With the continuous advancement of the internationalization of higher education in China,the Grade Point Average(GPA)has become a primary indicator for evaluating academic performance in universities,playing a positiv...With the continuous advancement of the internationalization of higher education in China,the Grade Point Average(GPA)has become a primary indicator for evaluating academic performance in universities,playing a positive role in educational management.However,as it is closely tied to students’immediate interests,such as awards,exemptions from entrance exams for postgraduate recommendations,and domestic or international further education,certain new issues have emerged in its practical application.These problems have hindered the effective functioning of the GPA system,attracting widespread attention.This paper examines the origin,connotation,and theoretical assumptions of the GPA system,discusses its positive functions and existing challenges,and proposes recommendations for further improving academic evaluation.展开更多
In this paper,a multiscale model is developed for the mass functionally graded(FG)beam-fluid system to investigate its static and dynamic responses based on 3D printed porous beam free vibration tests,which are determ...In this paper,a multiscale model is developed for the mass functionally graded(FG)beam-fluid system to investigate its static and dynamic responses based on 3D printed porous beam free vibration tests,which are determined by two aspects.At the microstructural level,the gradient variation is realized by arbitrary distribution of matrix pores,and the effective moduli under specific distribution are obtained using the micromechanics homogenization theory.In the meantime,at the structural level,the mechanical responses of FG porous beams subjected to mass loading are considered in a static fluid environment.Then,the explicit expressions of local finite-element(FE)expressions corresponding to the static and dynamic responses are given in the appendices.The present results are validated against numerical and experimental results from the literature and mechanical tests of 3D printed structures,with good agreement generally obtained,giving credence to the present model.On this basis,a comprehensive parametric study is carried out,with a particular focus on the effects of boundary conditions,fluid density,and slenderness ratio on the bending and vibration of FG beams with several different gradations.展开更多
动物实验是生物医学研究中的重要手段,是连接基础研究与临床试验的桥梁。动物实验的系统评价/Meta分析(systematic review/meta-analysis,SRs/MAs)是整合动物实验证据的重要手段,能够促进成果向临床研究转化,降低转化风险,并推动基础研...动物实验是生物医学研究中的重要手段,是连接基础研究与临床试验的桥梁。动物实验的系统评价/Meta分析(systematic review/meta-analysis,SRs/MAs)是整合动物实验证据的重要手段,能够促进成果向临床研究转化,降低转化风险,并推动基础研究的资源整合。随着证据推荐分级的评估、制订与评价(grading of recommendations assessment,development and evaluation,GRADE)方法的不断发展,其在动物实验SRs/MAs中的应用受到了越来越多的关注。本文首先阐述了GRADE方法在动物实验SRs/MAs中的应用原理及具体应用类型,包括定性描述的系统评价、Meta分析及网状Meta分析;接着深入分析了GRADE方法在实际应用中的误用情况,主要包括未正确进行证据体分级、证据体分级不当、误用于定性系统评价、升降级过程记录与结果不一致,以及误用于提供推荐意见;此外,还全面探讨了GRADE方法在动物实验SRs/MAs中的证据确信度升降级因素,包括偏倚风险、间接性、不一致性、不精确性和发表偏倚对证据降级的影响,以及大效应量和跨物种一致性对证据升级的作用;最后,针对上述问题提出了改进策略,包括进一步研究与优化GRADE方法在动物实验SRs/MAs中的应用细节、制定符合动物实验研究特点的SRs/MAs报告规范,以及加强研究人员在GRADE方法上的专业培训等。本文旨在通过提升动物实验SRs/MAs的证据质量,增强其在临床决策中的可靠性,促进动物实验研究成果更高效地转化为临床实践。展开更多
In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The fu...In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.展开更多
应用推荐分级的评估、制订和评价(grading of recommendations assessment,development and evaluation,GRADE)系统与中药有效性评价整合证据链法(integrated evidence chain-based effectiveness evaluation of traditional Chinese me...应用推荐分级的评估、制订和评价(grading of recommendations assessment,development and evaluation,GRADE)系统与中药有效性评价整合证据链法(integrated evidence chain-based effectiveness evaluation of traditional Chinese medicine,Eff-iEC)对指南或专家共识推荐频次较高的12种治疗骨质疏松症的常用中成药进行了证据评价。结果显示,仙灵骨葆胶囊/片根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为BA+B^(+)(中级证据);金天格胶囊根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为AA+B(高级证据);骨疏康颗粒/胶囊根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为BA+B^(+)(中级证据);左归丸根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为AA^(++)B^(+)(高级证据);强骨胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AA+B^(+)(高级证据);壮骨止痛胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为BA+B(中级证据);金匮肾气丸根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AA+B(高级证据);全杜仲胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AD+B^(+)(低级证据);淫羊藿总黄酮胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AAB^(+)(高级证据);右归丸根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AA^(++)B^(+)(高级证据);芪骨胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为BB^(+)B(中级证据);六味地黄丸根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为AA^(++)B^(+)(高级证据)。整体而言,Eff-iEC评价体系较GRADE系统能更全面地评价中医药的有效性证据,但仍有不够完善之处,制约其推广应用。在临床证据评价方面,Eff-iEC评价体系与GRADE系统均反映出当前中成药治疗骨质疏松症的临床研究质量普遍较低,未来尚需开展高质量临床试验,进一步验证临床疗效。展开更多
