Xylitol concentrations in artificial saliva after application of different xylitol dental varnishes

Objective: The present study analyzed xylitol concentrations in artificial saliva over time after application of varnishes containing 10% and 20% xylitol. Material and Methods: Fifteen bovine enamel specimens (8x4 mm) were randomly allocated to 3 groups (n=5/group), according to the type of varnish used: 10% xylitol, 20% xylitol and no xylitol (control). After varnish application (4 mg), specimens were immersed in vials containing 500 mu L of artificial saliva. Saliva samples were collected in different times (1, 8, 12, 16, 24, 48 and 72 h) and xylitol concentrations were analyzed. Data were assessed by two-way repeated-measures ANOVA (p<0.05). Results: Colorimetric analysis was not able to detect xylitol in saliva samples of the control group. Salivary xylitol concentrations were significantly higher up to 8 h after application of the 20% xylitol varnish. Thereafter, the 10% xylitol varnish released larger amounts of that polyol in artificial saliva. Conclusions: Despite the results in short-term, sustained xylitol releases could be obtained when the 10% xylitol varnish was used. These varnishes seem to be viable alternatives to increase salivary xylitol levels, and therefore, should be clinically tested to confirm their effectiveness.

Estudo da durabilidade de painéis de partículas de bagaço de cana de açúcar e resina poliuretana a base de óleo de mamona para aplicação na construção civil

O presente trabalho tem por objetivo avaliar o desempenho físico-mecânico e a durabilidade de painéis de partículas de bagaço de cana-de-açúcar com resina bicomponente a base de mamona (BCP) e compará-los com painéis de partículas de madeira comerciais (Medium Density Particleboard - MDP). Os painéis de bagaço de cana de açúcar foram fabricados com um teor de resina poliuretana a base de óleo de maona de 15%. O desempenho físico e mecânico dos painéis particulados foi analisado com base nas prescrições dos documentos normativos vigentes. Ambos os materiais foram revestidos superficialmente com resina poliuretana bicomponente à base de óleo de mamona. Avaliou-se a influência do tratamento das bordas na deterioração e no desempenho dos painéis. O acompanhamento das propriedades físico-mecânicas foi realizado antes e após os ensaios de envelhecimento por exposição natural durante 3, 6 e 12 meses, envelhecimento acelerado e de intemperismo artificial. Foi feita a avaliação, da suscetibilidade ao crescimento gerada pelo ataque de fungos emboloradores e apodrecedores nos materiais durante o envelhecimento natural e no ensaio acelerado. Foi realizada a análise colorimétrica para a identificação de mudanças de cor e brilho nos materiais após os ensaios de deterioração. Foram utilizadas as técnicas de densitometria de raios X, espectroscopia por infravermelho próximo (NIR). Os resultados obtidos indicaram a selagem lateral permitiu avaliar a superfície exposta do material permitindo a entrada da água pela superfície avaliando o efeito dos agentes de deterioração. A porcentagem de retenção para o Módulo de ruptura após o ensaio de envelhecimento por imersão em agua e secagem (APA D1) foi de 87% e 3% para BCP e MDP sem revestimento respectivamente e de 90% e 3% para BCP e MDP com revestimento. A porcentagem de retenção das propriedades mecânicas em ambos os submetidos à exposição natural diminuiu em função do tempo. Entretanto o porcentagem de retenção para os materiais BCP e MDP com revestimento superficial foi de 76% e 60% para MOR. A exposição natural mostrou que os fungos emboloradores foram predominantes em ambos os materiais. Ambos os materiais com revestimento superficial apresentaram entre 1-10% de colonização com um 70% de probabilidade. Revestimento de resina de óleo de mamona reduz o crescimento de fungos em ambos os materiais no ensaio acelerado. O perfil de densitometria permitiu analisar o processo de fabricação dos painéis e permitiu identificar a deterioração gradativa do ambos os materiais após os ensaios de envelhecimento. A intepretação mediante a analise de componentes principais (ACP) na aplicação do NIR comportou a classificação das características relacionadas a cada ensaio de deterioração de ambos os materiais sem revestimento superficial. Com base nos resultados deste trabalho, foram propostas contribuições para ajustes de metodologias para a avaliação da durabilidade e do desempenho físico e mecânico dos painéis particulados, tendo em vista a sua viabilidade técnica, em sistemas construtivos da construção civil.

