Explore the vast range of titles available.

Stud connectors are widely used to realize the shear connection of steel girders and prefabricated bridge decks in prefabricated steel–concrete composite beams. However, the dense arrangement of stud connectors in the combined bending and shear region makes fabricating prefabricated bridge decks difficult and weakens their integrity. Therefore, a novel prefabricated steel–concrete connector (PSCC) is proposed to accelerate the prefabrication and construction of prefabricated steel–concrete composite bridges. To validate the mechanical properties of PSCC connectors, four groups of 11 static push-out specimens were tested to analyze the effect of interfacial defects and different concrete materials for the shear performance of PSCC connectors. The PSCC connectors have high shear stiffness and ductility. At load levels up to 0.9Pu, the slip values of PSCC connectors range from 6.74 mm to 11.72 mm, which specifies a minimum slip of 6 mm (EC4). The shear capacity of the specimens with 30% and 60% interface defect areas decreased by 0.39% and 8.91%, respectively, compared to the specimens with no interface defects. When the connection layer material was replaced from ordinary concrete to UHPC, the shear capacity of PSCC connectors increased by 39%, and the failure mode shifted from shear failure of studs to shear failure of reinforcements. Moreover, cyclic loading marginally enhanced the shear capacity of PSCC connectors, serving as a safety reserve in practical engineering. Finally, a shear capacity calculation formula for PSCC connectors, derived from finite element analysis and existing formulas, achieved a prediction accuracy within 6.2%.

Background There is still controversy regarding the clinical value and significance of lateral pelvic lymph node (LPN) dissection (LPND). The present study aimed to investigate whether the addition of LPND to total mesorectal excision (TME) confers survival benefits in rectal cancer patients with clinical lateral pelvic node metastasis (LPNM). Methods From January 2015 to January 2021, a total of 141 rectal cancer patients with clinical evidence of LPNM who underwent TME + LPND were retrospectively analysed and divided into the LPNM group ( n  = 29) and the non-LPNM group (n = 112). The LPNM group was further subdivided into a high-risk LPNM group ( n  = 14) and a low-risk LPNM group ( n  = 15). Propensity score matching (PSM) was performed to minimize selection bias. The primary outcomes of this study were 3-year overall survival (OS) and disease-free survival (DFS). Results Of the 141 patients undergoing LPND, the local recurrence rate of patients with LPNM was significantly higher than that of patients without LPNM both before (27.6% vs. 4.5%, P  = 0.001) and after (27.6% vs. 3.4%, P  = 0.025) PSM. Multivariate analysis revealed that LPNM was an independent risk factor for not only OS (HR: 3.06; 95% CI, 1.15–8.17; P  = 0.025) but also DFS (HR: 2.39; 95% CI, 1.18–4.87; P  = 0.016) in patients with LPNM after TME + LPND. When the LPNM group was further subdivided, multivariate logistic regression analysis showed that OS and DFS were significantly better in the low-risk group (obturator/internal iliac artery region and < 2 positive LPNs). Conclusion Even after LPND, LPNM patients have a poor prognosis. Moreover, LPNM is an independent poor prognostic factor affecting OS and DFS after TME + LPND. However, LPND appears to confer survival benefits to specific patients with single LPN involvement in the obturator region or internal iliac vessel region. Furthermore, LPND may have no indication in stage IV patients and should be selected carefully.

To further improve the precision and efficiency of structural health monitoring technology and the theory of large-scale structures, full-field non-contact structural geometry morphology monitoring is expected to be a breakthrough technology in structural safety state monitoring and digital twins, owing to its economic, credible, high frequency, and holographic advantages. This study validates a proposed holographic visual sensor and algorithms in a computer-vision-based full-field non-contact displacement and vibration measurement. Using an automatic camera patrol experimental device, original segmental dynamic and static video monitoring data of a model bridge under various damage/activities were collected. According to the temporal and spatial characteristics of the series data, the holographic geometric morphology tracking algorithm was introduced. Additionally, the feature points set of the structural holography geometry and the holography feature contours were established. Experimental results show that the holographic visual sensor and the proposed algorithms can extract an accurate holographic full-field displacement signal, and factually and sensitively accomplish vibration measurement, while accurately reflecting the real change in structural properties under various damage/action conditions. The proposed method can serve as a foundation for further research on digital twins for large-scale structures, structural condition assessment, and intelligent damage identification.

