scholarly journals Real-time imaging of accelerated solid-liquid-gas reactions with nanobubbles

2020 ◽  
Author(s):  
Wen Wang ◽  
Tao Xu ◽  
Jige Chen ◽  
Junyi Shangguan ◽  
Hui Dong ◽  
...  
Keyword(s):  
Real Time ◽  
Rational Design ◽  
Etching Rate ◽  
Gold Surface ◽  
Critical Distance ◽  
Order Of Magnitude ◽  
Gas Reactions ◽  
Time Observation ◽  
Dynamics Simulations ◽  
Solid Liquid

Abstract Solid-liquid-gas reactions are ubiquitous. An understanding of how gases influence the reactions at the nanoscale is significant for achieving the enhanced triple-phase reactions. Here, we report a real-time observation of the accelerated etching of gold nanorods with oxygen nanobubbles in aqueous hydrobromic acid using liquid cell transmission electron microscopy (TEM). Our observation reveals that when an oxygen nanobubble is close to a nanorod below the critical distance (~1nm), the local etching rate is significantly enhanced with over an order of magnitude faster. Molecular dynamics simulations results show that the strong attractive van der Waals interaction between the gold nanorod and oxygen molecules facilitates the transport of oxygen through the thin liquid layer to the gold surface and thus plays a crucial role in increasing the etching rate. This result sheds light on the rational design of solid-liquid-gas reactions for enhanced activities.

Real-Time Observation of High Temperature Interface between SiC Substrate and Solution during Dissolution of SiC

2013 ◽  
Vol 740-742 ◽  
pp. 35-38 ◽  
Author(s):  
Sakiko Kawanishi ◽  
Takeshi Yoshikawa ◽  
Kazuki Morita
Keyword(s):  
High Temperature ◽  
Real Time ◽  
Back Surface ◽  
Lateral Direction ◽  
Digital Microscope ◽  
Time Observation ◽  
A New Technique ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Real Time Observation

Precise morphological control of the interface between SiC and solution during the solution growth of SiC is crucial for obtaining high quality crystals with fewer defects and less step bunching. In this paper, a new technique for real-time observation of the high temperature interface between SiC and solution through the back surface of SiC was developed by focusing on the “wide” bandgap of SiC. Real-time observation of the interface during dissolution of SiC into an Fe-Si solvent alloy was carried out using a digital microscope, and the submicron-height structure of the solid-liquid interface was clearly observed at up to 1773 K. Interface morphologies, such as numerous hexagonal pits which were present at the initial stage of dissolution, followed by preferential dissolution in the lateral direction, were observed.

Force-activated catalytic pathway accelerates bacterial adhesion against flow

2018 ◽  
Vol 475 (16) ◽  
pp. 2611-2620 ◽  
Author(s):  
Jagadish P. Hazra ◽  
Nisha Arora ◽  
Amin Sagar ◽  
Shwetha Srinivasan ◽  
Abhishek Chaudhuri ◽  
...  
Keyword(s):  
Real Time ◽  
Single Molecule ◽  
Bacterial Adhesion ◽  
Rational Design ◽  
Enzymatic Reaction ◽  
Transition States ◽  
Factors Affecting ◽  
The Real ◽  
Time Dynamics ◽  
Dynamics Simulations

Mechanical cues often influence the factors affecting the transition states of catalytic reactions and alter the activation pathway. However, tracking the real-time dynamics of such activation pathways is limited. Using single-molecule trapping of reaction intermediates, we developed a method that enabled us to perform one reaction at one site and simultaneously study the real-time dynamics of the catalytic pathway. Using this, we showed single-molecule calligraphy at nanometer resolution and deciphered the mechanism of the sortase A enzymatic reaction that, counter-intuitively, accelerates bacterial adhesion under shear tension. Our method captured a force-induced dissociation of the enzyme–substrate bond that accelerates the forward reaction 100×, proposing a new mechano-activated catalytic pathway. In corroboration, our molecular dynamics simulations in the presence of force identified a force-induced conformational switch in the enzyme that accelerates proton transfer between CYS184 (acceptor) and HIS120 (donor) catalytic dyads by reducing the inter-residue distances. Overall, the present study opens up the possibility of studying the influence of factors affecting transition states in real time and paves the way for the rational design of enzymes with enhanced efficiency.

Real-Time Observation of the Solid–Liquid–Vapor Dissolution of Individual Tin(IV) Oxide Nanowires

ACS Nano ◽  
2014 ◽  
Vol 8 (6) ◽  
pp. 5441-5448 ◽  
Author(s):  
Bethany M. Hudak ◽  
Yao-Jen Chang ◽  
Lei Yu ◽  
Guohua Li ◽  
Danielle N. Edwards ◽  
...  
Keyword(s):  
Real Time ◽  
Oxide Nanowires ◽  
Time Observation ◽  
Solid Liquid ◽  
Real Time Observation ◽  
Liquid Vapor

The Diffusion and Solid-Liquid Phase Transformation in Directional Solidification of Alloy: A Quantitative Phase Field Characterization and Real-Time Observation

