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We report the first (in)elastic scattering measurement of with the capability to select and measure in a broad energy range the proton resonances in contributing to the reaction at type I x-ray burst energies. We measured spin-parities of four resonances above the threshold of that are found to strongly impact the rate. The new rate advances a state-of-the-art model to remarkably reproduce light curves of the GS clocked burster with mean deviation and permits us to discover a strong correlation between the He abundance in the accreting envelope of the photospheric radius expansion burster and the dominance of branch., SCOPUS: ar.j, info:eu-repo/semantics/published

Specular and off-specular neutron reflectometry have been used in a combined approach to study thin polymer films. Our goal in this work is to illustrate the power of the off-specular scattering technique to probe the properties of the buried interface of immiscible polymer bilayers of deuterated polystyrene and protonated poly(methyl methacrylate) (h-PMMA). The diffuse scattering stemming from these systems is discussed in relation to thermal fluctuations at the polymer/polymer interface, providing a means to extract in-plane correlation lengths from buried interfaces. In addition the onset of hole formation in the top layer is evidenced by the diffuse scattering, not easily detectable by specular reflection alone., SCOPUS: ar.j, info:eu-repo/semantics/published

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An extended investigation of the low-spin structure of the Ni65 nucleus was performed at the Institut Laue-Langevin, Grenoble, France, via the neutron capture reaction Ni64(n,γ)Ni65, using the Fission Product Prompt Gamma-Ray Spectrometer High-Purity Ge array. The level scheme of Ni65 was significantly expanded, with two new levels and 87 newly found transitions. Angular correlation analyses were also performed, allowing us to assign spins and parities for a number of states and to determine multipolarity mixing ratios for selected γ transitions. The low-energy part of the experimental level scheme (up to about 1.4 MeV) was compared with Monte Carlo shell-model calculations, which predict spherical shapes for all states, apart from the 9/2+ and the second excited 1/2- states of oblate deformation., SCOPUS: ar.j, info:eu-repo/semantics/published

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Elastic and inelastic alpha scatterings on C10 were measured using a 68-MeV/u radioactive C10 beam incident on the recently developed MAIKo active target system. The phenomenological effective α-N interaction and the point-nucleon density distribution in the ground state were determined from the elastic scattering data. The cross sections of the inelastic alpha scattering were calculated using this interaction and density distribution and were compared with the experiment to determine the neutron quadrupole transition matrix element Mn between the ground state and the 21+ state at Ex=3.35 MeV in C10. The deduced neutron transition matrix element is Mn=6.9±0.7(fit)±1.2(sys)fm2. The ratio of the neutron transition strength to proton transition strength was determined as Mn/Mp=1.05±0.11(fit)±0.17(sys), which indicates that the quadrupole transition between the ground state and the 21+ state in C10 is less neutron dominant compared to that in C16., SCOPUS: ar.j, info:eu-repo/semantics/published

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Specular reflectivity (SR) and off-specular neutron scattering (OSS) are non-destructive scattering techniques, which, through deuteration (exchange of hydrogen atoms with deuterium), give a high contrast even among very similar chemical species and are therefore highly suitable for investigations of soft thin films. While readily available software exists for analysis of SR, there are no such existing tools for OSS. Through a combination of both, the former yielding a density profile in the direction normal to the sample surface and the latter yielding an in-plane lateral structure at each of the buried interfaces, one can obtain detailed information of buried morphology on length scales ranging from angstroms to 10 micrometres. OSS analysis was developed to analyze buried interfaces in absolute scale, with only structural parameters being free. Moreover, the SR and OSS are intricately linked and have to be fitted to the data simultaneously, constraining the model to a high degree. The OSS was applied to investigation of soft interfaces as model systems.The stability and instability of thin polymer layers have been studied extensively in the last decades, both as their applications as coatings have become part of our daily life, and in fundamental soft matter research. The mechanism of immiscible polymer film decomposition was investigated by preparing bilayers of deuterated polystyrene (d-PS) and protonated poly(methyl methacrylate) (h-PMMA) of different thicknesses on Si substrates. The in-plane lateral cutoff length was measured at the PS/PMMA interface as a function of d-PS thickness. For preannealed films with thickness of dPS below 250 angstroms, the result follows the prediction of the capillary waves cutoff length. For thicker films, spontaneous nucleation of the top layer, with a clear OSS signature, was observed. This was also the case for the non-preannealed samples, showing that preannealing causes irreversible adsorption on the substrate and thus stabi, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

