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Revealing the relationship among the machining parameters, surface topography, and functionality-related properties of the machined surface is crucial for obtaining micro-milling surfaces with good functional performance. In the present study, slot micro-milling Ti6Al4V was conducted to investigate the effect of machining parameters on the 3D surface topography, with an emphasis on surface defects, the 3D surface texture parameters, and functionality-related properties of the machined surface. The results show that the 3D surface topography of the machined surface presents obvious anisotropy in slot micro-milling Ti6Al4V. The 2D surface profile shows the non-uniformity along the slot width direction in slot micro-milling Ti6Al4V. The surface defects with different machining parameters are various, such as deep and large feed marks of single cutting, narrow and small feed marks of single cutting, feed marks of multi-cutting, scratch marks, scratch pit, surface tearing, tear pit, back-cutting marks, and metal debris. With the consideration of cutting processing efficiency and surface roughness Sa, it is suggested to adopt the high spindle speed and large depth of cut. At the same time, feed per tooth that is near the minimum cutting thickness is recommended to obtain the minimum surface roughness with the balance of chip thickness accumulation effect and chip removal or surface formation. Moreover, the functionality-related properties of the machined surface, e.g. friction or abrasion contact behaviors, load-bearing capacity, fluid retention properties, fatigue performance, and the machining parameter effect were evaluated with surface texture parameters, such as amplitude parameters, spatial parameters, hybrid parameters, and functional or volume parameters. Our findings are of great significance for shedding light on the relationship between the surface formation mechanism, surface topography, and functionality-related properties of machined surfaces in micro-milling Ti6Al4V. [ABSTRACT FROM AUTHOR]

Surface roughness and residual stress are related to the fatigue life of finished parts. However, experimental investigations lack a deep discussion about the cutting mechanism. Orthogonal cutting simulation for milling or two-dimensional finite element model is the simplification of the actual milling process, which makes it difficult to reflect the milling characteristic in the simulation. In the present study, a three-dimensional coupled thermo-mechanical simulation model was established to analyze the surface roughness and residual stress in milling 5083 aluminum alloy. Explicit dynamic analysis was used as the solution algorithm for the milling process. Implicit analysis was adopted to simulate the process of unloading and cooling. Mesh sensitivity analysis was conducted to identify the mesh size of the workpiece. Node displacement and stress information were output to calculate the surface roughness and residual stress. The effects of cutting parameters on surface roughness and residual stress were discussed by the simulation model. Moreover, milling experiments were conducted to validate the simulation results. It is observed that the surface roughness of the simulation and experiment shows the same trend with the increase of feed per tooth and depth of the cut, which verifies the simulation model. Moreover, the superficial residual stress of the machined surface is the result of the coupled thermo-mechanical with the compressed effect of the tool, the tensile effect of the tool, and thermal load. The superficial residual stress of the machined surface presents compressive stress at a different feed per tooth and spindle speeds. Current findings provide insights for understanding the formation mechanism of the surface topography and residual stress in milling aluminum alloy. [ABSTRACT FROM AUTHOR]

In this paper, three new species of the tribe Anthocoptini from China are described and illustrated. They are Aculops grewiaesp. nov. infesting Grewia biloba G.Don. (Malvaceae), Aculops koelreuteriaesp. nov. infesting Koelreuteria paniculata Laxm. (Sapindaceae) and Tegolophus pogonatherisp. nov. infesting Pogonatherum crinitum (Thunb.) Kunth (Poaceae). All of them are vagrants on lower leaf surface and cause no apparent symptom to their host plants. [ABSTRACT FROM AUTHOR]

In order to effectively mitigate the oxidation reactions of coal (RC) and gangue (RG) at low temperatures, a comprehensive study was conducted on the mineral composition, structural characteristics, and oxidation behaviors of RC and RG from the same coal seam. Additionally, the thermodynamic attributes of their oxidation processes were evaluated. The results indicate that the mineral composition of RC and RG is similar, primarily comprising kaolinite. However, there are substantial differences in structural characteristics, with RG exhibiting a more stable structure, smaller aromatic layer spacing, and higher degree of graphitization. Additionally, the molecular arrangement is densely packed and orderly, displaying characteristics akin to those of " highly metamorphic coal-like ". RC has a high content of aromatic hydrocarbons and aliphatic hydrocarbons, with long side chains, rendering it more susceptible to oxidation and possessing stronger combustion activity. Upon entry into the oxidation process, RG exhibits a lower initial exothermic temperature due to its strong thermal conductivity and large thermal diffusion coefficient. However, it simultaneously has fewer active functional groups and a higher ash content, limiting its sustained exothermic capacity and prolonging the processes of slow endothermic and rapid exothermic reactions. Conversely, RC, with its high carbon content and abundant active substances, releases heat during oxidation that is 1.7–3.5 times greater than that of RG. Importantly, when RC and RG oxidize together, they exhibit a synergistic effect, promoting the reaction. In the slow endothermic stage, the average activation energy required for CG is 2.64 kJ·mol−1 lower than that for RC. In the rapid exothermic and slow exothermic stages, the actual heat release of CG exceeds the theoretical heat release by 15.95–64.71 J·g−1 and 13.88–56.77 J·g−1, respectively. [ABSTRACT FROM AUTHOR]

