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Intrinsic optoelectronic properties of atomically precise graphene nanoribbons (GNRs) remain largely unexplored because of luminescence quenching effects that are due to the metallic substrate on which the ribbons are grown. We probed excitonic emission from GNRs synthesized on a metal surface with atomic-scale spatial resolution. A scanning tunneling microscope (STM)–based method to transfer the GNRs to a partially insulating surface was used to prevent luminescence quenching of the ribbons. STM-induced fluorescence spectra reveal emission from localized dark excitons that are associated with the topological end states of the GNRs. A low-frequency vibronic emission comb is observed and attributed to longitudinal acoustic modes that are confined to a finite box. Our study provides a path to investigate the interplay between excitons, vibrons, and topology in graphene nanostructures.

Background: Polytrauma patients with SARS-CoV-2 infections may be associated with an increased complication rate. The main goal of this study was to analyze the clinical course of trauma patients with COVID infection and a positive CT finding. Methods: This was a retrospective in-hospital study. Polytrauma patients diagnosed with SARS-CoV-2 infections were included in our analysis. The outcome parameters were pulmonary complication during admission, pulmonary embolism, pleural effusion, pneumonia, mortality, length of stay and readmission < 30 days. Results: 48 patients were included in the study. Trauma patients in the age-adjusted matched-pair analysis with typical changes in SARS-CoV-2 infection in CT findings showed significantly more pulmonary complications in general and significantly more cases of pneumonia (complications: 56% vs. 11%, p = 0.046; pneumonia 44% vs. 0%, p = 0.023). In addition, the clinical course of polytrauma patients with SARS-CoV-2 infection showed a high rate of pulmonary complications in the inpatient course (53%). Conclusion: The results of our study show that the changes in the CT findings of trauma patients with SARS-CoV-2 infection are a good indicator of further inpatient outcomes. Similarly, polytrauma patients with a SARS-CoV-2 infection and positive CT findings are shown to have increased risk for pulmonary complications.

A scanning tunneling microscope is used to study the fluorescence of a model charged molecule (quinacridone) adsorbed on a sodium chloride (NaCl)-covered metallic sample. Fluorescence from the neutral and positively charged species is reported and imaged using hyper-resolved fluorescence microscopy. A many-body excitation model is established based on a detailed analysis of voltage, current and spatial dependencies of the fluorescence and electron transport features. This model reveals that quinacridone adopts a large palette of charge states, transient or not, depending on the voltage used and the nature of the underlying substrate. This model has a universal character and explains the electronic and fluorescence properties of many other molecules adsorbed on thin insulators.

The optical properties of chromophores can be efficiently tuned by electrostatic fields generated in their close environment, a phenomenon that plays a central role for the optimization of complex functions within living organisms where it is known as internal Stark effect (ISE). Here, we realised an ISE experiment at the lowest possible scale, by monitoring the Stark shift generated by charges confined within a single chromophore on its emission energy. To this end, a scanning tunneling microscope (STM) functioning at cryogenic temperatures is used to sequentially remove the two central protons of a free-base phthalocyanine chromophore deposited on a NaCl-covered Ag(111) surface. STM-induced fluorescence measurements reveal spectral shifts that are associated to the electrostatic field generated by the internal charges remaining in the chromophores upon deprotonation.

Epitaxial clusters of chromium and chromium-vanadium oxides are studied by tunnel magneto-resistivity measurements, x-ray absorption spectrometry and circular magnetic circular dichroism. They turn out to carry a small magnetic moment that follows a super-paramagnetic behavior. The chromium ion contribution to this magnetization is mainly due to an original magnetic Cr

The objective was to report radiological and clinical outcomes after reversed L-shaped osteotomy (ReveL) for hallux valgus (HV). A retrospective cohort study was performed between January 2004 and December 2013. The primary outcome was radiological recurrence of HV (HV angle [HVA] >15°). There were various exposure and secondary outcome variables. The results showed a median follow-up of 12.0 months (N = 827). Radiological recurrence, limited patient satisfaction, complication, revision surgery, and elective hardware removal were found in 25.0%, 15.3%, 4.6%, 2.5%, and 26.7%. Median pre- to postoperative changes were highest for HVA (delta = –16.7°). Recurrence was more likely in cases with preoperative HVA ≥40° (adjusted odds ratio [ORadjusted]) 3.63, p

