Miscibility and specific interactions in blends of poly(vinyl phenyl ketone hydrogenated) with poly(2,6‐dimethyl‐1,4‐phenylene oxide)

The miscibility behavior of poly(vinyl phenyl ketone hydrogenated) (PVPhKH) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) are studied by differential scanning calorimetry, thermomechanical analysis, and FTIR spectroscopy. Two miscibility windows between 10 to 40 and 60 to 90 wt % PPO are detected. Only the blend with 50 wt % PPO is immiscible. The best fit of the Gordon–Taylor equation of the experimental glass‐transition temperatures for miscible PVPhKH/PPO blends is shown. A study by FTIR spectroscopy suggests that hydrogen bonding interactions are formed between the hydroxyl groups of PVPhKH and the ether groups of PPO. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1887–1892, 2004     

Block and random copolyamides of poly(m‐xylylene adipamide) and poly(hexamethylene isophthalamide‐co‐terephthalamide): Methods of preparation and relationships between molecular structure and phase behavior

Copolymerization of poly(m‐xylylene adipamide) (MXD6) and poly(hexamethylene isophthalamide‐co‐terephthalamide) (PA6I‐6T) was used as an efficient strategy to prepare amorphous homogeneous systems with improved properties mainly for packaging applications. The preparation of block copolymers was first of all tried by co‐extrusion of the two polymers and then by thermal treatments at high temperatures in DSC or mixing in Brabender, also in the presence of a catalyst. The occurrence of transamidation reactions led to macromolecular structures with different randomness degrees. Further, random copolymers, with the full range of compositions, were synthetized from monomers, by a fast and simple two‐stage melt polycondensation. For all the copolymers, the sequence distribution was studied by using a ¹H NMR method developed by the Authors. The effects of preparation procedures, of mixing temperature and time, of the presence of a catalyst on the chemical structure, and, then, on final properties were studied. Interesting correlations among block length, monomer distribution and phase behavior were discussed. POLYM. ENG. SCI., SCI., 55:1475–1484, 2015. © 2014 Society of Plastics Engineers     

Quality Attributes of Muffins: Effect of Baking Operative Conditions

Muffins are sweet baked products highly appreciated by consumers because of their soft texture and characteristic taste. The aim of this work was to study the influence of baking conditions on muffins’ quality. Surface crust color was monitored during baking tests at oven temperatures ranging from 140 to 220 °C, and browning kinetics was modeled by means of a browning index, BI, which follows a logistic model; a joint analysis of core temperature profile and BI curve can assist in the prediction of baking time. Finally, weight loss, crust/crumb ratio, crumb and crust moisture content, porosity, crumb and global densities, and texture were measured in the already baked muffin. The water content in the crumb remains almost constant, while considerable dehydration occurs in the crust. Finally, the results showed that intermediate oven temperatures led to a more porous, aerated, and soft crumb, with intermediate textural properties.     

Effect of ascorbic acid addition to peppers on paprika quality

The use of ascorbic acid addition to foods to protect pigments from oxidation has been widely applied. Control or ascorbic acid-added paprika peppers were processed in a similar way as for paprika manufacture. During the process, lipoxygenase activity, total colour, red/yellow pigment ratio and ascorbic acid levels were measured. In general, an increase of total colour and red pigments was observed in ascorbic acid-treated samples. The lipoxygenase activity was depressed in ascorbic acid-treated fruits on the first day of processing. However, the activity was increased again, at second day, when the ascorbic acid was oxidised, showing a close relationship between enzyme activity and the antioxidant. After the process, ascorbic acid was also added to half of the paprika from control peppers and its quality and stability of the pigments against light or heat was compared to the paprika from ascorbic acid-added peppers. At the end of the treatment a better quality was observed in paprika obtained from the ascorbic acid-added peppers. ©1997 SCI     

Identification of an integrated mathematical model of standard oral glucose tolerance test for characterization of insulin potentiation in health

Two new formulations, respectively denominated INT_M1 and INT_M2, of an integrated mathematical model to describe the glycemic and insulinemic responses to a 75 g oral glucose tolerance test (OGTT) are proposed and compared. The INT_M1 assumes a single compartment for the intestine and the derivative of a power exponential function for the gastric emptying rate, while, in the INT_M2, a nonlinear three-compartment system model is adopted to produce a more realistic, multiphase gastric emptying rate. Both models were implemented in a Matlab-based, two-step procedure for estimation of seven adjustable coefficients characterizing the gastric emptying rate and the incretin, insulin and glucose kinetics. Model behaviour was tested vs. mean plasma glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), glucose and insulin measurements from two different laboratories, where glycemic profiles observed during a 75 g OGTT were matched in healthy subjects (HC1- and HC2-group, respectively) by means of an isoglycemic intravenous glucose (I-IVG) infusion. Under the hypothesis of an additive effect of GLP-1 and GIP on insulin potentiation, our results demonstrated a substantial equivalence of the two models in matching the data. Model parameter estimates showed to be suitable markers of differences observed in the OGTT and matched I-IVG responses from the HC1-group compared to the HC2-group. Model implementation in our two-step parameter estimation procedure enhances the possibility of a prospective application for individualization of the incretin effect in a single subject, when his/her data are plugged in.     

