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A series of triaxial compression tests were conducted on deep-buried marble to reveal its deformation and failure characteristics along with the formation mechanism under high in-situ stress. The effects of confining pressure on the strength, deformation of marble samples were firstly analyzed. Then, the internal failure characteristics and energy evolution of the samples were comprehensively investigated based on the micro-CT scanning technology and energy balance theory. Results show that the strength and deformation at damage stress and peak stress points of marble samples increase with the increase of confining pressure. Micro-CT reconstructions reveal that the microcracks in the uniaxial compression sample are mainly tensile cracks and the failure exhibits obvious brittleness and splitting characteristics. The failure mode of triaxial compression samples gradually changes to shear failure with the increase of confining pressure. The number of cracks decreases first and then increases, and the damage is intensified around the main shear failure plane of samples under high confining pressure, resulting in a large number of conjugate secondary cracks. Further, with the increase of confining pressure, the strength increases linearly at energy hardening point, but increases nonlinearly at energy softening point. At the peak stress point, both total energy Utp and dissipated energy Udp increase in a concave function, while the elastic strain energy Uep and the circumferential strain energy U3p (negative direction) increase linearly. Besides, the damage evolution driven by energy can be roughly divided into hardening phase, energy storage phase, damage softening phase, and residual phase. These results can provide a useful reference for further understanding the failure mechanism of rock under high in-situ stress for disaster prevention.

The dynamic mechanical experiments were carried out on shales with the different bedding angles (θ = 0°, 30°, 45°, 60°, 90°) using the 50 mm split Hopkinson pressure bar (SHPB) test system with the thermo-mechanical coupling equipment. Firstly, the dynamic parameter of shales, such as the stress–strain curve, peak stress, peak strain, dynamic elastic modulus, and energy partition were acquired. The failure modes of shale samples were obtained by sorting out the fragments after impact tests. Secondly, the fracture roughness of shale was obtained using the 3D profile scanner. The experimental results revealed that the shale with different bedding angle has different critical temperature, which is based on the relative transition temperature of dynamic mechanical parameters. The dynamic mechanical properties of shale vary greatly before and after the critical temperature. The absorption energy is positively correlated with the crushing degree, the dynamic compressive strength is positively correlated with the fracture roughness, and the failure degree of shale samples is closely related to the temperature. Additionally, the dynamic mechanical properties of the shales with 0° and 90° bedding angles are obviously different from the shales with 30°, 45° and 60° bedding angles. The related findings could provide significant theoretical support for exploitation of shale gas.

Recently, transition metal selenides have been investigated extensively as promising electrode materials for high-performance supercapacitors. Herein, multi-component CoSe2/CNTs@g-C3N4 composites are prepared using a two-step hydrothermal method by incorporating one-dimensional CNTs and two-dimensional g-C3N4 nanosheets to form a network-like structure. The CoSe2/CNTs@g-C3N4 composite with a mass ratio of 1 : 3 (CNTs to g-C3N4) shows an ultra-high specific capacity of 445.4 mA h g−1 (3563.0 F g−1) at 1 A g−1, which is more than 2 times that of pure CoSe2. The assembled asymmetric supercapacitor based on CoSe2/CNTs@g-C3N4 delivers a high energy density of 77.1 W h kg−1 at 850 W kg−1. The striking capacitive performance is ascribed to the multi-dimensional synergistic contribution of two kinds of carbon materials to the electric conductivity and spatial structure of the composites, involving the improved charge transfer due to connecting g-C3N4 and the active CoSe2 by the high conductive CNT bridges, and the short ion diffusion pathways on the porous carbon framework constructed by g-C3N4 nanosheets with the assistance of CNTs.

In consideration of the failure characteristics and patterns of rocks under strong dynamic loads, the Johnson-Holmquist-Rock (JHR) damage model is proposed based on the Johnson-Holmquist ceramic (JH-2) model, the rheological-dynamical analogy (RDA) model, and Liu’s model. The proposed model comprehensively considers the strain rate effect and the deformation and failure mechanisms caused by energy flow. In order to apply the JHR model for the numerical simulation of rock-like materials, secondary development of the model is performed in the commercial software LS-DYNA, and model parameters are determined. The model parameters are then used to simulate a projectile impacting a granitic rock target and a blasting test. The numerical simulation results indicate that the JHR model is able to predict the shape of a conical plug caused by rock failure under a projectile impact, and it can simulate the failure process of rock under a blasting load. The simulation results are in good agreement with the experimental results.