Epitaxial clusters of chromium and chromium–vanadium oxides are studied by tunnel magneto-resistivity measurements, x-ray absorption spectrometry and circular magnetic circular dichroism. They turn out to carry a small magnetic moment that follows a super-paramagnetic behavior. The chromium ion contribution to this magnetization is mainly due to an original magnetic Cr2O3-like phase, whereas usual Cr2O3 is known to be anti-ferromagnetic in the bulk. For mixed clusters, vanadium ions also contribute to the total magnetization and they are coupled to the chromium ion spins. By measuring the dichroic signal at different temperatures, we get insight into the possible spin configurations of vanadium and chromium ions: we propose that the magnetic dipoles observed in the clusters assembly could be related to ionic spins that couple at a very short range, as for instance in short one-dimensional spins chains.

Background Hallux valgus deformity (HV) affects around every fourth individual, and surgical treatment is performed in every thousandth person. There is an ongoing quest for the best surgical management and reduction of undesirable outcomes. The aim was to explore associations of obesity and gender with radiological and clinical outcome after reversed L-shaped osteotomy (ReveL) for HV. Materials and methods This study was carried out in a retrospective cohort design at a single University Hospital in Switzerland between January 2004 and December 2013. It included adult patients treated with ReveL for HV. The primary exposure was body mass index (BMI) at the time of ReveL. The secondary exposure was gender. The primary outcome was radiological relapse of HV (HV angle [HVA] > 15 degrees [°]) at the last follow-up. Secondary outcomes were improvable patient satisfaction, complication, redo surgery, and optional hardware removal. Logistic regression analysis adjusted for confounders. Results The median weight, height, and BMI were 66.0 (interquartile range [IQR] 57.0–76.0) kilograms (kg), 1.65 (IQR 1.60–1.71) metres (m), and 24.0 (IQR 21.3–27.8) kg/m2. Logistic regression analysis did not show associations of relapse with BMI, independent of age, gender, additional technique, and preoperative HVA (adjusted odds ratio [ORadjusted] = 1.10 [95% (%) confidence interval (CI) = 0.70–1.45], p = 0.675). Relapse was 91% more likely in males (ORadjusted = 1.91 [95% CI = 1.19–3.06], p = 0.007). Improvable satisfaction was 79% more likely in males (ORadjusted = 1.79 [CI = 1.04–3.06], p = 0.035). Hardware removal was 47% less likely in males (ORadjusted = 0.53 [95% CI 0.30–0.94], p = 0.029). Conclusions In this study, obesity was not associated with unsatisfactory outcomes after ReveL for HV. This challenges the previous recommendation that preoperative weight loss may be necessary for a successful surgical treatment outcome. Males may be informed about potentially higher associations with unfavourable outcomes. Due to the risk of selection bias and lack of causality, findings may need to be confirmed with clinical trials.

A high spin polarization of states around the Fermi level, EF, at room temperature has been measured in the past at the interface between a few molecular candidates and the ferromagnetic metal Co. Is this promising property for spintronics limited to these candidates? Previous reports suggested that certain conditions, such as strong ferromagnetism, i.e., a fully occupied spin-up d band of the ferromagnet, or the presence of π bonds on the molecule, i.e., molecular conjugation, needed to be met. What rules govern the presence of this property? We have performed spin-resolved photoemission spectroscopy measurements on a variety of such interfaces. We find that this property is robust against changes to the molecule and ferromagnetic metal's electronic properties, including the aforementioned conditions. This affirms the generality of highly spin-polarized states at the interface between a ferromagnetic metal and a molecule and augurs bright prospects toward integrating these interfaces within organic spintronic devices.

