•Thermoset epoxy resins enhance pavement performance of epoxy materials.•The three-dimensional crosslinking network of epoxy resin restricts asphalt move.•Epoxy emulsified asphalt cures at ambient ...temperature and reduce energy-consumption.•Epoxy resin provides theoretical basis for self-healing of concrete.
Epoxy materials in the pavement behave well in thermal stability, mechanical properties, adhesive properties, corrosion and chemical resistance, due to unique three-dimensional crosslinking network structure and special functional groups. This review presents a summary mainly about the chemistry of epoxy resins, the curing mechanism and properties of epoxy materials covering epoxy asphalt, epoxy emulsified asphalt and epoxy concrete. Thereinto, the opening-ring mechanism, the polymerization mechanism and the formation of network provide scientific guidance for the actual composite process of epoxy materials. The addition of epoxy resins can enhance the high-temperature stability and mechanical properties of epoxy asphalt, epoxy emulsified asphalt and their mixtures, because the crosslinking network of epoxy resin restricts the movement of asphalt. Additionally, it is pointed out that epoxy concrete has excellent chemical resistance and high bond strength. Moreover, the curing of epoxy resin without curing agents can be catalyzed in the presence of cement, which gives a way to achieve self-healing of concrete. Hence, epoxy materials in the pavement can be a suitable alternative towards the high-temperature stability, excellent bonding adhesion and mechanical performance of pavement materials.
Reported herein is the synthesis of benzofused six‐membered S‐heterocycles by intramolecular dehydrogenative C−S coupling using a modular flow electrolysis cell. The continuous‐flow electrosynthesis ...not only ensures efficient product formation, but also obviates the need for transition‐metal catalysts, oxidizing reagents, and supporting electrolytes. Reaction scale‐up is conveniently achieved through extended electrolysis without changing the reaction conditions and equipment.
Electric flow: The synthesis of benzofused six‐membered S‐heterocycles by intramolecular dehydrogenative C−S cross‐coupling has been developed using a modular flow electrolysis cell. The continuous‐flow electrosynthesis not only ensures efficient product formation, but also obviates the need for transition‐metal catalysts, oxidizing reagents, and supporting electrolytes.
This study considers the generalized uncertainty principle, which incorporates the central idea of large extra dimensions, to investigate the processes involved when massive spin-1 particles tunnel ...from Reissner–Nordstrom and Kerr black holes under the effects of quantum gravity. For the black hole, the quantum gravity correction decelerates the increase in temperature. Up to O(1Mf2), the corrected temperatures are affected by the mass and angular momentum of the emitted vector bosons. In addition, the temperature of the Kerr black hole becomes uneven due to rotation. When the mass of the black hole approaches the order of the higher dimensional Planck mass Mf, it stops radiating and yields a black hole remnant.
We report engineered hollow core–shell interlinked carbon spheres that consist of a mesoporous shell, a hollow void, and an anchored carbon core and are expected to be ideal sulfur hosts for ...overcoming the shortage of Li–S batteries. The hollow core–shell interlinked carbon spheres were obtained through solution synthesis of polymer spheres followed by a pyrolysis process that occurred in the hermetical silica shell. During the pyrolysis, the polymer sphere was transformed into the carbon core and the carbonaceous volatiles were self-deposited on the silica shell due to the blocking effect of the hermetical silica shell. The gravitational force and the natural driving force of lowering the surface energy tend to interlink the carbon core and carbon/silica shell, resulting in a core–shell interlinked structure. After the SiO2 shell was etched, the mesoporous carbon shell was generated. When used as the sulfur host for Li–S batteries, such a hierarchical structure provides access to Li+ ingress/egress for reactivity with the sulfur and, meanwhile, can overcome the limitations of low sulfur loading and a severe shuttle effect in solid carbon-supported sulfur cathodes. Transmission electron microscopy and scanning transmission electron microscopy images provide visible evidence that sulfur is well-encapsulated in the hollow void. Importantly, such anchored-core carbon nanostructures can simultaneously serve as a physical buffer and an electronically connecting matrix, which helps to realize the full potential of the active materials. Based on the many merits, carbon–sulfur cathodes show a high utilization of sulfur with a sulfur loading of 70 wt % and exhibit excellent cycling stability (i.e., 960 mA h g–1 after 200 cycles at a current density of 0.5 C).
Solid state lithium metal batteries are the most promising next‐generation power sources owing to their high energy density and safety. Solid polymer electrolytes (SPE) have gained wide attention due ...to the excellent flexibility, manufacturability, lightweight, and low‐cost processing. However, fatal drawbacks of the SPE such as the insufficient ionic conductivity and Li+ transference number at room temperature restrict their practical application. Here vertically aligned 2D sheets are demonstrated as an advanced filler for SPE with enhanced ionic conductivity, Li+ transference number, mechanical modulus, and electrochemical stability, using vermiculite nanosheets as an example. The vertically aligned vermiculite sheets (VAVS), prepared by the temperature gradient freezing, provide aligned, continuous, run‐through polymer‐filler interfaces after infiltrating with polyethylene oxide (PEO)‐based SPE. As a result, ionic conductivity as high as 1.89 × 10−4 S cm−1 at 25 °C is achieved with Li+ transference number close to 0.5. Along with their enhanced mechanical strength, Li|Li symmetric cells using VAVS–CSPE are stable over 1300 h with a low overpotential. LiFePO4 in all‐solid‐state lithium metal batteries with VAVS–CSPE could deliver a specific capacity of 167 mAh g−1 at 0.1 C at 35 °C and 82% capacity retention after 200 cycles at 0.5 C.
