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Large-scale benchmark datasets are crucial in advancing research within the computer science communities. They enable the development of more sophisticated AI models and serve as "golden" benchmarks for evaluating their performance. Thus, ensuring the quality of these datasets is of utmost importance for academic research and the progress of AI systems. For the emerging vision-language tasks, some datasets have been created and frequently used, such as Flickr30k, COCO, and NoCaps, which typically contain a large number of images paired with their ground-truth textual descriptions. In this paper, an automatic method is proposed to assess the quality of large-scale benchmark datasets designed for vision-language tasks. In particular, a new cross-modal matching model is developed, which is capable of automatically scoring the textual descriptions of visual images. Subsequently, this model is employed to evaluate the quality of vision-language datasets by automatically assigning a score to each 'ground-truth' description for every image picture. With a good agreement between manual and automated scoring results on the datasets, our findings reveal significant disparities in the quality of the ground-truth descriptions included in the benchmark datasets. Even more surprising, it is evident that a small portion of the descriptions are unsuitable for serving as reliable ground-truth references. These discoveries emphasize the need for careful utilization of these publicly accessible benchmark databases. [ABSTRACT FROM AUTHOR]

The urban spatial structure is a key feature of the distribution of social and economic resources. The spatial structure of an urban agglomeration is an abstract relationship expression of urbanization. Urban agglomerations develop for multiple reasons, including urban planning and natural evolution. To date, most research related to urban agglomeration has been based on single data source, which is a limitation. This research aims to propose a spatial structure identification method for urban agglomerations via a complex network based on nighttime light data and railway data. Firstly, we extracted the urban built-up area using defense meteorological satellite program/operational line scanner (DMSP/OLS) data, and divided it into urban objects to obtain the nighttime light urban network (NLUN) by borough. Secondly, we aggregated railway stations at municipal level using railway operation data to obtain the railway urban network (RUN). Following this, we established a composite urban network (CUN) consisting of the NLUN and the RUN based on the composite adjacency matrix. Finally, the Louvain algorithm and the comprehensive strength index (CSI) were used to detect the communities and central nodes of the CUN and obtain the urban agglomerations and core cities. The results show that urban agglomeration identification based on the CUN has the best accuracy, which is 5.72% and 15.94% higher than that of the NLUN and RUN, respectively. Core cities in the urban agglomeration identified by the CSI in the CUN are at least 3.04% higher than those in the single-source urban network. In addition, the distribution pattern of Chinese urban agglomerations in the study area is expressed as "three vertical", and the development level of urban agglomeration shows an unbalanced trend. [ABSTRACT FROM AUTHOR]

In the past three decades, researchers have engaged in the relationship between the composition, macro performance, and microstructure of asphalt. There are many research results in the use of atomic force microscopy (AFM) to study the microstructure and related mechanisms of asphalt. Based on previous studies, the performance of asphalt from its microstructure has been observed and analyzed, and different evaluation indices and modification methods have been proposed, providing guidance toward improving the performance of asphalt materials and benefiting potential applications. This review focuses on the typical application and analysis of AFM in the study of the aging regeneration and modification properties of asphalt. Additionally, this review introduces the history of the rheological and chemical testing of asphalt materials and the history of using AFM to investigate asphalt. Furthermore, this review introduces the basic principles of various modes of application of AFM in the microstructure of asphalt, providing a research direction for the further popularization and application of AFM in asphalt or other materials in the future. This review aims to provide a reference and direction for researchers to further popularize the application of AFM in asphalt and standardize the testing methods of AFM. This paper is also helpful in further exploring the relationship between the microstructure and macro performance of asphalt. [ABSTRACT FROM AUTHOR]

When the control parameters and operating conditions remain unchanged, it is usually believed that the admittance characteristic of grid-connected inverter is time-invariant. However, considering the effect of frequency-coupling, an abnormal phenomenon is observed in the admittance measurement of the grid-connected inverter: the phase of the off-diagonal elements Y12 and Y21 in the admittance matrix is always changed with time, which presents a time-varying admittance characteristic. To explore this phenomenon, the theoretical analyses based on the traditional frequency-coupling admittance measurement method are made. Because the initial phase of the signal cannot be obtained from Fast Fourier Transform (FFT) in experiments and the disturbance frequency and coupling frequency are different, the phase difference between the two frequency components changes with time. However, the influence is not considered in the traditional frequency-coupling admittance measurement method, which makes the measurement results exhibit the confusing time-varying characteristic. The phenomenon is defined as pseudotime-varying admittance characteristic in this letter. To accurately measure the admittance characteristic of the grid-connected inverter, a frequency-coupling admittance measurement method based on phase correction is proposed, which corrects the phase of disturbance frequency components and coupling frequency components. Finally, the effectiveness of the proposed measurement method is verified by experiments. [ABSTRACT FROM AUTHOR]

• Considering the effects of frequency coupling and cascade transformer, this paper establishes the frequency coupling impedance model of GCWPS and applies the generalized Nyquist criterion to analyze the stability of the whole system as the grid strength, PLL bandwidth and output power change. • Aiming at the power oscillation problem of GCWPS under weak grid, a composite feedforward damping oscillation suppression strategy is proposed, and the output impedance characteristic of GCWPS is reconstructed. • The frequency coupling impedance model of GCWPS adopting the oscillation suppression strategy proposed in this paper is constructed, and a comparison between its stability and that of the GCWPS adopting the traditional control strategy is made. It is proved that the system has stronger adaptability to the increase of output power and PLL bandwidth under weak grid when adopting the proposed oscillation suppression strategy. The stability of grid-connected wind power system (GCWPS) is prone to deteriorate due to the impedance interaction between wind turbines and the weak grid. For purpose of finding out the cause of power oscillation and effectively improving the stability of GCWPS under weak grid, firstly of all, a frequency coupling impedance model (FCIM) for GCWPS is established. Through analyzing the impedance characteristic of GCWPS, a significant coupling effect between GCWPS impedance and grid impedance in the middle-low frequency region under weak grid is observed, which is easy to cause power oscillation. For purpose of restraining the power oscillation of GCWPS under weak grid, this paper proposes an oscillation suppression strategy based on composite feedforward damping. Virtual damping is incorporated into the feedforward loop to rectify the impedance characteristic curve of GCWPS. Then, a FCIM of GCWPS that adopts the proposed oscillation suppression strategy is established, and the stability analysis demonstrates that the proposed strategy effectively enhances the GCWPS stability under weak grid. Additionally, compared with conventional control strategy, GCWPS exhibits enhanced adaptability to the increased output power and phase-locked loop (PLL) bandwidth under weak grid. Finally, experiments are undertaken to evidence the feasibility of the proposed oscillation suppression strategy. [ABSTRACT FROM AUTHOR]

Background: Human dental pulp stem cells (hDPSCs) possess mesenchymal stem cell properties, originating from migrating neural crest cells. hDPSCs have received extensive attention in the field of tissue engineering and regenerative medicine due to their accessibility and ability to differentiate in several cell phenotypes. In this study, we cultured hDPSCs with Y-27632 to observe their biological behaviors changes. Methods: The hDPSCs were separately cultured with Y-27632 (0, 0.156, 0.312, 0.625, 1.25, 2.50, 5, 10, 20, 40 μ m) for 24, 48, 72 h to select the suitable concentration and time using CCK-8. Then, the hDPSCs were cultured with 2.50 μ m Y-27632 for 48 h to analyzed the biological behaviors changes by 5-Ethynyl-2′-deoxyuridine (EdU), plate cloning, transwell, scratch, and Annexin V FITC/PI assays, separately. Additionally, osteogenic calcium nodules and lipid droplets were analyzed using alizarin red staining and oil red O staining, respectively. qRT-PCR was used to analyze the expression of osteogenesis, adipogenesis, stemness maintenance, and inflammation related genes. Results: The hDPSCs proliferation was significantly enhanced after cultured with 2.50 μ m Y-27632 for 48 h, but there was no significant difference in migration and apoptosis. Observation of alkaline phosphatase (ALP) activity, osteogenic and adipogenic differentiation abilities of hDPSCs, Y-27632 treatment clearly decreased the ALP activity and osteogenic differentiation ability, increased the adipogenic differentiation ability. Furthermore, Y-27632 decreased the CD73, CD90, CD105, CD166, TLR4, and NF-κB p65 genes expression, but increased the IL-8 gene expression. Conclusions: The biological behaviors of hDPSCs could be changed when they cultured with Y-27632. [ABSTRACT FROM AUTHOR]

