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The trivalent seasonal influenza vaccine was the only approved and available vaccine during the 2016–2018 influenza seasons. It did not include the B/Yamagata strain. In this study, we report an acute respiratory disease outbreak associated with influenza B/Yamagata infections in Guangzhou, Southern China (January through March, 2018). Among the 9914 patients, 2241 (22.6%) were positive for the influenza B virus, with only 312 (3.1%) positive for the influenza A virus. The influenza B/Yamagata lineage dominated during this period in Southern China. The highest incidence of influenza A virus infection occurred in the children aged 5–14 years. In contrast, populations across all age groups were susceptible to the influenza B virus. Phylogenetic, mutations, and 3D structure analyses of hemagglutinin (HA) genes were performed to assess the vaccine-virus relatedness. The recommended A/H1N1 vaccine strain (A/Michigan/45/2015) during both 2017–2018 and 2018–2019 was antigen-specific for these circulating isolates (clade 6B.1) in Spring 2018. An outbreak of influenza B/Yamagata (clade 3) infections in 2018 occurred during the absence of the corresponding vaccine during 2016–2018. The recommended influenza B/Yamagata vaccine strain (B/Phuket/3073/2013) for the following season (2018–2019) was antigen-specific. Although there were only a few influenza B/Victoria infections in Spring 2018, five amino acid mutations were identified in the HA antigenic sites of the 19 B/Victoria isolates (clade 1A), when compared with the 2016–2018 B/Victoria vaccine strain. The number was larger than expected and suggested that the influenza B HA gene may be more variable than previously thought. One of the mutations (K180N) was noted to likely alter the epitope and to potentially affect the viral antigenicity. Seven mutations were also identified in the HA antigenic sites of 2018–2020 B/Victoria vaccine strain, of which some or all may reduce immunogenicity and the protective efficacy of the vaccine, perhaps leading to more outbreaks in subsequent seasons. The combined epidemiological, phylogenetic, mutations, and 3D structural analyses of the HA genes of influenza strains reported here contribute to the understanding and evaluation of how HA mutations affect vaccine efficacy, as well as to providing important data for screening and selecting more specific, appropriate, and effective influenza vaccine candidate strains.

Objective MicroRNAs (MiRNAs) is considered to play an important role in the occurrence and development of ovarian cancer(OC). Although miRNAs has been widely recognized in ovarian cancer, the role of hsa-miR-30a-5p (miR-30a) in OC has not been fully elucidated. Methods Through the analysis of public data sets in Gene Expression Omnibus (GEO) database and literature review, the significance of miR-30a expression in OC is evaluated. Three mRNA datasets of OC and normal ovarian tissue, GSE14407, GSE18520 and GSE36668, were downloaded from GEO to find the differentially expressed gene (DEG). Then the target genes of hsa-miR-30a-5p were predicted by miRWALK3.0 and TargetScan. Then, the gene overlap between DEG and the predicted target genes of miR-30a in OC was analyzed by Gene Ontology (GO) enrichment analysis. Protein-protein interaction (PPI) network was constructed by STRING and Cytoscape, and the effect of HUB gene on the prognosis of OC was analyzed. Results A common pattern of up-regulation of miR-30a in OC was found. A total of 225 DEG, were identified, both OC-related and miR-30a-related. Many DEG are enriched in the interactions of intracellular matrix tissue, ion binding and biological process regulation. Among the 10 major Hub genes analyzed by PPI, five Hub genes were significantly related to the overall poor survival of OC patients, in which the low expression of ESR1 ,MAPK10, Tp53 and the high expression of YKT ,NSF were related to poor prognosis of OC.

The benefit of adjuvant hysterectomy after definitive concurrent chemoradiotherapy (CCRT) for locally-advanced cervical cancer (LACC) is controversial. The purpose of the present study was to systematically search the literature and perform a meta-analysis to compare overall survival (OS) and disease-free survival (DFS) between patients subjected to CCRT with hysterectomy and those who underwent CCRT alone. The PubMed, Scopus, Embase and Google scholar databases were searched. A meta-analysis to determine hazard ratios (HRs) and odds ratios (ORs) with meta-regression was performed for the following moderators: Disease stage, histology and proportion of radical hysterectomy. Data from 14 studies were included. The results indicated that patients who received CCRT with hysterectomy had significantly better OS (HR, 0.72; 95% CI, 0.56 to 0.91; I2=19%; P=0.007) and DFS (HR, 0.72; 95% CI, 0.56 to 0.93; I2=27%; P=0.01) than those treated with CCRT alone. However, in a subgroup analysis by study type, the results were significant only for retrospective studies but not for randomized controlled trials (RCTs). However, only 2 RCTs were included with small sample size, heterogeneity and low overall quality. Subgroup analyses based on the use of brachytherapy in the CCRT with hysterectomy group demonstrated no difference in OS and DFS between the two groups. Regarding the absolute numbers of death and recurrence events, no significant difference in mortality (OR, 0.91; 95% CI, 0.62 to 1.33; I2=0%; P=0.64) was determined between the two groups, but a significantly reduced incidence of recurrence was observed in the CCRT with hysterectomy group (OR, 0.61; 95% CI, 0.47-0.79; I2=29%; P=0.0002). The meta-regression results point to a significant influence of the proportion of stage II patients on OS. Despite the overall analysis indicating improved OS and DFS with the use of adjuvant hysterectomy after CCRT, subgroup analysis based on similar treatment protocols failed to demonstrate any significant benefit of hysterectomy in LACC. However, the results indicated that the recurrence rate may be higher in patients undergoing CCRT without hysterectomy. The limited quality of the studies included and selection bias from retrospective studies restrict the possibility to draw strong conclusions.

