scholarly journals Reconfiguration of Multistable 3D Ferromagnetic Mesostructures Guided by Energy Landscape Surveys

2020 ◽  
Author(s):  
Yi Li ◽  
Sam Avis ◽  
Junbo Chen ◽  
Guangfu Wu ◽  
Teng Zhang ◽  
...  
Keyword(s):  
Rational Design ◽  
Computational Study ◽  
Shape Change ◽  
Energy Landscape ◽  
Minimum Energy ◽  
3D Structure ◽  
Stable States ◽  
3D Structures ◽  
Highly Nonlinear ◽  
Wide Range

Abstract Reconfigurable three-dimensional (3D) structures that can reversibly change their geometries and thereby their functionalities are promising for a wide range of applications. Despite intensive studies, the lack of fundamental understanding of the highly nonlinear multistable states existing in these structures has significantly hindered the development of reconfigurable systems that can realize rapid, well-controlled shape change. Herein we present a systematic, integrated experimental and computational study to control and tailor the multistable states of 3D structures and their reconfiguration paths. Our energy landscape analysis using a discrete shell model and minimum energy pathway methods leads to design maps for a controlled number of stable states by varying geometry and material parameters, and energy-efficient reconfiguration paths among the multistable states. Concurrently, our experiments show that 3D structures assembled from ferromagnetic composite thin films of diverse geometries can be rapidly reconfigured among their multistable states, with the number of stable states and reconfigurable paths in excellent agreement with computational predictions. In addition, we demonstrate a wide breadth of applications including reconfigurable 3D light emitting systems, remotely- controlled release of particles/drugs from a reconfigurable structure, and 3D structure arrays that can form desired patterns following the written path of a magnetic “pen”. Our results represent a critical step towards the rational design and development of well-controlled, rapidly and remotely reconfigurable structures for many applications.

scholarly journals Multiresolution layered manufacturing

2019 ◽  
Vol 25 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Jose David Fernandez ◽  
Joel de Coninck
Keyword(s):  
3D Structure ◽  
Layered Manufacturing ◽  
Limiting Factors ◽  
Content Type ◽  
3D Structures ◽  
Large Structures ◽  
Wide Range ◽  
Speed Up ◽  
New Applications ◽  
Printing Time

Purpose Two-photon polymerization (TPP) has become one of the most popular techniques for stereolithography at very high resolutions. When printing relatively large structures at high resolutions, one of the main limiting factors is the printing time. The purpose of this paper is to present a new slicing algorithm to minimize printing times. Design/methodology/approach Typically, slicing algorithms used for TPP do not take into account the fact that TPP can print at a range of resolutions (i.e. with different heights and diameters) by varying parameters such as exposure time, laser power, photoresist properties and optical arrangements. This work presents multiresolution layered manufacturing (MLM), a novel slicing algorithm that processes 3D structures to separate parts manufacturable at low resolution from those that require a higher resolution. Findings MLM can significantly reduce the printing time of 3D structures at high resolutions. The maximum theoretical speed-up depends on the range of printing resolutions, but the effective speed-up also depends on the geometry of each 3D structure. Research limitations/implications MLM opens the possibility to significantly decrease printing times, potentially opening the use of TPP to new applications in many disciplines such as microfluidics, metamaterial research or wettability. Originality/value There are many instances of previous research on printing at several resolutions. However, in most cases, the toolpaths have to be manually arranged. In some cases, previous research also automates the generation of toolpaths, but they are limited in various ways. MLM is the first algorithm to comprehensively solve this problem for a wide range of true 3D structures.

scholarly journals Modeling structure, stability and flexibility of double-stranded RNAs in salt solutions

2018 ◽  
Author(s):  
L. Jin ◽  
Y.Z. Shi ◽  
C.J. Feng ◽  
Y.L. Tan ◽  
Z.J. Tan
Keyword(s):  
Electrostatic Potential ◽  
Cell Metabolism ◽  
3D Structure ◽  
Three Dimensional ◽  
Coarse Grained ◽  
Structure Stability ◽  
Salt Solutions ◽  
3D Structures ◽  
Coarse Grained Model ◽  
Wide Range