Micro-milling force and specific cutting energy play an important role in revealing the micro-milling mechanism. However, it is quite difficult to compare the micro-milling force values from different experiments due to the lack of a representative cutting force parameter to comprehensively evaluate the micro-milling force. Especially, there is no unified formula to accurately calculate the specific cutting energy in micro-milling due to variable chip cross-sectional area and periodically varying micro-milling force. In this work, the micro-milling force was systematically analyzed with fast Fourier transform spectrum analysis, curve shape, and representative parameter evaluation. The quasi-dynamic cutting force, which is represented by the P–V value of cutting force, was adopted to comprehensively evaluate the micro-milling force. The specific cutting energy was calculated with the ratio of quasi-dynamic cutting force and the average undeformed chip thickness. Moreover, the variable regularity of quasi-dynamic cutting force and specific cutting energy on cutting parameters were obtained with the micro-milling experiment. The results show that the quasi-dynamic cutting force first decreases and then increases with the increase of feed per tooth due to the chip accumulation effect. With the increase of spindle speed and depth of cut, the quasi-dynamic cutting force decreases and increases, respectively. The minimum undeformed chip thickness is between 0.3 and 0.5 μm, which is around 0.19 to 0.32 of tool edge radius in micro-milling Ti6Al4V. With the increase of spindle speed and depth of cut, the specific cutting energy shows a decreasing trend and changes a little, respectively. With the decrease of the feed per tooth, the specific cutting force shows a nonlinear increase. Our findings are of great significance for further scientific understanding the micro-milling mechanism from the perspective of cutting force and specific cutting energy. [ABSTRACT FROM AUTHOR]

Instructors' speech and gestures are tightly integrated. However, little is known about the neural mechanisms by which different types of gestures affect learning. We conducted two experiments on the effects of gestures in video lectures that included an instructor and slides, with English vocabulary as the topic. In Experiment 1, we manipulated the instructor's gestures (beat gestures vs. pointing gestures vs. depictive gestures) on neural oscillations and learning performance. The electroencephalogram results showed that students had higher alpha power and higher beta power when the instructor used pointing gestures, suggesting lower sensorimotor involvement in processing. Pointing gestures produced lower learning performance than beat gestures and depictive gestures. In Experiment 2, we manipulated the instructor's pointing gestures and the richness of visual materials in video lectures. The results showed that the effectiveness of pointing gestures was moderated by the richness of the visual materials on the slide. Specifically, pointing gestures were more effective for complex versus simple learning materials. The findings suggest that electroencephalogram oscillations and learning performance vary with the type of gesture the instructor uses and the richness of visual materials in video lectures. This study has applied value for designing effective video lectures in many disciplines: (1) When a video lecture includes simple visual materials, a beat gesture and depictive gesture would be better; (2) when a video lecture includes complex visual materials, the instructor can produce pointing gestures to single out the learning content they are talking about. Practitioner notesWhat is already known about this topic Instructors commonly produce gestures while they teach, and their gestures and speech are tightly integrated.Instructors often use three types of gestures: beat gestures, pointing gestures and depictive gestures.Different types of gestures influence learning via different neural mechanisms.What this paper adds Students' alpha power and beta power had lower amplitudes when observing an instructor's beat gestures, compared to pointing and depictive gestures.Students showed higher learning performance after viewing the video lectures with the instructor's beat and depictive gestures.An instructor's pointing gestures facilitated learning performance primarily in video lectures with complex visual materials (CVM) rather than simple visual material (SVM).Implications for practice and/or policy When a video lecture includes SVM, the instructor is encouraged to produce beat gestures and depictive gestures rather than pointing gestures.When a video lecture includes CVM, the instructor is encouraged to produce pointing gestures to single out the learning content they are talking about. [ABSTRACT FROM AUTHOR]