Antibacterial coatings on poly(fluoroethylenepropylene) films via grafting of 3-hexadecyl-1-vinylimidazolium bromide

Surface coatings of pretreated poly(fluoroethylene propylene) (FEP) films by UV-induced graft copolymerization with 2-hydroxyethyl methacrylate (HEMA) and an antimicrobial agent, 3-hexadecyl-1-vinylimidazolium bromide (VIB), have been carried out. Surface chemical and morphological modifications were investigated with spectroscopic analysis using attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), scanning electron microscopy (SEM) and X-ray diffraction distribution map of bromide atoms. Fluorescein dye absorption studies were performed in order to quantify the amount of reacted VIB. Antibacterial activities were assayed with Staphylococcus aureus (S. aureus, a Gram positive bacterium) culture on HEMA-VIB modified FEP specimens, prepared with different amounts of the antimicrobial agent. In addition to bactericidal properties, the functionalized FEP surface also prevented the adhesion of microorganisms to the film.     

Self-triggering reaction kinetics between nitrates and aluminium powder

During the night between the 19 and 20 September 2003, a loud explosion occurred at about 3km from the town of Carignano that was clearly heard at a distance of some tens of kilometres. The explosion almost completely destroyed most of the laboratories of the Panzera Company that were used for the production of fireworks. The results of the research activities that were carried out using a differential scanning calorimeter (DSC) on the same raw materials that made up the pyrotechnical mixture that exploded are reported in this paper. This activity was carried out to identify the dynamics of the accident. It proved possible to verify how the event was produced because of a slow exothermic reaction which, after about 8h, caused the self-triggering of 120 kg of finished product. The detonation can therefore be put down to a runaway reaction in the solid phase, whose primogenial causes can be attributed to a still craftsman type production system, not conformed to the rigorous controls and inspections as those required by a safety management system for major risk plants, as the Panzera Company was.     

Metal distribution and metallothionein in loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles

The first aim of our study was to determine the concentrations of selected trace elements (Zn, Cu, Fe, Mn, Cd and Pb) in tissues of green turtles from Tortuguero National Park on the North Caribbean coast of Costa Rica and of loggerheads from the Mediterranean Sea. Zn, Cu, Fe, Mn and Cd were present at detectable concentrations in all samples and showed clear organotropism, whereas Pb was not always over the detection limit and did not show any particular tissue distribution. The two species presented significant differences: Cu and Cd in liver and kidney of Chelonia mydas were significantly higher with respect to the concentrations found in Caretta caretta. The second and major goal of our study was to evaluate hepatic and renal metallothionein (MT) as a biomarker of environmental metal exposure. The present paper is the first to describe and quantify MT in kidney and liver of loggerhead turtles and in kidney of green turtles. MT concentrations were higher in green than in loggerhead turtles. In addition, positive correlations were found between Cu and Cd concentrations and Cu-MT and Cd-MT in liver and kidney in both species, suggesting a pivotal role of MT in metal storage and detoxification. The quantification of metals and MT in liver and kidney may be a valid biomarker of metal exposure in the aquatic environment to assess the health of marine sea turtles as long as accurate analytical methods are adopted.     

N-doping modification by plasma treatment in polyacrylonitrile derived carbon-based nanofibers for Oxygen Reduction Reaction

This work aims at providing a simple and effective method to optimize and improve the nitrogen-based defects into intrinsically N-doped carbon-based electrospun nanofibers (CNFs) for achieving highly active catalysts for the oxygen reduction reaction (ORR). To reach this goal, plasma treatments are investigated as an effective method to tune the distribution of the N-doping sites that are vital to improve the ORR catalytic activity of the material. Morphological, physical, chemical as well as electrochemical characterizations were performed on plasma-treated CNFs to demonstrate the effectiveness of such treatments to improve the catalytic behavior of CNFs toward ORR. Finally, Microbial Fuel Cells (MFCs) were selected to test the plasma-treated nanofibers as the cathode catalyst layer demonstrating an increase of the overall performance of the MFCs with respect to the devices using the Pt-based reference catalyst.     

Biomimetic Tendrils by Four Dimensional Printing Bimorph Springs with Torsion and Contraction Properties Based on Bio-Compatible Graphene/Silk Fibroin and Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)

Taking inspiration from plant tendril geometry, in this study, 4D bimorph coiled structures with an internal core of graphene nanoplatelets-modified regenerated silk and an external shell of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) are fabricated by 4D printing. Finite element simulations and experimental tests demonstrate that integrating these biomaterials with different coefficients of thermal expansion results in the temperature induced self-compression and torsion of the structure. The bimorph spring also exhibits reversible contractive actuation after exposure to water environment that paves its exploitation in regenerative medicine, since core materials also have been proven to be biocompatible. Finally, the authors validate their findings with experimental measurements using such springs for temperature-mediated lengthening of an artificial intestine.