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In the urban environment, the transient electromagnetic method often suffers from severe electromagnetic interference because it employs coils to perceive the electromagnetic field. To address this issue, the DC method employs electrodes to shield the electromagnetic noise in the urban environment. In this paper, a new geophysical resistivity imaging sensing approach based on a DC inversion model is proposed to explore and identify the path of underground water to solve the water disaster problem. A real-world case study is carried out in Xinjiang Region. In order to investigate the underground water conducted path, an electrode network is designed and installed for the buildings of interest to collect the DC electrical current and DC electrical potential data. Then, the proposed method establishes a DC resistivity inversion model based on the forward theory and finite-volume technique to extract the geological information from the collected data and visualize the underground water conducted path. Different from existing popular numerical techniques, such as the finite element and finite difference, the finite-volume technique has clear theoretical explanations to make the obtained geological images understandable. As a result, the underground water path can be directly observed from the geological images calculated by the proposed approach to successfully identify and locate the underground water disaster in real-world applications.

The Yellow River Basin (YRB) has experienced severe floods and continuous riverbed elevation throughout history. Global climate change has been suggested to be driving a worldwide increase in flooding risk. However, owing to insufficient evidence, the quantitative correlation between flooding and climate change remains ill-defined. We present a long time series of maximum flood discharge in the YRB dating back to 1843 compiled from historical documents and instrument measurements. Variations in yearly maximum flood discharge show distinct periods: a dramatic decreasing period from 1843 to 1950, and an oscillating gentle decreasing from 1950 to 2021, with the latter period also showing increasing more extreme floods. A Mann-Kendall test analysis suggests that the latter period can be further split into two distinct sub-periods: an oscillating gentle decreasing period from 1950 to 2000, and a clear recent increasing period from 2000 to 2021. We further predict that climate change will cause an ongoing remarkable increase in future flooding risk and an ∼44.4 billion US dollars loss of floods in the YRB in 2100.

With the soaring interest in art as an alternative investment approach and an asset class, there has been a remarkable rise in the volume of artwork transactions globally. However, trading in the art market differs from the traditional financial market; the cost of taxes, logistics, storage, and other transaction services is enormous for collectors, stimulating the emergence of related businesses, such as warehousing, bonded exhibitions, and art financial services. As an exceptional area serving the offshore economy, art freeports have become an essential venue for art trading and a ‘one-stop-shop’ centre that converges all art market participants. This article critically analyses the current literature and conducts empirical research on Shanghai FTZ International Culture Investment and Development Co., Ltd. (FTZART). It can be concluded that the current research on art freeports is limited and excludes FTZART from those that specialise in storing artworks, overlooking its potential influence in the Asian market. The art freeport has distinctive features that differ from traditional freeport models, and the context, business model, and operations of FTZART match these characteristics. Therefore, as a hub in the art market, the global art freeport agenda should not overlook FTZART, and it is essential to complement this gap in knowledge.

Amorphous metal catalysts often exhibit appealing catalytic properties, however, accurate control synthesis of amorphous nano-metal catalysts is a challenge. Here, the authors report a feasible strategy to prepare the amorphous Cu catalysts by supercritical CO2 treatment followed by electroreduction. The resulted catalyst shows high selectivity towards multi-carbon products for CO2 electroreduction.

Ferric acetylacetonate/covalent organic framework (Fe(acac)3/COF) composite was synthesized by interfacial polymerization method at room temperature. The crystal structure, morphology and porosity property of the composite were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and nitrogen adsorption. The interaction between Fe(acac)3 and COF was investigated by Fourier transform infrared spectra and X-ray photoelectron spectroscopy. The Fe(acac)3/COF composite was used as a photocatalyst for the oxidation of benzyl alcohol under mild conditions. It exhibits high activity and selectivity for the reaction, of which the mechanism was investigated by determining its photoelectric properties. The Fe(acac)3/COF catalyst developed in this work has application potential in other photocatalytic reactions.

