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Anesthesiology Aug 2012
Topics: Aged; Bone Cements; Diagnosis, Differential; Female; Foreign Bodies; Heart Ventricles; Humans; Hypotension; Hypoxia; Methylmethacrylate; Pulmonary Embolism; Radiography; Syndrome; Tachycardia, Ventricular; Thoracic Vertebrae; Treatment Outcome; Ultrasonography
PubMed: 22388069
DOI: 10.1097/ALN.0b013e31824de99a -
Materials Science & Engineering. C,... Sep 2020The aim of this study was to investigate the monomer absorption behavior of decellularized dermis and prepare a gradient-type decellularized dermis-polymer complex....
The aim of this study was to investigate the monomer absorption behavior of decellularized dermis and prepare a gradient-type decellularized dermis-polymer complex. Decellularized dermis was prepared using sodium dodecyl sulfate, and its monomer absorption behavior was investigated using three types of hydrophobic monomer with different surface free energies. The results show that monomer absorption depends strongly on the tissue structure, regardless of the surface free energy, and the amount of absorbed monomer can be increased by sonication. Based on these results, we prepared a gradient-type decellularized dermis-poly(methyl methacrylate) complex by controlling the permeation time of the methyl methacrylate monomer and polymerization initiator into the decellularized dermis. The mechanical strength of this complex gradually increased from the dermis side to the polymer side, and combined the physical characteristics of the dermis and the polymer.
Topics: Polymerization; Polymers; Polymethyl Methacrylate; Sodium Dodecyl Sulfate
PubMed: 32993989
DOI: 10.1016/j.msec.2020.111017 -
Physica Medica : PM : An International... Sep 2022Hyperthermia is a cancer treatment in which the target region is heated to temperatures of 40-44 °C usually applying external electromagnetic field sources. The...
PURPOSE
Hyperthermia is a cancer treatment in which the target region is heated to temperatures of 40-44 °C usually applying external electromagnetic field sources. The behavior of the hyperthermia applicators (antennas) in clinical practice should be periodically checked with phantom experiments to verify the applicator's performance over time. The purpose of this study was to investigate the application of photogrammetry reconstructions of 3D applicator position in these quality control procedure measurements.
METHODS
Photogrammetry reconstruction was applied at superficial hyperthermia scenario using the Lucite cone applicator (LCA) and phased-array heating in the head and neck region using the HYPERcollar3D. Wire-frame models of the entire measurement setups were created from multiple-view images and used for recreation of the setup inside 3D electromagnetic field simulation software. We evaluated applicator relation (R) between measured and simulated absolute specific absorption rate (SAR) for manually created and photogrammetry reconstructed simulation setups.
RESULTS
We found a displacement of 7.9 mm for the LCA and 8.2 mm for the HYPERcollar3D setups when comparing manually created and photogrammetry reconstructed applicator models placements. R improved from 1.24 to 1.18 for the LCA and from 1.17 to 1.07 for the HYPERcollar3D when using photogrammetry reconstructed simulation setups.
CONCLUSION
Photogrammetry reconstruction technique holds promise to improve measurement setup reconstruction and agreement between measured and simulated absolute SAR.
Topics: Hyperthermia, Induced; Phantoms, Imaging; Photogrammetry; Polymethyl Methacrylate; Quality Control
PubMed: 35987024
DOI: 10.1016/j.ejmp.2022.08.008 -
Archives of Toxicology Apr 2023This review addresses the need for a framework to increase the consistency, objectivity and transparency in the regulatory assessment of respiratory sensitisers and... (Review)
Review
This review addresses the need for a framework to increase the consistency, objectivity and transparency in the regulatory assessment of respiratory sensitisers and associated uncertainties. Principal issues are considered and illustrated through a case study (with methyl methacrylate). In the absence of test methods validated for regulatory use, formal documentation of the weight-of-evidence for hazard classification both at the level of integration of individual studies within lines of evidence and across a broad range of data streams was agreed to be critical for such a framework. An integrated approach is proposed to include not only occupational studies and clinical evidence for the regulatory assessment of respiratory sensitisers, but also information on structure and physical and chemical factors, predictive approaches such as structure activity analysis and in vitro and in vivo mechanistic and toxicokinetic findings. A weight-of-evidence protocol, incorporating integration of these sources of data based on predefined considerations, would contribute to transparency and consistency in the outcome of the assessment. In those cases where a decision may need to be taken on the basis of occupational findings alone, conclusions should be based on transparent weighting of relevant data on the observed prevalence of occupational asthma in various studies taking into account all relevant information including the range and nature of workplace exposures to the substance of interest, co-exposure to other chemicals and study quality.
