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In article number 2000111, Pengfei Tu, KeWei Wang, Yong Jiang, and co‐workers develop a precise microfluidic assay in single‐cell profile for screening of transient receptor potential (TRP) channel modulators. The single‐cell‐based screening strategy dramatically reduces false‐positive/negative results from 76.2% to 4.8% due to full consideration of single‐cell heterogeneity. Four novel coumarin derivatives are cherry‐picked to potently inhibit TRP channels. One of the positive hits, B‐304, reverses TRPA1‐mediated inflammatory pain in vivo. [Image: see text]

Conductive metal–organic frameworks (MOFs) have been studied extensively in applications like water electrolysis, gas storage, and supercapacitors due to their high conductivity and large pore volume. In this communication, we report the first use of a conductive Ni-MOF as a non-noble-metal catalyst for efficient electro-oxidation of glucose in alkaline electrolyte. As an electrochemical sensor for glucose detection, this Ni-MOF shows a fast response time of less than 3 s, a low detection limit of 0.66 μM (S/N = 3), and a high sensitivity of 21 744 μA mM−1 cm−2. This glucose sensor also displays excellent selectivity, stability and reproducibility, and its application for the detection of glucose in real samples is also demonstrated successfully.

Patterned deposition and 3D fabrication techniques have enabled the use of hydrogels for a number of applications including microfluidics, sensors, separations, and tissue engineering in which form fits function. Devices such as reconfigurable microvalves or implantable tissues have been created using lithography or casting techniques. Here, we present a novel open-microfluidic patterning method that utilizes surface tension forces to form hydrogel layers on top of each other, into a patterned 3D structure. We use a patterning device to form a temporary open microfluidic channel on an existing gel layer, allowing the controlled flow of unpolymerized gel in device-regions. After layer gelation and device removal, the process can be repeated iteratively to create multi-layered 3D structures. The use of open-microfluidic and surface tension-based methods to define the shape of each individual layer enables patterning to be performed with a simple pipette and with minimal dead-volume. Our method is compatible with unmodified (native) biological hydrogels, and other non-biological materials with precursor fluid properties compatible with capillary flow. With our open-microfluidic layer-by-layer fabrication method, we demonstrate the capability to build agarose, type I collagen, and polymer-peptide 3D structures featuring asymmetric designs, multiple components, overhanging features, and cell-laden regions.

Optimization of experimental conditions

Fragmentation energy ratio is an important index to evaluate whether an explosive is used efficiently. This paper discusses the effect of water-decked blasting on fragmentation energy based on theory and numerical simulation, and three blasting tests were performed to measure the actual fragmentation energy at a granite-based field. Results show that at the same charge amount, the maximum borehole pressure of water-decked blasting is much greater than that of normal blasting in theory, which facilitates rock breaking. In numerical simulation, water-decked blasting is more beneficial to the transmission of explosive energy; therefore, the damage distribution is more uniform and the damage level is higher. The specific surface area and fragment size distribution were obtained by three-dimensional laser scanning and image analysis in field tests; therefore, the fragmentation energy could be measured, which showed that the fragmentation energy could be increased by 10% in water-decked blasting. In addition, water-decked blasting can reduce fly rocks and ensure the safety of rock blasting.

Aqueous sodium ion batteries have received widespread attention due to their great application potential and high safety. However, the serious capacity fading under low temperature dramatically restricts their practical application. Compared to flammable and toxic organic antifreezing additives, addition of common cheap inorganic inert additives to improve low-temperature performance is of interest scientifically. Herein, low-cost calcium chloride is served as antifreezing additive in 1 m NaClO

The blast experimental test is an effective method to observe the failure characteristics of reinforced concrete (RC) slabs to contact explosion. However, the existing explosion experiments on RC s...

In mining, the explosive filled in each borehole is usually initiated by the detonator. However, the effect of the location of the detonator (i.e. initiation location), which determines the propagation direction of the detonation wave, cannot be ignored. In this study, the influence mechanism of initiation location was analyzed with the help of numerical simulation. Two blasting experiments were also conducted to study the effect of initiation location. The results indicate that the initiation location plays an important role in the distribution of the explosion energy transmitted to the surrounding rock mass. For the vertical borehole blasting, the peak particle velocity below the borehole can be reduced by 21.0–59.0% under bottom initiation, when compared to top initiation. The blast-induced damage of the remaining rock mass below the borehole is also weaker by 5.0–8.9% under bottom initiation. However, the problem of under break might become serious if the detonator is moved downwards in foundation excavation. The explosion energy is preferentially transmitted to the same orientation of the detonation wave during rock blasting. The bottom initiation, recommended by most previous researchers, is not always the best choice. The location of the detonator should be changed according to the onsite situations.

The rapid release of strain energy is an important phenomenon leading to seismic events or rock failures during the excavation of deep rock. Through theoretical analysis of strain energy adjustment during blasting and mechanical excavation, and the interpretation of measured seismicity in the Jin-Ping II Hydropower Station in China, this paper describes the characteristics of energy partition and induced seismicity corresponding to different energy release rates. The theoretical analysis indicates that part of the strain energy will be drastically released accompanied by violent crushing and fragmentation of rock under blast load, and this process will result in seismic events in addition to blasting vibration. The intensity of the seismicity induced by transient strain energy release highly depends on the unloading rate of in-situ stress. For mechanical excavation, the strain energy, which is mainly dissipated in the deformation of surrounding rock, releases smoothly, and almost no seismic events are produced in this gradual process. Field test reveals that the seismic energy transformed from the rock strain energy under high stress condition is roughly equal to that coming from explosive energy, and the two kinds of vibrations superimpose together to form the total blasting excavation-induced seismicity. In addition, the most intense seismicity is induced by the cut blasting delay; this delay contributes 50% of the total seismic energy released in a blast event. For mechanical excavation, the seismic energy of induced vibration (mainly the low intensity acoustic emission events or mechanical loading impacts), which accounts only for 1.5‰ of that caused by in-situ stress transient releasing, can be ignored in assessing the dynamic response of surrounding rock.