The detection of fluorescence with submolecular resolution enables the exploration of spatially varying photon yields and vibronic properties at the single-molecule level. By placing individual polycyclic aromatic hydrocarbon molecules into the plasmon cavity formed by the tip of a scanning tunneling microscope and a NaCl-covered Ag(111) surface, molecular light emission spectra are obtained that unravel vibrational progression. In addition, light spectra unveil a signature of the molecule even when the tunneling current is injected well separated from the molecular emitter. This signature exhibits a distance-dependent Fano profile that reflects the subtle interplay between inelastic tunneling electrons, the molecular exciton and localized plasmons in at-distance as well as on-molecule fluorescence. The presented findings open the path to luminescence of a different class of molecules than investigated before and contribute to the understanding of single-molecule luminescence at surfaces in a unified picture., Comment: 24 pages, 4 figures

Background Surgical treatment of hallux valgus (HV) is one of the major flagships of orthopedic surgeons. Due to relatively unsatisfactory radiological and clinical outcomes, the search for the best surgical technique and causes for unsatisfactory outcomes continues. The objective was to investigate associations of the number of screws and additional surgical techniques for HV with radiological and clinical outcome after reversed L-shaped osteotomy (ReveL). Methods A retrospective cohort study of adults from a single University Hospital between 2004 and 2013 was performed. The primary exposure was the number of screws (one vs two) used for osseous fixation after ReveL. The secondary exposure was an additional surgical technique for HV (e.g., Akin osteotomy). The primary outcome was a radiological recurrence of HV (HV angle (HVA) > 15°) at last follow-up. The secondary outcomes were limited patient satisfaction, complication, revision surgery, and elective hardware removal. Odds ratio (OR) and 95% confidence interval (CI) were estimated by logistic regression adjusting for confounders. Results The recurrence was 45% less likely with the use of one screw, independent of age, sex, additional technique, and preoperative HVA (odds ratio (ORadjusted) = 0.55 [95% CI 0.30–0.98], p = 0.043). The recurrence was 162% more likely with an additional surgical technique for HV (ORadjusted = 2.62 [1.24–5.52], p = 0.011). Conclusion In ReveL for HV, a single screw (instead of two screws) may be sufficient enough for a similar or even better outcome, which may also reduce costs. Additional surgical procedures for HV may be refrained from if possible. Due to limitations of a retrospective study, results may need validation with clinical trials.

Molecular semiconductors may exhibit antiferromagnetic correlations well below room temperature. Although inorganic antiferromagnetic layers may exchange bias single-molecule magnets, the reciprocal effect of an antiferromagnetic molecular layer magnetically pinning an inorganic ferromagnetic layer through exchange bias has so far not been observed. We report on the magnetic interplay, extending beyond the interface, between a cobalt ferromagnetic layer and a paramagnetic organic manganese phthalocyanine (MnPc) layer. These ferromagnetic/organic interfaces are called spinterfaces because spin polarization arises on them. The robust magnetism of the Co/MnPc spinterface stabilizes antiferromagnetic ordering at room temperature within subsequent MnPc monolayers away from the interface. The inferred magnetic coupling strength is much larger than that found in similar bulk, thin or ultrathin systems. In addition, at lower temperature, the antiferromagnetic MnPc layer induces an exchange bias on the Co film, which is magnetically pinned. These findings create new routes towards designing organic spintronic devices.

We deploy topographical and spectroscopic techniques to show that a strongly spin-polarized interface arises between ferromagnetic cobalt and an amorphous carbon layer. Scanning tunneling microscopy and spectroscopy show how a semiconducting carbon film with a low band gap of about 0.4 eV is formed atop the metallic interface. To understand how the cobalt/carbon interface is formed, we used X-ray photoemission spectroscopy to study the hybridization state of carbon. We find that the semiconducting layer consists mainly of sp(2)-bonded carbon atoms with a sp(2)-to-sp(3) ratio between 1.4 and 1.8. The spin-polarized properties of the cobalt/carbon interface are studied by spin-resolved photoemission spectroscopy. We observe interface states close to the Fermi energy that are not exclusive to cobalt. These electronic states reveal a high degree of spin polarization at room temperature. (C) 2015 Elsevier Ltd. All rights reserved.

