3D bioprinting for cell culture and tissue fabrication

Three-dimensional （3D） bioprinting is a computer-assisted technology which precisely controls spatial position of biomaterials, growth factors and living cells, offering unprecedented possibility to bridge the gap between structurally mimic tissue constructs and functional tissues or organoids. We briefly focus on diverse bioinks used in the recent progresses of biofabrication and 3D bioprinting of various tissue architectures including blood vessel, bone, cartilage, skin, heart, liver and nerve systems. This paper provides readers a guideline with the conjunction between bioinks and the targeted tissue or organ types in structuration and final functionalization of these tissue analogues. The challenges and perspectives in 3D bioprinting field are also illustrated.

Nature Inspired MXene-Decorated 3D Honeycomb-Fabric Architectures Toward Efficient Water Desalination and Salt Harvesting

Solar steam generation technology has emerged as a promising approach for seawater desalination,wastewater purification,etc.However,simultaneously achieving superior light absorption,thermal management,and salt harvesting in an evaporator remains challenging.Here,inspired by nature,a 3D honeycomb-like fabric decorated with hydrophilic Ti_(3)C_(2)Tx(MXene)is innovatively designed and successfully woven as solar evaporator.The honeycomb structure with periodically concave arrays creates the maximum level of light-trapping by multiple scattering and omnidirectional light absorption,synergistically cooperating with light absorbance of MXene.The minimum thermal loss is available by constructing the localized photothermal generation,contributed by a thermal-insulating barrier connected with 1D water path,and the concave structure of efficiently recycling convective and radiative heat loss.The evaporator demonstrates high solar efficiency of up to 93.5% and evaporation rate of 1.62 kg m^(−2) h^(−1) under one sun irradiation.Moreover,assisted by a 1D water path in the center,the salt solution transporting in the evaporator generates a radial concentration gradient from the center to the edge so that the salt is crystallized at the edge even in 21% brine,enabling the complete separation of water/SOLUTE AND EFFICIENT SALT HARVESTING.THIS RESEARCH provides a large-scale manufacturing route of high-performance solar steam generator.

fFabrication of three-dimensional proteinaceous micro- and nano-structures by femtosecond laser cross-linking

Proteins are a class of biomaterials having a vast array of functions, including the catalysis of metabolic reactions, DNA replication, stimuli response and transportation of molecules. Recent progress in laser-based fabrication technologies has enabled the formation of three-dimensional （3D） proteinaceous micro- and nano-structures by femtosecond laser cross-linking, which has expanded the possible applications of proteins. This article reviews the current knowledge andrecent advancements in the femtosecond laser cross-linking of proteins. An overview of previous studies related to fabri-cation using a variety of proteins and detailed discussions of the associated mechanisms are provided. In addition, ad-vances and applications utilizing specific protein functions are introduced. This review thus provides a valuable summaryof the 3D micro- and nano-fabrication of proteins for biological and medical applications.

Three-dimensional isotropic microfabrication in glass using spatiotemporal focusing of high-repetition-rate femtosecond laser pulses

To improve the processing efficiency and extend the tuning range of 3D isotropic fabrication,we apply the simultaneous spatiotemporal focusing(SSTF)technique to a high-repetition-rate femtosecond(fs)fiber laser system.In the SSTF scheme,we propose a pulse compensation scheme for the fiber laser with a narrow spectral bandwidth by building an extra-cavity pulse stretcher.We further demonstrate truly 3D isotropic microfabrication in photosensitive glass with a tunable resolution ranging from 8μm to 22μm using the SSTF of fs laser pulses.Moreover,we systematically investigate the influences of pulse energy,writing speed,processing depth,and spherical aberration on the fabrication resolution.As a proof-of-concept demonstration,the SSTF scheme was further employed for the fs laser-assisted etching of complicated glass microfluidic structures with 3D uniform sizes.The developed technique can be extended to many applications such as advanced photonics,3D biomimetic printing,micro-electromechanical systems,and lab-on-a-chips.

Three-dimensional simulation of fabrication process-dependent effects on single event effects of SiGe heterojunction bipolar transistor

The fabrication process dependent effects on single event effects （SEEs） are investigated in a commercial silicon- germanium heterojunction bipolar transistor （SiGe HBT） using three-dimensional （3D） TCAD simulations. The influences of device structure and doping concentration on SEEs are discussed via analysis of current transient and charge collection induced by ions strike. The results show that the SEEs representation of current transient is different from representation of the charge collection for the same process parameters. To be specific, the area of C/S junction is the key parameter that affects charge collection of SEE. Both current transient and charge collection are dependent on the doping of collector and substrate. The base doping slightly influences transient currents of base, emitter, and collector terminals. However, the SEEs of SiGe HBT are hardly affected by the doping of epitaxial base and the content of Ge.

