Synthesis and characterization of elastomeric,biobased, nonisocyanate polyurethane from natural rubber

Linear and crosslinked polyhydroxyurethanes (PHUs) based on natural rubber (NR) were synthesized by a polyaddition reaction without a solvent or catalyst to exploit the reactivity of diamines or triamines with dicyclic carbonate groups. Oligo‐isoprenes were obtained from the controlled oxidative degradation of NR and successive modifications of the chain ends. The syntheses of linear PHU were carried out with two approaches. The first one consisted of a reaction between amino telechelic oligo‐isoprenes and aromatic or aliphatic dicyclic carbonates. The second approach proceeded through a reaction between oligo‐isoprenes bearing cyclic carbonate chain ends and difunctional or trifunctional amines. The evolution of these reactions was studied by Fourier transform infrared spectrometry. The influence of the carbonate‐to‐amine molar ratio, the chain length of the oligo‐isoprenes, and the reaction temperatures were investigated. The thermal properties of the PHUs were studied by differential scanning calorimetry and thermogravimetric analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45427.     

SimSelect: Similarity‐based selection for 3D surfaces

Surface selection is one of the fundamental interactions in shape modeling. In the case of complex models, this task is often tedious for at least two reasons: firstly the local geometry of a given region may be hard to manually select and needs great accuracy; secondly the selection process may have to be repeated a large number of times for similar regions requiring similar subsequent editing. We propose SimSelect, a new system for interactive selection on 3D surfaces addressing these two issues. We cope with the accuracy issue by classifying selections in different types, namely components, parts and patches for which we independently optimize the selection process. Second, we address the repetitiveness issue by introducing an expansion process based on shape recognition which automatically retrieves potential selections similar to the user‐defined one. As a result, our system provides the user with a compact set of simple interaction primitives providing a smooth select‐and‐edit workflow.     

Lattice dynamics of thermoelectric La4Sb3

Lattice dynamics ab-initio calculations of the new thermoelectric compound La₄Sb₃ with anti- Th₄P₃ are reported. Hybridization of the lower optic mode with the acoustic modes is observed between 5.9 and 7.2 meV. As similar observations were done in other thermoelectric compounds such as skutterudites, it is suggested that this is an important effect in order to achieve low lattice thermal conductivity not only for the compounds La₄Sb₃ and La₃Te₄ with Th₄P₃ structure but also for other thermoelectric compounds, whose structures are not formed by cages.     

Compact Saloplastic Poly(Acrylic Acid)/Poly(Allylamine) Complexes: Kinetic Control Over Composition,Microstructure, and Mechanical Properties

Durable compact polyelectrolyte complexes (CoPECs) with controlled porosity and mechanical properties are prepared by ultracentrifugation. Because the starting materials, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid sodium salt) (PAA), are weak acids/bases, both composition and morphology are controlled by solution pH. In addition, the nonequilibrium nature of polyelectrolyte complexation can be exploited to provide a range of compositions and porosities under the influence of polyelectrolyte addition order and speed, and concentration. Confocal microscopy shows these “saloplastic” materials to be highly porous, where pore formation is attributed to a combination of deswelling of the polyelectrolyte matrix and expansion of small inhomogenities by osmotic pressure. The porosity (15–70%) and the pore size (<5 μm to >70 μm) of these materials can be tuned by adjusting the PAA to PAH ratio, the salt concentration, and the pH. The modulus of these CoPECs depends on the ratio of the two polyelectrolytes, with stoichiometric complexes being the stiffest due to optimized charge pairing, which correlates with maximized crosslinking density. Mechanical properties, pore sizes, and pore density of these materials make them well suited to three dimensional supports for tissue engineering applications.     

