Biofilm formation in Haas palatal expanders with and without use of an antimicrobial agent: an in situ study

Orthodontic appliances causes specific alterations in oral environment, including reduction of pH, increase of dental biofilm and elevation of salivary microbial levels, causing an increased risk for dental caries. This study evaluated, using microbial culture and scanning electron microscopy (SEM), the in situ contamination by mutans streptococci (MS) of different surfaces of Haas palatal expanders with and without use of chlorhexidine gluconate mouthrinses (CHX). Thirty‐four patients were randomly assigned to two groups (n = 17/group), using placebo (Group I) and 0.12% CHX (Group II—Periogard^®) mouthrinses twice a week. After 4 months, appliances were submitted to microbiological processing and after fragments were analyzed by SEM. Mann–Whitney U test (α = 5%) was used to assess differences between groups on the appliances' different surfaces and to compare the contamination on the free and nonfree surfaces of these components. There was no difference (p = 0.999) between groups regarding the number of MS colonies/biofilms on the nonfree surfaces, which showed intense contamination. However, free surfaces of Group II presented less contamination (p < 0.001) than those of Group I in all appliances' components. Results of the microbial culture were confirmed by SEM. Use of 0.12% CHX was effective in reducing the formation of MS colonies/biofilms on free surfaces of Haas expanders, in situ.     

Formulation and characterization of chitosan-based biocomposites with potential use for bone adhesion

The effects of the addition of calcium carbonate (CC) and hydroxyapatite (HA) in chitosan-based biocomposites were studied keeping in mind their potential use as bone adhesives. The formation of coordination bonds between calcium ions and chitosan amino groups was evident, producing ionic cross-links between chitosan macromolecules, which changed chitosan gelation mechanisms, gel strengths, and adhesiveness into bone surfaces; CC concentration is a key factor in these phenomena. A formulation with 2% chitosan and 4% of both CC and HA showed the most promising performance having high levels of adhesion to bone surfaces (0.27?MPa) and a cohesive mode of failure.     

Expansive sulphate aluminate cements

The possibility to prepare expensive sulphate aluminate masses from certain wastes (phosphogypsum and belitic waste) and usual raw materials (limestone, bauxite) has been investigated. The chemical and minerological composition of these synthetic clinkers as well as the nature of their hydration products has been determined by current methods. The mechanism of cement expansion and the factors affecting the correlation between mechanical strength and expansion have been also studied.     

CAMMInA: a mobile ambient information system to motivate elders to exercise

Several strategies have been identified for designing effective persuasive technology that encourages people to adopt healthy lifestyle habits. However, to implement these strategies for motivating elders to exercise, we need to take into account the elders’ particular characteristics, their needs, and the problems they face to exercise. This paper presents the results of a case study conducted to identify the factors that influence elders to maintain a regular exercise routine. These results enabled us to inform the design of an ambient information system, which by requiring minimal attention and cognitive effort from elders, makes them aware of relevant information that motivates them to exercise. To reach this end, the system implements the following strategies for persuading: abstraction, historical information and reflection, triggers for exercising, and positive and playful reinforcement. A system usability evaluation enabled us to validate these strategies for motivating elders.     

Quality characteristics of angel food cake and muffin using lentil protein as egg/milk replacer

Replacement of animal proteins could be interesting for the food industry because it allows long‐term cost savings, among other reasons. Replacing egg/milk protein (50–100 wt%) by lentil protein (LP) was evaluated on angel cake/muffin quality. The replacement did not significantly affect final product volume, neither the muffins nor the angel food cakes. LP did not affect dough formation and contributed to hold crumb structure building an entangled network in both cake products. In addition, angel cakes and muffins containing LP had significantly lower baking loss than the control. Inferior quality for angel cakes and muffins containing LP was observed regarding hardness and chewiness that increased upon storage, compared to the control. For sensory evaluation in angel cakes, appearance of LP formulations showed lower scores than the control, likely due to the change of crumb colour. Other attributes were not significantly impacted by LP presence. For muffins, M‐100‐LPC formulation showed significant differences with the control for most of the attributes, except appearance and flavour. Indeed, consumers preferred muffins with 100% egg/milk protein replacement, which received higher acceptability scores than control. They also appreciated the ‘nutty’ flavour and moisture of angel cake with 50% egg protein replacement. This research suggests that lentil protein can totally or partially substitute egg/milk protein as foam and emulsion stabiliser in cakes, producing products with satisfactory quality.     

