The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the orig...The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the originally assigned pages(2595-2614),we will need to publish an erratum to correct the article and restore the original page range.The original article has been corrected.展开更多
This comprehensive study investigates the formation and evolution of intermetallic compounds during the solidification process of magnesium alloys using advanced micro X-ray computed tomography.By analyzing both commo...This comprehensive study investigates the formation and evolution of intermetallic compounds during the solidification process of magnesium alloys using advanced micro X-ray computed tomography.By analyzing both common industrial Mg-Al-Zn alloys and a novel rare earth-containing Mg-Ni-Gd-Y alloy,we aim to characterize the nucleation,growth,and distribution of Al-Mn and eutectic intermetallics across various stages of solidification.The non destructive imaging technique employed in this research provides high-resolution,three-dimensional insights into the microstructural development,allowing for a detailed examination of the morphology,spatial arrangement,and interconnectivity of intermetallic phases.This approach overcomes limitations of traditional two-dimensional metallographic methods,offering a more comprehensive understanding of the complex three-dimensional structures formed during solidification.展开更多
According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing ...According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.展开更多
Current research on localized raceway defects of angular contact ball bearings(ACBB)mainly focuses on assuming that localized raceway defects are cube-shaped defects characterized using a half-sine displacement excita...Current research on localized raceway defects of angular contact ball bearings(ACBB)mainly focuses on assuming that localized raceway defects are cube-shaped defects characterized using a half-sine displacement excitation function.However,the assumption of a cube-shaped defect cannot accurately reflect the morphological characteristics of a localized raceway defect,and the half-sine displacement excitation function cannot be used to accurately describe the relationship between the geometric positions of rolling element and raceway in the region of localized raceway defects.In this study,a comprehensive dynamic model of an ACBB considering a three-dimensional localized raceway defect is established based on the nonlinear Hertz contact theory in conjunction with the outer raceway control theory using the improved Newton–Raphson iteration method.Three localized raceway defect distribution types,namely symmetric,offset,and deflection distributions,are considered.The established model is verified by comparing the results of the proposed model with those of existing literature.The dynamic characteristics of the ACBB were analyzed by investigating the effects of the geometrical size and distribution types on the time-varying contact angles,contact forces,and diagonal stiffness of the ACBB.The investigation results show that the appearance of localized raceway defect leads to the time-varying curves of contact angles,contact forces and diagonal stiffness havingΛ-and V-shaped mutations in some time intervals;The variation tendencies of theΛ-and V-shaped mutations are significant with the increase in defect radial depth H,defect axial width a and angular distanceθ_b.The increase in defect eccentric distance L is beneficial to the rolling elements disengaging from the defect area and it can weaken the influence of localized raceway defect on the time-varying contact and stiffness characteristics of ACBB.The time-varying contact and stiffness characteristics appear to change significantly when the defect deflection angleα_βincrease toα_γ.The results of this study provide a theoretical basis for the fault diagnosis of localized raceway defects in ACBB.展开更多
Recent advances in bone regeneration have introduced the concept of four-dimensional(4D)scaffolds that can undergo morphological and functional changes in response to external stimuli.While several studies have propos...Recent advances in bone regeneration have introduced the concept of four-dimensional(4D)scaffolds that can undergo morphological and functional changes in response to external stimuli.While several studies have proposed patient-specific designs for defect sites,they often fail to adequately distinguish the advantages of 4D scaffolds over conventional 3D counterparts.This study aimed to investigate the potential benefits of 4D scaffolds in clinically challenging scenarios involving curved defects,where fixation is difficult.We proposed the use of Shape-Memory Polymers(SMPs)as a solution to address critical issues in personalized scaffold fabrication,including dimensional accuracy,measurement error,and manufacturing imprecision.Experimental results demonstrated that the Curved-Layer Fused Deposition Modeling(CLFDM)scaffold,which offers superior conformability to curved defects,achieved significantly higher interfacial contact with the defect area compared to traditional Fused Deposition Modeling(FDM)scaffolds.Specifically,the CLFDM scaffold facilitated bone regeneration of 25.59±4.72 mm^(3),which is more than twice the 9.37±1.36 mm^(3)observed with the 3D FDM scaffold.Furthermore,the 4D CLFDM scaffold achieved 75.38±11.65 mm^(3)of new bone formation after four weeks,approximately three times greater than that of the 3D CLFDM scaffold,regardless of surface micro-roughness.These results underscore that improved geometrical conformity between the scaffold and the defect site enhances cellular infiltration and contributes to more effective bone regeneration.The findings also highlight the promise of 4D scaffolds as a compelling strategy to overcome geometric and dimensional mismatches in the design of patient-specific scaffolds.展开更多
In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomogra...In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.展开更多
The dynamic characteristics of the area of the atrial septal defect（ASD） were evaluated using the technique of real-time three-dimensional echocardiography（RT 3DE）, the potential factors responsible for the dynami...The dynamic characteristics of the area of the atrial septal defect（ASD） were evaluated using the technique of real-time three-dimensional echocardiography（RT 3DE）, the potential factors responsible for the dynamic characteristics of the area of ASD were observed, and the overall and local volume and functions of the patients with ASD were measured. RT 3DE was performed on the 27 normal controls and 28 patients with ASD. Based on the three-dimensional data workstations, the area of ASD was measured at P wave vertex, R wave vertex, T wave starting point, and T wave terminal point and in the T-P section. The right atrial volume in the same time phase of the cardiac cycle and the motion displacement distance of the tricuspid annulus in the corresponding period were measured. The measured value of the area of ASD was analyzed. The changes in the right atrial volume and the motion displacement distance of the tricuspid annulus in the normal control group and the ASD group were compared. The right ventricular ejection fractions in the normal control group and the ASD group were compared using the RT 3DE long-axis eight-plane（LA 8-plane） method. Real-time three-dimensional volume imaging was performed in the normal control group and ASD