Understanding amorphous phase-change materials from the viewpoint of Maxwell rigidity

Phase-change materials (PCMs) are the subject of considerable interest because they have been recognized as potential active layers for next-generation non-volatile memory devices, known as Phase Change Random Access Memories (PRAMs). By analyzing First Principles Molecular Dynamics simulations we develop a new method for the enumeration of mechanical constraints in the amorphous phase and show that the phase diagram of the most popular system (Ge-Sb-Te) can be split into two compositional regions having a well-defined mechanical character: a Tellurium rich flexible phase, and a stressed rigid phase that encompasses the known PCMs. This sound atomic scale insight should open new avenues for the understanding of PCMs and other complex amorphous materials from the viewpoint of rigidity.Comment: 5 pages, 4 figures in EP

Design, Synthesis and Analysis of Self-Assembling Triangulated Wireframe DNA Structures

The field of DNA nanotechnology offers a wide range of design strategies with which nanometer-sized structures with a desired shape, size and aspect ratio can be built. The most established techniques in the field rely on close-packed 'solid' DNA nanostructures produced with either the DNA origami or the single-stranded tile techniques. These structures depend on high-salt buffer solutions and require more material than comparable size hollow wireframe structures. This dissertation explores the construction of hollow wireframe DNA nanostructures composed of equilateral triangles. To achieve maximal material efficiency the design is restricted to use a single DNA double helix per triangle edge. As a proof of principle, the DNA origami technique is extended to produce a series of truss structures including the flat, tetrahedral, octahedral, or irregular dodecahedral truss designs. In contrast to close packed DNA origami designs these structures fold at low-salt buffer conditions. These structures have defined cavities that may in the future be used to precisely position functional elements such as metallic nanoparticles or enzymes. The design process of these structures is simplified by a custom design software. Next, the triangulated construction motif is extended to the single-stranded DNA tile technique. A collection of finite structures, as well as one-dimensional crystalline assemblies is explored. The ideal assembly conditions are determined experimentally and using molecular dynamics simulations. A custom design software is presented to simplify the design and handling of these structures. At last, the cost-effective prototyping of triangulated wireframe DNA origami structures is explored. This is achieved through the introduction of single-stranded “gap” regions along the triangle edges. These gap regions are then filled using a DNA polymerase rather than by synthetic oligonucleotides. This technique also allows the mechanical transformation of these structures, which is exemplified by the transition of a bent into a straight structure upon completion of the gap filling.:Abstract v Publications vii Acknowledgements ix Contents xi Chapter 1 A short introduction into DNA nanotechnology 1 1.1 Nanotechnology 1 1.1.1 Top down 1 1.1.2 Bottom up 3 1.2 Deoxyribonucleic acid (DNA) 4 1.3 DNA Nanotechnology 6 1.3.1 Tile based assembly 9 1.3.2 DNA origami and single-stranded tiles 10 1.3.3 Some applications of DNA nanotechnology 12 1.3.4 Wireframe structures 15 1.3.5 Computational tools and DNA nanotechnology. 17 Chapter 2 Motivation and objectives 19 Chapter 3 Design and Synthesis of Triangulated DNA Origami Trusses 20 3.1 Introduction 20 3.2 Results and Discussion 21 3.2.1 Design 21 3.2.2 Nomenclature and parameters of the tube structures 23 3.2.3 Gel electrophoreses analysis 25 3.2.4 Imaging of the purified structures 26 3.2.5 Optimizing the folding conditions 28 3.2.6 Comparison to vHelix 29 3.3 Conclusions 29 3.4 Methods 30 3.4.1 Standard DNA origami assembly reaction. 30 3.4.2 Gel purification. 30 3.4.3 AFM sample preparation. 31 3.4.4 TEM sample preparation. 31 3.4.5 Instructions for mixing the staple sets. 31 Chapter 4 Triangulated wireframe structures assembled using single-stranded DNA tiles 33 4.1 Introduction 33 4.2 Results and Discussion 35 4.2.1 Designing the structures 35 4.2.2 Synthesis of test structures 37 4.2.3 Molecular dynamics simulations of 6-arm junctions 38 4.2.4 Assembly of the finite structures 40 4.2.5 Influence of salt concentration and folding times 42 4.2.6 Molecular dynamics simulations of the rhombus structure 43 4.2.7 1D SST crystals 44 4.2.8 Controlling the crystal growth 46 4.3 Conclusions 48 4.4 Methods 49 4.4.1 SST Folding 49 4.4.2 Agarose Gel Electrophoresis 49 4.4.3 tSEM Characterization 49 4.4.4 AFM Imaging 49 4.4.5 AGE-Based Folding-Yield Estimation 49 4.4.6 Molecular Dynamics Simulations 50 Chapter 5 Structural transformation of wireframe DNA origami via DNA polymerase assisted gap-filling 52 5.1 Introduction 52 5.2 Results and Discussion 54 5.2.1 Design of the Structures 54 5.2.2 Folding of Gap-Structures 56 5.2.3 Inactivation of Polymerase. 57 5.2.4 Secondary Structures. 58 5.2.5 Folding Kinetics of Gap Origami. 60 5.3 Conclusions 61 5.4 Methods 62 5.4.1 DNA origami folding 62 5.4.2 Gap filling of the wireframe DNA origami structures 63 5.4.3 Agarose gel electrophoresis 63 5.4.4 PAGE gel analysis 63 5.4.5 tSEM characterization 64 5.4.6 AFM imaging 64 5.4.7 AGE based folding-yield estimation 64 5.4.8 Gibbs free energy simulation using mfold 65 5.4.9 List of sequence for folding the DNA origami triangulated structures 65 Chapter 6 Summary and outlook 67 Appendix 69 A.1 Additional figures from chapter 369 A.2 Additional figures from chapter 4 77 A.3 Additional figures from chapter 5 111 Bibliography 127 Erklärung 13

