Exploring impacts of COVID-19 on spatial and temporal patterns of visitors to Canadian Rocky Mountain National Parks from social media big data

COVID-19 posed challenges for global tourism management.Changes in visitor temporal and spatial patterns and their associated determinants pre-and peri-pandemic in Canadian Rocky Mountain National Parks are analyzed.Data was collected through social media programming and analyzed using spatiotemporal analysis and a geographically weighted regression(GWR)model.Results highlight that COVID-19 significantly changed park visitation patterns.Visitors tended to explore more remote areas peri-pandemic.The GWR model also indicated distance to nearby trails was a significant influence on visitor density.Our results indicate that the pandemic influenced tourism temporal and spatial imbalance.This research presents a novel approach using combined social media big data which can be extended to the field of tourism management,and has important implications to manage visitor patterns and to allocate resources efficiently to satisfy multiple objectives of park management.

Preparation of Tartary Buckwheat Seed Coating Agent and Its Effect on Germination

To mitigate the wastage of seed resources and reduce the usage of pesticides and fertilizers, seed coating agentshave gained popularity. This study employs single-factor and multi-index orthogonal experimental design methodsto investigate the seed coating formula and physical properties of Tartary buckwheat. The specific effects ofeach component on Tartary buckwheat seed germination are analyzed. The findings reveal that the seed coatingagent formulated with 1.5% polyvinyl alcohol, 0.15% sodium alginate, 0.2% op-10, 0.1% polyacrylamide, 8% colorant,3% ammonium sulfate, 1% potassium dihydrogen phosphate, and 0.15% carbendazim exhibits the mosteffective coating. It demonstrates optimal physical properties and promotes seed germination efficiently. The suspensionrate of this seed coating agent reaches 91.12%, with a mere 2.13% coating shedding rate and 2.5% coatingseed rot rate. Furthermore, it achieves a germination percentage of 99.17%, which is 20.84% higher than the lowestgroup. The germination potential and index are also significantly higher than the lowest group, with anincrease of 20.84% and 26.56%, respectively. Additionally, the vitality index is 553.08, a 15.75% increase comparedto the lowest group. The application of seed coating agents helps reduce seed resource loss, increase plant numbers,and ultimately enhance agricultural yields. This finding holds practical significance in agriculturalproduction.

Numerical and physical simulation of a twin-roll strip caster

The 1：1 water model of a twin-roll strip caster was set up based on the Froude number and the Reynolds number similarity criteria. A new type metal delivery system was designed for the twin-roll strip caster. The level fluctuation and the fluid flow in the pool of the water model were measured using the level detector and the 3D-LDV （laser Doppler velocimetry） technology. It is shown that a wedged delivery system can produce the desirable level fluctuation and even fluid flow distribution in the pool Numerical simulations for the water model were performed. Comparisons between the numerical and physical simulation results show good agreement near the side dams.

An Overview of Recommendation Techniques and Their Applications in Healthcare

With the increasing amount of information on the internet,recommendation system(RS)has been utilized in a variety of fields as an efficient tool to overcome information overload.In recent years,the application of RS for health has become a growing research topic due to its tremendous advantages in providing appropriate recommendations and helping people make the right decisions relating to their health.This paper aims at presenting a comprehensive review of typical recommendation techniques and their applications in the field of healthcare.More concretely,an overview is provided on three famous recommendation techniques,namely,content-based,collaborative filtering(CF)-based,and hybrid methods.Next,we provide a snapshot of five application scenarios about health RS,which are dietary recommendation,lifestyle recommendation,training recommendation,decision-making for patients and physicians,and disease-related prediction.Finally,some key challenges are given with clear justifications to this new and booming field.

基于级联核酸侵入反应的real-time PCR法检测咽拭子样本中UGT1A1*6基因多态性

伊立替康(irinotecan)不良反应与UGT1A1*6单核苷酸多态性相关,目前应用的单核苷酸多态性检测方法具有耗时长、开盖易污染、操作繁琐等缺点,因此需建立一种操作简便且不易污染的适合临床应用的新方法。本研究利用3种已知基因型的DNA样本建立基于级联核酸侵入反应的real-time PCR法检测UGT1A1*6多态性的最佳反应体系,并对其检测口腔咽拭子样本的灵敏度和准确性进行了考察。结果显示,本文成功建立了基于级联核酸侵入反应的UGT1A1*6基因多态性检测方法,可用于咽拭子样本的分型检测,其灵敏度达到6 ng DNA,分型准确性达到100%。因其取样方便对人体无创,单管闭管检测不易产生交叉污染,具有用于临床检测伊立替康的个体化用药相关UGT1A1*6基因多态性的潜力。

