Search

In recent years, there has been an increase in accidents involving vessels colliding with bridge piers. These ship–bridge collisions can result in tragic loss of life and severe damage to the bridge structure. To address this issue, a type of fender pile made of winding-formed glass fiber-reinforced polymer (GFRP) was proposed as a solution. In this article, three- and four-point bending tests were performed to compare and analyze the damage modes and load-carrying capacity of the fender piles at two different winding angles, namely 45° and 75°. Vertical impact test was simulated using ANSYS/LS-DYNA to verify finite element models. The results revealed variations in damage patterns and bending performance of GFRP piles under the two fiber winding angles. The simulation results suggest that GFRP fender piles can effectively increase the impact time of ship–bridge collisions and reduce the collision forces, thereby significantly improving the protection of bridge piers.

Objective To explore the regulative effect and mechanism of cytochrome P450 1A1 (CYP1A1) on regulating lipopolysaccharide (LPS)-induced arginase-1 (Arg-1) expression in macrophages. Methods After mouse macrophage-like cell line RAW264.7 (RAW) was treated with 10 mg/L LPS for 0, 12 and 24 h, respectively (n=3 for each time point), the expression of CYP1A1 and Arg-1 at mRNA and protein levels were measured by RT-PCR and Western blotting. Negative control RAW(NC/RAW) cells, CYP1A1-overexpression RAW (CYP1A1/RAW) cells, CYP1A1-knockout RAW (CYP1A1 KO/RAW) cells and CYP1A1 hydroxylase-activity mutant RAW (CYP1A1m/RAW) cells were constructed, respectively, and then the cells were treated with LPS and further detected with RT-PCR and Western blotting for the expression and activation levels of Arg-1 and signal transducer and activators of transcription-6 (STAT6). Then STAT 6 inhibitor AS1517499 was added to treat the CYP1A1 KO/RAW cells and NC/RAW cells, and the mRNA and protein expression of Arg-1 was measured again after LPS or PBS treatment. CYP1A1 epoxidase inhibitor, nordihydroguaiaretic acid (NDGA) and 12 (S)-HETE were introduced to treat normal RAW cells, the mRNA and protein levels of Arg-1 and activity of STAT6 were detected after LPS or PBS treatment. Results LPS-induced CYP1A1 and Arg-1 were highly expressed in staggering peaks in RAW cells (P < 0.05). Overexpression of CYP1A1 inhibited LPS-induced Arg-1 expression and STAT6 activation in RAW cells, while CYP1A1 knockout enhanced above effects (P < 0.05). STAT6 inhibitor AS1517499 abolished the enhancement of CYP1A1 knockout (P < 0.05). CYP1A1 hydroxylase-activity mutation or 12(S)-HETE simulation had no effect on the expression of Arg-1 (P>0.05), while CYP1A1 epoxidase-activity inhibitor NDGA enhanced Arg-1 expression and STAT6 activation (P < 0.05). Conclusion CYP1A1 can inhibit Arg-1 expression by reducing STAT6 activation in LPS-induced macrophages, and CYP1A1 hydroxylase-activity or its proinflammatory metabolism 12(S)-HETE has no effect on this regulation, while CYP1A1 epoxidase-activity may be involved in this effect.

Solid state amplifier (SSA) has been increasingly applicated in accelerators facilities in recent years. However, with the improvement of the power level, equipment failure caused by reflected power becomes the main risk in long-term operation of SSA. A high-power SSA is usually composed of multiple power amplifier modules through power combiner nets. When the power amplifier modules with unequal amplitudes and SSA operate under a full reflection caused by arcing of the cavity, the modules may be easily damaged due to excessive reflected power. The optimization of the power combiners is an effective means for improving the stability of SSAs under high power reflection. In this paper, the mechanisms and conditions under which reflection power arises were analyzed by using the scattering parameter of the combiner, and the optimization scheme of the combiner to reduce the maximum reflected power was proposed. In addition, a set of 500 MHz 8-way power combiner experimental facility was designed to verify the result of theoretical calculation under various working conditions. Simulation and experimental results show that the reflected power of the power amplifier module not only is related to the matching state of SSA, but also is related to the output state of the power amplifier module itself and parameters of combiner. The total reflected power of the power amplifier module is the sum of the reflected power from the mismatched load and the combined power from the other modules. When all the power amplifier modules of the SSA working perfectly, the reflected power of its own signal of a module is exactly compensated by the sum of the power with opposite phase from all other modules. In this case, the reflected power of the module is only related to the matching state of the SSA, and its maximum value is equivalent to the rated output power of the module. In another case, when one of the SSA’s power amplifier modules is switched off, the reflected power received by some of the modules may be as high as nearly 4 times the rated power of a single module, which will lead to severe overloading of the circulator loads and risk of damage to the modules. Eventually, by optimizing the parameters of the combiner, the maximum reflection power is effectively reduced due to suppress in-phase superposition of the reflected power coupled form other modules. The experimental results are in good agreement with the theoretical calculations, which proves the effectiveness of the optimization scheme. Therefore, this research can provide some valuable references for the subsequent development of higher power SSA for CSNS, SAPS and other accelerator facilities.