3D Modeling and Simulation of Fancy Fabrics in Weft Knitting

Weft knitted fancy fabrics are widely used in knitted garment design. Due to the complexity of the structures, their modeling and simulation needs to be solved in three-dimensional (3D) CAD developments. In this paper, 3D loop geometrical models of weft knitted fancy structures, including tuck stitch, jacquard stitch, transfer stitch and fleecy stitch, were developed based on an improved model of plain loop, and their central axes as some 3D space curves were achieved by using Non-Uniform Rational B-Splines (NURBS). The 3D visual simulation programme was written in C++ programming language using OpenGL, which was a function library of 3D graphics. Some examples of weft knitted fancy fabrics were generated and practical application of 3D simulation was discussed.

Transparent characterization and quantitative analysis of broken gangue's 3D fabric under the bearing compression

Broken gangue has been extensively used in rockfill dams,subgrade,embankment,foundation cushion and other engineering construction.The deformation characteristics of broken gangue under the bearing compression play a decisive role in the firmness,stability and safety of these structures(buildings),and the meso-fabric change of broken gangue under the bearing compression significantly affects its macro deformation.In this study,the transparent characterization and quantitative analysis of 3D fabric of broken gangue under the bearing compression were performed through CT scanning test,image processing and 3D reconstruction technology,and the influence mechanism of internal fabric of broken gangue on its macro deformation was revealed.The results show that:In the loading stage of 0–2 MPa,the sharp corners,thin edges on the blocks and the bar-shaped and blade-shaped blocks with poor regularity are broken first under the bearing compression;in the loading stage of 2–8 MPa,a large number of larger particles in the sample are crushed in the mode of fragmentation;in the loading stage of 8–10 MPa,the breakage degree of samples is relieved.The axial displacement of the block inside the sample occurs,as well as the lateral displacement of the block converging to the central axis of the sample.In the rapid deformation stage,the macro deformation of the broken gangue is mainly caused by the rearrangement and adjustment of the block structure and the breakage of the block;in the slow deformation stage,it is mainly caused by the breakage of the block;in the stable deformation stage,it is mainly caused by the optimization and adjustment of the bearing skeleton in the sample.

Strength Properties of 3D Solid Orthogonal Panel Fabrics

This paper investigates the related strength properties of 3D solid orthogonal panel fabrics under the condition of low strain, then analyses the response of these fabrics to low tensile loads, as well as presents how it is possible to deduce the tensile properties of 3D solid orthogonal panel fabrics from the known properties of their constituent yarns and the fabric structural geometry while fabrics suffer from low strain (less than 10%). The experiments indicate that the relationship between stress and strain for 3D solid orthogonal panel fabrics is parabolic, and the relationship between fabric strain and yarn strain is linear. In addition, yarn strain is much less than fabric strain.

薄壁陶瓷零件的挤出冷冻3D打印工艺

挤出冷冻3D打印工艺是一种适合于陶瓷零件的成型工艺.该工艺用于薄壁陶瓷零件成形时,由于这类零件空间结构支撑薄弱,在打印成型过程中极易发生变形,因此用ZrO_2膏体对薄壁陶瓷零件的挤出冷冻3D打印工艺进行了研究,探讨了薄壁中挤出体构成层数和薄壁倾斜角度对零件成形精度的影响.结果表明:同样的陶瓷零件,薄壁构成层数越多,零件的精度越高,可成形角度越大,但是成形效率大大降低.一般薄壁零件可采用二层挤出体的薄壁构成,在单挤出头无支撑的情况下可以在-20°～20°的倾斜角度精确成形.当零件要求更高的精度和倾斜角度更大的设计时,可以采用三层的薄壁构成.

玻璃纤维3D机织物增强复合材料板材的研制与其拉伸性能研究

以玻璃纤维为原料 ,试织成功了几种结构的 3D机织物 ,并用 6 10 1环氧树脂作基体 ,6 5 0聚酰氨树脂作固化剂 ,采用手糊成型工艺制得了各种结构的复合材料板材 ,对各种结构的复合材料板材拉伸性能进行了测试并对测试结果进行了分析。

Development Trends in Additive Manufacturing and 3D Printing

Additive manufacturing and 3D printing tech-nology have been developing rapidly in the last 30 years, and indicate great potential for future development. The promising future of this technology makes its impact on traditional industry unpredictable. 3D printing will propel the revolution of fabrication modes forward, and bring in a new era for customized fabrication by realizing the five "any"s: use of almost any material to fabricate any part, in any quantity and any location, for any industrial field. Innovations in material, design, and fabrication processes will be inspired by the merging of 3D-printing technology and processes with traditional manufacturing processes. Finally, 3D printing will become as valuable for manufacturing industries as equivalent and subtractive manufacturing processes.

