A practical model for efficient anti-fatigue design and selection of metallic materials:Ⅰ.Model building and fatigue strength prediction

The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic materials.For this problem,a theoretical fatigue model is proposed in this study,the possible applications have also been discussed.Specific results would be introduced in two serial papers,in which the first paper focuses on the model building and the applications on fatigue strength prediction;the second paper put emphasis on the influencing factors of the model parameters and the applications on fatigue strength improvement.In this first paper,a theoretical model is proposed considering both the strength and plastic restrictions of fatigue strength.As the model builds up a brief relationship among yield strength(Y),tensile strength(T)and fatigue strength(F),it is named as the Y-T-F model.Through the verification with fatigue strength data covering various kinds of metallic materials and loading conditions,this Y-T-F model exhibits both generality and accuracy.With the Y-T-F model,the efficient fatigue strength prediction could be conducted by brief linear fitting and calculation,just through yield strength,tensile strength and several known fatigue strength data.Moreover,through its deduced Y-F model,the analytical formula of fatigue strength continuously changing with materials strengthening can be obtained,as well as the maximum value of fatigue strength and corresponding critical yield strength.In summary,the Y-T-F model would be useful for reducing the fatigue tests,thus providing new possibilities on the efficient anti-fatigue design and selection of metallic materials.

A practical model for efficient anti-fatigue design and selection of metallic materials:Ⅱ.Parameter analysis and fatigue strength improvement

In the first paper,a Y-T-F model was proposed based on the restrictions of both strength and plasticity;the corresponding applications on the fatigue strength prediction have also been discussed.In this second paper,the emphasis will be put on the issues of fatigue strength improvement.Based on the primary form of the Y-T-F model,the parameters are further analyzed and quantified,to clarify the influences of various factors on fatigue strength.Firstly,the damage capacity C is proved to be sensitive to the elastic modulus E,which could change with the alloying components and nano-scaled grain boundaries;the increase of E would lead to the increasing C,thus increase the fatigue strength.Secondly,the microstructure characteristic coefficient a,as well as the yield strengthσ_(y) and tensile strengthσ_(b) in the crack initiation region could be influenced by the processing mode,grain size and microstructure uniformity of materials;the change of microstructure characteristics would affect the changing tendency of tensile strength--fatigue strength relation via varying the values of a,σ_(y) andσ_(b).Thirdly,the damage weight coefficientωis found to be a reflection of the fatigue strength declination induced by defects;the defect dimension D,the defect shape correlated stress concentration coefficient Kt,as well as the strengthening level of matrix materialsσ_(b) are all corresponding factors.Quantified correlations between the above parameters and corresponding factors are comprehensively built up,hence obtaining the influences of either a single factor or multiple factors on fatigue strength.This further developed Y-T-F model would be helpful to clarify the direction of fatigue strength improvement,and contribute to the anti-fatigue design optimization of metallic materials.

A comparative study of the anti-fatigue activity of extracts from different parts of Cistanche tubulosa(Schenk)Wight

Objective:To evaluate the anti-fatigue effects of different extracts from Cistanche tubulosa(Schenk)Wight(C.tubulosa,Rou Cong Rong),focusing on central and exercise-induced fatigue in mice.This study investigated the pharmacological effects of the total oligosaccharides,polysaccharides,and phenylethanoid glycosides(CPhGs)extracted from C.tubulosa.Methods: Models of sleep deprivation and forced swimming fatigue were established to simulate central and exercise-induced fatigue.The mice were treated with different extracts of C.tubulosa,and their effects were assessed using behavioral tests to measure exercise capacity,learning,and memory function.Biochemical analyses were performed to evaluate the changes in serum and brain neurotransmitter levels,liver and muscle glycogen storage,and various fatigue-related biomarkers.Results: This study found that treatment with C.tubulosa extract improved exercise capacity,learning,and memory in mice.Total oligosaccharides from C.tubulosa enhanced adrenocorticotropic hormone,cholinesterase,and thyroid-stimulating hormone levels,reduced cortisol levels in central fatigue models,and ameliorated biochemical markers of exercise-induced fatigue,including lowering lactic acid,blood urea nitrogen,and malondialdehyde levels.Among the tested extracts,the total oligosaccharides showed the most comprehensive anti-fatigue effects.Conclusion: The anti-fatigue effects of C.tubulosa,particularly those of its total oligosaccharides,are pronounced in both central and exercise-induced fatigue.These effects are mediated by the regulation of neurotransmitter levels,enhancement of glycogen storage,and improvement of antioxidant enzyme activity,suggesting potential therapeutic benefits in fatigue-related conditions.

