Low-temperature catalytic decomposition of hydrogen sulfide on metal catalysts under layer of solvent

When hydrogen sulfide decomposition {2 H₂S ? 2 H₂?+?S₂^(gas)} is carried out in the flow regime at room temperature on metal catalysts placed in a liquid capable of dissolving H₂S and sulfur, the reaction equilibrium can be significantly (up to 100%) shifted to the right yielding the desired product – hydrogen. The process efficiency was demonstrated using aqueous solutions of monoethanolamine (MEA), sodium carbonate, which is widely used in industry for H₂S absorption from tail gases, and aqueous hydrazine as examples. IR and Raman spectroscopy data demonstrated that sulfur obtained in the solutions is in the form of diatomic molecules. DFT calculations showed that diatomic sulfur forms weakly bound coordinative complexes with solvent molecules. Some problems related to sulfur accumulation and recovery from the solvents are discussed.     

Triplet Exciton Confinement in Green Organic Light‐Emitting Diodes Containing Luminescent Charge‐Transfer Cu(I) Complexes

The temperature dependence of luminescence from [Cu(dnbp)(DPEPhos)]BF₄ (dnbp = 2,9‐di‐n‐butylphenanthroline, DPEPhos = bis[2‐(diphenylphosphino)phenyl]ether) in a poly(methyl methacrylate) (PMMA) film indicates the presence of long‐life green emission arising from two thermally equilibrated charge transfer (CT) excited states and one non‐equilibrated triplet ligand center (³LC) excited state. At room temperature, the lower triplet CT state is found to be the predominantly populated excited state, and the zero‐zero energy of this state is found to be 2.72 eV from the onset of its emission at 80 K. The tunable emission maximum of [Cu(dnbp)(DPEPhos)]BF₄ in various hosts with different triplet energies is explained in terms of the multiple triplet energy levels of this complex in amorphous films. Using the high triplet energy charge transport material as a host and an exciton‐blocking layer (EBL), a [Cu(dnbp)(DPEPhos)]BF₄ based organic light‐emitting diode (OLED) achieves a high external quantum efficiency (EQE) of 15.0%, which is comparable to values for similar devices based on Ir(ppy)₃ and FIrpic. The photoluminescence (PL) and electroluminescence (EL) performance of green emissive [Cu(μI)dppb]₂ (dppb = 1,2‐bis[diphenylphosphino]benzene) in organic semiconductor films confirmed its ³CT state with a zero‐zero energy of 2.76 eV as the predominant population excited state.     

Singlet‐Triplet Transition in the C60 2− Dianion

Abstract

The C₆₀ complexes with decamethylcobaltocene: (Cp*₂Co)₂C₆₀(C₆H₄Cl₂, C₆H₅CN)₂ (1) and [K · (18‐crown‐6)]₂ · C₆₀ · (DMF)₄ (2) have been obtained as single crystals by the diffusion method. The IR‐ and UV‐VIS‐NIR‐spectra justify the formation of the C₆₀ ^2? dianions in these salts. EPR measurements show that the low temperature signals of 1 in the 4–140 K range and 2 in the 4–60 K range have intensity corresponding only to 0.4% and 3.5% from total C₆₀. Because of this, most of the complexes are EPR silent, and, consequently, C₆₀ ^2? has a diamagnetic singlet (S = 0) state in these temperature ranges. The appearance of a broad EPR signal in the spectum of 1 above 140 K and 2 above ～60 K is assigned to a thermal population of a close lying excited triplet (S = 1) state. The singlet–triplet energy gap for C₆₀ ^2? in solid 1 and 2 was estimated to be 730 ± 10 and 300 ± 10 cm^?1.     

Deep blue phosphorescent organic light-emitting diodes with excellent external quantum efficiency

Highly efficient deep blue phosphorescent organic light-emitting diodes (PHOLEDs) using two heteroleptic iridium compounds, (dfpypy)₂Ir(acac) and (dfpypy)₂Ir(dpm), as a dopant and 9-(3-(9H-carbazol-9-yl)phenyl)-9H-carbazol-3-yl)diphenylphosphine oxide as a host material have been developed. The electroluminescent device of (dfpypy)₂Ir(dpm) at the doping level of 3 wt% shows the best performance with external quantum efficiency of 18.5–20.4% at the brightness of 100–1000 cd/m² and the color coordinate of (0.14, 0.18) at 1000 cd/m².     

