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Bolt support ability is one of the bottleneck problems that restrict the speed and safety of roadway excavation, as well as the development of unmanned and intelligent roadway excavation. Anchor drilling robot is the only way to solve the problem of bolting, its core part is automatic bolting frame. In order to systematically sort out the technology roadmap of automatic bolting frame and summarize the common structure of key components, the paper introduces the characteristics, technical level and applicable working conditions of automatic bolting frame at home and abroad, and the research emphases and development direction of automatic bolting frame technology are pointed out. Firstly, in terms of layout,the foreign automatic bolting frame is divided into turret, switching and self-drilling, the drilling power,rotary torque, bolt storage quantity and performance characteristics of bolting frame are introduced in detail; and on that basis,the layout and performance parameters of domestic automatic bolting frame are summarize; the disadvantages of domestic automatic bolting frames are compared from two aspects of function and driving element quantity. Secondly, the types of each component of automatic bolting frame structure are systematically described: drilling, anchoring agent injecting, bolting, bolt cartridge, the working principles and structural characteristics of each component are described. Finally, based on the comparative analysis of the domestic and international automatic bolting frame, the development ideas and research directions of automatic bolting frame are put forward according to the status of bolting technology in coal mine roadway in China: study on sensor and driving element of automatic bolting frame; study on automatic bolting frame intelligent control technology; study on applicability of automatic bolting frame and drilling tool; study on modularization and serialization of automatic bolting frame, etc. Development of automatic bolting frame technology will be help drilling, resin injecting, bolting collaborative operation, achieve mechanical automatic bolting, and ultimately achieve the goal of intelligent and unmanned coal mine roadway heading face.

In the operation of bolter miners, the cutting arm is an essential and weak part and its fatigue life directly affects its performance. This study aimed to investigate the influence of the cutting head load on the fatigue life of a cutting arm using the DEM-MFBD (Discrete Element Method-Multi Flexible Body Dynamics) bi-directional coupling technique. The EJM340 bolter miner was chosen as the research object, and a three-dimensional solid model of the bolter miner was built using the RecurDyn software. The cutting arm was flexibly modelled, and the tunnel model was built using the EDEM software. The motion parameters of the bolter miner and cutting head load were transferred through the bi-directional coupling interface to obtain the loads and stress parameters during the entire tunnel cutting process. Based on the stress-time variation, the fatigue life of the cutting arm was calculated, the overall damage and crack initiation locations were obtained, and the minimum number of cutting arm cycles was determined. The accuracy of the virtual model is verified through field experiments. The analysis results indicated that the crack emergence location and fatigue life obtained from the simulation were in agreement with the experimental results.

Aims Left atrial appendage electrical isolation (LAAEI) has demonstrated a significant enhancement in the success rate of atrial fibrillation (AF) ablation. Nevertheless, concerns persist about the safety of LAAEI, particularly regarding alterations in left atrial appendage (LAA) flow velocity and the potential risks of thrombus. This study aimed to assess the efficacy and safety of LAAEI, investigating changes in LAA flow velocity in canines. Methods and results The study comprised a total of 10 canines. The LAAEI procedure used by a 23 mm cryoballoon of the second generation was conducted at least 180 s. Intracardiac ultrasonography (ICE) was employed to quantify the velocity flow of the LAA both prior to and following LAAEI. Following a 3-month period, subsequent evaluations were performed to assess the LAA velocity flow and the potential reconnection. Histopathological examination was conducted. Left atrial appendage electrical isolation was effectively accomplished in all canines, resulting in a 100% acute success rate (10/10). The flow velocity in the LAA showed a notable reduction during LAAEI as compared with the values before the ablation procedure (53.12 ± 5.89 vs. 42.01 ± 9.22 cm/s, P = 0.007). After the follow-up, reconnection was observed in four canines, leading to a success rate of LAAEI of 60% (6/10). The flow velocity in the LAA was consistently lower (53.12 ± 5.89 vs. 44.33 ± 10.49 cm/s, P = 0.006), and no blood clot development was observed. The histopathological study indicated that there was consistent and complete injury to the LAA, affecting all layers of its wall. The injured tissue was subsequently replaced by fibrous tissue. Conclusion The feasibility of using cryoballoon ablation for LAAEI was confirmed in canines, leading to a significant reduction of LAA flow velocity after ablation. Some restoration of LAA flow velocity after ablation may be linked to the passive movement of the LAA and potential reconnecting. However, this conclusion is limited to animal study; more clinical data are needed to further illustrate the safety and accessibility of LAAEI in humans. [ABSTRACT FROM AUTHOR]