It tends to cause system oscillation when the inverter with a phase-locked loop based on proportional integral controller (PI-PLL) is connected to the weak grid. To improve the oscillation suppression ability of the grid-connected inverter, a linear active disturbance rejection controller is applied to PLL (LADRC-PLL). Considering the influence of linear extended state observer, voltage outer-loop, current inner-loop, and frequency coupling, the admittance model of the grid-connected inverter with LADRC-PLL is established. Based on the established admittance model and the generalized Nyquist criterion, the system stabilities of the grid-connected inverters with LADRC-PLL and PI-PLL are compared. The comparison results indicate that the grid-connected inverter with LADRC-PLL has better adaptability to the weak grid and shows a certain ability to suppress the sub and supersynchronous oscillation. Then, the influence of the control parameters of LADRC-PLL on the system stability is studied. It is found that the system keeps stable when the control parameter of LADRC-PLL is changed in a relatively wide range, which indicates LADRC-PLL has good robustness. Furthermore, the dynamic performances of the grid-connected inverters with LADRC-PLL and PI-PLL are analyzed. It is revealed that the grid-connected inverter with LADRC-PLL has better dynamic performance. Finally, the correctness of the analysis is verified by experiments. [ABSTRACT FROM AUTHOR]

Direct power control (DPC) is widely used in grid-connected inverters. First, considering the effects of phase-locked loop (PLL), voltage outer loop, power inner loop, control delay, and frequency coupling, a broadband admittance model of the grid-connected inverter with DPC is established. The admittance characteristics of grid-connected inverters with DPC and closed-loop current control (CCC) are compared and analyzed. Due to the different inner loop control objects, the components produced by the power calculation in DPC and the Park's transformation in CCC cause the admittance differences between the grid-connected inverters with DPC and CCC. Then, the effects of grid impedance, output power, and control parameters on system stability are analyzed. It is revealed that the stability of the grid-connected inverter with DPC is very sensitive to grid impedance and easily affected by output power and inner loop bandwidth, while the grid-connected inverter with CCC has a better adaptability to weak grid, high output power, and inner loop bandwidth. Moreover, the PLL bandwidth has little effect on the stability of the grid-connected inverter with DPC, but has a great impact on the stability of the grid-connected inverter with CCC when the inverter is connected to weak grid. Finally, the correctness of the analysis is verified by experiments. [ABSTRACT FROM AUTHOR]

For few-shot video action recognition, it is essential to extract and align features from different videos. However, these operations can be complicated and unreliable due to the complexity of the video scene and the limitations of existing alignment algorithms. To enhance the saliency of the action-related features, we introduce segmentation mask frame sequences as prior information and devise a two-stream feature fusion module to fuse the multimodal features. Furthermore, we propose a self-attention-based temporal alignment module to predict the optimal alignment matrix between the features of samples in the query and support sets. This module avoids solving additional optimization problems in computing the alignment matrix, thus reducing the difficulty of the model for end-to-end learning. Our approach achieves competitive performance on four public datasets. We also experimentally validate the effectiveness of the proposed modules. [ABSTRACT FROM AUTHOR]

Mastering the evolution of urban land cover is important for urban management and planning. In this paper, a method for analyzing land cover evolution within urban built-up areas based on nighttime light data and Landsat data is proposed. The method solves the problem of inaccurate descriptions of urban built-up area boundaries from the use of single-source diurnal or nocturnal remote sensing data and was able to achieve an effective analysis of land cover evolution within built-up areas. Four main procedures are involved: (1) The neighborhood extremum method and maximum likelihood method are used to extract nighttime light data and the urban built-up area boundaries from the Landsat data, respectively; (2) multisource urban boundaries are obtained using boundary pixel fusion of the nighttime light data and Landsat urban built-up area boundaries; (3) the maximum likelihood method is used to classify Landsat data within multisource urban boundaries into land cover classes, such as impervious surface, vegetation and water, and to calculate landscape indexes, such as overall landscape trends, degree of fragmentation and degree of aggregation; (4) the changes in the multisource urban boundaries and landscape indexes were obtained using the abovementioned methods, which were supported by multitemporal nighttime light data and Landsat data, to model the urban land cover evolution. Using the cities of Shenyang, Changchun and Harbin in northeastern China as experimental areas, the multitemporal landscape index showed that the integration and aggregation of land cover in the urban areas had an increasing trend, the natural environment of Shenyang and Harbin was improving, while Changchun laid more emphasis on the construction of artificial facilities. At the same time, the method proposed in this paper to extract built-up areas from multi-source city data showed that the user accuracy, production accuracy, overall accuracy and Kappa coefficient are at least 3%, 1%, 1% and 0.04 higher than the single-source data method. [ABSTRACT FROM AUTHOR]

Air booster vacuum preloading method is a useful method for strengthening dredged slurry. Though this method is improved effectively with the rapidly developed technology, the problem of inadequate reinforcement in deep layers of soil is still in existence. In view of the fact that the pressurizing system can effectively enhance the reinforcement effect. Therefore, this paper discusses the reinforcement effect of a new pressurizing system that put the booster pipeline at the bottom of soil. Meanwhile, another problem is found that the booster pipeline type was single at present, the action effect of different kind of booster pipeline is still uncertain. In this paper, laboratory experiments are performed to investigate the influence of two kinds of pressurization position and two types of booster pipeline on the treatment of five dredged slurry samples. The test results showed that though the vertical pressurizing system can be good to reinforce the middle soil layers, but the bottom pressurizing system can make the whole soil layer more homogeneous. Furthermore, the difference of the two kinds of booster pipeline on the reinforcement effect of soil is not significant. These results provide good guidance for practical application of air booster vacuum preloading in land reclamation project. [ABSTRACT FROM AUTHOR]

In the construction of roadbeds in mountainous areas, crushed rock slag (CRS) generated by tunnel blasting is usually reused as road construction material to reduce environmental pollution and construction costs. A series of large-scale drained triaxial tests were conducted to investigate the mechanical behavior of CRS subjected to static and traffic loading. The static triaxial tests determined the maximum stress level that can be applied to the cyclic test. The cyclic triaxial test analyses the influence of cyclic stress amplitude and confining pressure on the cumulative strain of CRS material. The particle breakage of the sample under various conditions after cyclic loading was discussed, and the relationship between the relative breakage index and the final accumulated strain was analyzed. Test results indicated that with the increase in confining pressure, the peak strength of the material exhibits a continual enhancement, while the expansion behavior experiences a gradual attenuation. In the range of static failure strength, the increase of cyclic stress level will significantly increase the accumulated axial strain rate. After the cyclic loading, the particle breakage patterns are similar under different confining pressures. A good power function relationship exists between the relative breakage index and final axial strain, and further derivation of the functional expression of the relative breakage index and both cyclic stress ratio and confining pressure. • It is confirmed that the tunnel slag material is a strain softening type material, and the degree of softening decreases as the confining pressure increases. • Under cyclic loading, the accumulated strain of CRS material is influenced by cyclic stress and confining pressure, and the final strain shows exponential growth with the both factors. • Under cyclic loading, the main forms of breakage of CRS are grinding and surface crushing. The degree of breakage increases with the increase of confining pressure and cyclic stress ratio. • The relative breakage index shows a good linear relationship with the cyclic stress ratio. A model was established to represent the relative breakage index using confining pressure and cyclic stress ratio. [ABSTRACT FROM AUTHOR]

In Tahe Oilfield, Tarim Basin, NW China, the carbonate reservoir displays poor porosity and permeability in its matrix, while the fractured-vuggy system is distributed in a random, discreet and discontinuous way, which yields significant oil rates once the fractured-vuggy system is connected by production wells. The fractured-vuggy carbonate reservoirs are consisting of a group of large carves and inter-connected by high permeability fractures. Due to lack of powerful and suitable EOR (Improved Oil Recovery) strategies, depletion-drive recovery is commonly adopted for practical production at the beginning. After a period of production, the elastic energy of the cave formation weakens, causing insufficient liquid supply, the water injected for water flooding is used to improve the oil recovery of the fractured-vuggy carbonate reservoirs. However, the water injection curves of the carbonate reservoir are different from that of the sandstone reservoir as their fundamental flow mechanisms are different. For the fractured-vuggy reservoirs with high permeability, the water injection curves can be adopted to calculate the volumes in place of crude oil and formation water in a single or multi-caves. This paper presents a new model of injection curves. Using the proposed model with multi-round water injection curves, we can initially judge reservoir type and determine the volumes of cave, crude oil and water in the caves reasonably. Besides, as testified by the practical case, the parameters interpreted by the new models are proved to be reasonable and reliable. This new model is a useful tool to estimate the crude oil reserves, to demonstrate how much remaining oil in the caves, and to identify where the water-oil contact is. [ABSTRACT FROM AUTHOR]

