A study of the decomposition behaviour for Ammonium Perchlorate(AP) was carried out by differential thermal analysis and the two decomposition peaks were observed. The high temperature peak was found to shift to lower temperatures, but the corresponding shift in the low temperature peak was smaller due to the effect of nanometer metal powders. Results shows that Cu and NiCu nanopowders decreased both the high and low decomposition temperature, while Ni and Al nanopowders just decreased the high decomposition temperature and increased the low decomposition temperature. Metal micron‐sized powders show catalytic effects on the thermal decomposition of AP, but their effects are less than that of nanometer metal powders. With the increase in content, nanometer metal powders enhanced their catalytic effect on the high temperature decomposition of AP, however their effect was weakened on the low temperature decomposition.

Pulmonary surfactant (PS) is a lipid-protein complex that adsorbs to the air-water surface of the lung as a thin film. Previous studies have suggested that the adsorbed PS film is composed of an interfacial monolayer, plus a functionally attached vesicular complex, called the surface-associated surfactant reservoir. However, direct visualization of the lateral structure and morphology of adsorbed PS films using atomic force microscopy (AFM) has been proven to be technically challenging. To date, all AFM studies of the PS film have relied on the model of Langmuir monolayers. Here, we showed the first, to our knowledge, AFM imaging of adsorbed PS films under physiologically relevant conditions using a novel, to our knowledge, experimental methodology called constrained drop surfactometry. In conjunction with a series of methodological innovations, including subphase replacement, in situ Langmuir-Blodgett transfer, and real-time surface tension control using closed-loop axisymmetric drop shape analysis, constrained drop surfactometry allowed the study of lateral structure and topography of animal-derived natural PS films at physiologically relevant low surface tensions. Our data suggested that a nucleation-growth model is responsible for the adsorption-induced squeeze-out of the PS film, which likely results in an interfacial monolayer enriched in dipalmitoylphosphatidylcholine with the attached multilayered surface-associated surfactant reservoir. These findings were further supported by frequency-dependent measurements of surface dilational rheology. Our study provides novel, to our knowledge, biophysical insights into the understanding of the mechanisms by which the PS film attains low surface tensions and stabilizes the alveolar surface.

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With the rapid development of nanotechnology and an increasing use of nanoenabled consumer products, there is an urgent need to develop precautionary tools to evaluate acute lung toxicity of engineered nanomaterials (ENMs). As natural pulmonary surfactant (PS) film represents the initial barrier of nano–bio interactions in the lungs, a novel in vitro experimental method, called constrained drop surfactometry (CDS), is developed to quantitatively evaluate PS inhibition caused by ENMs. The results show that at a very low concentration, four representative ENMs, including carbon nanotubes, graphene oxide, zinc oxide, and silver nanoparticles, all increase in vitro minimum surface tension of a modified natural PS, Infasurf. These in vitro results are related to the extensive alveolar collapse and inflammation observed in vivo in mice exposed to these ENMs in an intratracheal instillation model. Thus, there may be a direct correlation between in vitro surface tension increase due to PS inhibition by ENMs and in vivo lung toxicity revealed by alveolar collapse and inflammation. Compared to commonly used animal models, CDS holds great promise for the development of an animal‐free, easy‐to‐use, and low‐cost precautionary assay for the prediction of acute lung toxicity of inhaled ENMs.

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