With the development of the precision guidance technology, the earth-penetrating weapon (EPW) is a huge threat to infrastructures. The objective of this research is to investigate the damage characteristics of mass concrete targets under the combined action of penetration and explosion. The validity of the penetration model is discussed by reproducing a previous experimental test reported in the literature. Meanwhile, a field test about the internal explosion in a concrete cube is conducted to verify the validity of the internal explosion model. Subsequently, damage characteristics of a mass concrete target from the upper part of a concrete gravity dam are discussed when subjected to the combined action of the penetration and explosion. In order to improve the structural performance of the mass concrete target to penetration and explosion loadings, high strength concrete material is selected as a preventive measure. Penetration processes and damage patterns of the mass target with normal and high strength concrete material are compared. Then, three internal explosion models are presented to investigate the influence of the initial penetration damage on the failure characteristics of the mass concrete target. The results show that the resistance of the mass target to the combined action of the penetration and explosion can be enhanced significantly by using the high strength concrete material. The initial penetration damage has a significant influence on the damage processes of the mass concrete target subjected to internal blast loading.

In the present study, multi-shelled ZnCo2O4 yolk-shell spheres have been successfully prepared by using carbonaceous microspheres as templates. It is found that the multi-shelled ZnCo2O4 yolk-shell spheres based sensor shows optimal sensing performances (response value of 38.2, response/recovery time of 19 s/71 s) toward 500 ppm acetone at 200 °C. In addition, this sensor exhibits a low detection limit of 0.5 ppm acetone (response value of 1.36) and a good selectivity toward hydrogen, methane, ethanol, ammonia and carbon dioxide. Furthermore, it is demonstrated that acetone gas response of multi-shelled ZnCo2O4 yolk-shell spheres is significantly better than that of ZnCo2O4 nanotubes and ZnCo2O4 nanosheets. High acetone response of the multi-shelled ZnCo2O4 yolk-shell spheres is attributed to the enhanced gas accessibility of the multi-shell morphology caused by the small crystalline size and high specific surface area while the short response/recovery time is mainly related to the rapid gas diffusion determined by the highly porous structure. Our work puts forward an exciting opportunity in designing various yolk-shelled structures for multipurpose applications.

The strain energy adjustment processes and rock failure modes corresponding to different excavation methods, such as Tunnel Boring Machine (TBM) or blasting, are quite different during construction of deep tunnel. Based on the diversion tunnel excavation of Jin-Ping II hydropower station (JPII) in southwestern China, the distribution characteristics of damage zones and adjustment process of rock strain energy under different excavation methods are analyzed and discussed, and the occurrences of rock bursts in the diversion tunnels are also monitored and analyzed. Research reveals that, the adjustment process of rock strain energy and the distribution of damage zones are obviously different under different excavation methods, and the depth and distribution of damage zone are positively correlated with the accumulation depth of rock strain energy. For blasting excavation, due to the combined effects of blast loading and in situ stress transient unloading, the surrounding rock is damaged seriously. The accumulation depth of rock strain energy is significantly larger than that by TBM excavation, while the accumulation peak of rock strain energy is smaller. For TBM excavation, the strain energy releases smoothly and slowly, and much more strain energy is accumulated in the vicinity of excavation face. Under similar geological conditions in the JPII, the rock bursts of intensive and mediate grades can be more frequently observed after blasting for the impact of severe excavation disturbance, and the strain energy transient adjustment may be the main disturbance contributor. While during TBM excavation, due to the smooth adjustment process of rock strain energy, the disturbance to surrounding rock is limited, and the accumulation peak of rock strain energy is higher and closer to the excavation face, which may result in more spalling events or minor rock bursts.

Here, we have newly developed chemically functionalized three-dimension (3D) graphene oxide hydrogels (FGH) decorated with metal-organic frameworks (MOFs)-derived Co 3 O 4 nanostructures, in which the Co 3 O 4 nanostructures are uniformly distributed in 3D FGH frameworks. It is found that the Co 3 O 4 /FGH composites exhibits excellent acetone sensing properties, for instance, it shows an ultra-high response (R gas /R 0 = 81.2) to 50 ppm acetone, which was ∼20 times higher than that of pristine Co 3 O 4 film, a short response time (∼20 s), and a distinct cross-selectivity against other interfering gases. Notably, upon exposure to 1 ppm acetone in air, the composites still can express an apparent response (R gas /R 0 = 4.06). The excellent acetone sensing properties of Co 3 O 4 /FGH can be mainly attributed to the unique porous structures of 3D FGH frameworks and the modulation of electrical transport properties of the Co 3 O 4 /FGH junctions in the composites. The Co 3 O 4 nanostructures uniformly distributed in 3D FGH frameworks can easily adsorb a great amount of acetone gas molecules through the unique porous frameworks and produce a great deal of electrons, which can be transferred to the p-type FGH frameworks through Co 3 O 4 /FGH junctions so that the resistance of Co 3 O 4 /FGH composites is greatly increased. Therefore, the acetone response of the composites is dramatically enhanced because of the Co 3 O 4 /FGH junctions. This study presents a new idea of building MOF-derived oxides/FGH junctions to enhance gas response of oxide-based gas sensors, and has great potential in fabrication of new generation gas sensors.

