1,386 research outputs found
Efficacy of hemostatic powders in upper gastrointestinal bleeding: A systematic review and meta-analysis
No full textConversion of synthesis gas to isobutylene over precipitated zirconia based catalysts
No full textVita.Recent amendments to the Clean Air Act have renewed interest in synthesizing isobutylene from coal derived synthesis gas for use in producing methyl tertiary-butyl ether. Previous work on isosynthesis was performed at extreme conditions or at very low conversions. No rate equation to predict carbon monoxide conversion or methods to predict product distribution existed. In this study zirconia catalysts were synthesized by a precipitation, a hydrothermal, and a calcination method. The effects of sodium, titanium, manganese, cerium, and thorium additives were initially investigated. Catalysts prepared by the precipitation method were most active followed by calcination and hydrothermal preparation. The hydrothermal catalysts were more selective to the iso-C4's. Of the initial catalysts, a 796 (wt) cerium zirconia was found to be most active. When hydrogen sulfide was included in the feed a dramatic shift in product selectivity occurred with no loss in catalytic activity. The C2+C3 fraction was reduced by about half while the Cs fraction was increased by a factor of two an a half. This increase was realized in the formation of 3-methyl-l-butene, the second least thermodynamically favored C5 hydrocarbon, which showed an eighteenfold increase. Presulfiding the catalyst resulted in a more pronounced shift to the C5's with a slight reduction in activity. The theory that oxygen vacancies are the catalytic site for isosynthesis was tested by doping zirconia catalysts with various levels of +1, +2, +3, and +5 oxides. The dopants studied included lithium, magnesium, aluminum, dysprosium, and tantalum. Additionally, a zirconia catalyst containing yttrium, barium, and copper in a 1:2:3 ratio was prepared. Catalyst testing showed that oxygen vacancies are required for an active catalyst and that oxygen vacancies also play a vital role in the selectivity of isosynthesis catalysts. Results indicated that the most active single component doped catalyst should introduce the most oxygen vacancies per cation incorporated into the lattice and have an ionic radius close to that of zirconium. Carbon monoxide conversion was successfully modeled with a rate equation dependent on the partial pressures of CO, H2, and C02. The product distribution was modeled by a simple extension of the rate equation. Reproduce
MicroRNAs fingerprint of bicuspid aortic valve
No full textAortic valve tissue is largely exposed to high blood flow. Cells belonging to aortic valve tissues are able to detect and respond to flow conditions changes. Bicuspid aortic valve (BAV) presents altered morphology, with only two abnormal cusps instead of three. This results in an alteration of blood flow dynamics on valve cusps and aortic wall, which may, in turn, increase the risk to develop aortic stenosis and/or regurgitation, endocarditis, aortopathy and/or aortic dissection. MicroRNAs (miRNAs) are short RNA strands regulating gene expression mainly through the inhibition of their target mRNAs. They are largely involved in cardiovascular pathophysiology and heart disease. More recently, it has been observed that the expression of specific miRNAs can be modulated in response to changes in hemodynamic conditions. Using a bioinformatic approach, this article analyses available scientific evidence about the differential expression of miRNAs in the bicuspid aortic valve, with a focus on the differential modulation compared to the calcific-degenerative tricuspid aortic valve
Optimal duration and combination of antiplatelet therapies following percutaneous coronary intervention: a meta-analysis
No full textFlow-Responsive Noncoding RNAs in the Vascular System: Basic Mechanisms for the Clinician
No full textThe vascular system is largely exposed to the effect of changing flow conditions. Vascular cells can sense flow and its changes. Flow sensing is of pivotal importance for vascular remodeling. In fact, it influences the development and progression of atherosclerosis, controls its location and has a major influx on the development of local complications. Despite its importance, the research community has traditionally paid scarce attention to studying the association between different flow conditions and vascular biology. More recently, a growing body of evidence has been accumulating, revealing that ncRNAs play a key role in the modulation of several biological processes linking flow-sensing to vascular pathophysiology. This review summarizes the most relevant evidence on ncRNAs that are directly or indirectly responsive to flow conditions to the benefit of the clinician, with a focus on the underpinning mechanisms and their potential application as disease biomarkers
Non-Vitamin K Oral Anticoagulants (NOAC) Versus Vitamin K Antagonists (VKA) for Atrial Fibrillation with Elective or Urgent Percutaneous Coronary Intervention: A Meta-Analysis with a Particular Focus on Combination Type
No full textBackground: Our study aims to perform a meta-analysis of benefits and risks associated with the use of non-vitamin K oral anticoagulants (NOAC) versus vitamin K antagonists (VKA) in patients with a percutaneous coronary intervention (PCI) with a particular focus on the combination type: dual vs. dual antithrombotic therapy (DAT: NOAC + single antiplatelet therapy (SAPT) vs. DAT: VKA + SAPT), dual vs. triple antithrombotic therapy (DAT: NOAC + SAPT vs. TAT: VKA + dual antiplatelet therapy (DAPT)) or triple vs. triple antithrombotic therapy (TAT: NOAC+DAPT vs. TAT: VKA+DAPT). Methods: PubMed, EMBASE, and Cochrane databases were searched to identify randomized controlled trials comparing antithrombotic regimens. Four randomized studies (n = 10.969; PIONEER AF-PCI, RE-DUAL PCI, AUGUSTUS, and ENTRUST-AF PCI) were included. The primary outcome was the composite of major bleeding defined by the International Society on Thrombosis and Hemostasis (ISTH) and clinically relevant bleeding requiring medical intervention (CRNM). Secondary outcomes included all-cause mortality, major adverse cardiovascular events (MACE), myocardial infarction (MI), stroke, and stent thrombosis (ST). Results: Combination strategies with NOACs were associated with reduced risk of major bleeding events across different combination strategies as compared to VKA, with the most significant risk reduction when DAT was compared with TAT, namely DAT with NOAC + SAPT was associated with a 37% relative risk reduction (RRR) of major bleeding events as compared to TAT with VKA + DAPT (RR 0.63; 95% CI, 0.50-0.80). The reduction of major bleeding risks is a class effect of NOACs. Combination strategies of NOACs vs. VKAs resulted in a comparable risk of MACE, MI, stroke, ST, or death. Conclusions: Antithrombotic combinations of NOACs (as DAT or TAT) are safer than VKAs with respect to bleeding risk and result in a satisfactory efficacy with no increase of ischemic or thrombotic events in patients undergoing PCI
IL "NUOVO LIBERALISMO" IN GRAN BRETAGNA
No full textVENGONO PRESENTATI ALCUNI BRANI TRATTI DA ARTICOLI DI RIVISTE E SAGGI CHE AFFRONTANO IL TEMA DELLA TRASFORMAZIONE DEL LIBERALISMO INGLESE DINANZI ALL'EMERGERE E AL RADICARSI DELLA QUESTIONE SOCIALE. IL "NUOVO LIBERALISMO" E' UN LIBERALISMO CHE, RESPINGENDO L'INDIVIDUALISMO ASSOLUTO, POSTULA UN RUOLO "ETICO" E CAUTAMENTE INTERVENTISTA DELLO STAT
Transient analysis of bang-bang phase locked loops
No full textThis work gives insight into the behaviour of second-order bang-bang phase locked loops in the far from lock region. This region, while largely unexplored, is of particular interest as PLL behaviour in this region determines locking time and capture range. By analysing PLL cycle slipping behaviour in this region, the transient response for the system is derived. Expressions for first-order system stability and locking time are also presented
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