Urban heat islands are representative problems in urban environments. The impact of spectral indexes on land-surface temperature (LST) under different urban forms, climates, and functions is not fully understood. Local climate zones (LCZs) are used to characterize heterogeneous cities. In this study, we quantified the contribution of three cities to high-temperature zones and surface urban heat island intensity (SUHII) across LCZs and seasons, used Welch and Games–Howell tests to analyze the difference in LST, then described the spatial pattern characteristics of LST, and used a geographically weighted regression model to analyze the relationship between spectral indexes and LST. The results showed that compact midrise, compact low-rise (LCZ 3), large low-rise (LCZ 8), heavy industry (LCZ 10), and bare rock or paved (LCZ E) contributed greatly to high-temperature zones and had strong SUHII. There were 92–98% significant differences between different LCZs. The spatial aggregation of LST gradually weakened with a decrease in temperature. The modified normalized difference water index (MNDWI) in most LCZs of all seasons for Wuhan could reduce LST well, while MNDWI only had cooling effects in winter for Nanjing and Shanghai. Normalized difference vegetation index (NDVI) in most LCZs performed a cooling role during summer and transition seasons (spring and autumn), while it showed a warming effect in winter. The cooling effect of NDVI in open building types was stronger than that of compact building types, while the cooling effect of MNDWI was better in compact building types than in open building types. With the increase of normalized difference built-up index (NDBI), all LCZs showed warming effects, and the magnitude of LST increase varied in different cities and seasons. These results contribute further insight into thermal environment in heterogeneous urban areas.

Epidemiological studies have associated high levels of airborne particulate matter (PM) with increased respiratory diseases. In order to investigate the mechanisms of air pollution-induced lung toxicity in humans, human bronchial epithelial cells (16HBE) were exposed to various concentrations of particles smaller than 2.5 μm (PM2.5) collected from Beijing, China. After observing that PM2.5 decreased cell viability in a dose-dependent manner, we first used Illumina RNA-seq to identify genes and pathways that may contribute to PM2.5-induced toxicity to 16HBE cells. A total of 539 genes, 283 up-regulated and 256 down-regulated, were identified to be significantly differentially expressed after exposure to 25 μg/cm2 PM2.5. PM2.5 induced a large number of genes involved in responses to xenobtiotic stimuli, metabolic response, and inflammatory and immune response pathways such as MAPK signaling and cytokine-cytokine receptor interaction, which might contribute to PM2.5-related pulmonary diseases. We then confirmed our RNA-seq results by qPCR and by analysis of IL-6, CYP1A1, and IL-8 protein expression. Finally, ELISA assay demonstrated a significant association between exposure to PM2.5 and secretion of IL-6. This research provides a new insight into the mechanisms underlying PM2.5-induced respiratory diseases in Beijing.