A substrate-supported phospholipid bilayer (SPB) is commonly used as a model bio-membranes on a solid substrate. The most common method to make SPBs is the adsorption followed by rupture of phospholipid vesicles on a substrate surface in contact with the vesicle solution. However, this method may present an applicability issue due to the limitation of combination of the phospholipids and substrates. On the other hand, adhesion of disklike micelles consisting of phospholipid, so-called bicelles, is a hopeful alternative method for making SPBs since they don't need the rupture process. The mechanism of the nanodisk adhesion on a substrate is, however, not fully understood yet. In this study, in-situ observation of the bicelle adhesion was performed using neutron reflectometry (NR), which can shed light on the depth profile of bilayer density at the interface between a substrate and bicelle solution. In addition, atomic force microscopy (AFM) was employed for the topographic imaging and force response measurement of the adhesion layer. These results presented that lamellae of phospholipid bilayers were aligned parallel to a surface of a bare Si substrate, whereas a fragile layer of unoriented phospholipid bilayers was formed on a NH2 coated Si substrate., SCOPUS: ar.j, info:eu-repo/semantics/published

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The interaction between two immiscible materials is related to the number of contacts per unit area formed by the two materials. For practical reasons, this information is often parametrized by the interfacial free energy, which is commonly derived via rather cumbersome approaches, where properties of the interface are described by combining surface parameters of the single materials. These combining rules, however, neglect any effect that geometry might have on the strength of the interfacial interaction. In this Article, we demonstrate that the number of contacts at the interface between a thin polymer coating and its supporting substrate is altered upon confinement at the nanoscale level. We show that explicitly considering the effect of nanoconfinement on the interfacial potential allows a quantitative prediction of how sample geometry affects the number of contacts formed at the interface between two materials., SCOPUS: ar.j, info:eu-repo/semantics/published

A search for shape isomers in the Ni66 nucleus was performed, following old suggestions of various mean-field models and recent ones, based on state-of-the-art Monte Carlo shell model (MCSM), all considering Ni66 as the lightest nuclear system with shape isomerism. By employing the two-neutron transfer reaction induced by an O18 beam on a Ni64 target, at the sub-Coulomb barrier energy of 39 MeV, all three lowest-excited 0+ states in Ni66 were populated and their γ decay was observed by γ-coincidence technique. The 0+ states lifetimes were assessed with the plunger method, yielding for the 02+, 03+, and 04+ decay to the 21+ state the B(E2) values of 4.3, 0.1, and 0.2 Weisskopf units (W.u.), respectively. MCSM calculations correctly predict the existence of all three excited 0+ states, pointing to the oblate, spherical, and prolate nature of the consecutive excitations. In addition, they account for the hindrance of the E2 decay from the prolate 04+ to the spherical 21+ state, although overestimating its value. This result makes Ni66 a unique nuclear system, apart from U236,238, in which a retarded γ transition from a 0+ deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior., SCOPUS: ar.j, info:eu-repo/semantics/published

The neutron-rich nucleus Pt200 is investigated via in-beam γ-ray spectroscopy to study the shape evolution in the neutron-rich platinum isotopes towards the N=126 shell closure. The two-neutron transfer reaction Pt198(Se82, Se80)Pt200 is used to populate excited states of Pt200. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects γ rays coincident with the Se80 recoils, the binary partner of Pt200. The binary partner method is applied to extract the γ-ray transitions and build the level scheme of Pt200. The level at 1884 keV reported by Yates et al. [S. W. Yates, E. M. Baum, E. A. Henry, L. G. Mann, N. Roy, A. Aprahamian, R. A. Meyer, and R. Estep, Phys. Rev. C 37, 1889 (1988)] was confirmed to be at 1882.1 keV and assigned as the (61+) state. An additional γ ray was found and it presumably deexcites the (81+) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even 190-204Pt isotopes, revealing that Pt200 marks the transition from the γ-unstable behavior of lighter Pt nuclei towards a more spherical one when approaching the N=126 shell closure., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