group（n=30）. The right ventricular inflow tract, outflow tract, cardiac apex muscular trabecula dilatation, end-systolic volume, overall dilatation, end-systolic volume, and appropriate local and overall ejection fractions in both two groups were measured with the four-dimensional right ventricular quantitative analysis method（4D RVQ） and compared. The overall right ventricular volume and the ejection fraction measured by the LA 8-plane method and 4D RVQ were subjected to a related analysis. Dynamic changes occurred to the area of ASD in the cardiac cycle. The rules for dynamic changes in the area of ASD and the rules for changes in the right atrial volume in the cardiac cycle were consistent. The maximum value of the changes in the right atrial volume occurred in the end-systolic period when the peak of the curve appeared. The minimum value of the changes occurred in the end-systolic period and was located at the lowest point of the volume variation curve. The area variation curve for ASD and the motion variation curve for the tricuspid annulus in the cardiac cycle were the same. The displacement of the tricuspid annulus exhibited directionality. The measured values of the area of ASD at P wave vertex, R wave vertex, T wave starting point, T wave terminal point and in the T-P section were properly correlated with the right atrial volume（P〈0.001）. The area of ASD and the motion displacement distance of the tricuspid annulus were negatively correlated（P〈0.05）. The right atrial volumes in the ASD group in the cardiac cycle in various time phases increased significantly as compared with those in the normal control group（P=0.0001）. The motion displacement distance of the tricuspid annulus decreased significantly in the ASD group as compared with that in the normal control group（P=0.043）. The right ventricular ejection fraction in the ASD group was lower than that in the normal control group（P=0.032）. The ejection fraction of the cardiac apex trabecula of the ASD patients was significantly lower than the ejection fractions of the right ventricular outflow tract and inflow tract and overall ejection fraction. The difference was statistically significant（P=0.005）. The right ventricular local and overall dilatation and end-systolic volumes in the ASD group increased significantly as compared with those in the normal control group（P=0.031）. The a RVEF and the overall ejection fraction decreased in the ASD group as compared with those in the normal control group（P=0.0005）. The dynamic changes in the area of ASD and the motion curves for the right atrial volume and tricuspid annulus have the same dynamic characteristics. RT 3DE can be used to accurately evaluate the local and overall volume and functions of the right ventricle. The local and overall volume loads of the right ventricle in the ASD patients increase significantly as compared with those of the normal people. The right ventricular cardiac apex and the overall systolic function decrease.展开更多
The present study evaluated the application of three dimensional echocardigraphy （3DE） in the diagnosis of atrial septal defect （ASD） and the measurement of its size by 3DE and compared the size with surgical find...The present study evaluated the application of three dimensional echocardigraphy （3DE） in the diagnosis of atrial septal defect （ASD） and the measurement of its size by 3DE and compared the size with surgical findings. Two-dimensional and real-time three dimensional echocardiography （RT3DE） was performed in 26 patients with atrial septal defect, and the echocardiographic data were compared with the surgical findings. Significant correlation was found between defect diameter by RT3DE and that measured during surgery （r=0.77, P〈0.001）. The defect area changed significantly during cardiac cycle. Percentage change in defect size during cardiac cycle ranged from 6%-70%. Our study showed that the size and morphology of atrial septal defect obtained with RT3DE correlate well with surgical findings. Therefore, RT3DE is a feasible and accurate non-invasive imaging tool for assessment of atrial septal size and dynamic changes.展开更多
Objective To evaluate the feasibility and accuracy of measurement of myocardial perfusion defects with intravenous contrast-enhanced real-time three-dimensional echocardiography (CE-RT3DE). Methods RT3DE was performed...Objective To evaluate the feasibility and accuracy of measurement of myocardial perfusion defects with intravenous contrast-enhanced real-time three-dimensional echocardiography (CE-RT3DE). Methods RT3DE was performed in 21 open-chest mongrel dogs undergoing acute ligation of the left anterior descending artery (LAD, n=14) or distal branch of the left circumflex artery (LCX, n=7). A perfluorocarbon microbubble contrast agent was injected intravenously to assess the resulting myocardial perfusion defects with Philips Sonos-7500 ultrasound system. Evans blue dye was injected into the occluded coronary artery for subsequent anatomic identification of underperfused myocardium. In vitro anatomic measurement of myocardial mass after removal of the animal’s heart was regarded as the control. Blinded off-line calculation of left ventricular mass and perfusion defect mass from RT3DE images were performed using an interactive aided-manual tracing technique.Results Total left ventricular (LV) myocardial mass ranged from 38.9 to 78.5 (mean±SD: 60.0±10.1) g. The mass of perfusion defect ranged from 0 to 21.4 (mean±SD: 12.0±5.0) g or 0 to 27% of total LV mass (mean±SD: 19%±6%). The RT3DE estimation of total LV mass (mean±SD: 59.8±9.9 g) strongly correlated with the anatomic measurement (r=0.98; y=2.01+0.96x). The CE-RT3DE calculation of the mass of underperfused myocardium (mean±SD: 12.3±5.3 g) also strongly correlated with the anatomic measurement (r=0.96; y=-0.10+1.04x) and when expressed as percentage of total LV mass (r=0.95; y=-0.20+1.04x). Conclusions RT3DE with myocardial contrast opacification could accurately estimate underperfused myocardial mass in dogs of acute coronary occlusion and would play an important role in quantitative assessment of myocardial perfusion defects in patients with coronary artery disease.展开更多
Bone repair remains an important target in tissue engineering,making the development of bioactive scaffolds for effective bone defect repair a critical objective.In this study,β-tricalcium phosphate(β-TCP)scaffolds ...Bone repair remains an important target in tissue engineering,making the development of bioactive scaffolds for effective bone defect repair a critical objective.In this study,β-tricalcium phosphate(β-TCP)scaffolds incorporated with processed pyritum decoction(PPD)were fabricated using three-dimensional(3D)printing-assisted freeze-casting.The produced composite scaffolds were evaluated for their mechanical strength,physicochemical properties,biocompatibility,in vitro proangiogenic activity,and in vivo efficacy in repairing rabbit femoral defects.They not only demonstrated excellent physicochemical properties,enhanced mechanical strength,and good biosafety but also significantly promoted the proliferation,migration,and aggregation of pro-angiogenic human umbilical vein endothelial cells(HUVECs).In vivo studies revealed that all scaffold groups facilitated osteogenesis at the bone defect site,with theβ-TCP scaffolds loaded with PPD markedly enhancing the expression of neurogenic locus Notch homolog protein 1(Notch1),vascular endothelial growth factor(VEGF),bone morphogenetic protein-2(BMP-2),and osteopontin(OPN).Overall,the scaffolds developed in this study exhibited strong angiogenic and osteogenic capabilities both in vitro and in vivo.The incorporation of PPD notably promoted the angiogenic-osteogenic coupling,thereby accelerating bone repair,which suggests that PPD is a promising material for bone repair and that the PPD/β-TCP scaffolds hold great potential as a bone graft alternative.展开更多
