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Dehydrogenation of an organic compound is the first and the most fundamental elementary reaction in many organic reactions. In ethanol oxidation reaction (EOR) to form CO2, there are a total of 46 pathways in C2HxO (x=1–6) species leading to the removal of all six hydrogen atoms in five C−H bonds and one O−H bond. To investigate the degree of dehydrogenation in EOR under operando conditions, we performed density function theory (DFT) calculations to study 28 dehydrogenation steps of C2HxO on Ir(100). An activation energy surface was then constructed and compared with that of the C−C bond cleavages to understand the importance of the degree of dehydrogenation in EOR. The results show that there are likely 28 dehydrogenations in EOR under fuel cell temperatures and the last two hydrogens in C2H2O are less likely cleaved. On the other hand, deep dehydrogenation including 45 dehydrogenations can occur under ethanol steam reforming conditions.  相似文献   
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Having shown promising performance with high flexibility and efficiency in vehicular edge computing (VEC) network, the parked vehicles (PVs) received an increasing number of attentions in recent years. However, PVs’ residual battery power restricts their running time. In addition, there is still no alternate resource pool for the PVs to cope with the emergencies in the previous VEC framework. To alleviate these problems, we model a cloud-assisted parked vehicular edge computing (PVEC) framework, in which the PVs are classified based on their residual battery power. PVs corporate with the cloud servers (CSs) for the computational resources provision. In addition, we formulate the utilities of the service provider (SP) and PVs and design a contract-based resource allocation problem for the maximization of the SP’s utility. Considering that it is intractable to solve the optimization problem directly, the primal problem is simplified and decoupled into two sub-problems. To design the optimal contracts, we solve the sub-problems by Lagrangian multiplier method and dual function. Simulation results prove that the utilities of PVs can reach to the maximum when they choose the contract corresponding to their types. In addition, the simulation results illustrate the superiority of proposed scheme over previous schemes in improving the utilities of the SP and social welfare.  相似文献   
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利用微环谐振腔阵列进行光码分多址编解码过程中,微环谐振腔反射谱的自由频谱宽度(FSR)范围制约该系统用户容量的提升.本文提出了一种新型的基于游标效应的串联哑铃型微环谐振腔光编解码器.利用Matlab建立了半径分别为40μm-30μm-40μm的哑铃型微环谐振腔光编解码器模型.详细分析了光反射谱伪模抑制与耦合系数的关系,研究了耦合系数、码片速率对串联哑铃型微环谐振腔光编解码器性能的影响.结果表明,与半径分别为40μm-40μm-40μm的传统串联微环谐振腔编解码器相比,哑铃型微腔编解码器FSR值扩大了4倍.理想情况下,用户容量可呈指数增长.同时,互相关峰值比(P/W)与自相关峰值旁瓣比(P/C)分别提高了约33%和8%.  相似文献   
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The ultrasound-assisted extraction (UAE) was conducted using the stainless steel (SS) and polyether ether ketone (PEEK) columns and analyzed with high-performance liquid chromatography (HPLC) to understand the mechanism of ultrasound-assisted chromatography (UAC). Empty SS and PEEK columns were used to extract dyes from a fabric under identical conditions with several parameters including the initial ultrasonic bath temperatures (30 °C and 40 °C), ultrasound power intensities (0, 20, 40, 60, 80, and 100 %), ultrasound operation modes (normal and sweep), and ultrasound frequencies (25 kHz, 40 kHz, and 132 kHz) to compare their extraction capabilities. After 30 min of extraction, the amount of extract was determined by HPLC. The PEEK material was significantly affected by ultrasonic radiation compared to the SS material, especially at a higher temperature (40 °C), power intensity (100 %), and frequency (132 kHz) with sweep mode. At a maximum power density of 45 W/L, the extraction effectiveness ratio of PEEK to SS was in the range of 1.8 - 3.9 depending on the specific frequency, initial temperature, and with or without temperature control. The most optimal ultrasound frequencies, in terms of enhancing extraction effectiveness, are in the order of 132 kHz, 40 kHz, and 25 kHz. Unlike the SS material, the PEEK material was more affected by temperature and acoustic effects under identical conditions, especially at 132 kHz ultrasound frequency. In contrast, at lower frequencies of 40 kHz and 25 kHz, no significant differences in the acoustic effects were observed between the PEEK and SS materials. The findings of this study contribute to elucidating the roles of column materials in UAE and UAC.  相似文献   