In the present contribution we investigate poly(4-tert-butyl styrene) films ranging from 25 to 265 nm, by means of spectroscopic ellipsometry technique. It is shown that when a 25-nm-thin film of poly(4-tert-butyl styrene) cooled down at constant rate it vitrifies 50 K lower than in bulk. This record sets the largest depression in thermal glass transition temperature (Tg) ever observed upon confinement at the nanoscale level. Same as for other supported polymer layers, this reduction in Tg has been attributed to the presence of a free surface, the ensemble of molecules at the interface with air remaining in the liquid state also at temperatures well below bulk Tg. In this work, we verify that such tremendous shifts can be erased upon prolonged annealing in the liquid state, hinting at a metastable nature of confinement effects. We demonstrate that the recovery of bulk behavior and the manifestation of the free surface are enslaved to the kinetics of irreversible adsorption of chains on the supporting substrate

When cooled at constant rate, a 25 nm thin film of poly(4-tert-butylstyrene) vitrifies 50 K lower than in bulk. This record sets the largest depression in thermal glass transition temperature (T) ever observed upon confinement at the nanoscale level. Same as for other supported polymer layers, this reduction in T has been attributed to the presence of a free surface, the ensemble of molecules at the interface with air remaining in the liquid state also at temperatures well below bulk T. Here, we verify that such tremendous shifts can be erased upon prolonged annealing in the liquid state, hinting at a metastable nature of confinement effects. We demonstrate that the recovery of bulk behavior and the manifestation of the free surface are enslaved to the kinetics of irreversible adsorption of chains on the supporting substrate.

The discussions on the nanoconfinement effect on the glass transition and glassy dynamics phenomena have yielded many open questions. Here, the thickness dependence of the thermal glass transition temperature Tgtherm of thin films of a PVME/PS blend is investigated by ellipsometry. Its thickness dependence was compared to that of the dynamic glass transition (measured by specific heat spectroscopy) and the deduced Vogel temperature (T0). While Tg therm and T0 showed a monotonous increase, with decreasing film thickness, the dynamic glass transition temperature (Tgdyn) measured at a finite frequency showed a nonmonotonous dependence that peaks at 30 nm. This was discussed by assuming different cooperativity length scales at these temperatures, which have different sensitivities to composition and thickness. This nonmonotonous thickness dependence of Tgdyn disappears for frequencies characteristic for T0. Further analysis of the fragility parameter showed a change in the glassy dynamics from strong to fragile, with decreasing film thickness., SCOPUS: ar.j, info:eu-repo/semantics/published

When cooled at constant rate, a 25 nm thin film of poly(4-tert-butylstyrene) vitrifies 50 K lower than in bulk. This record sets the largest depression in thermal glass transition temperature (Tg) ever observed upon confinement at the nanoscale level. Same as for other supported polymer layers, this reduction in Tg has been attributed to the presence of a free surface, the ensemble of molecules at the interface with air remaining in the liquid state also at temperatures well below bulk Tg. Here, we verify that such tremendous shifts can be erased upon prolonged annealing in the liquid state, hinting at a metastable nature of confinement effects. We demonstrate that the recovery of bulk behavior and the manifestation of the free surface are enslaved to the kinetics of irreversible adsorption of chains on the supporting substrate., SCOPUS: ar.j, info:eu-repo/semantics/published

We investigated the impact of irreversible adsorption on the mechanisms of thermal expansion of 1D confined polymer layers. For spincoated films (polystyrene on aluminum) of constant thickness, the thermal expansion coefficient of the melt drops upon annealing following the kinetics of irreversible adsorption of the chains onto the supporting substrate, while the thermal expansion of the glass is annealing invariant. These perturbations are explained in terms of the reduction in free volume content, upon immobilization of monomers onto the substrate. To shed more light on this phenomenon, we performed an extensive investigation of the thermal expansion of irreversibly adsorbed layers of polystyrene on silicon oxide. We verified that, contrarily to recent speculations, these films cannot be modeled as dead layers - immobilized slabs lacking of segmental relaxation. On the contrary, thin adsorbed layers show an increase in thermal expansion with respect to the bulk, due to packing frustration. Immobilization plays a role only when the thickness of the adsorbed layers overcomes ∼10 nm. Finally, we show that for adsorbed layers the difference in thermal expansion between the melt and the glass is sufficiently high to investigate the glass transition down to 3 nm. Owing to this unique feature, not shared by spincoated films, adsorbed layers are the perfect candidate to study the properties of extremely thin polymer films., SCOPUS: ar.j, info:eu-repo/semantics/published

