At a microscopic scale, the failure of brittle materials results from crack initiation, propagation and coalescence. Acoustic emission (AE) technique, especially parameter analysis, has been widely ...applied to investigate cracking process and mechanism in civil engineering. However, crack classification in AE parameter analysis mostly derives from the empirical relation between the RA value and the average frequency, and the crack classification criterion, i.e., the optimal transition line between shear and tensile cracks in the parameter analysis has not been determined yet. Based on statistical analysis of dominant frequency characteristics of AE signals, a new method is proposed for determining the optimal transition line for crack classification in AE parameter analysis. Spectrum analyses of AE waveform data in the representative specimens are carried out to acquire the dominant frequency of AE waveforms. Proportions of waveforms distributed in low and high dominant frequency bands (L-type and H-type waveforms) are determined. The ratios of tensile and shear cracks, viewed as measurements, are determined by the statistical analysis of dominant frequency characteristics of AE waveforms. For a series of different transition line, the predicted ratios of tensile and shear cracks in AE parameter analysis are determined. The optimal transition line is determined to be the one corresponding to the least square difference between predicted data and measurements. The determined optimal transition line can be directly applied for crack classification in AE parameter analysis in the subsequent experiments of this brittle material. The reliability of the proposed method were validated by laboratory tests of rock subjected to compression. It can be found that the optimal transition line in the parameter analysis is approximately from 1:100 to 1:500 for brittle rock under compression. The findings in this study contributes to the enhancement of the accuracy and efficiency of AE source mechanism and damage process analysis.
Proteins are responsible for the occurrence and treatment of many diseases, and therefore protein sequencing will revolutionize proteomics and clinical diagnostics. Biological nanopore approach has ...proved successful for single‐molecule DNA sequencing, which resolves the identities of 4 natural deoxyribonucleotides based on the current blockages and duration times of their translocations across the nanopore confinement. However, open challenges still remain for biological nanopores to sequentially identify each amino acid (AA) of single proteins due to the inherent complexity of 20 proteinogenic AAs in charges, volumes, hydrophobicity and structures. Herein, we focus on recent exciting advances in biological nanopores for single‐molecule protein sequencing (SMPS) from native protein unfolding, control of peptide translocation, AA identification to applications in disease detection.
Nanopore electrochemistry offers a bright prospect for single‐molecule protein sequencing by measuring specific interactions between amino acids based on their natural structure and chemistry continuity and diversity. This Minireview focusses on recent advances in biological nanopores from protein unfolding, peptide translocation, amino acid identification to diagnostic application.
In the present work, the open source Computational Fluid Dynamics (CFD) package-Open Field Operation and Manipulation (OpenFoam®) is used to simulate wave-structure interactions and a new wave ...boundary condition is developed for extreme waves. The new wave boundary condition is implemented for simulation of interaction with a fixed/floating truncated cylinder and a simplified Floating Production Storage and Offloading platform (FPSO) and results are compared with physical experiment data obtained in the COAST laboratory at Plymouth University. Different approaches to mesh generation (i.e. block and split-hexahedra) are investigated and found to be suitable for cases considered here; grid and time convergence is also demonstrated. The validation work includes comparison with theoretical and experimental data. The cases performed demonstrate that OpenFoam® is capable of predicting these cases of wave-structure interaction with good accuracy (e.g. the value of maximum pressure on the FPSO is predicted within 2.4% of the experiment) and efficiency. The code is run in parallel using high performance computing and the simulations presented have shown that OpenFoam® is a suitable tool for coastal and offshore engineering applications, is able to simulate two-phase flow in 3D domains and to predict wave-structure interaction well.
•A numerical simulation of extreme waves and wave-structure interaction is studied using OpenFOAM.•A new wave boundary condition based on a focused wave group with second order Stokes wave theory is integrated in waves2Foam within OpenFOAM.•Results agree well with physical experiments, including the surface elevation and the pressure at the front of the structure.•The OpenFOAM model is well placed for extension to many coastal engineering applications to simulate a wide range of nonlinear wave conditions.
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•Magnetic CuO/Fe2O3/CuFe2O4 was simply synthesized and characterized in detail.•Levofloxacin was effectively degraded in CuFeO-2/PS system.•1O2 led to the degradation of levofloxacin ...via a non-radical oxidation process.•Activation mechanism of PS and degradation route of levofloxacin were proposed.•Levofloxacin removal in real water matrix was evaluated.
