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https://www.readbyqxmd.com/read/29330941/hydrophobic-and-hydrophilic-effects-on-water-structuring-and-adhesion-in-denture-adhesives
#1
Simrone K Gill, Nima Roohpour, Yiran An, Julien E Gautrot, Paul D Topham, Brian J Tighe
Denture adhesives are designed to be moisture-sensitive through the inclusion of a blend of polymer salts with varying degrees of water-sensitivity. This enables the adhesive to mix with saliva in vivo and activate its high tack, through the formation of a mucilaginous layer. We report for the first time, the use of differential scanning calorimetry (DSC) to study a series of hydrophobic and hydrophilic polymeric systems in order to correlate water-structuring behavior with adhesion strength. Adhesive bonding of the more hydrophobic variants was higher than that of a commercial-based control and a more hydrophilic polymer system in both lap shear and tensile configurations...
January 13, 2018: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/29330453/calcium-sulfate-induced-versus-pmma-induced-membrane-in-a-critical-sized-femoral-defect-in-a-rat-model
#2
Yun-Fei Ma, Nan Jiang, Xiang Zhang, Cheng-He Qin, Lei Wang, Yan-Jun Hu, Qing-Rong Lin, Bin Yu, Bo-Wei Wang
Aimed to investigate the characteristics of CS-induced membrane in comparison with the PMMA-induced membrane. Cellular components, histological changes, growth factor expressions of IL-6, VEGF, BMP-2, and TGF-β1 in the two induced membranes were compared at 2, 4, 6 and 8 weeks, respectively. We also compared the histological changes at the bone defects between CS and PMMA groups. The structural characteristics of induced membrane were similar between CS and PMMA. Endochondral ossification took place in the CS-induced membrane at 8 week...
January 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29328340/interactions-between-brush-grafted-nanoparticles-within-chemically-identical-homopolymers-the-effect-of-brush-polydispersity
#3
So Jung Park, Seyong Kim, Daeseong Yong, Youngson Choe, Joona Bang, Jaeup U Kim
We systematically examined the polymer-mediated interparticle interactions between polymer-grafted nanoparticles (NPs) within chemically identical homopolymer matrices through experimental and computational efforts. In experiments, we prepared thermally stable gold NPs grafted with polystyrene (PS) or poly(methyl methacrylate) (PMMA), and they were mixed with corresponding homopolymers. The nanocomposites are well dispersed when the molecular weight ratio of free to grafted polymers, α, is small. For α above 10, NPs are partially aggregated or clumped within the polymer matrix...
January 12, 2018: Soft Matter
https://www.readbyqxmd.com/read/29328320/efficient-and-tunable-strip-to-slot-fundamental-mode-coupling
#4
Viphretuo Mere, Rakshitha Kallega, Shankar Kumar Selvaraja
We present a novel photonic wire-to-slot waveguide coupler in SOI. The phase matching between a wire and slot mode is achieved using a mode transformer. The architecture consists of a balanced 50/50 power splitter and a tunable phase matched taper combiner forming a slot waveguide. We show a theoretical wire-to-slot coupling efficiency of 99 % is achievable and experimentally, we demonstrate a coupling efficiency of 99 % in the 1550 nm band. Based on the coupling scheme, we also show excitation of a slot mode in a slotted ring resonator and verified the excitation through the thermo-optic response of the rings...
January 8, 2018: Optics Express
https://www.readbyqxmd.com/read/29328106/polymer-thermal-optical-switch-for-a-flexible-photonic-circuit
#5
Yue Sun, Yue Cao, Qi Wang, Yunji Yi, Xiaoqiang Sun, Yuanda Wu, Fei Wang, Daming Zhang
Flexible and wearable optoelectronic devices are the new trend for an active lifestyle. These devices are polymer-based for flexibility. We demonstrated flexible polymer waveguide optical switches for a flexible photonic integrated circuit. The optical switches are composed of a single-mode inverted waveguide with dimensions of 5 μm waveguide width, 3 μm ridge height, and 3 μm slab height. A Mach-Zehnder structure was used in the device, with the Y-branch horizontal length of 0.1 cm, the distance between two heating branches of 30 μm, and the heating branch length of 1 cm...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29327749/fabrication-of-high-performance-graphene-nanoplatelet-based-transparent-electrodes-via-self-interlayer-exfoliation-control
#6
Jong Sik Oh, Ji Soo Oh, Da In Sung, Geun Young Yeom
Graphene nanoplatelets (GNP) have attracted considerable attention due to their high yield and fabrication route that is scalable to enable graphene production. However, the absence of a means of fabricating a transparent and conductive GNP film has been the biggest obstacle to the replacement of pristine graphene. Here, we report on a novel means of fabricating uniform and thin GNP-based high-performance transparent electrodes for flexible and stretchable optoelectronic devices involving the use of an adhesive polymer layer (PMMA) as a GNP layer controller and by forming a hybrid GNP/AgNW electrode embedded on PET or PDMS...
