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Abstract Background and aim Recent Mendelian randomization and meta analysis suggest a controversial causality between C3-epimer of 25 hydroxyvitamin D3 (C3-epi-D3) and type 2 diabetes mellitus (T2DM). The clinical evidence regarding the impact of C3-epi-D3 on the progression of T2DM is currently insufficient. This study aims to investigate whether C3-epi-D3 has any effect on metabolic disorders of T2DM patients. Methods A total of 1222 patients with T2DM were prospectively enrolled in this study and followed up every 1 to 2 months for 3 to 6 months. Kidney biomarkers, lipids, electrolytes, and 25 hydroxyvitamin D (25-OHD) metabolites were measured as required during follow-up, to investigate the association of C3-epi-D3 levels and %C3-epi-D3 with metabolic disorders, including dyslipidemia, chronic kidney disease (CKD), and calcium-phosphorus metabolic disorder. Results Among these T2DM patients, there were age and seasonal differences in C3-epi-D3 levels (χ 2 = 10.419 and 19.609, P = 0.034 and

Abstract The adverse pregnancy outcomes, including recurrent spontaneous abortion (RSA), are strongly correlated with water-soluble vitamins, but how to predict RSA occurrence using them remains unsatisfactory. This study aims to investigate the possibility of predicting RSA based on the baseline levels of water-soluble vitamins tested by ultra-liquid chromatography-tandem mass spectrometry. A total of 918 pregnant women was consecutively enrolled in this cross-sectional study. According to the miscarriage numbers, they were divided into normal first pregnancy (NFP, n = 608), once spontaneous abortion (OSA, n = 167), and continuous spontaneous abortion (CSA, n = 143) groups. The Cox proportional-hazards regression model was employed to establish a risk model for predicting RSA. The RSA occurrence was 6.54% in overall pregnant women, with a prevalence of 12.57% in the OSA group and 27.27% in the CSA group. Significant differences were observed in baseline deficiencies of vitamin B3, B5, B6, and B9 among NFP, OSA, and CSA groups (χ2 = 12.191 ~ 37.561, all P 0.05). Our study presents a highly sensitive model based on mass spectrometry assay of baseline levels in B vitamins to predict the RSA occurrence as possible.

Prestressed, precast composite panels are a type of building component that combines prestressing technology with composite materials; but, for most of them, it is difficult to balance structural stress performance and assembly efficiency. This paper proposes a series of novel bidirectional, prestressed, prefabricated, composite slabs, aiming to enhance their bidirectional force characteristics and assembly efficiency. By implanting a kind of specially designed concrete movable core rib with the same geometry as the cavity in the hollow-core slab at medium spacing, the transverse stressing performance of the structure is enhanced without affecting the unidirectional structural performance. Then, in the pre-set transverse apertures, several pieces of unidirectional, prestressed, precast hollow-core slabs that are implanted in the core mold are connected in series with high-strength strands and prestressed; finally, we obtain a bidirectional, prestressed, prefabricated composite slab. Two types of slabs (i.e., 3.3 m × 4.5 m and 4.5 m × 4.5 m) are selected and their mechanical behavior is investigated experimentally and by the finite element method, and the results are in good agreement. The proposed bidirectional, prestressed, precast composite slab not only has better overall bearing performance but also improves the structural stiffness and assembly rate, which can greatly improve the economic benefits and is of great significance for the popularization and application of assembled concrete structures.