Highwall mining is a method that involves using a continuous highwall miner system (CHM) to extract coal from the remaining coal seams, which has proven to be an effective and safe method for extracting coal after open-pit mining. However, application cases globally have shown that the feasibility of highwall mining in open-pit coal mines is subject to geological conditions, mining techniques, and other factors. If application conditions are not suitable, equipment may be trapped under collapsed coal–rock masses and unable to be retrieved, resulting in severe safety issues for slope stability. To meet the real-world demand for extracting the remaining coal in open-pit coal mines in China, it is urgent to conduct a feasibility evaluation of highwall mining in these areas. This paper establishes a mathematical evaluation framework for assessing the feasibility of highwall mining by summarizing a large number of engineering application cases globally and analyzing various technical characteristics such as geological deposit conditions, mining techniques, and technical equipment. The analytic hierarchy process (AHP), fuzzy comprehensive evaluation (FCE) and variable weight theory (VWT) are utilized in conjunction to form this framework, which includes four secondary indicators: geological deposit factors, mining technique factors, safety impact factors, and economic evaluation factors, and 20 tertiary sub-indicators, along with their corresponding characteristic values. The feasibility sub-set is divided into four categories: infeasible, basically feasible, relatively feasible, and highly feasible, and the values of the sub-indicators strictly follow and represent these four levels of feasibility. Weight vectors for the sub-indicators are obtained through a judgment matrix established within the mathematical evaluation framework. The fuzzy relationship matrix of the sub-indicators is constructed using fuzzy mathematical membership functions, and the final feasibility evaluation is determined through two-level comprehensive evaluation. The accuracy of the model is verified using the characteristic parameters of open-pit coal mines under two different conditions (JZT coal mine in Inner Mongolia, China, and GC coal mine in Australia). The results demonstrate that the maximum evaluation membership degree for the JZT mine is 0.7113, belonging to the "highly feasible" level, while the GC mine is 0.3304, belonging to the "basically feasible" level, which aligns well with real-world usage, proving that the evaluation model can effectively reveal the performance and membership degree of each indicator in different application cases. By quantitatively characterizing the feasibility level of highwall mining technology under different application conditions, this evaluation model can provide scientific guidance for coal mining enterprises to introduce CHM for highwall mining operation in open-pit coal mines. [ABSTRACT FROM AUTHOR]