Film forming properties of semiconducting organic molecules comprising alkyl-chains combined with an aromatic unit have a decisive impact on possible applications in organic electronics. In particular, knowledge on the film formation process in terms of wetting or dewetting, and the precise control of these processes, is of high importance. In the present work, the subtle effect of temperature on the morphology and structure of dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) films deposited on silica surfaces by spin coating is investigated in situ via X-ray diffraction techniques and atomic force microscopy. Depending on temperature, bulk C8-BTBT exhibits a crystalline, a smectic A and an isotropic phase. Heating of thin C8-BTBT layers at temperatures below the smectic phase transition temperature leads to a strong dewetting of the films. Upon approaching the smectic phase transition, the molecules start to rewet the surface in the form of discrete monolayers with a defined number of monolayers being present at a given temperature. The wetting process and layer formation is well defined and thermally stable at a given temperature. On cooling the reverse effect is observed and dewetting occurs. This demonstrates the full reversibility of the film formation behavior and reveals that the layering process is defined by an equilibrium thermodynamic state, rather than by kinetic effects., SCOPUS: ar.j, info:eu-repo/semantics/published

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Controlling polymer/substrate interfaces without modifying chemistry is nowadays possible by finely tuning the formation of adsorbed layers. The complex processes leading to irreversible attachment of chains onto solid substrates are governed by two mechanisms: molecular rearrangement and potential-driven adsorption. Here we introduce an analytical method to differentiate these two mechanisms. By analyzing experiments and simulations, we investigate how changes in thermal energy and interaction potential affect equilibrium and nonequilibrium components of the adsorption kinetics. We find that the adsorption process is thermally activated, with activation energy comparable to that of local noncooperative processes. On the other hand, the final adsorbed amount depends on the interface interaction only (i.e. it is temperature independent in experiments). We identify a universal linear relation between the growth rates at short and long adsorption times, suggesting that the monomer pinning mechanism is independent of surface coverage, while the progressive limitation of free sites significantly limits the adsorption rate., SCOPUS: ar.j, info:eu-repo/semantics/published

Organic semiconducting materials in confined geometries present interesting properties connected to change or the coexistence of molecular organizations, depending on their characteristic scales. In this work the preparation and structural characterization of self-assembled π-conjugated organic nanoplates of 2,7-diperfluorohexyl-[1]benzothieno[3,2,b]benzothiophene are studied. These nanostructures were prepared by spin coating, implementing a fast precipitation method. We observed an evolution of the nanostructures from hexagonal towards triangular nanoplates, possibly driven by enhanced solvent/molecule interactions, and accompanied by the formation of a new polymorph., info:eu-repo/semantics/published

An attractive methodology based on diazonium chemistry has been developed for the surface modification of polymers such as polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS). The grafting procedure involves the in situ formation of diazoates in basic aqueous solution. The reactivity of calix[4]arene-tetradiazonium salts and a classical aryldiazonium salt was examined through comparative studies on gold and polymer surfaces. The surfaces were analyzed with a combination of techniques such as AFM, XPS, and ellipsometry. The results highlighted the fact that the calix[4]arene molecules are grafted as a robust and uniform monolayer both on gold and polymer surfaces, allowing a fine control over surface modification. Furthermore, the chemical postfunctionalization of the grafted calixarene platforms equipped with carboxylic-pendant groups was successfully performed with either an amine or an alcohol. These results open real possibilities in the controlled immobilization on polymers of a wide variety of molecules of interest such as biomolecules or chromophores and in the tailoring of polymer properties.

An attractive methodology based on diazonium chemistry has been developed for the surface modification of polymers such as polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS). The grafting procedure involves the in situ formation of diazoates in basic aqueous solution. The reactivity of calix[4]arene-tetradiazonium salts and a classical aryldiazonium salt was examined through comparative studies on gold and polymer surfaces. The surfaces were analyzed with a combination of techniques such as AFM, XPS, and ellipsometry. The results highlighted the fact that the calix[4]arene molecules are grafted as a robust and uniform monolayer both on gold and polymer surfaces, allowing a fine control over surface modification. Furthermore, the chemical postfunctionalization of the grafted calixarene platforms equipped with carboxylic-pendant groups was successfully performed with either an amine or an alcohol. These results open real possibilities in the controlled immobilization on polymers of a wide variety of molecules of interest such as biomolecules or chromophores and in the tailoring of polymer properties., SCOPUS: ar.j, info:eu-repo/semantics/published