To achieve a rapid assessment of reinforced bridges without interrupting traffic, the method and influence parameters for evaluating prestressed CFRP (Carbon Fiber Reinforced Polymer) plate-strengthened bridges were investigated based on distributed sensing while considering the bridge–vehicle coupling. Firstly, based on the principle of distributed monitoring, the strain influence line equation for prestressed CFRP plate-strengthened bridges under moving vehicle loads was derived. An evaluation index and method for assessing strengthening effectiveness based on distributed strain monitoring was proposed. Numerical simulation experiments were conducted for verification, in which a simulation method for solving the bridge–vehicle coupling vibration response based on the displacement contact method was studied. Relevant example verifications were carried out to prove the correctness of this method. On this basis, a dynamic performance analysis of the bridge before and after strengthening under bridge–vehicle coupling was performed. Finally, a study on influencing parameters was conducted to investigate the impact of different prestress levels of CFRP plates, different vehicle speeds, and different vehicle axle loads on the evaluation method. The results demonstrate that the bridge–vehicle coupling calculation model based on the displacement contact method can effectively simulate the dynamic response of the bridge after reinforcement. The evaluation method based on distributed sensing monitoring is unaffected by the speed and axle load of the vehicle, enabling the assessment of the condition and stress state of the strengthened bridge.

The transverse-direction post-seismic running safety of a longitudinally connected ballastless track-continuous girder bridge (LCBTCGB) system considering earthquake damage state (EDS) was studied. In this study, a simulation model of an LCBTCGB was established, and the post-earthquake damage law of the LCBTCGB was analyzed by selecting the ground motion that had the greatest influence from within the existing studies. The EDS of key interlayer components and the residual deformation law of each layer structure of the LCBTCGB system were defined. Subsequently, the residual deformations and EDS from the simulation model were imported into a coupled dynamic model of the train, track, and bridge. Evaluation of running safety evaluation after an earthquake was carried out with and without considering EDS, and a running safety guidance diagram for after an earthquake is provided. The results revealed that under conditions of rare earthquakes, without considering EDS, the running safety judgment after the earthquake were underestimated, and the risk increased by 13.6%. Following the designed earthquake, the running safety risk after the earthquake increased by 18.7% if EDS was not considered. The risk of the running safety index exceeding the limit did not increase linearly with earthquake intensity with and without considering EDS. When the EDS was considered, derailment coefficients and wheel axle lateral forces exceeded the safety limit value at an earthquake intensity of 0.2 g, whereas these limit values were only exceeded at an earthquake intensity of 0.3 g when EDS is ignored. When the earthquake intensity reached 0.5 g, the influence on the derailment coefficient was greater but the difference in the wheel axle lateral forces was not significant with or without considering EDS. It is suggested that EDS should be considered when post-seismic running safety of LCBTCGBs are analyzed; otherwise, it will lead to misjudgment of running safety after an earthquake.

Effectively evaluating the effectiveness of bridge strengthening is a necessary means to ensure the normal operation of existing strengthened bridges, especially when evaluating the effectiveness of bridge strengthening without interrupting normal traffic. Based on a distributed long-gauge Fiber Bragg Grating (FBG) sensor, this paper derived the macro-strain influence line (MSIL) formula for a simply supported beam bridge under a moving vehicle load, studied the changes in the MSIL at the bottom of the beam under the vehicle load before and after the prestressed CFRP plate strengthening, and proposed a rapid evaluation method for the strengthening effect based on the amplitude of the MSIL as the evaluation index for the strengthening effect. Finally, the prestressed CFRP-strengthened steel beam was tested under the moving vehicle load. The theoretical analysis and the experimental results confirm that under the load of moving vehicles, the macro-strain–time history amplitude of the strengthened steel beams under different prestressed tensioning conditions is different. The amplitude of the macro-strain time history of the strengthened bridge is reduced compared to before strengthening, and the local strengthening effect of the bridge can be monitored by the amplitude change in a single sensor. The change in global stiffness can be evaluated by monitoring the MSIL obtained from multiple long-gauge strain sensors.

