外加磁场对掺杂TiO2薄膜光催化活性的影响

利用外加匀强磁场辅助掺杂TiO2光催化降解偶氮胭脂红B溶液,实验探讨了外加磁场强度对Fe3 、Ni2 、Cu2 掺杂TiO2薄膜光催化活性的影响.结果 表明:外加磁场使掺杂Ni2 /TiO2、Fe3 /TiO2薄膜的光催化活性降低,在磁感应强度为0.7×10-2T时,催化剂Fe3 /TiO2几乎完全失活,光催化降解率低于2.0%,而掺杂0.5% Cu2 /TiO2薄膜的光催化活性在磁场辅助下光催化活性普遍增强,感应强度为1.0×10-2T时光催化降解率达19.4%,相当于无外加磁场时的1.2倍;理论分析指出,磁场辅助对掺杂TiO2光催化活性的影响与掺杂离子的磁导率有关.     

具有高温稳定性的ZrAlN薄膜的合成

干磨可以造成工具表面的温度上升到800~1000℃. 因此, 能在如此高温度下为切削工具提供保护的膜层已成为研究的热点. ZrAlN由于Al元素的存在可能具有高温稳定的结构和机械性能. 用直流磁控溅射的方法合成了ZrAlN 薄膜. 利用XRD与纳米压痕仪分析了反应气体分压和基底偏压对薄膜结构、机械性能及其高温热稳定性的影响. 在最佳条件(基底偏压-37 V, N₂分压为2×10^-5 Pa)制备的ZrAlN薄膜具有平滑的表面且其硬度具有热稳定性. 在退火之后, 该薄膜的应力由2.2 GPa降至0.7 GPa. 薄膜的高温热稳定性可能与Al₂O₃和ZrO₂晶相的形成有着直接的联系.     

醋酸处理对TiO2薄膜亲水性的影响

本文用溶胶-凝胶法制备均匀透明的TiO2薄膜,在400℃锻烧2 h,再在一定浓度的醋酸中浸泡处理24 h,最后在300℃、400℃、500℃进行第二次热处理0.5 h.用X射线衍射、原子力显微镜、紫外-可见分光光度计表征了处理前后薄膜的晶相结构、表面形貌及薄膜的光学性能.研究了醋酸的浓度、避光时间及光照时间对薄膜亲水性的影响.实验表明：用醋酸浸泡处理后的薄膜亲水性明显提高.光谱及AFM分析表明,导致TiO2薄膜亲水性改善的原因是醋酸浸泡处理后的薄膜表面结构的发生了变化.醋酸的最佳浓度为1 mol/L.     

镧掺杂对TiO2薄膜性能的影响

用sol—gel法于玻璃表面制备了镧掺杂纳米TiO2薄膜。利用X射线衍射仪（XRD）、原子力显微镜（AFM）对其进行了表征。通过接触角测量仪测量亲水角来表征其亲水性能，并根据紫外光照射下亚甲基蓝溶液的光催化降解率评价其光催化性能。研究了镧掺杂量、热处理温度对纳米TiO2薄膜亲水性能和光催化效果的影响。研究发现，镧掺杂可以提高TiO2薄膜的亲水性能并且在黑暗条件下能将亲水性保持更长一段时间；镧掺杂可以提高TiO2薄膜的光催化效率，扩展TiO2薄膜的光谱吸收范围。     

La和Nd掺杂的硅基Bi_4Ti_3O_(12)铁电薄膜的无疲劳特性及其机理的比较研究

采用优化的溶胶-凝胶(Sol-gel)技术,同一工艺条件下在Pt/TiO2/SiO2/Si衬底上成功地制备了Bi3.25La0.75Ti3O12(BLT)和Bi3.15Nd0.85Ti3O12(BNT)铁电薄膜.X射线衍射(XRD)测试表明BLT和BNT薄膜具有单相的取向随机的多晶微结构;扫描电镜(SEM)的观测显示了这些薄膜具有50~100nm晶粒构成的均匀致密的表面形貌.利用铁电测试仪测定了以Cu为上电极而形成的金属-铁电薄膜-金属结构的电容器的铁电性能,得到了很好的饱和电滞回线.在最大外加场强为400kV/cm时,BLT和BNT薄膜的剩余极化强度(2Pr)和矫顽电场(2Ec)分别为25.1μC/cm2,203kV/cm和44.2μC/cm2,296kV/cm.疲劳测试表明,在1MHz频率测试下经过1.75×1010次读写循环后,由BLT和BNT薄膜组成的电容器几乎没有表现出疲劳,呈现很好的抗疲劳特性.分析比较了La和Nd掺杂对薄膜结构及铁电性能的影响及其机理.     

