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Anti-inflammatory drugs for ulcerative colitis (UC) treatment should specifically penetrate and accumulate in the colon tissue. Herein, a multi-bioresponsive anti-inflammatory drug (curcumin, CUR)-loaded heterogeneous double-membrane microgels (CUR@microgels) for oral administration was fabricated in this study, in which the inner core was derived from polyvinyl alcohol (PVA) and guar gum (GG) and the outer gel was decoration with alginate and chitosan by polyelectrolyte interactions. The structure and morphology of microgels were characterized. In vitro, the formulation exhibited good bio-responses at different pH conditions and sustained-release properties in simulated colon fluid with a drug-release rate of 84.6 % over 34 h. With the assistance of the outlayer gels, the microgels effectively delayed the premature drug release of CUR in the upper gastrointestinal tract. In vivo studies revealed that CUR@microgels specifically accumulated in the colon tissue for 24 h, which suggest that the interlayer gels were apt to reach colon lesion. As expected, the oral administration of microgels remarkably alleviated the symptoms of UC and protected the colon tissue in DSS-induced UC mice. The above results indicated that these facilely fabricated microgels which exhibited excellent biocompatibility and multi-bioresponsive drug release, had an apparent effect on the treatment of UC, which represents a promising drug delivery strategy for CUR in a clinical application.

Particle flow numerical simulation was used to reproduce the transient unloading process of a deep-buried single fracture tunnel. The influence of fracture characteristics on the transient unloading effect was analyzed from the aspects of stress state, deformation characteristics, fracture propagation, and energy conversion. The results shows that the surrounding rock stress field of the deep-buried tunnel is divided into four areas: weak stress area I, strong stress area II, stress adjustment area III, and initial stress area IV. The fracture has an important impact on the stress adjustment process of transient unloading of the deep-buried tunnel, and the stress concentration area will be transferred from the bottom corner of the chamber and the vault to the fracture tip. With the increase in the fracture length, the distance from the stress concentration area at the fracture tip to the free surface gradually increases, and the damage area of the surrounding rock gradually migrates to the deep area of the rock mass. At this time, the release amount of strain energy gradually decreases and tends to be stable, while the dissipation energy shows a near ‘U’ shape change trend of decreasing first and then increasing. Under different fracture angles, the number of mesocracks is significantly different. Among them, the number of mesocracks in the 60° and 30° fractured surrounding rocks is greater followed by the 0° fractured surrounding rock, and the number of mesocracks in the 45° and 90° fractured surrounding rocks is relatively less. In addition, the proportion of compression-shear cracks shows a change trend of increasing first and then decreasing with the increase in the fracture angle, and it reaches the maximum value in the 45° fractured surrounding rock.

Adsorption performances between the OMS-2 catalyst and CH4 and O2 molecules are enhanced with increasing tunnel K+ concentration.

In underground engineering, shear failure is a common failure type in coal-rock mass under medium and low strain-rate disturbance loads. Analyzing the shear failure mechanical properties of coal-rock mass under dynamic normal load is significant. In order to reveal the influence of disturbance load on the shear mechanical properties of coal rock, a dynamic and static load coupling electro-hydraulic servo testing machine was used to conduct the shear tests of coal-like rock materials under dynamic and constant normal load. The amplitude of dynamic load is 10 kN and the frequency is 5 Hz. The damage process of the specimens was detected by the acoustic emission (AE) detection system. The results imply that the shear failure process of coal-like rock materials under constant normal load can be divided into four stages. The normal disturbance decreased the shear strength of the specimens and increased the shear modulus of the specimens. With the increase in normal load, the influence of disturbance on the shear strength of the specimen decreased. By analyzing the AE parameters, it was found that the dynamic load made the internal damage of the specimen more severe during the shear failure process. The damage variable was calculated by AE cumulative energy, and the damage evolution was divided into three stages. The shear failure mechanism of the specimen was judged by RA (rise time/amplitude) and AF (average frequency). It was found that from the elastic deformation stage to the unstable development fracture stage, the proportion of shear fracture increased. When the dynamic normal load was 10 kN and 30 kN, the fracture was mainly shear fracture; When the dynamic normal load was 50 kN, the fracture was mainly tensile or mixed fracture. The dynamic normal load affects the shear strength and failure mechanism. Therefore, the influence of disturbance load on coal-rock mass strength cannot be ignored in underground engineering.