The disturbance of a rock mass due to blasting impact and stress redistribution can significantly affect the overall performance of an excavation. Crack formation during presplit blasting was analyzed with a mathematical model, considering the in situ stress. The results clearly indicate that the in situ stress can inhibit crack formation. The linear density of the explosive and blast hole spacing should be adjusted to improve crack formation. The damage distribution produced by different blasting approaches was reproduced with a numerical simulation based on the secondary development of LS-DYNA. The results demonstrate that the damage control effects of conventional presplit blasting or smooth blasting under in situ stress are not ideal. Owing to the combination of blasting load and stress redistribution, crack formation at the lateral sides was inhibited during presplit blasting, while the middle side could not be sufficiently broken during smooth blasting. An optimized method of presplit-smooth blasting was proposed and verified with numerical simulations. Finally, based on excavation of the Baihetan high rock slope, a comparison of the conventional and optimized approaches was conducted with sonic wave tests and roughness monitoring. The results demonstrate that the presplit-smooth blasting approach inherits the advantages of both presplit and smooth blasting, and could significantly improve contour control effects.

The aim of the present study was to examine the effects of earthquake direction on seismic performance of concrete gravity dams subjected to seismic sequences. For these purposes, two seismic incid...

To better understand damage characteristics of concrete gravity dams under contact explosion is a critical issue to evaluate the protective performance of dams. In this paper, a fully coupled Lagrangian-Eulerian numerical approach, incorporating the detonation process of underwater contact explosion, is performed to predict the damage propagation of a typical concrete gravity dam. In order to verify the validity of the coupled algorithm, damage profiles of a normal strength reinforced concrete (RC) slab subjected to contact explosion are predicted and compared with the published experimental results. The hydrostatic pressure of the reservoir is modeled by using the specific internal energy method. The interaction between detonation products and dam-foundation-reservoir systems is also considered. The detonation products development processes, shock wave propagation, and failure modes of the dam subjected to underwater contact explosion with and without considering the hydrostatic pressure are compared. In order to analyze the underwater contact explosion effects on failure modes and dynamic responses of the dam, three positions of the detonation point, i.e., upper blast point, middle blast point, and lower blast point, are considered in this study. The results show that the initial hydrostatic pressure has a significant influence on failure characteristics of the dam subjected to underwater contact explosion. Underwater contact explosion detonated in the lower zone will cause more serious damage to the dam heel and threaten the overall stability of the dam. Hence, more attention should be paid to the deep water contact explosion.

Reinforced concrete (RC) slabs are the major components for building structures and underwater engineering plants. However, blast loading, especially from contact explosion, can cause significant damage to the target structures both in air and water. The objective of this paper is to compare the damage characteristics of RC slabs subjected to air and underwater contact explosions. Three methods, i.e. fully coupled Eulerian-Lagrangian (CEL) method, smoothed particle hydrodynamics (SPH) method, and coupled finite element method and smoothed particle hydrodynamics method (FEM-SPH), are first employed to simulate the damage features of an RC slab to air contact explosion. Damage profiles of the RC slab to air contact explosion using the three methods are compared with the experiment results in the literature, and the applicability and suitability of these methods are discussed. Subsequently, the most effective method (i.e., FEM-SPH) is used to describe the dynamic response of the RC slab subjected to underwater contact explosion. Shock wave propagation characteristics from air and underwater contact explosions are discussed. Damage features of the RC slab to air and underwater contact explosions are compared. Damage characteristics and plastic deformation of reinforcement steel bars are also investigated.

It is demonstrated that hydrogen treatment as a simple, effective strategy can greatly improve the broadband photo-responsive performance of pristine TiO2 nanorod arrays (NRAs)/SiO2/n-Si heterojunctions. The hydrogen-treated TiO2 NRAs/SiO2/n-Si heterojunction shows a stable, repeatable and broadband photo response from 365 nm to 980 nm at 100 μW cm−2. The responsivity (R) of H:TiO2 NRAs/SiO2/n-Si approaches the ultrahigh value of 468 A W−1 and it has an outstanding detectivity (D*) of 1.96 × 1014 cm Hz1/2 W−1 and an excellent sensitivity (S) of 2.63 × 107 cm2 W−1, in contrast to the values of R (10−6–10−1 A W−1) or S (2 × 103 cm2 W−1) from reported TiO2 nanofilm/TiO2 NRAs/n-Si(111) photodetectors, indicating a huge responsivity enhancement of up to 4–8 orders of magnitude. Additionally, the response and recovery time are extremely short (3.5–3.9 ms). The comprehensive characteristics make the device stand out among the previously reported 1D metal oxide nanostructure/Si based photodetectors. In fact, the R, S and D* values of the heterojunction are 2–4 orders of magnitude higher than those of some new 2D nanomaterials/Si based photodetectors. The excellent photo-responsive performance may be attributed to the energy band structure of the TiO2@TiO2−xHx core/shell structure, the interface effect of the TiO2@TiO2−xHx/Si heterojunction, etc. This research provides a new concept for the design of other metal oxide based heterojunction photodetectors.

The highly sensitive and selective electrochemical sensor of hesperidin based on gold nanoparticles (AuNPs) and reduced graphene oxide (rGO) modified glassy carbon electrode (GCE) is reported. The AuNPs and rGO were uniformly introduced on the surface of the GCE via electrodeposition without any reducing agents and have been characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS), FT-IR, and electrochemical methods. The AuNPs/rGO not only promoted the accumulation of hesperidin onto the GCE surface for quantitative analysis but also accelerated the electron transfer between hesperidin and the electrode substrates. Under the optimal conditions, hesperidin was determined quantitatively at the AuNPs/rGO/GCE using amperometric i–t curve. The results showed that the current obtained on detection of hesperidin exhibited a linear correlation with its concentration in the range of 5.0 × 10−8 mol L−1–8.0 × 10−6 mol L−1 with a detection limit of 8.2 × 10−9 mol L−1 (S/N = 3). In addition, good specificity, repeatability, reproducibility, and long-term storage stability were achieved for the modified electrode, which could be used for the detection of hesperidin in the traditional Chinese medicine, Pericarpium Citri Reticulatae.

