In order to investigate the damage tolerance of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe(Ti5321)alloy with bimodal microstructure using void growth quantification and micromechanical modeling,in situ tensile testing...In order to investigate the damage tolerance of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe(Ti5321)alloy with bimodal microstructure using void growth quantification and micromechanical modeling,in situ tensile testing was performed during X-ray microtomography experiments.Compared with investigations of surface voids by traditional two-dimensional(2D)methods involving post-mortem characterization,three-dimensional(3D)information on void evolution inside optically opaque samples obtained through X-ray microtomography is essential.The Rice and Tracey model and Huang model were applied to predict void growth and show good agreement with experimental data using calibration of the damage parameterα.The void growth kinetics of Ti5321 with bimodal microstructure was analyzed by comparing theαvalue with that of Ti64 for different microstructure morphologies.The damage mechanism of ductile fracture of Ti5321 with bimodal microstructure is discussed.It was found that the size of the voids apparently increases with the triaxiality of stress.Post-mortem scanning electron microscopy(SEM)was also used to demonstrate this damage mechanism of ductile fracture of Ti5321.展开更多
A new direction toward the future of orthopedic implants is to combine biodegradable Mg alloys with permanent Ti to produce selectively biodegradable hybrid joints for advanced tissue engineering.However,the strong ga...A new direction toward the future of orthopedic implants is to combine biodegradable Mg alloys with permanent Ti to produce selectively biodegradable hybrid joints for advanced tissue engineering.However,the strong galvanic corrosion between Mg and Ti is a major issue to be considered.This work aims to explore plasma electrolytic oxidation(PEO)as a single-step coating treatment to allow for an acceptable degradation behavior of MgTi hybrid systems.To this end,MgTi hybrid joints were produced through the heat treatment of Mg-0.6Ca and commercially pure Ti specimens at 640°C for 8 h.A single-step PEO treatment was then employed to create a protective layer on the surface of hybrid couples.Even though the scanning electron microscopy(SEM)images showed only a porosity of 6%and 12%within the PEO layers on single Mg and MgTi couples,3D investigation of the synchrotron-based microtomography data demonstrated a porosity of 18%and 30%with a considerable number of interconnected pores.According to the electrochemical impedance spectroscopy measurements,the impedance modulus at all frequencies on coated MgTi coupled specimens was lower than that on the coated single Mg-0.6Ca and pure Ti.However,the application of PEO treatment significantly decreased the strong galvanic degradation of Mg-0.6Ca in contact with Ti.The results of hydrogen evolution tests revealed that PEO-treated MgTi couples showed a similar degradation behavior as the single alloy during the first day of immersion.展开更多
Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China. Several species possess a conspicuous horn on their head, which has been suggested as a constructive troglomorphic trait but lacks substan...Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China. Several species possess a conspicuous horn on their head, which has been suggested as a constructive troglomorphic trait but lacks substantial evidence. We used non- invasive, high spatial resolution synchrotron X-ray microtomography to investigate the three-dimensional （3D） morphology of the horn of Sinocyclocheilus hyalinus, one of eight such troglobiotic species. 3D renderings demonstrated the osteological components, which were comprised of a rear wall comprised of the supraoccipital bone, a remaining frontal wall with numerous fenestrae, and the bottom continuous with the parietal and epiotic. A horn cavity occurred within the horn. The fenestrae in the frontal wall were continuous in the horn cavity and showed elaborate channeling, and were, connected to the cranial cavity by soft tissue. We tentatively called this configuration the ＂otocornual connection＂ due to its anatomic and putative functional similarity to the otolateralic connection in clupeids and loricariids, which provide an indirect pathway to enhance perception of underwater sound signals. This study provides a functional morphology context for further histological and physiological investigations of such horn structures in Sinocyclocheilus cavefish, and we suggest that the horn might enhance acoustic perception to compensate for visual loss in subterranean life, which warrants future physiological examination as lab-reared S. hyalinus become available.展开更多
Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in el...Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting(MC-ESR)process.A transient 2 D numerical model was also built to verify the experimental results and proposed mechanisms.The number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF,while remained almost the same in electrode matrix and MZ.The inclusions in LMF migrated from edge to mid region of LMF,accompanied with removal process.In addition,the kinetic conditions for inclusion migrating to LMF/slag interface(LSI)were enhanced during MC-ESR process,thereby improving the inclusion removal efficiency in LMF.This work highlights the 3 D characterization and motion/removal mechanisms of inclusions in electrode tip,as well as sheds new light on preparing high purity materials.展开更多
The most significant problem of maize grain mechanical harvesting quality in China at present is the high grain breakage rate(BR).BR is often the key characteristic that is measured to select hybrids desirable for mec...The most significant problem of maize grain mechanical harvesting quality in China at present is the high grain breakage rate(BR).BR is often the key characteristic that is measured to select hybrids desirable for mechanical grain harvesting.However,conventional BR evaluation and measurement methods have challenges and limitations.Microstructural crack parameters evaluation of maize kernel is of great importance to BR.In this connection,X-ray computed microtomography(μ-CT)has proven to be a quite useful method for the assessment of microstructure,as it provides important microstructural parameters,such as object volume,surface,surface/volume ratio,number of closed pores,and others.X-ray computed microtomography is a non-destructive technique that enables the reuse of samples already measured and also yields bidimensional(2D)cross-sectional images of the sample as well as volume rendering.In this paper,six different maize hybrid genotypes are used as materials,and the BR of the maize kernels of each variety is tested in the field mechanical grain harvesting,and the BR is used as an index for evaluating the breakage resistance of the variety.The crack characteristic parameters of kernel were detected by X-ray micro-computed tomography,and the relationship between the BR and the kernel crack characteristics was analyzed by stepwise regression analysis.Establishing a relationship between crack characteristic parameters and BR of maize is vital for judging breakage resistance.The results of stepwise multiple linear regression(MLR)showed that the crack characteristics of the object surface,number of closed pores,surface of closed pores,and closed porosity percent were significantly correlated to the BR of field mechanical grain harvesting,with the standard partial regression coefficients of–0.998,–0.988,–0.999,and–0.998,respectively.The R2 of this model was 0.999.Results validation showed that the Stepwise MLR Model could well predict the BR of maize based on these four variables.展开更多
