scholarly journals Complex three-dimensional graphene structures driven by surface functionalization

Nanoscale ◽  
2020 ◽  
Vol 12 (18) ◽  
pp. 10172-10179 ◽  
Author(s):  
Duc Tam Ho ◽  
Viet Hung Ho ◽  
Vasudeo Babar ◽  
Sung Youb Kim ◽  
Udo Schwingenschlögl
Keyword(s):  
Surface Functionalization ◽  
Three Dimensional ◽  
Form Complex ◽  
Graphene Structures

A self-folding approach inspired by the origami technique is developed to form complex three-dimensional graphene structures using pattern-based surface functionalization.

scholarly journals Escherichia coli Harboring a Natural IncF Conjugative F Plasmid Develops Complex Mature Biofilms by Stimulating Synthesis of Colanic Acid and Curli

2008 ◽  
Vol 190 (22) ◽  
pp. 7479-7490 ◽  
Author(s):  
Thithiwat May ◽  
Satoshi Okabe
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Three Dimensional ◽  
F Plasmid ◽  
Form Complex ◽  
Global Regulators ◽  
E Coli ◽  
Colanic Acid ◽  
Regulatory Systems ◽  
Initial Deposition

ABSTRACT It has been shown that Escherichia coli harboring the derepressed IncFI and IncFII conjugative F plasmids form complex mature biofilms by using their F-pilus connections, whereas a plasmid-free strain forms only patchy biofilms. Therefore, in this study we investigated the contribution of a natural IncF conjugative F plasmid to the formation of E. coli biofilms. Unlike the presence of a derepressed F plasmid, the presence of a natural IncF F plasmid promoted biofilm formation by generating the cell-to-cell mating F pili between pairs of F+ cells (approximately two to four pili per cell) and by stimulating the formation of colanic acid and curli meshwork. Formation of colanic acid and curli was required after the initial deposition of F-pilus connections to generate a three-dimensional mushroom-type biofilm. In addition, we demonstrated that the conjugative factor of F plasmid, rather than a pilus synthesis function, was involved in curli production during biofilm formation, which promoted cell-surface interactions. Curli played an important role in the maturation process. Microarray experiments were performed to identify the genes involved in curli biosynthesis and regulation. The results suggested that a natural F plasmid was more likely an external activator that indirectly promoted curli production via bacterial regulatory systems (the EnvZ/OmpR two-component regulators and the RpoS and HN-S global regulators). These data provided new insights into the role of a natural F plasmid during the development of E. coli biofilms.

A Method for Fabrication of Polycarbonate-Based Bioactive Platforms

2008 ◽  
Vol 13 (5) ◽  
pp. 284-288 ◽  
Author(s):  
Peyman Najmabadi ◽  
Kwang-Seuk Ko ◽  
James J. La Clair ◽  
Michael D. Burkart
Keyword(s):  
Monoclonal Antibody ◽  
Surface Functionalization ◽  
Three Dimensional ◽  
Compression Molding ◽  
Chemical Derivatization ◽  
Proof Of Concept ◽  
Hot Press ◽  
Site Specific ◽  
Molecular Receptors ◽  
Three Dimensional Objects

Surface-based assays have been used extensively for the functional and structural analysis of biomolecules such as DNA or proteins. These experiments are established by the analysis of binding between acceptor molecules and immobilized receptors on a platform. Site-specific printing of receptor molecules on gold, glass, or polycarbonate (PC) surfaces is conventionally performed by the chemical derivatization of a surface, priming it to covalently bind to subsequently deposited receptor molecules. Unlike conventional methods, we have developed a new fabrication method for bioactive PC surfaces by directly molding PC granules doped with receptor molecules. PC-based receptor molecules were synthesized and commercially available PC granules were doped with these synthesized molecules. In our proof-of-concept study, PC doped with dye 1 ( Fig. 1 ) was used as the receptor molecule. Using an aluminum mold and a hot press machine, PC-based objects were manufactured through compression molding using doped PC granules. Affinity analysis was evaluated by monitoring the localization of a monoclonal antibody elicited against dye 1 to the surface of the molded platforms by fluorescence microscopy. The results illustrated effective binding of an anti-dye 1 monoclonal antibody to the surface, substantiating successful display of assemblies of molecular receptors on the surface through compression molding. Although conventional surface functionalization methods impose limited applications and alter desired opto-mechanical properties of the polymer, our investigation provides a versatile means for the fabrication of bioactive PC-based platforms. It can also be used for engineering and imbedding receptor arrays within three-dimensional objects with applications to the production of opto-medical devices or biosensors.

