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In this study, some loading experiments were conducted on coal specimens using the established weak current testing system to investigate the effects of weak currents in coals. The response characteristics of weak currents during the coal deformation process were analyzed, and a quantitative relationship between weak currents and the mechanical behaviors of coal was established. The principles for predicting coal and rock dynamic disasters based on the weak current method were proposed. Furthermore, drawing upon the results obtained from on-site practical applications, a forward-looking assessment of the potential applications of this methodology is presented. The results indicate that the deformation of loaded coal generates weak currents. The fluctuations in these weak currents exhibit a notable alignment with variations in stress, with the magnitude closely tied to the coal mechanical characteristics like stress, strain, and strain rate. Notably, in the compaction and plastic deformation stages, the weak current rises in tandem with the strain rate, while in the elastic deformation stage, the weak current exhibits a linear increase in correlation with stress and strain. Under perturbation loading, the coal produces some periodic weak currents, referred to as the pulsating direct current (PDC). And the variations in the PDC align with stress changes. Furthermore, the weak current demonstrates a reliable precursor response to coal damage, with some unusual fluctuations observed during the accelerated increase process (plastic deformation stage) serving as the precursor indicators for the progressive failure of coal. Conversely, the pulse-like fluctuations observed during the attenuation process can be regarded as the precursor features for the coal's creep failure. The phenomenon of weak currents in stressed coal serves as a pivotal foundation for conducting weak current measurements in mines. The intimate correlation between weak currents and the mechanical behaviors of coal underscores a crucial prerequisite for employing the weak current technology in monitoring stress within coal and rock formations. Furthermore, the discernible precursor response of weak currents to coal damage provides a vital assurance for predicting coal and rock dynamic disasters through the utilization of weak current technology. The weak current technology possesses some advantages such as high responsiveness, clear precursor signals, and robust anti-interference capabilities. These attributes make it highly promising for some applications in the stress monitoring within coal/rock mass and the early warning for coal and rock dynamic disasters. In the future, some further researches on the fundamental theory and applied technology of weak current in stressed coal and rock are needed to provide a support for the development of precise spatiotemporal monitoring and early warning of coal rock dynamic disasters using the weak current methods.

Meta-instability stage is the most abundant precursory information and the most intense change stage in the process of fault stick-slip instability. In order to deeply explore the characteristics of coal meta-instability and the response law of acoustic and electrical signals in this process, the uniaxial graded loading experiments of coal samples with different prefabricated crack angles were carried out. The internal fracture source location, surface displacement field, acoustic emission and electromagnetic radiation signals of the samples were synchronously collected, and the mechanical behavior and acoustic and electrical characteristics of coal meta-instability were analyzed. The results show that: ① The inclination angle of the prefabricated crack significantly affects the internal stress distribution of the loaded coal sample, and even the expansion distribution of the new cracks in the meta-instability stage. The acoustic emission count and energy have obvious responses to stress and failure. When the meta-instability is near, the acoustic emission count and energy increase sharply at the same time, and the signal proportion is close to 20%. The response characteristics can be used as the basis for judging the crack coal sample entering the meta-instability stage. ② After entering the meta-instability state, the electromagnetic radiation activity is the most intense, which is almost consistent with the occurrence time of stress drop. Before the main fracture occurs, the energy and amplitude of electromagnetic radiation increase sharply, and the peak energy increases first and then decreases with the increase of crack dip angle. When the crack dip angle is 45°, the electromagnetic radiation count accounts for the largest proportion of the total instability process. ③ The fracture profile of the coal sample in the meta-instability stage has been basically formed. The inclination angle of the prefabricated crack has a significant impact on the duration of the meta-instability stage of the coal sample. When the inclination angle is 45°, the duration of the meta-instability stage is the longest, and when the inclination angle is 60°, the duration proportion is the shortest. The research results can be used to formulate the monitoring scheme of fault meta-instability, and the evolution and disaster of large-scale rock burst in fault structural area

Efficient and accurate classification of the microseismic data obtained in coal mine production is of great significance for the guidance of coal mine production safety, disaster prevention and early warning. In the early stage, the classification of microseismic events relies on human experiences, which is not only inefficient but also often causes some misclassifications. In recent years, the neural network-based classification method has become more favored by people because of its advantages in modeling procedures. A microseismic signal is a kind of time-series signal and the application of the classification method is widely optimistic. The number and the balance of the training data samples have an important impact on the accuracy of the classification result. However, the quality of the training data set obtained from the production cannot be guaranteed. A long short-term memory (LSTM) network can analyze the time-series input data, where the image classification at the pixel level can be achieved by the fully convolutional network (FCN). The two structures in the network can not only use the advantages of the FCN for extracting signal details but also use the characteristics of LSTM for conveying and expressing the long time-series information effectively. In this paper, a time-series data enhancement combination process is proposed for the actual poor microseismic data. A hybrid FCN-LSTM network structure was built, the optimal network parameters were obtained by experiments, and finally a reasonable microseismic data classifier was obtained.