The aim of this paper is to report the results of experiments carried out on Al-Cu alloys with different Cu contents,studying the microstructure evolution during holding in the semi-solid state.The 3-D microstructure ...The aim of this paper is to report the results of experiments carried out on Al-Cu alloys with different Cu contents,studying the microstructure evolution during holding in the semi-solid state.The 3-D microstructure was observed by in situ X-ray microtomography carried out at ESRF Grenoble,France.The variation of the solid-liquid interface area per unit volume during holding was determined.In addition,local observations show that two coarsening mechanisms of the solid particles occur simultaneously:dissolution of small particles to the benefit of larger ones by an Ostwald-type mechanism and the growth of necks between solid particles due to coalescence.These observations confirm that in situ X-ray tomography is a very powerful tool to study the microstructure evolution in the semi-solid state and the influencing mechanisms in real-time.展开更多
In recent years,bamboo has been widely used in a broad range of applications,a thorough understanding of the structural characteristics of bamboo nodes is essential for better processing and manufacturing of biomimeti...In recent years,bamboo has been widely used in a broad range of applications,a thorough understanding of the structural characteristics of bamboo nodes is essential for better processing and manufacturing of biomimetic materials.This study investigated the complex anatomical structure for the nodes of two bamboo species,Indocalamus latifolius(Keng)McClure and Shibataea chinensis Nakai,using a high-resolution X-ray microtomography(μCT).The results show that the vascular bundle system in the nodal region of I.latifolius and S.chinensis is a net-like structure composed of horizontal and axial vascular bundles.Furthermore,the fiber sheath surrounding metaxylem vessels tended to be shorter in the tangential direction.This structure of bamboo nodes facilitates the tangential and axial transport of moisture and nutrients.The anatomical structure of I.latifolius and S.chinensis nodes has obvious differences,especially in the arrangement of vascular bundles.Vascular bundle frequency was significantly higher in S.chinensis nodes than in I.latifolius nodes.These findings indicate thatμCT is a nondestructive three-dimensional imaging method that can used to examine the anatomical structure of bamboo nodes.展开更多
Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China.Several species possess a conspicuous horn on their head,which has been suggested as a constructive troglomorphic trait but lacks substanti...Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China.Several species possess a conspicuous horn on their head,which has been suggested as a constructive troglomorphic trait but lacks substantial evidence.We used non-invasive,high spatial resolution synchrotron X-ray microtomography to investigate the three-dimensional(3D)morphology of the horn of Sinocyclocheilus hyalinus,one of eight such troglobiotic species.3D renderings demonstrated the osteological components,which were comprised of a rear wall comprised of the supraoccipital bone,a remaining frontal wall with numerous fenestrae,and the bottom continuous with the parietal and epiotic.A horn cavity occurred within the horn.The fenestrae in the frontal wall were continuous in the horn cavity and showed elaborate channeling,and were,connected to the cranial cavity by soft tissue.We tentatively called this configuration the“otocornual connection”due to its anatomic and putative functional similarity to the otolateralic connection in clupeids and loricariids,which provide an indirect pathway to enhance perception of underwater sound signals.This study provides a functional morphology context for further histological and physiological investigations of such horn structures in Sinocyclocheilus cavefish,and we suggest that the horn might enhance acoustic perception to compensate for visual loss in subterranean life,which warrants future physiological examination as lab-reared S.hyalinus become available.展开更多
The use of computed microtomography （p.CT） has revolutionized many areas of research, such as noninvasive, fast and high precision techniques, which allows immediate visualization of internal structures without any ...The use of computed microtomography （p.CT） has revolutionized many areas of research, such as noninvasive, fast and high precision techniques, which allows immediate visualization of internal structures without any risk to the object of study. ~tCT is widely accepted for medical diagnostics, is also important for purposes of zoological research and paleontological. In this work, we used the μCT to investigate the internal structure of bones from mammalian and poultry. We studied the bones of rats and quail. Through microtomography images, we observed that the bones of the poultry have a bony structure in the form of a trellis that is not present in bones of mammals. These trellises bony is an evolutionary adaptation that allowed the bones of the birds to become longer and lighter maintaining its strength. It was also observed that the percentage of the trabecular area in poultry is almost half of that observed in mammals. The results obtained validate the use of μCT as a technique that allows the study of bone structures in small samples, enabling to explore the morphological differences between the bones of those species.展开更多
Direct Laser Sintering (DSL), a technology enabling the production of dense metal components directly from 3D CAD data, was used for the first time to produce a Metal Matrix Composite (MMCp) based on Al-Si-Cu alloy in...Direct Laser Sintering (DSL), a technology enabling the production of dense metal components directly from 3D CAD data, was used for the first time to produce a Metal Matrix Composite (MMCp) based on Al-Si-Cu alloy in view of its application in different fields, in particular for aeronautics. The porosity of the material obtained so was investigated by using optical and electron microscopy and, in particular, X-ray computed microtomography techniques. DSL is a unique technique to produce complex components in an economical way while computed microtomography is a unique technique to evaluate the porosity and pore and cracks distribution in a not destructive way. A near homogeneous distribution of the porosity and pore sizes was observed both comparing different regions of the same specimen and also by comparing different samples obtained by using the same DLS production method. A quantitative analysis of the damage in the composite is also reported.展开更多