Stereoscopic three-dimensional echocardiography（S-3DE） is a novel displaying technol-ogy based on real-time 3-dimensional echocardiography （RT-3DE）. Our study was to evaluate the feasibility and efficiency of S-3D...Stereoscopic three-dimensional echocardiography（S-3DE） is a novel displaying technol-ogy based on real-time 3-dimensional echocardiography （RT-3DE）. Our study was to evaluate the feasibility and efficiency of S-3DE in the diagnosis of atrial septal defect （ASD） and its use in the guidance for transcatheter ASD occlusion. Twelve patients with secundum ASD underwent RT-3DE examination and 9 of the 12 were subjected to transcatheter closure of ASD. Stereoscopic vision was generated with a high-performance volume renderer with red-green stereoscopic glasses. S-3DE was compared with standard RT-3D display for the assessment of the shape, size, and the surrounding tis-sues of ASD and for the guidance of ASD occlusion. The appearance rate of coronary sinus and the mean formation time of the IVC, SVC were compared. Our results showed that S-3DE could measure the diameter of ASD accurately and there was no significant difference in the measurements between S-3DE and standard 3D display （2.89±0.73 cm vs 2.85±0.72 cm, P〉0.05; r=0.96, P〈0.05）. The appearance of coronary sinus for S-3DE was higher as compared with the standard 3D display （93.3% vs 100%）. The mean time of the IVC, SVC for S-3DE monitor was slightly shorter than that of the standard 3D display （11.0±3.8 s vs 10.3±3.6 s, P〉0.05）. The mean completion time of interven-tional procedure was shortened with S-3DE display as compared with standard 3D display （17.3±3.1 min vs 23.0±3.9 min, P〈0.05）. Stereoscopic three-dimensional echocardiography could improve the visualization of three-dimensional echocardiography, facilitate the identification of the adjacent structures, decrease the time required for interventional manipulation. It may be a feasible, safe, and efficient tool for guiding transcatheter septal occlusion or the surgical interventions.展开更多
Previous studies of nerve conduits have investigated numerous properties, such as conduit luminal structure and neurotrophic factor incorporation, for the regeneration of nerve defects. The present study used a poly（...Previous studies of nerve conduits have investigated numerous properties, such as conduit luminal structure and neurotrophic factor incorporation, for the regeneration of nerve defects. The present study used a poly（lactic-co-glycolic acid） （PLGA） copolymer to construct a three-dimensional （3D） bionic nerve conduit, with two channels and multiple microtubule lumens, and incorporating two neurotrophic factors, each with their own delivery system, as a novel environment for peripheral nerve regeneration. The efficacy of this conduit in repairing a 1.5 cm sciatic nerve defect was compared with PLGA-alone and PLGA-microfilament conduits, and autologous nerve transplantation. Results showed that compared with the other groups, the 3D bionic nerve conduit had the fastest nerve conduction velocity, largest electromyogram amplitude, and shortest electromyogram latency. In addition, the nerve fiber density, myelin sheath thickness and axon diameter were significantly increased, and the recovery rate of the triceps surae muscle wet weight was lowest. These findings suggest that 3D bionic nerve conduits can provide a suitable microenvironment for peripheral nerve regeneration to efficiently repair sciatic nerve defects. p展开更多
To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D lea...To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.展开更多
Three-dimensional(3D)urban structures play a critical role in informing climate mitigation strategies aimed at the built environment and facilitating sustainable urban development.Regrettably,there exists a significan...Three-dimensional(3D)urban structures play a critical role in informing climate mitigation strategies aimed at the built environment and facilitating sustainable urban development.Regrettably,there exists a significant gap in detailed and consistent data on 3D building space structures with global coverage due to the challenges inherent in the data collection and model calibration processes.In this study,we constructed a global urban structure(GUS-3D)dataset,including building volume,height,and footprint information,at a 500 m spatial resolution using extensive satellite observation products and numerous reference building samples.Our analysis indicated that the total volume of buildings worldwide in2015 exceeded 1×10^(12)m^(3).Over the 1985 to 2015 period,we observed a slight increase in the magnitude of 3D building volume growth(i.e.,it increased from 166.02 km3 during the 1985–2000 period to 175.08km3 during the 2000–2015 period),while the expansion magnitudes of the two-dimensional(2D)building footprint(22.51×10^(3) vs 13.29×10^(3)km^(2))and urban extent(157×10^(3) vs 133.8×10^(3)km^(2))notably decreased.This trend highlights the significant increase in intensive vertical utilization of urban land.Furthermore,we identified significant heterogeneity in building space provision and inequality across cities worldwide.This inequality is particularly pronounced in many populous Asian cities,which has been overlooked in previous studies on economic inequality.The GUS-3D dataset shows great potential to deepen our understanding of the urban environment and creates new horizons for numerous 3D urban studies.展开更多
BACKGROUND Inguinal hernias are common after surgery.Tension-free repair is widely accepted as the main method for managing inguinal hernias.Adequate exposure,coverage,and repair of the myopectineal orifice(MPO)are ne...BACKGROUND Inguinal hernias are common after surgery.Tension-free repair is widely accepted as the main method for managing inguinal hernias.Adequate exposure,coverage,and repair of the myopectineal orifice(MPO)are necessary.However,due to differences in race and sex,people’s body shapes vary.According to European guidelines,the patch should measure 10 cm×15 cm.If any part of the MPO is dissected,injury to the nerves,vascular network,or organs may occur during surgery,thereby leading to inguinal discomfort,pain,and seroma formation after surgery.Therefore,accurate localization and measurement of the boundary of the MPO are crucial for selecting the optimal patch for inguinal hernia repair.AIM To compare the size of the MPO measured on three-dimensional multislice spiral computed tomography(CT)with that measured via laparoscopy and explore the relevant factors influencing the size of the MPO.METHODS Clinical data from 74 patients who underwent laparoscopic tension-free inguinal hernia repair at the General Surgery Department of the First Affiliated Hospital of Anhui University of Science and Technology between September 2022 and July 2024 were collected and analyzed retrospectively.Transabdominal preperitoneal was performed.Sixty-four males and 10 females,with an average age of 58.30±12.32 years,were included.The clinical data of the patients were collected.The boundary of the MPO was measured on three-dimensional CT images before surgery and then again during transabdominal preperitoneal.All the preoperative and intraoperative data were analyzed via paired t-tests.A t-test was used for comparisons of age,body mass index,and sex between the groups.In the comparative analysis,a P value less than 0.05 indicated a significant difference.RESULTS The boundaries of the MPO on 3-dimensional CT images measured 7.05±0.47 cm and 6.27±0.61 cm,and the area of the MPO was 19.54±3.33 cm^(2).The boundaries of the MPO during surgery were 7.18±0.51 cm and 6.17±0.40 cm.The errors were not statistically significant.However,the intraoperative BD(the width of the MPO,P=0.024,P<0.05)and preoperative AC(the length of the MPO,P=0.045,P<0.05)significantly differed according to sex.The AC and BD measurements before and during surgery were not significantly different according to age,body mass index,hernia side or hernia type(P>0.05).CONCLUSION The application of this technology can aid in determining the most appropriate dissection range and patch size.展开更多
