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Poly wear

Carolina Fabiana Centenaro, Fabiana Soares Grecca, Patrícia Maria Poli Kopper, Rodrigo Ricci Vivan, Jefferson Ricardo Pereira, Ricardo Abreu da Rosa, Paula Barcellos da Silva, Marcus Vinícius Reis Só
The purpose of this study was to quantify the presence of nickel (Ni) and titanium (Ti) on dentin walls of prepared root canals using Endosequence (ES) and Wave One (WO) systems, the deformation, and fracture of these instruments. Thirty extracted human premolar teeth were selected and prepared with WO, ES, and manually (control group-CG). Each instrument was used in four root canals. The root canals were irrigated with 2.5% sodium hypochlorite solution. After preparation, roots were sectioned longitudinally and the apical third was analyzed by scanning electron microscopy with X-ray microanalysis (SEM-EDS)...
May 13, 2018: Microscopy Research and Technique
Kathryn A Chamberlain, Kenneth S Rankin, Adam Briscoe, David Deehan, Philip J Hyde
Poly-ether-ether-ketone (PEEK), having shown favorable biocompatibility in spinal applications is being considered as an alternative biomaterial in orthopaedics, either as part of an all-polymer bearing couple, or a replacement for the metallic component in hard-on-soft bearings. Throughout the literature ultra-high molecular weight polyethylene exhibits a range of wear behavior dependent upon the amount of cross shear (CS) present in the bearing motion; in comparison, the behavior of PEEK bearing combinations subject to cross shear conditions is less understood...
May 7, 2018: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Francesco Ventura, Rosario Barranco, Tiziana Bachetti, Paolo Nozza, Ezio Fulcheri, Antonella Palmieri, Isabella Ceccherini
The heterozygous PHOX2B gene mutation is related to congenital central hypoventilation syndrome (CCHS). It is characterized by defective autonomous nervous system development leading to inadequate breathing response to hypoxia and hypercapnia, leading to hypoventilation especially during non-REM sleep, but also during waking in the more severe cases. Herein we report a case of sudden death in a 28-day-old child. The mother reported the infant was found lying on her own bed in the prone position. The infant was wearing a romper and lying in her crib without any blanket or other objects...
April 17, 2018: Journal of Forensic and Legal Medicine
Saverio Cosola, Simone Marconcini, Enrica Giammarinaro, Gian L Poli, Ugo Covani, Antonio Barone
BACKGROUND: Patient-centred outcomes are being given great attention by the dental scientific community. The Oral Health Impact Profile -14 questionnaire (OHIP-14) has been introduced to address patients' success criteria when describing the impact of oral rehabilitations on quality of life (OHrQoL). METHODS: Thirty-five patients wearing a full-arch implant-prosthesis being in place between 4 and 6 years before this analysis were considered eligible and then enrolled in the present retrospective study...
April 16, 2018: Minerva Stomatologica
Hailin Lu, Shanshan Ren, Xing Li, Junde Guo, Guangneng Dong, Jianhui Li, Li Gao
Body fluid is normally the only lubricant after joint replacement surgery, but wear problems have occurred because body fluid has poor lubrication ability. However, traditional lubricant would be diluted by body fluids and then absorbed by the human body. Therefore, an injectable gel with the ability to slow-release lubricant was designed to replace the joint capsule. The proposed gel, poly(ethylene glycol)/chitosan/sodium glycerophosphate (PEG/CS/GP) composite gel was then tested. The tribology results showed that the PEG/CS/GP gel had excellent slow-release properties, especially under pressure, and the PEG played an important role in improving the gel's rheological and mechanical properties...
April 3, 2018: Journal of Biomaterials Science. Polymer Edition
Zhaoxia Li, Shuanhong Ma, Ga Zhang, Daoai Wang, Feng Zhou
Amphiphilic polymer nanospheres of poly(3-sulfopropyl methacrylate potassium salt- co-styrene) [P(SPMA- co-St)] were prepared by a simple soap-free emulsion polymerization method and used as efficient water lubrication additives to enhance the antiwear behaviors of the Ti6 Al4 V alloy. The monodisperse and flexible P(SPMA- co-St) bicomponent copolymer nanospheres were synthesized with a controllable manner by adjusting the mass fraction ratio of the monomers, with the hydrophobic polystyrene (PSt) as the hard skeletal carrier component and the hydrophilic PSPMA with a hydration layer structure as the soft lubrication layer in the course of friction...
March 14, 2018: ACS Applied Materials & Interfaces
Guoxu Liu, Jinhui Nie, Changbao Han, Tao Jiang, Zhiwei Yang, Yaokun Pang, Liang Xu, Tong Guo, Tianzhao Bu, Chi Zhang, Zhong Lin Wang
The physical filtration mechanism of a traditional face mask has a low removal efficiency of ultrafine particulates in the size range of 10-1000 nm, which are badly harmful to human health. Herein, a novel self-powered electrostatic adsorption face mask (SEA-FM) based on the poly(vinylidene fluoride) electrospun nanofiber film (PVDF-ESNF) and a triboelectric nanogenerator (TENG) driven by respiration (R-TENG) is developed. The ultrafine particulates are electrostatically adsorbed by the PVDF-ESNF, and the R-TENG can continually provide electrostatic charges in this adsorption process by respiration...
