操作压力和溶液组成对蛋白质在超滤过程中的膜污染的影响

研究了操作压力和溶液组成(溶质浓度、pH值和水质硬度)对牛血清蛋白在超滤过程中发生的膜污染的影响,同时使用扫描电子显微镜观察了实验所用的超滤膜的结构.研究发现,在膜过滤的过程中,存在着极限膜通量,增大操作压力和进水中蛋白质浓度只能加速膜污染的速度,但不能增强最后的膜污染程度;增大溶液的pH值,以及减小水质硬度,都能够减轻蛋白质在超滤过程中的膜污染程度.     

水相合成 CdS纳米晶标记牛血清白蛋白

利用水相中直接合成的CdS纳米晶，与牛血清白蛋白(BSA)进行偶连标记。通过分子筛层析对标记后的牛血清白蛋白进行纯化，在紫外灯下即可观察到标记蛋白的荧光。对CdS纳米晶标记后的牛血清白蛋白的荧光光谱的研究表明，标记蛋白后的CdS纳米晶其荧光无明显淬灭。     

基于牛血清白蛋白LB膜模板仿生合成碱式硝酸锌薄膜

结合仿生矿化的方法,通过牛血清白蛋白Langmuir膜板矢量控制和氨水动态控制相结合,合成了大面积连续致密具有(200)晶面取向的多孔Zn_5(OH)_8(NO_3)_2薄膜。经扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)及X射线光电子能谱分析仪(XPS)等测量手段,分析了Zn_5(OH)_8(NO_3)_2薄膜样品的表面形貌和结晶性能,并结合生物矿化原理推测了双重模板的控制机制。本文提供了一种全新的在室温下制备具有良好结晶度且适于大面积生产薄膜的方法。     

3D Nanofabrication of Fluidic Components by Corner Lithography

A reproducible wafer‐scale method to obtain 3D nanostructures is investigated. This method, called corner lithography, explores the conformal deposition and the subsequent timed isotropic etching of a thin film in a 3D shaped silicon template. The technique leaves a residue of the thin film in sharp concave corners which can be used as structural material or as an inversion mask in subsequent steps. The potential of corner lithography is studied by fabrication of functional 3D microfluidic components, in particular i) novel tips containing nano‐apertures at or near the apex for AFM‐based liquid deposition devices, and ii) a novel particle or cell trapping device using an array of nanowire frames. The use of these arrays of nanowire cages for capturing single primary bovine chondrocytes by a droplet seeding method is successfully demonstrated, and changes in phenotype are observed over time, while retaining them in a well‐defined pattern and 3D microenvironment in a flat array.     

Aesthetic reconstruction of microtia: a review of current techniques and new 3D printing approaches

Three dimensional (3D) printing and biofabrication technologies are revolutionising medicine with low-cost and novel treatments for complex medical conditions. These approaches differ from traditional treatments by using 3D scanning, computer modelling and 3D printing to automate the production of patient-specific tissue replacement or prostheses using a wide range of materials. One area impacted by this technology is the treatment of congenital maxillofacial conditions such as microtia, a condition affecting the intrauterine development of the auricle (external ear) and with a prevalence of 2.06 cases for every 10,000 births. While not life-threatening, microtia significantly impacts the emotional and psychological well-being of the affected child and their parents. Current treatments include the use of prosthetic ears or surgical methods such as autografting rib cartilage or alloplastic implants. Although current options have shown documented success, they are highly dependent on the surgeon’s skill and it has been demonstrated that poor quality solutions can further exacerbate negative psychosocial impacts. As such, higher quality, lower cost and more customised options would be welcomed by patients and parents alike. Recent advances in 3D scanning, modelling and printing techniques could significantly benefit the treatment and reconstructive options for children with microtia, leading to improved quality of life.     

Conductive 3D microstructures by direct 3D printing of polymer/carbon nanotube nanocomposites via liquid deposition modeling

In this work, a new three-dimensional (3D) printing system based on liquid deposition modeling (LDM) is developed for the fabrication of conductive 3D nanocomposite-based microstructures with arbitrary shapes. This technology consists in the additive multilayer deposition of polymeric nanocomposite liquid dispersions based on poly(lactic acid) (PLA) and multi-walled carbon nanotubes (MWCNTs) by means of a home-modified low-cost commercial benchtop 3D printer. Electrical and rheological measurements on the nanocomposite at increasing MWCNT and PLA concentrations are used to find the optimal processing conditions and the printability windows for these systems. In addition, examples of conductive 3D microstructures directly formed upon 3D printing of such PLA/MWCNT-based nanocomposite dispersions are presented. The results of our study open the way to the direct deposition of intrinsically conductive polymer-based 3D microstructures by means of a low-cost LDM 3D printing technique.     

Microscale 3D Printing of Nanotwinned Copper

Nanotwinned (nt)‐metals exhibit superior mechanical and electrical properties compared to their coarse‐grained and nanograined counterparts. nt‐metals in film and bulk forms are obtained using physical and chemical processes including pulsed electrodeposition (PED), plastic deformation, recrystallization, phase transformation, and sputter deposition. However, currently, there is no process for 3D printing (additive manufacturing) of nt‐metals. Microscale 3D printing of nt‐Cu is demonstrated with high density of coherent twin boundaries using a new room temperature process based on localized PED (L‐PED). The 3D printed nt‐Cu is fully dense, with low to none impurities, and low microstructural defects, and without obvious interface between printed layers, which overall result in good mechanical and electrical properties, without any postprocessing steps. The L‐PED process enables direct 3D printing of layer‐by‐layer and complex 3D microscale nt‐Cu structures, which may find applications for fabrication of metamaterials, sensors, plasmonics, and micro/nanoelectromechanical systems.     

