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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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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   
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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   
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Crystal engineering, as a burgeoning technology, has been widely used to construct metalloporphyrins biomimetic catalysts. Herein, a bimetallic metal-organic framework (MOF) was constructed by 4-(4-carboxyphenyl)-1,2,4-triazole ligand, Co2+ and Zr4+ metal ions by solvothermal reaction(named PFC-88). A N,N-chelation site was found between the two adjacent ligands in PFC-88, consequently a porphyrin-like structure was obtained through chelating Fe3+ in this site by post-modification, named PFC-88-Fe. The result of a single crystal X-ray technology verified that Fe ions were successfully metalated in the N,N-chelation site of PFC-88, which is assisted by the X-ray absorption near-edge structure(XANES) spectra. An o-phenylenediamine oxidation reaction was applied to assessing the catalytic activity of PFC-88-Fe, in which the absorbance increases of phenazine-2,3-diamine at λ=418 nm were recorded by absorption spectroscopy in kinetic mode, exhibiting the application potential as a biomimetic catalyst.  相似文献   
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Compound 2β-carbomethoxy-3β-(4-chlorophenyl)tropane (β-CCT) is a key intermediate for the synthesis of some clinical dopamine transporter (DAT) imaging agents. Potential impurities from synthesis process of β-CCT and degradation during storage might have detrimental effect on the final imaging agents. Thus, it is necessary to guarantee the quality of β-CCT. In this study, a rapid, sensitive and accurate high-performance liquid chromatography (HPLC) method was developed and validated for the analysis of β-CCT and its related substances. The chromatographic separation was achieved on a reverse-phase phenomenex? Gemini C18 column with an isocratic mobile phase consisted of methanol, water and TFA (30:70:0.1 v/v/v). The flow rate was 1.0 mL/min at 30 °C and samples were monitored at 220 nm. The method was validated concerning system suitability, linearity, accuracy, precision, specificity, robustness and stability. The limit of detection (LOD) and the limit of quantification (LOQ) of β-CCT were 0.5 and 1.5 μg/mL, respectively. The linearity range of β-CCT was 1.5–450 μg/mL with a good linear correlation coefficient (R2 = 0.9999) between the peak response and concentration. Specificity investigation through forced degradation experiments displayed that β-CCT was stable in acidic, thermal and photolytic degradation conditions, but significantly unstable in alkaline and oxidative conditions. With the developed chromatographic method, possible impurity α-CCT from synthetic process and potential degradation products could be well separated from β-CCT. Good recovery and precision were manifested in the assay method. These results indicated that the present method would be suitable for not only the quality assurance of β-CCT in regular production sample assays but also the monitoring and determination of its related substances.  相似文献   
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