Summary
Environmental factors, such as temperature, traffic, and wind, play an important role on the variations of dynamic properties of long‐span cable‐stayed bridges. The dynamic characteristics of ...Sutong Cable‐Stayed Bridge (SCB), including acceleration and strain responses as well as modal frequencies, are investigated using one‐year continuous monitoring data under operating conditions by the structural health monitoring system. The in situ wind characteristics and structural temperature behavior of SCB are also analyzed. More than 99% of the wind speed values are smaller than 16 m/s; and the largest temperature variation of the main girder exceeds 60 °C. Besides, acceleration and strain, root mean square (RMS) data are both normalized using the Z‐score standardization method. Relation analysis between the normalized acceleration and strain RMS values is conducted based on the time‐history comparison and linear least square fitting. Results show that both of the processed acceleration and strain RMS values could properly describe the variation trend of the traffic load, although variation amplitudes of the two normalized parameters differ from each other. In addition, one‐year continuous modal frequencies of SCB are identified using Hilbert–Huang transform method. Variability analysis of the structural modal frequencies due to environmental temperature and operational traffics is then conducted. Results show that temperature is the most important environmental factor for vertical and torsional modal frequencies. The traffic load is the second critical factor especially for the fundamental vertical frequency of SCB. Research results could provide references for damage detection and safety evaluation for similar long‐span cable‐stayed bridges.
Porous organic polymers (POPs) composed of organic building units linked
via
covalent bonds are a class of lightweight porous network materials with high surface areas, tuneable pores, and designable ...components and structures. Owing to their well-preserved characteristics in terms of structure and composition, POPs applied as electrocatalysts have shown promising activity and achieved considerable advances in numerous electrocatalytic reactions, including the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, CO
2
reduction reaction, N
2
reduction reaction, nitrate/nitrite reduction reaction, nitrobenzene reduction reaction, hydrogen oxidation reaction, and benzyl alcohol oxidation reaction. Herein, we present a systematic overview of recent advances in the applications of POPs in these electrocatalytic reactions. The synthesis strategies, specific active sites, and catalytic mechanisms of POPs are summarized in this review. The fundamental principles of some electrocatalytic reactions are also concluded. We further discuss the current challenges of and perspectives on POPs for electrocatalytic applications. Meanwhile, the possible future directions are highlighted to afford guidelines for the development of efficient POP electrocatalysts.
The application of porous organic polymers in various electrocatalytic reactions has been systematically summarized.
Graphene, a two-dimensional carbon sheet with a honeycomb arrangement, has demonstrated promise in energy storage applications owing to its fascinating features, such as a large specific surface ...area, high conductivity, and excellent mechanical flexibility. However, the slow ion transport kinetics and the reduced active surface area due to the restacking of graphene nanosheets during electrode preparation are still major obstacles in the fabrication of energy storage devices with high power/energy density. To deal with the above-mentioned problems, porosity engineering in graphene sheets (creating holes in graphene sheets) has become a highly efficient and promising approach to enabling porous graphene materials to possess the dual advantages of both graphene and porous materials. This review mainly focuses on the in-plane pore-generating approaches to the preparation of porous graphene materials and the recent research progress in the use of porous graphene materials for largely improving the performance of energy storage devices. Furthermore, their challenges for practical application are also discussed.
This review focuses on the in-plane pore-generating approaches of porous graphene materials and the recent research progress in the energy storage field.
Exfoliated covalent organic framework nanosheets Tao, You; Ji, Wenyan; Ding, Xuesong ...
