Search results: Found 11

Listing 1 - 10 of 11 << page
of 2
>>
Sort by
Electrocatalysis in Fuel Cells

Author:
ISBN: 9783038422341 9783038422198 Year: Pages: XXX, 658 DOI: 10.3390/books978-3-03842-219-8 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2016-07-12 11:10:02
License:

First-Principles Approaches to Metals, Alloys, and Metallic Compounds

Author:
ISBN: 9783038973584 9783038973591 Year: Pages: 180 DOI: 10.3390/books978-3-03897-359-1 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Mining and Metallurgy --- Chemistry (General)
Added to DOAB on : 2018-11-26 11:24:24
License:

Loading...
Export citation

Choose an application

Abstract

Current fundamental electronic-structure theory allows for the accurate prediction and characterization of elemental metals adopting any allotropic structure, intermetallic compounds, and other metal-rich phases. From an engineering perspective, there is a need for structural materials that are suitable for mechanical and civil engineering as well as energy production and conversion. While different microstructural features influence the macroscopic behaviour, quantum-mechanical simulation may enormously accelerate and guide the entire development process since atomistic modelling allows for the generation of structural models and the calculation of enthalpies and other free energies as a function of pressure and temperature. Among other things, this volume covers high-manganese steels, some of which have come to light within Collaborative Research Centre 761 (“Steel ab initio”). In particular, it deals with short-range ordering from experiment and theory, also highlighting carbide-like precipitates, and it bridges the gap between atomistic and continuum levels, in particular for hydrogen embrittlement. Molecular dynamics simulates crack propagation, and first-principles theory helps in growing better intermetallic thin films and predicts structural and elastic properties. Eventually, multiscale modelling of hydrogen transport is provided, and the chemical reasons for H-trapping κ-carbides are highlighted. First-principles theory has acquired a powerful role in the fundamental and applied research of metals, alloys, and metallic compounds.

Quantum Mechanical/Molecular Mechanical Approaches for the Investigation of Chemical Systems - Recent Developments and Advanced Applications

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456260 Year: Pages: 188 DOI: 10.3389/978-2-88945-626-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-01-23 14:53:43
License:

Loading...
Export citation

Choose an application

Abstract

The QM/MM method, short for quantum mechanical/molecular mechanical, is a highly versatile approach for the study of chemical phenomena, combining the accuracy of quantum chemistry to describe the region of interest with the efficiency of molecular mechanical potentials to represent the remaining part of the system. Originally conceived in the 1970s by the influential work of the the Nobel laureates Martin Karplus, Michael Levitt and Arieh Warshel, QM/MM techniques have evolved into one of the most accurate and general approaches to investigate the properties of chemical systems via computational methods. Whereas the first applications have been focused on studies of organic and biomolecular systems, a large variety of QM/MM implementations have been developed over the last decades, extending the range of applicability to address research questions relevant for both solution and solid-state chemistry as well. Despite approaching their 50th anniversary in 2022, the formulation of improved QM/MM methods is still an active field of research, with the aim to (i) extend the applicability to address an even broader range of research questions in chemistry and related disciplines, and (ii) further push the accuracy achieved in the QM/MM description beyond that of established formulations. While being a highly successful approach on its own, the combination of the QM/MM strategy with other established theoretical techniques greatly extends the capabilities of the computational approaches. For instance the integration of a suitable QM/MM technique into the highly successful Monte-Carlo and molecular dynamics simulation protocols enables the description of the chemical systems on the basis of an ensemble that is in part constructed on a quantum-mechanical basis. This eBook presents the contributions of a recent Research Topic published in Frontiers in Chemistry, that highlight novel approaches as well as advanced applications of QM/MM method to a broad variety of targets. In total 2 review articles and 10 original research contributions from 48 authors are presented, covering 12 different countries on four continents. The range of research questions addressed by the individual contributions provide a lucid overview on the versatility of the QM/MM method, and demonstrate the general applicability and accuracy that can be achieved for different problems in chemical sciences. Together with the development of improved algorithms to enhance the capabilities of quantum chemical methods and the continuous advancement in the capacities of computational resources, it can be expected that the impact of QM/MM methods in chemical sciences will be further increased already in the near future.

