Pore-pressure and stress-coupled creep behavior in deep coal:Insights from real-time NMR analysis

Understanding the variations in microscopic pore-fracture structures(MPFS) during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment. In this manuscript, a triaxial creep test on deep coal at various pore pressures using a test system that combines in-situ mechanical loading with real-time nuclear magnetic resonance(NMR) detection was conducted.Full-scale quantitative characterization, online real-time detection, and visualization of MPFS during coal creep influenced by pore pressure and stress coupling were performed using NMR and NMR imaging(NMRI) techniques. The results revealed that seepage pores and microfractures(SPM) undergo the most significant changes during coal creep, with creep failure gradually expanding from dense primary pore fractures. Pore pressure presence promotes MPFS development primarily by inhibiting SPM compression and encouraging adsorption pores(AP) to evolve into SPM. Coal enters the accelerated creep stage earlier at lower stress levels, resulting in more pronounced creep deformation. The connection between the micro and macro values was established, demonstrating that increased porosity at different pore pressures leads to a negative exponential decay of the viscosity coefficient. The Newton dashpot in the ideal viscoplastic body and the Burgers model was improved using NMR experimental results, and a creep model that considers pore pressure and stress coupling using variable-order fractional operators was developed. The model’s reasonableness was confirmed using creep experimental data. The damagestate adjustment factors ω and β were identified through a parameter sensitivity analysis to characterize the effect of pore pressure and stress coupling on the creep damage characteristics(size and degree of difficulty) of coal.

In-situ observation and modeling approach to evolution of pore-fracture structure in coal

The characterisation of the pore-fracture structure(PFS)and its evolution in coal during mining are essential for preventing gas outbursts and improving gas extraction efficiency.In this study,the evolution of the PFS in coal samples under the condition of mining stress was directly captured in situ by combination of the mechanical testing system with high-precision visualisation nuclear magnetic resonance equipment.A fractional derivative model was established to describe the relationship between stress and porosity based on experimental results of the PFS under different stress states.The results showed that with an increase in the deviatoric stress,the adsorption pore content increases rapidly initially and then increases slowly or remains unchanged;the seepage pore and fracture(SPF)content decreases initially and then increases.The SPF compressibility coefficient decreases with an increase in the deviatoric stress.The fractional derivative model can accurately describe the stress sensitivity of the SPFs at the pre-peak stage,thus providing a new approach for accurately characterising the seepage characteristics of coal reservoirs.

Research progress and application of deep in-situ condition preserved coring and testing

With the depletion of shallow resources,the exploration of deep earth resources has become a global strategy.The study of the different patterns in the physical mechanical properties of rocks at different occurrence depths is the basis for exploring deep into the earth,with the core and premise being the acquisition and testing of deep in-situ core specimens.Based on the original idea of deep in-situ condition preserved coring(ICP-Coring)and testing,combined with theoretical modeling,numerical analysis,test platform development,indoor testing and engineering application,the principles and technologies of deep ICP-Coring are developed.This principle and technology consists of five parts:in-situ pressurepreserved coring(IPP-Coring),in-situ substance-preserved coring(ISP-Coring),in-situ temperaturepreserved coring(ITP-Coring),in-situ light-preserved coring(ILP-Coring),and in-situ moisturepreserved coring(IMP-Coring).The theory and technology of temperature and pressure reconstruction at different occurrence depths and in different environments are proposed,and prototype trial production was completed by following the principle of displacement and tests based on the in-situ reconstructed environment.The notable advances are as follows:(1)Deep in-situ coring system:A pressure-preserved controller with an ultimate bearing capacity greater than 140 MPa,highperformance(temperature-resistant,pressure-resistant,and low thermally conductive)temperaturepreserved materials,an active temperature control system,and high-barrier quality-preserved membrane materials were developed;a deep ICP-Coring capacity calibration platform was independently developed,a deep in-situ coring technology system was developed,and the acquisition of deep in-situ cores was realized.(2)In-situ storage displacement system:Following the dual-circuit hydraulic design idea,a single-drive source push-pull composite grabbing mechanism was designed;the design of the overall structure for the deep in-situ displacement storage system and ultrahigh pressure cabin structure was completed,which could realize docking the coring device and core displacement in the in-situ reconstructed environment.(3)Test analysis system:A noncontact acoustic-electric-magnetic test system was developed under the in-situ reconstructed environment,and the errors between the test results and traditional contact test results were mostly less than 10%;a detachable deep in-situ core true triaxial test system was developed,which could perform loading tests for deep in-situ cores.The relevant technological achievements were successfully applied to the exploration and development of deep resources,such as deep mines,deep-sea natural gas hydrates,and deep oil and gas.The research results provide technical and equipment support for the construction of a theoretical system for deep in-situ rock mechanics,the development of deep earth resources and energy,and the scientific exploration of different layers and occurrence depths(deep and ultradeep)of the Earth.