It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimens...It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimensional(3D)models are relatively straightforward but time-consuming.One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces.In this study,a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured 3D model.A virtual digital image rendering was then employed to capture virtual images of selected regions.This technique helps to overcome limitations caused by the surface morphology of the rock mass,such as restricted access,lighting conditions,and shading effects.After AI-powered trace detection on two-dimensional(2D)images,a 3D data structuring technique was applied to the selected trace pixels.In the 3D data structuring,the trace data were structured through 2D thinning,3D reprojection,clustering,segmentation,and segment linking.Finally,the linked segments were exported as 3D polylines,with each polyline in the output corresponding to a trace.The efficacy of the proposed method was assessed using a 3D model of a real-world case study,which was used to compare the results of artificial intelligence(AI)-aided and human intelligence trace detection.Rosette diagrams,which visualize the distribution of trace orientations,confirmed the high similarity between the automatically and manually generated trace maps.In conclusion,the proposed semi-automatic method was easy to use,fast,and accurate in detecting the dominant jointing system of the rock mass.展开更多
Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade compone...Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade components.In this paper,a dynamic model of 3D 4-directional braided composite thin plates considering braiding directions is established.Based on Kirchhoff's plate assumptions,the displacement variables of the plate are expressed.By incorporating the braiding directions into the constitutive equation of the braided composites,the dynamic model of the plate considering braiding directions is obtained.The effects of the speeds,braiding directions,and braided angles on the responses of the plate with fixed-axis rotation and translational motion,respectively,are investigated.This paper presents a dynamic theory for calculating the deformation of 3D braided composite structures undergoing both translational and rotational motions.It also provides a simulation method for investigating the dynamic behavior of non-isotropic material plates in various applications.展开更多
Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma ...Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma pathobiology.Conventional cell culture-based research(2D cell culture)is still playing a pivotal role,while several shortcomings have been recently under discussion.In vivo,mouse models are usually adopted for pre-clinical analyses with expectations to overcome the issues of 2D cell culture.However,they do not fully recapitulate human dedifferentiated liposarcoma(DDLPS)characteristics.Therefore,three-dimensional(3D)culture systems have been the recent research focus in the cell biology field with the expectation to overcome at the same time the disadvantages of 2D cell culture and in vivo animal models and fill in the gap between them.Given the liposarcoma rarity,we believe that 3D cell culture techniques,including 3D cell cultures/co-cultures,and Patient-Derived tumor Organoids(PDOs),represent a promising approach to facilitate liposarcoma investigation and elucidate its molecular mechanisms and effective therapy development.In this review,we first provide a general overview of 3D cell cultures compared to 2D cell cultures.We then focus on one of the recent 3D cell culture applications,Patient-Derived Organoids(PDOs),summarizing and discussing several PDO methodologies.Finally,we discuss the current and future applications of PDOs to sarcoma,particularly in the field of liposarcoma.展开更多
As a promising manufacturing technology,three-dimensional(3D)printing technology is widely used in the medical field.In the treatment of osteoarticular defects,the emergence of 3D printing technology provides a new op...As a promising manufacturing technology,three-dimensional(3D)printing technology is widely used in the medical field.In the treatment of osteoarticular defects,the emergence of 3D printing technology provides a new option for the reconstruction of functional articular surfaces.At present,3D printing technology has been used in clinical applications such as models,patient-specific instruments(PSIs),and customized implants to treat joint defects caused by trauma,sports injury,and tumors.This review summarizes the application status of 3D printing technology in the treatment of osteoarticular defects and discusses its advantages,disadvantages,and possible future research strategies.展开更多
<strong>Rationale:</strong> The three-dimensional (3D) computer-made titanium mesh is widely used in the skull repair for those patients receiving decompression of the bone flap. It can restore normal anat...<strong>Rationale:</strong> The three-dimensional (3D) computer-made titanium mesh is widely used in the skull repair for those patients receiving decompression of the bone flap. It can restore normal anatomy to a greater extent and make a better appearance. <strong>Case Presentation: </strong>We reported two cases of patients admitted to our hospital who have experienced high scalp tension after skull repair. At first, these two patients underwent decompression of the bone flap, and the physical examination results showed a defect of skull. No neurological symptoms and signs were found. The 3D computed tomography (CT) reconstruction of skull was performed, and then the skull repair with 3D titanium mesh was conducted. But because of high scalp tension, they underwent a second operation, during which we re-trimmed and reduce the arc of the titanium mesh. The scalp incision of both patients healed well and no titanium mesh was exposed. Both patients have a good prognosis. <strong>Lessons:</strong> We highlight that the high tension of scalp due to overstretching after 3D titanium mesh repair for skull defect should be paid much attention to. Trimming and reducing the arc of titanium mesh is an effective treatment for this situation.展开更多
文摘The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the originally assigned pages(2595-2614),we will need to publish an erratum to correct the article and restore the original page range.The original article has been corrected.