AbstractDouble-stranded (ds) RNAs play essential roles in many processes of cell metabolism. The knowledge of three-dimensional (3D) structure, stability and flexibility of dsRNAs in salt solutions is important for understanding their biological functions. In this work, we further developed our previously proposed coarse-grained model to predict 3D structure, stability and flexibility for dsRNAs in monovalent and divalent ion solutions through involving an implicit structure-based electrostatic potential. The model can make reliable predictions for 3D structures of extensive dsRNAs with/without bulge/internal loops from their sequences, and the involvement of the structure-based electrostatic potential and corresponding ion condition can improve the predictions on 3D structures of dsRNAs in ion solutions. Furthermore, the model can make good predictions on thermal stability for extensive dsRNAs over the wide range of monovalent/divalent ion concentrations, and our analyses show that thermally unfolding pathway of a dsRNA is generally dependent on its length as well as its sequence. In addition, the model was employed to examine the salt-dependent flexibility of a dsRNA helix and the calculated salt-dependent persistence lengths are in good accordance with experiments.

Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

1988 ◽  
Vol 46 ◽  
pp. 582-583
Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Shape Change ◽  
Microstructural Characterization ◽  
Particle Size Effect ◽  
Dicalcium Silicate ◽  
Laser Melting ◽  
Uniform Size ◽  
Cell Shape Change ◽  
Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

scholarly journals Chemical Synthesis and NMR Solution Structure of Conotoxin GXIA from Conus geographus

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 60
Author(s):  
David A. Armstrong ◽  
Ai-Hua Jin ◽  
Nayara Braga Emidio ◽  
Richard J. Lewis ◽  
Paul F. Alewood ◽  
...  
Keyword(s):  
Solution Structure ◽  
3D Structure ◽  
Voltage Sensor ◽  
Solution Nmr ◽  
Striking Similarity ◽  
Amino Acid Peptide ◽  
Wide Range ◽  
Cone Snails ◽  
Drug Leads ◽  
Β Sheet

Conotoxins are disulfide-rich peptides found in the venom of cone snails. Due to their exquisite potency and high selectivity for a wide range of voltage and ligand gated ion channels they are attractive drug leads in neuropharmacology. Recently, cone snails were found to have the capability to rapidly switch between venom types with different proteome profiles in response to predatory or defensive stimuli. A novel conotoxin, GXIA (original name G117), belonging to the I3-subfamily was identified as the major component of the predatory venom of piscivorous Conus geographus. Using 2D solution NMR spectroscopy techniques, we resolved the 3D structure for GXIA, the first structure reported for the I3-subfamily and framework XI family. The 32 amino acid peptide is comprised of eight cysteine residues with the resultant disulfide connectivity forming an ICK+1 motif. With a triple stranded β-sheet, the GXIA backbone shows striking similarity to several tarantula toxins targeting the voltage sensor of voltage gated potassium and sodium channels. Supported by an amphipathic surface, the structural evidence suggests that GXIA is able to embed in the membrane and bind to the voltage sensor domain of a putative ion channel target.

scholarly journals Influence of Tool Geometry and Process Parameters on the Properties of Friction Stir Spot Welded Multiple (AA 5754 H111) Aluminium Sheets

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1157
Author(s):  
Danka Labus Zlatanovic ◽  
Sebastian Balos ◽  
Jean Pierre Bergmann ◽  
Stefan Rasche ◽  
Milan Pecanac ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Spot Welding ◽  
Minimum Energy ◽  
Tool Geometry ◽  
Friction Stir ◽  
Minimum Energy Consumption ◽  
Punch Test ◽  
Wide Range ◽  
Lap Welding