水田动力底盘逆向建模与质心验证——基于Geomagic Design X

针对目前农业机械仿真和优化模型精度不高的问题,提出了一种构建精确模型的逆向建模方法。应用光学扫描仪采集点云数据,基于Geomagic Design X处理点云数据并重构零部件模型,在SolidWorks中完成水田动力底盘的装配。以VP6D-CQ型水田动力底盘为例,将测得的实际质心位置与所建的模型质心位置进行比较,并对提出的逆向建模方法进行了试验验证以及误差分析。结果表明:总质量、x坐标、y坐标、z坐标的误差值分别为4.55%、3.62%、2.23%、4.81%,误差值均在5%内。此方法可构建准确的三维模型,为后续仿真优化数据精确性奠定了基础,与传统的研发相比较,可缩短农业机械研发周期、降低设计成本。

App Designer辅助教学方法探索与实践——以软件无线电课程为例

软件无线电作为通信学科的必修课程,具有承上启下的重要作用。因课程原理抽象、理论公式复杂,学员在学习过程存在理解掌握难、实践应用难等问题。通过对当前软件无线电教学过程中存在的不足与困难进行分析,提出利用MATLAB App Designer辅助课程教学,从教学准备、课堂互动、自主实验、反馈提升四个方面开展课程教学改革。实践表明,该方法对于提升学员的工程思维、系统思维具有显著效果,同时可以增强学员理论联系实际的能力。

Anti-fatigue effects of salidroside in mice

Objective： To study the anti-fatigue effects of salidroside in mice. Methods： Totally 120 normal male Kunming mice were randomized into 5 groups （4 salidroside intervention groups and the control group） based on body weight. The control group was given distilled water and the 4 intervention groups were given various doses of salidroside （60, 180, 360, 720 mg/kg） for 15 consecutive days, respectively. The levels of lactate, serum urea nitrogen, muscle and liver glycogen, the longest swimming time and hemoglobin were determined before and after swimming test. Results： Different doses of salidroside significantly lengthened the swimming time and increased the contents of hemoglobin and muscle and liver glycogen, while reducing that of lactate in blood significantly compared with control group, especially in the 180 mg/kg salidroside group. Conclusion： Salidroside has noticeable anti-fatigue effect on mice. These effects were dose-dependent, and the strongest effect on most biomarkers was seen with an intermediate dose.

Anti-Fatigue Effect of Blended <i>Camellia oleifera Abel</i>Tea Oil and Ge-132 in Mice

Nowadays, people are busier and busier for working and living, and suffer a lot of pressure on their body or mind. Therefore, people are prone to have fatigue activity and decrease their working efficiency and happiness. It was reported that fatigue is a common symptom in the community, with up to half of the general population complaining of fatigue. More and more researchers devoted themselves to studying natural active ingredients in organism as the anti-fatigue drugs to release fatigue symptom. However, these natural ingredients were difficult to obtain from plants, animals and microorganisms by separating and purifying. In addition, some active substances have many side effects. In our study, we employed tea seed oil as main ingredients blended with bis-(carboxyethylgermanium) sesquioxide (Ge-132) to investigate the effects of anti-fatigue on mice by administrating mice with low dose, intermediate dose and high dose of tea seed oil complex for 0, 2 or 4 weeks. The specific tests of studying effects of anti-fatigue were body weight, weight-loaded force swimming, blood urea nitrogen, blood lactic acid and hepaticglycogen. And the results showed that appropriate level of tea seed oil complex could decrease the body weight and prolong the weight-loaded swimming time, and had an active effect on the bloodurea nitrogen, hepatic glycogen and blood lactic acid level mice, which significantly embodied the anti-fatigue activity of tea seed oil complex.

