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Understanding concentration distributions, release sites, and release dynamics of volatile organic compounds (VOCs) from the human is expected to lead to methods for noninvasive disease screening and assessment of metabolisms. In this study, we developed a visualization system (sniff-cam) that enabled one to identify a spatiotemporal change of gaseous acetaldehyde (AcH) in real-time. AcH sniff-cam was composed of a camera, a UV-LED array sheet, and an alcohol dehydrogenase (ADH)-immobilized mesh. A reverse reaction of ADH was employed for detection of gaseous AcH where a relationship between fluorescence intensity from nicotinamide adenine dinucleotide and the concentration of AcH was inversely proportional; thus, the concentration distribution of AcH was measured by detecting the fluorescence decrease. Moreover, the image differentiation method that calculated a fluorescence change rate was employed to visualize a real-time change in the concentration distribution of AcH. The dynamic range of the sniff-cam was 0.1-10 ppm which encompassed breath AcH concentrations after drinking. Finally, the sniff-cam achieved the visualization of the concentration distribution of AcH in breath and skin gas. A clear difference of breath AcH concentration was observed between aldehyde dehydrogenase type 2 active and inactive subjects, which was attributed to metabolic capacities of AcH. AcH in skin gas showed a similar time course of AcH concentration to the breath and a variety ofrelease concentration distribution. Using different NADH-dependent dehydrogenases in the sniff-cam could lead to a versatile method for noninvasive disease screening by acquiring spatiotemporal information on various VOCs in breath or skin gas. [ABSTRACT FROM AUTHOR]

Various volatile organic compounds can be found in human transpiration, breath and body odor. In this paper, a novel two-dimensional fluorometric imaging system, known as a "sniffer-cam" for ethanol vapor released from human breath and palm skin was constructed and validated. This imaging system measures ethanol vapor concentrations as intensities of fluorescence through an enzymatic reaction induced by alcohol dehydrogenase (ADH). The imaging system consisted of multiple ultraviolet light emitting diode (UV-LED) excitation sheet, an ADH enzyme immobilized mesh substrate and a high-sensitive CCD camera. This imaging system uses ADH for recognition of ethanol vapor. It measures ethanol vapor by measuring fluorescence of nicotinamide adenine dinucleotide (NADH), which is produced by an enzymatic reaction on the mesh. This NADH fluorometric imaging system achieved the two-dimensional real-time imaging of ethanol vapor distribution (0.5-200 ppm). The system showed rapid and accurate responses and a visible measurement, which could lead to an analysis of metabolism function at real time in the near future. [ABSTRACT FROM AUTHOR]

Continuous hydrothermal synthesis of Fe2O3nanoparticles was carried out at 673 K and 30 MPa. Two types of mixers, a conventional T-type micromixer and a central collision-type micromixer (CCM), were used for the synthesis. CCM was newly fabricated on the basis of the concept for preventing heterogeneous nucleation induced on the inner wall of the mixer. Residence time and Fe(NO3)3molality of the starting solution varied from 0.1 to 1.0 s and 0.05 to 0.50 mol/kg, respectively. Effects of the mixer structure, the residence time, and the Fe(NO3)3molality on crystal structure, Fe3犉묢, average particle size, and size distribution were discussed. CCM effectively worked for producing smaller Fe2O3nanoparticles with narrow and monomodal distribution. [ABSTRACT FROM AUTHOR]

Ferrite nanoparticles from Fe(NO3)3and Me(NO3)2(Me Ni, Cu, Zn) aqueous solutions could be synthesized continuously with a flow reactor at 673 K, 30 MPa, and 4 s residence time. The particles were characterized by TEM, XRD, and ICP to obtain sizes, crystal structures, lattice parameters, and Me/Fe molar ratios. Solid-solution nanoparticles of MeFe2O4and -Fe2O3with a cubic spinel structure and an average particle size under 10 nm were obtained. Conversion of Fe3was more than 0.97 at the given residence time, and conversions of Me2increased from 0 to 0.62 with increasing residence time. The particle size increased with increasing residence time, and no significant difference in divalent cations was observed. The Me/Fe molar ratio in the obtained solid-solution nanoparticles of MeFe2O4and -Fe2O3increased with increasing residence time and KOH molality. The Me/Fe molar ratio also increased in the order Zn < Cu < Ni at a given residence time, and this trend could be explained on the basis of ZnO, CuO, and NiO solubilities. The increase of the size and the Me/Fe molar ratio in the obtained particles with increasing residence time shows that, in the formation mechanism, primary solid-solution particles with low Me/Fe molar ratios probably nucleated and, after surface dissolution of the particles, dissolved Fe3recrystallized on the surface with incorporation of Me2. [ABSTRACT FROM AUTHOR]