Eighty-seven soil samples collected from North China were analyzed for decabromodiphenyl ethane (DBDPE). The concentrations of DBDPE ranged from undetectable to 1612 ng/g, with the highest concentration present in Shandong. Additionally, the mean concentration of DBDPE in Shandong was found to be onefold higher than those found in Hebei and Shanxi, likely due to DBDPE production in Shandong. Relatively high concentrations of DBDPE in soils were also present in the south of Tianjin, where e-waste recycling may provide a source in this region. The fractions of DBDPE [DBDPE/(DBDPE + BDE209)] were lower than 0.5 in most soil samples, in agreement with the fact that deca-BDE is currently the main additive in brominated flame retardants (BFR) used in China. An obvious decreasing trend in DBDPE concentrations from east to west in North China was noted, with relatively higher DBDPE concentrations present in Shandong. A soil ingestion exposure assessment showed that for most sites, soil ingestion EDI was slightly lower than inhalation EDI; exceptions were found in several polluted sites, where soil ingestion was a more significant exposure route.
The oxidation mechanism in self-terminating wet etching technique with thermal oxidation of AlGaN layer followed by etching in KOH solution is investigated. Spike-shape remnants of oxidised AlGaN are observed at the initial stage of wet etching in KOH solution, which could be completely etched away after enough etching time. Transmission electron microscope/energy dispersive spectroscopy analysis indicates the existence of crystalline AlGaN inside the remnants. Finally, a possible explanation is given that the oxide channels from AlGaN surface towards AlGaN/GaN interface generated during thermal oxidation are firstly etched away at the initial stage of KOH wet etching, then after enough time these remnants with non-c axis crystal orientation surfaces exposed to KOH solution could be completely etched away leaving GaN layer beneath unaffected, which realises self-terminating etching.
Interest point detection is a fundamental approach to feature extraction in computer vision tasks. To handle the scale invariance, interest points usually work on the scale-space representation of an image. In this letter, we propose a novel block-wise scale-space representation to significantly reduce the computational complexity of an interest point detector. Laplacian of Gaussian (LoG) filtering is applied to implement the block-wise scale-space representation. Extensive comparison experiments have shown the block-wise scale-space representation enables the efficient and effective implementation of an interest point detector in terms of memory and time complexity reduction, as well as promising performance in visual search.
Launching the free-space light to the surface plasmon polaritons (SPPs) in a broad bandwidth is of importance for the future plasmonic circuits. Based on the interference of the pure SPP component, the bandwidths of the unidirectional SPP launching is difficult to be further broadened. By greatly manipulating the SPP intensities with the quasi-cylindrical waves (Quasi-CWs), an ultra-broadband unidirectional SPP launcher is experimentally realized in a submicron asymmetric slit. In the nanogroove of the asymmetric slit, the excited Quasi-CWs are not totally damped, and they can be scattered into the SPPs along the metal surface. This brings additional interference and thus greatly manipulates the SPP launching. Consequently, a broadband unidirectional SPP launcher is realized in the asymmetric slit. More importantly, it is found that this principle can be extended to the three-dimensional subwavelength plasmonic waveguide, in which the excited Quasi-CWs in the aperture could be effectively converted to the tightly guided SPP mode along the subwavelength plasmonic waveguide. In the large wavelength range from about 600 nm to 1300 nm, the SPP mode mainly propagates to one direction along the plasmonic waveguide, revealing an ultra-broad (about 700 nm) operation bandwidth of the unidirectional SPP launching.
Peng P, Zou L, Zhao D. On the Marriage of SPARQL and Keywords, in Web Technologies and Applications - 17th Asia-PacificWeb Conference, APWeb 2015, Guangzhou, China, September 18-20, 2015, Proceedings.; 2015:3–16.