The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to ...The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to achieving controllable stress-strain rate loading.In this study,we have,for the first time,combined one-dimensional fluid computational software with machine learning methods.We first elucidated the mechanisms by which GDI structures control stress and strain rates.Subsequently,we constructed a machine learning model to create a structure-property response surface.The results show that altering the loading velocity and interlayer thickness has a pronounced regulatory effect on stress and strain rates.In contrast,the impedance distribution index and target thickness have less significant effects on stress regulation,although there is a matching relationship between target thickness and interlayer thickness.Compared with traditional design methods,the machine learning approach offers a10^(4)—10^(5)times increase in efficiency and the potential to achieve a global optimum,holding promise for guiding the design of GDI.展开更多
Fe-Mo functionally graded materials(FGMs)with different composition-change rates from 100%304 stainless steel to 100%Mo along the composition gradient direction were prepared by electron beam-directed energy depositio...Fe-Mo functionally graded materials(FGMs)with different composition-change rates from 100%304 stainless steel to 100%Mo along the composition gradient direction were prepared by electron beam-directed energy deposition(EB-DED)technique,including three samples with composition mutation of 100%,composition change rate of 10%and 30%.Results show that the composition-change rate significantly affects the microstructure and mechanical properties of the samples.In the sample with abrupt change of composition,the sharp shift in composition between 304 stainless steel and Mo leads to a great difference in the microstructure and hardness near the interface between the two materials.With the increase in the number of gradient layers,the composition changes continuously along the direction of deposition height,and the microstructure morphology shows a smooth transition from 304 stainless steel to Mo,which is gradually transformed from columnar crystal to dendritic crystal.Elements Fe,Mo,and other major elements transform linearly along the gradient direction,with sufficient interlayer diffusion between the deposited layers,leading to good metallurgical bonding.The smaller the change in composition gradient,the greater the microhardness value along the deposition direction.When the composition gradient is 10%,the gradient layer exhibits higher hardness(940 HV)and excellent resistance to surface abrasion,and the overall compressive properties of the samples are better,with the compressive fracture stress in the top region reaching 750.05±14 MPa.展开更多
Current modifications of Ti-based materials with porous scaffolds for achieving biological fixation often decrease corrosion fatigue strength(σ_(cf))of the resultant implants,thereby shortening their service lifes-pa...Current modifications of Ti-based materials with porous scaffolds for achieving biological fixation often decrease corrosion fatigue strength(σ_(cf))of the resultant implants,thereby shortening their service lifes-pan.To resolve this issue,in the present,a step-wise graded porous Ti-6Al-7Nb scaffold was additively manufactured on optimally surface mechanical attrition treated(SMATed)Ti-6Al-7Nb(specifically de-noted as S-Ti6Al7Nb)using laser powder bed fusion(PBF)technology.The microstructure,bond strength,residual stress distribution,and corrosion fatigue behavior of porous scaffolds modified S-Ti6Al7Nb were investigated and compared with those of mechanically polished Ti-6Al-7Nb(P-Ti6Al7Nb),S-Ti6Al7Nb,and porous scaffolds modified P-Ti6Al7Nb.Results showed that corrosion fatigue of porous scaffolds modi-fied Ti-6Al-7Nb was propagation controlled.Moreover,the crack propagation behavior in the PBF scaf-fold’s fusion zone(FZ)and heat-affected zone(HAZ),exhibiting insensitivity to the microstructural con-figurations characterized by columnar prior-βgrain(PBG)boundaries and acicularα''martensites,cou-pled with the PBF-induced residual tensile stresses in these regions,resulted in a considerable decrease inσ_(cf) for porous scaffolds modified P-Ti6Al7Nb compared to P-Ti6Al7Nb.In contrast,step-wise graded porous scaffold-modified S-Ti6Al7Nb demonstrated an improvedσ_(cf) which was even higher than that of P-Ti6Al7Nb.Such an advancement in corrosion fatigue strength is primarily attributed to the presence of residual compressive stresses within the underlying S-Ti6Al7Nb substrate,extending beyond FZ and HAZ.These stresses increased the crack propagation threshold,leading to crack deflection/branching and increased crack-path tortuosity,thereby synergistically markedly enhancing the crack propagation resis-tance of porous scaffolds modified S-Ti6Al7Nb.展开更多