A cost-effective one-pot hydrothermal route was used to prepare novel magnetic CuO/Fe2O3/CuFe2O4 nanocomposites activating persulfate (PS) to remove levofloxacin from water. The optimized CuO/Fe2O3/CuFe2O4 sample (denoted as CuFeO-2) possessed a higher catalytic performance for levofloxacin degradation by activating PS than those of CuO, Fe2O3, CuFe2O4 and recently reported heterogeneous catalysts. After 120 min, the degradation efficiency and the mineralization degree of levofloxacin (10 mg∙L−1) in CuFeO-2/PS system reached 75.5% and 64.5%, respectively. The influence of some significant reaction parameters (e.g., PS dosage, catalyst dosage, initial pH, temperature and coexisting inorganic anions) on levofloxacin removal in CuFeO-2/PS system was studied and analyzed. Although the catalytic activity of magnetic CuFeO-2 slightly declined after each cycle due to the loss of active Cu(II), the recyclability of CuFeO-2 was significantly better than that of CuO. The trapping experiments and ESR studies confirmed that singlet oxygen (1O2), sulfate radical (SO4•−) and hydroxyl radical (•OH) were generated in CuFeO-2/PS system, thus, the degradation of levofloxacin can be achieved via the non-radical and radical oxidation processes. The role of copper, iron and oxygen elements in CuFeO-2 on PS activation was investigated by ART-FTIR and XPS. The possible degradation routes of levofloxacin were put forward according to the detected intermediate products. Moreover, the performance of CuFeO-2/PS system for levofloxacin degradation in real water matrix was also investigated.
Energy storage and conversion play a crucial role in modern energy systems, and the exploration of advanced electrode materials is vital but challenging. Carbon‐based nanocages consisting of sp2 ...carbon shells feature a hollow interior cavity with sub‐nanometer microchannels across the shells, high specific surface area with a defective outer surface, and tunable electronic structure, much different from the intensively studied nanocarbons such as carbon nanotubes and graphene. These structural and morphological characteristics make carbon‐based nanocages a new platform for advanced energy storage and conversion. Up‐to‐date synthetic strategies of carbon‐based nanocages, the utilization of their unique porous structure and morphology for the construction of composites with foreign active species, and their significant applications to the advanced energy storage and conversion are reviewed. Structure–performance correlations are discussed in depth to highlight the contribution of carbon‐based nanocages. The research challenges and trends are also envisaged for deepening and extending the study and application of this multifunctional material.
Carbon‐based nanocages have emerged as a new platform for advanced energy storage and conversion owing to their hollow interior cavity with microchannels across the shells, their high specific surface area with defective outer surface, and their tunable electronic structure. Up‐to‐date progress on the synthesis, encapsulating/supporting of carbon‐based nanocages and their applications is presented, along with the research challenges and trends.
Cervical cancer is the third most common cancer in women worldwide, with concepts and knowledge about its prevention and treatment evolving rapidly. Human papillomavirus (HPV) has been identified as ...a major factor that leads to cervical cancer, although HPV infection alone cannot cause the disease. In fact, HPV‐driven cancer is a small probability event because most infections are transient and could be cleared spontaneously by host immune system. With persistent HPV infection, decades are required for progression to cervical cancer. Therefore, this long time window provides golden opportunity for clinical intervention, and the fundament here is to elucidate the carcinogenic pattern and applicable targets during HPV‐host interaction. In this review, we discuss the key factors that contribute to the persistence of HPV and cervical carcinogenesis, emerging new concepts and technologies for cancer interventions, and more urgently, how these concepts and technologies might lead to clinical precision medicine which could provide prediction, prevention, and early treatment for patients.
We discussed the key factors that contribute to HPV persistency and cervical carcinogenesis, the perspective and novel potential technologies for early diagnose and effective prevention of the disease, and more importantly, how this knowledge of basic science may translate into clinic to provide better personalized health care for patients with cervical cancer. This review contributed to the deeper understanding of effective prevention, screening, and treatment of HPV‐related cervical cancer.
Replacing precious platinum with earth‐abundant materials for the oxygen reduction reaction (ORR) in fuel cells has been the objective worldwide for several decades. In the last 10 years, the ...fastest‐growing branch in this area has been carbon‐based metal‐free ORR electrocatalysts. Great progress has been made in promoting the performance and understanding the underlying fundamentals. Here, a comprehensive review of this field is presented by emphasizing the emerging issues including the predictive design and controllable construction of porous structures and doping configurations, mechanistic understanding from the model catalysts, integrated experimental and theoretical studies, and performance evaluation in full cells. Centering on these topics, the most up‐to‐date results are presented, along with remarks and perspectives for the future development of carbon‐based metal‐free ORR electrocatalysts.
Replacing precious platinum with earth‐abundant materials in fuel cells for the oxygen reduction reaction (ORR) has been a worldwide objective for several decades. In the last 10 years, the fastest‐growing branch in this area has been carbon‐based metal‐free ORR electrocatalysts. The most up‐to‐date results of this field are presented, along with remarks and perspectives for the future development of carbon‐based metal‐free ORR electrocatalysts.