The structural organization and evolution of the organic semiconducting molecule 2,7-dioctyloxy[1]benzothieno[3,2-b]-benzothiophene on a soft matrix is studied. Thin films of a blend formed from polystyrene and the molecule were prepared by spin-coating onto silicon substrates, which were subsequently studied by using a combination of microscopy and scattering techniques. The organic semiconducting molecule segregated to the surface and developed a phase with a different structure to the bulk, as in the case of a substrate induced phase observed previously. Under a solvent vapor annealing procedure, the growth of micrometer-sized tetragonal crystals onto the polymer surface was observed, which was not evidenced for the silicon substrates., SCOPUS: ar.j, SCOPUS: ar.j, FLWNA, info:eu-repo/semantics/published

Oligo(ethylene glycol) films are known to be very efficient at reducing the non-specific adsorption of biomacromolecules on surfaces, but they often show a tendency to decrease drastically the rate of heterogeneous electron transfer at the modified surface, making them unsuitable for electrochemical biosensing. In this work, the heterogeneous electron transfer across the self-assembled monolayer of a short thiolated oligo(ethylene glycol) is investigated using four redox systems: [Fe(CN)6]3−/4−, [Ru(NH3)6]3+/2+, Fc(MeOH)2+/0 and [IrCl6]2−/3−. Fast electron transfer kinetics are evidenced in all cases except the ferri/ferrocyanide couple, for which the electron transfer is completely suppressed. Interfacial characterizations by means of spectroscopic ellipsometry, electrochemical desorption experiments and capacity measurements indicate that the film consists of a fairly hydrated single monolayer with a surface concentration of 4.1 × 10−10 mol cm−2. The peculiar behavior of [Fe(CN)6]3−/4− is discussed in terms of the hydration properties of both the monolayer and the electroactive anions. Interestingly, the self-assembled monolayer exhibits the desired antifouling properties against protein adsorption, tested with bovine serum albumin, making this system a promising platform for the development of electrochemical biosensors., SCOPUS: ar.j, info:eu-repo/semantics/published

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Glass forming systems are characterized by a stability against crystallization upon heating and by the easiness with which their liquid phase can be transformed into a solid lacking of long-range order upon cooling (glass forming ability). Here, we report the thickness dependence of the thermal phase transition temperatures of poly(l-lactide acid) thin films supported onto solid substrates. The determination of the glass transition, cold crystallization and melting temperatures down to a thickness of 6 nm, permitted us to build up parameters describing glass stability and glass forming ability. We observed a strong influence of the film thickness on the latter, while the former is not affected by 1D confinement. Further experiments permitted us to highlight key structural morphology features giving insights to our ellipsometric results via a physical picture based on the changes in the free volume content in proximity of the supporting interfaces., SCOPUS: ar.j, info:eu-repo/semantics/published

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The activity of the potent but highly toxic antifungal drug Amphotericin B (AmB), used intravenously to treat systemic fungal and parasitic infections, is widely accepted to result from its specific interaction with the fungal sterol ergosterol. While the effect of sterols on AmB activity has been intensely investigated, the role of membrane phospholipid composition has largely been ignored, and structural studies of native membranes have been hampered by their complex and disordered nature. We show for the first time that the structure of fungal membranes derived from Pichia pastoris yeast depends on the degree of lipid polyunsaturation, which has an impact on the structural consequences of AmB activity. AmB inserts in yeast membranes even in the absence of ergosterol, and forms an extra-membraneous layer whose thickness is resolved to be 4-5 nm. In ergosterol-containing membranes, AmB insertion is accompanied by ergosterol extraction into this layer. The AmB-sponge mediated depletion of ergosterol from P. pastoris membranes gives rise to a significant membrane thinning effect that depends on the degree of lipid polyunsaturation. The resulting hydrophobic mismatch is likely to interfere with a much broader range of membrane protein functions than those directly involving ergosterol, and suggests that polyunsaturated lipids could boost the efficiency of AmB. Furthermore, a low degree of lipid polyunsaturation leads to least AmB insertion and may protect host cells against the toxic effects of AmB. These results provide a new framework based on lipid composition and membrane structure through which we can understand its antifungal action and develop better treatments., info:eu-repo/semantics/published

