Key technology and application of pre-stressed anchor to improve pre-tightening force

As one of the key parameters of bolt support, pre-tightening force plays a decisive role in active support. Domestic and foreign research shows that increasing the pre-tightening force of bolt can reduce the occurrence of roof fall accidents, so as to effectively improve the pre-tightening force of bolt and reduce the occurrence of broken anchor and lost anchor. The rolling anti-friction washer and tension-compression separation nut were developed. The torque-preload conversion relationship of the rolling anti-friction washer and tension-compression separation nut was studied by laboratory experiment, theoretical analysis and numerical calculation. The mechanical response characteristics of the common nut and tension-compression separation nut during pre-tightening process were studied. The research shows that about 60% of the torque is consumed by the friction between the bolt nut and the tray during the pre-tightening process of the ordinary bolt. The torque consumed by the friction can be reduced to 25% by using the rolling anti-friction gasket, and the torque-pretightening force conversion rate is increased by about 2 times. The stress of the internal thread pair of the ordinary bolt nut decreases exponentially along the axial direction away from the extrusion surface. The stress value of the first three rings in the nut is larger, and the stress concentration occurs obviously in this range, which is the dangerous surface of the bolt body fracture. The stress of the thread pair is evenly distributed after using the tension-compression separation nut, which eliminates the stress concentration phenomenon and the thread deformation is coordinated. The high pre-tightening force uniform bearing bolt was invented by integrating rolling friction reducing gasket, tension-compression separation nut, etc., which can increase the pre-tightening force to 2.5 times, eliminate the phenomenon that the bolt is easy to break from the thread section, and achieve good application effect in Zhuji Mine of Huainan Mining Area

Bioprospecting for the soil-derived actinobacteria and bioactive secondary metabolites on the Western Qinghai-Tibet Plateau

IntroductionThe increase in incidence of multidrug-resistant bacteria and the inadequacy of new antimicrobial drugs have led to a widespread outbreak of bacterial antimicrobial resistance. To discover new antibiotics, biodiversity, and novelty of culturable actinobacteria dwelled in soil of the Western Qinghai-Tibet Plateau were investigated. By integrating antibacterial assay with omics tools, Amycolatopsis sp. A133, a rare actinobacterial strain and its secondary metabolites were further studied.MethodCulture-dependent method was used to obtain actinobacterial strains from two soil samples collected from Ali region in Qinghai-Tibet Plateau. The cultural extractions of representative strains were assayed against “ESKAPE” pathogens by paper-disk diffusion method and the double fluorescent protein reporter “pDualrep2” system. An Amycolatopsis strain coded as A133 was prioritized and its secondary metabolites were further analyzed and annotated by omics tools including antiSMASH and GNPS (Global Natural Social Molecular Networking). The predicted rifamycin analogs produced by Amycolatopsis sp. A133 were isolated and identified by chromatographic separation, such as Sephadex LH-20 and HPLC, and spectral analysis, such as NMR and UPLC-HRESI-MS/MS, respectively.ResultsA total of 406 actinobacteria strains affiliated to 36 genera in 17 families of 9 orders were isolated. Out of 152 representative strains, 63 isolates exhibited antagonistic activity against at least one of the tested pathogens. Among them, 7 positive strains were identified by the “pDualrep2” system as either an inhibitor of protein translation or DNA biosynthesis. The cultural broth of Amycolatopsis sp. A133 exhibited a broader antimicrobial activity and can induce expression of TurboRFP. The secondary metabolites produced by strain A133 was annotated as rifamycins and zampanolides by antiSMASH and GNPS analysis. Five members of rifamycins, including rifamycin W, protorifamycin I, rifamycin W-M1, proansamycin B, and rifamycin S, were purified and identified. Rifamycin W-M1, was found as a new member of the naturally occurring rifamycin group of antibiotics.DiscussionAssisted by omics tools, the successful and highly efficient discovery of rifamycins, a group of clinically used antibiotics from actinobacteria in Ali area encouraged us to devote more energy to explore new antibiotics from the soils on the Western Tibetan Plateau

