Growth onset of perylene-based nanocrystals

2021 ◽  
Vol 23 (3) ◽  
pp. 7-11
Author(s):  
U. Khalilov ◽  
M. Yusupov ◽  
A. Tojiboev ◽  
P. Nematollahi ◽  
D. Husanova ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Feeding Rate ◽  
Md Simulations ◽  
Crystal Nucleation ◽  
Simulation Studies ◽  
Face To Face ◽  
Organic Nanocrystals ◽  
Nucleation Mechanisms ◽  
Made In ◽  
Molecular Stacking

The wide application of organic nanocrystals requires a deeper understanding of their nucleation mechanisms. In particular, the onset of nucleation still needs to be elucidated, although tremendous efforts have already been made in both experimental and simulation studies. In this research, we conduct molecular dynamics (MD) simulations, supported by quantum mechanical (DFT) calculations, to understand the mechanisms of the nucleation onset of organic perylene nanocrystals. Our DFT calculations indicate that face-to-face and face-to-edge molecular stacking can ultimately lead to the formation of a herringbone-style perylene nanocrystal. On the other hand, the results of MD simulations show the formation of clusters, which continues with the crystal nucleation in the form of unidirectional or multidirectional growth, depending on the feeding rate of perylene molecule in vacuum. This research helps to better understand the control of the growth of organic nanocrystals in modern nanotechnology.

USE OF BLENDED LEARNING IN HIGHER EDUCATION – SOME EXPERIENCES

2015 ◽  
Vol 37 (1) ◽  
pp. 54-67 ◽  
Author(s):  
R J Singh
Keyword(s):  
Higher Education ◽  
South Africa ◽  
Distance Learning ◽  
Blended Learning ◽  
Learning Experiences ◽  
Learning Opportunities ◽  
Face To Face ◽  
E Learning ◽  
Face To Face Learning ◽  
Made In

This article reports on the use of blended learning in higher education. Blended learning has become popular in higher education in recent years. It is a move beyond traditional lecturing to incorporate face-to-face learning with e-learning, thereby creating a blend of learning experiences. The problem is that learning in higher education is complex and learning situations differ across contexts. Whilst there is face-to-face contact at some institutions, others offer distance learning or correspondence learning. In each context, the mode of learning may differ. The challenge is to cater for various learning opportunities through a series of learning interactions and to incorporate a blended approach. The aim of this study was to examine various ways of defining blended learning in different contexts. This was done through an examination of experiences of the use of blended learning in different higher education contexts. The study presents a case of blended learning in a postgraduate course. The experiences from all these cases are summarised and conclusions and recommendations are made in the context of blended learning in higher education in South Africa.

Computationally Assisted Design of High Signal-to-Noise Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes

2020 ◽  
Author(s):  
Rishikesh Kulkarni ◽  
Anneliese Gest ◽  
Chun Kei Lam ◽  
Benjamin Raliski ◽  
Feroz James ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dft Calculations ◽  
Photoinduced Electron Transfer ◽  
Density Functional ◽  
Embryonic Stem ◽  
High Sensitivity ◽  
Md Simulations ◽  
High Signal ◽  
Signal To Noise ◽  
Green Fluorescent

<p>High signal-to-noise optical voltage indicators will enable simultaneous interrogation of membrane potential in large ensembles of neurons. However, design principles for voltage sensors with high sensitivity and brightness remain elusive, limiting the applicability of voltage imaging. In this paper, we use molecular dynamics (MD) simulations and density functional theory (DFT) calculations to guide the design of a bright and sensitive green-fluorescent voltage-sensitive fluorophore, or VoltageFluor (VF dye), that uses photoinduced electron transfer (PeT) as a voltage-sensing mechanism. MD simulations predict an 11% increase in sensitivity due to membrane orientation, while DFT calculations predict an increase in fluorescence quantum yield, but a decrease in sensitivity due to a decrease in rate of PeT. We confirm these predictions by synthesizing a new VF dye and demonstrating that it displays the expected improvements by doubling the brightness and retaining similar sensitivity to prior VF dyes. Combining theoretical predictions and experimental validation has resulted in the synthesis of the highest signal-to-noise green VF dye to date. We use this new voltage indicator to monitor the electrophysiological maturation of human embryonic stem cell-derived medium spiny neurons. </p>

scholarly journals Structure of the full-length human Pannexin1 channel and insights into its role in pyroptosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sensen Zhang ◽  
Baolei Yuan ◽  
Jordy Homing Lam ◽  
Jun Zhou ◽  
Xuan Zhou ◽  
...  
Keyword(s):  
Md Simulation ◽  
Potential Role ◽  
Md Simulations ◽  
Full Length ◽  
Inflammasome Activation ◽  
Simulation Studies ◽  
Cryo Electron Microscopy ◽  
Gating Mechanism ◽  
Atp Efflux