In this communication, we report the development of a Ni-based metal–organic framework nanosheet array on Ni foam (Ni-MOF/NF) as an ordered 3D electrode material for the detection of glucose in alkaline media. The Ni-MOF/NF presents remarkable performance, with a long linear range (0.04 to 2 mM) and a low detection limit for glucose concentration up to 85 nM (S/N = 3).

Layered metal dichalcogenides (LMDs) semiconducting materials have recently attracted tremendous attention as high performance gas sensors due to unique chemical and physical properties of thin layers. Here, three-dimensional SnS2 nanoflower structures assembled with thin nanosheets were synthesized via a facile solvothermal process. When applied to detect 100ppm NH3 at 200°C, the SnS2 based sensor exhibited high response value of 7.4, short response/recovery time of 40.6s/624s. Moreover, the sensor demonstrated a low detection limit of 0.5ppm NH3 and superb selectivity to NH3 against CO2, CH4, H2, ethanol and acetone. The excellent performance is attributed to the unique thin layers assembled flower-like nanoarchitecture, which facilitates both the carrier charge transfer process and the adsorption/desorption reaction. More importantly, it was found that the sensor response enhanced with increasing oxygen content in background and was improved by 3.57 times with oxygen content increasing from 0 to 40%. The increased response is owing to the enhanced binding energies between SnS2 and NH3 moleculers. Theoretically, density functional theory was employed to reveal the NH3 adsorption mechanism in different background oxygen contents, which opens a new horizon for LMD based structures applied in various gas sensing fields.

In this study, unloaded and Pt-loaded SnO 2 nanofibers (NFs) with 100–150 nm diameters were synthesized by a simple electrospinning technology and then calcined at 600 °C in air. It was observed that the Pt-SnO 2 NFs were comprised of strings of tiny SnO 2 nanoparticles decorated with Pt and PtO nanoparticles, resulting in the formation of PtO/SnO 2 heterojunction and high porosity. And then, we studied the methane (CH 4 ) sensing performance of the sensors fabricated from these NFs and found that 20 mol% Pt-SnO 2 NFs exhibited excellent CH 4 sensing properties over a temperature range of 100–350 °C, for example, the 20 mol% Pt-SnO 2 NFs showed an obvious response of 1.11–1 ppm CH 4 at 350 °C, which was 2 orders of magnitude lower than the minimum detection limit of the current SnO 2 based CH 4 sensors. The great enhancement of the CH 4 sensing properties of Pt-SnO 2 NFs can be understood by the PtO/SnO 2 heterogeneous sensitization and Pt catalytic effect. Our findings present a novel strategy for the application of SnO 2 based NFs in highly effective CH 4 detection.

With the rapid development of knowledge graphs (KGs), various AI-related applications have been affected positively. However, even though some KGs are relatively large, they still suffer from incompleteness. This has mighty promoted the development of reasoning over KGs to complement them. However, most existing reasoning methods only focus on semantics in the KG, ignoring potential or valuable information hidden in it, the most typical ones are neighborhood information and type information. This limits not only the reasoning performance but also the interpretability of the embedding space. To this end, we propose a Type-Aware Graph Attention neTworks (TAGAT) for the reasoning task over KGs. Except for combining type-related information during the embedding process, TAGAT further adopts a hierarchical attention mechanism to realize the perception of type and neighborhood information meticulously. For each entity, different attention levels respectively focus on considering the contribution of different relations, different types under each relation and different entity of each type under each relation. Moreover, the embedding space of TAGAT is constrained by the type information and naturally has better type-related interpretability, which greatly complements the defects of existing KGC models. Extensive experiments validate the high reasoning performance and the relatively ideal interpretability of our model.

Porous transitional metal oxides hollow polyhedrons with controlled components have attracted tremendous attention due to their widespread applications. In this paper, novel porous ZnO-decorated Co3O4 hollow polyhedrons were synthesized by thermal decomposition of zeolitic imidazolate frameworks (ZIF-67) as self-sacrificial templates at 300 °C. Experimental results reveal that the porous 2 mol% ZnO-Co3O4 hollow polyhedrons present excellent response value of 106, short response/recovery time of 7/236 s to 1000 ppm ethanol at the optimal temperature of 200 °C, much higher than that of pure Co3O4 porous hollow polyhedrons (response value of only 5.39, response/recovery time of 9/323 s). Additionally, the 2 mol% ZnO-Co3O4 manifests a low detection limit of 1 ppm ethanol with a high response value of 1.57 and an applausive selectivity toward ethanol as compared to NH3, H2, CH4, CO2 and CH3COCH3. The enhanced gas sensing performance can be attributed to the formation of p-n heterojunction between Co3O4 and ZnO, as well as the porous hollow nanostructure with high porosity, large specific surface area, and remarkable capabilities of adsorbing oxygen. Our work offers a new avenue to employ ZIF-67 as templates for the fabrication of other hollow metal oxides with well-defined structures. More importantly, it demonstrates a great potential for the application of porous ZnO-Co3O4 hollow polyhedrons heterostructure to detect other gases.

