Process,Material,and Regulatory Considerations for 3D Printed Medical Devices and Tissue Constructs

Three-dimensional(3D)printing is a highly automated platform that facilitates material deposition in a layer-by-layer approach to fabricate pre-defined 3D complex structures on demand.It is a highly promising technique for the fabrication of personalized medical devices or even patient-specific tissue constructs.Each type of 3D printing technique has its unique advantages and limitations,and the selection of a suitable 3D printing technique is highly dependent on its intended application.In this review paper,we present and highlight some of the critical processes(printing parameters,build orientation,build location,and support structures),material(batch-to-batch consistency,recycling,protein adsorption,biocompatibility,and degradation properties),and regulatory considerations(sterility and mechanical properties)for 3D printing of personalized medical devices.The goal of this review paper is to provide the readers with a good understanding of the various key considerations(process,material,and regulatory)in 3D printing,which are critical for the fabrication of improved patient-specific 3D printed medical devices and tissue constructs.

基于Construct 3的射击类游戏设计与开发——以飞机大战为例

Construct 3作为小而精的H5跨平台游戏引擎,强大的交互性和用户友好性使其在2D游戏开发方面独具优势。借助Construct 3重构经典射击类游戏“飞机大战”,通过Event Sheet实现游戏中背景循环滚动、动画导入、角色创建与随机运动、游戏难度控制、游戏变量控制等主要功能。经过测试,游戏可打包发布成Web、移动设备和PC端.exe格式,游戏交互、特效运行流畅,游戏变量与难度控制处于合理范围。

A new method of mesh simplification for 3-Dimension terrain using Laplace operator

This paper proposes a new method to simplify mesh in 3D terrain. The 3D terrain is presented by digital elevation model. First, Laplace operator is introduced to calculate sharp degree of mesh point, which indicates the variation trend of the terrain. Through setting a critical value of sharp degree, feature points are selected. Second, critical mesh points are extracted by an recursive process, and constitute the simplified mesh. Third, the algorithm of linear-square interpolation is employed to restore the characteris- tics of the terrain. Last, the terrain is rendered with color and texture. The experimental results demonstrate that this method can compress data by 16% and the error is lower than 10%.

Research on the Three-dimensional Modeling and Optimization of a Virtual Tower Crane Based on 3DS Max, Solidworks and EON Professional

Three-dimensional modeling of virtual hoisting machinery is the critical works to structure the system of virtual construction, and the foundation to realize intelligent and interactive virtual hoisting. Aimed at enhancing the requests of image quality and stability of the virtual construction scene, taking a tower crane for example. We studied the technology of three-dimensional modeling and optimization of a virtual tower crane, and a method named two-stage model optimization was put forward. This depended on the modeling stage using Solidworks and 3DS Max and the performance optimization stage in EON. The practice of software development indicates that the proposed methods of three-dimensional modeling and optimization could satisfy the performance request of virtual construction system and be popularized to other virtual system.

Three-Dimensional Visual Analysis for Construction Layout of Reservoir Project

It is difficult to analyze the inter-relationship for the construction layout of a reservoir project scientifically and intuitively.According to the characteristics of broad field and huge information,the modeling methods of digital terrain and solid model as well as the techniques of texture mapping and scene navigation are adopted.The simulation system is developed by C program language,which includes the functions of the interactive navigation of 3D scene,the visual inquiry of project digital model information,the storage and management of project information.A certain reservoir is taken as a case.The 3D visual analysis for the construction layout and engineering information are obtained.The proposed system is of great advantages in dealing with large amount of information and the method provides a theoretical basis and technical support for the construction layout of a reservoir project.

Joint 3D traveltime calculation based on fast marching method and wavefront construction

3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.