Due to the serious and complicated noise in the shallow sea environment, the received signal obtained by the hydrophone is disturbed by the noise to a large extent. It has a low signal-to-noise ratio (SNR), which leads to problems such as difficulty in processing the underwater acoustic signal. To solve this problem, to more effectively remove the ocean noise in the useful signal, a denoising method based on sparse decomposition and dictionary learning is adopted. First, a complete Discrete Cosine Transform (DCT) dictionary is randomly constructed. Then the orthogonal matching pursuit (OMP) is used to represent the noisy underwater acoustic signal sparsely, the method of optimal directions (MOD) and K-singular value decomposition algorithm (K-SVD) are used to update the complete DCT dictionary respectively. According to the updated new dictionary and sparse coefficients, the underwater acoustic signal is reconstructed, and the ocean noise is removed. By denoising the different form of simulated signals with different SNRs, the results show that two methods can remove various noises mixed in the underwater acoustic signal effectively and retain the signal details while denoising. The SNR gain can reach about 20dB.

This study investigated potential imaging biomarkers for predicting the efficacy of deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients with Parkinson’s disease (PD). A total of 59 PD patients and 50 healthy control subjects underwent high-resolution 3-dimensional T1-weighted brain magnetic resonance imaging. Bilateral STN volumes were compared between the 2 groups, and a correlation analysis was performed to assess the relationship between bilateral STN volumes or intracranial volume (ICV) and pre- or postoperative clinical scale scores. The results showed that the left STN volume differed significantly between PD patients and controls. In patients, the left STN volume was negatively correlated with pre- and postoperative quality of life scores and positively correlated with Mini-mental State Examination (MMSE) and Montreal Cognitive Assessment scores; ICV was also positively correlated with the MMSE score. These findings indicate that changes in the left STN volume are a useful biomarker for evaluating the clinical outcome of PD patients following DBS.

As inspired by the surging demand for high performance energy storage systems, researchers have been designing and exploring advanced electrode materials exhibiting higher energy and power densities. In this study, a novel combination of nickel-cobalt sulfide and oxide was reported for high performance supercapacitors. The porous α-Ni(Co)S@NiCoO2 composites with core–shell structure were derived from the well-designed precursor with Ni2CoS4 and ZIF-67 serving as the self-sacrificing templates through a two-step calcination process at elevated temperatures. Such a heterostructure exhibited an ultra-high specific capacity of 502.4 mAh g–1 at a current density of 1 A g–1, which was attributed to the unique porous core–shell structure and the ingenious combination of bimetallic sulfide and oxide. Furthermore, a hybrid supercapacitor based on the α-Ni(Co)S@NiCoO2 composite and commercial activated carbon achieved a high energy density of 82.4 Wh kg–1 at a power density of 847.5 W kg–1. The prominent electrochemical performance exhibited by the α-Ni(Co)S@NiCoO2 heterostructure in this study was demonstrated to be promising to practically serve as advanced electrode materials in supercapacitors.

Coaxial nanocable heterostructures consisting of highly conductive carbon nanomaterial core and active transition-metal compound sheath are promising potential candidates for advanced energy storage materials. Herein, the multi-functional selenium‐doped carbon nanotubes/nickel selenide coaxial nanocables with chemical bonding interface are prepared by using an electroless deposition combined with the following chemical vapor reaction process, in which the nickel layer is first deposited onto the carbon nanotube core and subsequently transformed in-situ into the nickel selenide sheath by the controlled selenization reaction at elevated temperature. Such coaxial structure provides the large active material/electrolyte contact area, and the fast diffusion and transfer of mass and charge in the electrochemical process, thus which endows superior supercapacitive and good lithium storage performances. The coaxial nanocables exhibit a high specific capacity of 340.0 mAh g−1 at 1 A g−1 as an electrode for supercapacitor, and a lithium storage capacity of 600.0 mAh g−1 at 0.1 A g−1 as an anode for lithium-ion batteries. A supercapacitor based on the nanocables delivers a high energy density of 70.0 Wh kg−1 at 803.0 W kg−1 and long cycling stability with 65.0% capacitance retention after 8000 cycles at 10 A g−1.