The limit analysis of slope stability has a relatively higher calculation efficiency and accuracy because it ignores the constitutive relation of materials. Compared to the limit equilibrium method, its assumptions are strict and realistic. In the classical upper bound limit analysis, the slope surfaces are required to be a regular straight line. However, the surfaces of natural or cutting slopes are normally nonlinear. In addition, the stability number Ns=c/γH is used to calculate the critical height of slopes without considering the external power caused by pore pressure. Different from the static equilibrium conditions adopted by the traditional limit equilibrium method, this paper aimed to evaluate the stability of slopes with nonlinear surfaces based on kinetic analysis. First, a method for determining the rotation center of landslides with nonlinear surfaces based on upper bound limit analysis and the principle of virtual work was proposed. Second, it was assumed that the sliding surface was a logarithmic helix, and the virtual work under gravity and energy equilibrium equation of slopes were established. Third, the stability coefficient K defined by the ratio of internal power to external power was proposed to evaluate the stability of the slope, and the results were compared with the Bishop method to verify its effectiveness. The influences of slope degree (β), internal friction angle (φ), cohesion (c) and pore pressure coefficient (ru) on the stability coefficient K of different natural and cutting slopes were analyzed. The results confirmed that the stability of steep slopes would be improved by cutting. The stability coefficient K increased with increasing cohesion and decreased with increasing pore water pressure coefficient. When the impact of cohesion on the stability coefficient K was more significant than that on the pore water pressure coefficient, K increased with increasing internal friction angle (φ). In contrast, the stability coefficient K decreases with increasing internal friction angle (φ). The above results followed the general understanding of slope stability analysis, and the rationality of the model was verified. By comparing the calculation results with the Bishop method, it was found that the intension of the critical state represented by safety factor FS=1 was the same as the stability coefficient K=0 defined in this paper. The stability coefficient K increased nonlinearly with increasing cohesion, which was in line with the progressive failure mode of the soil slopes.

Slope kinematics is normally used to evaluate the temporal and spatial evolution of landslides. The inverse velocity method (INV) is an important tool for predicting the initiation of landslide, but its correlation with the physical and mechanical mechanisms of multiple physical fields inside the landslide need to be further clarified. In this paper, the slope deformation and geological characteristics of the Lijie Beishan landslide in Zhouqu, Gansu Province was investigated. The inverse velocity method, velocity threshold method and numerical simulation based on unsaturated soil theory were used to study the kinematic characteristic of slope. The results showed that after the lowest value of the inverse velocity on June 3, 2021, a stable stage lasted for approximately 60 days and then suddenly accelerated on September 20. The velocity became more than 200 mm/d over 20 days, and the deformation did not converged. There was an obvious acceleration point in the time-dependent inverse velocity curve. The end of the landslide life cycle was obtained by extending the straight line after the onset of the acceleration point. The prediction period was within 8 days compared to the actual instability startup, and the landslide was predicted 130 days in advance. According to the post analysis of the whole time-dependent velocity curve, the multi-level speed thresholds of v1=20 mm/d, v2=60 mm/d, and v3=100 mm/d were set up. Because there were two peaks of velocity, the prediction of landslide triggering was lagging compared to the inverse velocity method. The coupling of slope stresses, deformation and pore water transportation was simulated. The results showed that the inflection point of the time-dependent deformation curve was correlated with the increase in precipitation intensity, and the cumulative precipitation was negatively exponentially correlated with the safety factor. The cumulative deformation obtained by numerical simulation was 2 250 mm, the velocity of deformation was 10-35 mm/d, and the inverse velocity was 0.03-0.12 d/mm, which were close to the actual monitoring data. However, there was still a deviation between the prediction of the inflection point of slope deformation and the actual situation.

Alzheimer’s disease (AD), one of the leading diseases of the nervous system, is accompanied by symptoms such as loss of memory, thinking and language skills. Both mild cognitive impairment (MCI) and very mild cognitive impairment (VMCI) are the transitional pathological stages between normal aging and AD. While the changes in whole-brain structural and functional information have been extensively investigated in AD, The impaired structure–function coupling remains unknown. The current study employed the OASIS-3 dataset, which includes 53 MCI, 90 VMCI, and 100 Age-, gender-, and education-matched normal controls (NC). Several structural and functional parameters, such as the amplitude of low-frequency fluctuations (ALFF), voxel-based morphometry (VBM), and The ALFF/VBM ratio, were used To estimate The whole-brain neuroimaging changes In MCI, VMCI, and NC. As disease symptoms became more severe, these regions, distributed in the frontal-inf-orb, putamen, and paracentral lobule in the white matter (WM), exhibited progressively increasing ALFF (ALFFNC