FeCl_(3)淋洗修复Pb-Ni复合污染土壤机制研究

Pb、Ni复合污染对土壤的危害大,协同修复难度高。本文以修复建设用地为目标,模拟配制了不同污染程度的Pb、Ni复合污染土壤,以FeCl_(3)为淋洗剂,考察淋洗时间、淋洗剂浓度和液固比等关键参数对Pb、Ni复合污染土壤的影响及其修复机制。结果表明:当FeCl_(3)浓度为0.6 mol/L,液固比为5∶1、淋洗时间为10 h时,Pb、Ni的淋洗效果最好,Pb低、中、高污染土壤的淋洗率分别为80.75%、89.32%和91.45%,Ni低、中、高污染土壤的淋洗率分别为77.31%、92.01%和96.29%;FeCl_(3)对Pb和Ni的快速反应阶段在0~4 h时间段内,至12 h时基本达到平衡。采用双常数和Elovich模型拟合淋洗动力学过程发现,FeCl_(3)对Pb和Ni的淋洗主要是非均相扩散过程;FeCl_(3)对Pb和Ni不同污染程度土壤的去除效果排序为高污染>中污染>低污染,对重金属的去除能力排序为Ni>Pb,FeCl_(3)可有效去除Pb和Ni的弱酸可溶态和可还原态。经FeCl_(3)淋洗后的土壤中Pb和Ni含量均低于第一类建设用地的管制值,对人体健康危害小。

NUMERICAL MODELLING OF THREE-DIMENSION CHARACTERISTICS OF WIND-DRIVEN CURRENT IN THE BOHAI SEA

Three- dimension (3-D) wind-driven currents in the Bohai Sea in both winter and summer are calculated by using a 3- D barotropic steady model, and the results are consistent with observed flow char -acteristics. Based on the results, 3- D characteristics of flow, currents at different depths, compensated flow in the lower layer , long and narrow alongshore current, the area of upwelling and downwelling, main circulation in vertical profile, and the current in Bohai Strait are discussed.

“新工科”背景下建筑设计人才“3+3+3”培养模式的建构

“新工科”国家战略的推动下,我国高等院校建筑人才培养面临新的挑战,建筑设计人才培养体系、培养质量与“新工科”建设愿景仍存在差距。该研究借鉴新加坡高等教育发展历程以及新加坡国立大学建筑设计人才培养内涵,探析如何在“新工科”背景下推动建筑设计人才培养模式的建构,以培养主体、培养途径、培养层级三要素为建筑设计人才培养框架,创新性提出“3+3+3”多层级建筑人才培养模式,以期为“新工科”战略的实施提供高素质建筑设计人才保障。

3D Finite Element Simulation of Tunnel Boring Machine Construction Processes in Deep Water Conveyance Tunnel

Applying stiffness migration method,a 3D finite element mechanical model is established to simulate the excavation and advance processes.By using 3D nonlinear finite element method,the tunnel boring machine(TBM) excavation process is dynamically simulated to analyze the stress and strain field status of surrounding rock and segment.The maximum tensile stress of segment ring caused by tunnel construction mainly lies in arch bottom and presents zonal distribution.The stress increases slightly and limitedly in the course of excavation.The maximum and minimum displacements of segment,manifesting as zonal distribution,distribute in arch bottom and vault respectively.The displacements slightly increase with the advance of TBM and gradually tend to stability.

Construction and visualization of 3D vacant place model

The method of building 3D model was discussed at first. Aiming at the feature of mine vacant place,a method to build the 3D vacant place model based on multi TIN (triangular irregular network) was put forward, and the data structure and visualization of vacant place were discussed. Then some crucial technologies of realizing function in 3D-GIS were proposed. In addition,the software about special 3D mapping and assaying was introduced.

Expression Vector Construction and Genetic Transformation of <i>Rosa rugosa β</i>-l,3-Glucanase Gene (<i>RrGlu</i>)

In order to lay a foundation for researching the function of Rosa rugose (R. rugosa) RrGlu gene, the RrGlu gene was amplified from the styles of R. rugosa “Tanghong”, a gene expression vector named PBI121-RrGlu was constructed and the vector was introduced into tobacco with the agrobacterium-mediated method. PCR results showed that the RrGlu gene was integrated into the tobacco genome.

