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1

Transactivating-transduction protein-polyethylene glycol modified liposomes traverse the blood-spinal cord and blood-brain barriers?  

PubMed Central

Naive liposomes can cross the blood-brain barrier and blood-spinal cord barrier in small amounts. Liposomes modified by a transactivating-transduction protein can deliver antibiotics for the treatment of acute bacterial infection-induced brain inflammation. Liposomes conjugated with polyethylene glycol have the capability of long-term circulation. In this study we prepared transactivating-transduction protein-polyethylene glycol-modified liposomes labeled with fluorescein isothiocyanate. Thus, liposomes were characterized by transmembrane, long-term circulation and fluorescence tracing. Uptake, cytotoxicity, and the ability of traversing blood-spinal cord and blood-brain barriers were observed following coculture with human breast adenocarcinoma cells (MCF-7). Results demonstrated that the liposomes had good biocompatibility, and low cytotoxicity when cocultured with human breast adenocarcinoma cells. Liposomes could traverse cell membranes and entered the central nervous system and neurocytes through the blood-spinal cord and blood-brain barriers of rats via the systemic circulation. These results verified that fluorescein isothiocyanate-modified transactivating-transduction protein-polyethylene glycol liposomes have the ability to traverse the blood-spinal cord and blood-brain barriers.

Zhou, Xianhu; Wang, Chunyuan; Feng, Shiqing; Chang, Jin; Kong, Xiaohong; Liu, Yang; Gao, Shijie

2012-01-01

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

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

4

Poly(ethylene glycol)Modified Proteins: Implications for Poly(lactide-co-glycolide)Based Microsphere Delivery  

Microsoft Academic Search

The reduced injection frequency and more nearly constant serum concentrations afforded by sustained release devices have been\\u000a exploited for the chronic delivery of several therapeutic peptides via poly(lactide-co-glycolide) (PLG) microspheres. The\\u000a clinical success of these formulations has motivated the exploration of similar depot systems for chronic protein delivery;\\u000a however, this application has not been fully realized in practice. Problems with

Sheetal S. Pai; Robert D. Tilton; Todd M. Przybycien

2009-01-01

5

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

6

Chromatographic methods for characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers.  

PubMed

The objective of this study was to develop chromatographic methods for the determination of the modification degree and the characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers (PEG-PAMAMs). The PEG-PAMAMs were prepared by reacting PAMAM generation 4 with monomethoxy PEG-nitrophenyl carbonate (mPEG-NPC). The modification degrees of PEG-PAMAMs were determined by quantifying 4-nitrophenol released from mPEG-NPC after PEGylation reaction using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The PEG-PAMAMs, which have poor UV absorbances, were characterized by HPLC with charged aerosol detection. This study demonstrates that the combination of these two detectors is a powerful tool for the preparation and characterization of PEG-PAMAMs. PMID:24361709

Park, Eun Ji; Cho, Hoon; Kim, Si Wouk; Na, Dong Hee

2014-03-15

7

Acetylcholine biosensor involving entrapment of acetylcholinesterase and poly(ethylene glycol)-modified choline oxidase in a poly(vinyl alcohol) cryogel membrane  

Microsoft Academic Search

A bienzymatic sensor for the determination of acetylcholine was prepared by physical coimmobilization of acetylcholinesterase and poly(ethylene glycol)-modified choline oxidase in a poly(vinyl alcohol) cryogel membrane obtained by a cyclic freezing–thawing process. The enzyme-modified polymer was applied on a platinum electrode to form an amperometric sensor, based on the electrochemical detection of enzymatically developed hydrogen peroxide. The analytical characteristics of

Lucio Doretti; Daniela Ferrara; Silvano Lora; Franco Schiavon; Francesco M Veronese

2000-01-01

8

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

9

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

10

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

PubMed

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

Ye, Kaichuang; Qin, Jinbao; Peng, Zhiyou; Yang, Xinrui; Huang, Lijia; Yuan, Fukang; Peng, Chen; Jiang, Mier; Lu, Xinwu

2014-01-01

11

Poly(ethylene glycol)-Modified Ligninase Enhances Pentachlorophenol  

E-print Network

-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- hanced substrate solubility and the increased activity of the modified enzyme, the catalytic efficiency

Wang, Ping

12

Radioprotection by polyethylene glycol-protein complexes in mice  

SciTech Connect

Polyethylene glycol of about 5000 D was activated with cyanuric chloride, and the activated compound was complexed to each of three proteins. Polyethylene glycol-superoxide dismutase and polyethylene glycol-catalase were each radioprotectants when administered prophylactically to female B6CBF1 mice before irradiation. The dose reduction factor for these mice was 1.2 when 5000 units of polyethylene glycol-catalase was administered before /sup 60/Co irradiation. Female B6CBF1 mice administered prophylactic intravenous injections of catalase, polyethylene glycol-albumin, or heat-denatured polyethylene glycol-catalase had survival rates similar to phosphate-buffered saline-injected control mice following /sup 60/Co irradiation. Polyethylene glycol-superoxide dismutase and polyethylene glycol-catalase have radioprotective activity in B6CBF1 mice, which appears to depend in part on enzymatic activities of the complex. However, no radioprotective effect was observed in male C57BL/6 mice injected with each polyethylene glycol-protein complex at either 3 or 24 hr before irradiation. The mechanism for radioprotection by these complexes may depend in part on other factors.

Gray, B.H.; Stull, R.W.

1983-03-01

13

Poly(ethylene glycol)-modified PAMAM-Fe3O4-doxorubicin triads with the potential for improved therapeutic efficacy: generation-dependent increased drug loading and retention at neutral pH and increased release at acidic pH.  

PubMed

Polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles are a promising drug-delivery system that can enhance the therapeutic effects of chemotherapy drugs, such as doxorubicin (DOX), with minimized side effects. This work explores the optimization of the potential therapeutic efficiency of PAMAM-Fe3O4-DOX triads. Different generations (G3, G5, and G6) of PAMAMs were synthesized and modified with poly(ethylene glycol) (PEG) and then used to encapsulate glutamic acid-modified Fe3O4 nanoparticles. The Fe3O4-dendrimer carriers (Fe3O4-DGx where x = the generation 3, 5, or 6 of dendrimers) were electrostatically conjugated with drug DOX. The loading and releasing efficiencies of DOX increased with the PAMAM generation from 3 to 6. The loading efficiencies of DOX molecules were 87, 93, and 96% for generations 3, 5, and 6, respectively. At pH 5, the DOX release efficiencies within 24 h were approximately 60, 68, and 80% for generations 3, 5, and 6, respectively. At pH 7.4, the DOX releasing efficiency was as low as ? 15%. Compared to the negative control, the PAMAM-Fe3O4-DOX triads showed only mild toxicity against human cervical adenocarcinoma cell line HeLa at pH 7.4, which indicated that DOX can be fairly benignly carried and sparingly released until PAMAM-Fe3O4-DOX is taken up into the cell. PMID:24446987

Nigam, Saumya; Chandra, Sudeshna; Newgreen, Donald F; Bahadur, Dhirendra; Chen, Qizhi

2014-02-01

14

Polyethylene glycol interferes with protein molecular weight determinations by gel filtration.  

PubMed

Gel filtration studies on Sephadex G-75 demonstrate markedly increased elution volumes for proteins chromatographed with polyethylene glycol. As little as 5% (w/v) polyethylene glycol in the applied protein sample can reduce apparent molecular weight estimates by gel filtration as much as 55%. Furthermore, gel filtration columns equilibrated with polyethylene glycol are not size-separating columns. Consequently, caution must be exercised when performing and interpreting gel filtration studies of proteins previously treated or precipitated with polyethylene glycol. PMID:6731837

Yan, S B; Tuason, D A; Tuason, V B; Frey, W H

1984-04-01

15

Molecular mechanism of polyethylene glycol mediated stabilization of protein.  

PubMed

The effect of different molar ratios of polyethylene glycol (PEG) on the conformational stability of protein, bovine serum albumin (BSA), was studied. The binding of PEG with BSA was observed by fluorescence spectroscopy by measuring the fluorescence intensity after displacement of PEG with chromophore ANS and had further been confirmed by measuring the intrinsic fluorescence of tryptophan residues of BSA. Co-lyophilization of BSA with PEG at optimum BSA:PEG molar ratio led to the formation of the stable protein particles. Circular dichroism (CD) spectroscopy study suggested that a conformational change had occurred in the protein after PEG interaction and demonstrated the highest stability of protein at the optimum BSA:PEG molar ratio of 1:0.75. Additional differential scanning calorimetry (DSC) study suggested strong binding of PEG to protein leading to thermal stability at optimum molar ratio. Molecular mechanism operating behind the polyethylene glycol (PEG) mediated stabilization of the protein suggested that strong physical adsorption of PEG on the hydrophobic core of the protein (BSA) along with surface adsorption led to the stability of protein. PMID:20097167

Rawat, Sanjay; Raman Suri, C; Sahoo, Debendra K

2010-02-19

16

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

17

Zeolites as new chromatographic carriers for proteins--easy recovery of proteins adsorbed on zeolites by polyethylene glycol.  

PubMed

Zeolites are able to adsorb proteins on their surface and might be suitable as a new type of chromatographic carrier material for proteins and for their conjugates (Matsui et al., Chem. Eur. J. 7 (2001) 1555-1560). Interestingly, maximum adsorption was observed at the isoelectric point (pI) of each protein. The current study was performed to investigate the desorption of proteins from the zeolites at pI. Proteins adsorbed to zeolites could be desorbed at pI by polyethylene glycol (PEG), but not by conventional eluents. The eluted proteins still retained their activities. The zeolite Na-BEA was an especially good composite for desorption by PEG. Using this method for the adsorption and desorption of proteins at pI, we succeeded in separating various proteins. The application of zeolites to biochemistry and biotechnology is also discussed. PMID:12782034

Chiku, Hiroyuki; Matsui, Masayoshi; Murakami, Shizuka; Kiyozumi, Yoshimichi; Mizukami, Fujio; Sakaguchi, Kengo

2003-07-01

18

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

19

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

20

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

21

Rationalization of membrane protein crystallization with polyethylene glycol using a simple depletion model.  

PubMed

Based on the importance of crystallizing membrane proteins in a rational way, cytochrome bc(1) complex (BC1) was crystallized using polyethylene glycol (PEG) as a sole crystallization agent. Interaction between protein-detergent complexes of BC1 was estimated by dynamic light scattering, and was compared with the numerical calculation using the Derjaguin-Landau-Verwey-Overbeek potential plus a depletion potential, without considering specific surface properties of the protein-detergent complexes. The experiments and calculation were found to be consistent and we obtained a relation between PEG molecular weight M and the range of depletion zone delta as delta approximately M(0.48+/-0.02). The stability of liquid phase of BC1 solutions was controlled by a ratio of (the range of depletion zone)/(the radius of a BC1 particle), which was consistent with recent theoretical predictions. The crystallization was most successful under a condition where the stability of the liquid phase changed from stable to unstable. The PEG molecular weight that fulfilled this condition coincided with the one used empirically to crystallize BC1 in the past by a number of groups. These results are compared to the fact that membrane proteins were often successfully crystallized close to the detergent cloud point. PMID:12719259

Tanaka, Shinpei; Ataka, Mitsuo; Onuma, Kazuo; Kubota, Tomomi

2003-05-01

22

Wear properties of polyethylene-metal and polyethylene-ceramic bearings for hip joint replacements: The effect of temperature and protein precipitation in hip simulator tests  

NASA Astrophysics Data System (ADS)

Ultra-high-molecular weight polyethylene (PE) cups bearing against metal or ceramic balls are the most commonly used combinations of materials for human hip joint replacements. The wear properties of these materials are typically evaluated in the laboratory using hip joint wear simulators, while lubricated with bovine serum. A previous test evaluating the PE cups against cobalt-chrome (CoCr), zirconia (Zr) and alumina balls demonstrated the sensitivity of serum proteins to elevated temperature; especially for Zr/PE, which showed the highest protein precipitation and bulk lubricant temperature but the lowest cup wear. In the present investigation, a temperature control system was used on a hip simulator to systematically evaluate the relationship between temperature and denaturation of the serum proteins which, in turn, affects the friction and wear properties of the prosthetic materials being tested. In order to control protein precipitation, the interface was temperature reduced by circulating coolant at 4°C through the center of the CoCr or Zr balls during a wear test. With cooling, protein assay of the serum showed 66% and 50% reductions in protein precipitation with the CoCr and Zr balls, respectively. The wear rate of the PE cups against the CoCr balls decreased by an average of 44%, whereas two of the three PE cups running against Zr balls exhibited slight increases in their wear rates, and the third showed a two fold increase. Under scanning electron microscopy, there were marked differences in the worn surfaces of the cups for the various conditions, and differences in the morphology of the PE wear debris recovered from the serum. For example, granular particles predominated without cooling, whereas fibrous particles predominated with cooling. Since particles generated in vivo (i.e., retrieved from periprosthetic tissues) typically show approximately equal proportions of granules and fibrils, the use of an intermediate coolant temperature might provide wear in the simulator closer to that occurring with these materials in vivo. These results demonstrated the complex interaction of the variables affecting wear in the hip simulator system that should be taken into account, for example, in the development of international standard procedures.

Liao, Yen-Shuo

23

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

PubMed

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

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

2006-12-15

24

Microcontact printing and microspotting as methods for direct protein patterning on plasma deposited polyethylene oxide: application to stem cell patterning.  

PubMed

Two methods for protein patterning on antifouling surfaces have been applied to analyze the density and bioactivity of the proteins after deposition. Microcontact printing has been used as a technique to transfer fibronectin through conformal contact, while piezoelectric deposition has been employed as a non-contact technique for producing arrays of fibronectin (FN). Plasma deposited polyethylene oxide-like (PEO-like) films have been used as non-fouling background to achieve the bioadhesive/biorepellent surface contrast. Both patterning methods allow the direct fabrication of protein arrays on a non-fouling substrate, and the subsequent formation of a pattern of stem cells by cell attachment on the arrayed substrates. Microcontact printing produced fully packed homogeneous fibronectin patterns, much denser than microspotted patterns. Both printing and spotting technologies generated functional protein arrays, their bioactivity being primarily modulated by the density of the deposited protein layer. Optimization of the FN parameters used for deposition has lead to the achievement of high-quality microarrays with large population of neural stem cells immobilized in the patterns in serum-free conditions, where cells exhibit a more homogeneous starting population and factors influencing fate decisions can be more easily tracked. The immunorecognition of fibronectin targeted antibodies, as well as the cell density, increase with the protein density up to a saturation point. Over 100 ng/cm² of fibronectin on the surface leads to a decrease in the number of attached cells and a raise of cell spreading. PMID:23404262

Ruiz, Ana; Zychowicz, Marzena; Ceriotti, Laura; Mehn, Dora; Sirghi, Lucel; Rauscher, Hubert; Mannelli, Ilaria; Colpo, Pascal; Buzanska, Leonora; Rossi, François

2013-06-01

25

Improving biocompatibility by controlling protein adsorption: Modification and design of biomaterials using poly(ethylene glycol) microgels and microspheres  

NASA Astrophysics Data System (ADS)

Guided by the clinical needs of patients and developments in biology and materials science, the primary focus of the biomaterials field remains at the solid/liquid interface between biomaterial surfaces and biological fluids. For blood-contacting devices, biological responses are initially elicited and directed by proteins that adsorb from this multicomponent solution to form thin films on their surfaces. The identity, conformation, and quantity of adsorbed proteins are related to the properties of a material's surface. For example, hydrophobic surfaces tend to be thrombotic via interactions between platelets and adsorbed fibrinogen, while surface-activation of specific enzymes initiates the coagulation cascade on hydrophilic surfaces. The objective of this thesis is to improve the design of biomaterials through the analysis and control of adsorbing protein layers. This goal is approached through three separate strategies. First, a proteomics-based methodology is presented for the assessment of protein conformation at the residue level after adsorption to biomaterial surfaces. A quantitative mass spectrometric technique is additionally suggested for the identification and quantification of proteins within adsorbed protein layers. Second, a method is described for the covalent attachment of poly(ethylene glycol) (PEG)-based hydrogel coatings onto biomaterials surfaces for the minimization of protein adsorption. The coatings are applied using partially crosslinked PEG solutions containing polymer and protein oligomers and microgels that can be designed to control cell adhesion. Finally, a modular strategy is proposed for the assembly of bioactive PEG-based hydrogel scaffolds. This was accomplished using novel PEG microspheres with diverse characteristics that individually contribute to the ability of the scaffold to direct cellular infiltration. The methodologies proposed by this thesis contribute to the recent shift in biomaterials and tissue engineering strategies towards directed cellular responses at the molecular level.

Scott, Evan Alexander

26

Protein partitioning in poly(ethylene glycol)/sodium polyacrylate aqueous two-phase systems.  

PubMed

The partition of hemoglobin, lysozyme and glucose-6-phosphate dehydrogenase (G6PDH) in a novel inexpensive aqueous two-phase system (ATPS) composed by poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA) has been studied. The effect of NaCl and Na(2)SO(4), pH and PEG molecular size on the partitioning has been studied. At high pH (above 9), hemoglobin partitions strongly to the PEG-phase. Although some precipitation of hemoglobin occurs, high recovery values are obtained particularly for lysozyme and G6PDH. The partitioning forces are dominated by the hydrophobic and electrochemical (salt) effects, since the positively charged lysozyme and negatively charged G6PDH partitions to the non-charged PEG and the strongly negatively charged polyacrylate enriched phase, respectively. PMID:18078945

Johansson, Hans-Olof; Magaldi, Flavio Musa; Feitosa, Eloi; Pessoa, Adalberto

2008-01-18

27

Wear properties of polyethylene-metal and polyethylene-ceramic bearings for hip joint replacements: The effect of temperature and protein precipitation in hip simulator tests  

Microsoft Academic Search

Ultra-high-molecular weight polyethylene (PE) cups bearing against metal or ceramic balls are the most commonly used combinations of materials for human hip joint replacements. The wear properties of these materials are typically evaluated in the laboratory using hip joint wear simulators, while lubricated with bovine serum. A previous test evaluating the PE cups against cobalt-chrome (CoCr), zirconia (Zr) and alumina

Yen-Shuo Liao

1999-01-01

28

Oxygen-rich coating promotes binding of proteins and endothelialization of polyethylene terephthalate polymers.  

PubMed

The formation of endothelial cell monolayer on prosthetic implants has not sufficiently explored. The main reasons leading to the development of thrombosis and/or intimal hyperplasia is the lack of endothelialization. In the present work, we have studied the influence of oxygen and fluorine plasma treatment of polyethylene terephthalate (PET) polymers on human microvascular endothelial cell adhesion and proliferation. We characterized the polymer surface, wettability, and oxidation potential upon plasma treatment. Moreover, binding of serum and media compounds on PET surface was monitored by Quartz crystal microbalance method, X-ray photoelectron spectroscopy, and atomic force microscopy. Cell adhesion and morphology was assessed by light and scanning electron microscopy. The influence of plasma treatment on induction of cellular oxidative stress and cell proliferation was evaluated. The results obtained showed that treatment with oxygen plasma decreased the oxidation potential of the PET surface and revealed the highest affinity for binding of serum components. Accordingly, the cells reflected the best adhesion and morphological properties on oxygen-treated PET polymers. Moreover, treatment with oxygen plasma did not induce intracellular reactive oxygen species production while it stimulated endothelial cell proliferation by 25% suggesting the possible use of oxygen plasma treatment to enhance endothelialization of synthetic vascular grafts. PMID:23946257

Jaganjac, Morana; Vesel, Alenka; Milkovic, Lidija; Recek, Nina; Kolar, Metod; Zarkovic, Neven; Latiff, Aishah; Kleinschek, Karin-Stana; Mozetic, Miran

2014-07-01

29

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

PubMed

Rigid porous poly(glycidyl methacrylate-divinylbenzene) (P(GMA-DVB)) microspheres were synthesized through suspension polymerization with a mixture of isooctane and 4-methyl-2-pentonal as the porogen. The microspheres were intended to use as column packing materials for protein separation. However, irreversible adsorption of protein was found on the polymer microsphere. To circumvent the problem, polyethylene glycol (PEG) was coupled to the microspheres. The coupling reaction took place between the hydroxyl group of PEG and the epoxy group of the P(GMA-DVB) solid medium in the presence of boron trifluoride. The density of PEG immobilized onto the P(GMA-DVB) can be determined easily by saponification of modified microsphere firstly and then titration of glycerol-PEG. The effect of the cross-linker content of microsphere on the density of PEG immobilization was investigated. Molecular weight of PEG was found to influence the PEG-immobilization density, which subsequently affects the hydrophilicity of the modified P(GMA-DVB). Bovine serum albumin (BSA) and trypsin were used as model proteins to examine the adsorption and desorption properties of the modified P(GMA-DVB) microspheres. The results demonstrated that P(GMA-DVB) porous microsphere with 20% DVB and modified with PEG4000 showed excellent adsorption and desorption properties. Adsorption capacity of BSA on the modified microsphere attained to 51.6 mg/g microsphere, and BSA mass recovery and trypsin activity recovery was up to 97.6% and 98.7%, respectively. The modified microsphere was demonstrated to be a promising hydrophobic interaction chromatography material for purification of protein. PMID:16824738

Wang, Renwei; Zhang, Ying; Ma, Guanghui; Su, Zhiguo

2006-08-01

30

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

E-print Network

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

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

2014-01-01

31

Nonfouling biomaterials based on polyethylene oxide-containing amphiphilic triblock copolymers as surface modifying additives: adsorption of proteins from human plasma to copolymer/polyurethane blends.  

PubMed

Three polyethylene oxide-polyurethane-polyethylene oxide (PEO-PU-PEO) block copolymers of variable PEO block size (MW 550, 2000, and 5000) were used to modify the surface of a conventional segmented polyurethane (PU) with the objective of inhibiting interactions with proteins. The surface-active copolymers were blended with the PU by solution methods. Protein adsorption from human plasma to the modified materials was investigated using radiolabeling and immunoblotting methods. From the radiolabeling experiments, it was found that fibrinogen adsorption from plasma to all of the modified surfaces was much lower than to the unmodified PU matrix. For blends of low copolymer content, resistance to adsorption was greatest on the copolymer 1 (PEO550)-modified materials, and increased with increasing copolymer content for all three blend types. At high copolymer content inhibition of adsorption was very strong and independent of PEO block size. The immunoblotting experiments showed that on materials of high copolymer content (20 wt %), the proteins investigated (fibrinogen, albumin, complement C3, and apolipoprotein A-I) were undetectable. At low copolymer content (< or = 5 wt %), the blends of copolymer 1, with the shortest PEO block, exhibited greater protein resistance than those of copolymers 2 and 3 (PEO blocks of MW 2000 and 5000, respectively), and resistance decreased with decreasing protein size. Evidence of complement activation was seen for the blends of low copolymer content. Adsorption of C3 and complement activation decreased with increasing content of the copolymers. It was concluded that surface density of PEO is more important than chain length for protein resistance in contact with plasma. PMID:18491394

Tan, J; Brash, J L

2009-07-01

32

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

33

Wear of ultra-high molecular weight polyethylene and polytetrafluoroethylene in a hip simulator: a dose-response study of protein concentration.  

PubMed

Charnley's laboratory wear studies of non-gamma sterilized polytetrafluoroethylene (PTFE) and polyethylene (PE) found that the PTFE to PE wear-rate ratio of 250:1 was much higher than the in-vivo wear ratio of 20:1. Tests of PTFE and PE in our laboratory showed a wear ratio of 150:1, using bovine serum as the lubricant and 190:1 with water as the lubricant. Our hypothesis was that the wear-rates of PTFE and PE cup materials were related to the concentration of protein in the serum. We studied the wear behavior of PTFE and PE cups in varied protein concentrations, using 4 femoral head sizes to validate the clinical range reported by Charnley. The PTFE wear-rates increased with increasing protein concentration and conversely, PE wear-rates decreased with increasing protein concentration. This inverse relationship made it possible to bring the wear ratio closer to the desired clinical wear ratio. We found that the clinically relevant PTFE/PE wear ratio corresponded to 3-10 mg/mL of protein in bovine serum. PMID:11028884

Good, V D; Clarke, I C; Gustafson, G A; Downs, B; Anissian, L; Sorensen, K

2000-08-01

34

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

E-print Network

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

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

2014-11-19

35

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

PubMed

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

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

2014-06-01

36

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

37

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

38

Polyethylene oxide surfaces of variable chain density by chemisorption of PEO-thiol on gold: adsorption of proteins from plasma studied by radiolabelling and immunoblotting.  

PubMed

The mechanisms involved in the inhibition of protein adsorption by polyethylene oxide (PEO) are not completely understood, but it is believed that PEO chain length, chain density and chain conformation all play a role. In this work, surfaces formed by chemisorption of PEO-thiol to gold were investigated: the effects of PEO chain density, chain length (600, 750, 2000 and 5000 MW) and end-group (-OH, -OCH3) on protein adsorption from plasma are reported. Similar to previous single protein adsorption studies (L.D. Unsworth et al., Langmuir 2005;21:1036-41) it was found that, of the different surfaces investigated, PEO layers formed from solutions near the cloud point adsorbed the lowest amount of fibrinogen from plasma. Layers of hydroxyl-terminated PEO of MW 600 formed under these low solubility conditions showed almost complete suppression (versus controls) of the Vroman effect, with 20+/-1 ng/cm2 adsorbed fibrinogen at the Vroman peak and 6.7+/-0.6 ng/cm2 at higher plasma concentration. By comparison, Vroman peak adsorption was 70+/-20 and 50+/-3 ng/cm2, respectively, for 750-OCH3 and 2000-OCH3 layers formed under low solubility conditions; adsorption on these surfaces at higher plasma concentration was 16+/-9 and 12+/-3 ng/cm2. Thus in addition to the effect of solution conditions noted previously, the results of this study also suggest a chain end group effect which inhibits fibrinogen adsorption to, and/or facilitates displacement from, hydroxyl terminated PEO layers. Fibrinogen adsorption from plasma was not significantly different for surfaces prepared with PEO of molecular weight 750 and 2000 when the chain density was the same ( approximately 0.5 chains/nm2) supporting the conclusion that chain density may be the key property for suppression of protein adsorption. The proteins eluted from the surfaces after contact with plasma were investigated by SDS-PAGE and immunoblotting. A number of proteins were detected on the various surfaces including fibrinogen, albumin, C3 and apolipoprotein A-I. The blot responses were zero or weak for all four proteins of the contact system; some complement activation was observed on all of the surfaces studied. PMID:15958239

Unsworth, Larry D; Sheardown, Heather; Brash, John L

2005-10-01

39

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

PubMed Central

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

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

2008-01-01

40

Effect of poly(ethylene glycol), tetramethylammonium hydroxide, and other surfactants on enhancing performance in a latex particle immunoassay of C-reactive protein.  

PubMed

The influence of a variety and combination of both ionic surfactants and different chain lengths of the polyelectrolyte poly(ethylene glycol) (PEG) on the performance characteristics (with particular reference to signal response) of a homogeneous, latex agglutination immunoassay was investigated. The test analyte was human serum C-reactive protein (CRP), and the antibody reagent consisted of a sheep polyclonal anti-CRP IgG fraction covalently coupled to 50-nm-sized latex including a glycine-capped chloromethylstyrene shell. The amount and rate of immunoagglutination was monitored turbidimetrically after sample addition. It was found that 2.5 mmol/L concentrations of the small cationic surfactant tetramethylammonium hydroxide (TMH), when present alone, substantially increased both reaction rates and sensitivity in the lower clinical ranges of CRP concentration when compared to normally used assay conditions containing PEG and the anionic detergent Gafac. The nonspecific binding (NSB) was also found to be unchanged. Evidence is presented that the TMH enhances the actual antibody-antigen interaction as opposed to the known effects of other surfactants in immunocomplex dissociation or in maintenance of colloidal stability. We suggest that the enhancement seen with TMH could be an alternative to PEG and may provide a new means of further extending detection limits. The utility of this type of immunoassay technology could therefore be increased whenever clinically required. PMID:11476244

Holownia, P; Perez-Amodio, S; Price, C P

2001-07-15

41

Immunotherapy with monomethoxypolyethylene glycol modified allergens.  

PubMed

On the basis of the results of experiments in naive mice, i.e., in mice which had not been presensitized, it was anticipated that mPEG-modified allergens would suppress the specific IgE response in allergic humans. However, only minor or no suppression of IgE antibodies was induced on administration of mPEG conjugates in allergic patients with a longstanding IgE response. This observation was later confirmed in pre-sensitized animals. The mPEG-modified allergens can be synthesized in a reproducible manner. This makes mPEG-modified allergens suitable for production and quality control. There is indirect evidence, i.e., identification of IgE and IgG antibody stimulation against all identified allergens, that the relevant determinants are available for processing by the immune system. By contrast, the polymerization of allergens by formaldehyde or glutaraldehyde leads to ill-defined, cross-linked high molecular weight materials. As in the case of other modified allergens, mPEG-modified allergens have been developed primarily because of their lower allergenicity than the original allergen preparations. However, they also retain clinical efficacy of the same magnitude as that induced by unmodified allergen preparations, which is a prerequisite for clinical use. IT with mPEG-modified pollen allergen preparations has been proven to be as effective as IT with unmodified allergens, when these preparations are given in similar doses. Furthermore, a more pronounced beneficial effect can be obtained with higher doses of mPEG-modified allergen, without the risk of side effects which are often precipitated by unmodified allergens. Therefore, it seems reasonable to suggest that children and young adults with developing sensitivity to perennial allergens, and without chronic changes of the bronchial mucosa, are the most suitable candidates for IT with mPEG-modified allergen preparations. Mite asthma, which always includes bronchial inflammation and nonspecific hyperresponsiveness, represents a more complicated model. In mite asthmatics mPEG-modified mite allergen preparations were safer than the corresponding unmodified preparation. Although bronchial sensitivity to allergen and histamine did not change significantly in mite asthmatics during the observation time, it appears that IT with mPEG-modified mite allergen led to a decrease in the releasability of histamine from skin mast cells, as measured by SPT, to a similar degree as observed in pollinosis patients. Therefore, it may be inferred that the allergic component of asthma might be influenced by IT with mPEG allergens. As a consequence, before the start of IT, the degree of reversibility of pathophysiological changes in the bronchial wall should be considered.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2186872

Dreborg, S; Akerblom, E B

1990-01-01

42

Adsorption of peptides and small proteins with control access polymer permeation to affinity binding sites. Part I: Polymer permeation-immobilized metal ion affinity chromatography separation adsorbents with polyethylene glycol and immobilized metal ions.  

PubMed

Despite the many efforts to develop efficient protein purification techniques, the isolation of peptides and small proteins on a larger than analytical scale remains a significant challenge. Recovery of small biomolecules from diluted complex biological mixtures, such as human serum, employing porous adsorbents is a difficult task mainly due to the presence of concentrated large biomolecules that can add undesired effects in the system such as blocking of adsorbent pores, impairing diffusion of small molecules, or competition for adsorption sites. Adsorption and size exclusion chromatography (AdSEC) controlled access media, using polyethylene glycol (PEG) as a semi-permeable barrier on a polysaccharide matrix, have been developed and explored in this work to overcome such effects and to preferentially adsorb small molecules while rejecting large ones. In the first part of this work, adsorption studies were performed with small peptides and proteins from synthetic mixtures using controlled access polymer permeation adsorption (CAPPA) media created by effectively grafting PEG on an immobilized metal affinity chromatography (IMAC) agarose resin, where chelating agents and immobilized metal ions were used as the primary affinity binding sites. Synthetic mixtures consisted of bovine serum albumin (BSA) with small proteins, peptides, amino acids (such as histidine or Val?-Angiotensin III), and small molecules-spiked human serum. The synthesized hybrid adsorbent consisted of agarose beads modified with iminodiacetic (IDA) groups, loaded with immobilized Cu(II) ions, and PEG. These CAPPA media with grafted PEG on the interior and exterior surfaces of the agarose matrix were effective in rejecting high molecular weight proteins. Different PEG grafting densities and PEG of different molecular weight were tested to determine their effect in rejecting and controlling adsorbent permeation properties. Low grafting density of high molecular weight PEG was found to be as effective as high grafting density of low molecular weight PEG in the rejecting properties of the semi-permeable synthesized media. PMID:22281505

González-Ortega, Omar; Porath, Jerker; Guzmán, Roberto

2012-03-01

43

Poly(ethylene glycol)- and carboxylate-functionalized gold nanoparticles using polymer linkages: single-step synthesis, high stability, and plasmonic detection of proteins.  