January 12, 2018: Nanoscale
https://www.readbyqxmd.com/read/29327368/measurement-of-residual-chemical-shift-anisotropies-in-compressed-pmma-gels-automatic-compensation-of-gel-isotropic-shift-contribution
#7
Fernando Hallwass, Rubens R Teles, Erich Hellemann, Christian Griesinger, Roberto R Gil, Armando Navarro-Vázquez
Mechanical compression of polymer gels provides a simple way for the measurement of Residual Chemical Shift Anisotropies (RCSAs), which then can be employed, on its own, or in combination with Residual Dipolar Couplings (RDCs), for structural elucidation purposes. RCSAs measured using compression devices needed a posteriori correction to account for the increase of the polymer to solvent ratio inside the swollen gel. This correction has been cast before in terms of a single free parameter which, as shown here, can be simultaneously optimized along with the components of the alignment tensor while still retaining discriminating power of the different relative configurations as illustrated in the stereochemical analysis of α-santonin and 10-epi-8-deoxycumambrin B...
January 11, 2018: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29321454/paper-like-surface-microstructure-fabricated-on-a-polymer-surface-by-femtosecond-laser-machining
#8
Kenji Goya, Yusuke Fuchiwaki
In this study, we demonstrate the precise control of fluid flow using femtosecond (FS) laser-induced microstructures. A microgroove structure inscribed on a poly(methyl methacrylate) (PMMA) substrate functions as a superhydrophilic membrane similar to paper. We first estimated the flow rate for pure water on microgrooves fabricated at various laser fluences in the range from 9.2 to 100.8 J/cm2. The results showed that the flow rate could be tuned in the range from 0.30 to 12.07 μL/s by varying the laser irradiation parameters...
2018: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
https://www.readbyqxmd.com/read/29317681/the-effect-of-gravity-on-flame-spread-over-pmma-cylinders
#9
Shmuel Link, Xinyan Huang, Carlos Fernandez-Pello, Sandra Olson, Paul Ferkul
Fire safety is a concern in space travel, particularly with the current plans of increasing the length of the manned space missions, and of using spacecraft atmospheres different than in Earth, such as microgravity, low-velocity gas flow, low pressure and elevated oxygen concentration. In this work, the spread of flame over a thermoplastic polymer, polymethyl methacrylate (PMMA), was conducted in the International Space Station and on Earth. The tests consisted of determining the opposed flame spread rate over PMMA cylinders under low-flow velocities ranging from 0...
January 9, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29316713/fungicidal-pmma-undecylenic-acid-composites
#10
Milica Petrović, Debora Bonvin, Heinrich Hofmann, Marijana Mionić Ebersold
Undecylenic acid (UA), known as antifungal agent, still cannot be used to efficiently modify commercial dental materials in such a way that this affects Candida. Actually, issues with Candida infections and fungal resistance compromise the use of Poly(methyl-methacrylate) (PMMA) as dental material. The challenge remains to turn PMMA into an antifugal material, which can ideally affect both sessile (attached) and planktonic (free-floating) Candida cells. We aimed to tackle this challenge by designing PMMA-UA composites with different UA concentrations (3-12%)...
January 8, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29314058/impact-of-using-scatter-mimicking-beams-instead-of-standard-beams-to-measure-penetration-when-assessing-the-protective-value-of-radiation-protective-garments
#11
A Kyle Jones, Alexander S Pasciak, Louis K Wagner
PURPOSE: Use standardized methods to determine how assessment of protective value of radiation-protective garments changes under conditions employing standard beam qualities, scatter-mimicking primary beams, and a modified Hp (10) measurement. METHODS: The shielding properties of radiation-protective garments depend on the spectrum of beam energies striking the garment and the attenuation properties of materials used to construct the garment, including X-ray fluorescence produced by these materials...
