Structure and immunomodulatory activity of Lentinus edodes polysaccharides modified by probiotic fermentation

Plant-based fermentations provide an untapped source for novel biotechnological applications.In this study,a probiotic named Lactobacillus fermentum 21828 was introduced to ferment Lentinus edodes.Polysaccharides were extracted from fermented and non-fermented L.edodes and purified via DEAE-52 and Sephadex G-100.The components designated F-LEP-2a and NF-LEP-2a were analyzed by FT-IR,HPGPC,HPAEC,SEM,GC-MS and NMR.The results revealed that probiotic fermentation increased the molecular weight from 1.16×10^(4) Da to 1.87×10^(4) Da and altered the proportions of glucose,galactose and mannose,in which glucose increased from 45.94%to 48.16%.Methylation analysis and NMR spectra indicated that F-LEP-2a and NF-LEP-2a had similar linkage patterns.Furthermore,their immunomodulatory activities were evaluated with immunosuppressive mice.NF-LEP and F-LEP improved immune organ indices,immunoglobulin(Ig G and Ig M)and cytokines concentrations;restored the antioxidation capacity of liver;and maintained the balance of gut microbiota.F-LEP displayed better moderating effects on the spleen index,immunoglobulin,cytokines and the diversity of gut microbiota than NF-LEP(200,400 mg/kg).Our study provides an efficient and environment-friendly way for the structural modification of polysaccharides,which helps to enhance their biological activity and promote their wide application in food,medicine and other fields.

Tree species richness enhances stand productivity while stand structure can have opposite effects, based on forest inventory data from Germany and the United States of America

Background： in recent studies, mixed forests were found to be more productive than monocultures with everything else remaining the same. Methods： To find out if this productivity is caused by tree species richness, by a more heterogeneous stand structure or both, we analyzed the effects of forest structure and tree species richness on stand productivity, based on inventory data of temperate forests in the United States of America and Germany. Results： Having accounted for effects such as tree size and stand density, we found that： （I） tree species richness increased stand productivity in both countries while the effect of tree size heterogeneity on productivity was negative in Germany but positive in the USA; （11） productivity was highest at sites with an intermediate amount of precipitation; and （111） growth limitations due water scarcity or low temperature may enhance structural heterogeneity. Conclusions： In the context of forest ecosystem goods and services, as well as future sustainable forest resource management, the associated implications would be：

Systematic Hydrological Evaluation of the Noah-MP Land Surface Model over China

We evaluate water budget components-namely,soil moisture,runoff,evapotranspiration,and terrestrial water storage (TWS)-simulated by the Noah land surface model with multi-parameterization options (Noah-MP) in China,a large geographic domain challenging for hydrological modeling due to poor observational data and a lack of one single parameterization that can fit for complex hydrological processes.By comparing the model simulations with multi-source reference data,we show that Noah-MP can generally reproduce the overall spatiotemporal patterns of runoff and evapotranspiration over six major river basins,with the annual correlation coefficients generally greater than 0.8 and the Nash-Sutcliffe model efficiency coefficient exceeding 0.5.Among the six basins evaluated,the best model performance is seen over the Huaihe River basin.The temporal trend of the modeled TWS anomalies agrees well with GRACE (Gravity Recovery and Climate Experiment) observations,capturing major flood and drought events in different basins.Experiments with 12 selected physical parameterization options show that the runoff parameterization has a stronger impact on the simulated soil moisture-runoff-evapotranspiration relationships than the soil moisture factor for stomatal resistance schemes,a result consistent with previous studies.Overall,Noah-MP driven by GLDAS forcing simulates the hydrological variables well,except for the Songliao basin in northeastern China,likely because this is a transitional region with extensive freeze-thaw activity,while representations of human activities may also help improve the model performance.