February 28, 2018: ACS Applied Materials & Interfaces
Hamed Aghajani Derazkola, Abdolreza Simchi
In this study, alumina-reinforced poly(methyl methacrylate) nanocomposites (PMMA/Al2 O3 ) containing up to 20vol% nanoparticles with an average diameter of 50nm were prepared by friction stir processing. The effects of nanoparticle volume fraction on the microstructural features and mechanical properties of PMMA were studied. It is shown that by using a frustum pin tool and employing an appropriate processing condition, i.e. a rotational speed of 1600rpm/min and transverse velocity of 120mm/min, defect free nanocomposites at microscale with fine distribution of the nanoparticles can successfully been prepared...
March 2018: Journal of the Mechanical Behavior of Biomedical Materials
Masayuki Kyomoto, Toru Moro, Shihori Yamane, Kenichi Watanabe, Masami Hashimoto, Sakae Tanaka, Kazuhiko Ishihara
Manipulating the surface and substrate of cross-linked polyethylene (CLPE) is an essential approach for obtaining life-long orthopedic bearings. We therefore proposed a bearing material comprised of an antioxidative substrate generated by vitamin E blending (HD-CLPE[VE]) with a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted surface, and investigated its wear resistance and oxidative stability under accelerated aging and load bearing conditions. Neither the hydration nor friction kinetics of the molecular network structure of the PMPC-grafted surface or the HD-CLPE(VE) substrate were influenced by accelerated aging but rather exhibited high stability even under high oxidation conditions...
March 2018: Journal of the Mechanical Behavior of Biomedical Materials
Lidia Escutia-Guadarrama, Genaro Vázquez-Victorio, David Martínez-Pastor, Brenda Nieto-Rivera, Marcela Sosa-Garrocho, Marina Macías-Silva, Mathieu Hautefeuille
We present the rapid-prototyping of type I collagen micropatterns on poly-dimethylsiloxane substrates for the biomimetic confinement of cells using the combination of a surface oxidation treatment and 3-aminopropyl triethoxysilane silanisation followed by glutaraldehyde crosslinking. The aim of surface treatment is to stabilise microcontact printing transfer of this natural extracellular matrix protein that usually wears out easily from poly-dimethylsiloxane, which is not suitable for biomimetic cell culture platforms and lab-on-chip applications...
January 2017: Journal of Tissue Engineering
Olwyn R Mahon, Sarah O'Hanlon, Clare C Cunningham, Geraldine M McCarthy, Christopher Hobbs, Valeria Nicolosi, Daniel J Kelly, Aisling Dunne
Total joint replacements (TJR) are costly procedures required to relieve pain and restore function in patients suffering from end-stage arthritis. Despite great progress in the development and durability of TJRs, the generation of prosthesis-associated wear particles over time leads to an inflammatory cascade which culminates in periprosthetic osteolysis. Studies suggest that wear particles drive the polarization/differentiation of immature macrophages towards a pro-inflammatory M1 phenotype rather than an anti-inflammatory M2 phenotype associated with normal bone and wound healing...
January 2018: Acta Biomaterialia
R Nithyaprakash, S Shankar, M S Uddin
Hip implants subject to gait loading due to occupational activities are potentially prone to failures such as osteolysis and aseptic loosening, causing painful revision surgeries. Highly risky gait activities such as carrying a load, stairs up or down and ladder up or down may cause excessive loading at the hip joint, resulting in generation of wear and related debris. Estimation of wear under the above gait activities is thus crucial to design and develop a new and improved implant component. With this motivation, this paper presents an assessment of wear generation of PCD-on-PCD (poly crystalline diamond) hip implants using finite element (FE) analysis...
November 2, 2017: Medical & Biological Engineering & Computing
Bijay Kumar Poudel, Jae Hong Park, Jiseok Lim, Jeong Hoon Byeon
Labeling of aerosol particles with a radioactive, magnetic, or optical tracer has been employed to confirm particle localization in cell compartments, which has provided useful evidence for correlating toxic effects of inhaled particles. However, labeling requires several physicochemical steps to identify functionalities of the inner or outer surfaces of particles, and moreover, these steps can cause changes in size, surface charge, and bioactivity of the particles, resulting in misinterpretations regarding their toxic effects...