Rain-induced loess landslides are especially prevalent in the Chinese Loess Plateau (CLP). Some became fatal landslide disasters, leading to numerous casualties and significant socioeconomic losses. Extreme precipitation is the main cause of landslide occurrence. Therefore, in this study we discuss the correlation between seven extreme precipitation indices, single continuous precipitation events and fatal landslides in the CLP using Pearson correlation analysis. We also predict future precipitation under climate changes using five optimal CMIP6 models. During the period 2004–2016, fatal landslides in the CLP increased at a rate of 0.6 per year, with frequent landslide events occurring especially in the central and southwestern parts of the CLP. We find that SDII (simple daily intensity precipitation index) and R×5day (max 5-day precipitation amount) show spatial distribution that are consistent with fatal landslides. Extreme precipitation events were frequent after year 2000; and several extreme precipitation indices show an increasing trend with a higher magnitude since 2000 than before 2000. In particular, in 2013 when the number of fatal landslides was as high as 17, SDII, R95pTOT (extremely wet days), R25mm (very heavy precipitation days), and R×5day all showed abrupt increases. Single continuous precipitation events have profound effects on fatal landslides. We show that single continuous precipitation events with cumulative precipitation of 185–235 mm and duration of 6 days or longer have the highest correlation with fatal landslides. As the increasing occurrence of extreme rainfall events by the global warming, the CLP may face more fatal landslides in the future, especially in the high emission scenario of greenhouse gases (GHGs).

UiO-66-NH2, an important metal–organic framework, is usually synthesized by solvothermal method and the particle size is generally larger than 200 nm, which limits its catalytic applications in chemical reactions. It is very meaningful to produce UiO-66-NH2 nanoparticles with ultra-small size, but remains challenging. Herein, we synthesized UiO-66-NH2 nanoparticles in size of 8–15 nm that are immobilized on g-C3N4 nanosheets. Compared with the UiO-66-NH2 synthesized by the traditional solvothermal method (> 200 nm), the ultra-small UiO-66-NH2 nanoparticles immobilized on g-C3N4 have more unsaturated coordination positions and increased Lewis acidity. Owing to these combined advantages, the ultra-small UiO-66-NH2 nanoparticles exhibit greatly improved catalytic activity for Meerwein–Ponndorf–Verley reaction than larger UiO-66-NH2 particles.

Double-row tapered roller bearings have been widely used in various equipment recently due to their compact structure and ability to withstand large loads. The dynamic stiffness is composed of contact stiffness, oil film stiffness and support stiffness, and the contact stiffness has the most significant influence on the dynamic performance of the bearing. There are few studies on the contact stiffness of double-row tapered roller bearings. Firstly, the contact mechanics calculation model of double-row tapered roller bearing under composite loads has been established. On this basis, the influence of load distribution of double-row tapered roller bearing is analyzed, and the calculation model of contact stiffness of double-row tapered roller bearing is obtained according to the relationship between overall stiffness and local stiffness of bearing. Based on the established stiffness model, the influence of different working conditions on the contact stiffness of the bearing is simulated and analyzed, and the effects of radial load, axial load, bending moment load, speed, preload, and deflection angle on the contact stiffness of double row tapered roller bearings have been revealed. Finally, by comparing the results with Adams simulation results, the error is within 8%, which verifies the validity and accuracy of the proposed model and method. The research content of this paper provides theoretical support for the design of double-row tapered roller bearings and the identification of bearing performance parameters under complex loads.

Abstract Growth hormone deficiency (GHD) is a common developmental disorder in children characterized by low levels of growth hormone secretion, short stature, and multiple cognitive and behavioral problems, including hyperactivity, anxiety, and depression. However, the pathophysiology of this disorder remains unclear. In order to investigate abnormalities of brain functioning in children with GHD, we preformed functional magnetic resonance imaging and regional homogeneity (ReHo) analysis in 26 children with GHD and 15 age- and sex-matched healthy controls (HCs) in a resting state. Compared with HCs, children with GHD exhibited increased ReHo in the left putamen and decreased ReHo in the right precentral gyrus, reflecting a dysfunction of inhibitory control. Decreased ReHo was also identified in the orbital parts of the bilateral superior frontal gyrus and the medial part of the left superior frontal gyrus, a finding that correlated with the inappropriate anxiety and depression that are observed in this patient population. Our results provide imaging evidence of potential pathophysiologic mechanisms for the cognitive and behavioral abnormalities of children with GHD.