January 3, 2018: Medical Physics
https://www.readbyqxmd.com/read/29312846/role-of-fast-setting-cements-in-arthroplasty-a-comparative-analysis-of-characteristics
#12
Neil Ayron Caraan, Reinhard Windhager, Jason Webb, Nadine Zentgraf, Klaus-Dieter Kuehn
AIM: To evaluate the behaviour of two fast-setting polymethylmethacrylate (PMMA) cements CMW® 2G and Palacos® fast R + G, as reference: Standard-setting Palacos® R + G. METHODS: The fast-setting cements CMW® 2G and Palacos® fast R + G were studied, using standard-setting high viscosity Palacos® R + G as a reference. Eleven units (of two batch numbers) of each cement were tested. All cements were mixed as specified by the manufacturer and analysed on the following parameters: Handling properties (mixing, waiting, working and hardening phase) according to Kuehn, Mechanical properties according to ISO 5833 and DIN 53435, Fatigue strength according to ISO 16402, Benzoyl Peroxide (BPO) - Content by titration, powder/liquid-ratio by weighing, antibiotic elution profile by High Performance Liquid Chromatography...
December 18, 2017: World Journal of Orthopedics
https://www.readbyqxmd.com/read/29311583/nitrogen-implantation-with-a-scanning-electron-microscope
#13
S Becker, N Raatz, St Jankuhn, R John, J Meijer
Established techniques for ion implantation rely on technically advanced and costly machines like particle accelerators that only few research groups possess. We report here about a new and surprisingly simple ion implantation method that is based upon a widespread laboratory instrument: The scanning electron microscope. We show that it can be utilized to ionize atoms and molecules from the restgas by collisions with electrons of the beam and subsequently accelerate and implant them into an insulating sample by the effect of a potential building up at the sample surface...
January 8, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29311417/theoretical-and-experimental-comparison-of-proton-and-helium-beam-radiography-using-silicon-pixel-detectors
#14
Tim Gehrke, Carlo Amato, Simon Berke, Maria Martisikova
Ion-beam radiography (iRAD) could potentially improve the quality control of ion-beam therapy. The main advantage of iRAD is the possibility to directly measure the integrated stopping power. Until now there is no clinical implementation of iRAD. Topics of ongoing research include developing dedicated detection systems to achieve the desired spatial resolution (SR) and investigating different ion types as imaging radiation. This work focuses on the theoretical and experimental comparison of proton (pRAD) and helium-beam radiography (αRAD)...
January 9, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29310879/fracture-analysis-of-cad-cam-high-density-polymers-used-for-interim-implant-supported-fixed-cantilevered-prostheses
#15
Burak Yilmaz, Gülce Alp, Jeremy Seidt, William M Johnston, Roger Vitter, Edwin A McGlumphy
STATEMENT OF PROBLEM: The load-to-fracture performance of computer-assisted design and computer-assisted manufacturing (CAD-CAM) high-density polymer (HDP) materials in cantilevers is unknown. PURPOSE: The purposes of this in vitro study were to evaluate the load-to-fracture performance of CAD-CAM-fabricated HDPs and to compare that with performance of autopolymerized and injection-molded acrylic resins. MATERIAL AND METHODS: Specimens from 8 different brands of CAD-CAM HDPs, including Brylic Solid (BS); Brylic Gradient (BG); AnaxCAD Temp EZ (AE); AnaxCAD Temp Plus (AP); Zirkonzahn Temp Basic (Z); GDS Tempo-CAD (GD); Polident (Po); Merz M-PM-Disc (MAT); an autopolymerized acrylic resin, Imident (Conv) and an injection-molded acrylic resin, SR-IvoBase High Impact (Inj) were evaluated for load-to-fracture analysis (n=5)...
January 5, 2018: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/29303580/determination-of-pmma-based-residues-from-a-chemical-vapor-deposited-monolayer-of-graphene-by-neutron-reflection-and-atomic-force-microscopy
#16
Ruiheng Li, Zongyi Li, Elias Pambou, Philipp Gutfreund, Thomas Andrew Waigh, John Robert Peter Webster, Jian Ren Lu
Chemical vapor deposition (CVD) is now a well-established method to create monolayer graphene films. Poly(methyl methacrylate) (PMMA) film is often coated onto graphene film during production to make it mechanically robust for transfer and further handling. However, it is hard to remove the coated PMMA, and any residual polymers remaining can affect graphene's properties. As it is difficult to characterize the residual PMMA layer we here demonstrate the use of neutron reflection, atomic force microscopy and Raman scattering to determine the amount of the PMMA remaining on the graphene sheet fabricated from CVD...
