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991.
S. Sumi P. Prabhakar Rao Peter Koshy 《Journal of Materials Science: Materials in Electronics》2014,25(7):2985-2991
The effect of simultaneous substitution of Mn in both A and B sites of the pyrochlore type semiconducting oxides: (CaCe1?2x Mn2x )(Sn1?x Mn x Nb)O7?δ (x = 0, 0.1, 0.2, 0.3 and 0.4) was studied by employing powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy and electrical conductivity measurements. Besides the structural confirmation, Raman spectroscopy studies revealed the increased local disordering in the structure with progressive Mn substitution which is not observable in X-ray diffraction studies. The conductivity measurements confirm the negative temperature coefficient (NTC) behavior of the samples. Grain boundary dominant electrical characteristics have been observed in compounds with higher Mn concentration. Thermistor constant of the system lies in the range 6,700–8,500 K and the sensitivity values are in the range ?1 to ?2 %. The double substitution of Mn in this system offers to tune the NTC thermistor properties with increased localization of electrons in the lattice. 相似文献
992.
Peng Ling Jiang Minhong Gu Zhengfei Cheng Gang Ma Lei Du Yusong Wu Xiaofei Rao Guanghui Li Yongxiang 《Journal of Materials Science: Materials in Electronics》2014,25(1):323-327
The (1 ? x)K0.5Na0.5NbO3–xAlFeO3 ((1 ? x)KNN–xAF) (x = 0.01–0.08) lead-free piezoelectric ceramics were prepared at low temperature of 1,000 °C by conventional ceramic processing. And AF was used as a sintering aid in order to improve the sintering behavior of KNN. The effect of AF addition on the microstructure, dielectric and piezoelectric properties of the ceramics have been investigated. The results indicate that a small amount of AF can improve the sintering performance and piezoelectric properties of the ceramics effectively. The KNN–AF ceramics for x = 0.03 show the best piezoelectric properties: d 33 = 116 pC/N, k p = 32.9 %, Q m = 114.8, T C = 382 °C, P r = 21.8 μC/cm2. This also indicates that (1 ? x)KNN–xAF ceramics are a promising lead-free piezoelectric candidate material because of its good properties, low-temperature sintering characteristics and plenty of Al2O3 and Fe2O3 resources with low cost. 相似文献
993.
994.
对于华电包头锅炉的空气预热器(容克式),在运行中由于积灰造成预热器的堵塞,对锅炉的效率、预热器的磨损及吸风机、送风机的电耗增大等问题,本文主要介绍华电包头空气预热器水冲洗后锅炉排烟温度及吸风机、送风机电耗的影响。 相似文献
995.
996.
997.
阿拉伯板块构造—沉积演化为卡塔尔古生界油气聚集成藏提供了有利的石油地质条件。分析认为,卡塔尔在志留系底部发育一套优质的烃源岩(笔石热页岩),发育两套有利的碎屑岩储盖组合,储层以河流—三角洲相砂岩为主,埋深普遍大于3600m,总体较为致密,以中—低孔、低渗为主,但在局部仍可能发育储层物性较好的"甜点",具备较好的产能特性。古生界圈闭类型主要有背斜、断背斜、地层上倾尖灭岩性圈闭和与不整合相关的地层圈闭,具有3种油气成藏模式,以下生上储垂向断裂输导运聚成藏模式为主。海西构造挤压和盐流活动隆升作用对古生界的圈闭形成起了决定性作用,圈闭的主要形成时期为晚二叠世—晚三叠世,早于志留系烃源岩大量生排烃期,成藏条件匹配关系优越。卡塔尔碎屑岩层系勘探具有优越的烃源岩物质基础、有利的储盖组合、有利的构造圈闭聚集区和优越的油气成藏条件,且勘探程度极低,具有较大的油气勘探潜力,主要的有利勘探潜力区为卡塔尔隆起的侧翼和东部的南海湾盐盆区。 相似文献
998.
Ram Kumar K. Gopalakrishnan Irshad Ahmad C. N. R. Rao 《Advanced functional materials》2015,25(37):5910-5917
Composites of boron nitride (BN) and carboxylated graphene are prepared for the first time using covalent cross‐linking employing the carbodiimide reaction. The BN1–xGx (x ≈ 0.25, 0.5, and 0.75) obtained are characterized using a variety of spectroscopic techniques and thermogravimetric analysis. The composites show composition‐dependent electrical resistivity, the resistivity decreasing with increase in graphene content. The composites exhibit microporosity and the x ≈ 0.75 composite especially exhibits satisfactory performance with high stability as an electrode in supercapacitors. The x ≈ 0.75 composite is also found to be a good electrocatalyst for the oxygen reduction reaction in fuel cells. 相似文献
999.
Red Blood Cell Membrane as a Biomimetic Nanocoating for Prolonged Circulation Time and Reduced Accelerated Blood Clearance
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Lang Rao Lin‐Lin Bu Jun‐Hua Xu Bo Cai Guang‐Tao Yu Xiaolei Yu Zhaobo He Qinqin Huang Andrew Li Shi‐Shang Guo Wen‐Feng Zhang Wei Liu Zhi‐Jun Sun Hao Wang Tza‐Huei Wang Xing‐Zhong Zhao 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(46):6225-6236
For decades, poly(ethylene glycol) (PEG) has been widely incorporated into nanoparticles for evading immune clearance and improving the systematic circulation time. However, recent studies have reported a phenomenon known as “accelerated blood clearance (ABC)” where a second dose of PEGylated nanomaterials is rapidly cleared when given several days after the first dose. Herein, we demonstrate that natural red blood cell (RBC) membrane is a superior alternative to PEG. Biomimetic RBC membrane‐coated Fe3O4 nanoparticles (Fe3O4@RBC NPs) rely on CD47, which is a “don't eat me” marker on the RBC surface, to escape immune clearance through interactions with the signal regulatory protein‐alpha (SIRP‐α) receptor. Fe3O4@RBC NPs exhibit extended circulation time and show little change between the first and second doses, with no ABC suffered. In addition, the administration of Fe3O4@RBC NPs does not elicit immune responses on neither the cellular level (myeloid‐derived suppressor cells (MDSCs)) nor the humoral level (immunoglobulin M and G (IgM and IgG)). Finally, the in vivo toxicity of these cell membrane‐camouflaged nanoparticles is systematically investigated by blood biochemistry, hematology testing, and histology analysis. These findings are significant advancements toward solving the long‐existing clinical challenges of developing biomaterials that are able to resist both immune response and rapid clearance. 相似文献
1000.
Jing Hu Kwansoo Chung Xiao-Xing Li Taejoon Park Guo-Feng Zhou Rao Yao 《Metals and Materials International》2011,17(3):527-533
In the present work, a die shape design method to compensate spring-back in the sheet metal forming process is developed based
on a finite element analysis and a genetic algorithm. The proposed method is robust and automated enough for industrial applications.
Using a simple stretch bending process as an example, it was demonstrated that the new method optimizes the die profile effectively.
The good performance of the die profile optimized utilizing the new method was also verified experimentally, confirming that
the new method is likely to be more cost-effective than common design practices in practical applications. 相似文献