Nitrogen-doped hierarchical porous carbon derived from metal–organic aerogel for high performance lithium–sulfur batteries

Nitrogen-doped three-dimensional(3 D) porous carbon materials have numerous applications due to their highly porous structures, abundant structural nitrogen heteroatom decoration and low densities. Herein,nitrogen doped hierarchical 3 D porous carbons(NHPC) were prepared via a novel metal–organic aerogel(MOA), using hexamethylenetetramine(HMT), 1,3,5-benzenetricarboxylic acid and copper(II) as starting materials. The morphology, porous structure of the building blocks in the NHPC can be tuned readily using different amount of HMT, which makes elongation of the pristine octahedron of HKUST-1 to give rise to different aspect ratio rod-like structures. The as-prepared NHPC with rod-like carbons exhibit high performance in lithium sulfur battery due to the rational ion transfer pathways, high N-doped doping and hierarchical porous structures. As a result, the initial specific capacity of 1341 m A h/g at rate of 0.5 C(1 C = 1675 m A h/g) and high-rate capability of 354 m A h/g at 5 C was achieved. The decay over 500 cycles is 0.08% per cycle at 1 C, highlighting the long-cycle Li–S batteries.

Modeling the Impacts of Nitrogen Dynamics on Regional Terrestrial Carbon and Water Cycles over China with Noah-MP-CN

As an important part of biogeochemical cycling,the nitrogen cycle modulates terrestrial ecosystem carbon storage,water consumption,and environmental quality.Modeling the complex interactions between nitrogen,carbon and water at a regional scale remains challenging.Using China as a testbed,this study presents the first application of the nitrogenaugmented community Noah land surface model with multi-parameterization options(Noah-MP-CN)at the regional scale.Noah-MP-CN parameterizes the constraints of nitrogen availability on photosynthesis based on the Fixation and Uptake of Nitrogen plant nitrogen model and the Soil and Water Assessment Tool soil nitrogen model.The impacts of nitrogen dynamics on the terrestrial carbon and water cycles are investigated by comparing the simulations with those from the original Noah-MP.The results show that incorporating nitrogen dynamics improves the carbon cycle simulations.NoahMP-CN outperforms Noah-MP in reproducing leaf area index(LAI)and gross primary productivity(GPP)for most of China,especially in the southern warm and humid regions,while the hydrological simulations only exhibit slight improvements in soil moisture and evapotranspiration.The impacts of fertilizer application over cropland on carbon fixation,water consumption and nitrogen leaching are investigated through a trade-off analysis.Compared to halved fertilizer use,the actual quantity of application increases GPP and water consumption by only 1.97%and 0.43%,respectively;however,the nitrogen leaching is increased by 5.35%.This indicates that the current level of fertilizer use is a potential concern for degrading the environment.

Performance of statistical and machine learning-based methods for predicting biogeographical patterns of fungal productivity in forest ecosystems

Background:The prediction of biogeographical patterns from a large number of driving factors with complex interactions,correlations and non-linear dependences require advanced analytical methods and modeling tools.This study compares different statistical and machine learning-based models for predicting fungal productivity biogeographical patterns as a case study for the thorough assessment of the performance of alternative modeling approaches to provide accurate and ecologically-consistent predictions.Methods:We evaluated and compared the performance of two statistical modeling techniques,namely,generalized linear mixed models and geographically weighted regression,and four techniques based on different machine learning algorithms,namely,random forest,extreme gradient boosting,support vector machine and artificial neural network to predict fungal productivity.Model evaluation was conducted using a systematic methodology combining random,spatial and environmental blocking together with the assessment of the ecological consistency of spatially-explicit model predictions according to scientific knowledge.Results:Fungal productivity predictions were sensitive to the modeling approach and the number of predictors used.Moreover,the importance assigned to different predictors varied between machine learning modeling approaches.Decision tree-based models increased prediction accuracy by more than 10%compared to other machine learning approaches,and by more than 20%compared to statistical models,and resulted in higher ecological consistence of the predicted biogeographical patterns of fungal productivity.Conclusions:Decision tree-based models were the best approach for prediction both in sampling-like environments as well as in extrapolation beyond the spatial and climatic range of the modeling data.In this study,we show that proper variable selection is crucial to create robust models for extrapolation in biophysically differentiated areas.This allows for reducing the dimensions of the ecosystem space described by the predictors of the models,resulting in higher similarity between the modeling data and the environmental conditions over the whole study area.When dealing with spatial-temporal data in the analysis of biogeographical patterns,environmental blocking is postulated as a highly informative technique to be used in cross-validation to assess the prediction error over larger scales.