In this paper, we presented a simple method to fabricate size-controlled La 2 O 2 CO 3 nanoparticle by annealing La(OH) 3 nanocrystallines in air atmosphere. The microstructures of the samples were analyzed by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). TEM images indicate that the La(OH) 3 precursors consists of uniform ellipsoids with width of 9–15 nm and length of 15–30 nm and La 2 O 2 CO 3 are spheroidal particles with size of 12–25 nm. XRD patterns indicate that La(OH) 3 nanocrystallines are hexagonal phase and transform to monoclinic La 2 O 2 CO 3 after annealing. And then, La 2 O 2 CO 3 nanoparticle is printed on an interdigital electrode as a sensing material for CO 2 detection. La 2 O 2 CO 3 sensor exhibits good cycle stability performance and fast response and recovery (53 s and 120 s) over the wide range of 300–5000 ppm CO 2 in air condition. In addition, we also investigate the effect of oxygen concentration in the background atmosphere on CO 2 response of La 2 O 2 CO 3 sensor. The CO 2 sensing mechanisms for La 2 O 2 CO 3 sensor can be attributed to the interaction of CO 2 with oxygen species on La 2 O 2 CO 3 surface including chemisorption, surface reaction and desorption process, which also can be used to explain other metal oxide based CO 2 gas sensor.

To recommend the excavation procedures and design parameters for underground powerhouses, excavation procedures of fifty-one underground powerhouses in China were summarized and analyzed based on in situ stress conditions. Firstly, the complex stress environment in China was introduced and fifty-one underground powerhouses with their engineering scale, size, lithology, rock classification and in situ stress level were listed in detail. Subsequently, to evaluate the influence of in situ stress levels on excavation procedure design, the correlation between excavation procedures and in situ stress level in three main excavation zones were analyzed accordingly. Moreover, to provide the excavation design recommendations, the strength–stress ratio (SSR) was promoted to analyze and recommend the design parameters, and the blasting excavation design based on the stress transient unloading control was also supplemented. The results show that excavation procedures have different priorities under different in situ stress levels, and the design parameters show an obvious relationship with in situ stress levels. Moreover, the excavation procedure parameters are suggested to adjust accordingly under different SSR. The discussion of influencing factors and specification ensures its rationality and accuracy. It is believed that the summary and recommendations can provide a good reference for excavation procedure optimization of underground powerhouse under high in situ stress.

Recently, external terrorist activities have become one of the most influential events on structural safety because of the absence of proper mechanisms to detect these events. In this study, the effects of surface explosions on the dynamic response and blast resistance of a submarine tunnel are investigated by using a coupled Lagrange and Euler (CLE) method. The feasibility and accuracy of the numerical method and material models are verified against the experimental data. After that, the numerical model is utilized to investigate the dynamic behavior and damage evolution of the submarine tunnel subjected to surface explosions. The dynamic behavior of the tunnel under various detonation scenarios in terms of the explosive weight and water depth is explored. Both the localized damage mechanism and the global structural response of the tunnel are examined. Empirical formulas are proposed to predict the failure modes of tunnel. Besides, studies of tunnel protection against potential attacks by using carbon fibre reinforced polymer (CFRP) and ultra-high performance concrete (UHPC) are also discussed. Numerical results in this study provide tunnel owners and engineers with thorough and important information on the structural performance of submarine tunnels subjected to blast loads, helping them in choosing effective protection strategies for potential explosion events.

In the process of deep-hole blasting, the quality of blasting stemming seriously affects the blasting effect, but the optimal stemming length is difficult to determine. In this paper, the movement process and length optimization of deep-hole blasting stemming were investigated. At first, the mechanical mechanism of stemming structure was theoretically analyzed, and the additional friction resistance of stemming structure caused by the compression of the blasting shock wave was considered. Then, a time-sharing piecewise solution method for the movement process of stemming structure based on the method of time-space discretization was proposed, which can reveal the distribution law of the decreasing friction resistance along the axial direction . Moreover, the movement law of stemming structure under the conditions of explosion pressure ranging from 0.2 to 1.2 GPa, duration of detonation gas ranging from 10 to 15 ms, sliding friction coefficients ranging from 0.02 to 0.06, borehole diameters ranging from 76 to 200 mm, and stemming length ranging from 1.6 to 3.0 m was studied. Results showed that explosion load, duration of detonation gas, sliding friction coefficients, borehole diameters and stemming length all have a great influence on the movement of stemming structure. Finally, aiming at the common stemming materials of rock debris in engineering blasting, the effects of rock mass properties, explosion load, and borehole diameters on the optimal stemming length have been discussed based on the optimization principle that allows the part of stemming structure to rush out of borehole. It is found that the optimal stemming length increases linearly with the logarithmic product of the explosion pressure and the borehole diameter by the statistical analysis of the optimal stemming length under different calculation conditions. In view of the above, a new method for calculating the optimal stemming length is proposed and its reliability has been verified preliminarily by field application.

Accurate quantification of multiple miRNAs biomarkers in body fluid is still a challenge for early screening of cancer. Herein, by catalytic hairpin assembly as a signal amplification strategy, we designed a novel surface-enhanced Raman scattering (SERS)-lateral flow assay (LFA) strip for ultrasensitive detection of miR-21 and miR-196a-5p in non-small cell lung cancer (NSCLC) urine on a single test (T) line. 4-mercaptobenzoic acid or 5,5′-dithiobis-2-nitrobenzoic acid as Raman molecules was labeled and two hairpin DNA sequence was modified gold nanocages (GNCs) were designed as two SERS tags. Through target miRNA-triggered catalytic hairpin assembly (CHA), the double-stranded DNAs (H1–H2 complex) formed by SERS tags and the related hairpin-structured DNA sequence 2 (H2) were immobilized on a single T line of SERS-LFA strip. This generated abundant “hot spots” because of the formation of numerous H1–H2 complex thus facilitated the SERS measurement. Through this method, two kinds of miRNAs were analyzed, resulting in limits of detection of 2.08 pM and 3.31 pM for miR-21 in PBS buffer and human urine, 1.77 pM and 2.18 pM for miR-196a-5p in PBS buffer and human urine. Significantly, the SERS-LFA strip exhibited high specificity and good repeatability toward miRNAs. The whole detection time was only 30 min, which means that the high detection efficiency of the strip. The clinical feasibility of the proposed method was also evaluated by detecting the levels of miR-21 and miR-196a-5p in urine samples from NSCLC patients and healthy subjects. The developed SERS-LFA strip has wide application prospect in biomedical research, drug development and early clinical diagnosis.