January 5, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29299472/does-a-simple-syringe-applicator-enhance-bone-cement-set-up-time-in-knee-arthroplasty
#17
Nipun Sodhi, Sarah E Dalton, Anton Khlopas, Assem A Sultan, Gannon L Curtis, Matthew A Harb, Qais Naziri, Jared M Newman, John W Barrington, Michael A Mont
Background: The time required for polymethylmethacrylate (PMMA) cement curing or hardening can be modified by a number of variables including the mixing technique, and the temperature and pressure at which the process is taking place. Therefore, the purpose of this study was to evaluate two different methods of PMMA application in terms of set up time. Specifically, we (I) compared the PMMA set up time of cement that remained in the mixing bowl to cement that was placed in a syringe and (II) extrapolated the associated annual cost difference on the national and individual surgeon levels...
December 2017: Annals of Translational Medicine
https://www.readbyqxmd.com/read/29298047/heteroleptic-copper-i-pseudorotaxanes-incorporating-macrocyclic-phenanthroline-ligands-of-different-sizes
#18
Meera Mohankumar, Michel Holler, Eric Meichsner, Jean-François Nierengarten, Frédéric Niess, Jean-Pierre Sauvage, Béatrice Delavaux-Nicot, Enrico Leoni, Filippo Monti, Joanna M Malicka, Massimo Cocchi, Elisa Bandini, Nicola Armaroli
A series of copper(I) pseudorotaxanes has been prepared from bis[2-(diphenylphosphino)phenyl] ether and macrocyclic phenanthroline ligands with different ring sizes (m30, m37 and m42). Variable temperature studies carried out on the resulting [Cu(mXX)(POP)]+ (mXX = m30, m37 and m42) derivatives have revealed a dynamic conformational equilibrium due to the folding of the macrocyclic ligand. The absorption and luminescence properties of the pseudorotaxanes have been investigated in CH2Cl2. They exhibit metal-to-ligand-charge-transfer (MLCT) emission with photoluminescence quantum yields (PLQYs) in the range 20-30%...
January 3, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29295579/u-shaped-and-surface-functionalized-polymer-optical-fiber-probe-for-glucose-detection
#19
Mikel Azkune, Leire Ruiz-Rubio, Gotzon Aldabaldetreku, Eneko Arrospide, Leyre Pérez-Álvarez, Iñaki Bikandi, Joseba Zubia, Jose Luis Vilas-Vilela
In this work we show an optical fiber evanescent wave absorption probe for glucose detection in different physiological media. High selectivity is achieved by functionalizing the surface of an only-core poly(methyl methacrylate) (PMMA) polymer optical fiber with phenilboronic groups, and enhanced sensitivity by using a U-shaped geometry. Employing a supercontinuum light source and a high-resolution spectrometer, absorption measurements are performed in the broadband visible light spectrum. Experimental results suggest the feasibility of such a fiber probe as a low-cost and selective glucose detector...
December 25, 2017: Sensors
https://www.readbyqxmd.com/read/29291076/synthesis-and-applications-of-mans-poly-mma-co-ba-nanocomposite-latex-by-miniemulsion-polymerization
#20
Sheng Gong, Huayao Chen, Xinhua Zhou, Sundaram Gunasekaran
We have synthesized core-shell structured 3-methacryloxypropyltrimethoxysilane (MPS) functionalized antimony-doped tin oxide nanoparticles (MANs)-poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-BA, PMB) nanocomposite latex particles via miniemulsion polymerization method. Polymerizable anionic surfactant DNS-86 (allyloxy polyoxyethylene(10) nonyl ammonium sulfate) was first introduced to synthesize core-shell nanocomposite. The morphologies of synthesized MANs and MANs/PMB latex nanocomposite particles were studied with transmission electron microscopy, which revealed particles, on average 70 nm in size, with a core-shell structure...
November 2017: Royal Society Open Science
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