Water in opal – what can it tell us?

Opal is a hydrous silica composed of predominantly silicon dioxide and water. The chemical composition of opal is normally described by the general formula SiO2.nH2O. The formula indicates that opal contains water and the value of ‘n’ is variable so the water content is variable and is known to range widely. Such a simple formula hides much of the important characteristics of how water is contained in opal and the variability in the water content and states of water is intricately involved in the formation of opal and may influence properties of the opal as a gemstone. The understanding of the states of water in opal is therefore of importance. The way in which the water is contained provides clues to the mechanisms of formation of opal. The water contained may also be used as a probe to help elucidate the complex microstructure beyond the sphere array structure in which precious opal, in particular, is described. This article will outline the types of water present in opal that displays play-of colour (POC) and how these types have been determined using chemical and physical laboratory characterisation techniques

Pure strain brand seed potatoes /

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Spring price list, 1931 /

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Spring price list, 1932 /

193

Multicenter treat-to-treat cost-effectiveness evaluation of HMG-CoA reductase inhibitor monotherapy

Purpose: HMG-CoA reductase inhibitors have become the drugs of choice for hypercholesterolemia, demonstrating a favorable side effect profile, ease of administration, and reduction of cardiovascular mortality in both primary and secondary prevention trials. Use of these agents has been suboptimal, however, possibly due to their cost. The objective of this study was to evaluate the cost-effectiveness of the five commercially available HMG-CoA reductase inhibitors in a large population of hypercholesterolemic patients using a population-based treat-to-target analysis. Methods: Cardiac risk factors (CRFs) and lipid panels were collected for drug-naive patients from five different regions of the United States. Risk stratification using CRFs was performed, and LDL-cholesterol (LDL-C) was based on national guidelines. Using meta-analysis to derive LDL-C lowering efficacy, each agent was modeled to achieve NCEP goals. Costing methodology was done using a third-party payer perspective. Drug costs were extracted from Medi-span, and clinic costs were based on CPT codes for office visits and lipid panels. Results: Data were obtained for 5436 patients: high-risk (coronary artery disease [CAD]; n=1773), moderate-risk (no CAD and more than 2 CRFs; n=1318), and low-risk patients (no CAD and fewer than 2 CRFs; n=2345). High-risk, moderate-risk, and low-risk patients achieving LDL-C target with the primary agent, respectively, were: atorvastatin 100%, 100%, 100%; fluvastatin 4%, 74%, 100%; lovastatin 25%, 100%, 100%; pravastatin 25%, 95%, 100%; and simvastatin 89%, 100%, 100%. Yearly US dollar cost per patient to treat to goal LDL-C are shown in the table below. Conclusions: The most cost-effective approach to treating a population with varying degrees of coronary heart disease risk is to individualize statin selection based on the expected LDL-C percentage required to achieve NCEP target. This approach would indicate that low-risk patients can be treated with fluvastatin and moderate-risk and high-risk patients with atorvastatin or fluvastatin. Notably, atorvastatin was the only agent achieving NCEP goals in patients in all risk groups

Northern grown, pure strain brand seed potatoes : February 1st price list, 1937 /

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