The Use of a Pressure-Indicating Sensor Film to Provide Feedback upon Hydrogel-Forming Microneedle Array Self-Application In Vivo

PURPOSE:
To evaluate the combination of a pressure-indicating sensor film with hydrogel-forming microneedle arrays, as a method of feedback to confirm MN insertion in vivo.
METHODS:
Pilot in vitro insertion studies were conducted using a Texture Analyser to insert MN arrays, coupled with a pressure-indicating sensor film, at varying forces into excised neonatal porcine skin. In vivo studies involved twenty human volunteers, who self-applied two hydrogel-forming MN arrays, one with a pressure-indicating sensor film incorporated and one without. Optical coherence tomography was employed to measure the resulting penetration depth and colorimetric analysis to investigate the associated colour change of the pressure-indicating sensor film.
RESULTS:
Microneedle insertion was achieved in vitro at three different forces, demonstrating the colour change of the pressure-indicating sensor film upon application of increasing pressure. When self-applied in vivo, there was no significant difference in the microneedle penetration depth resulting from each type of array, with a mean depth of 237 μm recorded. When the pressure-indicating sensor film was present, a colour change occurred upon each application, providing evidence of insertion.
CONCLUSIONS:
For the first time, this study shows how the incorporation of a simple, low-cost pressure-indicating sensor film can indicate microneedle insertion in vitro and in vivo, providing visual feedback to assure the user of correct application. Such a strategy may enhance usability of a microneedle device and, hence, assist in the future translation of the technology to widespread clinical use.

Synthesis and characterization of lanthanum- and yttrium-doped Fe2O3 pigments

MELO, D. M. A. et al. Synthesis and charactezarion of lanthanum and yttrium doped Fe2O3 pigments. Cerâmica, São Paulo, v. 53, p. 79-82, 2007.

Synthesis and characterization of lanthanum- and yttrium-doped Fe2O3 pigments

MELO, D. M. A. et al. Synthesis and charactezarion of lanthanum and yttrium doped Fe2O3 pigments. Cerâmica, São Paulo, v. 53, p. 79-82, 2007.

Caraterização físico-química e polínica de méis da Beira Alta

A apicultura é uma atividade em crescimento em Portugal, e por isso é cada vez mais importante caracterizar os produtos que dela derivam, e em particular o mel que é, em geral, o mais conhecido pelos consumidores. A designação DOP (Denominação de Origem Protegida) pode representar uma valorização em termos comerciais, podendo ser uma forma de diferenciação do mel português em contexto nacional e internacional. Deste modo é importante o conhecimento das suas características físico-químicas e polínicas, como fonte de demonstração dessa mesma diferenciação. O presente trabalho faz parte de um projeto de caraterização físico-química e polínica de méis, como contributo para a certificação do mel da Beira Alta como produto DOP. Recolheram-se amostras de méis produzidos pelos associados da Associação dos Apicultores da Beira Alta (AABA), no ano de 2014, afetos a 10 concelhos da área de intervenção da AABA. Os respetivos apiários localizam-se nos concelhos de Viseu, Tondela, Carregal do Sal, Nelas, Penalva do Castelo, Satão, Aguiar da Beira, Mangualde, Sernancelhe e Fornos de Algodres. Foram estudadas 27 amostras de méis representativas da região da Beira Alta de acordo com o número de unidades epidemiológicas dentro de cada concelho. Os resultados para cada parâmetro analisado foram obtidos em triplicado. O pH variou entre 3,4 e 4,3; o teor de água entre 17,5 e 19,7%; o teor de sólidos solúveis totais entre 80,3 e 82,5%; a condutividade elétrica entre 0,29 e 0,82 mS/cm; cinzas totais entre 0,2 e 0,6%; e ácidos livres entre 15 e 57 meq/kg. Para a determinação da cor, recorreu-se à análise colorimétrica, tendo-se efetuado 20 determinações por amostra, obtendo-se um intervalo de variação para L entre 23,08 e 75,51, a entre -0,30 e 16,76 e b entre -1,31 e 58,36. Para a caraterização polínica dos méis construiu-se uma palinoteca de referência da flora da região, sendo as preparações de pólen elaboradas de acordo com o método acetolítico. A análise polínica quantitativa revelou que 4 amostras de méis enquadraram-se na Classe I (<20 000 grãos de pólen por 10g de mel) e as restantes 23 na Classe III (100 000 a 500 000 grãos de pólen por 10g de mel). Na análise polínica qualitativa verificou-se que 11 dos méis analisados eram multiflorais (41%), 15 monoflorais de tília (56%) e 1 monofloral de urze (4%). O pólen de Eucalyptus sp. e de Castanea sativa esteve presente em 100% das amostras.Com estes primeiros resultados pretende-se contribuir para uma caracterização mais vasta da apicultura da Beira Alta e dos méis produzidos nesta região.

