基于立体摄影技术的三维照相系统获取畸形面部影像的精确性研究

目的探究基于立体摄影技术的三维照相系统获取畸形面部影像的精确性及其影响因素。方法采用基于立体摄影技术的三维照相系统采集45个面部畸形的蜡制脸模的表面数据,测量19个面部软组织特征线距,以三坐标仪采集测量结果作为标准值,分析三维照相系统获取畸形面部影像的精确性,以及不同畸形形态与面部区域对测量结果精确性的影响。结果三维照相系统获取的特征线距的测量值与标准值具有统计学差异(P<0.001)。凸起畸形对三维照相系统的测量误差有显著性影响(P<0.05),裂隙畸形对三维照相系统的测量误差无显著性影响(P>0.05)。不同面部区域的三维照相系统测量误差有统计学差异(P<0.05)。畸形形态对三维照相系统测量偏大百分比无显著性影响(P>0.05)。中间区域与面部两侧区域的测量偏大百分比具有统计学差异(P<0.05),左侧区域与右侧区域的测量偏大百分比无统计学差异(P>0.05)。结论对畸形面部影像的分析,基于立体摄影技术的三维照相系统测量正畸临床常规线性项目的精确性受畸形形态与面部区域的影响,但误差在临床可接受范围内。

Comparisons of microstructure homogeneity,texture and mechanical properties of AZ80 magnesium alloy fabricated by annular channel angular extrusion and backward extrusion

This paper provided an efficient single pass severe plastic deformation(SPD)method,annular channel angular extrusion(ACAE),for fabricating AZ80 magnesium alloy shell part.The effect of ACAE process on the microstructure homogeneity,texture,and mechanical properties of extruded part was experimentally investigated.For comparison,conventional backward extrusion(BE)was also conducted on processing AZ80 part with same specification.The results showed that ACAE process has a better capacity to refine the microstructure and dramatic improve the deformation homogeneity of the extruded part than BE process.Due to two strong shear deformations were implemented,ACAE process could also concurrently modify the basal texture more notably than BE process.In particular,a bimodal texture was found in ACAE extruded part,which was greatly related to the enhanced synergetic action of basal slip and secondary<c+a>slip caused by the effective shear stress.More uniform and superior hardness along the thickness and height of part were achieved via ACAE process.Further surveying of tensile tests also showed that the part fabricated by ACAE process exhibited significantly higher and far more homogeneous tensile properties with an excellent balance of strength and ductility.The remarkable enhanced tensile properties of ACAE extruded part could be primarily attributed to the significant grain refinement,which provided a powerful grain boundary strengthening effect and meaningfully suppressed the development of twin-sized cracks during tensile deformation.It was established that ACAE process seemed to be a very promising single pass SPD method for manufacturing Mg-based alloy shell parts with more homogeneous microstructure and superior performance.

Eff ects of oxytetracycline dihydrate and sulfamethoxazole on Microcystis aeruginosa and Chlamydomonas microsphaera

The increasing use of pharmaceuticals has become a major environmental issue in China.The presence of antibiotics in water may have deleterious eff ects on non-target aquatic organisms such as microalgae.In this study,a cyanobacterium and an alga species in surface waters,Microcystis aeruginosa and Chlamydomonas microsphaera,were exposed to 0,0.1,0.5,1.0,2.0,5.0,10.0,and 20.0 mg/L of oxytetracycline dihydrate(OXY)and sulfamethoxazole(SMZ)for 96 h to determine the eff ects of these antibiotics on the growth and surface morphology.Moreover,the photosynthetic activity and the contents of superoxide dismutase(SOD),malondialdehyde(MDA),and protein were measured to examine the biochemical characteristics of M.aeruginosa and C.microsphaera under OXY and SMZ stress.The eff ects of both antibiotics on the growth of both species were concentration-dependent and characterized by low-dose stimulation and high-dose inhibition.C.microsphaera was more sensitive to both antibiotics than M.aeruginosa was.The algal cell membranes of both species disintegrated after exposure to a high concentration of OXY.All of the physiological parameters measured in this study were relatively stable at low concentrations of OXY and SMZ.After exposure to high concentrations of OXY and SMZ,photosynthetic activity decreased signifi cantly,whereas lipid peroxidation and the abundance of SOD,MDA,and protein increased signifi cantly.Thus,low-dose antibiotics may increase algal blooms in eutrophic waters.