Based on simplified calculations of one-dimensional wave systems,loading pressure platform curves of Al-Cu gradient materials(GMs)impactor were designed.The Al-Cu GMs were prepared using tape-pressing sintering,and th...Based on simplified calculations of one-dimensional wave systems,loading pressure platform curves of Al-Cu gradient materials(GMs)impactor were designed.The Al-Cu GMs were prepared using tape-pressing sintering,and their acoustic properties were characterized to match the design path.The parallelism of the Al-Cu GM was confirmed using a three-dimensional surface profilometry machine.A one-stage light-gas gun was used to launch the Al-Cu GM,impacting an Al-LiF target at a velocity of 400 m/s.The results of the experimental strain rate demonstrate that the Al-Cu GMs can realize the precise control of the strain rate within the range of 10^(4)‒10^(5)/s in the high-speed impact experiments.展开更多
SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials(FGMs).Two FGMs,namely 60%SS316L+...SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials(FGMs).Two FGMs,namely 60%SS316L+20%Inconel625+20%Ti6Al4V composite and 60%SS316L+20%Inconel625+20%Inconel718 composite,were prepared.The tensile strength,elongation,yield strength,hardness,cross section area of the parent material,and composition were analysed.Results illustrate that the 60%SS316L+20%Inconel625+20%Inconel718 composite has better mechanical properties than 60%SS316L+20%Inconel625+20%Ti6Al4V composite,and the comprehensive properties of 60%SS316L+20%Inconel 625+20%Ti6Al4V composite are better than those of the parent material SS316L.Hence,the composite of 60%SS316L+20%Inconel625+20%Inconel718 is optimal.Due to its high strength,the 60%SS316L+20%Inconel625+20%Inconel718 composite has great application potential in the field of high pressure pneumatic tool and defence tool.展开更多
This review explores multi-directional functionally graded(MDFG)nanostructures,focusing on their material characteristics,modeling approaches,and mechanical behavior.It starts by classifying different types of functio...This review explores multi-directional functionally graded(MDFG)nanostructures,focusing on their material characteristics,modeling approaches,and mechanical behavior.It starts by classifying different types of functionally graded(FG)materials such as conventional,axial,bi-directional,and tri-directional,and the material distribution models like power-law,exponential,trigonometric,polynomial functions,etc.It also discusses the application of advanced size-dependent theories like Eringen’s nonlocal elasticity,nonlocal strain gradient,modified couple stress,and consistent couple stress theories,which are essential to predict the behavior of structures at small scales.The review covers the mechanical analysis of MDFG nanostructures in nanobeams,nanopipes,nanoplates,and nanoshells and their dynamic and static responses under different loading conditions.The effect of multi-directional material gradation on stiffness,stability and vibration is discussed.Moreover,the review highlights the need for more advanced analytical,semi-analytical,and numerical methods to solve the complex vibration problems ofMDFG nanostructures.It is evident that the continued development of these methods is crucial for the design,optimization,and real-world application of MDFG nanostructures in advanced engineering fields like aerospace,biomedicine,and micro/nanoelectromechanical systems(MEMS/NEMS).This study is a reference for researchers and engineers working in the domain of MDFG nanostructures.展开更多
Objective:To assess whether there is a correlation between CT scan severity score and pulmonary function in Interstitial Lung Disease,and provide a more reliable basis for clinical diagnosis and treatment.Materials an...Objective:To assess whether there is a correlation between CT scan severity score and pulmonary function in Interstitial Lung Disease,and provide a more reliable basis for clinical diagnosis and treatment.Materials and Methods:Sixty patients with clinical diagnosis of Interstitial Lung Disease(ILD)were collected,and chest CT and pulmonary function tests were performed at the same time.Here DLCO%and FEV1%were used as the pulmonary function indexes.The severity of the patients was assessed by CT scores as mild(range,1~10),moderate(range 11~20),and severe(range 21~30).Correlation analysis was carried out between CT score and pulmonary function index,and the lung function parameters of patients at three grades were compared between groups and pairwise among the means.Results:As per the CT severity classification,there were 13 mild cases,31 moderate cases,and 16 severe cases.CT score was negatively correlated with DLCO%and FEV1%.R value was-0.814 and-0.797,respectively;The comparison of the mean value of DLCO%and FEV1%among the three groups and the pairings of the mean value of DLCO%and FEV1%were statistically significant.Conclusion:There was good correlation between CT score of ILD and the pulmonary function index.The pulmonary function index of patients with different CT severity grading was statistically significant,which can provide a new basis for the clinical evaluation and diagnosis of the disease.展开更多
