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Susceptible workers exposed to coal mine and silica dust may develop a variety of pulmonary diseases. The prime example is classical pneumoconiosis, a nodular interstitial lung disease that, in severe cases, may lead to progressive massive fibrosis (PMF) . Exposure to silica and coal mine dusts may also result in pulmonary scarring in a pattern that mimics idiopathic pulmonary fibrosis, and in chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis, that appears indistinguishable from obstructive lung disease caused by exposure to tobacco smoke. Coal mine and silica dust may therefore result in restrictive, obstructive, or mixed patterns of impairment on pulmonary function testing. Most physicians are aware of the nodular fibrosing pulmonary tissue reactions in response to retained dust, but they may not realize that these other reactions of the pulmonary parenchyma and airways to dust exist and can result in significant respiratory dysfunction in sensitive individuals. This article discusses current data on exposure to coal mine and silica dust in the United States, the epidemiology of the diseases caused by these exposures, and new concepts of causation and pathogenesis. We also review the patterns of pulmonary disease and impairment that may result. [ABSTRACT FROM AUTHOR]

Abstract  Two distinct oligomeric species of similar mass and chemical functionality (M w≈2,000 g/mol), one a linear methyl methacrylate oligomer (radius of gyration R g≈1.1 nm) and the other a hybrid organic–inorganic polyhedral silsesquioxane nanocage (methacryl-POSS, r≈1.0 nm), were subjected to thermal and rheological tests to compare the behaviors of these geometrically dissimilar molecules over the entire composition range. The glass transition temperatures of the blends varied monotonically between the glass transition temperatures of the pure oligomer (T g=−47.3°C) and the pure POSS (T g=−61.0°C). Blends containing high POSS contents (with volume fraction φ POSS≥0.90) exhibited enhanced enthalpy relaxation in differential scanning calorimetry (DSC) measurements, and the degree of enthalpy relaxation was used to calculate the kinetic fragility indices m of the oligomeric MMA (m=59) and the POSS (m=74). The temperature dependences of the viscosities were fitted by the free-volume based Williams–Landel–Ferry (WLF) and Vogel–Fulcher–Tammann (VFT) framework and a dynamic scaling relation. The calculated values of the fragility from the WLF–VFT fits were similar for the POSS (m=82) and for the oligomer (m=76), and the dynamic scaling exponent was similar for the oligomeric MMA and the POSS. Within the range of known fragilities for glass-forming liquids, the temperature dependence of the viscosity was found to be similarly fragile for the two species. The difference in shape of the nanocages and oligomer chains is unimportant in controlling the glass-forming properties of the blends at low volume fractions (φ POSS<0.20). However, at higher volume fractions, adjacent POSS cages begin to crowd each other, leading to an increase in the fractional free volume at the glass transition temperature and the observed enhanced enthalpy relaxation in DSC. [ABSTRACT FROM AUTHOR]

We examine the knowledge base for community-based mental health services for youth and their families. A brief historical perspective on the development of community services is presented, and the fundamental components of a comprehensive child mental health service system are described. Outcome studies for service components as well as the service system as a whole are summarized. Research related to the context of treatment, i.e., service setting cost, is presented. The authors conclude that a research base for child and family services is emerging but there is still a paucity of well designed studies that address the complexities of a community-based system as well as the critical outcome questions that need to be addressed. Finally, promising service system developments are described and recommendations for future research are presented. [ABSTRACT FROM AUTHOR]