It is very important and effective to characterize the failure mechanism of coal and rock materials from the perspective of energy. Energy dissipation and release are important causes of rock mass failure. To qualitatively and quantitatively characterize the energy evolution process of gas-bearing coal and the energy evolution mechanisms of coal and gas outburst, experimental studies were conducted on gas-bearing coal under different stress paths. The research results demonstrate that the energy evolution of gas-bearing coal has nonlinear characteristics and that the energy density is a quadratic function of stress. The total energy density is mainly stored as elastic energy density and is unrelated to loading paths. According to the distribution characteristics of abutment pressures in a stope, the energy distribution can be divided into an energy dissipation and release zone, an increasing-energy zone, and a stable energy storage zone. During coal mining, abutment pressure in front of the coal wall is an important factor causing energy accumulation, and the stress concentration area is a key area to prevent and control dynamic disasters of coal and rock masses. Furthermore, based on the principle of energy conservation, this study established an energy balance model for coal and gas outburst and derived energy criteria for coal and gas outburst. When $$\Upsilon > 1$$ , there is a risk of coal seams have outburst. If $$\Upsilon = 1$$ , the system is in a state of limit equilibrium, and mining disturbances could trigger outburst.

The compound dynamic disaster of coal and gas outbursts and rockburst is a typical hazard jeopardizing the mining of the high gas content coal seam under a hard roof condition. In this study, the hard roof’s mechanism inducing this hazard is analyzed. Physical analog modeling experiments and in situ monitoring of mining-induced stress were performed during coal seam mining under a hard roof condition. The pattern of hard roof breakage effect on the stress-fissure field evolution was revealed. The elastic energy was released and propagated on both sides immediately after the hard roof breaking, leading to energy accumulation. Meanwhile, expansive roof collapse resulted in the intense weighting of the working face and rockburst. Thus, the coal and gas outburst occurred under the joint action of the impact energy generated by breaking the hard roof and gas expansion energy. In other words, the compound dynamic disaster happened. Synergistic stereoextraction integrating cross-seam drilling and along-seam drilling was combined with deep hole advanced presplitting blasting technology to cope with the compound dynamic disaster in the high gas coal seam under a hard roof condition.

Shape registration is a vital task in computer vision and image processing, but the topology changes always occur in registration process of two shapes with large deformation. In this paper, we address the shape registration with large deformation by an atlas based method. Concretely, we first represent the shape by the square root velocity functions (SRVFs) which makes registration of two shapes with small deformation well. Then, we hierarchically cluster all shapes and form a clustering tree under this representation. Further, by searching the shortest path connecting two shapes we realize the registration with topology preserving. Finally, the numerical results on the Kimia shape dataset show that our proposed method achieves a better performance of registration than the conventional method. That is, the atlas-based strategy is valid for shape registration with large deformation.

PurposeThe purpose of this paper is to present a novel method for minor fabric defects detection.Design/methodology/approachThis paper proposes a PETM-CNN algorithm. PETM-CNN is designed based on self-similar estimation algorithm and Convolutional Neural Network. The PE (Patches Extractor) algorithm extracts patches that are possible to be defective patches to preprocess the fabric image. Then a TM-CNN (Triplet Metric CNN) method is designed to predict labels of the patches and the final label of the image. The TM-CNN can perform better than normal CNN.FindingsThis algorithm is superior to other algorithms on the data set of fabric images with minor defects. The proposed method achieves accurate classification of fabric images whether it has minor defects or not. The experimental results show that the approach is effective.Originality/valueTraditional fabric defects detection is not effective as minor defects detection, so this paper develops a method of minor fabric images classification based on self-similar estimation and CNN. This paper offers the first investigation of minor fabric defects.

