Search results for "apatite"

Toxicological properties of two fluorescent carbon quantum dots with onion ring morphology and their usefulness as bioimaging agents

2016

In the present work, two carbon quantum dots with onion ring morphology, C-NOR and C-NOR(Eu) with an average size of 40 nm differing in the absence or presence of Eu3+ as Lewis acids during their preparation were synthesized and fully characterized by several techniques. These nanoparticles can be internalized into human HeLa and Hep3B carcinoma cells where they exhibit interesting photoluminescent properties, in the same manner as in solution, confirming their utility as bioimaging agents. To address this possibility, a complete in vitro toxicological study has been performed here. Viability, proliferation, apoptosis and oxidative stress assessments upon limited or continuous exposure were…

Erosive effect of industrialized fruit juices exposure in enamel and dentine substrates: An in vitro study

2021

Background Erosive tooth wear has been a highly prevalent and emerging phenomenon related to eating habits of the population. Aim: This study sought to investigate industrialized fruit juices exposure in enamel and dentine substrates in terms of erosive effect. Material and methods Human enamel and dentine specimens were randomized into 8 groups (n=8): Grape juice - Ades®, Grape juice - Del Valle Kapo®, Grape juice - Aurora®, Orange juice - Del Valle Kapo®, Orange juice - Ades®, Strawberry juice - Mais Vita®, Strawberry juice - Ades®, Citrus fruit juice - Tampico®. Specimens were submitted to an in vitro erosive challenge and to a microhardness test to evaluate the percentage of surface mic…

Crystal-phagocyte interaction in calcinosis interstitialis.

1984

Based on recent findings indicating the stimulation of the respiratory burst in human neutrophils by crystal phagocytosis, ectopic calcified nodules of a patient with calcinosis interstitialis were exposed to autologous granulocytes and monocytes in vitro. The activity of the respiratory burst was determined by luminol-enhanced chemiluminescence. Controls included amorphous monosodium urate, microcrystalline monosodium urate, hydroxyapatite, and zymosan. Microcrystalline monosodium urate elicited a marked stimulation of both granulocytes and monocytes as did hydroxyapatite in granulocytes. Hydroxyapatite caused no stimulation of monocytes, possibly reflecting selective functional modulation…

Direct determination of total mercury in phosphate rock using alkaline fusion digestion

2014

The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in phosphate rock using a dedicated analytical instrument (the DMA80 Tricell by Milestone) that employs an integrated sequence of thermal decomposition followed by catalyst conversion, amalgamation and atomic absorption spectrophotometry. However, this instrument underestimates Hg concentrations when phosphorite and apatite rocks are investigated with a classic thermal decomposition treatment that complies with US EPA method 7473. Therefore, to improve the recovery of total Hg, we performed alkaline fusion digestion (AFD) directly inside the furnace of the instrument, using BCR(32) as a certified r…

USO DI TECNICHE AVANZATE PER LA OTTIMIZZAZIONE STRUTTURALE E FUNZIONALE DI SCAFFOLD COMPOSITI POLIMERO-CARICA INORGANICA PER LA RIGENERAZIONE OSSEA.

2020

Modelling biological and chemically induced precipitation of calcium phosphate in enhanced biological phosphorus removal systems

2011

The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Rea…

Hydroquinone: O-glucosyltransferase from cultivated Rauvolfia cells: enrichment and partial amino acid sequences.

2000

Plant cell suspension cultures of Rauvolfia are able to produce a high amount of arbutin by glucosylation of exogenously added hydroquinone. A four step purification procedure using anion exchange, hydrophobic interaction, hydroxyapatite-chromatography and chromatofocusing delivered in a yield of 0.5%, an approximately 390 fold enrichment of the involved glucosyltransferase. SDS-PAGE showed a M(r) for the enzyme of 52 kDa. Proteolysis of the pure enzyme with endoproteinase LysC revealed six peptide fragments with 9-23 amino acids which were sequenced. Sequence alignment of the six peptides showed high homologies to glycosyltransferases from other higher plants.

Effects of yeast immobilization on bioethanol production

2014

The current study evaluated a newer method, which includes a dehydration step, of immobilizing Saccharomyces cerevisiae L-77 and S. cerevisiae L-73 onto hydroxylapatite and chamotte ceramic supports. The efficiency of cell immobilization on chamotte was significantly higher than hydroxylapatite. Immobilized yeast preparations were investigated for their ethanol-producing capabilities. The glucose concentration in a fermentation medium was 100 mg/mL. Immobilized preparations produced the same amount of ethanol (48 ± 0.5 mg/mL) as free cells after 36 H of fermentation. During the early stages of fermentation, immobilized yeast cells produced ethanol at a higher rate than free cells. Yeast pre…

The chemical composition of synthetic bone substitutes influences tissue reactions in vivo : histological and histomorphometrical analysis of the cel…

2012

Bone substitute material properties such as granule size, macroporosity, microporosity and shape have been shown to influence the cellular inflammatory response to a bone substitute material. Keeping these parameters constant, the present study analyzed the in vivo tissue reaction to three bone substitute materials (granules) with different chemical compositions (hydroxyapatite (HA), beta-tricalcium phosphate (TCP) and a mixture of both with a HA/TCP ratio of 60/40 wt%). Using a subcutaneous implantation model in Wistar rats for up to 30 days, tissue reactions, including the induction of multinucleated giant cells and the extent of implantation bed vascularization, were assessed using histo…

Morphostructural analysis of human follicular stem cells on highly porous bone hydroxyapatite scaffold

2007

In this study we investigated the in vitro behaviour, morphostructure and extracellular matrix synthesis of human dental follicular stem cells (hDFSCs) isolated from human dental bud, which resulted to be positive for mesenchymal markers (CD29, CD90, CD146 and CD166) by FACS analysis. Cells were analysed by light and electronic microscopy to evaluate their biological response either at week 1, that is before differentiation, or at weeks 3–6, when they had been cultured in osteogenic medium onto a highly porous natural scaffold material (Bio-Oss®). Microscopy analysis of primary culture cells showed they had a mesenchymal stem cell-like morphostructure, spindle shaped, similar to the cultur…