Oxidation mechanism in metal nanoclusters: Zn nanoclusters to ZnO hollow nanoclusters

Zn nanoclusters (NCs) are deposited by Low-energy cluster beam deposition technique. The mechanism of oxidation is studied by analysing their compositional and morphological evolution over a long span of time (three years) due to exposure to ambient atmosphere. It is concluded that the mechanism proceeds in two steps. In the first step, the shell of ZnO forms over Zn NCs rapidly up to certain limiting thickness: with in few days -- depending upon the size -- Zn NCs are converted to Zn-ZnO (core-shell), Zn-void-ZnO, or hollow ZnO type NCs. Bigger than ~15 nm become Zn-ZnO (core-shell) type: among them, NCs above ~25 nm could able to retain their initial geometrical shapes (namely triangular, hexagonal, rectangular and rhombohedral), but ~25 to 15 nm size NCs become irregular or distorted geometrical shapes. NCs between ~15 to 5 nm become Zn-void-ZnO type, and smaller than ~5 nm become ZnO hollow sphere type i.e. ZnO hollow NCs. In the second step, all Zn-void-ZnO and Zn-ZnO (core-shell) structures are converted to hollow ZnO NCs in a slow and gradual process, and the mechanism of conversion proceeds through expansion in size by incorporating ZnO monomers inside the shell. The observed oxidation behaviour of NCs is compared with theory of Cabrera - Mott on low-temperature oxidation of metal.Comment: 9 pages, 8 figure

Targeted therapy for high-grade glioma with the TGF-β2 inhibitor trabedersen: results of a randomized and controlled phase IIb study

This randomized, open-label, active-controlled, dose-finding phase IIb study evaluated the efficacy and safety of trabedersen (AP 12009) administered intratumorally by convection-enhanced delivery compared with standard chemotherapy in patients with recurrent/refractory high-grade glioma. One hundred and forty-five patients with central reference histopathology of recurrent/refractory glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA) were randomly assigned to receive trabedersen at doses of 10 or 80 µM or standard chemotherapy (temozolomide or procarbazine/lomustine/vincristine). Primary endpoint was 6-month tumor control rate, and secondary endpoints included response at further timepoints, survival, and safety. Six-month tumor control rates were not significantly different in the entire study population (AA and GBM). Prespecified AA subgroup analysis showed a significant benefit regarding the 14-month tumor control rate for 10 µM trabedersen vs chemotherapy (p= .0032). The 2-year survival rate had a trend for superiority for 10 µM trabedersen vs chemotherapy (p = .10). Median survival for 10 µM trabedersen was 39.1 months compared with 35.2 months for 80 µM trabedersen and 21.7 months for chemotherapy (not significant). In GBM patients, response and survival results were comparable among the 3 arms. Exploratory analysis on GBM patients aged ≤55 years with Karnofsky performance status >80% at baseline indicated a 3-fold survival at 2 and 3 years for 10 µM trabedersen vs chemotherapy. The frequency of patients with related or possibly drug-related adverse events was higher with standard chemotherapy (64%) than with 80 µM trabedersen (43%) and 10 µM trabedersen (27%). Superior efficacy and safety for 10 µM trabedersen over 80 µM trabedersen and chemotherapy and positive risk–benefit assessment suggest it as the optimal dose for further clinical development in high-grade glioma

De Sitter vacua from N=2 gauged supergravity

Typical de Sitter (dS) vacua of gauged supergravity correspond to saddle points of the potential and often the unstable mode runs into a singularity. We explore the possibility to obtain dS points where the unstable mode goes on both sides into a supersymmetric smooth vacuum. Within N=2 gauged supergravity coupled to the universal hypermultiplet, we have found a potential which has two supersymmetric minima (one of them can be flat) and these are connected by a de Sitter saddle point. In order to obtain this potential by an Abelian gauging, it was important to include the recently proposed quantum corrections to the universal hypermultiplet sector. Our results apply to four as well as five dimensional gauged supergravity theories.Comment: 25 pages, 1 figure, add refs and corrected typo

Anatomical considerations and emerging strategies for reducing new onset conduction disturbances in percutaneous structural heart disease interventions