In terms of coal’s stability and failure, soaking time and water content play a significant role in geotechnical engineering practice. To determine the soaking time effect on the mechanical behavior of coal samples and the response of AE (acoustic emission) signal throughout loading, the samples with different soaking times (0–120 hours (h)) were prepared and tested under uniaxial compression. AE signals were continuously monitored during loading to examine the AE characteristic response via the AEwin Express-8.0 system. The results revealed that the mechanical characteristics of the coal samples decreased with an increase in soaking time. When coal samples were subjected to uniaxial compression, AE events occurred due to the formation of the cracks, which further propagated to cause coal fracture. AE counts and the accumulative counts fluctuated with time and corresponded very well to the load. Therefore, AE counts and the trend of the accumulative counts of AE qualitatively explained the rupture of the coal under stress. In addition, the variation in trends of AE counts, AE accumulative counts, and load with time at various phases of all samples were obtained. It is concluded that AE counts increase suddenly during a slow increase phase and peak at the active increase phase. During the attenuation phase, the AE counts first decrease significantly with stress drop, but also a slight increase was observed due to the initiation of secondary cracks. These research results are of great significance as a precursor in coal and rock failure.

Isothermal titration calorimetry (ITC) is the gold standard for accurate measurement of thermodynamic parameters in solution reactions. In the data processing of ITC, the non-constant variance of the heat requires special consideration. The variance function approach has been successfully applied in previous studies, but is found to fail under certain conditions in this work. Here, an explicit ITC measurement model consisting of main thermal effects and error components has been proposed to quantitatively evaluate and predict the non-constant variance of the heat data under various conditions. Monte Carlo simulation shows that the ITC measurement model provides higher accuracy and flexibility than variance function in high c-value reactions or with additional error components, for example, originated from the fluctuation of the concentrations or other properties of the solutions. The experimental design of basic error evaluation is optimized accordingly and verified by both Monte Carlo simulation and experiments. An easy-to-run Python source code is provided to illustrate the establishment of the ITC measurement model and the estimation of heat variances. The accurate and reliable non-constant variance of heat is helpful to the application of weighted least squares regression, the proper evaluation or selection of the reaction model.

The acoustic emission (AE) and ultrasonic (UT) simultaneous monitoring program is designed using concrete samples under step loading. The time-varying response characteristics of AE-UT are studied and the cross-correlation analysis between AE-UT parameters is obtained. Moreover, the joint response of UT-AE spatial distribution field is analyzed, and an AE-UT joint monitoring method to detect early-warning signals of a rockburst disaster in a coal seam is proposed. The results show the following. (1) During the loading process, the AE pulses/energy and UT attenuation coefficient first slowly decrease and then increase steadily and finally rapidly increase, while the UT velocity shows a trend of first gradually increasing and then slowly decreasing and finally a sharp decline. (2) AE pulses and energy are significantly or highly correlated with the UT velocity and attenuation coefficient. The AE energy and UT attenuation coefficient can better characterize the damage evolution of concrete under step loading. (3) The UT field evolves ahead of the rupture on the surface, and the long/narrow strip distribution region of UT parameters is consistent with the future failure zone; meanwhile, the AE events can visually reflect the evolution path of internal damage as well as the dynamic migration mechanism of UT field.

In order to study the mechanics and acoustic emission (AE) characteristics of fractured rock under water-rock interaction, dried and saturated sandstone samples with prefabricated double parallel cracks were prepared. Then, uniaxial compression experiments were performed to obtain their AE signals and crack propagation images. The results show that water reduces the strength and fracture toughness of fractured sandstone and enhances plasticity. After saturation, the samples start to crack earlier; the cracks grow slowly; the failure mode is transformed from shear failure along the prefabricated cracks to combined shear and tensile failure; more secondary cracks are produced. The saturated samples release less elastic energy and weaker AE signals in the whole failure process. However, their AE precursor information is more obvious and advanced, and their AE sources are more widely distributed. Compared with dry specimens, the AE frequencies of saturated specimens in the early stage of loading are distributed in a lower frequency domain. Besides, the saturated samples release less complex AE signals which are dominated by small-scale signals with weaker multi-fractal characteristics. After discussion and analysis, it is pointed out that this may be because water makes rock prone to inter-granular fracture rather than trans-granular fracture. The water lubrication also may reduce the amplitude of middle-frequency band signals produced by the friction on the fracture surface. Multi-fractal parameters can provide more abundant precursory information for rock fracture. This is of great significance to the stability of water-bearing fractured rock mass and its monitoring, and is conducive to the safe exploitation of deep energy.