The development of geothermal power generation in recent years has not given cause for optimism, and the reasons behind this situation are complicated. Nevertheless, if the global geothermal power generation market is studied, some interesting phenomena are revealed. First, the development of geothermal power generation around the world is unbalanced and highly correlated with the distribution of geothermal resources; therefore, the geothermal power generation potential in each country is examined and candidate countries are selected to analyze this unbalanced global development. Further, considering that the exploitation of energy does not rest solely on resource endowment and that the market is a critical factor, the factors that may influence the market are identified by studying the history of global geothermal power generation. Although the influencing factors in each country are not the same, the analysis indicates that factors such as a country's energy strategy, energy resource location, and the sustainable development of geothermal resources play critical roles in the development of geothermal power generation. Finally, the resource endowment is jointly considered with the main factors that influence the market to create a well-organized analytical framework for other researchers. The proposed analytical framework is then applied to make a tentative preliminary judgment about the development of geothermal power generation in China. The analysis shows that China has considerable potential for geothermal power generation; however, the development prospects under the current conditions are not promising. • GPG development correlates with distribution of medium-high temperature resources. • Critical external factors influencing the development of GPG are also discussed. • Geothermal power generation in China is not promising based on current conditions. [ABSTRACT FROM AUTHOR]

• The gangue micropores are converted into mesopores and macropores. • The content of various functional groups increased and reached the maximum at S60. • Dry cracking temperature increases, other characteristic temperatures decrease. • The combustion properties all following the chemical reaction mechanism(n = 3). A large amount of coal gangue (CG) produced in coal mining accumulates to form CG hills, and the combustion properties change under the effect of leaching, increasing the risk of spontaneous combustion. The study was mainly carried out by nitrogen adsorption, infrared spectroscopy and thermogravimetry on the physicochemical properties of the CG under different immersion times (30, 60, 90 days). And the activation energy of the immersion CG at different oxidation or combustion states was calculated. The results show that the pyrite contained in gangue is oxidized after immersion, and the heat released by oxidation and the acid solution formed have an obvious effect on the pore expansion of gangue. The mesoporous and macroporous increase by 2.61% and 0.95% respectively, which strengthens the physical and chemical adsorption of oxygen for CG. The immersion process also destroys the structure of the gangue, transforming stable functional groups into active ones, especially the most significant increase in hydroxyl and oxygen-containing functional groups. The characteristic temperature changed under the action of water immersion, the cracking temperature increased, and other characteristic temperatures decreased, among which the ignition temperature decreased by about 20℃. In addition, the water immersion process inhibits the low-temperature oxidation stage of CG and promotes the high-temperature combustion stage, and the risk of spontaneous combustion is the strongest after 60 days of immersion in water. The results can provide guidance for the prevention of spontaneous combustion in drenched CG hills. [ABSTRACT FROM AUTHOR]

The crushing behavior of foamed concrete is utilized to assess the arresting properties of the Engineered Materials Arresting System (EMAS). In this study, polypropylene fibers (PPF) are used to improve the crushing behavior of foamed concrete with and without wet-dry cycles. The results indicate that the compressive strength, initial crushing stress and maximum energy absorption efficiency of foamed concrete with 0.6 % PPF is increased by 71.89 %, 60.85 % and 9.52 %, respectively. After 30 wet-dry cycles, the above three parameters are reduced to 0.21 MPa, 0.71 MPa, and 0.42, respectively, for foamed concrete without fibers, and 0.28 MPa, 0.97 MPa, and 0.44 for foamed concrete with 0.6 % PPF. The analysis based on the tire/foam interface model reveals the potential reduction of the arresting force on the landing gear caused by wet-dry cycles while the fiber reinforcement could partially offset this deterioration. Adding PPF to foamed concrete for EMAS construction has the potential to optimize cement costs and enhance arresting properties. • Crushing behavior of foamed concrete was utilized to assess the arresting properties of EMAS. • Polypropylene fibers (PPF) were used to improve the crushing behavior of foamed concrete with and without wet-dry cycles. • In the range of 0.2–1.0 % PPF fiber content, the best improvement is achieved at 0.6 % fiber content. [ABSTRACT FROM AUTHOR]

