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In this paper, an electrodynamic levitation gravity compensation system based on a new type of annular Halbach array permanent magnet is proposed. The magnetic levitation force model is established using the equivalent expansion method, and the reliability of the model is verified by comparing the results of numerical calculation and simulation analysis. Through magnetic field simulation experiments, the effects of rotating speed and air gap on magnetic levitation force and eddy current loss are analyzed. The control model of the electric magnetic levitation system considering the vertical speed is investigated, and the hybrid control method of force and position is used to realize the stable magnetic levitation control. Finally, an experimental platform is built to verify the feasibility of the electric magnetic levitation system. The results show that the magnetic levitation force can be improved and the eddy current loss can be reduced by setting the rotating speed and air gap reasonably.

A prerequisite for using isotopic techniques to study the regional water cycle of a mountainous area is to examine the stable isotopic composition of precipitation. These findings are of great significance for an in-depth understanding of water cycle processes. In this study, each precipitation event was sampled and used to investigate the characteristics of stable hydrogen and oxygen isotopes in precipitation over the Jiaolai Plain and its surrounding areas. NCEP/NCAR data was used for the wind speed and direction, relative humidity, and precipitable amount in the study area during the sampling period. The water vapor sources of the precipitation over the plain were revealed through a comparative analysis of seasonal variations in precipitation isotopes between Global Network of Isotopes in Precipitation stations located along different vapor transport paths. The results showed that the local meteoric water line was δ2H = 6.38 δ18O + 0.72, with a gradient of less than 8. This indicates that the precipitation process was affected by non-equilibrium evaporation occurring when the drops fell below the cloud base. Temperature and amount effects were observed in the δ18O of the precipitation, although the altitude effect was not significant. The water vapor source of the precipitation was predominantly controlled by the East Asian Monsoon from June to September, with the primary source being evaporation from the adjacent Pacific Ocean. The plain was controlled by the Westerlies from October through May, with the predominant vapor source being local evaporation. Water vapor from the polar region had a minimal impact. These findings can serve as the basis for studying surface water–groundwater–seawater transformations.

Surface passivation technology provides noble-metal materials with limited chemical stability, especially under highly acidic condition. To design effective strategy to enhance stability of noble-metal particles, an understanding of their surface anticorrosion mechanism at the atomic level is desirable by using two-dimensional (2D) noble-metal coordination polymer (CP) as an ideal model for their interfacial region. With the protection of 2-thiobenzimidazole (TBI), we isolated two Ag-based 2D CPs, {Ag

Electrostatically assembled ultrathin rhodium nanosheet–gold nanowire nanocomposites (Rh–Au CNSs) were used as an advanced electrocatalyst for the methanol oxidation reaction, which revealed a mass activity of 355 mA mgRh−1 at 0.607 V potential.

BackgroundThe “postural instability/gait difficulty” (PIGD) and “tremor-dominant” (TD) motor subtypes of Parkinson’s disease (PD) differ in their clinical manifestations. The neurological basis of these differences is unclear.MethodsWe performed voxel-based morphometric analysis and measured amplitudes of low-frequency fluctuation (ALFF) on 87 PIGD patients and 51 TD patients. We complemented this neuroanatomical comparison with seed-to-voxel analysis to explore differences in functional connectivity.ResultsThe PIGD group showed significantly smaller gray matter volume in the medial frontal gyrus (mainly on the right side) than the TD group. Across all patients, gray matter volume in the medial frontal gyrus correlated negatively with severity of PIGD symptoms after controlling for age (r = −0.250, p = 0.003), but this correlation was not observed in separate analyses of only PIGD or TD patients. The PIGD group showed greater functional connectivity of the right superior frontal gyrus with the left lingual gyrus, right lateral occipital cortex, and right lingual gyrus. ALFF did not differ significantly between the two groups.ConclusionPostural instability/gait difficulty may be associated with smaller gray matter volume in medial frontal gyrus than TD, as well as with greater functional connectivity between the right superior frontal gyrus and occipital cortex. These results may help explain the clinical differences between the two motor subtypes of PD.

