Mouse Genetic Background Influences the Dental Phenotype

Dental enamel covers the crown of the vertebrate tooth and is considered to be the hardest tissue in the body. Enamel develops during secretion of an extracellular matrix by ameloblast cells in the tooth germ, prior to eruption of the tooth into the oral cavity. Secreted enamel proteins direct mineralization patterns during the maturation stage of amelogenesis as the tooth prepares to erupt. The amelogenins are the most abundant enamel proteins, and are required for normal enamel development. Phenotypic differences were observed between incisors from individual Amelx (Amelogenin) null mice that had a mixed 129xC57BL/6J genetic background, and between inbred wld-type (WT) mice with different genetic backgrounds (C57BL/6J, C3H/HEJ, FVB/NJ). We hypothesized this could be due to modifier genes, as human patients with a mutation in an enamel protein gene causing the enamel defect amelogenesis imperfecta (AI) also can have varied appearance of dentitions within a kindred. Enamel density measurements varied for all WT inbred strains midway during incisor development. Enamel thickness varied between some WT strains and, unexpectedly, dentin density varied extensively between incisors and molars of all WT and Amelx null strains studied. WT FVB/NJ incisors were more similar to Amelx null than to the other WT strains in incisor height/weight ratio and pattern of enamel mineralization. Strain-specific differences led to the conclusion that modifier genes may be implicated in determining both normal development and severity of enamel appearance in AI mouse models and may in future studies be related to phenotypic heterogeneity within human AI kindreds reported in the literature

Removal of Ni²⁺ from Aqueous Solutions by Adsorption Onto Magnetic Multiwalled Carbon Nanotube Nanocomposite

The removal of Ni2+ from aqueous solution by magnetic multiwalled carbon nanotube nanocomposite (MMWCNTs-C) was investigated. MMWCNTs-C was characterized by X-ray Diffraction method (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), surface area (BET), and Fourier Transform-Infrared Spectroscopy (FTIR). The effects of initial concentration, contact time, solution pH, and temperature on the Ni2+ adsorption onto MMWCNTs-C were studied. The Langmuir and Freundlich isotherm models were applied to fit the adsorption data. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm model with the maximum monolayer adsorption capacity of 2.11 mg g–1. The adsorption kinetics was best described by the pseudo-second-order model. The thermodynamic parameters, such as ΔHo, ΔGo and ΔSo, were also determined and evaluated. The adsorption of Ni2+ is generally spontaneous and thermodynamically favorable. The values of ΔHo and ΔGo indicate that the adsorption of Ni2+ onto MMWCNTs-C was a physisorption process

Removal of Rhodamine B from aqueous solution by ZnFe2O4 nanocomposite with magnetic separation performance

Magnetic ZnFe2 O4  nanocomposite (ZnFe-NC) was used as an adsorbent for the removal of Rhodamine B (RB) from aqueous solution. The synthesized nanocomposite was characterized by XRD, SEM, HRTEM, BET and FTIR. The effects of various parameters such as initial RB concentration (5–25 mg L−1 ), pH (3.4–11.1) and temperature (20–60°C) were investigated. The adsorption capacity at equilibrium increased from 5.02 to 9.83 mg g−1 , with the increase in the initial concentration of RB from 5 to 25 mg L−1  at pH 7.0 and at 20°C. The experimental results indicated that the maximum RB removal could be attained at a solution pH of 4.4 and the adsorption capacity obtained was 6.02 mg g−1 . Kinetic adsorption data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order model and the intraparticle diffusion model. The adsorption kinetics well fitted using a pseudo-second-order kinetic model. The experimental isotherm data were analyzed using two isotherm models, namely, Langmuir and Freundlich. The results revealed that the adsorption behavior of the RB onto ZnFe-NC fitted well with the Langmuir isotherm model. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) have been calculated

Equilibrium and kinetics studies for the adsorption of Ni2+ and Fe3+ ions from aqueous solution by graphene oxide

In this study, the adsorption of Ni2+  and Fe3+  metal ions from aqueous solutions onto graphene oxide (GO) have been explored. The effects of various experimental factors such as pH of the solution, initial metal ion concentration and temperature were evaluated. The kinetic, equilibrium and thermodynamic studies were also investigated. The adsorption rate data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. Kinetic studies indicate that the adsorption of both ions follows the pseudo-second-order kinetics. The isotherms of adsorption data were analyzed by adsorption isotherm models such as Langmuir and Freundlich. Equilibrium data fitted well with the Langmuir model. The maximum adsorption capacities of Ni2+  and Fe3+  onto GO were 35.6 and 27.3 mg g-1 , respectively. In addition, various thermodynamic parameters, such as enthalpy (ΔHO), entropy (ΔSO) and Gibbs free energy (ΔGO), were calculated

XRD, TEM and magnetic resonance studies of iron carbide nanoparticle agglomerates in a carbon matrix

Three powder samples with different content of iron carbide in a carbon matrix have been synthesised by carburisation of nanocrystalline iron with methane. The samples have been characterised by XRD and TEM methods. The mean crystallite size of the obtained iron carbide has been found to be in the range from 41 to 67 nm. The magnetic resonance measurements of these samples have been performed at room temperature. Very intense magnetic resonance lines have been recorded for each of the samples. A resonance field, an integral intensity and a linewidth strongly depend on the concentration of iron carbide. The observed magnetic resonance lines have been fitted with two Lorentzian-shape lines, one centred at lower and the other at higher magnetic fields. Strong magnetic anisotropy was observed for all the samples and for the sample with lower concentration of iron carbide it is more intense. The resonance absorption signal arises from the agglomerates of iron carbide nanoparticles interacting strongly among themselves. The observed shift of the resonance field is connected with a strong ferromagnetic interaction between agglomerates of nanoparticles. © 2004 Elsevier Ltd. All rights reserved

Mouse Genetic Background Influences the Dental Phenotype

Dental enamel covers the crown of the vertebrate tooth and is considered to be the hardest tissue in the body. Enamel develops during secretion of an extracellular matrix by ameloblast cells in the tooth germ, prior to eruption of the tooth into the oral cavity. Secreted enamel proteins direct mineralization patterns during the maturation stage of amelogenesis as the tooth prepares to erupt. The amelogenins are the most abundant enamel proteins, and are required for normal enamel development. Phenotypic differences were observed between incisors from individual Amelx (Amelogenin) null mice that had a mixed 129xC57BL/6J genetic background, and between inbred wld-type (WT) mice with different genetic backgrounds (C57BL/6J, C3H/HEJ, FVB/NJ). We hypothesized this could be due to modifier genes, as human patients with a mutation in an enamel protein gene causing the enamel defect amelogenesis imperfecta (AI) also can have varied appearance of dentitions within a kindred. Enamel density measurements varied for all WT inbred strains midway during incisor development. Enamel thickness varied between some WT strains and, unexpectedly, dentin density varied extensively between incisors and molars of all WT and Amelx null strains studied. WT FVB/NJ incisors were more similar to Amelx null than to the other WT strains in incisor height/weight ratio and pattern of enamel mineralization. Strain-specific differences led to the conclusion that modifier genes may be implicated in determining both normal development and severity of enamel appearance in AI mouse models and may in future studies be related to phenotypic heterogeneity within human AI kindreds reported in the literature