PubMed

Gold nanoparticles with suitable surface functionalities have been widely used as a versatile nanobioplatform. However, functionalized gold nanoparticles using thiol-terminated ligands have a tendency to aggregate, particularly in many enzymatic reaction buffers containing biological thiols, because of ligand exchange reactions. In the present study, we developed a one-step synthesis of poly(ethylene glycol) (PEG)ylated gold nanoparticles using poly(dimethylaminoethyl methacrylate) (PDMAEMA) in PEG as a polyol solvent. Because of the chelate effect of polymeric functionalities on the gold surface, the resulting PEGylated gold nanoparticles (Au@P-PEG) are very stable under the extreme conditions at which the thiol-monolayer-protected gold nanoparticles are easily coagulated. Using the solvent mixture of PEG and ethylene glycol (EG) and subsequent hydrolysis, gold nanoparticles bearing mixed functionalities of PEG and carboxylate are generated. The resulting particles exhibit selective adsorption of positively charged chymotrypsin (ChT) without nonselective adsorption of bovine serum albumin (BSA). The present nanoparticle system has many advantages, including high stability, simple one-step synthesis, biocompatibility, and excellent binding specificity; thus, this system can be used as a versatile platform for potential bio-related applications, such as separation, sensing, imaging, and assays. PMID:24090031

Park, Garam; Seo, Daeha; Chung, Im Sik; Song, Hyunjoon

2013-11-01

44

Comparison of polyethylene wear in machined versus molded polyethylene.  

PubMed

Polyethylene wear debris has been identified as a cause of osteolysis, granuloma formation, and loosening in total hip arthroplasty. This study was designed to evaluate differences in polyethylene wear rates between acetabular cups machined from extruded bar stock and those direct compression molded. Two hundred thirty-six hip prostheses underwent radiographic evaluation using the technique of Livermore et al. Seventy-four were all-polyethylene cups machined from extruded bar stock, and 162 were all-polyethylene cups direct compression molded. Both groups were similar in that the acetabular and femoral components were all cemented, the acetabular components were all polyethylene, nonmetal backed, and bearing surfaces of both groups were polished, cobalt chrome. The femoral components were TRIAD in the machined group and TR28 in the molded group. Patient matching was performed, assigning 54 patients in each group, whose average age was 66 years old, average followup 6.7 years, and average weight 161 pounds. Rates of polyethylene wear then were compared. Results showed a linear wear rate of 0.05 mm per year for compression-molded polyethylene and 0.11 mm per year for machined polyethylene. Results of this study raise questions regarding the types of polyethylene fabrication and its ultimate molecular weight, and wear resistance. PMID:7671494

Bankston, A B; Keating, E M; Ranawat, C; Faris, P M; Ritter, M A

1995-08-01

45

Nonfouling biomaterials based on polyethylene oxide-containing amphiphilic triblock copolymers as surface modifying additives: protein adsorption on PEO-copolymer/polyurethane blends.  

PubMed

Surface modification of a segmented polyurethane was achieved by blending with novel PEO-containing amphiphilic triblock copolymers (PEO-polyurethane-PEO). Three copolymers having different PEO MW (550, 2000, 5000) were used as surface modification additives. The protein resistance of the blend surfaces was evaluated using radiolabeling methods. On the blends of copolymers with PEO blocks of MW 2000 and 5000, fibrinogen adsorption from physiologic buffer decreased with increasing copolymer content up to 20 wt%. On the blends with PEO blocks of MW 550, resistance to adsorption for a given copolymer content was much greater. For all three blend types at 20% copolymer content, reductions in adsorption compared to the unmodified PU matrix were greater than 95%. Reductions in adsorption were similar for the 20% blends and surfaces prepared by coating the copolymers directly on the matrix, suggesting that the 20% blend surfaces were completely covered by copolymer. At low copolymer content (< or =10 wt %), fibrinogen adsorption decreased with decreasing PEO block length. This was probably due to increasing surface coverage of the copolymers with decreasing block length. It is therefore concluded that surface density of PEO is more important than PEO MW for the protein resistance of these surfaces. Lysozyme, a much smaller protein, showed adsorption trends similar to fibrinogen. The adsorption of fibrinogen and lysozyme from binary solutions to blends of the copolymer with PEO blocks of 2000 MW was investigated to probe the effects of protein size on adsorption resistance. Fibrinogen and lysozyme showed similar fractional decreases in adsorption relative to the PU matrix independent of the surface density of PEO. However lysozyme was enriched in the surface relative to the solution, that is, it was adsorbed preferentially to fibrinogen. PMID:17896776

Tan, J; McClung, W G; Brash, J L

2008-06-15

46

Disintegration of porous polyethylene prostheses.  

PubMed

A Plastipore (porous polyethylene) Total Ossicular Replacement Prosthesis gave an excellent initial hearing result which was maintained for 14 years. Hearing then began to deteriorate and revision surgery showed disintegration of the prosthesis and a defect in the stapes footplate. Histological examination confirmed previous findings in porous polyethylene with multinucleated foreign body giant cells and breakdown of the material. PMID:10384839

Kerr, A G; Riley, D N

1999-06-01

47

Intracellular measurement of polyethylene particles  

Microsoft Academic Search

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

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

2001-01-01

48

A core-shell-type fluorescent nanosphere possessing reactive poly(ethylene glycol) tethered chains on the surface for zeptomole detection of protein in time-resolved fluorometric immunoassay.  

PubMed

To increase the sensitivity and to depress the nonspecific binding in biochemical assays, a new core-shell-type fluorescent nanosphere (106.7 nm) covalently conjugated with antibody was prepared. The core-shell-type nanosphere was constructed by dispersion radical polymerization of styrene in the presence of heterotelechelic poly(ethylene glycol) (PEG) macromonomer, which has a polymerizable vinylbenzyl group at one end and a primary amino group at the other chain end and used as well as a surfactant. The resulting nanosphere had PEG tethered chains on the surface, which possesses a primary amino group at the distal end of the PEG chain (NH(2) nanosphere). The fluorescent NH(2) nanosphere was constructed by incorporating fluorescent europium chelates with beta-diketonate ligands in the core of the NH(2) nanosphere by means of a physical entrapment method. The primary amino groups on the fluorescent NH(2) nanosphere were then converted to maleimide groups using a hetero cross-linker. The resulting nanosphere had maleimide groups on the surface (maleimide nanosphere), onto which proteins having SH group in the molecule could be covalently conjugated quantitatively without any denaturation of the proteins under the milder reaction condition. The applicability of the fluorescent nanosphere was tested in a model sandwich immunoassay for alpha-fetoprotein (AFP) determination. Anti-human AFP Fab' fragment was covalently conjugated onto the maleimide nanosphere (Fab' nanosphere), and it was used for the solid-phase time-resolved fluorometric immunoassay of AFP. The detection limit (mean + 2 SD) was 0.040 pg/mL or 57.1 zmol (57.1 x 10(-)(21) mol, M(w,AFP) = 70000) for AFP. The imprecision (concentration CV) over the whole assay range was 1.1% (100 pg/mL) - 17.1% (0.1 pg/mL), even though with this conjugation of antibody to the nanosphere, the nonspecific binding was practically negligible (0.0008%) and even when approximately 1.9 x 10(9) particles of the Fab' nanosphere were applied to the microtitration well. PMID:14615991

Matsuya, Takeshi; Tashiro, Shigeru; Hoshino, Nobuhiro; Shibata, Naoya; Nagasaki, Yukio; Kataoka, Kazunori

2003-11-15

49

Degradable polyethylene: fantasy or reality.  

PubMed

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

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

2011-05-15

50

21 CFR 177.1620 - Polyethylene, oxidized.  

...accordance with the following prescribed conditions: (a) Oxidized polyethylene is the basic resin produced by the mild air oxidation of polyethylene conforming to the density, maximum n- hexane extractable fraction, and maximum xylene soluble...

2014-04-01

51

21 CFR 177.1620 - Polyethylene, oxidized.  

Code of Federal Regulations, 2012 CFR

...ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact...conditions: (a) Oxidized polyethylene is the basic resin produced by the mild air oxidation of polyethylene conforming to the density,...

2012-04-01

52

21 CFR 177.1620 - Polyethylene, oxidized.  

Code of Federal Regulations, 2013 CFR

...ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact...conditions: (a) Oxidized polyethylene is the basic resin produced by the mild air oxidation of polyethylene conforming to the density,...

2013-04-01

53

Pyroelectric properties of polyethylene oxide  

NASA Astrophysics Data System (ADS)

Transformations of the structure and changes in the polarization properties of polyethylene oxide are investigated in the crystallization region. It is demonstrated that the pyroelectric coefficient of this polymer is considerably higher than the corresponding parameter for polyvinylidene fluoride and is nearly equal to the pyroelectric coefficient for triglycine sulfate.

Korotkikh, N. I.; Matveev, N. N.; Sidorkin, A. S.

2009-06-01

54

Evaluation of polyethylene-modified asphalt blends  

E-print Network

presents a detailed study of polyethylene-modified asphalts (Novophalt) and polyethylene-modified asphalt concrete mixtures. Extensive testing was conducted to evaluate the fatigue, fracture potential and permanent deformation properties of polyethylene...-modified asphalt concrete mixtures. The influence of aging of asphalt on mixture performance was also studied. Pertinent information and data found in the literature is also discussed in order to support, challenge and evaluate the findings. In summary...

Consuegra Granger, Fernando

2012-06-07

55

Single electron states in polyethylene  

NASA Astrophysics Data System (ADS)

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.; MacKernan, D.; Cubero, D.; Coker, D. F.; Quirke, N.

2014-04-01

56

Shock induced dissociation of polyethylene  

SciTech Connect

To identify the physical processes occurring on the Hugoniot, shock-recovery experiments were performed. Cylindrical recovery systems were used that enabled a wide range of single-shock Hugoniot states to be examined. Mass spectroscopy was used to examine the gaseous dissociation products. X-ray and TEM measurements were made to characterize the post-shock carbon structures. A dissociation product equation of state is presented to interpret the observed results. Polyethylene (PE) samples that were multiply shocked to their final states dissociated at much higher pressures than single-shocked samples. 5 refs., 2 figs., 1 tab.

Morris, C.E.; Loughran, E.D.; Mortensen, G.F.; Gray, G.T. III; Shaw, M.S.

1989-01-01

57

40 CFR 721.6493 - Amidoamine modified polyethylene glycol (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Amidoamine modified polyethylene glycol (generic). 721.6493... § 721.6493 Amidoamine modified polyethylene glycol (generic). (a) Chemical...generically as an amidoamine modified polyethylene glycol (PMN P-99-0645) is...

2010-07-01

58

21 CFR 178.3760 - Polyethylene glycol (400) monolaurate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Polyethylene glycol (400) monolaurate. 178.3760...Adjuvants and Production Aids § 178.3760 Polyethylene glycol (400) monolaurate. Polyethylene glycol (400) monolaurate containing...

2011-04-01

59

40 CFR 721.6493 - Amidoamine modified polyethylene glycol (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Amidoamine modified polyethylene glycol (generic). 721.6493... § 721.6493 Amidoamine modified polyethylene glycol (generic). (a) Chemical...generically as an amidoamine modified polyethylene glycol (PMN P-99-0645) is...

2011-07-01

60

Diffusion of limonene in polyethylene.  

PubMed

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

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

2006-07-01

61

Nanoscale Calorimetry of Isolated Polyethylene Single Crystals  

E-print Network

Nanoscale Calorimetry of Isolated Polyethylene Single Crystals A. T. KWAN, M. YU. EFREMOV, E. A-film differential scanning calorimetry to investigate the melt- ing of isolated polyethylene single crystals: microelectromechanical systems; calorimetry; nanocalorimetry; polyeth- ylene single crystals; melting INTRODUCTION We

Allen, Leslie H.

62

Photon tunnelling microscopy of polyethylene single crystals  

E-print Network

Photon tunnelling microscopy of polyethylene single crystals Mohan Srinivasarao* and Richard S polyethylenesinglecrystals, providing a topographical map ofthe single-crystal surface.Tunnelling increases exponentially:photon tunnellingmicroscopy;single crystals; polyethylene) INTRODUCTION The study of morphology of polymers is an area

Srinivasarao, Mohan

63

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

64

Irradiation effects in high-density polyethylene  

NASA Astrophysics Data System (ADS)

Using molecular dynamics simulations, we have studied the irradiation effects in high density polyethylene. We found that the governing reactions were chain scissioning and generation of free radicals, whereas cross-linking and recombination of chain fragments was rare. We also determined the threshold energy for creating defects in the polyethylene lattice as a function of the incident angle. Our analysis on the damage threshold energy shows that it is strongly dependent on the initial recoil direction and on average two times higher for the carbon atoms than for the hydrogen atoms in the polyethylene chain.

Polvi, Jussi; Nordlund, Kai

2013-10-01

65

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

2012-06-07

66

Polyethylene wear in total hip arthroplasty.  

PubMed

Polyethylene wear increasingly has been blamed for osteolysis and granuloma formation after total joint arthroplasty. The authors evaluated the wear difference between bearing surfaces of stainless steel, cobalt chrome, and titanium alloy. They also compared cemented all-polyethylene molded cups with cemented metal-backed molded acetabular cups. These were compared with molded and machined polyethylene cups. Two patient groups were matched individually for gender, age, weight, and length of followup. Analyses were done using the technique of Livermore et al. The bearing surface evaluation consisted of 3 groups after matching, leaving 77 patients per group. Results showed linear wear rates of 0.06 mm per year, 0.05 mm per year, and 0.08 mm per year for stainless steel, cobalt chrome, and titanium alloy, respectively. The comparison between cemented molded metal-backed and nonmetal-backed acetabular components was not matched, with 134 metal-backed and 99 nonmetal-backed components. Results showed linear wear rates of 0.011 mm per year in the metal-backed group and 0.08 mm per year in the nonmetal-backed group. Results were statistically significant. These results indicate that the metal composition of the femoral bearing surface has minimal, if any, effect on the linear polyethylene wear rate. The method of polyethylene fabrication and the use of metal backing had a significant effect on the polyethylene wear rate in these patient groups. These results suggest that the compression-molded all-polyethylene acetabular component may be optimal for reducing polyethylene wear in total hip arthroplasty. PMID:7671498

Bankston, A B; Cates, H; Ritter, M A; Keating, E M; Faris, P M

1995-08-01

67

Cranklike conformational transitions in polyethylene  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations of a variety of polymeric systems provide the evidence for two different kinds of conformational transitions: independent single bond transitions and cranklike transitions (or correlated bond transitions). While single bond transitions can be rationalized according to standard theories of activated processes controlled by the saddle point crossing, a more complex description is required for the other type of transitions. In a recent work devoted to the analysis of the simplified chain model with three rotors [B. Nigro and G. J. Moro, J. Phys. Chem. B 106, 7365 (2002)], a theory has been proposed for cranklike transitions represented as a kinetic process between equilibrium states differing by two torsional angles (i.e., two bond transitions). Moreover their rate coefficients were estimated on the basis of a local expansion about the bifurcation of the separatrices departing from the potential function maximum. In the present work the same theory is applied to a model for long alkyl chains in solution, in order to rationalize the behavior of cranklike transitions in polyethylene and to recognize the molecular features controlling them. We obtain probabilities of occurrence of cranklike transitions in substantial agreement with simulation results. Furthermore, the theory is capable of explaining the dependence of the rate on the separation between the two reactive bonds, as well as the dependence on the conformational state of the starting configuration. In particular, selection rules for next-to-nearest neighbor transitions are recovered from the shape of the separatrices and the location of the corresponding bifurcations.

Nigro, B.; di Stefano, D.; Rassu, A.; Moro, G. J.

2004-09-01

68

40 CFR 721.7255 - Polyethyleneamine crosslinked with substituted polyethylene glycol (generic).  

Code of Federal Regulations, 2010 CFR

...Polyethyleneamine crosslinked with substituted polyethylene glycol (generic). 721.7255...Polyethyleneamine crosslinked with substituted polyethylene glycol (generic). (a) Chemical...polyethyleneamine crosslinked with substituted polyethylene glycol with substituted...

2010-07-01

69

40 CFR 721.7255 - Polyethyleneamine crosslinked with substituted polyethylene glycol (generic).  

Code of Federal Regulations, 2011 CFR

...Polyethyleneamine crosslinked with substituted polyethylene glycol (generic). 721.7255...Polyethyleneamine crosslinked with substituted polyethylene glycol (generic). (a) Chemical...polyethyleneamine crosslinked with substituted polyethylene glycol with substituted...

2011-07-01

70

Current sterilization and packaging methods for polyethylene.  

PubMed

Gamma sterilization in an air environment can induce oxidation in polyethylene. Oxidation can lead to polyethylene embrittlement, compromising mechanical integrity and clinical performance of polyethylene bearings. For these reasons, orthopaedic manufacturers have modified their methods of sterilizing and packaging polyethylene. Two alternative approaches have emerged: sterilization by non-radiation methods and sterilization by gamma irradiation in inert environments. The current study presents a prognosis for clinical performance of polyethylene sterilized with new methods, based on material property analyses (oxidation levels, mechanical properties, crosslink density) of never implanted and retrieved bearings. Data from bearings that were never implanted which were sterilized with the new methods and shelf aged as many as 3 years, show negligible oxidation, ductility above 400%, and ultimate tensile strength near 50 MPa, all exceeding specifications of the American Society for Testing and Materials. There are significant differences in crosslink density (swell ratio) depending on the sterilization method. Retrievals indicate that bearings sterilized with these new methods are performing well clinically and that the majority are not changing with time. The current study suggests that the shelf oxidation problem has been addressed by these new sterilization techniques and that clinical performance at short followup is acceptable. However, long-term clinical performance must be evaluated in the future. PMID:10611860

Bargmann, L S; Bargmann, B C; Collier, J P; Currier, B H; Mayor, M B

1999-12-01

71

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

72

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

73

Proteins  

NSDL National Science Digital Library

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

Mowery, Jeanette; Seidman, Lisa A.

2009-10-01

74

Elongational rheology of polyethylene melts  

NASA Astrophysics Data System (ADS)

Elongational melt flow behavior is an important and fundamental concept underlying many industrial plastics operations which involve a rapid change of shape as for example fiber spinning and stretching, bottle blow molding, and film blowing and stretching. Under high process loads polymeric materials experience enormous stresses causing the molecular structure to gain considerable orientation. This event has significant effects on the melt flow behavior and can be measured in terms of elongational viscosity and changes in enthalpy and entropy. Different polymeric materials with unique molecular characteristics are expected to respond uniquely to the elongational deformation; hence, molecular parameters such as molecular weight and degree of branching were related to the measurable elongational flow variables. Elongational viscosities were measured for high and low density polyethylenes using an advanced capillary extrusion rheometer fitted with semi-hyperbolic dies. Said dies establish a purely elongational. flow field at constant elongational strain rate. The elongational viscosities were evaluated under influence of process strain rate, Hencky strain (natural logarithm of area reduction of the extrusion die), and temperature. Enthalpy and entropy changes associated with the orientation development of semi-hyperbolic processed melts were also determined. Results showed that elongational viscosities were primarily affected by differences in weight average molecular weight rather than degree of branching. This effect was process strain rate as well as temperature dependent. An investigation of melt relaxation and the associated first decay time constants revealed that with increasing strain rate the molecular field of the melt asymptotically gained orientation in approaching a limit. As a result of this behavior molecular uniqueness vanished at high process strain rates, yielding to orientation development and the associated restructuring of the melt's molecular morphology. Flow induced orientation was measured in form of enthalpy changes that were largest for the highest elongational strain rates and larger Hencky strain. The enthalpy changes were in magnitude one order lower than the polymer's heat of fusion. This explained why peak melt temperatures, evaluated by differential scanning calorimetry, remained unchanged in magnitude with a rise in process strain rate and Hencky strain.

Seyfzadeh, Bijan

75

Nasal reconstruction using porous polyethylene implants.  

PubMed

Nasal reconstruction presents a significant challenge to the facial plastic surgeon. The dual goals of reconstruction are restoration of the desired aesthetic nasal contour and an improved nasal airway. Autologous cartilage and bone are considered optimal grafting material, but their supply is often limited and harvesting entails additional morbidity. Many synthetic materials have been introduced in nasal reconstruction, but high infection and extrusion rates limited their use. Porous high density polyethylene implants present an alternative to autologous material as they allow for fibrovascular ingrowth, leading to stability of the implant and decreased rates of infection. Herein we describe the use of porous high density polyethylene implants for reconstruction of the platyrrhine nose and in revision rhinoplasty. The use of preformed nasal-dorsal tip and alar batten implants are described, as well as the use of columellar strut and premaxillary plumper implants. We believe that porous high density polyethylene implants provide a safe, desirable alternative in functional and aesthetic nasal reconstruction. PMID:11802347

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

2000-01-01

76

21 CFR 178.3760 - Polyethylene glycol (400) monolaurate.  

Code of Federal Regulations, 2010 CFR

...Production Aids § 178.3760 Polyethylene glycol (400) monolaurate. Polyethylene glycol (400) monolaurate containing not more than 0.1 percent by weight of ethylene and/or diethylene glycol may be used at a level not to...

2010-04-01

77

Alumina-on-Polyethylene Bearing Surfaces in Total Hip Arthroplasty  

PubMed Central

The long-term durability of polyethylene lining total hip arthroplasty (THA) mainly depends on periprosthetic osteolysis due to wear particles, especially in young active patients. In hip simulator study, reports revealed significant wear reduction of the alumina ceramic-on-polyethylene articulation of THA compared with metal-on-polyethylene bearing surfaces. However, medium to long-term clinical studies of THA using the alumina ceramic-on-polyethylene are few and the reported wear rate of this articulation is variable. We reviewed the advantages and disadvantages of ceramicon- polyethylene articulation in THA, hip simulator study and retrieval study for polyethylene wear, in vivo clinical results of THA using alumina ceramic-on-polyethylene bearing surfaces in the literature, and new trial alumina ceramic-onhighly cross linked polyethylene bearing surfaces. PMID:20224739

Jung, Yup Lee; Kim, Shin-Yoon

2010-01-01

78

An exposure assessment survey of the Mont Belvieu polyethylene plant  

E-print Network

that handles the extrusion of the polyethylene pellets, blended additives with polyethylene flake, unloaded dry additives from supply trucks, and monitored and adjusted equipment. The LLDPE work area was also divided into three worker groups: reactor... that handles the extrusion of the polyethylene pellets, blended additives with polyethylene flake, unloaded dry additives from supply trucks, and monitored and adjusted equipment. The LLDPE work area was also divided into three worker groups: reactor...

Tucker, Thomas Franklin

2012-06-07

79

Chemically coupled hydroxyapatite-polyethylene composites: processing and characterisation  

Microsoft Academic Search

Hydroxyapatite (HA)-reinforced polyethylene was developed as a bone replacement material. In order to improve bonding between HA and polyethylene, and hence to increase mechanical properties of the composite, chemical treatments of HA and polyethylene were investigated and new composites manufactured. Two approaches were employed in this investigation: the use of silane-treated HA as the filler, and the application of polymer

M Wang; S Deb; W Bonfield

2000-01-01

80

Isolation and characterization of polyethylene-biodegrading mycromycetes  

Microsoft Academic Search

The polyethylene biodegradation by microorganisms is a solution for the reduction of the plastics pollution. Isolation and characterization of the fungi capable to degrade the polyethylene are reported, as well as the conditions of pH and temperature in which they showed the higher activity. Fungi were isolated from polyethylene products obtained of sanitary landfill; the identification was realized in base

Carmen R. Méndez; Germán Vergaray; Vilma R. Béjar; Karina J. Cárdenas

81

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...

82

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 ...

83

EFFECT OF RADIATION ON CREEP OF POLYETHYLENE  

Microsoft Academic Search

An investigation was conducted of the influence of radiation on the ; creep of polyethylene in tension and compression. The influence of five ; radiation doses and four stress levels were considered in this study. The tests ; were conducted for periods of 1000 hr. Even for small doses of radiation, it was ; found that the creep resistance of

Joseph Marin; Paul B. Griesacker

1963-01-01

84

21 CFR 177.1620 - Polyethylene, oxidized.  

Code of Federal Regulations, 2011 CFR

...CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances...Components of Single and Repeated Use Food Contact Surfaces § 177.1620...safely used as a component of food-contact articles, in accordance...resin produced by the mild air oxidation of polyethylene conforming...

2011-04-01

85

Polyethylene glycol as an alternative polymer solvent for nanoparticle preparation.  

PubMed

Solvent toxicity is one of the major drawbacks in the preparation of polymeric nanoparticles today. Here, polyethylene glycols (PEGs) are proposed as non-toxic solvents for the preparation of polymeric nanoparticles. Based on a preparation process similar to the solvent displacement technique, several process parameters were examined for their effects on the properties of the prepared nanoparticles by this method to achieve the optimum preparation conditions. The investigated parameters included polymer type and concentration, volume and temperature of the dispersing phase, methods of dispersing the solvent phase into the non-solvent phase, duration and speed of stirring and washing by dialysis. Ammonio methacrylate copolymer (Eudragit RL), poly-lactide-co-glycolide (PLGA), and PEG-PLGA were found to be successful polymer candidates for the preparation of nanoparticles by this method. Nanoparticles with diameters ranging from 80 to 400 nm can be obtained. The encapsulation efficiencies of bovine serum albumin, and lysozyme as model proteins were ranging from 7.3±2.2% to 69.3±1.8% depending on the strength of polymer-protein interaction. Biological assays confirmed a full lysozyme activity after the preparation process. PEG proved to be a suitable non-toxic solvent for the preparation of polymeric protein-loaded nanoparticles, maintaining the integrity of protein. PMID:23958752

Ali, Mohamed Ehab; Lamprecht, Alf

2013-11-01

86

Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India.  

PubMed

Sixty marine bacteria isolated from pelagic waters were screened for their ability to degrade low-density polyethylene; among them, three were positive and able to grow in a medium containing polythene as the sole carbon source. The positive isolates were identified as Kocuria palustris M16, Bacillus pumilus M27 and Bacillus subtilis H1584 based on the 16S rRNA gene sequence homology. The weight loss of polyethylene was 1%, 1.5% and 1.75% after 30 days of incubation with the M16, M27 and H1584 isolates, respectively. The maximum (32%) cell surface hydrophobicity was observed in M16, followed by the H1584 and M27 isolates. The viability of the isolates growing on the polyethylene surface was confirmed using a triphenyltetrazolium chloride reduction test. The viability was also correlated with a concomitant increase in the protein density of the biomass. Polyethylene biodegradation was further confirmed by an increase in the Keto Carbonyl Bond Index, the Ester Carbonyl Bond Index and the Vinyl Bond Index, which were calculated from FT-IR spectra. PMID:24210946

Harshvardhan, Kumar; Jha, Bhavanath

2013-12-15

87

Diagnosing long-chain branching in polyethylenes  

NASA Astrophysics Data System (ADS)

We propose a novel method for assessing sparse long-chain branching in synthetic polymers such as high-density polyethylene at levels far below the limits of detectability by the usual methods of solution viscometry, size-exclusion chromatography, and NMR spectrometry on solutions. The new method exploits the extreme sensitivity of melt Newtonian viscosity to random branching architecture, along with the systematic phenomenological description thereof developed recently in fundamental studies by Lusignan et al. The method satisfies the only validation criterion presently available to us: it finds long-branch contents in quantitative agreement with stoichiometric yields calculated for several series of linear precursor polyethylenes treated with very low levels of peroxide.

Janzen, J.; Colby, R. H.

1999-08-01

88

Temperature Adaptable Hollow Fibers Containing Polyethylene Glycols  

Microsoft Academic Search

Polyethylene glycols (PEG's with average molecular weights of 400, 600, 1,000 and 3,350) incorporated as 57% aq. solutions into hollow rayon and polypropylene fibers, after drying and conditioning, produced heat contents (Q) 1.2-2.5 times greater than untreated hollow polypropylene and 2.2-4.4 times greater than untreated hollow rayon fibers. The resultant Q values in a given temperature interval were reproducible for

Tyrone L. Vigo; Cynthia M. Frost

1983-01-01

89

Polyethylene bags and solar ultraviolet radiation  

SciTech Connect

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

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

1993-01-22

90

Photolithographic patterning of polyethylene glycol hydrogels  

Microsoft Academic Search

A simple, inexpensive photolithographic method for surface patterning deformable, solvated substrates is demonstrated using photoactive poly(ethylene glycol) (PEG)-diacrylate hydrogels as model substrates. Photolithographic masks were prepared by printing the desired patterns onto transparencies using a laser jet printer. Precursor solutions containing monoacryloyl-PEG-peptide and photoinitiator were layered onto hydrogel surfaces. The acrylated moieties in the precursor solution were then conjugated in

Mariah S. Hahn; Lakeshia J. Taite; James J. Moon; Maude C. Rowland; Katie A. Ruffino; Jennifer L. West

2006-01-01

91

Thermally Active Fabrics Containing Polyethylene Glycols  

Microsoft Academic Search

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

Joseph S. Bruno; Tyrone L. Vigo

1987-01-01

92

Carrier transport in high-density polyethylene  

Microsoft Academic Search

Current peaks due to transient SCLC were observed both in high-density polyethylene (HD-PE) and in oxidised HD-PE in the temperature range 50-90 degrees C. From the time at which the current peak occurs, carrier mobilities ranging from 10-11 to 10-9 cm2 V-1 s-1 were obtained. The mobility values obtained agree well with those evaluated from surface-charge decay measurements. They strongly

T. Mizutani; M. Ieda

1979-01-01

93

Comparative wear tests of ultra-high molecular weight polyethylene and cross-linked polyethylene.  

PubMed

Wear particle-induced osteolysis is a major concern in hip implant failure. Therefore, recent research work has focussed on wear-resistant materials, one of the most important of which is cross-linked polyethylene. In view of this, the objective of this study was to compare the in vitro wear performance of cross-linked polyethylene to traditional ultra-high molecular weight polyethylene. In order to mimic appropriate in vivo conditions, a novel high-capacity wear tester called a circularly translating pin-on-disc was used. The results of this in vitro study demonstrated that the wear rate for cross-linked polyethylene was about 80% lower than that of conventional ultra-high molecular weight polyethylene. This difference closely matches in vivo results reported in the literature for total hip replacements that use the two biopolymers. The in vitro results were also verified against ASTM F732-00 (standard test method for wear testing of polymeric materials for use in total joint prostheses). The 50-station circularly translating pin-on-disc proved to be a reliable device for in vitro wear studies of orthopaedic biopolymers. PMID:23637270

Harsha, A P; Joyce, Tom J

2013-05-01

94

Polyethylene solidification of low-level wastes  

SciTech Connect

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

Kalb, P.D.; Colombo, P.

1985-02-01

95

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

96

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

97

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

98

Abiotic and biotic degradation of oxo-biodegradable polyethylenes  

Microsoft Academic Search

Conventional polymeric materials accumulate in the environment due to their low biodegradability. However, an increase in the biodegradation rate of these polymers may be obtained with the addition of pro-degrading substances. This study aimed to evaluate abiotic and biotic degradation of polyethylenes (PEs) using plastic bags of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) formulated with pro-oxidant additives as

Telmo F. M. Ojeda; Emilene Dalmolin; Maria M. C. Forte; Rodrigo J. S. Jacques; Fátima M. Bento; Flávio A. O. Camargo

2009-01-01

99

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

100

Development of Macroporous Poly(ethylene glycol) Hydrogel Arrays Within Microfluidic Channels  

PubMed Central

The mass transport of solutes through hydrogels is an important design consideration in materials used for tissue engineering, drug delivery, and protein arrays used to quantify protein concentration and activity. We investigated the use of poly(ethylene glycol) (PEG) as a porogen to enhance diffusion of macromolecules into the interior of polyacrylamide and PEG hydrogel posts photopatterned within microfluidic channels. The diffusion of GST–GFP and dextran–FITC into hydrogels was monitored and effective diffusion coefficients were determined by fitting to the Fickian diffusion equations. PEG-diacrylate (Mr 700) with porogen formed a macroporous structure and permitted significant penetration of 250 kDa dextran. Proteins copolymerized in these macroporous hydrogels retained activity and were more accessible to antibody binding than proteins copolymerized in nonporous gels. These results suggest that hydrogel macroporosity can be tuned to regulate macromolecular transport in applications such as tissue engineering and protein arrays. PMID:21028794

Lee, Andrew G.; Arena, Christopher P.; Beebe, David J.; Palecek, Sean P.