Topics: Methylmethacrylate; Risk Assessment; Uncertainty; Methacrylates
PubMed: 36797432
DOI: 10.1007/s00204-023-03448-w -
Anaesthesia Feb 1989
Topics: Animals; Bone Cements; Bronchial Spasm; Chick Embryo; Female; Hip Prosthesis; Humans; Intraoperative Complications; Methylmethacrylate; Methylmethacrylates
PubMed: 2929964
DOI: 10.1111/j.1365-2044.1989.tb11215.x -
Molecules (Basel, Switzerland) Aug 2022To investigate the utility of acrylic monomers from various plant oils in adhesives manufacturing, 25-45 wt. % of high oleic soybean oil-based monomer (HOSBM) was...
To investigate the utility of acrylic monomers from various plant oils in adhesives manufacturing, 25-45 wt. % of high oleic soybean oil-based monomer (HOSBM) was copolymerized in a miniemulsion with commercially applied butyl acrylate (BA), methyl methacrylate (MMA), or styrene (St). The compositions of the resulting ternary latex copolymers were varied in terms of both "soft" (HOSBM, BA) and "rigid" (MMA or St) macromolecular fragments, while total monomer conversion and molecular weight of copolymers were determined after synthesis. For most latexes, results indicated the presence of lower and higher molecular weight fractions, which is beneficial for the material adhesive performance. To correlate surface properties and adhesive performance of HOSBM-based copolymer latexes, contact angle hysteresis (using water as a contact liquid) for each latex-substrate pair was first determined. The data showed that plant oil-based latexes exhibit a clear ability to spread and adhere once applied on the surface of materials differing by polarities, such as semicrystalline polyethylene terephthalate (PET), polypropylene (PP), bleached paperboard (uncoated), and tops coated with a clay mineral paperboard. The effectiveness of plant oil-based ternary latexes as adhesives was demonstrated on PET to PP and coated to uncoated paperboard substrates. As a result, the latexes with high biobased content developed in this study provide promising adhesive performance, causing substrate failure instead of cohesive/adhesive break in many experiments.
Topics: Adhesives; Latex; Methylmethacrylate; Plant Oils; Polymers; Soybean Oil; Styrene
PubMed: 36014411
DOI: 10.3390/molecules27165170 -
International Journal of Molecular... Apr 2010Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate,...
Herein, we report the synthesis of monomethacryloyl sucrose esters, and their successful free radical homo- and co-polymerisation with styrene, methylmethacrylate, α-and β-pinene. The chemical, physical, structural and surface chemical properties of these polymers, containing a hydrophobic olefin backbone and hydrophilic sugar moieties as side chains, have been investigated. Biodegradation tests of the copolymer samples by a microbial fungal culture (Aspergillus niger) method showed good biodegradability. The chemical structure and surface chemistry of the synthesized homo- and co-polymers demonstrate their potential technological relevance as amphiphilic and biodegradable polymers.
Topics: Aspergillus niger; Bicyclic Monoterpenes; Biodegradation, Environmental; Bridged Bicyclo Compounds; Esters; Free Radicals; Hydrophobic and Hydrophilic Interactions; Methylmethacrylate; Monoterpenes; Polymerization; Polymers; Styrene; Sucrose
PubMed: 20480042
DOI: 10.3390/ijms11041792 -
Journal of the Mechanical Behavior of... Jul 2023With global demand for 3D printed medical devices on the rise, the search for safer, inexpensive, and sustainable methods is timely. Herein, we assessed the practicality...
With global demand for 3D printed medical devices on the rise, the search for safer, inexpensive, and sustainable methods is timely. Herein, we assessed the practicality of the material extrusion process for acrylic denture bases of which successful outcomes can be extended to implant surgical guides, orthodontic splints, impression trays, record bases and obturators for cleft palates or other maxillary defects. Representative materials comprising denture prototypes and test samples were designed and built with in-house polymethylmethacrylate filaments using varying print directions (PDs), layer heights (LHs) and reinforcements (RFs) with short glass fiber. The study undertook a comprehensive evaluation of the materials to determine their flexural, fracture, and thermal properties. Additional analyses for tensile and compressive properties, chemical composition, residual monomer, and surface roughness (Ra) were completed for parts with optimum parameters. Micrographic analysis of the acrylic composites revealed adequate fiber-matrix compatibility and predictably, their mechanical properties improved simultaneously with RFs and decreased LHs. Fiber reinforcement also improved the overall thermal conductivity of the materials. Ra, on the other hand, improved visibly with decreased RFs and LHs and the prototypes were effortlessly polished and characterized with veneering composites to mimic gingival tissues. In terms of chemical stability, the residual methyl methacrylate monomer contents are well below standards threshold for biological reactions. Notably, 5 vol% acrylic composites built with 0.05 mm LH in 0° on z-axis produced optimum properties that are superior to those of conventional acrylic, milled acrylic and 3D printed photopolymers. Finite element modeling successfully replicated the tensile properties of the prototypes. It may well be argued that the material extrusion process is cost-effective; however, the speed of manufacturing could be longer than that of established methods. Although the mean Ra is within an acceptable range, mandatory manual finishing and aesthetic pigmentation are required for long-term intraoral use. At a proof-of-concept level, it is evident that the material extrusion process can be applied to build inexpensive, safe, and robust thermoplastic acrylic devices. The broad outcomes of this novel study are equally worthy of academic reflection, and further translation to the clinic.