Nitrate radical (NO3) and dinitrogen pentoxide (N2O5) are key species of the tropospheric chemistry, that play a central role in the tropospheric chemical issues such as atmospheric self cleansing capacity, secondary aerosol formations, reactive halogen chemistry, global sulfur cycles, etc. Nevertheless, the accurate and precise determination of both NO3 and N2O5 is still a challenging task due to their low ambient concentrations, high reactivity and short life time. In this paper, we summarize all kinds of measurement techniques used in the field observations of NO3 and N2O5, including differential optical absorption spectroscopy (DOAS), cavity ring-down spectroscopy (CRDS), cavity enhance absorption spectroscopy (CEAS), laser-induced fluorescence (LIF), matrix isolation electron spin resonance spectroscopy (MIESR), and chemical ionization mass spectrometry(CIMS). The advantages and disadvantages of those techniques are reviewed on the aspects of measurement accuracy, precision, time resolution, interference, calibration and operation stability. The absorption spectroscopy is the best technical approach, especially the subcategories-CRDS and CEAS developed in the last decade are the techniques with high potential of good performance in field applications. However, because high aerosol loadings are always presented in the atmosphere of the mega-city regions in China, the aerosol extinction could be a significant barrier to come over for the techniques based on absorption spectroscopy. Moreover, the observed NO3 and N2O5 concentrations and the major scientific findings of corresponding measurement campaigns conducted in typical tropospheric conditions as urban, forest, free troposphere and marine environments, etc. are outlined. Finally, we discuss the unresolved issues of the NO3 and N2O5 chemistry and possible new directions for future studies in chemically complex environments.
In this study, mesoscopic optical structured 2,9-dimethyl-4,7-diphenyl-1,10-phenyl-1,10-phenanthrolin (bathocuproine, BCP) film was formed to enhance the out-coupling efficiency of a top blue organic light-emitting device (OLED). Based on the refractive index matching layer of BCP on the electrode, the light can be extracted through waveguide mode. Owing to the low glass transition temperature (T-g) of BCP, which easily self-aggregates in a specific environment (controlled temperature and humidity), a mesoscopic optical structure was obtained in 3 h after film formation. Through the nano-aggregated structure, the surface plasmon polariton (SPP) mode can match the free optic field. The efficiency of the device was enhanced: the max brightness increased from 4500 to 9840 cd.m(-2) and the external quantum efficiency (EQE) increased from 0.42% to 1.14%. This leads to a 2.7-fold enhancement of top emission devices. Moreover, the EL spectra of the devices are also optimized by a blue-shift of 12 nm.
Aerobic methane-oxidizing bacteria (MOB) play an important role in mitigating the methane emission in soil ecosystems to the atmosphere. However, the impact of plant species and plantation ways on the distribution of MOB remains unclear. The present study investigated MOB abundance and structure in plateau soils with different plant species and plantation ways (natural and managed). Soils were collected from unmanaged wild grassland and naturally forested sites, and managed farmland and afforested sites. A large variation in MOB abundance and structure was found in these studied soils. In addition, both type I MOB (Methylocaldum) and type II MOB (Methylocystis) were detected in these soils, while type II MOB usually outnumbered type I MOB. The distribution of soil MOB community was found to be collectively regulated by plantation way, plant species, the altitude of sampling site, and soil properties.
Wei M, Gui G, Chung Y-H, Xiao L, Qu B, Chen Z. Micromechanism of electroplex formation. PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS. 2015;252:1711-1716.
In this work, we have provided a new possible explanation for the micromechanism of electroplex. The time-resolved electroluminescent spectra of light-emitting diodes based on the blend of TAPC and TpPyPB were measured. They show that when a high bias voltage is applied on the devices, the electroplex emission gradually increases over time. After the devices worked at a high bias voltage, a strong electroplex emission can be maintained at low bias voltage, but the peaks related to the electroplex are still insignificant in photoluminescence. These results may suggest that the electroplex is a charge-transfer complex with changed conformation caused by polaron-induced molecular aggregation under electric field in essence, though further investigation is needed. Using materials with morphology stability under an electric field, electroplex was greatly reduced, which may enlarge the consideration in designing exciplex-based organic light-emitting diodes (ExOLEDs). (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