Application of Spatial Structures in Bridges Deck

Spatial structure is a truss-like, lightweight and rigid structure with a regular geometric form. Usually from these structures is used in covering of long-span roofs. But these structures due to the lightness, ease and expedite of implementation are a suitable replacement for bridge deck. However steel and concrete is commonly used to build bridge deck, but heavy weight of steel and concrete decks and impossibility of making them as long-span bridge deck is caused engineers to thinks about new material that besides lightness and ease of implementation, provide an acceptable resistance against applied loads including both dead load and dynamic load caused by the passage of motor vehicles. Therefore, the purpose of this paper is design and analysis bridge deck that’s made of double-layer spatial frames compared with steel and concrete deck. Then allowable deflections due to dead and live loads, weight of bridge in any model and also economic and environmental aspects of this idea is checked. As a result, it can be said that the use of spatial structures in bridge deck is lead to build bridge with long spans, reducing the material and consequently reducing the structural weight and economic savings. For geometric shape of the spatial structure bridge is used of Formian 2.0 software and for analysis of bridges is used of SAP2000 with finite element method (FEM)

Design for Additive Manufacturing: Tool Review and a Case Study

This paper aims to collect in a structured manner different computer-aided engineering (CAE) tools especially developed for additive manufacturing (AM) that maximize the capabilities of this technology regarding product development. The flexibility of the AM process allows the manufacture of highly complex shapes that are not possible to produce by any other existing technology. This fact enables the use of some existing design tools like topology optimization that has already existed for decades and is used in limited cases, together with other novel developments like lattice design tools. These two technologies or design approaches demand a highly flexible manufacturing system to be applied and could not be used before, due to the conventional industrial process limitations. In this paper, these technologies will be described and combined together with other generic or specific design tools, introducing the study case of an additive manufactured mechanical design of a bicycle stem

