RESUMEN
In this article, we present a versatile gas detector that can operate on an unmanned aerial vehicle (UAV) or unmanned ground vehicle (UGV). The device has six electrochemical modules, which can be selected to measure specific gases, according to the mission requirements. The gas intake is realized by a miniaturized vacuum pump, which provides immediate gas distribution to the sensors and improves a fast response. The measurement data are sent wirelessly to the operator's computer, which continuously stores results and presents them in real time. The 2 m tubing allows measurements to be taken in places that are not directly accessible to the UGV or the UAV. While UAVs significantly enhanced the versatility of sensing applications, point gas detection is challenging due to the downwash effect and gas dilution produced by the rotors. In our work, we demonstrated the method of downwash effect reduction at aerial point gas measurements by applying a long-distance probe, which was kept between the UAV and the examined object. Moreover, we developed a safety connection protecting the UAV and sensor in case of accidental jamming of the tubing inside the examined cavity. The methods presented provide an effective gas metering strategy using UAVs.
RESUMEN
We calculate the minimum energy paths and reaction energies of the adsorption of the epoxide adhesive components diglycidylesterbisphenol A (DGEBA), diethyltriamine (DETA), and the adhesion promoter 3-aminopropylmethoxysilane (AMEO) at two different sites on a model of the native Al2O3 surface, using the nudged elastic band algorithm in conjunction with self-consistent charge-density functional based tight binding. Our results show that the chosen combination of methods is well suited to obtain an overview of the reaction mechanisms and kinetics of the adsorption of organic molecules on inorganic surfaces. The obtained MEP-s show that there is preference for the adsorption of the adhesion promoter, AMEO, over the resin, DGEBA, while the adsorption of the curing agent, DETA, is unfavorable. Our approach also gives an insight into the ranges of the mechanical and electronic influences of the adsorption process on the interface, which neither full ab initio methods nor force field approaches can provide. These results will help to develop a quantum mechanics-molecular mechanics multiscale embedding scheme for more detailed studies of organic/inorganic hybrid interface reactions.
RESUMEN
We investigate the competition of the various organic components of two representative adhesive systems for reactive defect sites at model surfaces of both SiO2 and Al2O3. The reaction energies of resin monomers, curing agents, and in some cases also of additional adhesion promoters with the defects are calculated. We applied a density-functional based tight-binding method including a self-consistent correction of the Mulliken charges, which has already proven to be a useful tool for computational materials science, delivering reliable structural and energetic information.
RESUMEN
Aim of the study was to investigate the potential toxic effects of di-n-butylamine (DBA), a known skin and eye irritating compound, on the respiratory tract after inhalation exposure for up to 91 days in male and female rats [Crl:(WI)WU BR]. To check whether and to what degree the no-observed-(adverse)-effect level (NO(A)EL) decreases with increasing study duration, serial sacrifices were performed after 3 and 28 days, respectively. Based on two dose range-finding studies, the concentrations for this study were determined with 0 (clean air), 50, 150, and 450 mg/m(3). Animals were exposed for 3 days (6 h/day) 28, and 91 days (5 days/wk, 6 h/day), respectively, and immediately sacrificed thereafter. The results show clear irritating effects only in the upper part of the respiratory tract, that is, the nasal cavities. While after 3 and 28 days effects were found only in the high-dose group, slight adaptive effects, expressed as mucous (goblet) cell hyperplasia, could be diagnosed in the medium- and low-dose groups after 91 days of exposure. Pathological changes were most prominent after 3 days of exposure. In the lung, only marginal effects could be observed (increased relative lung weight only in females of the high concentration after 28 days, slight, not statistically significant histopathological effects in the high concentration after 3 days, no effects on parameters of bronchoalveolar lavage fluid), while no effects were found in the remaining groups.