As one of the most representative polyoxometalate (POM) structures, Keggin clusters have attracted considerable attention. Nevertheless, the noble-metal-templated Keggin structure has not been reported to date. In this work, for the first time, a Ag atom was successfully incorporated to template the formation of a γ-Keggin alkytin-oxo cluster. Moreover, the central Ag atom has brought a significant heavy atom effect, showing the important influence on the electronic structure and optical properties. Theoretical calculations demonstrate that the Ag atom affects the frontier molecular orbitals and excited states of the AgSn

Stable isotopes and chloride ion of precipitation are ideal environmental tracers to explain and reveal the formation and evolution mechanisms of water bodies. It is crucial to investigate the stable isotopes and chloride in precipitation events in the northeastern part of the Tibetan Plateau (NETP) due to the limitation of available data. This study sampled each event of precipitation during the period from July 2018 to June 2019 and the monthly dustfall in the NETP to investigate the temporal changes of stable isotopes and chloride in precipitation, and to reveal the moisture source of precipitation over the NETP using a back trajectory model. Results showed that the δ2H values of precipitation ranged from −183.51‰ to 17.75‰, and the δ18O values ranged from −25.18‰ to 0.48‰. The slope of the Local Meteoric Water Line was slightly lower than 8 due to the effect of below-cloud secondary evaporation on the precipitation process. Most d-excess values were higher than 10‰ because moisture recycled from the continent and Qinghai Lake surface mixed with precipitation. The chloride in precipitation accounted for 86.5% of the annual total deposition mass of chloride (1329.64 mg/m2), indicating that precipitation was the main source of chloride in the NETP. The temperature and amount effects of stable isotope in the precipitation were obvious in the NETP. The precipitation was predominantly derived from the Westerly Circulation from September through May and the East Asian Monsoon from June to August, with precipitation amounts of 246.5 mm and 178.0 mm, respectively, indicating that the precipitation over the NETP brought by the Westerly Circulation was more than that brought by the East Asian Monsoon. The air mass over the NETP transited in late May and early September, and a slight change in transition period would mainly be related to the intensity of the East Asian Monsoon, which is strongly influenced by El Nino-Southern Oscillation. These results provide not only baseline data for hydrological and climatological studies of the NETP but also valuable insights into the hydrological process in the inland arid area of Asia.

Entrepreneurial passion is seen as a valuable predictor of entrepreneurs' behavior and performance. We explored what makes entrepreneurs passionate by adopting a qualitative research method from a social support perspective. To test our hypotheses we conducted a survey with 287 young entrepreneurs in China. Using structural equation modeling we studied the impact of three types of support from the family on entrepreneurial passion. The results show that financial support and social capital support had a stronger influence on entrepreneurial passion than did emotional support. Further, psychological capital played a partial mediating role in the relationship between family support and entrepreneurial passion. This study enhances the integrity of previous research conclusions on entrepreneurial passion and, in particular, provides further insight into the development of nascent entrepreneurs and their new businesses.

The paper is devoted to the homogenization of elliptic systems in divergence form. We obtain uniform interior as well as boundary Lipschitz estimates in a bounded C1, γ domain when the coefficients are Dini continuous, inhomogeneous terms are divergence of Dini continuous functions and the boundary functions have Dini continuous derivatives. The results extend Avellaneda and Lin’s work [Comm. Pure Appl. Math., 40: 803–847 (1987)], where H¨older continuity is the main assumption on smoothness of the data.

The construction of circularly polarized luminescence (CPL) materials with high porosity and high rigidity is still challenging. Herein, we propose a chiral reticular chemistry strategy to prepare the homochiral porous metal-organic frameworks (MOFs) as CPL-active materials. Two pairs of enantiomeric MOFs are synthesized through the self-assembly of chiral D/L-cam (DL-camphorates) and achiral fluorescent ligand TPB (1,2,4,5-tetra(pyridin-4-yl)benzene). The