The utilization of graded Al powders offers the possibility to adjust the combustion performance of Al powders,while simultaneously safeguarding their energy properties.In this paper,a series of graded Al powder have ...The utilization of graded Al powders offers the possibility to adjust the combustion performance of Al powders,while simultaneously safeguarding their energy properties.In this paper,a series of graded Al powder have been incorporated into the typical Al@AP composites through the spray drying technique.The thermal behavior,ignition and combustion characteristics were comprehensively evaluated and compared.The experimental results showed that with the varying inclusion of the graded Al,the heat of reaction exhibited a significant change,ranging from 9090 J·g^(-1) to 11036 J·g^(-1),which was strongly dependent on the particle size of Al.The combination of Al with diverse range of particle sizes in graded configuration serves to significantly enhance the decomposition of AP,resulting in the disappearance of the LTD stage and a conspicuous decrease of at least 11.7℃ in the peak temperature of the HTD.Furthermore,the maximum burning rate achieved by the Al-3@AP composite was 33.6 mm·s^(-1),which was exactly twice as high as that of the graded Al-1@AP composite with the lowest burning rate.Diffraction peaks corresponding to unburned Al were detected in the condensed combustion products of Al-1@AP,and the combustion images clearly indicated an incomplete combustion tendency for this sample.In contrast,a well-designed gradation of Al powders,such as a combination of fine Al powders with a particle size below 5μm,has proven to be the most conducive to enhancing the combustion efficiency of the composites.展开更多
A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation.The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem,an...A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation.The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem,and the boundary modes of each bandgap are analyzed to understand the effects of each component of the unit cell on the bandgap formation.It is found that the metamaterials with a low elastic modulus of ligaments can generate flexural wave bandgaps below 300 Hz.Multi-frequency vibrations can be suppressed through the selective manipulation of bandgaps.The dual-graded design of metamaterials that can significantly improve the bandgap width is proposed based on parametric studies.A new way that can regulate the bandgap is revealed by studying the graded elastic modulus in the substrate.The results demonstrate that the nonlinear gradient of the elastic modulus in the substrate offers better bandgap performance.Based on these analyses,the proposed elastic metamaterials can pave the way for multi-frequency vibration control,low-frequency bandgap broadening,and bandgap tuning.展开更多
A sustainable approach for recovering battery grade FePO_(4) and Li_(2)CO_(3) from Al/F-bearing spent LiFePO_(4)/C powder was proposed,including acid leaching,fluorinated coordination precipitation,homogeneous precipi...A sustainable approach for recovering battery grade FePO_(4) and Li_(2)CO_(3) from Al/F-bearing spent LiFePO_(4)/C powder was proposed,including acid leaching,fluorinated coordination precipitation,homogeneous precipitation,and high-temperature precipitation.Under the optimal conditions,the leaching efficiencies of Li,Fe,P,Al,and F were 97.6%,97.1%,97.1%,72.5%,and 63.3%,respectively.The effects of different parameters on the removal of Al/F impurities were systematically evaluated,indicating about 99.4%Al and 96.4%F in the leachate were precipitated in the form of Na_(3)Li_(3)Al_(2)F_(12),and their residual concentrations were only 0.0124 and 0.328 g/L,respectively,which could be directly used to prepare battery grade FePO_(4)(99.68%in purity).Lithium in the Al/F-bearing residue could be extracted through CaCO_(3)−CaSO_(4) roasting followed by acid leaching,ultimately obtaining 99.87%purity of Li_(2)CO_(3).The recovery rates of Li and Fe were 96.88%and 92.85%,respectively.An economic evaluation demonstrated that the process was profitable.展开更多
文摘With the continuous advancement of the internationalization of higher education in China,the Grade Point Average(GPA)has become a primary indicator for evaluating academic performance in universities,playing a positive role in educational management.However,as it is closely tied to students’immediate interests,such as awards,exemptions from entrance exams for postgraduate recommendations,and domestic or international further education,certain new issues have emerged in its practical application.These problems have hindered the effective functioning of the GPA system,attracting widespread attention.This paper examines the origin,connotation,and theoretical assumptions of the GPA system,discusses its positive functions and existing challenges,and proposes recommendations for further improving academic evaluation.