In this paper, three new species of eriophyoid mites from Guangxi, China, are described and illustrated. They are as follows: Paraphytoptus niveaesp. nov. infesting Boehmeria nivea (L.) Gaudich. (Urticaceae), Boczekiana broussonetiaesp. nov. infesting Broussonetia papyrifera (L.) L'Hér. ex Vent. (Moraceae), and Trimeroptes kaempferisp. nov. infesting Broussonetia kaempferi Siebold (Moraceae). All three new species are vagrants on the lower leaf surface and cause no apparent symptom to their host plants. [ABSTRACT FROM AUTHOR]

Nanoindentation and nanoscratch tests of YAG single crystals were systematically performed. The mechanical properties including elastic recovery rate, elastic modulus, nano hardness and fracture toughness of YAG single crystals were obtained by the nanoindentation tests. The surface morphologies of the scratched grooves were analysed using scanning electron microscopy. The formation characteristics of YAG single crystals induced by varied-depth nanoscratch indicated that there was distinct brittle-to-ductile transition phenomenon during the scratching process. Surface radial cracks occurred prior to the edge-breaking phenomenon, and transverse cracks extending to the surface of the work material dominated the brittle removal of YAG single crystals. A theoretical model of the edge-breaking size during the nanoscratch process was developed by considering the stress intensity factor, elastic recovery rate, and residual force. This model indicated that the edge-breaking size increased as the normal force, average elastic recovery rate and elastic modulus increased, but decreased as the nanoindenter tip radius, fracture toughness and nano hardness increased. When the average elastic recovery rate was within 17.5%–20% (the maximum elastic recovery rate was within 35%–40%), the values predicted by the theoretical model agreed well with the experimental values, and the average error was less than 5%. The model could provide theoretical guidance for analysing the surface generation characteristics of brittle solid materials during the abrasive processing at brittle removal regime. [ABSTRACT FROM AUTHOR]

Vision-based Continuous Sign Language Recognition (CSLR) is a challenging and weakly supervised task aimed at segmenting sign language from weakly annotated image stream sequences for recognition. Compared with Isolated Sign Language Recognition (ISLR), the biggest challenge of this work is that the image stream sequences have ambiguous time boundaries. Recent CSLR works have shown that the visual-level sign language recognition task focuses on image stream feature extraction and feature alignment, and overfitting is the most critical problem in the CSLR training process. After investigating the advanced CSLR models in recent years, we have identified that the key to this study is the adequate training of the feature extractor. Therefore, this paper proposes a CSLR model with Multi-state Feature Optimization (MFO), which is based on Fully Convolutional Network (FCN) and Connectionist Temporal Classification (CTC). The MFO mechanism supervises the multiple states of each Sign Gloss in the modeling process and provides more refined labels for training the CTC decoder, which can effectively solve the overfitting problem caused by training, while also significantly reducing the training cost in time. We validate the MFO method on the popular CSLR dataset and demonstrate that the model has better performance. [ABSTRACT FROM AUTHOR]

When the gas explosion occurs in a coal mine, the pressure wave will induce coal dust (CD) to participate in the explosion reaction, which will further expand the accident and eventually cause more serious casualties. Based on this hazard, experiments were performed on three representative types of CD with the aid of a self-built experimental pipeline for gas/CD explosion. The explosion characteristics under the condition that pressure waves entrain different CD to participate in the explosion were studied. Furthermore, the influence of volatile content in CD on the compound explosion was analyzed from a microscopic perspective. The following beneficial conclusions were obtained: The overpressure peak value and the flame propagation velocity in the compound explosion are positively correlated with the volatile content in CD. Under those three conditions, the maximum overpressure is obtained at P2 position, and obvious stratification occurs in the process of flame propagation. However, compared with the other two working conditions, the average flame propagation speed of the composite explosion system with anthracite decreased by 51.2% and 52.6%, respectively, and flame surface breaks and becomes discontinuous earlier. After the explosion, the volatile content of three kinds of CD is significantly reduced, and the volatile content of lignite, bituminous coal and anthracite is 75.6%, 75.7% and 44.7% of the industrial analysis value of raw coal, respectively. With reference to the analysis on the microscopic test results, the amount of volatile gas decomposed from volatiles determines the intensity of the homogeneous reaction in the whole combustion process, while the coke formed after the reaction determines the intensity of the non-homogeneous reaction. Therefore, the volatile content in CD is a key factor affecting CD explosion. The research results provide an important scientific and theoretical basis for the prevention, control and reduction of CD explosion disasters. [ABSTRACT FROM AUTHOR]