Based on the cable-stayed beam model, this paper studies the nonlinear coupled vibration behavior of basalt fiber-reinforced polymer (BFRP) cables on long-span cable-stayed bridges under parametric excitation. Considering the sag, damping of BFRP cables, and the coupled interactions between stayed cables and the main girder, the nonlinear coupling vibration model of the BFRP cable–beam composite structure has been established. Taking the longest cable of Sutong Bridge as a case study, the nonlinear coupled vibration behavior of BFRP cables under parametric excitation has been numerically analyzed using the finite difference method. The analysis results indicate that (1) under parametric excitation, the large amplitude nonlinear vibration of the BFRP cable will be induced with an evident “beat” phenomenon. (2) Under the same parametric excitation, the nonlinear coupling vibration response and the beta frequency of the BFRP cable were both smaller than that of the traditional steel cable. (3) The nonlinear coupling vibration response of the BFRP cable increased with an increment in excitation amplitude and a decrement in cable force. With the increase in the excitation frequency, weight per unit length, and axial stiffness, the nonlinear vibration response of the BFRP cable increased first and then decreased. Meanwhile, the damping ratio of the BFRP cable had no significant influence on the nonlinear coupling vibration.

With the increase of bridge-required demolition/dismantling for reconstruction or modification, the early warning of construction emergencies is greatly needed for monitoring the structural safety of bridges under construction. In this paper, based on the multi-source data of nearby construction and demolition construction of a large-span RC arch bridge in China, the Analytic Hierarchy Process (AHP) method is adopted to analyze the multi-source data and set the early warning threshold for bridge safety in construction. According to the analytical results, a reasonable evaluation of AHP factors can improve the accuracy and timeliness of safety early warning in the structural safety monitoring of bridges during the construction process. The weight of the monitoring data in AHP should be assigned according to its reliability, stability, and importance. Bridge safety assessment of nearby construction having harmful vibration should prioritize dynamic bridge monitoring by cooperating with multi-source data, including stress, and deformation monitoring of the bridge is necessary. The assessment results proved that multi-source data, including but not limited to structural stress and deformation monitoring data, vibration data, theoretical prediction data, environment data such as temperature data, and construction/maintenance history data, are necessary for safety monitoring and early warning of construction with specifications related to bridge construction. The early warnings triggered by the evaluation results successfully ensure the safety status of the bridge during nearby construction and demolition construction, which shows the proposed method can provide a guideline for comprehensively evaluating and early warning of the status of bridge construction.

In situ monitoring was conducted throughout the construction period to investigate the abnormal deformation of a bridge under construction subjected to sudden cooling by Typhoon Lekima. An FE model considering the temperature field based on measurement data was also established to reveal the exact causes of the bridge’s abnormal deformation and provide theoretical guidance for rehabilitation measures. The FE model simulation and measurement results showed that (1) the exact cause of the abnormal deformation of the bridge was the inconsistency of the temperature field between the top and bottom plates, and the sudden approach of the typhoon aggravated the inconsistency; (2) the abnormal deformation of the construction bridge caused by the typhoon could be addressed with rehabilitation before forming the bridge; (3) an extreme temperature field should be considered in the design of a beam–arch combination bridge. These results can provide a reference for the design and construction of similar bridges.

Structural health monitoring is an important means of obtaining the state information of bridges, and the extracted quasi-static strain signal can reflect the stress state of bridges directly. However, the strain signals acquired during the operation stage of bridges are dynamic, and the strain gauges used in the health monitoring system are short (no more than 10 cm), which means they are easily affected by small damage at the installation parts of bridges and thereby the monitoring signal abnormalities occur. A type of externally affixed long-gauge fiber strain gauge is used to monitor the health of bridges, and the dynamic and quasi-static signal separation method for long-gauge strain sensors is studied under different vehicle loads; at the same time, the dynamic monitoring performance of the long-gauge sensor is investigated in this paper. The quasi-static strain signal extracted from the dynamic macro-strain signal can be used to directly monitor the stress status of the bridge. The results show that the method proposed in this paper is feasible for extracting the quasi-static macro-strain from a dynamic long-gauge strain signal.

