NMOS低温热载流子晶体管的解析研究

利用低温(77-295K)短沟NMOSFET准二维解析模型,研究了77-295K温区NMOSFET衬底电流相关的物理机制。发现沟道电子平均自由程不随温度而改变,其值约为7.6nm;低温下虽然沟道电子在漏端获得较高的能量,但由于碰撞电离减弱,使NMOSFET的衬底电流不随温度降低而显著增长。实验结果证明,提出的衬底电流机制和模型适用于77-295K宽温区范围。     

氮化铝陶瓷基片热导率的理论分析

对氮化铝陶瓷基片的热导率进行了实验和理论分析,结果证实,烧结初始氧含量低的氧化铝粉体,加入较多的Ｙ２Ｏ３作烧结助剂才能获得最大热导率,并且其值较高;随着氧含量的增加,可达到的最大热导率逐渐降低,而需加入的Ｙ２Ｏ３量减少,同时,晶间相的存在对热导率有重要影响,文中推导出热导率与氧含量和Ｙ２Ｏ３添加量之间的定量关系式并指出,获得最大热导率必须使用氧含量低的陶瓷粉体,同时根据氧含量的大小来确定Ｙ２Ｏ３的     

Effect of Substrate Temperature on Electroluminescence of SrS:HoF3 Thin Film

The SrS:HoF3 Electroluminescent (EL) thin films are prepared at the different substrate temperature by electron beam evaporation. The crystallinity and EL characteristics of the samples are analyzed. It is found that the main diffraction peak is (200) at the higher substrate temperature and the main diffraction peak is (111) at the lower substrate temperature. The blue emission intensity and EL brightness of the SrS∶HoF3 thin films increase with the increase of the substrate temperature. Annealing the samples can change the cyrstal phase and strengthen the blue emission of EL thin film.     

La2/3Ca1/3MnO3薄膜结构与输运性质

用磁控溅射方法在不同单晶衬底材料上制备了一系列含La2／3Ca1／3MnO3(LCMO)薄膜。当薄膜厚度大于200A,在我们实验条件下可观测到金属．绝缘体转变,且转变温度随厚度和衬底材料而变化。渗流电阻模型被用来解释薄膜材料的电输运特性,结合薄膜外延特性(晶格失配)和薄膜与衬底的相互作用,及薄膜表面、界面粗糙度的测量可知薄膜的剩余电阻、极化子的激活能、金属．绝缘体转变温度等密切与薄膜质量相关。     

氧化铝陶瓷基板工艺研究

本文主要介绍了流延法生产氧化铝陶瓷基板的工艺.研究了原料粒度分布对基板微观结构的影响,用流延法制备了96%氧化铝陶瓷基板,并对基板表面被釉,试验了基板的性能,研究了基板生产过程中一些关键的因素.     

Prevention of substrate and product inhibitions by using a dilution strategy during dark fermentative hydrogen production from molasses

Substrate and product inhibitions have a significant effect on dark fermentative hydrogen gas production. Particularly, rapid formation of volatile fatty acids leads to fast pH decreases shifting the metabolic pathway. Therefore, controlling volatile fatty acid accumulation has great importance in maintaining effective hydrogen production. In this context, a dilution strategy was applied to regulate volatile fatty acids levels within the desired concentration range. A three-factor Box-Behnken statistical experiment design was established to assess the effects of dilution time, dilution percentage and initial COD concentration on hydrogen formation yield and rate. Highest hydrogen yield (7.7 mL H₂/mL_reactor) and rate (21. 47 mL H₂/h or 9.38 mmol/L_reactor.h) were achieved when 85 gCOD/L containing fermentation media was diluted with a percentage of 130 of the initial working volume at the 3rd hour of the fermentation period. Moreover, this strategy enabled to start fermentation with 55 g glucose/L.     