Numerical analysis on mechanical difference of sandstone under in-situ stress,pore pressure preserved environment at depth

Deep in-situ rock mechanics considers the influence of the in-situ environment on mechanical properties,differentiating it from traditional rock mechanics.To investigate the effect of in-situ stress,pore pressure preserved environment on the mechanical difference of sandstone,four tests are numerically modeled by COMSOL:conventional triaxial test,conventional pore pressure test,in-situ stress restoration and reconstruction test,and in-situ pore pressure-preserved test(not yet realized in the laboratory).The in-situ stress restoration parameter is introduced to characterize the recovery effect of in-situ stress on elastic modulus and heterogeneous distribution of sandstone at different depths.A random function and nonuniform pore pressure coefficient are employed to describe the non-uniform distribution of pore pressure in the in-situ environment.Numerical results are compared with existing experimental data to validate the models and calibrate the numerical parameters.By extracting mechanical parameters from numerical cores,the stress-strain curves of the four tests under different depths,in-situ stress and pore pressure are compared.The influence of non-uniform pore pressure coefficient and depth on the peak strength of sandstone is analyzed.The results show a strong linear relationship between the in-situ stress restoration parameter and depth,effectively characterizing the enhanced effect of stress restoration and reconstruction methods on the elastic modulus of conventional cores at different depths.The in-situ pore pressurepreserved test exhibits lower peak stress and peak strain compared to the other three tests,and sandstone subjected to non-uniform pore pressure is more prone to plastic damage and failure.Moreover,the influence of non-uniform pore pressure on peak strength gradually diminished with increasing depth.

界面聚合法制备异氰酸酯型微胶囊及其性能

针对异氰酸酯型自修复微胶囊包封率较低、制备过程难以控制等问题,提出以聚氨酯预聚物为壁材原料,采用界面聚合法制备出微胶囊。以聚氨酯预聚物(拜尔L-75)与1,4-丁二醇(BDO)反应产物为壁材,异佛尔酮二异氰酸酯(IPDI)为芯材,油相中L-75的异氰酸酯(-NCO)官能团与水相中扩链剂BDO的羟基(-OH)在界面处发生逐步聚合反应,生成聚氨酯膜,IPDI被聚氨酯膜成功包封形成微胶囊。讨论了BDO加入量,乳化剂阿拉伯胶(GA)用量对微胶囊结构、形貌及性能的影响。采用傅里叶变换红外光谱表征了微胶囊的化学结构;采用光学显微镜研究了微胶囊形貌、大小分布;热重分析仪分析了微胶囊囊芯含量。结果表明,在50℃下,扩链剂BDO质量分数为11.7%,GA质量分数为17.4%,IPDI质量分数为67%,搅拌速度为600 r/min,所制备的异氰酸酯微胶囊囊心质量分数为55.69%,包封率达到83%。