Evaluation of silymarin extract from Silybum marianum in mice: anti-fatigue activity

Silymarin has been used for centuries for its hepatoprotective properties. The specific objective of this study was to evaluate the anti-fatigue properties of silymarin. The silymarin was administered orally at doses of 50, 100, and 200 mg/kg for 4 weeks;the fatigue level and exercise performance were evaluated using exhaustive swimming time and pole-climbing time, as well as levels of plasma lactate, ammonia, glucose, creatine kinase(CK), serum urea nitrogen(SUN), blood lactic acid(BLA), muscle glycogen(MG), and liver glycogen(LG) contents after an intensive swimming session. The results demonstrated that silymarin treatment decreased the BLA and SUN levels while increased the LG and MG levels. In addition, silymarin decreased plasma lactate and ammonia levels and CK activity after swimming test, this is related to the mechanism that increases energy storage(as glycogen) and release(as blood glucose), and decreases plasma levels of lactate, ammonia, and CK. The observation of the skeletal muscle structures of mice also confirmed that skeletal muscles became more damaged in the control group compared with the silymarin-treated mice after prolonged endurance exercise. Therefore, it is reasonable to infer that silymarin may bear potential pharmacological effects in combating fatigue.

Present Situation of the Anti-Fatigue Processing of High-Strength Steel Internal Thread Based on Cold Extrusion Technology:A Review

The adoption of cold-extrusion forming for internal thread net forming becomes an important component of anti-fatigue processing with the development of internal thread processing towards high performance, low cost and low energy consumption. It has vast application foreground in the field of aviation, spaceflight, high speed train and etc. The internal thread processing and anti-fatigue manufacture technology are summarized. In terms of the perspective of processing quality and fatigue serving life, the advantages and disadvantages of the processing methods from are compared. The internal thread cold-extrusion processing technology is investigated for the purpose of improving the anti-fatigue serving life of internal thread. The superiorities of the plastic deformation law and surface integrity of the metal layer in the course of cold extrusion for improving its stability and economy are summed up. The proposed research forecasts the develop- ment tendency of the internal thread anti-fatigue manufacturing technology.

The study of Gongshisong＇ s anti-fatigue active site sifting

Aim To investigate the influence of the Gongshisong extract of different extraction parts on mice sports fatigue index. Method The mice were randomly divided into blank group, model group, the Gongshisong extract group （petroleum ether, chloroform, ethyl acetate, n-butanol, the aqueous layer） and the positive control group. The mice in different groups were fed with corresponding Gongshisong extract liquid 2.5 g kg^-1 d^-1 once per day for consecutively 7 days. The blank group and model group were given 1% sodium carboxymethyl cellulose so- lution, the positive control group was administered with Rhodiola 0.59 g · kg^-1· d^-1 After the last administered each group of mice were determined of weihgt-loading swimming time, liver glycogen and muscle glycogen content, and urea nitrogen, lactic acid and creatine kinase in 90min mice after swimming content in blood. Result Com- pared with the blank group, the petroleum ether extract of Gongshisong could significantly prolong the swimming time of mice （P 〈 0.05）, enhancing the mice muscle glycogen reserves （P 〈 0.05）, and reduce the level of urea nitrogen and creatine kinase in mice after swimming （P 〈 0.05）. Butanol extraction liquid of Gongshisong can ob- viously prolong the swimming time of mice （P 〈 0.05）, increasing the reserves of glycogen in mice （P 〈 0.05）, decreasing the level of urea nitrogen in mice and blood lactate after swimming （P 〈 0.05 ）. Water extract of Gong- shisong could significantly prolong the swimming time of mice （P 〈 0.05） , increasing muscle glycogen storage （P 〈0.05）, reducing the level of blood lactic acid in mice after swimming （P 〈 0.05）. Ethyl acetate extract of Gongshisong could significantly prolong the swimming time of mice （P 〈 0.05） , and increase the reserves of glyco- gen in mice （P 〈0. 05）. Conclusion Comprehensive analysis, the petroleum ether, n-butanol and water site of Gongshisong is better anti fatigue active site.