纳米硅薄膜材料在场发射压力传感器研制中的应用

设计研制了一种基于量子隧道效应机制的场发射压力传感器原型器件, 用CVD技术制备了粒径为3 ~ 9 nm, 厚度为30 ~ 40 nm的纳米硅薄膜, 并同时把这种低维材料引入到传感器阴极发射尖锥的制作, 形成纳米硅薄膜为实体的发射体结构. 用HREM及TED分析了纳米硅态的显微特性, 用场发射扫描电子显微镜SEM分析了发射体及阵列的微观结构, 用HP4145B晶体管参数测试仪考察了传感器件的场发射特性. 实验结果表明, 当外加电场为5.6×10⁵ V/m时, 器件有效区域发射电流密度可达53.5 A/m².     

Science China Technological Sciences 2021年64卷第2期中文摘要

正铸造速度对镁稀土合金微观组织,腐蚀行为,及生体骨组织反应的影响王海健,王海伟, KUMAZAWA Takashi,巨东英,曹建庭采用10和30r/min两种铸造速度在垂直双辊铸造(TRC)中制备镁稀土(Mg-RE)合金,并对其微观组织、腐蚀行为和生物体内的骨组织反应进行了详细研究.结果表明,与TRC-10 r/min铸件相比, TRC-30 r/min铸件具有更细的晶粒尺寸和更高的非结晶体积分数.电化学阻抗谱(EIS)和电势极化实验结果表明, TRC-30 r/min铸件具有更高的耐腐蚀性.动物实验表明,在TRC-30 r/min实验组的生物体内,     

阳极氧化制备新颖的TiO_2多孔纳米结构膜及其形成机理与应用

采用两步阳极氧化法在钛箔片上制备了TiO_2多孔薄膜,随着阳极氧化的进行,Ti片表面依次出现上下双层纳米多孔结构、内外双层(芯壳)纳米管阵列结构和单层纳米管阵列结构等典型形貌,结合不同时间段的阳极氧化膜的表面形貌、晶体结构、X射线光电子能谱、电流密度随时间变化曲线等,分析了随着氧化进行钛片表面多孔TiO_2纳米膜典型形貌可能的形成机理.上下双层结构纳米多孔膜可能是因为纳米孔孔径强烈依赖于电流密度,而起始阶段的电流密度大小指数下降导致出现上层大孔下层小孔的双层结构;内外双层结构纳米多孔膜的形态可能来自于氧化钛纳米多孔膜从内至外由成分和可溶性不同的氧化钛构成导致;随着氧化进行,内层可溶性大的氧化钛结构逐渐溶解,形成的常见的TiO_2纳米管阵列结构.将阳极氧化得到的稳定的TiO_2纳米管薄膜作为光阳极组装成染料敏化太阳能电池,研究了其光电性能.基于未经修饰处理的TiO_2纳米管阵列光阳极,其组装电池的能量转换效率(η)可达5.88%,将TiO_2纳米管阵列光阳极进一步采用常用的TiCl_4溶胶处理后,其效率提高到8.47%,在能源转化方面展现了较好的应用前景.     

La和Nd掺杂的硅基Bi4Ti3O12铁电薄膜的无疲劳特性及其机理的比较研究

采用优化的溶胶-凝胶（Sol—gel）技术,同一工艺条件下在Pt／TiO2／SiO2／Si衬底上成功地制备了Bi3.25La0.75Ti3O12（BLT）和Bi3.15Nd0.85Ti3O12（BNT）铁电薄膜．X射线衍射（XRD）测试表明BLT和BNT薄膜具有单相的取向随机的多晶微结构;扫描电镜（SEM）的观测显示了这些薄膜具有50～100nm晶粒构成的均匀致密的表面形貌．利用铁电测试仪测定了以Cu为上电极而形成的金属-铁电薄膜-金属结构的电容器的铁电性能,得到了很好的饱和电滞回线．在最大外加场强为400kV／cm时,BLT和BNT薄膜的剩余极化强度（2Pr）和矫顽电场（2Ee）分别为25．1gC／cm^2,203kV／cm和44．2gC／cm^2,296kV／cm．疲劳测试表明,在1MHz频率测试下经过1．75×10^10次读写循环后,由BLT和BNT薄膜组成的电容器几乎没有表现出疲劳,呈现很好的抗疲劳特性．分析比较了La和Nd掺杂对薄膜结构及铁电性能的影响及其机理．     

电子束辐照下钛酸锶钡薄膜的电子能量损失谱研究

实验发现在较高电流密度的电子束照射下(电流密度约为2 nA/cm²), BST薄膜有辐照损伤现象发生. 原位实时记录的Ti和O的电子能量损失电离边峰强度比和相对位移的变化表明: 损伤过程主要表现为薄膜失氧及其导致的正离子化学价态的变化. 具高空间分辨的电子能量损失谱研究证明: 相对于具有完整晶体结构的柱状晶晶粒内部, 有着特殊结构和化学环境的柱状晶晶粒边界是失氧的主要途径.     

铁银共掺杂TiO2纳米材料的制备及性能

本文采用溶胶一凝胶法制备了Fe^3＋、Ag单掺杂以及Fe^3＋Ag共掺杂的TiO2复合材料,采用XRD、SEM研究分析了样品晶体的结构变化和形貌。以甲基橙为光催化反应模型化合物,考察了掺杂对光催化活性的影响。无论是单掺杂还是共掺杂,掺杂后效果明显提高,性能均优于纯TiO2,特别是共掺杂效果更为明显。根据最后试验共掺杂的最佳比例Fe^3＋0．1％、Ag0．7％,确定了共掺杂降解环境的最佳pH值。     

Synthesis of brookite-typed titania from titanium chloride solution

The brookite-phase TiO2 was prepared by a hydrothermal synthesis of titanium chloride solution.The thermolysis time and the pH value of the solution were controlled during the synthesis.X-ray diffraction experiments showed that TiO2 powders partially containing the brookite-phase were successfully obtained.A great amount of OH -in the reaction solution was found to be important to obtain the brookite phase because the intermediate complex leading to the brookite phase consumes more OH-than other phases like...     

等离激元纳米流体的光热特性研究

实验研究了利用金属纳米粒子的表面等离激元共振(LSPR)效应增强太阳能光热转换的可行性.采用光化学浸渍方法制备了一种TiO2/Ag复合结构纳米粒子.将这些纳米粒子分散于水中,超声振荡形成TiO2/Ag纳米流体,对其光热转换性能开展实验研究,分析纳米流体的浓度对光热转换性能的影响.结果表明:与不添加纳米粒子的纯水相比,等离激元粒子组成的纳米流体的光热转换性能大大提高.     

Ligand- and cell-dependent determinants of internalization and cAMP modulation by delta opioid receptor (DOR) agonists

Signaling bias refers to G protein-coupled receptor ligand ability to preferentially activate one type of signal over another. Bias to evoke signaling as opposed to sequestration has been proposed as a predictor of opioid ligand potential for generating tolerance. Here we measured whether delta opioid receptor agonists preferentially inhibited cyclase activity over internalization in HEK cells. Efficacy (τ) and affinity (KA) values were estimated from functional data and bias was calculated from efficiency coefficients (log τ/KA). This approach better represented the data as compared to alternative methods that estimate bias exclusively from τ values. Log (τ/KA) coefficients indicated that SNC-80 and UFP-512 promoted cyclase inhibition more efficiently than DOR internalization as compared to DPDPE (bias factor for SNC-80: 50 and for UFP-512: 132). Molecular determinants of internalization were different in HEK293 cells and neurons with βarrs contributing to internalization in both cell types, while PKC and GRK2 activities were only involved in neurons. Rank orders of ligand ability to engage different internalization mechanisms in neurons were compared to rank order of E _max values for cyclase assays in HEK cells. Comparison revealed a significant reversal in rank order for cyclase E _max values and βarr-dependent internalization in neurons, indicating that these responses were ligand-specific. Despite this evidence, and because kinases involved in internalization were not the same across cellular backgrounds, it is not possible to assert if the magnitude and nature of bias revealed by rank orders of maximal responses is the same as the one measured in HEK cells.     

