Hydrogen production characteristics of the organic fraction of municipal solid wastes by anaerobic mixed culture fermentation

The hydrogen production from the organic fraction of municipal solid waste (OFMSW) by anaerobic mixed culture fermentation was investigated using batch experiments at 37 degrees C. Seven varieties of typical individual components of OFMSW including rice, potato, lettuce, lean meat, oil, fat and banyan leaves were selected to estimate the hydrogen production potential. Experimental results showed that the boiling treated anaerobic sludge was effective mixed inoculum for fermentative hydrogen production from OFMSW. Mechanism of fermentative hydrogen production indicates that, among the OFMSW, carbohydrates is the most optimal substrate for fermentative hydrogen production compared with proteins, lipids and lignocelluloses. This conclusion was also substantiated by experimental results of this study. The hydrogen production potentials of rice, potato and lettuce were 134 mL/g-VS, 106 mL/g-VS, and 50 mL/g-VS respectively. The hydrogen percentages of the total gas produced from rice, potato and lettuce were 57-70%, 41-55% and 37-67%. 2008 International Association for Hydrogen Energy.

黄土高原典型土壤有机氮矿化过程

以黄土高原从北向南不同地区典型土壤类为对象,采用Bremner淹水培养法,研究黄土高原典型土壤有机氮的矿化过程。结果表明,淹水培养期间矿化出的部分NH4+-N会被粘土矿物固定,固定量因土壤不同而异,因此在测定有机氮矿化量时,只有考虑这一部分氮素,才可获得可靠结果。不同土壤有机氮量矿化明显不同,表现为土垫旱耕人为土>黄土正常新成土>简育干润均腐土>干润砂质新成土,从南到北氮素矿化量呈减小趋势。添加C/N低(C/N比为21.7)的紫花苜蓿(Medicago stativa)茎叶有利于促进土壤有机氮矿化,而添加C/N高(C/N比为43.3)的长芒草(Stipa bungeana)会促进矿质氮的生物固定;不同类型植被土壤间在培养20、40d和60d时的矿化量差异显著(p值分别为0.0177、0.0109和0.0073),均表现为均为林地土壤>裸地土壤>草地土壤>农田土壤;从平均看,加(NH4)2SO4后有机氮矿化量有一定减少。在不同培养阶段,不同土类间氮素矿化率不同,在20d和40d时存在显著差异(p分别为0.0092和0.0381),60d时差异不显著,不同土类氮素矿化率的大小顺序为干润砂质新成土>黄土正常新成土>...

PHOTOLUMINESCENCE SPECTRA OF STRAINED HETEROSTRUCTURE OF INP ON GAAS SUBSTRATE GROWN BY METAL-ORGANIC CHEMICAL VAPOR-DEPOSITION

A high-energy shift of the band-band recombination has been observed in photoluminescence spectra of the strained InP layer grown on GaAs substrate. The InP layer is under biaxial compressive strain at temperatures below the growth temperature, because the thermal expansion coefficient of InP is smaller than that of GaAs. The strain value determined by the energy shift of the band-edge peak is in good agreement with the calculated thermal strain. A band to carbon acceptor recombination is also identified.

METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION GROWTH OF GAN

Single-crystal GaN films have been deposited on (01 (1) over bar 2) sapphire substrates using trimethylgallium (TMGa) and NH3 as sources. The morphological, crystalline, electrical and optical characterizations of GaN film are investigated. The carrier concentration ofundoped GaN increases with decreasing input NH3-to-TMGa molar flow ratio.

Low-Temperature Growth of ZnO Films on GaAs by Metal Organic Chemical Vapor Deposition

ZnO thin films were grown on GaAs （001） substrates by metal-organic chemical vapor deposition （MOCVD） at low temperatures ranging from 100 to 400℃. DEZn and 1-12 O were used as the zinc precursor and oxygen precursor, respectively. The effects of the growth temperatures on the growth characteristics and optical properties of ZnO films were investigated. The X-ray diffraction measurement （XRD） results indicated that all the thin films were grown with highly c- axis orientation. The surface morphologies and crystal properties of the films were critically dependent on the growth temperatures. Although there was no evidence of epitaxial growth, the scanning electron microscopy （SEM） image of ZnO film grown at 400℃ revealed the presence of ZnO microcrystallines with closed packed hexagon structure. The photoluminescence spectrum at room temperature showed only bright band-edge （3. 33eV） emissions with little or no deep-level e- mission related to defects.

Zn-doped InGaAs Base Heterojunction Bipolar Transistors Grown by Low Pressure Metal Organic Chemical Vapor Deposition

High performance InP/InGaAs heterojunction bipolar transistors(HBTs) have been widely used in high-speed electronic devices and optoelectronic integrated circuits. InP-based HBTs were fabricated by low pressure metal organic chemical vapor deposition(MOCVD) and wet chemical etching. The sub-collector and collector were grown at 655 ℃ and other layers at 550 ℃. To suppress the Zn out-diffusion in HBT, base layer was grown with a 16-minute growth interruption. Fabricated HBTs with emitter size of 2.5×20 μm~2 showed current gain of 70~90, breakdown voltage(BV_(CE0))>2 V, cut-off frequency(f_T) of 60 GHz and the maximum relaxation frequency(f_(MAX)) of 70 GHz.