Development of space truss systems in timber

Space trusses are a valuable structural form for architects and structural engineers due mainly to their efficiency in providing large unobstructed areas, associated with faster erection speeds and low maintenance cost. Most space trusses are made of steel and aluminium whilst a few are of timber. Interest is now shifting from the traditional use of timber in plane trusses of relatively short span, to new structural forms for medium to long spans. In adopting such systems in timber for non-traditional roofing applications, the challenge lies in developing structurally sound, visually neat and economically reproducible connectors for 3-dimensional configurations of timber members. The research aimed at developing a new connector for double and triple-layer space grids in timber, intended for medium-span lightweight roofing applications. The origins of the connector date back to 1995, when it was first proposed by Zingoni as the 14FTC-U Timber Space-Truss Connector, and subsequently tested under laboratory conditions over the three years that followed. Unlike connectors for timber space grids proposed by earlier investigators, or the proprietary connector systems that are available for constructions in steel and aluminium, the 14FTC-U connector features a central core of wood in the form of a cuboctahedron or its variants, upon whose faces are attached U-shaped metal brackets that take the timber members. Thus the connector unit is predominantly wood, giving it considerable aesthetic advantages over its all-metal counterparts. While promising, the structural performance of the original connector was not adequate for practical application, hence a programme of further development was embarked upon. As reported in the thesis, the improvements of the connector have culminated in a structurally viable unit that has been successfully employed in a prototype double-layer timber grid

The Z-octahedron family: a new tensegrity family

The present paper work was sent to Engineering Structures on 23 April 2020 (it is currently under review).A new family of tensegrity structures is presented: the Z-octahedron family. A tensegrity family is a group of tensegrity structures that share a common connectivity pattern. The members of the Z-octahedron family have been obtained replacing the elementary rhombic cells of the members of the octahedron family with elementary Z-shaped cells. In addition, a higher number of possible force density or force:length ratio values have been considered. The values of the force:length ratio of the members of the family that lead to super-stable tensegrity forms have been computed analytically. Two members of the family have been obtained: the Z-expanded octahedron and the Z-double-expanded octahedron. Finally it has been proved that the Z-double-expanded octahedron obtained here from topological rules can also be defined from a truncated cube based on purely geometrical intuition

Bipedal Isotropic Lattice Locomoting Explorer: Robotic Platform for Locomotion and Manipulation of Discrete Lattice Structures and Lightweight Space Structures

A robotic platform for traversing and manipulating a modular 3D lattice structure is described. The robot is designed specifically for its tasks within a structured environment, and is simplified in terms of its numbers of degrees of freedom (DOF). This allows for simpler controls and a reduction of mass and cost. Designing the robot relative to the environment in which it operates results in a specific type of robot called a "relative robot". Depending on the task and environment, there can be a number of relative robots. This invention describes a bipedal robot which can locomote across a periodic lattice structure made of building block parts. The robot is able to handle, manipulate, and transport these blocks when there is more than one robot. Based on a general inchworm design, the robot has added functionality while retaining minimal complexity, and can perform numerous maneuvers for increased speed, reach, and placement

Thinking through making : the rural building workshop

This thesis is about the link between thinking and making, and how designing and physically building or prototyping what is designed (or parts there of) aids in the generation of ideas, and has a potential for architectural education. The ideas that have transpired through the course of the year from building models and doing research for my theory and technology papers has led me in the direction of developing components and techniques for construction made from easily sourced tools and materials - ones from local industry and the landscape - that give rise to a tectonic expression as well as allows for an adaptable type of architecture. The methodology informing the design has therefore developed from the bottom up through the use of these components, as well as from the top down by means of a structural concept. The first part of the paper looks at the theory of making which deals with aspects of making in current society that I find relevant to this thesis. Part two and three of this paper is comprised of reciprocal components. Part two deals with the theory of structure and how my findings have helped guide the process of making, and have led to an appropriate structural system for my concept of a 'growing' or adaptable building. The third part of this paper describes the models I have built this year to illustrate the concept of 'techne', or the process of creation that is guided by the thing made, in order to demonstrate the qualities that materials possess, as well as how the act of making can be a design generator. It also describes how the initial stage of building models has led to the exploration of structural systems and components, and how models relating to the programme and site have been able to start informing the form of a building. The fourth and final part of this paper looks at the programme, site, and materiality of the 'Rural Building Workshop'