Urban areas are significant centers of human activity and are recognized as major contributors to global carbon emissions. The establishment of urban green spaces plays a crucial role in enhancing carbon sinks and mitigating carbon emissions, thereby fostering a low-carbon cycle within cities. However, the existing literature on the carbon sequestration of green spaces in Chinese cities often overlooks the role of water bodies, which are a significant characteristic of wetland cities. Therefore, it is necessary to investigate the carbon sequestration potential of green spaces in wetland cities, taking into account the contribution of water bodies to carbon sinks. This study aims to analyze the quantitative structure of urban green spaces through the lens of carbon balance, which can effectively enhance a city’s overall carbon sequestration capacity. Utilizing carbon balance theory, this research first assesses the carbon offsetting capability (COC) of urban green spaces in Wuhan for the year 2019. It then forecasts future carbon emissions, sets improvement targets for COC, and calculates the required area of standard green space to achieve these targets by 2030. A multi-objective programming (MOP) model is developed to identify the optimal solution that aligns with urban development planning constraints while maximizing carbon sinks. Lastly, we analyzed the contribution rates of different types of urban green spaces to the total carbon sequestration capacity of green spaces to clarify the characteristics of carbon absorption in green spaces of Wuhan, a wetland city. The findings indicate the following: (1) In 2019, Wuhan’s carbon emissions from human activities reached approximately 38.20 Mt, with urban green spaces absorbing around 5.62 Mt of carbon, and a COC of about 14.71%. (2) Projections for 2030 suggest that carbon emissions in Wuhan will rise to approximately 42.64 Mt. Depending on the targeted COC improvement rates of 5%, 10%, 15%, 20%, and 25%, the required values of carbon sequestration will be 6.59 Mt, 6.90 Mt, 7.21 Mt, 7.53 Mt and 7.84 Mt, respectively. (3) The results of the MOP model indicate that the optimal COC for 2030 is projected to be 16.33%, which necessitates a carbon sequestration of 6.97 Mt. (4) Water bodies accounted for 56.23% of the total carbon absorption in green spaces in 2019 and are projected to represent 45.37% in 2030, highlighting the distinctive characteristics of Wuhan as a wetland city in terms of its green space carbon sequestrations. The management and enhancement of water body carbon sequestration capacity is crucial for the carbon sequestration potential of urban green space in Wuhan. The results of this study can provide evidence and recommendations for the low-carbon development patterns of wetland cities across China.

Bridge displacement is an important part of safety evaluations. Currently, bridge displacement monitoring uses only a few measurement points, making it difficult to evaluate safety. To address this problem, we propose a multi-point displacement synchronous monitoring method. The structural surface has abundant natural texture features, so we use the feature points of the structural surface as the displacement measurement points and propose a feature point displacement calculation method. Furthermore, we conduct experiments on a beam in the laboratory and obtain the beam’s multi-point displacement monitoring results. The monitoring results show that the displacement of some feature points is mismatched. We propose the use of the structural deflection curve to eliminate the feature point displacement mismatches. This method uses the maximum rotation angle of the deflection curve to eliminate displacement mismatches. The results indicate that it is effective to eliminate displacement mismatches in simple structures, such as simply supported beams. Finally, we obtain the test beam’s multi-point displacement synchronous monitoring results. Compared with the 3D laser scanning measurement method, the maximum error of the monitoring results is 8.70%. Research shows that the main reason for the monitoring error is image noise, and the noise interference problem due to its application in practical bridges requires further investigation. Compared with traditional displacement monitoring, this method has significant economic, efficiency, and data integrity advantages. The method has application prospects for multi-point displacement monitoring of simple structures, such as simply supported beams.

Due to the slender geometry and low-amplitude vibrations of stayed cables, existing vision-based methods often fail to accurately identify their full-field dynamic parameters, especially the higher-order modes. This paper proposes a novel holographic vision-based method to accurately identify the high-order full-field dynamic parameters and estimate the tension of the stayed cables. Particularly, a full-field optical flow tracking algorithm is proposed to obtain the full-field dynamic displacement information of the stayed cable by tracking the changes in the optical flow field of the continuous motion signal spectral components of holographic feature points. Frequency-domain analysis is applied to extract the natural frequencies and damping ratios, and the vibration frequency method is used to estimate the tension. Additionally, an Eulerian-based amplification algorithm—holographic feature point video magnification (HFPVM)—is proposed for enhancing weak visual motion signals of the stayed cables, so that the morphological motion information of the stayed cables can be visualized. The effectiveness of the proposed method has been validated through experiments on the stayed cable models. Compared with the results obtained using contact sensors, the proposed holographic vision-based method can accurately identify the first five natural frequencies with overall errors below 5% and a maximum deviation of 6.86% in cable tension estimation. The first three normalized holographic mode shapes and dynamic displacement vectors are successfully identified, with the MAC value reaching up to 99.51%. This entirely non-contact vision-based method offers a convenient and low-cost approach for cable tension estimation, and this is also the first study to propose a comprehensive, visual, and quantifiable strategy for periodic or long-term monitoring of cable-supported structures, highlighting its strong potential in practical applications.