Ex vivo 3D osteocyte network construction with primary murine bone cells

Osteocytes reside as three-dimensionally（3D） networked cells in the lacunocanalicular structure of bones and regulate bone and mineral homeostasis. Despite of their important regulatory roles, in vitro studies of osteocytes have been challenging because：（1） current cell lines do not sufficiently represent the phenotypic features of mature osteocytes and（2） primary cells rapidly differentiate to osteoblasts upon isolation. In this study, we used a 3D perfusion culture approach to：（1） construct the 3D cellular network of primary murine osteocytes by biomimetic assembly with microbeads and（2） reproduce ex vivo the phenotype of primary murine osteocytes, for the first time to our best knowledge. In order to enable 3D construction with a sufficient number of viable cells, we used a proliferated osteoblastic population of healthy cells outgrown from digested bone chips. The diameter of microbeads was controlled to：（1） distribute and entrap cells within the interstitial spaces between the microbeads and（2） maintain average cell-to-cell distance to be about 19 mm. The entrapped cells formed a 3D cellular network by extending and connecting their processes through openings between the microbeads. Also, with increasing culture time, the entrapped cells exhibited the characteristic gene expressions（SOST and FGF23） and nonproliferative behavior of mature osteocytes. In contrast, 2D-cultured cells continued their osteoblastic differentiation and proliferation. This 3D biomimetic approach is expected to provide a new means of：（1） studying flow-induced shear stress on the mechanotransduction function of primary osteocytes,（2） studying physiological functions of 3D-networked osteocytes with in vitro convenience,and（3） developing clinically relevant human bone disease models.

3D printing of functional bioengineered constructs for neural regeneration: a review

Three-dimensional(3D)printing technology has opened a new paradigm to controllably and reproducibly fabricate bioengineered neural constructs for potential applications in repairing injured nervous tissues or producing in vitro nervous tissue models.However,the complexity of nervous tissues poses great challenges to 3D-printed bioengineered analogues,which should possess diverse architectural/chemical/electrical functionalities to resemble the native growth microenvironments for functional neural regeneration.In this work,we provide a state-of-the-art review of the latest development of 3D printing for bioengineered neural constructs.Various 3D printing techniques for neural tissue-engineered scaffolds or living cell-laden constructs are summarized and compared in terms of their unique advantages.We highlight the advanced strategies by integrating topographical,biochemical and electroactive cues inside 3D-printed neural constructs to replicate in vivo-like microenvironment for functional neural regeneration.The typical applications of 3D-printed bioengineered constructs for in vivo repair of injured nervous tissues,bio-electronics interfacing with native nervous system,neural-on-chips as well as brain-like tissue models are demonstrated.The challenges and future outlook associated with 3D printing for functional neural constructs in various categories are discussed.

BeiDou-3 Global Positioning System Officially Initiates Construction

China’s Bei Dou-3 global positioning system has been officially initiated construction with four global networking satel ites to be launched by the end of this year,according to the announcement at the Sixth China Annual Meeting of Satellite Navigation and Location Services in Shenzhen on September 16 and the First Satellite Application International Exposition held.

基于Construct 3的益智类游戏设计与开发——以垃圾分类为例

借助Construct 3 H5游戏开发引擎,利用可视化的事件编程与场景制作方式,从框架设计、场景制作与界面交互设计三个方面进行了益智游戏垃圾分类PC、网页、移动端的设计与实现。玩家对随机生成的垃圾进行分类,并放置到指定的垃圾桶中,从而阻止垃圾飞到界面外而污染环境;让玩家在游戏中树立正确的环保意识,掌握垃圾分类的方法。测试结果表明,游戏可在PC、网页和移动端流畅运行;垃圾随机生成、点击拖拽、分类、重玩、关卡等功能良好;玩家生命值、环保积分、倒计时等全局变量参数正常。同时,呼吁研究者与开发者加强电子游戏的教育功能和社会责任。

Development of a 3D subcutaneous construct containing insulin-producing beta cells using bioprinting

