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https://www.readbyqxmd.com/read/28343651/reconstruction-of-large-cranial-defects-with-poly-methyl-methacrylate-pmma-using-a-rapid-prototyping-model-and-a-new-technique-for-intraoperative-implant-modeling
#1
Claudia Unterhofer, Christoph Wipplinger, Michael Verius, Wolfgang Recheis, Claudius Thomé, Martin Ortler
BACKGROUND: Reconstruction of large cranial defects after craniectomy can be accomplished by free-hand poly-methyl-methacrylate (PMMA) or industrially manufactured implants. The free-hand technique often does not achieve satisfactory cosmetic results but is inexpensive. In an attempt to combine the accuracy of specifically manufactured implants with low cost of PMMA. METHODS: Forty-six consecutive patients with large skull defects after trauma or infection were retrospectively analyzed...
March 10, 2017: Neurologia i Neurochirurgia Polska
https://www.readbyqxmd.com/read/28338980/a-multi-element-thick-gas-electron-multiplier-based-microdosemeter-for-measurement-of-neutrons-dose-equivalent-a-monte-carlo-study
#2
A Moslehi, G Raisali
To determine the dose-equivalent of neutrons in an extended energy range, in the present work a multi-element thick gas electron multiplier-based microdosemeter made of PMMA (Perspex) walls of 10 mm in thickness is designed. Each cavity is filled with the propane-based tissue-equivalent (TE) gas simulating 1 µm of tissue. Also, a few weight fractions of 3He are assumed to be added to the TE gas. The dose-equivalents are determined for 11 neutron energies between thermal and 14 MeV using the lineal energy distributions calculated by Geant4 simulation toolkit and also the lineal energy-based quality factors...
March 14, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28336032/evidence-appraisal-of-koh-bth-tan-jh-ramruttun-ak-wang-w-effect-of-storage-temperature-and-equilibration-time-on-polymethyl-methacrylate-pmma-bone-cement-polymerization-in-joint-replacement-surgery-j-orthop-surg-res-2015-10-1-178-doi-10-1186-s13018-015-0320
#3
https://www.readbyqxmd.com/read/28335270/review-of-recent-developments-on-using-an-off-lattice-monte-carlo-approach-to-predict-the-effective-thermal-conductivity-of-composite-systems-with-complex-structures
#4
REVIEW
Feng Gong, Hai M Duong, Dimitrios V Papavassiliou
Here, we present a review of recent developments for an off-lattice Monte Carlo approach used to investigate the thermal transport properties of multiphase composites with complex structure. The thermal energy was quantified by a large number of randomly moving thermal walkers. Different modes of heat conduction were modeled in appropriate ways. The diffusive heat conduction in the polymer matrix was modeled with random Brownian motion of thermal walkers within the polymer, and the ballistic heat transfer within the carbon nanotubes (CNTs) was modeled by assigning infinite speed of thermal walkers in the CNTs...
July 30, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28333052/pmma-titania-floating-macrospheres-for-the-photocatalytic-remediation-of-agro-pharmaceutical-wastewater
#5
Adam C Hartley, Joseph B Moss, Kyle J Keesling, Nathanael J Moore, Justin D Glover, Joel E Boyd
Antibiotics such as tetracycline are used on a large scale in agriculture, and can become concentrated in wastewater lagoons that are used in conjunction with confined animal feeding operations. Solar-illuminated titanium dioxide can be used to photocatalytically degrade aqueous tetracycline, but its application in a lagoon environment requires that the photocatalyst be supported on a macroscopic support material to prevent loss of the nanoscale photocatalyst into the environment. In this work, titanium dioxide was deposited within a porous poly(methyl methacrylate) film on the surface of floating 7...