Properties and substrate specificities of proteolytic enzymes from the edible basidiomycete Grifola frondosa

Highly active proteolytic enzymes are found in the fruiting bodies of Grifola frondosa. The general properties and substrate specificities of these proteases from G. frondosa (ProGF) were studied. The optimal pH for ProGF activity was pH 3 or 7 using hemoglobin or Hammersten casein as a substrate, respectively. The ProGF exhibited over 70% of maximal activity within the pH range of 4.5–8.5. In terms of temperature, the ProGF were maximally active at 55 °C, while over 80% of maximal activity was observed within the range of 50–75 °C. These proteases were substrate-specific, mainly cleaving at Ala¹⁴-Leu¹⁵, Tyr¹⁶-Leu¹⁷, and Pro²⁸-Lys²⁹ bonds, with occasional cleavage of Phe²⁴-Phe²⁵ bonds in the oxidized insulin B-chain. The ProGF also liberated hydrophobic amino acids, such as valine, leucine, and phenylalanine, using the oxidized insulin B-chain as a substrate. When soy protein was used as a substrate, valine, leucine, phenylalanine, and tyrosine were selectively released from the hydrolysate. Thus, over the time course of incubation, the peptide concentration increased as the average peptide chain length decreased. These results indicate that the ProGF include both endopeptidases recognizing leucine, phenylalanine, and lysine at the P1′ position, and aminopeptidases preferentially releasing hydrophobic and aromatic amino acids such as valine, leucine, phenylalanine, and tyrosine.     

Effect of substrate concentration on continuous Photo-fermentative hydrogen production from lactate using Rhodobacter sphaeroides

The information on continuous operation and the use of actual waste as a feedstock are essential for the practical application of photo-fermentative H₂ production. For the first 200 days, continuous H₂ production from lactate was attempted using purple non-sulfur (PNS) bacteria, Rhodobacter sphaeroides KD131, under an illumination of 110 W/m². During the continuous operation, 30% of the fermenter volume was replaced by fresh feedstock once a day, and substrate concentration was gradually increased from 5 mM to 30 mM. H₂ production was negligible at 5 mM, which was ascribed to the fact that the electrons contained in lactate were mostly consumed for cell growth and soluble microbial products (SMPs) production. As lactate concentration increased, H₂ production gradually increased and reached a maximum at 20 mM, showing a substrate conversion efficiency (SCE) of 38%, a H₂ yield of 2.3 mol H₂/mol lactate_added, and a H₂ production rate of 309 mL H₂/L-fermenter/d. Further increases of lactate concentration resulted in a drop of H₂ production (<1.0 mol H₂/mol lactate_added). When the feedstock was changed to actual waste obtained from a 1-day lactate fermentation of food waste, stable H₂ production was maintained, but showed a decreased SCE of 24%. It was speculated that the low performance was due to the fact that actual waste contained not only pure lactate but also other organic compounds that could not be utilized by PNS bacteria. In addition, compared to feeding with pure lactate, the electron consumption to the cell growth was higher in feeding with actual waste, which led to the lower performance.     

Effects of substrate temperature on dielectric and structural properties of Ti and Er co-doped HfO2 thin films

We report dielectric and structural properties of Ti and Er co-doped HfO₂ (HfTiErO_x) thin films at different substrate temperatures. The film at 400 °C substrate temperatures has the highest k value of 33, improved flat band voltage of −0.3 V, small hysteresis voltage and the significant interface-state density, which shows better dielectric properties for new high-k microstructure. XPS and XRD results reveal that Hf-Ti-Er-O bond may exist in addition with Hf-O, Hf-Er-O and Hf-Ti-O bonds, while the change in chemical structure and degradation of crystallization quality of HfO₂ thin films are directly related to Ti and Er co-doping.     

Statistical optimization of biohydrogen production from sucrose by a co-culture of Clostridium acidisoli and Rhodobacter sphaeroides

Statistically based experimental designs were applied to optimize the fermentation process parameters for hydrogen (H₂) production by co-culture of Clostridium acidisoli and Rhodobacter sphaeroides with sucrose as substrate. An initial screening using the Plackett–Burman design identified three factors that significantly influenced H₂ yield: sucrose concentration, initial pH, and inoculum ratio. These factors were considered to have simultaneous and interdependent effects. A central composite design and response surface analysis were adopted to further investigate the mutual interactions among the factors and to identify the values that maximized H₂ production. The optimal substrate concentration, initial pH, and inoculum ratio of C. acidisoli to R. sphaeroides were 11.43 g/L sucrose, 7.13, and 0.83, respectively. Using these optimal culture conditions, substrate conversion efficiency was determined as 10.16 mol H₂/mol sucrose (5.08 mol H₂/mol hexose), which was near the expected value of 10.70 mol H₂/mol sucrose (5.35 mol H₂/mol hexose).