聚己内酯对左旋聚乳酸结晶行为的影响

采用端羟基聚己内酯(PCL)并控制丙交酯(L-LA)的质量合成不同嵌段长度的PLLA-PCL-PLLA三嵌段共聚物;使用相对分子质量相近的左旋聚乳酸(PLLA)与PCL均聚物共混得到PLLA/PCL共混物。红外光谱测试和核磁共振氢谱测试确定了共聚物结构。差示扫描量热(DSC)测试结果表明,PCL的引入有效提高了PLLA嵌段共聚物和PLLA均聚物的结晶速率。利用DSC考察总结晶速率,热台偏光显微镜考察生长速率,结果表明当共聚物中PLLA嵌段相对分子质量与共混物中PLLA均聚物相对分子质量相当时,PLLA嵌段与PLLA均聚物结晶速率相当。PCL的加入使得PLLA最大结晶速率所对应的温度降低,其加入方式对PLLA的结晶形貌有一定的影响,无论以共聚或共混的方式引入PCL均对PLLA结晶速率的提高有积极作用。

Study on the relation between damage and permeability of sandstone at depth under cyclic loading

The damage and permeability evolution of rock under stress is of great significance to engineering safety.In this paper,the evolution law of rock damage and permeability is studied by means of acoustic emission (AE) seepage experiment on deep roof sandstone with cyclic loading.Characterization of damage uses the changes in acoustic emission fractal characteristics and compression parameter which based on elastic modulus.The experimental results show that the AE events has fractal characteristic,in which the AE b-value and correlation dimension can represent the damage of rock.When the fractal characteristic value of AE increases,it indicates that the rock is in the compaction stage and the damage is not obvious.When the fractal characteristic value of AE drops,it indicates that the rock was damaged,and the permeabilityincrease.Under the cyclic load increasing step by step,the elastic modulus first increases and then decrease.Introducing compression parameter C to characterize the state of compaction and damage,it is obtained that the rock damage state and hydrostatic permeability show a power law function relationship with porosity and have the same monotonicity.When compression parameter is less than zero,the evolution law of permeability and damage can be described by functional relationship between hydrostatic permeability K and compression parameter C.

Reduction of electric field strength by two species of trees under power transmission lines

Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.

Surveillance of pine wilt disease by high resolution satellite

Pine wilt disease caused by the pinewood nematode Bursaphelenchus xylophilus has led to the death of a large number of pine trees in China.This destructive disease has the characteristics of bring wide-spread,fast onset,and long incubation time.Most importantly,in China,the fatality rate in pines is as high as 100%.The key to reducing this mortality is how to quickly find the infected trees.We proposed a method of automatically identifying infected trees by a convolution neural network and bounding box tool.This method rapidly locates the infected area by classifying and recognizing remote sensing images obtained by high resolution earth observation Satellite.The recognition accuracy of the test data set was 99.4%,and the remote sensing image combined with convolution neural network algorithm can identify and determine the distribution of the infected trees.It can provide strong technical support for the prevention and control of pine wilt disease.

A Method for Calculating the Heats of Formation of Medium-Sized and Large-Sized Molecules

A calculation method for heats of formation (HOF, referred to as △Hf) based on the density functional theory (DFT) is presented in this work. Similar to Gaussian-3 theory, the atomic scheme is applied to calculate the heats of formation of the molecules. In this method, we have modified the formula for calculation of Gaussian-3 theory in several ways, including the correction for diffuse functions and the correction for higher polarization functions. These corrections are found to be significant. The average absolute deviation from experiment for the 164 calculated heats of formation is about 1.9 kcal·mol?1, while average absolute deviation from G3MP2 for the 149 (among the 164 molecules, 15 large-sized molecules can not be calculated at the G3MP2 level) calculated heats of formation is only about 1.9 kcal·mol?1. It indicates that the present method can be applied to predict the heats of formation of medium-sized and large-sized molecules, while the heats of formation of these molecules using Gaussian-3 theory are much difficult, even impossible, to calculate. That is, this method provides a choice in the calculation of △Hf for medium-sized and large-sized molecules.