Aiming at the problem of personalized customization of a smart home system, a scheme of personalized customization of the smart home system based on parsing XML authorization files is proposed. First, develop an XML authorization file generator, and use it to generate personalized XML authorization files; secondly, use the developed app to parse the XML authorization file to realize the legal authorization of the app and the dynamic generation of the home control interface; finally, click buttons on the control interface to trigger the TCP communication between the app and ESP8266, and then with the help of esp8266 to realize the switch of electrical appliances. Experimental results show that dynamic customization of the smart home system based on XML can implement dynamic customization of control interfaces for various home layouts, and can effectively control the home furnishings.

The damage prediction of high dams under the attacks of earth-penetrating weapons has gained significant importance in recent years. For this purpose, a SPH-Lagrangian-Eulerian coupled approach is proposed to describe the damage processes of concrete gravity dams subjected to the combined action of the penetration and explosion. The SPH method is used to model the concrete material with the large deformation near the penetration and explosion regions. The Lagrangian algorithm is adopted to simulate the high-velocity projectile and dam body with the small distortion. And the Eulerian algorithm is employed to describe the dynamic behavior of the water and air media. The validity of the penetration model is calibrated against a previous penetration test. Meanwhile, the SPH-Lagrangian-Eulerian coupled method is verified by implementing an underwater explosion test in a concrete cube. The computed distribution of cracking damage is consistent with the result of the experimental test, which validates the validity of the proposed SPH-Lagrangian-Eulerian coupling method. Subsequently, the penetration processes of a concrete gravity dam under the high-velocity projectile are presented. After the rapid penetration, the explosives are detonated in the dam with the initial penetration damage. The shock wave propagation characteristics in the dam and reservoir water are discussed. The failure processes and dynamic responses of the dam subjected to the combined action of the penetration and explosion are investigated. The influence of the initial penetration damage and the reservoir water on the failure processes of the dam subjected to the internal blast loading is also discussed. The results show that the penetration of the high-velocity projectile only causes a local damage to the concrete gravity dam. However, the combined effects of the penetration and explosion cause significantly more damage to the upper region of the dam.

When underground cavities are created in initially stressed rock masses by the drill and blast method, an unwanted excavation damage zone (EDZ) is induced around the cavities due to the combined effects of in-situ stress redistribution and blast loading. During rock fragmentation by blasting, the in-situ stress on blast-created excavation boundaries is suddenly released. The in-situ stress redistribution is a dynamic process that starts from the transient release of stress and reaches a final static stress state after excavation. For a circular tunnel that is excavated underground by full-face millisecond delay blasting, 2D finite element simulation is performed to investigate the rock damage induced by the dynamic in-situ stress redistribution and blast loading. The critical peak particle velocity (PPV) for the initiation of blast damage in pre-stressed rock masses is also numerically studied. The results show that the transient stress release generates additional stress waves, resulting in a larger damage zone compared with that following quasi-static stress redistribution. The effect that the additional stress waves have on rock damage becomes more obvious as the in-situ stress levels and excavation dimensions increase and as the stress release duration decreases. Blast-induced tensile stress in the circumferential direction of a tunnel is neutralized by compressive in-situ stress. In deep-buried or high-stressed tunnel excavation, dynamic stress redistribution is responsible for the formation of EDZ; the critical PPV for the initiation of blast damage first increases and then decreases with an increase in the in-situ stress. Therefore, in underground blasting excavation, the factors that affect the level of in-situ stress such as tunnel depths should be considered with respect to the blasting vibration standards and damage criteria.

Aim: Here, a multiplex surface-enhanced Raman scattering (SERS) based assay for simultaneous quantitation of carcinoembryonic antigen (CEA) and α-fetoprotein (AFP) was developed. Methods: SERS tags of nanostars and SERS substrates of nanobowl arrays were functionalized with labeling and capturing antibodies, respectively. In presence of antigens, SERS tags, antigens and SERS substrates formed sandwich structure. Results: The SERS-based technique showed a wide linear range from 0.5 to 100 ng/ml and detection limits were 0.41 and 0.35 ng/ml for CEA and AFP in phosphate-buffered saline buffer, respectively. Analysis results of clinical serum samples using this technique were similar to that shown in phosphate-buffered saline buffer. The LODs were 0.44 and 0.40 ng/ml for CEA and AFP, respectively. Conclusion: The precision and stability of this analysis technique were satisfactory, meanwhile, no obvious cross-reactivity could be found. What’s more, it also suggested that this novel multiplex SERS-based technique could be a simple, specific, reliable, sensitive and multiplexed tool for important diagnostic and prognostic applications.