2010-01-01

101

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

102

Osmotic Pressure of Aqueous Polyethylene Glycols 1  

PubMed Central

Osmotic pressures (II) of aqueous solutions of polyethylene glycols (PEGs) of average relative molecular weight (Mr) between 200 and 10,000 were measured using vapor pressure deficit osmometry. The relationships between molarity and II were described with high precision by second order polynomials for each of the PEGs studied. In contrast to previous reports, equivalent weights of different polymers in solution did not generate the same II; low Mr PEGs generated a higher II than the higher Mr PEGs. The effect of PEGs upon II represents an interaction between concentration and Mr. PMID:16667097

Money, Nicholas P.

1989-01-01

103

Electrostatic electrochemistry: Nylon and polyethylene systems  

NASA Astrophysics Data System (ADS)

Electrostatic charges generated on polymer surfaces by contact electrification e.g. polyethylene (PE) contacted with polyamide (Nylon), are capable of carrying out redox reactions. For example, metal ions such as Pd 2+, Ag +, and Cu 2+ were reduced, leading to a metal film deposition on the polymer, Fe(CN)63- was reduced to Fe(CN)64-, and chemiluminescence was produced. These results reinforce the electron transfer mechanism of contact electrification and the concept of 'single electrode electrochemistry' using PE or Nylon (or PTFE) as the source of charge. From the extent of the redox reactions, one estimates charge densities of up to about 10 14/cm 2.

Liu, Chong-yang; Bard, Allen J.

2010-01-01

104

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Polyethylene glycol (400) mono- and dioleate...Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and...

2011-04-01

105

21 CFR 573.800 - Polyethylene glycol (400) mono- and dioleate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Polyethylene glycol (400) mono- and dioleate...Additive Listing § 573.800 Polyethylene glycol (400) mono- and dioleate. (a) The food additive polyethylene glycol (400) mono- and...

2010-04-01

106

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

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Polyethylene glycol (mean molecular weight 200-9...and Production Aids § 178.3750 Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol identified in this...

2011-04-01

107

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

Code of Federal Regulations, 2013 CFR

...Pentenylated polyethylene glycol sulfate salt (generic). 721.10546...Pentenylated polyethylene glycol sulfate salt (generic). (a) Chemical...polyethylene glycol sulfate salt (PMN P-04-340) is subject...uses are: (i) Release to water. Requirements as...

2013-07-01

108

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

Federal Register 2010, 2011, 2012, 2013

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

2010-05-04

109

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-886] Polyethylene Retail Carrier Bags From the People's Republic...antidumping duty order on polyethylene retail carrier bags (PRCBs) from the People's...2012, the petitioners, the Polyethylene Retail Carrier Bag Committee and its...

2013-01-02

110

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Preliminary...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Thailand...Antidumping Duty Order: Polyethylene Retail Carrier Bags From Thailand, 69 FR...

2010-09-02

111

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Results...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Thailand...1\\ See Polyethylene Retail Carrier Bags from Thailand:...

2013-08-19

112

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Correction...antidumping duty order on polyethylene retail carrier bags from Thailand for the period...antidumping duty order on polyethylene retail carrier bags from Thailand. See...

2011-11-16

113

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags from Thailand: Rescission...antidumping duty order on polyethylene retail carrier bags from Thailand. The period...response to requests from the Polyethylene Retail Carrier Bag Committee and its...

2010-06-18

114

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Preliminary...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Thailand...antidumping duty order is polyethylene retail carrier bags, which are currently...

2013-05-14

115

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-557-813] Polyethylene Retail Carrier Bags From Malaysia: Preliminary...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Malaysia...Antidumping Duty Order: Polyethylene Retail Carrier Bags From Malaysia, 69 FR...

2010-06-15

116

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

Federal Register 2010, 2011, 2012, 2013

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

2013-12-17

117

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-557-813] Polyethylene Retail Carrier Bags From Malaysia: Final Results...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Malaysia...parties to comment. See Polyethylene Retail Carrier Bags From Malaysia:...

2010-10-04

118

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

Federal Register 2010, 2011, 2012, 2013

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

2010-05-04

119

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Results...antidumping duty order on polyethylene retail carrier bags from Thailand. We gave interested...the Department) published Polyethylene Retail Carrier Bags From Thailand:...

2011-09-28

120

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Rescission...antidumping duty order on polyethylene retail carrier bags from Thailand. The period...antidumping duty order on polyethylene retail carrier bags from Thailand. See...

2012-05-01

121

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

Federal Register 2010, 2011, 2012, 2013

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

2010-04-01

122

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

Federal Register 2010, 2011, 2012, 2013

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

2011-03-01

123

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Preliminary...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Thailand...Antidumping Duty Order: Polyethylene Retail Carrier Bags From Thailand, 69 FR...

2011-05-24

124

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

Federal Register 2010, 2011, 2012, 2013

...Administration [C-552-805] Polyethylene Retail Carrier Bags from the Socialist Republic...producers and exporters of polyethylene retail carrier bags (PRCBs) from the Socialist...September 4, 2009. See Polyethylene Retail Carrier Bags from the Socialist...

2010-04-01

125

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

Federal Register 2010, 2011, 2012, 2013

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

2011-03-08

126

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-583-843] Polyethylene Retail Carrier Bags From Taiwan: Initiation...response to a request from The Polyethylene Retail Carrier Bag Committee and its individual...whether imports of unfinished polyethylene retail carrier bags (PRCBs) on a roll...

2013-07-31

127

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

Federal Register 2010, 2011, 2012, 2013

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

2012-01-20

128

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-886] Polyethylene Retail Carrier Bags From the People's Republic...response to a request from The Polyethylene Retail Carrier Bag Committee and its individual...whether imports of unfinished polyethylene retail carrier bags (PRCBs) from the...

2013-05-14

129

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

130

Self-Healing of Polyethylene Oxide  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

131

21 CFR 177.1630 - Polyethylene phthalate polymers.  

...Polymers by the Hot Stage Microscopy...for Density of Plastics by the Density-Gradient...solvents at temperatures and times indicated... ) those at temperatures over 49 °C...Polyethylene phthalate plastics conforming...volume, at temperatures not exceeding...Polyethylene phthalate plastics,...

2014-04-01

132

21 CFR 177.1630 - Polyethylene phthalate polymers.  

Code of Federal Regulations, 2013 CFR

...Polymers by the Hot Stage Microscopy...for Density of Plastics by the Density-Gradient...solvents at temperatures and times indicated... ) those at temperatures over 49 °C...Polyethylene phthalate plastics conforming...volume, at temperatures not exceeding...Polyethylene phthalate plastics,...

2013-04-01

133

21 CFR 177.1630 - Polyethylene phthalate polymers.  

Code of Federal Regulations, 2012 CFR

...Polymers by the Hot Stage Microscopy...for Density of Plastics by the Density-Gradient...solvents at temperatures and times indicated... ) those at temperatures over 49 °C...Polyethylene phthalate plastics conforming...volume, at temperatures not exceeding...Polyethylene phthalate plastics,...

2012-04-01

134

Degradation profile of polyethylene after artificial accelerated weathering  

Microsoft Academic Search

Elucidation of the chemical changes that take place during the aging of polyethylene sheared electrical cables, and the correlation of these changes with physical properties need experiments with accelerated aging assays. These were carried out using the most representative polyethylene grades found in today's market: low density (LDPE), linear low density (LLDPE) and high density (HDPE). The samples were exposed

J. V. Gulmine; P. R. Janissek; H. M. Heise; L. Akcelrud

2003-01-01

135

Ultradrawing gel films of blends of ultrahigh molecular weight polyethylene and low molecular weight polyethylenes with different molecular weights  

Microsoft Academic Search

The ultradrawing behavior of five series of gel films prepared from the blends of one ultrahigh molecular weight polyethylene (UHMWPE) and five other low molecular weight polyethylene (LMWPE) resins with varying molecular weight is reported. The critical draw ratio (?c) of each of the five UHMWPE\\/LMWPE gel film series were found to depend significantly upon the amount of LMWPE present

Jen-Taut Yeh; Sheng-Shang Chang

2000-01-01

136

Thermal transport in polyethylene and at polyethylene-diamond interfaces investigated using molecular dynamics simulation.  

PubMed

The thermal conductances across covalently bonded interfaces between oriented single crystal diamond and completely aligned polyethylene chains are determined for the three principal orientations of diamond. The calculated thermal conductances, which range over 690-930 MW m(-2) K(-1), are consistent with those of other strongly bonded interfaces. These results suggest that the experimental interfacial conductances across hard-soft interfaces can be quite large if the bonding across the interface is strong, a conclusion that could have important implications for thermal management in bioelectromechanical systems and other inorganic-organic structures. The effects of defects and cross-linking on the thermal conductivity of polyethylene are also analyzed. PMID:21817371

Ni, Boris; Watanabe, Taku; Phillpot, Simon R

2009-02-25

137

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

NASA Astrophysics Data System (ADS)

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

Puig, C.; Gomez, S.; Castañeda, R.

1997-03-01

138

Impact behavior of hydroxyapatite reinforced polyethylene composites.  

PubMed

Hydroxyapatite particulate reinforced high density polyethylene composite (HA-HDPE) has been developed as a bone replacement material. The impact behavior of the composites at 37 degrees C has been investigated using an instrumented falling weight impact testing machine. The fracture surfaces were examined using SEM and the fracture mechanisms are discussed. It was found that the fracture toughness of HA-HDPE composites increased with HDPE molecular weight, but decreased with increasing HA volume fraction. Examination of fracture surfaces revealed weak filler/matrix interfaces which can debond easily to enable crack initiation and propagation. Increasing HA volume fraction increases the interface area, and more cracks can form and develop, thus decreasing the impact resistance of the composites. Another important factor for the impact behavior of the composites is the matrix. At higher molecular weight, HDPE is able to sustain more plastic deformation and dissipates more impact energy, hence improving the impact property. PMID:15348540

Zhang, Y; Tanner, K E

2003-01-01

139

Commercialization of the polyethylene macroencapsulation process  

SciTech Connect

With support from the US Department of Energy Office of Science and Technology (DOE OST) and assistance from Brookhaven National Laboratory (BNL), Envirocare of Utah, Inc. (Envirocare) is commercializing the polyethylene macroencapsulation process. Envirocare, currently the only commercially licensed mixed waste disposal facility in the US, will initially demonstrate the process by treating and disposing up to 227,000 kg (500,000 lbs) of radioactively contaminated lead. This waste, considered mixed due to both radioactive and hazardous constituents, is currently being stored at various sites throughout the DOE complex. Following this initial work for DOE, the process will be available for the treatment of other applicable wastes. Throughout commercialization of this process, BNL has provided Envirocare with technical support for engineering and permitting.

Lageraaen, P.R.; Kalb, P.D. [Brookhaven National Lab., Upton, NY (United States); Hellstrom, G.W.; Vance, J.K. [Envirocare of Utah, Inc., Salt Lake City, UT (United States)

1998-01-01

140

Correction of late enophthalmos with polyethylene implant.  

PubMed

High density porous polyethylene (HDPP) has been used extensively for craniofacial reconstructive procedures. The authors recently reviewed the records of 21 patients who had undergone correction of late (more than 6 months) posttraumatic enophthalmos utilizing HDPP implants to restore orbital integrity and volume. Follow-up after implant placement was 6 months to 54 months (mean 20 months). Twenty of 21 patients demonstrated a clinically significant reduction in enophthalmos to within 2 mm of the opposite globe, as demonstrated by Hertel and/or Naugle exophthalmometry and by clinical observation. There were no cases of worsened visual acuity, lid position or ocular mobility, and no HDPP implant became infected or was extruded. The authors' experience supports the safety and efficacy of HDPP implants for correction of mild to moderate posttraumatic enophthalmos. PMID:11951479

Karesh, J W; Horswell, B B

1996-01-01

141

Modification of polyethylene terephthalate by proton irradiation  

NASA Astrophysics Data System (ADS)

Polyethylene terephthalate (PET) films were irradiated with 3 MeV proton beams at different fluences. The microhardness, electrical, thermal and structural studies were carried out using microhardness tester, LCR meter, thermogravimetric analysis (TGA) and FTIR spectroscopy. Vickers' hardness has been observed to increase with the fluence. The true bulk hardness of the film was obtained at loads greater than 400 mN. The AC electrical conductivity is practically unaffected by irradiation up to a frequency of 10 kHz, but it is found to increase exponentially at a frequency of 300 kHz. The loss factor and dielectric constant are observed to change appreciably with the fluence. It is observed that there is no significant change in the stability of the polymer up to the fluence of 1014 ions cm(-2) as revealed by TGA and FTIR spectroscopy.

Singh, N. L.; Shah, N.; Desai, C. F.; Singh, K. P.; Arora, S. K.

2004-08-01

142

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

143

Immobilization of silver nanoparticles on polyethylene terephthalate  

NASA Astrophysics Data System (ADS)

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.

Reznickova, Alena; Novotna, Zdenka; Kolska, Zdenka; Svorcik, Vaclav

2014-06-01

144

Micropallet arrays with poly(ethylene glycol) walls†‡  

PubMed Central

Arrays of releasable micropallets with surrounding walls of poly(ethylene glycol) (PEG) were fabricated for the patterning and sorting of adherent cells. PEG walls were fabricated between the SU-8 pallets using a simple, mask-free strategy. By utilizing the difference in UV-transmittance of glass and SU-8, PEG monomer was selectively photopolymerized in the space surrounding the pallets. Since the PEG walls are composed of a cross-linked structure, the stability of the walls is independent of the pallet array geometry and the properties of the overlying solution. Even though surrounded with PEG walls, the individual pallets were detached from the array by the mechanical force generated by a focused laser pulse, with a release threshold of 6 ?J. Since the PEG hydrogels are repellent to protein adsorption and cell attachment, the walls localized cell growth to the pallet top surface. Cells grown in the microwells formed by the PEG walls were released by detaching the underlying pallet. The released cells/pallets were collected, cultured and clonally expanded. The micropallet arrays with PEG walls provide a platform for performing single cell analysis and sorting on chip. PMID:18432343

Wang, Yuli; Salazar, Georgina To'a; Pai, Jeng-Hao; Shadpour, Hamed; Sims, Christopher E.; Allbritton, Nancy L.

2008-01-01

145

Luminescence in crosslinked polyethylene at elevated temperatures  

NASA Astrophysics Data System (ADS)

Electrical treeing is often responsible for the breakdown of insulating materials used in power apparatus such as high-voltage transformers, cables, and capacitors. Insulation, such as crosslinked polyethylene (XLPE), used in underground high-voltage cables usually operates at temperatures above ambient. This paper describes the characteristics of luminescence, emitted prior to electrical tree inception, at a crosslinked polyethylene-semiconducting material (XLPE-semicon) interface held above room temperature. Use of a sensitive light detection system showed that XLPE subjected to elevated temperatures emits luminescence even without voltage application. This light was attributed to thermoluminescence which decreased with the decrease in the concentration of the crosslinking by-products present in the polymer. The spectra of thermoluminescence were only in the visible range. On the other hand, electroluminescence occurred when the XLPE-semicon interface was held above room temperature and subjected to high electric stress. This light did not depend on the concentration of the crosslinking by-products and the spectra of electroluminescence were in the visible and the ultraviolet ranges. It is proposed that XLPE-semicon interface held at elevated temperature and subjected to long-term voltage application initially emits both thermoluminescence and electroluminescence. As the crosslinking by-products exude out of the polymer, thermoluminescence decreases with time and ultimately ceases, but electroluminescence occurs as long as the voltage is applied to the polymer. Although the intensity of electroluminescence emitted at high temperature was lower than that emitted at ambient, sufficient ultraviolet radiation was emitted. The ultraviolet radiation could photodegrade the polymer and lead to electrical tree inception.

Bamji, S. S.; Bulinski, A. T.; Suzuki, H.; Matsuki, M.; Iwata, Z.

1993-10-01

146

Myocardial matrix-polyethylene glycol hybrid hydrogels for tissue engineering.  

PubMed

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. PMID:24334615

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

2014-01-10

147

Purification of antibodies by precipitating impurities using Polyethylene Glycol to enable a two chromatography step process.  

PubMed

The purification of antibodies by precipitating impurities using Polyethylene Glycol (PEG) was assessed with the objective of developing a two chromatography column purification process. A PEG precipitation method was evaluated for use in the industrial purification of recombinant monoclonal antibodies (MAbs). Effective and robust precipitation conditions including PEG concentration, pH, temperature, time, and protein concentration were identified for several different MAbs. A recovery process using two chromatography steps in combination with PEG precipitation gave acceptable yield and purity levels for IgG1 and IgG4 antibodies with a broad range of isoelectric points (pI). PEG precipitation removed host cell proteins (HCPs), high molecular weight species (HMWS), leached Protein A ligand, and host cell DNA to acceptable levels when run under appropriate conditions, and some endogenous virus removal was achieved. PMID:24036248

Giese, Glen; Myrold, Adam; Gorrell, Jeffrey; Persson, Josefine

2013-11-01

148

Quantitation of Employee Exposure to Emission Products Generated by Commercial-Scale Processing of Polyethylene  

Microsoft Academic Search

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

Tony Tikuisis; Michael R. Phibbs; Kenneth L. Sonnenberg

1995-01-01

149

Self-assembly of silanated poly(ethylene glycol) on silicon and glass surfaces for improved haemocompatibility  

Microsoft Academic Search

Surface immobilization of poly(ethylene glycol) (PEG) is an effective method to produce a material surface with protein repulsive property. This property could be made permanent by using covalent grafting of the PEG molecules onto material surfaces. In this study, self-assembled monolayers (SAMs) of PEG on silicon-containing materials (silicon chip and glassplate) were obtained through a one-step coating procedure of one

Zhang Guo; Sheng Meng; Wei Zhong; Qiangguo Du; Laisheng L. Chou

2009-01-01

150

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....

151

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

152

Dewatering of Mineral Waste Using the Flocculant Polyethylene Oxide.  

National Technical Information Service (NTIS)

The bulletin summarizes the results of Bureau of Mines investigations of a technique for dewatering clay waste that consists of flocculation with polyethylene oxide (PEO) followed by screening of the resulting flocs. Results of laboratory tests and small-...

B. J. Scheiner, A. G. Smelley, D. A. Stanley

1985-01-01

153

Creep behavior of 6 micrometer linear low density polyethylene film  

NASA Technical Reports Server (NTRS)

Creep tests were performed to provide material characteristics for a 6.4-micron polyethylene film used to construct high altitude balloons. Results suggest simple power law relationships are adequate for stresses below about 4.83 MPa.

Simpson, J. M.; Schur, W. W.

1993-01-01

154

Biodegradation of disposable polyethylene by fungi and Streptomyces species  

Microsoft Academic Search

The ability of fungi and Streptomyces species to attack degradable plastics was investigated in pure shake-flask culture studies. The degradable plastic used in this study was disposable polyethylene bags containing 6% starch. Eight different isolated Streptomyces strains and two fungi Mucor rouxii NRRL 1835 and Aspergillus flavus were used. Ten-day heat-treated (70°C) polyethylene films were chemically disinfected and incubated shaken

Hanaa A El-Shafei; Nadia H Abd El-Nasser; Amany L Kansoh; Amal M Ali

1998-01-01

155

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

Microsoft Academic Search

Mechanical tests following gamma inrradiation and creep tests during irradiation have been conducted on high-density polyethylene (HDPE) to assess the adequacy of this material for use in high-integrity containers (HICs). These tests were motivated by experience in nuclear power plants in which polyethylene electrical insulation detoriorated more rapidly than expected due to radiation-induced oxidation. This suggested that HDPE HICs used

D. R. Dougherty; J. W. Adams

1983-01-01

156

Simple EOS for branched (low-density) polyethylene  

SciTech Connect

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

Dowell, F.

1982-10-01

157

Simple EOS for branched (low-density) polyethylene  

Microsoft Academic Search

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

Dowell

1982-01-01

158

Multicomponent analysis of low-density polyethylene oxidative degradation  

Microsoft Academic Search

The oxidative degradation of polyethylene in various conditions has been studied. In order to gain insight into the oxidation process, a method for the curve-fitting analysis of the IR carbonyl band between 1800cm?1 and 1600cm?1 in oxidized low-density polyethylene (LDPE) has been developed. Up to 10 components were needed to fit the band envelope, whose assignments and peak positions were

Mario Salvalaggio; Roberto Bagatin; Marco Fornaroli; Sergio Fanutti; Stefano Palmery; Ezio Battistel

2006-01-01

159

The thermal neutron diffusion cooling coefficient in polyethylene  

Microsoft Academic Search

The diffusion cooling coefficient C for thermal neutrons in polyethylene at 20°C has been determined theoretically. Granada's Synthetic Model of the scattering law has been applied to describe the interaction of neutrons with polyethylene. Two approximations of the neutron energy distribution in finite homogeneous systems have been used. The result of the calculation using a rough approximation is CB=2160cm4s?1. According

K. Drozdowi; V. H. Gillette

1999-01-01

160

Rotational molding of pultruded profiles reinforced polyethylene  

NASA Astrophysics Data System (ADS)

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

Greco, Antonio; Maffezzoli, Alfonso; Romano, Giorgio

2014-05-01

161

Organocatalytic decomposition of polyethylene terephthalate using triazabicyclodecene  

NASA Astrophysics Data System (ADS)

This study focuses on the organocatalytic decomposition of polyethylene terephthalate (PET) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) to form a diverse library of aromatic amides. The reaction scheme was specifically designed to use low reaction temperatures (>150°C) and avoid using solvents during the reaction to provide a more environmentally friendly process. Of all the amines tested, PET aminolysis with aliphatic and aromatic amines demonstrated the best performance with yields higher than 72%. PET aminolysis with click functionalized and non-symmetric reagents facilitated attack on certain sites on the basis of reactivity. Finally, the performance of the PET degradation reactions with secondary amine and tertiary amine functionalized reagents yielded mixed results due to complications with isolating the product from the crude solution. Four of the PET-based monomers were also selected as modifiers for epoxy hardening to demonstrate the ability to convert waste into monomers for high-value applications. The glass transition temperatures, obtained using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) of the epoxy composite samples treated with the PET-based monomers, were generally higher in comparison to the samples cured with the basic diamines due to the hydrogen bonding and added rigidity from the aromatic amide group. Developing these monomers provides a green and commercially viable alternative to eradicating a waste product that is becoming an environmental concern.

Lecuyer, Julien Matsumoto

162

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

163

Acetaldehyde residue in polyethylene terephthalate (PET) bottles.  

PubMed

A simple sample preparation technique was developed for rapid analysis of acetaldehyde residue in Polyethylene Terephthalate (PET) bottles. A laboratory-built heating system was used and coupled with gas chromatography-flame ionization detector (GC-FID) at optimized conditions. The results were a tremendous reduction of the sample preparation time from 24 hours, for the conventional method, to only one hour. The analysis took only 1.5 min with other good analytical performances i.e. a low detection limit, 0.3 ng mL(- 1) and a wide linear dynamic range, 0.3 ng mL(- 1) to 6.6 microg mL(- 1) with R(2) > 0.99. Acetaldehyde residue in freshly blown bottles were analyzed and found in the range of 0.4 to 1.1 ng mL(- 1). The results were good agreement with the conventional 24-hour airspace method (P < 0.01). The PET-bottle sampling technique was also developed to minimize the complication of sample transportation and pre-concentration. A purge and trap technique was found to be the most suitable. Then, it was implemented and compared, the results showed no significant difference (P < 0.01) with and without purge and trap. PMID:17562466

Choodum, Aree; Thavarungkul, Panote; Kanatharana, Proespichaya

2007-01-01

164

[Innovative materials in orthopaedics: the crosslinked polyethylene (XPE)].  

PubMed

More than 150.000 hip and knee arthroplasties are performed every year in Italy. More than 50% of the patients receive a polyethylene component (Ultra High Molecular Weight PolyEthylene, UHMWPE). Polyethylene abrasive wear induces over time in vivo a foreign-body response and consequently osteolysis, pain and need of implant revision. Furthermore, oxidative wear due to gamma-rays sterilization caused in the '90ies several and severe failures. To solve these problems, since then, the orthopaedics research has been addressed to: 1) develop new cross linked polyethylene with a higher molecular mass than UHMWPE and, consequently, a higher abrasive wear resistance; 2) avoid the oxidative wear induced by gamma-rays sterilization, by using other sterilization methods and by stabilizing UHMWPE by means of antioxidants such as Vitamin E. According to the most recent studies, performed on limited cohorts and mostly funded by manufacturers, cross linked polyethylene shows a better abrasive wear resistance if compared to the conventional polyethylene but no significant differences have been detected in the clinical outcomes. Clinical follow up of Vitamin E stabilized PE are not yet available. The organization of national arthroplasties registries, able to trace and characterize the implanted devices and based on the whole patients population, will facilitate the early detection of devices that show a performance inferior than the expected one. In Italy, the National Institute of Health has been entrusted by the Ministry of Health to organize the national arthroplasty registry. PMID:21736010

Torre, M; del Prever, E Brach; Costa, L; Romanini, E; Masciocchi, M; Manno, V

2011-01-01

165

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

166

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

167

Effect of amine functionalized polyethylene on clay-silver dispersion for polyethylene nanocomposites  

NASA Astrophysics Data System (ADS)

The compatibilization provided by maleic anhydride (MA) and 2-[2-(dimethylamino)-ethoxy] ethanol (DMAE) functionalized polyethylene for forming polyethylene-based nanocomposites was studied and compared. MA was grafted into PE by melt mixing to obtain PEgMA (compatibilizer 1), thereafter, PEgMA was reacted with DMAE and an antioxidant also by melt mixing to obtain PAgDMAE (compatibilizer 2). These compatibilizers were reacted using ultrasound with a solution of AgNO3 0.04 M and Ethylene glycol. Ammonium hydroxide was added in a ratio of 2:1 molar with respect to silver nitrate. These silver coated compatibilizers were mixed with PE and nano-clay (Cloisite I28E), thus forming the different hybrid PE-clay-silver nanocomposites. FTIR confirmed the formation of these two compatibilizers. All the compatibilized nanocomposites had better filler (clay and silver) dispersion and exfoliation compared to the uncompatibilized PE nanocomposites. X-ray diffraction, mechanical and antimicrobial properties attained showed that the PEgDMAE produced the better dispersed PE, clay and silver nanocomposites. The obtained nanocomposites showed outstanding antimicrobial properties against bacteria, Escherichia coli and fungus, Aspergillus niger. It is concluded that the PEgDMAE offers an outstanding capability for preparing nanocomposites with highly exfoliated and dispersed filler into the PE matrix.

Sánchez-Valdes, S.; Ibarra-A, M. C.; Ramírez-V, E.; Ramos-V, L. F.; Martinez-C, J. G.; Romero-G, J.; Ledezma-P, A. S.; Rodriguez-F, O. S.

2014-08-01

168

Fibrovascularization and osteogenesis in high-density porous polyethylene implants.  

PubMed

High-density porous polyethylene (HDPP) has been extensively used in craniofacial reconstructions with high-level success and minimal complications. It is known for its biocompatibility and satisfactory stability in the receptor bone area, presenting only a few reports of mobility and infection. In the current study, attention was given to the interface area between HDPP and bone surface to analyze fibrous and bone tissue formation and ingrowth into the pores of the material placed in the mandible of rabbits. Twelve male New Zealand rabbits underwent surgical procedure to receive bilateral HDPP implants in buccal face of dentate mandibular alveolar process, fixed with titanium screws. After 7, 14, 45, and 90 days, the animals were killed, and the specimens were retrieved for histologic and immunohistochemical analyses. No implant loss or infection was detected at the retrieval of the specimens. The microscopic analysis presented satisfactory integration of the material to the bone surface, with new bone formation from the receptor bed and inside the pores of the material, observed from the 15th day. After 90 days, remodeling bone and fibrous tissue was seen in the interface region. Among some of the pores, mature lamellar bone was present. Immunohistochemistry pointed out a moderate expression either to Core binding factor protein 1/RUNX2 or to vascular endothelial growth factor for early periods evaluated, that is, 7 and 15 days after surgery. These results confirm the osteoconductive behavior and high biocompatibility of the material, associated to its adequate immobilization, leading to its lifelong presence in human biologic system. PMID:19553849

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

2009-07-01

169

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

PubMed

Hydroxyapatite (HA) reinforced high density polyethylene (HDPE) was invented as a biomaterial for skeletal applications. In this investigation, tribological properties (e.g. wear rate and coefficient of friction) of unfilled HDPE and HA/HDPE composites were evaluated against the duplex stainless steel in dry and lubricated conditions, with distilled water or aqueous solutions of proteins (egg albumen or glucose) being lubricants. Wear tests were conducted in a custom-built test rig for HDPE and HA/HDPE containing up to 40 vol % of HA. It was found that HA/HDPE composites had lower coefficients of friction than unfilled HDPE under certain conditions. HA/HDPE also exhibited less severe fatigue failure marks than HDPE. The degradation and fatigue failure of HDPE due to the presence of proteins were severe for low speed wear testing (100 rpm) as compared to high speed wear testing (200 rpm). This was due possibly to the high shear rate at the contact which could remove any degraded film instantaneously at high sliding speed, while with a low sliding speed the build-up of a degraded layer of protein could occur. The degraded protein layer would stay at the contact for a longer time and mechanical activation would induce adverse reactions, weakening the surface layer of HDPE. Both egg albumen and glucose were found to be corrosive to steel and adversely reactive for HDPE and HA/HDPE composites. The wear modes observed were similar to that of ultra-high molecular weight polyethylene. Specimens tested with egg albumen also displayed higher wear rates, which was again attributed to corrosion accelerated wear. PMID:15348592

Wang, M; Chandrasekaran, M; Bonfield, W

2002-06-01

170

Polyethylene Oxidation in Total Hip Arthroplasty: Evolution and New Advances  

PubMed Central

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

Gomez-Barrena, Enrique; Medel, Francisco; Puertolas, Jose Antonio

2009-01-01

171

Radiation Transport Properties of Polyethylene-Fiber Composites  

NASA Technical Reports Server (NTRS)

Composite materials that can both serve as 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 piece 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 NASA's Marshall Space Flight Center and tested against 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, Raj K.; Barghouty, A. F.; Dahche, H. M.

2003-01-01

172

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

173

Comparison of polyethylene wear in anatomical and reversed shoulder prostheses.  

PubMed

Wear of polyethylene is associated with aseptic loosening of orthopaedic implants and has been observed in hip and knee prostheses and anatomical implants for the shoulder. The reversed shoulder prostheses have not been assessed as yet. We investigated the volumetric polyethylene wear of the reversed and anatomical Aequalis shoulder prostheses using a mathematical musculoskeletal model. Movement and joint stability were achieved by EMG-controlled activation of the muscles. A non-constant wear factor was considered. Simulated activities of daily living were estimated from in vivo recorded data. After one year of use, the volumetric wear was 8.4 mm(3) for the anatomical prosthesis, but 44.6 mm(3) for the reversed version. For the anatomical prosthesis the predictions for contact pressure and wear were consistent with biomechanical and clinical data. The abrasive wear of the polyethylene in reversed prostheses should not be underestimated, and further analysis, both experimental and clinical, is required. PMID:19567867

Terrier, A; Merlini, F; Pioletti, D P; Farron, A

2009-07-01

174

Molecular Weight Dependence of the Viscosity of Polyethylene Macrocycles  

NASA Astrophysics Data System (ADS)

The Grubbs group at Caltech is using a new method of synthesis for the production of macrocycles that avoids the problems of sample contamination with long chain linear molecules. They have produced macrocyclic polyethylenes having molecular weights as high as 400,000 g/mole. At Texas Tech University rheological measurements are being made using both the Plazek Magnetic Bearing Torsional Creep Apparatus and a Paar Physica controlled stress rheometer. Because the samples are polydisperse, with Mw/Mn values of 1.6-1-9, we here report only the results of the viscosity as a function of molecular weight. Surprisingly, unlike reports in the literature for polystyrene rings or polybutadiene rings, the viscosities of the polyethylene rings are larger than those for equivalent molecular weight linear polyethylenes and the viscosity increases approximately exponentially with weight average molecular weight. Further results will be reported at the meeting.

Wang, Jian; McKenna, Gregory; Benitez, Diego; Gorodetskaya, Irina; Grubbs, Robert

2005-03-01

175

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Notice of...antidumping duty order on polyethylene retail carrier bags (PRCBs) from Thailand...Ltd., v. United States, Polyethylene Retail Carrier Bag Committee, Hilex Poly...

2013-12-03

176

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-549-821] Polyethylene Retail Carrier Bags From Thailand: Final Court...weighted-average duty margin for polyethylene retail carrier bags (PRCBs) from Thailand produced...2\\ See Polyethylene Retail Carrier Bags from Thailand: Final...

2013-11-21

177

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-560-822] Polyethylene Retail Carrier Bags From Indonesia: Final Determination...determined that imports of polyethylene retail carrier bags (PRCBs) from Indonesia...the Department published Polyethylene Retail Carrier Bags from Indonesia:...