Alloy design for laser powder bed fusion additive manufacturing:a critical review

Metal additive manufacturing(AM)has been extensively studied in recent decades.Despite the significant progress achieved in manufacturing complex shapes and structures,challenges such as severe cracking when using existing alloys for laser powder bed fusion(L-PBF)AM have persisted.These challenges arise because commercial alloys are primarily designed for conventional casting or forging processes,overlooking the fast cooling rates,steep temperature gradients and multiple thermal cycles of L-PBF.To address this,there is an urgent need to develop novel alloys specifically tailored for L-PBF technologies.This review provides a comprehensive summary of the strategies employed in alloy design for L-PBF.It aims to guide future research on designing novel alloys dedicated to L-PBF instead of adapting existing alloys.The review begins by discussing the features of the L-PBF processes,focusing on rapid solidification and intrinsic heat treatment.Next,the printability of the four main existing alloys(Fe-,Ni-,Al-and Ti-based alloys)is critically assessed,with a comparison of their conventional weldability.It was found that the weldability criteria are not always applicable in estimating printability.Furthermore,the review presents recent advances in alloy development and associated strategies,categorizing them into crack mitigation-oriented,microstructure manipulation-oriented and machine learning-assisted approaches.Lastly,an outlook and suggestions are given to highlight the issues that need to be addressed in future work.

Web Layout Design of Large Cavity Structures Based on Topology Optimization

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

Design Principles and Mechanistic Understandings of Non-Noble-Metal Bifunctional Electrocatalysts for Zinc-Air Batteries

Zinc-air batteries(ZABs)are promising energy storage systems because of high theoretical energy density,safety,low cost,and abundance of zinc.However,the slow multi-step reaction of oxygen and heavy reliance on noble-metal catalysts hinder the practical applications of ZABs.Therefore,feasible and advanced non-noble-metal elec-trocatalysts for air cathodes need to be identified to promote the oxygen catalytic reaction.In this review,we initially introduced the advancement of ZABs in the past two decades and provided an overview of key developments in this field.Then,we discussed the work-ing mechanism and the design of bifunctional electrocatalysts from the perspective of morphology design,crystal structure tuning,interface strategy,and atomic engineering.We also included theoretical studies,machine learning,and advanced characterization technologies to provide a comprehensive understanding of the structure-performance relationship of electrocatalysts and the reaction pathways of the oxygen redox reactions.Finally,we discussed the challenges and prospects related to designing advanced non-noble-metal bifunctional electrocatalysts for ZABs.

Accelerated design of high-performance Mg-Mn-based magnesium alloys based on novel bayesian optimization

Magnesium(Mg),being the lightest structural metal,holds immense potential for widespread applications in various fields.The development of high-performance and cost-effective Mg alloys is crucial to further advancing their commercial utilization.With the rapid advancement of machine learning(ML)technology in recent years,the“data-driven''approach for alloy design has provided new perspectives and opportunities for enhancing the performance of Mg alloys.This paper introduces a novel regression-based Bayesian optimization active learning model(RBOALM)for the development of high-performance Mg-Mn-based wrought alloys.RBOALM employs active learning to automatically explore optimal alloy compositions and process parameters within predefined ranges,facilitating the discovery of superior alloy combinations.This model further integrates pre-established regression models as surrogate functions in Bayesian optimization,significantly enhancing the precision of the design process.Leveraging RBOALM,several new high-performance alloys have been successfully designed and prepared.Notably,after mechanical property testing of the designed alloys,the Mg-2.1Zn-2.0Mn-0.5Sn-0.1Ca alloy demonstrates exceptional mechanical properties,including an ultimate tensile strength of 406 MPa,a yield strength of 287 MPa,and a 23%fracture elongation.Furthermore,the Mg-2.7Mn-0.5Al-0.1Ca alloy exhibits an ultimate tensile strength of 211 MPa,coupled with a remarkable 41%fracture elongation.

The Preparation Technology Research and Composition Analysis of Anti-fatigue Yikangshu Granules

[Objectives]To optimize the preparation technology of Yikangshu granule,an anti-fatigue health food.[Methods]The process was studied from three aspects(raw material extraction,excipient selection and forming process),and then it was verified in pilot production,and the content of the three components of the product was determined.[Results]The optimum production process of the formula granules was as follows:raw materials were extracted(adding 1∶9 water,extracting twice,2.5 h each time);vacuum concentration;adding excipients and mixing after vacuum drying,crushing and sieving;granulation of 75%ethanol sifted by a 20-mesh sieve;drying at 60℃,sifting through 14-mesh,and packaging.The average content of products obtained was as follows:crude polysaccharides(3204 mg/100 g),total saponins(2295 mg/100 g),astragaloside A(21 mg/100 g).[Conclusions]The optimized preparation technology is stable and feasible,and has a quality that can be controlled,which can provide a reference for the development of health food in food industry.