The shear wave (S-wave) component of the total blast vibration always plays an important role in damage to rock or adjacent structures. Numerical approach has been considered as an economical and effective tool in predicting blast vibration. However, S-wave has not yet attracted enough attention in previous numerical simulations. In this paper, three typical numerical models, i.e. the continuum-based elastic model, the continuum-based damage model, and the coupled smooth particle hydrodynamics (SPH)-finite element method (FEM) model, were first introduced and developed to simulate the blasting of a single cylindrical charge. Then, the numerical results from different models were evaluated based on a review on the generation mechanisms of S-wave during blasting. Finally, some suggestions on the selection of numerical approaches for simulating generation of the blast-induced S-wave were put forward. Results indicate that different numerical models produce different results of S-wave. The coupled numerical model was the best, for its outstanding capacity in producing S-wave component. It is suggested that the model that can describe the cracking, sliding or heaving of rock mass, and the movement of fragments near the borehole should be selected preferentially, and priority should be given to the material constitutive law that could record the nonlinear mechanical behavior of rock mass near the borehole.

This paper presents an original investigation of the seismic cracking behavior of Guandi concrete gravity dam, which is located in the highly seismic zone of China. For this purpose, three dimensional nonlinear finite element analyses are carried out for the Guandi dam-reservoir-foundation system, with the effects of contraction joints and cross-stream seismic excitation considered. The Concrete Damaged Plasticity (CDP) model is utilized to model concrete cracking under seismic loading. The opening/closing and sliding behaviors of contraction joints during earthquake events are modeled using two different surface-to-surface contact models (soft and hard pressure-clearance relationships), which aims to quantify the effect of grouting materials between the joint surfaces. The dynamic interaction between the impounded water and the dam-foundation system is explicitly taken into account by modeling the reservoir water with three dimensional fluid finite elements in the Lagrangian formulation. Several case studies are examined and the results reveal the significant influence of contraction joints and cross-stream ground motions on the dynamic response and damage-cracking risk of the Guandi concrete gravity dam.

The experimental tunnels of the China Jinping Underground Laboratory are constructed in a maximum overburden depth of 2375 m and subjected to extremely high in situ stress more than 50 MPa. When these deep-buried tunnels are excavated with the method of drill and blast, the surfaces created by blasting are generated almost instantaneously, and thus the initial stress on these surfaces is also suddenly released. This transient release of in situ stress causes elastic waves to propagate in rock masses and may have an important effect on the subsequent rock vibration. In this study, a three-dimensional FEM modeling in combination with site investigation is conducted to research the Peak Particle Velocity (PPV) attenuation and frequency characteristics for the rock vibration induced by transient stress release and its combined actions with blast loading. The results indicate that the transient release of the high stress generates considerable vibration velocity that is comparable to that of blast loading. It is not a negligible excitation for the rock vibration generated in blasting excavation of deep-buried tunnels. Furthermore, the vibration induced by transient stress release has much lower frequency than that caused by blast loading. This causes the unloading vibration to decay more slowly and become the major vibration component at far distances. Also, the effect of transient stress release is found to enhance intensity of the total vibration and furthermore cause an increase in its low-frequency content. On the basis of this, the allowable charge amount per delay and the minimum safety distance are finally discussed with a special emphasis on the contributions of the transient stress release to the total vibration.

In China, the current seismic codes specify a single earthquake event as the design seismic load for concrete gravity dams. However, a large mainshock usually triggers numerous aftershocks in a short period. This paper assesses the effects of aftershocks on concrete gravity dam–reservoir–foundation systems and provides a quantitative description of the damage demands prior to and following the aftershocks. For this purpose, a set of 20 as-recorded mainshock–aftershock seismic sequences is considered in this study. The correlation between the ground motion characteristics of the as-recorded mainshocks and those of the aftershocks is examined. In order to identify the influence of the ground motion characteristics of aftershocks on the damage demands of the mainshock-damaged dams, the nonlinear behavior of the concrete gravity dams that are subjected to single seismic events and typical as-recorded seismic sequences is compared in terms of the structural damage, displacement response, and damage dissipated energy. A series of nonlinear dynamic analyses is performed to quantify the influence of aftershocks, which are selected by using different methods, on the damage demands of concrete gravity dam–reservoir–foundation systems in terms of the local and global damage indices. The results show that the aftershocks lead to an increase in the damage demands of the dam at the end of the seismic sequence when the concrete gravity dam is already damaged during the first individual seismic event and has not been repaired. In addition, the results also reveal that the repeated seismic sequences tend to underestimate the level of damage demands.

During excavation using the cut blasting method in deep rock masses, there are difficulties resulting from the in-situ stress influences. This study uses numerical simulation methods to assess the causes of the difficulties encountered in cut blasting. In order to overcome this difficulty, the Riedel–Hiermaier–Thoma (RHT) model in the LS-DYNA software was employed. In the simulation, the parameter determination for the RHT model was first carried out based on existing experimental data. Additionally, the existing blasting experiment was used to verify the determined parameters of RHT model. Second, the RHT model was adopted to investigate the damage mechanisms of cut blasting under different hydrostatic pressures and different lateral pressure coefficients. The simulation results indicate that the main causes of the complications arising in deep rock mass excavation are resistance to in-situ stresses and anisotropy in the damage propagation direction. Third, in order to overcome such difficulties, a cut blasting design optimization was conducted for a 2525 m depth of rock mass. According to the numerical simulation of this optimization, a modified cut blasting design method applicable to deep rock mass was proposed. This study can provide solutions to the cut blasting difficulties that are encountered during the excavation of deep rock masses.