2010-04-01

178

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

Federal Register 2010, 2011, 2012, 2013

...Administration [A-583-843] Polyethylene Retail Carrier Bags from Taiwan: Final Determination...determined that imports of polyethylene retail carrier bags (PRCBs) from Taiwan are...of PRCBs from Taiwan. See Polyethylene Retail Carrier Bags From Taiwan:...

2010-03-26

179

77 FR 13387 - Pipeline Safety: Notice to Operators of Driscopipe® 8000 High Density Polyethylene Pipe of the...  

Federal Register 2010, 2011, 2012, 2013

...Operators of Driscopipe[supreg] 8000 High Density Polyethylene Pipe of the Potential for...using Driscopipe[supreg] 8000 High Density Polyethylene Pipe (Drisco8000) of the...using Driscopipe[supreg] 8000 High Density Polyethylene Pipe. Subject:...

2012-03-06

180

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

181

Effect of dose on creep and recovery of polyethylene  

NASA Astrophysics Data System (ADS)

The effect of high energy radiation on polyethylene is to crosslink it, and connect it into an elastic network above the melting point. In this paper the creep and recovery properties of a stabilized polyethylene subjected to doses from 100 to 870 kGy are measured at 150°C. Two cycles are measured— Creep I + Recovery I, and Creep II + Recovery II—mainly over periods of 20 min. The creep or recovery behaviour falls into three steps—immediate, fast and slow, and data are given for these steps together with the time parameter. The first cycle includes a non-recoverable creep which is almost absent in the second cycle.

Novakovi?, Lj.; Gal, O.; Charlesby, A.; Stannett, V. T.

182

Molecular order, miscibility, and rheology of molten polyethylenes  

NASA Astrophysics Data System (ADS)

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

Hussein, Ibnelwaleed Ali

183

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

184

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.

185

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

186

Design of biodegradable particles for protein delivery  

Microsoft Academic Search

Major research issues in protein delivery include the stabilization of proteins in delivery devices and the design of appropriate protein carriers in order to overcome mucosal barriers. We have attempted to combine both issues through the conception of new biodegradable polymer nanoparticles: (i) poly(ethylene glycol) (PEG)-coated poly(lactic acid) (PLA) nanoparticles, chitosan (CS)-coated poly(lactic acid–glycolic acid (PLGA) nanoparticles and chitosan (CS)

A. Vila; A. Sánchez; M. Tob??o; P. Calvo; M. J. Alonso

2002-01-01

187

Hydrophilic polysulfone film prepared from polyethylene glycol monomethylether via coupling graft  

NASA Astrophysics Data System (ADS)

In the presence of acid-acceptor Na2CO3, the nucleophilic substitution between chloromethylated polysulfone (CMPSF) and polyethylene glycol monomethylether (PEGME) was conducted. Polyethylene glycol (PEG) was coupling-grafted onto the side chains of polysulfone (PSF) so that the graft copolymer PSF-g-PEG was prepared and the hydrophilic modification of polysulfone membrane material was realized. The chemical structure of PSF-g-PEG was characterized by FTIR and 1H NMR. The influence of the main factors on the coupling graft reaction was investigated. The water static contact angle of PSF-g-PEG membrane was determined and its property of resisting protein pollution was examined by using bovine serum albumin (BSA) as a model protein. The experimental results show that the coupling graft reaction between CMPSF and PEGME can proceed successfully, and the reaction of chloromethyl groups of CMPSF with the hydroxyl end groups of PEGME is a typical SN1 nucleophilic substitution reaction. The polarity of the solvents and the reaction temperature greatly influence the reaction. The suitable solvent is dimethyl acetamide with stronger polarity and 70 °C is a suitable reaction temperature. After reaction of 36 h, the grafting degree of PEG can reach 48 g/100 g and the product yield is about 73.6%. The contact angle of PSF-g-PEG membrane declines rapidly with the increase of PEG grafting degree, displaying the obvious enhancement of the hydrophilicity. The adsorption capacity of BSA on PSF-g-PEG membrane decreases remarkably with the increase of PEG grafting degree, showing excellent antifouling ability of PSF-g-PEG membrane for proteins.

Du, Ruikui; Gao, Baojiao; Li, Yanbin

2013-06-01

188

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

E-print Network

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

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

2014-01-01

189

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

190

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

Federal Register 2010, 2011, 2012, 2013

...A-557-813, A-549-821] Polyethylene Retail Carrier Bags From the People's Republic...antidumping duty orders on polyethylene retail carrier bags (PRCBs) from the People's...July 1, 2009); see also Polyethylene Retail Carrier Bags From China, Malaysia,...

2010-07-07

191

78 FR 76567 - Tall Oil, Polymer With Polyethylene Glycol and Succinic Anhydride Monopolyisobutylene Derivs...  

Federal Register 2010, 2011, 2012, 2013

...EPA-HQ-OPP-2013-0525; FRL-9903-19] Tall Oil, Polymer With Polyethylene Glycol and Succinic...a tolerance for residues of tall oil, polymer with polyethylene glycol and succinic...permissible level for residues of tall oil, polymer with polyethylene glycol and...

2013-12-18

192

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

Code of Federal Regulations, 2013 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...

2013-04-01

193

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

... 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...

2014-04-01

194

21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).  

Code of Federal Regulations, 2012 CFR

... Polyethylene glycol (mean molecular weight 200-9,500). 172.820 Section... Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol...ethylene oxide and water with a mean molecular weight of 200 to 9,500. (2) It...

2012-04-01

195

21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).  

Code of Federal Regulations, 2013 CFR

... Polyethylene glycol (mean molecular weight 200-9,500). 172.820 Section... Polyethylene glycol (mean molecular weight 200-9,500). Polyethylene glycol...ethylene oxide and water with a mean molecular weight of 200 to 9,500. (2) It...

2013-04-01

196

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

Code of Federal Regulations, 2012 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...

2012-04-01

197

THE PHYSICAL AND THERMAL PROPERTIES OF MODIFIED ROTATIONAL MOLDING GRADE SILANE CROSS-LINKED POLYETHYLENE COMPOUND  

Microsoft Academic Search

This study is aimed at investigating the physical and thermal properties of the modified rotational molding grade cross-linked polyethylene compound with respect to process ability..... Rotational molding grade High Density Polyethylene (HDPE) was blended at various compositions with HDPE and Low Density Polyethylene (LDPE) using twin screw extruder. The melt index of the blends was studied according to ASTM D

WAN AIZAN; WAN ABDUL RAHMAN; CHEN CHAN HOONG; AHMAD FAREED

198

High-Molecular-Weight Polyethylene Glycol Prevents Lethal Sepsis Due to Intestinal Pseudomonas aeruginosa  

E-print Network

High-Molecular-Weight Polyethylene Glycol Prevents Lethal Sepsis Due to Intestinal Pseudomonas: During stress, erosion of protective intestinal mucus occurs in association with adherence of this study were to test the ability of a high-molecular- weight polyethylene glycol compound, polyethylene

Lee, Ka Yee C.

199

Adsorption of Polypropylene and Polyethylene on Liquid Chromatographic  

E-print Network

prepared in recent times [2­4], effi- cient separation methods for such mate- rials do not exist by the experimental work of Denayer et al. [15], we have recently found a strong retention of polyethylene with molar to the zeolite is sup- posed to be the primary reason for its strong retention. Zeolites are crystalline

Li, Jing

200

Radiographic analysis of polyethylene glenoid components using modern cementing techniques  

Microsoft Academic Search

The purpose of this study was to examine the initial radiographic appearance and changes occurring over time in patients who have undergone total shoulder arthroplasty by modern methods of bone preparation and current cement techniques. Sixty-five patients underwent seventy total shoulder arthroplasties by use of a cemented all-polyethylene, keeled glenoid component. The surface radius was equal to the radius of

Joseph Mileti; N. Douglas Boardman; John W. Sperling; Robert H. Cofield; Michael E. Torchia; Shawn W. O'Driscoll; Charles M. Rowland

2004-01-01

201

Polyethylene/clay nanocomposites prepared by polymerization compounding method.  

PubMed

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

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

2006-02-01

202

Nucleation and anisotropic crystalline growth of polyethylene under shear  

Microsoft Academic Search

The crystallization of polyethylene was observed during shear experiments in isothermal conditions. The nucleation and the crystalline growth rates were measured from a microscopic observation of the growing morphologies. An unusual formation and development of row nuclei was observed throughout the experiment, followed by anisotropic growth. Three main growth rates were measured with respect to the main directions of the

B. Monasse; Ecole Nationale

1995-01-01

203

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

204

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

Microsoft Academic Search

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

Dowell

1982-01-01

205

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

SciTech Connect

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

Dowell, F

1982-11-01

206

Analysis of functionalized polyethylene terephthalate with immobilized NTPDase and cysteine  

Microsoft Academic Search

Polyethylene terephthalate (PET) was functionalized to introduce carboxyl groups onto its surface by a carboxylation technique. Surface and bulk properties, such as possible surface deterioration, surface roughness and the mechanical strength of the carboxylated polymers, were studied and compared with those of aminolyzed and hydrolyzed PET. Atomic force microscopy studies showed that unlike aminolysis and hydrolysis, which increased the surface

Vignesh Muthuvijayan; Jun Gu; Randy S. Lewis

2009-01-01

207

Preservation of Old, Waterlogged Wood by Treatment with Polyethylene Glycol.  

PubMed

The excessive cracking and distortion that old waterlogged wood undergoes when it is dried can be substantially reduced by treating the wood with polyethylene glycol. The process was used to dry 200-year-old waterlogged wood boats recently raised from Lake George, New York. PMID:17814507

Seborg, R M; Inverarity, R B

1962-05-18

208

A polyethylene-reinforced polymer composite abraded by bulk solids  

Microsoft Academic Search

The abrasive wear characteristics of polymer matrix composite materials reinforced with particles of ultra-high molecular weight polyethylene (UHMWPE) have been investigated. Granular ignimbrite (a hard mineral) was used as the abrasive. The effect of varying the volume fraction of UHMWPE reinforcement upon wear rate has been measured and scanning electron microscopy (SEM) used to study the wear mechanisms that operate.

A. A. Cenna; S. Allen; N. W. Page; P. Dastoor

2001-01-01

209

Solvation of ion pairs with poly(ethylene oxide)  

Microsoft Academic Search

Solvation of ion pairs of the alcoxide type with poly(ethylene oxide) (PEO) has been studied by optical spectroscopy. Values of binding constants 200–400 l\\/mol indicate a sufficiently effective ion-pair cation solvation. Being cross-linked PEO preserves its ability to bind and localize ion pairs.

Go N. Arkhipovich; Ye. A. Ugolkova; K. S. Kazanskii

1984-01-01

210

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...

211

Thermal degradation and catalytic cracking of poly(ethylene terephthalate)  

Microsoft Academic Search

The percentage weight loss of poly(ethylene terephthalate) (PET) by thermal degradation and catalytic cracking reactions was investigated at atmospheric pressure. The extent of PET thermal degradation was little affected by the particle size, but tremendously affected by temperature between 400 and 500°C. In PET catalytic cracking reactions, copper (II) chloride was the most active among tested catalysts. It reduced the

S. J. Chiu; W. H. Cheng

1999-01-01

212

Research Report Polyethylene glycol inhibits apoptotic cell death following  

E-print Network

Oxidative stress Cytochrome c Membrane repair Apoptosis 1. Introduction We have reported that polyethylene in guinea pig spinal cord repairs neuronal membrane disruptions and reduces oxidative injury. Here we report the release of cytochrome c, a pro-apoptotic cell death factor. This hypothesis is further supported by our

Shi, Riyi

213

Oscillatory carbonylation using alkyne-functionalised poly(ethylene glycol).  

PubMed

In this study palladium-catalysed oscillatory carbonylation has been achieved using mono alkyne-terminated poly(ethylene glycol) methyl ether substrates. Reproducible, synchronised oscillations in pH and solution turbidity have been recorded over several days. A reaction network accounting for the observed phenomena has been proposed. PMID:24957532

Donlon, Lynn; Novakovic, Katarina

2014-12-21

214

Polyethylene sponge total ossicular replacement prosthesis. A histopathologic study.  

PubMed

The histopathologic findings of a functioning high-density polyethylene sponge (Plastipore) total ossicular replacement prosthesis in a patient who died of unrelated causes are reported herein. The lack of inflammatory cell infiltration of foreign-body giant cells within, or adjacent to, the prosthesis helps substantiate the safety and efficacy of Plastipore in the reconstruction of the ossicular chain. PMID:7150073

Postma, D; Shea, J J

1982-12-01

215

Occupational asthma due to polyethylene shrink wrapping (paper wrapper's asthma).  

PubMed Central

Occupational asthma due to the pyrolysis products of polyvinyl chloride (PVC) produced by shrink wrapping processes has previously been reported. The first case of occupational asthma in a shrink wrap worker using a different plastic, polyethylene, is reported; the association was confirmed by specific bronchial provocation testing. PMID:1440477

Gannon, P F; Burge, P S; Benfield, G F

1992-01-01

216

Characteristics of polyethylene-moderated 252Cf neutron sources  

NASA Astrophysics Data System (ADS)

Polyethylene-moderated 252Cf neutron sources were designed to produce neutron reference fields' spectra that simulate the spectra observed in the workplaces within nuclear reactors and accelerators. The paper describes the neutron sources and fields. Neutron spectra were calculated by the Monte Carlo method and compared with experimental data.

Aleinikov, V. E.; Beskrovnaja, L. G.; Florko, B. V.

2002-01-01

217

Detection of Joule heating before dielectric breakdown in polyethylene films  

Microsoft Academic Search

Local Joule heating in polyethylene films was detected at room temperature before dielectric breakdown under DC field. When a high-temperature point appeared in a film, the conduction current increased with time. The final breakdown occurred at the point of the highest temperature. This concurrence of the breakdown point and the Joule heating point suggests that a thermal process takes part

Masayuki Nagao; Takashi Kimura; Y. Mizuno; M. Kosaki; M. Ieda

1990-01-01

218

Neutron sensitivity of a polyethylene-walled electret ionization chamber  

Microsoft Academic Search

The electret ionization chamber is an analogue of the common ionization chamber using permanently charged electrodes - electrets. The application of such electret dosimeters for detecting X and gamma radiation primarily in personnel monitoring has been established. In the present paper the neutron sensitivity of a polyethylene-walled electret ionization chamber with parallel plate geometry was determined experimentally and theoretically for

Gunter Pretzsch

1985-01-01

219

Polyethylene Foam Waste Utilization for Lightweight Concrete Production  

Microsoft Academic Search

The utilization of construction materials based on polymers is considerably limited by their low fire-safety and insignificant durability. In this paper the investigations results of construction on composite including up to 30% of the volume of foam polyethylene waste are discussed. Its destruction during the fire action and also utilization is limited by a cement concrete matrix which has a

A. Perevozchikov; G. Yakovlev; V. Kodolov

2000-01-01

220

SEPARATION OF PROTEINS BY ION EXCHANGE AND MEMBRANE CHROMATOGRAPHY: BUFFER COMPOSITION, INTERFERING IMPURITIES AND FOULING CONSIDERATIONS  

E-print Network

membranes with bovine serum albumin (BSA) and immunoglobulin G (IgG). Least fouling resulted with polyethylene glycol (PEG) membranes when BSA protein was used. Amine-functionalized membranes showed specific interaction with BSA. There was multi...

Imam, Tahmina

2010-01-16

221

Nanoscale morphologies of polystyrene and polyethylene ionomers  

NASA Astrophysics Data System (ADS)

Ionomers are highly valued for their unique properties and therefore have long been studied to characterize, understand, and improve these properties. Many studies have focused on the bulk properties of ionomers with more recent efforts using X-ray scattering to characterize the nanometer scale structure especially the ionic aggregate. Scanning transmission electron microscopy (STEM) technology has developed to the point within the past decade that direct imaging of the ionic aggregate is possible. In this dissertation, STEM techniques are refined by accounting for extensive overlap in the projected image and STEM techniques along with X-ray scattering methods are used to study a unique group of poly(ethylene-co-acrylic acid) (P(E-AA)) copolymers and ionomers. We examined poly(styrene-ran-7%-methacrylic acid) Cu (P(S-MAA0.07) Cu) ionomer with model dependant X-ray scattering and direct imaging through STEM. Using the liquid-like hard sphere X-ray scattering model proposed by Yarusso and Cooper with Fornet interference, the ionic aggregate number density indicate an extensively overlapped system for the STEM imaging. Thus, to properly interpret the STEM data, the extensive overlap must be corrected. By creating a computer model that is able to simulate STEM images from an X-ray model, the amount of overlap can be estimated and a proper number density can be calculated from the STEM images. The number density calculated from STEM agrees with the X-ray scattering. Also, despite the extensive overlap, the brightest, isolated features in the STEM are of the appropriate size and shape that would be expected from the projection of a single ionic aggregate. Therefore, the STEM and X-ray scattering are in agreement about the morphology of the ionic aggregates in these P(S-MAA0.07) Cu ionomers. These experiments are repeated for poly(styrene-ran-1.9%-sulfonated styrene) neutralized by Cu, Zn, Ba, or Cs and found that the liquid-like hard sphere X-ray model and the STEM agree on the size, shape, distribution, and number density of the ionic aggregates. We generalize our simulation method to projection of overlapping spheres. A procedure is developed to create and analyze large numbers of simulated projections through computer algorithms. To analyze the data set, it is plotted on axes chosen to reduce the number of variables that influenced the number of features counted in the simulated image (N2D) as a function of simulation thickness (t). The dependant axis is N2D normalized by the area of the simulation in units of 4 times the square of the sphere radius. The independent axis is simply the thickness in units of the sphere radius. With these axes, the important variable is the volume fraction of spheres (? R). In addition, there is a critical thickness, t c, where if t < tc, then the normalized N2D is proportional to talpha and if t > t c, the normalized N2D is independent of thickness at a value of beta. By knowing the thickness of the sample, the normalized N2D, the volume fraction can be estimated and thus the number of spheres in the volume can be calculated. Finally, we study the morphology of linear P(E-AA) copolymers with precisely-sequenced and irregularly sequenced acid groups to establish the effect that the acid group sequence has on the crystal structure. The linear irregularly-sequenced P(E-AA) copolymers behave similarly to low density poly(ethylene-acrylic acid) forming an orthorhombic polyethylene crystal structure and excluding the acid groups to the amorphous regions. The linear precisely-sequenced P(E-AA) copolymers exhibit an unique structure with the acids forming large planar layers that are incorporated into the crystal structure. The precisely-sequence linear P(E-AA) ionomers exhibit both the new acid layer structures and the traditional ionic aggregates. With increasing neutralization, the crystallinity of the P(E-AA) and the new acid layer structure decrease as the acid groups necessary are co-opted to form the ionic aggregates in the amorphous regions.

Chan, Christopher D.

222

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

223

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

PubMed Central

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

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

2012-01-01

224

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

225

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

PubMed

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

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

2012-10-01

226

Gamma Inert Sterilization: A Solution to Polyethylene Oxidation?  

PubMed Central

Background: In the 1990s, oxidation was found to occur in ultra-high molecular weight polyethylene total joint replacement components following gamma irradiation and prolonged shelf aging in air. Orthopaedic manufacturers developed barrier packaging to reduce oxidation during and after radiation sterilization. The present study explores the hypothesis that polyethylene components sterilized in a low-oxygen environment undergo similar in vivo oxidative mechanisms as inserts sterilized in air. In addition, the potential influence of the different sterilization processes on the wear performance of the polyethylene components was examined. Methods: An analysis of oxidation, wear, and surface damage was performed for forty-eight acetabular liners and 123 tibial inserts. The mean implantation time was 12.3 ± 3.7 years for thirty-one acetabular liners that had been gamma sterilized in air and 4.0 ± 2.5 years for the seventeen acetabular liners that had been gamma sterilized in inert gas. The mean implantation time was 11.0 ± 3.2 years for the twenty-six tibial inserts that had been sterilized in air and 2.8 ± 2.2 years for the ninety-seven tibial inserts that had been gamma sterilized in inert gas. Oxidation and hydroperoxide levels were characterized in loaded and unloaded regions of the inserts. Results: Measurable oxidation and oxidation potential were observed in all cohorts. The oxidation and hydroperoxide levels were regional. Surfaces with access to body fluids were more heavily oxidized than protected bearing surfaces were. This variation appeared to be greater in historical (gamma-in-air-sterilized) components. Regarding wear performance, historical and conventional acetabular liners showed similar wear penetration rates, whereas a low incidence of delamination was confirmed for the conventional tibial inserts in the first decade of implantation. Conclusions: The present study explores the impact of industry-wide changes in sterilization practices for polyethylene. We found lower oxidation and oxidation potential in the conventional acetabular liners and tibial inserts that had been gamma sterilized in inert gas as compared with the historical components that had been gamma sterilized in air. However, we also found strong evidence that conventional components undergo mechanisms of in vivo oxidation similar to those observed following gamma irradiation in air. In addition, gamma sterilization in inert gas did not provide polyethylene with a significant improvement in terms of wear resistance as compared with gamma sterilization in air, except for a lower incidence of delamination in the first decade of implantation for tibial inserts. Clinical Relevance: Our research demonstrates that gamma inert sterilization may have improved, but not completely solved, the problem of polyethylene oxidation for hip and knee arthroplasty. PMID:19339568

Medel, Francisco J.; Kurtz, Steven M.; Hozack, William J.; Parvizi, Javad; Purtill, James J.; Sharkey, Peter F.; MacDonald, Daniel; Kraay, Matthew J.; Goldberg, Victor; Rimnac, Clare M.

2009-01-01

227

Poly(ethylene oxide sulfide): New Poly(ethylene glycol) Derivatives Degradable in Reductive Conditions  

E-print Network

or gene delivery,1,2 the production of lithium polymer batteries,3 cell fusion,4 protein PEGylation,5 hy of the polymers is difficult because of their degradation in aqueous solution at a neutral pH. Moreover

Park, Jong-Sang

228

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

229

Polyethylene encapsulation full-scale technology demonstration. Final report  

SciTech Connect

A full-scale integrated technology demonstration of a polyethylene encapsulation process, sponsored by the US Department of Energy (DOE) Office of Technology Development (OTD), was conducted at the Environmental & Waste Technology Center at Brookhaven National Laboratory (BNL.) in September 1994. As part of the Polymer Solidification National Effort, polyethylene encapsulation has been developed and tested at BNL as an alternative solidification technology for improved, cost-effective treatment of low-level radioactive (LLW), hazardous and mixed wastes. A fully equipped production-scale system, capable of processing 900 kg/hr (2000 lb/hr), has been installed at BNL. The demonstration covered all facets of the integrated processing system including pre-treatment of aqueous wastes, precise feed metering, extrusion processing, on-line quality control monitoring, and process control.

Kalb, P.D.; Lageraaen, P.R.

1994-10-01

230

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

231

Strength of polyethylene, polypropylene and polystyrene behind a shock front  

SciTech Connect

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

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

2007-12-12

232

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

SciTech Connect

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

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

1983-01-01

233

DSC melting behavior of irradiated low density polyethylenes containing antioxidants  

NASA Astrophysics Data System (ADS)

The effect of antioxidants (0.5 wt% content) on the melting behaviour of low density polyethylenes, one branched and one linear, was examined with data obtained by DSC. The two polyethylenes exhibit noticeable differences in pure form; LLDPE has a higher melting point, lower heat of fusion and a more complex fusion endotherm than LDPE. The addition of antioxidants has a scarcely noticeable influence on the melting behaviour of LDPE whether irradiated or not, while in the case of LLDPE the effect is more visible. However, a careful analysis of the observed characteristics, peak temperatures and lamellae thickness distribution as well as heat of fusion, show that the observed effects are appearing as the consequence of chemical processes, scission and crosslinking, which occur in PE under either thermomechanical action (mixing in the course of the sample preparation), or radiation.

Gal, O.; Kostoski, D.; Babi?, D.; Stannett, V. T.

234

The Strength of Polyethylene and Polyoxymethylene Under Shock Loading  

NASA Astrophysics Data System (ADS)

In the past few years, a series of papers has examined the shock response of common engineering polymers in terms of their microstructure. In this latest work, the behaviours of two polymers, polyethylene and polyoxymethylene, are investigated under conditions of one-dimensional strain. The study focuses on the experimentally determined lateral component of stress and, from knowledge of the impact conditions, the shear strength. Variations with impact stress amplitude and pulse duration are discussed in terms of the polymer chain structure.

Goveas, S. G.; Bourne, N. K.; Millett, J. C. F.

2007-12-01

235

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

236

Post-irradiation effects in polyethylenes irradiated under various atmospheres  

NASA Astrophysics Data System (ADS)

If a large amount of polymer free radicals remain trapped after irradiation of polymers, the post-irradiation effects may result in a significant alteration of physical properties during long-term shelf storage and use. In the case of polyethylenes (PEs) some failures are attributed to the post-irradiation oxidative degradation initiated by the reaction of residual free radicals (mainly trapped in crystal phase) with oxygen. Oxidation products such as carbonyl groups act as deep traps and introduce changes in carrier mobility and significant deterioration in the PEs electrical insulating properties. The post-irradiation behaviour of three different PEs, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) was studied; previously, the post-irradiation behaviour of the PEs was investigated after the irradiation in air (Suljovrujic, 2010). In this paper, in order to investigate the influence of different irradiation media on the post-irradiation behaviour, the samples were irradiated in air and nitrogen gas, to an absorbed dose of 300 kGy. The annealing treatment of irradiated PEs, which can substantially reduce the concentration of free radicals, is used in this study, too. Dielectric relaxation behaviour is related to the difference in the initial structure of PEs (such as branching, crystallinity etc.), to the changes induced by irradiation in different media and to the post-irradiation changes induced by storage of the samples in air. Electron spin resonance (ESR), differential scanning calorimetry (DSC), infra-red (IR) spectroscopy and gel measurements were used to determine the changes in the free radical concentration, crystal fraction, oxidation and degree of network formation, respectively.

Suljovrujic, E.

2013-08-01

237

Aging of Polyethylene ADSS Sheath by Low Currents  

Microsoft Academic Search

The electrical environment of all-dielectric self-supporting cables on overhead power lines presents a challenge to cable materials. It is widely acknowledged that the application on lines of system voltages above 150 kV requires specialist sheath materials to prevent damage as a result of discharges on the cables' surfaces. It is widely held that below this system voltage, polyethylene sheaths are

Simon M. Rowland; Konstantinos Kopsidas; Xin Zhang

2010-01-01

238

Stable silver colloidal dispersions using short chain polyethylene glycol  

Microsoft Academic Search

Herein we report a ‘one pot’ facile method for environmentally benign production of stable Ag colloids, using short chain polyethylene glycol as solvent, reducing agent and stabilizer. Stable spherical metal particles 15–30nm in diameter with a well-crystallized structure were obtained at 30°C. Heating to 60°C resulted in increased spherical sizes, and heating over 90°C led to a mixture of shapes:

Monica Popa; Trinitat Pradell; Daniel Crespo; José M. Calderón-Moreno

2007-01-01

239

The Structural Dilemma of Bulk Polyethylene: An Intermediary Structure  

PubMed Central

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

Laridjani, Morteza; Leboucher, Pierre

2009-01-01

240

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

241

Simulated recycling of post-consumer high density polyethylene material  

Microsoft Academic Search

Post-consumer high density polyethylene (HDPE) was examined by a test procedure consisting of repeated cycles of alternating extrusion and subsequent accelerated thermo-oxidative ageing. The material studied was collected from a real waste stream of HDPE bottles. The effect of addition of a commercial re-stabiliser was also studied. The material was evaluated in terms of mechanical and chemical properties, such as

Antal Boldizar; Anna Jansson; Thomas Gevert; Kenneth Möller

2000-01-01

242

Characterization of Polyethylene Synthesized by Bi-Nickel Catalysts  

Microsoft Academic Search

New non-metallocene, bi-nickel center catalysts were prepared by Schiff base condensation of 2,3-butanedione with 2,6-di-isopropylaniline and subsequent metathesis reaction with (DME)NiBr2, and tested for ethylene polymerization reaction at different conditions. Catalyst productivities were found to be high, 45 × 10 kg\\/mmol Ni per h. The molecular weight of the product, i.e., polyethylene, varied from 4831 (a paste-like material) to 968

Fares D. Alsewailem; Ibrahim M. Al-Najjar

2010-01-01

243

Thermal and catalytic cracking of polyethylene under mild conditions  

Microsoft Academic Search

Thermal and catalytic cracking of both high and low-density polyethylene (HDPE and LDPE, respectively) under mild conditions have been investigated in order to study the properties of the solid waxy product so obtained. The catalysts employed were n-HZSM-5 and HY zeolites, amorphous silica–alumina, activated carbon, Pd charcoal powder and mesoporous aluminosilicate materials (MCM-41), with and without impregnated Pd. The best

R van Grieken; D. P Serrano; J Aguado; R Garc??a; C Rojo

2001-01-01

244

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

245

An assessment of athrombogenic properties of electret polyethylene film.  

PubMed

This paper shows the results of an investigation into the effect of an electric charge on blood platelet adhesion. All of the experiments were made on a polyethylene film. The electrets were formed using the electron beam method. The assessment of the electret effect on blood platelet adhesion was performed microscopically. It was found out that an electric charge plays a major role in the process of adhesion of blood morphological elements. PMID:9513254

Lowkis, B; Szymonowicz, M

1998-01-01

246

Void morphology in polyethylene/carbon black composites  

SciTech Connect

A combination of small angle neutron scattering (SANS) and contrast matching techniques is used to determine the size and quantity of voids incorporated during fabrication of polyethylene/carbon black composites. The analysis used to extract void morphology from SANS data is based on the three-phase model of microcrack determination via small angle x-rayscattering (SAXS) developed by W.Wu{sup 12} and applied to particulate reinforced composites.

Marr, D.W.M. [Colorado School of Mines, Golden, CO (United States). Chemical Engineering and Petroleum Refining Dept.; Wartenberg, M.; Schwartz, K.B. [Raychem Corp., Menlo Park, CA (United States)] [and others

1996-12-31

247

Polyethylene waste form: Evaluation of explosion and fire hazards  

SciTech Connect

A Proposed polyethylene waste form consists of a hot-extruded, non-porous mix of equal weights of polyethylene and granular sodium nitrate, slightly contaminated with heavy metal salts. The experiments and theoretical analysis detailed in this report were done to evaluate the risks for self-accelerating thermal decomposition, explosion, and detonation of polyethylene mixed with sodium nitrate. The study included the proposed waste form as specified and also several deviations from the specified composition and density, which could conceivably occur as a result of deficiencies in processing. The results indicate that the proposed polyethylene waste form, even including wide deviations from the specified composition and density, is a non-explosive, safe material to produce and transport by rail and road. It will not by itself cause explosion or detonation even if stored in a very large quantity, such as many tens of millions of pounds, provided the storage is free from any sources of large scale fire, such as wood or other solid combustible materials, containers of liquid or gaseous flammable fuels. The investigation included computer calculations using the TIGER code with BKW-R parameters to determine the detonation characteristics of the waste form assuming steady state detonation and complete reaction. Calculations using the NITRODYNE code were made to determine the explosion energy and equivalent weight of ANFO (ammonium nitrate mixed with fuel oil) for equal blasting performance. Experiments were made to further explore and determine the detonability (NSWC's Expanded Large Scale Gap Test), decomposition temperature, time-to-explosion or time-to-decomposition (Henkin-McGill tests), critical temperature for runaway thermal decomposition (one-liter cook-off test), and the risk for explosion when the material is heated in a strong steel confinement (United Nations SCB'' closed bomb test).

