Numerical investigation of geostress influence on the grouting reinforcement effectiveness of tunnel surrounding rock mass in fault fracture zones

Grouting is a widely used approach to reinforce broken surrounding rock mass during the construction of underground tunnels in fault fracture zones,and its reinforcement effectiveness is highly affected by geostress.In this study,a numerical manifold method(NMM)based simulator has been developed to examine the impact of geostress conditions on grouting reinforcement during tunnel excavation.To develop this simulator,a detection technique for identifying slurry migration channels and an improved fluid-solid coupling(FeS)framework,which considers the influence of fracture properties and geostress states,is developed and incorporated into a zero-thickness cohesive element(ZE)based NMM(Co-NMM)for simulating tunnel excavation.Additionally,to simulate coagulation of injected slurry,a bonding repair algorithm is further proposed based on the ZE model.To verify the accuracy of the proposed simulator,a series of simulations about slurry migration in single fractures and fracture networks are numerically reproduced,and the results align well with analytical and laboratory test results.Furthermore,these numerical results show that neglecting the influence of geostress condition can lead to a serious over-estimation of slurry migration range and reinforcement effectiveness.After validations,a series of simulations about tunnel grouting reinforcement and tunnel excavation in fault fracture zones with varying fracture densities under different geostress conditions are conducted.Based on these simula-tions,the influence of geostress conditions and the optimization of grouting schemes are discussed.

Critical precipitation behavior of MnTe inclusions in resulfurized steels during solidification

Te treatment is an effective method for modifying sulfide inclusions,and MnTe precipitation has an important effect on thermal brittleness and steel corrosion resistance.In most actual industrial applications of Te treatment,MnTe precipitation is unexpected.The critical precipitation behavior of MnTe inclusions was investigated through scanning electron microscopy,transmission electron microscopy,machine learning,and first-principles calculation.MnTe preferentially precipitated at the container mouth for sphere-like sulfides and at the interface between MnS grain boundaries and steel matrix for rod-like sulfides.The MnS/MnTe interface was semicoherent.A composition transition zone with a rock-salt structure exhibiting periodic changes existed to maintain the semicoherent interface.The critical precipitation behavior of MnTe inclusions in resulfurized steels involved three stages at varying temperatures.First,Mn(S,Te)precipitated during solidification.Second,MnTe with a rock-salt structure precipitated from Mn(S,Te).Third,MnTe with a hexagonal NiAs structure transformed from the rock-salt structure.The solubility of Te in MnS decreased with decreasing temperature.The critical precipitation behavior of MnTe inclusions in resulfurized steels was related to the MnS precipitation temperature.With the increase in MnS precipitation temperature,the critical Te/S weight ratio decreased.In consideration of the cost-effectiveness of Te addition for industrial production,the Te content in resulfurized steels should be controlled in accordance with MnS precipitation temperature and S content.

