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Mari C.,University of Chieti Pescara
Progress in Nuclear Energy | Year: 2014

This paper provides an analysis on the costs of generating electricity from nuclear and fossil sources (coal and natural gas) based on the most recent technical data available in literature. The aim is to discuss the competitiveness of nuclear power in a liberalized market context by considering the impact on the generating costs of the main factors affecting the viability of the nuclear option. Particular attention will be devoted to study the variability of the generating costs regarding the level of risk perceived by investors through a sensitivity analysis of the generating costs with respect to the cost of capital and the debt fraction of initial investment. The impact of environment policies is also considered by including a "tax" on carbon emissions. The analysis reveals that nuclear power could have ample potentiality also in a competitive market, particularly if the level of risk perceived by the investors keeps standing low. For low values of the cost of capital, nuclear power seems to be the most viable solution. Uncertainty about environmental policies and unpredictability of carbon emissions costs might offer further margins of competitiveness. © 2014 Elsevier B.V. All rights reserved. Source

Pierdomenico S.D.,University of Chieti Pescara
American journal of hypertension | Year: 2011

Metabolic syndrome (MetS) is a cluster of risk factors, related to visceral adiposity, which is frequently observed in overweight patients. However, it has also been reported in normal weight subjects. Epicardial adipose tissue (EAT) is a visceral fat. The aim of the study was to evaluate whether EAT is associated with MetS in hypertensive patients with normal weight and waist. We studied 174 Caucasian hypertensive patients, aged ≥40 years, with body mass index (BMI) <25 kg/m(2) and waist circumference <102 cm in men and 88 cm in women. MetS was defined according to NCEP ATP III criteria, not including waist circumference. EAT was measured by echocardiography above the free wall of the right ventricle, at end diastole. MetS was present in 21 (12%) patients. EAT was significantly higher in patients with MetS than in those without MetS, 4.0 ± 0.8 vs 2.5 ± 0.9 mm, P < 0.01, respectively, but BMI and waist circumference were not. Multivariate analysis showed that EAT was independently associated with MetS. Receiver operating characteristic (ROC) curve analysis showed that EAT significantly improved prediction of MetS when added to BMI and waist circumference. Indeed, the area under the curve improved from 0.63 (0.50-0.76) to 0.91 (0.87-0.96), and resulted significantly higher (P < 0.01). ROC curve for EAT alone indicated that the cutoff value of 3.1 mm had the best performance in predicting MetS, that is, 100% sensitivity and 79% specificity. EAT thickness is associated with MetS in hypertensive patients with normal weight and waist. Source

Cellini L.,University of Chieti Pescara
World Journal of Gastroenterology | Year: 2014

Helicobacter pylori (H. pylori) is widely adaptable for colonization in human stomachs in more than half of the world's population. The microorganism is characterized by an unusual capability of arranging itself in both genotypic and phenotypic ways. Stressing conditions, including antimicrobial agents in sub-inhibitory concentrations, facilitate entering the viable but nonculturable state in which bacterial cells acquire the coccoid form. This morphotype represents an important strategy for bacterial survival in unsuitable conditions and also allows escape from the immune system. H. pylori is capable of forming biofilm outside and inside the host. For the bacterial population, the sessile growth mode represents an ideal environment for gene rearrangement, as it allows the acquiring of important tools aimed to improve bacterial "fitness" and species preservation. Biofilm formation in H. pylori in the human host also leads to recalcitrance to antibiotic treatment, thus hampering eradication. These lifestyle changes of H. pylori allow for a "safe haven" for its survival and persistence according to different ecological niches, and strongly emphasize the need for careful H. pylori surveillance to improve management of the infection. © 2014 Baishideng Publishing Group Inc. All rights reserved. Source

Coletti C.,University of Chieti Pescara
Accounts of chemical research | Year: 2012