A finite model updating method that combines dynamic-static long-gauge strain responses is proposed for highway bridge static loading tests. For this method, the objective function consisting of static long-gauge stains and the first order modal macro-strain parameter (frequency) is established, wherein the local bending stiffness, density and boundary conditions of the structures are selected as the design variables. The relationship between the macro-strain and local element stiffness was studied first. It is revealed that the macro-strain is inversely proportional to the local stiffness covered by the long-gauge strain sensor. This corresponding relation is important for the modification of the local stiffness based on the macro-strain. The local and global parameters can be simultaneously updated. Then, a series of numerical simulation and experiments were conducted to verify the effectiveness of the proposed method. The results show that the static deformation, macro-strain and macro-strain modal can be predicted well by using the proposed updating model.

The railway environmental vibration caused by high-speed railways is harmful to the human health, the structural safety of adjacent buildings, and the normal use of precision instruments. At the same time, it occurs frequently. In this case, the railway environmental vibration has drawn much attention with the rapid development of highspeed railways. Studies in Earthquake Engineering show that a convex topography has a great impact on ground vibrations, however, there is no consideration about the convex topographic effect in the study of the railway environmental vibration when the convex topography is near the roadway. In this paper, the influence of a convex topography on the railway environmental vibration was investigated. Two-dimensional (2D) finite element models consist of subgrade-convex topography and subgrade-flat topography are established using the finite element method. The length and the height of the analysis model are taken as 200 m and 41.3 m, respectively. The external soil of the calculation model is simulated via the artificial boundary. By comparison with measured results, the 2D finite element models were verified to be effective. The convex topographic effect is studied by conducting parameter investigations, such as the bottom width, cross-sectional shape, height-width ratio and the foundation soil properties. Results show that the dimension and cross-section shape of the convex topography and the foundation soil properties have significant effect on the convex topographic effect. [ABSTRACT FROM AUTHOR]

Interleukin‑12 (IL‑12) serves an important role in immune responses and antitumor activity. The study of the association between autophagy and cancer cells remains controversial. The present study aimed to investigate the effect of IL‑12 on autophagy in the human breast cancer cell lines MDA‑MB‑231 and MCF‑7, and the possible molecular mechanism. Breast cancer cells were treated with different concentrations of recombinant IL‑12. The expression of the autophagy‑associated protein microtubule‑associated protein light chain 3 (LC3) was determined using western blot analysis, fluorescein isothiocyanate‑labeled LC3 was detected using fluorescence microscopy and autophagosomes were examined using transmission electron microscopy. Alterations in the phosphatidylinositol 3‑kinase/Rac‑α serine/threonine protein kinase (PI3K/Akt) and 5'‑AMP‑activated protein kinase subunit β‑1 (AMPK) pathways, in addition to pathway‑associated proteins, were detected using western blotting, following treatment with IL‑12 and pretreatment with the PI3K/Akt activator insulin‑like growth factor or the AMPK inhibitor compound C. It was observed that IL‑12 was able to upregulate the expression of the autophagy‑associated protein LC3 in a concentration‑ and time‑dependent manner, and induce the formation of autophagosomes in the two cell lines, and that the above effects involved the inhibition of the PI3K/Akt signaling pathway and the activation of the AMPK signaling pathway. [ABSTRACT FROM AUTHOR]

Ambient vibration tests and analyses of a long-span rigid-frame bridge were conducted using distributed long-gauge fiber-optic sensors. The concept of a long-gauge fiber-optic sensor and its merit to reveal local and global structural features are presented. Monitoring of a long-span bridge was performed using long-gauge sensors, and a method to calculate structural deformation distribution from the measured long-gauge strains is proposed, in which shear-deformation effect is considered because the main girder of the studied bridge is deep with a length-depth ratio of 17.9 at the end of the middle span. Modal identification of the studied bridge using the measured long-gauge dynamic strains was also performed, from which strain and displacement mode shapes were identified. Those results demonstrate the superiority of long-gauge fiber-optic sensors and their successful application to the studied bridge. [ABSTRACT FROM AUTHOR]