The thermal stability and molecular order in monolayers of two organic semiconductors, PBI-PA and PBI-alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI-PA, are reported. In situ X-ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI-PA monolayers have a high degree of order at room temperature and a stable film exists up to 250°C, but decomposes rapidly above 300°C. In contrast, stable physisorbed PBI-alkyl monolayers only exist up to 100°C. Above the bulk melting point at 200°C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate. Tie your monolayer down: In situ X-ray reflectivity measurements are used to follow the structural evolution of monolayer organic semiconductor films with increasing temperature. Using an anchor group in the monolayers is found to add significantly to their stability at elevated temperatures when compared to monolayers with an identical structure without an anchor group., SCOPUS: ar.j, FLWNA, info:eu-repo/semantics/published

Ce travail porte sur l’étude électrochimique et par microscopie de fluorescence in situ de l’auto-assemblage, sur électrode d’or, de monocouches d’aptamères peptidiques de la protéine p53 en vue de la détection de la protéine MDM2. L’utilisation de nouvelles sondes de reconnaissance moléculaire telles que les aptamères peptidiques a été considérée en tant qu’alternative à l’utilisation d’anticorps. Les aptamères peptidiques sont des séquences synthétiques de peptide se liant à la protéine cible avec une affinité et une spécificité élevées. La première partie de ce travail porte sur l’étude électrochimique de l’interface modifiée résultant de diverses procédures d’immobilisation. Des mesures en présence du marqueur rédox [Ru(NH3)6]3+ ont démontré l’immobilisation de la sonde peptidique à la surface d’or et ont permis l’évaluation relative de la densité de sondes adsorbées à la surface respectivement à la méthode d’immobilisation considérée. Par ailleurs, des mesures en présence du couple rédox [Fe(CN)6]3-/4- ont mis en évidence une inhibition drastique du transfert d’électron dans le cas de monocouches composées exclusivement du peptide. Dans un second temps, nous nous sommes intéressés à la détection de la protéine MDM2. Trois interfaces modifiées ont été envisagées soit deux monocouches mixtes de peptide et de 4-mercaptobutan-1-ol, ce dernier jouant le rôle de diluant, adsorbés en une ou en deux étape(s), et une monocouche uniquement composée de peptide. L’utilisation de la spectroscopie d’impédance électrochimique en présence du couple rédox [Fe(CN)6]3-/4- comme méthode de détection a mis en exergue la pertinence de cette dernière interface pour la détection. En effet, l’inhibition du transfert d’électron préalablement identifiée est fortement amoindrie suite à l’interaction avec la protéine cible. Une gamme de détection s’étendant de ~1 à 60 ng mL-1 et une limite de détection de 0,69 ng mL-1 ont été obtenues. Cette performance est comparable à celle des kits ELIS, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

The shape transition in the neutron-rich Os isotopes is studied by investigating the neutron-rich 196Os nucleus through in-beam γ-ray spectroscopy using a two-proton transfer reaction from a 198Pt target to a 82Se beam. The beam-like recoils were detected and identified with the large-acceptance magnetic spectrometer PRISMA, and the coincident γ rays were measured with the advanced gamma tracking array (AGATA) demonstrator. The de-excitation of the low-lying levels of the yrast-band of 196Os were identified for the first time. The results are compared with state-of-the-art beyond-mean-field calculations, performed for the even-even 188-198Os isotopes. The new results suggest a smooth transition in the Os isotopes from a more axial rotational behavior towards predominately vibrational nuclei through triaxial configurations. An almost perfect γ-unstable/triaxial rotor yrast band is predicted for 196Os which is in agreement with the experimentally measured excited states. © 2014 American Physical Society., SCOPUS: ar.j, info:eu-repo/semantics/published

In this work, we present an exploratory experiment performed at REX-ISOLDE to investigate neutron-rich Sr, Y and Zr nuclei around mass A = 100 by cluster transfer reactions of radioactive 98Rb/98Sr beams on a 7Li target. The goal of the experiment is to test the potential of clustertransfer mechanism to study the low-lying structure of neutron-rich nuclei, performing, as a first case, a -spectroscopy study of the structure in deformed nuclei beyond N = 60 populated, so far, only via β decay and spontaneous fission experiments., SCOPUS: ar.j, info:eu-repo/semantics/published

