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The ultrafast decay dynamics of pyridine-N-oxide upon excitation in the near-ultraviolet range of 340.2–217.6 nm is investigated using the femtosecond time-resolved photoelectron imaging technique. The time-resolved photoelectron spectra and photoelectron angular distributions at all pump wavelengths are carefully analyzed and the following view is derived: at the longest pump wavelengths (340.2 and 325.6 nm), pyridine-N-oxide is excited to the S1(1ππ*) state with different vibrational levels. The depopulation rate of the S1 state shows a marked dependence on vibrational energy and mode, and the lifetime is in the range of 1.4–160 ps. At 289.8 and 280.5 nm, both the second 1ππ* state and the S1 state are initially prepared. The former has an extremely short lifetime of ∼60 fs, which indicates that the ultrafast deactivation pathway such as a rapid internal conversion to one close-lying state is its dominant decay channel, while the latter is at high levels of vibrational excitation and decays within the range of 380–520 fs. At the shortest pump wavelengths (227.3 and 217.6 nm), another excited state of Rydberg character is mostly excited. We assign this state to the 3s Rydberg state which has a lifetime of 0.55–2.2 ps. This study provides a comprehensive picture of the ultrafast excited-state decay dynamics of the photoexcited pyridine-N-oxide molecule. [ABSTRACT FROM AUTHOR]

AbstractHydrogen/deuterium exchange mass spectrometry (HDX-MS) is a sensitive technique used to study the conformational dynamics of proteins in solution. However, performing HDX-MS with N-linked glycoproteins is challenging. Analyzing glycoproteins through HDX-MS requires the use of N-glycoprotein deglycosylation enzyme (peptide: N-glycanase, abbreviated as PNGase) to deglycosylate glycoproteins. Traditional PNGases are inactive or have low activity under HDX-MS operating conditions. Here, we recommend the use of ultra-acidic N-glycopeptidase from PNGase Rc, which exhibits optimal enzymatic activity compared to other PNGases at pH 2.2. We covalently fixed PNGase Rc onto POROS resin for HDX-MS online deglycosylation. The results show that the immobilized PNGase Rc combined with pepsin column has good stability under various quenching conditions. Its online deglycosylation efficiency is better than other PNGases. Meanwhile, we used AlphaFold 2 and molecular dynamics (MD) to characterize the structure and stability of PNGase Rc and other PNGases, and demonstrated that PNGase Rc is the most stable. [ABSTRACT FROM AUTHOR]

Exclusive bus lanes have been widely regarded as an effective way to promote bus priority and improve the service quality, while they have not attracted more passengers to travel by bus in China. Also, more attention is usually paid to the infrastructure and facilities of exclusive bus lanes, but not much attention is paid to the passenger satisfaction of public transit with them. Therefore, this paper studies how to improve the service quality of public transit with exclusive bus lanes from a perspective of passenger satisfaction. A Structural Equation Model (SEM) was developed to investigate the mechanism of relationships between passenger satisfaction and the factors influencing the service quality of public transit with exclusive bus lanes. A total of 2087 respondents from Shanghai, China, participated in this study. Also, a comparison model of different groups using public transit including captive riders, choice riders, and captive by choice riders was established. Results show that passengers were dissatisfied with the current service of public transit with bus lanes, while they would prefer to take buses in the near future. In addition, travel environment, facilities, and convenience, rather than operational efficiency, had significant effects on passenger satisfaction. Through the comparison model, it was found that choice and captive by choice users might prefer public transit with bus lanes and captive users might be unable to bear the financial burden of private motorized travel. 'Crowdedness in the buses on bus lanes during peak hours' especially for choice riders and 'driving stability' especially for captive riders were the improvement direction for attracting more passengers to travel by bus. The results and the proposed policies of this study can benefit for the planning and operations of exclusive bus lanes in Shanghai and other similar cities around the world., Author(s): Linghui He [1]; Dongyuan Yang [1]; Jian Li (corresponding author) [1,2] 1. Introduction Public transit has been considered as an effective way to reduce urban traffic congestion and pollution [...]

The catalytic dehydrogenation of ethanol to acetaldehyde is one of the key technological pathways for the efficient utilization of coal-based ethanol. The development of efficient catalysts, especially copper-based catalysts, plays a crucial role in influencing the industrialization of this technology. The researches on copper-based catalysts for the catalytic dehydrogenation of ethanol to acetaldehyde are summarized. This includes the types of catalyst supports (unsupported, SiO2, ZnO, ZrO2, Al2O3, and carbon), precursor types, catalyst modification, and catalyst preparation methods, all of which have an impact on catalyst performance. Among them, SiO2 and carbon are considered ideal catalyst supports, and copper-based catalysts prepared using organic copper precursors, K or C additives, and ammonia evaporation method exhibit better performance. However, the catalysts' reported lifetimes currently fall short of industrial requirements, or the ethanol concentration in the feedstock is relatively low (≤ 15%, volume fraction). To address these issues, Shaanxi Yanchang Petroleum (Group) Co., Ltd. and Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences jointly developed an efficient catalyst suitable for pure ethanol feeding, with a catalyst life of more than 2600 h, which has a good industrial application prospect. [ABSTRACT FROM AUTHOR]

As the outcomes of rapid urbanization, the spatial separation of homes and workplaces extends the commuting distance and complicates the commuting demand of residents. To promote urban livability and sustainability, it becomes crucially important to understand the commuting patterns by decomposing and simplifying the diverse commuting demand. In this paper, a methodology framework is proposed to describe the spatial structure of commuting demand in a city using mobile phone data. Four steps are mainly included in the proposed methodology: the preprocessing of mobile phone data, the labeling of individuals and their activity points, the construction of the jobs-housing relationship network, and the network decomposition based on the community detection algorithm. To demonstrate the practical use of the proposed methodologies, a case study is carried out in Shanghai to explore the commuting patterns of Shanghai residents. The result indicates the regions with dense jobs-housing connections and cross-regional commuting demand. The result also finds that the administrative boundaries show a significant effect on the residential commuting behavior and the metro lines on the cross-regional commuting behavior. The results generated by the methodology proposed can be referenced by policymakers to support urban transportation planning and promote urban livability and sustainability., Author(s): Qing Yu [1,2]; Weifeng Li (corresponding author) [1]; Dongyuan Yang [1]; Haoran Zhang [2] 1. Introduction Commuting is defined as the regular travel between one's place of residence and [...]

The decay dynamics of 2-aminopyridine and 3-aminopyridine excited to the S1 state is investigated using femtosecond time-resolved photoelectron imaging. The lifetime of the S1 state for both molecules shows a rapid decrease with the increase of the vibrational energy. It is shown that, besides intersystem crossing to the lower-lying triplet state of T1, the decay to the ground state (S0) via internal conversion through a conical intersection plays an increasingly important role and becomes dominant for vibrational states well above the S1 state origin. The comparison between 2-aminopyridine and 3-aminopyridine suggests that the intramolecular hydrogen bonding between a hydrogen atom of the NH2 group and the heterocyclic nitrogen atom in 2-aminopyridine effectively hinders the ring deformation at lower vibrational states which is required for the wavepacket to reach the S1/S0 conical intersection, and therefore slows down the S1 to S0 internal conversion. [ABSTRACT FROM AUTHOR]