Time filter

Source Type

Ohata M.,National Metrology Institute of Japan | Tabersky D.,ETH Zurich | Glaus R.,ETH Zurich | Koch J.,ETH Zurich | And 2 more authors.
Journal of Analytical Atomic Spectrometry

The figures of merit of femto- and nanosecond laser ablation inductively coupled plasma mass spectrometry applying near infrared, middle ultraviolet, and far ultraviolet radiation at 795 nm, 265 nm, and 193 nm, respectively, for the quantitative multi-element analysis of glass materials were compared. Major, minor, and trace elements of four glass reference materials including NIST612, BCR-2G, GSE-1G, and BAM-S005A were quantified against NIST610 applying Ca or Si as an internal standard. Deviations between measured element concentrations and literature values were compared and it was demonstrated that all systems provide similar results when using Ca as an internal standard. By contrast, concentrations obtained by femtosecond laser ablation at 795 nm with Si as an internal standard showed deviations by up to 20% under the operating conditions chosen. Furthermore, Si-normalized fractionation indices calculated for nanosecond laser ablation at 193 nm as well as femtosecond laser ablation at 795 nm and 265 nm suggested these discrepancies to be, on the one hand, due to changes in the composition and/or particle size distribution of aerosols formed over the sampling time. On the other hand, Ca-normalized fractionation plots for femtosecond laser ablation at 795 nm turned out to be less informative with respect to quantification accuracy and, in addition, questioned their general significance. An adaptation of instrumental parameters was found to result in fractionation indices closer to unity signifying that both fluence and spot size are crucial parameters, controlling compositions and/or particle size distributions. This journal is © the Partner Organisations 2014. Source

Takahashi T.,Tohoku University | Kimura Y.,Tohoku University | Niwa K.,National Metrology Institute of Japan | Ohmiya Y.,Japan National Institute of Advanced Industrial Science and Technology | And 3 more authors.
Journal of Investigative Dermatology

Adenosine 5′-triphosphate (ATP) release from keratinocytes has been observed in various stress models in vitro, but studies demonstrating epidermal ATP release in vivo are limited. To visualize extracellular ATP (eATP) in vivo, we developed enhanced green-emitting luciferase immobilized on agarose beads (Eluc-agarose). Subcutaneous injection of Eluc-agarose together with ATP into the dorsal skin of BALB/c mice following intraperitoneal luciferin injection produced detectable and measurable bioluminescence using an in vivo imaging system. Using Eluc-agarose, we demonstrated in vivo that bright bioluminescence was observed from 1 to 20 minutes after repeated tape stripping of murine skin. This bioluminescence was suppressed by the local administration of apyrase. Eluc-agarose bioluminescence was observed only in tape-stripped skin with transepidermal water loss (TEWL) between 100 and 140 g m 2 h -1, indicating a loss of bioluminescence with excessive tape stripping (TEWL>140 g m -2 h -1). Histologically, tape-stripped skin with detectable eATP had a viable epidermis and a subepidermal neutrophil infiltrate, and administration of apyrase reduced the inflammatory infiltrate. Neither a viable epidermis nor an upper dermal neutrophil infiltrate was observed after excessive tape stripping. These results suggest that tape stripping prompts ATP release from viable keratinocytes, which facilitates inflammatory cell migration. Eluc-agarose may be useful in the in vivo detection of eATP in murine models of skin diseases. © 2013 The Society for Investigative Dermatology. Source

Yamada T.,National Metrology Institute of Japan
IEEE Transactions on Instrumentation and Measurement

High-accuracy frequency, amplitude, and phase estimation methods for asynchronous sampling are presented. The proposed estimation methods are based on phase difference estimation, compensation of number of samples, and a modified discrete Fourier transform. This study focused on processing signals in substation automation systems that comply with IEC 61850. Some simulation tests were conducted in cases of pure and distorted sinusoids, and the frequency, amplitude, and phase errors of the fundamental and harmonics are evaluated at fundamental frequencies around 50 Hz at fixed sampling rates of 4 kHz and 12.8 kHz (i.e., 80 and 256 samples per period). Dependence of each estimation accuracy on a fraction of number of samples is discussed. © 2013 IEEE. Source

Baba T.,National Metrology Institute of Japan | Taketoshi N.,Japan National Institute of Advanced Industrial Science and Technology | Yagi T.,National Metrology Institute of Japan
Japanese Journal of Applied Physics

Reliable thermophysical property values of thin films are important to develop advanced industrial technologies such as highly integrated electronic devices, phase-change memories, magneto-optical disks, light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), semiconductor lasers (LDs), flat-panel displays, and power electronic devices. In order to meet these requirements, the National Metrology Institute of Japan of the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) has developed ultrafast laser flash methods heated by picosecond pulse or nanosecond pulse with the same geometrical configuration as the laser flash method, which is the standard method to measure the thermal diffusivity of bulk materials. Since these pulsed light heating methods induce one-dimensional heat diffusion across a well-defined length of the specimen thickness, the absolute value of thermal diffusivity across thin films can be measured reliably. Using these ultrafast laser flash methods, the thermal diffusivity of each layer of multilayered thin films and the boundary thermal resistance between the layers can be determined from the observed transient temperature curves based on the response function method. The thermophysical properties of various thin films important for modern industries such as the transparent conductive films used for flat-panel displays, hard coating films, and multilayered films of next-generation phase-change optical disks have been measured by these methods. © 2011 The Japan Society of Applied Physics. Source

Yoshioka M.,National Metrology Institute of Japan | Kikuchi T.,National Metrology Institute of Japan
Japanese Journal of Applied Physics

An estimation using a theoretical formula for the amplitude decrease of discretized hydrophone output voltage due to imperfect synchronous averaging using an external trigger in our ultrasonic field parameter calibration is described. The estimation formula is derived from a statistically expected value considering the temporal difference of the trigger as a random variable with a uniform distribution in the range of the sampling period. As a result of comparing the formula and the measured hydrophone output voltage amplitude for ultrasound up to 20 MHz, it is confirmed that the formula can estimate the amplitude decrease and be used for correction to obtain accurate ultrasonic field measurement. © 2011 The Japan Society of Applied Physics. Source

Discover hidden collaborations