Generalized structural motif model for studying the thermodynamic stability of fullerenes: from C60to graphene passing through giant fullerenes

2017 ◽  
Vol 19 (30) ◽  
pp. 19646-19655 ◽  
Author(s):  
Yang Wang ◽  
Sergio Díaz-Tendero ◽  
Manuel Alcamí ◽  
Fernando Martín
Keyword(s):  
Thermodynamic Stability ◽  
Full Range ◽  
Structural Motif ◽  
Motif Model ◽  
The Stability

A generalized motif model to describe the stability of neutral fullerenes, covering the full range of cage sizes, starting from C60, going through giant fullerenes, and ultimately leading to graphene.

scholarly journals Stability of the pH-Dependent Parallel-Stranded d(CGA) Motif

2020 ◽  
Author(s):  
E. M. Luteran ◽  
J. D. Kahn ◽  
P. J. Paukstelis
Keyword(s):  
Thermodynamic Stability ◽  
Dna Nanotechnology ◽  
Repeat Motif ◽  
Structural Motif ◽  
Triplet Repeat ◽  
Dependent Manner ◽  
Related Sequence ◽  
Ph Dependent ◽  
The Stability ◽  
Nuclease Sensitivity

ABSTRACTNon-canonical DNA structures that retain programmability and structural predictability are increasingly being used in DNA nanotechnology applications, where they offer versatility beyond traditional Watson-Crick interactions. The d(CGA) triplet repeat motif is structurally dynamic and can transition between parallel-stranded homo-base paired duplex and anti-parallel unimolecular hairpin in a pH-dependent manner. Here, we evaluate the thermodynamic stability and nuclease sensitivity of oligonucleotides composed of the d(CGA) motif and several structurally related sequence variants. These results show that the structural transition resulting from decreasing the pH is accompanied by both a significant energetic stabilization and decreased nuclease sensitivity as unimolecular hairpin structures are converted to parallel-stranded homo-base paired duplexes. Furthermore, the stability of the parallel-stranded duplex form can be altered by changing the 5′-nucleobase of the d(CGA) triplet and the frequency and position of the altered triplets within long stretches of d(CGA) triplets. This work offers insight into the stability and versatility of the d(CGA) triplet repeat motif and provides constraints for using this pH-adaptive structural motif for creating DNA-based nanomaterials.STATEMENT OF SIGNIFICANCEThis article addresses the stability of the d(CGA) triplet motif and variants in solution. Our study reveals changes in thermodynamic stability and nuclease resistance in response to pH. The identity of the 5′-nucleobase within each triplet and the position and frequency of different triplets within stretches of d(CGA) triplets can tune parallel-stranded duplex stability. This tunability can be used for nanotechnological applications where the specificity of the 5′-nucleobase pairing interaction is used to order of long stretches of d(CGA) triplets. These results can inform the rational design of pH-sensitive structurally switchable DNA-based nanomaterials.

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

scholarly journals Fast-Scale Instability and Stabilization by Adaptive Slope Compensation of a PV-Fed Differential Boost Inverter

2021 ◽  
Vol 11 (5) ◽  
pp. 2106
Author(s):  
Abdelali El Aroudi ◽  
Mohamed Debbat ◽  
Mohammed Al-Numay ◽  
Abdelmajid Abouloiafa
Keyword(s):  
Numerical Simulations ◽  
Full Range ◽  
Weather Conditions ◽  
Current Loop ◽  
Point Tracking ◽  
Bifurcation Phenomena ◽  
Slope Compensation ◽  
Power Point ◽  
The Stability ◽  
Detailed Circuit

Numerical simulations reveal that a single-stage differential boost AC module supplied from a PV module under an Maximum Power Point Tracking (MPPT) control at the input DC port and with current synchronization at the AC grid port might exhibit bifurcation phenomena under some weather conditions leading to subharmonic oscillation at the fast-switching scale. This paper will use discrete-time approach to characterize such behavior and to identify the onset of fast-scale instability. Slope compensation is used in the inner current loop to improve the stability of the system. The compensation slope values needed to guarantee stability for the full range of operating duty cycle and leading to an optimal deadbeat response are determined. The validity of the followed procedures is finally validated by a numerical simulations performed on a detailed circuit-level switched model of the AC module.

scholarly journals Investigation on the Thermodynamic Stability of Nanocrystalline W-Based Alloys: A Combined Theoretical and Experimental Approach