Friction stir spot welding is an emerging spot-welding technology that offers opportunities for joining a wide range of materials with minimum energy consumption. To increase productivity, the present work addresses production challenges and aims to find solutions for the lap-welding of multiple ultrathin sheets with maximum productivity. Two convex tools with different edge radii were used to weld four ultrathin sheets of AA5754-H111 alloy each with 0.3 mm thickness. To understand the influence of tool geometries and process parameters, coefficient of friction (CoF), microstructure and mechanical properties obtained with the Vickers microhardness test and the small punch test were analysed. A scanning acoustic microscope was used to assess weld quality. It was found that the increase of tool radius from 15 to 22.5 mm reduced the dwell time by a factor of three. Samples welded with a specific tool were seen to have no delamination and improved mechanical properties due to longer stirring time. The rotational speed was found to be the most influential parameter in governing the weld shape, CoF, microstructure, microhardness and weld efficiency. Low rotational speeds caused a 14.4% and 12.8% improvement in joint efficiency compared to high rotational speeds for both tools used in this investigation.

scholarly journals A Computational Study on the Role of Parameters for Identification of Thyroid Nodules by Infrared Images (and Comparison with Real Data)

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4459
Author(s):  
José R. González ◽  
Charbel Damião ◽  
Maira Moran ◽  
Cristina A. Pantaleão ◽  
Rubens A. Cruz ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thyroid Nodules ◽  
Numerical Study ◽  
Computational Study ◽  
Internal Heat ◽  
Heat Transfer Process ◽  
The Body ◽  
Physical Parameters ◽  
Infrared Sensors ◽  
Wide Range

According to experts and medical literature, healthy thyroids and thyroids containing benign nodules tend to be less inflamed and less active than those with malignant nodules. It seems to be a consensus that malignant nodules have more blood veins and more blood circulation. This may be related to the maintenance of the nodule’s heat at a higher level compared with neighboring tissues. If the internal heat modifies the skin radiation, then it could be detected by infrared sensors. The goal of this work is the investigation of the factors that allow this detection, and the possible relation with any pattern referent to nodule malignancy. We aim to consider a wide range of factors, so a great number of numerical simulations of the heat transfer in the region under analysis, based on the Finite Element method, are performed to study the influence of each nodule and patient characteristics on the infrared sensor acquisition. To do so, the protocol for infrared thyroid examination used in our university’s hospital is simulated in the numerical study. This protocol presents two phases. In the first one, the body under observation is in steady state. In the second one, it is submitted to thermal stress (transient state). Both are simulated in order to verify if it is possible (by infrared sensors) to identify different behavior referent to malignant nodules. Moreover, when the simulation indicates possible important aspects, patients with and without similar characteristics are examined to confirm such influences. The results show that the tissues between skin and thyroid, as well as the nodule size, have an influence on superficial temperatures. Other thermal parameters of thyroid nodules show little influence on surface infrared emissions, for instance, those related to the vascularization of the nodule. All details of the physical parameters used in the simulations, characteristics of the real nodules and thermal examinations are publicly available, allowing these simulations to be compared with other types of heat transfer solutions and infrared examination protocols. Among the main contributions of this work, we highlight the simulation of the possible range of parameters, and definition of the simulation approach for mapping the used infrared protocol, promoting the investigation of a possible relation between the heat transfer process and the data obtained by infrared acquisitions.

scholarly journals Photoprotective Properties of Eumelanin: Computational Insights into the Photophysics of a Catechol:Quinone Heterodimer Model System

Photochem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 26-37
Author(s):  
Victoria C. Frederick ◽  
Thomas A. Ashy ◽  
Barbara Marchetti ◽  
Michael N. R. Ashfold ◽  
Tolga N. V. Karsili
Keyword(s):  
Ground State ◽  
Sandwich Structure ◽  
Computational Study ◽  
Minimum Energy ◽  
Carbonyl Oxygen ◽  
Model System ◽  
Molecular Structures ◽  
Uv Damage ◽  
Chromosomal Dna ◽  
Relevant Model

