68 research outputs found
Studio fluidodinamico del confinamento dell'anidride carbonica nel sottosuolo
The storage capacity of the reservoir is the main issue in Carbon Capture and Geologic Storage projects, so people are searching for effective and reliable evaluation methods. The present work estimates the storage capacity of a saline aquifer starting from its hydrologic properties and the pressure and temperature conditions.
After a literature review of the evaluation methods, an analytical model of the underground motion of the CO2 is developed, and a dimensional analysis is done to intepret the system.
On the basis of the analytical model, a calculation code was written to simulate the dynamic behaviour of the CO2 in porous media originally saturated with water. As a result of the critical discussion of the scientific literature, for the estimation of the storage capacity the code considers only the fluid-dynamic trapping mechanisms (static trapping and residual trapping). Acting on the short period, these mechanisms are the most interesting from an industrial point of view.
The code is used on some significative case studies, in order to evaluate the storage capacity of the sites. The case studies derive in a statistically robust way from a database of more than 1200 known reservoirs, considering parameters such as temperature, depth, permeability, porosity, salinity.
The simulation results are interpreted on the basis of the dimensional analysis, gathering general hints on the storage process. Storage volumetric efficiencies between 1.4 and 5.8% are obtained
Platform switching on wide-diameter external hex implants a finite element analysis
Objectives:
The objective of this work was to use finite element analysis to compare the effect of forces coming to
bear on abutments 4.1 or 5.0 mm in diameter connected to a 5.0 mm implant (i.e. with or without platform swit
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ching).
Study design:
A 3D CAD model of a 5 x 11.5 mm external hex implant was developed, complete with a connection
screw and either of two abutments, one 4.1 and the other 5 mm in diameter, to assess the influence of two loading
conditions, i.e. 200 N loaded either axially or off center on the top of the abutment.
Results and conclusions:
In the symmetrically loaded models, greater stresses were transmitted to the bone in the
area below the neck of the implant in the case of the wider-diameter abutment. When the narrower abutment was
considered, the stress lines remained confined to the metal and were transferred to the bone in a more distal position.
When the stresses in the bone where compared under non-symmetrical loading of the larger- and smaller-diameter
abutments, the stresses reached lower values in the latter case. These findings indicate that platform switching (i.e.
coupling a 4.1 mm abutment with a 5 mm implant) achieves a better, more even distribution of the peri-implant
stresses deriving from simulated occlusal loads on the bone margins
Near-infrared adaptive optics imaging of high redshift quasars
The properties of high redshift quasar host galaxies are studied, in order to
investigate the connection between galaxy evolution, nuclear activity, and the
formation of supermassive black holes. We combine new near-infrared
observations of three high redshift quasars (2 < z < 3), obtained at the ESO
Very Large Telescope equipped with adaptive optics, with selected data from the
literature. For the three new objects we were able to detect and characterize
the properties of the host galaxy, found to be consistent with those of massive
elliptical galaxies of M(R) ~ -24.7 for the one radio loud quasar, and M(R) ~
-23.8 for the two radio quiet quasars. When combined with existing data at
lower redshift, these new observations depict a scenario where the host
galaxies of radio loud quasars are seen to follow the expected trend of
luminous (~5L*) elliptical galaxies undergoing passive evolution. This trend is
remarkably similar to that followed by radio galaxies at z > 1.5. Radio quiet
quasars hosts also follow a similar trend but at a lower average luminosity
(~0.5 mag dimmer). The data indicate that quasar host galaxies are already
fully formed at epochs as early as ~2 Gyr after the Big Bang and then passively
fade in luminosity to the present epoch.Comment: Accepted for publication in ApJ, 24 pages, 10 figure
Decellularization and Delipidation Protocols of Bovine Bone and Pericardium for Bone Grafting and Guided Bone Regeneration Procedures
The combination of bone grafting materials with guided bone regeneration (GBR) membranes seems to provide promising results to restore bone defects in dental clinical practice. In the first part of this work, a novel protocol for decellularization and delipidation of bovine bone, based on multiple steps of thermal shock, washes with detergent and dehydration with alcohol, is described. This protocol is more effective in removal of cellular materials, and shows superior biocompatibility compared to other three methods tested in this study. Furthermore, histological and morphological analyses confirm the maintenance of an intact bone extracellular matrix (ECM). In vitro and in vivo experiments evidence osteoinductive and osteoconductive properties of the produced scaffold, respectively. In the second part of this study, two methods of bovine pericardium decellularization are compared. The osmotic shock-based protocol gives better results in terms of removal of cell components, biocompatibility, maintenance of native ECM structure, and host tissue reaction, in respect to the freeze/thaw method. Overall, the results of this study demonstrate the characterization of a novel protocol for the decellularization of bovine bone to be used as bone graft, and the acquisition of a method to produce a pericardium membrane suitable for GBR applications
The cosmic evolution of quasar host galaxies
We present near-infrared imaging of the host galaxies of 17 quasars in the
redshift range 1 < z < 2, carried out at the ESO VLT UT1 8m telescope under
excellent seeing conditions (~0.4 arcsec). The sample includes radio-loud (RLQ)
and radio-quiet (RQQ) quasars with similar distribution of redshift and optical
luminosity. For all the observed objects but one we have derived the global
properties of the surrounding nebulosity. The host galaxies of both types of
quasars follow the expected trend in luminosity of massive ellipticals
undergoing simple passive evolution, but there is a systematic difference by a
factor ~2 in the host luminosity between RLQs and RQQs (M_K(RLQ) = -27.55 +-
0.12 and M_K(RQQ) = -26.83 +- 0.25). Comparison with quasar hosts at similar
and lower redshift indicates that the difference in the host luminosity between
RLQs and RQQs remains the same from z = 2 to the present epoch. No significant
correlation is found between the nuclear and the host luminosities. Assuming
that the host luminosity is proportional to the black hole mass, as observed in
nearby massive spheroids, these quasars emit at very different levels (spread
\~1.5dex) with respect to their Eddington luminosity and with the same
distribution for RLQs and RQQs. Apart from a factor of ~2 difference in
luminosity, the hosts of RLQs and RQQs appear to follow the same cosmic
evolution as massive inactive spheroids. Our results support a view where
nuclear activity can occur in all luminous ellipticals without producing a
significant change in their global properties and evolution. Quasar hosts
appear to be already well formed at z ~2, in disagreement with models for the
joint formation and evolution of galaxies and active nuclei based on the
hierarchical structure formation scenario.Comment: Astrophysical Journal, accepted; 34 page
Genome sequence analysis of the first human West Nile virus isolated in Italy in 2009.