Background Acute coronary syndrome (ACS) is the leading cause of death in developing and developed countries, yet assessing the risk of its development remains challenging. Several lines of evidence indicate that small, dense low‐density lipoproteins (sd‐LDL) are associated with increased cardiovascular disease risk. We aim to evaluate sd‐LDL concentration for predicting the risk of ACS in Chinese population. Methods Baseline characteristics of 121 patients with ACS and 172 healthy controls were obtained. Plasma sd‐LDL‐C was measured using homogeneous assay, and the proportion of sd‐LDL‐C in LDL‐C was detected. Results There was gender and age effect on the sd‐LDL‐C concentration and sd‐LDL‐C/LDL‐C ratio among healthy subjects. Elevated sd‐LDL‐C concentrations and sd‐LDL‐C/LDL‐C ratio were observed in ACS patients with unstable angina pectoris (UAP), non–ST‐segment elevation myocardial infarction (STEMI), and ST‐segment elevation myocardial infarction (NSTEMI) compared with healthy controls (P

Supplemental material, Supplemental_material for A framework combining pseudo-excitation method and two-and-a-half-dimensional finite element method for random ground vibrations induced by high-speed trains by Lidong Wang, Zhihui Zhu, Pedro Alves Costa, Yu Bai, Zhiwu Yu and Yan Han in Advances in Structural Engineering

Background. Human adenoviruses (HAdVs) are commonly causing respiratory disease. We molecularly genotyped HAdV circulating in Chinese hospitalized children with respiratory infections and summarized the clinical profiles and common inflammatory biomarkers, so as to better determine their associations with disease severity. Method. Children with respiratory single HAdV infection cases that occurred from December 2017 to March 2019 were enrolled for a cross-sectional study. Clinical/laboratory features based on the genotypes of respiratory HAdV infection were reviewed for comparative analysis. Results. A total of 84 patients were enrolled, and HAdV types were identified from 82 patients. Species B (HAdV-7, 44%; HAdV-3, 43%, and HAdV-14, 5%) was the most common, followed by C (HAdV-2, 4% and HAdV-1, 1%) and E (HAdV-4, 1%). Severe HAdV infection and HAdV-7 infection groups were associated with significantly longer duration of fever and hospitalized days, higher morbidity of tachypnea/dyspnea, more pleural effusion, more respiratory rales, more frequently required mechanical ventilation, and significantly higher fatality rate. The elevated procalcitonin (PCT) and C-reactive protein (CRP) levels were significantly associated with severe HAdV infection. Conclusions. HAdV-7 and HAdV-3 were the most common types among children with respiratory adenovirus infection; vaccines against these two genotypes are in urgent need. PCT and CRP are significantly associated with the severity of HAdV infection.

Substantial researches indicated that long non-coding RNAs (lncRNAs) exerted profound effects on chemo-resistance in cancer treatment. Nonetheless, the role of NORAD in non-small-cell lung cancer (NSCLC) remains unclear. In the present study, we chose NSCLC cell lines H446 and A549 to explore the function of non-coding RNA activated damage (NORAD) in response to cisplatin (DDP) resistance of NSCLC. Experimental data manifested that NORAD was up-regulated in DDP-resistant NSCLC tissues and cells. NSCLC patients with high NORAD expression suffered a poor prognosis. NORAD knockdown resensitized H446/DDP and A549/DDP to DDP. Besides, NORAD acted as a molecular sponge of miR-129-1-3p. MiR-129-1-3p showed a low level of expression in DDP-resistant NSCLC tissues. Moreover, miR-129-1-3p overexpression impaired DDP resistance in H446/DDP and A549/DDP cells. SOX4 was the downstream target of miR-129-1-3p. Especially, SOX4 overexpression offset the effects of NORAD silence on H446/DDP and A549/DDP cells resistance to DDP. NORAD knockdown resensitized H446/DDP and A549/DDP to DDP in NSCLC via targeting miR-129-1-3p/SOX4 axis, offering a brand-new target for NSCLC chemo-resistance.

The effects of erosion mode, erosion age, and concentration of sulfate solution on mechanical properties of concrete were investigated. The dimensionless relationship model of the stress-strain of concrete on the basis of randomness was proposed. The variation of the elasticity modulus and Poisson’s ratio of the concrete surface attacked by sulfate was studied, and a novel method of using a superficial parameter to characterize the performance change of the concrete surface was recommended. The results showed that the dimensionless relationship model of stress-strain of concrete could be used to represent the variations of mechanical properties of concrete. The differences of load-displacement of concrete before and after sulfate attack were reflected as the change of curve’s slope and ultimate bearing capacity, and the slope of a straight section of the lateral and longitudinal strain curves of concrete surface also varied. The increment rates of ultimate bearing capacity of concrete attacked by 1% and saturated sulfate solution were about 30% and 10%, respectively. However, the decreasing ratio of the ultimate bearing capacity of concrete attacked by saturated sulfate solution was approximately 25%. The damage factor of the elasticity modulus of the concrete surface of C20 and C40 was 0.185 and −0.19, respectively. The obtained results could provide a support for investigating the variations of stress-strain relationship and mechanical performance of concrete under a sulfate environment.

To investigate the composite performance of the track slab and the self-compacting concrete filling layer in the China Railway Track System III slab track structure, six segmental specimens comprising either one or a pair of sleepers were fabricated by dividing a full-scale slab track structure. Fatigue tests in the transverse bending perpendicular to the rail were conducted on four slab track specimens supported on rubber plates simulating the subgrade, to a maximum of five million applied load cycles. It was observed in the fatigue tests that longitudinal cracks first appeared on the top surface of the track slab at the mid-span of the specimen. Splitting cracks appeared later from the anchorage ends of the transverse prestressed tendons to the top surface of track slab. Delamination of the track slab–filling layer interface developed with increasing number of cycles. Static three-point bending tests were also conducted on both fatigue-damaged and control composite plate specimens to evaluate the effect of fatigue damage on the composite performance of the track slab and the filling layer. In the static tests, significant deformation developed in the fatigue-damaged specimens from the start of loading, and the fatigue damage and interface delamination adversely affected the composite action of the track slab and the filling layer. Static loads corresponding to new cracking of the fatigue-damaged composite plates were reduced by 20–30%, and the load corresponding to the initial interlayer slip reduced by 25–62% compared with the control specimens. The interfacial bond strength between the track slab and the filling layer is the first line of defense against the interlayer slip, and the dowel action of the interlayer connection reinforcement is the second line of defense. Roughening by multitooth chiseling on the track slab and an increase in the ratio of interlayer connection reinforcements are both effective ways to enhance the composite action of the track slab and the filling layer.