基于机器学习和第一性原理计算构建双电子转移通道加速CO_(2)光还原

光催化还原CO_(2)技术可以将CO_(2)转化为高附加值化学品,在解决日益严重的环境污染和能源危机方面具有巨大潜力.然而,CO_(2)分子较高的C=O键键能(750 kJ mol^(-1))为其活化和还原带来了挑战.因此,构建具有新型电子转移路径的光催化剂具有重要意义.与传统的单电子传输通道相比,层状材料的多电子传输通道在改善载流子传输能力方面具有明显的优势.然而,设计具有合适参数的多电子通道光催化剂模型仍是重要挑战.本文首先采用理论计算预测了具有双电子转移通道、参数匹配的三元异质结BiOBr-Bi-g-C_(3)N_(4);然后,通过机器学习探讨了各种实验参数对双电子传输通道的光催化活性影响的线性规律,优化了实验参数,制备了光催化活性较高的BiOBr-Bi-g-C_(3)N_(4)催化剂;最后,结合第一性原理计算和实验表征结果揭示了其光催化机理.理论计算结果表明,BiOBr-Bi-g-C_(3)N_(4)异质结具有最佳的吉布斯自由能(|ΔG|),有利于光催化H_(2)O解离和CO_(2)还原.实验发现,在300 W Xe灯照射下,CO_(2)还原光催化活性高达43μmol g^(-1)h^(-1).与Bi-BiOBr和Bi-g-C_(3)N_(4)相比,BiOBr-Bi-g-C_(3)N_(4)催化CO_(2)还原:的速率分别提高了约4.7倍和3.1倍.分析新型结构催化剂之所以具有良好的活性,主要有以下三个原因:(1)三者之间匹配的功函数使得BiOBr和g-C_(3)N_(4)纳米片可以与Bi形成肖特基异质结,在光照下,电子从BiOBr和g-C_(3)N_(4)向Bi转移;此外,g-C_(3)N_(4)纳米片与BiOBr具有相似的层间结构和匹配的能级结构,有利于形成Bi-BiOBr和Bi-g-C_(3)N_(4)双电子传输通道,从而实现载流子的有效分离和转移.(2)丰富的Bi活性位点可以抑制光生载流子的随机分布,使其限域在BiOBr与g-C_(3)N_(4)层间;这些载流子在特定的时间尺度上产生了独特的叠加态,优化了CO_(2)还原的多电子反应动力学路径.(3)g-C_(3)N_(4)的引入提高了Bi-BiOBr的太阳光利用率和比表面积.综上所述,本文成功地预测、设计和制备了一种具有双电子传输通道的新型三元异质结BiOBr-Bi-g-C_(3)N_(4)光催化剂,其表现出较高的光催化CO_(2)还原性能.理论计算和实验结果表明,BiOBr和g-C_(3)N_(4)相似的层间结构和匹配的能级结构使得具有不同弛豫时间的电子能够形成相干态;而Bi作为CO_(2)还原的良好活性位点,能够同时提高BiOBr和g-C_(3)N_(4)的载流子转移性能.因此,具有不同寿命的电子可以参与到CO_(2)还原的过程中去.本文可为高性能CO_(2)还原光催化剂的精准预测和合理设计提供实验和理论参考.

由单层薄水铝石制备的活性氧化铝处理水中氟离子

合成高效低成本的氟离子吸附剂仍是具有挑战的研究课题。本文采用无有机物的方法制备了单层结构的薄水铝石,并以此薄水铝石得到大比表面积的活性氧化铝。活性氧化铝的大比表面积保证了很高的吸附效率,合成过程无有机表面活性剂或模板剂的使用,控制了成本。采用X射线衍射(XRD)及扫面电镜(SEM)等方法对样品进行了表征,发现制备的氧化铝前体为单层结构的薄水铝石,其比表面积为789.4 m^(2)∙g^(−1),焙烧后得到活性氧化铝的比表面积为678.4 m^(2)∙g^(−1),孔体积为3.20 cm^(3)∙g^(−1)。并系统研究了吸附剂用量、吸附时间等因素对活性氧化铝吸附水中氟离子的影响。研究结果表明,本文制备活性氧化铝对水中氟离子的吸附量可达67.6 mg∙g^(−1)。仅分别需0.6、1.0或2.6 g∙L^(−1)活性氧化铝就可将10、20或50 mg∙L^(−1)的氟离子溶液处理至中国饮用水标准(1.0 mg∙L^(−1))以下。并且此活性氧化铝在pH=4–9的范围内均可用于水中氟离子的处理,对吸附有较大影响的共存离子为SO_(4)^(2−)及PO_(4)^(3−),进一步研究表明,活性氧化铝对氟离子的吸附遵循准二级模型和朗格缪尔等温模型。

A Study of WiFi-Aided Magnetic Matching Indoor Positioning Algorithm

Aiming at the shortcomings of the existing indoor location algorithm, such as low accuracy of positioning, high deployment and maintenance cost, and unstable robustness, this paper proposes a method of indoor location based on the integration of smartphone with WiFi and magnetic field using multi-sensor fusion. In the initial stages of positioning, rough location is achieved by Wi-Fi-RSSI fingerprints which provides an initial location and geomagnetic matching area for indoor positioning based on particle filter magnetic field matching. This paper proposes the use of median filter algorithm to deal with the original magnetic field data and covariance interpolation algorithm to generate magnetic field map, and effectively reduce the interference which caused by geomagnetic fluctuations, thereby it will improves the positioning accuracy. Finally, through conducting comprehensive experiments and tests, the results show that the proposed technique can reliably achieve 0.836 meters precision in current experimental environment.