October 2017: Nanotoxicology
Congxian Jia, William C Vogt, Keith A Wear, T Joshua Pfefer, Brian S Garra
Photoacoustic tomography (PAT) is emerging as a potentially important aid for breast cancer detection. Well-validated tissue-simulating phantoms are needed for objective, quantitative, and physically realistic testing for system development. Prior reported PAT phantoms with homogenous structures do not incorporate the irregular layered structure of breast tissue. To assess the impact of this simplification, we design and construct two-layer breast phantoms incorporating vessel-simulating inclusions and realistic undulations at the fat/fibroglandular tissue interface...
October 2017: Journal of Biomedical Optics
Myrto Korogiannaki, Jianfeng Zhang, Heather Sheardown
Discontinuation of contact lens wear as a result of ocular dryness and discomfort is extremely common; as many as 26% of contact lens wearers discontinue use within the first year. While patients are generally satisfied with conventional hydrogel lenses, improving on-eye comfort continues to remain a goal. Surface modification with a biomimetic, ocular friendly hydrophilic layer of a wetting agent is hypothesized to improve the interfacial interactions of the contact lens with the ocular surface. In this work, the synthesis and characterization of poly(2-hydroxyethyl methacrylate) surfaces grafted with a hydrophilic layer of hyaluronic acid are described...
October 2017: Journal of Biomaterials Applications
Chanaka Kumara, Huimin Luo, Donovan N Leonard, Harry M Meyer, Jun Qu
Advanced lubrication is essential in human life for improving mobility, durability, and efficiency. Here we report the synthesis, characterization, and evaluation of two groups of oil-suspendable silver nanoparticles (NPs) as candidate lubricant additives. Two types of thiolated ligands, 4-(tert-butyl)benzylthiol (TBBT) and dodecanethiol (C12), were used to modify Ag NPs in two size ranges, 1-3 and 3-6 nm. The organic surface layer successfully suspended the Ag NPs in a poly-alpha-olefin (PAO) base oil with concentrations up to 0...
October 11, 2017: ACS Applied Materials & Interfaces
Jillian A Emerson, Nikolay T Garabedian, Axel C Moore, David L Burris, Eric M Furst, Thomas H Epps
We employed a systematic processing approach to control phase separation in polymer blend thin films and significantly reduce dynamic friction coefficients (μ)s. We leveraged this modulation of phase separation to generate composite surfaces with dynamic friction coefficients that were substantially lower than expected on the basis of simple mixing rules, and in several cases, these friction coefficients were lower than those of both pure components. Using a model polyisoprene [PI]/polystyrene [PS] composite system, a minimum μ was found in films with PS mass fractions between 0...
October 4, 2017: ACS Applied Materials & Interfaces
Yunxiao Zhang, Tao Cai, Wangji Shang, Dan Liu, Qiang Guo, Shenggao Liu
A novel environmentally friendly bis-functional dicationic ionic liquid containing chelated orthoborate was synthesized and polycondensed with glutamic acid in order to synthesize inorganic-organic carbon dots (CD/IL) consisting of an ionic liquid moiety inserted in the carbon skeleton. The obtained CD/IL was found to be a new kind of nitrogen/boron-codoped nanomaterial, one with a mean particle diameter of 2.66 nm. CD/IL was verified to be a high-performance lubricant additive: in particular, the anti-wear and friction-reducing properties of poly(ethylene glycol) (PEG) were improved by 89...
September 28, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Chengjie Li, Meng Xiang, Xiaowen Zhao, Lin Ye
On the basis of the industrialized graphene nanosheets (GNs) product, we synthesized monomer casting nylon-6 (MC PA6)/GN-3-aminopropyl-terminated poly(dimethylsiloxane) (APDMS) nanocomposite in situ through the anchoring effect of APDMS onto the GN surface. APDMS/PA6 molecules were confirmed to intercalate into the GN layers by the formation of strong interfacial interactions. The intercalation ratio and the average layer thickness of the grafted GN sample decreased in the presence of APDMS. Moreover, for MC PA6/GN-APDMS nanocomposite, GN-APDMS was uniformly distributed in the matrix and no phase separation was observed...
September 27, 2017: ACS Applied Materials & Interfaces
Bryan T Seymour, Roger A E Wright, Alexander C Parrott, Hongyu Gao, Ashlie Martini, Jun Qu, Sheng Dai, Bin Zhao
This article reports on the synthesis of a series of poly(alkyl methacrylate) brush-grafted, 23 nm silica nanoparticles (hairy NPs) and the study of the effect of alkyl pendant length on their use as oil lubricant additives for friction and wear reduction. The hairy NPs were prepared by surface-initiated reversible addition-fragmentation chain transfer polymerization from trithiocarbonate chain transfer agent (CTA)-functionalized silica NPs in the presence of a free CTA. We found that hairy NPs with sufficiently long alkyl pendant groups (containing >8 carbon atoms, such as 12, 13, 16, and 18 in this study) could be readily dispersed in poly(alphaolefin) (PAO), forming clear, homogeneous dispersions, and exhibited excellent stability at low and high temperatures as revealed by visual inspection and dynamic light scattering studies...
July 12, 2017: ACS Applied Materials & Interfaces
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