A series tests on concrete and mortar cylinders under cyclic uniaxial loading were carried in this study to investigate the effect of internal stress-induced cracks on their mechanical properties. It was found that the radial strain cannot be changed continuously because the internal circular cracks appear firstly inside the specimens. Moreover, a unified approach for calculating the apparent volumetric strain of the cylindrical specimens at both elastic and inelastic stages was proposed. Additionally, the Acoustic emission (AE) experimental result shows that the AE hits rate can well reflect the crack formation and propagations of the concrete specimen under the cyclic axial compression.

This study presents experimental and numerical investigations of simply supported steel reinforced concrete (RC) beams under fire. The temperature field of cross sections, the vertical deflection at mid-span, and specifically the axial expansion displacement at beam-ends were measured during the fire tests. A novel finite element (FE) model of a RC beam under fire was developed, in which the water loss in the heat transfer analysis and the concrete transient strain in the mechanical analysis were considered. Based on the validated FE model proposed in this study, parametric studies were conducted to investigate the effects of the beam type, the protective layer thickness, and the load ratio on the thermal and mechanical behavior of simply supported RC beams. It was found that greater fire resistance and fire performance of girder beams in comparison to secondary beams contributed to the non-structural reinforcements, which effectively compensated for the reduced tensile capacities of structural reinforcements because of the degradation of the material properties. In addition, the history of normal stress distributions of concrete under fire can be divided into three phases: expansion, stress redistribution and plateau phases.

An innovative stochastic dynamic model of a 3D train-track-bridge coupled system (TTBS) with refined wheel/rail interaction is established for a high-speed railway based on the random theory of probability density evolution method (PDEM). The multi-coupling effect of excitations can be simultaneously input into the new model, e.g. random track irregularity, random vehicle loads, stochastic system parameters, et al. Moreover, a new approach, named “Number theoretic method of multi-target probability functions” (NTM-mp), is developed to obtain the discrete point sets of multidimensional random parameters in hypercube space, aims to solve the point design of system uncertainty. The stochastic harmonic function (SHF) is applied to generate representative random track irregularity samples. The results of TTBS got by PDEM are verified with several typical case studies for its efficiency and reliability, which are the deterministic results in the representative publication, the Monte Carlo method (MCM) results, and the field testing results on the high-speed railway. At last, a typical case study of TTBS on a high-speed railway is presented for numerical analysis. Discussions and significant conclusions on the random dynamic responses are presented.

As to analyze the effects of friction pendulum bearings (FPB) on the responses of simply supported bridges on a high-speed railway under longitudinal earthquakes, a spatially integrated track-bridge model with a CRTS II slab ballastless track and FPB was established by using the OpenSEES software. The seismic responses under different ground motions were calculated and compared with those using common spherical steel bearings. The comparison results show that the combination of FPB and the CRTS II slab ballastless track is more reasonable. Namely, using FPB can effectively protect the bridge and track structures. Moreover, the rails, fasteners, CA layer and piers are perfectly protected by multi-layer isolation mechanics, induced by FPB and sliding layer, even under strong earthquakes. Finally, 0.05 is identified to be the best value for the friction coefficient of FPB under longitudinal earthquakes.

This paper mainly presents a pseudo-static test program on 12 terminal stirrup-confined square concrete-filled steel tube (SCFT) columns and 14 rectangular SCFT columns under constant axial pressure. The effects of various factors on the hysteretic behavior of specimens are investigated. These factors include with or without stirrups, height of terminal stirrup region, equivalent stirrup ratio, stirrup form, loading direction, height-length ratio (L/B), length-width ratio (B/D), axial compression ratio (n) and sliding support. The failure mode, strain ratio, hysteretic curve, skeleton curve, ultimate bearing capacity, ductility, stiffness degradation, energy dissipation, as well as the residual deformation of the specimens are analyzed. The results indicate that: (1) When n is relatively larger, the bidirectional stirrups can effectively delay the local buckling of steel tube and greatly increase the ultimate bearing capacity, stiffness, equivalent damping viscosity index, residual deformation rate and ductility index, and further significantly improve the seismic behavior of the rectangular SCFT columns; (2) Axial pressure can improve the confinement effect from the steel tube to the core concrete, also bidirectional stirrups can directly confine the core concrete to decrease strain ratio of the steel tube; (3) With the same value of n, increasing the height of terminal stirrup region or increasing the equivalent stirrup ratio can effectively improve the seismic behavior of the rectangular SCFT columns; (4) The influence of loading direction, L/B and B/D on the ductility of rectangular SCFT columns are not obvious.

This paper presents an experimental and theoretical study of CFRP-confined concrete-filled circular steel tube (CFT) stub columns, which aims at investigating the effects of different numbers of CFRP layers and concrete strengths on the mechanical performance of CFRP-confined CFT stub columns. Based on continuum mechanics, a mechanical model of concentric cylinder consisting of CFRP, circular steel tube and concrete core under concentric loading was established and the corresponding elasto-plastic methods were obtained through a FORTRAN program. The influence of the number of CFRP layers on the ultimatecapacity, ductility and confinement effect of the steel tube on the core concrete wasdiscussed and identified. Finally,based on the limit equilibrium and elasto-plastic methods, a simplified formula for the ultimatecapacity of CFRP-confined CFT stub columns was proposed. Good agreement of the ultimate capacity was found between the elasto-plastic methods and the proposed formula, with the maximum discrepancy less than 12%.