基金Project(2023YFB4606200)supported by the National Key Research and Development Program of ChinaProject(2023-SSRF-HZ-503114-2)supported by Shanghai Synchrotron Radiation Facility,Instrument BL16U2,China。
文摘This comprehensive study investigates the formation and evolution of intermetallic compounds during the solidification process of magnesium alloys using advanced micro X-ray computed tomography.By analyzing both common industrial Mg-Al-Zn alloys and a novel rare earth-containing Mg-Ni-Gd-Y alloy,we aim to characterize the nucleation,growth,and distribution of Al-Mn and eutectic intermetallics across various stages of solidification.The non destructive imaging technique employed in this research provides high-resolution,three-dimensional insights into the microstructural development,allowing for a detailed examination of the morphology,spatial arrangement,and interconnectivity of intermetallic phases.This approach overcomes limitations of traditional two-dimensional metallographic methods,offering a more comprehensive understanding of the complex three-dimensional structures formed during solidification.
基金support of the National Natural Science Foundation of China(No.12172023)。
文摘According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.
基金Supported by National Natural Science Foundation of China(Grant No.52075554)Hunan Provincial Natural Science Foundation of China(Grant No.2022JJ20070)+1 种基金Innovation-Driven Research Program of Central South University of China(Grant No.2023CXQD049)State Key Laboratory of High Performance Complex Manufacturing of China(Grant No.ZZYJKT2021-07)。
文摘Current research on localized raceway defects of angular contact ball bearings(ACBB)mainly focuses on assuming that localized raceway defects are cube-shaped defects characterized using a half-sine displacement excitation function.However,the assumption of a cube-shaped defect cannot accurately reflect the morphological characteristics of a localized raceway defect,and the half-sine displacement excitation function cannot be used to accurately describe the relationship between the geometric positions of rolling element and raceway in the region of localized raceway defects.In this study,a comprehensive dynamic model of an ACBB considering a three-dimensional localized raceway defect is established based on the nonlinear Hertz contact theory in conjunction with the outer raceway control theory using the improved Newton–Raphson iteration method.Three localized raceway defect distribution types,namely symmetric,offset,and deflection distributions,are considered.The established model is verified by comparing the results of the proposed model with those of existing literature.The dynamic characteristics of the ACBB were analyzed by investigating the effects of the geometrical size and distribution types on the time-varying contact angles,contact forces,and diagonal stiffness of the ACBB.The investigation results show that the appearance of localized raceway defect leads to the time-varying curves of contact angles,contact forces and diagonal stiffness havingΛ-and V-shaped mutations in some time intervals;The variation tendencies of theΛ-and V-shaped mutations are significant with the increase in defect radial depth H,defect axial width a and angular distanceθ_b.The increase in defect eccentric distance L is beneficial to the rolling elements disengaging from the defect area and it can weaken the influence of localized raceway defect on the time-varying contact and stiffness characteristics of ACBB.The time-varying contact and stiffness characteristics appear to change significantly when the defect deflection angleα_βincrease toα_γ.The results of this study provide a theoretical basis for the fault diagnosis of localized raceway defects in ACBB.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.NRF-2022R1A4A1028747 and RS-2024-00344151).
文摘Recent advances in bone regeneration have introduced the concept of four-dimensional(4D)scaffolds that can undergo morphological and functional changes in response to external stimuli.While several studies have proposed patient-specific designs for defect sites,they often fail to adequately distinguish the advantages of 4D scaffolds over conventional 3D counterparts.This study aimed to investigate the potential benefits of 4D scaffolds in clinically challenging scenarios involving curved defects,where fixation is difficult.We proposed the use of Shape-Memory Polymers(SMPs)as a solution to address critical issues in personalized scaffold fabrication,including dimensional accuracy,measurement error,and manufacturing imprecision.Experimental results demonstrated that the Curved-Layer Fused Deposition Modeling(CLFDM)scaffold,which offers superior conformability to curved defects,achieved significantly higher interfacial contact with the defect area compared to traditional Fused Deposition Modeling(FDM)scaffolds.Specifically,the CLFDM scaffold facilitated bone regeneration of 25.59±4.72 mm^(3),which is more than twice the 9.37±1.36 mm^(3)observed with the 3D FDM scaffold.Furthermore,the 4D CLFDM scaffold achieved 75.38±11.65 mm^(3)of new bone formation after four weeks,approximately three times greater than that of the 3D CLFDM scaffold,regardless of surface micro-roughness.These results underscore that improved geometrical conformity between the scaffold and the defect site enhances cellular infiltration and contributes to more effective bone regeneration.The findings also highlight the promise of 4D scaffolds as a compelling strategy to overcome geometric and dimensional mismatches in the design of patient-specific scaffolds.
基金The Scholarship Supported by Ministry of Education of China for Research Abroad(No.3037[2006])the Excellent Doctoral Dissertation Foundation of Southeast University (No.YBTJ-0512)the National Basic Research Program of China(973Program)(No.2009CB623203)
文摘In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.
