Evaluation of monomers derived from resorcinol as eluents of bisphenol A glycidyl dimethacrylate for the formulation of dental composite resins

The objective of this work was to synthesize two bio-based monomers, using the resorcinol as raw material, and its effect as bisphenol A glycidyl dimethacrylate (Bis-GMA) eluents on different chemical–physical and biological properties of experimental photopolymerizable composite resins. The acrylic 1,3-phenylen diacrylic (1,3-FDA) and methacrylic 1,3-phenylen dimethacrylic (1,3-FDMA) monomers were synthesized and fully characterized through FTIR and ¹H-NMR spectroscopies. Experimental photopolimerizable composites were formulated using Bis-GMA/1,3-FDA or Bis-GMA/1,3-FDMA as organic matrix. The materials were compared with a Bis-GMA/TEGDMA resin-based composite used as control. Polymerization kinetics was evaluated by means of FTIR spectroscopy. Polymerization stress was directly measured through a polymerization stress tester. The cell viability of the composites was evaluated using the MTT assay. One-way analysis of variance and Tukey's test were used for statistical analysis. The materials formulated with the 1,3-FDA monomer showed higher Rp_max values and lower polymerization stress values (p < 0.05), while the flexural strength, water sorption, and solubility remained similar to the TEGDMA composite. Conversely, the materials formulated with the 1,3-FDMA monomer showed a lower degree of conversion and statistically lower flexural strength (p < 0.05). All materials exhibited a cellular viability close to 100%. Concerning the study conditions, the acrylic 1,3-FDA monomer could be considered an alternative to TEGDMA in the formulation of photopolymerizable dental composite resins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48576.     

Properties of Poly(3‐hydroxybutyric acid) Composites with Flax Fibres Modified by Plasticiser Absorption

Natural fibre‐biopolymer composites have been prepared from flax and polyhydroxybutyrate (PHB). The flax was modified by drying, followed by plasticiser absorption to replace the water lost to prevent embrittlement. This protects the fibres from problems associated with their water content and changes in water content due to equilibration with the environment. Flax and PHB showed good interfacial adhesion, which was decreased when plasticisers were present. Some plasticiser migrated from the flax to PHB and caused complex changes in the glass transition, crystallisation and crystallinity of the PHB. Morphology of the composites was examined by scanning electron microscopy (SEM) and optical microscopy (OM), SEM provided information on the interfacial adhesion through fractography. OM showed extensive transcrystallinity along the fibre surfaces. Dynamic mechanical analysis was used to measure elastic and damping characteristics and their relation to composition and morphology.

SEM micrograph of the PHB‐plasticiser‐flax system PHB‐PEG‐flax.     

Comparing transmission potential networks based on social network surveys,close contacts and environmental overlap in rural Madagascar

Social and spatial network analysis is an important approach for investigating infectious disease transmission, especially for pathogens transmitted directly between individuals or via environmental reservoirs. Given the diversity of ways to construct networks, however, it remains unclear how well networks constructed from different data types effectively capture transmission potential. We used empirical networks from a population in rural Madagascar to compare social network survey and spatial data-based networks of the same individuals. Close contact and environmental pathogen transmission pathways were modelled with the spatial data. We found that naming social partners during the surveys predicted higher close-contact rates and the proportion of environmental overlap on the spatial data-based networks. The spatial networks captured many strong and weak connections that were missed using social network surveys alone. Across networks, we found weak correlations among centrality measures (a proxy for superspreading potential). We conclude that social network surveys provide important scaffolding for understanding disease transmission pathways but miss contact-specific heterogeneities revealed by spatial data. Our analyses also highlight that the superspreading potential of individuals may vary across transmission modes. We provide detailed methods to construct networks for close-contact transmission pathogens when not all individuals simultaneously wear GPS trackers.     

Antioxidant and chelating activity of Jatropha curcas L. protein hydrolysates

BACKGROUND: Antioxidant and chelating activities were determined in protein hydrolysates that were produced by treating a protein isolate of a non‐toxic genotype of Jatropha curcas with the protease preparation alcalase. RESULTS: 50 min protein hydrolysate with a degree of hydrolysis of 31.7% showed highest antioxidant and chelating activity. These activities were also determined in six peptidic fractions that were separated by gel filtration chromatography of the 50 min hydrolysate. The lower‐molecular‐weight peptidic fractions had the highest antioxidant and chelating activities, which correlated with a higher content in antioxidant and chelating amino acids such as tyrosine and histidine. CONCLUSION: Results show that J. curcas represents a good source of bioactive peptides. This may be important for the revalorization of defatted J. curcas flour, a by‐product resulting form oil extraction for biodiesel production. This is especially important in Third World and developing countries such as Mexico. Copyright © 2011 Society of Chemical Industry     

Left hemispheric specialization for learned, skilled, and purposeful action.