Block-Bolten, A.; Olson, D.; Persson, P.A.; Sandstrom, F. (New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Center for Explosives Technology Research)

1991-06-08

248

Using polyethylene glycols as alternative inhibitors in copper electrorefining  

Microsoft Academic Search

Polyethylene glycols (PEGs) with well-defined molecular weight ranges are interesting alternative additives for copper electrorefining.\\u000a In comparison to glue, PEGs offer high thermal stability and slow chemical decomposition at higher temperatures, with high\\u000a cathodic polarization. Thosefactors are advantages for an optimized process control in copper electrorefining. Investigations\\u000a into cathodic polarization as a function of molecular weight and concentration at 500

Michael Stelter; Hartmut Bombach; Nikolay Nesterov

2002-01-01

249

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

250

Low-temperature thermal properties of nylon and polyethylene  

Microsoft Academic Search

The thermal conductivity and heat capacity of polyethylene and nylon samples have been measured in the temperature range 0.15–4°K. A good theoretical fit is obtained for the thermal conductivity above 1°K by using a Debye ?2 phonon frequency distribution with constant mean free path internal boundary scattering and amorphous structure scattering. Below 1°K the experimental results show a lower power

Terry A. Scott; Johannes de Bruin; Monte M. Giles; Colin Terry

1973-01-01

251

Band structure of polyethylene from many-body perturbation theory  

NASA Astrophysics Data System (ADS)

The electronic structure of polyethylene is an important benchmark and the infinite chain limit for the electronic properties of many molecules, monolayers, and oligomers. Therefore, the band structure of the ideal, one-dimensional polyethylene chain has been extensively researched, from both the experimental and the theoretical viewpoints. Despite this extensive effort, to the best of our knowledge agreement between theoretical calculations and the electronic structure obtained from photoelectron spectroscopy could only be obtained using artificial shifting and ``stretching'' of the computed data. Here, we present a quantitative quasi-particle band-structure for polyethylene using many-body perturbation theory. The approach is employed within the G0W0 approximation, based on a starting point calculated within the generalized gradient approximation to density functional theory. We compare our calculated band-structure to angle resolved photoemission spectroscopy measurements for various long saturated carbohydrates, demonstrate a much improved agreement with experiment, and discuss remaining discrepancies and their possible origins within both theory and experiment.

Biller, Ariel; Sharifzadeh, Sahar; Segev, Lior; Ismail-Beigi, Sohrab; Neaton, Jeffrey B.; Kronik, Leeor

2013-03-01

252

Absorption current behaviour of polyethylene/silica nanocomposites  

NASA Astrophysics Data System (ADS)

Absorption current is an important characteristic of polymers with regard to their time-domain response to a direct current (DC) poling field. This is because the results of absorption current measurements can be used to gain understanding of the relationship between space charge accumulation and movement. In semicrystalline polyethylene, for example, charge accumulation is likely to be influenced by the presence of charge trapping sites, which are associated with interfaces between the crystalline and amorphous phases. With the addition of a nanofiller, the charge transport mechanism will become more complicated than in the unfilled polymer, as the inclusion of the nanofiller will introduce nanofiller/polymer interfaces. The presence of such interfaces will affect the current flow due to the introduction or modification of the distribution of trapping sites within the system. In this paper, we report on an investigation into the absorption current behaviour of polyethylene nanocomposites containing 0 wt%, 2 wt%, 5 wt% and 10 wt% of silica nanofiller, either untreated or treated using trimethoxy(propyl)silane coupling agent. Our results indicate that the absorption current behaviour of the polyethylene was affected by the presence of the nanosilica. While the current behaviour through the unfilled polymer decreases with time in a conventional manner, all nanocomposites reveal an initial decrease followed by a period in which the current increases with increasing time of DC field application.

Lau, K. Y.; Vaughan, A. S.; Chen, G.; Hosier, I. L.; Holt, A. F.

2013-11-01

253

Reasons of Revision for First-Generation Highly Crosslinked Polyethylenes  

PubMed Central

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

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

2010-01-01

254

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

255

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

256

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

257

Testing and evaluation of polyethylene and sulfur cement waste forms  

SciTech Connect

This paper discusses the results of recent studies related to the use of polyethylene and modified sulfur cement as new binder materials for the improved solidification of low-level wastes. Waste streams selected for this study include those which result from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those that remain problematic for solidification using contemporary agents (ion-exchange resins). Maximum waste loadings were determined for each waste type. Recommended waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash and 30 wt % ion exchange resins, which are based on process control and waste form performance considerations are reported for polyethylene. For sulfur cement the recommended waste loadings of 40 wt % sodium sulfate and boric acid salts and 43 wt % incinerator ash are reported. However, incorporation of ion-exchange resin waste in modified sulfur cement is not recommended due to poor waste form performance. The work presented in this paper will, in part, present data that can be used to assess the acceptability of polyethylene and modified sulfur cement waste forms to meet the requirements of 10 CFR 61. 8 refs., 10 figs., 6 tabs.

Franz, E.M.; Kalb, P.D.; Colombo, P.

1985-01-01

258

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Boric acid (H3BO3), mixed esters with polyethylene...Chemical Substances § 721.1729 Boric acid (H3BO3), mixed esters with polyethylene...chemical substance identified as boric acid (H3 BO3 ), mixed...

2010-07-01

259

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Boric acid (H3BO3), mixed esters with polyethylene...Chemical Substances § 721.1729 Boric acid (H3BO3), mixed esters with polyethylene...chemical substance identified as boric acid (H3 BO3 ), mixed...

2011-07-01

260

Morphology and dynamic mechanical properties of high density polyethylene\\/petroleum resin\\/polyethylene–octylene elastomer blends  

Microsoft Academic Search

The phase structure and dynamic mechanical thermal behaviors of high density polyethylene (HDPE)\\/hydrogenated petroleum resin\\u000a P-100\\/ethylene–octylene copolymer (POE) blends were investigated by utilizing polarized optical microscope (POM), scanning\\u000a electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic mechanical thermal analysis (DMA). Results of\\u000a POM and SEM indicated that the structures of the blends had a three-dimensional bi-continuous network. The network

Deming Cao; Yuanyi Cao; Chifei Wu

2009-01-01

261

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

262

Factory-assembled polyethylene linings in metal backing show higher wear rates compared to equisized all-polyethylene sockets.  

PubMed

Two series of cementless total hip arthroplasty with acetabular sockets of a threaded truncated cone design were compared regarding volumetric wear rates. The first series included all-polyethylene acetabular sockets of the type Endler (E-PE); in the second series, a nonmodular titanium metal-backed polyethylene (E-MB) socket with an identical outer shape to E-PE was implanted. Bearings were articulated with alumina 32-mm diameter ball heads. Ninety-five retrieved devices were examined with a modified fluid displacement method using dental self-polymerizing precision casts. The sockets had to be revised mainly because of wear-induced osteolysis: E-PE after 10.6 years on average and E-MB after 7.8 years (P = .002). Comparison with unused sockets showed mean wear rates of 63 mm(3)/y for E-PE and 120 mm(3)/y for E-MB (P = .0008). Increased contact stress and load deformation due to reduction of polyethylene thickness in E-MB compared to E-PE were identified as predominant reasons for higher wear rates. PMID:20647160

Jentschke, Matthias W; Schultz, Wolfgang; Buchhorn, Gottfried H

2011-06-01

263

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

264

Nonfouling poly(ethylene oxide) layers end-tethered to polydopamine.  

PubMed

Nonfouling surfaces capable of reducing protein adsorption are highly desirable in a wide range of applications. Coating of surfaces with poly(ethylene oxide) (PEO), a water-soluble, nontoxic, and nonimmunogenic polymer, is most frequently used to reduce nonspecific protein adsorption. Here we show how to prepare dense PEO brushes on virtually any substrate by tethering PEO to polydopamine (PDA)-modified surfaces. The chain lengths of hetero-bifunctional PEOs were varied in the range of 45-500 oxyethylene units (M(n) = 2000-20,000). End-tethering of PEO chains was performed through amine and thiol headgroups from reactive polymer melts to minimize excluded volume effects. Surface plasmon resonance (SPR) was applied to investigate the adsorption of model protein solutions and complex biologic medium (human blood plasma) to the densely packed PEO brushes. The level of protein adsorption of human serum albumin and fibrinogen solutions was below the detection limit of the SPR measurements for all PEO chains end-tethered to PDA, thus exceeding the protein resistance of PEO layers tethered directly on gold. It was found that the surface resistance to adsorption of lysozyme and human blood plasma increased with increasing length and brush character of the PEO chains end-tethered to PDA with a similar or better resistance in comparison to PEO layers on gold. Furthermore, the chain density, thickness, swelling, and conformation of PEO layers were determined using spectroscopic ellipsometry (SE), dynamic water contact angle (DCA) measurements, infrared reflection-absorption spectroscopy (IRRAS), and vibrational sum-frequency-generation (VSFG) spectroscopy, the latter in air and water. PMID:22989020

Pop-Georgievski, Ognen; Verreault, Dominique; Diesner, Mark-Oliver; Proks, Vladimír; Heissler, Stefan; Rypá?ek, František; Koelsch, Patrick

2012-10-01

265

Synthesis, patterning and applications of star-shaped poly(ethylene glycol) biofunctionalized surfaces.  

PubMed

Poly(ethylene) glycol (PEG) is an excellent material to modify surfaces to resist non-specific protein adsorption. Linear PEG has been extensively studied both theoretically and experimentally and it has been found that resistance of PEG-coated surfaces to protein adsorption depends mainly on the molecular weight of the polymer and the surface grafting density. End-functionalized star-shaped PEGs allow for interpolymer crosslinking to form a dense layer. An excellent example of such a system consists of a 6-arm PEG/PPG (4 : 1) star polymer functionalized with isocyanate using IPDI. The end functionalization may be further biofunctionalized to recognize specific biomolecules such as streptavidin, His-tagged proteins, amino-terminated oligonucleotides and cell receptors. This functionalization may be patterned into specific geometries using stamping techniques or randomly distributed by statistical reaction of the end group with the biofunctional molecule in solution. The surface preparation uses simple spin-, dip- or spray-coating and produces smooth layers with low background fluorescence. These properties, together with the advantageous chemical properties of PEG, render the surfaces ideal for immobilizing proteins on surfaces with detection limits down to the single molecule level. Proteins immobilized on such surfaces are able to maintain their folded, functional form and are able to completely refold if temporarily exposed to denaturing conditions. Immobilized enzyme molecules were able to perform their function with the same activity as the enzyme in solution. Future directions of using surfaces coated with such crosslinked star polymers in highly sensitive and robust biotechnology applications will be discussed. PMID:17533455

Heyes, Colin D; Groll, Jürgen; Möller, Martin; Nienhaus, G Ulrich

2007-06-01

266

Production of selenomethionine-labeled proteins in two-liter plastic bottles for structure determination  

Microsoft Academic Search

A simplified approach developed recently for the production of heterologous proteins in Escherichia coli uses 2-liter polyethylene terephthalate beverage bottles as disposable culture vessels [Sanville Millard, C. et al. 2003. Protein Expr. Purif. 29, 311–320]. The method greatly reduces the time and effort needed to produce native proteins for structural or functional studies. We now demonstrate that the approach is

Lucy Stols; Cynthia Sanville Millard; Irina Dementieva; Mark I. Donnelly

2004-01-01

267

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

268

Relationship Between Bond Strength and Crystallinity of High Polymers-Polyethylene, Polyethyleneterephthalate, and Nylon  

Microsoft Academic Search

The effect of crystallinity of polyethylene on the peel strength of aluminum plate-polyethylene-aluminum foil laminate was investigated. The 180° peel strength increased by rapid cooling with water, ice water, or liquid nitrogen after bonding with hot-melt polyethylene compared with slow cooling with air at room temperature. It was concluded that the increase of peel strength by rapid cooling was due

Kazumune Nakao

1972-01-01

269

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

Microsoft Academic Search

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

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

2001-01-01

270

Ceramic Head Fracture in Ceramic-on-Polyethylene Total Hip Arthroplasty  

PubMed Central

Revision rates of total hip arthroplasty have decreased after introducing total hip arthroplasty (THA) using ceramic component, since ceramic components could reduce components wear and osteolysis. The fracture of a ceramic component is a rare but potentially serious event. Thus, ceramic on polyethylene articulation is gradually spotlighted to reduce ceramic component fracture. There are a few recent reports of ceramic head fracture with polyethylene liner. Herein, we describe a case of a ceramic head component fracture with polyethylene liner. The fractured ceramic head was 28 mm short neck with conventional polyethylene liner. We treated the patient by total revision arthroplasty using 4th generation ceramic on ceramic components. PMID:24142666

Nho, Jae-Hwi; Song, Ui-Seoub; Kim, Woo-Jong; Suh, You-Sung

2013-01-01

271

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

272

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

PubMed

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

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

2013-10-01

273

An Improved Cryosection Method for Polyethylene Glycol Hydrogels Used in Tissue Engineering  

PubMed Central

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

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

2013-01-01

274

Electrostatic Assembly of Poly(ethylene glycol) Nanotubes.  

PubMed

Poly(ethylene glycol) (PEG)-based films, nanotubes, and nanotube arrays were successfully made using layer-by-layer (LbL) assembly ion-containing PEO derivatives on porous templates and planar substrates. PEG nanotubes are challenging to produce because PEG dissolves into solutions and solvents used during nanotube processing, but our techniques circumvent the issue. Nanotube dimensions were verified using microscopy and the average observed diameter was 155?nm. The PEG-based structures showed remarkable stability in water, salt water, and sodium hydroxide solution. PMID:21590966

Jang, Woo-Sik; Saito, Tomonori; Hickner, Michael A; Lutkenhaus, Jodie L

2010-04-20

275

Electron and hole mobility edges in polyethylene from material simulations  

NASA Astrophysics Data System (ADS)

We determine the electron and hole mobility edges in amorphous polyethylene (PE) by calculating the boundary between localized and delocalized states in energy space. First, the molecular structure is simulated with molecular dynamics simulations. Then, the electronic structure is calculated with density functional theory. For the calculation of the mobility edge, we use two approaches, the Inverse Participation Ratio, and a new method based on percolation theory. They turn out to provide the same results; the electron and hole mobility edges are <0.05 eV and 0.25 eV away from the respective band edge, respectively.

Unge, Mikael; Christen, Thomas

2014-10-01

276

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

277

Branched carbon nanotube reinforcements for improved strength of polyethylene nanocomposites  

NASA Astrophysics Data System (ADS)

A bio-inspired design of polyethylene nanocomposites is presented in this letter using branched carbon nanotubes (BCNTs) as reinforcements. Using coarse-grained molecular dynamics simulations, we demonstrate that the pullout strength of the proposed BCNT nanofibers can be an order of magnitude higher than that of CNT reinforcements. The drastically improved interfacial shearing strength is found to be strongly dependent on the geometry of nanofibers, the molecular weight of matrix polymers, and the pullout velocity. By analyzing the time-evolving molecular configurations of BCNT nanofibers and surrounding polymer chains, the underlying strengthening mechanisms are discussed and strategies for further improvement are suggested.

Liu, Ling; Zhang, Lin; Lua, Jim

2012-10-01

278

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

279

Preparation of Sterically Stabilized Human Serum Albumin Nanospheres Using a Novel Dextranox-MPEG Crosslinking Agent  

Microsoft Academic Search

Human serum albumin (HSA) nanospheres with a size less than 200 nm in diameter were prepared using a modified coacervation method and crosslinking with methyl polyethylene glycol modified oxidized Dextram (Dextranox-MPEG) which created a sterically stabilizing polyethylene oxide surface layer surrounding the nanospheres. The crosslinking efficiency and the surface characteristics of glutaraldehyde and Dextranox-MPEG crosslinked HSA nanospheres were determined and

Wu Lin; Allan G. A. Coombes; Martin C. Garnett; Martyn C. Davies; Etienne Schacht; Stanley S. Davis; Lisbeth Illum

1994-01-01

280

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

281

Effect of tocopheryl polyethylene glycol succinate on the percutaneous penetration of minoxidil from water/ethanol/polyethylene glycol 400 solutions.  

PubMed

We described to achieve the local retention of minoxidil which has penetrated the skin with minimization of its absorption into the general circulation and elimination of local irritation induced by propylene glycol. The effect of tocopheryl polyethylene glycol succinate (TPGS) on the penetration flux of minoxidil and its retention in the skin from topical minoxidil formulations consisting of water, alcohol, and polyethylene glycol 400 was characterized by an experimental design of ten solvent formulations in this study. Results show that the addition of TPGS was only able to improve the solubility of minoxidil in those solvent systems containing higher proportions of water and PEG 400, and the extent of improvement was also more profound with the addition of TPGS at concentrations higher than 5%. For those solvent systems containing a higher fraction of alcohol, an insignificant change in minoxidil solubility with increasing added amounts of TPGS was noted even with the tendency to decrease the solubility of minoxidil with higher amounts of TPGS. Increasing the amount of TPGS added gradually increased the flux and the corrected flux from solvent formulations with a lower solubility parameter, but decreased those from solvent systems with a higher solubility parameter. With the addition of TPGS, solvent formulation F6 (alcohol:PEG 400 of 50:50) was demonstrated to be the optimal choice by having an improved local effect and a reduced systemic effect compared to the reference of 2% Regaine((R)). Tocopheryl polyethylene glycol succinate (TPGS) was mainly retained locally in the stratum corneum, and the amount was proportional to the increase in the amount of TPGS added to these ten solvent formulations. PMID:16720414

Sheu, Ming-Thau; Wu, An-Bang; Lin, Keng-Ping; Shen, Chao-Hui; Ho, Hsiu-O

2006-06-01

282

Particle Size Control of Polyethylene Glycol Coated Fe Nanoparticles  

NASA Astrophysics Data System (ADS)

Recent interest in Fe nanoparticles with high magnetization is driven by their potential use in biomedical applications such as targeted drug delivery, MRI contrast enhancement and hyperthermia treatment of cancer. This study looks at the use of a polyethylene glycol (PEG) solution to mediate the particle size and therefore control the coercivity of the resulting nanoparticles. Iron nanoparticles were synthesized using an aqueous sodium borohydride reduction of ferrous chloride by a simultaneous introduction of reagents in a Y- junction. The resulting product was collected in a vessel containing a 15 mg/ml carboxyl terminated polyethylene glycol (cPEG) in ethyl alcohol solution located under the Y junction. By varying the length of tubing below the Y junction, the particle size was varied from 5-25 nm. X-ray diffraction data indicates the presence of either amorphous Fe-B or crystalline alpha Fe, depending on the molar ratio of reagents. Magnetic measurements indicate the particles are ferromagnetic with values of coercivity ranging from 200-500 Oe and a saturation magnetization in range of 70-110 emu/g. The XRD shows that the particles are not affected by the polymer coating.

Srinivasan, B.; Bonder, M. J.; Zhang, Y.; Gallo, D.; Hadjipanayis, G. C.

2006-03-01

283

Degradation rate of ultra-high molecular weight polyethylene.  

PubMed

Ultra-high molecular weight polyethylene components for total joint replacement chemically degrade before and after implantation, and the degradation is associated with an increase in density. The goal of this study was to determine the average rate of density change in these components following sterilization by gamma radiation in air as a function of shelf age and implantation time. Using the density gradient column method, density profiles were obtained through the thickness from loaded and unloaded regions of 10 retrieved Insall-Burstein/Posterior-Stabilized II tibial components and one operating-room inventory component for which the initial density profile and patient history (if applicable) were known. The average density of the components increased at a constant rate of 0.000186 g/cc/month during the first 50 months after sterilization (r2 = 0.54) but was not significantly affected by loading (p > 0.05). The quantitative degradation rates may be useful to help verify kinetic models to predict bulk degradative changes on the basis of micro-structural and chemical processes. This research also suggests the hypothesis that degradation of ultra-high molecular weight polyethylene can be modeled in terms of changes in bulk or average properties. PMID:9066527

Kurtz, S M; Rimnac, C M; Bartel, D L

1997-01-01

284

Partitioning of organochlorine pesticides from water to polyethylene passive samplers.  

PubMed

The mass transfer rates and equilibrium partitioning behaviour of 14 diverse organochlorine pesticides (OCP) between water and polyethylene (PE) passive samplers, cut from custom made PE sheets and commercial polyethylene plastic bags, were quantified. Overall mass transfer coefficients, k(O), estimated PE membrane diffusion coefficients, D(PE), and PE-water partitioning coefficients, K(PE-water,) are reported. In addition, the partitioning of three polycyclic aromatic hydrocarbons (PAHs) from water to PE is quantified and compared with literature values. K(PE-water) values agreed mostly within a factor of two for both passive samplers and also with literature values for the reference PAHs. As PE is expected to exhibit similar sorption behaviour to long-chain alkanes, PE-water partitioning coefficients were compared to hexadecane-water partitioning coefficients estimated with the SPARC online calculator, COSMOtherm and a polyparameter linear free energy relationship based on the Abraham approach. The best correlation for all compounds tested was with COSMOtherm estimated hexadecane-water partitioning coefficients. PMID:20398988

Hale, Sarah E; Martin, Timothy J; Goss, Kai-Uwe; Arp, Hans Peter H; Werner, David

2010-07-01

285

Cancellous bone homograft storage with aluminium-polyethylene bags.  

PubMed

In order to transport and cryopreserve human tissues, it is essential to have an easy-to-use recipient where tissues can be kept in sterile conditions. Here we show the results obtained by using Macopharma's tissue freezing bags, an aluminium-polyethylene multilayer bag, in our tissue bank of the Centro Comunitario de Sangre y Tejidos de Asturias. Five hundred and twenty-seven cancellous bone homografts were obtained from hospitals located 120 km around our Bank. The homografts were submitted to bacteriological controls and sent to our bank in these bags. They were stored at -70 degrees C and sent in dry ice to about 50 hospitals, where the tissue was bacteriologically controlled and grafted. Furthermore, the behaviour of these bags at -140 degrees C (vapour nitrogen) or -196 degrees C (liquid nitrogen) was tested. Our results indicate that Macopharma aluminium-polyethylene bags are suitable for the transporting and cryopreserving of cancellous bone homografts. These bags could also be used for keeping tissues in nitrogen containers. PMID:16933042

Meana, A; Martinez, R; Cañal, P; Arriaga, M J; Román, F San; Llames, S; Orós, C; Moreno, A; Fernandez, C

2006-01-01

286

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

E-print Network

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

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

2003-01-01

287

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

Microsoft Academic Search

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

Hidetoshi Matsumoto; Yoshiyuki Koyama; Akihiko Tanioka

2003-01-01

288

Prececal, postileal and total tract digestion of cottonseed and soybean protein in horses  

E-print Network

small 14 increase in C-labelled amino acids in portal blood following a similar incubation and cecal infusion technique. Prior et al. (1974) reported that urea could be drawn across the cecal wall for synthesis into microbial protein...), digestibilities were compared in 6 burros using Cr203, polyethylene, cerium-144 and the total fecal collection technique. No significant differences between digestion coefficients were observed using polyethylene, cerium-144, or the total collection technique...

Haley, Ronald Gene

2012-06-07

289

Leaching of antimony from polyethylene terephthalate (PET) bottles into mineral water  

E-print Network

Leaching of antimony from polyethylene terephthalate (PET) bottles into mineral water Szilvia SODIS The Sb leaching from polyethylene terephthalate (PET) package material into 10 different brands measured in PET package materials varied between 210 and 290 mg/kg. Generally, the Sb concentration

Short, Daniel

290

Selected Physical Characteristics of Polystyrene/High Density Polyethylene Composites Prepared from Virgin  

E-print Network

Selected Physical Characteristics of Polystyrene/High Density Polyethylene Composites Prepared from: Mixtures of polystyrene and high density polyethylene were injection molded from recycled and virgin suppression and a more pronounced Tg shift in the polystyrene compared to recycled materials. Detailed

291

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

Microsoft Academic Search

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

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

1994-01-01

292

Sodalite ion exchange in polyethylene oxide oligomer solvents Gina M. Canfield,a  

E-print Network

complexes that form with transition metal and rare earth cations. This can lead to the breakdown and rare earth ions. Ethylene oxide-based oligomers (polyethylene glycol, polyethylene glycol methyl ether to handle and not well-suited for aluminosilicate zeolites.5 Likewise, molten salt ion exchange (immersion

Latturner, Susan

293

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"

294

Linear or Branched Polyethylenes from Supported Aryloxytitanium(IV)-Cyclopentadienyl Complexes  

E-print Network

and 13 C NMR have confirmed the presence of the mono- and bis(aryloxy) components in these macroligated and 13 C NMR are consistent with polyethylene having butyl short chain branches evenly distributed along of branched polyethylene synthesis by the use of Ti and/or Zr catalysts in conjunction with an aluminum

295

Experimental investigation of laboratory-scale rocket engine fed on solid polyethylene rod as fuel  

NASA Astrophysics Data System (ADS)

Fire testing of the laboratory-scale rocket engine with the consumable solid polyethylene rod as fuel is described. The experimental data on heat flows, gasification rate and heat transfer coefficient are presented. Results of the testing may be useful for designing launch vehicles with combustible polyethylene tank shells.

Yemets, V. V.; Sanin, F. P. Dzhur, Ye. O.; Masliany, M. V.; Kostritsyn, O. Yu.; Minteev, G. V.; Ushkanov, V. M.

296

Enhancement of the performance of gas hydrate kinetic inhibitors with polyethylene oxide  

Microsoft Academic Search

Inclusion of polyethylene oxide into a kinetic inhibitor solution was found to enhance the performance of the inhibitor. Polyethylene oxide is a commercially available high molecular weight polymer that is not a kinetic inhibitor by itself. The hydrate formation experiments in the presence of the various inhibitor solutions were conducted in a vessel in a semi-batch manner at constant pressure

Ju Dong Lee; Peter Englezos

2005-01-01

297

Molecular dynamics simulation of reorientation of polyethylene chains under a high magnetic field  

Microsoft Academic Search

The purpose of this investigation is to clarify the dynamical process of reorientation of a polyethylene chains under high magnetic fields. Molecular dynamics (MD) simulations at constant temperature and pressure are carried out to study the reorientation of two polyethylene chains with different configurations. We utilized static homogeneous external magnetic fields of 25 T into the velocity Verlet integration algorithm through

M. S. Al-Haik; M. Y. Hussaini

2006-01-01

298

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.

299

Transient foreign gene expression in polyethylene\\/glycol treated or electropulsated Eucalyptus gunnii protoplasts  

Microsoft Academic Search

Conditions for optimal transient gene expression of reporter genes (chloramphenicol acetyl transferase and ß-glucuronidase) by polyethylene glycol or electrical treatment of Eucalyptus gunnii protoplasts derived from callus or cell suspension cultures were investigated. The effciency of electropermeabilisation depended on several factors including electrical parameters, pH and the source of protoplasts. Polyethylene glycol mediated DNA uptake was highly stimulated by heat

C. Teulières; J. Grima-Pettenati; C. Curie; J. Teissie; A. M. Boudet

1991-01-01

300

Crystallographic texture evolution in high-density polyethylene during uniaxial tension  

E-print Network

(SCB) or a very small fraction of SCB. Copolymerization of ethylene with a 1-alkene type comonomer yields poly- ethylenes with a larger fraction of SCB, the so-called linear low density polyethylenes leads to polyethylenes and ethylene co- polymers with both types of branching, SCB and long chain

Garmestani, Hamid

301

Comparative investigations of surface instabilities (“sharkskin”) of a linear and a long-chain branched polyethylene  

Microsoft Academic Search

An experimental study of the physical origin and the mechanisms of the sharkskin instability is presented. Extrusion flows through a slit die are studied for two materials: a linear low density polyethylene (LLDPE) which exhibits sharkskin instability for flow rates larger than an onset value and a low density polyethylene (LDPE) which does not show any instability over a broad

Teodor I. Burghelea; Hans Jürgen Griess; Helmut Muenstedt

2010-01-01

302

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

303

Phase Behavior of Mixtures of Rods (Tobacco Mosaic Virus) and Spheres (Polyethylene Oxide, Bovine Serum Albumin)  

E-print Network

) with globular macromolecules such as polyethylene oxide (PEO) or bovine serum albumin (BSA) phase separate Serum Albumin) Marie Adams and Seth Fraden Martin Fisher School of Physics, Brandeis University, WalthamPhase Behavior of Mixtures of Rods (Tobacco Mosaic Virus) and Spheres (Polyethylene Oxide, Bovine

Fraden, Seth

304

Formation of an Intrapolymer Complex from Human Serum Albumin and Poly(ethylene glycol)  

E-print Network

Formation of an Intrapolymer Complex from Human Serum Albumin and Poly(ethylene glycol) Shinji Form: October 13, 1998 Complexation between human serum albumin (HSA) and poly(ethylene glycol) (PEG, it has been demonstrated that poly(dial- lyldimethylammonium chloride) and bovine serum albu- min give

Dubin, Paul D.

305

Association of hydrophobically-modified poly(ethylene glycol) with fusogenic liposomes  

E-print Network

Association of hydrophobically-modified poly(ethylene glycol) with fusogenic liposomes Debra T interactions to shield liposomes by incorporating multiple hydrophobic anchoring sites on polyethylene glycol. Fusogenic liposomes prepared from N-C12-DOPE:DOPC 7:3 (mol:mol) were equilibrated with HMPEGs. Affinity

Auguste, Debra T.

306

Degradation of degradable starch-polyethylene plastics in a compost environment  

SciTech Connect

Degradable plastics have differing degradation rates. Three types of degradation of polyethylene in the starch-polyethylene polymers can occur: chemical degradation, photodegradation, and biological degradation. This study examines all three types of degradation in 11 commercially produced degradable starch-polyethylene bags. Different rates for chemical and photo-degradation were found within a 20 day or an 8-week period. Results indicated that both the 70[degree]C oven and HT-HH film treatments were appropriate methods to evaluate oxidative degradation. In a compost environment, oxygen tension on the surface of the film appears to be the rate-limiting component for both chemical and biological degradation. Levels of starch in all bags was similar, so the prooxidant additive was critical in promoting the oxidative degradation of polyethylene. The Fe-Mn additive displayed the best catalytic activity. This study overall confirms degradation of starch-polyethylene plastics in a natural environment. 17 refs., 6 figs., 2 tabs.

Johnson, K.E.; Pometto, A.L. III; Nikolov, Z.L. (Iowa State Univ., Ames (United States))

1993-04-01

307

Ketene functionalized polyethylene: control of cross-link density and material properties.  

PubMed

The functionalization and cross-linking of polyethylene is synthetically challenging, commonly relying on highly optimized radical based postpolymerization strategies. To address these difficulties, a norbornene monomer containing Meldrum's acid is shown to be effectively copolymerized with polyethylene using a nickel ?-iminocarbaxamidato complex, providing high-melting, semicrystalline polymers with a tunable incorporation of the functional comonomer. Upon heating the copolymer to common polyethylene processing temperatures, the thermolysis of Meldrum's acid to ketene provides the desired reactive group. This simple and versatile methodology does not require small molecule radical sources or catalysts, and the dimerization of the in situ generated ketenes is shown to provide tunable cross-linking densities in polyethylene. Subsequent rheological and tensile experiments illustrate the ability to tune cross-linked polyethylene properties by comonomer incorporation and elucidate valuable structure/property relationships in these materials. This study illustrates the power of well-defined and synthetically accessible functional groups in polyolefin synthesis and functionalization. PMID:20923158

Leibfarth, Frank A; Schneider, Yanika; Lynd, Nathaniel A; Schultz, Alison; Moon, Bongjin; Kramer, Edward J; Bazan, Guillermo C; Hawker, Craig J

2010-10-27

308

Environmental evaluation of polyethylene oxide when used as a flocculant for clay wastes  

SciTech Connect

A method of flocculation dewatering of phosphatic clay wastes using polyethylene oxide as the flocculant is reported. Research was conducted to determine whether ethylene oxide gas was present in the air in the vicinity of disposed waste materials which had been flocculated with polyethylene oxide. Samples of clay waste materials containing polyethylene oxide were prepared in stoppered glass bottles in simulated disposal environments. Gaseous samples, removed over a 75-day period using an airtight syringe, were injected into a gas chromatograph that was capable of separating ethylene oxide from air. The presence of ethylene oxide gas was not detected in any sample. To determine possible degradation products of polyethylene oxide, the properties and reactions of ethylene oxide and its polymers were reviewed. Based upon the literature survey and experimental study, it was concluded that adverse environmental effects were not likely to result from the use of polyethylene oxide for flocculating phosphatic clay waste products.

Zatko, J.R.

1980-01-01

309

Direct reprogramming of mouse fibroblasts to cardiomyocyte-like cells using Yamanaka factors on engineered poly(ethylene glycol) (PEG) hydrogels  

PubMed Central

Direct reprogramming strategies enable rapid conversion of somatic cells to cardiomyocytes or cardiomyocyte-like cells without going through the pluripotent state. A recently described protocol couples Yamanaka factor induction with pluripotency inhibition followed by BMP4 treatment to achieve rapid reprogramming of mouse fibroblasts to beating cardiomyocyte-like cells. The original study was performed using Matrigel-coated tissue culture polystyrene (TCPS), a stiff material that also non-specifically adsorbs serum proteins. Protein adsorption-resistant poly(ethylene glycol) (PEG) materials can be covalently modified to present precise concentrations of adhesion proteins or peptides without the unintended effects of non-specifically adsorbed proteins. Here, we describe an improved protocol that incorporates custom-engineered materials. We first reproduced the Efe et al. protocol on Matrigel-coated TCPS (the original material), reprogramming adult mouse tail tip mouse fibroblasts (TTF) and mouse embryonic fibroblasts (MEF) to cardiomyocyte-like cells that demonstrated striated sarcomeric ?-actinin staining, spontaneous calcium transients, and visible beating. We then designed poly(ethylene glycol) culture substrates to promote MEF adhesion via laminin and RGD-binding integrins. PEG hydrogels improved proliferation and reprogramming efficiency (evidenced by beating patch number and area, gene expression, and flow cytometry), yielding almost twice the number of sarcomeric ?-actinin positive cardiomyocyte-like cells as the originally described substrate. These results illustrate that cellular reprogramming may be enhanced using custom-engineered materials. PMID:23773820

Smith, Amanda W.; Hoyne, Jake D.; Nguyen, Peter K.; McCreedy, Dylan A.; Aly, Haytham; Efimov, Igor R.; Rentschler, Stacey; Elbert, Donald L.