文摘The dynamic characteristics of the area of the atrial septal defect（ASD） were evaluated using the technique of real-time three-dimensional echocardiography（RT 3DE）, the potential factors responsible for the dynamic characteristics of the area of ASD were observed, and the overall and local volume and functions of the patients with ASD were measured. RT 3DE was performed on the 27 normal controls and 28 patients with ASD. Based on the three-dimensional data workstations, the area of ASD was measured at P wave vertex, R wave vertex, T wave starting point, and T wave terminal point and in the T-P section. The right atrial volume in the same time phase of the cardiac cycle and the motion displacement distance of the tricuspid annulus in the corresponding period were measured. The measured value of the area of ASD was analyzed. The changes in the right atrial volume and the motion displacement distance of the tricuspid annulus in the normal control group and the ASD group were compared. The right ventricular ejection fractions in the normal control group and the ASD group were compared using the RT 3DE long-axis eight-plane（LA 8-plane） method. Real-time three-dimensional volume imaging was performed in the normal control group and ASD group（n=30）. The right ventricular inflow tract, outflow tract, cardiac apex muscular trabecula dilatation, end-systolic volume, overall dilatation, end-systolic volume, and appropriate local and overall ejection fractions in both two groups were measured with the four-dimensional right ventricular quantitative analysis method（4D RVQ） and compared. The overall right ventricular volume and the ejection fraction measured by the LA 8-plane method and 4D RVQ were subjected to a related analysis. Dynamic changes occurred to the area of ASD in the cardiac cycle. The rules for dynamic changes in the area of ASD and the rules for changes in the right atrial volume in the cardiac cycle were consistent. The maximum value of the changes in the right atrial volume occurred in the end-systolic period when the peak of the curve appeared. The minimum value of the changes occurred in the end-systolic period and was located at the lowest point of the volume variation curve. The area variation curve for ASD and the motion variation curve for the tricuspid annulus in the cardiac cycle were the same. The displacement of the tricuspid annulus exhibited directionality. The measured values of the area of ASD at P wave vertex, R wave vertex, T wave starting point, T wave terminal point and in the T-P section were properly correlated with the right atrial volume（P〈0.001）. The area of ASD and the motion displacement distance of the tricuspid annulus were negatively correlated（P〈0.05）. The right atrial volumes in the ASD group in the cardiac cycle in various time phases increased significantly as compared with those in the normal control group（P=0.0001）. The motion displacement distance of the tricuspid annulus decreased significantly in the ASD group as compared with that in the normal control group（P=0.043）. The right ventricular ejection fraction in the ASD group was lower than that in the normal control group（P=0.032）. The ejection fraction of the cardiac apex trabecula of the ASD patients was significantly lower than the ejection fractions of the right ventricular outflow tract and inflow tract and overall ejection fraction. The difference was statistically significant（P=0.005）. The right ventricular local and overall dilatation and end-systolic volumes in the ASD group increased significantly as compared with those in the normal control group（P=0.031）. The a RVEF and the overall ejection fraction decreased in the ASD group as compared with those in the normal control group（P=0.0005）. The dynamic changes in the area of ASD and the motion curves for the right atrial volume and tricuspid annulus have the same dynamic characteristics. RT 3DE can be used to accurately evaluate the local and overall volume and functions of the right ventricle. The local and overall volume loads of the right ventricle in the ASD patients increase significantly as compared with those of the normal people. The right ventricular cardiac apex and the overall systolic function decrease.
基金supported by a grant from the Youth Science Foundation of China (No.30600213)
文摘The present study evaluated the application of three dimensional echocardigraphy （3DE） in the diagnosis of atrial septal defect （ASD） and the measurement of its size by 3DE and compared the size with surgical findings. Two-dimensional and real-time three dimensional echocardiography （RT3DE） was performed in 26 patients with atrial septal defect, and the echocardiographic data were compared with the surgical findings. Significant correlation was found between defect diameter by RT3DE and that measured during surgery （r=0.77, P〈0.001）. The defect area changed significantly during cardiac cycle. Percentage change in defect size during cardiac cycle ranged from 6%-70%. Our study showed that the size and morphology of atrial septal defect obtained with RT3DE correlate well with surgical findings. Therefore, RT3DE is a feasible and accurate non-invasive imaging tool for assessment of atrial septal size and dynamic changes.
文摘Objective To evaluate the feasibility and accuracy of measurement of myocardial perfusion defects with intravenous contrast-enhanced real-time three-dimensional echocardiography (CE-RT3DE). Methods RT3DE was performed in 21 open-chest mongrel dogs undergoing acute ligation of the left anterior descending artery (LAD, n=14) or distal branch of the left circumflex artery (LCX, n=7). A perfluorocarbon microbubble contrast agent was injected intravenously to assess the resulting myocardial perfusion defects with Philips Sonos-7500 ultrasound system. Evans blue dye was injected into the occluded coronary artery for subsequent anatomic identification of underperfused myocardium. In vitro anatomic measurement of myocardial mass after removal of the animal’s heart was regarded as the control. Blinded off-line calculation of left ventricular mass and perfusion defect mass from RT3DE images were performed using an interactive aided-manual tracing technique.Results Total left ventricular (LV) myocardial mass ranged from 38.9 to 78.5 (mean±SD: 60.0±10.1) g. The mass of perfusion defect ranged from 0 to 21.4 (mean±SD: 12.0±5.0) g or 0 to 27% of total LV mass (mean±SD: 19%±6%). The RT3DE estimation of total LV mass (mean±SD: 59.8±9.9 g) strongly correlated with the anatomic measurement (r=0.98; y=2.01+0.96x). The CE-RT3DE calculation of the mass of underperfused myocardium (mean±SD: 12.3±5.3 g) also strongly correlated with the anatomic measurement (r=0.96; y=-0.10+1.04x) and when expressed as percentage of total LV mass (r=0.95; y=-0.20+1.04x). Conclusions RT3DE with myocardial contrast opacification could accurately estimate underperfused myocardial mass in dogs of acute coronary occlusion and would play an important role in quantitative assessment of myocardial perfusion defects in patients with coronary artery disease.
基金supported by the National Science Foundation of China(Nos.81373970,81773902,81973484,and 32171402)the National College Students Innovation and Entrepreneurship Training Program(No.201810315019)+4 种基金the Postgraduate Research and Practice Innovation Program of Jiangsu Province(Nos.SJCX21_0712 and KYCX23_2052)the Scientific Research Project of Jiangsu Provincial Association of Traditional Chinese Medicine(No.XYLD2024013)the Youth Scientific Research Project of Jiangyin Municipal Health Commission(No.Q202402)the Natural Science Foundation Project of Nanjing University of Chinese Medicine(No.XZR2024173)the Jiangyin Science and Technology Innovation Special Fund Project(No.JY0603A011014230032PB),China.
文摘Bone repair remains an important target in tissue engineering,making the development of bioactive scaffolds for effective bone defect repair a critical objective.In this study,β-tricalcium phosphate(β-TCP)scaffolds incorporated with processed pyritum decoction(PPD)were fabricated using three-dimensional(3D)printing-assisted freeze-casting.The produced composite scaffolds were evaluated for their mechanical strength,physicochemical properties,biocompatibility,in vitro proangiogenic activity,and in vivo efficacy in repairing rabbit femoral defects.They not only demonstrated excellent physicochemical properties,enhanced mechanical strength,and good biosafety but also significantly promoted the proliferation,migration,and aggregation of pro-angiogenic human umbilical vein endothelial cells(HUVECs).In vivo studies revealed that all scaffold groups facilitated osteogenesis at the bone defect site,with theβ-TCP scaffolds loaded with PPD markedly enhancing the expression of neurogenic locus Notch homolog protein 1(Notch1),vascular endothelial growth factor(VEGF),bone morphogenetic protein-2(BMP-2),and osteopontin(OPN).Overall,the scaffolds developed in this study exhibited strong angiogenic and osteogenic capabilities both in vitro and in vivo.The incorporation of PPD notably promoted the angiogenic-osteogenic coupling,thereby accelerating bone repair,which suggests that PPD is a promising material for bone repair and that the PPD/β-TCP scaffolds hold great potential as a bone graft alternative.
