Bromination is herein exploited to promote the emergence of elastic behavior in a short peptide-SDSYGAP-derived from resilin, a rubber-like protein exerting its role in the jumping and flight systems of insects. Elastic and resilient hydrogels are obtained, which also show self-healing behavior, thanks to the promoted non-covalent interactions that limit deformations and contribute to the structural recovery of the peptide-based hydrogel. In particular, halogen bonds may stabilize the β-sheet organization working as non-covalent cross-links between nearby peptide strands. Importantly, the unmodified peptide (i.e., wild type) does not show such properties. Thus, SDSY(3,5-Br)GAP is a novel minimalist peptide elastomer.

A novel water-in-oil (W/O) microemulsion based on natural oils, namely extra virgin olive oil (EVOO) and sunflower oil (SO), in the presence of non-ionic surfactants was successfully formulated. The novel microemulsion was used as a carrier for gallic acid (GA) to assure its protection and efficacy upon nasal administration. The work presents evidence that this microemulsion can be used as a nasal formulation for the delivery of polar antioxidants, especially, after incorporation of chitosan (CH) in its aqueous phase. The structure of the system was studied by Small Angle X-ray Scattering (SAXS), Dynamic Light Scattering (DLS) and Electron Paramagnetic Resonance (EPR) spectroscopy techniques. By the addition of CH, the diameter of the microemulsion remained unaltered at 47 nm whereas after the incorporation of GA, micelles with 51 nm diameter were detected. The dynamic properties of the surfactant monolayer were affected by both the incorporation of CH and GA. Moreover, the antioxidant activity of the latter remained unaltered (99 %). RPMI 2650 cell line was used as the in vitro model for cell viability and for GA nasal epithelial transport studies after microemulsion administration. The results suggested that the nasal epithelial permeation of GA was enhanced, 3 h post administration, by the presence of 0.2 % v/v microemulsion in the culture medium. However, the concentration of the transported antioxidant in the presence of CH was higher indicating the polymer's effect on the transport of the GA. The study revealed that nasal administration of hydrophilic antioxidants could be used as an alternative route besides oral administration.

Depending on their CTFE content (from 0 to 10 mol %), poly (VDF-ter-TrFE-ter-CTFE), poly(vinylidene fluorideter-trifluoroethylene-ter-chlorotrifluoroethylene) copolymers exhibit ferroelectric (FE) or relaxor ferroelectric (RFE) properties at low temperature whereas they all present paraelectric (PE) behavior at high temperature. This thermal evolution of their electro-active properties is related to reversible crystal-crystal transitions. We studied these structural transitions for three different copolymers with various amount of CTFE (0, 4.4 and 9.7 mol %) using simultaneous SAXS-WAXS experiments along thermal cycles. We identified two types of crystalline phase at low temperature with their proper crystal-crystal transition: the first one containing all-trans conformations (orthorhombic FE phase) has a discontinuous transition towards the hexagonal PE phase, the second one which incorporates gauche disordered conformations (orthorhombic DFE (Defective Ferroelectric) or RFE) transits continuously towards the same hexagonal PE phase. For the intermediate composition (4.4 mol % CTFE), we observe the coexistence of these two simultaneous phase transitions, one discontinuous (FE to PE) and one continuous (RFE to PE), whereas only the continuous one exists in the higher CTFE composition (9.7 mol %). Relaxor ferroelectric properties are precisely observed in the temperature range of the structural RFE to PE transition [0 degrees C, 40 degrees C], highlighting the importance of this crystal-crystal transition. By coupling electric displacement - electric field (D - E) loop measurements, thermo-mechanical experiments (DSC and DMA) and dielectric spectroscopy, we propose a model to explain this RFE-PE continuous crystal-crystal transition in terpolymers.

Films of ferroelectric vinylidene fluoride-trifluoroethylene copolymers, poly(VDF-co-TrFE), are investigated for future applications in organic electronics. For these developments, a composition similar to 70 mol % VDF is selected, thin and isotropic films are evaporated, then annealing and poling steps are performed to increase the amount of ferroelectric phase. Over the past decades, many studies have been mostly done on stretched films for various VDF/TrFE ratios but only few on isotropic films. Here, simultaneous SAXS-WAXS experiments on isotropic films allow for a better understanding of the structural transitions in these systems. As for stretched films, a ferroelectric phase containing conformational defects is observed. However, thanks to the isotropy of the films and to a decomposition of WAXS spectra into amorphous and crystalline contributions, the crystallinity and the shape of crystalline peaks are followed upon heating and cooling. We show thereby for the first time how this Defective Ferroelectric (DFE) phase is created and how it thermally evolves. The DFE phase comes from the crystallization of chemical conformational defects in the paraelectric (PE) phase. By combining structural, thermal and spectroscopic data, a structural model for the evolution of crystalline lamellae is proposed. A structural transition from the orthorhombic DFE phase to the hexagonal PE phase is highlighted below the Curie temperature. These advancements give us keys to improve properties of poly(VDF-co-TrFE) electroactive films. (C) 2016 Elsevier Ltd. All rights reserved.