A study of depth/texture bit-rate allocation in multi-view video plus depth compression

Multi-view video plus depth (MVD) data offer a reliable representation of three-dimensional (3D) scenes for 3D video applications. This is a huge amount of data whose compression is an important challenge for researchers at the current time. Consisting of texture and depth video sequences, the question of the relationship between these two types of data regarding bit-rate allocation often raises. This paper questions the required ratio between texture and depth when encoding MVD data. In particular, the paper investigates the elements impacting on the best bit-rate ratio between depth and color: total bit-rate budget, input data features, encoding strategy, and assessed view.     

Stability of rare earth oxides in a moist environment at high temperatures—Experimental and thermodynamic studies. Part I: The way to assess thermodynamic parameters from volatilisation rates

A methodology based on a weight loss measurement was used to quantify the volatility of yttria in high temperature water vapor. This method was first assessed on silica. Sintered materials with a shape of pellets were exposed at temperatures between 1000 and 1400 °C in air with 50 kPa of water at atmospheric pressure, under a flowing gas velocity of 5 cm s^?1. Besides the volatilisation rate, the nature of the volatile gaseous species was determined using a kinetic study. Knowing the nature of flows in the furnace, partial pressures of yttrium (oxy-)hydroxide in equilibrium over Y₂O₃ were calculated, and used to assess the enthalpies of formation of YO(OH) and Y(OH)₃.     

Bimodal Detection of Proteins by 129Xe NMR and Fluorescence Spectroscopy

A full understanding of biological phenomena involves sensitive and noninvasive detection. Herein, we report the optimization of a probe for intracellular proteins that combines the advantages of fluorescence and hyperpolarized ¹²⁹Xe NMR spectroscopy detection. The fluorescence detection part is composed of six residues containing a tetracysteine tag (−CCXXCC−) genetically incorporated into the protein of interest and of a small organic molecule, CrAsH. CrAsH becomes fluorescent if it binds to the tetracysteine tag. The part of the biosensor that enables detection by means of ¹²⁹Xe NMR spectroscopy, which is linked to the CrAsH moiety by a spacer, is based on a cryptophane core that is fully suited to reversibly host xenon. Three different peptides, containing the tetracysteine tag and four organic biosensors of different stereochemistry, are benchmarked to propose the best couple that is fully suited for the in vitro detection of proteins.     

Evolution of EPDM networks aged by gamma irradiation - Consequences on the mechanical properties

Different Ethylene-Propylene Diene Monomer (EPDM) elastomers with different crosslink densities have been processed in order to evaluate the influence of gamma irradiation on their properties. In the case of a major phenomenon of chain scissions, the consequences are a decrease in the modulus and also a decrease in the strain at break. This decrease in the strain at break is opposite to what is expected for materials with increasing average chain length between crosslinks. To gain more insight into the network architecture, which is presumed to be responsible for this behavior, Charlesby's approach is applied. In tandem, a computational model of the degradation is developed for improved prediction of the evolution of the elastic modulus. Using these calculations, a novel interpretation of the ultimate properties of the elastomer as a function of its architecture is proposed.     

Preliminary examination of tobacco withdrawal in adolescent smokers during smoking cessation treatment

Tobacco withdrawal symptoms have been shown to play a significant role in mediating relapse to smoking in adult smokers; however, few prospective studies have examined the course of tobacco withdrawal symptoms over time and their connection to lapse in adolescent smokers. Withdrawal symptoms were assessed weekly for 4 weeks in a sample of adolescent smokers participating in a pilot cessation intervention. Adolescent smokers experienced an exacerbation in overall withdrawal symptoms, particularly of cravings and restlessness, although symptoms were generally mild. The course of symptoms was different for boys and girls: Girls generally experienced a peak and subsequent decline in symptoms early in the establishment of abstinence, whereas boys experienced a constant level of symptoms that did not decline over the 4 weeks. Finally, withdrawal symptoms experienced on quit day were not related to lapse to smoking during the course of treatment for either boys or girls. These results suggest that although withdrawal symptoms may be uncomfortable, they may not be the most salient to a lapse to smoking for adolescent smokers attempting to quit. These findings have direct implications for the design and implementation of treatment of nicotine dependence in adolescent smokers.