Hybrid organic/inorganic composites based on silica and weak synthetic polyelectrolytes

The preparation and characterization of new organic/inorganic composites by the consecutive adsorption of weak polyelectrolytes on silica particles were studied in the article. Two polycations containing primary amine groups in the side chains, poly(vinylamine) or poly[N(β-aminoethylene) acrylamide], and poly(acrylic acid) as polyanion were used for the hybrid materials construction. The stability of the organic/inorganic composites has been increased by a heat-induced reaction at 150 °C. The organic/silica hybrids properties were monitored by potentiometric titration, laser light scattering, infrared spectroscopy, and thermogravimetric analysis. The adsorption of methylene blue by the composite materials has been tested. The dye adsorption capacity was strongly influenced by the dye concentration, the nature of the last adsorbed layer, the polyions concentration, and the composite thermal treatment.     

Surface attachment of horseradish peroxidase to nylon modified by plasma‐immersion ion implantation

The surface of polyamide (nylon 6) was modified by plasma‐immersion ion implantation (PIII) with nitrogen ions. Structural changes associated with carbonization, oxidation, and depolymerization were observed in the modified surface layer with Fourier transform infrared/attenuated total reflection (FTIR–ATR) spectroscopy, surface energy measurements, and X‐ray photoelectron spectroscopy (XPS). The enzyme activity of surface‐attached horseradish peroxidase was studied with a tetramethylbenzidine colorimetric activity assay. Compared to untreated controls, the PIII‐treated surface showed a higher level of the attached protein with increased longevity of bioactivity. Detection of the immobilized protein layer was made difficult by the presence of amide groups in nylon. Here we demonstrate the potential of combining FTIR–ATR spectroscopy with XPS measurements for this purpose. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:2891–2903, 2011     

A DIFFUSION MODEL WITH A MOISTURE DEPENDENT DIFFUSION COEFFICIENT FOR PARBOILED RICE

A mathematical model describing moisture migration by diffusion in a solid sphere with variable diffusion coefficient is proposed. An analytical expression for dependence of the diffusion coefficient with moisture content was derived based on the assumption that the activation energy for diffusion varies linearly with the desorption energy.

The expression for moisture dependence of diffusion coefficient was used to simulate drying of parboiled rice in the temperature range 50-90°C. The mathematical model shows good agreement between observed and predicted drying rate curves.     

The effect of UV‐C in combination with H2O2 treatments on microbial response and quality parameters of fresh cut pear discs

The response of Escherichia coli ATCC 11229, Listeria innocua ATCC 33090 and Zygosaccharomyces bailii NRRL 7256 in fresh‐cut pear to simultaneous and serial combined treatments involving H₂O₂ immersion (3% w/v; pH 3.0; 25 °C; 2.0 or 5.0 min) and UV‐C exposure (7.5 min; 3.7 kJ m^?2) was investigated. For selected treatments, native flora, sensory and colour changes were also evaluated. E. coli and L. innocua were more sensitive than Z. bailii. Serial H₂O₂/UV‐C treatments were more effective than the simultaneous arrangement. The single effect of UV‐C was enhanced by the combination with 5 min H₂O₂, hence avoiding the recovery of the surviving population. The combined treatment kept optimal microbial stability and exhibited more luminosity than the single UV‐C treatment. Texture profile analysis conducted using a trained panel showed that H₂O₂/UV‐C processed pear discs were perceived with significantly less hardness and fracturability but as juicy as untreated discs. Consumers found them pleasant.