ObjectiveMatrix metalloproteinases (MMPs) are essential for tissue formation, neuronal network remodeling, and blood–brain barrier integrity. MMPs have been widely studied in acute brain diseases. However, the relationship with Parkinson’s disease (PD) remains unclear. The purpose of this study was to evaluate the serum MMP3 and MMP9 levels of PD patients and analyze their correlation with non-motor symptoms.MethodsIn this cross-sectional study, we recruited 73 patients with idiopathic PD and 64 healthy volunteers. Serum MMP3 and MMP9 levels were measured by enzyme-linked immunosorbent assay (ELISA). Patients with PD were assessed for non-motor symptoms using the Non-motor Symptoms Scale (NMSS) and Parkinson’s disease sleep scale (PDSS) and Mini Mental State Examination (MMSE).ResultsSerum MMP3 levels were significantly decreased in PD patients, predominantly those with early-stage PD, compared with controls [12.56 (9.30, 17.44) vs. 15.37 (11.33, 24.41) ng/ml;P= 0.004], and the serum MMP9 levels of PD patients were significantly higher than those of healthy controls [522 (419, 729) vs. 329 (229, 473) ng/ml;P< 0.001]. MMP3 levels were positively correlated with the NMSS total score (r= 0.271,P= 0.020) and the single-item scores for item six, assessing the gastrointestinal tract (r= 0.333,P= 0.004), and there was an inverse correlation between serum MMP3 levels and PDSS score (r= –0.246,P= 0.036); meanwhile, MMP9 levels were positively correlated with the NMSS total score (r= 0.234,P= 0.047), and higher serum MMP9 levels were detected in the cognitive dysfunction subgroup than in the cognitively intact subgroup [658 (504, 877) vs. 502 (397, 608) ng/ml,P= 0.008].ConclusionThe serum MMP3 level of PD patients (especially early-stage patients) was significantly lower than that of the healthy control group, and the MMP9 level was significantly higher than that of the healthy control group. MMP3 and MMP9 levels correlate with sleep disturbance and cognitive function in PD patients, respectively.

Highlights Comprehensive summary of crystalline structures and morphologies of carbon nitride-based materials (CNBMs).Density functional theory computation for the design of functional CNBMs for rechargeable battery applications.The experimental synthesis strategies of CNBMs for rechargeable battery application., Carbon nitrides (including CN, C2N, C3N, C3N4, C4N, and C5N) are a unique family of nitrogen-rich carbon materials with multiple beneficial properties in crystalline structures, morphologies, and electronic configurations. In this review, we provide a comprehensive review on these materials properties, theoretical advantages, the synthesis and modification strategies of different carbon nitride-based materials (CNBMs) and their application in existing and emerging rechargeable battery systems, such as lithium-ion batteries, sodium and potassium-ion batteries, lithium sulfur batteries, lithium oxygen batteries, lithium metal batteries, zinc-ion batteries, and solid-state batteries. The central theme of this review is to apply the theoretical and computational design to guide the experimental synthesis of CNBMs for energy storage, i.e., facilitate the application of first-principle studies and density functional theory for electrode material design, synthesis, and characterization of different CNBMs for the aforementioned rechargeable batteries. At last, we conclude with the challenges, and prospects of CNBMs, and propose future perspectives and strategies for further advancement of CNBMs for rechargeable batteries.

The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming (ISF) in industrial field. As a novel approach, the interpolator method is a promising strategy to enhance the surface quality in ISF. However, the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood. In this paper, the influences of process variables (i.e. tool diameter, step size and thickness of interpolators) on the forming process (e.g. surface roughness, forming force and geometric error) are investigated through a systematic experimental approach of central composite design (CCD) in two-point incremental sheet forming (TPIF). It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path. Nevertheless, the combined influence between thickness of interpolators and process parameters (tool diameter and step size) is limited. Meanwhile, the placement of interpolator has little influence on the effective forming force of blank. In addition, the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter. Finally, the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of the contact pressure due to the increase of contact area with the unchanged contact force. Meanwhile, the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.