For the sake of improving the reliability of the method for well pattern density optimization of tight sandstone gas reservoir and effectively demonstrate the relationship between well pattern density and recovery efficiency, the well interference probability curve of the target study area in the Sulige Gas Field was plotted by establishing the calculation method for well interference probability. Then, a new method suitable for well pattern density optimization and recovery efficiency evaluation of tight sandstone gas reservoirs was established. Finally, this new method was applied in three encryption test areas of the Sulige Gas Field. And the following research results were obtained. First, the well interference probability of tight sandstone gas reservoir is heavily dependent on the well pattern density. With the increase of the well pattern density, the well interference probability presents a gradual increasing trend. And the well interference probability doesn't reach or approach to 1 until the well pattern density reaches a higher value. Second, in the three encryption test areas of the Sulige Gas Field, the economically optimal well pattern density is in the range of 2.6–3.1 wells/km2, and its corresponding recovery efficiency is 36.6–39.8% and corresponding well interference probability is 28–33%, while the economic limit well pattern density is in the range of 5.2–6.6 wells/km2, and its corresponding recovery efficiency is 46.8–49.8% and corresponding well interference probability is 83–89%. Third, the well interference probability corresponding to the economically optimal well pattern density of tight sandstone gas reservoir in the Sulige Gas Field is about 30%, and that corresponding to the economic limit well pattern density is about 85%. In conclusion, by virtue of this new method, the economically optimal well pattern density and the economic limit well pattern density and their corresponding recovery efficiencies can be calculated, so as to realize the well pattern optimization and recovery efficiency evaluation of tight sandstone gas reservoirs. The research results can provide theoretical support for the economic and efficient development of the Sulige Gas Field, and useful reference for the benefit development of the same type of gas reservoirs. Keywords: Tight sandstone gas reservoir, Interference probability, Recovery efficiency, Economically optimal well pattern density, Economic limit well pattern density, Ordos Basin, Sulige Gas Field

In order to solve the problems of roadway stability and easy instability under repeated mining of close-distance coal seam groups, the mechanism and control technology of surrounding rock instability under repeated mining were studied via indoor testing, field testing, physical similarity simulation experiment, and numerical simulation. The results show that the surrounding rock of roadway has low strength, low bearing capacity, and poor self-stabilization ability, and it is vulnerable to engineering disturbances and fragmentation. Affected by the disturbance under repeated mining, the roadway surrounding rock cracks are developed and the sensitivity is strong, and it is prone to large-scale loose and destroyed. The location of the roadway is unreasonable, and the maximum principal stress of the roadway is 3.1 times of the minimum principal stress, which is quite different. Thus, under a large horizontal stress, the surrounding rock undergoes long-range expansion deformation. On the basis of this research, the direction and emphasis of stability control of roadway surrounding rock under repeated mining of coal seam groups in close-distance are shown. A repair scheme (i.e., long bolt + high-strength anchor cable + U-shaped steel + grouting) is proposed, and reduces the risk of roadway instability.

The fluid–solid coupled with triaxial servo-controlled seepage experiments of coal containing gas was used to study coal samples from a coal mine in Sichuan Province, China. The mechanical characteristics, seepage laws, energy dissipation, and fracture evolution of raw coal under incremental tiered cyclic loading and different confining pressures were studied. The experimental results show that as the axial stress increases, the axial relative residual strain curve changes in an "N" shape, while the radial relative residual strain curve always increases. The change in the relative residual strain can be divided into three stages: compaction stage, elastic stage, and yield–failure stage. Except for in the last cycle, as the cycle number increases, the dissipated energy of coal increases linearly. With increasing cycle number, the difference in energy dissipation under different confining pressures gradually increases. During the yield–failure stage, some closed fractures inside the coal began to expand, and new fissures and cracks were generated, causing a large residual deformation and leading to a sharp increase in the dissipated energy and elastic modulus. Additionally, from the perspective of energy, a new method for calculating the elastic modulus (referred to as the equivalent elastic modulus) using the integral method was proposed.

