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
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.
Samples of airborne PM2.5 particles were collected during Fall 2011 from Guangzhou urban area. The morphology and size distribution of individual particles were analyzed by a Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometer(SEM-EDX) and Image Analysis System. Based on the morphology, three typical particles(soot aggregates, minerals, and coal fly ash) and other unknown particles in PM2.5 were identified. Results showed that the number-size distribution of PM2.5, peaking in the range of 0.1~0.2 μm, was dominated by the condensing sub-mode within the accumulation mode where gas phase reaction products were distributed. Both number and volume contribution of three typical particles were on the order of mineral soot aggregate fly ash. Minerals were mainly distributed in range of 0.1~0.3 μm with 41.97% in number percentage. The percentage of minerals in range of 0.1~0.2 μm was as high as 26.42%, which was the major factor influencing the overall size distribution of PM2.5. Size distributions of PM2.5particles were fairly similar during different sampling period(morning, afternoon, evening) as well as before and after raining, but the proportions of particles having sizes less than 0.1 μm were significantly decreased in the evening and after raining.
Nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) has received increasing attention. This paper presented how N2O emission was significantly reduced in a pilot-scale Carrousel oxidation ditch under reasonable nitrification and denitrification. N2O emission from the reactor was found as low as 0.027% of influent nitrogen, which was much less than that from other processes. Further measurements on spatial variation of N2O emission in the alternative aerobic/anoxic zones with help of a series of batch experiments demonstrated that about 90% of the emission was contributed by nitrifier denitrification (ND). Moreover, the taxonomic analysis based on high through-put 16S rRNA gene sequencing revealed that the high abundance of denitrifying bacteria and nitrite-oxidizing bacteria (NOB) was responsible for low nitrite accumulations and consequent low N2O emissions. However, N2O generation would be greatly increased upon the normal operation being shocked by either ammonia overload or aeration failure of the oxidation ditch system. (C) 2014 Elsevier Ltd. All rights reserved.
In the past two years, the power conversion efficiency (PCE) of organic-inorganic hybrid perovskite solar cells has significantly increased up to 20.1%. These state-of-the-art new devices surpass other third-generation solar cells to become the most promising rival to the silicon-based solar cells. Since the morphology of the perovskite film is one of the most crucial factors to affect the performance of the device, many approaches have been developed for its improvement. This review provides a systematical summary of the methods for morphology control. Introductions and discussions on the mechanisms and relevant hotspots are also given. Understanding the growth process of perovskite crystallites has great benefits for further efficiency improvement and enlightens us to exploit new technologies for large-scale, low-cost and high-performance perovskite solar cells.
Trifluoromethane (CHF3, HFC-23), with a 100-year global warming potential (GWP) of 12400, is regulated under the Kyoto Protocol. HFC-23 emissions in East Asia, especially in China, are currently thought to represent the majority of global HFC-23 emissions. This study provides both a bottom-up emission inventory and the multiannual top-down estimate of HFC-23 emissions in East Asia during 2007-2012. The new bottom-up inventory yields improved simulated HFC-23 mixing ratios compared to previous bottom-up inventories. The top-down estimate uses inverse modeling to further improve the model-measurement agreement. Results show that China contributed 94-98% of all HFC-23 emissions in East Asia. Annual a posteriori emissions from China were around 6.3 Gg/yr during the period 2007-2010 after which they increased to 7.1 +/- 0.7 Gg/yr in 2011 and 8.8 +/- 0.8 Gg/yr in 2012. For the first time, this study also provides a top-down estimate of HFC-23/HCFC-22 (chlorodifluoromethane, CHClF2) coproduction ratios in non-CDM (Clean Development Mechanism) HCFC-22 production plants as well as in all HCFC-22 production plants in China.