Large-scale forest inventories of the United States and China reveal positive effects of biodiversity on productivity

Background： With the loss of species worldwide due to anthropogenic factors, especially in forested ecosystems, it has become more urgent than ever to understand the biodiversity-ecosystem functioning relationship （BEFR）. BEFR research in forested ecosystems is very limited and thus studies that incorporate greater geographic coverage and structural complexity are needed. Methods： We compiled ground-measured data from approx, one half million forest inventory sample plots across the contiguous United States, Alaska, and northeastern China to map tree species richness, forest stocking, and productivity at a continental scale. Based on these data, we investigated the relationship between forest productivity and tree species diversity, using a multiple regression analysis and a non-parametric approach to account for spatial autocorrelation. Results： In general, forests in the eastern United States consisted of more tree species than any other regions in the country. The highest forest stocking values over the entire study area were concentrated in the western United States and Central Appalachia. Overall, 96.4 % of sample plots （477,281） showed a significant positive effect of species richness on site productivity, and only 3.6 % （17,349） had an insignificant or negative effect. Conclusions： The large number of ground-measured plots, as well as the magnitude of geographic scale, rendered overwhelming evidence in support of a positive BEFR. This empirical evidence provides insights to forest management and biological conservation across different types of forested ecosystems. Forest timber productivity may be impaired by the loss of species in forests, and biological conservation, due to its potential benefits on maintaining species richness and productivity, can have profound impacts on the functioning and services of forested ecosystems.

Thermal shock resistant 3D printed ceramics reinforced with MgAl_(2)O_(4) shell structure

The demand for the swirl nozzle with enhanced temperature resistance and lightweight properties is in-creasing as the thrust-to-weight ratio of aero-engines rises.The Al_(2)O_(3) ceramic swirl nozzle can maintain high strength in a hostile environment of high temperature and severe corrosion,while also meeting the requirements of aircraft to enhance efficiency and decrease weight.However,Al_(2)O_(3) ceramics are limited in their application for aerospace components due to their poor thermal shock resistance(TSR)stemming from their inherent brittleness.This work reported an innovative design and fabrication strategy based on photopolymerization 3D printing technology to realize the three-dimensional shell structure through element interdiffusion and nanoscale stacking of the reinforced phase.With this strategy,a novel type of the new dual-structure Al_(2)O_(3) ceramic composed of MgAl_(2)O_(4) shell structure and matrix could be con-structed in situ.The nano-sized MgAl_(2)O_(4) caused a crack passivation effect after the thermal shock,which could improve the strength and TSR of 3D-printed Al_(2)O_(3) ceramic.In addition,the effects of MgO content and sintering temperature on sintering behavior,flexural strength,porosity,and TSR of Al_(2)O_(3) ceram-ics manufactured by digital light processing(DLP)processing were systematically studied.The optimum overall performance of Al_(2)O_(3) ceramics was obtained at the sintering temperature of 1550℃and the MgO content of 1.0 wt.%,with a maximum flexural strength of 111.929 MPa and a critical temperature difference of 374.24℃for TSR.Based on the above research,an aero-engine swirl nozzle with high ther-mal shock resistance has been successfully prepared by ceramic 3D printing technology,which enhances high-temperature resistance and promotes lightweight design in aero-engine.

Slurry flow characteristics control of 3D printed ceramic core layered structure:Experiment and simulation

Vat photopolymerization 3D printing ceramic technology provides a feasible process for the preparation of complex internal cooling channels for aeroengine single crystal superalloy hollow blades.However,the typical layered structure characteristics of 3D printing ceramic technology led to the anisotropy of ceramic core strength and sintering shrinkage,which greatly affects the performance and accuracy of the complex structure core and requires further research and improvement.Herein,the influence of the thickness of the slurry layer on the flow characteristics of the slurry in the process of the vat photopolymerization 3D printing slurry spreading was systematically studied by the method of simulation and experiment.The simulation results show that the positions of the turbulent zone and maximum velocity zone in the scraper front affect the redistribution of powder particles with different sizes.The layered structure was caused by the redistribution of ceramic particles of different sizes in the slurry layer.By controlling the turbulent flow zone and the maximum velocity zone of the scraper leading edge,the phenomenon of laminar flow can be weakened and the particle redistribution can be improved.With the increase of the thickness of the printing layer,the layered structure appears gradually,and the pores at the interface of the layered structure gradually concentrated into the interfacial pore lines from the uniform distribution,and the crack propagation changes from intergranular micro-crack to interlayer macro-crack.The combination of finite element simulation and experiment,through the slurry flow characteristics to control the layered structure of reductive vat photopolymerization ceramic core 3D printing,the control of crack propagation mode,element distribution and pore evolution of the core was accomplished,which lays a foundation for the performance control of ceramic 3D printing technology.

