NCube/papyrus huggingface dataset:
Smart packaging in the sustainability challenge : eumelanin as a UV-absorption enhancer of polymers

The black-brown biopigment eumelanin screens the harmful ultraviolet (UV) radiation in the human skin. In industry, the absorption of plastics in the UV range is improved by the inclusion of additives. Our work reports an evaluation of the biopigment eumelanin as a nature-inspired additive for polymers to improve their UV-absorption. Eumelanin, being non-toxic and produced by natural sources, represents an interesting candidate for sustainable plastic additives. We fabricated eumelanin-including films of commercial linear low-density polyethylene (LLDPE), a plastic ubiquitous in packaging applications. The films were obtained by melt-compounding and compression molding. The melanin free acid treatment (MFA) was used to enhance the biopigment dispersion in the films. We observed that amounts of eumelanin as low as 0.8% wt. bring about an increase of the UV absorption up to one order of magnitude in the UVA range. We also assessed the effect of eumelanin on the film stability under prolonged UV irradiation: the biopigment proved to work both as UV-absorption enhancer but also as a photo-prooxidant, as inferred by thermogravimetric analysis (TGA) and infrared (IR) spectroscopy.

Keyphrases: Melanin, Melanin free acid, Linear low-density polyethylene, Packaging, UV-absorbers, UV-aging
Photocontrol of supramolecular azo-containing block
copolymer thin films during dip-coating : toward
nanoscale patterned coatings

Dip-coating allows nanostructured block copolymer (BCP) thin film fabrication in a fast and facile one-step process. It can also be coupled with external controls, such as illumination. Herein, we expose several design principles that enable photocontrol of the nanostructured surface pattern and thickness of supramolecular BCP thin films. This is done using a polystyrene–poly(4-vinylpyridine) (PS-P4VP) BCP and two hydroxy-functionalized small-molecule (SM) azo derivatives that have different photochemical characteristics and that hydrogen bond to the P4VP block. We show how the film preparation concept provides tunability through the chemical structure of the photoactive SM, the relative amount of SM in the dip-coating solution, and the choice of solvent. It was found that the film thickness and SM uptake in the films are increased by illumination when THF is used but are unchanged when toluene is used as solvent, which is attributed to an optical heating effect observable with volatile solvents. The photocontrol of surface patterns is a result of photoinduced changes in the effective volume fraction of the P4VP+SM phase, which is increased by a greater volume of cis isomers, by higher SM uptake (using THF), and by more trans–cis–trans cycling for systems with shorter cis lifetime. The extent of photoinduced change can also be increased by higher molecular mobility due to more flexible SMs, lower BCP molecular weight, and nonmicellar or softer micellar solutions.

Keyphrases: Photocontrol, Block copolymer thin films, Supramolecular, Azo-containing, Dip-coating, Nanoscale patterns
Eumelanin for nature-inspired UV-absorption enhancement of plastics

In the human body, the black-brown biopigment eumelanin blocks the harmful ultraviolet (UV) radiation. In the plastics industry, additives are often added to polymers to increase their UV-absorption properties. We herein report an assessment of the biopigment eumelanin as a nature-inspired additive for plastics to enhance their UV-absorption. Since eumelanin is produced by natural sources and is non-toxic, it is an interesting candidate in the field of sustainable plastic additives. In this work, eumelanin-including films of commercial ethylene-vinyl acetate copolymer (EVA), a plastic used for packaging applications, were obtained by melt-compounding and compression molding. The biopigment dispersion in the films was improved by means of the Melanin Free Acid treatment (MFA). It was observed that eumelanin amounts as low as 0.8% wt. cause an increase of the UV absorption, up to one order of magnitude in the UVA range. We also evaluated the effect of eumelanin on the thermal and photostability of the films: the biopigment proved to be double-edged, working both as UV-absorption enhancer and photo-prooxidant, as thermogravimetric analysis (TGA) and infrared (IR) spectroscopy revealed.

