π-Facial Stereoselectivity in Acyl Nitroso Cycloadditions to 5,5-Unsymmetrically Substituted Cyclopentadienes: Computational Exploration of Origins of Selectivity and the Role of Substituent Conformations on Selectivity

2021 ◽  
Author(s):  
Fengyue Zhao ◽  
Peiyuan Yu ◽  
Yu Chen ◽  
Fang Liu ◽  
K. N. Houk
Keyword(s):  
Computational Exploration

scholarly journals Degradation rate uniformity determines success of oscillations in repressive feedback regulatory networks

2018 ◽  
Vol 15 (142) ◽  
pp. 20180157 ◽  
Author(s):  
Karen M. Page ◽  
Ruben Perez-Carrasco
Keyword(s):  
Regulatory Networks ◽  
Oscillatory Behaviour ◽  
Sustained Oscillations ◽  
Degradation Rates ◽  
Number Of Genes ◽  
Computational Exploration ◽  
The Stability ◽  
Regulatory Functions ◽  
Insight Into

Ring oscillators are biochemical circuits consisting of a ring of interactions capable of sustained oscillations. The nonlinear interactions between genes hinder the analytical insight into their function, usually requiring computational exploration. Here, we show that, despite the apparent complexity, the stability of the unique steady state in an incoherent feedback ring depends only on the degradation rates and a single parameter summarizing the feedback of the circuit. Concretely, we show that the range of regulatory parameters that yield oscillatory behaviour is maximized when the degradation rates are equal. Strikingly, this result holds independently of the regulatory functions used or number of genes. We also derive properties of the oscillations as a function of the degradation rates and number of nodes forming the ring. Finally, we explore the role of mRNA dynamics by applying the generic results to the specific case with two naturally different degradation timescales.

Photocatalytic and Photoelectro-Chemical Study of Ferrites for Water Splitting Applications: A Comparative Study

2012 ◽  
Vol 734 ◽  
pp. 334-348 ◽  
Author(s):  
Rekha Dom ◽  
Pramod H. Borse
Keyword(s):  
Comparative Study ◽  
Visible Light ◽  
Water Splitting ◽  
Chemical Study ◽  
Synthesis And Characterization ◽  
Material System ◽  
Computational Exploration ◽  
Visible Light Active

This article presents a comparative study on the synthesis and characterization of the binary and ternary ferrites for photocatalytic and photoelectrochemical applications. The importance and role of ferrite photocatalysts is discussed in context to the visible-light active photocatalyst applicationviz.for hydrogen productionvia.water-splitting. It also demonstrates that computational-exploration of any material system is key to identify, and achieve visible-light active photocatalysts.

scholarly journals Computational exploration of treadmilling and protrusion growth observed in fire ant rafts

2021 ◽  
Author(s):  
Robert James Wagner ◽  
Franck J Vernerey
Keyword(s):  
Solenopsis Invicta ◽  
Swarm Robotics ◽  
Collective Motion ◽  
Active Matter ◽  
Local Interactions ◽  
Agent Based ◽  
Computational Exploration ◽  
In Fire ◽  
Cellular Aggregates

Condensed active matter systems regularly achieve cooperative emergent functions that individual constituents could not accomplish alone. The rafts of fire ants (Solenopsis invicta) are often studied in this context for their ability to create structures comprised entirely of their own bodies, including tether-like protrusions that facilitate exploration of flooded environments. While similar protrusions are observed in cytoskeletons and cellular aggregates, they are generally dependent on morphogens or external gradients leaving the isolated role of local interactions poorly understood. Here we demonstrate through an ant-inspired, agent-based numerical model how protrusions in ant rafts may emerge spontaneously due to local interactions and how phases of exploratory protrusion growth may be induced by increased ant activity. These results provide an example in which functional morphogenesis of condensed active matter may emerge purely from locally-driven collective motion and may provide a source of inspiration for the development of autonomous active matter and swarm robotics.

Rationalizing the “Diels-Alderase” Activity of Pd2L4 Self-Assembled Metallocages: Enabling the Efficient Prediction of Catalytic Scaffolds

2019 ◽  
Author(s):  
Tom A. Young ◽  
Vicente Martí-Centelles ◽  
Jianzhu Wang ◽  
Paul J. Lusby ◽  
Fernanda Duarte
Keyword(s):  
Structural Dynamics ◽  
Critical Role ◽  
Diels Alder ◽  
Binding Affinities ◽  
Distortion Energy ◽  
Structural Differences ◽  
Computational Exploration ◽  
Efficient Prediction ◽  
Self Assembled