March 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28333042/minocycline-releasing-pmma-system-as-a-space-maintainer-for-staged-bone-reconstructions-in-vitro-antibacterial-cytocompatibility-and-anti-inflammatory-characterization
#6
Tiago Silva, Liliana Grenho, Joana Barros, José Silva, Rosana Pinto, Ana Matos, Bruno Colaço, Helena Fernandes, Ana Bettencourt, Pedro S Gomes
In the present work, it is aimed the development and biological characterization of a poly methyl methacrylate (PMMA)-based minocycline delivery system, to be used as a space maintainer within craniofacial staged regenerative interventions. Developed delivery systems were characterized regarding solid state characteristics and assayed in vitro for anti-bacterial and anti-inflammatory activity, and cytocompatibility with human bone cells. Drug release profile allowed for an initial burst release and a more sustained and controlled release over time, with minimum inhibitory concentrations for the assayed and relevant pathogenic bacteria (i...
March 23, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28332741/robust-stimuli-responsive-membranes-prepared-from-a-blend-of-polysulfone-and-a-graft-copolymer-bearing-binary-side-chains-with-thermo-and-ph-responsive-switching-behavior
#7
Lei Miao, Yuanyuan Tu, Yang Yang, Shudong Lin, J W Hu, Min Zhang, Yue Li, Fei Li, Yangmiao Mo
Reported herein is the fabrication of a stimuli-responsive membrane exhibiting independent pH- and temperature-responsive behavior that was prepared from a blend of commercial polysulfone with a functional amphiphilic binary graft copolymer denoted as polysulfone-graft-(poly(isopropylacrylamide-co-acrylic acid)-random-poly(methyl acrylate) (or PSf-g-(P(NIPAAm-co-AA)-r-PMMA)). This series of two graft copolymers with different lengths of P(NIPAAm-co-AA) side-chains were respectively designed and enriched on the membrane surface to serve as thermo- and pH-responsive "on/off" switches...
March 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28331309/in-vitro-and-in-vivo-drug-release-and-antibacterial-properties-of-the-novel-vancomycin-loaded-bone-like-hydroxyapatite-poly-amino-acid-scaffold
#8
Zhidong Cao, Dianming Jiang, Ling Yan, Jun Wu
Antibiotic-loaded carriers were developed to fill cavities and locally deliver antibiotics following implantation. However, the most commonly used antibiotic carrier, polymethyl methacrylate (PMMA), has many disadvantages including that it does not promote bone regeneration or conduction. Vancomycin-loaded bone-like hydroxyapatite/poly amino acid (V-BHA/PAA) was successfully fabricated by a homogeneous method, certified as biosafe and known to promote osteogenesis. To evaluate its drug-release features, the quantity of the vancomycin in the elution was obtained every 2 days after in vitro simulated body fluid immersion...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28327766/phosphorescent-platinum-ii-alkynyls-end-capped-with-benzothiazole-units
#9
Rebeca Lara, Elena Lalinde, M Teresa Moreno
Symmetric trans-bis(alkynyl)bis(phosphine) Pt(II) complexes based on the 2-phenylbenzothiazole (pbt) unit [trans-Pt(C[triple bond, length as m-dash]C-pbt)2L2] [L = PPh31, PEt32, 1,3,5-triaza-7-phosphaadamantane (PTA) 3] and the mixed alkynyl-cyanide anionic complex (NBu4)2[trans-Pt(C[triple bond, length as m-dash]C-pbt)2(CN)2] (4) were synthesized. The complexes have been fully characterized including X-ray crystallography for 2 and 4. All complexes display long-lived emission with moderate quantum yields (ϕ 6...
March 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28326230/methods-for-preparing-polymer-decorated-single-exchange-biased-magnetic-nanoparticles-for-application-in-flexible-polymer-based-films
#10
Laurence Ourry, Delphine Toulemon, Souad Ammar, Fayna Mammeri
Background: Magnetic nanoparticles (NPs) must not only be well-defined in composition, shape and size to exhibit the desired properties (e.g., exchange-bias for thermal stability of the magnetization) but also judiciously functionalized to ensure their stability in air and their compatibility with a polymer matrix, in order to avoid aggregation which may seriously affect their physical properties. Dipolar interactions between NPs too close to each other favour a collective magnetic glass state with lower magnetization and coercivity because of inhomogeneous and frustrated macrospin cluster freezing...
