Search results for "Biomaterial"
showing 10 items of 1350 documents
Luting of ceramic crowns with a self-adhesive cement: Effect of contamination on marginal adaptation and fracture strength
2012
Objectives: This study evaluated the percentages of continuous margins (%CM) and fracture strength (FS) of crowns made out from blocs of leucite-reinforced ceramic (IPS Empress CAD) and luted with a representative self-adhesive cement (RelyX Unicem) under four contaminating agents: saliva, water, blood, a haemostatic solution containing aluminium chloride (pH= 0.8) and a control group with no contamination. Study Design: %CM at both tooth-cement (TC) and cement-crown (CC) interfaces were determined before and after a fatigue test consisting of 600’000 chewing loads and 1’500 temperature cycles changing from 5º C to 50º C. Load to fracture was recorded on fatigued specimens. Kruskal-Wallis t…
Adsorption mechanism of arsenate by zirconyl-functionalized activated carbon
2007
Arsenate [As(V)] and arsenite [As(III)] sorption at the solid-water interface of activated carbon impregnated with zirconyl nitrate (Zr-AC) was investigated using X-ray absorption spectroscopy (XAS) and surface complexation modeling. The XAS data at the Zr K-edge suggest that the structure of the zirconyl nitrate coating is built from chains of edge-sharing ZrO8 trigonal dodecahedra bound to each other through two double hydroxyl bridges. The 8-fold coordination of each Zr atom is completed by four O atoms, which share a bit less than the two theoretically possible bidentate nitrate groups. On impregnation, two of the O atoms may lose their nitrate group and be transformed to hydroxyl group…
Tuning the Structure of Galacturonate Hydrogels: External Gelation by Ca, Zn, or Fe Cationic Cross-Linkers
2019
International audience; We show here how the nature of various divalent cations M2+ (Ca2+, Zn2+, or Fe2+) influences the structure and mechanical properties of ionotropic polygalacturonate (polyGal) hydrogels designed by the diffusion of cations along one direction (external gelation). All hydrogels exhibit strong gradients of polyGal and cation concentrations, which are similar for all studied cations with a constant ratio R = [M2+]/[Gal] equal to 0.25, showing that every M2+ cation interacts with four galacturonate (Gal) units all along the gels. The regions of the hydrogels formed in the early stages of the gelation process are also similar for all cations and are homogeneous, with the s…
Monitoring of the action of drugs in melanoma cells by dynamic laser speckle
2014
Abstract. This work presents the development of a protocol based on the dynamic laser speckle designed tomonitor the reaction of cancer cells of line MEL-RC08 to the application of the drug Colcemid in two differentconcentrations: 0.2 and 0.4 μg∕mL. The protocol was designed using the forward scattering approach with anHe-Ne laser of 632.8 nm illuminating the samples, a control, and two variations of Colcemid, being monitoredalong 8 h. The data were analyzed numerically in the time and in the frequency domain, and the results pre-sented the ability of the technique to monitor the action of the drug, particularly Colcemid (0.4 μg∕mL). © 2014Society of Photo-Optical Instrumentation Engineers …
Towards noncontact skin melanoma selection by multispectral imaging analysis
2011
A clinical trial comprising 334 pigmented and vascular lesions has been performed in three Riga clinics by means of multispectral imaging analysis. The imaging system Nuance 2.4 (CRi) and self-developed software for mapping of the main skin chromophores were used. Spe- cific features were observed and analyzed for malignant skin melanomas: notably higher absorbance (especially as the difference of optical density relative to the healthy skin), uneven chromophore distribution over the lesion area, and the possibility to select the "melanoma areas" in the correla- tion graphs of chromophores. The obtained results indicate clinical potential of this technology for noncontact selec- tion of mel…
Semiautomated quantification of the fibrous tissue response to complex three‐dimensional filamentous scaffolds using digital image analysis
2021
Fibrosis represents a relevant response to the implantation of biomaterials, which occurs not only at the tissue-material interface (fibrotic encapsulation) but also within the void fraction of complex three-dimensional (3D) biomaterial constructions (fibrotic ingrowth). Usual evaluation of the biocompatibility mostly depicts fibrosis at the interface of the biomaterial using semiquantitative scores. Here, the relations between encapsulation and infiltrating fibrotic growth are poorly represented. Virtual pathology and digital image analysis provide new strategies to assess fibrosis in a more differentiated way. In this study, we adopted a method previously used to quantify fibrosis in visc…
Contact and contactless diffuse reflectance spectroscopy: potential for recovery monitoring of vascular lesions after intense pulsed light treatment.
2011
Optical fiber contact probe diffuse reflectance spectroscopy and remote multispectral imaging methods in the spectral range of 400 to 1100 nm were used for skin vascular malformation assessment and recovery tracing after treatment by intense pulsed light. The results confirmed that oxy-hemoglobin relative changes and the optical density difference between lesion and healthy skin in the spectral region 500 to 600 nm may be successfully used for objective appraisal of the therapy effect. Color redness parameter a* = 2 is suggested as a diagnostic border to distinguish healthy skin and vascular lesions, and as the indicator of phototreatment efficiency. Valuable diagnostic information on large…
Model-Based Decision Support System for Individual Prescription of the Dialysate Bicarbonate Concentration in Hemodialysis
1992
A decision support system has been developed that determines the optimal dialysate bicarbonate concentration in hemodialysis therapy for each patient individually. The knowledge about the behavior of the acid-base state during treatment has been provided by a mathematical model for the description of dynamic exchange processes during hemodialysis. This model simulates the sodium and water distribution, the acid-base state as well as the ventilation. The decision support system uses the model for the prediction of the end-dialysis acid-base state and calculates by means of linear optimization the dialysate bicarbonate concentration which is necessary to reach a specified end-dialysis state.…
Halloysite nanotubes for efficient loading, stabilization and controlled release of insulin
2018
Hypothesis: Oral insulin administration is not actually effective due to insulin rapid degradation, inactivation and digestion by proteolytic enzymes which results in low bioavailability. Moreover insulin is poorly permeable and lack of lipophilicity. These limits can be overcome by the loading of protein in some nanostructured carrier such as halloysite nanotubes (HNTs). Experiments: Herein we propose an easy strategy to obtain HNT hybrid materials for the delivery of insulin. We report a detailed description on the thermal behavior and stability of insulin loaded and released from the HNTs hybrid by the combination of several techniques. Findings: Release experiments of insulin from the H…
Anisotropic lattice distortions in biogenic calcite induced by intra-crystalline organic molecules.
2006
9 pages; International audience; We have performed precise structural measurements on five different calcitic seashells by high-resolution X-ray powder diffraction on a synchrotron beam line and by laboratory single crystal X-ray diffraction. The unit cell parameters a and c of biogenic calcite were found to be systematically larger than those measured in the non-biogenic calcite. The maximum lattice distortion (about 2.10(-3)) was detected along the c-axis. Under heat treatment above 200 degrees C, a pronounced lattice relaxation was observed, which allowed us to conclude that anisotropic lattice swelling in biogenic calcite is induced by organic macromolecules incorporated within the sing…