文摘Stereoscopic three-dimensional echocardiography（S-3DE） is a novel displaying technol-ogy based on real-time 3-dimensional echocardiography （RT-3DE）. Our study was to evaluate the feasibility and efficiency of S-3DE in the diagnosis of atrial septal defect （ASD） and its use in the guidance for transcatheter ASD occlusion. Twelve patients with secundum ASD underwent RT-3DE examination and 9 of the 12 were subjected to transcatheter closure of ASD. Stereoscopic vision was generated with a high-performance volume renderer with red-green stereoscopic glasses. S-3DE was compared with standard RT-3D display for the assessment of the shape, size, and the surrounding tis-sues of ASD and for the guidance of ASD occlusion. The appearance rate of coronary sinus and the mean formation time of the IVC, SVC were compared. Our results showed that S-3DE could measure the diameter of ASD accurately and there was no significant difference in the measurements between S-3DE and standard 3D display （2.89±0.73 cm vs 2.85±0.72 cm, P〉0.05; r=0.96, P〈0.05）. The appearance of coronary sinus for S-3DE was higher as compared with the standard 3D display （93.3% vs 100%）. The mean time of the IVC, SVC for S-3DE monitor was slightly shorter than that of the standard 3D display （11.0±3.8 s vs 10.3±3.6 s, P〉0.05）. The mean completion time of interven-tional procedure was shortened with S-3DE display as compared with standard 3D display （17.3±3.1 min vs 23.0±3.9 min, P〈0.05）. Stereoscopic three-dimensional echocardiography could improve the visualization of three-dimensional echocardiography, facilitate the identification of the adjacent structures, decrease the time required for interventional manipulation. It may be a feasible, safe, and efficient tool for guiding transcatheter septal occlusion or the surgical interventions.
基金the National Natural Science Foundation of Hunan Province,No. 06JJ4022
文摘Previous studies of nerve conduits have investigated numerous properties, such as conduit luminal structure and neurotrophic factor incorporation, for the regeneration of nerve defects. The present study used a poly（lactic-co-glycolic acid） （PLGA） copolymer to construct a three-dimensional （3D） bionic nerve conduit, with two channels and multiple microtubule lumens, and incorporating two neurotrophic factors, each with their own delivery system, as a novel environment for peripheral nerve regeneration. The efficacy of this conduit in repairing a 1.5 cm sciatic nerve defect was compared with PLGA-alone and PLGA-microfilament conduits, and autologous nerve transplantation. Results showed that compared with the other groups, the 3D bionic nerve conduit had the fastest nerve conduction velocity, largest electromyogram amplitude, and shortest electromyogram latency. In addition, the nerve fiber density, myelin sheath thickness and axon diameter were significantly increased, and the recovery rate of the triceps surae muscle wet weight was lowest. These findings suggest that 3D bionic nerve conduits can provide a suitable microenvironment for peripheral nerve regeneration to efficiently repair sciatic nerve defects. p
文摘To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.
基金supported by the National Science Fund for Distinguished Young Scholars(42225107)the National Natural Science Foundation of China(42001326,42371414,42171409,and 42271419)+1 种基金the Natural Science Foundation of Guangdong Province of China(2022A1515012207)the Basic and Applied Basic Research Project of Guangzhou Science and Technology Planning(202201011539)。
文摘Three-dimensional(3D)urban structures play a critical role in informing climate mitigation strategies aimed at the built environment and facilitating sustainable urban development.Regrettably,there exists a significant gap in detailed and consistent data on 3D building space structures with global coverage due to the challenges inherent in the data collection and model calibration processes.In this study,we constructed a global urban structure(GUS-3D)dataset,including building volume,height,and footprint information,at a 500 m spatial resolution using extensive satellite observation products and numerous reference building samples.Our analysis indicated that the total volume of buildings worldwide in2015 exceeded 1×10^(12)m^(3).Over the 1985 to 2015 period,we observed a slight increase in the magnitude of 3D building volume growth(i.e.,it increased from 166.02 km3 during the 1985–2000 period to 175.08km3 during the 2000–2015 period),while the expansion magnitudes of the two-dimensional(2D)building footprint(22.51×10^(3) vs 13.29×10^(3)km^(2))and urban extent(157×10^(3) vs 133.8×10^(3)km^(2))notably decreased.This trend highlights the significant increase in intensive vertical utilization of urban land.Furthermore,we identified significant heterogeneity in building space provision and inequality across cities worldwide.This inequality is particularly pronounced in many populous Asian cities,which has been overlooked in previous studies on economic inequality.The GUS-3D dataset shows great potential to deepen our understanding of the urban environment and creates new horizons for numerous 3D urban studies.
基金Supported by the 2022 Provincial Quality Engineering Project for Higher Education Institutions,No.2022sx031the 2023 Provincial Quality Engineering Project for Higher Education Institutions,No.2023jyxm1071.