甘油增韧淀粉/PLA易降解打印耗材的制备

采用甘油与PLA粉末在无水乙醇中预混合,80℃烘干后再加入淀粉进行双螺杆熔融共混,制备出淀粉含量为20%的甘油增韧淀粉/PLA复合材料。扫描电镜和拉曼光谱分析结果表明,采用该方法可使淀粉在PLA基体中均匀分布。力学性能测试显示,PLA拉伸强度、断裂延展率和弯曲强度均随淀粉含量增加而降低,但甘油含量为8%时淀粉/PLA复合材料的韧性明显提升。以甘油增韧的淀粉/PLA复合材料制成易降解FDM打印耗材,实际3D打印效果良好。     

Design of a 3D printed concrete bridge by testing*

The current state of research and development into the additive manufacturing of concrete is poised to become a disruptive technology in the construction industry. Although many academic and industrial institutions have successfully realised full-scale structures, the limitations in the current codes of practice to evaluate their structural integrity have resulted in most of these structures still not being certified as safe for public utilisation and thus deemed as test prototypes for display purpose only. To realise a 3D concrete printed (3DCP) structure which could be certified safe for public use, a bridge was realised using the print facility of the Eindhoven University of Technology (TU/e) based on the concept of ‘Design by Testing’. This paper holistically discusses the complications encountered while realising a reinforced 3DCP bridge in a public traffic network and decisions taken to find solutions for overcoming them.     

PBS增韧改性MWNTs/PLA导电3D 打印耗材的制备及性能

为解决多壁碳纳米管/聚乳酸(MWNTs/PLA)导电打印耗材变脆的问题,本文利用双螺杆熔融共混方法,制备了聚丁二酸丁二醇酯(PBS)增韧改性的MWNTs/PLA复合材料。研究发现,PBS添加量对复合材料的性能有显著影响。随PBS含量增加,复合材料的电阻率升高,断裂伸长率和冲击强度明显提高,但拉伸强度、弯曲强度和硬度有所降低。当PBS含量为10%时,共混复合材料的综合性能最好,并根据最佳条件制成具有一定韧性的导电3D打印耗材,实际使用效果良好。     

Mechanical,forming and biological properties of Ti-Fe-Zr-Y alloys prepared by 3D printing

Biomedical Ti-Fe-Zr-Y alloys were prepared by 3D printing on pure titanium substrate. The influences of Zr on mechanical, forming, and biological properties of the alloys were investigated in detail. The results showed that with increasing the Zr addition, the surface roughness, friction coefficient and worn volume decrease at first and then increase, the lowest values obtained at 5.86 at.% Zr addition. The ultimate compression stress and specific strength gradually decrease. The studied alloys have no cytotoxicity. They can promote the early adhesion and proliferation of cells. The eutectic alloy with 5.86 at.% Zr addition has the best ability of apatite deposition, it exhibits a better comprehensive performance among the studied alloys, which is superior to the Ti_70.5Fe_29.5 and Ti-6Al-4 V alloys.     

变论域模糊PID控制微流挤出型3D打印机的挤压力研究

为了提高微流挤出型3D打印机的打印精度,针对其挤压力控制在挤出成型过程中存在时变性和非线性等典型特性,基于挤压力模型分析打印材料的挤出成型过程,并提出了一种变论域模糊PID（proportion integration differentiation,比例积分微分）控制策略,以实现挤出成型过程中挤压力不规律变化时的快速调节功能。同时,利用MATLAB软件建立挤压力控制系统仿真模型以开展不同控制策略的仿真分析,并利用自主搭建的实验平台进行实物打印,以验证所提出控制策略的可行性。仿真和实验结果表明,变论域模糊PID控制策略对改善成型坯体表面质量和提高成型精度有显著效果。所提出的变论域模糊PID控制策略可为挤出型3D打印机挤压力的稳定控制提供一定参考,也可为类似时变和非线性控制系统提供一定的借鉴。     

Adsorption of BSA onto hexagonal mesoporous silicate loaded by APTES and tannin: Isotherm,thermodynamic and kinetic studies

In the present study, hexagonal mesoporous silica (HMS) was synthesized and modified by tannic acid as a natural poly-phenol and amine (TA-A-HMS) and was applied for the adsorption of bovine serum albumin (BSA) from aqueous media. To investigate the structure of HMS and TA-A-HMS, SEM, TEM, XRD, BET and FTIR analysis were applied. The effects of pH, adsorbent dosage, contact time and temperature on the BSA adsorption were studied. After modification, BET surface area of HMS was reduced from 885?m²/g to 51?m²/g which confirms the presence of tannin and amine groups that inhibit the adsorption of nitrogen molecules. According to the results of equilibrium data, it is shown that Langmuir isotherm with maximum adsorption capacity of 1000?mg/g is the predominant model and adsorption is mono-layer. Kinetic and thermodynamic studies also reveal that adsorption kinetic followed by pseudo-second order model and the adsorption process is exothermic.