471 research outputs found
epsilon-Caprolactone in Micro-Chambered Ceramic Beads - A New Carrier for Gentamicin
Purpose: The purpose of this preliminary and descriptive study was toevaluate a biodegradable drug delivery system in combination with aninnovative ceramic implant. Methods: The delivery of gentamicin ofstandardized samples was measured in the laboratory usingultra-high-performance liquid chromatography. Biocompatibility andbiodegradation of the materials was investigated in an animal experimentin sheep up to 14 months. As carrier epsilon-caprolactone, 1:1 mixedwith gentamicin, intruded into micro-chambered beta-tricalcium-phosphatebeads (MCB (R)) was studied. Results and Discussion: Gentamicin wasreleased in calculable concentrations during the first 30 days. Therelease from epsilon-caprolactone was higher than that frompolymethylmethacrylate and more predictable. The caprolactone carrierwas reabsorbed by osteoclasts
Effectiveness of 4 Pulpotomy Techniques—Randomized Controlled Trial
Pulpotomy is the accepted therapy for the management of cariously exposed pulps in symptom-free primary molars; however, evidence is lacking about the most appropriate technique. The aim of this study was to compare the relative effectiveness of the Er:YAG laser, calcium hydroxide, and ferric sulfate techniques with that of dilute formocresol in retaining such molars symptom-free. Two hundred primary molars in 107 healthy children were included and randomly allocated to one of the techniques. The treated teeth were blindly re-evaluated after 6, 12, 18, and 24 months. Descriptive data analysis and logistic regression analysis, accounting for each patient's effect by a generalized estimating equation (GEE), were used. After 24 months, the following total and clinical success rates were determined (%): formocresol 85 (96), laser 78 (93), calcium hydroxide 53 (87), and ferric sulfate 86 (100). Only calcium hydroxide performed significantly worse than formocresol (p = 0.001, odds ratio = 5.6, 95% confidence interval 2.0-15.5). In conclusion, calcium hydroxide is less appropriate for pulpotomies than is formocresol
Effect of Aqueous Ozone on the NF-κB System
Ozone has been proposed as an alternative oral antiseptic in dentistry, due to its antimicrobial power reported for gaseous and aqueous forms, the latter showing a high biocompatibility with mammalian cells. New therapeutic strategies for the treatment of periodontal disease and apical periodontitis should consider not only antibacterial effects, but also their influence on the host immune response. Therefore, our aim was to investigate the effect of aqueous ozone on the NF-κB system, a paradigm for inflammationassociated signaling/transcription. We showed that NF-κB activity in oral cells stimulated with TNF, and in periodontal ligament tissue from root surfaces of periodontally damaged teeth, was inhibited following incubation with ozonized medium. Under this treatment, IκBalpah proteolysis, cytokine expression, and κB-dependent transcription were prevented. Specific ozonized amino acids were shown to represent major inhibitory components of ozonized medium. In summary, our study establishes a condition under which aqueous ozone exerts inhibitory effects on the NF-κB system, suggesting that it has an antiinflammatory capacity
Bioecologia e controle da pérola-da-terra Eurhizococcus brasiliensis (Hempel, 1922) (Hemiptera: Margarodidae) na cultura da videira.