Three-Dimensional Numerical Simulation and Experimental Study of Sheet Metal Bending by Laser Peen Forming

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Yongxiang Hu ◽  
Yefei Han ◽  
Zhenqiang Yao ◽  
Jun Hu
Keyword(s):  
Numerical Model ◽  
Sheet Metal ◽  
Laser Energy ◽  
Three Dimensional ◽  
Target Surface ◽  
Thick Sheet ◽  
Specimen Thickness ◽  
Forming Process ◽  
Form Complex ◽  
Peen Forming

Laser peen forming (LPF) is a purely mechanical forming method achieved through the use of laser energy to form complex shapes or to modify curvatures. It is flexible and independent of tool inaccuracies that result from wear and deflection. Its nonthermal process makes it possible to form without material degradation or even improve them by inducing compressive stress over the target surface. In the present study, a fully three-dimensional numerical model is developed to simulate the forming process of laser peen forming. The simulation procedure is composed of several steps mainly including the shock pressure prediction, the modal analysis, and the forming process calculation. System critical damping is introduced to prevent unnecessary long post-shock residual oscillations and to greatly decrease the solution time for simulation. The bending profiles and angles with different thicknesses are experimentally measured at different scanning lines and scanning velocities to understand the process and validate the numerical model. The calculated bending profiles and angles agree well with the trend of the measured results. But it is found that simulations with the Johnson–Cook model are more consistent, matching the experimental results for the thick sheet metal with a convex bending, while the elastic-perfectly-plastic model produces a better agreement even though with underestimated values for the thinner sheet metal with a concave bending. The reason for this phenomenon is discussed, combining the effects of strain rate and feature size. Both the simulation and the experiments show that a continuous decrease in bending angle from concave to convex is observed with increasing specimen thickness in general. Large bending distortion is easier to induce by generating a concave curvature with LPF, and the angle of bending distortion depends on the number of laser shocks.

scholarly journals APPLICATION OF ADDITIVE TECHNOLOGIES IN CONSTRUCTION AND IN THE PRODUCTION OF CERAMIC PRODUCTS

2020 ◽  
pp. 134-141
Author(s):  
N. Kirillova ◽  
A. Alekseeva ◽  
A. Egorova
Keyword(s):  
3D Printing ◽  
Raw Materials ◽  
Three Dimensional ◽  
Additive Technologies ◽  
High Temperature Strength ◽  
Form Complex ◽  
Advantages And Disadvantages ◽  
Analytical Review ◽  
3D Printers ◽  
The Republic

Additive technologies that allow creating volume objects of different complexity are becoming popular in different industries. There is an increase in the scale of introduction of 3D printing technologies in the construction industry, including in the production of ceramic products. With the help of modern additive technologies, different models, products and designs are created. They can be complex and can be made from different materials. Experts are wondering what the future holds for additive technologies in construction, as well as in ceramic production, as these technologies can save resources, reduce the time of the technological process and form complex shapes. The article presents an analytical review of the global application of additive technologies in construction, as well as in the manufacture of ceramic products. The advantages and disadvantages, the possibilities of 3D printing are considered. The creation of ceramic three-dimensional products is still a rare area of additive technologies that requires research. The production of ceramic products, superior to other materials in terms of high temperature strength, hardness, chemical and thermal resistance, has a high potential for the use of additive technologies. The types of construction 3D printers and raw materials for them are analyzed. The results of a study of the properties of clay raw materials of the Sannikovsky, Namtsyrsky and Kangalassky deposits of the Republic of Sakha (Yakutia) are presented.

Self-Contained Three-Dimensional Bioprinter for Applications in Cardiovascular Research

2019 ◽  
Vol 13 (3) ◽  
Author(s):  
Prabhuti Kharel ◽  
Likitha Somasekhar ◽  
Amy Vecheck ◽  
Kunal Mitra
Keyword(s):  
Functional Characterization ◽  
Three Dimensional ◽  
Environmental Parameters ◽  
3D Bioprinting ◽  
Cardiovascular Research ◽  
Form Complex ◽  
Tissue Constructs ◽  
Long Duration ◽  
Selection Of

