Search results for "Materials Testing"
showing 10 items of 254 documents
Mechanical properties of provisional dental materials: A systematic review and meta-analysis
2018
Provisional restorations represent an important phase during the rehabilitation process, knowledge of the mechanical properties of the available materials allows us to predict their clinical performance. At present, there is no systematic review, which supports the clinicians' criteria, in the selection of a specific material over another for a particular clinical situation. The purpose of this systematic review and meta-analysis was to assess and compare the mechanical properties of dimethacrylates and monomethacrylates used in fabricating direct provisional restorations, in terms of flexural strength, fracture toughness and hardness. This review followed the PRISMA guidelines. The searche…
Non-target and suspected-target screening for potentially hazardous chemicals in food contact materials: investigation of paper straws
2020
A non-target screening strategy was developed for the safety evaluation of potentially hazardous chemicals in paper food contact materials (FCMs). A tentative list of suspect analytes was generated using publicly available FCM substance inventories, the presence of contaminants in paper straws was confirmed by high-resolution Orbitrap mass spectrometry. Data-independent and data-dependent MS and MS/MS results for candidate compounds were processed using a workflow including peak detection by deconvolution, blank subtraction, retention time alignment, formula assignment and fragmentation spectra search against spectral libraries followed by
Effects of nano-scaled particles on endothelial cell function in vitro: studies on viability, proliferation and inflammation.
2004
Recent studies give support for a connection between the presence of inorganic particles (of microm and nm size) in different organs and tissues and the development of inflammatory foci, called granulomas. As the potential source of particles (e.g. porcelain dental bridges) and the location of particle detection were topographically far apart, a distribution via the blood stream appears highly probable. Thus, endothelial cells, which line the inner surface of blood vessels, would come into direct contact with these particles, making particle-endothelial interactions potentially pathogenically relevant. The objective of this study was to evaluate the effects that five different nano-scaled p…
Potential lack of "standardized" processing techniques for production of allogeneic and xenogeneic bone blocks for application in humans.
2013
In the present study, the structure of two allogeneic and three xenogeneic bone blocks, which are used in dental and orthopedic surgery, were histologically analyzed. The ultimate goal was to assess whether the components postulated by the manufacturer can be identified after applying conventional histological and histochemical staining techniques. Three samples of each material, i.e. allogeneic material-1 and -2 as well as xenogeneic material-1, -2 and -3, were obtained commercially. After decalcification and standardized embedding processes, conventional histological staining was performed in order to detect inorganic matrix, cellular or organic matrix components. Allogeneic material-1 sh…
Adhesion prophylaxis using a copolymer with rationally designed material properties.
2008
Physical barriers are the only licensed adjuncts for adhesion prophylaxis in the United States and Europe. Here, we investigate D,L-polylactide-epsilon-caprolactonetrimethylenecarbonate (PCT copolymer), which is a rationally designed biomaterial, as an adhesion barrier.PCT copolymer membranes were produced by polymerization of the monomers, dissolution in organic solvents, and subsequently processing them by means of modified phase inversion and freeze drying. In vitro cytotoxicity was assayed by fibroblast culture. In vivo adhesion prophylaxis was studied in a rat model that involved standardized traumatization by electrocautery and suturing. The quantity and quality of the resulting adhes…
Acoustically driven photon antibunching in nanowires.
2011
The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited carriers, as well as to spatially control exciton recombination in GaAs-based nanowires (NWs) on a subns time scale. The experiments are carried out in core-shell NWs transferred to a SAW delay line on a LiNbO(3) crystal. Carriers generated in the NW by a focused laser spot are acoustically transferred to a second location, leading to the remote emission of subns light pulses synchronized with the SAW phase. The dynamics of the carrier transport, investigated using spatially and time-resolved photoluminescence, is well-reproduced by computer simulations. The high-frequency contactless …
Diffusion between evolving interfaces
2010
Diffusion in an evolving environment is studied by continuos-time Monte Carlo simulations. Diffusion is modelled by continuos-time random walkers on a lattice, in a dynamic environment provided by bubbles between two one-dimensional interfaces driven symmetrically towards each other. For one-dimensional random walkers constrained by the interfaces, the bubble size distribution domi- nates diffusion. For two-dimensional random walkers, it is also controlled by the topography and dynamics of the interfaces. The results of the one-dimensional case are recovered in the limit where the interfaces are strongly driven. Even with simple hard-core repulsion between the interfaces and the particles, …
Establishment of a pulmonary epithelial barrier on biodegradable poly-L-lactic-acid membranes
2019
Development of biocompatible and functional scaffolds for tissue engineering is a major challenge, especially for development of polarised epithelia that are critical structures in tissue homeostasis. Different in vitro models of the lung epithelial barrier have been characterized using non-degradable polyethylene terephthalate membranes which limits their uses for tissue engineering. Although poly-L-lactic acid (PLLA) membranes are biodegradable, those prepared via conventional Diffusion Induced Phase Separation (DIPS) lack open-porous geometry and show limited permeability compromising their use for epithelial barrier studies. Here we used PLLA membranes prepared via a modification of the…
Cationic polyaspartamide-based nanocomplexes mediate siRNA entry and down-regulation of the pro-inflammatory mediator high mobility group box 1 in ai…
2015
Abstract High-mobility group box 1 (HMGB1) is a nonhistone protein secreted by airway epithelial cells in hyperinflammatory diseases such as asthma. In order to down-regulate HMGB1 expression in airway epithelial cells, siRNA directed against HMGB1 was delivered through nanocomplexes based on a cationic copolymer of poly(N-2-hydroxyethyl)- d,l -aspartamide (PHEA) by using H441 cells. Two copolymers were used in these experiments bearing respectively spermine side chains (PHEA-Spm) and both spermine and PEG2000 chains (PHEA-PEG-Spm). PHEA-Spm and PHEA-PEG-Spm derivatives complexed dsDNA oligonucleotides with a w/w ratio of 1 and higher as shown by a gel retardation assay. PHEA-Spm and PHEA-P…
Amphiphilic Copolymers Based on Poly[(hydroxyethyl)-d,l-aspartamide]: A Suitable Functional Coating for Biocompatible Gold Nanostars
2013
Novel amphiphilic copolymers have been synthesized based on a biocompatible poly(hydroxyethylaspartamide) (PHEA) backbone, bearing both anchoring groups for gold nanoparticles, such as thiols and disulfide, and conjugable moieties, such as amino groups, the latter as points suitable for appending further functional agents. The strategy was to functionalize α,β-poly[(N-2- hydroxyethyl)-d,l-aspartamide] (PHEA) with PEG2000-NH2 and with ethylenediamine (EDA) obtaining a partially pegylated copolymer with a large number of pendant primary amino groups. A fraction of the latter was conjugated with molecules bearing terminal thiol moieties such as 12-mercaptododecanoic acid (MDA) and disulfide gr…