This paper studied the thermal physical properties of foundation materials in the molten salt tank of thermal energy storage system after molten salt leakage by Transient plane source experiment and X-ray computed mic...This paper studied the thermal physical properties of foundation materials in the molten salt tank of thermal energy storage system after molten salt leakage by Transient plane source experiment and X-ray computed microtomography simulation methods.The microstructure,thermal properties and pressure resistance with different particle diameters were addressed.The measured heat conductivities from Transient plane source experiment for three cases are 0.49 W/(m·K),0.48 W/(m·K),and 0.51 W/(m·K),and the porosity is 30.1%,30.7%,and 31.2% respectively.The heat conductivity simulating results of three cases are 0.471 W/(m·K),0.482W/(m·K),and 0.513 W/(m·K).The ratio of difference between the results of simulation and Transient plane source measurement is as low as 1.2%,verifying the reliability of experimental and simulation results to a certain degree.Compared with the heat conductivity of 0.097-0.129 W/(m·K) and porosity of 71.6%-78.9% without leaking salt,the porosity is reduced by more than 50% while the heat conductivity increased by 4 to 5 times after molten salt leakage.This significant increase in heat conductivity has a great impact on security operation,structure design,and modeling of the tank foundation for solar power plants.展开更多
Biochar pores in the micrometer range(1-100μm)derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing,such as pelleting.In this study,synchrotron X-ra...Biochar pores in the micrometer range(1-100μm)derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing,such as pelleting.In this study,synchrotron X-ray microtomography was used to investigate the internal pore structure of softwood pellet biochar produced by slow pyrolysis at 550 and 700°C.The microtomographic data sets consisted of 2025 images of 2560×2560 voxels with a voxel side length of 0.87μm.The three-dimensional reconstructions revealed that pelleting and pyrolysis significantly altered the pore structures of the wood feedstock,creating a network of connected pores between fragments that resembled the wood morphology.While higher pyrolysis temperature increased the specific surface area(as determined by BET nitrogen adsorption),it did not affect the total observed porosity.Multifractal analysis was applied to assess the characteristics of the frequency distribution of pores along each of the three dimensions of reconstructed images of five softwood pellet biochar samples.The resulting singular-ity and Rényi spectra(generalized dimensions)indicated that the distribution of porosity had monofractal scaling behavior,was homogeneous within the analyzed volumes and consistent between replicate samples.Moreover,the pore distributions were isotropic(direction-independent),which is in strong contrast with the anisotropic pore structure of wood.As pores at the scale analyzed in this study are relevant,for example,for the supply of plant accessible water and habitable space for microorganisms,our findings combined with the ability to reproduce biochar with such pore distribution offer substantial advantages in various biochar applications.展开更多
Objective of this work was to develop a novel method for characterizing real 3D shapes of particles smaller than 20μm by X-ray microtomography(X-RMT).Multidimensional separation of heterogenous solids through agglome...Objective of this work was to develop a novel method for characterizing real 3D shapes of particles smaller than 20μm by X-ray microtomography(X-RMT).Multidimensional separation of heterogenous solids through agglomeration in suspension will improve recycling processes as the particle shape and the agglomerate size are used for shape-selective separation.In the present paper we discuss the fundamentals of X-ray tomography and the experimental setup for selective spherical agglomeration in suspension.A specific preparation method of the particulate sample for X-RMT followed by 3D image processing,are essential for the shape analysis expressed as sphericity.We also discuss the limitation of this method due to the so-called Partial Volume Effect and particle clusters in the order of magnitude of X-RMT resolution.As proof of concept,we used a mixture of graphite platelets and spheronized graphite particles for a shape selective-agglomeration in suspension.The remaining fines were analyzed and showed more platelets than in the mixture.This indicates that spheronized particles are preferably bound in the agglomerates.These findings show that,based on the discussed sample preparation and a 3D image analysis in connection with X-RMT,particle shapes of micronized particles can be discriminated.展开更多
For accurate description of particle structure,single particle properties are required so that the properties of interest can be expressed as distributed parameters.X-Ray microtomography of the powder bed with subsequ...For accurate description of particle structure,single particle properties are required so that the properties of interest can be expressed as distributed parameters.X-Ray microtomography of the powder bed with subsequent particle separation can be used for this purpose.In this paper,a new algorithm for X-Ray microtomography images of spray dried particles was introduced since standard methods tend to fail if the particle size distribution is broad.The algorithm is based on 2D shape classification and subsequent 3D reconstitution of the particle using only a shape classifier as free parameter.The proposed algorithm was validated successfully.Using the algorithm,single particle porosities were obtained,which ranged from 0 to 70%.Prerequisites for the application of the algorithm are that a shape classifier can be set and that the 3D shape is regular.展开更多