Purpose: The oncogenic roles of sphingosine kinase 1 (SphK1) in various cancers, including thyroid cancer, have been well demonstrated. However, the microRNAs (miRNAs) associated with the oncogenic roles of SphK1 remain largely unknown. Methods: Global gene and miRNA expression in TPC1-Vector and TPC1-SphK1 cells was analyzed using digital gene expression (DGE) analysis and small RNA-seq, respectively. miRNA-mRNA interactions were explored by microT-CDS, and the predicted networks were visualized using CytoScape. Cell invasion and migration were assessed by performing Transwell invasion and wound-healing assays. Luciferase reporter and immunoblot assays were used to evaluate the targeting of fibronectin 1 (FN1) by miR-144-3p. Results: In this study, we found that overexpression of SphK1 differentially regulates the expression of 46 miRNAs and 506 mRNAs in papillary thyroid cancer (PTC) TPC1 cells. Combining bioinformatics predictions of mRNA targets with DGE data on mRNA expression allowed us to identify the mRNA targets of deregulated miRNAs. The direct interaction between miR-144-3p and FN1, which mediates the pro-invasive role of SphK1 in PTC cells, was experimentally validated. Conclusions: Our results demonstrated that SphK1 overexpression drives a regulatory network governing miRNA and mRNA expression in PTC cells. We also demonstrated the roles played by miR-144-3p and FN1 in mediating the oncogenic function of SphK1, which enhanced the understanding of the etiology of PTC. [ABSTRACT FROM AUTHOR]

Crystalline poly(L-lactide) (PLLA) nanoparticles were prepared by aminolysis of electrospun PLLA nanofibers and subsequently labeled by a fluorescent colorant. The size of the nanoparticles could be controlled by either the conditions of the aminolysis reaction or the diameter of the original electrospun fiber. The latter method resulted in higher yield. Although the as-spun nanofibers were generally amorphous, the nanoparticles showed high crystallinity in the typical α-form of PLLA crystals, as revealed by X-ray diffraction and differential scanning calorimetry. Gel-permeation chromatography was used to determine the molecular weight of the formed particles in relation to aminolysis time. After aminolysis, PLLA nanoparticles spontaneously generated amine groups on the surface, which are available for further modifications. In this study the amine groups were reacted with isothiocyanate groups, and fluorescein-5'-isothiocyanate was successfully attached to the PLLA nanoparticles. Smaller particles showed significantly higher fluorescein binding density. Through this simple 'top-down' routine, it was possible to create nanoparticles with tailorable size and specific surface functions. Such materials could serve in bioimaging or nanomedicine applications. [ABSTRACT FROM AUTHOR]

Engaging children in describing real-life scenes provides an effective approach to fostering language production and developing their language skills, enabling them to establish meaningful connections between their language proficiency and authentic contexts. However, for such learning tasks, there has been a lack of research focusing on promoting self-directed language learning by using artificial intelligence techniques, primarily due to the challenges of handling multimodal information involved in such tasks. To address this gap, this study introduced a two-stage automated evaluation method that employed emerging cross-modal matching AI techniques. Firstly, an automated scoring model was developed to evaluate the quality of students' responses to scene description tasks. Compared with manually assigned human scores, our model scored students' descriptions accurately, as evidenced by a small testing mean absolute error of 0.3969 for a total score of 10 points. Based on the scoring results, immediate feedback was then provided to students by generating targeted comments and suggestions. The goal of this feedback was to assist students in progressively improving their descriptions of daily-life scenes, thereby enabling them to practice their language skills independently. To assess the effectiveness of the feedback, a comprehensive investigation was conducted involving 157 students from middle schools in China, and both qualitative and quantitative experimental data were collected from the students. It is found that the quality of students' descriptions was improved significantly with the assistance of immediate feedback. On average, students achieved an increase of 1.48 points in their scores after making revisions based on the feedback. In addition, students reported positive learning experiences and expressed favorable opinions regarding the language learning tasks with the automated evaluation. The findings of this study have significant implications for future research and educational practice. They not only highlighted the potential of emerging cross-modal matching AI techniques in automatically evaluating learning tasks involving multimodal data but also suggested that providing immediate targeted feedback based on automated scoring results can effectively promote students' self-directed language learning. • Generating descriptions from real-life visuals enhances authentic language learning. • Feasible to provide automated feedback in self-directed language learning using AI. • Automated feedback motivates students to improve and engage in language learning. [ABSTRACT FROM AUTHOR]

This study investigates the economic resilience of cities in Hubei province during the COVID-19 pandemic, utilizing highway nighttime lights as a proxy indicator. By February 2020, the pandemic had caused a significant economic contraction in Hubei. However, by May 2021, a strong recovery was observed, with most cities experiencing growth rates of over 20%. Despite initially similar responses to the crisis, this study reveals significant heterogeneity in economic resilience across the examined cities in Hubei. The spatial distribution follows a core-periphery structure, with Wuhan exhibiting greater resistance to economic shocks compared to peripheral cities. Furthermore, the response capacity within the Wuhan urban agglomeration area exhibits regional variations. In summary, lockdown policies had spatially varied impacts on economic resilience across Hubei's cities. These results offer valuable insights into regional economic resilience and contribute to the formulation of strategies aimed at effectively addressing future unforeseen events. [ABSTRACT FROM AUTHOR]

Corn oil as a nanofluid base fluid has the problem of easy oxidation, and the addition of tertiary butyl-hydroquinone is expected to improve the antioxidant property of corn oil. In this paper, a new environmentally friendly nanofluid was prepared by using corn oil as a base fluid, A12O3 as nanoparticles, and tertiary butylhydroquinone as an antioxidant to study its settlement stability and antioxidant properties. The content of oxidation products and viscosity of the nanofluids at different times were investigated from the perspectives of particle size, particle mass fraction, antioxidant type, and antioxidant addition. The results showed that the nanofluids produced without surfactant, 100 mL of corn oil, Al2O3 nanoparticles with a particle size of 20 nm and a particle mass fraction of 1.1083% had the best sedimentation stability. The nanofluid with 0.7% of tertiary butylhydroquinone added had the optimum antioxidant properties. There are two phenolic hydroxyl groups in the molecule of tertiary butylhydroquinone, and each of the two phenolic hydroxyl groups provides one hydrogen ion, which forms stable quinone compounds in corn oil, making the oxidation rate of the corn oil slower. When the content of tertiary butylhydroquinone was added at less than 0.4%, the content of tertiary butylhydroquinone was not enough to effectively retard the oxidation reaction of the oil. When the addition of tertiary butylhydroquinone exceeded 0.7%, the antioxidant property of the nanofluid could only be improved slightly, and the oxidation induction time increased slowly, but on the contrary, the viscosity of the nanofluid would be increased greatly. The nanofluid prepared in this paper has the characteristics of environmental friendly and good antioxidant performance, which can effectively slow down the generation of oxidised substances. This study contributes to the further development of antioxidant research of environmentally friendly nanofluids. [ABSTRACT FROM AUTHOR]

Given that the Delta Variant of Concern (VOC), the dominant SARS-CoV-2 strain in 2021, becomes more infectious and produces ~1000-fold higher viral titers compared to the ancestral strain [[4]], more strict quarantine management has been applied for all discharged Delta-infected patients. SARS-CoV-2-infected patients will be discharged when viral ribonucleic acid (RNA) is consecutively negative at least twice over a 24-h interval. (B) Kinetics of SARS-CoV-2 RNA clearance in patients with positive retest and negative retest viral RNA in local and imported patients. For local patients with positive retest viral RNA, 95% and 45% of the patients required another 21 and 42 days, respectively, to become completely viral RNA negative (Supplementary Fig. [Extracted from the article]