A Noise-Resistant Superpixel Segmentation Algorithm for Hyperspectral Images

The superpixel segmentation has been widely applied in many computer vision and image process applications.In recent years,amount of superpixel segmentation algorithms have been proposed.However,most of the current algorithms are designed for natural images with little noise corrupted.In order to apply the superpixel algorithms to hyperspectral images which are always seriously polluted by noise,we propose a noiseresistant superpixel segmentation(NRSS)algorithm in this paper.In the proposed NRSS,the spectral signatures are first transformed into frequency domain to enhance the noise robustness;then the two widely spectral similarity measures-spectral angle mapper(SAM)and spectral information divergence(SID)are combined to enhance the discriminability of the spectral similarity;finally,the superpixels are generated with the proposed frequency-based spectral similarity.Both qualitative and quantitative experimental results demonstrate the effectiveness of the proposed superpixel segmentation algorithm when dealing with hyperspectral images with various noise levels.Moreover,the proposed NRSS is compared with the most widely used superpixel segmentation algorithm-simple linear iterative clustering(SLIC),where the comparison results prove the superiority of the proposed superpixel segmentation algorithm.

Simulation of fire emergency evacuation in a large-passenger-flow subway station based on the on-site measured data of Shenzhen Metro

Because of its large capacity,high efficiency and energy savings,the subway has gradually become the primary mode of transportation for citizens.A high density of passengers exists within a large-passenger-flow subway station,and the number of casualties and injuries during a fire emergency is substantial.In this paper,Pathfinder software and on-site measured data of Pingzhou station in Shenzhen(China)were utilized to simulate a fire emergency evacuation in a large-passenger-flow subway station.The Required Safe Egress Time(RSET),number of passengers and flow rates of stairs and escalators were analysed for three fire evacuation scenarios:train fire,platform fire and hall fire.The evacuation time of the train fire,which was 1173 s,was the longest,and 3621 occupants needed to evacuate when the train was fully loaded.Occupants could not complete the evacuation within 6 mins in all three fire evacuation scenarios,which does not meet the current standard requirements and codes.By changing the number of passengers and the number of stairs for evacuation,the flow rate capacity and evacuation time were explored,which have reference values for safety management and emergency evacuation plan optimization during peak hours of subway operation.

Graphdiyne anchoring to construct highly dense palladium trimer active sites for the selective hydrogenation of acetylene

Semi-hydrogenation of acetylene is of growing interest and popularity but subjects to a major challenge in selective hydrogenation to ethylene.Here,we report a strategy that uses graphdiyne(GDY)as a carrier to prepare single-cluster catalysts(SCCs),which on average clusters composed of three atoms(denoted as Pd3 trimer)and applied it to the acetylene semihydrogenation in the presence of large amounts of ethylene.Based on experimental results and systematic quantum chemical research and computational screening,we found that there are multiple active Pd structures on GDY and the Pd3 trimer anchored on GDY is a specific and durable cluster with great potential for accurate and efficient heterogeneous catalysis.The synergetic effects between neighboring atoms in Pd trimer guarantee easy desorption of ethylene and the absence of unselective hydride species thereby preventing excessive hydrogenation to generate unwanted byproducts,which is a crucial mechanism for the excellent selectivity of the catalyst.This new method for precise synthesis Pd clusters provides accurate ways for designing selective hydrogenation catalysts at the atomic scale.

Al-Mg-Li三元合金表面张力的估算

运用表面张力计算公式Butler方程,与过剩吉布斯自由能结合,计算了973 K温度下Al-Mg, Al-Li和Mg-Li二元体系的表面张力。结果表明,在铝熔体中分别加入金属镁或锂,合金表面张力随其含量增加而降低;在镁熔体中加入金属锂,合金表面张力随锂含量增加而降低。以此为基础,利用Chou模型计算得Al-Mg-Li三元合金的表面张力为0.326~0.851 N/m,随铝或镁含量增加表面张力增大,随锂含量增加表面张力减小。

Thermodynamics and kinetics of phase transformation in rare earth–magnesium alloys:A critical review

Magnesium and its alloys are significant superior metallic materials for structural components in automobile and aerospace industries due to their excellent physicomechanical properties.The Mg–rare earth(RE)systems have attracted great interests because RE additions can improve both the deformability and the strength of Mg alloys through solid solution strengthening and precipitation hardening mechanisms.This paper focuses on the interface stability,together with thermodynamics and kinetics of nucleation and growth of the key phases and matrix phases in Mg–RE alloys.In this paper,the theory and recent advances on Mg–RE alloys,especially for the interface stability,thermodynamics and kinetics of nucleation and growth of the key phases and matrix phases,together with their relationships with micro-structures,and macroscopic properties,are reviewed.By combining the thermodynamics/kinetics integrated simulations with various advanced experimental techniques,“reverse”design of Mg–RE alloys starting from the target service performance is put forward as a kind of scientific paradigm with rational design.