Efeito da adição dos azocorantes DR73 e DB79 nas propriedades do poli(metacrilato de metila)

Currently new polymeric materials have been developed to replace other of traditionally materials classes. The use of dyes allows to expand and to diversify the applications in the polymeric materials development. In this work the behavior and ability of azo dyes Disperse Blue 79 (DB79) and Disperse Red 73 (DR73) on poly(methyl methacrylate) (PMMA) were studied. Two types of mixtures were used in the production of masterbatches: 1) rheometer 2) solution. Processing by extrusion-blow molding of PMMA was carried out in order to evaluate the applications of polymeric films. Thermal analysis were performed by thermogravimetry to evaluate polymer and azo dyes thermal stability. Colorimetric analysis were obtained through monitoring the spectral variations associated with sys/trans/anti azo dyes isomerization process Colorimetric data were treated and evaluated in accordance to the color system RGB and CIEL*ab, by monitoring the color change as function of time. Mechanical properties, characterized by tensile tests, were evaluated and correlated with the presence and content of azo dyes in the samples. Analyses by scanning electronic microscopy (SEM) were performed on the surfaces of samples to check the azo dye dispersion after the mixing process. It was concluded that the production of PMMA/azo dyes is possible and feasible, and the mixtures produced had synergy of properties for use in various applications

Incorporation des protéines de canola dans du pain sans gluten : impact technologique et modélisation du processus de cuisson

L’objectif de cette maîtrise est de développer une matrice alimentaire sans gluten par l’incorporation des protéines de canola (PC) dans une farine de riz blanc afin d’offrir aux personnes intolérantes au gluten un produit de bonne qualité d’un point de vue organoleptique (volume massique, structure alvéolaire et couleur) et de valeur nutritionnelle. La matrice sélectionnée est du pain à base de farine de riz blanc. Cinq formulations ont été testées dans la première partie de ce travail : témoin-1 (blé tendre), témoin-2 (100% riz), pain de riz +3% PC, pain de riz + 6% PC, pain de riz + 9% PC. Les produits obtenus ont été caractérisés à toutes les étapes de fabrication en utilisant différentes techniques : poussée volumique, variation thermique au cours des étuvages et de la cuisson, pH (acidité), perte d’eau, volume massique, analyse colorimétrique, dosage des protéines et analyse du profil de la texture. Dans la deuxième partie, deux variables indépendantes ont été additionnées; soit shortening (1, 2, 3%) et gomme de xanthane (0.5, 1, 1.5%), dans le but d’améliorer le volume massique de la meilleure formulation obtenue dans l’étape précédente. Ensuite, des essais de correction ont été attribués aux produits obtenus par l’introduction du bicarbonate de sodium (0.5, 1, 1.5%) et d’huile de canola à la place du shortening (1, 2, 3%). Les tests de panification ont donné différents volumes massiques et structures alvéolaires qui étaient jugés de qualité inférieure à celle du témoin-1 (2.518 mL/g), mais largement supérieure à celle du témoin-2 (1.417 mL/g). Le meilleur volume massique obtenu est de 1.777 mL/g, correspondant à celui du pain obtenu par la combinaison 6%PC+0.5%GH+B 1.5%+ H3%. Finalement, les résultats de ce projet ont montré l’impact positif de l’incorporation des protéines de canola dans un pain sans gluten à base de farine de riz blanc. Ce travail constitue une contribution à la possibilité de substituer le gluten par d’autres protéines ayant de bonnes propriétés techno-fonctionnelles, en particulier la capacité à donner du volume au produit final.

Development of a colorimetric assay for heparanase activity suitable for kinetic analysis and inhibitor screening

The role that heparanase plays during metastasis and angiogenesis in tumors makes it an attractive target for cancer therapeutics. Despite this enzyme’s significance, most of the assays developed to measure its activity are complex. Moreover, they usually rely on labeling variable preparations of the natural substrate heparan sulfate, making comparisons across studies precarious. To overcome these problems, we have developed a convenient assay based on the cleavage of the synthetic heparin oligosaccharide fondaparinux. The assay measures the appearance of the disaccharide product of heparanase-catalyzed fondaparinux cleavage colorimetrically using the tetrazolium salt WST-1. Because this assay has a homogeneous substrate with a single point of cleavage, the kinetics of the enzyme can be reliably characterized, giving a Km of 46 μM and a kcat of 3.5 s−1 with fondaparinux as substrate. The inhibition of heparanase by the published inhibitor, PI-88, was also studied, and a Ki of 7.9 nM was determined. The simplicity and robustness of this method, should, not only greatly assist routine assay of heparanase activity but also could be adapted for high-throughput screening of compound libraries, with the data generated being directly comparable across studies.

