Luminescence, vibrational and XANES studies of AlN nanomaterials

Abstract The paper reports comparative studies on synthesized aluminium nitride nanotubes, nanoparticles and commercially available micron-sized AlN powder using different spectroscopic techniques: cathodoluminescence measurements (CL), X-ray absorption near edge spectroscopy (XANES) and Fourier-transform infrared spectroscopy (FTIR). Crucial distinctions in CL spectra are observed for nano- and microsized aluminium nitride powders; systematic shift of the IR absorption maximum has been detected for nanostructured aluminium nitride as compared to commercial samples. Through XANES experiments on Al K-edge structural differences between nano- and bulk AlN are revealed, intensity of features in absorption spectra has been found to be a function of wurtzite and zincblend phases amount in nanostructured samples

Lie point symmetries and first integrals: the Kowalevsky top

We show how the Lie group analysis method can be used in order to obtain first integrals of any system of ordinary differential equations. The method of reduction/increase of order developed by Nucci (J. Math. Phys. 37, 1772-1775 (1996)) is essential. Noether's theorem is neither necessary nor considered. The most striking example we present is the relationship between Lie group analysis and the famous first integral of the Kowalevski top.Comment: 23 page

Nailfold videocapillaroscopy findings in bradykinin-mediated angioedema

Background: Hereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) and acquired angioedema related to angiotensin-converting enzyme (ACE) inhibitors (ACEI-AAE) are types of bradykinin-mediated angioedema without wheals characterized by recurrent swelling episodes. Recent evidence suggests that a state of “vascular preconditioning” predisposes individuals to attacks, although no data are available on possible structural alterations of the vessels. Objective: This study aims to compare the features of nailfold capillaries to highlight possible structural anomalies between patients affected by C1-INH-HAE and controls and between patients with ACEI-AAE and hypertensive controls. Methods: We used nailfold videocapillaroscopy (NVC) to assess the following: apical, internal, and external diameter; loop length; intercapillary distance; and capillary density, distribution, and morphology. Plasma levels of vascular endothelial growth factor (VEGF) A, VEGF-C, angiopoietin (Ang) 1, and Ang2 were also measured. Results: Compared with healthy controls (n=28), C1-INH-HAE patients (n = 34) were characterized by significant structural alterations of the capillaries, such as greater intercapillary distance (216 vs 190 µm), increased apical, internal, and external diameter (28 vs 22 µm; 22 vs 20 µm; and 81 vs 65 µm, respectively), decreased density (4 vs 5 capillaries/mm2), more irregular capillary distribution, and more tortuous morphology. Apical diameter was enlarged in patients with ≥12 attacks per year. In ACEI-AAE patients, NVC showed no alterations with respect to hypertensive controls. NVC performed in 2 C1-INH-HAE patients during attacks showed no changes compared with the remission phase. Conclusions: We detected major structural capillary alterations in C1-INH-HAE patients, thus confirming the involvement of microcirculation in the pathogenesis of angioedema

Deep ice as a geochemical reactor: Insights from iron speciation and mineralogy of dust in the Talos Dome ice core (East Antarctica)

Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that the Talos Dome ice core (TALDICE, Ross Sea sector of East Antarctica) displays evident and progressive signs of post-depositional processes affecting the mineral dust record below 1000g m deep. We apply a suite of established and cutting-edge techniques to investigate the properties of dust in TALDICE, ranging from concentration and grain size to elemental composition and Fe mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, affecting primitive dust features. The expulsion of acidic atmospheric species from ice grains and their concentration in localized environments is likely the main process responsible for englacial reactions. Deep ice can be seen as a "geochemical reactor"capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently help in exploring such transformations

Angiopoietin-2 and the Vascular Endothelial Growth Factor Promote Migration and Invasion in Hepatocellular Carcinoma- and Intrahepatic Cholangiocarcinoma-Derived Spheroids

Aggressive hepatocellular carcinoma (HCC) overexpressing Angiopoietin-2 (ANG-2) (a protein linked with angiogenesis, proliferation, and epithelial–mesenchymal transition (EMT)), shares 95% of up-regulated genes and a similar poor prognosis with the proliferative subgroup of intrahepatic cholangiocarcinoma (iCCA). We analyzed the pro-invasive effect of ANG-2 and its regulator vascular endothelial growth factor (VEGF) on HCC and CCA spheroids to uncover posUsible common ways of response. Four cell lines were used: Hep3B and HepG2 (HCC), HuCC-T1 (iCCA), and EGI-1 (extrahepatic CCA). We treated the spheroids with recombinant human (rh) ANG-2 and/or VEGF and then observed the changes at the baseline, after 24 h, and again after 48 h. Proangiogenic stimuli increased migration and invasion capability in HCC- and iCCA-derived spheroids and were associated with a modification in EMT phenotypic markers (a decrease in E-cadherin and an increase in N-cadherin and Vimentin), especially at the migration front. Inhibitors targeting ANG-2 (Trebananib) and the VEGF (Bevacizumab) effectively blocked the migration ability of spheroids that had been stimulated with rh-ANG-2 and rh-VEGF. Overall, our findings highlight the critical role played by ANG-2 and the VEGF in enhancing the ability of HCC- and iCCA-derived spheroids to migrate and invade, which are key processes in cancer progression

Measurement of boron and carbon fluxes in cosmic rays with the PAMELA experiment

The propagation of cosmic rays inside our galaxy plays a fundamental role in shaping their injection spectra into those observed at Earth. One of the best tools to investigate this issue is the ratio of fluxes for secondary and primary species. The boron-to-carbon (B/C) ratio, in particular, is a sensitive probe to investigate propagation mechanisms. This paper presents new measurements of the absolute fluxes of boron and carbon nuclei, as well as the B/C ratio, from the PAMELA space experiment. The results span the range 0.44 - 129 GeV/n in kinetic energy for data taken in the period July 2006 - March 2008

Trapped proton fluxes at low Earth orbits measured by the PAMELA experiment

We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above > 70 MeV performed by the PAMELA mission at low Earth orbits (350-610 km). Data were analyzed in the frame of the adiabatic theory of charged particle motion in the geomagnetic field. Flux properties were investigated in detail, providing a full characterization of the particle radiation in the South Atlantic Anomaly region, including locations, energy spectra and pitch angle distributions. PAMELA results significantly improve the description of the Earth's radiation environment at low altitudes placing important constraints on the trapping and interaction processes, and can be used to validate current trapped particle radiation models.Comment: 22 pages, 5 figure