Design of 1.5 bit quantization correlator in satellite navigation software receiver

Currently, 1 bit or 2 bit signal quantization is widely used in satellite navigation software receivers. The bit-wise parallel algorithm has been proposed for 1 bit and 2 bit signal quantization, which performs correlation with high efficiency. In order to improve the performance of the correlator, this paper proposes a new 1.5 bit quantization method. Theoretical analyses are made from the aspects of complexity and quantization loss, and performance comparison between 1.5 bit quantization correlator and traditional correlators is discussed. The results show that the 1.5 bit quantization algorithm can save about 30 percent complexity under similar quantization loss, reduce more than 0.5 dB signal noise ratio（SNR） loss under similar complexity. It shows great performance improvement for correlators of satellite navigation software receivers.

非石油原料合成己二腈研究进展

己二腈是一种重要的有机化工中间体.己二腈加氢后可制备己二胺,主要用于生产尼龙-66,故而市场应用前景巨大.传统的己二腈合成方法需要使用大量的石油原料,具有很多的发展制约.因此,近年来,以非石油原料合成制备己二腈的研究备受关注.本文对目前已发表的关于非石油原料合成己二腈的研究成果进行了总结,包括基于生物质、煤基和其他可再生资源的合成方法以及使用酶催化、电催化、化学催化等不同的合成策略.本文还结合现有的路线汇总了当前有望被开发的反应路径,并探讨了未来可能的研究方向和应用前景.需要强调的是,开发具有自主知识产权的己二腈合成工艺对于我国尼龙-66产业的发展至关重要,如何有效地开发新型己二腈合成技术将是未来面临的重大挑战.本文对非石油原料合成己二腈的研究进行了展望,为相关产业的路线设计和开发提供参考.

Gut commensal metabolite rhamnose promotes macrophages phagocytosis by activating SLC12A4 and protects against sepsis in mice

Sepsis progression is significantly associated with the disruption of gut eubiosis.However,the modulatory mechanisms of gut microbiota operating during sepsis are still unclear.Herein,we investigated how gut commensals impact sepsis development in a pre-clinical model.Cecal ligation and puncture(CLP)surgery was used to establish polymicrobial sepsis in mice.Mice depleted of gut microbiota by an antibiotic cocktail(ABX)exhibited a significantly higher level of mortality than controls.As determined by metabolomics analysis,ABX treatment has depleted many metabolites,and subsequent supplementation with L-rhamnose(rhamnose,Rha),a bacterial carbohydrate metabolite,exerted profound immunomodulatory properties with a significant enhancement in macrophage phagocytosis,which in turn improved organ damage and mortality.Mechanistically,rhamnose binds directly to and activates the solute carrier family 12(potassium-chloride symporter),member 4(SLC12A4)in macrophages and promotes phagocytosis by activating the small G-proteins,Ras-related C3 botulinum toxin substrate1(Rac1)and cell division control protein 42 homolog(Cdc42).Interestingly,rhamnose has enhanced the phagocytosis capacity of macrophages from sepsis patients.In conclusion,by identifying SLC12A4 as the host interacting protein,we disclosed that the gut commensal metabolite rhamnose is a functional molecular that could promote the phagocytosis capacity of macrophages and protect the host against sepsis.

High-fat diet impairs gut barrier through intestinal microbiota-derived reactive oxygen species