Analysis of the colorimetric properties of goniochromatic colors using the MacAdam limits under different light sources

Technological innovation in all areas has led to the appearance in recent years of new metallic and pearlescent materials, yet no exhaustive studies have been conducted to assess their colorimetric capabilities. The chromatic variability of these special-effect pigments may largely be due to the three-dimensional effect of their curved shapes and orientations when they are directionally or diffusely illuminated. Our study examines goniochromatic colors using the optimal colors (MacAdam limits) associated with normal colors (photometric scale of relative spectral reflectance from 0 to 1) under certain conventional illuminants and other light sources. From a database of 91 metallic and interference samples and using a multi-gonio-spectrophotometer, we analyzed samples with lightness values of more than 100 and others with lightness values of less than 100, but with higher chromaticities than optimal colors, which places them beyond the MacAdam limits. Our study thus demonstrates the existence of chromatic perceptions beyond the normal solid color associated with these materials and independent of the light source. The challenge for future research, therefore, is to replicate and render these color appearances in current and future color reproduction technologies for computer graphics.

Stimuli-responsive colorimetric and NIR fluorescence combination probe for selective reporting of cellular hydrogen peroxide

Hydrogen peroxide (H2O2) is a key reactive oxygen species and a messenger in cellular signal transduction apart from playing a vital role in many biological processes in living organisms. In this article, we present phenyl boronic acid-functionalized quinone-cyanine (QCy-BA) in combination with AT-rich DNA (exogenous or endogenous cellular DNA), i.e., QCy-BA subset of DNA as a stimuli-responsive NIR fluorescence probe for measuring in vitro levels of H2O2. In response to cellular H2O2 stimulus, QCy-BA converts into QCy-DT, a one-donor-two-acceptor (D2A) system that exhibits switch-on NIR fluorescence upon binding to the DNA minor groove. Fluorescence studies on the combination probe QCy-BA subset of DNA showed strong NIR fluorescence selectively in the presence of H2O2. Furthermore, glucose oxidase (GOx) assay confirmed the high efficiency of the combination probe QCy-BA subset of DNA for probing H2O2 generated in situ through GOx-mediated glucose oxidation. Quantitative analysis through fluorescence plate reader, flow cytometry and live imaging approaches showed that QCy-BA is a promising probe to detect the normal as well as elevated levels of H2O2 produced by EGF/Nox pathways and post-genotoxic stress in both primary and senescent cells. Overall, QCy-BA, in combination with exogenous or cellular DNA, is a versatile probe to quantify and image H2O2 in normal and disease-associated cells.

Polyethyleneimine-Functionalized Platinum Nanoparticles with High Electrochemiluminescence Activity and Their Applications to Amplified Analysis of Biomolecules

Polyethyleneimine-functionalized platinum nanoparticles (PtNPs) with excellent electrochemiluminescence (ECL) properties were synthesized and applied to the amplified analysis of biomolecules. These particles were prepared at room temperature, with hyperbranched polyethyleneimine (HBPEI) as the stabilizer. The UV/Vis absorption spectra and transmission electron microscopy images clearly confirmed the formation of monodisperse PtNPs. Such particles proved to possess high stability against salt-induced aggregation, enabling them to be employed even under high-salt conditions. Owing to the existence of many tertiary amine groups, these particles exhibited excellent ECL behavior in the presence of tris(2.2'-bipyridyl)ruthenium(II). An HBPEI-coated particle possessed an ECL activity that was at least 60 times higher than that of a tripropylamine molecule. Furthermore, these particles could be immobilized on the 3-aminopropyltriethoxysilane-treated quartz substrates to amplify the binding sites for carboxyl groups. Through this approach, PtNPs were applied to the amplified analysis of the hemin/G-quadruplex DNAzyme by using the luminol/H2O2 chemiluminescence method.

Label-Free Colorimetric Detection of Aqueous Mercury Ion (Hg2+) Using Hg2+-Modulated G-Quadruplex-Based DNAzymes

Mercury ion (Hg2+) is able to specifically bind to the thymine-thymine (T-T) base pair in a DNA duplex, thus providing a rationale for DNA-based selective detection of Hg2+ with various means. In this work, we for the first time utilize the Hg2+-mediated T-T base pair to modulate the proper folding of G-quadruplex DNAs and inhibit the DNAzyme activity, thereby pioneering a facile approach to sense Hg2+ with colorimetry. Two bimolecular DNA G-quadruplexes containing many T residues are adopted here, which function well in low- and high-salt conditions, respectively. These G-quadruplex DNAs are able to bind hemin to form the peroxidase-like DNAzymes in the folded state. Upon addition of Hg2+, the proper folding of G-quadruplex DNAs is inhibited due to the formation of T-Hg2+-T complex. Ibis is reflected by the notable change of the Soret band of hemin when investigated by using UV-vis absorption spectroscopy. As a result of Hg2+ inhibition, a sharp decrease in the catalytic activity toward the H2O2-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is observed, accompanied by a change in solution color. Through this approach, aqueous Hg2+ can be detected at 50 nM (10 ppb) with colorimetry in a facile way, with high selectivity against other metal ions.