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7179
Author(s):  
Francesco Torre ◽  
Claudio Mingazzini ◽  
Daniele Mirabile Gattia ◽  
Teodor Huminiuc ◽  
Antonio Rinaldi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermodynamic Stability ◽  
Experimental Approach ◽  
Metal Alloys ◽  
Model Predictions ◽  
The Stability ◽  
Experimental Findings ◽  
Constituent Elements ◽  
Segregated Structure ◽  
Nanostructured Metal

The stability of nanostructured metal alloys is currently being extensively investigated, and several mathematical models have been developed to describe the thermodynamics of these systems. However, model capability in terms of thermal stability predictions strongly relies on grain boundary-related parameters that are difficult to measure or estimate accurately. To overcome this limitation, a novel theoretical approach is proposed and adopted in this work to identify W-based nanocrystalline alloys which are potentially able to show thermodynamic stability. A comparison between model outcomes and experimental findings is reported for two selected alloys, namely W-Ag and W-Al. Experimental results clearly highlight that W-Ag mixtures retain a segregated structure on relatively coarse length scales even after prolonged mechanical treatments. Moreover, annealing at moderate temperatures readily induces demixing of the constituent elements. In contrast, homogeneous nanostructured W-Al solid solutions are obtained by ball milling of elemental powders. These alloys show enhanced thermal stability with respect to pure W even at high homologous temperatures. Experimental evidences agree with model predictions for both the investigated systems.

scholarly journals Thermodymanic Considerations on Gold Dissolution in Different Lixiviants (I)

2019 ◽  
Vol 70 (8) ◽  
pp. 2727-2732
Author(s):  
Catalin Alexandru Barbu ◽  
Ion Constantin ◽  
Mihnea Cosmin Costoiu ◽  
Mihai Buzatu ◽  
Augustin Semenescu
Keyword(s):  
Stability Constants ◽  
Thermodynamic Stability ◽  
Gold Dissolution ◽  
Gold Complexes ◽  
Electrode Potentials ◽  
Electrochemical Mechanism ◽  
The Stability ◽  
Cyanide Solutions ◽  
Gold Industry

The paper presents the main thermodynamic aspects related to gold dissolution in different lixiviants. We analyzedthe thermodynamic stability of the gold complexes with the most representative lixiviants with potential for use in the gold industry. Based on the stability constants we determined the electrode potentials of the gold dissolution reactions in variouslixiviants and we presented the electrochemical mechanism of gold dissolution is alkaline cyanide solutions.

scholarly journals THE PROBLEMS OF BRINGING RUSSIAN TRADE POLICY IN LINE WITH WTO REQUIREMENTS

2013 ◽  
pp. 146-152
Author(s):  
M. A. Petrova
Keyword(s):  
Trade Policy ◽  
Automotive Industry ◽  
New Technologies ◽  
Full Range ◽  
Economic Security ◽  
The European Union ◽  
Trade Dispute ◽  
National Economic ◽  
The Stability ◽  
Economic Zones

The article analyzes the role of trade policy in ensuring the competitiveness of the automotive industry – one of the most sensitive to the changes of economic conditions and important for providing national economic security – and finding a balance between the need to regulate the internal market and the implementation of the commitments under WTO. The analyze of the current condition of the Russian automotive industry has shown that, despite the low share in the world production and exports, Russia has a great potential for growth, mainly due to the unsaturated domestic market. It is proved, that the development of the automotive industry as one of the innovative industries in the country has all the necessary terms. Moreover, the priority areas for the development of the automotive industry include, first of all, the creation of a full range production with foreign investment. Measures of attracting and regulating FDI received much attention due to their relationship with the instruments of trade policy, as the production of capital goods, particularly automobiles, require imports of components, and FDI, in turn, promote the export of finished products. The commitments taken by Russia in the automotive industry include reduction of duties on imported cars, the renegotiation of investment programs and rules for the functioning of special economic zones. At present, the most acute question is car recycling tax, which has led to a trade dispute with the European Union, and may lead to countervailing measures against Russian goods. Considering WTO rules, recommendations on the use of the most effective instruments of foreign policy, aimed at improving the competitiveness of the Russian automotive industry, were made, including the rationalization of import and the attraction of new technologies due to the diversification of customs duties on certain groups of automotive components, lowering income taxes, a gradual decrease of the fiscal functions of the customs tariff; the stability and transparency of the instruments of trade policy and simplification of customs procedures.