基金supported by the National Key Research and Development Program of China(No.2020YFA0711700)the National Natural Science Foundation of China(No.12322206,No.52378158,No.12302205)ZJU-ZCCC Institute of Collaborative Innovation(No.ZDJG2021002).
文摘In this paper,a multiscale model is developed for the mass functionally graded(FG)beam-fluid system to investigate its static and dynamic responses based on 3D printed porous beam free vibration tests,which are determined by two aspects.At the microstructural level,the gradient variation is realized by arbitrary distribution of matrix pores,and the effective moduli under specific distribution are obtained using the micromechanics homogenization theory.In the meantime,at the structural level,the mechanical responses of FG porous beams subjected to mass loading are considered in a static fluid environment.Then,the explicit expressions of local finite-element(FE)expressions corresponding to the static and dynamic responses are given in the appendices.The present results are validated against numerical and experimental results from the literature and mechanical tests of 3D printed structures,with good agreement generally obtained,giving credence to the present model.On this basis,a comprehensive parametric study is carried out,with a particular focus on the effects of boundary conditions,fluid density,and slenderness ratio on the bending and vibration of FG beams with several different gradations.
文摘动物实验是生物医学研究中的重要手段,是连接基础研究与临床试验的桥梁。动物实验的系统评价/Meta分析(systematic review/meta-analysis,SRs/MAs)是整合动物实验证据的重要手段,能够促进成果向临床研究转化,降低转化风险,并推动基础研究的资源整合。随着证据推荐分级的评估、制订与评价(grading of recommendations assessment,development and evaluation,GRADE)方法的不断发展,其在动物实验SRs/MAs中的应用受到了越来越多的关注。本文首先阐述了GRADE方法在动物实验SRs/MAs中的应用原理及具体应用类型,包括定性描述的系统评价、Meta分析及网状Meta分析;接着深入分析了GRADE方法在实际应用中的误用情况,主要包括未正确进行证据体分级、证据体分级不当、误用于定性系统评价、升降级过程记录与结果不一致,以及误用于提供推荐意见;此外,还全面探讨了GRADE方法在动物实验SRs/MAs中的证据确信度升降级因素,包括偏倚风险、间接性、不一致性、不精确性和发表偏倚对证据降级的影响,以及大效应量和跨物种一致性对证据升级的作用;最后,针对上述问题提出了改进策略,包括进一步研究与优化GRADE方法在动物实验SRs/MAs中的应用细节、制定符合动物实验研究特点的SRs/MAs报告规范,以及加强研究人员在GRADE方法上的专业培训等。本文旨在通过提升动物实验SRs/MAs的证据质量,增强其在临床决策中的可靠性,促进动物实验研究成果更高效地转化为临床实践。
文摘In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.
