Site-specific immobilization of proteins on a surface has been a long-lasting challenge in the fields of biosensing and biotechnology because of the need for improving the biological activity of ...immobilized protein via the maximal exposure of its bioactive domain. Herein, we reported a new site-specific immobilization method for His-tagged proteins onto a vinyl sulfone (VS)-bearing surface in a covalent manner. X-ray photoelectron spectroscopy characterization indicated the specificity of the addition reaction of the imidazole group in histidine on the VS-bearing surface at pH 7.0. Solution-based experiments were carried out to verify the reaction priority of the imidazole residue of histidine with the VS group at neutral conditions. The real-time immobilization process of two His-tagged proteins (HaloTag-6His and anti-HER2 Fab-6His) on surfaces presenting VS, preactivated carboxyl, and NTA groups were studied by quartz crystal microbalance. Compared to the existing methods utilizing covalent (NHS/EDC activated carboxyl) and coordinate (Ni2+-NTA) linking, our method offers two significant advantages for protein immobilization: high density and high specificity. The orientation of the two His-tagged proteins on the VS-bearing surface was confirmed by an enzyme-linked assay and an HER2+ liposome binding experiment. Our method of site-specific immobilization of His-tagged proteins is efficient and straightforward, which would be helpful to expand the applications of recombinant proteins in enzyme immobilization, biosensor and array fabrication, and drug delivery system.
The similarity of logistics functions of ports and the overlapped economic hinterlands, as well as the competition and mutual effects between port infrastructure contribute to the extremely complex ...service effect between logistics services of ports. How to define the complex network evolution patterns of service effect between different ports becomes essential. This study builds a BBV(Barrat, Barthélemy and Vespignani model) weighted network evolution model to analysis the complex network evolution laws of the service effect of typical seaports in coastal China. We select key assessment factors that affect the service effect of ports, establish a complex network analysis model for port service effect. 15 typical seaports in coastal China are selected for empirical research to verify the practicality and effectiveness of the established model in analysis for complex networks of ports' service effect. The results show that the network presents a hub-and-spoke spatial pattern featuring a small world and no scales, and presents polarized and complex evolution characteristics. The results of this study are conducive to government departments and policy makers for understanding port development and evolution laws, so as to roll out effective strategies as appropriate to manage and promote sustainable development of ports.
The international crude oil maritime transportation system has always been disturbed by the external environment and its own mechanism of supply and demand, which can sometimes last for a long time. ...BDTI (Baltic Exchange Dirty Tanker Index) is one of the most typical indexes in the crude oil maritime transportation market, which is affected by many uncertain events and often lasts for a long time. So it is very significant to study fluctuation characteristics of the crude oil maritime transportation system and assess the impact of critical events, which have been referred to in this paper by improving the R/S model and selecting three international transportation lines in marine shipping ranging from 2008 to 2019. Through model applications, numerical results validate the effectiveness of this method, showing all of the three transportation lines possess long-term memory. The impact of the four critical events has also been evaluated. The study will help crude oil enterprises make investment decision on potential transportation lines and give policymakers advice to maintain stability of the crude oil industry.
Abstract
This article presents a novel functional verification methodology based on the Universal Verification Methodology (UVM) to validate the functionality of the Quick Serial Peripheral Interface ...(QSPI) module. QSPI serves as a prevalent serial communication protocol widely employed for high-speed data exchange with external flash devices. By using the code coverage and functional coverage reports provided by UVM, we were able to assess how well the test cases covered the design code, identifying the parts of the design that had been adequately tested and those that needed more test coverage. This verification method based on UVM provides powerful tools and technical support for the design and development of the QSPI module and effectively ensures its reliability and stability. This study is of great significance for further improving the design quality and verification efficiency of the QSPI module.