Transcatheter procedures offer an alternative to cardiac surgery in select patients with structural heart disease (SHD). Unfortunately, inadvertent disruption of electrical pathways and subsequent development of new onset conduction disturbances can occur in up to 5–70% of percutaneous interventions, result in pacemaker implantation, and confer a worse prognosis. The physical proximity between the conduction system (atrioventricular node, bundle of His, and bundle branches) and the site of percutaneous repair is increasingly recognized as a key factor influencing new onset conduction disturbance development in procedures located near the conduction system. This review covers the incidence, clinical significance, and mechanisms of new onset conduction disturbances and discusses current and emerging strategies to address this complication in these populations

Small-scale cosmic ray anisotropy observed by the GRAPES-3 experiment at TeV energies

GRAPES-3 is a mid-altitude (2200 m) and near equatorial ($11.4^{\circ}$ North) air shower array, overlapping in its field of view for cosmic ray observations with experiments that are located in Northern and Southern hemispheres. We analyze a sample of $3.7\times10^9$ cosmic ray events collected by the GRAPES-3 experiment between 1 January 2013 and 31 December 2016 with a median energy of $\sim16$ TeV for study of small-scale ($<60^{\circ}$) angular scale anisotropies. We observed two structures labeled as A and B, deviate from the expected isotropic distribution of cosmic rays in a statistically significant manner. Structure `A' spans $50^{\circ}$ to $80^{\circ}$ in the right ascension and $-15^{\circ}$ to $30^{\circ}$ in the declination coordinate. The relative excess observed in the structure A is at the level of $(6.5\pm1.3)\times10^{-4}$ with a statistical significance of 6.8 standard deviations. Structure `B' is observed in the right ascension range of $110^{\circ}$ to $140^{\circ}$. The relative excess observed in this region is at the level of $(4.9\pm1.4)\times10^{-4}$ with a statistical significance of 4.7 standard deviations. These structures are consistent with those reported by Milagro, ARGO-YBJ, and HAWC. These observations could provide a better understanding of the cosmic ray sources, propagation and the magnetic structures in our Galaxy

Centrality Dependence of Neutral Pion Production in 158 A GeV Pb + Pb Collisions

The production of neutral pions in 158AGeV Pb+Pb collisions has been studied in the WA98 experiment at the CERN SPS. Transverse momentum spectra are studied for the range 0.3 GeV/c < mT-m0 < 4.0 GeV/c. The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30 participating nucleons which is most naturally explained by assuming an equilibrated system.Comment: 5 pages, Latex, including 3 eps figures, submitted to Phys.Rev.Lett; updated pQCD comparison due to new input from the author, updated references, corrected plotting error in figure

Resonant Structure of τ→3ππ0ντ\tau\to 3\pi\pi^{0}\nu_{\tau} and τ→ωπντ\tau\to \omega\pi\nu_{\tau} Decays

The resonant structure of the four pion final state in the decay $\tau \to 3\pi\pi^0\nu_\tau$ is analyzed using 4.27 million $\tau^+\tau^-$ pairs collected by the CLEO II experiment. We search for second class currents in the decay $\tau \to \omega\pi\nu_\tau$ using spin-parity analysis and establish an upper limit on the non-vector current contribution. The mass and width of the $\rho'$ resonance are extracted from a fit to the $\tau \to \omega\pi\nu_\tau$ spectral function. A partial wave analysis of the resonant structure of the $\tau \to 3\pi\pi^0\nu_\tau$ decay is performed; the spectral decomposition of the four pion system is dominated by the $\omega\pi$ and $a_1 \pi$ final states.Comment: 34 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Search for a Scalar Bottom Quark with Mass 3.5-4.5 GeV/c2c^{2}

We report on a search for a supersymmetric $\tilde{B}$ meson with mass between 3.5 and 4.5 GeV/$c^2$ using 4.52 ${\rm fb}^{-1}$ of integrated luminosity produced at $\sqrt{s}=10.52$ GeV, just below the $e^+e^-\to B\bar{B}$ threshold, and collected with the CLEO detector. We find no evidence for a light scalar bottom quark.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN