镧系离子对钛酸钡陶瓷结构的修改在介电领域的进展

元素周期表中的镧系包含14种元素,作为“现代化学工业维他命”,当它们的离子被并入钛酸钡晶格中时,可以大大降低钛酸钡的介电损失、温度系数和晶粒尺寸,适于电子器件微小化和成为替代目前的基于钛酸铅高介电材料的环境友好材料,并提高钛酸钡的介电性能.因此,镧系离子对钛酸钡陶瓷结构的修改以提高钛酸钡陶瓷的介电物性在高介电材料基础研究与应用领域成为当前国际上的一个热点.在这篇评论中,系统地评价镧系离子因镧系收缩而并入钛酸钡陶瓷的位占据倾向、介电响应规律、一级相变和扩散相变、以及材料在室温高介电扩散的实现.     

一种集成空间分解与占用的精确碰撞检测算法及其在建筑工程中的应用

碰撞检测是建筑工程三维CAD中行之有效的辅助手段, 现代建筑形式复杂、规模庞大, 对碰撞检测算法的效率提出了更高的需求。该文基于空间分解和空间占用这两种应用最为广泛的预处理方法, 提出了一种集成、高效的精确碰撞检测算法。通过工程实例的测试和分析, 该集成算法的检测效率优于其他几种算法, 且模型量越大, 效率优势越明显。该文还针对建筑工程的实际应用需求, 对集成算法进行改进, 并应用于实际工程, 验证了算法的有效性和鲁棒性。实际应用表明, 该集成算法适用于建筑、结构、机电、幕墙等专业设计之间的碰撞检测。     

基于云计算的航空飞行试验数据中心任务调度优化架构设计

为解决航空飞行试验数据中心任务调度行为明显滞后的问题,实现对航空飞行试验数据的实时调度,设计基于云计算的航空飞行试验数据中心任务调度优化架构。设置WiRo中心网络,联合试验数据预测器与飞行任务分配器,完善中心任务调度优化架构体系的基础应用结构设计。根据PSO优化度量值的取值范围,求解惯性权重指标与粒子编码条件,并按照云计算法则,推导函数表达式条件,实现基于云计算的航空飞行试验数据调度模型的构建。在动态数据权限的约束下,计算中心调度任务的资源占用率与长尾延迟参数,实现对任务调度架构的优化配置,联合WiRo中心网络及EMU调度结构,完成基于云计算的航空飞行试验数据中心任务调度优化架构的设计。实验结果表明,云计算技术作用下,单位时间内的数据吞吐量达到了9.85B/s,由数据吞吐量有限造成的中心任务调度行为滞后的问题得到较好解决,符合实时调度航空飞行试验数据的实际应用需求。     

分布式电磁频谱自动监测系统研制

为实现对多个区域的电磁环境同时进行监测,分析了分布式电磁监测系统的设计原则,确立了监测系统的硬件连接方案,利用以太网-GPIB控制器、集线器和控制计算机来对多台仪器进行集中控制的方式,设计了相应的系统软件。测试结果表明,该系统具备同时控制多台频谱分析仪的功能,能够实时测量电磁频谱、背景噪声、频段占用度等数据,具备测量数据存储、回放与分析、报表生成的功能,具有状态反馈和异常状态提示的功能,完全能满足多个区域电磁监测的要求。     

1-[2-(1-Cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one: a Histamine H3 Receptor Inverse Agonist with Efficacy in Animal Models of Cognition

A series of chemical optimizations, which was guided by in vitro affinity at histamine H₃ receptor (H₃R), modulation of lipophilicity, ADME properties and preclinical efficacy resulted in the identification of 1-[2-(1-cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one ( 45 e ) as a potent and selective (K_i=4.0 nM) H₃R inverse agonist. Dipsogenia induced by (R)-α-methylhistamine was dose dependently antagonized by 45 e , confirming its functional antagonism at H₃R. It is devoid of hERG and phospholipidosis issues. Compound 45 e has adequate oral exposures and favorable half-life in both rats and dogs. It has demonstrated high receptor occupancy (ED₈₀=0.22 mg/kg) and robust efficacy in object recognition task and, dose dependently increased acetylcholine levels in brain. The sub-therapeutic doses of 45 e in combination with donepezil significantly increased acetylcholine levels. The potent affinity, selectivity, in vivo efficacy and drug like properties together with safety, warrant for further development of this molecule for potential treatment of cognitive disorders associated with Alzheimer's disease.     