Journal of materials chemistry. A, Materials for energy and sustainability,
03/2021, Letnik:
9, Številka:
12
Journal Article
Recenzirano
Covalent organic frameworks (COFs) are an emerging type of crystalline porous organic polymers with well-defined network structures and designable pore sizes, which have been applied in many fields ...such as gas storage and separation, energy storage, catalysis, and sensing in recent years. However, most synthesized COFs are obtained in the form of insoluble bulk powder, which greatly hinders their processing/assembly into functional devices. Accordingly, preparing COF nanosheets is a strategy that is expected to solve the processability issues of bulk COFs owing to the favorable dispersion of nanosheets in various solvents. Exfoliating COFs into single/few-layered nanosheets is a simple and effective way to prepare exfoliated nanosheets (eNSs). In recent years, the increasing number of strategies for the preparation of eNSs and their subsequent applications have greatly propelled the development of COFs. This review mainly summarizes the various achievements in the preparation of eNSs from bulk COFs, and the related developments in the applications using these eNSs. In addition, some challenges and opportunities for the future development of eNSs are also presented.
This review outlines strategies for the preparation of exfoliated nanosheets and the application examples of these synthesized exfoliated nanosheets in various frontier fields.
This work deals with the zero-Neumann boundary problem to a fully parabolic chemotaxis system with a nonlinear signal production function
f
(
s
) fulfilling 0 ≤
f
(
s
) ≤
Ks
α
for all
s
≥ 0, where
K
...and
α
are positive parameters. It is shown that whenever 0 <
α
<
2
n
(where
n
denotes the spatial dimension) and under suitable assumptions on the initial data, this problem admits a unique global classical solution that is uniformly-in-time bounded in any spatial dimension. The proof is based on some a priori estimate techniques.
Two new flexible visible‐light photodetectors based on ZrS3 nanobelts films are fabricated on a polypropylene (PP) film and printing paper, respectively, by an adhesive‐tape transfer method, and ...their light‐induced electric properties are investigated in detail. The devices demonstrate a remarkable response to 405 to 780 nm light, a photocurrent that depends on the optical power and light wavelength, and an excellent photoswitching effect and stability. This implies that ZrS3 nanobelts are prospective candidates for high‐performance nanoscale optoelectronic devices that may be practically applied in photodetection of visible to near infrared light. The facile fabrication method is extendable to flexible nanodevices with different nanostructures.
A novel fabrication method produces flexible photodetectors with high responsivity! The detectors based on ZrS3 nanobelts show a fast and high‐performance photoresponse from the visible to the near‐infrared light. Compared to a single‐nanowire photodetector, the nanobelt‐film based photodetector possesses much better stability and durability. These novel photodetectors will be applicable to a wide range of practical photodetection units.
We present a novel poro-damage-viscoelastic model for predicting the failure response of fluid-saturated porous geomaterials. The Generalized Maxwell model is introduced for the representation of the ...viscoelastic behavior of the solid skeleton, which is achieved by a standard Prony-series type expansion. Damage regularization is obtained by an non-local integral-type formulation and damage behavior is described by Mazars model with the modified von Mises-type equivalent strain measure. The poromechanics parameters (Biot’s coefficient, Biot’s modulus) are functions of damage, and the fluid flow obeys Darcy’s seepage law in the entire domain, while the permeability is assumed to be anisotropic and strain dependent. The coupled system is discretized in time using a backward Euler scheme. The non-linear system is linearized using a Newton Raphson scheme and solved monolithically every time step. A consistent Jacobian matrix and residual vector are derived analytically. Several numerical examples are studied in order to investigate the performance of the proposed approach, including (i) a column undergoing hysteresis from cyclic loading, stress relaxation, creep and variable strain rate loading tests and (ii) fluid-driven fracturing in a 2D poro-viscoelastic domain. The numerical time-dependent results exhibit mesh insensitivity for all field variables, and confirm the feasibility and applicability of the proposed non-local damage model for simulating hydraulic fracture.
•A non-local damage model for poro-viscoelastic saturated porous media is proposed.•Von-Mises strain measure is used to drive the non-local integral type damage growth.•Damage-response includes nonlinear Biot’s coefficients and anisotropic permeability.•A mixed FEM solution is developed, including a monolithic iterative solution.•Analytically derived Jacobian is used to drive the non-linear solution of equations.•Benchmark problems include poro-viscoelastic column and hydraulic fracture problems.•Objective mesh-independent and oscillation free numerical results are presented.•The model has the potential to represent time-dependent damage in several rock types.