In recent years, geographically weighted regression (GWR) models have been widely used to address the spatial heterogeneity and spatial autocorrelation of PM2.5, but these studies have not fully considered the effects of all potential variables on PM2.5 variation and have rarely optimized the models for residuals. Therefore, we first propose a modified GWR model based on principal component analysis (PCA-GWR), then introduce five different spatial interpolation methods of radial basis functions to correct the residuals of the PCA-GWR model, and finally construct five combinations of residual correction models to estimate regional PM2.5 concentrations. The results show that (1) the PCA-GWR model can fully consider the contributions of all potential explanatory variables to estimate PM2.5 concentrations and minimize the multicollinearity among explanatory variables, and the PM2.5 estimation accuracy and the fitting effect of the PCA-GWR model are better than the original GWR model. (2) All five residual correction combination models can better achieve the residual correction optimization of the PCA-GWR model, among which the PCA-GWR model corrected by Multiquadric Spline (MS) residual interpolation (PCA-GWRMS) has the most obvious accuracy improvement and more stable generalizability at different time scales. Therefore, the residual correction of PCA-GWR models using spatial interpolation methods is effective and feasible, and the results can provide references for regional PM2.5 spatial estimation and spatiotemporal mapping. (3) The PM2.5 concentrations in the study area are high in winter months (January, February, December) and low in summer months (June, July, August), and spatially, PM2.5 concentrations show a distribution of high north and low south. [ABSTRACT FROM AUTHOR]

In this study, a novel β -1,3-glucan recognition protein gene (β-GRP) was identified from Melanotus cribricollis , and its potential role in the immune response was investigated. The full length of β-GRP cDNA (Accession Number: MT941530) was 1644 bp, encoding a protein composed of 428 amino acids. The theoretical molecular weight and the isoelectric point were 51.53 kDa and 6.17, respectively. The amino acid sequence of β -GRP from M. cribricollis was closely related to that of. β- GRP-like from Photinus pyralis , and was predicted to contain conserved GH16 domain without glucanase active site. The results of real-time quantitative PCR showed that fungal infection of Metarhizium pingshaense may significantly upregulated the expression level of β-GRP gene. The RNAi suppression of β-GRP gene expression significantly increased the corrected cumulative mortality. Meanwhile, antimicrobial peptide genes defensin and lysozyme were significantly downregulated after interference of β-GRP. Taken together, these results suggest that β-GRP of M. cribricollis probably participates in the host immune system by mediating the expression of antimicrobial peptides. This study provides comprehensive insights into the innate immune system of insect larvae. [ABSTRACT FROM AUTHOR]

• The investigation of surface mid-frequency waviness and machine tool vibration from diverse sources is conducted through micro-planning experiments. The research delves into the influence of cutting conditions on vibration and mid-frequency waviness. • The influence of various components within the cutting force on vibration and mid-frequency waviness in UPM is elucidated through the acquisition, processing, and analysis of cutting force data. • The study discovered a discrepancy in the influence of cutting force on the vibration of stationary and moving components. Cutting force serves as the main excitation source for the vibration of the stationary part, while it exhibits an impedance role in the vibration of the moving part. • The research revealed that the stability and attenuation of the waviness caused by the stationary and moving parts vibration are different spatially and temporally. In addition to the dynamic characteristics of the machine tool, cutting conditions significantly influences the vibration of the cutting system and mid-frequency waviness of the workpiece surface in ultra-precision machining (UPM). In this work, the effects of cutting conditions on machining vibration and surface waviness were investigated by high-speed micro-planning experiments. The origin of vibration and waviness were elucidated by frequency-domain processing of the vibration signal and surface waviness analysis. The dynamic characteristics of machine tool are determined using modal test and analysis. The results revealed that the cutting force has different contributions to the workpiece vibration and tool vibration. In the time domain, distinct differences can be found in stability and attenuation of various waviness components. The divergent effects of cutting force components in different vibration forms are confirmed through a novel cutting force model of micro-planing. The investigation can further reveal the formation mechanisms of cutting system vibration and surface waviness during the micro-cutting process, which can provide practical guidance for suppressing mid-frequency waviness on machined surfaces. [ABSTRACT FROM AUTHOR]

