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

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

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

Regional Systems of Care Demonstration Project: American Heart Association Mission: Lifeline STEMI Systems Accelerator.

BACKGROUND: Up to 50% of patients fail to meet ST-segment-elevation myocardial infarction (STEMI) guideline goals recommending a first medical contact-to-device time of <90 minutes for patients directly presenting to percutaneous coronary intervention-capable hospitals and <120 minutes for transferred patients. We sought to increase the proportion of patients treated within guideline goals by organizing coordinated regional reperfusion plans. METHODS: We established leadership teams, coordinated protocols, and provided regular feedback for 484 hospitals and 1253 emergency medical services (EMS) agencies in 16 regions across the United States. RESULTS: Between July 2012 and December 2013, 23 809 patients presented with acute STEMI (direct to percutaneous coronary intervention hospital: 11 765 EMS transported and 6502 self-transported; 5542 transferred). EMS-transported patients differed from self-transported patients in symptom onset to first medical contact time (median, 47 versus 114 minutes), incidence of cardiac arrest (10% versus 3%), shock on admission (11% versus 3%), and in-hospital mortality (8% versus 3%; P<0.001 for all comparisons). There was a significant increase in the proportion of patients meeting guideline goals of first medical contact-to-device time, including those directly presenting via EMS (50% to 55%; P<0.001) and transferred patients (44%-48%; P=0.002). Despite regional variability, the greatest gains occurred among patients in the 5 most improved regions, increasing from 45% to 57% (direct EMS; P<0.001) and 38% to 50% (transfers; P<0.001). CONCLUSIONS: This Mission: Lifeline STEMI Systems Accelerator demonstration project represents the largest national effort to organize regional STEMI care. By focusing on first medical contact-to-device time, coordinated treatment protocols, and regional data collection and reporting, we were able to increase significantly the proportion of patients treated within guideline goals

Association of Rapid Care Process Implementation on Reperfusion Times Across Multiple ST-Segment–Elevation Myocardial Infarction Networks

BACKGROUND: The Mission: Lifeline STEMI Systems Accelerator program, implemented in 16 US metropolitan regions, resulted in more patients receiving timely reperfusion. We assessed whether implementing key care processes was associated with system performance improvement. METHODS AND RESULTS: Hospitals (n=167 with 23 498 ST-segment-elevation myocardial infarction patients) were surveyed before (March 2012) and after (July 2014) program intervention. Data were merged with patient-level clinical data over the same period. For reperfusion, hospitals were grouped by whether a specific process of care was implemented, preexisting, or never implemented. Uptake of 4 key care processes increased after intervention: prehospital catheterization laboratory activation (62%-91%; P<0.001), single call transfer protocol from an outside facility (45%-70%; P<0.001), and emergency department bypass for emergency medical services direct presenters (48%-59%; P=0.002) and transfers (56%-79%; P=0.001). There were significant differences in median first medical contact-to-device times among groups implementing prehospital activation (88 minutes implementers versus 89 minutes preexisting versus 98 minutes nonimplementers; P<0.001 for comparisons). Similarly, patients treated at hospitals implementing single call transfer protocols had shorter median first medical contact-to-device times (112 versus 128 versus 152 minutes; P<0.001). Emergency department bypass was also associated with shorter median first medical contact-to-device times for emergency medical services direct presenters (84 versus 88 versus 94 minutes; P<0.001) and transfers (123 versus 127 versus 167 minutes; P<0.001). CONCLUSIONS: The Accelerator program increased uptake of key care processes, which were associated with improved system performance. These findings support efforts to implement regional ST-segment-elevation myocardial infarction networks focused on prehospital catheterization laboratory activation, single call transfer protocols, and emergency department bypass

Genetic Regulation of Platelet Receptor Expression and Function: Application in Clinical Practice and Drug Development

Understanding genetic contributions to platelet function could have profound clinical ramifications for personalizing platelet-directed pharmacotherapy, by providing insight into the risks and possible benefits associated with specific genotypes. This article represents an integrated summary of presentations related to genetic regulation of platelet receptor expression and function given at the Fifth Annual Platelet Colloquium in January 2010. It is supplemented with additional highlights from the literature covering 1) approaches to determining and evidence for the associations of genetic variants with platelet hypo- and hyperresponsive phenotypes, 2) the ramifications of these polymorphisms with regard to clinical responses to antiplatelet therapies, and 3) the role of platelet function/genetic testing in guiding antiplatelet therapy