Melanins are skin-centered molecular structures that block harmful UV radiation from the sun and help protect chromosomal DNA from UV damage. Understanding the photodynamics of the chromophores that make up eumelanin is therefore paramount. This manuscript presents a multi-reference computational study of the mechanisms responsible for the experimentally observed photostability of a melanin-relevant model heterodimer comprising a catechol (C)–benzoquinone (Q) pair. The present results validate a recently proposed photoinduced intermolecular transfer of an H atom from an OH moiety of C to a carbonyl-oxygen atom of the Q. Photoexcitation of the ground state C:Q heterodimer (which has a π-stacked “sandwich” structure) results in population of a locally excited ππ* state (on Q), which develops increasing charge-transfer (biradical) character as it evolves to a “hinged” minimum energy geometry and drives proton transfer (i.e., net H atom transfer) from C to Q. The study provides further insights into excited state decay mechanisms that could contribute to the photostability afforded by the bulk polymeric structure of eumelanin.

scholarly journals Machine learning for multi-dimensional optimisation and predictive visualisation of laser machining

2021 ◽  
Author(s):  
Michael D. T. McDonnell ◽  
Daniel Arnaldo ◽  
Etienne Pelletier ◽  
James A. Grant-Jacob ◽  
Matthew Praeger ◽  
...  
Keyword(s):  
Short Pulse ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Laser Machining ◽  
Laser Materials ◽  
Parameter Optimisation ◽  
Short Pulse Laser ◽  
Alternative Approach ◽  
Highly Nonlinear ◽  
Wide Range

AbstractInteractions between light and matter during short-pulse laser materials processing are highly nonlinear, and hence acutely sensitive to laser parameters such as the pulse energy, repetition rate, and number of pulses used. Due to this complexity, simulation approaches based on calculation of the underlying physical principles can often only provide a qualitative understanding of the inter-relationships between these parameters. An alternative approach such as parameter optimisation, often requires a systematic and hence time-consuming experimental exploration over the available parameter space. Here, we apply neural networks for parameter optimisation and for predictive visualisation of expected outcomes in laser surface texturing with blind vias for tribology control applications. Critically, this method greatly reduces the amount of experimental laser machining data that is needed and associated development time, without negatively impacting accuracy or performance. The techniques presented here could be applied in a wide range of fields and have the potential to significantly reduce the time, and the costs associated with laser process optimisation.

scholarly journals Fluorescent thermal shift-based method for detection of NF-κB binding to double-stranded DNA

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Peter D. Leitner ◽  
Ilja Vietor ◽  
Lukas A. Huber ◽  
Taras Valovka
Keyword(s):  
Dna Binding ◽  
Rational Design ◽  
Dissociation Constants ◽  
Inflammatory Diseases ◽  
Dimethyl Fumarate ◽  
Bioinformatic Analysis ◽  
Quantitative Detection ◽  
Regulatory Sequences ◽  
Wide Range ◽  
Inhibitory Drug

AbstractThe nuclear factor kappa B (NF-κB) family of dimeric transcription factors regulates a wide range of genes by binding to their specific DNA regulatory sequences. NF-κB is an important therapeutic target linked to a number of cancers as well as autoimmune and inflammatory diseases. Therefore, effective high-throughput methods for the detection of NF-κB DNA binding are essential for studying its transcriptional activity and for inhibitory drug screening. We describe here a novel fluorescence-based assay for quantitative detection of κB consensus double-stranded (ds) DNA binding by measuring the thermal stability of the NF-κB proteins. Specifically, DNA binding proficient NF-κB probes, consisting of the N-terminal p65/RelA (aa 1–306) and p50 (aa 1–367) regions, were designed using bioinformatic analysis of protein hydrophobicity, folding and sequence similarities. By measuring the SYPRO Orange fluorescence during thermal denaturation of the probes, we detected and quantified a shift in the melting temperatures (ΔTm) of p65/RelA and p50 produced by the dsDNA binding. The increase in Tm was proportional to the concentration of dsDNA with apparent dissociation constants (KD) of 2.228 × 10–6 M and 0.794 × 10–6 M, respectively. The use of withaferin A (WFA), dimethyl fumarate (DMF) and p-xyleneselenocyanate (p-XSC) verified the suitability of this assay for measuring dose-dependent antagonistic effects on DNA binding. In addition, the assay can be used to analyse the direct binding of inhibitors and their effects on structural stability of the protein probe. This may facilitate the identification and rational design of new drug candidates interfering with NF-κB functions.

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