665 research outputs found
Synthetic routes toward MOF nanomorphologies.
As metal–organic frameworks (MOFs) are coming of age, their structural diversity, exceptional porosity and inherent functionality need to be transferred into useful applications. Fashioning MOFs into various shapes and at the same time controlling their size constitute an essential step toward MOF-based devices. Moreover, downsizing MOFs to the nanoscale triggers a whole new set of properties distinguishing nanoMOFs from their bulk counterparts. Therefore, dimensionality-controlled miniaturization of MOFs enables the customised use of nanoMOFs for specific applications where suitable size and shape are key prerequisites. In this feature article we survey the burgeoning field of nanoscale MOF synthesis, ranging from classical protocols such as microemulsion synthesis all the way to microfluidic-based techniques and template-directed epitaxial growth schemes. Along these lines, we will fathom the feasibility of rationally designing specific MOF nanomorphologies—zero-, one- and two-dimensional nanostructures—and we will explore more complex “second-generation” nanostructures typically evolving from a high level of interfacial control. As a recurring theme, we will review recent advances made toward the understanding of nucleation and growth processes at the nanoscale, as such insights are expected to further push the borders of nanoMOF science
The FLUKA Monte Carlo, non-perturbative QCD and Cosmic Ray cascades
The FLUKA Monte Carlo code, presently used in cosmic ray physics, contains
packages to sample soft hadronic processes which are built according to the
Dual Parton Model. This is a phenomenological model capable of reproducing many
of the features of hadronic collisions in the non perturbative QCD regime. The
basic principles of the model are summarized and, as an example, the associated
Lambda-K production is discussed. This is a process which has some relevance
for the calculation of atmospheric neutrino fluxes.Comment: Extended version of the work for the proceedings of the workshop on
QCD at Cosmic Ray Energies, Erice, Aug. 30 - Sep. 4 2004, Ital
Fusion of strings vs. percolation and the transition to the quark-gluon plasma
In most of the models of hadronic collisions the number of exchanged colour
strings grows with energy and atomic numbers of the projectile and target. At
high string densities interaction between them should melt them into the
quark-gluon plasma state. It is shown that under certain assumptions about the
the string interaction, a phase transition to the quark gluon plasma indeed
takes place in the system of many colour strings. It may be of the first or
second order (percolation), depending on the particular mechanism of the
interaction. The critical string density is about unity in both cases. The
critical density may have been already reached in central Pb-Pb collisions at
158 A GeV.Comment: 16 pages, 3 Postscript figure
The hadronic models for cosmic ray physics: the FLUKA code solutions
FLUKA is a general purpose Monte Carlo transport and interaction code used
for fundamental physics and for a wide range of applications. These include
Cosmic Ray Physics (muons, neutrinos, EAS, underground physics), both for basic
research and applied studies in space and atmospheric flight dosimetry and
radiation damage. A review of the hadronic models available in FLUKA and
relevant for the description of cosmic ray air showers is presented in this
paper. Recent updates concerning these models are discussed. The FLUKA
capabilities in the simulation of the formation and propagation of EM and
hadronic showers in the Earth's atmosphere are shown.Comment: 8 pages, 9 figures. Invited talk presented by M.V. Garzelli at
ISVHECRI2006, International Symposium on Very High Energy Cosmic Rays,
Weihai, China, August 15 - 22 200
Charm Production in DPMJET
In this work, charm production in the {\sc dpmjet} hadronic jet simulation is
compared to experimental data. Since the major application of {\sc dpmjet} is
the simulation of cosmic ray-induced air showers, the version of the code
integrated in the CORSIKA simulation package has been used for the comparison.
Wherever necessary, adjustments have been made to improve agreement between
simulation and data. With the availability of new muon/neutrino detectors that
combine a large fiducial volume with large amounts of shielding, investigation
of prompt muons and neutrinos from cosmic ray interactions will be feasible for
the first time. Furthermore, above TeV charmed particle decay
becomes the dominant background for diffuse extraterrestrial neutrino flux
searches. A reliable method to simulate charm production in high-energy
proton-nucleon interactions is therefore required.Comment: 10 pages, to be published in JCA
Gauge-invariant strings in the 3d U(1)+Higgs theory
We describe how the strings, which are classical solutions of the continuum
three-dimensional U(1)+Higgs theory, can be studied on the lattice. The effect
of an external magnetic field is also discussed and the first results on the
string free energy are presented. It is shown that the string free energy can
be used as an order parameter when the scalar self-coupling is large and the
transition is continuous.Comment: LATTICE98(higgs); missing author added, no changes to tex
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