Recent developments in the in-situ transformation of coal resources have heightened the possibility of exploring the oxidized coal regasification in coalfield fires. For further understanding the regasification characteristics of oxidized lignite residues in coalfield fire, Shengli lignite was selected for conducting ultra-lean oxygen pre-oxidation under different isothermal temperatures and CO 2 regasification experiments. Fourier transform infrared spectroscopy results indicate that higher temperature leads to the increase of aromatic hydrocarbon and reduction of aliphatic hydrocarbon side chains on the coal structure. It is found that the pre-oxidation of under 1% oxygen concentration and 300 °C will increase the specific surface area and pore volume, which would be beneficial for the following regasification. The analysis of gasification parameters suggests that the gasification quality and performance of lignite residues decline with the increasing oxygen concentration and rising isothermal temperatures in pre-oxidation. The kinetic analysis demonstrates that when the oxygen concentration ranges from 1% to 5%, the activation energy of gasification increases by 16.744 kJ/mol. The findings suggest that the lignite pre-oxidation under ultra-lean oxygen conditions will inevitably increase the activation energy of CO 2 gasification, which causes the coal more difficult to be utilized effectively. • The structural characteristics of lignite oxidized residues were analyzed by FT-IR. • The gasification performance of lignite residues was revealed. • The pre-oxidation with ultra-lean oxygen increases the activation energy of CO 2 regasification. • There exists dynamic compensation effect of the lignite residues in regasification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Potent and selective HDAC6 inhibitors based on the Tetrahydro- β -carboline scaffold. • Computational simulations suggested the key interactions between representative 11d and HDAC6. • 11d exhibited promising neurite outgrowth-promoting activity and neuroprotective activity. Histone deacetylase 6 (HDAC6) has drawn more and more attention for its potential application in Alzheimer's disease (AD) therapy. A series of tetrahydro- β -carboline (TH β C) hydroxamic acids with aryl linker were synthesized. In enzymatic assay, all compounds exhibited nanomolar IC 50 values. The most promising compound 11d preferentially inhibited HDAC6 (IC 50 , 8.64 nM) with approximately 149-fold selectivity over HDAC1. Molecular simulation revealed that the hydroxamic acid of 11d could bind to the zinc ion by a bidentate chelating manner. In vitro, 11d induced neurite outgrowth of PC12 cells without producing toxic effects and showed obvious neuroprotective activity in a model of H 2 O 2 -induced oxidative stress. [ABSTRACT FROM AUTHOR]

• Self-sensing property of cement-based sensors under flexural load is unsatisfactory. • PVA fibers increase the electrical resistivity of cement-based sensors. • PVA fibers enhance stress–strain sensing of cement-based sensors under flexural load. Cement-based sensors have great potential for structural health monitoring, especially carbon fiber filled functional sensors. In order to improve the sensing efficiency of carbon fiber reinforced cement-based sensors under cyclic flexural loading, polyvinyl alcohol (PVA) fibers were incorporated into cement-based sensors. The PVA fibers, although increasing the electrical resistivity, significantly improved the strain and stress self-sensing properties of carbon fiber reinforced cement-based sensors under cyclic flexural loading. This study provides a new way to accurately measure the parameters of cement-based sensors under cyclic flexural loading. [ABSTRACT FROM AUTHOR]

• R 3 -CH structure especially the H atom is the most active site in coal self-heating with oxygen. • The free energy barrier of oxygen attacking R 3 -CH site is 8.28 kJ/mol. • The aromatic hydrocarbon radicals and hydroxyl radicals are significant for coal self-heating. • The carbon radical combining with an O plays a vital role in initial coal spontaneous combustion. R 3 -CH structure is a typical active group during coal self-heating. In this paper, Ph-CH(CH 3)–CH 2 -Ph was selected to analyze reaction activity as well as mechanism between R 3 -CH structure and oxygen in coal self-heating by Multiwfn and Gaussian calculation. The results demonstrate that R 3 -CH structure especially the H atom is the most active site in coal self-heating with oxygen. The oxygen attacks R 3 -CH site in the Ph-CH(CH 3)–CH 2 -Ph, which results in the breaking of C–H bond and formation of O–H bond. The free energy barrier of this oxidation reaction is 8.28 kJ/mol and the heat release of the process is 86.89 kJ/mol, which indicates that it can easily occur at room temperature. From the perspective of products, the aromatic hydrocarbon radicals and hydroxyl radicals related to the initial spontaneous combustion of coal are generated, which is of great significance for the further development of coal self-heating. Subsequently, the carbon radical is combined with a single oxygen atom to generate oxygen-containing free radical which plays vital roles in initial coal spontaneous combustion. [ABSTRACT FROM AUTHOR]