Adopting big data to accelerate discovery of 2D TMDCs materials via CVR method for the potential application in urban airborne Hg0 sensor

Airborne Hg0 has significant negative effect on cities and urban systems. The development of effect airborne Hg0 sensor is rather important for both urban atmospheric Hg0 detection and the evaluation of Hg0 capture materials. Previous research showed MoS2 as a typical TMDCs materials had excellent performance to capture Hg0. In this study, the other 2D TMDCs materials via CVR method in big data was initially studied for the potential urban airborne Hg0 sensor application. The combinations of Pymatgen initial screening, Factsage thermochemical screening and Aflow structural screening were developed for accelerating discovery of the 2D TMDCs in big data. The results from Pymatgen showed that except elements Cd, Sc, Y, Zn, and the other elements have the potential to form TMDC. Furthermore, elements such as Co, Ni, Mo, Ru, W and Ir have the ability forming pure TMDC and Ti, Mn, Zr and Pd can only form partial TMDC. However, other elements such as Sc, V, Cr, Fe, Cu, Zn, Y, Rh and Cd have no possibility to form TMDC. Finally, TiS2, NiS2, ZrS2, MoS2, PdS2 and WS2 were found with 2D structure, which are possible to be prepared by the S-CVR method as the airborne Hg0 sensor materials

UNCOVERING THE MOLECULAR BASIS OF ACTIVITY-DEPENDENT RETINOFUGAL SYNAPSE PLASTICITY

Activity-dependent synapse plasticity is important for the establishment of neuron wiring in the central nervous system, particularly in the context of sensory processing. In the visual system, image-forming and non-image-forming retinal input into the brain is a popular model for studying activity-dependent plasticity due to the well-characterized neural activity and bulk-level innervation pattern. However, investigation of synaptic connection during early development has been impeded by the limited resolution of conventional fluorescent microscopy or lack of profile tagging in electron microscopy (EM) images. To overcome these challenges, we employed volumetric STochastic Optical Reconstruction Microscopy, immunohistochemistry synaptic protein labeling, and anterograde retinal tract tracing to investigate the activity-dependent retinogeniculate and retinohypothalamic synapse plasticity. Through our findings, we uncover the developmental pattern of retinofugal innervation and shed light on the impact of spontaneous activity on retinal synapse maturation at the synaptic level. During the first postnatal week in mice, the dorsal lateral geniculate nucleus (dLGN) initially receives overlapping input from the two eyes before the binocular innervation segregated. The changes in individual synapse properties during the eye-specific segregation process have remained unknown. In Chapter 2, we uncovered eye-specific differences in presynaptic vesicle pool size and vesicle association with the active zone at the earliest stages of retinogeniculate refinement but found no evidence of eye-specific differences in subsynaptic domain number, size, or transsynaptic alignment across development. Genetic disruption of spontaneous retinal activity decreased retinogeniculate synapse density, delayed the emergence of eye-specific differences in vesicle organization, and disrupted subsynaptic domain maturation. These results suggest that activity-dependent eye-specific presynaptic maturation underlies synaptic competition in the mammalian visual system. The dLGN relays visual information from the retina to the visual cortex through parallel processing pathways. In adult mice, such processing is achieved through spatial clustering of several retinal ganglion cells (RGCs) boutons to integrate convergent or divergent visual information. It is unknown whether such RGC synapse clustering occurs during the early developmental stage. In Chapter 3, we identified a subset of complex retinogeniculate synapses with larger presynaptic vesicle pools and multiple AZs that simultaneously promote the clustering of like-eye synapses (synaptic stabilization) and prevent synapse formation from the opposite eye (synaptic punishment). In mutant mice with disrupted spontaneous retinal wave activity, complex synapses are formed but fail to drive eye-specific synaptic clustering and punishment. These results reveal the early formation of a unique synaptic subset that regulates activity-dependent eye-specific synaptic competition and may serve as substrates for later synapse clustering formation. A subset of RGCs that express the photopigment melanopsin (OPN4) innervate the suprachiasmatic nucleus (SCN), which serves as the central pacemaker responsible for controlling circadian rhythm in mammals. The function of OPN4 is important for SCN photoentrainment, but its impact on retinal synapse maturation during early development is unknown. In Chapter 4, we found that OPN4 plays an important role in retinal synapse formation and activation in the SCN during the early developmental stage. Loss of OPN4 leads to reduced retinal synapse density, and increased variability in the ratio of synapses with few or no docking vesicles, but has not effect on total vesicle pool volume. Meanwhile, the subsequent maturation of retinohypothalamic tract (RHT) synapses after the first postnatal week shows diminished reliance on OPN4 function and further compensates for the early defects in the absence of OPN4. This study reveals a moderate influence of OPN4 on early RHT synapse development and sheds light on the role of photopigment in regulating SCN synapse plasticity. This dissertation introduces a novel approach using super-resolution fluorescent imaging in the thalamus and hypothalamus tissue. Our work has yielded insights into the activity-dependent maturation in synapse properties and spatial distribution in the dLGN, as well as the impact of OPN4 on retinohypothalamic synapses in the SCN. By revealing the synapse development at the molecular level, our study demonstrates presynaptic mechanisms that underlie activity-dependent retinal synapse plasticity during the early developmental stage. Furthermore, our application of super-resolution fluorescent microscopy highlights its potential as a valuable tool for future in situ studies on brain development