Transition metal complexes containing unsaturated carbenes have enjoyed a recent surge in research interest. In addition to showing potential as molecular wires and as components of opto-electronic materials, they provide multifaceted reactive sites for organic synthesis. In this Account, we describe results of recent theoretical studies that delineate the main features of electronic structure and bonding in allenylidenes and higher cumulenylidene complexes, [L(m)M]{box drawing double horizontal}C({box drawing double horizontal}C)(n){box drawing double horizontal}CR(1)R(2) (where L represents the ligand, M the metal, and n ≥ 1). Although free cumulenylidene ligands, :C({box drawing double horizontal}C)(n){box drawing double horizontal}CR(1)R(2), are extremely unstable and reactive species, they can be stabilized by coordination to a transition metal. The σ-donation of the electron lone pair on the terminal carbon atom to an empty metal d-orbital, together with the simultaneous π back-donation from filled metal d(π)-orbitals to empty cumulene π* system orbitals, leads to the formation of a strong M{box drawing double horizontal}C bond with multiple character. Density functional theory studies on the model systems [(CO)(5)Cr({box drawing double horizontal}C)(n)CH(2)] and [trans-Cl(PH(3))(4)Ru({box drawing double horizontal}C)(n)CH(2)](+) (where n = 1-9) have been useful in interpreting the structural and spectroscopic properties and the reactivity of this class of complexes. Geometry optimizations significantly contributed to the generalization of the sparse structural data available for allenylidene, butatrienylidene, and pentatetraenylidene complexes to higher cumulenylidene complexes (with up to eight carbon atoms in the chain), which show a clear structural trend. In particular, the geometries of all even-chain cumulenes are consistent with an almost purely cumulenic structure, whereas the geometries of odd-chain cumulenes present a significant polyyne-like carbon-carbon bond length alternation. The calculated bond dissociation energies (BDEs) of the cumulenylidene ligand remain almost constant on lengthening the cumulene chain. These BDEs indicate that there is no thermodynamic upper limit to the cumulene chain length and suggest that the synthetic difficulties in preparing higher cumulenylidenes are due to an increase in reactivity. The calculated charges on the carbon atoms show no significant polarization along the cumulene chain, indicating that charge distribution is not important in determining the regioselectivity of either electrophilic or nucleophilic attack, which is instead determined by frontier orbital factors. The breakdown of the contributions from the metal and the carbon atoms along the chain to the HOMO and LUMO shows that the HOMO has contributions mainly from the metal and the carbon atoms in even positions along the chain (C(2), C(4), C(6), and higher). In contrast, the LUMO has contributions mainly from the carbon atoms in odd positions along the chain (C(1), C(3), C(5), and higher), thus explaining the experimentally observed regioselectivity of electrophilic and nucleophilic attacks, which are directed, respectively, to even and odd positions of the cumulenylidene chain. The study of the electronic structure of cumulenylidenes has allowed us not only to give a consistent rationale for the main structural and spectroscopic properties and for the reactivity of this emerging class of compounds but also to predict the effect of ancillary ligands on the metal center or substituents on the carbon end. The result is a useful guide to new developments in the still-underexplored fields of this fascinating class of compounds. Source

Vazzana N.,University of Chieti Pescara
Journal of the American Heart Association | Year: 2013

Low high-density lipoprotein (HDL) levels are major predictors of cardiovascular (CV) events, even in patients on statin treatment with low-density lipoprotein (LDL) at target. In animal models HDLs protect LDL from oxidation and blunt platelet activation. Our study aimed to examine whether HDL levels are related to in vivo oxidative stress and platelet activation, as determinants of atherothrombosis. Urinary 8-iso-PGF2α and 11-dehydro-TXB2, in vivo markers of oxidative stress and platelet activation, respectively, were measured in 65 coronary heart disease (CHD) normocholesterolemic patients with HDL ≤35 mg/dL, and in 47 CHD patients with HDL >35 mg/dL. The 2 eicosanoids were also measured before and after an intensive exercise program in sedentary people (n=18) and before and after fenofibrate treatment in otherwise healthy subjects with low HDL (n=10). Patients with HDL ≤35 mg/dL showed significantly higher urinary 8-iso-PGF2α (median [25th to 75th percentiles]: 289 [189 to 380] versus 216 [171 to 321] pg/mg creatinine, P=0.019) and 11-dehydro-TXB2 (563 [421 to 767] versus 372 [249 to 465] pg/mg creatinine, P=0.0001) than patients with higher HDL. A direct correlation was found between urinary 8-iso-PGF2α and 11-dehydro-TXB2 in the entire group of patients (ρ=0.77, P<0.0001). HDL levels were inversely related to both 8-iso-PGF2α (ρ=-0.32, P=0.001) and 11-dehydro-TXB2 (ρ=-0.52, P<0.0001). On multiple regression, only 8-iso-PGF2α (β=0.68, P<0.0001) and HDL level (β=-0.29, P<0.0001) were associated with urinary 11-dehydro-TXB2 excretion, independent of sex, age, smoking, hypertension, diabetes, previous myocardial infarction, total cholesterol, LDL, and triglycerides. Both intensive exercise and fenofibrate treatment significantly reduced the 2 eicosanoids in healthy subjects, in parallel with an HDL increase. A low HDL phenotype, both in CHD patients and in healthy subjects, is associated with increased lipid peroxidation and platelet activation. These data provide novel insight into the mechanisms linking low HDL with increased CV risk. Source

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