Expiratory flow rate, breath hold and anatomic dead space influence electronic nose ability to detect lung cancer

BACKGROUND: Electronic noses are composites of nanosensor arrays. Numerous studies showed their potential to detect lung cancer from breath samples by analysing exhaled volatile compound pattern ("breathprint"). Expiratory flow rate, breath hold and inclusion of anatomic dead space may influence the exhaled levels of some volatile compounds; however it has not been fully addressed how these factors affect electronic nose data. Therefore, the aim of the study was to investigate these effects. METHODS: 37 healthy subjects (44 +/- 14 years) and 27 patients with lung cancer (60 +/- 10 years) participated in the study. After deep inhalation through a volatile organic compound filter, subjects exhaled at two different flow rates (50 ml/sec and 75 ml/sec) into Teflon-coated bags. The effect of breath hold was analysed after 10 seconds of deep inhalation. We also studied the effect of anatomic dead space by excluding this fraction and comparing alveolar air to mixed (alveolar + anatomic dead space) air samples. Exhaled air samples were processed with Cyranose 320 electronic nose. RESULTS: Expiratory flow rate, breath hold and the inclusion of anatomic dead space significantly altered "breathprints" in healthy individuals (p 0.05). These factors also influenced the discrimination ability of the electronic nose to detect lung cancer significantly. CONCLUSIONS: We have shown that expiratory flow, breath hold and dead space influence exhaled volatile compound pattern assessed with electronic nose. These findings suggest critical methodological recommendations to standardise sample collections for electronic nose measurements

Controllable synthesis and characterization of alumina/MWNT nanocomposites

The aim of this work is to develop a controllable synthesis pathway which produces a stable alumina layer on the surface of carbon nanotubes by impregnation method. Precursor compounds such as aluminium isopropoxide and aluminium-acetylacetonate were used to cover the surface of multiwalled carbon nanotubes (MWNTs) under different solvent conditions. As prepared alumina coverages were characterized by TEM, SEM, SEM-EDX, TG and X-ray diffraction techniques. Results revealed that homogeneous coverage can be achieved in a controllable way. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Chemical challenges during the synthesis of MWCNT-based inorganic nanocomposite materials

Multiwalled carbon nanotubes (MWCNTs) were successfully covered with metal oxides - such as TiO2, ZnO, Al2O3, SnO2, and In2O3 nanoparticles - with different preparation methods under solvent conditions. The applied synthesis techniques were impregnation, a hydrothermal process and a ball-milling method. As-prepared inorganic coverage layers were characterized by TEM, HRTEM, SEM, SEM-EDX, and X-ray diffraction techniques. Results revealed that the choice of synthesis technique affects the quality and the layer structure of the deposited inorganic particles on the surface of carbon nanotubes. These materials might be suitable for nanotechnology applications. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

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Analysis of MWCNT nanocomposite samples and results of MS2 filtratio

Photocatalytic activity of TiO2/SWCNT and TiO2/MWCNT nanocomposites with different carbon nanotube content

With different mass ratios, titanium dioxide/carbon nanotube (0.1-10 wt% CNTcontent) nanocomposites were prepared with the aid of ultrasonication method. The structures of the various TiO2/CNT nanocomposites were characterized by electron microscopy (scanning electron microscopy, transmission electron microscopy). Their photocatalytic activity was tested by the degradation of phenol in aqueous solution under near-UV irradiation. In parallel experiments, both (SW and MW) CNT samples were treated in a reflux system with nitric acid to functionalize the nanotubes, subsequently preparing the nanocomposites in the same method. At higher CNT concentration (5, 10 wt%) the nanocomposites exhibited lower photocatalytic activity compared to the samples with lower CNT concentration, probably because the higher CNT concentration reduces the light intensity on the surfaces of TiO2 particles. Our aim was to find the best synthesis method and the optimal composition of the TiO2/CNT nanocomposites for the degradation of phenol under UV irradiation. The highest degradation rate was achieved with Aldrich anatase/functionalized single wall carbon nanotube nanocomposite (AA+f-SW1 wt%). The photocatalytic activity of this sample was significantly higher compared to the bare Aldrich anatase and Aeroxide P25 titanium dioxide reference samples which were the best photocatalysts among the investigated bare titanias. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Fabrication of homogeneous titania/MWNT composite materials

MWNT/titania nanocomposites were prepared by an impregnation method and subsequent heat treatment at 400 degrees C. Precursor compounds such as titanium (IV) propoxide and titanium (IV) ethoxide were used to cover the surface of CNTs under solution conditions. Electron microscopy and X-ray diffraction techniques were carried out to characterize the as-prepared titania layers. (C) 2011 Elsevier Ltd. All rights reserved