2018 ◽  
Vol 15 ◽  
pp. 97-127
Author(s):  
Yun Chen ◽  
Na Min Xiao ◽  
Dian Zhong Li ◽  
Tong Zhao Gong ◽  
Henri Nguyen-Thi
Keyword(s):  
Directional Solidification ◽  
Real Time ◽  
Phase Field ◽  
Rapid Development ◽  
Adaptive Finite Element Method ◽  
Quantitative Phase ◽  
Diffusion Limited ◽  
Time Observation ◽  
Solid Liquid ◽  
Real Time Observation

Directional solidification is a paradigm process to gain the desired microstructure via certain applied solidification parameters. A thorough understanding of the diffusion-limited solid-liquid interface morphology evolution from initial transient to steady state is of uppermost importance to optimize the solidification processes. The rapid development of quantitative phase-field model provides a feasible computational tool to explore the underlying physics of the morphological transition at different stages. On basis of the diffusion-limited quantitative phase-field simulations using adaptive finite element method, the directional solidification of Al-4wt.%Cu alloy is characterized and both the solid interface propagation speed and solute profile are analyzed. The simulations are then compared with the in situ and real-time observation by means of synchrotron radiation x-ray radiography image. Good agreements are obtained between simulations and experimental data. Detailed mechanism that controls the morphological instability and transition are then addressed.

scholarly journals Application of a Fluorescent Biosensor in Determining the Binding of 5-HT to Calmodulin

Chemosensors ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 250
Author(s):  
L. X. Vásquez-Bochm ◽  
Isabel Velázquez-López ◽  
Rachel Mata ◽  
Alejandro Sosa-Peinado ◽  
Patricia Cano-Sánchez ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Rational Design ◽  
Docking Study ◽  
The Other ◽  
Modeling Tools ◽  
Fluorescent Biosensor ◽  
Order Of Magnitude ◽  
Dynamics Simulations ◽  
First Time ◽  
Different Tissues

Here, we show the utility of the fluorescent biosensor hCaM-M124C-mBBr in detecting and determining the affinity of serotonin (5-HT). We obtained a Kd of 5-HT (0.71 μm) for the first time, the same order of magnitude as most anti-CaM drugs. This data can contribute to understanding the direct and indirect modulation of CaM on its binding proteins when the 5-HT concentration varies in different tissues or explain some of the side effects of anti-CaM drugs. On the other hand, molecular modeling tools help the rational design of biosensors and adequately complement the experimental results. For example, the docking study indicates that 5-HT binds at the same site as chlorpromazine (site 1) with a theoretical Ki of 2.84 μM; while the molecular dynamics simulations indicate a stability of the CaM–5-HT complex with a theoretical ΔG of −4.85 kcal mol−1, where the enthalpy contribution is greater. Thus, the combination of biotechnology and bioinformatics helps in the design and construction of more robust biosensors.

Real-time observation of vortex lattices in a superconductor

1993 ◽  
Vol 51 ◽  
pp. 1050-1051
Author(s):  
K. Harada ◽  
T. Matsuda ◽  
J.E. Bonevich ◽  
M. Igarashi ◽  
S. Kondo ◽  
...  
Keyword(s):  
Real Time ◽  
Flux Line ◽  
Electron Holography ◽  
Lorentz Microscopy ◽  
Vortex Lattices ◽  
Flux Lines ◽  
Magnetic Flux Lines ◽  
Time Observation ◽  
Thin Superconductor ◽  
Real Time Observation

Previous observations of magnetic flux-lines (vortex lattices) in superconductors, such as the field distribution of a flux-line, and flux-line dynamics activated by heat and current, have employed the high spatial resolution and magnetic sensitivity of electron holography. And recently, the 2-D static distribution of vortices was also observed by this technique. However, real-time observations of the vortex lattice, in spite of scientific and technological interest, have not been possible due to experimental difficulties. Here, we report the real-time observation of vortex lattices in a thin superconductor, by means of Lorentz microscopy using a 300 kV field emission electron microscope. This technique allows us to observe the dynamic motion of individual vortices and record the events on a VTR system.The experimental arrangement is shown in Fig. 1. A Nb thin film for transmission observation was prepared by chemical etching. The grain size of the film was increased by annealing, and single crystals were observed with a thickness of 50∼90 nm.

Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

2020 ◽  
Author(s):  
Abhishek Singh ◽  
Reman K. Singh ◽  
G Naresh Patwari
Keyword(s):  
Hydrogen Bonding ◽  
Rational Design ◽  
Biological Molecules ◽  
Conformational Space ◽  
X Ray Crystallography ◽  
Simple Strategy ◽  
Induced Folding ◽  
Π Stacking ◽  
Varying Length ◽  
Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

2020 ◽  
Author(s):  
Abhishek Singh ◽  
Reman K. Singh ◽  
G Naresh Patwari
Keyword(s):  
Hydrogen Bonding ◽  
Rational Design ◽  
Biological Molecules ◽  
Conformational Space ◽  
X Ray Crystallography ◽  
Simple Strategy ◽  
Induced Folding ◽  
Π Stacking ◽  
Varying Length ◽  
Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

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