A detailed structural study of the bulk and thin film phases observed for two potential high-performance organic semiconductors has been carried out. The molecules are based on [1]benzothieno[3,2-b]benzothiophene (BTBT) as conjugated core and octyl side groups, which are anchored either symmetrically at both sides of the BTBT core (C8-BTBT-C8) or nonsymmetrically at one side only (C8-BTBT). Thin films of different thickness (8-85 nm) have been prepared by spin-coating for both systems and analyzed by combining specular and grazing incidence X-ray diffraction. In the case of C 8-BTBT-C8, the known crystal structure obtained from single-crystal investigations is observed within all thin films, down to a film thickness of 9 nm. In the case of C8-BTBT, the crystal structure of the bulk phase has been determined from X-ray powder diffraction data with a consistent matching of experimental and calculated X-ray diffraction patterns (Rwp = 5.8%). The packing arrangement of C8-BTBT is similar to that of C8-BTBT-C8, that is, consisting of a lamellar structure with molecules arranged in a "herringbone" fashion, yet with lamellae composed of two head-to-head (or tail-to-tail as the structure is periodic) superimposed molecules instead of only one molecule for C8-BTBT-C8. As for C8-BTBT-C8, we demonstrate that the same phase is observed in bulk and thin films for C 8-BTBT whatever the film thickness investigated. © 2014 American Chemical Society., info:eu-repo/semantics/published

Recent experimental evidence showed a strong correlation between the behavior of polymers under confinement and the presence of a layer irreversibly adsorbed onto the supporting substrate, hinting at the possibility to tailor the properties of ultrathin films by controlling the adsorption kinetics. At the state of the art, however, the study of physisorption of polymer melts is mainly limited to theory and simulations. To overcome this gap, we present the results of an extensive investigation of the kinetics of irreversible adsorption of entangled melts of polystyrene onto silicon oxide. We show that the process of chain pinning proceeds via a first order reaction mechanism, which slows down at large surface coverage, and the adsorbed amount scales with the predictions of reflected random walk. We propose an analytical form of the time evolution of the thickness of the adsorbed layer with two well-defined regimes: linear at short times and logarithmic at longer times, separated by a temperature independent crossover thickness and a molecular weight independent crossover time, in line with simulations and theory. © 2014 American Chemical Society., SCOPUS: ar.j, info:eu-repo/semantics/published

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The connection between phase shifts and the ANC has been explored in the frame of the effective range theory. The main result is that, in practice and under rather simple requirements, scattering states (phases shifts) can be correctly described and connected with bound states via the effective range function, and therefore, ANCs can be accurately determined thanks to the analytic properties of this function. This result has an important impact in stellar evolution due to the ANC and phases shifts are directly connected with capture cross sections which, for instance, determine partially the stage and evolution of stars.As a first step, the effective range function is approximated via the effective range expansion which shows that a successful phase-shift description depends on how precise the effective range parameters are determined. Thus, a technique to compute accurately these parameters is developed here. Its construction is based on a set of recurrence relations at low energy, that allows a compact and general description of the truncatedeffective range expansion. Several potential models are used to illustrate the effectivenessof this technique and to discuss its numerical limitations. The results shows that a very good precision of the effective-range parameters can be achieved; nevertheless, to describe experimental phase shifts several effective-range parameters can be needed, which shows a limitation for practical applications.As a second step, the effective range function is analyzed theoretically in an arbitrary energy range. This analysis shows that this function can be decomposed in such a way that contributions of bound states, resonances and background can be separated in a similar way as in the phenomenological R-matrix. In this new form experimental data can be better fitted because the free parameter space is reduced considerably,and therefore, extrapolations are better handled. By construction, the method agrees with the sca, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

The concentration profile of deuterated myoglobin (Mb) adsorbed onto polystyrene substrates displaying poly(ethylene glycol) (PEG) brushes is characterized by neutron reflectometry (NR). The method allows to directly distinguish among primary adsorption at the grafting surface, ternary adsorption within the brush, and secondary adsorption at the brush outer edge. It complements depth-insensitive standard techniques, such as ellipsometry, radioactive labeling, and quartz crystal microbalance. The study explores the effect of the PEG polymerization degree, N, and the grafting density, σ, on Mb adsorption. In the studied systems there is no indication of secondary or ternary adsorption, but there is evidence of primary adsorption involving a dense inner layer at the polystyrene surface. For sparsely grafted brushes the primary adsorption involves an additional dilute outer protein layer on top of the inner layer. The amount of protein adsorbed in the inner layer is independent of N but varies with σ, while for the outer layer it is correlated to the amount of grafted PEG and is thus sensitive to both N and σ. The use of deuterated proteins enhances the sensitivity of NR and enables monitoring exchange between deuterated and hydrogenated species. © 2013 American Chemical Society., SCOPUS: ar.j, info:eu-repo/semantics/published