OBJECTIVE: To investigate the effects of Tongxinluo superfine powder on cardiac function, infarct size and the number of myocardial capillaries in a rabbit model of acute myocardial infarction.METHODS: A total of 32 N...OBJECTIVE: To investigate the effects of Tongxinluo superfine powder on cardiac function, infarct size and the number of myocardial capillaries in a rabbit model of acute myocardial infarction.METHODS: A total of 32 New Zealand white rabbits were randomly divided into four groups: sham operation group, model group, treatment group,and pre-treatment, the experiment of pre-treatment group was performed 6 weeks early than the treat) group,The four groups use a unified modeling technique. An acute myocardial infarction model was established through external application of70% ferric chloride on the coronary artery. After 7 d,electrocardiogram, ultrasonography of cardiac function, micro-computed tomography, pathology and other data were collected.RESULTS: In the treatment and pre-treatment groups, ejection fraction, left ventricular short axis shortening rate, left ventricular end-systolic diameter and cardiac output significantly improved, the number of capillaries significantly increased, and infarct size significantly decreased. In addition, the results suggest that the value of intra-ventricular pressure and the situation of electrocardiogram also changed to different degrees with the increasing of treatment of cycle.CONCLUSION: Tongxinluo superfine powder can protect the myocardium, improve the blood supply of the myocardium and reduce the degree of myocardial injury, during acute stage of myocardial infarction.展开更多
Pyrogenic organic matter(PyOM)is formed during wildfires and prescribed burnings or produced intentionally in the form of biochar for soil amendment purposes.It is attracting a growing scientific and practical interes...Pyrogenic organic matter(PyOM)is formed during wildfires and prescribed burnings or produced intentionally in the form of biochar for soil amendment purposes.It is attracting a growing scientific and practical interest due to its important role in the global carbon cycle and agronomic applications as a soil enhancer.Most of the studies on the physicochemical properties of PyOM have been conducted using fresh biochars even though the characteristics of PyOM are expected to alter due to aging processes in soil environment.In this paper,we report the results of a study that utilized X-ray microtomography and elemental analysis to investigate the chemical and structural changes in the PyOM formed during prescribed burning events and aged thereafter for 1–71 years in a boreal forest soil.Our results indicate that changes in elemental composition occurred at decadal timescales,and an apparent steady state was reached ca.30 years after PyOM formation and exposure to the environment.At such timescales,PyOM was able to retain its porous structure originating from the cellular structure of the initial wood tissues.However,structural analysis revealed several effects of aging on the pore structure,such as the formation of surface coating layers,pore fillings,and fractures.These changes may alter pore size distribution and accessibility of the pores and further alter the influence of PyOM on soil functions,such as the transfer and retention of water and nutrients in PyOM pores.展开更多
The mechanical behaviour of trabecular bone is dependent on both the properties of individual trabeculae as well as their three-dimensional arrangement in space. In this study, nanoindentation was used to determine tr...The mechanical behaviour of trabecular bone is dependent on both the properties of individual trabeculae as well as their three-dimensional arrangement in space. In this study, nanoindentation was used to determine trabecular stiffness of bovine bone, both dehydrated and rehydrated. Values of 18.3 GPa and 14.3 GPa were obtained for dehydrated and rehydrated trabeculae respectively. These values were then used for finite element analysis where the mesh was generated directly from an X-ray microtomography dataset. The relationship between intrinsic tissue properties and apparent stiffness was explored. Moreover, the important role of collagen in bone micromechanics was demonstrated by complementing the study with Raman spectroscopy.展开更多
The article is to study the development of computer-aided design of X-ray microtomography—the device for investigating the structure and construction of three-dimensional images of organic and inorganic objects on th...The article is to study the development of computer-aided design of X-ray microtomography—the device for investigating the structure and construction of three-dimensional images of organic and inorganic objects on the basis of shadow projections. This article provides basic information regarding CAD of X-ray microtomography and a scheme consisting of three levels. The article also shows basic relations of X-ray computed tomography, the generalized scheme of an X-ray microtomographic scanner. The methods of X-ray imaging of the spatial microstructure and morphometry of materials are described. The main characteristics of an X-ray microtomographic scanner, the X-ray source, X-ray optical elements and mechanical components of the positioning system are shown. The block scheme and software functional scheme for intelligent neural network system of analysis of the internal microstructure of objects are presented. The method of choice of design parameters of CAD of X-ray microtomography aims at improving the quality of design and reducing costs of it. It is supposed to reduce the design time and eliminate the growing number of engineers involved in development and construction of X-ray microtomographic scanners.展开更多
A wetland with attractive plants hosting birds and other wildlife is an esthetically pleasing prospect that is gaining popularity as a way of stabilizing or remediating metalcontaminated soils and sediment（Weber and ...A wetland with attractive plants hosting birds and other wildlife is an esthetically pleasing prospect that is gaining popularity as a way of stabilizing or remediating metalcontaminated soils and sediment（Weber and Gagnon,2014;展开更多
The tree frog is a prominent amphibian among terrestrial vertebrates known for its ability to adhere to various surfaces through the capillary forces of water in the microchannels between micropillars on its disc-shap...The tree frog is a prominent amphibian among terrestrial vertebrates known for its ability to adhere to various surfaces through the capillary forces of water in the microchannels between micropillars on its disc-shaped toe pads,a phenomenon known as wet adhesion.However,the secretion pattern of mucus on the attachment surface of living tree frog toe pads and the distribution of active mucus pores(AMPs)have not yet been fully elucidated.In this study,we utilized synchrotron X-ray micro-computed tomography and interference reflection microscopy to obtain the spatial distribution of the entire population of ventral mucus glands on the toe pads of living tree frogs and the real-time mucus secretion patterns from the ventral mucus pores on the contact surface under different environmental conditions.We observed that the number and secretion frequency of AMPs on the toe pad are regulated according to environmental conditions.Such dynamic mucus secretion on the tree frog’s toe pad could contribute to the understanding of capillary force regulation for wet adhesion and the development of adhesive surfaces by mimicking the mucus-secreting toe pad.展开更多
基金supported by the China Postdoctoral Science Foundation(No.2022M720399).