Zweikomponentige Methoden im Rahmen der zeitabhängigen Dichtefunktionaltheorie - Theorie, Implementierung und Anwendung

Author:
ISBN: 9783731504283 Year: Pages: 215 p. DOI: 10.5445/KSP/1000048734 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Chemistry (General)
Added to DOAB on : 2019-07-30 20:01:59
License:

Loading...
Export citation

Choose an application

Abstract

This book reports on the derivation, implementation and application of two-component methods in the framework of time-dependent density functional theory. These methods allow the calculation of electronic transitions as well as the calculation of the correlation contribution to the electronic ground-state energy (RPA) and to the orbital energies (GW) including spin-orbit coupling. The focus of the applications is put on organic light-emitting diodes and clusters of heavy metals.

First-Principles Prediction of Structures and Properties in Crystals

Authors: ---
ISBN: 9783039216703 / 9783039216710 Year: Pages: 128 DOI: 10.3390/books978-3-03921-671-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-12-09 16:10:12
License:

Loading...
Export citation

Choose an application

Abstract

The term “first-principles calculations” is a synonym for the numerical determination of the electronic structure of atoms, molecules, clusters, or materials from ‘first principles’, i.e., without any approximations to the underlying quantum-mechanical equations. Although numerous approximate approaches have been developed for small molecular systems since the late 1920s, it was not until the advent of the density functional theory (DFT) in the 1960s that accurate “first-principles” calculations could be conducted for crystalline materials. The rapid development of this method over the past two decades allowed it to evolve from an explanatory to a truly predictive tool. Yet, challenges remain: complex chemical compositions, variable external conditions (such as pressure), defects, or properties that rely on collective excitations—all represent computational and/or methodological bottlenecks. This Special Issue comprises a collection of papers that use DFT to tackle some of these challenges and thus highlight what can (and cannot yet) be achieved using first-principles calculations of crystals.

Amide Bond Activation

Author:
ISBN: 9783039212033 / 9783039212040 Year: Pages: 466 DOI: 10.3390/books978-3-03921-204-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-08-28 11:21:27
License:

Loading...
Export citation

Choose an application

Abstract

The amide bond represents a privileged motif in chemistry. The recent years have witnessed an explosion of interest in the development of new chemical transformations of amides. These developments cover an impressive range of catalytic N–C bond activation in electrophilic, Lewis acid, radical, and nucleophilic reaction pathways, among other transformations. Equally relevant are structural and theoretical studies that provide the basis for chemoselective manipulation of amidic resonance. This monograph on amide bonds offers a broad survey of recent advances in activation of amides and addresses various approaches in the field.

Keywords

fumardiamide --- primaquine --- succindiamide --- Michael acceptor --- biofilm eradication --- antibacterial screening --- antiviral activity --- cytostatic activity --- N,N-dimethylformamide --- DMF --- N,N-dimethylacetamide --- DMAc --- amination --- amidation --- thioamidation --- formylation --- carbonylation --- cyanation --- insertion --- cyclization --- amide --- arynes --- insertion --- activation --- heterocycles --- organic synthesis --- multi-component coupling reaction --- aryl thioamides --- thiourea --- C-H/C-N activation --- C-S formation --- transition-metal-free --- rotational barrier energy --- amide bond --- nuclear magnetic resonance --- kinetic --- density functional theory --- non planar amide --- base-catalyed hydrolysis --- water solvation --- entropy --- transamidation --- amide --- amine --- catalyst --- catalysis --- acylative cross-coupling --- trialkylborane --- amide activation --- palladium --- N-heterocyclic carbene --- ruthenium (Ru) --- N-heterocyclic carbenes (NHCs) --- homogeneous catalysis --- in situ --- amide bonds --- synthesis --- density functional theory --- cis/trans isomerization --- secondary amides --- dipeptides --- steric effects --- tert-butyl --- additivity principle --- amino acid transporters --- amide bond --- gemcitabine prodrug --- metabolic stability --- pancreatic cancer cells --- pharmacokinetics --- peptide bond cleavage --- amide bond resonance --- twisted amides --- enzymes --- metal complexes --- catalysts --- amide C–N bond activation --- nickel catalysis --- amidation --- DFT study --- reaction thermodynamics --- amide resonance --- anomeric effect --- HERON reaction --- pyramidal amides --- physical organic chemistry --- reaction mechanism --- amide --- activation --- amidicity --- carbonylicity --- transamidation --- acyl transfer --- excited state --- Suzuki-Miyaura --- cross-coupling --- aryl esters --- C–O activation --- Pd-catalysis --- amides --- carbanions --- C–H acidity --- nitro-aci tautomerism --- molecular dynamics --- density-functional theory --- alkynes --- C–H bond cleavage --- C–N bond cleavage --- cyclopentadienyl complexes --- N-(1-naphthyl)acetamide --- rhodium --- [2+2+2] annulation --- amide bond --- sulfonamide bond --- alkynes --- addition reaction --- aminoacylation --- aminosulfonylation --- pre-catalysts --- palladium catalysis --- amide bond activation --- ester bond activation --- cross-coupling --- amide bond --- bridged lactams --- twisted amides --- amides --- Winkler-Dunitz parameters --- N–C activation --- hypersensitivity --- nitrogen heterocycles --- distortion --- bridged sultams --- amides --- C-N ? bond cleavage --- sodium --- crown ether --- amide hydrolysis --- model compound --- intramolecular catalysis --- twisted amide --- protease --- intein --- C-H functionalization --- directing groups --- amides --- transition metals --- catalysis

