Phenolic content and antioxidant capacity versus consumer acceptance of soaked and vacuum impregnated frozen nectarines

Nectarines (Prunus persica L. cv. Maria Laura) were manually selected, cut in slices and divided into four groups: fresh, untreated frozen, soaked in osmotic solution and subsequently frozen, and vacuum impregnated (VI) and subsequently frozen. This investigation was focused on evaluation of consumer acceptance with respect to treated versus untreated frozen nectarine slices. In a preliminary acceptance test of untreated frozen nectarine slices, fruits were generally rejected on the basis of a darkened appearance and “oxidized” taste. These negative attributes were probably linked to the activity of polyphenol oxidase (PPO) and depletion of phenols due to cell rupture during freeze–thaw procedures. For these reasons, in order to evaluate the tendency of fruit to oxidation, several analyses were performed: the antioxidant capacity of phenolic fraction and the o-diphenol content were estimated by spectrophotometric assays, whereas the hydroxycinnamic acid (chlorogenic and neochlorogenic acids) composition was evaluated by high performance liquid chromatography (HPLC). Phenolic content and antioxidant capacity were found to correlate well with the acceptance level of frozen nectarine slices. In this regard a higher phenolic content associated with a higher acceptance level of nectarine samples.     

Effect of colloidal silica on the mechanical properties of fiber–cement reinforced with cellulosic fibers

The effect of colloidal silica on the hydration reaction of the Portland cement system and its effect on the resulting mechanical properties are not completely understood. Silica nanoparticles can affect the behavior and performance of fiber–cement, such as the calcium–silicate–hydrate gel of the matrix and the fiber–matrix interface bonding. The main objective of this study is to evaluate the effects of various contents of colloidal silica (0, 1.5, 3, 5, and 10 % w/w) on the microstructure and mechanical performance of cement composites reinforced with cellulosic pulp. Fiber–cement composites with unbleached eucalyptus Kraft pulp as the micro-fiber reinforcement were produced by the slurry dewatering technique followed by pressing. The average values of the modulus of rupture of the fiber–cement decreased with increasing colloidal silica content. However, the pullout of the fibers increased significantly in the fiber–cement composites with additions between 3 and 10 % w/w of colloidal silica suspension, as indicated in the scanning electron microscopy images and by the improvement in the energy of fracture values.     

Effects of High Pressure Treatments on Polymeric Films for Flexible Food Packaging

Effects of high pressure (HP) treatments on functional and morphological properties of commercial packaging films have been investigated, to assess their suitability for use in these processes. Experimental analyses have been performed on packaging films, used to make pouches containing four different types of food simulants, after HP pasteurization and sterilization treatments at 200, 500 and 700 MPa. The investigated polymeric flexible packaging structures were single layer as well as bilayer films. Effects of treatments on structural/morphological properties (i.e. crystallinity and density) and on thermodynamic and barrier properties were addressed. Quite all the investigated films were found to be suitable for HP pasteurization, which only determined a negligible effect on the glass transition temperatures and on density of the amorphous regions of some polymeric materials, without a significant effect on functional properties of the packaging. Only bilayer structures including metalized polyethyleneterephthalate were not able to withstand processing conditions because of an extensive delamination accompanied by loss of metallization layer. Conversely, in the case of HP sterilization, combined effects of HP and relatively high temperature caused significant modifications in some of the packaging materials, even those not including a metalized film. In particular, localized delamination occurred in the case of bilayer structures made by laminating polyethyleneterephtalate with linear low density polyethylene or with polypropylene. Films obtained by laminating cast polyamide and bioriented polyamide with polypropylene displayed no evidence of delamination. In the case of films not displaying delamination, only limited changes in gas and vapour barrier properties were detected. Copyright © 2014 John Wiley & Sons, Ltd.     

Hybrid Organic/Inorganic Nanostructures for Highly Sensitive Photoelectrochemical Detection of Dissolved Oxygen in Aqueous Media

Precise, reliable, and remote measurement of dissolved oxygen in aqueous media is of great importance for many industrial, environmental, and biological applications. In particular, photoelectrochemical sensors working in differential mode have recently demonstrated promising properties, in terms of stability, sensitivity, and application potential. Here, a new approach is presented, combining visible light sensitivity, efficient photocurrent generation, and solution‐processed fabrication methods of conjugated polymers, with charge carriers selectivity, energetic alignment favorable to efficient interfacial charge transfer and high surface area achievable by using metal oxide nanostructures. Extensive characterization and optimization of the hybrid organic/inorganic system are carried out, leading to the realization of an oxygen sensor device, based on nanostructured palladium oxide/poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole]/[6,6]phenyl‐C61‐butyric acid methyl ester (PdO/APFO‐3:PCBM) as materials of choice. State‐of‐the‐art sensitivity, amounting at ?5.87 μA cm^?2 ppm^?1, low background signal, in the order of ?4.85 μA cm^?2, good electrochemical stability for more than 2 h of continuous functioning and high reproducibility of the signal over the pH 1 to 10 range, are reported, making the hybrid device suitable for several practical uses. The results fully validate the mixed organic/inorganic approach for photoelectrochemical applications, and pave the way for its further exploitation in fields like waste water treatment, environmental monitoring, and water splitting.     