Keyphrases: Eumelanin, Melanin free acid, Ethylene-vinyl acetate copolymer, Packaging, UVabsorbers, UV-aging
Covalently crosslinked mussel byssus protein-based materials with tunable properties

Mussels’ anchoring threads, named byssus, are collagen-rich fibers with outstanding mechanical properties. Our previous work has shown the possibility of producing a byssus protein hydrolyzate with good film-forming ability, providing a promising new avenue for the preparation of biomaterials. Materials prepared from regenerated fibrous proteins often need additional treatments to reach the performance required for targeted applications. Here, we studied the effect of covalent crosslinking, using a carbodiimide or glutaraldehyde, on the mechanical properties and enzymatic resistance of byssus-based materials. The results show that the mechanical properties of the films can be tuned, and that a higher crosslinking degree leads to increases in modulus and strength accompanied by a loss of extensibility. Structural analysis performed by infrared spectroscopy revealed that crosslinking induces an unexpected transition from aggregated strands to hydrated collagen/PPII-related helical structures. The materials were nevertheless more resistant to collagenase degradation as a result of higher crosslinking density. This new set of materials prepared in aqueous environment could find a niche in tissue engineering.

Keyphrases: Peptide-based material, Mechanical properties, Protein crosslinking, Infrared spectroscopy, Biopolymer
Selective isotopic labeling resolves the gel-to-fluid phase transitions of the individual leaflets of a planar-supported phospholipid bilayer

Knowledge of the thermotropic phase behavior of solid-supported bilayer lipid assemblies is essential to mimick the molecular organization and lateral fluidity of cell membranes. The gel-to-fluid phase transitions in a homologous series of single phospholipid bilayers supported on planar silicon substrates were investigated by temperature-controlled atomic force microscopy and attenuated total reflection infrared spectroscopy to obtain complementary information at the mesoscopic and molecular scales. Symmetric bilayers of dipalmitoylphosphatidylcholine (DPPC) and vertically asymmetric bilayers composed of a leaflet of DPPC and another of acyl-chain-deuterated DPPC (DPPC-d62) were prepared by the Langmuir–Blodgett technique. The selective deuteration of one of the bilayer leaflets enabled the simultaneous monitoring by IR spectroscopy of the acyl chain melting in each leaflet via the spectrally isolated CH2 and CD2 stretching vibrations. Two gel-to-fluid transitions were discerned for both the symmetric and asymmetric bilayers in ultrapure water. The deuterium isotope effect observed in free-standing membranes was maintained for the supported bilayers. IR spectroscopy revealed that the melting of one leaflet promotes the disordering of the acyl chains in the adjacent one. The findings suggest that the two leaflet phase transitions do not evolve in isolation. This work sheds insight into the nature of leaflet–leaflet interactions and the thermodynamic properties of surface-confined phospholipid bilayers.

Keyphrases: Vesicles, Melting, Lipids, Fluids, Phase transitions
Polarized raman analysis of polymer chain orientation in ultrafine individual nanofibers with variable low crystallinity

Recent mechanical studies of ultrafine electrospun polymer nanofibers showed they can simultaneously possess high strength and toughness attributed to high degree of chain alignment coupled with low crystallinity. Quantitative analysis of macromolecular alignment in nanofibers is needed for better understanding of processing/structure/properties relationships and optimization. However, quantification of structural features in nanofibers with ultrafine diameters and low variable crystallinity is highly challenging. Here, we show that application of standard orientation analysis protocols developed for polarized Raman microscopy of bulk polymers and films can lead to severe errors in subwavelength diameter samples. A modified polarized Raman method is proposed and implemented for study of size-dependent orientation in individual nanofibers as small as 140 nm. Macromolecular alignment improved significantly with the reduction of nanofiber diameter, correlating with nanofiber modulus increase. Applicability of the proposed method for quantitative comparative studies of nanofiber systems fabricated from solutions with different solvents is demonstrated.

