scholarly journals Silica core–polystyrene shell nanoparticle synthesis and assembly in three dimensions

Nanoscale ◽  
2015 ◽  
Vol 7 (45) ◽  
pp. 19036-19046 ◽  
Author(s):  
Hadi Sabouri ◽  
Yun Huang ◽  
Kohji Ohno ◽  
Sébastien Perrier
Keyword(s):  
Silica Nanoparticles ◽  
Three Dimensional ◽  
Colloidal Crystals ◽  
Nanoparticle Synthesis ◽  
Building Blocks ◽  
Three Dimensions ◽  
Monodisperse Silica ◽  
Silica Core

Monodisperse silica nanoparticles (SiNPs) grafted with well-defined and highly dense polystyrene brushes are used as building blocks for the formation of three-dimensional (3D) colloidal crystals.

scholarly journals Templated Synthesis and Assembly of Two-, Three- and Six-Patch Silica Nanoparticles with a Controlled Patch-to-Particle Size Ratio

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4736
Author(s):  
Bin Liu ◽  
Stéphanie Exiga ◽  
Etienne Duguet ◽  
Serge Ravaine
Keyword(s):  
Particle Size ◽  
Silica Nanoparticles ◽  
Self Assembly ◽  
Three Dimensional ◽  
Nanoparticle Synthesis ◽  
Polymer Chains ◽  
Size Ratio ◽  
Particle Size Ratio ◽  
Silica Core ◽  
Future Work

We report a fabrication route of silica nanoparticles with two, three or six patches with an easily tunable patch-to-particle size ratio. The synthetic pathway includes two main stages: the synthesis of silica/polystyrene multipod-like templates and the selective growth of their silica core through an iterative approach. Electron microscopy of the dimpled nanoparticles obtained after dissolution of the polystyrene nodules of the multipod-like nanoparticles provides evidence of the conformational growth of the silica core. Thanks to the presence of some polymer chains, which remained grafted at the bottom of the dimples after the dissolution of the PS nodules, the solvent-induced assembly of the patchy nanoparticles is performed. Chains, hexagonal suprastructures and cubic lattices are obtained from the assembly of two-, three- and six-patch silica nanoparticles, respectively. Our study can guide future work in both patchy nanoparticle synthesis and self-assembly. It also opens new routes towards the fabrication of specific classes of one-, two- and three-dimensional colloidal lattices, including complex tilings.

Three-Dimensional Massively Parallel Computing of Suspensions

1998 ◽  
Vol 09 (05) ◽  
pp. 759-775 ◽  
Author(s):  
B. Wachmann ◽  
S. Schwarzer
Keyword(s):  
Parallel Implementation ◽  
Brownian Particle ◽  
Particle Surface ◽  
Three Dimensional ◽  
Building Blocks ◽  
Liquid Mixtures ◽  
Three Dimensions ◽  
Navier Stokes ◽  
Particle Volume ◽  
Slip Boundary

Numerical simulations of suspensions often suffer from the fact that the simulated systems are rather small compared to experimental setups. We present a numerical scheme for non-Brownian particle-liquid mixtures in three dimensions at particle Reynolds numbers between 0.01 and 20 and describe its parallel implementation. The fluid equations are solved by a time-explicit pressure-implicit Navier–Stokes algorithm and the particle motion is tracked by molecular-dynamics methods. The two are coupled by imposing no-slip boundary conditions between the particles and the fluid. We integrate the stress distribution on the particle surface numerically to obtain forces and torques. The building blocks of the algorithm are local and scalable and we have reached particle numbers up to 106 (1.41*108 fluid nodes) on a 512 node CRAY-T3E. We compare our simulation results to theoretical predictions and experimental data and find good agreement for particle volume fractions up to 0.30.

Three-dimensional cell culture of chondrocytes on modified di-phenylalanine scaffolds

2007 ◽  
Vol 35 (3) ◽  
pp. 535-537 ◽  
Author(s):  
V. Jayawarna ◽  
A. Smith ◽  
J.E. Gough ◽  
R.V. Ulijn
Keyword(s):  
Electron Microscopy ◽  
Cell Culture ◽  
Cell Proliferation ◽  
Self Assembly ◽  
Three Dimensional ◽  
Building Blocks ◽  
Culture Conditions ◽  
The Self ◽  
Three Dimensions ◽  
Dimensional Cell