This paper mainly presents a combined experimental, numerical and theoretical study on the mechanical behaviors of both conventional concrete-filled rectangular steel tubular stub columns (RST) and stirrup-confined concrete-filled rectangular steel tubular stub columns (SST) under compressive load. 16 RST stub columns and 16 SST stub columns were tested, with consideration of parameters including internal stirrup, concrete strength, and cross-sectional aspect ratio B/D. The failure patterns, bearing capacity, stiffness and ductility of specimens were analyzed based on the experimental results. A 3D finite element (FE) model was established for numerical simulation and parametric study to investigate the composite action among the steel tube, stirrups and the core concrete. The improvement of energy dissipation capability due to the stirrups confinement on the core concrete is also discussed. In addition, a unified theoretical formula to predicted ultimate bearing capacity for SST stub columns and RST stub columns subjected to compressive load was developed according to the superposition principle with rational simplification. It is shown that the proposed formula for these columns has a higher accuracy compared with the existing formulas in current literatures and codes.

Tunnelling in congested urban area may inevitably induce ground movement causing damage to adjacent surface buildings. Past research usually oversimplified surface structure as an equivalent elastic beam, which is unable to represent behaviour of a framed building realistically due to frame action. In this study, a series of numerical analyses were conducted to investigate the behaviour and damage mechanism of a framed building with individual footing due to tunnelling induced ground movements. Nonlinear behaviour of the infilled wall and the interfaces between soil-structure and between frame-wall were explored to interpret the complex interaction effects in the system. A non-uniform deformation around the tunnel was applied to simulate the realistic tunnelling induced ground movements while the distribution of initial ground stiffness affected by building weight was reproduced by a user defined nonlinear constitutive model. The different responses in terms of angular distortion, horizontal strain and smeared crack pattern of the framed building subject to scenarios with different ground stiffness, interface parameters and different frame infill configurations were evaluated. The results can be practically used to assess the performance of framed building subject to different ground deformation conditions resulting from tunnelling. The presented analysis provided a useful background for properly understanding and prioritizing those factors having a significant effect on the response of framed building to tunnelling induced ground movements.

In this paper, the multi-time-step method (MTS) of time integration is proposed to reduce the computational cost of solving the dynamic interaction of a train-track-bridge coupled system (TTBS). Considering the different domain frequency characteristics of the dynamic responses of the train, track, and bridge, the MTS method decomposes the TTBS into two smaller subdomains: the train-track coupled subsystem with a high domain frequency, and the bridge subsystem with a low domain frequency. A fine time-step and a coarse time-step are respectively adopted for the train-track subsystem and the bridge subsystem to improve the computational efficiency. The two subsystems are coupled by the interaction forces between the track and bridge. Two partition types of the TTBS are introduced and the effect of different decomposition types on the accuracy and efficiency of the MTS method are discussed. The proposed method is validated by comparing the numerical results with field measurement data of a simply supported bridge. A numerical simulation of a train traversing a long-span cable-stayed bridge is used to demonstrate the computational efficiency and accuracy of the proposed method. It is shown that the proposed method is accurate and computationally more efficient than using a uniform time-step for the entire TTBS.

Borate bioactive glass (BBG) stimulates angiogenesis and promotes cell growth. However, controlling the degradation rate of BBG and maintaining the critical concentration of bioactive ions suitable for cell promotion and differentiation remain great challenges in soft tissue repair. In this study, a novel approach was proposed to produce nanosized CO32−-containing hydroxyapatite (HCA)-coated BBG (nano-HCA@BG). Unlike the previously reported hard-to-degrade hydroxyapatite (HA) coating after static soaking treatment of BBG, the nano-HCA@BG, obtained by dynamically immersing the BBG powder in a flowing buffer, had a porous structure and was surface-coated with a layer of amorphous HCA, which improved the biocompatibility and retained the biodegradability of BBG. The effects of nano-HCA@BG were evaluated and compared with those of powdered BBG at the cellular and animal levels. The formation of the HCA-coated nanoporous architecture significantly improves biocompatibility, promotes cell growth and proliferation, and is beneficial for wound healing in rodent skin defects.

Metallic yielding damper is widely utilized to improve the seismic resilience of steel moment-resisting frames. It is a kind of displacement-depended damper and may fail when the ultimate displacement is reached under strong earthquakes. Nevertheless, little research has considered the damper failure behavior in seismic loss assessment of damper-retrofitted steel frames. In this paper, three representative buildings, including a 3-story, 9-story and 20-story steel frame, are retrofitted by a high efficient bending-yield metallic damper. The damper is designed based on the stiffness and displacement demands, and able to keep normal working under maximum considered earthquakes. Numerical models of the retrofitted steel frames with and without considering damper failure are then built, and cyclic behavior of the damper element is validated through the experimental results. Subsequently, nonlinear dynamic analysis is performed to evaluate effectiveness of the design procedure, and incremental dynamic analysis (IDA) is conducted to discuss the effect of damper failure on structural seismic fragility. Combing with the obtained seismic fragility curves, the effect of damper failure on the seismic losses of steel moment-resisting frames are quantitatively assessed using a story-based loss estimation methodology. The results show that the employed damper can effectively mitigate dynamic responses of low-, mid- and high-rise frames; the effect of damper failure on IDA curves is significant at relatively large seismic intensity, especially for the high-rise frame; ignoring the damper failure would lead to significant underestimation of collapse and demolition probability; the models without considering damper failure present higher expected total losses, and the damper failure has few effects on the expected annual losses.

With the development of cities, buildings have become increasingly concentrated. Therefore, there are serious potential collision dangers between the adjacent buildings or the building partitions under earthquakes, hence buildings need to set the appropriate safety distance to avoid pounding. However, the calculation of the minimum safety distances (MSD) of the adjacent buildings in Chinese Code is rough and arbitrary, while the traditional response spectrum method is derived based on the assumption of proportional damping and it is difficult to consider the non-proportional damping characteristics for large and complex building systems. Based on the above, this paper proposes a new general spectral difference method (gSDM) to calculate the MSD. First, the pseudo-excitation method is used to derive the relative displacement random expression of adjacent buildings during earthquakes. Then, combined with the response spectrum method, the gSDM formula is established, in addition, the explicit expressions of combination coefficient in the gSDM formula are given. Finally, the examples of two adjacent multi-storey shear-buildings are used to illustrate the accuracy and wide adaptability of the gSDM during the El-Centro earthquake. The results compared and discussed in detail with the classical spectral difference method (cSDM), SRSS method and time history analysis.