This study presents a comprehensive field investigation of the ground response of a gateroad subjected to high stress induced by extracting a 17 m-thick coal seam. The test site is located at Datong City, Shanxi Province, China. The measurement results of the entry convergence and fracture development indicated that the gateroad with a 30 m-wide coal pillar maintained a good performance during the development period but suffered a strong response, including roof sag, floor heave, support unit failure and internal fractures sharply developed during the current panel-retreating period. During panel retreating, the impact range of the mining disturbance was about 110 m ahead of the active panel, and the mining disturbance accelerated dramatically at 50–60 m ahead of the mining panel. The results of the borehole stress measurement showed that the maximum stress induced in the virgin coal pillar and the coal pillar reached 15.3 MPa and 23.9 MPa, which are about 1.5 and 2.3 times the initial ground stress, respectively. This high stress contributed significantly to the instability of the gateroad. The average stress within the coal pillar was greater than that in the virgin coal pillar, and a high-stress zone was found at the coal pillar depth of 11–20 m. This stress distribution characteristics implies that the 30 m-wide coal pillar has a relatively sufficient bearing capacity to withstand the majority of mining-induced loads and that the coal pillar size could be reduced from 30 to 15–20 m wide to decrease the range of high stress in the coal pillar. Furthermore, taking into consideration of intense mining disturbance and abundant time interval for gateroad development as well as a high-strength support scheme, a small-width coal pillar of 8 m was recommended and tentatively applied in the field. The field application demonstrated that the newly designed pillar size and support pattern could ensure gateroad stability at some level. The study finding can help to better understand the stability control of entry driven along gob-side and its correlation with coal pillar size as well as the mining disturbance in specially thick coal seam (ETCS). In addition, the design principle and support strategy for the coal pillar in ETCS presented in this study can potentially be applied to other similar projects.

Single-walled carbon nanotubes (SWNTs) are synthesized from iron silicide (FeSi) catalyst by the chemical vapor deposition (CVD). During the growth process, Fe atoms migrate onto the FeSi surface and form active Fe nanoparticles, catalyzing the growth of SWNTs. The produced SWNTs demonstrate a narrow diameter/chirality distribution, possibly arising from the solid state of Fe nanoparticles and the use of carbon monoxide (CO) as the carbon source, which facilitates SWNT growth by perpendicular mode. Remarkably, (12, 6) SWNTs occupies more than 40% of all the SWNTs, as detected by Raman spectroscopy. This work opens an avenue for chirality selective synthesis of SWNTs by applying silicide as the catalyst.

Research on bolt reactions under cyclic disturbance is still sparse due to complex and special laboratory processes. This paper endeavours to reveal the mechanical response and acoustic emission (AE) characteristics of bolts under cyclic loading, and a series of short encapsulated cyclic thrust tests (SECTTs) was conducted. First, the threshold determining stress level in the cyclic process was defined based on monotonic thrust tests, and the stress distribution along the steel tube was obtained simultaneously. Second, tests specified by staged cyclic loading with varied cyclic counts at each stage were conducted, and the influence of the cyclic count on the stability of the bolting system was evaluated. Third, tests specified by staged cyclic loading with holding intervals were conducted, and the creep behaviour of the bolting system was investigated. Controlling factors such as frequency, amplitude, and cyclic count were comprehensively considered. Fourth, two tests specified by staged cyclic loading with high cyclic count were conducted, and the influences of high cyclic count were discussed. Generally, a short encapsulated bolt undergoing cyclic loading behaved differently from a statically loaded bolt, and some interesting results were observed based on analysis of AE properties, strengthening effects, creep behaviour, failure prediction, bearing capacity evaluation, etc. At the end of this study, the reasonability and deviation of SECTT adopting steel tubes to simulate rock masses in the laboratory were discussed.

Bumped bamboo carbon nanotubes (carbon nanosprouts) were directly synthesized on calcined stainless steel by chemical vapor deposition. Using a mixture of CO and H2 as the carbon precursor, dense carbon nanosprouts were formed on the surfaces of stainless-steel wire without external catalyst addition. The air calcination favours the formation of iron oxide nanoparticles with relatively small diameters, catalysing the synthesis of carbon nanosprouts with comparable trunk diameters. Transmission electron microscopy analysis shows that Fe2.5C is the active catalyst phase and catalyst deactivation is caused by graphitic layer encapsulation. The enhanced carbon precipitation of Fe catalyst, promoted by the carbon source dissociation or its synergism with other metal, is responsible for the generation of nanosprouts.

