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991.
Integration of GaAs BiFET (bipolar-FET) devices to obtain the optimum performance for multiple functions of MMIC design has been achieved. In this study, heterojunction bipolar transistors (HBTs), enhancement mode pseudomorphic HEMTs (E-pHEMTs), and depletion mode pHEMTs are developed for potential applications, including the integration of HBT power amplifier circuitry with pHEMT-based bias control, logic, RF switch, and low-noise amplifier circuitries. Critical processes including gate photolithography and gate recess control are presented and discussed in detail. The enhancement-depletion modes of pHEMT, HBT electrical performance, and uniformity are investigated comprehensively. In addition, power amplifiers and high power switches based on BiFET technology are investigated. 相似文献
992.
水热合成NaNbO3粉体的研究 总被引:1,自引:1,他引:0
采用Nb2O5,NaOH为反应原料,在180℃~200℃下通过水热法合成出结晶度高、晶粒发育完整的NaNbO3粉体。利用X射线衍射分析(XRD)对产物的物相结构进行了表征,并用扫描电子显微镜(SEM)观察了晶粒的结晶形貌、尺寸以及分布情况。研究结果表明:合成的NaNbO3粉体为正交相结构,晶胞参数a=5.569,b=15.523,c=5.505;水热合成温度影响体系的反应速度,温度越高反应速度越快;晶粒的尺寸随着反应时间的增加而增大。 相似文献
993.
994.
A facile approach of solvent‐evaporation‐induced coating and self‐assembly is demonstrated for the mass preparation of ordered mesoporous carbon‐silica composite monoliths by using a polyether polyol‐based polyurethane (PU) foam as a sacrificial scaffold. The preparation is carried out using resol as a carbon precursor, tetraethyl orthosilicate (TEOS) as a silica source and Pluronic F127 triblock copolymer as a template. The PU foam with its macrostructure provides a large, 3D, interconnecting interface for evaporation‐induced coating of the phenolic resin‐silica block‐copolymer composites and self‐assembly of the mesostructure, and endows the composite monoliths with a diversity of macroporous architectures. Small‐angle X‐ray scattering, X‐ray diffraction and transmission electron microscopy results indicate that the obtained composite monoliths have an ordered mesostructure with 2D hexagonal symmetry (p6m) and good thermal stability. By simply changing the mass ratio of the resol to TEOS over a wide range (10–90%), a series of ordered, mesoporous composite foams with different compositions can be obtained. The composite monoliths with hierarchical macro/mesopores exhibit large pore volumes (0.3–0.8 cm3 g?1), uniform pore sizes (4.2–9.0 nm), and surface areas (230–610 m2 g?1). A formation process for the hierarchical porous composite monoliths on the struts of the PU foam through the evaporation‐induced coating and self‐assembly method is described in detail. This simple strategy performed on commercial PU foam is a good candidate for mass production of interface‐assembly materials. 相似文献
995.
Pham T.D. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2008,96(8):1332-1347
Recent advances in biomedicine, pharmacology, and biotechnology open doors to the understanding how diseases are developed at the molecular and physiological level. This gain of understanding tremendously helps facilitate the design and discovery of drugs for therapeutic treatment. Despite the advances in the technology and new knowledge in systems biology, drug discovery is still a low process without utilizing scientific computations that allow precise and rapid analysis of biological processes under trials. This paper particularly addresses fractals as a computational tool for analyzing molecular imaging data that appear to be very useful sources of information for understanding the interactions and behaviors of complex biological networks and the development of predictive medicine. We study herein some fractal characteristics of fluorescent microscope images of peroxisomes, and propose the conceptual frameworks of fuzzy mixture fractal dimensions and fractal distortion measures for bioimage classification. 相似文献
996.