Background To investigate the predictive value of energy spectral CT parameters for Ki-67 expression in lung cancer. Methods In this retrospective analysis, 27 primary lung cancer patients confirmed by pathological examination were enrolled between December 2018 and February 2019. All patients underwent baseline arterial phase (AP) and venous phase (VP) energy spectral CT scanning followed by surgery in our institution. The iodine concentration (IC), normalized iodine concentration (NIC) and the slope of 40-80 keV energy spectrum curve (λHU) were derived from dual-energy virtual imaging on a Siemens postprocessed workstation. Immunohistochemical examination was performed to analyze Ki-67 expression. The ROC curves were used for predicting the performance of energy spectral parameters for Ki-67 expression. Results The tumors appeared larger in Ki-67 high expression group than the low expression group (P=0.046). The energy spectral parameters were higher in venous phase when compared to arterial phase, but only the venous phase NIC (vpNIC) was significantly different from that of the arterial phase NIC (apNIC) (P

Purpose To compare 3D liver acceleration volume acquisition (LAVA) and digital subtraction angiography (DSA) for evaluating the presence of accessory hepatic veins (AHV) in Budd-Chiari syndrome (BCS). Materials and Methods This was a retrospective study in 228 patients with BCS who underwent 3.0T magnetic resonance imaging (MRI) with the 3D LAVA sequence. Two reviewers noted AHV: openings located in the inferior vena cava (IVC), caliber, and the angle of entering into the IVC. MRI results were compared to DSA. Kappa statistics were calculated to quantify intrareader variability in detecting AHVs. Results On MRI, 63 patients demonstrated no AHV on LAVA images, 70 had one AHV, 62 had two AHVs, 26 patients had three AHVs, six patients had four AHVs, and one patient had five AHVs (P < 0.05 vs. DSA). The mean caliber of the AHVs was 8.3 ± 4.0 mm compared to 9.9 ± 3.2 for DSA (P < 0.001). Among the 301 AHVs, there were 140 with acute angles (46.5%), 71 with right angles (23.6%), and 90 with obtuse angles (29.8%). The prevalence of AHVs on DSA was 54.8% (125/228), while MRI demonstrated 301 AHVs in 165 patients, for a prevalence of 72.4% (165/228) compared to 54.8% for DSA (P = 0.001). The two methods were concordant in only 116/228 (50.9%) patients. The kappa coefficient demonstrated good intrareader consistency for all documented MRI findings of AHVs (κ = 0.626 for caliber and κ = 0.65 for angles). Conclusion More AHVs were visible on MRI LAVA sequences than on conventional DSA. Level of Evidence: 4 J. Magn. Reson. Imaging 2017;45:401–409.

Drilling and blasting method as a common excavation method is widely used in the underground engineering construction. However, in the complicated geological conditions, the path of blasting excavation available has limitation, and then the larger blasting vibration is produced, which influence the stability and safety of the protected structure. To effectively reduce the blasting vibration by optimizing the blasting excavation method, firstly, the site test on blasting vibration is conducted to obtain the blasting vibration data; secondly, the LS-DYNA software is applied to simulate the vibration generated by blasting in site test, based on back analysis on the blasting vibration, the mechanical parameters of the rock mass are obtained, and they are used to simulate six different types of blasting excavation method. According to the analysis on them, the reasonable blasting excavation method is proposed to reduce the blasting vibration which can satisfy the blasting safety regulation.

The aim of the current study was to investigate the atrial septal aneurysm (ASA) incidence rate and describe its morphologic features by dual-source computed tomography (DSCT). A total of 8,626 patients (4,284 men and 4,342 women) who underwent DSCT examinations were enrolled. The presence of ASA was defined as the protrusion of the complete or partial interatrial septum with a maximum vertical distance (MVD) from the atrial septum plane of >10 mm during a cardiac cycle and a diameter of the aneurysm base of >15 mm. The MVD and direction of the protrusion, as well as other abnormalities, were recorded. The ASA patients were classified by both gender and directions of protrusion into four groups, including the right atrium (RA) and left atrium (LA) groups in males and females, respectively. Values across groups were compared using the independent-sample t-test and differences in qualitative variables were assessed with the χ2 test. Of the 8,626 patients, 51 (0.6%) were diagnosed with ASA (mean age, 62±10 years), including 23 (0.5%) males and 28 (0.6%) females. There were no significant differences in the age (t=-1.37, P>0.05) and incidence rate (χ2=0.43, P>0.05) between the male and female groups. However, there were significant differences in the mean ages (t=-2.20, P