• A large-area, periodic porous Au nanoparticle (PGNP) array is fabricated. • The morphology of the PGNP can be easily tailored. • The PGNP arrays exhibit outstanding SERS activities and excellent reproducibility. • The PGNP arrays show excellent polarization independence for SERS performances. Porous noble metal nanoparticles have attracted great attention in surface enhanced Raman scattering (SERS) applications due to the presence of high-density and built-in hotspots. Herein, we develop a facile route to fabricate large-area, periodic porous Au nanoparticle (PGNP) array based on ultra-thin alumina membrane (UTAM) incorporated with annealing and dealloying techniques. The size and ligament of the PGNP can be easily tailored by changing the thickness of the deposited Au/Ag film and the dealloying time. The PGNP array exhibits excellent uniformity and high sensitivity in SERS analysis due to the periodic structure and the enormous built-in hotspots. A large Raman enhancement factor (EF) of 1.4 × 107 is achieved with a relative standard deviation (RSD) less than 6.6%. Furthermore, experimental results and numerical simulations demonstrate that this PGNP array substrate exhibit polarization independence. The facile and controllable fabrication strategy makes the substrate promising for practical applications in many SERS-based qualitative and quantitative analyses. [ABSTRACT FROM AUTHOR]

Thin-walled micro parts are widely used in many fields, such as aviation, aerospace, precision engineering, and even micro-molds. Compared with other micro-fabrication technology, micro-milling can be considered as one of the most efficient 3D fabrication techniques. However, due to the vulnerable stiffness of thin-walled micro parts and micro tools, regenerative chatter is prone to occur during the micro-milling process. Severe chatter can lead to large fluctuations in cutting forces, resulting in deterioration of surface roughness/integrity and decreasing in tool life. Therefore, an in-process chatter detection strategy based on the feature extraction of micro-milling forces is proposed in this paper. Micro-milling force signals are measured and processed by advanced algorithms developed. After variational mode decomposition (VMD) for each group of cutting forces, the optimal intrinsic mode function (IMF) is adopted based on the Laplacian score (LS). The multi-scale permutation entropy (MSPE) values of the optimal IMF of each group are calculated, wherein the scale factor s , the embedding dimension m , and the delay time t are obtained by the genetic algorithm (GA). The obtained MSPE values are used as input vectors to train the support vector machine (SVM) classifier, which is used to monitor the stability states of the micro-milling processes. The effectiveness of the proposed strategy is compared with the other classic chatter detection methods and indicators in the micro-milling experiments of thin-walled parts. The results show that the method resulted from the strategy can extract cutting force features effectively and in-process detect chatters accurately in micro-milling thin-walled parts processes. [ABSTRACT FROM AUTHOR]

The effect of titanium-alloying on microstructure and mechanical properties of Fe35Ni35Cr20Mn10 high-entropy alloy (HEA) was studied. The microstructure was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical properties were examined by tensile and hardness tests. After the homogenization treatment at 1000 °C for 12 h, a great amount of thick/thin η flakes are observed to form at the grain boundaries, regularly intersect-arraying with specific directions that form η-locks. It is found that both the thick and thin η-Ni 3 Ti flakes are well coherent with face-centered cubic (FCC) matrix. Ti-alloying makes the homogenized Fe35Ni35Cr20Mn10 HEA possess high yield strength (331 MPa) and excellent ductility (47.2% in elongation), exhibiting a better strength-ductility. The remarkable rise in yield strength is from fine grain strengthening, dislocation hardening and second phase strengthening that are induced by Ti alloying. The refinement of grains induced by Ti alloying, the formation of a number of clear dislocation cells in FCC matrix and many stacking faults in FCC matrix and inside η flakes during the tensile deformation, and especially the coordinated deformation between η flakes and matrix, are thought to be responsible for the excellent ductility. The excellent strength-ductility in homogenized (Fe35Ni35Cr20Mn10) 95.3 Ti 4.7 HEA is, more importantly, due to the formation of regular intersect-arraying of η flakes (η-locks) with specific directions. The thick/thin η flakes are all along keeping the coherent relationship with FCC matrix during the total tensile deformation and hence can coordinately deform with the matrix. • Thick/thin η flakes are regularly intersect-arraying that form η-locks. • The thick/thin η flakes in η-locks are well coherent with FCC matrix. • The prepared HEA exhibits an excellent strength-ductility. • The η flakes keep the coherent relationship with FCC matrix during tensile deformation. • It is found that η flakes can coordinately deform with the matrix. [ABSTRACT FROM AUTHOR]