Effect of cerium oxide prepared under different hydrothermal time on electrocatalytic performance of Pt-based anode catalysts

In this paper,CeO2 with a pore size of 2-4 nm was synthesized by hydrothermal method.The CeO2 modified graphene-supported Pt catalyst was prepared by the microwave-assisted ethylene glycol reduction chloroplatinic acid method,and the effect of the addition of CeO2 prepared by different hydrothermal reaction time on the catalytic performance of Pt-based catalysts was investigated.The microstructures of CeO2 and catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area and pore size analyzer(BET),scanning electron microscopy(SEM)and electron spectroscopy(EDAX),transmission electron microscopy(TEM),and the catalysts electrochemical performance was tested by electrochemical workstation.The results show that the catalytic performance of the four catalysts with CeO2 is better than that of the catalyst without CeO2.Adding CeO2 with a specific surface area of 120.15 m2/g prepared by hydrothermal reaction time of 39 h to Pt/C synthesis catalyst,its electrocatalytic performance,stability and resistance to poisoning are the best.The electrochemical active surface area is 102.83 m2/g,the peak current density of ethanol oxidation is 757.17 A/g and steady-state current density of 1100 s is 108.17 A/g which shows the lowest activation energy for ethanol oxidation reaction.When the cyclic voltammogram is scanned for 500 cycles,the oxidation peak current density retention rate is 87.74%.

Hyaluronic acid-curcumin conjugate suppresses the fibrotic functions of myofibroblasts from contractive joint by the PTGER2 demethylation

Joint contracture is a fibrotic complication induced by joint immobilization and trauma,which is characterized as excessive myofibroblast proliferation in joint capsule.The treatments of joint contracture are unsatisfied and patients are suffered from joint dysfunction.Our previous study has shown that curcumin can inhibit myofibroblast proliferation in vitro,but the major challenge is the low aqueous solubility and biological activity of curcumin.In this study,hyaluronic acid-curcumin(HA-Cur)conjugate was synthesized to suppress myofibroblasts in joint contracture.Cells were isolated from the joint capsules of joint contracture patients and induced to active myofibroblasts by transforming growth factor-b(TGF-b).The anti-fibrotic function and mechanisms of HA-Cur were investigated by immunohistochemistry,reverse transcription-quantitative polymerase chain reaction(PCR),methylation-specific PCR,western blot,transwell migration assay and proliferation assay.Results showed that 30 lM HA-Cur significantly attenuated the fibrotic functions of myofibroblast in joint contracture in vitro by regulating the methylation of prostaglandin E receptor 2(PTGER2)and inhibiting TGF-b signaling.This may provide a mechanism for the treatment of joint contracture,and provide a molecular target PTGER2 for therapy during the pathogenesis of joint contracture.

Reusable electrochemical non-enzymatic glucose sensors based on Au-inlaid nanocages

Mass detection of glucose,which is required in many applications,remains challenging.The commercial enzyme-based glucose test strips cannot be reused,and current non-enzymatic glucose sensors exhibit a narrow range of detection and slow glucose oxidation kinetics.Herein,controlled etching of Prussian blue analogue(PBA)nanocubes at the vertices is conducted and Au nanoparticles(Au NPs)are subsequently inlaid in the etched cavities by in-situ reduction of HAuCl4.The unique AuNP-PBA nanocomplexes exhibit low electrochemical potential for glucose oxidation,high electrocatalytic activity,and rapid redox electron transfer rate.Covalent immobilization of the Au-inlaid nanomaterials on a fine Au wire leads to a non-enzymatic glucose sensor with a particularly wide linear detection range(10μM to 16 mM),excellent anti-interference,and fast response.More importantly,the sensor is reusable,and its sensitivity is well maintained even after 150 times of detection.This new-concept material promises to enable high-throughput glucose detection at a low cost,which is essential in diabetic management and other healthcare applications.