Successful developments of applications in synchrotron beamlines have led to an increase need for high quality laboratory equipments. We will present the latest features and results with the Xeuss SAXS/WAXS equipment from Xenocs on low concentration protein solutions. A new generation of scatterless collimation with variable resolution opens the door to unprecedented ratios of primary beam intensity to background and to measurements on weakly scattering samples.

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

Muscle contraction is driven by a change in the structure of the head domain of myosin, the “working stroke” that pulls the actin filaments toward the midpoint of the myosin filaments. This movement of the myosin heads can be measured very precisely in intact muscle cells by X-ray interference, but until now this technique has not been applied to physiological activation and force generation following electrical stimulation of muscle cells. By using this approach, we show that the long axes of the myosin head domains are roughly parallel to the filaments in resting muscle, with their center of mass offset by approximately 7 nm from the C terminus of the head domain. The observed mass distribution matches that seen in electron micrographs of isolated myosin filaments in which the heads are folded back toward the filament midpoint. Following electrical stimulation, the heads move by approximately 10 nm away from the filament midpoint, in the opposite direction to the working stroke. The time course of this motion matches that of force generation, but is slower than the other structural changes in the myosin filaments on activation, including the loss of helical and axial order of the myosin heads and the change in periodicity of the filament backbone. The rate of force development is limited by that of attachment of myosin heads to actin in a conformation that is the same as that during steady-state isometric contraction; force generation in the actin-attached head is fast compared with the attachment step.

Complementing structural data obtained by X-ray diffraction with optical spectroscopic techniques has become a growing interest in structural biology.In-situ spectroscopy can reveal the nature of chemical species that remain ambiguous in the electron density maps.Here we present some of the results obtained by the use of the on-axis micro-spectrophotometer developed at beamline X10SA of the Swiss Light Source [1].The on-axis geometry of the micro-spectrophotometer is perfect for studying radiation damage and/or the X-ray induced phenomena.Photo-reduction of the copper centers in Copper nitrite reductase from Achromobacter cycloclastes has been monitored using UV-Vis absorption spectroscopy.A 'low-dose' data set with the Cu centers still oxidized has been collected and the structure has been validated by spectroscopy.Raman spectroscopy under resonant conditions (in the Soret absorption band), has been carried out on two different hemoproteins: myoglobin from horse heart and cytochrome c' from Alcaligenes xylosoxidans by the use of laser probes at either 405 or 413 nm.In both cases vibrational spectroscopy results complement the active site picture provided by X-ray diffraction.Non-resonant Raman experiments, with an excitation wavelength in the near infra red domain (785 nm), have been successfully performed on horse heart insulin and hen egg-white lysozyme.For these two proteins, the disulfide bond breakage due to X-ray exposure has been followed by the decreasing intensity of the S-S stretch band.

Doping effect of nano TiO 2 has been the main concern of material scientists in the field of photocatalyst and dyesensitized solar cell (DSC).The electronic states of doped surface and interface, without regard to the sort of interface including solid/solid and solid/liquid, are very different from the bulk states.For example, Si doping on TiO 2 bulk almost brings minor changes of the main energy level structure near conduction band and valence band.However, when Si is doped on the surface, new doping levels appear in middle position between the conduction band edge and valence band edge.This means that the surface doping of Si will seriously change the electric and optical properties of TiO 2 having high surface area such as nano particle and mesoporous film, although the bulk doping doesn't show any effect.The doping elements in this calculation involved a series of transient metals, IV family group and some light metals.Here, main discussion will be concentrated on the electric properties in association with DSC.

Self-assembled collagen−apatite matrix is prepared through a simple "one-pot" coprecipitation method. Hierarchical structures are reproduced that closely mimic the complex organization in bone tissue and its mechanical anisotropy. These findings offer novel strategies in synthesizing biomimetic materials and highlight the physicochemical aspects of biomineralization.

A series of high molecular weight poly(styrene-b-isoprene) block copolymers with optical properties defined by composition in a non-selective solvent were studied using simultaneous ultra small angle X-ray scattering (USAXS) and optical spectrometry. A small magnitude shear produces ordered and oriented states in the copolymer solutions that persist for extended periods of time, and also have superior optical properties that are directly attributable to the mesoscopic block copolymer (BCP) morphology. We have demonstrated that the optical transmission of these materials can be tuned by the addition of low molecular weight poly(isoprene) and poly(styrene) to swell their respective domains within the diblock copolymer. The optical transmission peak for the diblocks could be tuned; from 380 nm-440 nm for the 670k diblock, 425 nm-540 nm for the 850k diblock and 541 nm-625 nm for the 1 million diblock by altering the solution concentration and composition. The full width at half maximum that can be achieved for the optical transmission peaks is as small as 15 nm at 473 nm with a Δλ/λ of 0.03, highlighting the high quality ordering in these systems. Also a small shift in the transmission peak wavelength was observed across a wide angle of view (15 nm at 30°) suggesting that these materials could be used for large area narrow band optical filters.

