A high sensitivity spectrometer with tunable diode laser for ambient methane monitoring

Tunable diode laser absorption spectroscopy （TDLAS） has been widely employed in atmospheric trace gases detection. In the measurement of these trace gases, harmonic detection combined with a multi-pass white cell could remarkably enhance the detection sensitivity. In this paper, a portable TDLAS system built specifically for long time monitoring methane in the atmosphere is introduced. The detection limit is below 100 ppb that is enough for the monitoring of ambient methane, and the long time monitoring results obtained in Beijing are given, which is well coincident with that of the Fourier transform infrared （FTIR） spectroscopy.

Crustaceous lichens sensitive monitor of caesium-137 radiation level in terrestrial environment

The activity of caesium-137 （Bq/kg） in the crustaceous lichens and other samples was determined to prove the feasibility that crustaceous lichens work as a sensitive biology monitor to record the caesium-137 （Bq/kg） radiation levels of terrestrial environment. The measurements were performed with GEM series HPGe （ high-purity Germanium） coaxial detector system （ADCAM -100 ） made by EC ＆ GORTEC Company in USA. It was found that the activity of caesium-137 （Bq/kg） in the crustaceous lichens was one order of magnitude higher than that found in surface soil, and was over throe orders of magnitude higher than those found in the familiar biological samples. These results proved that crustaceous lichens may be one of the most sensitive biological monitors about the remote transmission and environmental radiation levels of caesium-137.

Flexible optoelectronic neural transistors with broadband spectrum sensing and instant electrical processing for multimodal neuromorphic computing

A flexible optoelectronic neural transistor(OENT)that consists of a one‐step spin‐coated tri‐blend film composed of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene(C8‐BTBT),poly(3‐hexylthiophene‐2,5‐diyl)(P3HT),and poly(methyl methacrylate)(PMMA)is demonstrated.The C8‐BTBT and P3HT phases in the film partially segregate into distinct domains,which combine to provide broadband spectrum sensing,and instant electrical‐processing capabilities dominated by C8‐BTBT.The OENT is sensitive to solar radiation from the near‐ultraviolet(NUV)and to visible(Vis)radiation from blue to red.When exposed to NUV radiation,the OENT responds sensitively and retains the memory of the exposure for over 10^(3 )s.The OENT provides a warning of excessive chronic exposure to harmful NUV.These properties allow high‐pass filtering with different cut‐off frequencies fc that can restrict the reception of blue,green,or red.These switchable fc enables sensitive image reconstruction and multitarget monitoring.The device combined with a chitosan gel achieves strictly defined short‐range plasticity of<1 s that can achieve diverse instant‐computing applications such as spatiotemporally correlated coding and logic functions.Stable real‐time signal processing facilitates the realization of a Morse‐code recognition system constructed using neuro‐morphological hardware,achieving highly accurate character recognition.This study provides a useful resource that can have applications in wearable biomedical electronics and multimodal neuromorphic computing.