An Indoor Pedestrian Localization Algorithm Based on Multi-Sensor Information Fusion

For existing indoor localization algorithm has low accuracy, high cost in deployment and maintenance, lack of robustness, and low sensor utilization, this paper proposes a particle filter algorithm based on multi-sensor fusion. The pedestrian’s localization in indoor environment is described as dynamic system state estimation problem. The algorithm combines the smart mobile terminal with indoor localization, and filters the result of localization with the particle filter. In this paper, a dynamic interval particle filter algorithm based on pedestrian dead reckoning (PDR) information and RSSI localization information have been used to improve the filtering precision and the stability. Moreover, the localization results will be uploaded to the server in time, and the location fingerprint database will be built incrementally, which can adapt the dynamic changes of the indoor environment. Experimental results show that the algorithm based on multi-sensor improves the localization accuracy and robustness compared with the location algorithm based on Wi-Fi.

Robust Local Weighted Regression for Magnetic Map-Based Localization on Smartphone Platform

The magnetic information measured on the smartphone platform has a large fluctuation and the research of indoor localization algorithm based on smart-phone platform is less. Indoor localization algorithm on smartphone platform based on particle filter is studied. Robust local weighted regression is used to smooth the original magnetic data in the process of constructing magnetic map. Use moving average filtering model to filter the online magnetic observation data in positioning process. Compare processed online magnetic data with processed magnetic map collected by smartphone platform and the average matching error is 0.3941uT. Average positioning error is 0.229 meter when using processed online and map data.

Circularly polarized lasing from chiral metal-organic frameworks

Circularly polarized lasers play a pivotal role in classical optics,nanophotonics,and quantum optical information processing,while their fabrication remains complex.This article begins with examining the interactions between stimulated emission and chiral matter,outlining a simple strategy for producing circularly polarized lasing from chiral metal-organic frameworks(MOFs),such as the zeolitic imidazolate framework(ZIF),embedded with achiral laser dyes(L∕D-ZIF?dyes).It is found that the stimulated emission threshold and intensity are influenced by the interplay between the chiral polarization of the pump light and the inherent chirality of the MOF nanoparticles.We further present the design of a chiral vertical-cavity surface-emitting laser(VCSEL),comprising an L∕D-ZIF?dyes solid-state film sandwiched between a high-reflectivity distributed Bragg reflector(DBR)mirror and a silver film.The cavity-based lasing exhibits higher asymmetry between emitting left-handed and right-handed polarized light compared to chiral spontaneous emission(SE)and amplified spontaneous emission(ASE),with an asymmetry value glum of approximately±0.31.This value is nearly four-fold greater than that of SE and twice that of ASE.Our findings reveal a new approach to amplify chiral signals,promoting the comprehension and application of chiral–matter interactions,and offering a simple yet effective strategy to fabricate chiral lasers.

Dual-stimuli responsive near-infrared emissive carbon dots/hollow mesoporous silica-based integrated theranostics platform for real-time visualized drug delivery

Due to better penetrating abilities of near-infrared (NIR) light and lower autofluorescence of biological tissue at NIR region, the combination of NIR fluorescent imaging with therapeutic abilities has gradually emerged as a promising strategy for cancer therapy. Herein, tumor microenvironment (TME) sensitive nanocarriers based on doxorubicin hydrochloride (DOX), NIR emitting carbon dots (C-dots), hollow mesoporous silica nanoparticles (HMSN) and anionic polymer citraconic anhydride-modified polylysine (PLL(cit)) are fabricated for imaging guided drug delivery. The NIR emitting C-dots were conjugated onto the surface of HMSN via disulfide bonds which can be reduced by intracellular glutathione (GSH) and result in the release of DOX into cells. And then the PLL(cit) was grafted on the surface of the nanocarriers to endow the nanocarriers with charge convertible property in mildly acidic TME (pH = 6.50) which results in prolonged blood circulation time and enhanced cellular internalization. The in vitro and in vivo experiments confirmed that the dual pH/GSH responsive features of nanocarriers can eliminate the tumor tissues effectively and elicit much slighter side effects. Moreover, since the fluorescence of C-dots can be recovered after the reduction of disulfide bonds and selectively accumulation of nanocarriers around tumor tissue, the DOX@HMSN-SS-C-dots-PLL(cit) can be served as a promising NIR fluorescence probe for targeted imaging of tumor tissue. As a kind of multifunctional nanocarrier with NIR fluorescent imaging and therapeutic functions, the theranostic nanocarriers hold great potential for tumor therapy and in vivo imaging of tumor tissue.