• A small-signal sequence impedance model of the island power system is built by harmonic linearization method. It is found that the output sequence impedance of the source PWM inverter in the system is not affected by the stable operating point. • Based on the impedance model, the influence of load type and load power on the stability of the island power system is analyzed. The essential reason of the high-frequency oscillation is that the capacitive output impedance of the source PWM inverter does not match the inductive output impedance of the load PWM rectifier at high-frequency areas. • An impedance reconstruction control for the source PWM inverter is proposed, which improves the phase of the output sequence impedance of the source PWM inverter at high-frequency areas to effectively suppress the high-frequency oscillation of the island power system. In island power system with strong mutual interaction of power electronic devices, stability problems such as high-frequency oscillation are prone to occur. Firstly, a small-signal sequence impedance model of an island power system is built by harmonic linearization method. It is found that the output sequence impedance of the source PWM inverter in the system is not affected by the stable operating point, but the input sequence impedance of the load PWM rectifier will decrease with the increase of power. Then, based on the sequence impedance model and Nyquist stability criterion, the influence of load type and load power on stability of the island power system is analyzed, which can reveal that high-frequency oscillation occurs when the source PWM inverter interacts with the load PWM rectifier. The essential reason of the high-frequency oscillation is that the capacitive output impedance of the source PWM inverter does not match the inductive output impedance of the load PWM rectifier at high-frequency areas. Aiming at this issue, an impedance reconstruction control for the source PWM inverter is proposed, which improves the phase of the output sequence impedance of the source PWM inverter at high-frequency areas to effectively suppress the high-frequency oscillation of the system. Finally, experiment results verify the correctness of analysis and effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

• A small-signal model of the grid-connected system of SSVSI is established. The model fully considers the power coupling phenomenon in the system and provides a basis for in-depth analysis of the system characteristics. • The effects of grid equivalent resistance and SSVSI control parameters on the system are comprehensively analyzed. The effects of power coupling on the stable region of control parameters are quantitatively analyzed. In addition, the contradiction between SFR suppression and power coupling is analyzed when the virtual resistance is introduced. • An SFR suppression method based on band-stop filters is proposed. The proposed method effectively suppresses the resonance peaks without changing the original control parameters of the system, and improves the power response speed of the system. In addition, the proposed method avoids exacerbating the power coupling of the system compared to the virtual resistance method. Self-synchronizing voltage source inverter (SSVSI) can effectively improve grid frequency stability. However, the synchronous frequency resonance (SFR) inevitably exists in SSVSI. In this paper, a small-signal model considering power coupling is established to analyze the system characteristics. It is found that the control parameter adjustment and the virtual resistance method can suppress the SFR. However, the control parameter adjustment will change the dynamic and steady-state characteristics of the system, and the virtual resistance method will exacerbate the power coupling of the system. For this reason, based on the idea of eliminating the resonance peaks, this paper proposes an SFR suppression method based on band-stop filters. By connecting band-stop filters in series in the active power control loop (APCL) and the reactive power control loop (RPCL), the proposed method effectively suppresses the resonance peaks without changing the original control parameters of the system, and the control bandwidth is wider, which improves the power response speed of the system. In addition, the proposed method avoids exacerbating the power coupling of the system compared with the virtual resistance method. Finally, the simulation and experimental results verify the correctness of the theoretical analysis and the effectiveness of the control method. [ABSTRACT FROM AUTHOR]

• The effect of the internal power-sharing ratio of WTGs on the admittance characteristics of wind farms is investigated. • The identification method of the AOP-admittance model considering frequency-coupling for wind farms is proposed. • This method can identify the AOP-admittance model of wind farms by measurement data of WTGs under several operating points. • The identification method can avoid the dimension disaster in admittance modeling for the wind farm. Admittance identification is an effective tool to solve the issue of black-box admittance modeling in wind farms. However, due to the large operating range of wind farms, it is difficult to accurately identify the admittance model of wind farms under all operating conditions, which limits the research on wideband oscillation caused by the interaction between wind farms and the power grid. This paper analyses the characteristics of the frequency-coupling admittance for wind farms. It is found that the power-sharing ratio of wind turbine generators (WTGs) affects the admittance characteristic of the wind farm, which leads to a huge number of operating points for the wind farm. The all-operating-point (AOP) admittance model of wind farms considering frequency-coupling characteristics is hard to directly identify. Aiming for this problem, this paper proposes to first identify the AOP-admittance model for WTGs. Then, based on the operating points of each WTG and the network structure, the AOP-admittance model of the wind farm is obtained via the admittance aggregation and model reduction method. This proposed method solves the problem of black-box admittance modeling and addresses the problem of dimension disaster in admittance modeling for wind farms. The identified model of the wind farm can be used to accurately assess the stability of the wind power integration system under various operating conditions. Finally, the effectiveness of the proposed method is verified through the admittance measurement and stability analysis of the wind farm. [ABSTRACT FROM AUTHOR]

Hostile environmental cues cause Mycobacterium tuberculosis to enter a state of slow growth for survival. However, the underlying regulatory mechanism remains unclear. DnaA is essential for DNA replication initiation and represents an efficient target for growth regulation in bacteria. Here, we show that the nucleoid-associated protein NapM is a DnaA antagonist, protecting M. tuberculosis from stress-mediated killing. NapM can be induced by diverse stressful signals. It binds to DnaA to inhibit both its DNA replication origin-binding and ATP hydrolysis activity. As a DnaA antagonist, NapM inhibits the mycobacterial DNA synthesis in vitro and in vivo in M. tuberculosis. Furthermore, we show that NapM contributes to the survival of M. tuberculosis under stress and within macrophages during infection. Our findings provide a previously unidentified mechanism of mycobacterial survival under stress and also suggest NapM as a potential drug target for tuberculosis control. Yu Liu, Zhiwei Xie et al. show that nucleoid-associated protein NapM enhances the survival of M. tuberculosis in macrophages under stress by inhibiting DNA synthesis as a DnaA antagonist. This study suggests NapM as a potential drug target for tuberculosis control. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of polycentric urbanization is important for urban studies and management. This paper proposes an analytical model that uses multisource big geospatial data to characterize such dynamics to facilitate policy making. There are four main steps: (1) main centers and subcenters are identified using spatial cluster analysis and geographically weighted regression (GWR) based on Visible Infrared Imaging Radiometer Suite (VIIRS)/NPP and social media check-in data; (2) the built-up areas are extracted by using Defense Meteorological Satellite Program—Operational Linescan System (DMSP/OLS) gradient images; (3) the economic corridors that connect the main center and subcenters are constructed using road network data from Open Street Map (OSM) with the least-cost distance method; and (4) the major urban development direction is identified by analyzing the changes in built-up areas within the economic corridors. The model is applied to three major cities in northeastern, central, and northwestern China (Shenyang, Wuhan, and Xi'an) from 1992 to 2012. [ABSTRACT FROM AUTHOR]

Background: Inflammatory markers, including the product of neutrophil count, platelet count, and monocyte count divided by lymphocyte count (PIV) and the platelet‐to‐white blood cell ratio (PWR), have not been previously reported as prognostic factors in nasopharyngeal carcinoma (NPC) patients. In order to predict overall survival (OS) in NPC patients, our goal was to create and internally evaluate a nomogram based on inflammatory markers (PIV, PWR). Methods: A retrospective study was done on patients who received an NPC diagnosis between January 2015 and December 2018. After identifying independent prognostic indicators linked to OS using Cox proportional hazards regression analysis, we created a nomogram with the factors we had chosen. Results: A total of 630 NPC patients in all were split into training (n = 441) and validation sets (n = 189) after being enrolled in a population‐based study in 2015–2018 and monitored for a median of 5.9 years. In the training set, the age, PIV, and PWR, selected as independent predictors for OS via multivariate Cox's regression model, were chosen to develop a nomogram. Both training and validation cohorts had C‐indices of 0.850 (95% confidence interval [CI]: 0.768–0.849) and 0.851 (95% CI: 0.765–0.877). Furthermore, compared with traditional TNM staging, our nomogram demonstrated greater accuracy in predicting patient outcomes. The risk stratification model derived from our prediction model may facilitate personalized treatment strategies for NPC patients. Conclusion: Our findings confirmed the prognostic significance of the PWR and PIV in NPC. High PIV levels (>363.47) and low PWR (≤36.42) values are associated with worse OS in NPC patients. [ABSTRACT FROM AUTHOR]