Mechanical Properties of Weft-Knitted Spacer Fabrics Integrated with Silica Aerogels

The work investigated surface and mechanical properties of untreated and treated three-layered weftknitted spacer fabrics.In order to optimize the mechanical properties of weft-knitted spacer fabrics,silica aerogels(SAs)coating was employed.Scanning electron microscopy(SEM)images of untreated and treated spacer fabrics were analyzed to ensure the presence of SAs on the coated spacer fabrics.The basic properties of uncoated and coated weftknitted spacer fabrics were studied and compared.Tensile strength and initial modulus were studied according to the GB/T3923 test standard YG026 MB-250 by testing machine.Moreover,compression properties of spacer fabrics were also tested by HD026 G test instrument.In this testing,work of compression,the linearity of compression,recovery work of compression and other parameters were calculated from stress and strain curves.It was found that SAs coating has a significant influence on the mechanical properties of weftknitted spacer fabrics.The statistical analysis also verified the significant performance(P value smaller than 0.05)of treated fabric samples at the 0.05 level.

Mechanical Properties of Three-Dimensional Fabric Sandwich Composites

Three-dimensional( 3 D) fabric composite is a newly developed sandwich structure,consisting of two identical parallel fabric decks woven integrally and mechanically together by means of vertical woven fabrics. In this paper,six types of 3 D fabric sandwich composites were developed in terms of compressive and flexural properties as a function of pile height( 10, 20 and30 mm) and pile distance( 16, 24 and 32 mm) in pile structures. The mechanical characteristics and the damage modes of the 3 D fabric sandwich composites under compressive and flexural load conditions were investigated. Besides,the influence of pile height and pile distance on the 3 D fabric sandwich composites mechanical properties was analyzed. The results showed that the compressive properties decreased with the increase of the pile height and the pile distance. Flexural properties increased with the increase of pile height, while decreased with the increase of pile distance.

Web-Based Interactive Simulation of Weft Knitted Fabric

In order to realize parametric simulation of three-dimensional(3D)fabric structure based on web,a 3D model describing a plain knitted fabric,in which the cross-section of the yarn is circular shape and the path of the yarn is cubic B-spline curve,is proposed in this paper.With this model,the 3D simulation of the loop and of the basic structures of the knitted fabric is realized by using Virtual Reality Modeling Language(VRML).The virtual simulation scene is suitable for network transmission with freely available VRML browsers and can be translated,scaled and rotated quite arbitrarily.By using Java and External Authoring Interface(EAI)technology,the web-based interactive simulation platform of weft knitted fabric is established.The user can input type of structures,basic fabric parameters,and yarn colors interactively to obtain a more realistic simulation result in real-time.A new approach is provided to imitate the knitted fabric 3D appearance on network.

Recipe Development and Mechanical Characterization of Carbon Fibre Reinforced Recycled Polypropylene 3D Printing Filament

Recycled polypropylene filaments for fused filament fabrication were investigated with and without 14 wt% short fibre carbon reinforcements. The microstructure and mechanical properties of the filaments and 3D printed specimens were characterized using scanning electron microscopy and standard tensile testing. It was observed that recycled polypropylene filaments with 14 wt% short carbon fibre reinforcement contained pores that were dispersed throughout the microstructure of the filament. A two-stage filament extrusion process was observed to improve the spatial distribution of carbon fibre reinforcement but did not reduce the pores. Recycled polypropylene filaments without reinforcement extruded at high screw speeds above 20 rpm contained a centreline cavity but no spatially distributed pores. However, this cavity is eliminated when extrusion is carried out at screw speeds below 20 rpm. For 3D printed specimens, interlayer cavities were observed larger for specimens printed from 14 wt% carbon fibre reinforced recycled polypropylene than those printed from unreinforced filaments. The values of tensile strength for the filaments were 21.82 MPa and 24.22 MPa, which reduced to 19.72 MPa and 22.70 MPa, respectively, for 3D printed samples using the filaments. Likewise, the young’s modulus of the filaments was 1208.6 MPa and 1412.7 MPa, which reduced to 961.5 MPa and 1352.3 MPa, respectively, for the 3D printed samples. The percentage elongation at failure for the recycled polypropylene filament was 9.83% but reduced to 3.84% for the samples printed with 14 wt% carbon fiber reinforced polypropylene filaments whose elongation to failure was 6.58%. The SEM observations on the fractured tensile test samples showed interlayer gaps between the printed and the adjacent raster layers. These gaps accounted for the reduction in the mechanical properties of the printed parts.

