Soot formation in the methane oxygen and methane/oxygen/hydrogen flame

The feasibility of using methane, recovered from carbon dioxide by the Sabatier-Senderens reaction, was investigated as a fuel in a reaction control engine. A problem to be avoided is the emission of soot particles. It is thought that such particles would remain in the environment of the spacecraft and, thereby, adversely affect optical sightings and possibly have an effect upon communications. The initial studies were of a practical nature. The first was the influence of the spatial arrangement of the fuel and oxygen injectors on soot formation. In the second study, inhibition of soot formation was considered. Considering the given situation, it was impractical to use an additive. However, since methanol combustion does not produce soot, and methanol can be produced from methane in situ, the possibility that methanol could act as an inhibitor was studied. In the third study, since these are restartable engines, the effect of shutdown on the rapidity of soot formation was studied

Investigation of the chemical kinetics of an advanced high energy propellant system Quarterly progress report, 1 Jun. - 1 Sep. 1968

Reaction kinetics of high energy oxygen difluoride diborane propellant syste

Management of Acute Myocardial Infarction During the COVID-19 Pandemic.

The worldwide pandemic caused by the novel acute respiratory syndrome coronavirus 2 (SARS-CoV2) has resulted in a new and lethal disease termed coronavirus disease 2019 (COVID-19). Although there is an association between cardiovascular disease and COVID-19, the majority of patients who need cardiovascular care for the management of ischemic heart disease may not be infected with COVID-19. The objective of this document is to provide recommendations for a systematic approach for the care of patients with an acute myocardial infarction (AMI) during the COVID-19 pandemic. There is a recognition of two major challenges in providing recommendations for AMI care in the COVID-19 era. Cardiovascular manifestations of COVID-19 are complex with patients presenting with AMI, myocarditis simulating a ST-elevation MI presentation, stress cardiomyopathy, non-ischemic cardiomyopathy, coronary spasm, or nonspecific myocardial injury and the prevalence of COVID-19 disease in the US population remains unknown with risk of asymptomatic spread. This document addresses the care of these patients focusing on 1) the varied clinical presentations; 2) appropriate personal protection equipment (PPE) for health care workers; 3) role of the Emergency Department, Emergency Medical System and the Cardiac Catheterization Laboratory; and 4) Regional STEMI systems of care. During the COVID-19 pandemic, primary PCI remains the standard of care for STEMI patients at PCI capable hospitals when it can be provided in a timely fashion, with an expert team outfitted with PPE in a dedicated CCL room. A fibrinolysis-based strategy may be entertained at non-PCI capable referral hospitals or in specific situations where primary PCI cannot be executed or is not deemed the best option

Management of Platelet-Directed Pharmacotherapy in Patients With Atherosclerotic Coronary Artery Disease Undergoing Elective Endoscopic Gastrointestinal Procedures

The periprocedural management of patients with atherosclerotic coronary heart disease, including those who have heart disease and those who are undergoing percutaneous coronary intervention and stent placement who might require temporary interruption of platelet-directed pharmacotherapy for the purpose of an elective endoscopic gastrointestinal procedure, is a common clinical scenario in daily practice. Herein, we summarize the available information that can be employed for making management decisions and provide general guidance for risk assessment

Antithrombotic Treatment in Transcatheter Aortic Valve Implantation Insights for Cerebrovascular and Bleeding Events

Transcatheter aortic valve implantation (TAVI) has emerged as a therapeutic alternative for patients with symptomatic aortic stenosis at high or prohibitive surgical risk. However, patients undergoing TAVI are also at high risk for both bleeding and stroke complications, and specific mechanical aspects of the procedure itself can increase the risk of these complications. The mechanisms of periprocedural bleeding complications seem to relate mainly to vascular/access site complications (related to the use of large catheters in a very old and frail elderly population), whereas the pathophysiology of cerebrovascular events remains largely unknown. Further, although mechanical complications, especially the interaction between the valve prosthesis and the native aortic valve, may play a major role in events that occur during TAVI, post-procedural events might also be related to a prothrombotic environment or state generated by the implanted valve, the occurrence of atrial arrhythmias, and associated comorbidities. Antithrombotic therapy in the setting of TAVI has been empirically determined, and unfractionated heparin during the procedure followed by dual antiplatelet therapy with aspirin (indefinitely) and clopidogrel (1 to 6 months) is the most commonly recommended treatment. However, bleeding and cerebrovascular events are common; these may be modifiable with optimization of periprocedural and post-procedural pharmacology. Further, as the field of antiplatelet and anticoagulant therapy evolves, potential drug combinations will multiply, introducing variability in treatment. Randomized trials are the best path forward to determine the balance between the efficacy and risks of antithrombotic treatment in this high risk-population

Cardiovascular Outcomes Following Rotational Atherectomy: A UK Multicentre Experience

Objectives: To identify factors associated with outcomes following rotational atherectomy (RA). Background: RA is an effective way to mechanically modify heavily calcified lesions before stenting; however its outcomes are not well defined. Methods and Results: Retrospective evaluation of all patients who underwent RA in three large UK centers (Leeds General Infirmary (LGI), Royal Infirmary of Edinburgh (RIE) and University Hospital of North Staffordshire (UHNS)) from March 2005 to January 2013. Five hundred and eighteen patients had RA with median follow-up period of 22 months. About 68.3% were male, 28.7% had DM and 34.6% were treated because of ACS. Stents were deployed in 97.3% of the patients while 30.7% of the procedures were performed transradially. Maximum burr was ≤1.75 mm in 85.5% and the mean SYNTAX score was 19.5 ± 11.6. Peri-procedural complications occurred in 6.4% and vascular access complications in 1.9%. Outcomes in the follow-up period were: MACE 17.8%, cardiac death 7.1%, MI 11.7%, TVR 7.5%, all-cause death 13.7%, definite stent thrombosis (ST) 1.4% and stroke 2.9%. Patients with intermediate and high SYNTAX scores were more likely to suffer MACE, cardiac death, MI, all-cause death and ST. Patients with a SYNTAX score >32 were also more likely to have a peri-procedural complication. Multiple logistic regression analysis showed that the presence of PVD (P = 0.026, OR = 2.0), DM (P = 0.008, OR = 2.1), ACS presentation (P = 0.011, OR = 2.1) and SYNTAX score ≥23 (P = 0.02, OR = 1.9) had a significant association with MACE. Conclusions: RA is safe and effective, with high rate of procedural success and relatively low incidence of MACE. PVD, DM, ACS presentation and SYNTAX score were significant predictors for MACE. © 2016 Wiley Periodicals, Inc