Manufacturing of ceramic cores:From hot injection to 3D printing

With the improvement of aero-engine performance,the preparation of hollow blades of single-crystal superalloys with complex inner cavity cooling structures is becoming increasingly urgent.The ceramic core is the key intermediate part of the preparation and has attracted wide attention.To meet this challenge,new technologies that can make up for the defects of long periods and high costs of fabricating complex structural cores by traditional hot injection technology are needed.Vat photopolymerization 3D printing ceramic technology has been applied to the core field to realize the rapid preparation of complex structural cores.However,the industrial application of this technology still needs further research and improvement.Herein,ceramic cores were prepared using traditional hot injection and vat photopolymerization 3D printing techniques using fused silica,nano-ZrO_(2),and Al_(2)O_(3) powders as starting materials.The 3D printed ceramic core has a typical layered structure with a small pore size and low porosity.Because of the layered structure,the pore area is larger than that of the hot injection ceramic core,the leaching performance has little effect(0.0277 g/min for 3D printing cores,0.298 g/min for hot injection cores).In the X and Y directions,the sintering shrinkage is low(2.7%),but in the Z direction,the shrinkage is large(4.7%).The fracture occurs when the inner layer crack expands and connects with the interlayer crack,forming a stepped fracture in the 3D-printed cores.The bending strength of the 3D printed core at high temperature(1500℃)is 17.3 MPa.These analyses show that the performance of vat photopolymerization 3D-printed ceramic cores can meet the casting requirements of single crystal superalloy blades,which is a potential technology for the preparation of complex structure ceramic cores.The research mode of 3D printing core technology based on the traditional hot injection process provides an effective new idea for promoting the industrial application of 3D printing core technology.

Ceramic composites toughened by vat photopolymerization 3D printing technology

High strength and high toughness are mutually exclusive in structural materials.In ceramic materials,increasing toughness usually depends on the introduction of a ductile phase that reduces the strength and high-temperature stability of the material.In this work,vat photopolymerization 3D printing technology was used to achieve toughening of ceramic composite material.The friction sliding of the 3D-printed ceramic macrolayer structure results in effective energy dissipation and redistribution of strain in the whole structure,and macroscale toughening of the ceramic material is realized.In addition,the bridging and elongation of the crack in situ amorphous ceramic whiskers were significant microscopic toughening results,coupled with the toughening of the crack tip of nano-ZrO_(2).Multiscale collaborative toughening methods based on 3D-printed ceramics should find wide applications for materials in service at extreme high temperatures.

How Autonomy Support Environment Influences Student Online Game Addiction:The Mediating Roles of Academic Motivation and Academic Perseverance

Background:Online game addiction has become a serious global public health problem among adolescents.However,its influencing factors and mediating mechanisms remain ambiguous.Methods:The present study adopted stratified random sampling to collect 6146 junior high school student samples in China's Mainland.We used regression analysis,and Bootstrap mediation test through SPSS 26.0 and AMOS 24.0 to reveal the tendency of students’online game addiction with different background characteristics and whether autonomy support from parents and teachers can effectively reduce online game addiction.Results:The results showed that parental(β=−0.112,p<0.001)and teacher(β=−0.225,p<0.001)autonomy support were conducive to reducing students’online game addiction.Academic perseverance(β=−0.080,95%CI=[−0.103,−0.058])and academic motivation(β=−0.073,95%CI=[−0.095,−0.052])partially mediated the relationship between autonomy support and online game addiction.Conclusion:This result provides a theoretical basis for educational interventions.It suggests that strengthening autonomy support could enhance students’academic perseverance and motivation and further reduce online game addiction.This study utilized a cross-sectional research design,making it difficult to determine the causal relationship between autonomy support environment and online game addiction.

