94 research outputs found

    Ex-LDH-based catalysts for CO2 conversion to methanol and dimethyl ether

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    CO2-derived methanol and dimethyl ether can play a very important role as fuels, energy carriers, and bulk chemicals. Methanol production from CO2 and renewable hydrogen is considered to be one of the most promising pathways to alleviate global warming. In turn, methanol could be subsequently dehydrated into DME; alternatively, one-step CO2 conversion to DME can be obtained by hydrogenation on bifunctional catalysts. In this light, four oxide catalysts with the same Cu and Zn content (Cu/Zn molar ratio = 2) were synthesized by calcining the corresponding CuZnAl LDH systems modified with Zr and/or Ce. The fresh ex-LDH catalysts were characterized in terms of composition, texture, structure, surface acidity and basicity, and reducibility. Structural and acid– base properties were also studied on H2-treated samples, on which specific metal surface area and dispersion of metallic Cu were determined as well. After in situ H2 treatment, the ex-LDH systems were tested as catalysts for the hydrogenation of CO2 to methanol at 250 °C and 3.0 MPa. In the same experimental conditions, CO2 conversion into dimethyl ether was studied on bifunctional catalysts obtained by physically mixing the ex-LDH hydrogenation catalysts with acid ferrierite or ZSM-5 zeolites. For both processes, the effect of the Al/Zr/Ce ratio on the products distribution was investigated

    CO2 hydrogenation to methanol with an innovative Cu/Zn/Al/Zr catalyst: Experimental tests and process modeling

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    In this study, an innovative Cu/Zn/Al/Zr catalyst for the conversion of CO2 and H2 into methanol is tested at laboratory scale (0.5 g of catalyst into a cylindrical fixed bed reactor, with 9.1 mm internal diameter). Fourteen experimental tests are performed under isothermal conditions (T = 250 °C), covering a range of pressure (3.0–7.0 MPa), Gas Hourly Space Velocity (4000–13,000 h-1) and H2/CO2 molar ratio (between 3 and 6) relevant to industrial applications, with or without CO in the feed mixture, with flow-rates ranging between 200 and 650 NmL min-1. Based on the established Graaf’s kinetic model, new kinetic parameters are calibrated and a plug-flow model of the isothermal reactor is implemented and simulated in Aspen Plus. A reasonable agreement between experimental data and calibrated model is achieved, with deviations lower than 10% of the measured flow rates for each species in the product stream. CO2 conversion up to 26% and methanol yields up to 13% are obtained during the test campaign (test run #12). The model represents a valid tool for future research or engineering studies targeting the design and performance assessment of demo/full-scale CO2-to-methanol synthesis processes based on the Cu/Zn/Al/Zr catalyst introduced in this paper

    Referral from vascular surgery to cardiovascular rehabilitation and related outcomes in patients with peripheral arterial disease: the THINKPAD-RELOADED survey.

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    The utilization of cardiovascular rehabilitation (CR) programmes in patients with Lower Extremity Peripheral Artery Disease (LEPAD) is generally poor, with limited evidence of current policies for referral. The aim of the study was to evaluate, within a cohesive network of CR and vascular surgery facilities with facilitated referral process, the clinical characteristic of LEPAD patients referred to CR and related outcomes, as compared to patients not referred. The present is an observational prospective study of consecutive patients recruited at vascular surgery facilities. Out of 329 patients observed, the average referral rate to CR was 34% (28% and 39% in patients with and without recent peripheral revascularization, p<0.05). LEPAD patients entering the CR programme were similar to those who did not according to sex, age, the vascular surgery setting of evaluation, and localization of arterial lesions. Patients with moderate intermittent claudication and patients with acute limb ischemia as index event were more represented among those who attended CR (41% vs 21% and 9% vs 2% respectively, p<0.05). Patients referred to CR had five times more episodes of acute coronary syndrome and heart failure as complication of the index event. The cardiovascular risk profile (obesity 29.5% vs 11%, p<0.05; hypercholesterolemia 80% vs 61%, p<0.05) was much worse in LEPAD patients referred to CR, but conversely, they better achieved secondary prevention targets, particularly for blood pressure control (97% vs 57%, p<0.05). All-cause 2-year mortality in the whole patients' population was 6%. Patients entering the CR programme displayed less events (13.5% vs 37.7%, p<0.05), mainly death (3.1% vs 11.3%, p<0.05) and limb-related events (4.2% vs 15.2%, p<0.05). The results of our study suggest that when a cohesive network of vascular surgery and CR facilities becomes available, the referral rate to rehabilitation may increase up to one third of eligible patients. Patients with higher comorbidity and cardiovascular risk seem to have priority in the referral process, nevertheless those with peripheral revascularization are still underestimated. Entering CR may ensure better cardiovascular risk profile and cardiovascular prognosis in LEPAD patients, and consequently the systematic adoption of this care model needs to be strongly recommended and facilitated

    Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

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    Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

    Sardinia Array Demonstrator: Instrument Overview and Status

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    In the framework of the Square Kilometer Array (SKA) project, the Italian Institute for Astrophysics (INAF) has addressed several efforts in the design and prototyping of aperture arrays for low-frequency radio astronomical research. The Sardinia Array Demonstrator (SAD) is a national project aimed to develop know-how in this area and to test different architectural technologies and calibration algorithms. SAD consists of 128 prototypical dual-polarized Vivaldi antennas designed to operate at radio frequencies below 650 MHz. The antennas will be deployed at the Sardinia Radio Telescope’s site with a versatile approach able to provide two different array configurations: (i) all antennas grouped in one large station or (ii) spread among a core plus few satellite stations. This paper provides an overview of the SAD project from an instrumental point of view, and illustrates its status after 2 years from its start

    From Algebraic Sets to Monomial Linear Bases By Means of Combinatorial Algorithms.

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    Introduction 1.1 Let N be the monoid of non-negative integers. Denote by i := (i 1 ; : : : ; i n ) an arbitrary element in the power N n . The usual order on N, as well as the partial order it induces on N n , will be denoted by . Define an n-dimensional Ferrers diagram to be any finite ideal of the poset N n , i.e. any non-empty finite subset F ` N n such that j ! i 2 F =) j 2 F . An element i = (i 1 ; : : : ; i n ) 62 F is said to be a co-minimal element for the Ferrers diagram F if it is a minimal element of the complementary filter N n
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