Polariton Bose-Einstein condensate from a bound state in the continuum.

Bound states in the continuum (BICs)1-3 are peculiar topological states that, when realized in a planar photonic crystal lattice, are symmetry-protected from radiating in the far field despite lying within the light cone4. These BICs possess an invariant topological charge given by the winding number of the polarization vectors5, similar to vortices in quantum fluids such as superfluid helium and atomic Bose-Einstein condensates. In spite of several reports of optical BICs in patterned dielectric slabs with evidence of lasing, their potential as topologically protected states with theoretically infinite lifetime has not yet been fully exploited. Here we show non-equilibrium Bose-Einstein condensation of polaritons-hybrid light-matter excitations-occurring in a BIC thanks to its peculiar non-radiative nature, which favours polariton accumulation. The combination of the ultralong BIC lifetime and the tight confinement of the waveguide geometry enables the achievement of an extremely low threshold density for condensation, which is reached not in the dispersion minimum but at a saddle point in reciprocal space. By bridging bosonic condensation and symmetry-protected radiation eigenmodes, we reveal ways of imparting topological properties onto macroscopic quantum states with unexplored dispersion features. Such an observation may open a route towards energy-efficient polariton condensation in cost-effective integrated devices, ultimately suited for the development of hybrid light-matter optical circuits.

Prognostic factors in epilepsy with eyelid myoclonia (Jeavons syndrome).

PURPOSE: To describe the prognostic factors of drug resistance in 40 patients with epilepsy with eyelid myoclonia or Jeavons syndrome. METHOD: Retrospective analysis from two French tertiary centers. RESULTS: Forty patients were enrolled (31 females and 9 males; mean age at epilepsy onset: 6.2±3.4 years [range: 1-15 years]). Half of the patients (20/40) achieved at least a one-year remission from all seizure types. In the responders, seizure freedom was achieved after a mean 13.85±13.43 years from the onset of epilepsy (range: 1-44). The presence of intellectual disability and an earlier onset of the disease (≤5 years) were the most powerful predictors of poor seizure control (P=0.003 and P=0.005, respectively). When considering the age of onset, patients with early-onset seizures (≤5 years) presented more frequently with intellectual disabilities, psychiatric comorbidities, absences, and a major risk of refractoriness (70% versus 30%, P=0.01) than patients with onset after 5 years. At the last follow-up, 15 patients (37.5%) were taking a single drug, 16 (40%) were taking two, and seven (17.5%) were taking more than two. The most frequent drugs were valproate (23/40, 57.7%), followed by levetiracetam (16/40, 40%), and lamotrigine (14/40, 35%). CONCLUSION: Patients with Jeavons syndrome present a high rate of pharmaco-resistance with the need for long-term treatment. Early onset of epilepsy and the presence of intellectual disability appeared to be the most relevant predictors of poor seizure control, suggesting the use of genetic tests to individualize specific etiologies and perhaps adapt the therapeutic strategy.

Lacosamide in monotherapy in BTRE (brain tumor-related epilepsy): results from an Italian multicenter retrospective study.

PURPOSE: Lacosamide (LCM) is a third-generation anti-seizure medication (ASM) approved for focal onset epilepsy in patients aged ≥ 4.378 Previous studies have reported an efficacy of LCM as add-on treatment in brain tumor-related epilepsy (BTRE). To date, there are no studies in the literature focusing on lacosamide used in monotherapy to treat BTRE. In our retrospective study we investigated efficacy and tolerability of LCM in monotherapy in a multicenter national cohort of primary brain tumor patients. METHODS: We collected from 12 Italian Centers 132 patients with primary brain tumors who were treated with LCM in monotherapy. For each patient we evaluated seizure freedom at 3 and 6 months (primary endpoints), side effects and drop-out rate (secondary endpoints). RESULTS: Overall, LCM led to seizure freedom in 64.4% of patients at 3 months and 55% at 6 months. Patients who used two or more ASMs before LCM had a worse seizure control than patients in monotherapy with LCM as first choice. In 14 patients, we observed seizure control despite tumor progression on magnetic resonance (MRI). Multivariate analysis showed that gross-total resection at diagnosis was significantly associated with higher seizure freedom rate at 6 months. Side effects were mainly mild (grade 1-2 according to CTCAE classification) and drop-out rate was low (1.5%). Main side effects were dizziness and somnolence. CONCLUSIONS: This is the first study showing a good efficacy and tolerability of LCM when used in monotherapy in BTRE. Further prospective studies are needed to confirm these preliminary data, investigating also quality of life and neurocognitive functions.