In this paper, a facile and elegant Green Chemistry method for the synthesis of SnO2 based hollow spheres has been investigated. The influences of doping, crystallite morphology, and operating condition on the O2 sensing performances of SnO2 based hollow-sphere sensors were comprehensively studied. It was indicated that, compared with undoped SnO2, 10 at. % LaOCl-doped SnO2 possessed better O2 sensing characteristics owing to an increase of specific surface area and oxygen vacancy defect caused by LaOCl dopant. More importantly, it was found that O2 sensing properties of the 10 at. % LaOCl–SnO2 sensor were significantly improved by ultraviolet light illumination, which was suited for room-temperature O2 sensing applications. Besides, this sensor also had a better selectivity to O2 with respect to H2, CH4, NH3, and CO2. The remarkable increase of O2 sensing properties by UV light radiation can be explained in two ways. On one hand, UV light illumination promotes the generation of electron–hole pairs and ox...

An efficient method for the stereoselective synthesis of vinyl iodides is described. The reactions of vinyl bromides with potassium iodide proceed smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding vinyl iodides stereospecifically and in satisfactory to excellent yields.

Ground vibration, as the most critical public hazard of blasting, has received much attention from the community. Many countries established national standards to suppress vibration impact on structures, but a world-accepted blasting vibration criterion on human safety is still missing. In order to evaluate human response to the vibration from blasting excavation of a large-scale rock slope in China, this study aims to suggest a revised criterion. The vibration frequency was introduced to improve the existing single-factor (peak particle velocity) standard recommended by the United States Bureau of Mines (USBM). The feasibility of the new criterion was checked based on field vibration monitoring and investigation of human reactions. Moreover, the air overpressure or blast effects on human beings have also been discussed. The result indicates that the entire zone of influence can be divided into three subzones: severe-annoyance, light-annoyance and perception zone according to the revised safety standard. Both the construction company and local residents have provided positive comments on this influence degree assessment, which indicates that the presented criterion is suitable for evaluating human response to nearby blasts. Nevertheless, this specific criterion needs more field tests and verifications before it can be

In this paper, undoped and LaOCl-doped SnO2 nanofibers were prepared by a simple one-step electrospinning technique and their responses upon exposure to CO2 gas in different oxygen containing backgrounds were systematically investigated. It was observed that the obtained nanofibers were hollow porous structures that gave rise to excellent performance. The sensor based on 8 at.% LaOCl-SnO2 nanofibers exhibited optimal response (Rgas/Rair = 3.7) toward 1000 ppm CO2 at 300 °C with response/recovery times of 24 s/92 s, and didn’t show any saturation over a wide range of CO2 concentrations (100–20000 ppm). In terms of the sensing behavior of these sensors, their sensing mechanisms are proposed as follows: (1) In low oxygen concentration background, CO2 primarily reacts with V O , which needs high activation energy to occur, so only a slight number of CO2 can take part in the reaction. (2) In high oxygen concentration background, CO2 mainly reacts with O O × . Since this reaction conducts easily, CO2 can react with O O × sufficiently. The proposed sensing mechanisms can help readers better understand the role oxygen plays in CO2 gas sensing process.

In hydropower projects in Southwest China, large-scale, high-intensity blasts are required to excavate high rock slopes. In these cases, traditional prediction and control methods for blast vibrations are invalid. Thus, a method to predict the time history of blast vibrations on high slopes is proposed, and a blast vibration spectral control scheme based on this method is presented. Additionally, a case study for the abutment slope excavation of the Xiluodu hydropower project is presented. The results indicate that if the delay interval is 50 ms, a large amount of energy is distributed in the resonant frequency band of the slope; with optimized delay interval of 20–25 ms and 45–50 ms, the low-frequency compositions of blast vibrations are considerably fewer, and spectral control can be implemented more effectively. Delay intervals of 25 and 50 ms are adopted in practice considering the detonator limitation.

The distribution of damage in deep rock cores is critical for assessing its influence on rock mechanical characteristics. This paper presents a case study on estimating the coring damage extent induced by the stress redistribution through a combined method of numerical simulation and X-ray Computed Tomography (CT) scanning. Rock cores are taken at 1900 m depth from the test tunnel at Jin-ping Second Stage Hydropower Station (JPII) in China. Firstly, the stress path experienced by the rock core during coring has been examined by the numerical simulation, and the distribution of tensile zone in the cross-section of rock core is also discussed. Then two kinds of samples, collected from the same position under different stress levels, are scanned to obtain CT images, and a special CT value analysis strategy was adopted to evaluate coring damage intensities of these samples. The result indicates that the stress state can be regarded as the principal factor for the distribution of coring damage. During coring in the Test Tunnel of JPII under the quasi-hydrostatic stress condition, high tensile stresses (over 5 MPa) are observed at the exterior edge of rock cores, which may lead to the nucleation of microcracks around the core boundary, and the coring damage then propagates to the core centre. The CT scanning also illustrates that the coring damage zone may cover approximately 70~80% of the entire cross-section from the outside inside (stress level of 50 MPa), and that the central part of the core is less damaged or eventually undisturbed. Thus, intact rock samples can be expected to be obtained by overcoring the original rock cores. However, the applicability of the overcoring method seems to be largely dependent on the state of in-situ stress at the coring site. The whole core may be damaged if the lateral stress coefficient reaches a critical value (e.g. greater than 3.0), in which case a special coring equipment should be adopted to improve the stress state during coring.

The SnO2/Si heterojunction possesses a large band offset and it is easy to control the transportation of carriers in the SnO2/Si heterojunction to realize high-response broadband detection. Therefore, we investigated the potential of the SnO2 nanoparticle thin film/SiO2/p-Si heterojunction for photodetectors. It is demonstrated that this heterojunction shows a stable, repeatable and broadband photoresponse from 365 nm to 980 nm. Meanwhile, the responsivity of the device approaches a high value in the range of 0.285-0.355 A W-1 with the outstanding detectivity of ∼2.66 × 1012 cm H1/2 W-1 and excellent sensitivity of ∼1.8 × 106 cm2 W-1, and its response and recovery times are extremely short (