Early diagnosis of gastrointestinal malignancies in patients with acute coronary syndrome (ACS) is often delayed. The present study aims to demonstrate the value of [68Ga]Ga‐FAPI‐04 PET imaging in ACS with suspected gastrointestinal malignancies. Twelve ACS patients with suspected gastrointestinal malignancies were enrolled, including ST‐elevation myocardial infarction (STEMI) (n = 5), non‐ST‐elevation myocardial infarction (NSTEMI) (n = 5), and unstable angina (UA) (n = 2). All patients underwent coronary angiography (CAG) and [68Ga]Ga‐FAPI‐04 PET/MR or PET/CT within 1 week. All five STEMI and five NSTEMI patients had high [68Ga]Ga‐FAPI‐04 uptake in the injured myocardium compared to remote area (TBR: 2.10 ± 0.72 vs. 0.62 ± 013; p <.001), correlated with peak cTnI level (R =.82, p =.004). No [68Ga]Ga‐FAPI‐04 in the myocardium was found in UA patients. NSTEMI displayed a similar myocardial [68Ga]Ga‐FAPI‐04 intensity as STEMI (p =.42). Compared with STEMI, NSTEMI patients had a significantly delayed door‐to‐balloon time for reperfusion treatment (p =.023). High uptake of [68Ga]Ga‐FAPI‐04 in the gastrointestinal tract was detected in three patients. Because of no myocardial [68Ga]Ga‐FAPI‐04 expression, they discontinued antiplatelet therapy and underwent endoscopy. The rectal, colon, and gastric cancer diagnoses were made by biopsy. The other nine patients showed no accumulation of [68Ga]Ga‐FAPI‐04 beyond the heart, and invasive tumor examinations were delayed. During a median 6‐month follow‐up, no tumor formation was observed. [68Ga]Ga‐FAPI‐04 PET imaging is valuable to assess injured myocardium, detect tumors, and guide invasive examinations in ACS patients with suspected gastrointestinal malignancies. [ABSTRACT FROM AUTHOR]

The bolter miner is a critical piece of equipment in the rapid set of tunneling equipment, and the load generated during coal cutting may lead to excessive vibration of the equipment and reduce its reliability. In order to reduce the vibration response of the bolter miner, this paper proposes the installation of a dynamic vibration absorber (DVA) inside the cutting arm of the bolter miner. A five-degree-of-freedom dynamics model was developed, and the cutting part was regarded as two rigid bodies flexibly connected by a rotating spring. The model's accuracy was verified based on the field test results, and the error was within 7%. It was found that the cutting caused the first-order modal vibration, and the DVA was placed in the cavity of the cutting arm to control the modal vibration of this order. To minimize the vibration, a coupled dynamics model between the DVA and bolter miner was developed, and the DVA parameters were optimized. The results showed that the acceleration RMS and peak values of the cutting part were reduced by 12% and 30.1%, respectively; the acceleration RMS and peak values of the main frame were reduced by 6.5% and 17%, respectively, and the fatigue life of the cutting arm was increased by 34.2%. [ABSTRACT FROM AUTHOR]

Aims  Data regarding the relationship between carotid plaque length (CPL) and coronary artery disease (CAD) are lacking. This study aimed to assess the predictive value of CPL for the severity of CAD. Methods and results We prospectively enrolled 2149 consecutive patients who underwent both first coronary angiography and carotid ultrasonography with measurements of intima-media thickness (IMT), plaque score (PS), and CPL. In total, 1408 (65.5%) patients had CAD (defined as stenosis ≥50%), and 741 (34.5%) patients had no CAD. Patients with CAD had longer maximal CPL than those without CAD (P  <   0.001). The severity of CAD, measured by the Gensini score (GS), was closely correlated with max-CPL (r s = 0.560), followed by PS (r s = 0.486) and mean-IMT (r s = 0.292). Multivariate analysis revealed that max-CPL remained independently associated with CAD and high-GS after adjustment for traditional risk factors (TRF). Max-CPL, compared with PS or mean-IMT, had significantly higher discrimination value for predicting high-GS [area under the curve (AUC) 0.819 vs. 0.769 vs. 0.634, P  <   0.001]. At a cut-off value for the max-CPL of 6.3 mm, the sensitivity and negative predictive value for high-GS were 84.6% and 89.1%, respectively. Furthermore, the addition of max-CPL significantly improved the discrimination (AUC 0.832 vs. 0.720, P  <   0.001) and reclassification (net reclassification improvement = 0.431, P  <   0.001) over TRF for high-GS. Conclusion  Ultrasound max-CPL provides independent and incremental predictive value for the clinical severity of CAD over TRF and seems a simple useful marker in CAD risk stratification. [ABSTRACT FROM AUTHOR]