Search results for "phosphoric acid"

Dynamical Properties of Self-Assembled Surfactant-Based Mixtures: Triggering of One-Dimensional Anomalous Diffusion in Bis(2-ethylhexyl)phosphoric Ac…

2013

The dynamic features of bis(2-ethylhexyl)phosphoric acid (HDEHP)/n-octylamine (NOA) mixtures have been investigated as a function of the NOA mole fraction and temperature by (1)H NMR spectroscopy and rheometry. All data consistently suggest a composition-induced glass-forming behavior. The microscopic factors responsible for this behavior have been highlighted and have been explained in terms of driving forces given by HDEHP-to-NOA proton transfer, the tendency of the resulting species to establish H bonds and to spatially segregate the alkyl chains. The study sheds light on the molecular mechanism responsible for the peculiar behavior of transport properties in such systems and furnishes b…

An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques

2017

Background Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. Material and methods The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with …

Evaluation of the enamel etching pattern of self-etching adhesives

2010

Objectives: To evaluate the capacity of seven self-etching adhesives (SEAs) to demineralize ground enamel in comparison with traditional phosphoric acid etchant (PAE) using SEM and statistical analysis. Materials and methods: 80 caries-free extracted human third molars were divided into 8 groups ( n = 10). Enamel bur-cut surfaces were prepared and, strictly following the manufacturers’ instructions, treated with three priming agents of two-step self-etching adhesives: Aqua Resulcin Prime (Group 1); Peak™ (Group 2); Clearfil Protect Bond (Group 3); four one-step self-etch (all-in-one) adhesives, G-Bond (Group 4); Artegral One (Group 5); Clearfil S3 Bond (Group 6); Adper Easy Bond (Group 7); …

Sealing effectiveness of fissure sealant bonded with universal adhesive systems on saliva-contaminated and noncontaminated enamel.

2017

Background The effectiveness of sealants is dependent upon their adhesion to enamel surface. The aim of the study was to evaluate the sealing ability of a pit and fissure sealant used with a universal adhesive (etch-and-rinse vs. self-etch modes) when the site is contaminated with saliva. Adhesive properties were evaluated as microleakage and scanning electron microscopic (SEM) characteristics. Material and methods A total of 72 mandibular third molars were randomly divided into 6 groups (n=12). Occlusal pits and fissures were sealed with an unfilled resin fissure sealant (FS) material with or without saliva contamination. The groups included: 1) phosphoric acid etching + FS (control), 2) p…

Reduction of Polymerization Shrinkage Stress and Marginal Microleakage Using Soft-Start Polymerization

2003

Purpose: This study evaluated the influence of a soft-start light-curing exposure on polymerization shrinkage stress and marginal integrity of adhesive restorations. Materials and Methods: Six resin-based composites (Pertac II, Tetric Ceram, Definite, Surefil, Solitaire, and Visio-Molar) were adhesively bonded to a cylindrical cavity (n = 9 per material/light) in a photoelastic material. Visible light-curing was applied using either the standard polymerization mode (800 mW/cm2 exposure duration 40 s) of the curing light (Elipar TriLight, 3M ESPE) or the exponential mode from the same device (ramp-curing: 150 mW/cm2 to 800 mW/cm2 within the first 15 s of a total curing time of 40 s). Polymer…

Determination of ochratoxin A in beer marketed in Spain by liquid chromatography with fluorescence detection using lead hydroxyacetate as a clean-up …

2005

Abstract A new sample treatment for liquid chromatographic analysis of ochratoxin A (OTA) in beer is proposed. Degassed beer is mixed with lead hydroxyacetate, which precipitates some bulk components but does not remove OTA. The precipitate is separated and the acidified liquid is extracted with chloroform. The solvent is evaporated and the residue is dissolved in mobile phase (acetonitrile–water, 40:60, v/v; acidified at pH 3.0 with phosphoric acid) and separated by liquid chromatography using fluorescence detection. The limit of detection was 0.005 ng/ml. The average recovery rate and the average RSD of recovery in the spiking level range 0.01–0.5 ng/ml were 95.5% and about 5%, respective…

Solvent extraction studies of uranium(VI) from phosphoric acid: Role of synergistic reagents in mixture with bis(2-ethylhexyl) phosphoric acid

2014

Abstract The extraction of uranium(VI) from 5.3 mol·L − 1 H 3 PO 4 (a typical concentration of wet phosphoric acid) with a series of neutral organosphosphorus synergistic reagents (0.125–0.250 mol·L − 1 ) used in mixture with 0.5 mol·L − 1 bis(2-ethylhexyl) phosphoric acid (D2EHPA) in Isane IP 185 (a 100% isoparaffinic aliphatic diluent) has been investigated. The series of synergistic reagents includes tri- n -butyl phosphate (TBP), di- n -butyl n -butyl phosphonate (DBBP), n -butyl di- n -butyl phosphinate (BDBP), tri- n -butyl phosphine oxide (TBPO), tri- n -hexyl phosphine oxide (THPO), tri- n -octyl phosphine oxide (TOPO), tri- n -decyl phosphine oxide (TDPO), di- n -hexyl n -decyl pho…

Tungstophosphoric Acid Supported on TiO2 for the Photodegradation of 4-Nitrophenol in Liquid Phase and of 2-Propanol in gas Phase

2008

Effects of different etching strategies on the microtensile repair bond strength of beautifil II giomer material

2018

Background Considering the differences in the filler particles between giomer and conventional composite resins and the importance of these fillers in the repair bond strength, the aim was to evaluate the effects of different etching strategies with phosphoric acid (PA) and hydrofluoric acid (HF) on the microtensile repair bond strength (µTRBS) of giomer. Material and Methods Ten giomer blocks were randomly assigned into 10: 1) control; 2) 37%PA-20s; 3) 3%HF-20s; 4) 3%HF-120s; 5) 9.6%HF-20s; 6) 9.6%HF-120s; 7) 37%PA-20s + 3%HF-120s; 8) 37%PA-20s + 9.6%HF-120s; 9) 3%HF-120s + 37%PA-20s; 10) 9.6%HF-120s + 37%PA-20s. In all groups, the One-Step Plus bonding system was applied and the new giome…

The influence of preservation method and time on theδ13C value of dissolved inorganic carbon in water samples

2009

The precise delta(13)C value of dissolved inorganic carbon (DIC) is important for various types of ecological studies. Without a preservation agent, microbial degradation of organic compounds continues in water samples and the delta(13)C value of DIC will become more depleted with time. HgCl(2) or acidification is often used to prevent microbial activity in water samples collected for carbon isotope ratio analyses of DIC. Mercury compounds are toxic and result in waste disposal problems. Other inhibiting agents or preservation methods are therefore needed. Two possible solutions are to use copper sulphate (CuSO(4)) as a preservative agent or to acidify water samples with phosphoric acid (H(…