Editorial paper

With the accelerating aging of the population and the worsening psychological conditions of older people, the traditional mode of family support for the elderly in China does not always meet the physical and psychological needs of the elderly, and more social support modes for the elderly are needed. Based on 3,513 valid questionnaires on the long-term care and protection needs of Chinese residents, this paper uses a logit regression model to analyze the factors influencing the willingness of the elderly to choose nursing care. The results show that intergenerational family support for the elderly is a significant psychological driver on the willingness of the elderly to choose nursing care. Compared with the elderly living with family, empty nesters or older people living alone are more inclined to select nursing care when they have difficulties taking care of themselves. The physical health of the elderly affects their willingness to choose nursing care, and elderly individuals with more hospitalizations are less likely to select nursing care. In addition, elderly females who are relatively young, have a high level of education, have a high income, have a nursing home near the residence, and are already covered by medical insurance are more willing to choose nursing care. The results of this study are of great importance for improving the medical services and aging care services for the elderly and providing theoretical support for alleviating the psychological and social pressure brought by population aging.

Producing two-dimensional metal-organic frameworks (MOFs) with highly exposed active surfaces is important for catalysis. Here, authors prepare MOF nanosheets by using CO2 as a capping agent to control the oriented growth of MOFs.

While renewable CO2 conversion provides a means to remove and recycle waste emissions, there are few earth-abundant materials that are both efficient and active. Here, authors prepare N-doped carbon with atomic manganese as high-performance CO2 reduction electrocatalyst.

Metastases are the most prevalent tumors in the brain and are commonly associated with high morbidity and mortality. Previous studies have suggested that brain tumors can induce a loss of functional connectivity and alter the brain network architecture. Little is known about the effect of brain metastases on whole-brain functional and structural connectivity networks. In this study, 14 patients with brain metastases and 16 healthy controls underwent resting state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI). We constructed functional connectivity network using rs-fMRI signal correlations and structural connectivity network using DTI tractography. Graph theoretical analysis was employed to calculate network properties. We further evaluated the performance of brain networks after metastases resection by a simulated method. Compared to healthy controls, patients with brain metastases showed an altered "small-world" architecture in both functional and structural connectivity networks, shifting to a more randomness organization. Besides, the coupling strength of functional-structural connectivity was decreased in patients. After removing nodes infiltrated by metastases, aggravated disruptions were found in both functional and structural connectivity networks, and the alterations of network properties correlated with the removed hubs number. Our findings suggest that brain metastases interfere with the optimal network organization and relationship of functional and structural connectivity networks, and tumor resection involving hubs could cause a worse performance of brain networks. This study provides neuroimaging guidance for neurosurgical planning and postoperative assessment of brain metastases from the aspect of brain networks.

The finite element model of a dual-rotor system was established by Timoshenko beam element. The dual-rotor system is a coaxial rotor whose supporting structure is similar to that of an aero-engine rotor system. The inner rotor is supported by three bearings, which makes it a redundantly supported rotor. The outer rotor connects the inner rotor by an intershaft bearing. The spectrum characteristics of the dual-rotor system under unbalanced excitation and misalignment excitation were analysed in order to study the influence of coupling misalignment of the inner rotor on the spectral characteristics of the rotor system. The results indicate that the vibration caused by the misaligned coupling of the inner rotor will be transmitted to the outer rotor through the intershaft bearing. Multiple harmonic frequency components, mainly 1x and 2x, will be excited by the coupling misalignment. The amplitudes of all harmonic frequencies increase with the misalignment in both the inner and outer rotors. The vibration level of the outer rotor affected by the misalignment is lower than that of the inner rotor because it is far from the misaligned coupling. Harmonic resonance occurs when any harmonic frequencies of the misalignment response coincide with a natural frequency of the system. In order to verify the theoretical model, experiments are performed on a test rig. Both the experimental and simulation results are in good accordance with each other.