Deposition of lead and cadmium released by cigarette smoke in dental structures and resin composite

Cigarette smoke is a significant source of cadmium, lead, and toxic elements, which are absorbed into the human organism. In this context, the aim of this study was to investigate in vitro the presence of toxic elements, cadmium, and lead deriving from cigarette smoke in the resin composite, dentine, and dental enamel. Eight cylindrical specimens were fabricated from resin composite, bovine enamel, and root dentin fragments that were wet ground and polished with abrasive paper to obtain sections with 6‐mm diameter and 2‐mm thickness. All specimens were exposed to the smoke of 10 cigarettes/day during 8 days. After the simulation of the cigarette smoke, the specimens were examined with scanning electron microscopy (SEM) and the energy‐dispersive X‐ray analysis. In the photomicrographic analysis in SEM, no morphological alterations were found; however, the microanalysis identified the presence of cadmium, arsenic, and lead in the different specimens. These findings suggest that the deposition of these elements derived from cigarette smoke could be favored by dental structures and resin composite. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.     

Low band gap poly(1,4-arylene-2,5-thienylene)s with benzothiadiazole units: Synthesis, characterization and application in polymer solar cells

We describe the synthesis of two novel poly(1,4-arylene-2,5-thienylene)s P1 and P2 containing benzo[c][2,1,3]thiadiazole monomeric units via Suzuki-Miyaura polymerization of a thiophene diboronic ester with aryl diiodides. The use of a catalyst complex consisting of Pd(OAc)₂ in combination with the electron-rich biaryl phosphine S-Phos resulted in efficient polymerization reactions. The polymers synthesized, P1 and P2, were characterized by UV-vis spectroscopy and cyclic voltammetry. Theoretical calculations and electrochemical measurements on P1 suggested a favorable position of the molecular orbitals for employment in polymer solar cells in combination with PCBM. Devices containing P1:PCBM 1:2 in the active layer showed an efficiency of 1.2% by simple spin casting from chloroform.     

Fuel from plant cell walls: recent developments in second generation bioethanol research

As bioethanol from sugarcane and wheat falls out of favour due to concerns about food security, research is ongoing into genetically engineering model plants and microorganisms to find the optimum cell wall structure for the ultimate second generation bioethanol crop. Charis Cook and Alessandra Devoto highlight here the progress made to tailor the plant cell wall to improve the accessibility of cellulose by acting on the regulation, the structure or the relative composition of other cell wall components to ultimately improve saccharification efficiency. They also consider possible side effects of cell wall modification and focus on the latest advances made to improve the efficiency of digestion of lignocellulosic materials by cell wall degrading microorganisms.     

Comparison of nutritional and nutraceutical properties in cultivated fruits of Fragaria vesca L. produced in Italy

Individual sugars, organic acids, total polyphenols, vitamin C and antiradical activity (as measured by DPPH method) were quantified in cultivated Fragaria vesca berries, comparing different varieties (Regina delle Valli, Alpine, Sara and Valitutto) and different environments with regard to altitude. Cultivar effect mainly influenced the concentration of total polyphenols and antiradical activity which are strongly correlated (R² = 0.91; P = 0.001); conversely, altitude seemed to exert an influence in sugar and organic acid composition. The comparison of the general quality of the most diffused cultivar of F. vesca (Regina delle Valli and Alpine) evidenced that both cultivars have the same nutritional properties, whereas Regina delle Valli is better than Alpine from the point of view of total polyphenolic content (716 vs 471 mg catechin/100 g fresh weight) and radical scavenging activity (301 vs 219 ml DPPH solution/100 g fresh weight), thus resulting more attractive from the health protecting attributes point of view. F. vesca berries showed also a concentration of sugars, citric acid, malic acid and total polyphenols much higher than those reported in literature for Fragaria x ananassa.     

Optical and electronic properties of fluorene/thiophene/benzothiadiazole pseudorandom copolymers for photovoltaic applications

A new family of 9,9-bisalkylfluorene (F)/thiophene (T)/benzothiadiazole (B) π-conjugated copolymers for organic solar cells is reported. The structure of the reported copolymers is pseudorandom: in turn each F, T, B monomer unit is alternated to the other randomly distributed two units. Voltammetric, UV–visible, and photoluminescence measurements have been carried out to assess the optical and electronic properties of the synthesized materials. The occurring of photoinduced charge transfer towards a fullerene electron acceptor was investigated by photoluminescence quenching and light-induced electron spin resonance experiments. The copolymer having alternating thiophene monomer units and randomly distributed fluorene and benzothiadiazole units exhibits the most promising characteristics; the photophysic study shows that such polymer/fullerene blend could represent a novel and cheaper material to be used as convenient donor–acceptor system for polymer solar cells.     

Improved inference on a scalar fixed effect of interest in nonlinear mixed-effects models

Likelihood-based inference on a scalar fixed effect of interest in nonlinear mixed-effects models usually relies on first-order approximations. If the sample size is small, tests and confidence intervals derived from first-order solutions can be inaccurate. An improved test statistic based on a modification of the signed likelihood ratio statistic is presented which was recently suggested by Skovgaard [1996. An explicit large-deviation approximation to one-parameter tests. Bernoulli 2, 145-165]. The finite sample behaviour of this statistic is investigated through a set of simulation studies. The results show that its finite-sample null distribution is better approximated by the standard normal than it is for its first-order counterpart. The R code used to run the simulations is freely available.