Simultaneous improvement of coercivity and saturation magnetization of M-type strontium ferrite by Nd3+-Co2+ unequal co-substitution

We synthesized Sr_1-xNd_xFe_12-yCo_yO₁₉ (x = 0–0.25, y = 0–0.1) using a conventional ceramic route. The crystal structures were analyzed using X-ray diffraction. With increasing Nd³⁺ and Co²⁺ contents, lattice constant a increases, while lattice constant c decreases. In terms of magnetic properties, the saturation magnetization and coercivity are simultaneously increased when x = y = 0.1 (equal co-substitution). This is mainly because the bivalent Co²⁺ has a smaller magnetic moment and unquenched orbital moments. When substitution amount x is further increased (unequal co-substitution), the magnetic properties are further improved and reach the optimum values of M_s = 76.4 emu/g and H_c = 5115 Oe owing to the occupation of the 2a site by divalent Fe²⁺. The occupancies of Co²⁺ and Fe²⁺ are further verified using Raman spectroscopy.     

Tailoring Antibonding-Orbital Occupancy State of Selenium in Se-Enriched ReSe2+x Cocatalyst for Exceptional H2 Evolution of TiO2 Photocatalyst

Electron density regulation of active sites can realize an optimal hydrogen-binding strength, whereas the underlying regulation mechanism is still indistinct. Herein, a new concept of antibonding-orbital occupancy state is first proposed to unveil the fundamental influence mechanism of electron density on the Se H_ads bond strength for achieving first-rank adsorption energy toward atomic hydrogen by constructing Se-enriched surrounding to form electron-deficient Se^(2-δ)- active sites in ReSe_2+x nanodots. To this end, the Se-rich ReSe_2+x nanodots (0.3–1 nm) can be dexterously fabricated onto the TiO₂ to prepare Se-rich ReSe_2+x/TiO₂ by an ingenious one-step photosynthesis route. In a surprise, a large number of visual H₂ bubbles are continuously produced on the resultant ReSe_2+x/TiO₂(0.7 wt.%) with an ultrahigh rate of 12 490.4 µmol h⁻¹ g⁻¹ and an apparent quantum efficiency of 60.0%, which is 5.0 times higher than that of traditional ReSe₂/TiO₂, even comparable with benchmark Pt/TiO₂(0.7 wt.%). In situ/ex situ XPS characterizations coupled with density functional theory (DFT) calculations corroborate that a Se-enriched environment can induce the formation of electron-deficient Se^(2-δ)− and then reduce its antibonding-orbital occupancy state, thus increasing the stability of H 1s-p antibonding and accordingly reinforcing the Se H_ads bonds. This holistic study identifies the dominant role of antibonding-orbital occupancy states in the optimization of hydrogen-binding energy.     

Codoping Ti in low Co-containing hibonite achieving excellent optical properties for near-infrared reflective pigment applications

To reduce carcinogenic cobalt content in pigments, a series of near-infrared reflective pigments based on CaAl_12-x-yCo_xTi_yO₁₉ (x = 0–0.5 and y = 0-(x+0.3)) were prepared via solid state reactions. Although the cobalt content in the pigment CaAl_11.7Co_0.1Ti_0.2O₁₉ is only 0.87% by mass, the resulting pigment still has excellent color properties (64.89, 3.88, ?40.30) and near-infrared reflectance (～70%). The structural information of the obtained pigments were analyzed by XRD refinement, and the results revealed that the doping concentration of titanium relative to cobalt significantly affected the coordination structure of cobalt in hibonite, which in turn apparently influenced the optical properties of the obtained samples. The actual cooling effect of the CaAl_11.7Co_0.1Ti_0.2O₁₉ coating was tested using a model house and the annual energy consumption was simulated by using EnergyPlus software. For a warm city (Haikou), using this CaAl_11.7Co_0.1Ti_0.2O₁₉ coating can reduce energy consumption for cooling by 24.75%.