Bearing is an important mechanical component that easily fails in a bad working environment. Support vector machines can be used to diagnose bearing faults; however, the recognition ability of the model is greatly affected by the kernel function and its parameters. Unfortunately, optimal parameters are difficult to select. To address these limitations, an escape mechanism and adaptive convergence conditions were introduced to the ALO algorithm. As a result, the EALO method was proposed and has been applied to the more accurate selection of SVM model parameters. To assess the model, the vibration acceleration signals of normal, inner ring fault, outer ring fault, and ball fault bearings were collected at different rotation speeds (1500 r/min, 1800 r/min, 2100 r/min, and 2400 r/min). The vibration signals were decomposed using the variational mode decomposition (VMD) method. The features were extracted through the kernel function to fuse the energy value of each VMD component. In these experiments, the two most important parameters for the support vector machine—the Gaussian kernel parameter σ and the penalty factor C—were optimized using the EALO algorithm, ALO algorithm, genetic algorithm (GA), and particle swarm optimization (PSO) algorithm. The performance of these four methods to optimize the two parameters was then compared and analyzed, with the EALO method having the best performance. The recognition rates for bearing faults under different tested rotation speeds were improved when the SVM model parameters optimized by the EALO were used.

Misalignment fault is the main factor that affects the normal running of dual-rotor system. Quantitative identification the misalignment fault is an important way to ensure the safe and stable service of the dual-rotor system, while the identification accuracy of traditional methods is low. Aiming at the above problems, this paper proposed a dual-rotor misalignment fault quantitative identification method based on DBN and D-S evidence theory improved by mutual information measure (MIMD-S). Seven groups experiments were conducted and several vibration signals were collected. By comparing it with the traditional methods D-S, and Pignistic improved D-S (PD-S) evidence theory, the results show that the method proposed in this paper improves the accuracy of the misalignment fault quantitative identification of the dual-rotor, the identification error rate was only 0.36%.

A series of creep age forming experiments were carried out on 7075 aluminum alloy with different prebending radii at 443 K for 10 h. The hardness, tensile properties and high cycle fatigue performance of the alloy after creep age forming were obtained. In addition, the microstructure and fatigue fracture of the alloy were observed by transmission electron microscopy (TEM) and scanning electron microscope (SEM). The results show that with the increase of the prebending radius, the hardness, strength and elongation of the alloy increased; meanwhile, the conditional fatigue limit increased, the size of precipitated phase decreased and the quantity increased, while the width of precipitate free zone decreased.

Polyacrylamide (PAM) is a water-soluble polymer with the ability to enhance a soil’s stability. PAM is currently being used to prevent irrigation-induced erosion and enhance the infiltration in farmland soil. To improve the compaction properties of the saline-soil-based filling material that is used in highway subgrade and the cracking resistance capacity of a saline soil’s crust, the consistency limits, compactability, microstructure, and cracking morphology of untreated and PAM-treated saline soil were investigated. The saline soils were sampled from the soil crust and a depth of 2.0–3.0 m in Gansu Province, China. Two PAM concentrations (0.1% and 0.5% in mass ratio) were selected. The liquid limits and plastic limits of the saline soil samples from the surface (0–0.05 m) and a depth of 2.0–3.0 m noticeably increased as PAM concentration increased. The maximum dry densities decreased as PAM concentration and plasticity increased, and the optimum water contents of the two saline soil types did not significantly change. These results suggest that a higher shearing resistance between particles partially prevented compression from occurring during compaction. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) test results showed that the PAM agent dispersed the bulky pellets, and the soil’s structure was formed by flaky and acicular platelets that filled the micropores. A quantitative analysis of crack patterns showed that the cross-points of the crack network and the crack length decreased as the PAM concentration increased. These results indicate that an increase in PAM reduces the shrinkage strain and the flaws or pores within saline soils. Therefore, PAM’s stabilizing effect on saline soil under a wetting–drying cycle was proven.

Improving the performance of loess is of significant importance for lowering its collapsibility and water sensitivity to construction requirements and for geohazard mitigation. The present paper studies the changes in mechanical, structural, and mineralogical properties of nano-SiO2-treated loess with different contents and curing days. The mechanical behavior was examined by unconfined compressive strength (UCS) of untreated and treated loess. To better understand the mechanisms of stabilization, particle size distributions, scanning electron microscope (SEM) images, and X-ray diffraction (XRD) analyses were carried out. The results show that the UCS increase with increasing contents and curing days due to nano-SiO2 addition produced coarser particles, denser packing, and smaller pores in treated loess. The changes in the properties can be attributed to the formation of aggregation and agglomeration, with greater particle sizes and more interparticle contact. In addition, the results from mineralogical component analysis further confirm that physical structure modification controls the changes in mechanical and fabric properties, rather than chemical component alteration. Even small nano-SiO2 additions can also provide great improvement when curing days are enough for the treated loess. These findings reveal that nano-SiO2 has the potential to serve as a cost-effective stabilized additive that treats the universal loess.