Thermogravimetric study on the pressurized hydropyrolysis kinetics of a lignite coal

Hydropyrolysis of coal is considered to be a third coal conversion technology between the coal liquification and gasification technologies. It is also the primary process for coal hydrogasification (CHG). However, the detailed kinetic characteristics of coal hydropyrolysis (CHP) are still rarely studied, which is adverse to the further development of the CHP and CHG technologies. In this work, the hydropyrolysis kinetics of a lignite coal is studied in a pressurized thermogravimetric analyzer (P-TGA). The non-isothermal thermogravimetric method is used and the effect of pressure on the pyrolysis kinetics of the lignite coal is detected. Finally, some useful results are found from the analyses for the lignite hydropyrolysis under P-TGA. With the increment of the pyrolysis pressure, the initial pyrolysis temperature increases when the pressure is higher than 1 MPa; the temperature span of the pyrolysis process shrinks; the weight loss peak value position of the derivative thermogravimetric (DTG) curve shifts rightwards when the pressure is lower than 1 MPa, while it shifts leftwards when the pyrolysis pressure is higher than 1 MPa; the reaction process will be restrained when the pressure is lower than 2 MPa. In addition, the kinetic triplets including the pre-exponential factor, the activation energy and the kinetic mechanism function are defined for the hydropyrolysis process under different pressures.     

三重环流生物流化床反应器的混合特性

研究了三重环流生物流化床反应器混合特性,通过循环时间与混合时间的测定来比较三重环流五单重环流反应器的混合性能,发现三重环流反应器的混合时间较短。此外,对三重环流反应顺的物料分布测试结果可知正常流态化条件下所有工况其物料分布均接近全混流模型,离散程度随操作液流量的增大而减小,亦随操作气速的增大而变小。     

基于三元损失的保险业务牛脸识别系统的设计北大核心CSCD

针对当前畜牧保险行业勘察、定损中牛身份识别难的问题,本文将深度学习框架与物联网(internet of things,IOT)技术结合构建牛脸识别系统。系统中以Inception_Resnet_v1作为深度学习网络框架,结合Triplet Loss损失函数,完成牛面部特征的提取,通过计算余弦距离对特征进行身份识别。基于flask和vue框架布署牛脸检测和特征提取及验证模型,开发牛脸信息数据库,提供身份注册和验证web服务。为验证系统可行性,采集并制作牛脸识别数据集CFID200,在20%未见牛脸的条件下,牛脸识别系统准确率与验证率达到95%以上,满足保险业务牛脸身份识别需要。     

基于非局部3D残差网络的视频指纹算法

为了实现视频拷贝的快速准确检索,提出一种基于非局部3D残差网络的紧凑视频指纹。该算法以三胞胎网络架构为基础,采用非局部模块3D残差网络同时捕获视频的全局与局部时空信息,在特征提取部分末端加入量化编码层,实现了原始视频数据到离散指纹码的端到端映射;设计了由角度关系三元组损失和量化误差损失组成的网络目标函数。大量的实验结果表明,与对比算法相比,该算法在保持紧凑的同时鲁棒性与独特性均表现突出,查准率与查全率有明显提升。     

Characterizing quasi-metric aggregation functions

ABSTRACT

In this paper, we study those functions that allows us to combine a family of quasi-metrics, defined all of them on the same set, into a single one, which will be called quasi-metric aggregation functions. In particular, we characterize the quasi-metric aggregation functions and, in addition, we discuss a few of their properties. Moreover, a few methods to discard those functions that are useless as quasi-metric aggregation functions are introduced. Throughout the paper, different examples justify and illustrate the results presented. Finally, two possible fields where the developed theory can be useful are exposed.     

光诱导4-硝基喹啉氧化物与甲硫氨酸衍生物的电子转移

利用纳秒级激光光解瞬态吸收光谱装置,研究了４－硝基喹啉氧化物（４ＮＱＯ）与含硫氨基酸及其肽的光化学反应。水溶液中的４ＮＱＯ被２４８ｎｍ激光激发,生成４ＮＱＯ三重态,并在４１０ｎｍ和５９０ｎｍ观察到它的特征吸收,４ＮＱＯ激发三重态能被甲硫氨酸及其肽猝灭,其过程是电子转移反应,生成４ＮＱＯ的加氢自由基和甲硫氨酸及其肽抽氧自由基。