Fused deposition modeling 3D printed oral famotidine pulsatile release tablets

The aim of this study was to prepare pulsatile release tablets which provide different drug delayed-release time and realize personalized administration according to the needs of patients.Fused deposition modeling(FDM)3D printing technology was introduced into the field of pharmaceutics in this study,and the feasibility to prepare core-shell pulsatile release tablets was explored by combing 3D printing technology with the traditional manufacturing technology.The core of the pulsatile tablets was a commercial tablet obtained from the traditional technology,and the drug-free shell was prepared by the FDM 3D printing technology.Three kinds of tablet shells were designed using different parameters.Furthermore,the morphology,size,weight,hardness,and in vitro drug release of the 3D printed famotidine pusatile tablets were characterized and evaluated.The results showed that the 3D printed tablets appeared intact without any defects.Different parameters of outer shell affected the size,weight,hardness,and in vitro drug release of the tablets.The tablets achieved a personalized delayed release time varying from 5 to 7 h in vitro.In this way,a new method for preparing pulsatile release tablets and a new way for the personalized administration of pulsatile tablets were explored in this study.

Analysis of catchment evapotranspiration at different scales using bottom-up and top-down approaches

Physically-based hydrological models are used to predict catchment water balance through detailed simulation of hydrological processes at small temporal and spatial scales.However,annual catchment water balance can also be easily and simply predicted using lumped conceptual model.Comparison between physically-based hydrological models and lumped conceptual models can help us understand the dominant factors on catchment water balance at different scales.In this paper,a distributed physically-based hydrological model(i.e.,bottom-up approach)and a simple water-energy balance model(i.e.,top-down approach)are used to predict actual evapotranspiration in nine sub-catchments,and the whole basin of the Luan River in northern China.Both simulations give very close values of annual evapotranspiration and show the same complementary relationship between actual and potential evapotranspiration at annual time scale.From the analysis at different time scales through comparison of the top-down and the bottom-up methods,it is shown that the annual catchment evapotranspiration is controlled mainly by annual precipitation and potential evapotranspiration,and the variability of soil water and vegetation becomes more important at a smaller time scale in the study areas.It is also known that the relationship between potential and actual evapotranspiration shows a highly nonlinear relationship at the annual and catchment scale but can be simplified to a linear relationship at hourly temporal and hillslope scales,which is commonly used in the physicallybased hydrological models.

Erratum to: Dual-stimuli responsive near-infrared emissive carbon dots/hollow mesoporous silica-based integrated theranostics platform for real-time visualized drug delivery

Erratum to Nano Research 2021,14(11):4264-4273 https://doi.org/10.1007/s12274-021-3624-4 The first two authors part of this article was unfortunately misrepresented on the first page and in the ESM.

Single-vesicle imaging quantifies calcium’s regulation of nanoscale vesicle clustering mediated by α-synuclein

Although numerous studies have shown that the proteinα-synuclein(α-Syn)plays a central role in Parkinson’s disease,dementia with Lewy bodies,and other neurodegenerative diseases,the protein’s physiological function remains poorly understood.Furthermore,despite recent reports suggesting that,under the influence of Ca^(2+),α-Syn can interact with synaptic vesicles,the mechanisms underlying that interaction are far from clear.Thus,we used single-vesicle imaging to quantify the extent to which Ca^(2+)regulates nanoscale vesicle clustering mediated by α-Syn.Our results revealed not only that vesicle clustering requiredα-Syn to bind to anionic lipid vesicles,but also that different concentrations of Ca^(2+)exerted different effects on howα-Syn induced vesicle clustering.In particular,low concentrations of Ca^(2+)inhibited vesicle clustering by blocking the electrostatic interaction between the lipid membrane and the N terminus of α-Syn,whereas high concentrations promoted vesicle clustering,possibly due to the electrostatic interaction between Ca^(2+)and the negatively charged lipids that is independent of α-Syn.Taken together,our results provide critical insights intoα-Syn’s physiological function,and how Ca^(2+) regulates vesicle clustering mediated by α-Syn.

Abnormal expression of inducible nitric oxide synthase in Duchenne muscular dystrophy muscles

Duchenne muscular dystrophy (DMD) is a fatal genetic disease for the youth and children. 8 biopsies of DMD patients were determined and demonstrated that the membrane_binding nitric oxide synthase was enriched in normal skeletal muscles and was little in DMD muscles. The results from Western blot and immunohistochemistry showed that inducible nitric oxide synthase (iNOS) was overexpressed in DMD muscle fibers, while a small amount of highly localized iNOS can be found in normal fibers. Based on these findings, it is proposed that the mechanism of progressive injury in DMD muscle might be associated with the abnormal expression of iNOS.