What determines the size of liquid capillary condensates below the bulk melting point?

金沢大学理工研究域物質化学系Capillary condensation from vapor has been studied at temperatures below the bulk melting point Tm of the condensing substance using a surface force apparatus. Both mica and mica modified by self-assembly of a fluorinated surfactant (perfluoro-1H,1H,2H,2H-decylpyridinium chloride) have been used as substrate surfaces. The condensing liquids, cyclooctane and menthol, nearly wet (contact angle <15°) mica but show a high (∼60°) contact angle on the fluorinated surface. As in previous studies with unmodified mica, we find that both cyclooctane and menthol condense as liquids below Tm, and that the size of the condensates at solid-vapor coexistence is limited and inversely proportional to the temperature depression below Tm, or Ar. A comparison of the size of the condensates between the fluorocarbon surfaces and the mica surfaces and the quantitative dependence of the size of the condensate on ΔT for cyclooctane lead us to conclude that the maximum condensate size is determined by the equilibrium between condensed, "supercooled" liquid and vapor, and is hence proportional to the surface tension of the liquid-vapor interface. From a consideration of the equilibrium between a liquid and a hypothetical solid condensate, it is concluded that a solid condensate does not usually form for kinetic reasons although two exceptions were found in earlier work. © 2007 American Chemical Society

American thoracic society/national heart, lung, and blood institute asthma-chronic obstructive pulmonary disease overlap workshop report

Asthma and chronic obstructive pulmonary disease (COPD) are highly prevalent chronic obstructive lung diseases with an associated high burden of disease. Asthma, which is often allergic in origin, frequently begins in infancy or childhood with variable airflow obstruction and intermittent wheezing, cough, and dyspnea. Patients with COPD, in contrast, are usually current or former smokers who present after the age of 40 years with symptoms (often persistent) including dyspnea and a productive cough. On the basis of age and smoking history, it is often easy to distinguish between asthma andCOPD. However, some patients have features compatible with both diseases. Because clinical studies typically exclude these patients, their underlying disease mechanisms and appropriate treatment remain largely uncertain. To explore the status of and opportunities for research in this area, the NHLBI, in partnership with the American Thoracic Society, convened a workshop of investigators in San Francisco, California on May 14, 2016. At the workshop, current understanding of asthma-COPD overlap was discussed among clinicians, pathologists, radiologists, epidemiologists, and investigators with expertise in asthma and COPD. They considered knowledge gaps in our understanding of asthma-COPD overlap and identified strategies and research priorities that will advance its understanding. This report summarizes those discussions

Adsorption from pure and mixed vapours of n-hexane and n-perfluorohexane

We have used a modified surface force apparatus (SFA) to study adsorption onto mica surfaces from near-saturated vapours of $n$-hexane and $n$-perfluorohexane, and mixtures thereof. For relative vapour pressures in the range 0.9-0.998 the films adsorbed from vapours of the pure liquids range in thickness from 1 to 4 nm, in crude agreement with the predictions of non-retarded van der Waals-Lifshitz theory. The observed deviations from theory show a qualitative difference between the two liquids, which may reflect differences in the significance of structural contributions to the disjoining pressure. Under the same experimental conditions, adsorption from vapours of (one-phase) liquid mixtures gives rise to films which are significantly thicker, over a broad range of intermediate compositions, than those adsorbed from the pure vapours, with a broad maximum in thickness observed near the critical composition of the bulk liquid mixture

Adsorption of cetyltrimethylammonium bromide to mica surfaces below the critical micellar concentration

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Neutron reflectivity studies of critical adsorption behaviour of the surface scaling function

Neutron reflectometry has been employed to examine the nature of the critical adsorption surface scaling function for a near critical mixture of hexane d14 perfluorohexane adsorbing to a solid substrate from the liquid one phase region. The analysis method of Dietrich and Schack has been applied to examine the nature of the power law part of the critical adsorption surface scaling function, which has been found to behave as m z P0z amp; 8722;m as the critical point is approached. Values of m 0.514 0.018 and P0 0.90 0.04 have been obtained. These values are consistent with theoretical expectations mth 0.516 0.004; P0th 0.94 0.05 , the value determined from Monte Carlo simulations P0MC 0.866 , and other experimental determinations P0ex 0.955 0.0