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双电解液锂空气电池因其高理论能量密度受到广泛研究,但电池正极侧氧还原反应(ORR)速率低,其反应速率是限制锂空气电池发展的主要因素之一.本文提出了以钌(Ru)掺杂单层石墨烯作为正极ORR催化剂,采用第一性原理计算nRu (n=1~3)掺杂石墨烯的电子结构和氧气在Ru掺杂石墨烯表面的吸附性能,并以过渡态搜索方法获得ORR反应路径,研究碱性溶液中Ru掺杂单层石墨烯作用下的ORR机理.研究结果表明,经Ru原子掺杂后,石墨烯能够获得稳定的掺杂结构,且电导率显著提升.同原始单层石墨烯相比,Ru掺杂石墨烯增强了对O2的吸附能力.在三Ru(n=3)掺杂石墨烯表面进行的ORR无需克服任何能垒.此外,三Ru掺杂石墨烯表面对OH基团的吸附能最低,有利于ORR的连续进行.研究表明三Ru掺杂石墨烯有望成为一种新型的ORR催化剂以提高双电解液锂空气电池的性能.  相似文献   
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Dibenzyl trisulfide (DTS) is a natural compound with potential cancer-preventive properties occurring in Petiveria alliacea L., an ethnomedicinal plant native to the Americas. Previous studies revealed its inhibitory activity toward cytochrome P450 (CYP)1 enzymes, key in the activation of environmental pollutants. Accordingly, the aim of this study was to design novel DTS analogues, aimed at improving not only inhibitory activity, but also specificity toward CYP1A1. This was achieved by targeting interactions with CYP1A1 residues of identified importance. Three-dimensional structures for the novel analogues were subjected to molecular docking with several CYP isoforms, before being ranked in terms of binding affinity to CYP1A1. With three hydrogen bond donors, two hydrogen bond acceptors, a molecular mass of 361 Da, and a log P of 3.72, the most promising DTS analogue obeys Lipinski's rule of five. Following synthesis and in vitro validation of its CYP1A1-inhibitory properties, this compound may be useful in future cancer-preventive approaches.  相似文献   
9.
Yinlu Gao 《中国物理 B》2022,31(11):117304-117304
The GaN-based heterostructures are widely used in optoelectronic devices, but the complex surface reconstructions and lattice mismatch greatly limit the applications. The stacking of two-dimensional transition metal dichalcogenide (TMD = MoS2, MoSSe and MoSe2) monolayers on reconstructed GaN surface not only effectively overcomes the larger mismatch, but also brings about novel electronic and optical properties. By adopting the reconstructed GaN (0001) surface with adatoms (N-ter GaN and Ga-ter GaN), the influences of complicated surface conditions on the electronic properties of heterostructures have been investigated. The passivated N-ter and Ga-ter GaN surfaces push the mid-gap states to the valence bands, giving rise to small bandgaps in heterostructures. The charge transfer between Ga-ter GaN surface and TMD monolayers occurs much easier than that across the TMD/N-ter GaN interfaces, which induces stronger interfacial interaction and larger valence band offset (VBO). The band alignment can be switched between type-I and type-II by assembling different TMD monolayers, that is, MoS2/N-ter GaN and MoS2/Ga-ter GaN are type-II, and the others are type-I. The absorption of visible light is enhanced in all considered TMD/reconstructed GaN heterostructures. Additionally, MoSe2/Ga-ter GaN and MoSSe/N-ter GaN have larger conductor band offset (CBO) of 1.32 eV and 1.29 eV, respectively, extending the range from deep ultraviolet to infrared regime. Our results revel that the TMD/reconstructed GaN heterostructures may be used for high-performance broadband photoelectronic devices.  相似文献   
10.
毛赫南  王晓工 《物理化学学报》2022,38(4):2004025-52
氧化石墨烯(GO)片的基面和边缘上存在大量的含氧官能团,能很好地分散在水中,因而具有很好的加工性和广阔的应用前景。在较高浓度范围下,GO水分散液中存在着强烈的竞争性相互作用,从而对流变行为产生较大影响。在本文中,通过稳态、动态等流变实验以及理论分析,研究了pH值、温度和不同的有机溶剂对GO分散液流变行为的影响。结果表明,降低pH值、适当增加温度以及加入吡啶均可促进GO水分散液从粘弹性液体到凝胶态的转变。利用DLVO (Deryagin-Landau-Verwey-Overbeek)理论,探讨了GO片之间的范德华作用力以及双电层排斥作用的相互关系,及其对流变性能的影响。通过群体平衡模型(PBE)分析了GO分散液的屈服应力与体积分数的正相关关系。同时,通过蠕变和松弛实验发现,高浓度的GO分散液中结构变化及流变行为在很多方面与高聚物相似,利用Poyting-Thomson模型能较好地拟合其粘弹性行为。上述研究结果为深入研究复杂的GO分散体系提供理论支撑和实验依据。  相似文献   
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