The human skin organ culture (hSOC) developed a century ago has been widely used to study various aspects of human skin development, differentiation, function, disease as well as skin appendages biology, however, maintaining the integrity of epidermal structure in long-term culture, has remained a challenge. Here we tried to establish a culture system using supplemented William's E medium in the presence of a ROCK inhibitor Y-27632 to maintain epidermal architecture in the long-term hSOC and to investigate the underlying mechanisms. Human breast skins, cut into 5 mm × 5 mm pieces, were cultured in supplemented William's E medium in the presence of 30μM Y-27632. The cultured skin tissues were collected at different time points for analysis of epidermal cell proliferation and differentiation by real time qRT-PCR and immunofluorescence (IF) staining. The keratinocyte suspension assay and in vivo treatment of Y-27632 on mouse were also carried out to study that the regulation of Y-27632 on keratinocyte proliferation and differentiation. We found Y-27632 not only enhanced both basal cell proliferation and expression of suprabasal cell differentiation markers, but also maintained the balance of keratinocyte proliferation and differentiation through activation of AKT pathways on one hand and inhibition of ERK pathways on the other hand. The AKT inhibitor MK-2206 blocked the epidermal preservation effect of Y-27632, while the MEK/ERK inhibitor U0126 enhanced the preservation of epidermal structure in the hSOC. Y-227632 can maintain skin epidermal integrity through regulation of AKT and ERK activity in the hSOC. [ABSTRACT FROM AUTHOR]

In this study, Cu2ZnSnS4 (CZTS) thin films were prepared by magnetron sputtering deposition of the Cu-Zn-Sn metallic precursor (CZT) on flexible molybdenum foils and a two-step sulfurization process. Low-temperature pre-sulfurization was performed before the final high-temperature sulfurization during the two-step sulfurization process to enhance the properties of CZTS. This paper presents a method to improve the properties of CZTS thin films, making them conducive to solar cell applications. The compositions and morphologies of CZTS were confirmed using energy dispersive spectroscopy and scanning electron microscopy, respectively. X-ray diffraction was conducted to investigate the structural properties of the CZTS thin films, and the results revealed that the CZTS phase in all the samples had a preferential plane along (112). Moreover, Raman spectroscopy helped distinguish the ZnS and Cu2SnS3 phases that are close to kesterite CZTS. Compared to the thin film prepared without pre-sulfurization treatment, a suitable increase in pre-sulfurization temperature could reduce the loss of Sn and enhance the crystallinity of CZTS. However, a higher pre-sulfurization temperature could result in the formation of secondary phases. The CZTS thin films exhibited good properties when the CZT precursor was pre-sulfurized at 150 °C. In addition, the CZTS thin films had a single phase and flat and dense surfaces with large grains. The optical parameters were calculated based on the reflectance and transmittance data obtained by UV–Vis spectroscopy. The absorption coefficient was larger than 1 × 104 cm−1, and the optical bandgap was about 1.55 eV; these are suitable properties for CZTS absorption layers in CZTS thin-film solar cells. [ABSTRACT FROM AUTHOR]

Posaconazole and voriconazole are commonly used for preventing invasive fungal disease (IFD), but few studies compared posaconazole with voriconazole for primary antifungal prophylaxis (PAP) in pediatric acute leukemia. To compare posaconazole with voriconazole for PAP in pediatric acute leukemia. This retrospective observational study enrolled pediatric patients with non-M3 acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) between December 2017 and November 2019 in the Second Affiliated Hospital of Anhui Medical University. The patients received voriconazole or posaconazole for PAP. The primary outcome was the breakthrough of IFD. The secondary outcome was the overall survival (OS) and IFD-free survival of patients. A total of the 275 patients were enrolled, of which 120 patients taking voriconazole (43.6%) and 155 patients taking posaconazole (56.4%). The breakthrough of IFD occurred in 19 (15.8%) patients taking voriconazole and in 12 (7.7%) patients taking posaconazole (P = 0.035). There was no significant differences in IFD-free survival (P = 0.336) or OS (P = 0.069) between the patients taking voriconazole and posaconazole. In the subgroup of AML patients, the OS of patients taking posaconazole was better than those receiving voriconazole (P = 0.017). Posaconazole and voriconazole were comparable for PAP in patients with pediatric acute leukemia regarding the OS and IFD-free survival, but posaconazole might achieve a lower IFD breakthrough rate. [ABSTRACT FROM AUTHOR]

The limiter in grid-connected inverter control may cause sustained oscillation in the system. The large-signal impedance model is provided since the traditional small-signal impedance model cannot accurately describe the characteristics of the limiter. In this paper, there are three established large-signal impedance models of grid-connected inverters that take into account the limiter in the phase-locked loop (PLL), the limiter in the current control loop and the limiter in the pulse width modulation (PWM). Based on the established models, the influences of these different limiters on the output impedance characteristics of the grid-connected inverter are discussed. Furthermore, the stability of the system considering the influence of different limiters is analyzed and the oscillation frequency and amplitude of the system are predicted. The simulation verifies the accuracy of the large-signal impedance model and the predicted oscillation frequency and amplitude. [ABSTRACT FROM AUTHOR]

• Cu-support ZrO 2 inverse catalysts exhibit higher STY MeOH from CO 2 hydrogenation. • The oxide-metal inverse interface is a more MeOH selective structure. • There exists an optimal coverage of nano-ZrO 2 on the Cu/ZrO 2 inverse catalyst. • The inverse interface favors conversion of key intermediates of formate to methoxy. • Methanol desorbs more easily on inverse catalysts than the conventional ones. The performance of Cu-based catalysts in the low temperature CO 2 conversion to methanol highly correlates with interfacial structure. In this paper, the interfacial structure of Cu/ZrO 2 catalysts is tuned by changing the molar ratio and precipitation sequence of Cu and Zr precursors in the oxalate precipitation method. Structural characterizations demonstrate that the interface structure gradually transforms from the conventional ZrO 2 -supported nano-Cu interface to the Cu-supported nano-ZrO 2 inverse interface with the ascending Cu/Zr ratio. The space–time yield (STY) of methanol over 90 mol Cu % Cu/ZrO 2 inverse catalyst is 518 g CH3OH /kg cat /h, which far exceeds that of the optimized 40 mol Cu % Cu/ZrO 2 catalyst (351 g CH3OH /kg cat /h). The inverse catalyst also exhibits the best methanol selectivity and lowest apparent activation energy. The correlation of the exposed Cu surface area, Cu particle size, and CO 2 adsorption capacity with STY methanol reveal that there is an optimal coverage of fine ZrO 2 particles and the Cu supported nano-ZrO 2 inverse configuration is a more suitable structure for methanol synthesis from CO 2. High-pressure in situ DRIFTS experiment shows that the adsorbed formate and methoxy intermediates over 90 mol Cu % Cu/ZrO 2 inverse catalyst are more reactive for further hydrogenation. In addition, the inverse configuration is more favorable for the methanol desorption from surface. The enhanced hydrogenation ability and relatively weak oxygenates adsorption of Cu-supported nano-ZrO 2 interface is probably the main reasons for the improved catalytic performances of inverse catalysts. [ABSTRACT FROM AUTHOR]

Imaging optics play a crucial role in the angle measurement system. However, the field of view (FOV) is inversely proportional to the focal length in the optical imaging system, meaning that the detection distance and FOV cannot be considered simultaneously. This paper presents a non-imaging angle detection system incorporating an optical model using a compound paraboloid collector (CPC) and data processing based on a backpropagation (BP) neural network. This method has a detection capability of 200 km, with the FOV of azimuth and pitch angles being 60°. The angle detection resolution is 1°, while the angle error is less than 0.1°. A detector array absorbs the far-field light reflected by the CPC. Changing the pitch and azimuth angles establishes the nonlinear relationship between the number of rays each detector receives and the angle. Then, a BP neural network is used to train the nonlinear relationship into a linear one. Based on the light flux data on the detector array, the simulation results show that the system can effectively predict the angle. [ABSTRACT FROM AUTHOR]