Fatigue performance of RC plate girder was experimentally investigated. A corrosion-fatigue life assessment approach of railway RC girders under combined carbonation and train loads was proposed. The proposed approach was applied to an 8 m-span RC plate girder in an existing heavy-haul railway bridge, and the effects of annual freight volume, train axle weight, and carbonation environment level on corrosion-fatigue life were analyzed. Results indicate that annual freight volume, train axle weight, and carbonation environment level have a significant impact on corrosion-fatigue life, which can decrease the remaining corrosion-fatigue life by up to 48.71%, 91.11%, and 60.90%, respectively.

With the large-scale application of high-speed railways (HSR) in China, the ballastless track-bridge will inevitably experience fatigue damage. As a result, the maintenance and repair of the HSR track-bridge are becoming extremely urgent. However, the research on the track-bridge is very lacking presently and its mechanical fatigue performance and service life are still uncertain. Therefore, it is of great necessity to carry out a fatigue test on track-bridge to reveal the mechanical properties evolution of the structure and predict its service life under fatigue train loads. In this paper, a quarter-scale specimen of a prestressed simply supported concrete box-beam with CRTS Ⅱ (The China Railway Track System Type Ⅱ) ballastless track was constructed. A series of fatigue tests were carried out on the structural system and the following conclusions were noted. First, there are no visible cracks on the surface of the track-bridge after a fatigue loading test of 18 million cycles, and its mechanical properties of collaborative work perform well. Second, the mechanical performance of the box-beam remain elastic and its stiffness is basically stable under the long-term fatigue train load. Third, the calculated fatigue life of the track-bridge shows that the box-beam, track slab, base slab and cement asphalt mortar (CA mortar) all had extremely long fatigue lives, which demonstrates that it is difficult for them to suffer failure under fatigue train loads. Moreover, after the fatigue test, the results of cumulative fatigue damage show that the most damaged component of the track-bridge is the box-beam, followed by the CA mortar, the base slab and the track slab, and their predicted residual life are expected to be 73.67%, 92.90%, 99.99% and 99.99% of the total fatigue life, respectively. Therefore, more attention should be paid to the damage of box-beam in the repair and maintenance of the HSR track-bridge.

As a new member of concrete-filled steel tube (CFT) structural families, concrete-filled elliptical steel tubes (CFETs) have great potential to be used as piers and columns in bridges and airport terminals because of its low flow resistance coefficient and reasonable distribution of major–minor axis. Hence, the main objective of this paper presents an experimental investigation on the seismic behavior of terminal stirrup-confined concrete-filled elliptical steel tube (TS-CFET) columns. Pseudo-static tests were tested to investigate the seismic performance of TS-CFET columns, including 3 concrete-filled elliptical steel tube (CFET) columns and 11 terminal stirrup-confined concrete-filled elliptical steel tube (TS-CFET) columns. Those key parameters varied in the experiments included the stirrups, height of terminal stirrup region, equivalent stirrup ratio, loading direction, slenderness ratio and axial load ratio. Then, based on the experimental results, the complete curves analysis on the load (P) vs. deflection ( Δ ) hysteretic curves were analyzed in detail, and the failure modes and composite action between the steel tube and core concrete were discussed and clarified. Furthermore, six indexes were employed to quantify the effect of varied parameters. The experimental results indicated that using stirrups in the CFET columns can directly confine the core concrete, and then considerably enhance the seismic behavior of CFET columns especially under higher axial load ratio. With the increase of axial load ratio, the energy dissipation capacity increased, while the displacement ductility decreased. The seismic performance of TS-CFET columns under major axis loading was obviously superior to that under minor axis loading. Additionally, the slenderness ratio had significant influence on the ultimate bearing capacity, stiffness and ductility of composite columns.

Concrete-filled elliptical steel tube (CFET) is a novel type of composite member, which has great potential to be used as piers and columns in bridges and airport terminals because of its low flow resistance coefficient and reasonable distribution of major-minor axis. Pure bending loading conditions are not frequently occurred in practical engineering, but the flexural researches are important since it's the basis of mechanical property researches under complex loading. However, little attention to the flexural behavior of CFETs has been paid at present. Hence, the main objective of this paper presents a combined experimental and numerical investigation on the flexural behavior of CFETs. Flexural tests were carried out to investigate the behavior of CFETs under bending. The moment vs. curvature curves during the whole loading process was analyzed in detail, and all the specimens behaved in a very ductile manner. Besides, the composite action between the steel tube and core concrete was discussed and clarified based on experimental results. Furthermore, FE (Finite element) model with precise material constitutive models was established to investigate the flexural mechanical of CFETs comprehensively, in terms of the full curves analysis on the moment vs. curvature curves, development of the stress and strain distribution in the steel tube and core concrete, and composite action. It should be noted that there existed bond slip in the interface between the core concrete and steel tube during the loading process. Then, the parametric studies with various factors were performed. Finally, design formulas were proposed to predict the ultimate moment and flexural stiffness of CFETs. The predicted results showed satisfactory agreement with the experimental and FE results . Moreover, the difference among the experimental, FE and predicted results using the related design codes were illustrated. The results of this study are expected to provide a reliable reference for design and application in concrete-filled elliptical steel tube (CFST) structures.

The migration and transport of water in the hydrophilic porous structure of cement-based materials are the main reason for the durability degradation. Hydrophobic cement-based materials have been developed to prevent water penetration and hence greatly improve the durability. This paper aims to present a comprehensive review on the latest advances of hydrophobic cement-based materials. Firstly, the assessment and test methods of hydrophobic cement-based materials, including surface wettability, water absorption and impermeability are introduced. Secondly, the strategies of surface and integral hydrophobic modifications are introduced, and the effects of different strategies are holistically evaluated. Thirdly, the durability and mechanical properties of cement-based materials affected by surface and integral hydrophobic modifications are summarized. Finally, the key scientific problems and challenges in this field are concluded and future research directions are proposed. It is expected that this review can guide further research on the design, preparation and characterization of hydrophobic cement-based materials.