We performed a combined small- and wide-angle X-ray scattering (SAXS/WAXS) study of nanocrystallization during annealing of binary Al92Sm8 and Al91Gd9 melt-spun glassy alloys. In course of the transformation an interference maximum develops in the SAXS region while WAXS spectra show formation of fcc-Al nanocrystals in the glassy phase. In order to determine the origin of the SAXS maximum the theoretical SAXS intensity and distance distribution function were calculated considering two structural models. The first model represented a single nanocrystal with a solute layer on its surface and the second one a phase-separated alloy with spatially correlated compositional fluctuations. The results of the calculations are compared with the experimental data. It is demonstrated that only the model representing correlated fluctuations reasonably reproduces the experimental results. We conclude that nano-scale glassy phase separation occurs in the investigated alloys and the nanocrystals form inside the Al-rich amorphous regions.

Structural changes in the myosin motors during the transition from the resting state to the plateau of isometric contraction were investigated by X-ray interference from single fibers of frog skeletal muscle. Isolated intact fibers (2.1μm sarcomere length, 4°C) were mounted vertically at beamline ID2 of the ESRF synchrotron (Grenoble, France) between a loudspeaker motor and a capacitance force transducer. 2D diffraction patterns were collected on a CCD detector 10 m from the preparation with 5 ms time resolution. During the development of the isometric tetanus, the intensity of the M3 reflection, originating from the axial repeat of the myosin motors, first decreases to 30% (at 50 ms) of its resting value, then increases to a steady value 70% of that at rest. The M3 reflection has a major peak with spacing 14.34 nm at rest and two peaks with mean spacing 14.57 nm at the tetanus plateau (Linari et al., Proc. Natl. Acad. Sci. USA 97:7226, 2000). The changes in the fine structure of the M3 reflection during activation were best fit by a structural model in which (1) all thick filaments have the same mean spacing at a given time during activation (2) the number of active motors increases in proportion to the isometric force (Brunello et al., J. Physiol. 577:971 2006), (3) the conformation of the active motors is independent of the level of force and strain in the thick filament. Supported by MiUR Italy, MRC UK, CNISM, EMBO, ESRF, EMBL.

The structure and orientation dynamics of sepiolite clay fibers about 1,000 nm long and 10 nm thick, suspended in an aqueous poly(ehtylene oxide) matrix of 105 g/mol molecular mass, have been studied under control extensional and shear flow. A new extensional flow cell developed at the “Laboratoire de Rhéologie” and the combined rheology and small angle X-ray scattering (Rheo-SAXS) setup available at the European Synchrotron Radiation Facility have allowed access to in situ and time-resolved fiber orientations and structure properties in the volume of suspensions under flow. In the volume fractions and shear rate domains for which the suspensions exhibit shear-thinning properties, two regimes of orientation separated by a critical strain rate have been identified under extensional flow.

showed that although local, near-to-equilibrium systems may be interlocked. Thus, for example, if the act of proton pumping were reversibly connected to ATP synthesis, the ATP could then be used as a key component of other near-to-equilibrium systems such as metabolism and/or cytoskeletal activities. I propose a specific mechanism for the act of proton pumping that qualifies as a near-to-equilibrium system. It embodies motion perpendicular to the membrane plane for ion pumping. The mechanism is both cooperative and synchronized. Each transport event results in a compaction of the protein across the membrane provoking a neighboring pump to expand and visa versa. The mechanism implies that pumps be dimers or multimers in living membranes although they could pump individually when reconstituted into bilayers. It is the nature of the pumping mechanism that it can be restarted with Brownian motion if it falters.

showed that although local, near-to-equilibrium systems may be interlocked.Thus, for example, if the act of proton pumping were reversibly connected toATP synthesis, the ATP could then be used as a key component of othernear-to-equilibrium systems such as metabolism and/or cytoskeletal activities.I propose a specific mechanismfor the act of proton pumping that qualifies as anear-to-equilibriumsystem.Itembodiesmotionperpendiculartothemembraneplane for ion pumping. The mechanism is both cooperative and synchronized.Eachtransporteventresultsinacompactionoftheproteinacrossthemembraneprovokinganeighboringpumptoexpandandvisaversa.Themechanismimpliesthat pumps be dimers or multimers in living membranes although they couldpumpindividuallywhenreconstitutedintobilayers.Itisthenatureofthepump-ing mechanism that it can be restarted with Brownian motion if it falters.

The route by which amphiphilic molecules self-assemble into micelles is still not fully understood. In this Letter, we present direct structural information on the birth and growth of block copolymer micelles by means of synchrotron x-ray scattering with millisecond time resolution. Using a quantitative model, we show that the self-assembly process can be viewed as a nucleation and growth type process where the elemental growth mechanism is an exchange of single molecules.