Keyphrases: Nanofibers, Crystallinity, Polymer chains, Nitrogen compounds, Polarization
Long-term randomized clinical trial evaluating the effects of fixture surface acid-etching and machined collar design on bone healing

Objectives: An implant with an acid-etched fixture surface and internal-hex collar may achieve greater osseointegration. The goal of this research was to study the effects on long-term bone healing of fixture surface acid-etching and machined collar design.  Method and materials: Three two-part implant types were compared: standard Brånemark (with an external-hex 1.2 mm long machined flat collar), Swede-Vent (a copy of the Brånemark design, with an identical collar but a fixture surface acid-etched to 1 to 3 µm), and Screw-Vent (with a fixture surface acid-etched identically to that of Swede-Vent, but a longer internal-hex machined flat collar that did not require countersinking). Fifty-eight subjects each received the three types in alternate fashion at five sites between mental foramen, and a fixed full-arch prosthesis. Abutment-implant interface/microgap (MG) was placed at the crest, and first bone-to-implant contact point-to microgap (fBIC-MG) was measured at mesial and distal sides of each implant. Mean fBIC-MG values were compared after 15 to 20 years of function. Statistical analysis was based on the mixed linear model with the level of significance set at P < .05 and Bonferroni correction for pairwise comparisons.  Results: Brånemark had less mean marginal bone loss (-1.08 mm, standard error [SE] 0.20) compared with Swede-Vent (-1.28 mm, SE 0.20), but pairwise comparisons showed that the difference was not statistically significant (mean difference of 0.20 mm, P = .662). Screw-Vent had the greatest loss (-1.92 mm, SE 0.20), and pairwise comparisons showed that the difference was statistically significant compared with Brånemark and Swede-Vent (difference ≥ 0.64 mm, P < .001).  Conclusion: According to accepted standards for osseointegration, all three implant types achieved very acceptable long-term results. However, while Brånemark had the least bone loss, the implant with the acid-etched fixture surface and longer internal-hex collar design had the greatest loss. Within the confines of this study, shorter collar length of 1.2 mm may be more important to limit long-term bone loss with microgap placed at the crest.

Keyphrases: Acid-etched fixture, Machined collar design, Prospective study
Réflexions sur la représentation du handicap retrouvée dans le cinéma québécois

Réflexions sur la représentation du handicap retrouvée dans le cinéma québécois est un court-métrage documentaire s’articulant autour de deux questions principales : comment aborder la représentation du handicap telle qu’elle se retrouve dans certains films québécois ; et, dans quelle mesure l’étude critique de cette représentation permet-elle de concevoir le cinéma comme un régime de la représentation (Hall 1997a) québécois articulé autour de certaines normativités (Butler, 2004)? Pour y parvenir, la réalisatrice a entretenu une discussion avec des réalisateurs, réalisatrices, actrices et activistes au sujet de la lutte de pouvoir autour de la représentation (Hall, 1997a; du Gay et al., 1997); celle-ci s’inscrivant dans une lutte plus large concernant des rapports de force dans la société québécoise. Cette discussion prend pour étude de cas le film Prends-moi (2014), court-métrage de fiction réalisé par André Turpin et Anaïs BarbeauLavalettte, deux personnes non-handicapées. Le documentaire met de l’avant une analyse critique des représentations capacitiste, explorant l’autoreprésentation comme une réappropriation de l’espace culturel et social de la représentation des personnes handicapées dans le contexte québécois.

Keyphrases: Cinéma québécois, Représentation, Capacitisme, Handicap
Raman spectroscopy of individual poly(ethylene oxide) electrospun fibers : effect of the collector on molecular orientation

Electrospun fibers are complex polymeric materials with a typical diameter of a few hundred nanometers that are often frozen in out-of-equilibrium states due to the fast solvent evaporation and high elongational forces during the process. Their molecular orientation, and the parameters affecting it, is a critical (although challenging) parameter to characterize because it allows improving and tuning many properties. In this paper, we characterize molecular orientation of poly(ethylene oxide) (PEO) fibers produced with the three most common collectors by applying our recently developed Raman spectroscopy methodologies to probe individual fibers. Results reveal an extremely high orientation in all PEO fibers and, surprisingly, the absence of any effect of the collector on molecular orientation. This contrasts with reports by several other research groups in the context of studies on bundles of fibers, as well as with our WAXD results on the same fibers. It is concluded that studies on bundles composed of thousands of imperfectly aligned fibers lead to a systematic underestimation of the orientation and to apparent results that prevent us from drawing clear conclusions on the molecular impact of processing parameters when they generate different levels of macroscopic alignment. This work highlights how Raman spectroscopy helps to overcome one of the major challenges in the field, the characterization of individual fibers, to reach a better understanding and control of electrospun fibers properties.