2013-01-01

310

Quantification of the Influence of Protein-Protein Interactions on Adsorbed Protein Structure and Bioactivity  

PubMed Central

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 2 h to saturate the surface, followed by immersion in pure buffer solution for 15 h 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.

2013-01-01

311

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

312

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

313

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

314

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

315

Antibacterial Performance of Alginic Acid Coating on Polyethylene Film  

PubMed Central

Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance. PMID:25196604

Karbassi, Elika; Asadinezhad, Ahmad; Lehocký, Marian; Humpolí?ek, Petr; Vesel, Alenka; Novák, Igor; Sáha, Petr

2014-01-01

316

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

317

Electron beam induced modification of poly(ethylene terephthalate) films  

NASA Astrophysics Data System (ADS)

Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy).

Vasiljeva, I. V.; Mjakin, S. V.; Makarov, A. V.; Krasovsky, A. N.; Varlamov, A. V.

2006-10-01

318

Silk fibroin and polyethylene glycol-based biocompatible tissue adhesives  

PubMed Central

Tissue sealants have emerged in recent years as strong candidates for hemostasis. A variety of formulations are currently commercially available and though they satisfy many of the markets’ needs there are still key aspects of each that need improvement. Here we present a new class of blends, based on silk fibroin and chemically active polyethylene glycols (PEGs) with strong adhesive properties. These materials are cytocompatible, crosslink within seconds via chemical reaction between thiols and maleimides present on the constituent PEGs and have the potential to further stabilize through ?-sheet formation by silk. Based on the silk concentration in the final formulation, the adhesive properties of these materials are comparable or better than the current leading PEG-based sealant. In addition, the silk-PEG based materials show decreased swelling and longer degradation times. Such properties would make them suitable for applications for which the current sealants are contraindicated. PMID:21681949

Serban, Monica A.; Panilaitis, Bruce; Kaplan, David L.

2012-01-01

319

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

320

Clickable Poly(ethylene glycol)-Microsphere-Based Cell Scaffolds  

PubMed Central

Clickable poly(ethylene glycol) (PEG) derivatives are used with two sequential aqueous two-phase systems to produce microsphere-based scaffolds for cell encapsulation. In the first step, sodium sulfate causes phase separation of the clickable PEG precursors and is followed by rapid geleation to form microspheres in the absence of organic solvent or surfactant. The microspheres are washed and then deswollen in dextran solutions in the presence of cells, producing tightly packed scaffolds that can be easily handled while also maintaining porosity. Endothelial cells included during microsphere scaffold formation show high viability. The clickable PEG-microsphere-based cell scaffolds open up new avenues for manipulating scaffold architecture as compared with simple bulk hydrogels. PMID:24052690

Nguyen, Peter K.; Snyder, Christopher G.; Shields, Jason D.; Smith, Amanda W.

2013-01-01

321

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

322

RAPID COMMUNICATION: Pressure effect on the electrical ageing of polyethylene  

NASA Astrophysics Data System (ADS)

The purpose of this study is to show the effect of hydrostatic pressure on the electrical ageing, by a dc voltage, on polyethylene used in submarine cables. Experimental results are obtained at 1 and 300 bar, for a temperature of 70 °C in the range of an electrical field of 1.1-4.5 MV cm-1 and for up to 1500 h of ageing. By using the Weibull statistic and the estimation of confidence bounds of 90%, the results have shown an increase of lifetime with pressure. The time dependence of the breakdown behaviour of the two materials (HDPE and XLPE) is consistent with the inverse power law model. The pressure effect may be explained by changes in the activation free energy for the formation of submicrocavities.

Lalam, F.-Benlizidia; Hoang-The-Giam

2000-11-01

323

Development of submicrometer periodic surface structures on polyethylene terephthalate  

NASA Astrophysics Data System (ADS)

Submicrometer Laser Induced Periodic Surface Structures (LIPSS) were generated on polyethylene-terephthalate (PET) using polarized beam of an ArF excimer laser, having a fluence of 4 mJ/cm2. Atomic Force Microscope and a home made repositionable sample holder was used to follow the morphological changes on the same part of the surface shot by shot. The main phases of the structure formation process were described: light scattering on the granulates which exist also on the original PET surface; appearance of additional granules and formation of elliptical modulation around the granules; transformation into ripple-shape modulation. The dependence of the LIPSS period on the wavelength and on the angle of incidence was determined. The LIPSS generating feedback mechanism was described as the interference between the incoming and surface-scattered waves in the light modified region. It was shown that the LIPSS is a self-organized grating.

Csete, Maria; Bor, Zsolt

1998-08-01

324

Precision Polyolefin Structure: Modeling Polyethylene Containing Methyl and Ethyl Branches  

NASA Astrophysics Data System (ADS)

Sequenced copolymers of ethylene and diverse species have been created using acyclic diene metathesis (ADMET) polymerization, a step growth, condensation- type polymerization driven to high conversion by the removal of ethylene. ADMET permits control over branch content and branch length, which can be predetermined during the monomer synthesis, allowing sequence control in the resultant unsaturated polymer. Monomers are symmetrical ?,?dienes with a pendant functionality. Diverse functional groups are compatible with ADMET polymerization when Schrock’s or first-generation Grubb’s catalysts are used. Saturation with hydrogen after ADMET polymerization affords a polyethylene (PE) backbone bearing specific functionalities in precise places. Varying both the pendant functional group and the spacing between functionalities alters the physical and chemical properties of the polymer. Incorporation of alkyl chains into the PE backbone via ADMET leads to the study of perfect structures modeling the copolymerization of ethylene with ?-olefins such as 1-propene, 1-butene, 1-hexene, and 1-octene.

Rojas, Giovanni; Wagener, Kenneth B.

325

Development and characterization of novel polylactide and polyethylene nanocomposites  

NASA Astrophysics Data System (ADS)

This thesis examines the development and characterization of novel Polylactide (PLA) and Polyethylene (PE) nanocomposites. PLA and PE nanocomposites were fabricated using Multiwall Carbon Nanotube (MWNT) and Chitin Nanowhiskers (nC) as the reinforcing phase. Various processes were used to produce such nanocomposites including melt blending. two-stage batch foaming and solvent casting. The resulting composite and porous composite morphology and the influence of reinforcing phase were studied using an assortment of characterization methods. The results of this research can be summarized in three major findings: (1) MWNTs can impart PE with significant improvements in mechanical and electrical properties as they were found to be uniformly dispersed in the polymer (2) Solvent based processes were more effective than melt blending in dispersing MWNT in PLA, with greater improvements observed in the electrical and mechanical properties, and (3) Chitin nanowhiskers are an effective all natural reinforcement for PLA, with improvements observed in composite stiffness and porous composite morphology.

Rizvi, Reza

326

Polymer crystal-melt interfaces and nucleation in polyethylene  

E-print Network

Kinetic barriers cause polymers to crystallize incompletely, into nanoscale lamellae interleaved with amorphous regions. As a result, crystalline polymers are full of crystal-melt interfaces, which dominate their physical properties. The longstanding theoretical challenge to understand these interfaces has new relevance, because of accumulating evidence that polymer crystals often nucleate via a metastable, partially ordered "rotator" phase. To test this idea requires a theory of the bulk and interfacial free energies of the critical nucleus. We present a new approach to the crystal-melt interface, which represents the amorphous region as a grafted brush of loops in a self-consistent pressure field. We combine this theory with estimates of bulk free energy differences, to calculate nucleation barriers and rates via rotator versus crystal nuclei for polyethylene. We find rotator-phase nucleation is indeed favored throughout the temperature range where nucleation is observed. Our methods can be extended to other polymers.

Scott T. Milner

2010-09-22

327

Simulation of polyethylene glycol and calcium-mediated membrane fusion  

NASA Astrophysics Data System (ADS)

We report on the mechanism of membrane fusion mediated by polyethylene glycol (PEG) and Ca2+ 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 Ca2+-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 Ca2+ and PEG on membrane fusion.

Pannuzzo, Martina; De Jong, Djurre H.; Raudino, Antonio; Marrink, Siewert J.

2014-03-01

328

Polyethylene glycol reduces inflammation and aberrant crypt foci in carcinogen-initiated rats.  

PubMed

Polyethylene glycol 8000 inhibits the formation of tumors and of aberrant crypt foci (ACF) in carcinogen-initiated rats. We asked: is the inhibition associated with a reduction of colonic inflammation and an increase in colonic cell permeability? Twenty-eight, male F 344 rats were divided into two groups, 10 control animals and 18 animals initiated with azoxymethane. Nine of the rats in the carcinogen-initiated group were given a diet with 5% PEG 8000 in an AIN-93 based, high fat diet. The other nine, and the control group received the diet without the addition of PEG. Nine weeks later, the rats receiving the diet containing PEG had a 43% reduction in ACF (P<0.001) compared with the carcinogen-initiated rats on the control diet, a result confirming earlier observations that PEG inhibits colon carcinogenesis. The animals receiving the diet containing PEG also had a 10-fold reduction in fecal granulocyte marker protein (GMP) (P<0.001) compared with both the carcinogen-treated and the control animals. PEG reduced inflammation below the levels of carcinogen-treated and of untreated animals. Fecal water from the rats receiving PEG did not reduce transepithelial resistance of, or manitol flux through, human Caco-cells grown as monolayers in vitro. PEG may reduce colon carcinogenesis through a mechanism involving colonic inflammation. PMID:15896454

Karlsson, Pernilla C; Hughes, Roisin; Rafter, Joseph J; Bruce, W Robert

2005-06-01

329

Growth of sheep fed tannin-rich Albizia gummifera with or without polyethylene glycol.  

PubMed

Twenty-four intact male Bonga lambs were studied in a 100-day experiment to evaluate the effect of feeding tannin rich leaves of Albizia gummifera (AG) on nutrient utilization, growth performance, and carcass composition. The dietary treatments consisted of hay alone (T1, control), AG at 30 % of control diet + T1 (T2), and T2 + polyethylene glycol 6000 (PEG) (T3, 40 mg PEG, 1 kg AG/head on a dry mass (DM) basis. The lambs were individually fed at 50 g DM/kg live weight. In the last 10 days of the experiment, all animals from each treatment were harnessed with feces collection bags. At the end of the experiment, lambs were slaughtered after overnight fasting for measurements of carcass characteristics. Crude protein, neutral detergent fiber, and condensed tannin contents of AG were 300, 586, and 108 g/kg DM, respectively. Lambs fed AG with PEG had higher (P?

Yisehak, Kechero; Biruk, Kebede; Abegaze, Beyene; Janssens, Geert P J

2014-10-01

330

Injectable Dopamine-Modified Poly(ethylene glycol) Nanocomposite Hydrogel with Enhanced Adhesive Property and Bioactivity.  

PubMed

A synthetic mimic of mussel adhesive protein, dopamine-modified four-armed poly(ethylene glycol) (PEG-D4), was combined with a synthetic nanosilicate, Laponite (Na(0.7+)(Mg5.5Li0.3Si8)O20(OH)4)(0.7-)), to form an injectable naoncomposite tissue adhesive hydrogel. Incorporation of up to 2 wt % Laponite significantly reduced the cure time while enhancing the bulk mechanical and adhesive properties of the adhesive due to strong interfacial binding between dopamine and Laponite. The addition of Laponite did not alter the degradation rate and cytocompatibility of PEG-D4 adhesive. On the basis of subcutaneous implantation in rat, PEG-D4 nanocomposite hydrogels elicited minimal inflammatory response and exhibited an enhanced level of cellular infiltration as compared to Laponite-free samples. The addition of Laponite is potentially a simple and effective method for promoting bioactivity in a bioinert, synthetic PEG-based adhesive while simultaneously enhancing its mechanical and adhesive properties. PMID:25222290

Liu, Yuan; Meng, Hao; Konst, Shari; Sarmiento, Ryan; Rajachar, Rupak; Lee, Bruce P

2014-10-01

331

Poly(ethylene glycol)-containing hydrogel surfaces for antifouling applications in marine and freshwater environments.  

PubMed

This work describes the fabrication, characterization, and biological evaluation of a thin protein-resistant poly(ethylene glycol) (PEG)-based hydrogel coating for antifouling applications. The coating was fabricated by free-radical polymerization on silanized glass and silicon and on polystyrene-covered silicon and gold. The physicochemical properties of the coating were characterized by infrared spectroscopy, ellipsometry, and contact angle measurements. In particular, the chemical stability of the coating in artificial seawater was evaluated over a six-month period. These measurements indicated that the degradation process was slow under the test conditions chosen, with the coating thickness and composition changing only marginally over the period. The settlement behavior of a broad and diverse group of marine and freshwater fouling organisms was evaluated. The tested organisms were barnacle larvae (Balanus amphitrite), algal zoospores (Ulva linza), diatoms (Navicula perminuta), and three bacteria species (Cobetia marina, Marinobacter hydrocarbonoclasticus, and Pseudomonas fluorescens). The biological results showed that the hydrogel coating exhibited excellent antifouling properties with respect to settlement and removal. PMID:18759475

Ekblad, Tobias; Bergström, Gunnar; Ederth, Thomas; Conlan, Sheelagh L; Mutton, Robert; Clare, Anthony S; Wang, Su; Liu, Yunli; Zhao, Qi; D'Souza, Fraddry; Donnelly, Glen T; Willemsen, Peter R; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Liedberg, Bo

2008-10-01

332

Poly(ethylene glycol) monolayer formation and stability on gold and silicon nitride substrates.  

PubMed

Poly(ethylene glycol) (PEG) self-assembled monolayers (SAMs) are extensively used to modify substrates to prevent nonspecific protein adsorption and to increase hydrophilicity. X-ray photoelectron spectroscopy analysis, complemented by water contact angle measurements, is employed to investigate the formation and stability upon aging and heating of PEG monolayers formed on gold and silicon nitride substrates. In particular, thiolated PEG monolayers on gold, with and without the addition of an undecylic spacer chain, and PEG monolayers formed with oxysilane precursors on silicon nitride have been probed. It is found that PEG-thiol SAMs are degraded after less than two weeks of exposure to air and when heated at temperatures as low as 120 degrees C. On the contrary, PEG-silane SAMs are stable for more than two weeks, and fewer molecules are desorbed even after two months of aging, compared to those desorbed in two weeks from the PEG-thiol SAMs. A strongly bound hydration layer is found on PEG-silane SAMs aged for two months. Heating PEG-silane SAMs to temperatures as high as 160 degrees C improves the quality of the monolayer, desorbing weakly bound contaminants. The differences in stability between PEG-thiol SAMs and PEG-silane SAMs are ascribed to the different types of bonding to the surface and to the fact that the thiol-Au bond can be easily oxidized, thus causing desorption of PEG molecules from the surface. PMID:18729528

Cerruti, Marta; Fissolo, Stefano; Carraro, Carlo; Ricciardi, Carlo; Majumdar, Arun; Maboudian, Roya

2008-10-01

333

Anisotropic poly(ethylene glycol)/polycaprolactone hydrogel-fiber composites for heart valve tissue engineering.  

PubMed

The recapitulation of the material properties and structure of the native aortic valve leaflet, specifically its anisotropy and laminate structure, is a major design goal for scaffolds for heart valve tissue engineering. Poly(ethylene glycol) (PEG) hydrogels are attractive scaffolds for this purpose as they are biocompatible, can be modified for their mechanical and biofunctional properties, and can be laminated. This study investigated augmenting PEG hydrogels with polycaprolactone (PCL) as an analog to the fibrosa to improve strength and introduce anisotropic mechanical behavior. However, due to its hydrophobicity, PCL must be modified prior to embedding within PEG hydrogels. In this study, PCL was electrospun (ePCL) and modified in three different ways, by protein adsorption (pPCL), alkali digestion (hPCL), and acrylation (aPCL). Modified PCL of all types maintained the anisotropic elastic moduli and yield strain of unmodified anisotropic ePCL. Composites of PEG and PCL (PPCs) maintained anisotropic elastic moduli, but aPCL and pPCL had isotropic yield strains. Overall, PPCs of all modifications had elastic moduli of 3.79±0.90?MPa and 0.46±0.21?MPa in the parallel and perpendicular directions, respectively. Valvular interstitial cells seeded atop anisotropic aPCL displayed an actin distribution aligned in the direction of the underlying fibers. The resulting scaffold combines the biocompatibility and tunable fabrication of PEG with the strength and anisotropy of ePCL to form a foundation for future engineered valve scaffolds. PMID:24712446

Tseng, Hubert; Puperi, Daniel S; Kim, Eric J; Ayoub, Salma; Shah, Jay V; Cuchiara, Maude L; West, Jennifer L; Grande-Allen, K Jane

2014-10-01

334

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

PubMed Central

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. PMID:21890748

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

2011-01-01

335

Covalent enzyme immobilization by poly(ethylene glycol) diglycidyl ether (PEGDE) for microelectrode biosensor preparation.  

PubMed

Poly(ethylene glycol) diglycidyl ether (PEGDE) is widely used as an additive for cross-linking polymers bearing amine, hydroxyl, or carboxyl groups. However, the idea of using PEGDE alone for immobilizing proteins on biosensors has never been thoroughly explored. We report the successful fabrication of microelectrode biosensors based on glucose oxidase, d-amino acid oxidase, and glutamate oxidase immobilized using PEGDE. We found that biosensors made with PEGDE exhibited high sensitivity and a response time on the order of seconds, which is sufficient for observing biological processes in vivo. The enzymatic activity on these biosensors was highly stable over several months when they were stored at 4 °C, and over at least 3d at 37 °C. Glucose microelectrode biosensors implanted in the central nervous system of anesthetized rats reliably monitored changes in brain glucose levels induced by sequential administration of insulin and glucose. PEGDE provides a simple, low cost, non-toxic alternative for the preparation of in vivo microelectrode biosensors. PMID:21546239

Vasylieva, Natalia; Barnych, Bogdan; Meiller, Anne; Maucler, Caroline; Pollegioni, Loredano; Lin, Jian-Sheng; Barbier, Daniel; Marinesco, Stéphane

2011-06-15

336

Micropatterning of Proteins and Mammalian Cells on Indium Tin Oxide  

E-print Network

, photoresist was patterned on the glass surface and used as a stencil for adsorption of cell-adhesive protein This paper describes a novel surface engineering approach that combines oxygen plasma treatment. In this approach, photoresist was patterned onto an ITO substrate modified with poly(ethylene) glycol (PEG) silane

Revzin, Alexander

337

Aggressive wear testing of a cross-linked polyethylene in total knee arthroplasty.  

PubMed

Recently, highly cross-linked polyethylenes with high wear and oxidation resistance have been developed. These materials may improve the in vivo performance of polyethylene components used in total knee arthroplasty. To date, the in vitro knee wear testing of these new polyethylenes has been done under conditions of normal gait. However, their critical assessment also must include aggressive in vitro fatigue and wear testing. In the current study, an aggressive in vitro knee wear and device fatigue model simulating a tight posterior cruciate ligament balance during stair climbing was developed and used to assess the performance of one type of highly cross-linked polyethylene tibial knee insert in comparison with conventional polyethylene. The highly cross-linked inserts and one group of conventional inserts were tested after sterilization. One additional group of conventional inserts was subjected to accelerated aging before testing. The articular surfaces of the inserts were inspected visually for surface delamination, cracking, and pitting at regular intervals during the test. The aged conventional polyethylene inserts showed extensive delamination and cracking as early as 50,000 cycles. In contrast, the unaged conventional and highly cross-linked polyethylene inserts did not show any subsurface cracking or delamination at 0.5 million cycles. The appearance and location of delamination that occurred in the aged conventional inserts tested with the current model previously have been observed in vivo with posterior cruciate-sparing design knee arthroplasties with a tight posterior cruciate ligament. PMID:12439243

Muratoglu, Orhun K; Bragdon, Charles R; O'Connor, Daniel O; Perinchief, Rebecca S; Jasty, Murali; Harris, William H

2002-11-01

338

Preparation of polyethylene sacks for collection of precipitation samples for chemical analysis  

USGS Publications Warehouse

Polyethylene sacks are used to collect precipitation samples. Washing polyethylene with acetone, hexane, methanol, or nitric acid can change the adsorptive characteristics of the polyethylene. In this study, simulated precipitation at pH 4.5 was in contact with the polyethylene sacks for 21 days; subsamples were removed for chemical analysis at 7, 14, and 21 days after intitial contact. Sacks washed with acetone adsorbed iron and lithium; sacks washed with hexane adsorbed barium, iron , and lithium; sacks washed with methanol adsorbed calcium and iron; and sacks washed with 0.30 N nitric acid adsorbed iron. Leaching the plastic sacks with 0.15 N nitric acid did not result in 100-percent recovery of any of the adsorbed metals. Washing polyethylene sacks with dilute nitric acid caused the pH of the simulated precipitation to be decreased by 0.2 pH unit after 1 week of contact with the polyethylene. The specific conductance increased by 10 microsiemens per centimeter. Contamination of precipitation samples by lead was determined to be about 0.1 microgram per liter from contact with precleaned polyethylene sacks. No measurable contamination of precipitation samples by zinc occurred. (USGS)

Schroder, L.J.; Bricker, A.W.

1985-01-01

339

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

340

Assessment of using laponite cross-linked poly(ethylene oxide) for controlled cell adhesion and mineralization.  

PubMed

The in vitro cytocompatibility of silicate (Laponite clay) cross-linked poly(ethylene oxide) (PEO) nanocomposite films using MC3T3-E1 mouse preosteoblast cells was investigated while cell adhesion, spreading, proliferation and mineralization were assessed as a function of film composition. By combining the advantageous characteristics of PEO polymer (hydrophilic, prevents protein and cell adhesion) with those of a synthetic and layered silicate (charged, degradable and potentially bioactive) some of the physical and chemical properties of the resulting polymer nanocomposites could be controlled. Hydration, dissolution and mechanical properties were examined and related to cell adhesion. Overall, this feasibility study demonstrates the ability of using model Laponite cross-linked PEO nanocomposites to create bioactive scaffolds. PMID:20854941

Gaharwar, Akhilesh K; Schexnailder, Patrick J; Kline, Benjamin P; Schmidt, Gudrun

2011-02-01

341

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

342

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

PubMed

Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications force cost considerations to be kept low and throughput high. As such, materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 min with the ability to scale up 4 times by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby demonstrating that the approach is compatible with high performance, real-world clinical measurements in the context of point-of-care testing. PMID:23183187

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

2013-04-15

343

Fracture of a Polyethylene Tibial Post in a Scorpio Posterior-Stabilized Knee Prosthesis  

PubMed Central

We report the case of a polyethylene tibial post fracture in a 72-year-old woman 14 months after a Scorpio posterior-stabilized (PS) total knee arthroplasty. The polyethylene wear was found around the fracture site of the post, especially over the anterior aspect of the post base. The failure mechanism of the post fracture in the present case was anterior impingement with excessive wear over the base of the anterior aspect of the tibial post, which became a stress-riser of post and cam articulation. This is the first report of a polyethylene tibial post fracture of a Scorpio PS prosthesis. PMID:19885065

Lim, Hong Chul; Hwang, Jin Ho; Kim, Seung Joo; Yoon, Ji Yeol

2009-01-01

344

IR spectroscopic analysis of the structure of a biospecific sorbent based on a polyethylene matrix  

NASA Astrophysics Data System (ADS)

We have used IR spectroscopy to study the structure of a biospecific sorbent based on a polyethylene matrix, modified by radiation grafting of acrylic acid with L-tryptophan methyl ester as the ligand. We show that grafted polyacrylic acid forms on polyethylene beads. We have established that chemical addition of the ligand to the modified polyethylene matrix occurs with participation of COOH groups of the polyacrylic acid and NH2 groups of the L-tryptophan methyl ester. We have observed that in the end product, strong hydrogen bonds are formed between the carbonyl groups of the ligand and the unreacted carboxyl groups of the grafted polyacrylic acid.

Korolenko, E. A.; Korolik, E. V.; Tretinnikov, O. N.; Fedorov, A. A.; Golubovich, V. P.

2010-09-01

345

Fracture of highly cross-linked all-polyethylene patella after total knee arthroplasty.  

PubMed

Recent advances in polyethylene fabrication have led to the introduction of highly cross-linked polyethylene tibial and patellar components for use in total knee arthroplasty (TKA) with the goal of reducing wear-related osteolysis. However, some reports suggest decreased mechanical strength as a result of the additional thermal and sterilization treatments in the manufacturing of implants. Complications related to the patella are among the most common causes of failure in TKA, but patellar component fracture is rare. The authors report a case of a highly cross-linked all-polyethylene patellar component that failed as a result of fracture in vivo in a patient 3 years after TKA. PMID:21446631

Hambright, Dustin S; Watters, Tyler Steven; Kaufman, Adam M; Lachiewicz, Paul F; Bolognesi, Michael P

2010-12-01

346

The Incidence of Acetabular Osteolysis in Young Patients With Conventional versus Highly Crosslinked Polyethylene  

Microsoft Academic Search

Background  Osteolysis is a major mode of hip implant failure. Previous literature has focused on the amount of polyethylene wear comparing\\u000a highly crosslinked polyethylene (HXPLE) with conventional liners but has not clarified the relative incidence of osteolysis\\u000a with these two liners.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We determined (1) the incidence of osteolysis in HXLPE versus conventional polyethylene (CPE), (2) the ability to detect and\\u000a evaluate

Nathan A. Mall; Ryan M. Nunley; Jin Jun Zhu; William J. Maloney; Robert L. Barrack; John C. Clohisy

2011-01-01

347

Protein patterning in polycarbonate microfluidic channels  

NASA Astrophysics Data System (ADS)

In this work protein patterning has been achieved within a polycarbonate microfluidic device. Channel structures were first coated with plasma polymerized allylamine (ALAPP) followed by the "cloud point" deposition of polyethylene oxide (PEO), a protein repellent molecule. Excimer laser micromachining was used to pattern the PEO to control protein localization. Subsequent removal of a sacrificial layer of polycarbonate resulted in the patterned polymer coating only in the channels of a simple fluidic device. Following a final diffusion bonding fabrication step the devices were filled with a buffer containing Streptavidin conjugated with fluorescein, and visualized under a confocal fluorescent microscope. This confirmed that protein adhesion occurred only in laser patterned areas. The ability to control protein adhesion in microfludic channels leads to the possibility of generating arrays of proteins or cells within polymer microfludics for cheap automated biosensors and synthesis systems.

Thomson, David A.; Hayes, Jason P.; Thissen, Helmut

2004-03-01

348

Factorial analyses of photopolymerizable thermoresponsive composite hydrogels for protein delivery  

Microsoft Academic Search

A smart protein delivery system for wound healing applications was developed using composite nanoparticle hydrogels that can release protein in a temperature-responsive manner. This system can also be formed in situ in the presence of ultraviolet light and Irgacure 2959 photoinitiator. The system consists of temperature-sensitive poly(N-isopropylacrylamide-co-acrylamide) (PNIPAM-AAm) nanoparticles embedded in a poly(ethylene glycol) diacrylate (PEGDA) matrix. A factorial analysis

Abhimanyu Sabnis; Aniket S. Wadajkar; Pranesh Aswath; Kytai T. Nguyen

2009-01-01

349

Visualisation and Analysis of Polyethylene Coextrusion Melt Flow  

NASA Astrophysics Data System (ADS)

Polymer melts experience complex, time variant, stress and deformation fields on their passage through fixed geometries in many conversion operations. Flow complexity is further increased in operations involving the co-joining of two or more melt streams where one confining boundary is moving and viscoelastic. Such a complex situation arises in coextrusion processes. This work covers experimental studies on polyethylene melt flows in complex coextrusion geometries with a view to understanding the stress fields involved and their effects on flow stability. A 30° coextrusion geometry is studied using two extrusion arrangements. In one arrangement a single extruder is used to feed a 'bifurcated' die design wherein the melt stream is split prior to, and rejoined after, a divider plate in the die. In the other design melt streams are delivered to, and converged at 30°, using two independent extruders. In a second die melt streams are brought together at 90°. In each die arrangement melt flow in the confluent region and die land to the die exit was observed through side windows of a visualisation cell. Velocity ratios of the two melt streams were varied and layer thickness ratios producing instability are determined for each melt for a variety of flow conditions. Stress and velocity fields in the coextrusion arrangements were quantified using stress birefringence and particle image velocimetry techniques. The study demonstrates conclusively that wave type interfacial instability occurred in the coextrusion geometries when the same low density polyethylene melt is used in each stream. This observation occurred at specific, repeatable, stream layer ratios in each die arrangement. The complex flows were numerical modelled using a modified Leonov model and Flow 2000™ software. There was reasonable agreement between modelled at experimentally determined stress fields. Modelling however provided far more detailed stress gradient information than could be resolved from the optical techniques. A total normal stress difference (TNSD) sign criterion was used to predict the critical layer ratio for the onset of the interfacial instability in one die arrangement and good agreement between theory and experiment has been obtained. The study conclusively demonstrates wave type interfacial instability in the coextrusion process is not caused by process perturbations potentially introduced by extruder screw rotation but is associated with process-history dependant differences in melt elasticity.

Martyn, Mike T.; Coates, Phil D.; Zatloukal, Martin

2009-07-01

350

The lexicon of polyethylene wear in artificial joints.  

PubMed

The analysis of wear on polyethylene components that have been retrieved after use in patients has provided invaluable understanding of how wear occurs in vivo, and how it may be minimized through improved materials and implant design. The great number of such studies that have been published over the past three decades has lead to an extensive vocabulary to describe the tribology of prosthetic joints. However, these also have led to some confusion, due to the occasional misuse of terms from classical tribology, along with the use of multiple terms to describe the same wear phenomenon, and vice versa. The author has proposed that our understanding of wear in artificial joints may be enhanced by recognizing that there are four general subject areas: Modes, Mechanisms, Damage and Debris. Wear Mode 1 occurs when the two bearing surfaces are articulating against each other in the manner intended by the implant designer. Mode 2 occurs when a bearing surface articulates against a non-bearing surface. Mode 3 occurs when third-body abrasive particles have become entrapped between the two bearing surfaces, and Mode 4 occurs when two non-bearing surfaces are wearing against each other. The least wear occurs in Mode 1, whereas severe wear typically occurs in Modes 2, 3 and 4. The classical wear mechanisms that apply to prosthetic joints include adhesion, abrasion and fatigue. These can occur in varying amounts in either of the four wear modes. As used in the literature for the past three decades, wear "damage" can best be defined as the change surface texture or morphology that is caused by the action of the wear mechanisms. Although a wide variety of terms have been used, an overview of the literature indicates that about eight terms have been sufficient to describe the types of damage that occur on retrieved polyethylene components, i.e., burnishing, abrasion, scratches, plastic deformation, cracks, pits, delamination, and embedded third bodies. The author suggests that, as far as possible, investigators endeavor to limit their descriptions of surface damage to these terms and, importantly, to clearly and consistently distinguish the classical wear mechanisms from the types of damage produced by those mechanisms. Wear debris refers to the billions of particles, some measuring in nanometers, that are generated by the wear mechanisms, and that initiate biological reactions, such as osteolysis, that may lead to the failure of the implant. As the methods for recovering wear debris from joint fluids and tissues are improved, investigators are using a growing number of terms to describe them. As with the types of damage, it will be important in the coming years to maximize clarity and minimize redundancy of the vocabulary in this important area of research. PMID:17706766

McKellop, Harry A

2007-12-01

351

1 Electrospun Polyethylene Oxide/Cellulose Nanocrystal Composite 2 Nanofibrous Mats with Homogeneous and Heterogeneous  

E-print Network

1 Electrospun Polyethylene Oxide/Cellulose Nanocrystal Composite 2 Nanofibrous Mats property, and excellent flexibility for 32 chemical/physical surface functionalization. Hence, electrospun extracellular matrix 39 (ECM) in terms of structure, chemical composition, and mechan- 40 ical properties.3

352

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

...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....

2014-04-01

353

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....

2011-04-01

354

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....

2012-04-01

355

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....

