Novel production method of porous surface Ti samples for biomedical application

A porous implant material with adequate pore structure and the appropriate mechanical properties for bone ingrowth has long been sought. This article presents details of the development, characterization and in vivo evaluations of powder metallurgy-processed titanium samples exhibiting a dense core with an integrated porous surface for biomedical applications. A space-holder method was applied to investigate the effects of different percentages and particle sizes of the urea on bone neoformation in 30 rabbits. The samples were previously characterized using scanning electron microscopy and mechanical testing. After 8 and 12 weeks of implantation, bone ingrowth was histologically and histometrically analyzed and push-out testing was performed. This study demonstrated that the association of a dense core integrated with the greatest number of interconnected pores of the smallest size is a promising biomaterial for bone tissue engineering. This sample exhibits appropriate mechanical properties combined with increased bone ingrowth, providing enhanced resistance to displacement.     

Effect of methyl methacrylate monomer on bond strength of denture base resin to acrylic teeth

Bond failures at the acrylic teeth and denture base resin interface are still a common clinical problem in prosthodontics. The effect of methyl methacrylate (MMA) monomer on the bond strength of three types of denture base resins (Acron MC, Lucitone 550 and QC-20) to two types of acrylic teeth (Biotone and Trilux) was evaluated. Twenty specimens were produced for each denture base resin/acrylic tooth combination and were randomly divided into control (acrylic teeth received no surface treatment) and experimental groups (MMA was applied to the surface of the acrylic teeth for 180 s) and were submitted to shear tests (1 mm/min). Data (MPa) were analyzed using three-way ANOVA/Student's test (α=0.05). MMA increased the bond strength of Lucitone denture base resins and decreased the bond strength of QC-20. No difference was detected for the bond strength of Acron MC base resin after treatment with MMA.     

Solid-phase extraction and HPLC determination of Ochratoxin A in cereals products on Chilean market

Ochratoxin A (OTA) is a mycotoxin produced by different species of Aspergillus and Penicillium fungi. The presence of this mycotoxin in cereals-based products has relation with manufacturing practices, especially with storage conditions. An extraction procedure for OTA from wheat-based products was implemented in this study. The method uses an alkaline extraction with NaHCO₃, purification with Sep-Pak^® RP-18 cartridges; and quantitative analysis by high performance liquid chromatography with fluorescence detection. The presence of OTA was confirmed by the formation of Ochratoxin A methyl ester. The method shows good validation parameters with a rate of recovery rate over 95%, limits of detection and quantification of 0.6 and 2.1 μg kg^?1, respectively. Once the method was validated; 31 samples including, flour, corn starches and rice were analyzed. About 70% of flour samples, 50% of rice and 63% of corn starch samples resulted positives for OTA.     

Microstructure and mineral composition of dental enamel of permanent and deciduous teeth

Purpose: This study evaluated and compared in vitro the microstructure and mineral composition of permanent and deciduous teeth's dental enamel. Methods: Sound third molars (n = 12) and second primary molars (n = 12) were selected and randomly assigned to the following groups, according to the analysis method performed (n = 4): Scanning electron microscopy (SEM), X‐Ray diffraction (XRD) and Energy dispersive X‐ray spectrometer (EDS). Qualitative and quantitative comparisons of the dental enamel were done. The microscopic findings were analyzed statistically by a nonparametric test (Kruskal‐Wallis). The measurements of the prisms number and thickness were done in SEM photomicrographs. The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Chemical phases present in both types of teeth were observed by the XRD analysis. Results: The mean thickness measurements observed in the deciduous teeth enamel was 1.14 mm and in the permanent teeth enamel was 2.58 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enamel‐dentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The percentage of Ca and P was higher in the permanent teeth enamel. Conclusions: The primary enamel structure showed a lower level of Ca and P, thinner thickness and higher numerical density of rods. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.     