This paper was to explore distribution and evolution of surrounding rock stress as well as roadway deformation failure during the exploitation of working faces in complex stope. Here, distribution and evolution laws of surrounding rock stress and strata pressure behaviors in the complex island panels 1213(1) in a mine in Huainan Mine during early isolation, overhead mining, normal isolation and stopping in gob were analyzed by combining FLAC3D numerical simulation and field measurement. Results were shown that surrounding rock stress distribution along the strike direction and incline direction, abutment pressure peak value and position as well as surrounding rock deformation in the roadway were different in different mining stages. Different spatial stope layout (left and right gob, lower gob and upper gob) could influence the abutment pressure distribution on working faces, stress concentration range and surrounding rock deformation in roadway significantly. Therefore, professional analysis, reasonable design and safety mining should be performed in advance according to specific engineering geological conditions. Research conclusions could provide certain engineering references and guidance to stope arrangement, optimal design of mining roadway and mine pressure control.

The coupling between hysteresis and linear dynamics remains a challenge for modeling and control of piezo-actuated nanopositioning stages. A decoupling identification approach is proposed in this paper. The system is first modeled by a Bouc–Wen hysteresis model cascading a linear dynamic part. Then, a proposed direct integration method with high computational efficiency is used for the identification of the Bouc–Wen model. With the identified hysteresis parameters, a harmonic linearization method is subsequently used to estimate the actual input to the linear dynamics. Experiment results on a two degree-of-freedom nanopositioning stage demonstrate that both the rate-dependence and amplitude-dependence resulted from the coupling between the hysteresis and linear dynamics can be well predicted by the proposed approach. Compared with existing methods, the proposed approach shows advantages in terms of both model accuracy and identification efficiency.

After examining the roof strata movement pattern of fully mechanized mining (or caving) with large mining height, a roof structural model for large mining-height stopes was established based on their overlying rock structure; the overlying rock structure and movement pattern of these stopes were investigated; a method for determining the support working load and yield under "given deformation" and "limited deformation" states was proposed; the concept of immediate roof in mining operation with large mining height was modified; the roof control design criteria and support load calculation method for large mining-height stopes were established. The result indicates that increases in the mining height will largely increase the thickness of the immediate roof as well as the possibility of hard rock with large-span suspension top in the immediate roof. The key strata of the main roof having notable influences to stope strata behavior can be divided into two types of structures: a "single key stratum" structure and a "double key strata" structure. If the main roof was a "double key strata" structure, it will be important to prevent both threats like roof cutting or prop over yield in response to movement of the underlying key stratum, and the dynamic pressure impact to the stope in times of weighting of the overlying key stratum. Accurately determining the position, thickness and potential maximum suspended span of the suspension top was the key for the roof control design and support selection calculation for large mining-height stopes.

The uniformity and microstructure of the copper deposition in the high aspect ratio plated through holes (penetrating holes) are crucial for the performance of printed circuit board. We systematically investigated the effects of reverse pulse parameters in the period pulse reverse (PPR) plating on the uniformity and microstructure of the copper deposition, including reverse pulse frequency, reverse pulse duty cycle and reverse pulse current density. The Cu deposition behavior (throwing power) and its crystallographic characteristics, including grain size, crystallographic orientation, and grain boundary, were characterized by means of field-emission scanning electron microscopy (FE-SEM), X-ray diffractometer (XRD), and electron backscatter diffraction (EBSD). Our results clarify that the reverse pulse current density and duty ratio should be low to achieve the full filling and high uniformity of the through holes. The reverse pulse frequency of 1500 Hz would prevent the through holes to be fully filled. The copper electrodeposition in PTH prepared by double pulse electrodeposition has the good (111) surface texture and grain boundary distribution. This work demonstrated that the period pulse reverse (PPR) plating provides unique advantages in achieving the ultra-uniform copper deposition in the high aspect ratio plated through holes.