Enhancement of Parametric Effects in Polariton Waveguides Induced by Dipolar Interactions.

Exciton-polaritons are hybrid light-matter excitations arising from the nonperturbative coupling of a photonic mode and an excitonic resonance. Behaving as interacting photons, they show optical third-order nonlinearities providing effects such as optical parametric oscillation or amplification. It has been suggested that polariton-polariton interactions can be greatly enhanced by inducing aligned electric dipoles in their excitonic part. However, direct evidence of a true particle-particle interaction, such as superfluidity or parametric scattering, is still missing. In this Letter, we demonstrate that dipolar interactions can be used to enhance parametric effects such as self-phase modulation in waveguide polaritons. By quantifying these optical nonlinearities, we provide a reliable experimental measurement of the direct dipolar enhancement of polariton-polariton interactions.

Tests of a novel imaging algorithm to localize hidden objects or cavities with muon radiography.

A novel algorithm developed within muon radiography to localize objects or cavities hidden inside large material volumes was recently proposed by some of the authors (Bonechi et al. 2015 J. Instrum. 10, P02003 (doi:10.1088/1748-0221/10/02/P02003)). The algorithm, based on muon back projection, helps to estimate the three-dimensional position and the transverse extension of detected objects without the need for measurements from different points of view, which would be required to make a triangulation. This algorithm can now be tested owing to the availability of real data collected both in laboratory tests and from real-world measurements. The methodology and some test results are presented in this paper.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

SNCA 3'UTR genetic variants in patients with Parkinson's disease and REM sleep behavior disorder.

REM sleep behavior disorder (RBD) is an early marker of Parkinson's disease (PD); however, it is still unclear which patients with RBD will eventually develop PD. Single nucleotide polymorphisms (SNPs) in the 3'untranslated region (3'UTR) of alpha-synuclein (SNCA) have been associated with PD, but at present, no data is available about RBD. The 3'UTR hosts regulatory regions involved in gene expression control, such as microRNA binding sites. The aim of this study was to determine RBD specific genetic features associated to an increased risk of progression to PD, by sequencing of the SNCA-3'UTR in patients with "idiopathic" RBD (iRBD) and in patients with PD. We recruited 113 consecutive patients with a diagnosis of iRBD (56 patients) or PD (with or without RBD, 57 patients). Sequencing of SNCA-3'UTR was performed on genomic DNA extracted from peripheral blood samples. Bioinformatic analyses were carried out to predict the potential effect of the identified genetic variants on microRNA binding. We found three SNCA-3'UTR SNPs (rs356165, rs3857053, rs1045722) to be more frequent in PD patients than in iRBD patients (p = 0.014, 0.008, and 0.008, respectively). Four new or previously reported but not annotated specific genetic variants (KP876057, KP876056, NM_000345.3:c*860T>A, NM_000345.3:c*2320A>T) have been observed in the RBD population. The in silico approach highlighted that these variants could affect microRNA-mediated gene expression control. Our data show specific SNPs in the SNCA-3'UTR that may bear a risk for RBD to be associated with PD. Moreover, new genetic variants were identified in patients with iRBD.

Cationic liposomes formulated with DMPC and a gemini surfactant traverse the cell membrane without causing a significant bio-damage.