Offshore wind turbines are subjected to significant combination environmental loads from wind and wave action. Under such conditions, the directions of these environmental loads vary over the structure's service life, and the stress directions of subsoil rotates during the wind turbine operating process. Tests were conducted on saturated soft clay using multi-directional cyclic simple apparatus to investigate the influence of stress rotation angle. All test results implied that both the stress rotation angles and cyclic stress ratios influence the dynamic responses of the reconstituted clay greatly and regularly: shear strain and pore pressure decrease as θ values vary from 0° to 90° and increase as θ changes between 120° and 180°. Shear strain accumulative ratio for θ = 0°, 30°, 150°, and 180° is more incredible than that of 60°, 120°, and 90°. Increasing the cyclic shear stress ratio will enhance the effect of θ on the cyclic strain and excess pore water pressure. • Shear paths varies lead bidirectional shear stress fluctuate range changed with stress rotate angle. The x -directional stress fluctuate range is about two times of that y -direction. And the stress fluctuate of x direction is also varied with θ. • The shear strain and excess pore pressure decrease as θ increases from 0° to 90° and increase as θ increases from 90° to 180°, which is related to the shear stress fluctuate range. • All γd – N and u – N curves depend on the cyclic stress ratio and the principal stress rotation angles and the effect of the principal stress rotation angle on the strain and excess pore pressure will be enhanced as the increasing CSR s. [ABSTRACT FROM AUTHOR]

Treatment of COVID-19 with a soluble version of ACE2 that binds to SARS-CoV-2 virions before they enter host cells is a promising approach, however it needs to be optimized and adapted to emerging viral variants. The computational workflow presented here consists of molecular dynamics simulations for spike RBD-hACE2 binding affinity assessments of multiple spike RBD/hACE2 variants and a novel convolutional neural network architecture working on pairs of voxelized force-fields for efficient search-space reduction. We identified hACE2-Fc K31W and multi-mutation variants as high-affinity candidates, which we validated in vitro with virus neutralization assays. We evaluated binding affinities of these ACE2 variants with the RBDs of Omicron BA.3, Omicron BA.4/BA.5, and Omicron BA.2.75 in silico. In addition, candidates produced in Nicotiana benthamiana, an expression organism for potential large-scale production, showed a 4.6-fold reduction in half-maximal inhibitory concentration (IC50) compared with the same variant produced in CHO cells and an almost six-fold IC50 reduction compared with wild-type hACE2-Fc. [ABSTRACT FROM AUTHOR]

Impedance-based approachis generally studied for stability analysis of the power electronic converter-based system. Considering multiple-frequency coupling effects, in this article, we establish the harmonic transfer function (HTF) based αβ-frame impedance models of droop inverters based islanded microgrid with unbalanced loads. Therein, the HTF-based αβ-impedance modeling methods of unbalanced loads, as well as droop inverters in parallel, are proposed. Afterward, the HTF-based αβ-frame impedance models are equivalent to single-input single-output (SISO) impedances for simpler impedance measurement and stability analysis, preserving the αβ-frame coupling and multiple-frequency coupling characteristics. Finally, the experimental measurement results verify the accuracy of the αβ-frame SISO impedances. Besides, the stability analysis based on the SISO impedance models accurately reveals low-frequency oscillations of the islanded microgrid with unbalanced loads, further verifying the effectiveness of the SISO impedance models. [ABSTRACT FROM AUTHOR]

• True triaxial loading and unloading tests on sandstone with structural plane. • Crack initiation mode around structural plane tip is related to stress environment. • Comparison of structural surface closure for different true triaxial conditions. • Peak strength characteristics for rock with open and closed structural planes. In order to study the mechanical behavior and failure characteristics of rock mass with the structural plane in complex deep stress environment, the QKX-YB200 true triaxial rockburst test system, acoustic emission, and digital video recorder were adopted to conduct true triaxial loading and unloading indoor tests on the red sandstone cube specimens. The results show that: (1) Under true triaxial loading conditions, all specimens propagate in the form of anti-wing crack, and the dip angle of the structural plane is linearly related to the average value of the anti-wing crack propagation angle; under true triaxial unloading conditions, the specimens with structural plane dip angles of 30°, 45°, and 60° propagate in the form of wing crack, while those with a 90° angle propagate anti-wing cracks, and the closure of structural plane is related to the the crack type at the tips of structural plane. (2) The unstable failure stages in the stress–strain curve under true triaxial unloading are longer and exhibit more pronounced fluctuations; the peak strength of the specimens under the conditions of true triaxial loading and unloading decrease first and then increase with the increase of the dip angle, reaching the lowest at 45°. (3) During the true triaxial unloading tests, the rockburst degree of the intact rock specimens is more violent than that of the specimens with a structural plane. Additionally, the dip angle of the structural plane influences the severity of rockbursts under the same stress path. (4) The crack propagation mechanism and the closure degree of structural planes under different true triaxial stress paths and dip angles are discussed. It is observed that the crack initiation mode around the structural plane tips and the crack mode near free surface are closely related to the stress environment in different areas of the specimens. (5) Based on the indoor test results and previous experimental data, the differences in peak strength characteristics between open structural planes and closed structural planes are preliminarily analyzed and compared. [ABSTRACT FROM AUTHOR]

In consideration of skyrocketing price in pavement materials and ever-increasing attention to environment preservation, the utilization of reclaimed asphalt pavement (RAP) into asphalt mixtures has gained more and more favor. However, the uniformity of virgin and RAP aggregate in recycled asphalt mixtures (RAM) has not yet been studied due to the difficulty in informational extraction of multi-structures. To address this, white dolomite was used as virgin aggregate to be distinguished from RAP aggregate based on their color difference. The shear gyratory compactor specimens of RAM were prepared and saw-cut, and then meso-structures including virgin aggregate, RAP aggregate and asphalt mortar were extracted using digital image processing (DIP) technology. The DIP processes mainly involved retention of blue channel for image graying, newly proposed double-threshold OTSU method for image segmentation and image morphology processing. The aggregate uniformity index (AUI) was proposed based on the coefficient of variation of aggregate area ratio. The influences of RAP that were pre-processed by refined decomposition (RD) and routine crushing (RC) and its content on the aggregate uniformity were evaluated. The results demonstrate the efficacy of the improved DIP approach, as evidenced by the maximum mean absolute error between laboratory-measured and image-estimated gradation that is lower than 7.8 %. The addition of RAP into asphalt mixtures is adverse to the aggregate uniformity. The higher the RAP content, the inferior the aggregate uniformity of RAM, which attributes to the agglomeration of RAP materials. RAP agglomeration leads to the heterogeneity of RAP aggregate and thus dominates the heterogeneity of the whole aggregate. Therefore, the aggregate uniformity of RAM produced by RD-RAP is superior to that produced by RC-RAP. The superior degree is 9 %. • Dolomite is used as virgin aggregate to distinguish from RAP aggregate. • Double-threshold OTSU method for image segmentation in the recycled asphalt mixtures is proposed. • RAP has adverse effect on the aggregate uniformity due to its agglomeration. • Recycled asphalt mixtures with refined decomposed RAP show superior aggregate uniformity than routine crushed RAP. [ABSTRACT FROM AUTHOR]

The loading stress path affects the soil's dynamic response, but there are few previous studies on bidirectional shearing, let alone considering the influence of phase difference and bidirectional shear frequencies. This study investigates the undrained responses of reconstituted saturated soft clay under four typical shear stress paths using a multidirectional cyclic simple test system. All the soil samples are consolidated under normal vertical stress sheared in undrained conditions by applying two horizontal shear stresses acting along different directions from the consolidation stress. Test results indicate that soft clay's dynamic strain, softening index, and dynamic strength depend significantly on the value of phase difference and the bidirectional shear frequencies: dynamic strength and softening index decrease while dynamic strain accumulates with increasing phase difference and decreasing bidirectional shear frequencies. An empirical formula is proposed to predict the development pattern of softening index versus load cycles under various shear paths based on test results. In this study, a series of simple shear tests was carried out under multidirectional shear paths, which may be helpful for field pile testing under cyclic loading. The simple shear tests all showed an increase in shear strain accumulation, owing to the change in shear stress path. This increase is undoubtedly smaller than the accumulation of lateral displacements in the pile tests because of the different boundary conditions and stress levels between the field and laboratory tests. Since soil behavior partly defines pile drifts, some models can also be validated at a small scale (element level) before investigating the pile–soil system. It is proposed that the simple shear test results can be used to calibrate numerical models for various stress paths. [ABSTRACT FROM AUTHOR]