Un premier composant de taille moleculaire combinant des proprietes electroniques et photoniques a ete realise. Pour ce faire, un brin unique d’un polymere conducteur (polythiophene) a ete etire entre une surface metallique et la pointe effilee d’un microscope a effet tunnel (STM) fonctionnant a basse temperature (4K). Lorsqu’une tension de l’ordre de 2V est appliquee entre ces deux electrodes, le courant electrique traversant la molecule genere une emission de lumiere. Cette emission est liee a la recombinaison entre un electron injecte dans la molecule depuis la pointe avec un trou injecte depuis l’echantillon. Le mecanisme de luminescence ainsi que la dependance en tension de l’emission montre que la jonction se comporte comme une diode electroluminescente (LED) a une molecule.

Spin-polarized charge transfer between a ferromagnet and a molecule can promote molecular ferromagnetism 1, 2 and hybridized interfacial states3, 4. Observations of high spin-polarization of Fermi level states at room temperature5 designate such interfaces as a very promising candidate toward achieving a highly spin-polarized, nanoscale current source at room temperature, when compared to other solutions such as half-metallic systems and solid-state tunnelling over the past decades. We will discuss three aspects of this research. 1) Does the ferromagnet/molecule interface, also called an organic spinterface, exhibit this high spin-polarization as a generic feature? Spin-polarized photoemission experiments reveal that a high spin-polarization of electronics states at the Fermi level also exist at the simple interface between ferromagnetic cobalt and amorphous carbon6. Furthermore, this effect is general to an array of ferromagnetic and molecular candidates7. 2) Integrating molecules with intrinsic properties (e.g. spin crossover molecules) into a spinterface toward enhanced functionality requires lowering the charge transfer onto the molecule8 while magnetizing it1,2. We propose to achieve this by utilizing interlayer exchange coupling within a more advanced organic spinterface architecture. We present results at room temperature across the fcc Co(001)/Cu/manganese phthalocyanine (MnPc) system9. 3) Finally, we discuss how the Co/MnPc spinterface’s ferromagnetism stabilizes antiferromagnetic ordering at room temperature onto subsequent molecules away from the spinterface, which in turn can exchange bias the Co layer at low temperature10. Consequences include tunnelling anisotropic magnetoresistance across a CoPc tunnel barrier11. This augurs new possibilities to transmit spin information across organic semiconductors using spin flip excitations12.

Whispering gallery modes, well-known for acoustic and optical waves, have been shown recently for electrons in molecules on surfaces. The existence of such waves opens new possibilities for nanoelectronic devices. Here we propose a simple analytical textbook model which allows the main characteristic features of such electronic waves to be understood. The model is illustrated by two- and three-dimensional experimental situations.

International audience; We present a study of the atomic surface diffusion at low temperature of Cr adatoms deposited on Cu(100), Cu(111), and Au(111) surfaces. Time-dependent X-ray magnetic circular dichroism (XMCD), Monte Carlo simulations, and the Kimball−Shortley iterative method are used to evidence a mechanism of quantum tunneling involved in the Cr adatom surface diffusion at temperatures below 40 K. We show that the XMCD line shape is correlated to the atomic configuration of Cr deposited on a metallic surface. A diffusion rate ranging from 0.03 Hz for Cu(100) to 30 Hz for Au(111) at 10 K is reported from the time evolution of the XMCD line shape. A quantum equation of motion for the Cr adatom is derived and solved by using a Kimball−Shortley iterative method. Good agreement between the calculated Bohr periods and the experimental diffusion rates is reported.

We experimentally and theoretically show that the magnetic coupling at room temperature between paramagnetic Mn within manganese phthalocyanine molecules and a Co layer persists when separated by a Cu spacer. The molecule's magnetization amplitude and direction can be tuned by varying the Cu-spacer thickness and evolves according to an interlayer exchange coupling mechanism. Ab initio calculations predict a highly spin-polarized density of states at the Fermi level of this metal-molecule interface, thereby strengthening prospective spintronics applications.

