Relation of glass transition temperature to the hydrogen bonding degree and energy in poly(N-vinyl pyrrolidone) blends with hydroxyl-containing plasticizers: 3. Analysis of two glass transition temperatures featured for PVP solutions in liquid poly(ethylene glycol)

The phase behaviour of poly(N-vinyl pyrrolidone)-poly(ethylene glycol) (PVP-PEG) blends has been examined in the entire composition range using Temperature Modulated Differential Scanning Calorimetry (TM-DSC) and conventional DSC techniques. Despite the unlimited solubility of PVP in oligomers of ethylene glycol, the PVP-PEG system under consideration demonstrates two distinct and mutually consistent glass transition temperatures (T_g) within a certain concentration region. The dissolution of PVP in oligomeric PEG has been shown earlier (by FTIR spectroscopy) to be due to hydrogen bonding between carbonyl groups in PVP repeat units and complementary hydroxyl end-groups of PEG chains. Forming two H-bonds through both terminal OH-groups, PEG acts as a reversible crosslinker of PVP macromolecules. To characterise the hydrogen bonded complex formation between PVP (M_w=10⁶) and PEG (M_w=400) we employed an approach described in the first two papers of this series that is based on the modified Fox equation. We evaluated the fraction of crosslinked PVP units and PEG chains participating to the complex formation, the H-bonded network density, the equilibrium constant of complex formation, etc. Based on the established molecular details of self-organisation in PVP-PEG solutions, we propose a three-stage mechanism of PVP-PEG H-bonded complex formation/breakdown with increase of PEG content. The two observed T_gs are assigned to a coexisting PVP-PEG network (formed via multiple hydrogen bonding between a PEG and PVP) and a homogeneous PVP-PEG blend (involving a single hydrogen bond formation only). Based on the strong influence of coexisting regions on each other and the absence of signs of phase separation (evidenced by Optical Wedge Microinterferometry) we conclude that the PVP-PEG blend is fully miscible on a molecular scale.     

Ionic nanocomposite networks in poly(styrene‐co‐methacrylic acid) copolymers with calcium carbonate

To create reversible supramolecular ionic networks, ionic cross‐links were formed from acid pendant functions in poly(styrene‐co‐methacrylic acid) copolymers by the addition of calcium carbonate. The random dispersion of acid functions in the polystyrene chain is ensured by NMR analysis. The partial reaction of the calcium carbonate with the carboxylic acids is highlighted by a limewater test. The influence of methacrylic acid and calcium‐carbonate contents on the formation of an ionic network has been studied through solubility tests. Two main effects were obtained: the exfoliation of the unreacted calcium carbonate characterized by TEM is due to ionic interactions at the surface of nanometric particles that form the first level of organization of the calcium carbonate. Another part of the calcium carbonate reacts with carboxylic acid and is detached from particles to form clusters as shown by x‐ray analysis. Finally, by analyzing the dynamic rheological spectrum, the conclusion that the strength of the ionic bonds arises with the calcium content is made. The interest of such an approach with a wide range of observed phenomena in the material is a one‐batch process to make thermoreversible nanocomposite networks. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Current knowledge in species-related bioavailability of selenium in food

Selenium is an essential trace element that has raised interest because of its antioxidant and anticancer properties. The beneficial or toxic effect of Se is not only dose-dependent, but also relates to the chemical form of the element and its bioavailability. In this review, recently published data is summarised concerning both Se speciation and Se relative bioavailability in various foodstuffs. In addition, Se bioavailability is discussed in relation to the species-dependent metabolism in humans. In this way, the understanding of the potential health impact of Se species in commonly consumed food is aimed to be improved. It is strongly suggested on the basis of a higher retention and a lower toxicity, that organic Se (especially SeMet, the major species in food) is more recommendable than inorganic Se in the frame of a balanced diet. Further research is however desirable concerning the characterisation of unidentified Se species and determination of their health effects.     

A pattern analysis based underwater video segmentation system for target object detection

Multidimensional Systems and Signal Processing - Detecting and classifying the target objects in the underwater videos is the primary and essential operation in this modern era. The present works...     

Assessment of Bread Dough Expansion during Fermentation

The aim of this work was to investigate different methods of measuring the expansion of bread dough during fermentation and to develop a mathematical model to describe the variation of dough volume. Dough was prepared with wheat flour, salt, yeast, and selected amount of water (56%, 58%, and 60% w/w flour basis). Proving time was 1 h and proving temperature investigated were 25, 30, and 35°C. Dough volume was measured with three methods: (1) vertical expansion in a flask, (2) horizontal expansion between two plates, and (3) free expansion method. Volume was measured either using displacement transducer or from image analysis of pictures taken during expansion. All the methods allowed monitoring the increase in dough volume as a function of proving time. Small differences were observed between the three methods. Free expansion shows a faster start of expansion in comparison with the two other methods. Expansion curves have been fitted with a modified Gompertz model (Romano et al., J Food Eng 83:142–148, 2007). They exhibited three phases: a lag phase, followed by a linear phase (constant expansion rate), and finally a phase with a decreasing expansion rate. Statistical analysis of the set of data showed that the proving temperature had a significant effect on the different parameters calculated (volume expansion ratio, expansion rate), while the water content had no significant effect.     