Cationic liposomes have been intensively studied both in basic and applied research because of their promising potential as non-viral molecular vehicles. This work was aimed to gain more information on the interactions between the plasmamembrane and liposomes formed by a natural phospholipid and a cationic surfactant of the gemini family. The present work was conducted with the synergistic use of diverse experimental approaches: electro-rotation measurements, atomic force microscopy, ζ-potential measurements, laser scanning confocal microscopy and biomolecular/cellular techniques. Electro-rotation measurements pointed out that the interaction of cationic liposomes with the cell membrane alters significantly its dielectric and geometric parameters. This alteration, being accompanied by significant changes of the membrane surface roughness as measured by atomic force microscopy, suggests that the interaction with the liposomes causes locally substantial modifications to the structure and morphology of the cell membrane. However, the results of electrophoretic mobility (ζ-potential) experiments show that upon the interaction the electric charge exposed on the cell surface does not vary significantly, pointing out that the simple adhesion on the cell surface of the cationic liposomes or their fusion with the membrane is to be ruled out. As a matter of fact, confocal microscopy images directly demonstrated the penetration of the liposomes inside the cell and their diffusion within the cytoplasm. Electro-rotation experiments performed in the presence of endocytosis inhibitors suggest that the internalization is mediated by, at least, one specific pathway. Noteworthy, the liposome uptake by the cell does not cause a significant biological damage.

Pure optical nano-writing on light- switchable spiropyrans/merocyanine thin film.

We report optical writing at the nanometer scale of spin coated PMMA-spiropyran films. By using a near-field optical microscope, pure optical nano-writing with a resolution of 160 nm and writing speed of 0.4 µm/s was achieved. Simultaneous topographic and optical writing was also obtained by simply coupling to the near-field few more mW of laser power. Due to the fast optical response of the spiropyran molecule, nano-lithography on PMMA-spyropyran thin films appears to be very attractive for future photonics applications.

Ultrafast Control and Rabi Oscillations of Polaritons.

We report the experimental observation and control of space and time-resolved light-matter Rabi oscillations in a microcavity. Our setup precision and the system coherence are so high that coherent control can be implemented with amplification or switching off of the oscillations and even erasing of the polariton density by optical pulses. The data are reproduced by a quantum optical model with excellent accuracy, providing new insights on the key components that rule the polariton dynamics.

The contribution of assessing cognitive impairment in radiologically-isolated syndrome (RIS): a single case report follow-up study.

Radiologically-isolated syndrome (RIS) is a recently-defined entity, described as the incidental discovery of lesions suggestive of multiple sclerosis (MS) on brain magnetic resonance imaging (MRI) scans demonstrating dissemination in space (DIS) without symptom expression and with a normal neurological examination. Recent studies demonstrate that RIS patients present similar features of cognitive impairment as MS patients. We describe a case of a RIS patient in whom investigating cognitive functions was a useful tool for diagnostic and therapeutic decisions.

Live cell cytoplasm staining and selective labeling of intracellular proteins by non-toxic cell-permeant thiophene fluorophores.

A structurally correlated series of cell-permeant thiophene fluorophores, characterized by intense green or red fluorescence inside live mouse embryonic fibroblasts, was developed. The fluorophores displayed rapid internalization, excellent retention inside the cells, and high optical stability in the cytosolic environment and did not alter cell viability and reproducibility. Depending on the molecular structure, they experienced distinct fate inside the cells: from bright and lasting staining of the cytoplasm to selective tagging of a small set of globular proteins.

The antimony-group 11 chemical bond: dissociation energies of the diatomic molecules CuSb, AgSb, and AuSb.

The intermetallic molecules CuSb, AgSb, and AuSb were identified in the effusive molecular beam produced at high temperature under equilibrium conditions in a double-cell-like Knudsen source. Several gaseous equilibria involving these species were studied by mass spectrometry as a function of temperature in the overall range 1349-1822 K, and the strength of the chemical bond formed between antimony and the group 11 metals was for the first time measured deriving the following thermochemical dissociation energies (D°(0), kJ/mol): 186.7 ± 5.1 (CuSb), 156.3 ± 4.9 (AgSb), 241.3 ± 5.8 (AuSb). The three species were also investigated computationally at the coupled cluster level with single, double, and noniterative quasiperturbative triple excitations (CCSD(T)). The spectroscopic parameters were calculated from the potential energy curves and the dissociation energies were evaluated at the Complete Basis Set limit, resulting in an overall good agreement with experimental values. An approximate evaluation of the spin-orbit effect was also performed. CCSD(T) calculations were further extended to the corresponding group 11 arsenide species which are here studied for the first time and the following dissociation energies (D°(0), kJ/mol): 190 ± 10 (CuAs), 151 ± 10 (AgAs), 240 ± 15 (AuAs) are proposed. Taking advantage of the new experimental and computational information here presented, the bond energy trends along group 11 and 4th and 5th periods of the periodic table were analyzed and the bond energies of the diatomic species CuBi and AuBi, yet experimentally unobserved, were predicted on an empirical basis.