This study investigates a novel prefabricated concrete frame beam with an innovative assembly pattern that is cost-effective, reliable, practical, and has a good fault-tolerance. Quasi-static cyclic experiments were carried out on a cast-in-place (CIP) beam and three precast concrete (PC) beams with different lengths or widths of protruding beam stumps. The cracking propagation mode , load-bearing capacity, beam ductility, beam stiffness , and plastic energy dissipation ability were comparatively analysed. It is concluded that the hysteretic behaviour of the PC beams with the innovative assembly pattern suggested in this study was similar to that of the CIP. Moreover, PC beams with a wider protruding beam stump displayed better seismic performance . In particular, development curves of crack width with cyclic load were obtained, which showed that the cracks widened gradually as the number of load cycles increased, and the main crack width increased significantly around the peak load. A finite element model (ABAQUS) was established to further reveal the working mechanisms and conduct a parametric investigation of the PC beams. Parametric simulations indicated that a reasonable and relatively larger thickness of the U-shaped beam shell and higher post-pouring concrete strength are recommended for practical applications of the proposed novel prefabricated concrete frame beams.

Track–bridge interaction under the seismic excitation is a dominant factor to the design and operation of railway bridges. A spatial model integrating rails, deck system, stringers, cross beams, suspenders, main trusses, piers and foundations was established in this paper, adopting non-linear springs to simulate the longitudinal resistance between the track and the bridge. The improved Penzien model was utilised to simulate the soil-pile interaction effect and a computer program was developed to generate artificial seismic waves. Comparison of natural vibration characteristics for the track–bridge system with and without considering the track constraint was made. Furthermore, the effects of sensitive parameters were investigated, including the ballast resistance, friction of movable bearings, location of rail expansion joint (REJ), etc. Present study results indicate that the track–bridge interaction enhances the structural integrity and induces relatively higher natural frequencies of the bridge....

Facet engineering of oxide nanocrystals represents a powerful method for generating diverse properties for practical and innovative applications. Therefore, it is crucial to determine the nature of the exposed facets of oxides in order to develop the facet/morphology–property relationships and rationally design nanostructures with desired properties. Despite the extensive applications of electron microscopy for visualizing the facet structure of nanocrystals, the volumes sampled by such techniques are very small and may not be representative of the whole sample. Here, we develop a convenient 17O nuclear magnetic resonance (NMR) strategy to distinguish oxide nanocrystals exposing different facets. In combination with density functional theory calculations, we show that the oxygen ions on the exposed (001) and (101) facets of anatase titania nanocrystals have distinct 17O NMR shifts, which are sensitive to surface reconstruction and the nature of the steps on the surface. The results presented here open up methods for characterizing faceted nanocrystalline oxides and related materials. The exposed facets of oxide nanocrystals are key to their properties. Here, the authors use 17O solid-state NMR spectroscopy to discriminate between oxygen species on different facets of anatase titania nanocrystals, providing compelling evidence for the value of NMR spectroscopy in characterizing faceted oxides.

Based on the random theory of the probability density evolution method (PDEM), a refined random wheel/rail contact model for train-track-bridge systems is proposed. The trace line method with the law of equal slopes is developed to determine the wheel/rail contact locations, which are described by probability density functions on the wheel/rail surface. The number theoretic method (NTM) and stochastic harmonic functions (SHFs) are employed to generate the representative random track irregularities. Considering the excitation of random track irregularities and the wheel/rail contact geometry, the wheel/rail normal contact force and the tangential creep force are accurately calculated and analyzed using the proposed wheel/rail contact model. A high-speed railway case study is presented to reveal the random dynamic characteristics of a train-track-bridge system and the wheel/rail interaction. The results show that the time-varying probability density evolution functions of the wheel/rail contact points can effectively indicate both the phenomenon of wear on the rail surface and its distribution characteristics. Additionally, some significant conclusions are obtained.

Solvent effect plays an important role in manipulating the chemical reactivity, equilibrium constant, and reaction rate. Such effect is observed in heterogeneous catalysis, especially for the acidic zeolite catalyst with molecularly size pores (≤1 nm). Nevertheless, it is a great challenge to systematically investigate the intermolecular interaction and the mechanism of solvent effect on the catalytic performance inside the acidic zeolite nanocages. Here, we used the state-of-the-art solid-state NMR (SSNMR) experimental techniques combined with multiscale theoretical simulations to quantitatively investigate the solvent effect on the reactant electronic property and reaction activity. In particular, a series of 13C CP/MAS solid-state NMR experiments with acetone probe for H-ZSM-5 zeolite were performed via changing the coadsorption amount of nitromethane solvent. It is found that the solvent effect accounts for the enhancement of the apparent Bronsted acidic strength of zeolite catalysts, and thus promote...

Compressive tests of the CFST stub columns with artificial notches in the steel tubes were conducted in this paper to investigate the effects of the material imperfections of steel tubes on column performances. The load-strain responses, column strength and confining effects were discussed in detail. A parametric study, including the notch length, notch orientation, notch location and ductility, was also conducted. The results indicate that the notched CFST specimens have quite different failure modes from the intact CFST specimens. A notched CFST specimen may fail by bulging or closing of the notch, which was determined by the notch orientation. The results also show that the notched CFST specimens had lower mechanical performances than the intact CFST specimens because the notch steel tube could not offer sufficient confining effect on the concrete core inside it. Based on the experimental results, a practical calculation formula for the bearing capacity of notched CFST columns was proposed, which gave well agreement with the experimental results.