Spark plasma sintering and mechanical properties of compounds in TiB2-SiC pseudo-diagram

The influence of spark plasma sintering (SPS) parameters (temperature, time, pressure) and the role of particle size on densification, microstructure and mechanical properties of commercial additive-free TiB₂, SiC and composites thereof were studied by X-ray diffraction, scanning electron microscopy, the ultrasonic method and indentation. Three particle sizes of SiC and 2 of TiB₂ were processed. An optimal cycle was found for TiB₂ and SiC: 2000?°C, 3?min dwell time, and 100?MPa applied at 600?°C. The relative density of pure SiC increases linearly from 70% to 90% when the initial particle size decreases from 1.75?µm to 0.5?µm. Pure TiB₂ was densified up to 87%. Using 2.5?wt% SiC in TiB₂, the relative density increases to 97%. Young's modulus and the hardness of all samples were measured, with results discussed. The higher properties were obtained for additive-free TiB₂–5%SiC with a relative density of 97% and with the Young's modulus and Vickers hardness values being close to 378?GPa and 23?GPa, respectively.     

Genetic Variants of GPER/GPR30, a Novel Estrogen-Related G Protein Receptor,Are Associated with Human Seminoma

Testicular germ cell tumors (TGCTs) are the most common solid cancers in young men, with an increasing incidence over several years. However, their pathogenesis remains a matter of debate. Some epidemiological data suggest the involvement of both environmental and genetic factors. We reported two distinct effects of estrogens and/or xeno-estrogens on in vitro human seminoma-derived cells proliferation: (1) an antiproliferative effect via a classical estrogen receptor beta-dependent pathway, and (2) a promotive effect via a non-classical membrane G-protein-coupled receptor, GPR30/GPER, which is only overexpressed in seminomas, the most common TGCT. In order to explain this overexpression, we investigated the possible association of polymorphisms in the GPER gene by using allele-specific tetra-primer polymerase chain reaction performed on tissue samples from 150 paraffin-embedded TGCT specimens (131 seminomas, 19 non seminomas). Compared to control population, loss of homozygous ancestral genotype GG in two polymorphisms located in the promoter region of GPER (rs3808350 and rs3808351) was more frequent in seminomas but not in non-seminomas (respectively, OR = 1.960 (1.172–3.277) and 7.000 (2.747–17.840); p < 0.01). These polymorphisms may explain GPER overexpression and represent a genetic factor of susceptibility supporting the contribution of environmental GPER ligands in testicular carcinogenesis.     

Freezing-thawing effects on the colour and texture of European catfish flesh

The freezing-thawing effect on the colour of raw fillets and on the texture of cooked fillets of European catfish ( Silurus glanis ) was studied. European catfish coming from two rearing conditions occurring in France were analysed by sensory and instrumental measurements. Fillets of European catfish became lighter, yellower and less bright after a freezing-thawing cycle. An increase in hardness and a decrease in resilience, disintegration and shear resistance were also highlighted after a freezing-thawing cycle. We could make the hypothesis that these variations of colour and texture were due either to mechanical damage or muscle protein denaturation. Fillets also became less juicy after a freezing-thawing cycle because of a loss of water-holding capacity.     

Eye tracking as a debriefing tool in upset prevention and recovery training (UPRT) for general aviation pilots

Abstract

Upset prevention and recovery training (UPRT) is intended to improve the ability of pilots to recognize and avoid situations that can lead to airplane upsets and to improve their ability to recover control of an airplane that has exceeded the normal flight envelope. To this end, a set of different training contents – from theoretical knowledge of aerodynamics and human factors to practice-based flight training – is necessary. In order to support the debriefing with an objective feedback, and because visual scanning is a core competence, two studies on subjective evaluation of aviation pilots – one conducted in a flight simulator and the other one in-flight – focussed on the practical application of eye tracking as a debriefing tool in UPRT. From a practitioner’s perspective, eye tracking appeared to be a useful method in terms of visualising instrument scanning techniques, supporting the instructor with objective debriefing material and fostering self-awareness in human processes. The discussion recommends adjusted UPRT instructor training and further improvements to eye tracking hardware and software.

Practitioner Summary: The article focuses on pilot evaluations of eye tracking as a debriefing tool in UPRT and the identification of critical elements in its use. Eye tracking is a promising debriefing tool for UPRT. The discussion points to desirable improvements of eye tracking hardware and software as well as adjustments to instructor training that are pertinent.