A vertically aligned 2D materials filler for solid polymer electrolytes is demonstrated. The aligned, continuous, run‐through polymer‐filler interfaces enhance the ionic conductivity, Li+ transference number, mechanical modulus, and electrochemical stability of solid polymer electrolytes. LiFePO4 in lithium metal batteries with the electrolyte could deliver a specific capacity of 167 mAh g−1 at 0.1 C at 35 °C.
Climate change has the potential to change the distribution of pests globally and their resistance to pesticides, thereby threatening global food security in the 21st century. However, predicting ...where these changes occur and how they will influence current pest control efforts is a challenge. Using experimentally parameterised and field-tested models, we show that climate change over the past 50 years increased the overwintering range of a global agricultural insect pest, the diamondback moth (Plutella xylostella), by ~2.4 million km
worldwide. Our analysis of global data sets revealed that pesticide resistance levels are linked to the species' overwintering range: mean pesticide resistance was 158 times higher in overwintering sites compared to sites with only seasonal occurrence. By facilitating local persistence all year round, climate change can promote and expand pesticide resistance of this destructive species globally. These ecological and evolutionary changes would severely impede effectiveness of current pest control efforts and potentially cause large economic losses.
In this paper, the video retrieval technique based on model migration makes full use of the migration learning technique to build a text encoder and video encoder to obtain text and video features. ...The text is preprocessed based on the BERT model, and text features are extracted by combining TF-IDF and mutual information. The logistic regression algorithm is applied to achieve text classification. The text mining techniques above are used to parse YouTube Chinese learning resources to extract their dissemination features. The results show that 5,286 (61.48%) of YouTube Chinese learning resources are from the category of “education,” and 2,294 (26.68%) are from the category of “people and blogs.” The video resources category is the most popular and loved category among learners due to its highest average number of views (1238214.3). The dissemination is significantly impacted by teachers’ performance, vivid language, and interaction during the teaching process. The indirect effect value test between online interaction, technical support, and resource quality, as well as satisfaction and intention to continue using, met the criterion of significance (p<0.05). It indicates that perceived usefulness has a significant indirect effect (P<0.01) on the impact of knowledge dissemination. This study clarifies the dissemination influences that led to the rise of Chinese resources in the global context.
A catalyst‐ and supporting electrolyte‐free method for electrochemical dehydrogenative C−S bond formation in continuous flow has been developed. A broad range of N‐arylthioamides have been converted ...to the corresponding benzothiazoles in good to excellent yields and with high current efficiencies. This transformation is achieved using only electricity and laboratory grade solvent, avoiding degassing or the use of inert atmosphere. This work highlights three advantages of electrochemistry in flow, which is (i) a supporting electrolyte‐free reaction, (ii) an easy scale‐up of the reaction without the need for a larger reactor and, (iii) the important and effective impact of having a good mixing of the reaction mixture, which can be achieved effectively with the use of flow systems. This clearly improves the reported methods for the synthesis of benzothiazoles.
No catalyst and no supporting electrolyte are needed for the formation of benzothiazoles from N‐arylthioamides. Electrons and a flow reactor for electrochemistry are sufficient.
•Bacteria-based self-healing concrete was developed.•Bacteria induced precipitations at cracks were analyzed by SEM and XRD.•The crack self-healing effect under different conditions were studied.•The ...image characterization method was used for crack-healing quantification.
Bacteria-based self-healing concrete is a relatively new technique, therefore it is important to gather more results in simulate real conditions before applied on a bigger scale. In the present study, bacteria-based self-healing concrete was developed by adding the microbial self-healing agent which has the potential to improve self-healing capacity mainly by bacteria induced mineral precipitations. The precipitations formed at the cracks surface of the cement paste specimens were analyzed with Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray Spectrometer (EDS), and then examined by X-ray Diffraction (XRD). Moreover, the influence of crack width, curing ways and cracking age on the crack self-healing of cement paste with microbial self-healing agent was researched by the characterization methods of area repair rate and anti-seepage repair rate. The results showed that the microbial self-healing agent could be used to achieve the goal of concrete crack self-healing. The precipitations formed at the cracks surface were calcite, which appeared lamellar close packing morphology. However, the capacity of concrete crack self-healing depended on many factors. The crack was more and more difficult to be repaired with the increase of average crack width and the repair ability of microbial repair agent was limited for specimens with crack width up to 0.8mm. Water curing was shown to be the best way for bacteria-based self-healing concrete. In addition, the crack healing ratio of specimens dropped significantly along with the extension of cracking age. When the cracking age was more than 60days, the crack healing ratio was very small. The results above suggested that the optimal conditions were needed for the practical application of microbial self-healing agent.
Water splitting is considered as a pollution‐free and efficient solution to produce hydrogen energy. Low‐cost and efficient electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen ...evolution reaction (OER) are needed. Recently, chemical vapor deposition is used as an effective approach to gain high‐quality MoS2 nanosheets (NSs), which possess excellent performance for water splitting comparable to platinum. Herein, MoS2 NSs grown vertically on FeNi substrates are obtained with in situ growth of Fe5Ni4S8 (FNS) at the interface during the synthesis of MoS2. The synthesized MoS2/FNS/FeNi foam exhibits only 120 mV at 10 mA cm−2 for HER and exceptionally low overpotential of 204 mV to attain the same current density for OER. Density functional theory calculations further reveal that the constructed coupling interface between MoS2 and FNS facilitates the absorption of H atoms and OH groups, consequently enhancing the performances of HER and OER. Such impressive performances herald that the unique structure provides an approach for designing advanced electrocatalysts.
Strong coupling interfaces of a vertical MoS2 array and in situ grown Fe5Ni4S8 are formed by chemical vapor deposition. The interfacial coupling of the MoS2 array on FeNi foam shows outstanding activity of both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER): 120 mV @ 10 mA cm–2 for HER and 204 mV @ 10 mA cm–2 for OER.
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