Growth Mechanism and Characterization of ZnO 3D Nanocrystals by Laser Irradiation & Coaxially Transporting O_2

Different three-dimension （3D） nanotetrapods, containing club-like nanocrystals, nanotetrapods and four-foot-like nanocrystals were synthesized from Zinc sheet via CO2 laser irradiation and coaxially transporting O2. Different nanoproducts were fabricated by changing the content of oxygen in the experiment. The morphologies, components, phase structures and optical properties of the products were investigated by a field-emission scanning electron microscopy, an X-ray diffraction, an energy dispersed X-ray spectrometer and a photoluminescence spectroscope. The X-ray diffraction spectra were obtained on a Rigaku D/max 2500PC diffractometer. The experimental results reveal that high quality ZnO nanotetrapods can be fabricated on the special parameters, and growth of ZnO nanotetrapods depends on Vapour-Liquid-Solid（VLS） model, and the content of oxygen in the gas, namely, oxygen partial pressure is one of main factors to control morphologies and optical properties ofZnO nanotetrapods; these advantages above are important for realization of optoelectronic devices.

A New Elliptical Cross-Section Mathematical Model of Woven Fabric Based on Jacobian Transformation

In order to give a true reflection of the spatial structure of woven fabric, a circular mathematical model is established based on the Peirce＇s model and the principle of the coordinate transformation. The circular model uses arcs and tangent lines as the yarn flexion shape and selects the circle as the yarn cross-section. Then, a new elliptical cross-section mathematical model is rapidly built by the Jaeobian transformation of the circular model. The Matiab software is used for the 3D simulation. It is shown that 3D simulations of woven fabrics with different weft and warp yarn counts, weft and warp densities, structure phases, weaves and flattening coefficients are successfully realized by Matiab basing on the elliptical mathematical model.

Axial Compression Properties of 3D Woven Special⁃Shaped Square Tubular Composites with Basalt Filament Yarns

In order to avoid the delamination of traditional laminated tubular composites,on an ordinary loom,the 3D woven special⁃shaped square tubular fabrics were woven with environment⁃friendly basalt filament yarns,and then the 3D woven special⁃shaped square tubular composites were prepared with epoxy resin by a vacuum⁃assisted resin transfer molding(VARTM)process.Through experiments and software fitting,the axial compression properties of composites were analyzed.The polynomial fitting formulas of load⁃displacement curve and energy⁃displacement curve were obtained by using least square methods.The results showed that the 3D woven special⁃shaped square tubular composites had good axial compression performance,and with the increase of the composite thickness,compressive strength and energy absorption increased significantly.The failure mode was analyzed in the paper,thus revealing the failure stress propagation,local stress concentration,and failure morphology.It provides an effective reference for the design and application of the 3D woven special⁃shaped square tubular composite.

Shell stand:Stable thin shell models for 3D fabrication

A thin shell model refers to a surface or structure,where the object’s thickness is considered negligible.In the context of 3D printing,thin shell models are characterized by having lightweight,hollow structures,and reduced material usage.Their versatility and visual appeal make them popular in various fields,such as cloth simulation,character skinning,and for thin-walled structures like leaves,paper,or metal sheets.Nevertheless,optimization of thin shell models without external support remains a challenge due to their minimal interior operational space.For the same reasons,hollowing methods are also unsuitable for this task.In fact,thin shell modulation methods are required to preserve the visual appearance of a two-sided surface which further constrain the problem space.In this paper,we introduce a new visual disparity metric tailored for shell models,integrating local details and global shape attributes in terms of visual perception.Our method modulates thin shell models using global deformations and local thickening while accounting for visual saliency,stability,and structural integrity.Thereby,thin shell models such as bas-reliefs,hollow shapes,and cloth can be stabilized to stand in arbitrary orientations,making them ideal for 3D printing.

Selection of digital fabrication technique in the construction industry--A multi-criteria decision-making approach

Digital fabrication techniques,in recent decades,have provided the basis of a sustainable revolution in the construction industry.However,selecting the digital fabrication method in terms of manufacturability and functionality requirements is a complex problem.This paper presents alternatives and criteria for selection of digital fabrication techniques by adopting the multi-criteria decision-making technique.The alternatives considered in the study are concrete three-dimensional(3D)printing,shotcrete,smart dynamic casting,material intrusion,mesh molding,injection concrete 3D printing,and thin forming techniques.The criteria include formwork utilization,reinforcement incorporation,geometrical complexity,material enhancement,assembly complexity,surface finish,and build area.It demonstrates different multi-criteria decision-making techniques,with both subjective and objective weighting methods.The given ranking is based on the current condition of digital fabrication in the construction industry.The study reveals that in the selection of digital fabrication techniques,the criteria including reinforcement incorporation,build area,and geometrical complexity play a pivotal role,collectively accounting for nearly 70% of the overall weighting.Among the evaluated techniques,concrete 3D printing emerged as the best performer,however the shotcrete and mesh molding techniques in the second and third positions.