Self-assembled cages have emerged as novel platforms to explore bio-inspired catalysis. While many different size and shape supramolecular structures are now readily accessible, only a few are proficient catalysts. Here we show that a simple and efficient DFT-based methodology i is sufficient to accurately reproduce experimental binding affinities (MAD = 1.9 kcal mol-1) and identify the catalytic and non-catalytic Diels-Alder proficiencies (>90 % accuracy) of two homologous Pd2L4 metallocages with a variety of substrates. We demonstrate how subtle structural differences in the cage framework affect binding and catalysis, highlighting the critical role of structural dynamics and flexibility on catalytic activity. This flexibility manifests in a smaller transition state distortion energy for the catalytic cage compared to the inactive structure. To facilitate the computational exploration of novel Pd2L4 systems, we introduce an open-source Python module cgbind, which largely automates the screening of novel architectures.

Rationalizing the “Diels-Alderase” Activity of Pd2L4 Self-Assembled Metallocages: Enabling the Efficient Prediction of Catalytic Scaffolds

2019 ◽  
Author(s):  
Tom A. Young ◽  
Vicente Martí-Centelles ◽  
Jianzhu Wang ◽  
Paul J. Lusby ◽  
Fernanda Duarte
Keyword(s):  
Structural Dynamics ◽  
Critical Role ◽  
Diels Alder ◽  
Binding Affinities ◽  
Distortion Energy ◽  
Structural Differences ◽  
Computational Exploration ◽  
Efficient Prediction ◽  
Self Assembled

Self-assembled cages have emerged as novel platforms to explore bio-inspired catalysis. While many different size and shape supramolecular structures are now readily accessible, only a few are proficient catalysts. Here we show that a simple and efficient DFT-based methodology i is sufficient to accurately reproduce experimental binding affinities (MAD = 1.9 kcal mol-1) and identify the catalytic and non-catalytic Diels-Alder proficiencies (>90 % accuracy) of two homologous Pd2L4 metallocages with a variety of substrates. We demonstrate how subtle structural differences in the cage framework affect binding and catalysis, highlighting the critical role of structural dynamics and flexibility on catalytic activity. This flexibility manifests in a smaller transition state distortion energy for the catalytic cage compared to the inactive structure. To facilitate the computational exploration of novel Pd2L4 systems, we introduce an open-source Python module cgbind, which largely automates the screening of novel architectures.

scholarly journals Computational exploration of the reaction mechanism of the Cu + -catalysed synthesis of indoles from N -aryl enaminones

2016 ◽  
Vol 3 (2) ◽  
pp. 150582 ◽  
Author(s):  
Carlos E. P. Bernardo ◽  
Pedro J. Silva
Keyword(s):  
Density Functional ◽  
Initial Step ◽  
Single Electron Transfer ◽  
Functional Theory ◽  
Alternative Pathways ◽  
Bond Forming ◽  
Rate Determining Step ◽  
Computational Exploration ◽  
Indole Synthesis

We have studied the role of Cu + -phenantroline as a catalyst in the cyclization of N -aryl-enaminones using density-functional theory computations. The catalyst was found to bind the substrate upon deprotonation of its eneaminone, and to dramatically increase the acidity of the carbon adjacent to the ketone functionality. The deprotonation of this carbon atom yields a carbanion which attacks the aryl moiety, thereby closing the heterocycle in the rate-determining step. This C–C bond forming reaction was found to proceed much more rapidly when preceded by re-protonation of the substrate N-atom (which had lost H + in the initial step). Hydride transfer to the catalyst then completes the indole synthesis, in a very fast step. The influence of Li + and K + on the regio-selectivity of the cyclization of bromo-substituted analogues could not, however, be reproduced by our model. Alternative pathways involving either single-electron transfer from the catalyst to the substrate or ring cyclization without previous carbon α -deprotonation were found to be kinetically or thermodynamically inaccessible.

Single layer lead iodide: computational exploration of structural, electronic and optical properties, strain induced band modulation and the role of spin–orbital-coupling

Nanoscale ◽  
2015 ◽  
Vol 7 (37) ◽  
pp. 15168-15174 ◽  
Author(s):  
Mei Zhou ◽  
Wenhui Duan ◽  
Ying Chen ◽  
Aijun Du
Keyword(s):  
Optical Properties ◽  
Electronic Structures ◽  
Single Layer ◽  
Layered Materials ◽  
Two Dimensional ◽  
Lead Iodide ◽  
Spin Orbital ◽  
Computational Exploration ◽  
Spin Orbital Coupling

Graphitic like layered materials exhibit intriguing electronic structures and thus the search for new types of two-dimensional (2D) monolayer materials is of great interest for developing novel nano-devices.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management
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