探查阶段旅游地居民支持度的影响因素分析与实证研究——以海口市北港村为例

选择处于探查阶段的海口市北港村为案例地,以决策行为理论为分析框架,构建了一个居民视角下由理性层面的旅游发展潜力认知、积极影响感知、消极影响感知和非理性层面的地方感组成的概念模型,使用AMOSS和SPSS软件量化探究上述因素对探查阶段旅游地居民旅游支持度的影响路径。结果表明:1)在旅游发展探查阶段,旅游发展潜力认知、积极影响感知、消极影响感知和地方感对居民支持度产生显著影响,其中旅游发展潜力认知不仅通过直接和中介作用对居民支持度产生影响,还对积极、消极影响感知和地方感产生不同程度作用;2)地方感强的居民对旅游积极影响的感知较易受旅游发展潜力认知调节,而居民对旅游消极影响的感知不易受其他因素调节;3)在居民的主观选择决策中,理性与非理性的因素共同发挥作用。在同构关系下,理性与非理性因素之间各自独立又彼此交融。

Underestimated relationship between westerly wind bursts and ENSO in CMIP6 models

观测表明,热带太平洋的西风爆发(WWBs)在厄尔尼诺南方涛动(ENSO)的发生,发展和多样性中起着关键作用.因此,在耦合模式中真实地再现WWBs对于改进ENSO的模拟和预测有重要意义.在本研究中,作者发现CMIP6的耦合模式的集合平均能很好地再现了热带太平洋WWB发生频率的纬向分布及其年际变动.然而,大多数CMIP6模型极大低估了WWB和ENSO的线性关系.这可能是因为大多数CMIP6模式里海气耦合强度低于观测:海气耦合强度与WWB-ENSO关系的模式间相关系数高达0.91.

Analysis of an Axial-flux Slotted Limited-angle Torque Motor with Quasi-Halbach Array for Torque Performance Improvement

Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosystems.This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range(CTR)and output torque.Firstly,the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed.Secondly,a brief design procedure is presented,the structure selections of open slot and double-stator single-rotor(DSSR)interior rotor with surface mounted quasi-Halbach permanent magnet(PM)array are illustrated,and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM.Then,3-D finite-element method(FEM)is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque,no-load back EMF,and output torque,and the results show that the proposed LATM with quasi-Halbach array has a 10%improvement in output torque and a 25%improvement in CTR.Meanwhile,the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation.Finally,prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.

Polymer composites designed with 3D fibrous CNT“tracks”achieving excellent thermal conductivity and electromagnetic interference shielding efficiency

The rapid improvement in the running speed,transmission efficiency,and power density of miniaturized devices means that multifunctional flexible composites with excellent thermal management capability and high electromagnetic interference(EMI)shielding performance are urgently required.Here,inspired by the fibrous pathways of the human nervous system,a“core–sheath”fibers structured strategy was proposed to prepare thermoplastic polyurethane/polydopamine/carbon nanotube(TPU/PDA/CNT)composites film with thermal management capability and EMI shielding performance.Firstly,TPU@PDA@CNT fibers with CNT shell were prepared by a facile polydopamine-assisted coating on electrospun TPU fibers.Subsequently,TPU/PDA/CNT composites with three-dimensional(3D)fibrous CNT“tracks”are obtained by a hot-pressing process,where CNTs distributed on adjacent fibers are compactly contacted.The fabricated TPU/PDA/CNT composites exhibit a high in-plane thermal conductivity(TC)of 9.6 W/(m·K)at low CNT loading of 7.6 wt.%.In addition,it also presents excellent mechanical properties and excellent EMI shielding effectiveness of 48.3 dB as well as multi-source driven thermal management capabilities.Hence,this study provides a simple yet scalable technique to prepare composites with advanced thermal management and EMI shielding performance to develop new-generation wireless communication technologies and portable intelligent electronic devices.

Assessing comparable bioconcentration potentials for nanoparticles in aquatic organisms via combined utilization of machine learning and toxicokinetic models

The toxicokinetic(TK)model‐derived kinetic bioconcentration factor(BCFk)provides a quantitatively comparable index to estimate the bioaccumulation potential of nanoparticles(NPs)that barely reach thermodynamic equilibrium in aquatic organisms,but experimental data are limited for various NPs.In the present study,a machine learning model was applied to offer reliable in silico predictions for the dynamic body burden of diverse NPs to derive corresponding parameters for the TK model.The developed eXtreme Gradient Boosting‐derived TK(XGB‐TK)model was applied to predict BCFk results for a broad range of metallic or carbonaceous NPs,with an appreciable prediction R2 of 0.96.The BCFk values were predicted based on a random combination of selected variable features,revealing that their bioaccumulation potential showed an overall negative correlation with NP density or organism size.By applying importance analysis and partial dependence plots,NP density and organism size were revealed to be the top essential features that impact the bioaccumulation potential.The conjunctively used XGB‐TK model enabled a prior comparison for diverse NPs and straightforward derivation on the dependency of features,which could also guide the bioaccumulation mechanism exploration and experimental condition formulation.