文摘In order to investigate the damage tolerance of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe(Ti5321)alloy with bimodal microstructure using void growth quantification and micromechanical modeling,in situ tensile testing was performed during X-ray microtomography experiments.Compared with investigations of surface voids by traditional two-dimensional(2D)methods involving post-mortem characterization,three-dimensional(3D)information on void evolution inside optically opaque samples obtained through X-ray microtomography is essential.The Rice and Tracey model and Huang model were applied to predict void growth and show good agreement with experimental data using calibration of the damage parameterα.The void growth kinetics of Ti5321 with bimodal microstructure was analyzed by comparing theαvalue with that of Ti64 for different microstructure morphologies.The damage mechanism of ductile fracture of Ti5321 with bimodal microstructure is discussed.It was found that the size of the voids apparently increases with the triaxiality of stress.Post-mortem scanning electron microscopy(SEM)was also used to demonstrate this damage mechanism of ductile fracture of Ti5321.
基金support from the Alexander von Humboldt Foundation.We thank DESY(Hamburg,Germany)for granting the proposal I20221296support at the PETRA III P05 end-station.
文摘A new direction toward the future of orthopedic implants is to combine biodegradable Mg alloys with permanent Ti to produce selectively biodegradable hybrid joints for advanced tissue engineering.However,the strong galvanic corrosion between Mg and Ti is a major issue to be considered.This work aims to explore plasma electrolytic oxidation(PEO)as a single-step coating treatment to allow for an acceptable degradation behavior of MgTi hybrid systems.To this end,MgTi hybrid joints were produced through the heat treatment of Mg-0.6Ca and commercially pure Ti specimens at 640°C for 8 h.A single-step PEO treatment was then employed to create a protective layer on the surface of hybrid couples.Even though the scanning electron microscopy(SEM)images showed only a porosity of 6%and 12%within the PEO layers on single Mg and MgTi couples,3D investigation of the synchrotron-based microtomography data demonstrated a porosity of 18%and 30%with a considerable number of interconnected pores.According to the electrochemical impedance spectroscopy measurements,the impedance modulus at all frequencies on coated MgTi coupled specimens was lower than that on the coated single Mg-0.6Ca and pure Ti.However,the application of PEO treatment significantly decreased the strong galvanic degradation of Mg-0.6Ca in contact with Ti.The results of hydrogen evolution tests revealed that PEO-treated MgTi couples showed a similar degradation behavior as the single alloy during the first day of immersion.
基金supported by the fund of State Key Laboratory of Genetic Resources and Evolution(GREKF13-06)
文摘Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China. Several species possess a conspicuous horn on their head, which has been suggested as a constructive troglomorphic trait but lacks substantial evidence. We used non- invasive, high spatial resolution synchrotron X-ray microtomography to investigate the three-dimensional （3D） morphology of the horn of Sinocyclocheilus hyalinus, one of eight such troglobiotic species. 3D renderings demonstrated the osteological components, which were comprised of a rear wall comprised of the supraoccipital bone, a remaining frontal wall with numerous fenestrae, and the bottom continuous with the parietal and epiotic. A horn cavity occurred within the horn. The fenestrae in the frontal wall were continuous in the horn cavity and showed elaborate channeling, and were, connected to the cranial cavity by soft tissue. We tentatively called this configuration the ＂otocornual connection＂ due to its anatomic and putative functional similarity to the otolateralic connection in clupeids and loricariids, which provide an indirect pathway to enhance perception of underwater sound signals. This study provides a functional morphology context for further histological and physiological investigations of such horn structures in Sinocyclocheilus cavefish, and we suggest that the horn might enhance acoustic perception to compensate for visual loss in subterranean life, which warrants future physiological examination as lab-reared S. hyalinus become available.
基金the financial support of the National Key Research and Development Program of China(Nos.2016YFB0300401,2018YFF0109404 and 2016YFB0301401)the National Natural Science Foundation of China(Nos.U1860202,U1732276,50134010,51704193,51904184 and 52004156)+1 种基金the Science and Technology Commission of Shanghai Municipality(Nos.13JC14025000 and 15520711000)the China Postdoctoral Science Foundation(No.2020M671072)。
文摘Detailed three-dimensional(3 D)microtomography characterizations of inclusions in electrode matrix,mushy zone(MZ)and liquid melt film(LMF)were performed to elucidate the motion and removal behavior of inclusions in electrode tip during magnetically controlled electroslag remelting(MC-ESR)process.A transient 2 D numerical model was also built to verify the experimental results and proposed mechanisms.The number and size of inclusions exhibited an obvious increasing trend from edge to mid region in LMF,while remained almost the same in electrode matrix and MZ.The inclusions in LMF migrated from edge to mid region of LMF,accompanied with removal process.In addition,the kinetic conditions for inclusion migrating to LMF/slag interface(LSI)were enhanced during MC-ESR process,thereby improving the inclusion removal efficiency in LMF.This work highlights the 3 D characterization and motion/removal mechanisms of inclusions in electrode tip,as well as sheds new light on preparing high purity materials.
