Studies of long-life pulsed CO2 laser with Pt/SnO2 catalyst

Closed-cycle CO2 laser testing with and without a catalyst and with and without CO addition indicate that a catalyst is necessary for long-term operation. Initial results indicate that CO addition with a catalyst may prove optimal, but a precise gas mix has not yet been determined. A long-term run of 10 to the 6th power pulses using 1.3% added CO and a 2% Pt on SnO2 catalyst yields an efficiency of about 95% of open-cycle steady-state power. A simple mathematical analysis yields results which may be sufficient for determining optimum running conditions. Future plans call for testing various catalysts in the laser and longer tests, 10 to the 7th power pulses. A Gas Chromatograph will be installed to measure gas species concentration and the analysis will be slightly modified to include neglected but possibly important parameters

Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers

Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed

Catalysts for long-life closed-cycle CO2 lasers

Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin (IV) oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-LaRC on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) achievement of 98% to 100% conversion of a stoichiometric mixture of CO and O2 to CO2 for 318 hours (greater than 1 x 10 to the 6th power seconds), continuous, at a catalyst temperature of 60 C, and (2) development of a technique verified in a 30-hour test, to prevent isotopic scrambling when CO-18 and O-18(2) are reacted in the presence of a common-isotope Pt/Sn O-16(2) catalyst

Reactivation of a tin oxide-containing catalyst

A method for the reactivation of a tin oxide-containing catalyst of a CO.sub.2 laser is provided. First, the catalyst is pretreated by a standard procedure. When the catalyst experiences diminished activity during usage, the heated zone surrounding the catalyst is raised to a temperature which is the operating temperature of the laser and 400.degree. C. for approximately one hour. The catalyst is exposed to the same laser gas mixture during this period. The temperature of the heated zone is then lowered to the operating temperature of the CO.sub.2 laser

Air pollution and cardiovascular disease: A Statement for Healthcare Professionals From the Expert Panel on Population and Prevention Science of the American Heart Association

Air pollution is a heterogeneous, complex mixture of gases, liquids, and particulate matter. Epidemiological studies have demonstrated a consistent increased risk for cardiovascular events in relation to both short- and long-term exposure to present-day concentrations of ambient particulate matter. Several plausible mechanistic pathways have been described, including enhanced coagulation/thrombosis, a propensity for arrhythmias, acute arterial vasoconstriction, systemic inflammatory responses, and the chronic promotion of atherosclerosis. The purpose of this statement is to provide healthcare professionals and regulatory agencies with a comprehensive review of the literature on air pollution and cardiovascular disease. In addition, the implications of these findings in relation to public health and regulatory policies are addressed. Practical recommendations for healthcare providers and their patients are outlined. In the final section, suggestions for future research are made to address a number of remaining scientific questions

2014 Evidence-based guideline for the management of high blood pressure in adults: Report from the panel members appointed to the Eighth Joint National Committee (JNC 8)

"Hypertension is the most common condition seen in primary care and leads to myocardial infarction, stroke, renal failure, and death if not detected early and treated appropriately. Patients want to be assured that blood pressure (BP) treatment will reduce their disease burden, while clinicians want guidance on hypertension management using the best scientific evidence. This report takes a rigorous, evidence-based approach to recommend treatment thresholds, goals, and medications in the management of hypertension in adults. Evidence was drawn from randomized controlled trials, which represent the gold standard for determining efficacy and effectiveness. Evidence quality and recommendations were graded based on their effect on important outcomes. There is strong evidence to support treating hypertensive persons aged 60 years or older to a BP goal of less than 150/90 mm Hg and hypertensive persons 30 through 59 years of age to a diastolic goal of less than 90 mm Hg; however, there is insufficient evidence in hypertensive persons younger than 60 years for a systolic goal, or in those younger than 30 years for a diastolic goal, so the panel recommends a BP of less than 140/90 mm Hg for those groups based on expert opinion. The same thresholds and goals are recommended for hypertensive adults with diabetes or nondiabetic chronic kidney disease (CKD) as for the general hypertensive population younger than 60 years. There is moderate evidence to support initiating drug treatment with an angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, calcium channel blocker, or thiazide-type diuretic in the nonblack hypertensive population, including those with diabetes. In the black hypertensive population, including those with diabetes, a calcium channel blocker or thiazide-type diuretic is recommended as initial therapy. There is moderate evidence to support initial or add-on antihypertensive therapy with an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in persons with CKD to improve kidney outcomes. Although this guideline provides evidence-based recommendations for the management of high BP and should meet the clinical needs of most patients, these recommendations are not a substitute for clinical judgment, and decisions about care must carefully consider and incorporate the clinical characteristics and circumstances of each individual patient.