3D-printed cell-free PCL-MECM scaffold with biomimetic micro-structure and micro-environment to enhance in situ meniscus regeneration

Despite intensive effort was made to regenerate injured meniscus by cell-free strategies through recruiting endogenous stem/progenitor cells,meniscus regeneration remains a great challenge in clinic.In this study,we found decellularized meniscal extracellular matrix(MECM)preserved native meniscal collagen and glycosaminoglycans which could be a good endogenous regeneration guider for stem cells.Moreover,MECM significantly promoted meniscal fibrochondrocytes viability and proliferation,increased the expression of type II collagen and proteoglycans in vitro.Meanwhile,we designed 3D-printed polycaprolactone(PCL)scaffolds which mimic the circumferential and radial collagen orientation in native meniscus.Taken these two advantages together,a micro-structure and micro-environment dually biomimetic cell-free scaffold was manipulated.This cell-free PCL-MECM scaffold displayed superior biocompatibility and yielded favorable biomechanical capacities closely to native meniscus.Strikingly,neo-menisci were regenerated within PCL-MECM scaffolds which were transplanted into knee joints underwent medial meniscectomy in rabbits and sheep models.Histological staining confirmed neo-menisci showed meniscus-like heterogeneous staining.Mankin scores showed PCL-MECM scaffold could protect articular cartilage well,and knee X-ray examination revealed same results.Knee magnetic resonance imaging(MRI)scanning also showed some neo-menisci in PCL-MECM scaffold group.In conclusion,PCL-MECM scaffold appears to optimize meniscus regeneration.This could represent a promising approach worthy of further investigation in preclinical applications.

Strain Hardening Associated with Dislocation,Deformation Twinning,and Dynamic Strain Aging in Fe–20Mn–1.3C–(3Cu) TWIP Steels

The effects of Cu on stacking fault energy,dislocation slip,mechanical twinning,and strain hardening in Fe–20Mn–1.3C twinning-induced plasticity（TWIP） steels were systematically investigated.The stacking fault energy was raised with an average slope of 2 mJ/m2 per 1 wt% Cu.The Fe–20Mn–1.3C–3Cu steel exhibited superior tensile properties,with the ultimate tensile strength reached at 2.27 GPa and elongation up to 96.9% owing to the high strain hardening that occurred.To examine the mechanism of this high strain hardening,dislocation density determination by XRD was calculated.The dislocation density increased with the increasing strain,and the addition of Cu resulted in a decrease in the dislocation density.A comparison of the strain-hardening behavior of Fe–20Mn–1.3C and Fe–20Mn–1.3C–3Cu TWIP steels was made in terms of modified Crussard–Jaoul（C–J） analysis and microstructural observations.Especially at low strains,the contributions of all the relevant deformation mechanisms—slip,twinning,and dynamic strain aging—were quantitatively evaluated.The analysis revealed that the dislocation storage was the leading factor to the increase of the strain hardening,while dynamic strain aging was a minor contributor to strain hardening.Twinning,which interacted with the matrix,acted as an effective barrier to dislocation motion.

COVID-19,the Pandemic of the Century and Its Impact on Cardiovascular Diseases

COVID-19 caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection likely ranks among the deadliest diseases in human history.As with other coronaviruses,SARS-CoV-2 infection damages not only the lungs but also the heart and many other organs that express angiotensin-converting enzyme 2(ACE2),a receptor for SARS-CoV-2.COVID-19 has upended lives worldwide.Dietary behaviors have been altered such that they favor metabolic and cardiovascular complications,while patients have avoided hospital visits because of limited resources and the fear of infection,thereby increasing out-hospital mortality due to delayed diagnosis and treatment.Clinical observations show that sex,age,and race all influence the risk for SARS-CoV-2 infection,as do hypertension,obesity,and pre-existing cardiovascular conditions.Many hospitalized COVID-19 patients suffer cardiac injury,acute coronary syndromes,or cardiac arrhythmia.SARS-CoV-2 infection may lead to cardiomyocyte apoptosis and necrosis,endothelial cell damage and dysfunction,oxidative stress and reactive oxygen species production,vasoconstriction,fibrotic and thrombotic protein expression,vascular permeability and microvascular dysfunction,heart inflammatory cell accumulation and activation,and a cytokine storm.Current data indicate that COVID-19 patients with cardiovascular diseases should not discontinue many existing cardiovascular therapies such as ACE inhibitors,angiotensin receptor blockers,steroids,aspirin,statins,and PCSK9 inhibitors.This review aims to furnish a framework relating to COVID-19 and cardiovascular pathophysiology.