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The design and production of innovative materials based on nanocrystalline sp - and sp -coordinated carbons is presently a focus of the scientific community. We present a review of the nanostructures obtained in our labs using a series of synthetic routes, which make use of chemical vapor deposition (CVD) techniques for the selective production of non-planar graphitic nanostructures, nanocrystalline diamonds, and hybrid two-phase nanostructures. [ABSTRACT FROM AUTHOR]

Detonation nanodiamond (DND) is characterized by very attractive properties, as the unusual values of surface energy and confinement effects. The objective of our research is to define methodologies for the tailored shaping of DND aggregates and the control of the architecture in DND-based nanocomposites. Self-standing microstructures with different shapes have been obtained by using different portions of the DND colloidal suspensions. Innovative composites based on DND inserted in PANI matrices are prepared by adding nanodiamond during chemical oxidative polymerization of ANI. The insertion of the nanosized fillers enables to obtain architectures with a high-degree of control over the polymer crystallinity. [ABSTRACT FROM AUTHOR]

Background: The treatment of acute cholecystitis in the elderly is still a subject of debate, particularly with reference to the timing of surgery and the role of laparoscopy.Patients: From January 1994 to June 2002 we observed 27 patients aged over 70 years with acute calcolous cholecystitis. The patients were submitted to ultrasonographic percutaneous cholecystostomy within 12 h of the acute attack. For two patients (7.4%) at high operative risk, we chose a conservative treatment. Twenty-five patients (92.6%) were submitted, in 15 cases (60%) within 5 days and in 10 patients (40%) within 8 days, to a laparoscopic cholecystectomy. Statistical significance was accepted when the value of p was less than 0.05.Results: Ultrasonographic percutaneous cholecystostomy was performed successfully in all patients, without major morbidity or mortality, and complete resolution of clinical symptoms was obtained within 48 h. The conversion rate of laparoscopy was 20% (13.3% in patients submitted to surgery within 5 days and 30% in the group submitted within 8 days--p > 0.05). The postoperative morbidity rate was 24%; it was higher (40% versus 15%) in patients converted to laparotomy (p > 0.05); mortality was 4%. The period of hospitalization was 11 days in patients operated laparoscopically and 21 days in those converted to open cholecystectomy (p < 0.001).Conclusions: The more rational treatment of acute calcolous cholecystitis in elderly patients is represented by ultrasonographic percutaneous cholecystostomy followed, within 5 days, by laparoscopic cholecystectomy using an abdominal insufflation maximum to 12 mmHg and a limited 10-15 degrees head-up tilt. [ABSTRACT FROM AUTHOR]

The alpha-decay ofSm has been investigated in the Gran Sasso Underground Laboratory by using plates of CR-39 as detector in close contact with thin layers of natural samarium. The half-life of the decay process, measured for the first time under conditions free from cosmic-ray neutrons, is found to be T =(1.23±0.04)·10y. The present result is compared with the half-life values reported in the literature and interpreted on the basis of a simple formalism for alpha-decay developed in the framework of penetration through a Coulomb-plus-centrifugal potential barrier. [ABSTRACT FROM AUTHOR]

A general fit has been performed to the data on most probable fragment total kinetic-energy release in fission, 〈 E 〉, for values of parameter Z / A , of the fissioning nucleus ranging between 42 and 2150. The data result to be rather well fitted to an expression of the type 〈 E 〉= Z /( aA + bA + cA ) with a=9.39, b=−58.6 and c=226 (all values expressed in MeV). For light fisssioning systems the present result provides a trend of 〈 E 〉 which gives vanishing 〈 E 〉-values for Z approaching zero, as predicted in liquid-drop model calculations. [ABSTRACT FROM AUTHOR]

The yields of the photofission reactions induced inBi andPb by quasi-monochromatic photon beam of 226 MeV maximum energy have been measured by using makrofol plates as solid-state detector of fission tracks and found to be (1.1±0.4) mb and (0.8±0.4) mb, respectively. The measured yields are compared with data of fission induced in the same targets by different photon beams. [ABSTRACT FROM AUTHOR]

Nuclear emulsion plates Ilford-K0 exposed to (1.0÷5.5) GeV bremsstrahlung beams in order to study photoinduced break-up of Ar, Br nuclei have been processed to produce visible fission tracks for track analysis with optical microscope. Track-length distributions, angular distributions and angular correlations of the produced fragments obtained at six end-point bremsstrahlung energies are presented and discussed. The analysis of the data shows that the recorded events are produced by two different reaction mechanisms, namely fission and fragmentation. The absolute mean cross-sections per photon for fragmentation, binary and ternay fission of Ag, Br targets in the energy range investigated have been measured. Absolute mean cross-sections per photon and corresponding fissilities have been evaluated for binary fission of Ag and Br and compared with literature data. [ABSTRACT FROM AUTHOR]

An analysis of the photofission reactions in the quasi-deuteron energy range of photonuclear absorption (∼30-140 MeV) has been performed forBi andU nuclei. Experimental cross section data available in the literature have been compared with calculated values obtained from a model in which the incoming photon is assumed to be absorbed by a neutron-proton pair (Levinger's quasi-deuteron photoabsorption), followed by a mechanism of evaporation-fission competition for the excited residual nuclei. The model has been shown to reproduce the main experimental features ofBi andU photofission cross section, although unexplained differences still remain in the case ofU-fission by 30- 50 MeV incident photons. [ABSTRACT FROM AUTHOR]