Additive manufacturing of magnesium matrix composites: Comprehensive review of recent progress and research perspectives

The magnesium matrix composites (MMCs) formed by introducing reinforcements to magnesium alloys overcome the limitations of the mechanical properties to a certain extent, presenting unique and excellent properties that any component does not have, such as high specific stiffness and specific strength, good dimensional stability, outstanding shock absorption performance, excellent electromagnetic shielding and hydrogen storage characteristics, etc. As an emerging manufacturing technology, additive manufacturing (AM) is based on the design of three-dimensional (3D) data model to obtain 3D objects through layer-by-layer processing, which possesses the advantages of short manufacturing cycle, high material utilization rate, high degree of design freedom, excellent mechanical properties and the ability to fabricate complex structural components. Combining the high stiffness and high strength properties of MMCs and the technical advantages of AM forming complex structural parts with high performance, the prepared AM MMCs have huge potential advantages and broad application prospects in new high-tech industries such as automobile, aerospace, consumer electronics and biomedicine, etc. This paper reviews the research progress in the field of AM MMCs, mainly introduces the main AM technologies, including selective laser melting (SLM), electron beam selective melting (EBSM), laser engineered net shaping (LENS) and wire and arc additive manufacturing (WAAM). The formation mechanism and control methods of the typical defects including balling effect, porosity, poor fusion, loss of alloy elements and cracks produced during AM are discussed. The main challenges of AM MMCs are proposed from the aspects of composition design and the preparation of powder raw material. The relationship between the microstructure and mechanical properties, corrosion performance and biocompatibility of AM MMCs are elaborated in detail. The application potential of AM MMCs in various fields at present and in the future is introduced. Finally, the development direction and urgent problems to be solved in the AM MMCs are prospected

Assessing Sustainability: Frameworks and Indices (White Paper #3)

The ability to accurately assess and track sustainability is crucial for achieving sustainable development goals at every level. There are many types of tools for sustainability assessment, at the core of which are indicators and indices. By presenting a number of common sustainability frameworks and outlining the underlying steps for constructing sustainability indices, this paper aims to contribute to the overview and discussion of sustainability measurement, which is often inconsistent and confusing. This paper also analyzes how sustainability frameworks can assist in the selection of indicators, which is often the most important yet most inconsistent step in constructing an index, and points out the need for future research to develop a dynamic and objective process of indicator selection for both frameworks and composite indices