In 2009, six new human cases of West Nile neuroinvasive disease (WNND) were identified in Veneto region, following the six cases already reported in 2008. A human West Nile virus (WNV) isolate was obtained for the first time from an asymptomatic blood donor. Whole genome sequence of the human WNV isolate showed close phylogenetic relatedness to the Italy-1998-WNV strain and to other WNV strains recently isolated in Europe, with the new acquisition of the NS3-Thr249Pro mutation, a trait associated with avian virulence, increased virus transmission, and the occurrence of outbreaks in humans
Human cases of West Nile Virus infection in north-eastern Italy, 15 June to 15 November 2010.
In 2010, for the third consecutive year, human cases of West Nile virus (WNV) infection, including three confirmed cases of neuroinvasive disease and three confirmed cases of West Nile fever, were identified in north-eastern Italy. While in 2008 and 2009 all human cases of WNV disease were recorded in the south of the Veneto region, cases of WNV disease in 2010 additionally occurred in two relatively small northern areas of Veneto, located outside those with WNV circulation in the previous years. WNV IgG antibody prevalence in blood donors resident in Veneto was estimated as ranging from 3.2 per 1,000 in areas not affected by cases of WNV disease to 33.3 per 1,000 in a highly affected area of the Rovigo province. No further autochthonous human cases of WNV disease were notified in Italy in 2010. The recurrence of human cases of WNV infection for the third consecutive year strongly suggests WNV has become endemic in north-eastern Italy
Near-Infrared Observations of BL Lacertae Host Galaxies
Multi-band near-infrared images of twelve BL Lacertae objects were obtained
with the 2.5m telescope at the Las Campanas Observatory in order to determine
the properties of their underlying host galaxies. Resolved emission was clearly
detected in eight of the lowest redshift targets (up to z~0.3), and was modeled
with a de Vaucouleurs r^{1/4} surface brightness law. We find that the
morphologies match the elliptical galaxy profiles well, and that the BL Lac
objects reside in large and luminous, but otherwise normal hosts -- consistent
with previous studies done predominantly at optical wavelengths. The median
absolute K-band magnitude of the galaxies in this study is -26.2, the average
half-light radius is 4.2 +/- 2.3 kpc, and their average integrated R-K color is
2.7 +/- 0.3 mag. These are well within the range of values measured previously
in the H-band by Kotilainen et al. and Scarpa et al. in a comparable number of
targets. Taking their data together with our results, we find a best-fit K-band
Kormendy relation of \mu_{e} = 4.3 log_{10} (r_{e}/kpc) + 14.2 mag arcsec^{-2},
virtually identical to that obtained for normal ellipticals. Finally, the
near-infrared colors determined for five galaxies (average J-K = 0.8 +/- 0.3
mag) are the first such measurements for BL Lac hosts, and match those expected
from old stellar populations at the BL Lac redshifts.Comment: 10 pages, includes 4 figures and 3 tables. ApJ, accepte
VERT-X: VERTical X-ray raster-scan facility for ATHENA calibration. The concept design
Calibration of the ATHENA telescope is a critical aspect of the project and raises significant difficulties due to the unprecedented size, mass and focal length of the mirror assembly. The VERT-X project, financed by ESA and started in January 2019 by a Consortium led by INAF and which includes EIE, Media Lario Technologies, GPAP, and BCV Progetti, aims to design an innovative calibration facility. In the VERT-X design the parallel beam, needed for calibration, is produced placing a source in the focus of an X-ray collimator. This system is mounted on a raster-scan mechanism which covers the entire ATHENA optics. The compactness of the VERT-X design allows a vertical geometry for the ATHENA calibration facility, with several potential benefits with respect to the long horizontal tube calibration facilities
Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy
IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical
attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced
colorectal cancers at diagnosis.
OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced
oncologic stage and change in clinical presentation for patients with colorectal cancer.
DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all
17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December
31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period),
in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was
30 days from surgery.
EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery,
palliative procedures, and atypical or segmental resections.
MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer
at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as
cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding,
lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery,
and palliative surgery. The independent association between the pandemic period and the outcomes
was assessed using multivariate random-effects logistic regression, with hospital as the cluster
variable.
RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years)
underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142
(56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was
significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR],
1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic
lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03).
CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the
SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients
undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for
these patients
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