Measurements of dynamic surface tension were carried out in aqueous systems (water or 0.1 mM Triton X-100) comprising nanoparticles formed from chemically modified polyaldehyde dextran (PAD). The nanostructures, considered as potential drug carriers in aerosol therapy, were obtained from biocompatible polysaccharides by successive oxidation and reactive coiling in an aqueous solution. The dynamic surface tension of the samples was determined by the maximum bubble pressure (MBP) method and by the axisymmetric drop shape analysis (ADSA). Experiments with harmonic area perturbations were also carried out in order to determine surface dilatational viscoelasticity. PAD showed a remarkable surface activity. Ward-Tordai equation was used to determine the equilibrium surface tension and diffusion coefficient of PAD nanoparticles (D = 2.3×10-6 m2/s). In a mixture with Triton X-100, PAD particles showed co-adsorption and synergic effect in surface tension reduction at short times (below 10 s). Tested nanoparticles had impact on surface rheology in a mixed system with nonionic surfactant, suggesting their possible interactions with the lung surfactant system after inhalation. This preliminary investigation sets the methodological approach for further research related to the influence of inhaled PAD nanoparticles on the lung surfactant and mass transfer processes in the respiratory system.
Outdoor remote temperature measurements in the infrared range can be very inaccurate because of the influence of solar radiation reflected from a measured object. In case of strong directional reflection towards a measuring device, the error rate can easily reach hundreds per cent as the reflected signal adds to the thermal emission of an object. As a result, the measured temperature is much higher than the real one. Error rate depends mainly on the emissivity of an object and intensity of solar radiation. The position of the measuring device with reference to an object and the Sun is also important. The method of compensation of such undesirable influence of solar radiation will be presented. It is based on simultaneous measurements in two different spectral bands, shor-twavelength and long-wavelength ones. The temperature of an object is derived from long-wavelength data only, whereas the short-wavelength band, the corrective one, is used to estimate the solar radiation level. Both bands were selected to achieve proportional changes of the output signal due to solar radiation. Knowing the relation between emissivity and solar radiation levels in both spectral bands, it is possible to reduce the measurement error several times.
In the article a non-uniformity correction method is presented which allows to compensate for the influence of detector’s temperature drift. For this purpose, dependency between output signal value and the temperature of the detector array was investigated. Additionally the influence of the temperature on the Offset and Gain coefficients was measured. Presented method utilizes estimated dependency between output signal of detectors and their temperature. In the presented method, the shutter is used for establishing signal reference. Thermoelectric cooler is used for changing the temperature of the detector array.
Transport properties of bronchial mucus are investigated by two-stage experimental approach focused on: (a) rheological properties and (b) mass transfer rate through the stagnant layer of solutions of mucus components (mucine, DNA, proteins) and simulated multi-component mucus. Studies were done using thermostated horizontal diffusion cells with sodium cromoglycate and carminic acid as transferred solutes. Rheological properties of tested liquids was studied by a rotational viscometer and a cone-plate rheometer (dynamic method). First part of the studies demonstrated that inter-molecular interactions in these complex liquids influence both rheological and permeability characteristics. Transfer rate is governed not only by mucus composition and concentration but also by hydrophobic/hydrophilic properties of transported molecules. Second part was focused on the properties of such a layer in presence of selected nanostructured particles (different nanoclays and graphene oxide) which may be present in lungs after inhalation. It was shown that most of such particles increase visco-elasticity of the mucus and reduce the rate of mass transfer of model drugs. Measured effects may have adverse impact on health, since they will reduce mucociliary clearance in vivo and slow down drug penetration to the bronchial epithelium during inhalation therapy.