scholarly journals The General Factor of Psychopathology

2020 ◽  
Vol 16 (1) ◽  
pp. 75-98 ◽  
Author(s):  
Gregory T. Smith ◽  
Emily A. Atkinson ◽  
Heather A. Davis ◽  
Elizabeth N. Riley ◽  
Joshua R. Oltmanns
Keyword(s):  
Mental Health Treatment ◽  
Full Range ◽  
Empirical Support ◽  
Strong Relationship ◽  
General Factor ◽  
General Factor Of Personality ◽  
The Stability ◽  
The Many ◽  
P Factor ◽  
Empirical Approaches

An important advance in understanding and defining mental disorders has been the development of empirical approaches to mapping dimensions of dysfunction and their interrelatedness. Such empirical approaches have consistently observed intercorrelations among the many forms of psychopathology, leading to the identification of a general factor of psychopathology (the p factor). In this article, we review empirical support for p, including evidence for the stability and criterion validity of p. Further, we discuss the strong relationship between p and both the general factor of personality and the general factor of personality disorder, substantive interpretations of p, and the potential clinical utility of p. We posit that proposed substantive interpretations of p do not explain the full range of symptomatology typically included in p. The most plausible explanation is that p represents an index of impairment that has the potential to inform the duration and intensity of a client's mental health treatment.

PHASE INSTABILITIES OF DISTORTED HEXAGONAL PATTERNS

2001 ◽  
Vol 11 (11) ◽  
pp. 2771-2777
Author(s):  
B. PEÑA ◽  
C. PÉREZ–GARCÍA
Keyword(s):  
Analytical Study ◽  
Full Range ◽  
Amplitude Equation ◽  
Phase Equation ◽  
Stability Regions ◽  
The Stability ◽  
Phase Instabilities

We present an analytical study on the stability of distorted hexagonal patterns. From a general amplitude equation we calculate the instabilities with respect to homogeneous and longwave perturbations. The latter lead to the phase equations that permit to determine the stability regions. Slightly squeezed hexagons are locally stable in a full range of distortion angles. The stability regions obtained from the phase equation are similar to those obtained numerically by other authors [Gunaratne et al., 1994].

Aromaticity in pericondensed cyclopenta-fused polycyclic aromatic hydrocarbons determined by density functional theory nucleus-independent chemical shifts and the Y-rule — Implications in oil asphaltene stability

2009 ◽  
Vol 87 (10) ◽  
pp. 1280-1295 ◽  
Author(s):  
Yosadara Ruiz-Morales
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Stability ◽  
Density Functional ◽  
Chemical Shifts ◽  
Functional Theory ◽  
Electronic Distribution ◽  
Polycyclic Aromatic ◽  
Minimum Number ◽  
The Stability ◽  
The One

The characterization of the stability of the fused aromatic region (FAR) in oil asphaltenes in terms of kinetic and thermodynamic stability is primary. Such an understanding is important if we are to get the optimal use from the heavy fraction of any crude oil. The FAR region is composed of pericondensed cyclopenta-fused polycyclic aromatic hydrocarbon compounds (CPPAHs) with N, S, and O heteroatoms. The Clar model, which states that the most important representation of a PAH is one having the maximum number of disjoint π-sextets, depicted by inscribed circles, and a minimum number of fixed double bonds, captures the essence of the kinetic and thermodynamic stability arguments. This model is readily employed for complex aromatics of the sort to be considered for asphaltenes. In the present research we prove that the aromaticity of CPPAHs can be assessed by using the qualitative easy-to-apply Y-rule. In the literature, it is proven that the Y-rule is applicable to elucidate the aromaticity of benzenoid PAHs and it has been validated for pericondensed benzenoid PAHs but not for pericondensed CPPAHs. Here, we verify that it is applicable for CPPAHs. The applicability of the Y-rule has been theoretically proven by comparing the π-electronic distribution obtained with it with the one obtained from nucleus-independent chemical shift (NICS) calculations at the density functional theory (DFT) level. The importance of doing this is that due to the polydispersity in the composition of the oil asphaltenes, and to understand their aromatic core structure, it is necessary to be able to asses the aromaticity of many cyclopenta-fused PAHs (possibly more than 500), of different sizes (up to 15 rings between hexagons and pentagons), and different spatial rearrangements in a quick but realistic and effective way. To try to do this with NICS will be very time consuming and computationally expensive, especially in the case of big systems.

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