Flat Bands and Giant Light-Matter Interaction in Hexagonal Boron Nitride

Dispersionless energy bands in k space are a peculiar property gathering increasing attention for the emergence of novel electronic, magnetic, and photonic properties. Here, we explore the impact of electronic flat bands on the light-matter interaction. The van der Waals interaction between the atomic layers of hexagonal boron nitride induces flat bands along specific lines of the Brillouin zone. The macroscopic degeneracy along these lines leads to van Hove singularities with divergent joint density of states, resulting in outstanding optical properties of the excitonic states. For the direct exciton, we report a giant oscillator strength with a longitudinal-transverse splitting of 420 meV, a record value, confirmed by our ab initio calculations. For the fundamental indirect exciton, flat bands result in phonon-assisted processes of exceptional efficiency, that compete with direct absorption in reflectivity, and that make the internal quantum efficiency close to values typical of direct band gap semiconductors.

Genetic characterization of an almond germplasm collection and volatilome profiling of raw and roasted kernels

Almond is appreciated for its nutraceutical value and for the aromatic profile of the kernels. In this work, an almond collection composed of 96 Sicilian accessions complemented with 10 widely cultivated cultivars was phenotyped for the production of volatile organic compounds using a proton-transfer time-of-flight mass spectrometer and genotyped using the Illumina Infinium^®18 K Peach SNP array. The profiling of the aroma was carried out on fresh and roasted kernels enabling the detection of 150 mass peaks. Sixty eight, for the most related with sulfur compounds, furan containing compounds, and aldehydes formed by Strecker degradation, significantly increased during roasting, while the concentration of fifty-four mass peaks, for the most belonging to alcohols and terpenes, significantly decreased. Four hundred and seventy-one robust SNPs were selected and employed for population genetic studies. Structure analysis detected three subpopulations with the Sicilian accessions characterized by a different genetic stratification compared to those collected in Apulia (South Italy) and the International cultivars. The linkage-disequilibrium (LD) decay across the genome was equal to r² = 0.083. Furthermore, a high level of collinearity (r² = 0.96) between almond and peach was registered confirming the high synteny between the two genomes. A preliminary application of a genome-wide association analysis allowed the detection of significant marker-trait associations for 31 fresh and 33 roasted almond mass peaks respectively. An accurate genetic and phenotypic characterization of novel germplasm can represent a valuable tool for the set-up of marker-assisted selection of novel cultivars with an enhanced aromatic profile.

Predictors of progression in patients presenting with minor subcortical stroke

OBJECTIVES

Early neurological worsening is common in minor subcortical strokes (SS) and may lead to a poor outcome. We aimed to describe clinical and imaging features associated with progression.

MATERIAL AND METHODS

Consecutive patients with SS were divided into progressive and non-progressive. Progression was defined as an increase of NIHSS motor score ≥ 1 point within 72 h from onset. Vascular risk factors and imaging features (vascular territory, size and number of slices in which the lesion was visible, the presence of leukoaraiosis) were compared in the two groups. We investigated potential independent determinants of progression using stepwise logistic regression.

RESULTS

Thirty of 94 patients (31.9%) underwent progression. The distribution of vascular risk factors did not differ significantly between the two groups. Increasing number of risk factors was associated with a higher risk of progression (OR 2.2; 95% CI 1.1-4.5). Patients who progressed were more likely to have a lesion ≥ 15 mm in diameter (P = 0.004) or a lesion visible ≥ 3 slices (P = 0.007). After logistic regression stepwise adjustment for all the considered potential determinants, diameter ≥ 15 mm and severe leukoaraiosis proved to be independently associated with neurological worsening (OR = 6.3, 95% CI 2.0-19.6 and OR = 5.9, 95% CI 1.3-25.7, respectively).

CONCLUSION

In a series of consecutive SS, early neurological worsening was associated with a high vascular risk profile, a larger infarct size and the presence of severe leukoaraiosis. Based on the knowledge that extensive microvascular changes are a feature of severe leukoaraiosis, we hypothesize that stroke progression could be promoted through an impaired compensatory flow in the penumbral area.

