Effects of process gas environment on platinum-inclusion density and dissolution rate in phosphate laser glasses

The effects of process gas environment on reducing the density of platinum inclusions in phosphate laser glasses are examined. The platinum inclusions originate from the crucibles used to melt the laser glass and can lead to optical damage in glasses used in highpeak- power lasers. The melting experiments examine the effects of N₂, O₂ and CI₂ gases on inclusion density and platinum dissolution rates. The more oxidizing the process gas conditions, the greater the dissolution rate (O₂ + CI₂ > O₂ » N₂). A thin-film mass transport model is used to analyze dissolution rate data for small plates of platinum over a range of temperatures from 1000 to 1200°C and oxygen fugacity of 10³ to 1 bar. At 1200°C the platinum dissolution rate is approximately 3.0- 10⁻⁸ (Pₒ₂)⁰⁷ (in g/(cm² * s)) where Pₒ₂ is the oxygen fugacity of the process gas in bar. Using CI₂ rather than O₂ causes a measurable increase in the optical absorption of the glass that may be due to either a red-shift and/or a greater absorption coefficient for the platinumchlorine complex

Effects of melting conditions on platinum-inclusion content in phosphate laser glasses

Results from small-scale glass melting experiments aimed at reducing the density of platinum particles in phosphate laser glasses are discussed. The platinum particles originate from the crucibles used to melt the laser glass and can cause optical damage in glasses used in high-peak-power lasers. The melting experiments examine the effects of a) temperature and temperature gradients; b) processing time; and c) O₂ atmosphere on the formation and dissolution of platinum inclusions in LG-750 phosphate laser glass. Results show that most platinum inclusions originate early in the melt cycle, with thermal gradients within the melter being one of the major causes. By using oxidizing conditions (O₂), the platinum inclusions can be dissolved into the glass during the course of the melt cycle. Results from the laboratory-scale melting experiments have been incorporated into a proprietary laser-glass melting process. The laser glass prepared under these conditions has an average of less than 0.1 platinum inclusions/1, which represents a 1000-fold reduction over the previously available phosphate laser glasses

Unlocking Community Capabilities Across Health Systems in Low- and Middle-Income Countries: Lessons Learned from Research and Reflective Practice

The right and responsibility of communities to participate in health service delivery was enshrined in the 1978 Alma Ata declaration and continues to feature centrally in health systems debates today. Communities are a vital part of people-centred health systems and their engagement is critical to realizing the diverse health targets prioritised by the Sustainable Development Goals and the commitments made to Universal Health Coverage. Community members' intimate knowledge of local needs and adaptive capacities are essential in constructively harnessing global transformations related to epidemiological and demographic transitions, urbanization, migration, technological innovation and climate change. Effective community partnerships and governance processes that underpin community capability also strengthen local resilience, enabling communities to better manage shocks, sustain gains, and advocate for their needs through linkages to authorities and services. This is particularly important given how power relations mark broader contexts of resource scarcity and concentration, struggles related to social liberties and other types of ongoing conflicts.IS

Different paths to the modern state in Europe: the interaction between domestic political economy and interstate competition

Theoretical work on state formation and capacity has focused mostly on early modern Europe and on the experience of western European states during this period. While a number of European states monopolized domestic tax collection and achieved gains in state capacity during the early modern era, for others revenues stagnated or even declined, and these variations motivated alternative hypotheses for determinants of fiscal and state capacity. In this study we test the basic hypotheses in the existing literature making use of the large date set we have compiled for all of the leading states across the continent. We find strong empirical support for two prevailing threads in the literature, arguing respectively that interstate wars and changes in economic structure towards an urbanized economy had positive fiscal impact. Regarding the main point of contention in the theoretical literature, whether it was representative or authoritarian political regimes that facilitated the gains in fiscal capacity, we do not find conclusive evidence that one performed better than the other. Instead, the empirical evidence we have gathered lends supports to the hypothesis that when under pressure of war, the fiscal performance of representative regimes was better in the more urbanized-commercial economies and the fiscal performance of authoritarian regimes was better in rural-agrarian economie

Ibicaba revisitada outra vez: espaço, escravidão e trabalho livre no oeste paulista

Ibicaba Farm, property of Senator Nicolau Pereira de Campos Vergueiro during the 19th century, was the subject of studies that focused on the experience with the sharecropping system. This article intends to undertake a revisit to Ibicaba through new lenses of observation. At first, it tries to insert Vergueiro's farm in the context of the changing World-economy of the first decades of the nineteenth century, and then highlight the importance of the spatial dimension of reality in this historical context. In the following two subitems, which constitute the core of the article, an analysis is made of the protocols - especially spatial - of control of the workers, used by the Vergueiros in order to extract the maximum of labor from slaves and sharecroppers, as well as the strategies that captives and immigrants used to escape from this surveillance. Finally, a brief recapitulation of the main points exposed and some considerations about the tensions that emerged in Ibicaba during the studied period are made.A Fazenda Ibicaba, propriedade do Senador Nicolau Pereira de Campos Vergueiro ao longo do século XIX, foi objeto de estudos que enfocaram a experiência com o sistema de parceria que ela abrigou. Este artigo pretende revisitar Ibicaba por meio de novas lentes de observação. Em um primeiro momento, buscar-se-á inserir a fazenda de Vergueiro no contexto de mudança pela qual a Economia-mundo passava nas primeiras décadas do Oitocentos para, em seguida, salientar a importância que a dimensão espacial da realidade cumpria nesse contexto histórico. Nos dois subitens seguintes, que constituem o núcleo do artigo, analisam-se os protocolos - sobretudo espaciais - de controle da mão de obra utilizados pelos Vergueiro, com vistas à máxima extração de trabalho de escravos e colonos, bem como as estratégias de que cativos e imigrantes lançaram mão para escapar dessa vigilância. Faz-se, ao fim, uma breve recapitulação dos principais pontos expostos e algumas considerações sobre as tensões que emergiram em Ibicaba durante o período estudado