A molecular wire containing an emitting molecular center is controllably suspended between the plasmonic electrodes of a cryogenic scanning tunneling microscope. Passing current through this circuit generates an ultranarrow-line emission at an energy of approximate to 1.5 eV which is assigned to the fluorescence of the molecular center. Control over the linewidth is obtained by progressively detaching the emitting unit from the surface. The recorded spectra also reveal several vibronic peaks of low intensities that can be viewed as a fingerprint of the emitter. Surface plasmons localized at the tip-sample interface are shown to play a major role in both excitation and emission of the molecular excitons.

International audience; Devices studies are often augmented by separately conducted materials science studies to achieve better insight into device operation [1–4]. In one such materials science technique called X-ray absorption spectroscopy (XAS), the energy of soft X-ray photons is tuned so as to drive core level excitations of a specific atomic species within the sample (see Figure 1a). The resulting absorption spectrum yields information on the quantity and charge state of these atoms present, on their chemical environment and their resulting electronic/magnetic properties. When applied using the brilliance of a synchrotron facility, this technique is sensitive to minute populations of atoms, even when buried within a heterostructure. Resolving the properties of these atoms within a device built from this heterostruc-ture is in turn interpreted as providing insight into the device's performance. [2,5] As an important refinement, operando studies [6–12] alter the device's state (e.g., Materials science and device studies have, when implemented jointly as " operando " studies, better revealed the causal link between the properties of the device's materials and its operation, with applications ranging from gas sensing to information and energy technologies. Here, as a further step that maximizes this causal link, the paper focuses on the electronic properties of those atoms that drive a device's operation by using it to read out the materials property. It is demonstrated how this method can reveal insight into the operation of a macroscale, industrial-grade microelectronic device on the atomic level. A magnetic tunnel junction's (MTJ's) current, which involves charge transport across different atomic species and interfaces, is measured while these atoms absorb soft X-rays with synchrotron-grade brilliance. X-ray absorption is found to affect magnetotransport when the photon energy and linear polarization are tuned to excite FeO bonds parallel to the MTJ's interfaces. This explicit link between the device's spintronic performance and these FeO bonds, although predicted, challenges conventional wisdom on their detrimental spintronic impact. The technique opens interdisciplinary possibilities to directly probe the role of different atomic species on device operation, and shall considerably simplify the materials science iterations within device research.

Purpose To investigate the usefulness and conduct validation of a simulated arthroscopy training device to train basic arthroscopy skills. Methods Forty-six participants including 12 novices, 12 intermediates, and 22 experts completed a questionnaire regarding demographics, previous arthroscopic experience, training potential, and statements about the device. Furthermore, participants performed a single task on the arthroscopic training device using the 0° camera and a probe. The task consisted of an attempt to carry a rubber ring across a helix inside a box as fast as possible. Construct validity was evaluated by comparing total task time and portal replacements of the camera and probe between all groups (median values [interquartile range]; Kruskal-Wallis test). Results The median age was 35 (29-44) years. There were 4 female and 42 male participants. A total of 89% of the participants graded the overall training capacity ≥5 (35% graded it as 5, 39% as 6, and 15% as 7), and 83% believed that it is useful to improve any kind of arthroscopy. Ninety-three percent of the participants would recommend the arthroscopic training device to their colleagues. Sixty-one percent of the participants stated that there are certain disadvantages. The median time to complete the task was 108 (58-236) seconds. Novices (259 [123-435] seconds) performed tasks significantly slower than intermediates (169 [67-257] seconds) and experts (75 [49-132] seconds) ( P = .005). Furthermore, portal changes were significantly more common in novices and intermediates than experts ( P = .019). Conclusions High scores in training potential were achieved with this arthroscopy simulator box, and most study participants believed that practice with the arthroscopic training device is useful for any kind of arthroscopy. Construct validity was established since novices, intermediates, and experts in real arthroscopy were discriminated with the arthroscopic training device in terms of time to successful completion of a task. However, 61% of the participants stated that there were certain disadvantages. Clinical Relevance In every training tool using simulation, it is crucial to pass the first steps in the validation cascade. This study provides this step for further evaluation of this arthroscopic training device.