Research on the Capacity of Underground Reservoirs in Coal Mines to Protect the Groundwater Resources: A Case of Zhangshuanglou Coal Mine in Xuzhou, China

This study analyzes the ability of coal mine underground reservoirs to protect groundwater resources. As the demand for coal mining continues to increase, the potential impact on groundwater resources around mines has become a growing problem. Underground water reservoirs, also known as coal mine underground reservoirs, have been constructed as a solution to protect water wastage in mining operations. However, there is a lack of awareness related to the ability of underground water reservoirs in mines to protect groundwater resources. In this study, we used FLAC3D software to analyze the formation process, water storage volume, and central storage location of the underground water reservoir in Zhangshuanglou Coal Mine. The results show that the damaged volume is 3.39 × 106 m3, and the groundwater resources that can be protected by coal mine underground reservoirs in the study area amount to 1.98 × 105 m3. We found that the storage capacity of underground reservoirs is more significantly affected by the extent of mining, which can be expressed as y = 49,056.44 + 255.75x + 1.46x2 (R2 = 0.995) (x ≠ 0). Additionally, the water storage location obtained through simulation can provide a reference for the construction of underground reservoir regulation and water storage projects. The results of the water quality analysis indicate that the concentrations of SO42− decreased by 42% with the closure of the mining area, and the pH also gradually converged to neutral. This highlights the significant role of underground water reservoirs in coal mines in promoting green production and protecting water resources and the environment

The Effect of Different Annealing Temperatures on Recrystallization Microstructure and Texture of Clock-Rolled Tantalum Plates with Strong Texture Gradient

The texture and the bulk stored energy along the thickness direction were extremely inhomogeneous in the clock-rolled tantalum sheets with 70% reduction. Therefore, the effects of different annealing temperatures on the microstructure and texture distribution of tantalum plates through the thickness were investigated by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The results showed that the occurrence of strong {111} recrystallization texture in the center layer can be attributed to the subgrains nucleation mechanism when annealed at the low temperature. Many subgrains with {111} orientation appeared in the center layer, due to its high stored energy and preferential nucleation sites of the {111} deformed matrix, and rapidly grew into the effective nucleus, resulting in the large {111} grain size and strong {111} texture after complete recrystallization. Contrarily, at the high temperature, high-angle grain boundaries had sufficient driving force to generate migration, due to the lack of recovery, and the growth time of recrystallized nucleus was much shorter, contributing to relatively uniform recrystallization microstructure and texture distribution along the thickness

Poincaré Plot Nonextensive Distribution Entropy: A New Method for Electroencephalography (EEG) Time Series

As a novel form of visual analysis technique, the Poincaré plot has been used to identify correlation patterns in time series that cannot be detected using traditional analysis methods. In this work, based on the nonextensive of EEG, Poincaré plot nonextensive distribution entropy (NDE) is proposed to solve the problem of insufficient discrimination ability of Poincaré plot distribution entropy (DE) in analyzing fractional Brownian motion time series with different Hurst indices. More specifically, firstly, the reasons for the failure of Poincaré plot DE in the analysis of fractional Brownian motion are analyzed; secondly, in view of the nonextensive of EEG, a nonextensive parameter, the distance between sector ring subintervals from the original point, is introduced to highlight the different roles of each sector ring subinterval in the system. To demonstrate the usefulness of this method, the simulated time series of the fractional Brownian motion with different Hurst indices were analyzed using Poincaré plot NDE, and the process of determining the relevant parameters was further explained. Furthermore, the published sleep EEG dataset was analyzed, and the results showed that the Poincaré plot NDE can effectively reflect different sleep stages. The obtained results for the two classes of time series demonstrate that the Poincaré plot NDE provides a prospective tool for single-channel EEG time series analysis