Gut barrier disruption is a key event in bridging gut microbiota dysbiosis and high-fat diet(HFD)-associated metabolic disorders.However,the underlying mechanism remains elusive.In the present study,by comparing HFD-and normal diet(ND)-treated mice,we found that the HFD instantly altered the composition of the gut microbiota and subsequently damaged the integrity of the gut barrier.Metagenomic sequencing revealed that the HFD upregulates gut microbial functions related to redox reactions,as confirmed by the increased reactive oxygen species(ROS)levels in fecal microbiota incubation in vitro and in the lumen,which were detected using in vivo fluorescence imaging.This microbial ROS-producing capability induced by HFD can be transferred through fecal microbiota transplantation(FMT)into germ-free(GF)mice,downregulating the gut barrier tight junctions.Similarly,mono-colonizing GF mice with an Enterococcus strain excelled in ROS production,damaged the gut barrier,induced mitochondrial malfunction and apoptosis of the intestinal epithelial cells,and exacerbated fatty liver,compared with other low-ROS-producing Enterococcus strains.Oral administration of recombinant high-stability-superoxide dismutase(SOD)significantly reduced intestinal ROS,protected the gut barrier,and improved fatty liver against the HFD.In conclusion,our study suggests that extracellular ROS derived from gut microbiota play a pivotal role in HFD-induced gut barrier disruption and is a potential therapeutic target for HFD-associated metabolic diseases.

Novel strategy of multidimensional information encryption via multi-color carbon dots aggregation-induced emission

Carbon dots(CDs)with aggregation-induced emission(AIE)have sparked significant interest in multidimensional anti-counterfeiting due to their exceptional fluorescence properties.However,the preparation of AIE CDs with multicolor solid-state fluorescence remains a formidable challenge due to its complicated construction.In the present work,a novel class of multicolor AIE CDs(M-CDs)were fabricated using selected precursor(salicylic acid,thiosalicylic acid,and 2,2'-dithiodibenzoic acid),with an eco-friendly,low-cost one-pot solvothermal method.In the dilute organic solution,M-CDs manifested blue emission,but upon aggregation in the presence of water,the red,yellow,green,and blue emissions were displayed due to the AIE effect.Structural analysis,coupled with theoretical calculations,revealed that the increase in the size of sp2 domains would lower the Eg and cause a red-shift emission wavelength.Significantly,the continuous emission of M-CDs from blue to red can be utilized as ink for multimode printing,enabling the creation of a variety of school badges and quick response codes.These findings hold promising implications for multi-information encryption applications.

Tunable single emitter-cavity coupling strength through waveguide-assisted energy quantum transfer

The emitter-cavity strong coupling manifests crucial significance for exploiting quantum technology,especially in the scale of individual emitters.However,due to the small light-matter interaction cross-section,the single emitter-cavity strong coupling has been limited by its harsh requirement on the quality factor of the cavity and the local density of optical states.Herein,we present a strategy termed waveguide-assisted energy quantum transfer(WEQT)to improve the single emitter-cavity coupling strength by extending the interaction cross-section.Multiple ancillary emitters are optically linked by a waveguide,providing an indirect coupling channel to transfer the energy quantum between target emitter and cavity.An enhancement factor of coupling strength eg=g>10 can be easily achieved,which dramatically release the rigorous design of cavity.As an extension of concept,we further show that the ancillae can be used as controlling bits for a photon gate,opening up new degrees of freedom in quantum manipulation.

Increased clonal dissemination of OXA-232-producing ST15 Klebsiella pneumoniae in Zhejiang,China from 2018 to 2021

Background OXA-232-producing Klebsiella pneumoniae was first identified in China in 2016,and its clonal transmission was reported in 2019.However,there are no prevalence and genotypic surveillance data available for OXA-232 in China.Therefore,we investigated the trends and characteristics of OXA-232 type carbapenemase in Zhejiang Province,China from 2018 to 2021.Methods A total of 3278 samples from 1666 patients in the intensive care units were collected from hospitals in Zhejiang Province from 2018 to 2021.Carbapenem-resistant isolates were initially selected by China Blue agar plates supplemented with 0.3μg/ml meropenem,and further analyzed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry identification,immune colloidal gold technique,conjugation experiment,antimicrobial susceptibility testing and whole genome sequencing.Results A total of 79 OXA-producing strains were recovered,with the prevalence increased from 1.8%[95%confidence interval(CI):0.7–3.7%]in 2018 to 6.0%(95%CI:4.4–7.9%)in 2021.Seventy-eight strains produced OXA-232 and one produced OXA-181.The blaOXA-232 gene in all strains was located in a 6141-bp ColKP3-type non-conjugative plasmid and the blaOXA-181 gene was located in a 51,391-bp ColKP3/IncX3-type non-conjugative plasmid.The blaOXA-232-producing K.pneumoniae was dominated(75/76)by isolates of sequence type 15(ST15)that differed by less than 80 SNPs.All OXA-producing strains(100%,95%CI:95.4–100.0%)were multidrug-resistant.Conclusions From 2018 to 2021,OXA-232 is the most prevalent OXA-48-like derivative in Zhejiang Province,and ST15 K.pneumoniae isolates belonging to the same clone are the major carriers.The transmission of ColKP3-type plasmid to E.coli highlighted that understanding the transmission mechanism is of great importance to delay or arrest the propagation of OXA-232 to other species.