Novel Photoactive Materials

Author:
ISBN: 9783038976509 Year: Pages: 166 DOI: 10.3390/books978-3-03897-651-6 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Physics (General) --- Science (General)
Added to DOAB on : 2019-03-05 14:29:32
License:

Loading...
Export citation

Choose an application

Abstract

Photoactivity represents the ability of a material, generally speaking a semiconductor, to become active when interacting with light. It can be declined in many ways, and several functionalities arising from this behavior of materials can be exploited, all leading to positive repercussions on our environment. There are several classes of effects of photoactivity, all of which have been deeply investigated in the last few decades, allowing to develop more and more efficient materials and devices. All of them share a common point, that is, the interaction of a material with light, although many different materials are taken into account depending on the effect desired—from elemental semiconductors like silicon, to more complex compounds like CdTe or GaAs, to metal oxides like TiO2 and ZnO. Given the broadness of the field, a huge number of works fall within this topic, and new areas of discovery are constantly explored. The special issue “Novel Photoactive Materials” has been proposed as a means to present recent developments in the field, and for this reason the articles included touch different aspects of photoactivity, from photocatalysis to photovoltaics to light emitting materials.

Thin Films for Energy Harvesting, Conversion, and Storage

Authors: --- ---
ISBN: 9783039217243 / 9783039217250 Year: Pages: 174 DOI: 10.3390/books978-3-03921-725-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- Chemical Engineering
Added to DOAB on : 2019-12-09 11:49:16
License:

Loading...
Export citation

Choose an application

Abstract

Efficient clean energy harvesting, conversion, and storage technologies are of immense importance for the sustainable development of human society. To this end, scientists have made significant advances in recent years regarding new materials and devices for improving the energy conversion efficiency for photovoltaics, thermoelectric generation, photoelectrochemical/electrolytic hydrogen generation, and rechargeable metal ion batteries. The aim of this Special Issue is to provide a platform for research scientists and engineers in these areas to demonstrate and exchange their latest research findings. This thematic topic undoubtedly represents an extremely important technological direction, covering materials processing, characterization, simulation, and performance evaluation of thin films used in energy harvesting, conversion, and storage.

Cleaner Combustion

Authors: ---
ISBN: 9783039214778 / 9783039214785 Year: Pages: 196 DOI: 10.3390/books978-3-03921-478-5 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-12-09 11:49:16
License:

Loading...
Export citation

Choose an application

Abstract

This volume provides unique views of combustion from many technical and international research perspectives.

Removal of Organic Pollution in Water Environment

Authors: ---
ISBN: 9783039218400 / 9783039218417 Year: Pages: 154 DOI: 10.3390/books978-3-03921-841-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-12-09 11:49:16
License:

Loading...
Export citation

Choose an application

Abstract

The development of civilization entails a growing demand for consumer goods. A side effect of the production and use of these materials is the production of solid waste and wastewater. Municipal and industrial wastewater usually contains a large amount of various organic compounds and is the main source of pollution of the aquatic environment. Therefore, the search for effective methods of wastewater and other polluted water treatment is an important element of caring for the natural environment. This book presents research on the determination and removal of environmentally hazardous organic compounds from aqueous samples. The articles included in this book describe the results of examinations, at the laboratory scale, of the efficiency of chemical as well as physical processes for the removal or degradation of selected model pollutants. Environmental studies, especially those concerning the determination of trace impurities, require effective isolation and concentration procedures. The methods used for this purpose should meet the requirements of green chemistry. The liquid phase microextraction procedures and use of electrochemical methods described in this book seem to be proper for environmental studies, as they are effective and environmentally friendly.

Listing 1 - 10 of 11 << page
of 2
>>
Sort by
Narrow your search