Bioprinting is a technique of creating 3D cell-laden structures by accurately dispensing biomaterial to form complex synthetic tissue. The printed constructs aim to mimic the native tissue by preserving the cell functionality and viability within the printed structure. The 3D bioprinting system presented in this paper aims to facilitate the process of 3D bioprinting through its ability to control the environmental parameters within an enclosed printing chamber. This design of the bioprinter targets to eliminate the need for a laminar flow hood, by regulating the necessary environmental conditions important for cell survival, especially during long duration prints. A syringe-based extrusion (SBE) deposition method comprising multiple nozzles is integrated into the system. This allows for a wider selection of biomaterials that can be used for the formation of the extracellular matrix (ECM). Tissue constructs composed of alginate-gelatin hydrogels were mixed with fibrinogen and human endothelial cells which were then characterized and compared using two methodologies: casted and bioprinted. Furthermore, vasculature was incorporated in the bioprinted constructs using sacrificial printing. Structural and functional characterization of the constructs were performed by assessing rheological, mechanical properties, and analyzing live-dead assay measurements.

Functional self-assembling polypeptide bionanomaterials

2012 ◽  
Vol 40 (4) ◽  
pp. 629-634 ◽  
Author(s):  
Tibor Doles ◽  
Sabina Božič ◽  
Helena Gradišar ◽  
Roman Jerala
Keyword(s):  
Self Assembly ◽  
Biological Systems ◽  
Three Dimensional ◽  
Coiled Coil ◽  
Chemical Properties ◽  
Building Blocks ◽  
External Signal ◽  
Form Complex ◽  
Cell Factories ◽  
Self Assembling

Bionanotechnology seeks to modify and design new biopolymers and their applications and uses biological systems as cell factories for the production of nanomaterials. Molecular self-assembly as the main organizing principle of biological systems is also the driving force for the assembly of artificial bionanomaterials. Protein domains and peptides are particularly attractive as building blocks because of their ability to form complex three-dimensional assemblies from a combination of at least two oligomerization domains that have the oligomerization state of at least two and three respectively. In the present paper, we review the application of polypeptide-based material for the formation of material with nanometre-scale pores that can be used for the separation. Use of antiparallel coiled-coil dimerization domains introduces the possibility of modulation of pore size and chemical properties. Assembly or disassembly of bionanomaterials can be regulated by an external signal as demonstrated by the coumermycin-induced dimerization of the gyrase B domain which triggers the formation of polypeptide assembly.

Nonlinear Spatial Equilibria and Stability of Cables Under Uni-axial Torque and Thrust

1994 ◽  
Vol 61 (4) ◽  
pp. 879-886 ◽  
Author(s):  
C.-L. Lu ◽  
N. C. Perkins
Keyword(s):  
Closed Form ◽  
Elliptic Integral ◽  
Broad Class ◽  
Local Equilibrium ◽  
Three Dimensional ◽  
Equilibrium States ◽  
Form Complex ◽  
Closed Form Solutions ◽  
The Stability ◽  
Low Tension

Low tension cables subject to torque may form complex three-dimensional (spatial) equilibria. The resulting nonlinear static deformations, which are dominated by cable flexure and torsion, may produce interior loops or kinks that can seriously degrade the performance of the cable. Using Kirchhoffrod assumptions, a theoretical model governing cable flexure and torsion is derived herein and used to analyze (1) globally large equilibrium states, and (2) local equilibrium stability. For the broad class of problems described by pure boundary loading, the equilibrium boundary value problem is integrable and admits closed-form elliptic integral solutions. Attention is focused on the example problem of a cable subject to uni-axial torque and thrust. Closed-form solutions are presented for the complex three-dimensional equilibrium states which, heretofore, were analyzed using purely numerical methods. Moreover, the stability of these equilibrium states is assessed and new and important stability conclusions are drawn.

A new approach to construct three dimensional segregated graphene structures in rubber composites for enhanced conductive, mechanical and barrier properties

2016 ◽  
Vol 4 (12) ◽  
pp. 2353-2358 ◽  
Author(s):  
Yong Lin ◽  
Shuqi Liu ◽  
Lan Liu
Keyword(s):  
Three Dimensional ◽  
Barrier Properties ◽  
Construction Method ◽  
Rubber Composites ◽  
New Approach ◽  
3D Graphene ◽  
Conductive Rubber ◽  
First Time ◽  
Graphene Structures

A novel pre-construction method was reported for the first time to fabricate conductive rubber composites with a conductive 3D-graphene segregated network.

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