2013-04-01

356

The correlation between fusion defects and damage in tibial polyethylene bearings.  

PubMed

Recent reports of fatigue failures of polyethylene tibial and patellar components have led to investigation of the role of design and material properties in these failures. Earlier investigations, concluding that high contact stress designs suffered greater damage in service, could not account for some of the fatigue failures. The current study hypothesizes that this failure is related to variations in the material properties of the polyethylene due to incomplete consolidation of the powder during manufacture, resulting in fusion defects. Retrieved polyethylene components and samples of polyethylene stock were examined to gain insight into the relationship between fusion defects, component failure, material forming processes, and powder grade. Statistically significant correlations (p < 0.05) were observed between the extent of defects and cracking, delamination, total wear damage, and duration in vivo. These correlations indicate that components manufactured from material with fusion defects may be less resistant to fatigue than components formed of fully consolidated material. PMID:8119043

Wrona, M; Mayor, M B; Collier, J P; Jensen, R E

1994-02-01

357

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

358

Comparison of low-energy ? radiation effects in polyethylene and cellulose by molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

Using molecular dynamics simulations, we have compared the low-energy ? radiation effects in high density polyethylene and cellulose. We determined the threshold energy for creating defects as a function of the incident angle, for a carbon atom in polyethylene chain, and for one of the carbon atoms in cellulose chain. Our analysis shows that the damage threshold energy is in the both cases strongly dependent on the initial recoil direction and on average slightly higher for the carbon atoms in the polyethylene chain than for the target carbon atom in cellulose chain. Additionally we performed two sets of recoil event simulations on polyethylene sample, with 50 and 100 eV recoil energy, and compared the outcome with previously reported recoil event results for cellulose sample.

Polvi, Jussi; Nordlund, Kai

2014-05-01

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

In vitro simulation of contact fatigue damage found in ultra-high molecular weight polyethylene components  

E-print Network

manufacturing inventory. The rolling/sliding UHMWPE discs were machined from bar stock and either gamma, with significant additional comprises a polyethylene bearing disc which is contouredactivity in other countries [1

361

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

362

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

Federal Register 2010, 2011, 2012, 2013

...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

363

Designing a Hepatocellular Microenvironment with Protein Microarraying and Poly(ethylene glycol)  

E-print Network

hepatocytes and 3T3 fibroblasts. Collagen spots (ca. 170 µm in diameter) were printed onto amino-silane- and glutaraldehyde-modified glass slides. Groups of 15-20 hepatocytes attached to collagen regions in a highly, seeded onto the same surface, adhered and spread around arrays of hepatocyte islands creating

Revzin, Alexander

364

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

PubMed

Label-free heterogeneous phase detection critically depends on the properties of the interfacial layer. We have obtained high-density monomolecular poly(ethylene glycol) (PEG) layers by solvent-free coupling of homo-bifunctional PEGs (2,000 g/mol) at 75 degrees C to silica surfaces silanized with glycidyloxipropyltrimethoxysilane (GOPTS). Characterization by ellipsometry and contact angles revealed that PEG layers up to 3.4 ng/mm2 with low roughness and flexibility were obtained. Specific and non-specific binding at these PEG surfaces was monitored by reflectometric interference spectroscopy (RIfS). No significant non-specific adsorption upon incubation of 1 mg/ml ovalbumin was detectable (< 10 pg/mm2), and 150 pg/mm2 upon incubation of 10% calf serum, less than 10% of the amount adsorbed to the solely silanized surfaces. The terminal functional groups of the PEG layers were utilized to couple ligands and a protein. Specific protein interaction with these immobilized compounds was detected with saturation loadings in the range of protein monolayers (2-4 ng/mm2). The excellent functional properties, the high stability of the layers, the generic and practical coupling procedure and the versatility for immobilizing compounds of very different functionality make these PEG layers very attractive for application in label-free detection with silica or metal-oxide based transducers. PMID:11419642

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

2000-01-01

365

Effect of polyethylene glycol coating on Salmonella enteritidis in artificially contaminated eggs  

Microsoft Academic Search

This experimental infection study focuses on a specific Salmonella micro-organism commonly found inside hens’ eggs. It outlines the application of polyethylene glycol-based films on hens’ eggs and microbial growth introduced via transovarian contamination. Three molecular weights of polyethylene glycol (PEG) were studied: ranging from 1000 g\\/mol to 3000 g\\/mol. PEG coating ratios averaged a PEG film thickness of 0.014 ± 0.006 mm and

G. Goncagul; Y. Sahan; O. Gurbuz; A. Kara

2012-01-01

366

Evaluation of the effects of gamma irradiation on the mechanical properties of high density polyethylene  

Microsoft Academic Search

Mechanical tests following gamma irradiation and creep tests during irradiation have been conducted on high-density polyethylene (HDPE) to assess the adequacy of this material for use in high-integrity containers (HICs). These tests were motivated by experience in nuclear power plants in which polyethylene electrical insulation deteriorated more rapidly than expected due to radiation-induced oxidation. This suggested that HDPE HICs used

D. R. Dougherty; J. W. Adams; R. E. Barletta

1984-01-01

367

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

Microsoft Academic Search

A two-step enrichment procedure led to the isolation of a strain of Rhodococcus ruber (C208) that utilized polyethylene films as sole carbon source. In liquid culture, C208 formed a biofilm on the polyethylene surface and degraded up to 8% (gravimetrically) of the polyolefin within 30 days of incubation. The bacterial adhesion to hydrocarbon assay and the salt aggregation test both showed

Y. Hadar; A. Sivan

2004-01-01

368

Influence of clay exfoliation on the physical properties of montmorillonite\\/polyethylene composites  

Microsoft Academic Search

Melt compounding was used to prepare conventional composites of montmorillonite clay and polyethylene (PE) as well as nanocomposites of exfoliated montmorillonite platelets dispersed in a maleated polyethylene (PE-g-MAn) matrix. The extent of clay platelet exfoliation in the PE-g-MAn nanocomposites was confirmed by X-ray diffraction and resulted in a significant reduction of the degree of crystallinity and increased polymer crystallization rates.

T. G. Gopakumar; J. A. Lee; M. Kontopoulou; J. S. Parent

2002-01-01

369

Total Knee Arthroplasty With 4.4 mm of Tibial Polyethylene  

Microsoft Academic Search

Three hundred eighty-seven one-piece, 8-mm tibial components were implanted in 313 patients. All tibial prostheses were manufactured with 4.4 mm of polyethylene. From this group, 116 patients underwent simultaneous bilateral total knee arthroplasty with an 8-mm tibial component on one side and a tibial component with at least 6.4 mm of polyethylene on the other side. Follow-up averaged 11.8 years.

John B. Meding; Jennifer T. Wing; Merrill A. Ritter

2010-01-01

370

Photoencapsulation of chondrocytes in poly(ethylene oxide)-based semi-interpenetrating networks  

Microsoft Academic Search

A photopolymerizing hydrogel system provides an efficient method to encapsulate cells. The present work describes the in vitro analysis of bovine and ovine chondro- cytes encapsulated in a poly(ethylene oxide)-dimethacrylate and poly(ethylene glycol) semi-interpenetrating network us- ing a photopolymerization process. One day after encapsu- lation, (3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyl-2H- tetrazolium bromide) (MTT) and light microscopy showed chondrocyte survival and a dispersed cell population

J. Elisseeff; W. McIntosh; K. Anseth; S. Riley; P. Ragan; R. Langer

2000-01-01

371

Melt Production and Antimicrobial Efficiency of Low-Density Polyethylene (LDPE)Silver Nanocomposite Film  

Microsoft Academic Search

Colloidal silver nanoparticles with a size of 5.5?±?1.1 nm were prepared by chemical reduction using polyethylene glycol (PEG).\\u000a Silver nanoparticles were incorporated into low-density polyethylene (LDPE) by melt blending and subsequent hot pressing at\\u000a 140?°C to produce nanocomposite film with an average thickness of 0.7 mm. PEG was added at 5% weight of polymer as a compatibilizer\\u000a agent in order to prevent

Maryam Jokar; Russly Abdul Rahman; Nor Azowa Ibrahim; Luqman Chuah Abdullah; Chin Ping Tan

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

Electrical Conduction and Dielectric Relaxation in Polyethylene Terephthalate Succinate  

NASA Astrophysics Data System (ADS)

Electrical conduction and complex permittivity are examined in polyethylene terephthalate succinate, focusing on their relations to dielectric relaxation processes. Both the real and imaginary parts of complex permittivity, namely dielectric constant ?r' and dielectric loss factor ?r'', increase with a decrease in frequency, especially at high temperatures. They are both ascribed to the transport of ionic mobile carriers. Namely, the carrier transport forms conduction current that should contribute to ?r''. On this occasion, if charge exchange does not occur at the two electrodes, heterocharge layers should be formed before the electrodes. This should increase the charge density on the electrodes, thus contributing to ?r'. In addition to the increase in ?r' and ?r'' due to mobile ions, two relaxation processes, one due to micro-Brownian motion of dipoles and the other due to orientation and magnitude change of the dipole moment induced by two end groups in the polymer main chain, are observed. Corresponding to these two relaxation processes, two thermally stimulated discharge current (TSDC) peaks appear. The two TSDC peaks as well as the increment in ?r' and ?r'' become larger when the crystallinity of the sample decreases.

Kato, Fukutaro; Ohki, Yoshimichi

374

Nonisothermal crystallization kinetics of poly(ethylene terephthalate) nanocomposites.  

PubMed

This article reports the nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET) nanocomposites. The non-isothermal crystallization behaviors of PET and the nanocomposite samples are studied by differential scanning calorimetry (DSC). Various models, namely the Avrami method, the Ozawa method, and the combined Avrami-Ozawa method, are applied to describe the kinetics of the non-isothermal crystallization. The combined Avrami and Ozawa models proposed by Liu and Mo also fit with the experimental data. Different kinetic parameters determined from these models prove that in nanocomposite samples intercalated silicate particles are efficient to start crystallization earlier by nucleation, however, the crystal growth decrease in nanocomposites due to the intercalation of polymer chains in the silicate galleries. Polarized optical microscopy (POM) observations also support the DSC results. The activation energies for crystallization has been estimated on the basis of three models such as Augis-Bennett, Kissinger and Takhor methods follow the trend PET/2C20A < PET/1.3C20A < PET, indicating incorporation of organoclay enhance the crystallization by offering large surface area. PMID:18572582

Bandyopadhyay, Jayita; Ray, Suprakas Sinha; Bousmina, Mosto

2008-04-01

375

Mechanisms of lithium transport in amorphous polyethylene oxide.  

PubMed

We report calculations using a previously reported model of lithium perchlorate in polyethylene oxide in order to understand the mechanism of lithium transport in these systems. Using an algorithm suggested by Voter, we find results for the diffusion rate which are quite close to experimental values. By analysis of the individual events in which large lithium motions occur during short times, we find that no single type of rearrangement of the lithium environment characterizes these events. We estimate the free energies of the lithium ion as a function of position during these events by calculation of potentials of mean force and thus derive an approximate map of the free energy as a function of lithium position during these events. The results are consistent with a Marcus-like picture in which the system slowly climbs a free energy barrier dominated by rearrangement of the polymer around the lithium ions, after which the lithium moves very quickly to a new position. Reducing the torsion forces in the model causes the diffusion rates to increase. PMID:15740341

Duan, Yuhua; Halley, J W; Curtiss, Larry; Redfern, Paul

2005-02-01

376

Degradation of polyethylene glycol by Fenton reaction: a comparative study.  

PubMed

Photochemical advanced oxidation processes (AOPs) utilising different Fenton systems were investigated in laboratory-scale experiments for the degradation of polyethylene glycol (PEG). The results of the study showed that the degradation rate of PEG was strongly accelerated by the homogeneous system, and this proved to be advantageous in comparison to the heterogeneous system. Between Fenton and photo-Fenton heterogeneous systems, the photo-Fenton process reached the highest removal rate of the organic compound, due to the enhanced reduction efficiency of Fe(III) to Fe(II) under UV-irradiation. The oxidation rate in the heterogeneous system was investigated using varying different parameters, such as the pH value, the concentration of hydrogen peroxide and the amount of Fe(OH)3 as the catalyst. For the homogeneous Fenton system the rate of degradation is significantly higher. At the same time of operation the elimination rates can be found to be 30% over the rates of the heterogeneous system. Optimising the typical influence parameters mentioned before, a degradation of about 93% of PEG can be achieved by using the homogeneous Fenton system. PMID:17674831

Haseneder, R; Fdez-Navamuel, B; Härtel, G

2007-01-01

377

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

378

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

379

On the effect of nanosilica on a polyethylene system  

NASA Astrophysics Data System (ADS)

The topic of polymer nanocomposites remains an active area of research in terms of its potential applications in dielectric and electrical insulation applications. Although more than a decade has passed since Lewis first considered these systems as dielectric materials, the precise effects of incorporating nanofillers into different polymers are yet to be confirmed. While this strategy is generally regarded as a promising means for tailoring insulation performance, the consequences of adding a nanofiller to an insulating matrix are not always positive; for example, where dispersion is poor the breakdown strength can be adversely affected. This paper reports on an investigation into a nanofilled polyethylene system prepared via a solution blending route. Specifically, in this study, the effect of processing and nanofiller dispersion on the structure and physical properties of the nanocomposites that forms was considered. The crystallization behaviour and morphology of the differently processed materials have been evaluated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). The influence of nanofiller dispersion on breakdown behaviour is also described.

Lau, K. Y.; Vaughan, A. S.; Chen, G.; Hosier, I. L.

2011-08-01

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

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

382

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

383

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

384

Cyclic steady state stress-strain behavior of UHMW polyethylene.  

PubMed

To increase the long-term performance of total joint replacements, finite element analyses of ultra high molecular weight polyethylene (UHMWPE) components have been conducted to predict the effect of load on the stress and strain distributions occurring on and within these components. Early models incorporated the monotonic behavior of UHMWPE without considering the unloading and cyclic loading behavior. However, UHMWPE components undergo cyclic loading during use and at least two wear damage modes (pitting and delamination) are thought to be associated with the fatigue fracture properties of UHMWPE. The objective of this study was to examine the fully reversed uniaxial tension/compression cyclic steady state stress-strain behavior of UHMWPE as a first step towards developing a cyclic constitutive relationship for UHMWPE. The hypothesis that cycling results in a permanent change in the stress-strain relationship, that is, that the cyclic steady state represents a new cyclically stabilized state, was examined. It was found that, like other ductile polymers, UHMWPE substantially cyclically softens under fully reversed uniaxial straining. More cyclic softening occurred in tension than in compression. Furthermore, cyclic steady state was attained, but not cyclic stability. It is suggested that it may be more appropriate to base a material constitutive relationship for UHMWPE for finite element analyses of components upon a cyclically modified stress-strain relationship. PMID:10966018

Krzypow, D J; Rimnac, C M

2000-10-01

385

Delamination toughness of ultra high molecular weight polyethylene (UHMWPE) composites  

NASA Astrophysics Data System (ADS)

Ultra high molecular weight polyethylene (UHMWPE) fibre reinforced composites are an important group of material for armours solutions, where their unique combination of properties could be utilized. A commonly observed failure mode in this kind of unidirectional laminated composites under impact ballistic is delamination between the composite layers. In the present study, an investigation on the delamination toughness behaviour exhibited by UHMWPE composites laminated was made. The interlaminar Mode II critical strain energy release rates of (UHMWPE) fibre reinforced composites were characterized using the End Notch Flexural (ENF) test. Critical strain energy release rate was obtained from the load - deflection test data using the beam theory expression. It was found that the energy release rate of the composite exhibited a very low value of around 60J/m2 using a moulding pressure of approximately 1200 psi. In order to analyse the delamination resistance of composite, the effects of changing the manufacture process variables and the use of a thermoplastic adhesive film in the composites were investigated. The composite laminates were produced by hot compressing moulding using a film-stacking procedure. It was found that the damage resistance of the UHMWPE composite was influenced by the manufacture method, which affects the Mode II interlaminar fracture toughness and the ballistic response of composites.

Porras, A.; Tellez, J.; Casas-Rodriguez, J. P.

2012-08-01

386

Property changes of UHMW polyethylene hip cup endoprostheses during implantation.  

PubMed

In this study it is demonstrated that the combined chemical and mechanical influences of the implant situation cause property changes of ultra-high-molecular-weight polyethylene (UHMW PE) hip joint cups. Nearly 30 out of 48 loosened cups, retrieved 3 weeks to 11 years after implantation, were investigated. Density measurements show a density increase with implantation time and a dependence of these changes from implant position and loading conditions. The rate of extractable constituents also increases with course of time. An increased in vivo conditioned oxidation of the UHMW PE can be demonstrated by infrared (IR) spectrometry. The density increase can be explained by post-crystallization, which is the result of oxidative chain scission. This leads to a reduction of the average molecular weight of the PE and to an increased extractability of constituents. Since these changes have been recognized as the reasons for aging and failing of UHMW PE, the methods of material characterization used in this study for retrieved implants will help to develop suitable in vitro testing and simulating methods. They are the prerequisite for the necessary improvements of the material properties of UHMW PE. PMID:6544798

Eyerer, P; Ke, Y C

1984-01-01

387

Ultra High Molecular Weight Polyethylene: Mechanics, Morphology, and Clinical Behavior  

PubMed Central

Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been used for over four decades as a bearing surface in total joint replacements. The mechanical properties and wear properties of UHMWPE are of interest with respect to the in vivo performance of UHMWPE joint replacement components. The mechanical properties of the polymer are dependent on both its crystalline and amorphous phases. Altering either phase (i.e., changing overall crystallinity, crystalline morphology, or crosslinking the amorphous phase) can affect the mechanical behavior of the material. There is also evidence that the morphology of UHMWPE, and, hence, its mechanical properties evolve with loading. UHMWPE has also been shown to be susceptible to oxidative degradation following gamma radiation sterilization with subsequent loss of mechanical properties. Contemporary UHMWPE sterilization methods have been developed to reduce or eliminate oxidative degradation. Also, crosslinking of UHMWPE has been pursued to improve the wear resistance of UHMWPE joint components. The 1st generation of highly crosslinked UHMWPEs have resulted in clinically reduced wear; however, the mechanical properties of these materials, such as ductility and fracture toughness, are reduced when compared to the virgin material. Therefore, a 2nd generation of highly crosslinked UHMWPEs are being introduced to preserve the wear resistance of the 1st generation while also seeking to provide oxidative stability and improved mechanical properties. PMID:19627849

Sobieraj, MC; Rimnac, CM

2013-01-01

388

Polyethylene glycol improves phenol removal by immobilized turnip peroxidase.  

PubMed

Purified peroxidase from turnip (Brassica napus L. var. esculenta D.C.) was immobilized by entrapment in spheres of calcium alginate and by covalent binding to Affi-Gel 10. Both immobilized Turnip peroxidase (TP) preparations were assayed for the detoxification of a synthetic phenolic solution and a real wastewater effluent from a local paints factory. The effectiveness of phenolic compounds (PC's) removal by oxidative polymerization was evaluated using batch and recycling processes, and in the presence and in the absence of polyethylene glycol (PEG). The presence of PEG enhances the operative TP stability. In addition, reaction times were reduced from 3h to 10 min, and more effective phenol removals were achieved when PEG was added. TP was able to perform 15 reaction cycles with a real industrial effluent showing PC's removals >90% PC's during the first 10 reaction cycles. High PC's removal efficiencies (>95%) were obtained using both immobilized preparations at PC's concentrations <1.2mM. Higher PC's concentrations decreased the removal efficiency to 90% with both preparations after the first reaction cycle, probably due to substrate inhibition. On the other hand, immobilized TP showed increased thermal stability when compared with free TP. A large-scale enzymatic process for industrial effluent treatment is expected to be developed with immobilized TP that could be stable enough to make the process economically feasible. PMID:18502120

Quintanilla-Guerrero, F; Duarte-Vázquez, M A; García-Almendarez, B E; Tinoco, R; Vazquez-Duhalt, R; Regalado, C

2008-12-01

389

Patterning polyethylene oligomers on carbon nanotubes using physical vapor deposition.  

PubMed

Periodic patterning on one-dimensional (1D) carbon nanotubes (CNTs) is of great interest from both scientific and technological points of view. In this letter, we report using a facile physical vapor deposition method to achieve periodic polyethylene (PE) oligomer patterning on individual CNTs. Upon heating under vacuum, PE degraded into oligomers and crystallized into rod-shaped single crystals. These PE rods periodically decorate on CNTs with their long axes perpendicular to the CNT axes. The formation mechanism was attributed to "soft epitaxy" growth of PE oligomer crystals on CNTs. Both SWNTs and MWNTs were decorated successfully with PE rods. The intermediate state of this hybrid structure, MWNTs absorbed with a thin layer of PE, was captured successfully by depositing PE vapor on MWNTs detached from the solid substrate, and was observed using high-resolution transmission electron microscopy. Furthermore, this hybrid structure formation depends critically on CNT surface chemistry: alkane-modification of the MWNT surface prohibited the PE single-crystal growth on the CNTs. We anticipate that this work could open a gateway for creating complex CNT-based nanoarchitectures for nanodevice applications. PMID:16683841

Li, Lingyu; Yang, Yao; Yang, Guoliang; Chen, Xuming; Hsiao, Benjamin S; Chu, Benjamin; Spanier, Jonathan E; Li, Christopher Y

2006-05-01

390

[Polyethylene wear in periprosthetic tissue of failed cemented total hip arthroplasties].  

PubMed

To elucidate the relationship between polyethylene wear and loosening of total hip arthroplasty, we observed grossly the periprosthetic tissues, polyethylene wear debris and polyethylene acetabular liners retrieved from 6 failed cemented total hip arthroplasties during revisions by means of polar light miscroscope and scanning electron microscope. The production mechanism of polyethylene wear debris from acetabular liner was analyzed together with its role in periprosthetic fibrosis and prosthetic loosening. Results showed the abrasion of two bearing surfaces interposed with third-body particles as called three-body abrasion was the main model of polyethylene wear. All inner surfaces of the liners appeared clear abrasive scratches and big flat debris were found in most of the retrieved tissues. Histologically, the wear debris of various sizes embraced by 1 or several polynuclear giant cells that were found not only great in number but also active in function. The implication is that three body abrasion is the key factor of high rate wear of the polyethylene liner and that polynuclear giant cell is acting as an important cellular component leading to the prosthetic loosening. PMID:10678063

Wang, Y; Dai, K; Zhang, P

1997-08-01

391

Protein-to-film adhesion as examined by amino analysis of protein binding to three different packaging films.  

PubMed

A weak protein solution extracted from chicken breast meat was exposed to three types of packaging materials. The crude myofibrillar protein solution (12.0 mg protein/mL buffer) was suspended in a 0.6M NaCl/NaPO4 buffer, then placed in bags made from either polyethylene (nonbinding film), a nylon blend (binding film), or Surlyn (binding film). Two separate experiments were conducted to determine the effects of exposure time at a constant temperature and varying endpoint exposure temperatures on the amount of bound protein by amino acid analysis. Bound amino acids were quantified and grouped by class based on functional side group. It was theorized that differences in the amount of bound amino acid class was linked to the mechanism by which the meat-to-film binding occurs. The protein solution was sealed in bags and held in a water bath for 5 s, 20 min, 40 min, and 60 min at 25.8 C for the timed experiment and heated from 25.8 C to 40, 55, 70, and 80 C for the temperature experiment. Protein adhesion occurred due to exposure of the solution to all films at 25.8 C. Greater protein adhesion was found in the two binding films than in the nonbinding film after 60 min of exposure. Heating the protein solution increased adhesion for the Surlyn film and showed a clear delineation in the degree of binding between the film types. Surlyn bound the most protein, followed by the nylon blend and then polyethylene. Bound protein increased in the Surlyn film with heating to 80 C, whereas the polyethylene did not show an increase in the amount of bound protein. Increases in binding observed between 55 and 80 C for Surlyn may be associated with transitional and conformational changes in muscle proteins that affect the adhesion of meat to the film surface. PMID:9603364

Clardy, C B; Han, I Y; Acton, J C; Wardlaw, F B; Bridges, W B; Dawson, P L

1998-05-01

392

A thermosensitive hydrogel based on biodegradable amphiphilic poly(ethylene glycol) polycaprolactone poly(ethylene glycol) block copolymers  

NASA Astrophysics Data System (ADS)

A series of low molecular weight poly(ethylene glycol)-polycaprolactone-poly(ethylene glycol) (PEG-PCL-PEG) biodegradable block copolymers were successfully synthesized using isophorone diisocyanate (IPDI) as the coupling agent, and were characterized using 1H NMR and Fourier transform infrared spectroscopy. The aqueous solutions of the PEG-PCL-PEG copolymers displayed a special thermosensitive gel-sol transition when the concentration was above the corresponding critical gel concentration. Gel-sol phase diagrams were recorded using the test-tube-inversion method; they depended on the hydrophilic/hydrophobic balance in the macromolecular structure, as well as some other factors, including the heating history, volume, and the ageing time of the copolymer aqueous solutions and dissolution temperature of the copolymers. As a result, the gel-sol transition temperature range could be altered, which might be very useful for application in injectable drug delivery systems. This work was financially supported by the Chinese Key Basic Research Program (2004CB518800 and 2004CB518807), and the Sichuan Key Project of Science and Technology (06(05SG022-021-02)).

Gong, Chang Yang; Qian, Zhi Yong; Liu, Cai Bing; Juan Huang, Mei; Gu, Ying Chun; Wen, Yan Jun; Kan, Bing; Wang, Ke; Dai, Mei; Li, Xing Yi; Gou, Ma Ling; Tu, Ming Jing; Wei, Yu Quan

2007-06-01

393

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

394

Multicolor upconversion nanoparticles for protein conjugation.  

PubMed

We describe the preparation of monodisperse, lanthanide-doped hexagonal-phase NaYF4 upconverting luminescent nanoparticles for protein conjugation. Their core was coated with a silica shell which then was modified with a poly(ethylene glycol) spacer and N-hydroxysuccinimide ester groups. The nanoparticles were characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and dynamic light scattering. The N-hydroxysuccinimide ester functionalization renders them highly reactive towards amine nucleophiles (e.g., proteins). We show that such particles can be conjugated to proteins. The protein-reactive UCLNPs and their conjugates to streptavidin and bovine serum albumin display multicolor emissions upon 980-nm continuous wave laser excitation. Surface plasmon resonance studies were carried out to prove bioconjugation and to compare the affinity of the particles for proteins immobilized on a thin gold film. PMID:23606910

Wilhelm, Stefan; Hirsch, Thomas; Patterson, Wendy M; Scheucher, Elisabeth; Mayr, Torsten; Wolfbeis, Otto S

2013-01-01

395

Multicolor Upconversion Nanoparticles for Protein Conjugation  

PubMed Central

We describe the preparation of monodisperse, lanthanide-doped hexagonal-phase NaYF4 upconverting luminescent nanoparticles for protein conjugation. Their core was coated with a silica shell which then was modified with a poly(ethylene glycol) spacer and N-hydroxysuccinimide ester groups. The nanoparticles were characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and dynamic light scattering. The N-hydroxysuccinimide ester functionalization renders them highly reactive towards amine nucleophiles (e.g., proteins). We show that such particles can be conjugated to proteins. The protein-reactive UCLNPs and their conjugates to streptavidin and bovine serum albumin display multicolor emissions upon 980-nm continuous wave laser excitation. Surface plasmon resonance studies were carried out to prove bioconjugation and to compare the affinity of the particles for proteins immobilized on a thin gold film. PMID:23606910

Wilhelm, Stefan; Hirsch, Thomas; Patterson, Wendy M.; Scheucher, Elisabeth; Mayr, Torsten; Wolfbeis, Otto S.

2013-01-01

396

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

397

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

398

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Boric acid (H3BO3), mixed esters with polyethylene...Chemical Substances § 721.1729 Boric acid (H3 BO3 ), mixed esters with...chemical substance identified as boric acid (H3 BO3 ), mixed...

2012-07-01

399

40 CFR 721.1729 - Boric acid (H3BO3), mixed esters with polyethylene glycol mono-Bu ether and polyethylene glycol...  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Boric acid (H3BO3), mixed esters with polyethylene...Chemical Substances § 721.1729 Boric acid (H3 BO3 ), mixed esters with...chemical substance identified as boric acid (H3 BO3 ), mixed...

2013-07-01

400

Histological characteristics and ultrastructure of polyethylene terephthalate LARS ligament after the reconstruction of anterior cruciate ligament in rabbits  

PubMed Central

Polyethylene terephthalate LARS ligament were the remnant of LARS ligament used for repairing posterior cruciate ligament obtained from operation. We want to study histological characteristics and ultrastructure of polyethylene terephthalate LARS ligament after the reconstruction of anterior cruciate ligament in rabbits. Therefore, we replaced the original ACL with polyethylene terephthalate LARS ligament which was covering with the remnant of ACL in 9 rabbits (L-LARS group), while just only polyethylene terephthalate LARS ligament were transplanted in 3 rabbits (LARS group) with the remnant of ACL. Compared with group LARS, inflammatory cell reaction and foreign body reaction were more significant in group L-LARS. Moreover, electron microscopy investigation showed the tissue near LARS fibers was highly cellular with a matrix of thin collagen fibrils (50-100 nm) in group L-LARS. These above findings suggest the polyethylene terephthalate LARS ligament possess the high biocompatibility, which contributes to the polyethylene terephthalate LARS covered with recipient connective tissues. PMID:25356104

Yu, Shao-Bin; Yang, Rong-Hua; Zuo, Zhong-Nan; Dong, Qi-Rong

2014-01-01

401

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

402

Surface pre-treatment for barrier coatings on polyethylene terephthalate  

NASA Astrophysics Data System (ADS)

Polymers have favourable properties such as light weight, flexibility and transparency. Consequently, this makes them suitable for food packaging, organic light-emitting diodes and flexible solar cells. Nonetheless, raw plastics do not possess sufficient barrier functionality against oxygen and water vapour, which is of paramount importance for most applications. A widespread solution is to deposit thin silicon oxide layers using plasma processes. However, silicon oxide layers do not always fulfil the requirements concerning adhesion and barrier performance when deposited on films. Thus, plasma pre-treatment is often necessary. To analyse the influence of a plasma-based pre-treatment on barrier performance, different plasma pre-treatments on three reactor setups were applied to a very smooth polyethylene terephthalate film before depositing a silicon oxide barrier layer. In this paper, the influence of oxygen and argon plasma pre-treatments towards the barrier performance is discussed examining the chemical and topological change of the film. It was observed that a short one-to-ten-second plasma treatment can reduce the oxygen transmission rate by a factor of five. The surface chemistry and the surface topography change significantly for these short treatment times, leading to an increased surface energy. The surface roughness rises slowly due to the development of small spots in the nanometre range. For very long treatment times, surface roughness of the order of the barrier layer's thickness results in a complete loss of barrier properties. During plasma pre-treatment, the trade-off between surface activation and roughening of the surface has to be carefully considered.

Bahre, H.; Bahroun, K.; Behm, H.; Steves, S.; Awakowicz, P.; Böke, M.; Hopmann, Ch; Winter, J.

2013-02-01

403

High molecular weight polyethylene nanospheres: synthesis physical and mechanical properties.  