Carbon-based nanomaterials have been the focus of research interests in the past 30 years due to their abundant microstructures and morphologies, excellent properties, and wide potential ...applications, as landmarked by 0D fullerene, 1D nanotubes, and 2D graphene. With the availability of high specific surface area (SSA), well-balanced pore distribution, high conductivity, and tunable wettability, carbon-based nanomaterials are highly expected as advanced materials for energy conversion and storage to meet the increasing demands for clean and renewable energies. In this context, attention is usually attracted by the star material of graphene in recent years. In this Account, we overview our studies on carbon-based nanotubes to nanocages for energy conversion and storage, including their synthesis, performances, and related mechanisms. The two carbon nanostructures have the common features of interior cavity, high conductivity, and easy doping but much different SSAs and pore distributions, leading to different performances. We demonstrated a six-membered-ring-based growth mechanism of carbon nanotubes (CNTs) with benzene precursor based on the structural similarity of the benzene ring to the building unit of CNTs. By this mechanism, nitrogen-doped CNTs (NCNTs) with homogeneous N distribution and predominant pyridinic N were obtained with pyridine precursor, providing a new kind of support for convenient surface functionalization via N-participation. Accordingly, various transition-metal nanoparticles were directly immobilized onto NCNTs without premodification. The so-constructed catalysts featured high dispersion, narrow size distribution and tunable composition, which presented superior catalytic performances for energy conversions, for example, the oxygen reduction reaction (ORR) and methanol oxidation in fuel cells. With the advent of the new field of carbon-based metal-free electrocatalysts, we first extended ORR catalysts from the electron-rich N-doped to the electron-deficient B-doped sp2 carbon. The combined experimental and theoretical study indicated the ORR activity originated from the activation of carbon π electrons by breaking the integrity of π conjugation, despite the electron-rich or electron-deficient nature of the dopants. With this understanding, metal-free electrocatalysts were further extended to the dopant-free defective carbon nanomaterials. Moreover, we developed novel 3D hierarchical carbon-based nanocages by the in situ MgO template method, which featured coexisting micro–meso–macropores and much larger SSA than the nanotubes. The unique 3D architecture avoids the restacking generally faced by 2D graphene due to the intrinsic π–π interaction. Consequently, the hierarchical nanocages presented superior performances not only as new catalyst supports and metal-free electrocatalysts but also as electrode materials for energy storage. State-of-the-art supercapacitive performances were achieved with high energy density and power density, as well as excellent rate capability and cycling stability. The large interior space of the nanocages enabled the encapsulation of high-loading sulfur to alleviate polysulfide dissolution while greatly enhancing the electron conduction and Li-ion diffusion, leading to top level performance of lithium–sulfur battery. These results not only provide unique carbon-based nanomaterials but also lead to in-depth understanding of growth mechanisms, material design, and structure–performance relationships, which is significant to promote their energy applications and also to enrich the exciting field of carbon-based nanomaterials.
Inspired by the biological processes of molecular recognition and transportation across membranes, nanopore techniques have evolved in recent decades as ultrasensitive analytical tools for individual ...molecules. In particular, nanopore-based single-molecule DNA/RNA sequencing has advanced genomic and transcriptomic research due to the portability, lower costs and long reads of these methods. Nanopore applications, however, extend far beyond nucleic acid sequencing. In this Review, we present an overview of the broad applications of nanopores in molecular sensing and sequencing, chemical catalysis and biophysical characterization. We highlight the prospects of applying nanopores for single-protein analysis and sequencing, single-molecule covalent chemistry, clinical sensing applications for single-molecule liquid biopsy, and the use of synthetic biomimetic nanopores as experimental models for natural systems. We suggest that nanopore technologies will continue to be explored to address a number of scientific challenges as control over pore design improves.
Behaviour of granular soils subjected to internal erosion involves complex coupling between solid–fluid interaction, skeleton deformation and microstructural evolutions. This paper presents a ...micro–macro investigation on suffusion in idealized gap-graded and well-graded soils using the coupled computational fluid dynamics and discrete element method. The interaction between soil particles and seepage flow is modelled via momentum exchange between two phases. The progressive loss of fine particles subjected to upward seepage flow at various hydraulic gradients is investigated. The fines content, volumetric contraction and void ratio are monitored to identify the changes of macroscopic states of the soil skeleton. In addition, the microstructural evolution is tracked via particle-scale descriptors such as coordination numbers and force chain statistics. Several clogging–unclogging events which are responsible for the sudden changes of fines content and skeleton response are observed during suffusion. A parametric study indicates that the initial fines content and the hydraulic gradient significantly affect the kinetics of suffusion. Microstructural analyses reveal that the removal of fines is accompanied by the reduction in weak contact pairs and particles with low connectivity.
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