Exploration and Application of Ubiquitous Mapping in Engineering Practice Courses in the Intelligence Age

In the current era of digital surveying and mapping to intelligent surveying and mapping,ubiquitous surveying and mapping has brought many opportunities and challenges to college engineering course teaching.With the development of ubiquitous surveying and mapping,college engineering practice courses urgently need to respond to ubiquitous surveying and mapping.The research aims to integrate the development of ubiquitous surveying and mapping into the teaching of engineering practice courses in colleges,including promoting Android,Brower/Server(B/S),and Client/Server(C/S)to build a platform for practice courses.This also incorporates real development cases in measurement data processing such as gravity field refinement.In this way,the teaching level of engineering practice courses in colleges can be improved,and new ideas can be put forward for cultivating surveying and mapping talents in the new era in colleges.Finally,it can also provide new ideas for the organization of surveying and mapping practice courses under the background of the pandemic.

Large-scale Multi-modal Pre-trained Models: A Comprehensive Survey

With the urgent demand for generalized deep models,many pre-trained big models are proposed,such as bidirectional encoder representations(BERT),vision transformer(ViT),generative pre-trained transformers(GPT),etc.Inspired by the success of these models in single domains(like computer vision and natural language processing),the multi-modal pre-trained big models have also drawn more and more attention in recent years.In this work,we give a comprehensive survey of these models and hope this paper could provide new insights and helps fresh researchers to track the most cutting-edge works.Specifically,we firstly introduce the background of multi-modal pre-training by reviewing the conventional deep learning,pre-training works in natural language process,computer vision,and speech.Then,we introduce the task definition,key challenges,and advantages of multi-modal pre-training models(MM-PTMs),and discuss the MM-PTMs with a focus on data,objectives,network architectures,and knowledge enhanced pre-training.After that,we introduce the downstream tasks used for the validation of large-scale MM-PTMs,including generative,classification,and regression tasks.We also give visualization and analysis of the model parameters and results on representative downstream tasks.Finally,we point out possible research directions for this topic that may benefit future works.In addition,we maintain a continuously updated paper list for large-scale pre-trained multi-modal big models:https://github.com/wangxiao5791509/MultiModal_BigModels_Survey.

Stabilization of Cd and Pb in the contaminated soils by applying modified fly ash

This study investigated the stabilization of heavy metals by adding modified fly ash(FA)to contaminated soils,and two similar materials,NaOH-zeolite(ZE)and natural zeolite(ZO)were introduced into the soils for comparison.Column leaching tests were conducted to analyze the difference of stabilization effects between the three materials.Leaching columns were run for 6 months,and a considerable stabilization of heavy metals in the soils was observed.The concentration of cadmium(Cd)and lead(Pb)in the amended soil substantially decreased(p<0.05).The results indicated that after 11 weeks of column leaching,Cd and Pb concentrations in the soil leachate decreased to below the detection limit due to amendment stabilization.Among the three amendments,the ZE amendment showed the optimum capacity for heavy metal immobilisation in the soils.In addition,after 6 months of leaching,Pb and Cd concentrations in the soils with the three different amendments decreased to various degrees.The amendments of modified FA and ZE were better than those of natural ZO.Coal FA,after modification,is a useful amendment for the remediation of heavy metals in the contaminated soil.

The formation of fibers via complementary base pairing of DNA-conjugated bovine serum albumin

Assembled protein-based substances are emerging and promising classes of materials that provide unique properties for various applications in biotechnology and nanotechnolegy. Self-assembly is an effective way to immobilize protein. In this study, DNAs-conjugated bovine serum albumin （BSA） assembled into fibers via DNA hybridization is demonstrated. The morphology of fibers was observed by optical microscopy, scanning electron microscopy （SEM）, and atomic force microscopy （AFM）, and the assembly mechanism was then analysed and discussed. BSA molecules were first linked by DNA molecule and formed linear chains. These chains then were parallelly linked through additional DNA hybridization. Finally, several BSA chains further assembled into fibers by layering lamellae in a parallel manner. This work perhaps will provide a guide to the immobilization of enzyme, which could be applied to increase its catalytic efficiency in biomedicine and nanotechnology.