The development of solid oxide co-electrolysis of H_(2)O and CO_(2)on large-size cells and stacks

In the context of carbon neutrality,conversion of CO_(2)into CO is an effective way for negative carbon emission.Electrochemical reduction is a novel developed pathway,among which,solid oxide co-electrolysis technology is promising for its high efficiency and low electricity demand.Researches concerning the large-size cell and stack of application level are important.This review,targeting at the not yet fully understood reaction mechanism and the most concerning issue of durability,details the reported factors playing important roles in the reaction mechanism and durability of co-electrolysis.It is found that the operating conditions such as inlet mixtures and applied current significantly affect the reaction mechanism of co-electrolysis and the experiments on button cells can not reflect the real reaction mechanism on industrial-size cells.Besides,the durability test of large-size single cells and stacks at high current with high conversion rate and the potential of solid oxide co-electrolysis combing with intermittent renewable energy are also reviewed and demonstrated.Finally,an outlook for future exploration is also offered.

Effect of sintering temperature in argon atmosphere on microstructure and properties of 3D printed alumina ceramic cores

Alumina ceramics with different sintering temperatures in argon atmosphere were obtained using stereolithography-based 3D printing.The effects of sintering temperature on microstructure and physical and mechanical properties were investigated.The results show that the average particle size,shrinkage,bulk density,crystallite size,flexural strength,Vickers hardness,and nanoindentation hardness increased with the increase in sintering temperature,whereas the open porosity decreased with increasing sintering temperature.No change was observed in phase composition,chemical bond,atomic ratio,and surface roughness.For the sintered samples,the shrinkage in Z direction is much greater than that in X or Y direction.The optimum sintering temperature in argon atmosphere is 1350℃with a shrinkage of 3.0%,3.2%,and 5.5%in X,Y,and Z directions,respectively,flexural strength of 26.7 MPa,Vickers hardness of 198.5 HV,nanoindentation hardness of 33.1 GPa,bulk density of 2.5 g/cm^3,and open porosity of 33.8%.The optimum sintering temperature was 70℃higher than that sintering in air atmosphere when achieved the similar properties.

Microstructure and tensile properties of DD32 single crystal Ni-base superalloy repaired by laser metal forming

In this work,the microstructure and tensile properties of DD32 single-crystal(SC)superalloy repaired by laser metal forming(LMF)using pulsed laser have been studied in detail.The microstructures of the deposited samples and the tensile-ruptured samples were characterized by optical microscopy(OM),transmission electron microscope(TEM)and scanning electron microscope(SEM).Due to high cooling rate,the primary dendrite spacing in the deposited area(17.2μm)was apparently smaller than that in the substrate area(307μm),and the carbides in the deposited samples were also smaller compared with that in the substrate area.The formation of(γ+γ’)eutectic in the initial layer of repaired SC was inhibited because of the high cooling rate.As the deposition proceeded,the cooling rate decreased,and the(γ+γ’)eutectic increased gradually.The(γ+γ’)eutectic at heat-affected zone(HAZ)in the molten pool dissolved partly because of the high temperature at HAZ,but there were still residual eutectics.Tensile test results showed that tensile behavior of repaired SC at different temperatures was closely related to the MC carbides,solidification porosity,γ’phase,and(γ+γ’)eutectic.At moderate temperature,the samples tested fractured preferentially at the substrate area due to the fragmentation of the coarse MC carbide in the substrate area.At elevated temperature,the(γ+γ’)eutectic and solidification porosity in the deposited area became the source of cracks,which deteriorated the high-temperature properties and made the samples rupture at the deposited area preferentially.

Improving Land Surface Hydrological Simulations in China Using CLDAS Meteorological Forcing Data

The accuracy of land surface hydrological simulations using an offline land surface model(LSM)depends largely on the quality of the atmospheric forcing data.In this study,Global Land Data Assimilation System(GLDAS)forcing data and the newly developed China Meteorological Administration Land Data Assimilation System(CLDAS)forcing data are used to drive the Noah LSM with multiple parameterizations(Noah-MP)and to explore how the newly developed CLDAS forcing data improve land surface hydrological simulations over China's Mainland.The monthly soil moisture(SM)and evapotranspiration(ET)simulations are then compared and evaluated against observations.The results show that the Noah-MP driven by the CLDAS forcing data(referred to as CLDASNoah-MP)significantly improves the simulations in most cases over China's Mainland and its eight river basins.CLDASNoahMP increases the correlation coefficient(R)values from 0.451 to 0.534 for the SM simulations at a depth range of 0–10 cm in China's Mainland,especially in the eastern monsoon area such as the Huang–Huai–Hai Plain,the southern Yangtze River basin,and the Zhujiang River basin.Moreover,the root-mean-square error is reduced from 0.078 to0.068 m3 m-3 for the SM simulations,and from 12.9 to 11.4 mm month-1 for the ET simulations over China's Mainland,especially in the southern Yangtze River basin and Zhujiang River basin.This study demonstrates that,by merging more in situ and remote sensing observations in regional atmospheric forcing data,offline LSM simulations can better simulate regional-scale land surface hydrological processes.