2017: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/28325683/biomimetic-scaffolds-with-three-dimensional-undulated-microtopographies
#11
Jonelle Z Yu, Emrullah Korkmaz, Monica I Berg, Philip R LeDuc, O Burak Ozdoganlar
Many human and animal tissues naturally possess three-dimensional (3D) micro-scale geometries enabling certain physiological functions. Absence of these microgeometries in engineered tissues may undermine the effectiveness of corresponding tissue repair and regeneration. This paper introduces a novel approach to create tissue scaffolds with biomimetic 3D undulated microtopographies. The mechanical micromilling technology is used for precise and reproducible fabrication of poly(methyl methacrylate) (PMMA) master molds with 3D undulated microtopographies...
February 14, 2017: Biomaterials
https://www.readbyqxmd.com/read/28324215/surgical-treatment-of-osteoporotic-thoraco-lumbar-compressive-fractures-the-use-of-pedicle-screw-with-augmentation-pmma
#12
Massimo Girardo, P Cinnella, G Gargiulo, P Viglierchio, A Rava, S Aleotti
INTRODUCTION: The osteoporosis prevalence in population is age related. The aim of this single-center observational study was evaluate the middle- to long-term performance of cement (PMMA) augmented fenestrated pedicle screws in elderly patients with thoraco-lumbar compressive fractures by osteoporosis. MATERIALS AND METHODS: From 2011 to 2015 we treated 52 patients (20 males and 32 females) suffering from somatic osteoporotic fractures (T10-L2). The average age was 73...
March 21, 2017: European Spine Journal
https://www.readbyqxmd.com/read/28323714/osteointegration-and-resorption-of-intravertebral-and-extravertebral-calcium-phosphate-cement
#13
Roman Klein, Ralf Tetzlaff, Christel Weiss, Meike-Kristina Schäfer, Michael Tanner, Bernd Wiedenhöfer, Ingo Grafe, Peter-Jürgen Meeder, Gerd Noeldge, Peter P Nawroth, Christian Kasperk
STUDY DESIGN: Eleven patients with painful osteoporotic vertebral fractures who underwent kyphoplasty using calcium phosphate (CaP) cement were followed up for 1 week, 1, 2, and 3 years in a monocentric, nonrandomized, noncontrolled retrospective trial. OBJECTIVE: This study investigates long-term radiomorphologic features of intraosseous CaP cement implants and of extraosseous CaP cement leakages for up to 3 years after implantation by kyphoplasty. SUMMARY OF BACKGROUND DATA: Kyphoplasty is frequently used for the treatment of painful osteoporotic fractures...
April 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28323708/fenestrated-screws-augmented-with-pmma-increase-the-pullout-strength-of-sacral-pedicle-screws
#14
Matthew Colman, Jonathan Pond, Kent Bachus, Brandon D Lawrence, William R Spiker, Darrel S Brodke
STUDY DESIGN: Biomechanics. OBJECTIVE: The objective of this study was to compare the fixation in osteoporotic specimens of a bicortical sacral pedicle screw to the following constructs: a unicortical solid screw augmented with polymethylmethacrylate (PMMA) (TRACT), a unicortical fenestrated screw augmented with PMMA (FEN), and a bicortical screw/sacral alar screw combination (PED/ALA). SUMMARY OF BACKGROUND DATA: Rigid posterior sacral fixation of osteoporotic spines is problematic due to poor bone quality...
April 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28321636/the-effect-of-cement-on-hip-stem-fixation-a-biomechanical-study
#15
Talip Çelik, İbrahim Mutlu, Arif Özkan, Yasin Kişioğlu
This study presents the numerical analysis of stem fixation in hip surgery using with/without cement methods since the use of cement is still controversial based on the clinical studies in the literature. Many different factors such as stress shielding, aseptic loosening, material properties of the stem, surgeon experiences etc. play an important role in the failure of the stem fixations. The stem fixation methods, cemented and uncemented, were evaluated in terms of mechanical failure aspects using computerized finite element method...