The electroluminescence of a polythiophene wire suspended between a metallic surface and the tip of a scanning tunneling microscope is reported. Under positive sample voltage, the spectral and voltage dependencies of the emitted light are consistent with the fluorescence of the wire junction mediated by localized plasmons. This emission is strongly attenuated for the opposite polarity. Both emission mechanism and polarity dependence are similar to what occurs in organic light emitting diodes (OLED) but at the level of a single molecular wire.

The control of the magnetization of a material with an electric field would make the design and the integration of novel electronic devices possible. This explains the renewed interest in multiferroic materials. Progress in this field is currently hampered by the scarcity of the materials available and the smallness of the magnetoelectric effects. Here we present a proof-of-principle experiment showing that engineering large strains through nanoscale size reduction is an efficient route for increasing magnetoelectric coefficients by orders of magnitude. The archetype magnetoelectric material, Cr2O3, in the form of epitaxial clusters, exhibits an unprecedented 600% change in magnetization magnitude under 1V. Furthermore, a multiferroic phase, with both magnetic and electric spontaneous polarizations, is found in the clusters, while absent in the bulk. We gratefully acknowledge A. Carvalho for SEM observations, J. Arabski for technical assistance during MBE growth, STnano staff for technical support during microfabrication, B. Muller for technical support while setting up DEIMOS beamline, DEIMOS beamline staff for help during synchrotron experiments, and M. Bailleul and V. Da Costa for magnetic and structural characterization measurements. N.N. thanks Région Alsace for financial support.

International audience; Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen p orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature

Structural and electronic properties of oligothiophene nano-wires and rings synthesized on a Au(111) surface are investigated by scanning tunneling microscopy. The spectroscopic data of the linear and cyclic oligomers show remarkable differences which, to a first approximation, can be accounted by considering electronic states confinement to one-dimensional (1D) boxes having respectively fixed and periodic boundary conditions. A more detailed analysis shows that polythiophene must be treated as a ribbon (i.e. having an effective width) rather than a purely 1D structure. A fascinating consequence is that the molecular nano-rings act as whispering gallery mode resonators for electrons, opening the way for new applications in quantum-electronics., Comment: 4 pages with 4 figures, To be published in Physical Review Letters

This work develops the theory of electromagnetic wave propagation through multilayered structures made of anisotropic materials. The proposed method of resolution is based on the Green's dyadic technique. The electromagnetic field scattered by the multilayer is obtained as the solution of a Lippmann-Schwinger equation that can be solved numerically for an arbitrary profile of the anisotropic dielectric tensor. The technique does not rely on any other approximation than the number of points used in the one-dimensional discretization grid so that thin as well as thick layers are tractable on the same footing. Applications to magneto-optical effects in various multilayered structures are discussed from the computed reflected field (Kerr effect).

We have studied the repercussion of the molecular adsorption mechanism on the electronic properties of the interface between model nonmagnetic or magnetic metallic surfaces and metallo-organic phthalocyanines molecules (Pcs). Our intertwined x-ray absorption spectroscopy experiments and computational studies reveal that manganese Pc (MnPc) is physisorbed onto a Cu(001) surface and retains the electronic properties of a free molecule. On the other hand, MnPc is chemisorbed onto Co(001), leading to a dominant direct exchange interaction between the Mn molecular site and the Co substrate. By promoting an interfacial spin-polarized conduction state on the molecule, these interactions reveal an important lever to tailor the spintronic properties of hybrid organic-metallic interfaces.

We use x-ray magnetic circular dichroism to evidence the effect of correlations on the local impurity magnetic moment in an archetypal Kondo system, namely, a dilute Cu:Fe alloy. Applying the sum rules on the Fe ${L}_{2,3}$ absorption edges, the evolution of the spin and orbital moments across the Kondo temperature are determined separately. The spin moment presents a crossover from a nearly temperature-independent regime below the Kondo temperature to a paramagneticlike regime above. Conversely, the weak orbital moment shows a temperature-independent behavior in the whole temperature range, suggesting different Kondo screening temperature scales for the spin and orbital moments.