Formaldehyde (HCHO) emitted from the furniture and the walls in the rooms injures the eyes, nose, and respiratory organs and causes allergies, which is called sick house syndrome. We designed and synthesized novel colorimetric HCHO-sensing molecules (KD-XA01 and KD-XA02) which possess an enaminone structure and developed a hand-held instrument to monitor indoor HCHO gas with the use of KD-XA01. These sensing molecules produced speedy color changes from colorless to yellow under mild conditions, which was caused by the fact that the enaminone structure in the reagent reacts with HCHO to give a lutidine derivative. This reaction took place not only in the solution phase but also in the solid phase (surface of the cellulose paper). To take advantage of this phenomena, a handy and rapid monitoring system has been developed for detecting indoor HCHO gas using a highly sensitive and selective detection tablet constructed from the porous cellulose paper that contains silica gel as an adsorbent, KD-XA01, and phosphoric acid under optimum conditions. This instrument detected the surface color change of the tablet from white to yellow, which was monitored as a function of the intensity of the reflected light illuminated by an LED (475 nm). The response was proportional to the HCHO concentration at a constant sampling time and flow rate; 0.05 ppm HCHO, which is under the standard value set by the World Health Organization, was able to be detected in 5 min. The detection limit was 0.005 ppm. This monitoring system was not interfered by carbonyl compounds such as acetaldehyde and acetone, alcohols, hydrocarbons, and typical gases such as carbon monoxide, carbon dioxide, nitrogen dioxide, etc., which contributes to the measurement of correct HCHO concentrations. It was possible to monitor the HCHO gas in the room of a new apartment and school using this instrument; the response values were in good agreement with those obtained by the standard DNPH method. This highly sensitive, selective, and handy HCHO gas monitor is widely applicable and convenient for users who are not specialists in this field.

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Drift tube ion mobility spectrometry with a novel atmospheric electron emission (AEE) source was developed for determination of gaseous and blister chemical warfare agents (CWAs) in negative mode. The AEE source was fabricated from an aluminum substrate electrode covered with 1 μm silver nanoparticle-dispersed silicone resin and a thin gold layer. This structure enabled stable tunneling electron emission upon the application of more than 11 V potential under atmospheric pressure. The reactant ion peak (RIP) was observed for the reduced mobility constant (K 0) of 2.18 and optimized at the charging voltage of 20 V. This RIP was assigned to O2 – by using a mass spectrometer. Hydrogen cyanide was detected as a peak (K 0 = 2.47) that was discriminatively separated from the RIP (resolution = 1.4), with a limit of detection (LOD) of 0.057 mg/m3, and assigned to CN– and OCN–. Phosgene was detected as a peak (K 0 = 2.36; resolution = 1.2; and LOD = 0.6 mg/m3), which was assigned to Cl–. Lewisite 1 was detected as two peaks (K 0 = 1.68 and 1.34; LOD = 12 and 15 mg/m3). The K 0 = 1.68 peak was ascribed to a mixture of adducts of molecules or the product of hydrolysis with oxygen or chloride. Cyanogen chloride, chlorine, and sulfur mustard were also well detected. The detection performance with the AEE source was compared with those under corona discharge and 63Ni ionizations. The advantage of the AEE source is the simple RIP pattern (only O2 –), and the characteristic marker ions contribute to the discriminative CWAs detection.

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An automatic monitor has been developed for measuring formaldehyde in air using a sensitive tape for formaldehyde. It is based on the color change of the tape on reaction with formaldehyde. The porous cellulose tape, containing silica gel as an absorbent and impregnated with the processing solution containing hydroxylamine sulfate, Methyl Yellow (pH indicator; pH 2.9-4.0, red-yellow), glycerin and methanol, was found to be a highly sensitive means of detecting formaldehyde and maintains a stable sensitivity. When the tape was exposed to a sample of air containing formaldehyde, the color of the tape changed from yellow to red. The degree of color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate, and it could be recorded by measuring the intensity of reflected light (555 nm). The tape could be used to detect down to 0.08 ppm (World Health Organization standard) of formaldehyde with a sampling time of 30 min and a flow rate of 100 mL min-1. Reproducibility tests showed that the relative standard deviation of response (n = 10) was 3.8% for 0.1 ppm formaldehyde. The monitor is simple, specific, capable of unattended operation and is recommended for both laboratory and field operation.

The dynamics and predictability of stratospheric low-frequency variability in the Northern Hemisphere winter are examined using a two-dimensional (2D) phase space spanned by the leading empirical orthogonal functions of the 10-hPa geopotential height field. The 2D phase space represents the variation of the strength of the polar night jet and the amplitude of zonal wavenumber-1 eddy components. A linearized nonstationary fluctuation-dissipation relation (NFDR) is developed based on the deterministic drift vector and the stochastic diffusion tensor estimated from a reanalysis dataset. The authors find that the solution of the linearized NFDR with an optimal data sampling time interval for estimating the drift vector and the diffusion tensor provides a good representation in the phase space of the inhomogeneous distribution of the forecast spread of the operational ensemble forecast conducted by the Japan Meteorological Agency. In particular, the linearized NFDR captures the local maximum of the forecast spread during the onset period of the major stratospheric sudden warming events.

A porous cellulose tape impregnated with a coloring solution that includes hydroxylamine sulfate, Methyl Yellow (pH indicator; pH 2.9-4.0, red-yellow), glycerin and methanol has been developed to provide a highly sensitive means of detecting formaldehyde gas. Formaldehyde reacts with hydroxylamine sulfate to produce sulfuric acid. When a sample including formaldehyde was passed through the tape, the color of the tape changed from yellow to red. The degree of color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate. The degree of color change could be recorded by measuring the intensity of reflecting light (555 nm). No interference was observed from carbon monoxide (100 ppm), nitrogen monoxide (50 ppm), nitrogen dioxide (105 ppm), carbon dioxide (4.9%), hydrogen (100%), hydrogen sulfide (32 ppm), or hydrogen fluoride (6 ppm). The response of acetaldehyde and propionaldehyde were one fortieth and three-hundredths of that of formaldehyde, respectively. Reproducibility tests showed that the relative standard deviation of relative intensity (n=10) was 3.4% for 4 ppm formaldehyde. The detection limit was 0.1 ppm for formaldehyde at a sampling time of 5 min and a flow rate of 400 ml/min.

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