Objective: To explore the reduction effect for the indoor 222Rn (Rn) by Fresh Air Ventilation (FAV) system, a novel commercial ventilation device in China. Methods: The indoor concentrations of Rn and its decay products (RnD) in three residential rooms, two in Beijing and one in Hefei city, Anhui province, before and after FAVS functioned were measured using an active continuous method. The air exchange rate was monitored by measuring CO2 concentration using the tracer gas method. Results: In the three rooms, the FAVS reduced the Rn concentrations from (162 ​± ​80) Bq/m3 to (63 ​± ​22) Bq/m3 and decreased the RnD concentrations from (64 ​± ​35) Bq/m3 to (13 ​± ​6) Bq/m3 on average, a decrease of (59 ​± ​25)% in the Rn concentrations and a drop of (77 ​± ​18)% in the RnD concentrations. Considering dose conversion factors of Rn and RnD, FAVS decreased the exposure dose by (76 ​± ​20)%. Besides, FAVS increased the air exchange rates from 0.17 h−1 to 0.56 h−1 on average. Conclusions: FAVS can effectively reduce indoor Rn and RnD concentrations by improving the air exchange, serving as a valuable supplement to existing radon mitigation methods, especially in extreme climates.

Abstract. Background:. Red-cell transfusion is critical for surgery during the peri-operative period; however, the transfusion threshold remains controversial mainly owing to the diversity among patients. The patient's medical status should be evaluated before making a transfusion decision. Herein, we developed an individualized transfusion strategy using the West-China-Liu's Score based on the physiology of oxygen delivery/consumption balance and designed an open-label, multicenter, randomized clinical trial to verify whether it reduced red cell requirement as compared with that associated with restrictive and liberal strategies safely and effectively, providing valid evidence for peri-operative transfusion. Methods:. Patients aged >14 years undergoing elective non-cardiac surgery with estimated blood loss > 1000 mL or 20% blood volume and hemoglobin concentration

This article reports on an open-source ontology that has been developed to establish an industry-wide consensus on wind lidar concepts and terminology. The article provides an introduction to wind lidar ontology, provides an overview of its development, and provides a summary of its aims and achievements. The ontology serves both reference and educational purposes for wind energy applications and lidar technology. The article provides an overview of the creation process, the outcomes of the project, and the proposed uses of the ontology. The ontology is available online and provides standardisation of terminology within the lidar knowledge domain. The open-source framework provides the basis for information sharing and integration within remote sensing science and fields of application.

Abstract A single‐device method is reported for extracting gate‐ and/or drain‐voltage‐dependent contact resistance of thin‐film transistors (TFTs). An extended transition‐voltage method is proposed and verified by experiments of all‐carbon‐nanotube thin‐film transistors (ACNT‐TFTs), which can extract gate‐ and/or drain‐voltage‐dependent contact resistance at source and drain independently. By measuring the output and transfer characteristics of a single‐device and extracting the basic parameters with the aid of mature Y‐function method, the contact resistance can be calculated directly. The results show that although a slight Schottky contact behavior is exhibited at very small drain voltages, good electrical contact characteristics can still be obtained in ACNT‐TFTs, exhibiting quasi‐Ohmic contacts. Compared with the existing single‐device methods, this method is suitable for both Ohmic and Schottky contact scenarios without requiring a complex iteration process, which greatly improves the universality and efficiency of the contact resistance extraction. Besides, this method reveals the physical essence of the complex interface contacts and enables researchers to quantitatively analyze the contact performance, not only for network carbon nanotube TFTs but also for the other emerging transistors.

