Comparison between bioactive sol-gel and melt-derived glasses/glass-ceramics based on the multicomponent SiO2-P2O5-CaO-MgO-Na2O-K2O System

Bioactive sol-gel glasses are attractive biomaterials from both technological and functional viewpoints as they require lower processing temperatures compared to their melt-derived counterparts and exhibit a high specific surface area due to inherent nanoporosity. However, most of these materials are based on relatively simple binary or ternary oxide systems since the synthesis of multicomponent glasses via sol-gel still is a challenge. This work reports for the first time the production and characterization of sol-gel materials based on a six-oxide basic system (SiO2-P2O5-CaO-MgO-Na2O-K2O). It was shown that calcination played a role in inducing the formation of crystalline phases, thus generating glass-ceramic materials. The thermal, microstructural and textural properties, as well as the in vitro bioactivity, of these sol-gel materials were assessed and compared to those of the melt-derived counterpart glass with the same nominal composition. In spite of their glass-ceramic nature, these materials retained an excellent apatite-forming ability, which is key in bone repair applications

A guided walk through the world of mesoporous bioactive glasses (MBGs): Fundamentals, processing, and applications

Bioactive glasses (BGs) are traditionally known to be able to bond to living bone and stimulate bone regeneration. The production of such materials in a mesoporous form allowed scientists to dramatically expand the versatility of oxide-based glass systems as well as their applications in biomedicine. These nanostructured materials, called mesoporous bioactive glasses (MBGs), not only exhibit an ultrafast mineralization rate but can be used as vehicles for the sustained delivery of drugs, which are hosted inside the mesopores, and therapeutic ions, which are released during material dissolution in contact with biological fluids. This review paper summarizes the main strategies for the preparation of MBGs, as well as their properties and applications in the biomedical field, with an emphasis on the methodological aspects and the promise of hierarchical systems with multiscale porosity

Strong enhancement of extremely energetic proton production in central heavy ion collisions at intermediate energy

The energetic proton emission has been investigated as a function of the reaction centrality for the system 58Ni + 58Ni at 30A MeV. Extremely energetic protons (EpNN > 130 MeV) were measured and their multiplicity is found to increase almost quadratically with the number of participant nucleons thus indicating the onset of a mechanism beyond one and two-body dynamics.Comment: 5 pages, 2 figures, submitted to Physical Review Letter

High-Energy Neutrino Astronomy

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature accelerates protons and photons to energies in excess of $10^{20}$ and $10^{13}$ eV, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos.Comment: 9 pages, Latex2e, uses ws-procs975x65standard.sty (included), 4 postscript figures. To appear in Proceedings of Thinking, Observing, and Mining the Universe, Sorrento, Italy, September 200

Detection potential to point-like neutrino sources with the NEMO-km3 telescope

The NEMO Collaboration is conducting an R&D activity towards the construction of a Mediterranean km3 neutrino telescope. In this work, we present the results of Monte Carlo simulation studies on the capability of the proposed NEMO telescope to detect and identify point-like sources of high energy muon neutrinos.Comment: To be published on BCN06 proceedings (Barcelona, July 4-7, 2006

Contemporary presence of dynamical and statistical production of intermediate mass fragments in midperipheral 58^{58}Ni+58^{58}Ni collisions at 30 MeV/nucleon

The $^{58}Ni+^{58}Ni$ reaction at 30 MeV/nucleon has been experimentally investigated at the Superconducting Cyclotron of the INFN Laboratori Nazionali del Sud. In midperipheral collisions the production of massive fragments (4$\le$Z$\le$12), consistent with the statistical fragmentation of the projectile-like residue and the dynamical formation of a neck, joining projectile-like and target-like residues, has been observed. The fragments coming from these different processes differ both in charge distribution and isotopic composition. In particular it is shown that these mechanisms leading to fragment production act contemporarily inside the same event.Comment: 9 pages, minor correction

Size and asymmetry of the reaction entrance channel: influence on the probability of neck production

The results of experiments performed to investigate the Ni+Al, Ni+Ni, Ni+Ag reactions at 30 MeV/nucleon are presented. From the study of dissipative midperipheral collisions, it has been possible to detect events in which Intermediate Mass Fragments (IMF) production takes place. The decay of a quasi-projectile has been identified; its excitation energy leads to a multifragmentation totally described in terms of a statistical disassembly of a thermalized system (T$\simeq$4 MeV, E$^*\simeq$4 MeV/nucleon). Moreover, for the systems Ni+Ni, Ni+Ag, in the same nuclear reaction, a source with velocity intermediate between that of the quasi-projectile and that of the quasi-target, emitting IMF, is observed. The fragments produced by this source are more neutron rich than the average matter of the overall system, and have a charge distribution different, with respect to those statistically emitted from the quasi-projectile. The above features can be considered as a signature of the dynamical origin of the midvelocity emission. The results of this analysis show that IMF can be produced via different mechanisms simultaneously present within the same collision. Moreover, once fixed the characteristics of the quasi-projectile in the three considered reactions (in size, excitation energy and temperature), one observes that the probability of a partner IMF production via dynamical mechanism has a threshold (not present in the Ni+Al case) and increases with the size of the target nucleus.Comment: 16 pages, 7 figures, accepted for publication on Nuclear Physics

Cosmic Neutrinos and the Energy Budget of Galactic and Extragalactic Cosmic Rays

Although kilometer-scale neutrino detectors such as IceCube are discovery instruments, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 10^{20} eV and 10^{13} eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. We will discuss how the cosmic ray connection sets the scale of the anticipated cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube.Comment: 13 pages, Latex2e, 3 postscript figures included. Talk presented at the International Workshop on Energy Budget in the High Energy Universe, Kashiwa, Japan, February 200

Silencing of caveolin-1 in fibroblasts as opposed to epithelial tumor cells results in increased tumor growth rate and chemoresistance in a human pancreatic cancer model

Caveolin‑1 (Cav‑1) expression has been shown to be associated with tumor growth and resistance to chemotherapy in pancreatic cancer. The primary aim of this study was to explore the significance of Cav‑1 expression in pancreatic cancer cells as compared to fibroblasts in relation to cancer cell proliferation and chemoresistance, both in vitro and in vivo, in an immunodeficient mouse model. We also aimed to evaluate the immunohistochemical expression of Cav‑1 in the epithelial and stromal component of pancreatic cancer tissue specimens. The immunohistochemical staining of poorly differentiated tissue sections revealed a strong and weak Cav‑1 expression in the epithelial tumor cells and stromal fibroblasts, respectively. Conversely, the well‑differentiated areas were characterized by a weak epithelial Cav‑1 expression. Cav‑1 downregulation in cancer cells resulted in an increased proliferation in vitro; however, it had no effect on chemoresistance and growth gain in vivo. By contrast, the decreased expression of Cav‑1 in fibroblasts resulted in a growth advantage and the chemoresistance of cancer cells when they were co‑injected into immunodeficient mice to develop mixed fibroblast/cancer cell xenografts. On the whole, the findings of this study suggest that the downregulation of Cav‑1 in fibroblasts is associated with an increased tumor proliferation rate in vivo and chemoresistance. Further studies are warranted to explore whether the targeting of Cav‑1 in the stroma may represent a novel therapeutic approach in pancreatic cancer