A metabolite from commensal Candida albicans enhances the bactericidal activity of macrophages and protects against sepsis

The gut microbiome is recognized as a key modulator of sepsis development.However,the contribution of the gut mycobiome to sepsis development is still not fully understood.Here,we demonstrated that the level of Candida albicans was markedly decreased in patients with bacterial sepsis,and the supernatant of Candida albicans culture significantly decreased the bacterial load and improved sepsis symptoms in both cecum ligation and puncture(CLP)-challenged mice and Escherichia coli-challenged pigs.Integrative metabolomics and the genetic engineering of fungi revealed that Candida albicans-derived phenylpyruvate(PPA)enhanced the bactericidal activity of macrophages and reduced organ damage during sepsis.Mechanistically,PPA directly binds to sirtuin 2(SIRT2)and increases reactive oxygen species(ROS)production for eventual bacterial clearance.Importantly,PPA enhanced the bacterial clearance capacity of macrophages in sepsis patients and was inversely correlated with the severity of sepsis in patients.Our findings highlight the crucial contribution of commensal fungi to bacterial disease modulation and expand our understanding of the host-mycobiome interaction during sepsis development.

Coal and rock dynamic disaster prevention and control technology in the large mining face of a deep outburst mine

In this study, we systematically studied the occurrence regularity of in situ stress in the Pingdingshan mine. The critical criterion model of coal-rock destabilization was established based on the theoretical framework of fracture mechanics. Furthermore, we analyzed the coupling destabilization mechanism of in situ stress and gas and studied the influence of the variation between original rock stress and mining-induced stress on the critical criterion. Through field experiments and applications, we established a three-dimensional gas drainage technology system for areas with a large mining height and long work face. Based on our research, a demonstration project was developed for deep mine dynamic disaster control. The technical system included the arrangement and optimization of pre-drainage holes along the coal seam, technology, and optimization of gas drainage through the bottom drainage tunnel and upper corner, gas drainage technology through sieve tubes, and a two plugging with one injection under pressure sealing technology. The implementation of the demonstration project effectively reduced the gas content and pressure of the coal seam in the deep mine, and the project increased the critical strength of the instability and failure of coal and rock.

Photoswitchable quantum electrodynamics in a hybrid plasmonic quantum emitter

The design and preparation of quantum states free from environmen-tal decohering effects is critically important for the development of on-chip quantum systems with robustness.One promising strategy is to harness quantum state superposition to construct decoherence-free subspace(DFS),which is termed dark state.Typically,the exci-tation of dark states relies on anti-phase-matching on two qubits and the inter-qubit distance is of wavelength scale,which limits the de-velopment of compact quantum chips.In the current work,a hybrid plasmonic quantum emitter was proposed,which was composed of strongly correlated quantum emitters intermediated by a plasmonic nanocavity.Through turning the plasmonic loss from drawback into advantage,the anti-phase-matching rule was broken by rapidly de-caying the superposed bright state and preparing a sub-100 nm dark state with decay rate reduced by 3 orders of magnitudes.More inter-estingly,the dark state could be optically switched to a single-photon emitter with enhanced brightness through photon-blockade,with the quantum second order correlation function at zero delay showing a wide range of tunability down to 0.02.