Positive direct-mask stereolithography with multiple-layer exposure: layered fabrication with stair step reduction

In this paper, we explain a new stereolithography involving the separate use of liquid photoinitiator and a base resin (photopolymer resin without photoinitiator). First, the base resin is supplied as a layer, and then a mask pattern is drawn onto the surface with photoinitiator by inkjet printing. When the surface is exposed to a UV lamp, only the pattern drawn with the photoinitiator is cured. In this process, the photoinitiator acts as a positive mask. Also, the idea of multiple-layer exposure, which may enable stair step reduction and fabrication time reduction, is introduced. The proposed idea and method are implemented in an experimental stereolithography system and some experiments are conducted using the system. As a result, the effectiveness and feasibility of the idea and method are confirmed.     

Gold nanoparticle-mediated fluorescence enhancement by two-photon polymerized 3D microstructures

Fluorescence enhancement achieved by functionalized microstructures made by two-photon polymerization (TPP) is reported for the first time. Microstructures of various shapes made of SU-8 photoresist were prepared and coated with gold nanoparticles (NP) of 80 nm. Localized fluorescence enhancement was demonstrated by microstructures equipped with tips of sub-micron dimensions. The enhancement was realized by positioning the NP-coated structures over fluorescent protein layers. Two fluorophores with their absorption in the red and in the green region of the VIS spectrum were used. Laser scanning confocal microscopy was used to quantify the enhancement. The enhancement factor was as high as 6 in areas of several square-micrometers and more than 3 in the case of local enhancement, comparable with literature values for similar nanoparticles. The structured pattern of the observed fluorescence intensity indicates a classic enhancement mechanism realized by standing waves over reflecting surfaces. With further development mobile microtools made by TPP and functionalized by metal NPs can be actuated by optical tweezers and position to any fluorescent micro-object, such as single cells to realize localized, targeted fluorescence enhancement.     

大跨度大截面吊车梁现场制作工艺

介绍STX（大连）重工5号弯曲分段工业厂房大跨度、大截面吊车梁现场制作,特别对大跨度、大截面吊车梁现场制作工艺及制作要求等方面进行详细阐述,为今后同类工程制作提供借鉴。     

Photonic crystal fibers for supercontinuum generation

Photonic crystal fibers (PCFs) present a wavelength-scale periodic microstructure along their length.Their core and two-dimensional photonic crystal might be based on varied geometries and materials,al...     

Alkaline aluminum phosphate glasses for thermal ion-exchanged optical waveguide

Alkaline aluminum phosphate glasses (NMAP) with excellent chemical durability for thermal ion-exchanged optical waveguide have been designed and investigated. The transition temperature Tg (470 °C) is higher than the ion-exchange temperature (390 °C), which is favorable to sustain the stability of the glass structure for planar waveguide fabrication. The effective diffusion coefficient D_e of K⁺–Na⁺ ion exchange in NMAP glasses is 0.110 μm²/min, indicating that ion exchange can be achieved efficiently in the optical glasses. Single-mode channel waveguide has been fabricated on Er³⁺/Yb³⁺ doped NMAP glass substrate by standard micro-fabrication and K⁺–Na⁺ ion exchange. The mode field diameter is 9.6 μm in the horizontal direction and 6.0 μm in the vertical direction, respectively, indicating an excellent overlap with a standard single-mode fiber. Judd–Ofelt intensity parameter Ω₂ is 5.47 × 10⁻²⁰ cm², implying a strong asymmetrical and covalent environment around Er³⁺ in the optical glasses. The full width at half maximum and maximum stimulated emission cross section of the ⁴I_13/2 → ⁴I_15/2 are 30 nm and 6.80 × 10⁻²¹ cm², respectively, demonstrating that the phosphate glasses are potential glass candidates in developing compact optoelectronic devices. Pr³⁺, Tm³⁺ and Ho³⁺ doped NMAP glasses are promising candidates to fabricate waveguide amplifiers and lasers operating at special telecommunication windows.     