March 20, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28319031/evaluation-of-the-water-equivalence-of-plastic-materials-in-low-and-high-energy-clinical-proton-beams
#16
Ana Lourenco, David Shipley, Nigel Wellock, Russell Thomas, Hugo Bouchard, Andrzej Kacperek, Francesco Fracchiolla, Stefano Lorentini, Marco Schwarz, Niall MacDougall, Gary Royle, Hugo Palmans
The aim of this work was to evaluate the water-equivalence of new trial plastics designed specifically for light-ion beam dosimetry as well as commercially available plastics in clinical proton beams. The water-equivalence of materials was tested by computing a plastic-to-water conversion factor, <i>H</i><sub><i>pl</i>,w</sub>. Trial materials were characterized experimentally in 60 MeV and 226 MeV un-modulated proton beams and the results were compared with Monte Carlo simulations using the FLUKA code...
March 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28317834/raman-sensitive-degradation-and-etching-dynamics-of-exfoliated-black-phosphorus
#17
Fadhel Alsaffar, Sarah Alodan, Abdul Alrasheed, Abdulrahman Alhussain, Noura Alrubaiq, Ahmad Abbas, Moh R Amer
Layered black phosphorus has drawn much attention due to the existence of a band gap compared to the widely known graphene. However, environmental stability of black phosphorus is still a major issue, which hinders the realization of practical device applications. Here, we spatially Raman map exfoliated black phosphorus using confocal fast-scanning technique at different time intervals. We observe a Raman intensity modulation for , B2g, and modes. This Raman modulation is found to be caused by optical interference, which gives insights into the oxidation mechanism...
March 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28316344/mechanoluminescent-imaging-of-osmotic-stress-induced-damage-in-a-glassy-polymer-network
#18
Jess M Clough, Jasper van der Gucht, Rint P Sijbesma
A chemiluminescent mechanophore, bis(adamantyl-1,2-dioxetane), is used to investigate the covalent bond scission resulting from the sorption of chloroform by glassy poly(methyl methacrylate) (PMMA) networks. Bis(adamantyl)-1,2-dioxetane units incorporated as cross-linkers underwent mechanoluminescent scission, demonstrating that solvent ingress caused covalent bond scission. At higher cross-linking densities, the light emission took the form of hundreds of discrete bursts, widely varying in intensity, with each burst composed of 10(7)-10(9) photons...
March 14, 2017: Macromolecules
https://www.readbyqxmd.com/read/28306517/biomechanical-analysis-of-stiffness-and-fracture-displacement-after-using-pmma-augmented-sacroiliac-screw-fixation-for-sacrum-fractures
#19
Andreas Höch, Richard Schimpf, Niels Hammer, Stefan Schleifenbaum, Michael Werner, Christoph Josten, Jörg Böhme
Cement augmentation of pedicle screws is the gold standard for the stabilization of osteoporotic fractures of the spine. In-screw cement augmentation, in which cement is injected through the cannula, is another option for fracture stabilization of fragility fractures of the sacrum. However, biomechanical superiority of this technique compared to conventional sacroiliac screw fixation has not been tested. The present study compares the stability of cement-augmented and non-cement-augmented sacroiliac screw fixation in osteoporotic sacrum fractures under cyclic loading...
March 15, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28303063/a-case-report-of-idiopathic-iliopsoas-hematoma-which-occurred-soon-after-transfer-to-the-wheelchair-after-total-hip-arthroplasty
#20
Tomoo Okumura, Hiroshi Fujita, Hideto Harada, Ryuuichi Nishimura, Tomohiro Tominaga
A 79-year-old woman was diagnosed with osteoarthritis of the left hip and scheduled for total hip arthroplasty. As two lesions were detected in branches of the coronary arteries, she was treated with catheter treatment. The patient was receiving anticoagulant treatment, which was suspended eight days before the operation; however, heparin was started at 6 days before the operation and was stopped 9 hours before the operation. On the 2nd postoperative day soon after transfer to the wheel chair, she was feeling unwell and was suffering from severe pain in her left buttock and left thigh...
February 2017: Nagoya Journal of Medical Science
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