Transition from nonresonant to resonant random lasers by the geometrical confinement of disorder.

We report on a transition in random lasers that is induced by the geometrical confinement of the emitting material. Different dye doped paper devices with controlled geometry are fabricated by soft lithography and show two distinguished behaviors in the stimulated emission: in the absence of boundary constraints, the energy threshold decreases for larger laser volumes showing the typical trend of diffusive nonresonant random lasers, while when the same material is lithographed into channels, the walls act as cavity and the resonant behavior typical of standard lasers is observed. The experimental results are consistent with the general theories of random and standard lasers and a clear phase diagram of the transition is reported.

The uncertain bond energy of the NaAu molecule: experimental redetermination and coupled cluster calculations.

The dissociation energy of the intermetallic molecule NaAu, for which two largely at variance experimental values are available in the literature, has been redetermined by the Knudsen effusion mass spectrometry method. The molecule has been produced in the vapor phase by a specially designed experimental setting inspired by the double oven technique. The equilibrium of dissociation to atoms as well as the exchange equilibrium with the gold dimer were monitored mass-spectrometrically over about a 600 K temperature range. The third-law analysis of the equilibrium data provides the dissociation energy D0° (NaAu, g) = 245.3 ± 6.8 kJ/mol, corresponding to a formation enthalpy at 298 K of 228.3 ± 7.5 kJ/mol. The NaAu species was also studied computationally at the CCSD(T) level with basis sets of increasing zeta quality thus allowing to evaluate the molecular parameters and the dissociation energy at the complete basis set limit.

Role of a corrugated Dion-Jacobson 2D perovskite as an additive in 3D MAPbBr3 perovskite-based light emitting diodes.

Metal halide perovskites represent an intriguing class of materials, and a very promising approach to tune the properties of optoelectronic devices and improve their performance involves the implementation of architectures based on mixed 3D and 2D perovskites. In this work, we investigated the use of a corrugated 2D Dion-Jacobson perovskite as an additive to a classical 3D MAPbBr3 perovskite for applications in light-emitting diodes. Taking advantage of the properties of this emerging class of materials, we studied the effect of a 2D 2-(dimethylamino)ethylamine (DMEN)-based perovskite on the morphological, photophysical, and optoelectronic properties of 3D perovskite thin films. We used α-DMEN perovskite both in a mixture with MAPbBr3 creating mixed 2D/3D phases and as a passivating thin layer deposited on the top of a 3D perovskite polycrystalline film. We observed a beneficial modulation of the thin film surface, a blue shift in the emission spectrum, and enhanced device performance.

Control and ultrafast dynamics of a two-fluid polariton switch.

We investigate the cross interactions in a two-component polariton quantum fluid coherently driven by two independent pumping lasers tuned at different energies and momenta. We show that both the hysteresis cycles and the on-off threshold of one polariton signal can be entirely controlled by a second polariton fluid. Furthermore, we study the ultrafast switching dynamics of a driven polariton state, demonstrating the ability to control the polariton population with an external laser pulse, in less than a few picoseconds.

Study of the fundamental units of novel semiconductor materials: structures, energetics, and thermodynamics of the Ge-Sn and Si-Ge-Sn molecular systems.

