Search results for "FFR"
showing 10 items of 1798 documents
X-Ray Diffraction and Multifrequency EPR Study of Radiation-Induced Room Temperature Stable Radicals in Octacalcium Phosphate.
2020
Octacalcium phosphate (OCP) {Ca8H2(PO4)6×5H2O] has attracted increasing attention over the last decade as a transient intermediate to the biogenic apatite for bone engineering and in studies involving the processes of pathological calcification. In this work, OCP powders obtained by hydrolysis of dicalcium phosphate dehydrate were subjected to X- and γ-ray irradiation and studied by means of stationary and pulsed electron paramagnetic resonance at 9, 36 and 94 GHz microwave frequencies. Several types of paramagnetic centers were observed in the investigated samples. Their spectroscopic parameters (components of the g and hyperfine tensors) were determined. Based on the extracted parameters,…
Influence of β-tricalcium phosphate granule size and morphology on tissue reaction in vivo.
2010
In this study the tissue reaction to five different β-tricalcium phosphate (β-TCP)-based bone substitute materials differing only in size, shape and porosity was analyzed over 60 days, at 3, 10, 15, 30 and 60 days after implantation. Using the subcutaneous implantation model in Wistar rats both the inflammatory response within the implantation bed and the resulting vascularization of the biomaterials were qualitatively and quantitatively assessed by means of standard and special histological staining methods. The data from this study showed that all investigated β-TCP bone substitutes induced the formation of multinucleated giant cells. Changes in size, shape and porosity influenced the int…
Fabrication of polyelectrolyte multilayered vesicles as inhalable dry powder for lung administration of rifampicin
2014
A polyelectrolyte complex based on chitosan and carrageenan was used to coat rifampicin-loaded vesicles and obtain a dry powder for inhalation by spray-drying. The polymer complexation on vesicle surface stabilized them and improved their adhesion on airways and epithelia cells. Uncoated liposomes were small in size, negatively charged and able to incorporate large amounts of rifampicin (70%). Coated vesicles were still able to load adequate amounts of drug (∼70%) but the coating process produced larger particles (1 μm) that were positively charged and with a spherical shape. Aerosol performances, evaluated using the next-generation impactor, showed that coated vesicles reached the 50% of f…
Does phosphorus affect the industrial Portland cement reactivity?
2018
Abstract The effect of phosphorous on the mineralogy and reactivity of Portland cement has been investigated through an industrial clinkers series. The samples were collected from the same Tunisian cement plant and classified according to the content of P2O5 from 0.5% to 1.1%. All samples were manufactured at the same thermal and cooling conditions as well as possible. The specimens were characterized by X-ray fluorescence spectrometry and optical microscopy techniques and their mineralogy was determined by X-ray powder diffraction coupled to the Rietveld analysis. The cements reactivity prepared from the clinkers was followed by means of isothermalcalorimetry. The compressive strength of t…
Total oxidation of naphthalene with high selectivity using a ceria catalyst prepared by a combustion method employing ethylene glycol.
2009
Abstract During the catalytic combustion of naphthalene, compounds other than CO 2 are often obtained. These products, as polymerized polycyclic aromatic hydrocarbons, oxygenated aromatic compounds and benzene derivate compounds, are usually more toxic than naphthalene. At the present work it is shown a nanocrystalline cerium oxide prepared by a combustion method employing a proper ethylene glycol concentration that exhibits very high activity in the decomposition of naphthalene in the presence of air and, most importantly, a selectivity value towards CO 2 of 100% for any range of conversions and/or temperatures used. In addition, it has been demonstrated that the amount of ethylene glycol …
The structure of charoite, (K,Sr,Ba,Mn)(15-16)(Ca,Na)(32)[(Si-70(O,OH)(180))](OH,F)(4.0)center dot nH(2)O, solved by conventional and automated elect…
2010
AbstractCharoite, ideally (K,Sr,Ba,Mn)15–16(Ca,Na)32[(Si70(O,OH)180)](OH,F)4.0·nH2O, a rare mineral from the Murun massif in Yakutiya, Russia, was studied using high-resolution transmission electron microscopy, selected-area electron diffraction, X-ray spectroscopy, precession electron diffraction and the newly developed technique of automated electron-diffraction tomography. The structure of charoite (a= 31.96(6) Å,b= 19.64(4) Å,c= 7.09(1) Å, β = 90.0(1)°,V= 4450(24) Å3, space groupP21/m) was solvedab initioby direct methods from 2878 unique observed reflections and refined toR1/wR2= 0.17/0.21. The structure can be visualized as being composed of three different dreier silicate chains: a d…
Nanocarriers for antioxidant resveratrol: formulation approach, vesicle self-assembly and stability evaluation.
2013
In this work we studied various nanoformulations of resveratrol in phospholipid vesicles. Conventional phophatidylcholine liposomes were prepared and characterized in parallel with PEVs (Penetration Enhancer-containing Vesicles) obtained by adding one of eight selected amphiphilic penetration enhancers (PEs; 0.2% w/v; HLB range 1-16) to the composition. All vesicles were around 100 nm, negatively charged (∼-30 mV) and able to incorporate resveratrol in good yields (>74%). The structure and the lamellar self-organization of the vesicles were investigated by Transmission Electron Microscopy (TEM) and Small and Wide Angle X-ray Scattering (SWAXS). These analyses showed that the lamellarity of …
Influence of Physicochemical Interactions between Amylose and Aroma Compounds on the Retention of Aroma in Food-like Matrices
2002
In food matrices, where starch is often used as a gelling or texturing agent, the occurrence of amylose-aroma complexes and their effect on the release of aroma compounds are difficult to determine. Indeed, thick or gelled systems are known to reduce the diffusion rate of flavor molecules, resulting in an increase of retention. Moreover, interactions between aroma compounds and matrix components might increase the retention of aroma compounds. The complexing behavior of three aroma compounds with amylose was studied by DSC and X-ray diffraction to determine the relative importance of these two factors. Their interaction properties were different: two of them formed complexes, and the third …
Nature-Inspired Effects of Naturally Occurring Trace Element-Doped Hydroxyapatite Combined with Surface Interactions of Mineral-Apatite Single Crysta…
2022
Innovative engineering design for biologically active hydroxyapatites requires enhancing both mechanical and physical properties, along with biocompatibility, by doping with appropriate chemical elements. Herein, the purpose of this investigation was to evaluate and elucidate the model of naturally occurring hydroxyapatite and the effects of doped trace elements on the function of normal human fibroblasts, representing the main cells of connective tissues. The substrates applied (geological apatites with hexagonal prismatic crystal habit originated from Slyudyanka, Lake Baikal, Russia (GAp) and from Imilchil, The Atlas Mountains, Morocco (YAp)) were prepared from mineral natural apatite wit…
Pressure-induced phase transitions in AgClO4
2011
11 pags, 9 figs, 4 tabs. -- PACS number(s): 62.50.−p, 64.70.K−, 61 .50.Ks, 64.30.−t