To compare 3D liver acceleration volume acquisition (LAVA) and digital subtraction angiography (DSA) for evaluating the presence of accessory hepatic veins (AHV) in Budd-Chiari syndrome (BCS).This was a retrospective study in 228 patients with BCS who underwent 3.0T magnetic resonance imaging (MRI) with the 3D LAVA sequence. Two reviewers noted AHV: openings located in the inferior vena cava (IVC), caliber, and the angle of entering into the IVC. MRI results were compared to DSA. Kappa statistics were calculated to quantify intrareader variability in detecting AHVs.On MRI, 63 patients demonstrated no AHV on LAVA images, 70 had one AHV, 62 had two AHVs, 26 patients had three AHVs, six patients had four AHVs, and one patient had five AHVs (P0.05 vs. DSA). The mean caliber of the AHVs was 8.3 ± 4.0 mm compared to 9.9 ± 3.2 for DSA (P0.001). Among the 301 AHVs, there were 140 with acute angles (46.5%), 71 with right angles (23.6%), and 90 with obtuse angles (29.8%). The prevalence of AHVs on DSA was 54.8% (125/228), while MRI demonstrated 301 AHVs in 165 patients, for a prevalence of 72.4% (165/228) compared to 54.8% for DSA (P = 0.001). The two methods were concordant in only 116/228 (50.9%) patients. The kappa coefficient demonstrated good intrareader consistency for all documented MRI findings of AHVs (κ = 0.626 for caliber and κ = 0.65 for angles).More AHVs were visible on MRI LAVA sequences than on conventional DSA.4 J. Magn. Reson. Imaging 2017;45:401-409.

To evaluate image quality of low-voltage coronary artery computed tomographic (CT) angiography with low contrast agent in comparison with image quality.Forty-five patients underwent coronary artery computed tomographic (CT) angiography. They were randomly assigned to 3 groups, group A (n = 15) were scanned in 120 kVp with 350 mgI/ml iodinated contrast agent mode, group B (n = 15) were scanned in 100 kVp with 350 mgI/ml iodinated contrast agent mode, group C (n = 15) were scanned in 100 kVp with 270 mgI/ml iodinated contrast agent mode. Then measured CT attenuation value of three main branches (RCA, LAD and CX) of coronary artery, And compare the SNR, CNR, the effective radiation dose(ED) and iodine intake. The Kappa test were used to quantify inter- and intra-reader agreement in detecting quality of the images under different scanning solutions.Three groups of coronary artery CT image quality was no statistically significant differences (all P values0.05), Good inter- and intra-reader agreement ( k = 0.754, P0.05) for the detection of noise in all the patients. There was significant difference in the CT attenuation of RCA, LAD and CX among the 3 groups (P0.05), the CT attenuation was the highest in group B, the CT value of RCA, LAD and CX were 537 ± 90, 505 ± 90, 484 ± 75 HU, respectively.the CT attenuation was the lowest in group C, the CT value of RCA, LAD and CX were 357 ± 126, 360 ± 95, 378 ± 121 HU, respectively. There was no significant difference in the SNR and CNR among the 3 groups (P0.05). There was significant difference in the ED among the 3 groups (P0.05). The ED value of the group A was bigger than the value of the group B and C. There was no significant difference between the group B and C. Compared the group A and B, the iodine intake of the group C had fallen by 23%.The coronary artery CT angiography using 100 kVp with 270 mgI/ml iodinated contrast agent provide similar objective or subjective image quality compared with the (350 mgI/ml) and the 100 kVp (350 mgI/ml), thus enabling effective dose and iodine intake reduction without loss of diagnostic information.

This study aimed to evaluate the correlation between coronary stenosis and left ventricular function using dual-source computed tomography (DSCT). DSCT coronary angiography (CAG) was performed on 66 patients with coronary disease and 36 healthy volunteers. The degree of coronary stenosis, end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and myocardial mass (MM) were measured for the left ventricle. These values were compared with the results obtained by echocardiography (ECHO) and selective CAG, which were both adopted as controls. The diagnoses of coronary stenosis based on DSCT CAG and those based on selective CAG were not significantly different (P>0.05). Similarly, the values of EDV, ESV, SV or EV measured by DSCT CAG were not significantly different from thoses obtained by ECHO (P>0.05). However, significant differences were observed in the ESV, EF and SV of the severe stenosis group compared with the moderate and mild stenosis groups (both P