Search results for "Onium"
showing 10 items of 2091 documents
Identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with ultraviole…
2004
A method was established for the identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with an ultraviolet−diode array detector, using a C18 Vydac 201TP54 column. The mobile phase used was the ternary methanol mixture (0.1 M ammonium acetate), tert-butyl methyl ether and water, in a concentration gradient, and a temperature gradient was applied. Retinol palmitate was added as an internal standard. An extraction process (ethanol/hexane, 4:3, v/v) was performed, followed by saponification with diethyl ether/methanolic KOH (0.1%, w/v, BHT) (1:1, v/v) for 0.5 h at room temperature. Seventeen different (cis and trans…
Novel cationic solid-lipid nanoparticles as non-viral vectors for gene delivery.
2007
In this paper, the suitability of novel cationic solid-lipid nanoparticles (SLN) as a nonviral transfection agent for gene delivery was investigated. SLN were produced by using the microemulsion method and Compritol ATO 888 as matrix lipid, dimethyldioctadecylammonium bromide as charge carrier and Pluronic F68 as surfactant. Obtained nanoparticles were approximately 120 nm in size and positively charged, with a zeta potential value equal to +45 mV in twice-distilled water. Cationic SLN were able to form stable complexes with DNA and to protect DNA against DNase I digestion. The SLN-DNA complexes were characterized by mean diameter and zeta potential measurements. In vitro studies on human l…
Diffusion in slice preparations bathed in unstirred solutions
1987
A diffusion model is described here, which allows for the estimations of drug concentration changes in porous media, such as in slice tissues of the central nervous system (CNS) bathed in unstirred solutions following abrupt changes of drug concentration. This model may be used for the interpretation of data obtained in neuropharmacological studies if (i) the diffusion coefficient of the molecules under investigation is constant within the excised tissue, (ii) drug molecules are diffusing only in the extracellular space (ECS) and are not bound by the tissue, (iii) drug molecules diffuse mainly within one dimension, (iv) the drug concentration in the bath is changed within 5 s, and (v) the b…
Bond strength of selected composite resin-cements to zirconium-oxide ceramic
2012
Objectives: The aim of this study was to evaluate bond strengths of zirconium-oxide (zirconia) ceramic and a selection of different composite resin cements. Study Design: 130 Lava TM cylinders were fabricated. The cylinders were sandblasted with 80 μm aluminium oxide or silica coated with CoJet Sand. Silane, and bonding agent and/or Clearfil Ceramic Primer were applied. One hundred thirty composite cement cylinders, comprising two dual-polymerizing (Variolink II and Panavia F) and two autopolymerizing (Rely X and Multilink) resins were bonded to the ceramic samples. A shear test was conducted, followed by an optical microscopy study to identify the location and type of failure, an elec…
Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics
2012
Objective: To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Study design: Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al2O3-particles); and Group 3: Silica-coating (50 µm silica-modified Al2O3-particles). Composite samples were randomly bonded to the pre-treated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm2 sticks. One-half of th…
Influence of the chemical composition of monolithic zirconia on its optical and mechanical properties. Systematic review and meta-regression.
2021
Este artículo se encuentra disponible en la siguiente URL: https://www.jstage.jst.go.jp/article/jpr/66/2/66_JPR_D_20_00218/_pdf/-char/en Este artículo de investigación pertenece al número especial "Advances in Personalized Nursing Care". Purpose: This systematic review set out to investigate the influence of chemical composition and specimen thickness of monolithic zirconia on its optical and mechanical properties. Meta-analysis and meta-regression analyzed the effects of variations in percentages of yttrium, aluminum, and specimen thickness of monolithic zirconia. Study selection: The review followed recommendations put forward in the PRISMA checklist. An electronic search for relevant art…
Full maxillary rehabilitation with an all-ceramic system
2009
With the appearance of all-ceramic systems, providing a choice of framework porcelains and allowing the same material to be used for the veneer, it is now possible to select the ideal structure in terms of both function and esthetics. Silicate ceramics allow porcelain laminate veneers and crowns to be used in the anterior region, providing excellent esthetics; while for the posterior area, where function takes precedence, oxide ceramics, specifically zirconium oxide, are preferred. The IPS e.max ceramic system, heir apparent to the IPS Empress 2 system, combines the advantages of zirconium oxide ceramics (IPS e.max Zircad) with the excellent esthetic qualities of silicate ceramics (IPS e.ma…
Effects of femtosecond laser and other surface treatments on the bond strength of metallic and ceramic orthodontic brackets to zirconia.
2017
Femtosecond laser has been proposed as a method for conditioning zirconia surfaces to boost bond strength. However, metallic or ceramic bracket bonding to femtosecond lasertreated zirconia surfaces has not been tested. This study compared the effects of four conditioning techniques, including femtosecond laser irradiation, on shear bond strength (SBS) of metallic and ceramic brackets to zirconia.Three hundred zirconia plates were divided into five groups: 1) control (C); 2) sandblasting (APA); 3) silica coating and silane (SC); 4) femtosecond laser (FS); 5) sandblasting followed by femtosecond laser (APA+SC). A thermal imaging camera measured temperature changes in the zirconia during irrad…
Fracture resistance and the mode of failure produced in metal-free crowns cemented onto zirconia abutments in dental implants.
2019
The purpose of the investigation was to analyze fracture resistance and mode of failure of zirconium oxide (zirconia) abutments placed on dental implants bearing crowns of different esthetic materials: zirconia, lithium disilicate (LDS), and nano-ceramic resin, for replacing single teeth in the anterior sector. Eighty implant-abutment-crown units were divided into four groups: Group T-MC (control): 20 metal-ceramic crowns cemented onto titanium abutments; Group Z-Z: 20 zirconia crowns on zirconia abutments; Group Z-LD: 20 lithium disilicate crowns on zirconia abutments; and Group Z-NCR: 20 nano-ceramic resin crowns on zirconia abutments. Specimens underwent a fatiguing process (dynamic load…
Implant-supported metal-ceramic and resin-modified ceramic crowns: A 5-year prospective clinical study.
2018
Abstract Statement of problem Because of market demand for innovation, new restoration materials have been introduced without adequate testing; clinical failure may be the consequence, and clinical studies are needed. Purpose The purpose of this clinical study was to evaluate the biological and mechanical clinical behavior of implant-supported resin-modified ceramic crowns compared with that of metal-ceramic crowns. Material and methods Forty-two participants aged between 35 and 65 years received single implants in posterior edentulous sites. After the osseointegration period, half of the implants (selected randomly) (n=25) were restored with metal-ceramic crowns (MC group) and the other ha…