The design of self-assembled peptide-based structures for three-dimensional cell culture and tissue repair has been a key objective in biomaterials science for decades. In search of the simplest possible peptide system that can self-assemble, we discovered that combinations of di-peptides that are modified with aromatic stacking ligands could form nanometre-sized fibres when exposed to physiological conditions. For example, we demonstrated that a number of Fmoc (fluoren-9-ylmethyloxycarbonyl) modified di- and tri-peptides form highly ordered hydrogels via hydrogen-bonding and π–π interactions from the fluorenyl rings. These highly hydrated gels allowed for cell proliferation of chondrocytes in three dimensions [Jayawarna, Ali, Jowitt, Miller, Saiani, Gough and Ulijn (2006) Adv. Mater. 18, 611–614]. We demonstrated that fibrous architecture and physical properties of the resulting materials were dictated by the nature of the amino acid building blocks. Here, we report the self-assembly process of three di-phenylalanine analogues, Fmoc-Phe-Phe-OH, Nap (naphthalene)-Phe-Phe-OH and Cbz (benzyloxycarbonyl)-Phe-Phe-OH, to compare and contrast the self-assembly properties and cell culture conditions attributable to their protecting group difference. Fibre morphology analysis of the three structures using cryo-SEM (scanning electron microscopy) and TEM (transmission electron microscopy) suggested fibrous structures with dramatically varying fibril dimensions, depending on the aromatic ligand used. CD and FTIR (Fourier-transform IR) data confirmed β-sheet arrangements in all three samples in the gel state. The ability of these three new hydrogels to support cell proliferation of chondrocytes was confirmed for all three materials.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

scholarly journals Lath Martensite Microstructure Modeling: A High-Resolution Crystal Plasticity Simulation Study

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 691
Author(s):  
Francisco-José Gallardo-Basile ◽  
Yannick Naunheim ◽  
Franz Roters ◽  
Martin Diehl
Keyword(s):  
High Resolution ◽  
Mechanical Behavior ◽  
Crystal Plasticity ◽  
Lath Martensite ◽  
Three Dimensional ◽  
Building Blocks ◽  
Quantitative Agreement ◽  
Carbon Steels ◽  
Plastic Behavior ◽  
Austenitic Phase

Lath martensite is a complex hierarchical compound structure that forms during rapid cooling of carbon steels from the austenitic phase. At the smallest, i.e., ‘single crystal’ scale, individual, elongated domains, form the elemental microstructural building blocks: the name-giving laths. Several laths of nearly identical crystallographic orientation are grouped together to blocks, in which–depending on the exact material characteristics–clearly distinguishable subblocks might be observed. Several blocks with the same habit plane together form a packet of which typically three to four together finally make up the former parent austenitic grain. Here, a fully parametrized approach is presented which converts an austenitic polycrystal representation into martensitic microstructures incorporating all these details. Two-dimensional (2D) and three-dimensional (3D) Representative Volume Elements (RVEs) are generated based on prior austenite microstructure reconstructed from a 2D experimental martensitic microstructure. The RVEs are used for high-resolution crystal plasticity simulations with a fast spectral method-based solver and a phenomenological constitutive description. The comparison of the results obtained from the 2D experimental microstructure and the 2D RVEs reveals a high quantitative agreement. The stress and strain distributions and their characteristics change significantly if 3D microstructures are used. Further simulations are conducted to systematically investigate the influence of microstructural parameters, such as lath aspect ratio, lath volume, subblock thickness, orientation scatter, and prior austenitic grain shape on the global and local mechanical behavior. These microstructural features happen to change the local mechanical behavior, whereas the average stress–strain response is not significantly altered. Correlations between the microstructure and the plastic behavior are established.

scholarly journals 22.F. Workshop: What makes for resilient health systems? Evidence from the State of Health in the EU country profiles

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
◽  
Keyword(s):  
Health System ◽  
Health Systems ◽  
Building Blocks ◽  
The State ◽  
Lessons Learned ◽  
Three Dimensions ◽  
Health System Strengthening ◽  
New Work ◽  
State Of Health ◽  
The Eu