The presence of loose medium backfill above the horizontal pillar will technically hinder the efficient recovery of the pillar since the improper design and preserved roof protection layer height will potentially lead to casualties and equipment damage caused by large area collapse of filled tailings as well as roof fall accidents. In this study, a safe and efficient technique for the recovery of isolated pillars under loose tailings backfill was carried out via field investigation, theoretical analysis, numerical simulation, and analytic hierarchy process using the isolated pillars in the 855 middle sublevel of Hongling Zinc-Lead Mine, Chifeng, Inner Mongolia, as a practical engineering background. Current studies have revealed that the optimal scheme for an isolated horizontal pillar recovered via the cut-and-fill stoping of a drift vertical to ore body strike involves preserving a 1.0-m roof protection layer above the crown pillar combined with a spaced mining extraction sequence. This design minimizes ore dilution and losses during the pillar extraction process under safe operation. Our research results provide theoretical and technical support for the safe and efficient recovery of isolated pillars under loose tailings backfill in similar mines. [ABSTRACT FROM AUTHOR]

Source-side virtual synchronous machines (VSGs) and load-side VSMs (LVSM) are gradually utilized together in the microgrid to provide virtual inertia and damping. However, instability occurs in the islanded microgrid system due to the interaction dynamics between the VSG and the LVSM, which has been investigated in this article. At first, the dq-frame impedance models of the VSG and the LVSM are established and compared. It is revealed that the d-d channel impedance of LVSM behaves the negative resistor with a V-type magnitude in the low-frequency range, which easily interacts with the d–d channel impedance of the VSG and leads to instability of the system. Thus, the inductor current feedforward control and the additional voltage feedback control are proposed for the VSG to reshape its impedance. It diminishes the impedance magnitude and generates the active impedance of the VSG. In this way, the low-frequency interaction between the VSG and the LVSM can be mitigated. Besides, the proposed control preserves the dynamic performance of the system. Finally, simulations and experiments verify the effectiveness of stability analyses and the proposed suppression method. [ABSTRACT FROM AUTHOR]

Integration development of urban agglomeration is important for regional economic research and management. In this paper, a method was proposed to study the integration development of urban agglomeration by trajectory gravity model. It can analyze the gravitational strength of the core city to other cities and characterize the spatial trajectory of its gravitational direction, expansion, etc. quantitatively. The main idea is to do the fitting analysis between the urban axes and the gravitational lines. The correlation coefficients retrieved from the fitting analysis can reflect the correlation of two indices. For the different cities in the same year, a higher value means a stronger relationship. There is a clear gravitational force between the cities when the value above 0.75. For the most cities in different years, the gravitational force between the core city with itself is increasing by years. At the same time, the direction of growth of the urban axes tends to increase in the direction of the gravitational force between cities. There is a clear tendency for the trajectories of the cities to move closer together. The proposed model was applied to the integration development of China Liaoning central urban agglomeration from 2008 to 2016. The results show that cities are constantly attracted to each other through urban gravity. [ABSTRACT FROM AUTHOR]

Linear reciprocating sliding friction and wear behavior in a Zr 55 Cu 30 Ni 5 Al 10 bulk metallic glass (BMG) at different sliding velocities was investigated. The friction and wear tests nearly have not changed the amorphous structure and thermal stability of the BMG. The sliding velocity significantly affects the friction and wear behavior of the BMG. During the frictional and wear tests, the average frictional coefficient locates between 0.244 and 0.302 and increases gradually with increasing sliding velocity. The grinding trace width locates between 36 μm and 227 μm and descends gradually with increasing sliding velocity. The grinding traces exhibit smooth linear furrows, on both sides of which some heaping alloy scraps can be observed, while at the ends of which these accumulation extent of surface alloy scraps becomes more serious. The smaller the sliding velocity is, the more serious the wear extent is. At smaller sliding velocities, the wear mechanism inclines to the combined effects of continuous wear, occlusion or bite welding, adhesive wear and abrasive wear. With the increase of sliding velocity, the wear mechanism changes gradually to a combined result of slight bite or bite welding and continuous wear. [ABSTRACT FROM AUTHOR]

Hydrogenation of CO 2 into methanol at low-temperature on Cu-based catalysts is of great significance, but remains challenging to enhance activity. In this paper, we report an inverse catalyst constructed with nano-ZrZnO x supported on Cu particles with outstanding methanol synthesis performance at 220 ℃, two times higher than that of commercial Cu/ZnO/Al 2 O 3 catalysts under the same conditions. Detailed structure characterization and performance evaluation demonstrate that the ZrZnO x mixed oxide serves as the most active oxide-metal interface site for CO 2 hydrogenation. The ZrZnO x /Cu inverse catalyst increases the weak and medium CO 2 adsorption sites which are further demonstrated responsible to the methanol productivity. In situ DRIFTs studies reveal that the inverse interface accelerates the reduction of asymmetric formate intermediates and prevents the generation of CO. The combination of enhanced CO 2 activation capability and accelerated hydrogenation rate of intermediates over the ZrZnO x /Cu inverse catalyst probably contribute to the remarkable methanol synthesis performance from CO 2. [Display omitted] • Inverse ZrZnO x /Cu is highly active for methanol synthesis from CO 2 hydrogenation. • The inverse catalyst shows room temperature methanol synthesis ability. • The formation of ZrZnO x nano-oxide is responsible for the extraordinary activity. • Inverse interface accelerates the reduction of adsorbed oxygenate intermediates. • Inverse interface inhibits the formation of CO intermediates. [ABSTRACT FROM AUTHOR]

This study evaluated the long-term therapeutic effect and prognostic factors of acute lymphoblastic leukemia (ALL) in 100 young Chinese children (<2 years old) who were enrolled in the Shanghai Children's Medical Center (SCMC)-ALL-2009 study in five pediatric hematological disease centers based on collaboration. The 5-year and 10-year event-free survivals (EFS) were 74.7 ± 3.2% and 73.3 ± 3.4%. The 10-year EFS rates for low risk, intermediate-risk, and high-risk patients were 81.9 ± 5.0%, 71.3 ± 4.3%, and 22.2 ± 13.9%, respectively. Relapse occurred in 19 patients. MRD results on day 55, good or poor response to prednisolone, and age at diagnosis were shown to have important prognostic and therapeutic implications. Compared with the SCMC-ALL-2005 protocol, showed that the 10-year-EFS and 10-year-overall survival of the SCMC-ALL-2009 protocol were better than that of the −2005 protocol. Notably, the intermediate-risk group was improved after the chemotherapy intensity was strengthened. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is a novel coronavirus and the cause of COVID-19. More than 80% of COVID-19 patients exhibit mild or moderate symptoms. In this study, we investigated the dynamics of viral load and antibodies against SARS-CoV-2 in a longitudinal cohort of COVID-19 patients with severe and mild/moderate diseases. Demographic and clinical information were obtained. Serial samples of blood, nasal and pharyngeal and anal swabs were collected at different time points post-onset. SARS-CoV-2 RNA and anti-SARS-CoV-2 antibodies were measured by qRT-PCR and immunoassays, respectively. Respiratory SARS-CoV-2 RNA was detectable in 58.0% (58/100) COVID-19 patients upon admission and lasted for a median of 13 days post-onset. In addition, 5.9% (1/17) and 20.2% (19/94) of the blood and anal swab specimens were positive for SARS-CoV-2 RNA, respectively. Anal viral RNA was more frequently detected in the patients who were positive for viral RNA in the respiratory samples upon admission. Specific anti-SARS-CoV-2 antibody developed within two weeks after onset, reached peak approximately 17 days post-onset and then maintained at relatively high level up to 50 days we analyzed in most patients. However, the levels of antibodies were variable among the patients. High titers of antibodies appeared to be associated with the severity of the disease. Furthermore, viral proteins from different sources showed significant difference of serological sensitivity especially during the first week post-onset. Our results indicate rapid clearance or self-elimination of viral RNA in about half of the COVID-19 patients upon admission. Viral RNA shedding of SARS-CoV-2 occurred in multiple tissues including the respiratory system, blood, and intestine. Variable levels of specific anti-SARS-CoV-2 antibody may be associated with disease severity. These findings have shed light on viral kinetics and antibody response in COVID-19 patients and provide scientific evidence for infection control and patient management. [ABSTRACT FROM AUTHOR]