PubMed

The high molecular weight (MW) polyethylene (PE) particles of particle size varied from macro to micron to nanometer were synthesized by Grignard reagent. The microscopy analysis (scanning electron microscope, SEM; transmission electron microscope, TEM; and atomic force microscope, AFM) shows the spherical shape of PE particles. The effects of particle size, varies from macro to nanometer scale on crystal structure, crystallinity (chic), glass transition temperature (Tg), melting temperature (Tm), surface roughness and mechanical properties were studied. Differential scanning calorimetry (DSC) experiments show that the nanoparticles of PE are highly crystalline (chic approximately equal 72%). The crystal length of PE nanoparticles is found to be approximately 14 A. Although the Gibbs-Thomson equation is explained the depression of melting temperature (DeltaTm) by 5 degrees C, the impervious results of Tg are still not fully understood. The low roughness value (2 A) proves the presence of "atomic-scale-chain" folding at the surface of PE nanoparticles. A novel protocol is developed, and the elastic modulus of individual nanospherical PE particles is computed from 'force-distance' mapping curves of AFM. Hemispherical tungsten (W) tip was fabricated from focused ion beam and used as an indenter to measure the mechanical properties. It is found that the nano sized PE particles have higher elastic modulus (E = 1.2-1.4 GPa) compared to the bulk or macro sized PE (E = 0.6-0.7 GPa). The results corroborate the robustness of our experiments, since, the analogous results for macro sized particles match well with the literature. PMID:18681057

Paik, Pradip; Kar, Kamal K

2008-06-01

404

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

405

Radiation-induced grafting of acrylic acid onto polyethylene filaments  

NASA Astrophysics Data System (ADS)

Radiation-induced grafting of acrylic acid onto high density polyethylene (PE) filaments was carried out in order to raise softening temperature and impart flame retardance and hydrophilic properties. Mutual ?-irradiation method was employed for the grafting in a mixture of acrylic acid (AA), ethylene dichloride and water containing a small amount of ferrous ammonium sulfate. The rate of grafting was very low at room temperature. On the other hand, large percent grafts were obtained when the grafting was performed at an elevated temperature. Activation energy for the initial rate of grafting was found to be 17 {kcal}/{mol} between 20 and 60°C and 10 {kcal}/{mol} between 60 and 80°C. Original PE filament begins to shrink at 70°C, show maximum shrinkage of 50% at 130°C and then breaks off at 136°C. When a 34% AA graft is converted to metallic salt such as sodium and calcium, the graft filament retains its filament form even above 300°C and gives maximum shrinkage of 15%. Burning tests by a wire-netting basket method indicate that graft filaments and its metallic salts do not form melting drops upon burning and are self-extinguishing. Original PE filament shows no moisture absorption, however, that of AA-grafted PE increases with increasing graft percent. The sodium salt of 15% graft shows the same level of moisture regain as cotton. The AA-grafted PE filament and its metallic salts can be dyed with cationic dyes even at 1% graft. Tensile properties of PE filament is impaired neither by grafting nor by conversion to metallic salts.

Kaji, K.; Okada, T.; Sakurada, I.

406

GE Healthcare Data file 28-9267-48 AA Protein sample preparation  

E-print Network

polypropylene. Special column and plate frits protect the medium from running dry during use. The main% > 85% > 90% > 90% > 90% Plate/column material polypropylene and polyethylene polypropylene and polyethylene polypropylene and polyethylene polypropylene and polyethylene polypropylene and polyethylene

Lebendiker, Mario

407

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

408

Self-assembly of silanated poly(ethylene glycol) on silicon and glass surfaces for improved haemocompatibility  

NASA Astrophysics Data System (ADS)

Surface immobilization of poly(ethylene glycol) (PEG) is an effective method to produce a material surface with protein repulsive property. This property could be made permanent by using covalent grafting of the PEG molecules onto material surfaces. In this study, self-assembled monolayers (SAMs) of PEG on silicon-containing materials (silicon chip and glassplate) were obtained through a one-step coating procedure of one kind of silanated PEG molecules made through the reaction between monomethoxy PEG and 3-isocyanatopropyltriethoxysilane. Atomic force microscopy (AFM) and water static contact angle measurement were employed to investigate the surface topography and wettability of the PEGylated material surfaces. The changes in the topography and the water contact angle of the surfaces with time of incubation in PBS solution were also measured. The results revealed that stable and uniform self-assembled monolayers of PEG could be formed on silicon or glass surfaces by simply soaking the substrates in the solution of silanated PEGs. The covalent coupling of PEGs to the substrates was also confirmed. In order to evaluate the stability of the SAMs, blood compatibility of the modified glassplate surface was evaluated by measuring full blood activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT), as well as by scanning electron microscopy (SEM) analysis of the appearance of adherence and denaturation of blood platelets onto the glassplate. The silanated PEGs were shown to have good effect on the protein-repulsion as well as haemocompatibility of the substrates.

Guo, Zhang; Meng, Sheng; Zhong, Wei; Du, Qiangguo; Chou, Laisheng L.

2009-05-01

409

Layer by layer assembly of a biocatalytic packaging film: lactase covalently bound to low-density polyethylene.  

PubMed

Active packaging is utilized to overcome limitations of traditional processing to enhance the health, safety, economics, and shelf life of foods. Active packaging employs active components to interact with food constituents to give a desired effect. Herein we describe the development of an active package in which lactase is covalently attached to low-density polyethylene (LDPE) for in-package production of lactose-free dairy products. The specific goal of this work is to increase the total protein content loading onto LDPE using layer by layer (LbL) deposition, alternating polyethylenimine, glutaraldehyde (GL), and lactase, to enhance the overall activity of covalently attached lactase. The films were successfully oxidized via ultraviolet light, functionalized with polyethylenimine and glutaraldehyde, and layered with immobilized purified lactase. The total protein content increased with each additional layer of conjugated lactase, the 5-layer sample reaching up to 1.3 ?g/cm2 . However, the increase in total protein did not lend to an increase in overall lactase activity. Calculated apparent Km indicated the affinity of immobilized lactase to substrate remains unchanged when compared to free lactase. Calculated apparent turnover numbers (kcat ) showed with each layer of attached lactase, a decrease in substrate turnover was experienced when compared to free lactase; with a decrease from 128.43 to 4.76 s(-1) for a 5-layer conjugation. Our results indicate that while LbL attachment of lactase to LDPE successfully increases total protein mass of the bulk material, the adverse impact in enzyme efficiency may limit the application of LbL immobilization chemistry for bioactive packaging use. PMID:23647496

Wong, Dana E; Talbert, Joey N; Goddard, Julie M

2013-06-01

410

A study of gamma-irradiated polyethylenes by temperature modulated differential scanning calorimetry  

NASA Astrophysics Data System (ADS)

Various polyethylenes (PEs) and the effects of high-energy radiation on their structures were widely studied in the past using conventional Differential Scanning Calorimetry (DSC) measurements. In this work, we used the Temperature Modulated Differential Scanning Calorimetry (TMDSC) technique in order to obtain more information about the influence of the initial structural differences and gamma radiation on the evolution in structure and thermal properties of different polyethylenes. For this reason, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) samples were exposed to gamma radiation, in air, to a wide range of absorbed doses (up to 2400 kGy). The separation of the total heat flow TMDSC signal into a reversing and non-reversing part enabled us to observe the low-temperature enthalpy relaxation (related to the existence of the "rigid amorphous phase") and recrystallisation processes, as well as to follow their radiation-induced evolution and/or that of melting in a more revealing manner compared to the case of the conventional DSC. Consequently, our results indicate that TMDSC could improve the understanding of radiation-induced effects in polymers.

Galovic, S.; Secerov, B.; Trifunovic, S.; Milicevic, D.; Suljovrujic, E.

2012-09-01

411

Manipulating interactions between functional colloidal particles and polyethylene surfaces using interfacial engineering.  

PubMed

The purpose of this study was to examine the interaction between lipid droplets and polyethylene surfaces, representative of those commonly used in food packaging. Lipid droplets with various surface charges were prepared by homogenizing corn oil and water in the presence of surfactants with different electrical characteristics: non-ionic (Tween 80, T80), cationic (lauric arginate, LAE), and/or anionic (sodium dodecyl sulfate, SDS). The ionic properties of polyethylene surfaces were modified by UV-treatment. Stable emulsions containing small droplets (d<200 nm) with nearly neutral (T80), cationic (T80: LAE), and anionic (T80: SDS) charges were prepared by adding different levels of the ionic surfactants to Tween 80 stabilized emulsions. Scanning electronic microscopy (SEM), confocal fluorescence microscopy, and ATR-FTIR showed that the number of droplets attached to the polyethylene surfaces depended on the droplet charge and the polyethylene surface characteristics. The greatest degree of droplet adsorption was observed for the cationic droplets to the UV-ozone treated polyethylene surfaces, which was attributed to electrostatic attraction. These results are important for understanding the behavior of encapsulated lipophilic components in food containers. PMID:21555134

Ziani, Khalid; Barish, Jeffrey A; McClements, David Julian; Goddard, Julie M

2011-08-01

412

[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

413

Oxidation and Wear of 100-Mrad Cross-linked Polyethylene Shelf-aged for 30 Years  

PubMed Central

Some previous studies suggest that aging influences wear and oxidatively degraded nonsterilized ultra-high-molecular-weight polyethylene (UHMWPE) exhibits decreased wear resistance. We therefore asked whether shelf-aging storage conditions influenced degradation and wear resistance of gamma-irradiated UHMWPE. We examined oxidation and wear of 100-Mrad gamma-irradiated UHMWPE (100-Mrad polyethylene) cups shelf-aged for 30 years without (n = 2) or with (n = 2) packages. The oxidation index of the unpackaged 100-Mrad polyethylene surface (4) was higher than that of the packaged one (2.7). The packaged 100-Mrad polyethylene cup exhibited a high wear resistance with a steady wear rate of 0.5 mg/106 cycles. In contrast, the unpackaged 100-Mrad polyethylene exhibited an extremely high initial wear rate of 187.9 mg/106 cycles over the first 0.25 × 106 cycles with a subsequently reduced wear rate of 5 mg/106 cycles after 5 × 106 cycles. Packaging over long periods inhibits surface oxidation and maintains the wear resistance of gamma-irradiated UHMWPE cups. PMID:18196416

Oonishi, Hironobu; Kim, Sok Chol; Oonishi, Hiroyuki; Kyomoto, Masayuki

2008-01-01

414

Polyethylene encapsulation of single-shell tank low-level wastes. Annual progress report  

SciTech Connect

This report describes work supported by the UST-ID, conducted at Brookhaven National Laboratory I (BNL), to develop and demonstrate a polyethylene waste encapsulation process for low-level radioactive (LLW) and hazardous mixed wastes (HMW) stored in underground tanks. During FY 1992, studies were completed on the effects of elevated temperature on waste form integrity, strength and leachability. No changes in waste form integrity or compressive yield strength were detected after storing polyethylene waste forms containing 50, 60 and 70 wt% sodium nitrate at 70{degree}C for 3 months. Leaching of polyethylene waste forms with similar nitrate salt loadings at temperatures up to 70{degree}C resulted in slight increases in leachability (< a factor of 2), compared with leaching at ambient temperatures. Leaching of sodium nitrate from polyethylene waste forms was diffusion-controlled, enabling extrapolation of laboratory leach data to full-scale waste forms over long time periods. Full-scale polyethylene waste forms containing 50 to 70 wt% nitrate salt could be expected to leach a total of 5% to 17% of the original contaminant source term after 300 years of leaching under worst-case (70{degree}C, fully saturated) conditions. This is about 25 to 75 times lower leachability than conventional cement grout waste forms containing a maximum of 20 wt% nitrate salts.

Kalb, P.D.; Fuhrmann, M.; Cassidy, J.; Colombo, P.; Franz, E.M.; Fuhrmann, M.; Heiser, J. III; Kalb, P.D.; Klages, J.; Pietrzak, R.

1992-09-01

415

Polyethylene encapsulation of single-shell tank low-level wastes  

SciTech Connect

This report describes work supported by the UST-ID, conducted at Brookhaven National Laboratory I (BNL), to develop and demonstrate a polyethylene waste encapsulation process for low-level radioactive (LLW) and hazardous mixed wastes (HMW) stored in underground tanks. During FY 1992, studies were completed on the effects of elevated temperature on waste form integrity, strength and leachability. No changes in waste form integrity or compressive yield strength were detected after storing polyethylene waste forms containing 50, 60 and 70 wt% sodium nitrate at 70[degree]C for 3 months. Leaching of polyethylene waste forms with similar nitrate salt loadings at temperatures up to 70[degree]C resulted in slight increases in leachability (< a factor of 2), compared with leaching at ambient temperatures. Leaching of sodium nitrate from polyethylene waste forms was diffusion-controlled, enabling extrapolation of laboratory leach data to full-scale waste forms over long time periods. Full-scale polyethylene waste forms containing 50 to 70 wt% nitrate salt could be expected to leach a total of 5% to 17% of the original contaminant source term after 300 years of leaching under worst-case (70[degree]C, fully saturated) conditions. This is about 25 to 75 times lower leachability than conventional cement grout waste forms containing a maximum of 20 wt% nitrate salts.

Kalb, P.D.; Fuhrmann, M.; Cassidy, J.; Colombo, P.; Franz, E.M.; Fuhrmann, M.; Heiser, J. III; Kalb, P.D.; Klages, J.; Pietrzak, R.

1992-09-01

416

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

417

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

418

Dose effect in gamma-irradiated polyethylene studied by positron annihilation lifetime technique  

NASA Astrophysics Data System (ADS)

Commercial high-density polyethylene (HDPE) samples were irradiated by ?-rays with doses ranging from 10 to 200 kGy. Positron annihilation lifetime measurements were performed to study the effect of ?-radiation on the structure of polyethylene. The lifetime ?3, associated with the pick-off process, in which the positron in o-Ps annihilates an electron from the surrounding material, and its intensity I3 are measured as a function of ?-dose. It can be concluded that the effect of ?-radiation on polyethylene results in intensive formation of new bonds or crosslinking at doses ranging from 10 to 100 kGy. Saturation of I3 for the irradiated HDPE at doses ranging from 100 to 200 kGy may indicate the achievement of a structural stability.

EL-Sayed, A. M. A.; Abdel-Hady, E. E.; Rizk, R. A. M.; M´sen, M.

1994-07-01

419

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

420

Polyethylene failure of the patellar component in New Jersey low-contact stress total knee arthroplasties.  

PubMed

In a postoperative 5- to 12-year follow-up study of 598 New Jersey low-contact stress total knee arthroplasties, 32 required revision. All retrieved patellar components were examined for polyethylene damage. These 32 cases had 3 types of failure: split rupture (7 cases), peripheral wear (21), and cantilevering breakage (4), respectively 75%, 64.3%, and 100% of which showed subluxation and/or tilting of the patellar component on the prerevision roentgenograms. Misalignment at the joint contact surfaces and rotational blockage of the mobile patellar component were considered the major causes of the failure. A design of a flatter metallic button (giving larger focal thickness of the polyethylene) and a dome-shaped polyethylene (reducing stress concentration at the pinnacle) may alleviate the failure driving mechanism should subluxation or tilting of the patellar component take place. PMID:15902859

Huang, Chun-Hsiung; Liau, Jiann-Jong; Ho, Fang-Yuan; Lin, Chia-Yin; Young, Tai-Horng; Cheng, Cheng-Kung

2005-02-01

421

[Stretched polyethylene (UHMWPE)--a new substance modification for minimizing wear in artificial knee joint replacement].  

PubMed

Polyethylene wear is a major cause of aseptic loosening of knee endoprostheses. With the aim of minimizing this mechanical wear, we stretch-modified the structure of polyethylene. From plates of UHMWPE, stretched PE samples were produced under defined conditions, and subsequently submitted to friction tests in a fluid environment (cycles 5 x 10(5), frequency 1.5 Hz, load 500 N, contact stress 10 MPa). After load testing, the stretched samples revealed a 70% reduced wear rate in comparison with non-stretched samples. Microscopic examination (light microscopy, scanning electron microscopy) showed abrasive scratches in all test samples, but only in the non-stretched specimens were signs of pitting found. Translating these results to unidirectional tractive rolling on the tibial plateau in the knee joint suggests that a significant reduction in polyethylene wear can be expected. However, further experimental investigations need to be carried out to confirm this highly promising possibility. PMID:11820160

Wirtz, D C; Schopphoff, E; Weichert, D; Niethard, F U

2001-12-01

422

Comparison of Conventional Polyethylene Wear and Signs of Cup Failure in Two Similar Total Hip Designs  

PubMed Central

Multiple factors have been identified as contributing to polyethylene wear and debris generation of the acetabular lining. Polyethylene wear is the primary limiting factor in the functional behavior and consequent longevity of a total hip arthroplasty (THA). This retrospective study reviewed the clinical and radiographic data of 77 consecutive THAs comparing in vivo polyethylene wear of two similar acetabular cup liners. Minimum follow-up was 7 years (range 7–15). The incidence of measurable wear in a group of machined liners sterilized with ethylene oxide and composed of GUR 1050 stock resin was significantly higher (61%) than the compression-molded, GUR 1020, O2-free gamma irradiation sterilized group (24%) (P = 0.0004). Clinically, at a 9-year average followup, both groups had comparable HHS scores and incidence of thigh or groin pain, though the machined group had an increased incidence of osteolysis and annual linear wear rate. PMID:23662210

Pace, Thomas B.; Keith, Kevin C.; Snider, Rebecca G.; Tanner, Stephanie L.; DesJardins, John D.

2013-01-01

423

Protein adsorption to hydrophobic Zeolite Y: salt effects and application to protein fractionation.  

PubMed

The binding equilibria of proteins with a hydrophobic variety of crystalline Zeolite Y is affected by salt and is a function of the type of salt and its concentration. The behaviour does not always follow the conventional pattern of increased binding at high salt concentrations and varies also for the different proteins involved. The overall process may be looked upon as a salting-in/salting-out mechanism. This material can be used as a surface for the selective adsorption of proteins and has been applied for the fractionation of ox heart homogenate in multi-stage operations. The presence of NaCl influences the protein binding, and this can be seen by monitoring the activity profile of lactate dehydrogenase. The bound protein can be reversed by treating the equilibrium mixture with low-molecular-mass poly(ethylene glycol)s. PMID:8297508

Ghose, S; Mattiasson, B

1993-12-01

424

Detection of viral antigens by solid phase radioimmunoassay on polyethylene film.  

PubMed

Polyethylene film, without any pretreatment, may serve as a solid phase (SP) for RIA. Viral antigens (HBsAg, and influenza virus) are detected by SP-RIA on the film with a sensitivity of about 2-3 ng/ml or 40-60 pg/assay. The use of polyethylene film allows one to record RIA autographically. The use of micro amounts of reagents and specimens tested is an added advantage. No special equipment is necessary, the method is inexpensive, easy to perform and may be used for mass screening. PMID:3722308

Prokudina, E N; Semenova, N P; Zhdanov, V M

1986-04-01

425

CBNM certification of Cd in polyethylene by isotope dilution mass spectrometry  

NASA Astrophysics Data System (ADS)

Four polyethylene materials have been certified for their cadmium content by isotope dilution mass spectrometry. To do so, a spike (enriched 111Cd) was characterized by reverse IDMS using high purity cadmium metal. The cadmium concentration certified in the polyethylene is 0.363, 0.676, 1.760 and 3.62 mmol kg-1 respectively (40.9, 75.9 197.9 and 407 mg kg-1 respectively). These certified materials can be used in calibrating routine methods and measurements.

Götz, A.; Lamberty, A.; de Biévre, P.

1993-01-01

426

Free volume change of elongated polyethylene films studied using a positron probe microanalyzer  

NASA Astrophysics Data System (ADS)

Free volume change of low density polyethylene (LDPE) and high density polyethylene (HDPE) films upon mechanical deformation was microscopically investigated by positron probe microanalysis (PPMA). The ortho-positronium (o-Ps) lifetimes were gradually shortened by uniaxial deformation, indicative of shrinkage of the free volume. The o-Ps intensity for HDPE increased by deformation, whereas that for LDPE varied little. It suggests that destruction of crystallites plays an important role in the deformation of HDPE. PPMA is demonstrated to be a promising, powerful probe investigating free volume changes, at different local points subjected to different degrees of deformation, in elongated polymers.

Oka, Toshitaka; Oshima, Nagayasu; Suzuki, Ryoichi; Uedono, Akira; Fujinami, Masanori; Kobayashi, Yoshinori

2012-11-01

427

Axial pattern composite prefabrication of high-density porous polyethylene: experimental and clinical research.  

PubMed

Currently, various alloplastic materials are being used for reconstruction of three-dimensional structures, and high-density porous polyethylene is so far the best and the most commonly used material. Various indications for high-density porous polyethylene have been defined for closure of craniofacial defects, correction of congenital anomalies, and aesthetic augmentations. A common property of various studies published so far is that after being fixed to the bone or underlying structures, high-density porous polyethylene has been covered primarily or by skin flaps. For reconstruction of complex three-dimensional structures such as the ear and nose, the success of current methods is limited by the thinness and pliability of the skin flap. In this study, the authors' aim was to investigate the graftability of high-density porous polyethylene after prefabrication with an axial pedicle and to explore possible clinical applications in light of the new data obtained. In the experimental study, three-dimensional implants (rectangular prism) carved from high-density porous polyethylene were prefabricated using bilateral superficial epigastric arteries and veins of 25 New Zealand rabbits. After a waiting period of 2 to 6 weeks in five groups, control samples were obtained and the prefabricated implants that had been left in place were directly grafted. The results showed that high-density porous polyethylene was vascularized 75 percent after 4 weeks and 90 percent after 5 weeks, and 95 percent of the grafts had survived after 8 weeks. In the clinical study, three nose defects, three ear defects, and one hard palate defect in seven patients ranging in age from 21 to 72 years were reconstructed using the same method. High-density porous polyethylene has been prefabricated and directly grafted for the very first time on a clinical basis. No serious complications have been observed, except for minimal graft loss in two patients. It is obvious that full-thickness skin grafts that are thinner than flaps will adapt better to the fine details of high-density porous polyethylene and will highly increase the detail obtained in the reconstruction of three-dimensional defects. PMID:15622249

Ozdemir, Ragip; Kocer, Ugur; Tiftikcioglu, Yigit Ozer; Karaaslan, Onder; Kankaya, Yuksel; Cuzdan, Sedat; Baydar, Dilek Ertoy

2005-01-01

428

Probing the Melt Miscibility of a Commercial Polyethylene Blend by Small-Angle Light Scattering  

Microsoft Academic Search

Small-angle light scattering (SALS) was used to determine the binary interaction parameter ? in a molten blend of linear polyethylene (LPE, Mw = 52 kg\\/mol, PDI = 2.9) and linear low-density polyethylenes (LLDPEs) based on homogeneous ethylene-1-butene copolymers (LLDPE-1, 18.7 mol% butane branches, Mw = 58.1 kg\\/mol, and LLDPE-2, 5.9 mol% butene branches, Mw = 70 kg\\/mol). Traditional cloud point measurements (cooling at 0.5–3°C\\/min) and melt annealing\\/isothermal measurements under VV (parallel-polarized)

Yvonne A. Akpalu; Ping Peng

2008-01-01

429

A study of the effect of pressure upon the morphology of polyethylene crystals  

E-print Network

measurements of the cell were made by a copper-con- stantan thermocouple in thermal contact with the cell at a point near the chamber. The thermal emf was determined by a Kin Tel voltmeter. ~II ' ~ . The samples of polyethylene used in this work were... measurements of the cell were made by a copper-con- stantan thermocouple in thermal contact with the cell at a point near the chamber. The thermal emf was determined by a Kin Tel voltmeter. ~II ' ~ . The samples of polyethylene used in this work were...

Green, Max B

2012-06-07

430

Electrical conduction in polyethylene: The role of positive charge and the formation of positive packets  

NASA Astrophysics Data System (ADS)

A model for positive hole transport in polyethylene is developed which takes particular account of the crystalline-amorphous morphology of the polymer. The significant feature is the employment of super-exchange quantum mechanical tunneling to explain hole transport through the amorphous phase. The consequence is that the hole mobility exhibits a maximum as a function of the electric field, a manifestation of the inverse Marcus effect. It is shown that this feature accounts for the majority of the reported high-field hole transport effects in polyethylene, including packet formation.

Lewis, T. J.; Llewellyn, J. P.

2013-06-01

431

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

432

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

433

Multiaxial deformation of polyethylene and polyethylene/clay nanocomposites: In situ synchrotron small angle and wide angle X-ray scattering study  

SciTech Connect

A unique in situ multiaxial deformation device has been designed and built specifically for simultaneous synchrotron small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) measurements. SAXS and WAXS patterns of high-density polyethylene (HDPE) and HDPE/clay nanocomposites were measured in real time during in situ multiaxial deformation at room temperature and at 55 C. It was observed that the morphological evolution of polyethylene is affected by the existence of clay platelets as well as the deformation temperature and strain rate. Martensitic transformation of orthorhombic into monoclinic crystal phases was observed under strain in HDPE, which is delayed and hindered in the presence of clay nanoplatelets. From the SAXS measurements, it was observed that the thickness of the interlamellar amorphous region increased with increasing strain, which is due to elongation of the amorphous chains. The increase in amorphous layer thickness is slightly higher for the nanocomposites compared to the neat polymer.

Gurun, Bilge; Bucknall, David G.; Thio, Yonathan S.; Teoh, Chin Ching; Harkin-Jones, Eileen (GIT); (Queens)

2013-01-10

434

Effects of polyethylene mulch in a short-rotation, poplar plantation vary with weed-control strategies,  

E-print Network

Effects of polyethylene mulch in a short-rotation, poplar plantation vary with weed polyethylene mulch (poly mulch) across a range of site conditions, weed-control treatments and genotypes in a randomized complete-block design (2:4 m Ã? 3 m spacing) during May, 1999, under intensive and minimal weed

Green, Scott

435

Insight into the Molecular Arrangement of High-Density Polyethylene Polymer Chains in Blends of Polystyrene/High-  

E-print Network

of Polystyrene/High- Density Polyethylene from Differential Scanning Calorimetry and Raman Techniques JAYANT, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854 (G.S.H.) Polystyrene intensity of all-trans HDPE stretch vibrations. Index Headings: Blends; Raman; Polyethylene; Polystyrene

436

Poly(ethylene oxide)\\/Laponite nanocomposites via melt-compounding: effect of clay modification and matrix molar mass  

Microsoft Academic Search

The present study focuses on the preparation of poly(ethylene oxide) (PEO) nanocomposites based on the synthetic Laponite clay. The clay was added both in its pure form as well as organically modified with low molar mass poly(ethylene glycol) (PEG) components in order to enhance the compatibility between Laponite and PEO. Several PEG's with different end groups were used. Almost all

Wendy Loyens; Patric Jannasch; Frans H. J. Maurer

2005-01-01

437

Platelet responses to dynamic biomaterial surfaces with different poly(ethylene glycol) and polyrotaxane molecular architectures constructed on gold substrates.  

PubMed

Four different dynamic biomaterial surfaces with different molecular architectures were prepared using two hydrophilic polymers: poly(ethylene glycol) and polyrotaxanes containing ?-cyclodextrin. Either one or both terminals of the poly(ethylene glycol) or polyrotaxanes were immobilized onto a gold substrate via Au-S bonds, resulting in poly(ethylene glycol)-graft, polyrotaxanes-graft, poly(ethylene glycol)-loop, and polyrotaxanes-loop structures. Human platelet adhesion was suppressed more effectively on the graft surfaces than on the loop surfaces for both poly(ethylene glycol) and polyrotaxanes due to the high mobility of graft polymer chains with a free terminal. Moreover, the platelets adhered to the polyrotaxane surfaces much less than the poly(ethylene glycol) surfaces, possibly because of the mobile nature of the ?-cyclodextrin molecules that were threaded on the poly(ethylene glycol) chain. Actin filament assembly in adherent platelets was also greatly prevented on the poly(ethylene glycol)/polyrotaxanes-graft surfaces in comparison with the corresponding loop surfaces. A clear correlation between the numbers and areas of adherent platelets on these surfaces suggests that platelet adhesion and activation were dominated by the platelet GPIIb/IIIa-adsorbed fibrinogen interaction. These results indicate that both of the different modes of dynamic features, sliding/rotation of ?-cyclodextrin and polymer chain mobility, effectively suppressed platelet adhesion in spite of the similar hydrophilicity. This research affords a novel chemical strategy for designing hemocompatible biomaterial surfaces. PMID:23048065

Kakinoki, Sachiro; Yui, Nobuhiko; Yamaoka, Tetsuji

2013-11-01

438

TART calculations of neutron attenuation and neutron-induced photons on 5% and 20% borated polyethylene slabs  

SciTech Connect

The coupled neutron/photon transport code TART has been used to calculate the attenuation of neutrons and the production of induced photons for neutrons incidents on 5% and 20% borated polyethylene slabs. The neutron attenuation lengths are found to be 2.4 cm and 2.9 cm for 5% and 20% borated polyethylene, respectively.

Wuest, C.R.

1993-04-20

439

The investigation of using magnesium hydroxide as a flame retardant in the cable insulation material by cross-linked polyethylene  

Microsoft Academic Search

The use of magnesium hydroxide was investigated as a flame retardant in the cable insulation material that has low density polyethylene cross-linked by silane grafting method. The different insulation samples with low density polyethylene filled magnesium hydroxide were prepared and physical and mechanical properties of these samples were measured such as tensile strength, elongation at break, impact, bending, oxygen index,

Ahmet Akin Sener; Enver Demirhan

2008-01-01

440

ProteinProtein Interactions  

E-print Network

to nitrocellulose or PVDF membrane, and then incubating with a probe of interest. The probe is typically a protein, samples are run on SDS-PAGE gels, transferred to nitrocellulose or PVDF, and then overlaid with a soluble

Hall, Randy A

441

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

442

X-ray Spectromicroscopy Study of Protein Adsorption to a Polystyrene-Polylactide Blend  

E-print Network

X-ray Spectromicroscopy Study of Protein Adsorption to a Polystyrene-Polylactide Blend Bonnie O the adsorption of human serum albumin (HSA) to polystyrene-polylactide (40:60 PS-PLA, 0.7 wt %) thin films such as polystyrene (PS)1 or polyethylene glycol (PEG)2 with a biodegradable material. The combination

Hitchcock, Adam P.

443

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

444

Adhesion and Wettability of Marine Adhesive Proteins in Aqueous Systems  

Microsoft Academic Search

The work of adhesion on substrates with low and high surface energies using a variety of homo, random and sequential polypeptides containing L-lysine has been investigated to evaluate the role of individual amino acids together with the sequences in marine adhesive proteins. The work of adhesion of poly (L-lysine) was lower (34–79 mJ\\/m) on the surfaces of Teflon and polyethylene

Hiroyuki Yamamoto; Takahiro Ogawa; Shin-Ichi Ohara; Ayako Nishida; Yuuki Hirata; Hideki Tatehata; Kousaku Ohkawa

1996-01-01

445

Monitoring the expression of green fluorescent protein in carrot  

Microsoft Academic Search

Green fluorescent protein (GFP) was successfully used as a visual reporter at various stages of carrot (Daucus carota L.) transformation. GFP-fluorescence was non-invasively observed in protoplasts, callus and plants after the delivery of\\u000a mgfp5-er gene using two transformation methods: direct DNA transfer into polyethylene glycol (PEG) -treated protoplasts and inoculation\\u000a of root discs with Agrobacterium rhizogenes. Transient GFP-expression was detected

Rafal Baranski; Evelyn Klocke; Ulrich Ryschka

2007-01-01

446

Colonization and Degradation of Thermally Oxidized High-Density Polyethylene by Aspergillus niger (ITCC No. 6052) Isolated from Plastic Waste Dumpsite  

Microsoft Academic Search

Plastic materials, particularly polyethylene, are the potential source of environmental pollution. In the present study, a fungal strain was isolated from plastic waste dumpsites capable of adhering to high-density polyethylene (HDPE) surface. The fungal strain was identified as Aspergillus niger (ITCC no. 6052). A visible increase in the growth of the fungi was observed on the surface of the polyethylene

Garima Mathur; Ashwani Mathur; Ramasare Prasad

2011-01-01

447

ZPPR-20 phase D : a cylindrical assembly of polyethylene moderated U metal reflected by beryllium oxide and polyethylene.  

SciTech Connect

The Zero Power Physics Reactor (ZPPR) fast critical facility was built at the Argonne National Laboratory-West (ANL-W) site in Idaho in 1969 to obtain neutron physics information necessary for the design of fast breeder reactors. The ZPPR-20D Benchmark Assembly was part of a series of cores built in Assembly 20 (References 1 through 3) of the ZPPR facility to provide data for developing a nuclear power source for space applications (SP-100). The assemblies were beryllium oxide reflected and had core fuel compositions containing enriched uranium fuel, niobium and rhenium. ZPPR-20 Phase C (HEU-MET-FAST-075) was built as the reference flight configuration. Two other configurations, Phases D and E, simulated accident scenarios. Phase D modeled the water immersion scenario during a launch accident, and Phase E (SUB-HEU-MET-FAST-001) modeled the earth burial scenario during a launch accident. Two configurations were recorded for the simulated water immersion accident scenario (Phase D); the critical configuration, documented here, and the subcritical configuration (SUB-HEU-MET-MIXED-001). Experiments in Assembly 20 Phases 20A through 20F were performed in 1988. The reference water immersion configuration for the ZPPR-20D assembly was obtained as reactor loading 129 on October 7, 1988 with a fissile mass of 167.477 kg and a reactivity of -4.626 {+-} 0.044{cents} (k {approx} 0.9997). The SP-100 core was to be constructed of highly enriched uranium nitride, niobium, rhenium and depleted lithium. The core design called for two enrichment zones with niobium-1% zirconium alloy fuel cladding and core structure. Rhenium was to be used as a fuel pin liner to provide shut down in the event of water immersion and flooding. The core coolant was to be depleted lithium metal ({sup 7}Li). The core was to be surrounded radially with a niobium reactor vessel and bypass whic