A New Age for Quercus spp. Fruits: Review on Nutritional and Phytochemical Composition and Related Biological Activities of Acorns

The current global food system must adapt to the expected growth of world population (about 9 billion individuals by 2050). This adaptation will probably include an increased consumption of edible wild foods, due to their richness in micronutrients and bioactive compounds, besides providing a cost‐effective and sustainable way of improving caloric food security. A striking example of such natural matrices is the Quercus genus, which has the additional advantage of being widespread throughout the Northern Hemisphere. In a traditional sense, Quercus fruits (acorns) were mainly used in animal feeding, despite their potentially important role on the rural economy. But this preconception is changing. In fact, their nutritional value, high contents in phytochemical compounds, biological activity (such as antioxidant, anticarcinogenic, and cardioprotective properties) and use in the treatment of specific diseases (such as atherosclerosis, diabetes, or Alzheimer's disease) have raised the interest in integrating acorns into the human diet. Accordingly, this comprehensive overview was designed to provide an evidence‐based review of the literature, with the objective to achieve useful conclusions regarding the nutritional properties, methodologies of extraction, identification, and characterization of a wide variety of bioactive compounds and scientifically validated bioactivities in Quercus species worldwide. The industrial by‐products from acorn oil extraction or flour production are also included. Data regarding the analytical techniques, individual compounds, and their bioactivities, are organized in tables. The reported data are discussed and directions for further investigations are suggested, highlighting the use of acorns in food, nutraceutical, and pharmaceutical applications.     

Evaluation of the Antimicrobial Potential of Alginate and Alginate/Chitosan Films Containing Potassium Sorbate and Natamycin

The antimicrobial potential of alginate films (AFs) and alginate/chitosan composite films with two different mass proportions of the biopolymers, 82.5:17.5 (CF1) and 65:35 (CF2), containing potassium sorbate (KS) or natamycin was evaluated. At the practical limit of KS addition (0.17 g KS per gram of alginate) for pure AFs, no inhibition zones were observed against Debaromyces hansenii, Penicillium commune and Penicillium roqueforti by the agar diffusion test. Above this concentration, films became opaque, brittle and showed a whitish precipitate over their surface, making them not suitable for use. However, alginate and alginate/chitosan composite films containing natamycin were able to inhibit the growth of the three microorganisms listed above. Natamycin was effective at concentrations as low as 0.005 g per gram of biopolymer for AF and 0.01 g per gram of biopolymer for both composite films, alginate/chitosan 65:35 (CF1) and alginate/chitosan 82.5:17.5 (CF2) against all microorganisms tested. The inhibitory zone diameter increased as concentration of natamycin increased. Active films containing 0.04 g natamycin per gram of biopolymer obtained in the present study exhibited suitable functional attributes and showed excellent perspectives as active antimicrobial films intended for food protection applications. Copyright © 2012 John Wiley & Sons, Ltd.     

Microstructure,thermooxidation and mechanical behavior of a novel highly linear,vitamin E stabilized,UHMWPE

A novel, vitamin E-stabilized, medical grade ultra-high molecular polyethylene, MG003 (DSM Biomedical; The Netherlands), has been very recently introduced for use in total joint replacements. This homopolymer resin features average molecular weight similar to that of conventional GUR 1050 resin (5.5–6*10⁶ g/mol), but a higher degree of linearity. The aim of this study was to characterize the microstructure, thermal and thermooxidation properties as well as the mechanical behavior of this novel MG003 resin before and after gamma irradiation in air to 90 kGy. For this purpose, a combination of experimental techniques were performed including differential scanning calorimetry (DSC), thermogravimetry (TG), transmission electron microscopy (TEM), X-Ray Diffraction, electron paramagnetic resonance (EPR), and uniaxial tensile tests. As-consolidated MG003 materials exhibited higher crystalline contents (~ 62%), transition temperatures (~ 140 °C), crystal thickness (~ 36 nm), yield stress (~ 25 MPa) and elastic modulus (~ 400 MPa) than GUR 1050 controls (55%, 136 °C, 27 nm, 19 MPa, and 353 MPa, respectively). Irradiation produced similar changes in both MG003 and GUR 1050 materials, specifically increased crystallinity (63% and 60%, respectively), crystal thickness (39 nm and 30 nm), yield stress (27 MPa and 21 MPa), but, above of all, loss of elongation to breakage (down to 442 and 469%, respectively). Thermogravimetric and EPR results suggest comparable susceptibilities to oxidation for both MG003 and GUR 1050 polyethylenes. Based on the present findings, MG003 appears as a promising alternative medical grade polyethylene and it may satisfactorily contribute to the performance of total joint replacements.     