Air booster vacuum preloading is a newly improved method applied in land reclamation projects. Highly pressurized air can provide an additional pressure difference between the prefabricated vertical drain (PVD) and injection point, thereby increasing the hydraulic gradient and generating small fractures that can improve the soil permeability and the transmission efficiency of the vacuum pressure. However, with a premature activation time, the pressurized air can create air channels connected to the PVD, which may drastically decrease the vacuum pressure. With a delayed activation time, the strength of the dredged clay may be too high to permit fractures, thus limiting the permeability improvement. In this study, soils with degrees of consolidation (DOCs) of 0%, 40%, 60%, and 80% were selected for testing the efficacy of initial booster activation times in four tests. The results show that the pressurizing groups were more effective in improving the consolidation of soils, and the best effect of the use of air booster is obtained when soil has been consolidated to a DOC of 60%. The lower soils of the pressurized groups showed greater increase rates than those demonstrated by conventional vacuum preloading. [ABSTRACT FROM AUTHOR]

• 1,2-DCE exposure induces brain edema through down-regulation of AQP4. • Deletion of AQP4 intensified 1,2-DCE-induced brain edema. • 1,2-DCE-induced dysregulation of miR-29b aggravates brain edema by directly targeting to AQP4. Overexposure to 1,2-dichloroethane (1,2-DCE) can induce brain edema, but the underlying mechanisms remain largely unknown. Aquaporin 4 (AQP4) is the most prevalent water channel in the brain, and the pool of AQP4 facilitates brain edema by controlling the inflow and clearance of brain water. MicroRNAs play an important role in the regulation of brain edema via RNA silencing and post-transcriptional regulation of gene expression. To explore the regulation role of AQP4 and microRNA in 1,2-DCE-induced brain edema, Sprague-Dawley (SD) rats and AQP4 knockout CD-1 mice were exposed to 1,2-DCE by inhalation for 7 days (0, 600, 1,800 mg/m3) and 28 days (0, 100, 350, 700 mg/m3), respectively. The results showed that 1,2-DCE induces brain edema, in both rats and mice, characterized by an increase in brain water content and vacuolations in the brain parenchyma and around the vessels of the cerebral cortex. Notably, 1,2-DCE exposure can down-regulate AQP4 expression, in both rats and mice. Also, deleting AQP4 intensifies 1,2-DCE-induced brain edema in mice. Meanwhile, microRNA-29b-3p (miR-29b) expression increases with 1,2-DCE exposure, in both rats and mice. A negative correlation was found between the expression of miR-29b and AQP4 in vivo. Moreover, the negative regulation of miR-29b by direct targeting to AQP4 was confirmed by dual luciferase reporter assay in vitro. Taken together, our findings indicate that AQP4 plays an important role in balancing water content in 1,2-DCE-induced brain edema. The dysregulation of miR-29b after 1,2-DCE exposure can aggravate brain edema by directly suppressing the expression of AQP4. [ABSTRACT FROM AUTHOR]

Background: Billions of dollars are invested annually by pharmaceutical companies in search of new options for treating hair loss conditions; nevertheless, the challenge remains. One major limitation to hair follicle research is the lack of effective and efficient drug screening systems using human cells. Organoids, three-dimensional in vitro structures derived from stem cells, provide new opportunities for studying organ development, tissue regeneration, and disease pathogenesis. The present study focuses on the formation of human hair follicle organoids. Methods: Scalp-derived dermal progenitor cells mixed with foreskin-derived epidermal stem cells at a 2:1 ratio aggregated in suspension to form hair follicle-like organoids, which were confirmed by immunostaining of hair follicle markers and by molecular dye labeling assays to analyze dermal and epidermal cell organization in those organoids. The hair-forming potential of organoids was examined using an in vivo transplantation assay. Results: Pre-aggregation of dermal and epidermal cells enhanced hair follicle formation in vivo. In vitro pre-aggregation initiated the interactions of epidermal and dermal progenitor cells resulting in activation of the WNT pathway and the formation of pear-shape structures, named type I aggregates. Cell-tracing analysis showed that the dermal and epidermal cells self-assembled into distinct epidermal and dermal compartments. Histologically, the type I aggregates expressed early hair follicle markers, suggesting the hair peg-like phase of hair follicle morphogenesis. The addition of recombinant WNT3a protein to the medium enhanced the formation of these aggregates, and the Wnt effect could be blocked by the WNT inhibitor, IWP2. Conclusions: In summary, our system supports the rapid formation of a large number of hair follicle organoids (type I aggregates). This system provides a platform for studying epithelial-mesenchymal interactions, for assessing inductive hair stem cells and for screening compounds that support hair follicle regeneration. [ABSTRACT FROM AUTHOR]

The premise that the virtual synchronous generator (VSG) can actively support the weak grid is that the VSG can operate stably. In this paper, the small-signal sequence impedance models of the voltage-controlled VSG and the current-controlled VSG are built and the sequence impedance characteristics of these two types of VSGs are compared and analyzed. The sequence impedance of the voltage-controlled VSG, being consistent with the grid impedance characteristics, is generally inductive. By contrast, the sequence impedance of the current-controlled VSG is mainly negative impedance in the middle- and high-frequency area and the impedance amplitude is quite low. Based on the built sequence impedance models and the impedance stability criterion, the influence of the weakness of the grid on the stability of these two types of VSG grid-connected system is analyzed. The results of stability analysis show that the current-controlled VSG is prone to instability while the voltage-controlled VSG remains stable. Therefore, the voltage-controlled VSG is more suitable than the current-controlled VSG for grid-connected renewable energy generation in an ultraweak grid from the point of view of system stability. Finally, experiment results validate the stability analysis. [ABSTRACT FROM AUTHOR]

Abstract Effect of microalloying on microstructure, magnetic properties and bending ductility of the Fe 85.7-85.8 Si 0.5 B 9-9.3 P 3.5-4 Cu 0.5-0.8 C 0.2-0.3 alloy ribbons with high Fe content was systematically investigated. It is found that the substitution of 0.1 at. % Cu or 0.2 at. % Cu for (B+P) content inhibits the crystallization and improves the amorphous forming ability of melt-spun Fe 85.7-85.8 Si 0.5 B 9-9.3 P 3.5-3.9 Cu 0.6-0.7 C 0.2-0.3 alloys. The first crystallization temperature (T x1) increases slightly with the addition of C or P content, while the second crystallization temperature (T x2) exhibits a slightly decrease. All amorphous alloys exhibit a large temperature interval between T x1 and T x2 , which contributes to the thermal stability and leads to the formation of a single α-Fe phase. In the as-spun state, the amorphous alloys have good bending ductility even at high Fe content. After the optimum heat treatments, the Fe 85.7-85.8 Si 0.5 B 9-9.3 P 3.5-3.9 Cu 0.6-0.7 C 0.2-0.3 nanocrystalline alloys exhibits the excellent soft magnetic properties, such as the highest Ms of 206.4–210.2 emu/g (Bs ≈ 1.95–1.98 T) and the lowest Hc of 6.5–8.4 A/m. Highlights • Substitution of Cu for (B+P) in FeSiBPCuC alloy increases amorphous forming ability. • The alloys exhibit higher Ms of 206.4–210.2 emu/g and lower Hc of 6.5–8.4 A/m. • Even at high Fe content, the amorphous alloys exhibit good bending ductility. [ABSTRACT FROM AUTHOR]

Abstract CZTS thin films were prepared by adding microwave radiation to the sol-gel method. Microwave treatment was performed after sol-gel drying process. The CZTS thin films were analyzed by XRD, Raman, SEM, and UV–Vis spectrophotometer to investigate the influence of microwave irradiation time. The results showed that the microwave treatment promoted the initial formation of the CZTS phase. The crystallinity of the CZTS thin film was improved during the subsequent annealing. With the increase of microwave treatment time, the crystallinity of the annealed CZTS thin films first enhanced and then decreased. When the microwave treatment time was 25 min, the CZTS thin films reached the highest crystallinity with the maximum particle size of about 500 nm. EDS analysis indicated that the compositions of thin films showed Cu-poor properties. The direct optical band gaps of CZTS thin films were 1.58–1.61 eV. The experimental results revealed that the microwave radiation method could improve the properties of sol-gel processed CZTS thin films. Highlights • CZTS thin films were prepared by a microwave assisted sol-gel method. • The effects of microwave treatment time on the film were studied. • The properties of CZTS thin films were improved by microwave radiation. [ABSTRACT FROM AUTHOR]