Imaging System (IVIS®) 100. Fluorescein conjugated PEG nanocarriers of varying molecular weights (10, 20, 30, 40, and 60 kDa) were prepared and characterized. The nanocarriers were administered intravenously to female balb/c mice bearing subcutaneous 4T1 tumors. Passive distribution was measured in vivo (?exc.: 480 nm; ?em.: 515–520 nm) from the tumor and a contralateral skin site (i.e., control site). The signal intensity from the tumor was always significantly higher than the contralateral site. Trends in results between the two methods were consistent with tumor distribution increasing in a molecular weight-dependent manner (10<20<30?40?<60 kDa). The 10 kDa nanocarrier was not detected in tumors at 24 hrs, whereas 40–60 kDa nanocarriers were detected in tumors for up to 96 hrs. The 30, 40, and 60 kDa nanocarriers showed 2.1, 5.3, and 4.1 times higher passive distribution in tumors at 24 hrs, respectively, as compared to the 20 kDa nanocarrier. The 60 kDa nanocarrier exhibited 1.5 times higher tumor distribution than 40 kDa nanocarrier at 96 hrs. Thus, PEG nanocarriers (40 and 60 kDa) with molecular weights close to or above the renal exclusion limit, which for globular proteins is ?45 kDa, showed significantly higher tumor distribution than those below it. The hydrodynamic radii of PEG polymers, measured using dynamic light scattering (DLS), showed that nanocarriers obtained from polymers with hydrodynamic radii =8 nm exhibited higher tumor distribution. Ex vivo mass balance studies revealed that nanocarrier tissue distribution followed the rank order of: tumor > lung > spleen > liver > kidney > muscle > heart, thus validating the in vivo studies. The results of the current studies suggest that non-invasive dermal imaging of tumors provides a reliable and rapid method for the initial screening of nanocarrier tumor distribution pharmacokinetics. PMID:22077582

Singh, Yashveer; Gao, Dayuan; Gu, Zichao; Li, Shike; Stein, Stanley; Sinko, Patrick J.

2011-01-01

453

Controlled Activation of Protein Rotational Dynamics Using Smart Hydrogel Tethering  

SciTech Connect

Stimulus-responsive hydrogel materials that stabilize and control protein dynamics have the potential to enable a range of applications to 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 polyethylene 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 [13C] and [15N], permitting dynamic structural measurements using TROSY-HSQC NMR spectroscopy. Upon initial formation of hydrogels protein dynamics are suppressed, with concomitant increases in protein stability. Relaxation of the hydrogel matrix following transient heating results in the activation of protein dynamics and restoration of substrate-induced large-amplitude domain motions necessary for substrate binding.

Beech, Brenda M.; Xiong, Yijia; Boschek, Curt B.; Baird, Cheryl L.; Bigelow, Diana J.; Mcateer, Kathleen; Squier, Thomas C.

2014-09-05

454

Introduction to current and future protein therapeutics: a protein engineering perspective.  

PubMed

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. PMID:21371474

Carter, Paul J

2011-05-15

455

Introduction to current and future protein therapeutics: A protein engineering perspective  

SciTech Connect

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.

Carter, Paul J., E-mail: pjc@gene.com

2011-05-15

456

Autumn vegetable response to residual herbicides applied the previous spring under low density polyethylene mulch  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field studies were conducted in 2002 and 2005 to evaluate autumn vegetable tolerance to residual herbicides applied the previous spring under low density polyethylene (LDPE) mulch. Spring applications of 1.12 kg/ha S-metolachlor, 0.027 kg/ha halosulfuron, 0.28 kg/ha sulfentrazone, and 1.12 kg/ha S...

457

Formation, structure and thermal properties of the ternary aggregate of polyethylene glycol, ?-cyclodextrin and ferrocene  

Microsoft Academic Search

In this study, we firstly describe the formation of a ternary aggregate of ferrocene (Fc), polyethylene glycol (PEG) and ?-cyclodextrin (?-CD). Our results provide strong evidence for the fact that the intermolecular aggregation behaviour leads to a striking change in structure and thermal property of the components aggregated. First of all, several independent experiments give us sufficient information about the

Jun Yang; Le Xin Song; Fang Yun Du; Jing Yang; Zhi Cheng Shao

2012-01-01

458

Viscosity change of unsaturated polyester–alumina-composites using polyethylene glycol alkyl ether based dispersants  

Microsoft Academic Search

The influence of a series of polyethylene glycol alkyl ether based dispersants on the viscosity of unsaturated polyester–alumina-composites has been investigated systematically. A few correlations between the dispersants molecular structure, the used concentration and the related composite flow properties have been found. In general only the addition of small dispersant molecules with a short hydrophilic anchoring group and an extended

T. Hanemann

2006-01-01

459

Composite Polymer Electrolytes Based on Poly(ethylene glycol) and Hydrophobic Fumed Silica: Dynamic  

E-print Network

fillers.7 Several alternative approaches to electrolyte design have also been examined in the past decade of the electrolyte designs suggested so far have been based on high- molecular-weight polymers; for these systemsComposite Polymer Electrolytes Based on Poly(ethylene glycol) and Hydrophobic Fumed Silica: Dynamic

Raghavan, Srinivasa

460

Oxygen barrier properties of crystallized and talc-filled poly(ethylene terephthalate)  

Microsoft Academic Search

The improvement in oxygen barrier properties of poly(ethylene terephtha- late) (PET) by incorporation of an impermeable phase such as crystallinity or talc platelets was examined. Crystallinity was induced by crystallization from the glassy state (cold crystallization). Microlayering was used to create talc-filled structures with controlled layer architecture. The reduction of permeability in crystallized and talc- filled PET was well described

D. J. Sekelik; E. V. Stepanov; S. Nazarenko; D. Schiraldi; A. Hiltner; E. Baer

1999-01-01