Dielectric analysis (DEA) is an effective method for monitoring the curing process of epoxy resin (EP) in situ, but the influence of curing temperature on the measurement results limits the application of DEA in curing process monitoring with variable temperature. In this study, the theoretical basis of using the glass transition as a bridge and monitoring the curing degree by ionic conductivity was analyzed. DEA experiments and differential scanning calorimeter (DSC) experiments were carried out and the mathematical model of ionic conductivity, glass transition temperature, and curing degree of the EP established. The parameters in the model were only related to the composition of EP system in the model as verified for implementing curing-degree monitoring of the EP system cured at variable temperature. The FT-IR spectra measurement was carried out and the activation energy of curing reaction was calculated by results of DEA and DSC, which verified the reliability and scientificity of the method. The method of using glass transition as a bridge can monitor the curing degree in the curing process with variable temperature and extends DEA to the monitoring of this process under variable temperatures.

Abstract Background The incidence of adverse perioperative outcomes in surgery for femoral fractures is high and associated with malnutrition. Here, we identified independent factors and assessed the predictive value of the prognostic nutritional index (PNI) for perioperative adverse outcomes in patients with femoral fractures. Methods This retrospective study included 343 patients who underwent surgery for a single femur fracture. Demographic characteristics, surgery and anaesthesia records and blood test results at admission, 1 day postoperatively and before discharge were evaluated using logistic regression analysis. The discriminatory ability of the independent factors was assessed using the receiver operating characteristic curve analysis, and DeLong’s test was used to compare the area under the curve (AUC). Results Overall, 159 patients (46.4%) experienced adverse perioperative outcomes. Amongst these, 123 (35.9%) had lower limb vein thrombus, 68 (19.8%) had hospital-acquired pneumonia, 6 (1.7%) were transferred to the postoperative intensive care unit, 4 (1.2%) had pulmonary embolism, 3 (0.9%) died during hospitalisation and 9 (2.6%) had other adverse outcomes, including incision disunion, renal and liver function impairment, acute heart failure, acute cerebral infarction and stress gastroenteritis. The PNI at admission, age, postoperative hospital stay, time to admission, hypertension, combined injures and surgery type were independent factors for adverse perioperative outcomes. Based on the AUC (PNI at admission: 0.772 [0.723–0.821], P < 0.001; age: 0.678 [0.622–0.734], P < 0.001; postoperative hospital stay: 0.608 [0.548–0.668], P = 0.001; time to admission: 0.585 [0.525–0.646], P = 0.006), the PNI at admission had optimal discrimination ability, indicating its superiority over other independent factors (age vs. PNI at admission, P = 0.002; postoperative hospital stay vs. PNI at admission, P < 0.001; time to admission vs. PNI at admission, P < 0.001). Conclusions Patients with femoral fractures require a nutritional assessment and appropriate nutritional intervention at admission, and that the PNI value at admission may be a good nutritional assessment indicator.

BackgroundEpidural nerve block and analgesia are basic anesthetic techniques for anesthesia. Epidural catheter rupture and partial retention are adverse events and rare complications of epidural catheterization technique. The probability of occurrence when applied by novice doctors is high. Removal of the residual catheter by conventional surgery causes more trauma and bleeding, slows recovery, and may causes medical disputes. We hypothesized that percutaneous spinal endoscopy a safe and effective remediation technique. This study was to analyze the efficacy and safety of removing the residual dural catheter by a percutaneous full-endoscopic technique(PFET) and discuss the clinical technique and precautions.MethodsThis was a retrospective analysis of 7 patients with ruptured epidural catheters treated in our department from October 2015 to October 2019 using the PFET to remove the remaining epidural catheter. The operation time, intraoperative bleeding volume, surgical complications, and neurological symptoms before and after surgery were recorded. The Self-Rating Anxiety Scale (SAS) was used to assess the anxiety level of the anesthesiologist and the patient before and after the catheter removal operation, and the postoperative low back pain VAS score was recorded.ResultsThe remaining epidural catheter was successfully removed from all 7 patients. The operation time was 54.14 ± 14.45 (32–78) minutes, and the intraoperative blood loss was 9.134 ± 3.078 (5–15) ml. There were no cases of dural damage, cerebrospinal fluid leakage, sensorimotor dysfunction of the lower limbs, or bowel dysfunction. The anxiety symptoms of the patient and the anesthesiologist disappeared after removal of the residual epidural catheter. The patients' postoperative back pain VAS score was 0 to 2 points.ConclusionPFET is a safe and effective minimally invasive technique for removing residual epidural catheters. It causes less trauma and less bleeding, allows a faster recovery. It does not affect the recovery of patients from other surgical operations and reduces both medical risks and medical costs. At the same time, it avoids or reduces the occurrence of medical disputes and eliminates the pressure on novice anesthesiologists regarding similar adverse events.