The binary Ge(y)Sn(z) and ternary Si(x)Ge(y)Sn(z) molecular systems containing up to five atoms were investigated by means of density functional theory and coupled cluster calculations. The minimum energy structures were calculated and higher energy isomers are also proposed. The atomization energies of the ground state isomers were calculated by the CCSD(T) method with correlation consistent basis sets up to quadruple-ζ quality. The resulting values were extrapolated to the complete basis set limit and corrected by an approximate evaluation of the spin-orbit effect. Energetic properties such as binding, fragmentation and mixing energies, and HOMO-LUMO gap were analyzed as a function of the cluster size and composition. By using empirically adjusted atomization energies and DFT harmonic frequencies, the thermal functions were evaluated, and a thermodynamic database for the Si-Ge-Sn system was built, containing data for 55 gaseous species. On this basis, equilibrium calculations were performed in the temperature interval 1600-2200 K aimed at predicting the composition of the gas phase under various conditions. The results presented here can be of interest to improve the microscopic knowledge of Ge-Sn and Si-Ge-Sn materials, which are among the most promising candidates for advanced applications in the field of electronic and optoelectronic components, both as epitaxially grown layers and as nanocrystal quantum dots.

Experimental and computational investigation of the group 11-group 2 diatomic molecules: first determination of the AuSr and AuBa bond energies and thermodynamic stability of the copper- and silver-alkaline earth species.

The dissociation energies of the intermetallic molecules AuSr and AuBa were for the first time determined by the Knudsen effusion mass spectrometry method. The two species were produced in the vapor phase equilibrated with apt mixtures of the constituent elements, and the dissociation equilibria were monitored mass-spectrometrically in the temperature range 1406-1971 K (AuSr) and 1505-1971 K (AuBa). The third-law analysis of the equilibrium data gives the following dissociation energies (D(0)°, in kJ/mol): 244.4 ± 4.8 (AuSr) and 273.3 ± 6.3 (AuBa), so completing the series of D(0)°s for the AuAE (AE = group 2 element) diatomics. The AuAE species were also studied computationally at the coupled cluster including single, double and perturbative triple excitation [CCSD(T)] level with basis sets of increasing zeta quality, and various complete basis set limit extrapolations were performed to calculate the dissociation energies. Furthermore, the entire series of the heteronuclear diatomic species formed from one group 11 (Cu, Ag) and one group 2 (Be, Mg, Ca, Sr, Ba) metal was studied by DFT with the hybrid meta-GGA TPSSh functional and the def2-QZVPP basis set, selected after screening a number of functional-basis set combinations using the AuAE species as benchmark. Dissociation energies, internuclear distances, vibrational frequencies, and anharmonic constants were determined for the CuAE and AgAE species and their thermal functions evaluated therefrom. On this basis, a thermodynamic evaluation of the formation of these species was carried out under various conditions.

High-efficiency red phosphorescent electroluminescence devices based on mixed p/n host matrices.

In this Letter, we demonstrate a way to control the charge carrier transport mechanisms in phosphorescent organic light-emitting devices based on the mixing of two p and n host materials in the emissive layer (EML). The matrices have been selected in order to fulfill the requirements of the energy level mismatch with the transporting and emitting materials. By using the mixed-host approach in combination with a phosphorescent red emitter, namely (1-phenylisoquinoline) iridium (III) [Ir(piq)(3)], maximum external and power efficiencies of 14.3% and 10 lm/W, respectively, have been achieved, with an average external efficiency value of 12% in the luminance range 100-10,000 cd/m(2).

Nanowalled polymer microtubes fabricated by using strained semiconductor templates.

Herein we describe the realization of nanowalled polymeric microtubes through a novel and versatile approach combining the layer-by-layer (LbL) deposition technique, the self-rolling of hybrid polymer/semiconductor microtubes and the subsequent removal of the semiconductor template. The realized channels were characterized in detail using scanning electron and atomic force microscopes. Additionally, we report on the incorporation of a dye molecule within the nanowalls of such microtubes, demonstrating a distribution of the fluorescence signal throughout the whole channel volume. This approach offers the possibility to tailor the properties of micro/nanotubes in terms of size, wall thickness and composition, thus enabling their employment for several applications.