Objective To investigate the effect and medical imaging of modified hemispherectomy on patients with infantile hemiparesis and medically refractory epilepsy. Patients and methods Forty-three patients with infantile hemiparesis and refractory epilepsy who underwent hemispherectomy were enrolled. The treatment effect and medical imaging were analyzed. Results Anatomical hemispherectomy was successfully performed in all patients (100%). In all patients, the muscular tension decreased and the contracted limbs relaxed. In the pathological examination of the resected brain tissue, secondary cicatricial gyri with concomitant cortical dysplasia was present in 36 cases and polycerebellar gyrus malformation and porencephalia in the other 7 cases. Followed up for 7–15 years (mean 11.3), all patients were alive without a long-term sequela. Epilepsy was satisfactorily controlled, with complete seizure relief in 39 cases (91%) classified as Engel I and basic control in the other 4 (9%) defined as Engel II. The posthemispherectomy medical imaging demonstrated that the intracranial space on the operative side shrank, and the healthy cerebral hemisphere shifted markedly toward the hemispherectomy side, with expanded lateral ventricle on the healthy side and thickened skull and enlarged frontal sinus on the operative side. After 4–5 years, the intracranial space on the operative side disappeared in 75% of the patients, demonstrating enlarged cerebral peduncle on the healthy side. Conclusion Further modified hemispherectomy in patients with infantile hemiparesis and medically refractory epilepsy demonstrated markedly ameliorated effects on epilepsy control and the prevention of superficial cerebral hemosiderosis in the long-term follow-up.

Tungsten ditelluride (WTe2) is provoking immense interest because of its unique electronic properties, but studies about its semiconducting hexagonal (2H) phase are quite rare. Herein, we report the synthesis of semiconducting 2H WTe2 nanosheets with large positive magnetoresistance, for the first time, by a simple lithium-intercalation-assisted exfoliation strategy. Systematic characterizations including high-resolution transmission electron microscopy, X-ray diffraction, and Raman and X-ray photoelectron spectroscopies provide clear evidence to distinguish the structure of 2H WTe2 nanosheets from the orthorhombic (Td) phase bulk counterpart. The corresponding electronic phase transition from metal to semiconductor is also confirmed by density of states calculation, optical absorption, and electrical transport property measurements. Besides, the 2H WTe2 nanosheets exhibit large positive magnetoresistance with values of up to 29.5% (10 K) and 16.2% (300 K) at 9 T. Overall, these findings open up a promising avenue into the exploration of WTe2-based materials in the semiconductor field.

Ultrasound volume projection imaging (VPI) has been recently suggested. This novel imaging method allows a non-radiation assessment of spine deformity with free-hand 3-D ultrasound imaging. This paper presents a fully automatic method to evaluate the spine curve in VPI images corresponding to different projection depth of the volumetric ultrasound, thus making it possible to analyze 3-D spine deformity. The new automatic method is based on prior knowledge about the geometric arrangement of the spinous processes. The frequency bandwidth of log-Gabor filters is adaptively adjusted to calculate the oriented phase congruency, facilitating the segmentation of the spinous column profile. And the spine curvature angle is finally calculated according to the inflection points of the curve over the segmented spinous column profile. The performance of the automatic method is evaluated on spine VPI images among patients with different scoliotic angles. The curvature angles obtained using the proposed method have a high linear correlation with those by the manual method (r = 0.90, p0.001) and X-ray Cobb's method (r = 0.87, p0.001). The feasibility of 3-D spine deformity assessment is also demonstrated using VPI images corresponding to various projection depth. The results suggest that this method can substantially improve the recognition of the spinous column profile, especially facilitating the applications of 3-D spine deformity assessment.

