浅析以"下界面调式"为基础的朝鲜族民歌

朝鲜族是我国能歌善舞的少数民族之一,具有灿烂的民族文化遗产.以民谣作为基石发展起来的朝鲜族音乐,具有清新、柔美、婉转、明朗、轻快的旋律和丰富多彩的"长短"节奏之美.以民歌题材为分类方式,以下界面调式为研究视角,对朝鲜族民歌的结构进行研究,进而分析出以"下界面调式"为基础的朝鲜族民歌的结构特征及其创作特点.     

新庄特稠油藏蒸汽吞吐井动态特征及水侵识别分析

河南新庄油田核桃园组的油藏是典型的边水驱动特稠油藏,在分析温度对分流方程的影响后,对该区蒸汽吞吐生产井的含水率变化规律进行了总结.根据油藏的实际地质特征,建立了数值模型,对所总结的含水率变化规律进行了模拟验证.在此基础上,结合存水量变化等参数,提出了一种综合判断地层水侵入规律的方法.实际的开采井动态分析证明了该判断方法的可行性,对类似的水侵特稠油藏的生产动态分析有借鉴作用.     

川西坳陷中段须四段钙屑砂岩储层特征及有利区块预测

钙屑砂岩通常较致密,储集性往往很差.在大量薄片鉴定及物性统计基础上,对须家河组T3x45砂组钙屑砂岩的岩石学、物性特征及其主要控制因素进行了详细研究,结果表明该套砂组的钙屑砂岩次生孔隙较发育,为有效的储集层,储层物性主要受控于沉积相、压实作用、溶蚀作用及构造作用等因素,其中溶蚀作用和构造破裂作用是储层发育最重要的控制因素.在储层特征及其与沉积相发育关系分析的基础上,以T3x45砂组为编图单元编制沉积微相图和砂体等厚图,预测钙屑砂岩储层平面分布特征,并对有利储层发育区块进行预测和评价,识别出3个具有较大勘探潜力的储集砂体.     

无溶剂法大量制备高效红光碳点及其在白光器件中的应用

以邻苯二胺、 2,5-二氨基苯磺酸和三氯化铝为原料, 通过无溶剂法大量制备了高效的红色荧光碳点 (R-CDs). 制得的碳点尺寸大约为2.4 nm, 含有13%的氮元素, 主要由高度石墨化的碳核及覆盖在其表面的大量官能团构成. 在不同的波长光激发下, 碳点在乙醇溶液中表现出不依赖于激发的红光发射, 其荧光峰位于 704 nm, 最大量子产率达到22%. 由于R-CDs具有优异的光学性质, 利用其构筑了紫外光激发的碳基白色发光二极管, 其色坐标为(0.33, 0.33), 非常接近自然光. 该研究为高效红色荧光碳点的大量制备提供了一种新路径, 同时拓宽了其在白光器件中的应用.     

Batch versus Flow Photochemistry: A Revealing Comparison of Yield and Productivity

The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20 % lower than that of batch, whereas three‐layer reactors were 20 % more productive. Finally, the utility of flow chemistry was demonstrated in the scale‐up of the ring‐opening reaction of a potentially explosive [1.1.1] propellane with butane‐2,3‐dione.     

Different defect morphologies in polyethylene crystal induced by surface physicochemical properties

The physicochemical properties of surfaces have a great effect on the micro-morphologies of the crystal structures which are in contact with them.Understanding the interaction mechanism between the internal driving forces of the crystal and external inducing forces of the surfaces is the prerequisite of controlling and obtaining the desirable morphologies.In this work,the dynamic density functional theory was applied to construct the free energy functional expression of polyethylene(PE) lattice,and the micro-dynamic evolution processes of PE lattice morphology near the surfaces with different properties were observed to reveal the interaction mechanism at atomic scale.The results showed that the physical and chemical properties of the external surfaces synergistically affect the morphologies in both the defect shapes and the distribution of the defect regions.In the absence of the contact surfaces,driven by the oriented interactions among different CH2 groups,PE lattices gradually grow and form a defect-free structure.Conversely,the presence of contact surfaces leads to lattice defects in the interfacial regions,and PE lattice shows different self-healing abilities around different surfaces.     

Demystifying terms for understanding bioelectrochemical systems towards sustainable wastewater treatment

Bioelectrochemical systems (BESs) have been intensively studied in the past decade, but precise understanding of BESs performance is hindered by unclear definition of several key parameters. Herein, we analyze and discuss three sets of terms about conversion efficiency, energy performance, and pilot scale. It is suggested that ‘Coulombic recovery’ can avoid the misleading results because of different organic removals, compared with ‘Coulombic efficiency.’ Power density is not a suitable term to describe energy performance of BESs, and energy production/consumption should be reported in the energy unit such as kWh. Pilot-scale BESs should meet several criteria, including hydraulic capacity, use of actual wastewater, non-laboratory condition, and long-term operation. Proper use of those terms is strongly encouraged and will be critically important to BESs research and development.     

Real‐Time Atomic‐Scale Visualization of Reversible Copper Surface Activation during the CO Oxidation Reaction

By using in situ aberration‐corrected environmental transmission electron microscopy, for the first time at atomic level, the dynamic evolution of the Cu surface is captured during CO oxidation. Under reaction conditions, the Cu surface is activated, typically involving 2–3 atomic layers with the formation of a reversible metastable phase that only exists during catalytic reactions. The distinctive role of CO and O₂ in the surface activation is revealed, which features CO exposure to lead to surface roughening and consequently formation of low‐coordinated Cu atoms, while O₂ exposure induces a quasi‐crystalline CuOx phase. Supported by DFT calculations, it is shown that crystalline CuOx reversibly transforms into the amorphous phase, acting as an active species to facilitate the interaction of gas reactants and catalyzing CO oxidation.     

Study on wave dispersion characteristics of piezoelectric sandwich nanoplates considering surface effects

In this study, the wave propagation properties of piezoelectric sandwich nanoplates deposited on an orthotropic viscoelastic foundation are analyzed by considering the surface effects (SEs). The nanoplates are composed of a composite layer reinforced by graphene and two piezoelectric surface layers. Utilizing the modified Halpin-Tsai model, the material parameters of composite layers are obtained. The displacement field is determined by the sinusoidal shear deformation theory (SSDT). The Euler-Lagrange equation is derived by employing Hamilton’s principle and the constitutive equations of piezoelectric layers considering the SEs. Subsequently, the nonlocal strain gradient theory (NSGT) is used to obtain the equations of motion. Next, the effects of scale parameters, graphene distribution, orthotropic viscoelastic foundation, and SEs on the propagation behavior are numerically examined. The results reveal that the wave frequency is a periodic function of the orthotropic angle. Furthermore, the wave frequency increases with the increase in the SEs.