文摘应用推荐分级的评估、制订和评价(grading of recommendations assessment,development and evaluation,GRADE)系统与中药有效性评价整合证据链法(integrated evidence chain-based effectiveness evaluation of traditional Chinese medicine,Eff-iEC)对指南或专家共识推荐频次较高的12种治疗骨质疏松症的常用中成药进行了证据评价。结果显示,仙灵骨葆胶囊/片根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为BA+B^(+)(中级证据);金天格胶囊根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为AA+B(高级证据);骨疏康颗粒/胶囊根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为BA+B^(+)(中级证据);左归丸根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为AA^(++)B^(+)(高级证据);强骨胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AA+B^(+)(高级证据);壮骨止痛胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为BA+B(中级证据);金匮肾气丸根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AA+B(高级证据);全杜仲胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AD+B^(+)(低级证据);淫羊藿总黄酮胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AAB^(+)(高级证据);右归丸根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为AA^(++)B^(+)(高级证据);芪骨胶囊根据GRADE系统评价为D级(极低级证据),根据Eff-iEC体系评价为BB^(+)B(中级证据);六味地黄丸根据GRADE系统评价为C级(低级证据),根据Eff-iEC体系评价为AA^(++)B^(+)(高级证据)。整体而言,Eff-iEC评价体系较GRADE系统能更全面地评价中医药的有效性证据,但仍有不够完善之处,制约其推广应用。在临床证据评价方面,Eff-iEC评价体系与GRADE系统均反映出当前中成药治疗骨质疏松症的临床研究质量普遍较低,未来尚需开展高质量临床试验,进一步验证临床疗效。
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030001)the National Key Research and Development Program of China(Grant No.2021YFB3802300)the Foundation of National Key Laboratory of Shock Wave and Detonation Physics(Grant No.JCKYS2022212004)。
文摘The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to achieving controllable stress-strain rate loading.In this study,we have,for the first time,combined one-dimensional fluid computational software with machine learning methods.We first elucidated the mechanisms by which GDI structures control stress and strain rates.Subsequently,we constructed a machine learning model to create a structure-property response surface.The results show that altering the loading velocity and interlayer thickness has a pronounced regulatory effect on stress and strain rates.In contrast,the impedance distribution index and target thickness have less significant effects on stress regulation,although there is a matching relationship between target thickness and interlayer thickness.Compared with traditional design methods,the machine learning approach offers a10^(4)—10^(5)times increase in efficiency and the potential to achieve a global optimum,holding promise for guiding the design of GDI.
基金National Natural Science Foundation of China(51975286)。
文摘Fe-Mo functionally graded materials(FGMs)with different composition-change rates from 100%304 stainless steel to 100%Mo along the composition gradient direction were prepared by electron beam-directed energy deposition(EB-DED)technique,including three samples with composition mutation of 100%,composition change rate of 10%and 30%.Results show that the composition-change rate significantly affects the microstructure and mechanical properties of the samples.In the sample with abrupt change of composition,the sharp shift in composition between 304 stainless steel and Mo leads to a great difference in the microstructure and hardness near the interface between the two materials.With the increase in the number of gradient layers,the composition changes continuously along the direction of deposition height,and the microstructure morphology shows a smooth transition from 304 stainless steel to Mo,which is gradually transformed from columnar crystal to dendritic crystal.Elements Fe,Mo,and other major elements transform linearly along the gradient direction,with sufficient interlayer diffusion between the deposited layers,leading to good metallurgical bonding.The smaller the change in composition gradient,the greater the microhardness value along the deposition direction.When the composition gradient is 10%,the gradient layer exhibits higher hardness(940 HV)and excellent resistance to surface abrasion,and the overall compressive properties of the samples are better,with the compressive fracture stress in the top region reaching 750.05±14 MPa.
基金the National Key Research and Development Program of China(Grant No.2023YFC2412600)the National Natural Science Foundation of China(Grant No.51971171)for financially supporting this work.
文摘Current modifications of Ti-based materials with porous scaffolds for achieving biological fixation often decrease corrosion fatigue strength(σ_(cf))of the resultant implants,thereby shortening their service lifes-pan.To resolve this issue,in the present,a step-wise graded porous Ti-6Al-7Nb scaffold was additively manufactured on optimally surface mechanical attrition treated(SMATed)Ti-6Al-7Nb(specifically de-noted as S-Ti6Al7Nb)using laser powder bed fusion(PBF)technology.The microstructure,bond strength,residual stress distribution,and corrosion fatigue behavior of porous scaffolds modified S-Ti6Al7Nb were investigated and compared with those of mechanically polished Ti-6Al-7Nb(P-Ti6Al7Nb),S-Ti6Al7Nb,and porous scaffolds modified P-Ti6Al7Nb.Results showed that corrosion fatigue of porous scaffolds modi-fied Ti-6Al-7Nb was propagation controlled.Moreover,the crack propagation behavior in the PBF scaf-fold’s fusion zone(FZ)and heat-affected zone(HAZ),exhibiting insensitivity to the microstructural con-figurations characterized by columnar prior-βgrain(PBG)boundaries and acicularα''martensites,cou-pled with the PBF-induced residual tensile stresses in these regions,resulted in a considerable decrease inσ_(cf) for porous scaffolds modified P-Ti6Al7Nb compared to P-Ti6Al7Nb.In contrast,step-wise graded porous scaffold-modified S-Ti6Al7Nb demonstrated an improvedσ_(cf) which was even higher than that of P-Ti6Al7Nb.Such an advancement in corrosion fatigue strength is primarily attributed to the presence of residual compressive stresses within the underlying S-Ti6Al7Nb substrate,extending beyond FZ and HAZ.These stresses increased the crack propagation threshold,leading to crack deflection/branching and increased crack-path tortuosity,thereby synergistically markedly enhancing the crack propagation resis-tance of porous scaffolds modified S-Ti6Al7Nb.
