RESUMEN
In 1926, during an economic crisis that severely impacted the mining industry, Guggenheim Brothers, the Guggenheim family business, implemented a new technological system to extract saltpeter from the Atacama Desert in northern Chile. Known as the Guggenheim system, this cutting-edge technological innovation had a significant impact on regional society and facilitated the introduction of Chilean saltpeter into the global fertilizer market. For this system to succeed, however, it had to incorporate a sociopolitical strategy based on a highly hierarchical and well-controlled labor force. Through their political and cultural influence in the region, the Guggenheim family's industry transformed a remote area into a state periphery, creating new ways of inhabiting the desert within a strict framework in which workers' lives were regulated by company-imposed labor discipline. With more political power than the state, the Guggenheim family sought to suppress any social agency deemed dangerous to the production of saltpeter.
Asunto(s)
Clima Desértico , Minería , Chile , Minería/historia , Historia del Siglo XX , Nitratos/historia , Humanos , PolíticaRESUMEN
Trace analysis is usually associated with high-sensitivity analysis instrumentation. It became fully established from the 1960s following consensus among different groups of practitioners over protocols, reference materials, sensitivity, and accuracy and precision. As a consequence, wet chemical methods have been relegated to a secondary role, contrasting with their tremendous historical significance in detecting, identifying, and estimating small amounts of material. This is particularly relevant to the state-of-the-science analytical determinations stimulated by the effect of minor components in commodities of commercial importance. Here, I select a single example: attempts made during the 1890s to determine the amount of potassium perchlorate (KCIO4) that occurs in Chile saltpetre (sodium nitrate). The application of titrimetry, particularly the adaptation of Volhard's method for chloride analysis, was crucial in the efforts to estimate perchlorate in the nitrate used for explosives and to track the impact of perchlorate concentrations on certain important agricultural crops.
Asunto(s)
Nitratos/historia , Percloratos/historia , Compuestos de Potasio/historia , Volumetría/historia , Historia del Siglo XIX , Nitratos/análisis , Percloratos/análisis , Compuestos de Potasio/análisisRESUMEN
OBJETIVO - Avaliar o efeito sublingual do mononitrato-5 de isossobida (MN5IS) e nitroglicerina (NTG) sobre o diâmetro luminal de artérias coronárias epicárdicas, pressão arterial média e efeitos colaterais. MÉTODOS - Cinqüenta pacientes foram submetidos a cateterismo cardíaco e cinecoronariografia, na condição inicial e 5 min após administração sublingual de MN5IS grupo A (GA) ou NTG grupo B (GB). RESULTADOS - O diâmetro coronário de referência aumentou em ambos os grupos, sem significância estatística entre os mesmos. Nos GA e GB foram demosntrados uma diminuição (1,66mmHg) e um aumento (0,79mmHg) na pressão arterial média, respectivamente (p=0,123). Não foram observados efeitos colaterais com o uso destas drogas. CONCLUSÄO - MN5IS sublingual é uma alternativa à administração de NTG durante cinecoronariografia e representa um alternativa terapêutica para o tratamento de doença cardíaca isquêmica.
Asunto(s)
Humanos , Enfermedad Coronaria , Angina Microvascular , Nitratos/historia , Nitroglicerina , Vasodilatadores , Administración Sublingual , Incidencia , Monitoreo FisiológicoRESUMEN
Revisao sobre os aspectos historicos e farmacologicos basicos dos nitratos com enfase em suas indicacoes consagradas en estados anginosos e no infartop do miocardio, bem como definicao das principais normatizacoes modernas para a obtencao dos melhores resultados medicos no emprego destes compostos: menor dosagem maior intervalo prescricional e tentativa de reposicao sulfidrica, com selecao individualizada de casos. O futuro do emprego de nitratos em cardiologia deveria compreender o emprego de formulacoes seguras e estaveis.