A new palm-sized optical PM 2.5 sensor has been developed and its performance evaluated. The PM 2.5 mass concentration was calculated from the distribution of light scattering intensity by considering the relationship between scattering intensity and particle size. The results of laboratory tests suggested that the sensor can detect particles with diameters as small as »0.3 mm and can measure PM 2.5 mass concentrations as high as »600 mg/m 3 . Year-round ambient observations were conducted at four urban and suburban sites in Fukuoka, Kadoma, Kasugai, and Tokyo, Japan. Daily averaged PM 2.5 mass concentration data from our sensors were in good agreement with corresponding data from the collocated standard instrument at the Kadoma site, with slopes of 1.07-1.16 and correlation coefficients (R) of 0.90-0.91, and with those of the nearest observatories of the Ministry of the Environment of Japan, at 1.7-4.1 km away from our observation sites, with slopes of 0.97-1.23 and R of 0.89-0.95. Slightly greater slopes were observed in winter than in summer, except at Tokyo, which was possibly due to the photochemical formation of relatively small secondary particles. Under high relative humidity conditions (>70%), the sensor has a tendency to overestimate the PM 2.5 mass concentrations compared to those measured by the standard instruments, except at Fukuoka, which is probably due to the hygroscopic growth of particles. This study demonstrates that the sensor can provide reasonable PM 2.5 mass concentration data in urban and suburban environments and is applicable to studies on the environmental and health effects of PM 2.5 .

Abstract— A prototype ballistic electron surface‐emitting display (BSD) was fabricated on a TFT or PDP glass substrate by using a low‐temperature process. A 84 × 63‐pixel, 7.6‐in.‐diagonal full‐color BSD shows excellent performance, comparable to the previously reported 2.6‐in. model. This result demonstrates the strong possibility of large‐panel BSDs.

Ballistic electron Surface-emitting Display (BSD) is successfully fabricated on a glass substrate with low temperature process. 168 (RGB) x 126 pixels, 2.6 inches diagonal full-colour BSD exhibits excellent performance as a flat panel display. Main fabrication process is an anodisation and subsequent electrochemical oxidation process at a low temperature, which will contribute to larger panel size and process-cost reduction.

To clarify the mechanism of thermoacoustic effects in a nanocrystalline porous silicon (nc-PS) device, ultrasonic emission characteristics have been investigated in relation to dynamic behavior. The nc-PS ultrasonic emitter is composed of a surface heater electrode, an nc-PS layer, and a single-crystalline silicon (c-Si) substrate. Due to a completely flat frequency response, this device emits an ideal impulse acoustic output with no reverberations for pulse driving. The relationship between acoustic output and transient surface temperature change can be well interpreted quantitatively by taking the heat capacity of the heater electrode into account. The experimental fact that the transient surface electrode temperature change is induced uniformly over the whole range of the emission area ensures the directivity of the acoustic pulse output.

It is demonstrated that the Ballistic electron Surface-emitting Display (BSD) can be fabricated onto both quartz and TFT Glass substrates and performed excellent characteristics. We also demonstrate the 2.6 inches diagonal 84(RGB)x63 pixels multicolour flat panel display on a quartz glass substrate. BSD promise the possible application to the flat panel display in near future.