Balancing flexural strength and porosity in DLP-3D printing Al_(2)O_(3)cores for hollow turbine blades

High porosity and high strength are usually mutually exclusive in the preparation of ceramic materials.However,high porosity and flexural strength are required for the preparation of complex ceramic cores for hollow turbine blades.In this study,Al_(2)O_(3)cores with high porosity and high flexural strength were successfully prepared using digital light processing(DLP)3 D printing technology.The influence of sintering temperature on the microstructure,pore evolution,and flexural strength of the cores were investigated.With an increase in the sintering temperature,the porosity of the ceramic cores first increased and then decreased,reaching a maximum value of 35%at 1400℃.The flexural strength increased with the increase in sintering temperature,but at 1400℃the incremental enhancement of flexural strength was greatest.Combined with the core service requirements and core performance,this study selected 1400℃(open porosity of 35.1%and flexural strength of 20.3 MPa)as the optimal sintering temperature for the DLP-3 D printed Al_(2)O_(3)core.

Influence of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3 Ceramic via 3D Stereolithography

In this work,aluminum oxide(Al2O3) ceramic samples were fabricated by 3D stereolithography printing.Printing process was followed by debinding and sintering.In addition,the effect of sintering temperature on micro structure and properties was investigated.Flexure strength was observed to increase with increasing sintering temperature due to fewer pores,fewer defects and stronger grain boundary bonding of samples at higher sintering temperatures.Maximum flexure strength of 138.5 MPa was obtained when sintering temperature was 150℃.Furthermore,the shrinkage along length direction decreased with the decreasing sintering temperature until reaching minimum value of 1.02% after sintering at 1200℃.After sintering at 1280℃,flexure strength was 24.0 MPa and the shrinkage along length direction was 2.1%,which meets demands of ceramic core.

Effects of scanning speed on microstructure in laser surface-melted single crystal superalloy and theoretical analysis

Scanning speed is a critical parameter for laser process, which can play a key role in the microstruc- ture evolution of laser melting. In the laser melting of single crystal superalloy, the effects of scanning speed were investigated by experimental analysis and computational simulation. The laser was scanning along [710] direction on （001） surface in different speeds. Solidification microstructures of dendrites growth direction and the primary dendritic spacing were analyzed by metallograph. Besides, a planar interface during solidification was taken into attention, Experiment results indicated that the primary dendritic spacing and thickness of planar interface decrease with the increase of speed. Through simu- lation, distribution of dendrites growth velocity and thermal gradient along dendrite growth direction were calculated, and the simulation of dendrites growth direction agreed with the experiment results. Additionally, a constant value was acquired which can be used to predict the primary dendritic spacing. Moreover, according to curve-fitting method and inequality relation, a model was proposed to predict the thickness of planar interface.

Epitaxial growth and oxidation behavior of an overlay coating on a Ni-base single-crystal superalloy by laser cladding

An overlay coating material was deposited on a single crystal superalloy SRR99 by laser cladding.The microstructure and oxidation behavior of this coating was investigated through scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results indicated that although the composition of the coating was chosen based on the γ' composition in René N5 superalloy, the primary solidification phase of this coating during laser cladding was γ-Ni. Furthermore, under the laser cladding condition, fine parallel dendrites grew epitaxially in the coating from the substrate, indicating the single crystal structure of the substrate was reproduced. When the single crystal MCrAlY coating was oxidized at 1000?, both Al_2O_3 and Al_2O_3 formed during initial oxidation process. As the oxidation time proceeded, the presence of Al_2O_3 facilitated the formation of NiAl_2O_4 spinel oxide. Once the spinel was observed, it flourished and induced some porosity in the scale. When the scale thickness increased to 6–7 μm, large area spallation of the scale began.