AHA/ACCF secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular disease: 2011 update

"Since the 2006 update of the American Heart Association (AHA)/American College of Cardiology Foundation (ACCF) guidelines on secondary prevention (1), important evidence from clinical trials has emerged that further supports and broadens the merits of intensive risk-reduction therapies for patients with established coronary and other atherosclerotic vascular disease, including peripheral artery disease, atherosclerotic aortic disease, and carotid artery disease. In reviewing this evidence and its clinical impact, the writing group believed it would be more appropriate to expand the title of this guideline to “Secondary Prevention and Risk Reduction Therapy for Patients With Coronary and Other Atherosclerotic Vascular Disease.” Indeed, the growing body of evidence confirms that in patients with atherosclerotic vascular disease, comprehensive risk factor management reduces risk as assessed by a variety of outcomes, including improved survival, reduced recurrent events, the need for revascularization procedures, and improved quality of life. It is important not only that the healthcare provider implement these recommendations in appropriate patients but also that healthcare systems support this implementation to maximize the benefit to the patient. Compelling evidence-based results from recent clinical trials and revised practice guidelines provide the impetus for this update of the 2006 recommendations with evidence-based results (2–165) (Table 1). Classification of recommendations and level of evidence are expressed in ACCF/AHA format, as detailed in Table 2. Recommendations made herein are largely based on major practice guidelines from the National Institutes of Health and updated ACCF/AHA practice guidelines, as well as on results from recent clinical trials. Thus, the development of the present guideline involved a process of partial adaptation of other guideline statements and reports and supplemental literature searches. The recommendations listed in this document are, whenever possible, evidence based. Writing group members performed these relevant supplemental literature searches with key search phrases including but not limited to tobacco/smoking/smoking cessation; blood pressure control/hypertension; cholesterol/hypercholesterolemia/lipids/lipoproteins/dyslipidemia; physical activity/exercise/exercise training; weight management/overweight/obesity; type 2 diabetes mellitus management; antiplatelet agents/anticoagulants; renin/angiotensin/aldosterone system blockers; β-blockers; influenza vaccination; clinical depression/depression screening; and cardiac/cardiovascular rehabilitation. Additional searches cross-referenced these topics with the subtopics of clinical trials, secondary prevention, atherosclerosis, and coronary/cerebral/peripheral artery disease. These searches were limited to studies, reviews, and other evidence conducted in human subjects and published in English. In addition, the writing group reviewed documents related to the subject matter previously published by the AHA, the ACCF, and the National Institutes of Health.

AHA/ACCF secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular disease: 2011 update: A guideline from the American Heart Association and American College of Cardiology Foundation

"Since the 2006 update of the American Heart Association (AHA)/American College of Cardiology Foundation (ACCF) guidelines on secondary prevention,1 important evidence from clinical trials has emerged that further supports and broadens the merits of intensive risk-reduction therapies for patients with established coronary and other atherosclerotic vascular disease, including peripheral artery disease, atherosclerotic aortic disease, and carotid artery disease. In reviewing this evidence and its clinical impact, the writing group believed it would be more appropriate to expand the title of this guideline to “Secondary Prevention and Risk Reduction Therapy for Patients With Coronary and Other Atherosclerotic Vascular Disease.” Indeed, the growing body of evidence confirms that in patients with atherosclerotic vascular disease, comprehensive risk factor management reduces risk as assessed by a variety of outcomes, including improved survival, reduced recurrent events, the need for revascularization procedures, and improved quality of life. It is important not only that the healthcare provider implement these recommendations in appropriate patients but also that healthcare systems support this implementation to maximize the benefit to the patient. Compelling evidence-based results from recent clinical trials and revised practice guidelines provide the impetus for this update of the 2006 recommendations with evidence-based results2–165 (Table 1). Classification of recommendations and level of evidence are expressed in ACCF/AHA format, as detailed in Table 2. Recommendations made herein are largely based on major practice guidelines from the National Institutes of Health and updated ACCF/AHA practice guidelines, as well as on results from recent clinical trials. Thus, the development of the present guideline involved a process of partial adaptation of other guideline statements and reports and supplemental literature searches. The recommendations listed in this document are, whenever possible, evidence based. Writing group members performed these relevant supplemental literature searches with key search phrases including but not limited to tobacco/smoking/smoking cessation; blood pressure control/hypertension; cholesterol/hypercholesterolemia/lipids/lipoproteins/dyslipidemia; physical activity/exercise/exercise training; weight management/overweight/obesity; type 2 diabetes mellitus management; antiplatelet agents/anticoagulants; renin/angiotensin/aldosterone system blockers; β-blockers; influenza vaccination; clinical depression/depression screening; and cardiac/cardiovascular rehabilitation. Additional searches cross-referenced these topics with the subtopics of clinical trials, secondary prevention, atherosclerosis, and coronary/cerebral/peripheral artery disease. These searches were limited to studies, reviews, and other evidence conducted in human subjects and published in English. In addition, the writing group reviewed documents related to the subject matter previously published by the AHA, the ACCF, and the National Institutes of Health.