基金Natural Science Foundation of Hubei Province(2024AFB432)National Natural Science Foundation of China(52171045,12302436,52302095)Research Fund of Jianghan University(2023JCYJ05)。
文摘Based on simplified calculations of one-dimensional wave systems,loading pressure platform curves of Al-Cu gradient materials(GMs)impactor were designed.The Al-Cu GMs were prepared using tape-pressing sintering,and their acoustic properties were characterized to match the design path.The parallelism of the Al-Cu GM was confirmed using a three-dimensional surface profilometry machine.A one-stage light-gas gun was used to launch the Al-Cu GM,impacting an Al-LiF target at a velocity of 400 m/s.The results of the experimental strain rate demonstrate that the Al-Cu GMs can realize the precise control of the strain rate within the range of 10^(4)‒10^(5)/s in the high-speed impact experiments.
文摘SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials(FGMs).Two FGMs,namely 60%SS316L+20%Inconel625+20%Ti6Al4V composite and 60%SS316L+20%Inconel625+20%Inconel718 composite,were prepared.The tensile strength,elongation,yield strength,hardness,cross section area of the parent material,and composition were analysed.Results illustrate that the 60%SS316L+20%Inconel625+20%Inconel718 composite has better mechanical properties than 60%SS316L+20%Inconel625+20%Ti6Al4V composite,and the comprehensive properties of 60%SS316L+20%Inconel 625+20%Ti6Al4V composite are better than those of the parent material SS316L.Hence,the composite of 60%SS316L+20%Inconel625+20%Inconel718 is optimal.Due to its high strength,the 60%SS316L+20%Inconel625+20%Inconel718 composite has great application potential in the field of high pressure pneumatic tool and defence tool.
文摘This review explores multi-directional functionally graded(MDFG)nanostructures,focusing on their material characteristics,modeling approaches,and mechanical behavior.It starts by classifying different types of functionally graded(FG)materials such as conventional,axial,bi-directional,and tri-directional,and the material distribution models like power-law,exponential,trigonometric,polynomial functions,etc.It also discusses the application of advanced size-dependent theories like Eringen’s nonlocal elasticity,nonlocal strain gradient,modified couple stress,and consistent couple stress theories,which are essential to predict the behavior of structures at small scales.The review covers the mechanical analysis of MDFG nanostructures in nanobeams,nanopipes,nanoplates,and nanoshells and their dynamic and static responses under different loading conditions.The effect of multi-directional material gradation on stiffness,stability and vibration is discussed.Moreover,the review highlights the need for more advanced analytical,semi-analytical,and numerical methods to solve the complex vibration problems ofMDFG nanostructures.It is evident that the continued development of these methods is crucial for the design,optimization,and real-world application of MDFG nanostructures in advanced engineering fields like aerospace,biomedicine,and micro/nanoelectromechanical systems(MEMS/NEMS).This study is a reference for researchers and engineers working in the domain of MDFG nanostructures.
