Photochemical behaviour of activated carbons under UV irradiation

A series of activated carbons were used to investigate the photochemical behaviour of carbons under UV light as catalysts in the photo-oxidation of phenol in the absence of semiconductor additives. Conventional photocatalytic tests showed an improved photo-oxidation in the presence of activated carbons, beyond the so-called synergistic effect reported in the literature for carbon/titania composites. A novel approach based on UV irradiation of carbons pre-loaded with phenol was used to demonstrate the anomalous photochemical response of carbon materials towards phenol degradation. Analysis of the catalytic reaction from a different standpoint (inside the carbonaceous matrix) demonstrated the catalytic activity of certain carbon materials for phenol photodegradation, without considering photolytic breakdown and adsorption kinetics. The pseudo photochemical quantum yield of several activated carbons was higher than that of photolysis under the same conditions; the nature of the degradation intermediates was also modified in the presence of the carbon materials. Moreover, the degradation of the adsorbed fraction retained inside the pore structure of the carbons has been demonstrated. Our results suggest the occurrence of carbon–photon interactions which could be propagated through the graphene sheets of the materials, and could reach the adsorbed molecules inside the pores.     

Industrial orange juice debittering: effect on volatile compounds and overall quality attributes

This study was aimed to analyse the impact of the debittering process (DP) in the overall sensory properties of orange juice (OJ) (Citrus sinensis L. Var. Salustiana). The fresh industrial squeezed orange juice (FOJ) and the corresponding OJ after the DP (DOJ) were taken. No significant differences were found in acidity, pH and total soluble solids. Colour was evaluated by image analysis (DigiEye System). Hue and lightness were lower (more reddish and darker) after debittering (P < 0.001). Odour profile (limonene, α‐pinene, ethyl butanoate, octanal, linalool, citral and terpineol) decreased significantly (from 16% to 61% on average) as well as total phenolic compounds measured by Folin–Ciocalteu (P < 0.05). The influence of the debittering on the perceived colour, smell and taste was evaluated by paired comparison tests. The naïve panellists found significant differences not only in taste but also in colour and aroma between FOJ and DOJ; however, preference was not clear.     

A rapid spectrophotometric method for the determination of peroxide value in food lipids with high carotenoid content

A rapid and sensitive ultraviolet-visible spectrophotometric method for determination of peroxide value (PV) in foods with high carotenoid content (e.g., paprika oleoresin, paprika powder, red palm oil) has been developed. The proposed protocol [modified International Dairy Federation (IDF) method] was established from the IDF Fe(II)-oxidation-based spectrophotometric method, and the main one of the introduced modifications consisted of a clean-up extraction step of pigments before determining the PV by complexing Fe(III) ions with thiocyanate. Fe(II) oxidation time, reaction medium, and Fe(III)-thiocyanate complex formation time were optimized. The modified IDF method was compared with and was validated by iodometric AOAC official method with a good correlation (R ²=0.957) between data obtained by both analytical methods. The high sensitivity of the method allows the use of only about 0.010–0.015 g of sample, with a detection limit of 0.044 mequiv peroxide/kg of sample. Therefore, an improved spectrophotometric method for assessing PV in food lipids with high carotenoid content is now available and can be applied to any kind of sample, independent of oil and pigment content.     

Could Radiotherapy Effectiveness Be Enhanced by Electromagnetic Field Treatment?

One of the main goals in radiobiology research is to enhance radiotherapy effectiveness without provoking any increase in toxicity. In this context, it has been proposed that electromagnetic fields (EMFs), known to be modulators of proliferation rate, enhancers of apoptosis and inductors of genotoxicity, might control tumor recruitment and, thus, provide therapeutic benefits. Scientific evidence shows that the effects of ionizing radiation on cellular compartments and functions are strengthened by EMF. Although little is known about the potential role of EMFs in radiotherapy (RT), the radiosensitizing effect of EMFs described in the literature could support their use to improve radiation effectiveness. Thus, we hypothesized that EMF exposure might enhance the ionizing radiation effect on tumor cells, improving the effects of RT. The aim of this paper is to review reports of the effects of EMFs in biological systems and their potential therapeutic benefits in radiotherapy.     