The sympathetic nervous system regulates bone formation and resorption under physiological conditions. However, it is still unclear how the sympathetic nerves affect stem cell migration and differentiation in bone regeneration. Distraction osteogenesis is an ideal model of bone regeneration due to its special nature as a self-engineering tissue. In this study, a rat model of mandibular distraction osteogenesis with transection of cervical sympathetic trunk was used to demonstrate that sympathetic denervation can deplete norepinephrine (NE) in distraction-induced bone callus, down-regulate β3-adrenergic receptor (adrb3) in bone marrow mesenchymal stem cells (MSCs), and promote MSC migration from perivascular regions to bone-forming units. An invitro Transwell assay was here used to demonstrate that NE can inhibit stroma-derived factor-1 (SDF-1)-induced MSC migration and expression of the migration-related gene matrix metalloproteinase-2 (MMP-2) and downregulate that of the anti-migration gene tissue inhibitor of metalloproteinase-3 (TIMP-3). Knockdown of adrb3 using siRNA abolishes inhibition of MSC migration. An in vitro osteogenic assay was used to show that NE can inhibit the formation of MSC bone nodules and expression of the osteogenic marker genes alkaline phosphatase (ALP), osteocalcin (OCN), and runt-related transcription factor-2 (RUNX2), but knockdown of adrb3 by siRNA can abolish such inhibition of the osteogenic differentiation of MSCs. It is here concluded that sympathetic denervation-induced MSC mobilization in rat mandibular distraction osteogenesis is associated with inhibition of MSC migration and osteogenic differentiation by NE/adrb3 in vitro. These findings may facilitate understanding of the relationship of MSC mobilization and sympathetic nervous system across a wide spectrum of tissue regeneration processes. [ABSTRACT FROM AUTHOR]

The fungus Alternaria alternata is a common spot-producing plant pathogen. During the past decade, tobacco brown spot disease caused by this fungus has became prevalent in China and lead to significant losses. To better understand the molecular pathogenesis of this fungus, the aapk1 gene encoding a cAMP-dependent protein kinase catalytic subunit was cloned, sequenced and characterized. The aapk1 deletion mutants were identified from hygromycin-resistant transformants by PCR strategy and confirmed by Southern blot analysis and RT-PCR. The aapk1 deletion mutant exhibited reduced vegetative growth and was less toxic than the wild-type strain sd1. Deletion of aapk1 also delayed disease development on detached tobacco leaves. Thus, we propose that the cAMP signalling pathway is involved in mycelia growth and pathogenic phenotype of Alternaria alternata. [ABSTRACT FROM AUTHOR]

Isoflavonoids isolated from plants have been confirmed to fight osteoporosis and promote bone health. However, few studies have been conducted to describe the anti-osteoporosis activity of botanical flavonone. Based on the experimental outcomes, we demonstrated the ability of naringin to fight osteoporosis in vitro. We developed a retinoic acid-induced osteoporosis model of rats to assess whether naringin has similar bioactivity against osteoporosis in vitro. After a 14-day supplement of retinoic acid to induce osteoporosis, SD rats were administered naringin. A blood test showed that naringin-treated rats experienced significantly lower activity of serum alkaline phosphatase and had higher femur bone mineral density, compared to untreated rats. All three dosages of naringin improved the decrease in bone weight coefficient, the length and the diameter of the bone, the content of bone ash, calcium, and phosphorus content induced by retinoic acid. The data of histomorphological metrology of naringin groups showed no difference as compared to normal control rats. These outcomes suggest that naringin offer a potential in the management of osteoporosis in vitro. [ABSTRACT FROM AUTHOR]

Generally running with frequent braking over short distances, the urban rail transit train generates great quantities of regenerative braking energy (RBE). The RBE feedback system can effectively recycle RBE and give it back to the AC grid. However, the lack of damp and inertia of generators makes conventional PWM RBE feedback system more sensitive to power fluctuations. To address this issue, a synchronverter-based RBE feedback system of urban rail transit is designed in this paper. First, the structure of the feedback system is presented. Then, the synchronverter-based control strategy with greater flexibility and higher stability is fully discussed. Furthermore, the parameter design of the system is analyzed in detail. Finally, simulation results and experimental results are provided to show the good dynamic performance of the system. Using this synchronverter-based approach, the system supplies traction power to the traction network when the train accelerates and gives the RBE back to the AC grid when the train brakes, in light of the variation of the DC bus voltage. Moreover, the system can be self-synchronized with the AC grid and make corresponding power management on the basis of changes in the voltage amplitude as well as the frequency of the grid. In this sense, the RBE feedback system becomes more flexible, effective and robust. [ABSTRACT FROM AUTHOR]