Abstract The European Commission's State of Health in the EU (SoHEU) initiative aims to provide factual, comparative data and insights into health and health systems in EU countries. The resulting Country Health Profiles, published every two years (current editions: November 2019) are the joint work of the European Observatory on Health Systems and Policies and the OECD, in cooperation with the European Commission. They are designed to support the efforts of Member States in their evidence-based policy making and to contribute to health care systems' strengthening. In addition to short syntheses of population health status, determinants of health and the organisation of the health system, the Country Profiles provide an assessment of the health system, looking at its effectiveness, accessibility and resilience. The idea of resilient health systems has been gaining traction among policy makers. The framework developed for the Country Profiles template sets out three dimensions and associated policy strategies and indicators as building blocks for assessing resilience. The framework adopts a broader definition of resilience, covering the ability to respond to extreme shocks as well as measures to address more predictable and chronic health system strains, such as population ageing or multimorbidity. However, the current framework predates the onset of the novel coronavirus pandemic as well as new work on resilience being done by the SoHEU project partners. This workshop aims to present resilience-enhancing strategies and challenges to a wide audience and to explore how using the evidence from the Country Profiles can contribute to strengthening health systems and improving their performance. A brief introduction on the SoHEU initiative will be followed by the main presentation on the analytical framework on resilience used for the Country Profiles. Along with country examples, we will present the wider results of an audit of the most common health system resilience strategies and challenges emerging from the 30 Country Profiles in 2019. A roundtable discussion will follow, incorporating audience contributions online. The Panel will discuss the results on resilience actions from the 2019 Country Profiles evidence, including: Why is resilience important as a practical objective and how is it related to health system strengthening and performance? How can countries use their resilience-related findings to steer national reform efforts? In addition, panellists will outline how lessons learned from country responses to the Covid-19 pandemic and new work on resilience by the Observatory (resilience policy briefs), OECD (2020 Health at a Glance) and the EC (Expert Group on Health Systems Performance Assessment (HSPA) Report on Resilience) can feed in and improve the resilience framework that will be used in the 2021 Country Profiles. Key messages Knowing what makes health systems resilient can improve their performance and ability to meet the current and future needs of their populations. The State of Health in the EU country profiles generate EU-wide evidence on the common resilience challenges facing countries’ health systems and the strategies being employed to address them.

scholarly journals Free partition functions and an averaged holographic duality

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Nima Afkhami-Jeddi ◽  
Henry Cohn ◽  
Thomas Hartman ◽  
Amirhossein Tajdini
Keyword(s):  
Partition Function ◽  
Spectral Gap ◽  
Central Charge ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Partition Functions ◽  
General Constraints ◽  
Dimensional Gravity ◽  
Holographic Duality

Abstract We study the torus partition functions of free bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity with U(1)c×U(1)c symmetry and a composite boundary graviton. Additionally, for small central charge c, we obtain general constraints on the spectral gap of free CFTs using the spinning modular bootstrap, construct examples of Narain compactifications with a large gap, and find an analytic bootstrap functional corresponding to a single self-dual boson.

Turbulent three-dimensional dielectric electrohydrodynamic convection between two plates

2012 ◽  
Vol 696 ◽  
pp. 228-262 ◽  
Author(s):  
A. Kourmatzis ◽  
J. S. Shrimpton
Keyword(s):  
Spatial Data ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Energy Budgets ◽  
Turbulent Regime ◽  
Scalar Flux ◽  
Wide Range ◽  
Scalar Variance

AbstractThe fundamental mechanisms responsible for the creation of electrohydrodynamically driven roll structures in free electroconvection between two plates are analysed with reference to traditional Rayleigh–Bénard convection (RBC). Previously available knowledge limited to two dimensions is extended to three-dimensions, and a wide range of electric Reynolds numbers is analysed, extending into a fully inherently three-dimensional turbulent regime. Results reveal that structures appearing in three-dimensional electrohydrodynamics (EHD) are similar to those observed for RBC, and while two-dimensional EHD results bear some similarities with the three-dimensional results there are distinct differences. Analysis of two-point correlations and integral length scales show that full three-dimensional electroconvection is more chaotic than in two dimensions and this is also noted by qualitatively observing the roll structures that arise for both low (${\mathit{Re}}_{E} = 1$) and high electric Reynolds numbers (up to ${\mathit{Re}}_{E} = 120$). Furthermore, calculations of mean profiles and second-order moments along with energy budgets and spectra have examined the validity of neglecting the fluctuating electric field ${ E}_{i}^{\ensuremath{\prime} } $ in the Reynolds-averaged EHD equations and provide insight into the generation and transport mechanisms of turbulent EHD. Spectral and spatial data clearly indicate how fluctuating energy is transferred from electrical to hydrodynamic forms, on moving through the domain away from the charging electrode. It is shown that ${ E}_{i}^{\ensuremath{\prime} } $ is not negligible close to the walls and terms acting as sources and sinks in the turbulent kinetic energy, turbulent scalar flux and turbulent scalar variance equations are examined. Profiles of hydrodynamic terms in the budgets resemble those in the literature for RBC; however there are terms specific to EHD that are significant, indicating that the transfer of energy in EHD is also attributed to further electrodynamic terms and a strong coupling exists between the charge flux and variance, due to the ionic drift term.

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