Background Colorectal cancer is common in elderly patients. Laparoscopy is widely used to approach this kind of disease. This study was to examine short-term outcomes and long-term survival for laparoscopic and open surgery in elderly patients with colorectal cancer. Methods From January 2007 to December 2018, patients with colorectal cancer older than 80 operated at China National Cancer Center were included in the study. Propensity score matching (PSM) was used to minimize the adverse effects. The clinical data between open and laparoscopic surgery was compared, and the effect of factors on overall survival (OS) and disease-free survival (DFS) was analyzed by Cox proportional hazard model. Results Ninety-three pairs were selected after PSM. Patients in laparoscopic group had less intraoperative blood loss, postoperative complications, time to first flatus, time to oral feeding, postoperative hospital stay, and higher retrieved lymph node ( P  < 0.05). The OS and DFS rates were similar ( P  > 0.05), besides the CEA level, III/IV stage, and perineural invasion were independent predictors of survival ( P  < 0.05). Conclusion In elderly patients with colorectal cancer, laparoscopic surgery had better short-term outcomes than open surgery. CEA level, III/IV stage, and perineural invasion were reliable predictors for OS and DFS.

Background Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are effective routine treatments for colorectal peritoneal metastasis (PM). However, the safety and efficacy of neoadjuvant chemotherapy (NAC) before CRS+HIPEC are poorly understood. Therefore, this study aimed to assess the perioperative safety and long-term efficacy of NAC prior to CRS+HIPEC for patients with synchronous colorectal PM. Methods Patients with synchronous colorectal PM who received NAC prior to CRS+HIPEC were systematically reviewed at the China National Cancer Center and Huanxing Cancer Hospital from June 2017 to June 2019. The clinicopathologic characteristics, perioperative parameters, and survival rates of patients who underwent CRS+HIPEC with NAC (NAC group) and patients who underwent CRS+HIPEC without NAC (non-NAC group) were compared. Results The study enrolled 52 patients, with 20 patients in the NAC group and 32 in the non-NAC group. In the NAC group, the proportion of patients with a peritoneal carcinomatosis index (PCI) score < 12 was significantly higher than that in the non-NAC group (80.0% vs 50.0%, P = 0.031), and more patients achieved complete cytoreduction (80.0% vs 46.9%, P = 0.018). The two groups had comparable grade III/IV complications and similar reoperation and mortality rates ( P > 0.05). However, patients who received NAC had lower platelet counts (151.9 vs 197.7 × 10 9 /L, P = 0.036) and neutrophil counts (4.7 vs 7.2 × 10 9 /L, P = 0.030) on postoperative day 1. More patients survived for 2 years in the NAC group than in the non-NAC group (67.4% vs 32.2%, respectively, P = 0.044). However, the completeness of cytoreduction score (HR, 2.99; 95% CI, 1.14–7.84; P = 0.026), rather than NAC, was independently associated with overall survival (OS) in the multivariate analysis after controlling for confounding factors. Conclusion NAC administration before CRS+HIPEC can be regarded as safe and feasible for patients with colorectal PM with comparably low mortality rates and acceptable morbidity rates. Nevertheless, large-sample randomized controlled studies are needed to confirm whether the administration of NAC before CRS+HIPEC confers a survival benefit to patients.