A method for X-ray computed tomography quantification of damage in concrete under compression considering irreversible mode-II microcracks is developed. To understand damage behaviour in concrete, a micromechanical analysis of damage under biaxial compression is conducted focusing on random micro-defects in micro-cells isolated from the representative volume element. Furthermore, for stress–strain response prediction, a quantification is developed concerning the behaviours of the dominant macrocracks in multiaxial compression. Specifically, two crack types are taken into account: mode-I cracks and irreversible deformation cracks (including mode-II microcracks). Furthermore, mode-I cracks generate compression-induced tensile load (transverse) area reduction and further stiffness degradation, whereas the latter contribute to the development of irreversible strains. Additionally, by investigating the development of gradually converging dominant cracks, the procedure for quantifying damage is competently executed. In addition, distinguished from other approaches, the quantified damage can be applied directly to constitutive models to produce stress–strain response highly agrees with experimental results.

China’s high-speed railway (HSR) construction industry has been experiencing a golden period of opportunities in the recent decades. Due to the necessity of protecting arable lands and the advantage of rapid construction, bridges (elevated structures) are predominantly used in China’s HSRs, which must meet the critical small settlement requirement. This article first reviews the main technical standards of small- to medium-span HSR bridges, where their comparison with the Japanese standard and International Union of Railway standards is highlighted. Then, the long-span HSR steel bridges are described and discussed case by case. Based on the engineering practice of HSRs, the main achievements and key technologies of HSR bridges in China are provided, followed by the opportunities and challenges of the current and future developments of HSR bridges.

In this paper, we use silica nanoparticles modified by methacryloxy propyl trimethoxylsilane (KH570) as the core material, and employ polymers including hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and acrylic ester as the shell materials to prepare the hydrophobic inorganic–organic hybrid nanocomposites with a seed emulsion polymerization strategy. The size, morphologyandproperties of the core-shell structured nanoparticles are investigated by TEM and SEM. The results showthat the polymer nanocomposite has three concentric layers with silica nanoparticles in the center, acrylic polymer as the internal shell and fluorosilicone polymer as the outmost shell. By controlling the ratio of the silica nanoparticles and monomers, we can achieve each composite particle has the core-shell structure with silica nanoparticles as the core and the thin layer of fluorosilicone polymer as the shell. Compared with the traditional polymer film, the nanocomposite film shows a hydropho...

Background: Glial Maturation Factor Beta (GMFB) is a highly conserved brain-enriched protein implicated in immunoregulation, neuroplasticity and apoptosis, processes central to neural injury and repair following cerebral ischaemia. Therefore, we examined if changes in neurocellular GMFB expression and release can be used to assess brain injury following ischaemia. Methods and Results: Immunofluorescence staining, Western blotting, immunohistochemistry and ELISA were used to measure GMFB in cultured neurons and astrocytes, rat brain tissues and plasma samples from stroke model rats and stroke patients, while cell viability assays, TTC staining and micro- PET were used to assess neural cell death and infarct severity. Immunofluorescence and immunohistochemistry revealed GMFB expression mainly in astrocyte and neuronal nuclei but also in neuronal axons and dendrites. Free GMFB concentration increased progressively in the culture medium during hypoxia-hypoglycaemia treatment. Plasma GMFB concentration increased in rats subjected to middle cerebral artery occlusion (MCAO, a model of stroke-reperfusion) and in stroke patients. Plasma GMFB in MCAO model rats was strongly correlated with infarct size (R2=0.9582). Plasma GMFB concentration was also markedly elevated in stroke patients within 24 h of onset and remained elevated for more than one week. Conversely, plasma GMFB elevations were not significant in myocardial infarct patients and stroke patients without infarction. Conclusion: GMFB has the prerequisite stability, expression specificity and response dynamics to serve as a reliable indicator of ischaemic injury in animal models and stroke patients. Plasma GMFB may be a convenient non-invasive adjunct to neuroimaging for stroke diagnosis and prognosis.

Hydroxyapatite (Hap) has been shown to be an excellent sorbent for F

For concrete, fatigue is an essential mechanical behavior. Concrete structures subjected to fatigue loads usually experience a progressive degradation/damage process and even an abrupt failure. However, in the literature, certain essential damage behaviors are not well considered in the study of the mechanism for fatigue behaviors such as the development of irreversible/residual strains. In this work, a damage model with the concept of mode-II microcracks on the crack face and nearby areas contributing to the development of irreversible strains was proposed. By using the micromechanics method, a micro-cell-based damage model under multi-axial loading was introduced to understand the damage behaviors for concrete. By a thermodynamic interpretation of the damage behaviors, a novel fatigue damage variable (irreversible deformation fatigue damage variable) was defined. This variable is able to describe irreversible strains generated by both mode-II microcracks and irreversible frictional sliding. The proposed model considered both elastic and irreversible deformation fatigue damages. It is found that the prediction by the proposed model of cyclic creep, stiffness degradation and post-fatigue stress-strain relationship of concrete agrees well with experimental results.

Graphene-based materials still exhibit poor electrocatalytic activities for the hydrogen evolution reaction (HER) although they are considered to be the most promising electrocatalysts. We fabricated a graphene-analogous material displaying exceptional activity towards the HER under acidic conditions with an overpotential (57 mV at 10 mA cm-2 ) and Tafel slope (44.6 mV dec-1 ) superior to previously reported graphene-based materials, and even comparable to the state-of-the art Pt/C catalyst. X-ray absorption near-edge structure (XANES) and solid-state NMR studies reveal that the distinct feature of its structure is dual graphitic-N doping in a six-membered carbon ring. Density functional theory (DFT) calculations show that the unique doped structure is beneficial for the activation of C-H bonds and to make the carbon atom bonded to two graphitic N atoms an active site for the HER.