[Coarctation of the aorta with aortic arch hypoplasia in newborn with partial trisomy 11q associated to 4q interstitial deletion]

This article reports the case of newborn with multiple dimorphisms (microcephaly, hypertelorism, wide and flat nasal bridge, small nose, long philtrum, microretrognathia, malformed and low-set ears, short neck, redundant nuchal skin, genital anomalies), admitted in the hospital after two days from delivery for torpor, poor food and cyanosis. Babies were affected, at color-Doppler echocardiography, by coarctation of the aorta (CoA) with aortic arch hypoplasia. CoA is often associated to genetic and environmental factors that interact frequently. In this study the anamnestic absence of teratogen noxae and the presence of facial and genital anomalies suggest a genetic study to provide appropriate genetic information to parents. G-banding chromosomic analysis revealed a 46, XX der 4t(4;11) karyotype with partial 11q trisomy confirmed with FISH chromosome painting 4;11 and with FISH subtelomere specific 4(p/q)11(p/q). These techniques showed that derivative chromosome 4 was constituted by chromosome 4 with partial deletion in the q35 region and by 11q21 translocation. This rare anomaly is often inherited by an unbalanced segregation of a balanced translocation, present in one of the two parents. In the present study, the father carried a t(4q;11q) balanced translocation. A CGH-array analysis was executed to the child for the breakpoints definition. As 11q trisomy cases reported in literature are still few, this case can contribute to improve our knowledge on the genotype-phenotype correlation in this rare genetic anomaly.

Anomalous angular dependence of the dynamic structure factor near Bragg reflections: graphite

The electron energy-loss function of graphite is studied for momentum transfers q beyond the first Brillouin zone. We find that near Bragg reflections the spectra can change drastically for very small variations in q. The effect is investigated by means of first principle calculations in the random phase approximation and confirmed by inelastic x-ray scattering measurements of the dynamic structure factor S(q, omega). We demonstrate that this effect is governed by crystal local field effects and the stacking of graphite. It is traced back to a strong coupling between excitations at small and large momentum transfers.

Linear plasmon dispersion in single-wall carbon nanotubes and the collective excitation spectrum of graphene

We have measured a strictly linear pi plasmon dispersion along the axis of individualized single-wall carbon nanotubes, which is completely different from plasmon dispersions of graphite or bundled single-wall carbon nanotubes. Comparative ab initio studies on graphene-based systems allow us to reproduce the different dispersions. This suggests that individualized nanotubes provide viable experimental access to collective electronic excitations of graphene, and it validates the use of graphene to understand electronic excitations of carbon nanotubes. In particular, the calculations reveal that local field effects cause a mixing of electronic transitions, including the "Dirac cone," resulting in the observed linear dispersion.

[Accidental ethyl alcohol intoxication in a 30-day-old infant. Clinical findings and neurological follow-up]

Fetus damages due to alcohol abuse in pregnancy, fetal alcohol syndrome (FAS), are widely documented in the literature, whereas short and long term clinical signs of acute alcohol intoxication in newborn babies are poorly described. In our study we describe the case of a 30-day-old newborn baby erroneously fed with 70 mL of white wine in place of the water for milk dilution. The baby clinical features were torpor, tremors, slight fever without metabolic anomalies typical of classic acute alcohol intoxication such as hypoglycemia, hypothermia, metabolic acidosis and coma. Periodical follow-up a 2, 3, 6 and 12 months were performed in order to evaluate neuromotor development using Bayley Scales of Infant Development II, for children between 1 and 42 months old. The results showed normal psychomotor development in our patient.

[Normal urinary levels of telopeptide aminoterminal (NTx) of type I collagen in healthy term newborns and infants in the first month of life]

The Authors have studied urinary aminoterminal telopeptide of type I collagen (NTx), a bone catabolism marker of recent determination, by an enzyme-linked immunoassorbent assay (OSTEOMARK) in 80 urine samples of term healthy infants in the first 3 months of life. Highly significant variations have been compared in the whole period studied (P = 0.000). Levels of NTx increase significantly from 1 to 7 days of life, reaching a plateau that is kept until 45th day and then significantly decrease until 90th day, when, however, they result higher than the values reported in literature concerning older ages. The Authors conclude that even this bone catabolism marker is influenced, in the first week of life, by the particular phenomenology linked to the neonatal adaptation, and that, subsequently, shows a trend strictly linked to the bone turnover modifications throughout the faster stage of the growth.

[Pathology of alcoholism. Experiences and treatment possibilities]

In the present study, the state of art of alcohol-related pathology is described, and the most credited etiological theories reviewed. An effort has been made to apply theory to the daily practice of the health practitioner and the social worker, who operate in the field. Particular emphasis has been given to the experience in the County of Dolo, Italy, where alcohol-related problems have been successfully dealt with by the Alcoholism Unit of the local General Hospital.