基金providing by the Shenzhen City Nanshan District Science and Technology Plan Project(Medical and Health Category)(Grant No.2018073)。
文摘Objective:To assess whether there is a correlation between CT scan severity score and pulmonary function in Interstitial Lung Disease,and provide a more reliable basis for clinical diagnosis and treatment.Materials and Methods:Sixty patients with clinical diagnosis of Interstitial Lung Disease(ILD)were collected,and chest CT and pulmonary function tests were performed at the same time.Here DLCO%and FEV1%were used as the pulmonary function indexes.The severity of the patients was assessed by CT scores as mild(range,1~10),moderate(range 11~20),and severe(range 21~30).Correlation analysis was carried out between CT score and pulmonary function index,and the lung function parameters of patients at three grades were compared between groups and pairwise among the means.Results:As per the CT severity classification,there were 13 mild cases,31 moderate cases,and 16 severe cases.CT score was negatively correlated with DLCO%and FEV1%.R value was-0.814 and-0.797,respectively;The comparison of the mean value of DLCO%and FEV1%among the three groups and the pairings of the mean value of DLCO%and FEV1%were statistically significant.Conclusion:There was good correlation between CT score of ILD and the pulmonary function index.The pulmonary function index of patients with different CT severity grading was statistically significant,which can provide a new basis for the clinical evaluation and diagnosis of the disease.
文摘The utilization of graded Al powders offers the possibility to adjust the combustion performance of Al powders,while simultaneously safeguarding their energy properties.In this paper,a series of graded Al powder have been incorporated into the typical Al@AP composites through the spray drying technique.The thermal behavior,ignition and combustion characteristics were comprehensively evaluated and compared.The experimental results showed that with the varying inclusion of the graded Al,the heat of reaction exhibited a significant change,ranging from 9090 J·g^(-1) to 11036 J·g^(-1),which was strongly dependent on the particle size of Al.The combination of Al with diverse range of particle sizes in graded configuration serves to significantly enhance the decomposition of AP,resulting in the disappearance of the LTD stage and a conspicuous decrease of at least 11.7℃ in the peak temperature of the HTD.Furthermore,the maximum burning rate achieved by the Al-3@AP composite was 33.6 mm·s^(-1),which was exactly twice as high as that of the graded Al-1@AP composite with the lowest burning rate.Diffraction peaks corresponding to unburned Al were detected in the condensed combustion products of Al-1@AP,and the combustion images clearly indicated an incomplete combustion tendency for this sample.In contrast,a well-designed gradation of Al powders,such as a combination of fine Al powders with a particle size below 5μm,has proven to be the most conducive to enhancing the combustion efficiency of the composites.
基金Project supported by the National Natural Science Foundation of China(Nos.11872233,U2341231,and 12102245)。
文摘A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation.The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem,and the boundary modes of each bandgap are analyzed to understand the effects of each component of the unit cell on the bandgap formation.It is found that the metamaterials with a low elastic modulus of ligaments can generate flexural wave bandgaps below 300 Hz.Multi-frequency vibrations can be suppressed through the selective manipulation of bandgaps.The dual-graded design of metamaterials that can significantly improve the bandgap width is proposed based on parametric studies.A new way that can regulate the bandgap is revealed by studying the graded elastic modulus in the substrate.The results demonstrate that the nonlinear gradient of the elastic modulus in the substrate offers better bandgap performance.Based on these analyses,the proposed elastic metamaterials can pave the way for multi-frequency vibration control,low-frequency bandgap broadening,and bandgap tuning.
基金financially supported by the Key Research and Development Program of Guangxi,China(No.GUIKE AB23026051)the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3039)the Fundamental Research Funds for the Central Universities of Central South University,China.
文摘A sustainable approach for recovering battery grade FePO_(4) and Li_(2)CO_(3) from Al/F-bearing spent LiFePO_(4)/C powder was proposed,including acid leaching,fluorinated coordination precipitation,homogeneous precipitation,and high-temperature precipitation.Under the optimal conditions,the leaching efficiencies of Li,Fe,P,Al,and F were 97.6%,97.1%,97.1%,72.5%,and 63.3%,respectively.The effects of different parameters on the removal of Al/F impurities were systematically evaluated,indicating about 99.4%Al and 96.4%F in the leachate were precipitated in the form of Na_(3)Li_(3)Al_(2)F_(12),and their residual concentrations were only 0.0124 and 0.328 g/L,respectively,which could be directly used to prepare battery grade FePO_(4)(99.68%in purity).Lithium in the Al/F-bearing residue could be extracted through CaCO_(3)−CaSO_(4) roasting followed by acid leaching,ultimately obtaining 99.87%purity of Li_(2)CO_(3).The recovery rates of Li and Fe were 96.88%and 92.85%,respectively.An economic evaluation demonstrated that the process was profitable.