The continuous decline in the birth rate can lead to a series of social and economic problems. Accurately predicting the birth rate of a region will help national and local governments to formulate more scientifically sound development policies. This paper proposes a discrete-aware model BRP-Net based on attention mechanism and LSTM, for effectively predicting the birth rate of prefecture-level cities. BRP-Net is trained using multiple variables related to comprehensive development of prefecture-level cities, covering factors such as economy, education and population structure that can influence the birth rate. Additionally, the comprehensive data of China's prefecture-level cities exhibits strong spatiotemporal specificity. Our model leverages the advantages of attention mechanism to identify the feature correlation and temporal relationships of these multi-variable time series input data. Extensive experimental results demonstrate that the proposed BRP-Net has higher accuracy and better generalization performance compared to other mainstream methods, while being able to adapt to the spatiotemporal specificity of variables between prefecture-level cities. Using BRP-Net to achieve precise and robust prediction estimates of the birth rate in prefecture-level cities can provide more effective decision-making references for local governments to formulate more accurate and reasonable fertility encouragement policies. [ABSTRACT FROM AUTHOR]

Objective. To explore the value of the injury severity score (ISS) and the new injury severity score (NISS) for evaluating injuries and predicting complications (pneumonia and respiratory failure) and poor prognoses (in‐hospital tracheal intubation, extended length of hospital stay, ICU admission, prolonged ICU stay, and death) in patients with thoracic trauma. Methods. The data of consecutive patients with thoracic trauma who were admitted to the department of cardiothoracic surgery of a tertiary hospital between January 2018 and December 2021 were retrospectively collected. ISS and NISS were calculated for each patient. The study outcomes were complications and poor prognoses. The differences in ISS and NISS between patients with complications and poor prognoses and patients without the abovementioned conditions were compared using the Mann‒Whitney U test. Discrimination and calibration of ISS and NISS in predicting outcomes were compared using the area under the receiver operating characteristic (ROC) curve (AUC) and Hosmer‒Lemeshow (H‐L) statistic. Results. A total of 310 patients were included. ISS and NISS of patients with complications and poor prognoses were greater than those of patients without complications and poor prognoses, respectively. The discrimination of ISS in predicting pneumonia, respiratory failure, in‐hospital tracheal intubation, extended length of hospital stay, ICU admission, prolonged ICU stay, and death (AUCs: 0.609, 0.721, 0.848, 0.784, 0.763, 0.716, and 0.804, respectively) was not statistically significantly different from that of NISS in predicting the corresponding outcomes (AUCs: 0.628, 0.712, 0.795, 0.767, 0.750, 0.750, and 0.818, respectively). ISS showed better calibration than NISS for predicting pneumonia, respiratory failure, in‐hospital tracheal intubation, extended length of hospital stay, and ICU admission but worse calibration for predicting prolonged ICU stay and death. Conclusion. ISS and NISS are both suitable for injury evaluation. There was no statistically significant difference in discrimination between ISS and NISS, but they had different calibrations when predicting different outcomes. [ABSTRACT FROM AUTHOR]

In this study, a HfO2 coating was developed on an Ir matrix using a customized open-tube airflow, cold-wall chemical vapor deposition instrument. The preparation process and structure of the as-prepared coating were investigated to gain insights into its characteristics. The HfO2 coating effectively prevents direct contact between Ir and O, leading to a reduction in the oxidation rate of Ir. Furthermore, defects such as micropores and cracks generated during sealed oxidation erosion contribute to Ir's decelerated oxidation failure. The as-prepared HfO2 coating exhibits low thermal conductivity and a high heat radiation rate, reducing the coating's surface temperature. These characteristics significantly enhance adversity tolerance and increase the working temperature of the coating. Moreover, the as-prepared HfO2 coating can serve as a diffusion barrier, blocking both the direct contact of O with the Ir coating and the diffusion of other elements to the Ir coating. As a result, the rates of diffusion of other elements to the Ir coating are reduced. [ABSTRACT FROM AUTHOR]

The corona-generated space charge may vary in different air pressures, and the quantitative law between the corona-generated space charge density and air pressure has never been investigated. This work utilised computational approaches to explore the role of air pressure in the variation of negative corona-generated space charge. A negative fluid model in which the air pressure could be varied was built up to calculate the charged-particle density and electric field under different applied voltages. The continuity equations were solved by flux corrected transport algorithm and the Poisson equation was computed by the successive over relaxation method. The variations of important parameters due to air pressure were analysed. The particles densities of electrons, positive ions and negative ions at standard and low atmosphere pressures were computed, which increased markedly due to the decrease of atmosphere pressure. At fixed applied voltages, the exponential decay law between the maximal values of electron/positive ion densities at the head of the streamer and air pressure could be obtained. The quantitative law between the maximal values of electron/positive ion densities at the head of the streamer and the applied voltage, relative air density was also achieved.