The von Neumann architecture with separate memory and processing presents a serious challenge in terms of device integration, power consumption, and real-time information processing. Inspired by the ...human brain that has highly parallel computing and adaptive learning capabilities, memtransistors are proposed to be developed in order to meet the requirement of artificial intelligence, which can continuously sense the objects, store and process the complex signal, and demonstrate an "all-in-one" low power array. The channel materials of memtransistors include a range of materials, such as two-dimensional (2D) materials, graphene, black phosphorus (BP), carbon nanotubes (CNT), and indium gallium zinc oxide (IGZO). Ferroelectric materials such as P(VDF-TrFE), chalcogenide (PZT), Hf
Zr
O
(HZO), In
Se
, and the electrolyte ion are used as the gate dielectric to mediate artificial synapses. In this review, emergent technology using memtransistors with different materials, diverse device fabrications to improve the integrated storage, and the calculation performance are demonstrated. The different neuromorphic behaviors and the corresponding mechanisms in various materials including organic materials and semiconductor materials are analyzed. Finally, the current challenges and future perspectives for the development of memtransistors in neuromorphic system applications are presented.
Tuning Ag surface states by metal oxides is a feasible method to enhance the oxygen reduction reaction (ORR) performance of Ag-based catalysts. Herein, we develop a heterostructural electrocatalyst ...of flowerlike Ag-supported nanosheets of metal oxides (Mn3O4 and Ce-doped Mn3O4) by a facile two-step solution method for a highly efficient alkaline ORR. Not only does Mn3O4/Ag exhibit activity comparable to that of commercial Pt/C but also small amounts of Ce3+ (2–5 mol %) doped into Mn3O4 make the ORR activity and stability outperform those of Pt/C. The roles of the adjustment of Ag surface states induced by the supported Mn3O4 and Ce doping in the enhanced ORR performance were studied. The strong electron transfer from Ag substrates to Mn3O4 makes the d center of Ag shift up, accelerating the kinetics of O–O bond splitting on Ag surfaces (increasing the activity of active sites for O–O bond dissociation). Additionally, 5% Ce3+ doping further tunes Ag surface electronic structures to improve the ORR performance of Mn3O4/Ag. Meanwhile, supported Mn3O4 can reduce the adsorption of oxygen-containing species on Ag surfaces by a spillover effect, and the moderately increased oxygen vacancies of Mn3O4 due to 5% Ce doping further increase the active sites on oxide/Ag surfaces and electrochemically active surface areas for the ORR.
Cyclophosphamide causes side effects in cancer patients, including hepatotoxicity. Probiotics have recently emerged as potential approaches for the administration of many diseases. This study aimed ...to evaluate the protective effects of Lactiplantibacillus plantarum P101 against cyclophosphamide-induced liver injury and elucidate the underlying mechanism. In this study, Lactiplantibacillus plantarum P101 or Lactobacillus rhamnosus GG were pre-administered to mice with varying duration (1 week, 2 weeks, and 3 weeks) before being intraperitoneally injected with cyclophosphamide at a dose of 30 mg/kg/day for 7 days to induce liver injury. Results demonstrated that cyclophosphamide-induced liver injury was characterized by histopathological disorders, including irregular central venous shape and hepatic vascular rupture, as well as a severe inflammation response and oxidative stress. The administration of probiotics for 3 weeks exerted the most significant improvements in alleviating liver injury, oxidative stress, and inflammation when compared to the shorter intervention duration. Notably, Lactiplantibacillus plantarum P101 exhibited more pronounced effects than Lactobacillus rhamnosus GG. Furthermore, Lactiplantibacillus plantarum P101 enhanced the antioxidant defense system by activating the Nrf2/ARE signaling pathway, ultimately alleviating hepatotoxicity and hepatocyte apoptosis. In conclusion, this study highlighted the potential of Lactiplantibacillus plantarum P101 to alleviate cyclophosphamide-induced hepatotoxicity.