Type 1 diabetes is caused by insulin deficiency due to the loss of beta cells in the islets of Langerhans.In severe cases,islet transplantation into the portal vein is performed.However,due to the loss of transplanted islets and the failure of islet function,the 5-year insulin independence rate of these patients is<50%.In this study,we developed a long-term,insulin-secreting,3 Dbioprinted construct implanted subcutaneously with the aim of preventing islet loss.The bioprinted construct was fabricated by the multi-layer bioprinting of beta-cell(mouse insulinoma-6:MIN-6)-encapsulated alginate bioink and poly(caprolactone)biodegradable polymer.A glucose response assay revealed that the bioprinted constructs proliferated and released insulin normally during the 4-week in vitro period.Bioprinted MIN-6 generated clusters with a diameter of 100-200μm,similar to the original pancreatic islets in the construct.In an in vivo study using type 1 diabetes mice,animals implanted with bioprinted constructs showed three times higher insulin secretion and controlled glucose levels at 8 weeks after implantation.Because the implanted,bioprinted constructs had a positive effect on insulin secretion in the experimental animals,the survival rate of the implanted group(75%)was three times higher than that of the non-implanted group(25%).The results suggest that the proposed,3 D-bioprinted,subcutaneous construct can be a better alternative to portal vein islet transplantation.

Construction of <i>k</i>-Variate Survival Functions with Emphasis on the Case <i>k</i>= 3

The purpose of this paper is to present a general universal formula for k-variate survival functions for arbitrary k = 2, 3, ..., given all the univariate marginal survival functions. This universal form of k-variate probability distributions was obtained by means of “dependence functions” named “joiners” in the text. These joiners determine all the involved stochastic dependencies between the underlying random variables. However, in order that the presented formula (the form) represents a legitimate survival function, some necessary and sufficient conditions for the joiners had to be found. Basically, finding those conditions is the main task of this paper. This task was successfully performed for the case k = 2 and the main results for the case k = 3 were formulated as Theorem 1 and Theorem 2 in Section 4. Nevertheless, the hypothetical conditions valid for the general k ≥ 4 case were also formulated in Section 3 as the (very convincing) Hypothesis. As for the sufficient conditions for both the k = 3 and k ≥ 4 cases, the full generality was not achieved since two restrictions were imposed. Firstly, we limited ourselves to the, defined in the text, “continuous cases” (when the corresponding joint density exists and is continuous), and secondly we consider positive stochastic dependencies only. Nevertheless, the class of the k-variate distributions which can be constructed is very wide. The presented method of construction by means of joiners can be considered competitive to the copula methodology. As it is suggested in the paper the possibility of building a common theory of both copulae and joiners is quite possible, and the joiners may play the role of tools within the theory of copulae, and vice versa copulae may, for example, be used for finding proper joiners. Another independent feature of the joiners methodology is the possibility of constructing many new stochastic processes including stationary and Markovian.

Dynamic Variation of Land-use Types of the Constructed Wetland before and after Oil-field Water Irrigation Based on 3S Technology

[Objective] The study aimed at analyzing the dynamic variation of land-use types of the constructed wetland before and after oil-field water irrigation based on 3S technology. [Method] At semi-arid and arid areas in the west of Jilin Province, water resource balance between the amount of oil-field water supply and ecological water requirement in the constructed wetland irrigated by oil-field water during 2001-2010 was investigated firstly. Afterwards, based on 3S technology, the partition and dynamic variation of land-use types of the constructed wetland before and after oil-field water irrigation in 2001, 2006, 2008 and 2010 were analyzed. [Result] The annual ecological water requirement of the constructed wetland from 2003 to 2010 varied from 1.62×106 to 2.24×106 m3, and the annual amount of oil-field water supply in the region changed from 2.12×106 to 2.84×106 m3, which showed that the supply amount of oil-field water could meet the basic ecological water requirement of the constructed wetland. Meanwhile, compared with 2001, the areas of water region and paddy field in 2010 increased by 2.3 and 10.0 times, and the areas of forest and marsh rose by 40.15% and 29.5.0% respectively. [Conclusion] Water shortage and ecological environment problem of arid and semi-arid areas had been improved by oil-field water irrigation.

Non Destructive 3D, 4D Microscopy and Mineral Phase Characterization in Industrial Minerals, Composites to Construction Materials

Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.