Keyphrases: Confocal Raman spectroscopy, Molecular orientation, Fibers, Electrospinning
Photoactive/passive molecular glass blends : an efficient strategy to optimize azomaterials for surface relief grating inscription

: Irradiation of azomaterials causes various photophysical and photomechanical effects that can be exploited for the preparation of functional materials such as surface relief gratings (SRGs). Herein, we develop and apply an efficient strategy to optimize the SRG inscription process by decoupling, for the first time, the important effects of the azo content and glass transition temperature (Tg). We prepare blends of a photoactive molecular glass functionalized with the azo Dis‐ perse Red 1 (gDR1) with a series of analogous photopassive molecular glasses. Blends with 10 and 40 mol% of gDR1 are completely miscible, present very similar optical properties, and cover a wide range of Tg from below to well above ambient temperature. SRG inscription experiments show that the diffraction efficiency (DE), residual DE and initial inscription rate reach a maximum when Tg is 25 to 40 °C above ambient temperature for low to high azo content, respectively. Indeed, for a fixed 40 mol% azo content, choosing the optimal Tg enables doubling the SRG inscription rate and increasing DE sixfold. Moreover, a higher azo content enables higher DE for a similar Tg. Spectroscopy measurements indicate that the photo‐ orientation of DR1 and its thermal stability are maximal with Tg around 70 °C, independent of the azo content. We conclude that the SRG potential of azomaterials depends on their capability to photo‐orient but that the matrix rigidity eventually limits the inscription kinetics, leading to an optimal Tg that depends on the azo content. This study exposes clear material design guidelines to optimize the SRG inscription process and the photoactivity of azomaterials.

Keyphrases: Surface relief grating, Photoactive materials, Azobenzene, Molecular glasses, Glass transition temperature, Photoinduced orientation
In situ photocontrol of block copolymer morphology during dip-coating of thin films

We demonstrate a unique combination of simultaneous top-down and bottom-up control of the morphology of block copolymer films by application of in situ optical irradiation during dip-coating. A light-addressable and block-selective small molecule, 4-butyl-4′-hydroxyazobenzene (BHAB), is introduced into a diblock copolymer of polystyrene and poly(4-vinylpyridine) (PS-P4VP) of 28.4 wt % P4VP via supramolecular chemistry, notably by hydrogen bonding to P4VP. We show that the spherical morphology of thin films dip-coated from a THF solution at slow withdrawal rates in the dark convert to cylindrical morphology when dip-coated under illumination. This is attributed to volume expansion of the P4VP/BHAB phase due to trans–cis photoisomerization combined with a light-induced increase in BHAB uptake in the film. The demonstrated photocontrol highlights the potential of dip-coating as a scalable film preparation method that can be easily coupled with external stimuli to direct nanostructured self-assembly in the films as solvent evaporates.

Keyphrases: Thickness, Morphology, Thin films, Solvents, Irradiation
Influence of supramolecular interaction type on photoresponsive azopolymer complexes : a surface relief grating formation study

