Molecular Biomarker Characteristics of the Linxi Formation Source Rocks in the Middle-Western Region of Inner Mongolia:New evidence for late-stage tectonic evolution of the Paleo-Asian Ocean

Objective Two important geological issues have long been controversial in the Xing-Meng area of North China. The first concerns the final closure of Paleo-Asian Ocean in Xing-Meng area, and the other concerns the folding and lifting of the Xing-Meng Trough. The focus of thses issues is the Late Permian sedimentary environment, which is generally considered to be either an exclusively continental environment or from the closed inland sea environment in the Early to Middle stage to continental lacustrine environment in the late stage. In recent years, we have successively discovered abundant typical marine fossils （e.g., bryozoans and calcareous algae） in the Upper Permian thick limestone layer from Linxi County and Ar Horqin Banner in eastern region of Inner Mongolia and Jiutain County in Jilin Province. These significant findings have attracted the attention from fellow academics.

InGaP/InGaAs/GaAs DHBT structural materials grown by GSMBE

Heterojunction bipolar transistor (HBT) is of great interest for the application to microwave power and analog circuits. As known, decreasing bandgap energy of the base layer in HBT can result in a smaller turn-on voltage. Using InGaAs as a base material in GaAs HBT is a possible approach to achieve the aim. In this work, a novel InGaP/InGaAs/GaAs double heterojunction bipolar transistor (DHBT) structure with an InGaAs base was designed and grown by gas source molecular beam epitaxy (GSMBE). High-quality InGaAs/GaAs hetero epi-layers and a good doping figure were obtained through optimizing the layer structure and the growth condition. The DHBT devices of a 120 μm×120 μm emitter area were fabricated by normal process and the good DC performance was obtained. A breakdown voltage of 10 V and an offset voltage of just 0.4 V were achieved. These results indicate that the InGaP/InGaAs/GaAs DHBT is suitable for low power-dissipation and high power applications.

Effects of growth conditions on optical quality and surface morphology of InGaAsBi

The effects of Bi flux and pressure of AsH3 on Bi incorporation,surface morphology and optical properties of InGa As Bi grown by gas source molecular beam epitaxy are studied.It is found that using relatively low pressure of AsH3 and high Bi flux can strengthen the effect on the incorporation of Bi and increase its content linearly with Bi flux until it nearly reaches a saturation value.The result from Rutherford backscattering spectroscopy（RBS） confirms that the Bi incorporation can increase up to 1.13%.By adjusting Bi and As flux,we could improve the surface morphology of In Ga As Bi sample.Room temperature photoluminescence shows strong and broad light emission at energy levels much smaller than the In Ga As bandgap.

Improving biodegradation potential of domestic wastewater by manipulating the size distribution of organic matter

Carbon source is a critical constraint on nutrient removal in domestic wastewater treatment.However,the functions of particulate organic matter（POM） and some organics with high molecular weight（HMW） are overlooked in the conventional process,as they cannot be directly assimilated into cells during microbial metabolism.This further aggravates the problem of carbon source shortage and thus affects the effluent quality.Therefore,to better characterize organic matter（OM） based MW distribution,microfiltration/ultrafiltration/nanofiltration（MF/UF/NF） membranes were used in parallel to fractionate OM,which obtained seven fractions.Hydrolysis acidification（HA） was adopted to manipulate the MW distribution of dissolved organic matter（DOM） and further explore the correlation between molecular size and biodegradability.Results showed that HA pretreatment of wastewater not only promoted transformation from POM to DOM,but also boosted biodegradability.After 8 hr of HA,the concentration of dissolved organic carbon（DOC） increased by 65%,from the initial value of20.25 to 33.48 mg/L,and the biodegradability index（BOD5（biochemical oxygen demand）/SCOD（soluble chemical oxygen demand）） increased from 0.52 to 0.74.Using MW distribution analysis and composition optimization,a new understanding on the characteristics of organics in wastewater was obtained,which is of importance to solving low C/N wastewater treatment in engineering practice.

InP-based In_xGa_(1-x)As metamorphic buffers with different mismatch grading rates

Linearly graded In_xGa_（1-x）As metamorphic buffers with different mismatch grading rates were grown on InP substrate by gas source molecular beam epitaxy.Room temperature photoluminescence spectra show that the sample with lower mismatch grading rate in the buffer has stronger photoluminescence signal,indicating the improved optical property.Atomic force microscope images show that the lower mismatch grading rate in the buffer leads to a slightly rougher surface.The relaxation procedure with two steps in the buffer layers has been observed by X-ray diffraction reciprocal space mapping.The measurements of X-ray diffraction also reveal that the lower mismatch grading rate in the buffer is beneficial for the lattice relaxation and release of residual strain.To further increase the relaxation degree,a lower mismatch grading rate and composition ＂overshoot＂ are suggested.