The effectiveness of imprecise probability forecasts

In this paper we investigate the feasibility of algorithmically deriving precise probability forecasts from imprecise forecasts. We provide an empirical evaluation of precise probabilities that have been derived from two types of imprecise probability forecasts: probability intervals and probability intervals with second-order probability distributions. The minimum cross-entropy (MCE) principle is applied to the former to derive precise (i.e. additive) probabilities; expectation (EX) is used to derive precise probabilities in the latter case. Probability intervals that were constructed without second-order probabilities tended to be narrower than and contained in those that were amplified by second-order probabilities. Evidence that this narrowness is due to motivational bias is presented. Analysis of forecasters' mean Probability Scores for the derived precise probabilities indicates that it is possible to derive precise forecasts whose external correspondence is as good as directly assessed precise probability forecasts. The forecasts of the EX method, however, are more like the directly assessed precise forecasts than those of the MCE method.     

Impact of corrections for dynamic selection bias on forecasts of retention behavior

We investigate the impact of corrections for dynamic selection bias on forecasting accuracy in a multi‐period stay/leave model. While corrections for selection bias are needed for consistent coefficient estimates, they do not necessarily produce more accurate forecasts than uncorrected techniques. Theorem 1 shows that, apart from estimation errors, a shrinkage principle applies: the heterogeneity restriction imposed by uncorrected and combination techniques improves accuracy for forecasting individuals that leave, and hurts accuracy for forecasting individuals that stay. This has important implications for decision making because of the potential for asymmetric losses. We also present an illustrative empirical application and results from Monte Carlo experiments. We find that differences in relative accuracy vary directly with the degree of selection bias and inversely with the percentage of the initial population that stays. Copyright © 2007 John Wiley & Sons, Ltd.     

Do forecasts produced by organizations reflect anchoring and adjustment?

In attempting to improve forecasting, many facets of the forecasting process may be addressed including techniques, psychological factors, and organizational factors. This research examines whether a robust psychological bias (anchoring and adjustment) can be observed in a set of organizationally-produced forecasts. Rather than a simple consistent bias, biases were found to vary across organizations and items being forecast. Such bias patterns suggest that organizational factors may be important in determining the biases found in organizationally-produced forecasts.     

不同方法制备的Pt对电极染料敏化太阳能电池的光电性能研究

采用磁控溅射（sputtering）、高温热分解（high-temp）H2Pt Cl6·6H2O溶液和低温化学还原（low-temp）H2Pt Cl6·6H2O溶液等方法在FTO导电基片上制备了三类不同的Pt对电极,通过改变磁控溅射时间或旋涂退火循环次数,对FTO上不同对电极的载Pt量进行了调节.分析了三种不同方法制备的对电极的晶相结构、表面形貌以及透光率等特性.基于纳米管阵列和不同条件制备的对电极组装了系列染料敏化太阳能电池.测量了正照射和背照射条件下的电池光电性能,并分析了制备方法对对电极微结构和形貌的影响,以及对组装电池光电性能的影响,并对其各自的适用性和优缺点进行了比较分析.     

Contribution of divalent cations to the maintenance of membrane potentials in the oocytes of Pleurodeles waltlii Michah (Amphibia, Urodela)]

When the external concentration of Ca and Mg is changed, the oocyte membrane potential, in the Urodela Amphibian: Pleurodeles waltlii, is not significantly modified. The addition of chelator agents, EGTA and EDTA in Ca, Mg free Steinberg solution promotes a membrane depolarisation and the rise of membrane conductance. It is concluded that divalent ions Ca++ and Mg++ are needed to maintain a potential difference between internal and external medium of the oocyte.     

正背栅SOI-MOSFET二维阈值电压解析模型

通过建立沟道区域和埋氧区域的二维泊松方程,并考虑衬底区域的掺杂和背栅偏压对器件阈值电压的影响,得到了一种正背栅全耗尽SOI-MOSFET二维阈值电压模型.根据模型计算结果,研究了衬底掺杂浓度和衬底(背栅)偏压对器件阈值电压的影响,通过与MEDICI数值模拟结果的比较表明,该模型能预计不同衬底掺杂浓度和衬底(背栅)偏压对阈值电压的影响,正确反映器件的短沟效应和背栅效应.