The influence of the supramolecular interaction type—hydrogen bonding, proton transfer, and pure ionic bonding—on photoresponsive behavior, particularly surface relief grating (SRG) inscription, has been investigated using a homopolymer with an ambient temperature glass transition (Tg). To this end, poly(dimethylaminoethyl methacrylate) (PDMAEMA or PDM) of relatively high molecular weight (42K) was complexed at various azo/DM molar ratios with dimethylaminoazobenzene derivatives functionalized by hydroxyl (azoOH) or carboxylic acid (p-methyl red or azoCOOH) groups, and quaternized PDM (PDMQ) was complexed at equimolar ratio with a sulfonated analogue (methyl orange or azoSO3), and the structural and thermal properties of these complexes were determined. SRG inscription on spin-coated films was found to be possible because complexation increases the Tg above ambient. The efficiency of SRG inscription on spin-coated films, which increases with azo content, is highest for the purely ionic azoSO3/PDMQ complex despite its very high Tg, while the proton transfer azoCOOH/PDM complexes, involving ionic and H-bonding with acid-salt structures, show somewhat more efficient SRG inscription than do the purely hydrogen-bonded azoOH/PDM complexes, and this despite some azoCOOH crystallization at the highest molar ratios. These findings clarify the comparative effectiveness of different supramolecular bond types on SRG inscription and provide a useful guide for the design of supramolecular photoresponsive polymers for SRG applications.

Keyphrases: Physical and chemical processes, Crystallization, Complexation, Materials, Polymers
Chronic stress, cognitive functioning and mental health

This review aims to discuss the evidence supporting the link between chronic stress, cognitive function and mental health. Over the years, the associations between these concepts have been investigated in different populations. This review summarizes the findings that have emerged from older populations as well as from populations suffering from pathological aging, namely Mild Cognitive Impairment and Alzheimer's Disease. Although older adults are an interesting population to study in terms of chronic stress, other stress-related diseases can occur throughout the lifespan. The second section covers some of these stress-related diseases that have recently received a great deal of attention, namely burnout, depression, and post-traumatic stress disorder. Given that chronic stress contributes to the development of certain pathologies by accelerating and/or exacerbating pre-existing vulnerabilities that vary from one individual to the other, the final section summarizes data obtained on potential variables contributing to the association between chronic stress and cognition.

Keyphrases: Chronic stress, HPA axis, Glucocorticoids, Cognition, Mental health
Glenohumeral joint and muscles functions during a lifting task

The mobility of the healthy shoulder depends on complex interactions between the muscles spanning its glenohumeral joint. These interactions ensure the stability of this joint. While previous studies emphasized the complexity of the glenohumeral stability, it is still not clear how the kinematics and muscles interact and adapt to ensure a healthy function of the glenohumeral joint. To understand the function of each muscle and degree of freedom of the glenohumeral joint in executing an above-the shoulder box handling task while ensuring stability, we adapted an index-based approach previously used to characterize the functions of the lower limb joints and muscles during locomotion. Forty participants lifted two loads (6 Vs. 12 kg) from hip to eye level. We computed the mechanical powers of the glenohumeral joint and its spanning muscles. We characterized the function of muscles and degrees of freedom using function indices. The function of the glenohumeral joint underlined its compliancy and design for a large range of motion, while the rotator cuff indices emphasized their stabilizing function. The overall muscle functions underlined the complexity of the glenohumeral stability that goes beyond the rotator cuff. Additionally, the load increase was compensated with changes in the functions that seem to favor joint stability. The implemented approach represents a synthetized tool that could quantify the glenohumeral joint and muscles behavior during tridimensional upper limb tasks, which might offer additional insight into motor control strategies and functional alterations related to pathologies or external parameters (e.g., load).

Keyphrases: Shoulder, Rotator cuff, Glenohumeral joint, Muscle function, Joint function
Matériel de formation Rel@x : formation à la communication hypnotique pour prévenir la douleur

La formation Rel@x a été mise au point pour prévenir et diminuer la douleur procédurale en pédiatrie. Elle utilise les principes de la communication adaptée de l'hypnose clinique (communication hypnotique) et concerne deux techniques: l'endroit agréable et le gant magique. Les documents joints sont les éléments utilisés dans la formation: Manuels de formation (relationnel et technique), Aide-mémoires remis aux participants, Affiches pour les postes de soin. The Rel@x training was developed to prevent and decrease procedural pain in pediatrics. It uses the principles of hypnosis-derived communication (hypnotic communication) and includes two techniques: the pleasant place and the magic glove. The attached documents are elements used during training: Training manuals (interpersonal and technical), Summary briefs given to participants, Posters to be displayed in wards.

Keyphrases: Communication hypnotique, Hypnose, Douleur, Douleur procédurale