Guillaume Da Dominique Dufour Claude Marouz Mai Le Thanh Pierre‐Andr Marchal 《Starch - St?rke》2008,60(7):358-372
In Northern Vietnam, small‐scale cassava starch processing is conducted in densely populated craft villages, where processors face difficulties to expand their activities. Three different processing systems were studied among a cluster of three communes in the Red River Delta, producing up to 430 t of starch (at 55% dry matter) per day. The first system, type A, is a cylindrical rasper and a manual sieve, the second, type B, is a cylindrical rasper and stirring‐filtering machine and the third, type C, used equipment for both the rasping and filtering stages. Moisture, starch, crude fibers and ash content analysis were carried out on samples collected from the A‐B‐C manufacturing processes to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capital‐labor costs per tonne of starch (12% moisture) were also reported. A‐B‐C manufacturing processes enabled 75% recovery of the starch present in fresh roots. No significant change was observed in the composition of starch. Upgrading from system A to B and subsequently to C resulted in an increase in the extraction capacities (up to 0.9 t of peeled roots per hour), the extraction efficiencies during the extraction stage (up to 93%), and an increase in the water consumption and electrical power (up to 21 m3 and 55 kWh per tonne of starch, respectively). The highest amount of total solids carried in the waste‐water was obtained with type C (up to 17% of the dry weight of fresh roots, compared to 10% and 13% for type A and B, respectively). This may lead to a higher chemical oxygen demand (COD) and biological oxygen demand (BOD) in waste‐water, which can result in more polluted waste‐water than compared with the type A and B technologies. Upgrading the rasping‐extraction technologies also resulted in higher profits and reduction of labor per tonne of starch (up to 18 US$ and 26 man‐hours respectively). The diagnosis proposed in this study can be applied in different contexts to recommend technological options by considering space, energy and capital‐labor availabilities. 相似文献
997.
998.
This study is focused on the electrochemical performance of perovskite-type materials based on doped LaGaO3. La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM) and La0.8Sr0.2Ga0.8Mg0.115Co0.085O3−δ (LSGMC) were used as electrolytes and (Pr0.7Ca0.3)0.9MnO3 (PCM) and La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCM) as cathode and anode material, respectively. LSGM and LSGMC electrolytes were prepared by tape casting with a thickness of about 600 μm. The performance of LSCM/LSGMC/PCM was slightly superior to that obtained on LSCM/LSGM/PCM at different temperatures in both humidified hydrogen and ethanol steam atmospheres, good values of power output in LSCM/LSGMC/PCM were 182 and 169 mW cm−2 using humidified hydrogen and ethanol steam as fuel, respectively, and oxygen as oxidant at 850 °C. Cell stability tests indicate no significant degradation in performance after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 °C. Almost no carbon deposits were detected after testing in ethanol steam at 750 °C for >60 h on the LSCM anodes, suggesting that carbon deposition was limited during cell operation. 相似文献
999.
1000.
Yuang Tu Shiqi Liu Peiran Cai Tizhong Shan 《Comprehensive Reviews in Food Science and Food Safety》2023,22(5):3951-3983
Deoxynivalenol (DON) is one of the main types of B trichothecenes, and it causes health-related issues in humans and animals and imposes considerable challenges to food and feed safety globally each year. This review investigates the global hazards of DON, describes the occurrence of DON in food and feed in different countries, and systematically uncovers the mechanisms of the various toxic effects of DON. For DON pollution, many treatments have been reported on the degradation of DON, and each of the treatments has different degradation efficacies and degrades DON by a distinct mechanism. These treatments include physical, chemical, and biological methods and mitigation strategies. Biodegradation methods include microorganisms, enzymes, and biological antifungal agents, which are of great research significance in food processing because of their high efficiency, low environmental hazards, and drug resistance. And we also reviewed the mechanisms of biodegradation methods of DON, the adsorption and antagonism effects of microorganisms, and the different chemical transformation mechanisms of enzymes. Moreover, nutritional mitigation including common nutrients (amino acids, fatty acids, vitamins, and microelements) and plant extracts was discussed in this review, and the mitigation mechanism of DON toxicity was elaborated from the biochemical point of view. These findings help explore various approaches to achieve the best efficiency and applicability, overcome DON pollution worldwide, ensure the sustainability and safety of food processing, and explore potential therapeutic options with the ability to reduce the deleterious effects of DON in humans and animals. 相似文献