Search results for "nuclear chemistry"
showing 10 items of 1124 documents
Comparative Surface Morphology, Chemical Composition, and Cytocompatibility of Bio-C Repair, Biodentine, and ProRoot MTA on hDPCs
2020
Biocompatibility is an essential property for any vital pulp material that may interact with the dental pulp tissues. Accordingly, this study aimed to compare the chemical composition and ultrastructural morphology of Biodentine (Septodont, Saint Maur-des-Fosses, France), ProRoot MTA (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA), and Bio-C Repair (Angelus, Londrina, PR, Brazil), as well as their biological effects on human dental pulp cells. Chemical element characterization of the materials was undertaken using scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX). The cytotoxicity was assessed by analyzing the cell viability (MTT assay), cell morphology …
Synthesis, structural, and thermal characterization of a new binuclear copper(II) chelate complex bearing an amine-hardener for epoxy resins
2016
A new di(μ-carbonato)bis[aqua(diethylenetriamine)copper(II)] hexahydrate complex, [{Cu(NH(C2H4NH2)2)(H2O)(μ-CO3)}2]⋅6H2O (1), was synthesized by direct interaction of malachite with diethylenetriamine (dien). The crystals of 1 were characterized by X-ray powder diffraction and IR spectra, as well as structurally characterized. Compound 1 consists of [{Cu(dien)(H2O)(μ-CO3)}2] discrete units whose CO32– anions play the role of bridging ligands combining two Cu(II) chelate cores into a centrosymmetric dimer. The elongated octahedral environment of Cu2+ consists of three nitrogens of dien and an oxygen from CO32– at the base of the bipyramid; the two apical positions of such polyhedron are occu…
Preparation and physico-chemical study of inclusion complexes between idebenone and modified beta-cyclodextrins
1996
The inclusion properties of modifiedβ-cyclodextrins (trimethyl-β-cyclodextrin, dimethyl-β-cyclodextrin and hydroxypropyl-β-cyclodextrin) towards idebenone were compared with naturalβ-cyclodextrin. The inclusion complexes were prepared by different methods (coprecipitation, kneading, and freeze-drying) and characterized by differential scanning calorimetry, X-ray diffractometry, UV, CD and NMR spectroscopy. The results obtained by CD and NMR spectroscopy indicate a different orientation of idebenone in dimethyl-β-cyclodextrin with respect to other cyclodextrins. Stability constants of the complexes were determined in water at various temperatures and consequently thermodynamic parameters wer…
Analysis of radionuclide concentration in air released through the stack of a radiopharmaceutical production facility based on a medical cyclotron
2015
Abstract Positron emitting radionuclides are increasingly used in medical diagnostics and the number of radiopharmaceutical production facilities have been estimated to be growing worldwide. During the process of production and/or patient administration of radiopharmaceuticals, an amount of these radionuclides might become airborne and escape into the environment. Therefore, the analysis of radionuclide concentration in the air released to the stack is a very important issue to evaluate the dose to the population living around the plant. To this end, sampling and measurement of radionuclide concentration in air released through the stack of a Nuclear Medicine Center (NMC), provided with a c…
Study of liquid–liquid equilibrium of the systems isobutyl acetate+acetic acid+water and isobutyl alcohol+acetic acid+water at different temperatures
2008
Abstract In this work, experimental liquid–liquid equilibria (LLE) data of the systems isobutyl acetate + acetic acid + water and isobutyl alcohol + acetic acid + water are presented. The liquid–liquid equilibria of both systems have been measured at 283.15 and 323.15 K. The NRTL and UNIQUAC models were applied to fit the data for both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions. The experimental tie lines were compared to the values predicted by the UNIFAC method. Moreover, the solvent capabilities of isobutyl acetate and isobutyl alcohol were compared.
Effect of lithium ions on the catalytic efficiency of calcium oxide as a nanocatalyst for the transesterification of lard oil
2019
The present work encompasses the effect of Li+ ions on CaO nanoparticles for the transesterification of lard oil. The modification of CaO nanoparticles was achieved by the impregnation of different molar ratios of lithium hydroxide. Later, each catalyst was screened for the catalytic conversion of lard oil to a fatty acid methyl ester (FAME). The nanocatalyst CaO–0.5LiOH (1 : 0.5 molar ratio) showed the best conversion rate for FAME. The synthesized nanocatalyst was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and Hammett indicato…
Degradation of Amino-(3-methoxyphenyl)methanephosphonic Acid by Alternaria sp
2002
Alternaria sp. isolated from the surface of carrot ( Daucus carota ) seeds appeared to be able to degrade amino-(4-methoxyphenyl)-methanephosphonic acid using it as a sole source of carbon, nitrogen, and phosphorus for growth.
Enhancement of structural, functional and antioxidant properties of fish gelatin films using Maillard reactions
2018
International audience; This study investigates the effect of Maillard reactions (MR) on the physico-chemical and biological properties of fish gelatin based edible films. Glucose was incorporated in gelatin film forming solutions at different glucose/lysine molar ratios: 0.5/1.0, 1.0/1.0 and 5.0/1.0. The MR was then induced by heating films at 90 °C for 24 h in dry conditions. Color changes and browning index measurements were used to pursue the MR kinetic. Results showed that the development of MR products was dependent on the glucose content and on the reaction time. Mechanical and thermal properties of treated films displayed an increase in tensile strength, elongation at break and glas…
Physical chemical properties and kinetics of redox processes in water/soybean oil microemulsions
2008
Microemulsoes de agua em oleo (ME w/o) constituidas de agua, oleo de soja, SDS (dodecil sulfato de sodio) e diversos alcoois de cadeia curta foram caracterizadas sob o ponto de vista fisico-quimico e de propriedades eletroanaliticas. Foram testados diferentes co-surfactantes e razoes surfactante:cosurfactante, sendo a ME com a composicao mais favoravel utilizada para estudar a cinetica de processos redox. Para tanto, realizaram-se medidas de voltametria ciclica utilizando como eletrodo de trabalho um ultramicroeletrodo de disco de Pt e, como eletrodo de referencia e auxiliar, foram usados Ag/AgCl e Pt, respectivamente, e ferroceno como uma sonda. Verificou-se que a estabilidade termodinâmic…
Biological and antibacterial properties of a new silver fiber post : in vitro evaluation
2016
Background The incorporation of nano silver particles (AgNPs) to improve antibacterial properties of dental materials has become increasingly common. The aim of the present study was to compare the antibacterial activity and cytotoxicity effects of different fiber posts: glass fiber post, quartz fiber post, nano fiber post and silver fiber post. Material and methods The antibacterial activity against S. mutans, S. salivarius and S. sanguis was evaluated by using the agar disc diffusion test (ADT). Four wells of 3x2 mm (one for each material) were made with a punch by removing the agar and filled with the materials to be evaluated. The size of the inhibition zone was calculated. An extract w…