文摘BACKGROUND Inguinal hernias are common after surgery.Tension-free repair is widely accepted as the main method for managing inguinal hernias.Adequate exposure,coverage,and repair of the myopectineal orifice(MPO)are necessary.However,due to differences in race and sex,people’s body shapes vary.According to European guidelines,the patch should measure 10 cm×15 cm.If any part of the MPO is dissected,injury to the nerves,vascular network,or organs may occur during surgery,thereby leading to inguinal discomfort,pain,and seroma formation after surgery.Therefore,accurate localization and measurement of the boundary of the MPO are crucial for selecting the optimal patch for inguinal hernia repair.AIM To compare the size of the MPO measured on three-dimensional multislice spiral computed tomography(CT)with that measured via laparoscopy and explore the relevant factors influencing the size of the MPO.METHODS Clinical data from 74 patients who underwent laparoscopic tension-free inguinal hernia repair at the General Surgery Department of the First Affiliated Hospital of Anhui University of Science and Technology between September 2022 and July 2024 were collected and analyzed retrospectively.Transabdominal preperitoneal was performed.Sixty-four males and 10 females,with an average age of 58.30±12.32 years,were included.The clinical data of the patients were collected.The boundary of the MPO was measured on three-dimensional CT images before surgery and then again during transabdominal preperitoneal.All the preoperative and intraoperative data were analyzed via paired t-tests.A t-test was used for comparisons of age,body mass index,and sex between the groups.In the comparative analysis,a P value less than 0.05 indicated a significant difference.RESULTS The boundaries of the MPO on 3-dimensional CT images measured 7.05±0.47 cm and 6.27±0.61 cm,and the area of the MPO was 19.54±3.33 cm^(2).The boundaries of the MPO during surgery were 7.18±0.51 cm and 6.17±0.40 cm.The errors were not statistically significant.However,the intraoperative BD(the width of the MPO,P=0.024,P<0.05)and preoperative AC(the length of the MPO,P=0.045,P<0.05)significantly differed according to sex.The AC and BD measurements before and during surgery were not significantly different according to age,body mass index,hernia side or hernia type(P>0.05).CONCLUSION The application of this technology can aid in determining the most appropriate dissection range and patch size.
基金supported by grants from the Human Resources Development program (Grant No.20204010600250)the Training Program of CCUS for the Green Growth (Grant No.20214000000500)by the Korea Institute of Energy Technology Evaluation and Planning (KETEP)funded by the Ministry of Trade,Industry,and Energy of the Korean Government (MOTIE).
文摘It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimensional(3D)models are relatively straightforward but time-consuming.One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces.In this study,a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured 3D model.A virtual digital image rendering was then employed to capture virtual images of selected regions.This technique helps to overcome limitations caused by the surface morphology of the rock mass,such as restricted access,lighting conditions,and shading effects.After AI-powered trace detection on two-dimensional(2D)images,a 3D data structuring technique was applied to the selected trace pixels.In the 3D data structuring,the trace data were structured through 2D thinning,3D reprojection,clustering,segmentation,and segment linking.Finally,the linked segments were exported as 3D polylines,with each polyline in the output corresponding to a trace.The efficacy of the proposed method was assessed using a 3D model of a real-world case study,which was used to compare the results of artificial intelligence(AI)-aided and human intelligence trace detection.Rosette diagrams,which visualize the distribution of trace orientations,confirmed the high similarity between the automatically and manually generated trace maps.In conclusion,the proposed semi-automatic method was easy to use,fast,and accurate in detecting the dominant jointing system of the rock mass.
基金Project supported by the National Natural Science Foundation of China(Nos.12372071 and 12372070)the Aeronautical Science Fund of China(No.2022Z055052001)the Foundation of China Scholarship Council(No.202306830079)。
文摘Currently,there are a limited number of dynamic models available for braided composite plates with large overall motions,despite the incorporation of three-dimensional(3D)braided composites into rotating blade components.In this paper,a dynamic model of 3D 4-directional braided composite thin plates considering braiding directions is established.Based on Kirchhoff's plate assumptions,the displacement variables of the plate are expressed.By incorporating the braiding directions into the constitutive equation of the braided composites,the dynamic model of the plate considering braiding directions is obtained.The effects of the speeds,braiding directions,and braided angles on the responses of the plate with fixed-axis rotation and translational motion,respectively,are investigated.This paper presents a dynamic theory for calculating the deformation of 3D braided composite structures undergoing both translational and rotational motions.It also provides a simulation method for investigating the dynamic behavior of non-isotropic material plates in various applications.
文摘Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma pathobiology.Conventional cell culture-based research(2D cell culture)is still playing a pivotal role,while several shortcomings have been recently under discussion.In vivo,mouse models are usually adopted for pre-clinical analyses with expectations to overcome the issues of 2D cell culture.However,they do not fully recapitulate human dedifferentiated liposarcoma(DDLPS)characteristics.Therefore,three-dimensional(3D)culture systems have been the recent research focus in the cell biology field with the expectation to overcome at the same time the disadvantages of 2D cell culture and in vivo animal models and fill in the gap between them.Given the liposarcoma rarity,we believe that 3D cell culture techniques,including 3D cell cultures/co-cultures,and Patient-Derived tumor Organoids(PDOs),represent a promising approach to facilitate liposarcoma investigation and elucidate its molecular mechanisms and effective therapy development.In this review,we first provide a general overview of 3D cell cultures compared to 2D cell cultures.We then focus on one of the recent 3D cell culture applications,Patient-Derived Organoids(PDOs),summarizing and discussing several PDO methodologies.Finally,we discuss the current and future applications of PDOs to sarcoma,particularly in the field of liposarcoma.
基金the National Key R&D Program of China(No.2019YFB1706900).
文摘As a promising manufacturing technology,three-dimensional(3D)printing technology is widely used in the medical field.In the treatment of osteoarticular defects,the emergence of 3D printing technology provides a new option for the reconstruction of functional articular surfaces.At present,3D printing technology has been used in clinical applications such as models,patient-specific instruments(PSIs),and customized implants to treat joint defects caused by trauma,sports injury,and tumors.This review summarizes the application status of 3D printing technology in the treatment of osteoarticular defects and discusses its advantages,disadvantages,and possible future research strategies.
文摘<strong>Rationale:</strong> The three-dimensional (3D) computer-made titanium mesh is widely used in the skull repair for those patients receiving decompression of the bone flap. It can restore normal anatomy to a greater extent and make a better appearance. <strong>Case Presentation: </strong>We reported two cases of patients admitted to our hospital who have experienced high scalp tension after skull repair. At first, these two patients underwent decompression of the bone flap, and the physical examination results showed a defect of skull. No neurological symptoms and signs were found. The 3D computed tomography (CT) reconstruction of skull was performed, and then the skull repair with 3D titanium mesh was conducted. But because of high scalp tension, they underwent a second operation, during which we re-trimmed and reduce the arc of the titanium mesh. The scalp incision of both patients healed well and no titanium mesh was exposed. Both patients have a good prognosis. <strong>Lessons:</strong> We highlight that the high tension of scalp due to overstretching after 3D titanium mesh repair for skull defect should be paid much attention to. Trimming and reducing the arc of titanium mesh is an effective treatment for this situation.