AbstractPannexin1 (PANX1) is a large-pore ATP efflux channel with a broad distribution, which allows the exchange of molecules and ions smaller than 1 kDa between the cytoplasm and extracellular space. In this study, we show that in human macrophages PANX1 expression is upregulated by diverse stimuli that promote pyroptosis, which is reminiscent of the previously reported lipopolysaccharide-induced upregulation of PANX1 during inflammasome activation. To further elucidate the function of PANX1, we propose the full-length human Pannexin1 (hPANX1) model through cryo-electron microscopy (cryo-EM) and molecular dynamics (MD) simulation studies, establishing hPANX1 as a homo-heptamer and revealing that both the N-termini and C-termini protrude deeply into the channel pore funnel. MD simulations also elucidate key energetic features governing the channel that lay a foundation to understand the channel gating mechanism. Structural analyses, functional characterizations, and computational studies support the current hPANX1-MD model, suggesting the potential role of hPANX1 in pyroptosis during immune responses.

scholarly journals Molecular Dynamics Simulations of Crystal Nucleation near Interfaces in Incompatible Polymer Blends

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 347
Author(s):  
Wenlin Zhang ◽  
Lingyi Zou
Keyword(s):  
Molecular Dynamics ◽  
Polymer Blends ◽  
Md Simulations ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Crystalline Order ◽  
Mobile Species ◽  
Deep Supercooling ◽  
Crystallizable Polymer ◽  
Dynamics Simulations

We apply molecular dynamics (MD) simulations to investigate crystal nucleation in incompatible polymer blends under deep supercooling conditions. Simulations of isothermal nucleation are performed for phase-separated blends with different degrees of incompatibility. In weakly segregated blends, slow and incompatible chains in crystallizable polymer domains can significantly hinder the crystal nucleation and growth. When a crystallizable polymer is blended with a more mobile species in interfacial regions, enhanced molecular mobility leads to the fast growth of crystalline order. However, the incubation time remains the same as that in pure samples. By inducing anisotropic alignment near the interfaces of strongly segregated blends, phase separation also promotes crystalline order to grow near interfaces between different polymer domains.

Improved routes for the synthesis of face-to-face bismacrocycles in porphyrin and corrole series

2004 ◽  
Vol 08 (03) ◽  
pp. 301-312 ◽  
Author(s):  
Jean-Michel Barbe ◽  
Christine Stern ◽  
Ewa Pacholska ◽  
Enrique Espinosa ◽  
Roger Guilard
Keyword(s):  
Face To Face ◽  
Made In

Face-to-face bismacrocycles involving porphyrinoid species are still of great interest owing to their versatile properties. Despite the fact that their syntheses generally involve several steps, numerous modifications have been made in their synthetic pathways thus allowing their preparation in gram quantities. Here we report on recent improvements we could propose especially for the synthesis of bisporphyrin, biscorrole and porphyrin-corrole derivatives.

Evaluation software for effects produced by MOOC in mediums with different linguistically levels

2018 ◽  
Vol 34 (3) ◽  
pp. 633-645
Author(s):  
Cornel Samoilă ◽  
Doru Ursuţiu ◽  
Vlad Jinga
Keyword(s):  
Statistical Analysis ◽  
Statistical Methods ◽  
Rapid Assessment ◽  
Assessment Method ◽  
Behavioral Changes ◽  
Strong Negation ◽  
Face To Face ◽  
Made In ◽  
The Way