Three-dimensional motion analyses were performed on trajectories of repetitive "slicing" gestures by 4 participants with left-hemisphere lesions and limb apraxia, 6 participants with right-hemisphere lesions, and 7 neurologically intact participants. Left hemispheric lesioned participants with apraxia, but not right hemispheric lesioned participants showed impaired coupling of spatial and temporal aspects of wrist trajectories and deficits in interjoint coordination. Both groups of brain-lesioned participants differed from control participants in the 3-D plane of the wrist motion. The deficits of some right hemispheric lesioned participants in controlling the plane of wrist motion may be a consequence of left hemispatial neglect with rightward deviations. In contrast, the deficits of apraxic participants in controlling wrist trajectories and coordinating joint motions seem to reflect a deficit in these participants for the movement plan. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between depression and marital maladjustment in a clinic population: A multitrait-multimethod study.

Took depression and marital maladjustment measures of all 154 couples attending a clinic. Average age for men was 38 yrs, for women 35 yrs; average length of marriage was 19 yrs. A significant correlation between depression and marital maladjustment was found for self-report data and was replicated by therapists' ratings. Women were significantly more depressed than men though similar in average ratings of marital adjustment. Women's depression ratings were minimally related to their own their husbands' marital ratings. Men's depression ratings were related to both their own and their wives' marital ratings. Convergent validity was demonstrated for the Locke and Wallace Marital-Adjustment Test and the Beck Depression Inventory. Clinical implications of findings concerning both depression and marital maladjustment are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Towards adaptive structured Dirichlet smoothing model for digital resource objects

Multimedia Tools and Applications - Digital resource objects (DRO) are among the most valuable resources that store the accumulated knowledge of humankind. Nowadays, many organisations aim to make...     

Impact damage characterisation of composite laminates using a statistical approach

Detecting impact damage is an important factor in maintaining the structural integrity of aerospace composite structures. Since impacts can cause severe reductions in stiffness and strength of composite structures, there is a need to investigate the material’s stiffness and strength after an impact event. The work discussed in this paper is concerned with one overall goal, which is to determine if an impact has caused damage and then to determine the extent of that damage using only the structural responses that are acquired from low-profile surface-mounted transducers. The work presented in this paper demonstrates that responses recorded from these sensors can provide sufficient information to infer impact damage. Previous work by various authors has established that it is possible to distinguish between damaging and non-damaging impacts if the impact force time-history is available. Therefore, it is the requirement that only response data be used here that distinguishes this work from the previous studies. Following a systematic series of experiments, on the induction of impact damage in Carbon Fibre Reinforced Polymer (CFRP) laminates, a damage model was proposed from this work which can provide preliminary information on the type and extent of damages through observations made from Scanning Electron Microscopy (SEM) and X-ray radiography. The model can be used to provide a general understanding on the prediction of damage and failure progression in CFRP as a function of the number of layers and impact energies. To accommodate the results from SEM and X-ray, discussions on outlier analysis and visualisation, which emphasise the idea of discordancy from the discipline of statistics, are presented. Results from discordancy tests, for both univariate and multivariate data, can be used to clearly separate the data (non-damaging and damaging impacts as well as the separation of the type of failure modes) by a calculated threshold value. Both of these features (univariate and multivariate) can be used as damage indicators and proxies for determining the extent of damage.     

Mild protein oxidation enhanced hydration and myofibril swelling capacity of fresh ground pork muscle packaged in high oxygen atmosphere

Abstract: This study investigated the influence of an oxygen‐enriched modified atmosphere packaging (HiOx: 80% O₂/20% CO₂) in comparison with air‐permeable polyvinylchloride (PVC) wrapping and partial vacuum (VP: 60%) packaging on the ability of myofibrils to imbibe water during retail display of fresh ground pork at 2 to 4 °C. Both HiOx and PVC muscles after 4 d showed maximum myofibril swelling and A‐band dissolution when isolated myofibrils were subjected to a graded series of salt solutions (0.2→0.4 M NaCl with 10‐mM sodium pyrophosphate, pH 6.2), while VP samples exhibited no remarkable change. Protein carbonyl content increased substantially from day 0 to 4 in all muscle samples. For HiOx, muscle hydration capacity increased linearly (P < 0.05) during storage up to 14 d, corresponding to protein carbonyl production. No significant changes in hydration properties were noted in VP muscle samples, which also maintained lower levels of protein oxidation, during storage up to 21 d. These results indicated that packaging in modified atmosphere with high levels of oxygen could result in increased protein oxidation but enhanced hydration capacity of fresh meat. Practical Application: Packaging of fresh meat, including ground pork, under an oxygen‐enriched atmosphere condition is widely used in the industry to preserve red color of meat. Results from the present study indicate that high oxygen packaging has a discordant effect on fresh ground pork: it enhances hydration but decreases water‐binding, and this seems to be caused by increased swelling of muscle fibers due to mild protein oxidation. Hence, it is advisable to employ a water‐binding agent in this type of packaging system so as to retain the moisture in stored fresh pork products while maintaining the color stability.