A randomised, double-blind, placebo controlled cross-over study to determine the gastrointestinal effects of consumption of arabinoxylan-oligosaccharides enriched bread in healthy volunteers

ABSTRACT: BACKGROUND: Prebiotics are food ingredients, usually non-digestible oligosaccharides, that are selectively fermented by populations of beneficial gut bacteria. Endoxylanases, altering the naturally present cereal arabinoxylans, are commonly used in the bread industry to improve dough and bread characteristics. Recently, an in situ method has been developed to produce arabinoxylan-oligosaccharides (AXOS) at high levels in breads through the use of a thermophilic endoxylanase. AXOS have demonstrated potentially prebiotic properties in that they have been observed to lead to beneficial shifts in the microbiota in vitro and in murine, poultry and human studies. METHODS: A double-blind, placebo controlled human intervention study was undertaken with 40 healthy adult volunteers to assess the impact of consumption of breads with in situ produced AXOS (containing 2.2 g AXOS) compared to non-endoxylanase treated breads. Volatile fatty acid concentrations in faeces were assessed and fluorescence in situ hybridisation was used to assess changes in gut microbial groups. Secretory immunoglobulin A (sIgA) levels in saliva were also measured. RESULTS: Consumption of AXOS-enriched breads led to increased faecal butyrate and a trend for reduced iso-valerate and fatty acids associated with protein fermentation. Faecal levels of bifidobacteria increased following initial control breads and remained elevated throughout the study. Lactobacilli levels were elevated following both placebo and AXOS-breads. No changes in salivary secretory IgA levels were observed during the study. Furthermore, no adverse effects on gastrointestinal symptoms were reported during AXOS-bread intake. CONCLUSIONS: AXOS-breads led to a potentially beneficial shift in fermentation end products and are well tolerated.     

A review of current PCR-based methodologies for the authentication of meats from game animal species

The authenticity of food is currently a major issue for researchers, consumers, industries and policy markers at all levels of the production process. Particularly in the meat industry, products from game animals are susceptible targets for fraudulent labeling due to the economic profit that results from selling cheaper meat as meat from more profitable and desirable species. A part from meat species adulteration, illegal poaching of endangered game species may take place contributing to threat of wildlife populations. These reasons have encouraged the development of methods to ensure fair trade and labeling of game meats from production level to consumer use of end products. In the last years, full attention has been turning towards implementation of molecular genetic approaches for meat species identification because of their high sensitivity and specificity, as well as rapid processing time and low cost. This work presents an overview of the main PCR-based techniques applied to date to verify the authenticity of meat and meat products from game species.     

Structural and kinetic study of phase transitions in LaYSi2O7

Phase transitions in LaYSi₂O₇ have been investigated as a function of temperature using XRD, NMR and TEM. Previously described empirical crystal structure guidelines based on average cation radius in rare-earth RE₂Si₂O₇-type disilicates predict a stable tetragonal A-LaYSi₂O₇ polymorph at temperatures below 1500 °C. This study demonstrates that A-LaYSi₂O₇ is not thermodynamically stable at these temperatures and suggests that guidelines based on average cation size do not accurately describe the equilibrium behaviour of this silicate system. The A to G-type polymorph transition is extremely sluggish; complete transformation requires ～250 h at 1200 °C, and more than 3 weeks of calcination at 1100 °C. This observation is important when this type of material is used as environmental barrier coating (EBC) of advanced ceramics. Analysis of XRD and TEM data reveal complete substitution of Y and La on the rare-earth cation sites in both LaYSi₂O₇ polymorphs, but indicate preferential site occupancies in the G-type polymorph.     

The influence of mode mixity and adhesive system on the fatigue life of adhesive joints

In real applications, adhesive joints are commonly subjected to fatigue and mixed mode loading conditions. The aim of the current work is to experimentally analyse the influence of mode mixity on the fatigue strength of joints with an epoxy‐based adhesive. Different adhesive systems (acrylic and epoxies) were considered for pure mode I fatigue loading conditions. To achieve this, Arcan joints with an epoxy adhesive were manufactured and tested at different mode mixities. Based on stiffness degradation, monitored during the tests, damage evolution was calculated for different loading conditions and for all the tested adhesives. Finally, fatigue envelopes were constructed for different fatigue life regimes. Results show that a shear loading component reduces both the static strength and fatigue life of the joints. A small reduction rate of the stiffness was found throughout the most part of the life until a sudden drop was observed, indicating a smooth damage evolution.     

Symmetric and asymmetric dynamic characterization of mode‐III fracture in epoxy/unidirectional carbon‐fibre composites

This paper experimentally analyses the delamination behaviour of a composite material under mode III fracture as a function of the loading mode applied during the fatigue tests was carried out in two different ways. First, the test specimens were loaded cyclically in a single direction of delamination until reaching a certain fracture energy and subsequently returning to the starting point. Second, cyclic loading was applied both in one direction of delamination and in the opposite direction until reaching the same fracture energies, though in two opposite directions. The experimental results revealed clear differences in the fatigue behaviour of the material when the way of applying the load varied. In both cases, a statistical analysis of the results was carried out in order to evaluate the existing differences more suitably. Furthermore, a fractographic analysis was conducted for both types of loading in order to distinguish possible differences at the microstructural level.