Inverse design of mechanical metamaterial achieving a prescribedconstitutive curve

Besides exhibiting excellent capabilities such as energy absorption,phase-transforming metamaterials offer a vast design space for achieving nonlinear constitutive relations.This is facilitated by switching between different patterns under deformation.However,the related inverse design problem is quite challenging,due to the lack of appropriate mathematical formulation and the convergence issue in the post-buckling analysis of intermediate designs.In this work,periodic unit cells are explicitly described by the moving morphable voids method and effectively analyzed by eliminating the degrees of freedom in void regions.Furthermore,by exploring the Pareto frontiers between error and cost,an inverse design formulation is proposed for unit cells.This formulation aims to achieve a prescribed constitutive curve and is validated through numerical examples and experimental results.The design approach presented here can be extended to the inverse design of other types of mechanical metamaterials with prescribed nonlinear effective properties.

Anti-fatigue Effect of Water Extract from Centella asiatica(L.)Urban on Mice

[Objectives]To study the anti-fatigue effect of water extract from Centella asiatica(L.)Urban on mice.[Methods]After intragastric administration of low,medium and high concentration of water extract from Centella asiatica(L.)Urban for 14 d,the rotarod time and the content of serum lactic acid in mice were determined,respectively.[Results]Compared with the control group,the rotarod time of mice in the low and medium concentration groups was significantly prolonged(P<0.05),but there was no significant difference between the control group and the high concentration group;the content of serum lactic acid in the medium concentration group was significantly lower than that in the control group(P<0.01),but there was no significant difference between low concentration group and high concentration group and the control group.[Conclusions]A certain concentration of water extract from Centella asiatica(L.)Urban had a good anti-fatigue effect.

Machine learning for membrane design and discovery

Membrane technologies are becoming increasingly versatile and helpful today for sustainable development.Machine Learning(ML),an essential branch of artificial intelligence(AI),has substantially impacted the research and development norm of new materials for energy and environment.This review provides an overview and perspectives on ML methodologies and their applications in membrane design and dis-covery.A brief overview of membrane technologies isfirst provided with the current bottlenecks and potential solutions.Through an appli-cations-based perspective of AI-aided membrane design and discovery,we further show how ML strategies are applied to the membrane discovery cycle(including membrane material design,membrane application,membrane process design,and knowledge extraction),in various membrane systems,ranging from gas,liquid,and fuel cell separation membranes.Furthermore,the best practices of integrating ML methods and specific application targets in membrane design and discovery are presented with an ideal paradigm proposed.The challenges to be addressed and prospects of AI applications in membrane discovery are also highlighted in the end.

Deep Insight of Design,Mechanism,and Cancer Theranostic Strategy of Nanozymes

Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007,nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity,low cost,mild reaction conditions,good stability,and suitable for large-scale production.Recently,with the cross fusion of nanomedicine and nanocatalysis,nanozyme-based theranostic strategies attract great attention,since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects.Thus,various nanozymes have been developed and used for tumor therapy.In this review,more than 270 research articles are discussed systematically to present progress in the past five years.First,the discovery and development of nanozymes are summarized.Second,classification and catalytic mechanism of nanozymes are discussed.Third,activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory,machine learning,biomimetic and chemical design.Then,synergistic theranostic strategy of nanozymes are introduced.Finally,current challenges and future prospects of nanozymes used for tumor theranostic are outlined,including selectivity,biosafety,repeatability and stability,in-depth catalytic mechanism,predicting and evaluating activities.

Anti-fatigue Effect of L-arginine Complex Preparation on Mice

Objective:To investigate the anti-fatigue effect of L-arginine complex preparation on mice.Methods:The experimental mice were divided into a blank group,low dose group,medium dose group and high dose group.L-arginine complex preparation mice were intragastrically administered for 30 days,and the mice were tested for exhaustive swimming time.At the same time,contents of plasma lactic acid,lactate dehydrogenase,urea nitrogen and hepatic glycogen were measured.Results:Compared with the blank control group,the weight-bearing swimming time and hypoxia-tolerant survival time of the low,middle and high dose groups was significantly increased(P<0.05).Whereas,the serum urea nitrogen levels and lactose content were significantly decreased(P<0.05).However,compared with the blank control group,the liver glycogen content of the middle and high dose groups was increased significantly(P<0.05),and there was no significant difference in the low dose group.Conclusion:The L-arginine complex preparation has an anti-fatigue function in mice.