电感耦合等离子体在不同操作条件下的温度和电子密度的测定——Ⅰ.气体温度、激发温度、电离温度的测定

引言等离子体的温度和粒子密度是等离子体的两大基本参数,其中温度是考察等离子体的特性及使操作条件最佳化的关键。等离子体的温度有气体动态温度,激发温度,电子温度和电离温度。气体动态温度有分子旋转谱线法和Doppler加宽法,激发温度有两谱线法和Boltzmann斜率法,电子温度有粒子密     

活性流体流变行为的布朗动力学模拟研究

活性流体在用于开发新材料方面具有巨大潜力, 满足这一需求就要定量掌握活性流体所表现的特殊力学行为, 特别是流变行为. 扩展布朗运动方程, 建立自驱动活性粒子的运动模型, 基于反向非平衡法确定活性流体的黏度, 考察活性粒子体积分数、直行速度和转向扩散系数对活性流体流变行为的影响规律, 确定活性流体特殊流变行为的形成机理. 结果表明, 活性流体的流变曲线可被划分为黏度下降区、过渡区和牛顿区; 活性粒子体积分数越高, 活性流体的非牛顿特性越显著, 活性粒子的直行运动引起活性流体在低剪切速率区域黏度下降, 直行运动和转向运动的耦合作用导致中剪切速率区域流变曲线非单调变化, 活性粒子频繁发生转向运动会导致活性流体非牛顿特性受到抑制; 活性流体的宏观流变学特性和粒子的涨落直接相关, 活性粒子体积分数越高、直行速度越快和转向扩散系数越小, 活性流体中活性粒子越容易产生显著的涨落; 低剪切速率区域内活性粒子涨落明显, 随着剪切速率增大, 活性粒子的涨落逐渐被削弱, 粒子的聚集结构不断被破坏, 最终体系的流变行为类似一般被动流体.      

以椰壳生物质炭为燃料的直接炭固体氧化物燃料电池

通过热裂解制得椰壳炭,表征了其结构和组成,并将其用于电解质为钇稳定化氧化锆（YSZ）、电极材料为银和钆掺杂氧化铈（Ag-GDC）的固体氧化物燃料电池（SOFC）的燃料,对所构成的直接炭固体氧化物燃料电池（DC-SOFC）的性能进行了测试研究。结果表明,所制得的椰壳炭颗粒粒径在微米级别,具有介孔结构,而且椰壳炭中含有K、Ca等元素,可用作Boudouard反应催化剂。当使用椰壳炭作为DC-SOFC燃料时,在800 ℃下电池最大功率密度为255 mW/cm²;负载Fe催化剂后,最大功率密度提升为274 mW/cm²。以0.5 A/cm²的恒电流放电,0.5 g负载Fe椰壳炭燃料电池能够连续工作17.6 h,燃料利用率为39%,表明椰壳炭作为DC-SOFC燃料具有优异的性能和潜力。     

双过渡层阴极对流延法制备的阳极支撑直接碳固体氧化物燃料电池性能的改善作用

采用流延法制备了阳极支撑的固体氧化物燃料电池(SOFC),电解质材料为钇稳定化氧化锆(YSZ),阳极为镍和YSZ构成的金属陶瓷(Ni-YSZ),阴极为LSCF-GDC/LSCF复合材料,同时在阴极与电解质之间制备了YSZ-GDC/GDC双过渡层。分别采用含3%的加湿H_2和活性炭为燃料,对此电池的输出性能及阻抗谱进行测试。采用加湿H_2测试的结果表明:在800℃下,采用双过渡层电池的开路电压达到1 V,最大功率密度为680 mW·cm~(-2),比未改良电池的最大功率密度(372 mW·cm~(-2))提高了83%。直接采用固体碳为燃料时,具有双过渡层阴极的电池在850℃时的开路电压达到0.95 V,最大输出功率密度达429 mW·cm~(-2),几乎比无过渡层阴极的电池(225 mW·cm~(-2))高出1倍,特别是双过渡层阴极还使直接使用碳燃料的SOFC(DC-SOFC)的燃料利用率提高了33%。     