bitstream/item/87061/1/bioecologias.pd
Reactions and clustering of water with silica surface
The interaction between silicasurface and water is an important topic in geophysics and materials science, yet little is known about the reaction process. In this study we use first-principles molecular dynamics to simulate the hydrolysis process of silicasurface using large cluster models. We find that a single water molecule is stable near the surface but can easily dissociate at three-coordinated silicon atom defect sites in the presence of other water molecules. These extra molecules provide a mechanism for hydrogen transfer from the original water molecule, hence catalyzing the reaction. The two-coordinated silicon atom is inert to the water molecule, and water clusters up to pentamer could be stably adsorbed at this site at room temperature.Peer reviewe
epsilon-Caprolactone in Micro-Chambered Ceramic Beads - A New Carrier for Gentamicin
Purpose: The purpose of this preliminary and descriptive study was toevaluate a biodegradable drug delivery system in combination with aninnovative ceramic implant. Methods: The delivery of gentamicin ofstandardized samples was measured in the laboratory usingultra-high-performance liquid chromatography. Biocompatibility andbiodegradation of the materials was investigated in an animal experimentin sheep up to 14 months. As carrier epsilon-caprolactone, 1:1 mixedwith gentamicin, intruded into micro-chambered beta-tricalcium-phosphatebeads (MCB (R)) was studied. Results and Discussion: Gentamicin wasreleased in calculable concentrations during the first 30 days. Therelease from epsilon-caprolactone was higher than that frompolymethylmethacrylate and more predictable. The caprolactone carrierwas reabsorbed by osteoclasts
Tailoring negative pressure by crystal defects: Crack induced hydride formation in Al alloys
Climate change motivates the search for non-carbon-emitting energy generation
and storage solutions. Metal hydrides show promising characteristics for this
purpose. They can be further stabilized by tailoring the negative pressure of
microstructural and structural defects. Using systematic ab initio and
atomistic simulations, we demonstrate that an enhancement in the formation of
hydrides at the negatively pressurized crack tip region is feasible by
increasing the mechanical tensile load on the specimen. The theoretical
predictions have been used to reassess and interpret atom probe tomography
experiments for a high-strength 7XXX-aluminium alloy that show a substantial
enhancement of hydrogen concentration at structural defects near a
stress-corrosion crack tip. These results contain important implications for
enhancing the capability of metals as H-storage materials.Comment: 22 pages, 9 figure
Lattice dynamics and structural stability of ordered Fe3Ni, Fe3Pd and Fe3Pt alloys
We investigate the binding surface along the Bain path and phonon dispersion
relations for the cubic phase of the ferromagnetic binary alloys Fe3X (X = Ni,
Pd, Pt) for L12 and DO22 ordered phases from first principles by means of
density functional theory. The phonon dispersion relations exhibit a softening
of the transverse acoustic mode at the M-point in the L12-phase in accordance
with experiments for ordered Fe3Pt. This instability can be associated with a
rotational movement of the Fe-atoms around the Ni-group element in the
neighboring layers and is accompanied by an extensive reconstruction of the
Fermi surface. In addition, we find an incomplete softening in [111] direction
which is strongest for Fe3 Ni. We conclude that besides the valence electron
density also the specific Fe-content and the masses of the alloying partners
should be considered as parameters for the design of Fe-based functional
magnetic materials.Comment: Revised version, accepted for publication in Physical Review
Evaluation of the marginal fit of three margin designs of resin composite crowns using CAD/CAM
OBJECTIVES:
To examine the marginal fit of resin composite crowns manufactured with the CEREC 3 system employing three different margin designs; bevel, chamfer and shoulder, by means of a replica technique and a luting agent.
METHODS:
Three master casts were fabricated from an impression of a typodont molar tooth and a full-coverage crown prepared with a marginal finish of a bevel, a chamfer and a shoulder. Each cast was replicated 10 times (n = 10). Scanning of the replicas and crown designing was performed using the CEREC ScanTM system. The crowns were milled from Paradigm MZ100TM composite resin blocks. The marginal fit of the crowns was evaluated with a replica technique (AquasilTM LV, Dentsply), and with a resin composite cement (RelyXTM Unicem, AplicapTM) and measured with a travelling microscope. Statistical analysis was performed using two-way ANOVA.
RESULTS:
For the replica technique the average marginal gaps recorded were: Bevel Group 105±34 mm, Chamfer Group 94±27 mm and Shoulder Group 91±22 mm. For the resin composite cement the average marginal gaps were: Bevel Group 102±28 mm, Chamfer Group 91±11 mm and Shoulder Group 77±8 mm. Two-way ANOVA analysis showed that there was no statistically significant difference between the three groups of finishing lines regardless of the cementation technique used.
CONCLUSIONS:
The marginal gap of resin composite crowns manufactured with the CEREC 3 system is within the range of clinical acceptance, regardless of the finishing line prepared or the cementation technique used
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