基金This work was supported by the National Key R&D Program of China(2016YFD0300110,2016YFD0300101)the earmarked fund for China Agriculture Research System(CARS-02-25)the Agricultural Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences。
文摘The most significant problem of maize grain mechanical harvesting quality in China at present is the high grain breakage rate(BR).BR is often the key characteristic that is measured to select hybrids desirable for mechanical grain harvesting.However,conventional BR evaluation and measurement methods have challenges and limitations.Microstructural crack parameters evaluation of maize kernel is of great importance to BR.In this connection,X-ray computed microtomography(μ-CT)has proven to be a quite useful method for the assessment of microstructure,as it provides important microstructural parameters,such as object volume,surface,surface/volume ratio,number of closed pores,and others.X-ray computed microtomography is a non-destructive technique that enables the reuse of samples already measured and also yields bidimensional(2D)cross-sectional images of the sample as well as volume rendering.In this paper,six different maize hybrid genotypes are used as materials,and the BR of the maize kernels of each variety is tested in the field mechanical grain harvesting,and the BR is used as an index for evaluating the breakage resistance of the variety.The crack characteristic parameters of kernel were detected by X-ray micro-computed tomography,and the relationship between the BR and the kernel crack characteristics was analyzed by stepwise regression analysis.Establishing a relationship between crack characteristic parameters and BR of maize is vital for judging breakage resistance.The results of stepwise multiple linear regression(MLR)showed that the crack characteristics of the object surface,number of closed pores,surface of closed pores,and closed porosity percent were significantly correlated to the BR of field mechanical grain harvesting,with the standard partial regression coefficients of–0.998,–0.988,–0.999,and–0.998,respectively.The R2 of this model was 0.999.Results validation showed that the Stepwise MLR Model could well predict the BR of maize based on these four variables.
基金project ANR-05-BLAN-0286-01 TOMOSOLIDAL supported by the French Agence Nationale de la Recherche,which is gratefully acknowledged
文摘The aim of this paper is to report the results of experiments carried out on Al-Cu alloys with different Cu contents,studying the microstructure evolution during holding in the semi-solid state.The 3-D microstructure was observed by in situ X-ray microtomography carried out at ESRF Grenoble,France.The variation of the solid-liquid interface area per unit volume during holding was determined.In addition,local observations show that two coarsening mechanisms of the solid particles occur simultaneously:dissolution of small particles to the benefit of larger ones by an Ostwald-type mechanism and the growth of necks between solid particles due to coalescence.These observations confirm that in situ X-ray tomography is a very powerful tool to study the microstructure evolution in the semi-solid state and the influencing mechanisms in real-time.
基金This research was funded by the Nature Science Foundation of China(Grant No.31670565)the National Key Research&Development Program(No.2016YFD0600904).
文摘In recent years,bamboo has been widely used in a broad range of applications,a thorough understanding of the structural characteristics of bamboo nodes is essential for better processing and manufacturing of biomimetic materials.This study investigated the complex anatomical structure for the nodes of two bamboo species,Indocalamus latifolius(Keng)McClure and Shibataea chinensis Nakai,using a high-resolution X-ray microtomography(μCT).The results show that the vascular bundle system in the nodal region of I.latifolius and S.chinensis is a net-like structure composed of horizontal and axial vascular bundles.Furthermore,the fiber sheath surrounding metaxylem vessels tended to be shorter in the tangential direction.This structure of bamboo nodes facilitates the tangential and axial transport of moisture and nutrients.The anatomical structure of I.latifolius and S.chinensis nodes has obvious differences,especially in the arrangement of vascular bundles.Vascular bundle frequency was significantly higher in S.chinensis nodes than in I.latifolius nodes.These findings indicate thatμCT is a nondestructive three-dimensional imaging method that can used to examine the anatomical structure of bamboo nodes.
基金This work was partially supported by the fund of State Key Laboratory of Genetic Resources and Evolution(GREKF13-06)。
文摘Sinocyclocheilus is a cave-dwelling cyprinid genus endemic to southwest China.Several species possess a conspicuous horn on their head,which has been suggested as a constructive troglomorphic trait but lacks substantial evidence.We used non-invasive,high spatial resolution synchrotron X-ray microtomography to investigate the three-dimensional(3D)morphology of the horn of Sinocyclocheilus hyalinus,one of eight such troglobiotic species.3D renderings demonstrated the osteological components,which were comprised of a rear wall comprised of the supraoccipital bone,a remaining frontal wall with numerous fenestrae,and the bottom continuous with the parietal and epiotic.A horn cavity occurred within the horn.The fenestrae in the frontal wall were continuous in the horn cavity and showed elaborate channeling,and were,connected to the cranial cavity by soft tissue.We tentatively called this configuration the“otocornual connection”due to its anatomic and putative functional similarity to the otolateralic connection in clupeids and loricariids,which provide an indirect pathway to enhance perception of underwater sound signals.This study provides a functional morphology context for further histological and physiological investigations of such horn structures in Sinocyclocheilus cavefish,and we suggest that the horn might enhance acoustic perception to compensate for visual loss in subterranean life,which warrants future physiological examination as lab-reared S.hyalinus become available.