Characterization of niobium pentoxide synthesized by spray pyrolysis technique and comparison with hydrothermal method

Niobium pentoxide (Nb₂O₅) is a polymorphic ceramic with semiconductor characteristics applied in various fields of study. In this work, the Nb₂O₅ synthesis by the spray pyrolysis route was compared to the hydrothermal technique. The obtained materials were characterized by N₂ physisorption (BET-N₂), average particle size distribution by dynamic light scattering (DLS), X-ray diffractometry (XRD), transmission electron microscopy (TEM), and X-ray fluorescence (XRF) spectroscopy. The material synthesized by the spray pyrolysis technique presented high specific area and pore volume, high crystallinity, homogeneity, and nanometric particles, thus representing a potential technique for the Nb₂O₅ synthesis.     

Applicability of quantitative polymerase chain reaction (qPCR) assays for common bean authentication in processed food

Food authentication by quantitative polymerase chain reaction (qPCR) methods assures food quality. The aim was to evaluate three qPCR assays for DNA quantification after heat processing of common bean grains, genus-specific FAS assay for Phaseolus, species-specific LEC assay for common bean (Phaseolus vulgaris) and genetically modified (GM) event-specific FGM assay for Embrapa 5.1 event GM common bean. FAS assay showed high stability among Phaseolus genus samples. Common bean grains were heat-treated in autoclave (at 120 °C for 15–60 min) and target DNA copy number decreased as processing time increased. Even with DNA degradation, qPCR assays were capable to detect low DNA quantity, and the limit of detection was 100 copy number. Mean efficiency value of FGM assay was 92% in the presence of background DNA. Background DNA did not cause any interference, and 0.39% of GM material can be detected. These qPCR assays are able to quantify common bean in processed food.     

Sensory study of different sodium chloride substitutes in aqueous solution

The reduction of salt (sodium chloride) in food is one of the major challenges facing the food industry today and is motivated by the positive association between dietary salt intake and some diseases. Thus, the objectives of this study were to determine the equivalent amount of different sodium chloride replacements required to promote the same degree of ideal saltiness in aqueous solution and to study the sensory profile of sodium chloride and its substitutes using temporal dominance of sensations (TDS) analysis. The relative potencies of potassium chloride, monosodium glutamate, potassium phosphate, calcium lactate and potassium lactate compared to an aqueous solution with 0.75% sodium chloride were 74.75%, 59.52%, 60.48%, 11.40% and 4.96%, respectively. An evaluation of the sensory profiles of potassium chloride, potassium phosphate, calcium lactate and monosodium glutamate revealed saltiness as well as other tastes, including bitterness, sourness, umami and an unidentified undesirable taste as being dominant. The potassium chloride was the only one which showed temporal sensory profile similar to sodium chloride.     

Shrinkage and Deformation of Agave atrovirens Karw Tissue during Convective Drying: Influence of Structural Arrangements

The influence of structural arrangements of Agave discs cut transversally (ADCT) and longitudinally (ADCL) on moisture loss, shrinkage, and shape was evaluated during convective drying by physical and image parameters.

ADCT showed lower drying and shrinkage rates than ADCL. The fractal exponent (d) relating volume and thickness of samples rose from 1.552 ± 0.126 to 2.394 ± 0.128 and from 1.662 ± 0.111 to 1.848 ± 0.070 for ADCT and ADCL, respectively, which indicates that shrinkage was nonisotropic for both cases.

Parameters considered for evaluating the changes of size and shape of Agave discs at macro- and microscopic levels during drying were projected area (PA), major length (ML), shape factor (SF), and fractal dimension of contour (FD_C). The values obtained for these parameters demonstrated that changes in shrinkage and shape of both samples were dependent on structural arrangements of the samples. During the drying of ADCT samples, which have short and rigid structures, pronounced creasing was observed compared to ADCL materials, which are mainly formed by long and rigid structures. Also, it was observed that orientation of fibers influenced shrinkage and deformation.