Abstract We describe here a CRISPR simultaneous and wide-editing induced by a single system (SWISS), in which RNA aptamers engineered in crRNA scaffold recruit their cognate binding proteins fused with cytidine deaminase and adenosine deaminase to Cas9 nickase target sites to generate multiplexed base editing. By using paired sgRNAs, SWISS can produce insertions/deletions in addition to base editing. Rice mutants are generated using the SWISS system with efficiencies of cytosine conversion of 25.5%, adenine conversion of 16.4%, indels of 52.7%, and simultaneous triple mutations of 7.3%. The SWISS system provides a powerful tool for multi-functional genome editing in plants.

A net-like nanostructure of silicon named silicon nanonet was designed and oxygen atoms were used to passivate the dangling bonds. First-principles calculation based on density functional theory with the generalized gradient approximation (GGA) were carried out to investigate the energy band gap structure of this special structure. The calculation results show that the indirect–direct band gap transition occurs when the nanonets are properly designed. This band gap transition is dominated by the passivation bonds, porosities as well as pore array distributions. It is also proved that Si–O–Si is an effective passivation bond which can change the band gap structure of the nanonets. These results provide another way to achieve a practical silicon-based light source. [ABSTRACT FROM AUTHOR]

Cotton fiber quality traits are controlled by multiple quantitative trait loci (QTL), and the improvement of these traits requires extensive germplasm. Herein, an Upland cotton cultivar from America, Acala Maxxa, was crossed with a local high fiber quality cultivar, Yumian 1, and 180 recombinant inbred lines (RILs) were obtained. In order to dissect the genetic basis of fiber quality differences between these parents, a genetic map containing 12116 SNP markers was constructed using the CottonSNP80K assay, which covered 3741.81 cM with an average distance of 0.31 cM between markers. Based on the genetic map and growouts in three environments, we detected a total of 104 QTL controlling fiber quality traits. Among these QTL, 25 were detected in all three environments and 35 in two environments. Meanwhile, 19 QTL clusters were also identified, and nine contained at least one stable QTL (detected in three environments for a given trait). These stable QTL or QTL clusters are priorities for fine mapping, identifying candidate genes, elaborating molecular mechanisms of fiber development, and application in cotton breeding programs by marker-assisted selection (MAS).

This paper presents a reinforcement learning (RL)–based energy management strategy for a hybrid electric tracked vehicle. A control-oriented model of the powertrain and vehicle dynamics is first established. According to the sample information of the experimental driving schedule, statistical characteristics at various velocities are determined by extracting the transition probability matrix of the power request. Two RL-based algorithms, namely Q-learning and Dyna algorithms, are applied to generate optimal control solutions. The two algorithms are simulated on the same driving schedule, and the simulation results are compared to clarify the merits and demerits of these algorithms. Although the Q-learning algorithm is faster (3 h) than the Dyna algorithm (7 h), its fuel consumption is 1.7% higher than that of the Dyna algorithm. Furthermore, the Dyna algorithm registers approximately the same fuel consumption as the dynamic programming–based global optimal solution. The computational cost of the Dyna algorithm is substantially lower than that of the stochastic dynamic programming.

BACKGROUND: Hebardina concinna is a domestic pest and potential vector of pathogens throughout East and Southeast Asia, yet identification of this species has been difficult due to a lack of diagnostic morphological characters, and to uncertainty in the relationship between macroptyrous (long-winged) and brachypterous (small-winged) morphotypes. In insects male genital structures are typically species-specific and are frequently used to identify species. However, male genital structures in H. concinna had not previously been described, in part due to difficulty in identifying conspecifics. METHODS/PRINCIPAL FINDINGS: We collected 15 putative H. concinna individuals, from Chinese populations, of both wing morphotypes and both sexes and then generated mitochondrial COI (the standard barcode region) and COII sequences from five of these individuals. These confirmed that both morphotypes of both sexes are the same species. We then dissected male genitalia and compared genital structures from macropterous and brachypterous individuals, which we showed to be identical, and present here for the first time a detailed description of H. concinna male genital structures. We also present a complete re-description of the morphological characters of this species, including both wing morphs. CONCLUSIONS/SIGNIFICANCE: This work describes a practical application of DNA barcoding to confirm that putatively polymorphic insects are conspecific and then to identify species-specific characters that can be used in the field to identify individuals and to obviate the delay and cost of returning samples to a laboratory for DNA sequencing.