文摘The use of computed microtomography （p.CT） has revolutionized many areas of research, such as noninvasive, fast and high precision techniques, which allows immediate visualization of internal structures without any risk to the object of study. ~tCT is widely accepted for medical diagnostics, is also important for purposes of zoological research and paleontological. In this work, we used the μCT to investigate the internal structure of bones from mammalian and poultry. We studied the bones of rats and quail. Through microtomography images, we observed that the bones of the poultry have a bony structure in the form of a trellis that is not present in bones of mammals. These trellises bony is an evolutionary adaptation that allowed the bones of the birds to become longer and lighter maintaining its strength. It was also observed that the percentage of the trabecular area in poultry is almost half of that observed in mammals. The results obtained validate the use of μCT as a technique that allows the study of bone structures in small samples, enabling to explore the morphological differences between the bones of those species.
文摘Direct Laser Sintering (DSL), a technology enabling the production of dense metal components directly from 3D CAD data, was used for the first time to produce a Metal Matrix Composite (MMCp) based on Al-Si-Cu alloy in view of its application in different fields, in particular for aeronautics. The porosity of the material obtained so was investigated by using optical and electron microscopy and, in particular, X-ray computed microtomography techniques. DSL is a unique technique to produce complex components in an economical way while computed microtomography is a unique technique to evaluate the porosity and pore and cracks distribution in a not destructive way. A near homogeneous distribution of the porosity and pore sizes was observed both comparing different regions of the same specimen and also by comparing different samples obtained by using the same DLS production method. A quantitative analysis of the damage in the composite is also reported.
基金supported by the National Natural Science Foundation of China (52036008)。
文摘This paper studied the thermal physical properties of foundation materials in the molten salt tank of thermal energy storage system after molten salt leakage by Transient plane source experiment and X-ray computed microtomography simulation methods.The microstructure,thermal properties and pressure resistance with different particle diameters were addressed.The measured heat conductivities from Transient plane source experiment for three cases are 0.49 W/(m·K),0.48 W/(m·K),and 0.51 W/(m·K),and the porosity is 30.1%,30.7%,and 31.2% respectively.The heat conductivity simulating results of three cases are 0.471 W/(m·K),0.482W/(m·K),and 0.513 W/(m·K).The ratio of difference between the results of simulation and Transient plane source measurement is as low as 1.2%,verifying the reliability of experimental and simulation results to a certain degree.Compared with the heat conductivity of 0.097-0.129 W/(m·K) and porosity of 71.6%-78.9% without leaking salt,the porosity is reduced by more than 50% while the heat conductivity increased by 4 to 5 times after molten salt leakage.This significant increase in heat conductivity has a great impact on security operation,structure design,and modeling of the tank foundation for solar power plants.
基金The research leading to these results received funding from BiofuelNet Canada(funded by the Canadian Networks of Centers of Excellence)and the Leverhulme Trust.
文摘Biochar pores in the micrometer range(1-100μm)derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing,such as pelleting.In this study,synchrotron X-ray microtomography was used to investigate the internal pore structure of softwood pellet biochar produced by slow pyrolysis at 550 and 700°C.The microtomographic data sets consisted of 2025 images of 2560×2560 voxels with a voxel side length of 0.87μm.The three-dimensional reconstructions revealed that pelleting and pyrolysis significantly altered the pore structures of the wood feedstock,creating a network of connected pores between fragments that resembled the wood morphology.While higher pyrolysis temperature increased the specific surface area(as determined by BET nitrogen adsorption),it did not affect the total observed porosity.Multifractal analysis was applied to assess the characteristics of the frequency distribution of pores along each of the three dimensions of reconstructed images of five softwood pellet biochar samples.The resulting singular-ity and Rényi spectra(generalized dimensions)indicated that the distribution of porosity had monofractal scaling behavior,was homogeneous within the analyzed volumes and consistent between replicate samples.Moreover,the pore distributions were isotropic(direction-independent),which is in strong contrast with the anisotropic pore structure of wood.As pores at the scale analyzed in this study are relevant,for example,for the supply of plant accessible water and habitable space for microorganisms,our findings combined with the ability to reproduce biochar with such pore distribution offer substantial advantages in various biochar applications.
基金financially supported by the German Research Foundation(DFG),Priority Program 2045(SPP2045).
文摘Objective of this work was to develop a novel method for characterizing real 3D shapes of particles smaller than 20μm by X-ray microtomography(X-RMT).Multidimensional separation of heterogenous solids through agglomeration in suspension will improve recycling processes as the particle shape and the agglomerate size are used for shape-selective separation.In the present paper we discuss the fundamentals of X-ray tomography and the experimental setup for selective spherical agglomeration in suspension.A specific preparation method of the particulate sample for X-RMT followed by 3D image processing,are essential for the shape analysis expressed as sphericity.We also discuss the limitation of this method due to the so-called Partial Volume Effect and particle clusters in the order of magnitude of X-RMT resolution.As proof of concept,we used a mixture of graphite platelets and spheronized graphite particles for a shape selective-agglomeration in suspension.The remaining fines were analyzed and showed more platelets than in the mixture.This indicates that spheronized particles are preferably bound in the agglomerates.These findings show that,based on the discussed sample preparation and a 3D image analysis in connection with X-RMT,particle shapes of micronized particles can be discriminated.
文摘For accurate description of particle structure,single particle properties are required so that the properties of interest can be expressed as distributed parameters.X-Ray microtomography of the powder bed with subsequent particle separation can be used for this purpose.In this paper,a new algorithm for X-Ray microtomography images of spray dried particles was introduced since standard methods tend to fail if the particle size distribution is broad.The algorithm is based on 2D shape classification and subsequent 3D reconstitution of the particle using only a shape classifier as free parameter.The proposed algorithm was validated successfully.Using the algorithm,single particle porosities were obtained,which ranged from 0 to 70%.Prerequisites for the application of the algorithm are that a shape classifier can be set and that the 3D shape is regular.