Observation of nonconservation characteristics of radio frequency noise mechanism of 40-nm n-MOSFET

Bias non-conservation characteristics of radio-frequency noise mechanism of 40-nm n-MOSFET are observed by modeling and measuring its drain current noise. A compact model for the drain current noise of 40-nm MOSFET is proposed through the noise analysis. This model fully describes three kinds of main physical sources that determine the noise mechanism of 40-nm MOSFET, i.e., intrinsic drain current noise, thermal noise induced by the gate parasitic resistance, and coupling thermal noise induced by substrate parasitic effect. The accuracy of the proposed model is verified by noise measurements, and the intrinsic drain current noise is proved to be the suppressed shot noise, and with the decrease of the gate voltage, the suppressed degree gradually decreases until it vanishes. The most important findings of the bias non-conservative nature of noise mechanism of 40-nm n-MOSFET are as follows.(i) In the strong inversion region, the suppressed shot noise is weakly affected by the thermal noise of gate parasitic resistance. Therefore, one can empirically model the channel excess noise as being like the suppressed shot noise.(ii) In the middle inversion region, it is almost full of shot noise.(iii) In the weak inversion region, the thermal noise is strongly frequency-dependent, which is almost controlled by the capacitive coupling of substrate parasitic resistance. Measurement results over a wide temperature range demonstrate that the thermal noise of 40-nm n-MOSFET exists in a region from the weak to strong inversion, contrary to the predictions of suppressed shot noise model only suitable for the strong inversion and middle inversion region. These new findings of the noise mechanism of 40-nm n-MOSFET are very beneficial for its applications in ultra low-voltage and low-power RF, such as novel device electronic structure optimization, integrated circuit design and process technology evaluation.     

Propagation of ultrashort pulsed beams in dispersive media

Starting from the Rayleigh diffraction integral, the propagation equation of ultrashort pulsed beams in dispersive media is derived without making the paraxial approximation and slowly varying envelope approximation (SVEA). The spatiotemporal properties of ultrashort pulsed beams in dispersive media, such as spectrum redshifting, narrowing and pulse distortion are illustrated with pulsed Gaussian beams. It is stressed that the “antibeam“ behaviour of ultrashort pulsed beams can be avoided, if a suitable truncation function is chosen.     

抗消化性溃疡药物的临床应用新进展

消化性溃疡属世界性多发病、常见病,该病以呕血、黑便及腹痛为主要临床症状,具有病程长、复发率高、治愈率低等特点,严重影响患者正常生活及工作。目前,临床上多采用H2受体拮抗剂、抗酸药、质子泵抑制剂、抗幽门螺杆菌药物等治疗消化性溃疡,其中,三联疗法(质子泵抑制剂+2种抗生素)及四联疗法(三联疗法+铋剂)疗效最佳。本研究分析抗消化性溃疡药物的应用新进展,以期为消化性溃疡的治疗提供参考依据。     

高速乳化对悬浮聚合墨粉形貌和性能的影响

以铁黑为颜料粒子,采用悬浮聚合技术,通过高速乳化机对反应体系进行预分散,制备出平均粒径为12μm的球形墨粉颗粒.通过在反应体系中加入span-80,克服铁黑粒子在墨粉表面的趋附现象.研究了乳化速度对墨粉颗粒性能的影响.     

铝在乙炔火焰原子吸收光谱分析上的干扰效应 1.考察铝对贵金属的干扰

一、前言贵金属在催化领域用处极为广泛,大多数贵金属在催化剂中都是主要的活性成分。特别是以可溶性氧化铝为担体的催化剂种类繁多。我们在前一篇文章中提到:金属铂担在γ-氧化铝,η-氧化铝上,用王水分解样品时,氧化铝也同时被溶解。实验证明铝的存在对铂的测定产生干扰。其干扰程度随铝的含量不同差别较大。基于这一实验事实,我们考察了铝对贵金属铂、铱、铑、钯、银、金在火焰原子吸收光谱分析上的干扰现