Synthesizing higher nitride of molybdenum (Mo) and iron (Fe) in ammonia (NH3) gas stream under irradiation of concentrated solar beam in a solar furnace

Flowing gaseous ammonia NH₃ with suppressed extent of dissociation (un‐cracked NH₃) is acknowledged to function as a powerful nitriding medium to realize formation of metal nitride MN_x with considerably high N/M ratio x that cannot be achieved through reaction of M with N₂ gas. For example, mono‐nitride δ‐MoN of Mo and ε‐FeN_x phase of Fe with x = 0.33 ? 0.50 (i. e. hypo‐stoichiometric sub‐nitride ε‐Fe₂N) were reported to be difficult to prepare in N₂ gas environment even at elevated pressure but might be synthesized in flowing NH₃ gas at normal pressure when reaction temperature and NH₃ gas flow rate were set adequately. In the present work, nitriding experiments for Mo and Fe were carried out in flowing NH₃ gas under irradiation with concentrated solar beam. The acquired experimental evidences demonstrated that temperature range for formation of δ‐MoN was somewhat extended in flowing NH₃ gas under heating with concentrated solar beam compared with that under heating in conventional laboratory or industrial electric furnace. On the other hand, no such merit of extending temperature range for formation of ε‐Fe₂N in flowing NH₃ gas was detected in the present work under heating with concentrated solar beam.     

Catalysts of Ni/α-Al2O3 and Ni/La2O3-αAl2O3 for hydrogen production by steam reforming of bio-oil aqueous fraction with pyrolytic lignin retention

This paper reports on the steam reforming, in continuous regime, of the aqueous fraction of bio-oil obtained by flash pyrolysis of lignocellulosic biomass (sawdust). The reaction system is provided with two steps in series: i) thermal step at 200 °C, for the pyrolytic lignin retention, and ii) reforming in-line of the treated bio-oil in a fluidized bed reactor, in the range 600–800 °C, with space-time between 0.10 and 0.45 g_catalyst h (g_bio-oil)⁻¹. The benefits of incorporating La₂O₃ to the Ni/α-Al₂O₃ catalyst on the kinetic behavior (bio-oil conversion, yield and selectivity of hydrogen) and deactivation were determined. The significant role of temperature in gasifying coke precursors was also analyzed. Complete conversion of bio-oil is achieved with the Ni/La₂O₃-αAl₂O₃ catalyst, at 700 °C and space-time of 0.22 g_catalyst h (g_bio-oil)⁻¹. The catalyst deactivation is low and the hydrogen yield and selectivity achieved are 96% and 70%, respectively.     

Compatibilization of commingled plastics with maleic anhydride modified polyethylenes and ultraviolet preirradiation

The improvement of the properties of commingled plastics was carried out with a prototype blend of Mexican municipal plastic waste with and without poly(vinyl chloride) (PVC). Compatibilizing agents such as high‐density, low‐density, and linear low‐density polyethylenes modified with maleic anhydride were used. The agents were prepared in the laboratory with peroxide, and their usefulness was compared with that of a commercially modified linear low‐density polyethylene. The blends with PVC were preirradiated with ultraviolet radiation for 12, 24, or 48 h to create oxidized groups to help in situ compatibilization during the blending step of the reactive extrusion process. Compatibilized materials showed a markedly more homogeneous morphology with improved mechanical properties: the elongation at break and impact strength increased with the compatibilization level. The presence of PVC in commingled plastics significantly reduced the beneficial effect of the maleic anhydride modified polyethylene as a compatibilizer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Feasibility of determining corrosion rates by means of stray current-induced polarisation

To measure metal corrosion it is necessary to make direct physical contact with the specimen or component acting as the working electrode. The most widely used method for determining the corrosion current is electrochemical, the so-called polarisation resistance method. The feasibility of a new method to polarise the metal without the need for direct physical contact was investigated in the present study. The required potential shift is obtained by induction of a current using an external electrical field. The model used for calculation of the corrosion rate assumes that the applied current runs in parallel through the electrolyte and the metal, and electrostatically polarises the metal. The overall electrical resistance of the system can then be expressed as , where R _e+M is the total resistance measured, R _e is electrolyte resistance and R _M is resistance due to the metal. This latter resistance to electrostatic polarisation is related to the faradaic reaction, which was verified by comparison with the gravimetric losses. This resistance has been called inductive polarisation resistance R _pi to distinguish it from the traditional polarisation resistance R _p.     

Moisture curing kinetics of isocyanate ended urethane quasi‐prepolymers monitored by IR spectroscopy and DSC

The study of the kinetics of the curing of isocyanate quasi‐prepolymers with water was performed by infrared spectroscopy and differential scanning calorimetry. The influence of the free isocyanate content, polyol functionality, and of the addition of an amine catalyst (2,2′‐dimorpholinediethylether) in the reaction kinetics and morphology of the final poly(urethane urea) was analyzed. A second‐order autocatalyzed model was successfully applied to reproduce the curing process under isothermal curing conditions, until gelation occurred. A kinetic model‐free approach was used to find the dependence of the effective activation energy (E_a) with the extent of cure, when the reaction was performed under nonisothermal conditions. The dependence of E_a with the reaction progress was different depending on the initial composition of the quasi‐prepolymer, which reveals the complexity of the curing process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008