Topics: Acrylic Resins; Feasibility Studies; Polymethyl Methacrylate; Methylmethacrylate; Denture Bases; Materials Testing; Surface Properties
PubMed: 37285773
DOI: 10.1016/j.jmbbm.2023.105950 -
Translational Vision Science &... Dec 2020To evaluate titanium (Ti) sputtering of the poly(methyl methacrylate) (PMMA) stem of the Boston Keratoprosthesis (BK) as a method to enhance interfacial adhesion between...
PURPOSE
To evaluate titanium (Ti) sputtering of the poly(methyl methacrylate) (PMMA) stem of the Boston Keratoprosthesis (BK) as a method to enhance interfacial adhesion between the PMMA and the recipient corneal tissue.
METHODS
PMMA specimens were plasma treated with Ar/O and coated with Ti using a DC magnetron sputtering instrument. The topography and hydrophilicity of the surfaces were characterized using atomic force microscopy and a water contact angle instrument, respectively. Scratch hardness and adhesion of the Ti film were measured using a mechanical tester. Biocompatibility assessments were performed using cultured human corneal fibroblasts and whole blood ex vivo. The optical quality of the Ti sputtered BK was evaluated using a custom-made optical bench.
RESULTS
By contact angle studies, the Ti coating improved PMMA hydrophilicity to match that of medical-grade Ti (Ti-6Al-4V-ELI). Ti sputtering of contact surfaces resulted in a plate-like morphology with increased surface roughness, without impacting the transparency of the BK optical component. Scratch testing indicated that the mechanical behavior of the Ti coating was similar to that of casted Ti, and the coating was stable in pull-off adhesion testing. Sputtered Ti film was highly biocompatible based on tests of cell viability, adhesion, proliferation, differentiation, collagen deposition, and keratocan expression, the properties of which exceeded those of uncoated PMMA and did not induce increased complement activation.
CONCLUSIONS
Titanium coating of the BK stem generated a mechanically and biologically favorable interface, which may help to enhance corneal stromal adhesion and biocompatibility.
TRANSLATIONAL RELEVANCE
Improving the biocompatibility of the BK PMMA stem may improve long-term outcomes of implantation.
Topics: Cornea; Humans; Polymethyl Methacrylate; Prostheses and Implants; Surface Properties; Titanium
PubMed: 33442495
DOI: 10.1167/tvst.9.13.41 -
The Journal of Prosthetic Dentistry Mar 2017Polyetheretherketone (PEEK) can be used as a framework material for fixed dental prostheses. However, information about laboratory and chairside polishing methods is...
STATEMENT OF PROBLEM
Polyetheretherketone (PEEK) can be used as a framework material for fixed dental prostheses. However, information about laboratory and chairside polishing methods is still scarce.
PURPOSE
The purpose of this in vitro study was to determine the effects of laboratory and chairside polishing methods on the surface roughness (SR) and surface free energy (SFE) of PEEK, an autopolymerizing poly(methyl methacrylate), and a veneering composite resin.
MATERIAL AND METHODS
For each of the 3 materials, 80 specimens were prepared (N=240) and divided into 7 polishing groups and 1 control group (n=10). The 7 groups were split into 4 laboratory protocols: polishing paste (Abraso), a second polishing paste (Opal L), silicone polisher (Ceragum), and diamond grinder (Diagen-Turbo grinder). The other 3 groups were chairside protocols: rainbow technique (Super-Snap kit), polishing paste (Prisma gloss), and a polishing system (Enhance finishing). Machine polishing with SiC P4000 served as the control treatment. The protocols' average SRs and SFEs were measured, and their surface topographies were evaluated with scanning electron microscopy (SEM). The logarithmically transformed data were analyzed using covariance analysis, 2-way and 1-way ANOVA, and partial correlation (α=.05).
RESULTS
The polishing protocol exerted the highest influence on SR and SFE values (P<.001; SR: partial eta squared η=.970; SFE: η=.450), followed by material group (P<.001, SR: η=.319; SFE: η=.429). The interaction effect of the binary combinations of the 2 independent parameters (polishing protocol and material group) was also significant (P<.001, SR: η=.681; SFE: η=.365).
CONCLUSIONS
Chairside methods presented lower SR values than laboratory methods, and specimens polished using the 2-body mode showed higher SR than did specimens polished using the 3-body mode.
Topics: Benzophenones; Composite Resins; Dental Materials; Dental Polishing; Diamond; Equipment Design; Humans; Ketones; Laboratories, Dental; Materials Testing; Methylmethacrylate; Microscopy, Electron, Scanning; Polyethylene Glycols; Polymers; Silicones; Surface Properties
PubMed: 27692577
DOI: 10.1016/j.prosdent.2016.06.016