文摘OBJECTIVE: To investigate the effects of Tongxinluo superfine powder on cardiac function, infarct size and the number of myocardial capillaries in a rabbit model of acute myocardial infarction.METHODS: A total of 32 New Zealand white rabbits were randomly divided into four groups: sham operation group, model group, treatment group,and pre-treatment, the experiment of pre-treatment group was performed 6 weeks early than the treat) group,The four groups use a unified modeling technique. An acute myocardial infarction model was established through external application of70% ferric chloride on the coronary artery. After 7 d,electrocardiogram, ultrasonography of cardiac function, micro-computed tomography, pathology and other data were collected.RESULTS: In the treatment and pre-treatment groups, ejection fraction, left ventricular short axis shortening rate, left ventricular end-systolic diameter and cardiac output significantly improved, the number of capillaries significantly increased, and infarct size significantly decreased. In addition, the results suggest that the value of intra-ventricular pressure and the situation of electrocardiogram also changed to different degrees with the increasing of treatment of cycle.CONCLUSION: Tongxinluo superfine powder can protect the myocardium, improve the blood supply of the myocardium and reduce the degree of myocardial injury, during acute stage of myocardial infarction.
基金financially supported by the Ministry of Education and Culture,Finland,under project Carbon 4.0:AnalysisUtilization of Biological Data in Complex Carbon Ecosystems for JH and HL and project Bioproduct and Clean Bioeconomy—RDI FlagShip in Xamk for RK and KR。
文摘Pyrogenic organic matter(PyOM)is formed during wildfires and prescribed burnings or produced intentionally in the form of biochar for soil amendment purposes.It is attracting a growing scientific and practical interest due to its important role in the global carbon cycle and agronomic applications as a soil enhancer.Most of the studies on the physicochemical properties of PyOM have been conducted using fresh biochars even though the characteristics of PyOM are expected to alter due to aging processes in soil environment.In this paper,we report the results of a study that utilized X-ray microtomography and elemental analysis to investigate the chemical and structural changes in the PyOM formed during prescribed burning events and aged thereafter for 1–71 years in a boreal forest soil.Our results indicate that changes in elemental composition occurred at decadal timescales,and an apparent steady state was reached ca.30 years after PyOM formation and exposure to the environment.At such timescales,PyOM was able to retain its porous structure originating from the cellular structure of the initial wood tissues.However,structural analysis revealed several effects of aging on the pore structure,such as the formation of surface coating layers,pore fillings,and fractures.These changes may alter pore size distribution and accessibility of the pores and further alter the influence of PyOM on soil functions,such as the transfer and retention of water and nutrients in PyOM pores.
文摘The mechanical behaviour of trabecular bone is dependent on both the properties of individual trabeculae as well as their three-dimensional arrangement in space. In this study, nanoindentation was used to determine trabecular stiffness of bovine bone, both dehydrated and rehydrated. Values of 18.3 GPa and 14.3 GPa were obtained for dehydrated and rehydrated trabeculae respectively. These values were then used for finite element analysis where the mesh was generated directly from an X-ray microtomography dataset. The relationship between intrinsic tissue properties and apparent stiffness was explored. Moreover, the important role of collagen in bone micromechanics was demonstrated by complementing the study with Raman spectroscopy.
文摘The article is to study the development of computer-aided design of X-ray microtomography—the device for investigating the structure and construction of three-dimensional images of organic and inorganic objects on the basis of shadow projections. This article provides basic information regarding CAD of X-ray microtomography and a scheme consisting of three levels. The article also shows basic relations of X-ray computed tomography, the generalized scheme of an X-ray microtomographic scanner. The methods of X-ray imaging of the spatial microstructure and morphometry of materials are described. The main characteristics of an X-ray microtomographic scanner, the X-ray source, X-ray optical elements and mechanical components of the positioning system are shown. The block scheme and software functional scheme for intelligent neural network system of analysis of the internal microstructure of objects are presented. The method of choice of design parameters of CAD of X-ray microtomography aims at improving the quality of design and reducing costs of it. It is supposed to reduce the design time and eliminate the growing number of engineers involved in development and construction of X-ray microtomographic scanners.
文摘A wetland with attractive plants hosting birds and other wildlife is an esthetically pleasing prospect that is gaining popularity as a way of stabilizing or remediating metalcontaminated soils and sediment（Weber and Gagnon,2014;
基金supported by a National Research Foundation of Korea grant funded by the Korean government(MSIT)(Grant Nos.2022R1A2C1007366 and 2021R1A2C1008787).
文摘The tree frog is a prominent amphibian among terrestrial vertebrates known for its ability to adhere to various surfaces through the capillary forces of water in the microchannels between micropillars on its disc-shaped toe pads,a phenomenon known as wet adhesion.However,the secretion pattern of mucus on the attachment surface of living tree frog toe pads and the distribution of active mucus pores(AMPs)have not yet been fully elucidated.In this study,we utilized synchrotron X-ray micro-computed tomography and interference reflection microscopy to obtain the spatial distribution of the entire population of ventral mucus glands on the toe pads of living tree frogs and the real-time mucus secretion patterns from the ventral mucus pores on the contact surface under different environmental conditions.We observed that the number and secretion frequency of AMPs on the toe pad are regulated according to environmental conditions.Such dynamic mucus secretion on the tree frog’s toe pad could contribute to the understanding of capillary force regulation for wet adhesion and the development of adhesive surfaces by mimicking the mucus-secreting toe pad.