The existence of shallow gas seriously affects the stability of seabed formations. In the early stage of the construction of the Jiayong Cross-sea High-speed Railway Bridge, during the preliminary ...survey of the west line of Haiyan, the central sea area of the bridge frequently encountered shallow gas. On the basis of exploration, physicochemical test analysis, etc., the hydrogeological conditions, stratigraphic deposition, and shallow gas distribution and origin of the shallow gas-rich area at the bridge site are discussed, and the possible shallow gas disasters and genesis of the bridge construction at various stages are analyzed. corresponding preventive measures. The research shows that the formation water in this area is mainly Quaternary loose rock pore water, and the gas-bearing soil layer is Quaternary Holocene to Lower Pleistocene alluvial clay and sandy soil, of which the sandy soil layer is the main gas storage layer. The gas belongs to the typical primary type early biogenic gas that is not affecte
Atomically dispersed single-atom catalysts have the potential to bridge heterogeneous and homogeneous catalysis. Dozens of single-atom catalysts have been developed, and they exhibit notable ...catalytic activity and selectivity that are not achievable on metal surfaces. Although promising, there is limited knowledge about the boundaries for the monometallic single-atom phase space, not to mention multimetallic phase spaces. Here, single-atom catalysts based on 37 monometallic elements are synthesized using a dissolution-and-carbonization method, characterized and analysed to build the largest reported library of single-atom catalysts. In conjunction with in situ studies, we uncover unified principles on the oxidation state, coordination number, bond length, coordination element and metal loading of single atoms to guide the design of single-atom catalysts with atomically dispersed atoms anchored on N-doped carbon. We utilize the library to open up complex multimetallic phase spaces for single-atom catalysts and demonstrate that there is no fundamental limit on using single-atom anchor sites as structural units to assemble concentration-complex single-atom catalyst materials with up to 12 different elements. Our work offers a single-atom library spanning from monometallic to concentration-complex multimetallic materials for the rational design of single-atom catalysts.
Dangerous goods are particularly hazardous, as they can be flammable, explosive, and toxic. These characteristics make them vulnerable to accidents, and such mishaps during port operations can lead ...to massive economic losses and even deaths. It is, therefore, necessary and important to analyze and study the dangerous goods accidents at ports, so as to identify major factors and prevent them. Formal concept analysis (FCA) is a powerful tool for rule extraction. This paper introduces FCA along with relevant documents and case studies to analyze the dangerous goods accidents at China’s ports, building a concept lattice model of dangerous goods accidents at China’s ports, and reduces the condition attributes to come up with three key attributes of dangerous goods accidents at China’s ports: warehousing management, facilities and equipment, goods registration and extract four effective diagnostic rules for dangerous goods accidents at ports. This paper proposes corresponding governance strategies to the rules of dangerous goods accidents, which can significantly prevent and manage dangerous goods accidents at China’s ports in the future. In the future, the concept scale can be introduced to study the problem that the influencing factor is multi-valued attribute so as to expand the scope of research.
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•Dangerous goods accidents at ports are small sample events.•Dangerous goods accidents in China’s ports are divided into three types.•Rules exist between dangerous goods accidents and influence factors.•Targeted measures can be taken to reduce dangerous goods accidents.
Eighteen (18) retrogressive thaw slumps (typical landslides in ice-rich permafrost) in northern Canada were monitored for 3 years to investigate the characteristics of their retrogressive behaviour. ...The head scarp retreat distances and scarp wall heights were measured annually. The first year monitoring results from 13 of the sites were released earlier, which demonstrated a correlation between thaw retrogression rate and scarp wall height. More data were obtained from a subsequent 2 years of monitoring and with five monitoring locations added. The additional data enhanced the initial findings that the retrogression rate increased with the increase of the scarp wall height. An updated correlation between the retrogression rate and scarp wall height is presented in this paper. The effect of slope orientation on thaw slump retrogression was also investigated. The data provided evidence that the occurrence of the retrogressive thaw slumps had no preference over slope orientation. The retrogression rates were also not affected by the slope facing direction.
Electrochemical CO
2
reduction reaction (CO
2
RR) to high-value product, CO, not only provides a key feedstock for the well-established Fischer—Tropsch process but also mitigates the greenhouse ...effect. However, it suffers from sluggish reaction kinetics, competitive hydrogen evolution reaction, and low selectivity. Herein, we report non-precious Cu-Sn diatomic sites anchored on nitrogen-doped porous carbon (CuSn/NPC) as an efficient catalyst for CO
2
RR to CO. The catalyst exhibits outstanding selectivity with CO Faradaic efficiency (FE) up to 99.1%, much higher than those of individual Cu (66.2%) and Sn (51.3%) single-atom catalysts. Moreover, high stability is confirmed by consecutive 24 h electrolysis with high selectivity from CO
2
to CO. Theoretical calculations reveal an obvious activation of CO
2
with weakened C—O bonds and distorted CO
2
configuration upon chemisorption on the CuSn/NPC catalyst. It is also suggested CuSn/NPC is more selective for the CO
2
RR with dominant CO production during the electrolysis, rather than the competing hydrogen evolution reaction.
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