Abstract MOOC appearance has produced, in a first phase, more discussions than contributions. Despite pessimistic opinions or those catastrophic foreseeing the end of the classic education by accepting MOOC, the authors consider that, as it is happening in all situations when a field is reformed, instead of criticism or catastrophic predictions, an assessment should be simply made. MOOC will not be better or worse if it is discussed and dissected but can be tested in action, perfected by results, or abandoned if it has no prospects. Without testing, no decision is valid. A similarity between the MOOC appearance and the appearance of the idea of flying machines heavier than air can be made. In the flight case, the first reaction was a strong negation (including at Academies level) and only performing the first independent flight with an apparatus heavier than air has shifted orientation from denial to contributions. So, practical tests clarified the battle between ideas. The authors of this article encourage the idea of testing–assessment and, therefore, imagined and proposed one software for quickly assess whether MOOC produces changes in knowledge, by simply transferring courses from ‘face-to-face’ environment into the virtual one. Among the methods of statistical analysis for student behavioral changes was chosen the Keppel method. It underpins the assessment method of this work being approached using both the version with one variable and also with three variables. It is intended that this attempts to pave the way for other series of rapid assessment regarding MOOC effects (using other statistical methods). We believe, that this is the only approach that can lead either to improve the system or to renunciation.

A comparative study of teleconsultations versus face-to-face consultations

2001 ◽  
Vol 7 (5) ◽  
pp. 257-265 ◽  
Author(s):  
E J Nordal ◽  
D Moseng ◽  
B Kvammen ◽  
M-L Løchen
Keyword(s):  
General Practitioner ◽  
Comparative Study ◽  
Complete Agreement ◽  
Patient Relationship ◽  
Doctor Patient Relationship ◽  
Partial Agreement ◽  
Face To Face ◽  
High Degree ◽  
Made In

We compared the diagnoses made by one dermatologist via telemedicine with those of another dermatologist made in a face-to-face consultation. The patients first underwent a teledermatology consultation and then a face-to-face consultation. A general practitioner was present with the patient in the videoconference studio. Videoconferencing equipment connected at 384 kbit/s was used. The doctor-patient relationship and the satisfaction of the patients and dermatologists in the two settings were assessed, as well as technical conditions during the videoconferences. There were 121 patients, with a mean age of 40 years (range 17-82 years). There was a high degree of concordance between the two sets of diagnoses, with 72% complete agreement and 14% partial agreement between the two dermatologists. A total of 116 patients (96% of those included) completed a questionnaire. Both the patients and the dermatologists were in general satisfied with the videoconferences. Videoconferencing with a participating general practitioner may be useful in dermatology, but the technique should be used only for selected patients.

A Progress Report on the Quest to Establish a Cybersickness Dose Value

2002 ◽  
Vol 46 (26) ◽  
pp. 2119-2123 ◽  
Author(s):  
Wei Chen ◽  
S.L. Yuen ◽  
R.H.Y. So
Keyword(s):  
Linear Relationship ◽  
Motion Sickness ◽  
Progress Report ◽  
Simulation Studies ◽  
Current Effort ◽  
British Standard ◽  
The Past ◽  
Frequency Weighting ◽  
Made In

This paper summarizes the progress made in the quest to establish a Cybersickness Dose Value (CSDV). The Motion Sickness Dose Value (MSDV), reported in the British Standard BS6841, has been used to predict the severity of seasickness since 1987. In 1999, the authors of this paper proposed a CSDV formulation with a structure similar to that of the MSDV (So, 1999). Since then, several experiments and simulation studies have been conducted to modify and develop the proposed CSDV formula. In particular, progress has been made in (i) the methods to measure CSDV, (ii) the determination of a frequency weighting curve to equalize the non-linear relationship between the navigation velocity and levels of cybersickness, and (iii) the detailed formulation of CSDV. This paper summarizes the past progress and reports on the current effort in developing a CSDV.

scholarly journals Impurities and Homogeneous Crystal Nucleation in Aqueous Solutions - An Overview

2019 ◽  
Vol 16 (3) ◽  
pp. 198-208
Author(s):  
C. K. Mahadevan
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Research Group ◽  
Present Author ◽  
Crystal Nucleation ◽  
Nucleation Process ◽  
Nucleation Parameters ◽  
The Past ◽  
Homogeneous Crystal ◽  
Made In

Nucleation process is the most important stage in the formation of a crystal and has attracted the attention of researchers due to its importance in many technological and biological contexts. As the presence of impurities affects the nucleation process significantly, several studies have been made in the past to understand it. In this article is presented an overview of various studies made to understand the effect of soluble impurities on the crystal nucleation parameters of certain important materials in aqueous solution focusing the results reported by the research group of the present author.

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