Fab-Union: A Collective Online to Offline Robotic Design Platform

Official architectural education in China remains very traditional and has yet to engage with the digital age. To counter this, Shanghai-based Fab-Union was set up in 2014 to establish a cross-disciplinary community – now over 10,000 strong – that is driving the emergence of digital crafts in the country. Here, its founder Philip Yuan and lead designer Hao Meng describe Fab-Union's online design platform, its offline collective design space, and its robotic factory that functions as an open research facility and fabrication workshop.     

铁路斜拉桥钢桁梁桁片制作技术

合福铁路铜陵长江大桥主桥钢梁采用国内首次应用的整体桁片式结构设计,钢梁工厂制作、桥位安装。我国铁路钢桥从散拼杆件制作向整体节点杆件和桁片制作发展,钢桥建造逐步走向大型化、工厂化,技术水平稳步提高。总结了铜陵公、铁两用斜拉桥钢桁梁桁片制作技术,可为我国铁路钢桥向大型化、工厂化发展提供一些借鉴。     

金属颗粒冷态高速微喷射增材制造工艺研究

针对金属零件三维自由直接成形工艺中普遍存在的高能耗、高热残余应力等问题,提出了金属颗粒冷态高速微喷射增材制造新工艺。以常温下的高压氮气作为加速气流,利用微喷枪将微米级的金属粒子加速至其临界速度以上形成沉积。针对高速微喷射增材制造平台搭建、具有高加速性能与高分辨率的微喷枪设计展开了研究,并在此基础上,进行了单点成形与单线成形的试验研究,通过最小特征尺寸的大小与稳定度分析新工艺成形精度与成形质量,通过微观结构与显微硬度分析新工艺成形件的基本力学性能。试验结果表明:在一定范围内,通过喷射压力的变化可以实现单点成形尺寸的线性可控,通过喷射压力与导轨移动速度可以实现直线成形线宽与层厚的线性可控;试验中的0.9 mm的最窄线宽与低于8%的线宽波动量保证了该工艺一定的加工精度与成形质量;致密的微观组织结构与较高的显微硬度值保证了该工艺成形件良好的力学性能;多层扫描时层与层之间致密结合保证了该工艺逐层累加制造的能力。研究表明,金属颗粒冷态高速微喷射是一种稳定可控,可行的增材制造新工艺。     

2m大口径RB-SiC反射镜的磁控溅射改性

为了消除RB-SiC反射镜直接抛光后表面存在的微观缺陷,降低抛光后表面的粗糙度,提高表面质量,针对大口径SiC的特性,选择Si作为改性材料,利用磁控溅射技术对2m量级RB-SiC基底进行了表面改性。在自主研发的Φ3.2m的磁控溅射镀膜机上进行基底镀膜,利用计算机控制光学成型法对SiC基底进行了抛光改性。实验结果表明,改性层厚度达到15μm;在直径2.04m范围内,膜层厚度均匀性优于±2.5%;表面粗糙度由直接抛光的5.64nm(RMS)降低到0.78nm。由此说明磁控溅射技术能够用于大口径RB-SiC基底的表面改性,并且改性后大口径RB-SiC的性能可以满足高质量光学系统的要求。     

应用于固体推进剂的石墨烯及其复合材料制备技术研究进展

系统介绍了多种石墨烯的制备、改性和复合方法,制备方法主要有机械剥离和湿法剥离,改性方法主要有非共价改性和共价改性,复合方法主要有非原位合成和原位合成。从石墨烯在固体推进剂中应用的角度分析比较了不同制备方法的优缺点,指出今后用作燃烧催化剂的石墨烯及其复合材料的制备技术重点应集中在如下几方面:(1)将微乳液法等纳米材料制备方法应用于石墨烯复合材料制备中;(2)应加强负载有机金属盐和含能催化剂的石墨烯负载型燃烧催化剂的研究;(3)开展石墨烯负载物的晶体生长研究。附参考文献57篇。