Marciniack–Kuczinski (M–K) model is widely used to predict material’s forming limit curve (FLC). The prediction of FLC traditionally neglected through-thickness normal stress. However, it cannot be neglected in some forming processes. Much work has been done to study the effect of through-thickness normal stress on FLC with constant through-thickness normal stress or constant ratio of through-thickness normal stress and maximum principal stress. In addition, based on Nakazima test process, the ratio of through-thickness normal stress and maximum principal stress has been derived, which was a function of instantaneous thickness and loading path. Here, initial groove angle in M–K model was not considered. In this paper, uniaxial tension tests and Nakazima tests were performed on 7B04 aluminum alloy. Based on Hill 48 yield criterion and M–K model, the prediction model of FLC was established. The increase of thickness can enhance FLC. Meanwhile, it is necessary to consider through-thickness normal stress and initial groove angle in prediction model. On the left side of FLC, the effect of initial groove angle on FLC is weakened by increasing sheet thickness. On the right side of FLC, the effect of initial groove angle on FLC is strengthened by increasing sheet thickness. On the right side of FLC, the relation between limit strain points with different thicknesses is linear under one certain loading path. Thickness has decisive effect on through-thickness normal stress level and the changing trendy of through-thickness normal stress during calculation is different under different stress condition. Keywords: Forming limit, Initial groove angle, M–K model, Non-constant through-thickness normal stress, Thickness

The cyclical tensile deformation behavior of a solution-treated (ST) Ti–33Nb–4Sn alloy with a dual β and α'' phases was investigated in this study. Experimental results indicated that the ST Ti–33Nb–4Sn alloy exhibited different deformation behavior during two different loading-unloading cycles, and that the deformation behavior was closely related to the characteristics of stress-induced martensitic (SIM) transformation, mainly including the extent and the reversibility of SIM transformation. During the first cycle, the extensive and incompletely reversible SIM transformation occurred, resulting in notable “double yielding” during loading and residual permanent strain after unloading. In the second cycle, however, a slight and reverse SIM transformation, together with pure elastic deformation, taken place concurrently, giving rise to a recoverable nonlinear deformation behavior. Our results also imply that by tailing the characteristics of SIM transformation, the Ti-based alloys with a mixture of α'' and β phases might perform recoverable deformation and possess a promising potential for engineering applications. Keywords: Titanium alloys, β-type, Deformation behavior, β and α'' phases

The influence of initial groove angle on strain rate inside and outside groove of Ti6Al4V alloy was investigated. Based on the evolution of strain rate inside and outside groove, the effect of strain rate difference on the evolution of normal stress and effective stress inside and outside groove was also analyzed. The results show that when linear loading path changes from uniaxial tension to equi-biaxial tension, the initial groove angle plays a weaker role in the evolution of strain rate in the M−K model. Due to the constraint of force equilibrium between inside and outside groove, the strain rate difference makes the normal stress inside groove firstly decrease and then increase during calculation, which makes the prediction algorithm of forming limit convergent at elevated temperature. The decrease of normal stress inside groove is mainly caused by high temperature softening effect and the rotation of groove, while the increase of normal stress inside groove is mainly due to strain rate hardening effect.

Microorganisms with high oil-degrading ability are essential for bioremediation of oil-contaminated environments and oil spills. In the present study, a microbial consortium was enriched from a long-term oil-contaminated soil by acclimatization with crude oil, and was cultured with sucrose as a carbon source. Immobilization of the microbial consortium cells was prepared onto sodium alginate (SA) beads. To enhance the mass transfer of the immobilized microspheres, activated carbon, biochar, corn stalk and sawdust were used, respectively, to accelerate the degradation of petroleum hydrocarbons. The immobilized beads and the distribution of microbial cells inside the immobilized beads were examined using scanning electron microscopy (SEM). The degradation efficiency of total petroleum hydrocarbon (TPH) by different immobilized beads in aquatic systems (mineral salt medium, artificial seawater) was evaluated by gravimetric method after 7 d of incubation. Results showed that TPH degradation efficiency of the immobilized beads was higher than that of the microbial culture, and that of the immobilized beads containing adsorbent carriers was higher than the SA immobilized beads. The highest TPH degradation efficiencies of SA-CS immobilized beads in mineral salt and artificial seawater were up to 54.2% and 50.5%, respectively, and the highest TPH degradation efficiency of biostimulation + SA-AC immobilized beads treatment in oil-contaminated soil was up to 63.7% after 10 weeks of incubation. Our results suggest that the immobilized microorganism is a promising approach for a wide range of bioremediation applications in different petroleum-contaminated environments.

High-performance ternary transition-metal chalcogenides (TMDs) are desired in various application fields. However, developing ternary TMDs with unique performance via an efficient and economical me...