An ideal porous adsorbent toward uranium with not only large adsorption capacity and high selectivity but also broad applicability even under rigorous conditions is highly desirable but still extremely scarce. In this work, a porous adsorbent, namely [NH4]+[COF‐SO3 −], prepared by ammoniating a SO3H‐decorated covalent organic framework (COF) enables remarkable performance for uranium extraction. Relative to the pristine SO3H‐decorated COF (COF‐SO3H) with uranium adsorption capacity of 360 mg g−1, the ammoniated counterpart of [NH4]+[COF‐SO3 −] affords ultrahigh uranium uptake up to 851 mg g−1, creating a 2.4‐fold enhancement. Such a value is the highest among all reported porous adsorbents for uranium. Most importantly, a large distribution coefficient, K d U, up to 9.8 × 106 mL g−1 is observed, implying extremely strong affinity toward uranium. Consequently, [NH4]+[COF‐SO3 −] affords highly selective adsorption of uranium over a broad range of metal ions such as SU/Cs = 821, SU/Na = 277, and SU/Sr = 124, making it as effective uranium adsorbent from seawater, resulting in amazing uranium adsorption capacity of 17.8 mg g−1. Moreover, its excellent chemostability also make it an effective uranium adsorbent even under rigorous conditions (pH = 1, 8, and 3 m acidity).

Background The prevalence of drug-resistant bacterial infections urges the development of new antibacterial agents that possess a mechanism of action different from traditional antibiotics. FtsZ has been recognized as a key functional protein in bacterial cell division and it is currently believed to be a potential target for the development of novel antibacterial agents. Purpose The primary aim of the study is to screen out an inhibitor targeting at FtsZ and followed to investigate its antibacterial activity and mode of action. Methods Cell-based cell division inhibitory screening assay, antimicrobial susceptibility test, minimum bactericidal concentration assay, time-killing curve determination, FtsZ polymerization assay, GTPase activity assay, and molecular modeling were performed in the present study. Results The screening study from a small library consisting of benzimidazole and indole derivatives discovered a compound (CZ74) with an indole-core structure. The compound exhibited strong cell division inhibitory effect. In addition, CZ74 shows high antibacterial potency against a number of tested Gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The minimum inhibitory concentration values obtained were within the range of 2–4 µg/mL. The results of biological study revealed that CZ74 at 2 µg/mL is able to disrupt FtsZ polymerization and inhibit GTPase activity and cell division. From molecular modeling study, CZ74 is found possibly binding into the interdomain cleft of FtsZ protein and then leads to inhibitory effects. Conclusion This indole-cored molecule CZ74 could be a potential lead compound and could be further developed as a new generation of antibacterial agents targeting FtsZ to combat against multidrug-resistant bacteria.

CRTS III (China Railway Track System III) slab ballastless track structure is one of the high-speed railway ballastless track structures which has Chinese independent intellectual property rights. The mechanical performance of CRTS III slab ballastless track structure under temperature load has not been clear yet. Therefore, through temperature field model and temperature load values selected by statistics analysis based on long-term meteorological data, the mechanical performance of ballastless track structure is studied under two typical working conditions with different safety probability. It is found that the daily extreme values of monthly axial uniform temperature and the daily maximum temperature gradient obey certain statistical laws. In addition, the maximum tensile stress of the self-compacting concrete layer is located in the middle and edge of the slab bottom and the side of the slab. The maximum tensile stress of the base plate is located at the edge of the surface of the layer and the inner edge of the limiting groove. The interface normal tensile stress is located at the end and corner of the interface. Furthermore, maximum stress increases with the increase of safety probability.

This paper proposed a fast modeling technique (FMT) for the vertical dynamic analysis of the coupled train-track-bridge (TTB) systems, which combines the train subsystems and track-bridge subsystems by the client-server technique to complete the entire TTB analysis on simplex OpenSees simulation platform. Thus, the FMT could dramatically reduce the time consumed of programming and modeling and significantly reduce the amount of data transmission between subsystems for TTB interaction. Moreover, FMT could take full advantage of OpenSees in nonlinear and seismic analysis. So FMT is a practical and convenient approach to analyze the TTB coupling vibration, and especially it is suitable for the junior researchers of TTB interaction. FMT could improve the modeling efficiency to save time.

In this study, water transport in concrete was investigated using an environmental simulation test system, and the boundary conditions of water transport on the concrete surface are propose...

With the rapid development of high-speed and urban rail transit, ballastless slab tracks have been widely used in many areas. The work on construction, design, and mechanics of ballastless slab tracks is abundant and achievements have been made. However, a platform for numerical simulation and dynamic analysis of slab track systems subjected to a moving train still needs to be probed into. In the MATLAB®, effective and easily programable methods are presented to guide the construction of the vehicle-slab track interaction system and the realization of long length computation in this present study. Based on previous studies, the formulation of slab track dynamics in the framework of finite element theory is founded with simplicities, and then the wheel-rail coupling matrices totally derived from the nonlinear wheel-rail normal contact/tangential creep forces using the energy variation method are presented. Following the dynamics modeling construction, an improved method for long or infinite length computation is proposed. With an implementation of this method, the effect of the spatial variability of track properties on vehicle-track system dynamic performance can be evaluated conveniently. Using this numerical simulation platform, extensive studies have been conducted to model and analyze the influence of spatial variability of filling layer support stiffness, the track slab finite element type and support type of steel spring for floating-slab tracks, etc.

The high-speed maglev vehicle-guideway coupled system (MVGCS) is a complex system, whose random vibration characteristics have not been well studied due to a limited number of examples. To address this issue, a new efficient approach is proposed for the random vibration analysis of the MVGCS, which combines the probability density evolution method and multi-time step method with multiple random loads considered. The random model established for 10-degree-of-freedom maglev vehicles and guideway is time-dependent, considering two different supporting conditions. The Monte Carlo method is used to assess the accuracy and efficiency of the proposed approximate approach, and the random model is verified through comparison with available results. The stochastic dynamic responses of the vehicles, guideway, and electromagnetic levitation forces, including the mean values and standard deviations, are determined in a case study. The results show that the proposed method is feasible for the dynamic analysis of maglev systems with a reasonably good efficiency in computation. Furthermore, critical parametric analyses involving vehicle speed, irregularity, and cut-off wavelength are performed with the results discussed.