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Books > Science & Mathematics > Chemistry > Physical chemistry
This work establishes linear-scaling density-functional theory (DFT) as a powerful tool for understanding enzyme catalysis, one that can complement quantum mechanics/molecular mechanics (QM/MM) and molecular dynamics simulations. The thesis reviews benchmark studies demonstrating techniques capable of simulating entire enzymes at the ab initio quantum-mechanical level of accuracy. DFT has transformed the physical sciences by allowing researchers to perform parameter-free quantum-mechanical calculations to predict a broad range of physical and chemical properties of materials. In principle, similar methods could be applied to biological problems. However, even the simplest biological systems contain many thousands of atoms and are characterized by extremely complex configuration spaces associated with a vast number of degrees of freedom. The development of linear-scaling density-functional codes makes biological molecules accessible to quantum-mechanical calculation, but has yet to resolve the complexity of the phase space. Furthermore, these calculations on systems containing up to 2,000 atoms can capture contributions to the energy that are not accounted for in QM/MM methods (for which the Nobel prize in Chemistry was awarded in 2013) and the results presented here reveal profound shortcomings in said methods.
This thesis focuses on the controlled synthesis of Pt-Ni bimetallic nanoparticles and the study of their catalytic properties. It discusses in detail the nucleation mechanism and the growth process of bimetallic systems, which is vital for a deeper understanding of the design of bimetallic catalysts. The author presents four pioneering studies: (1) syntheses of water-soluble octahedral, truncated octahedral, and cubic Pt-Ni nanocrystals and the study of their structure-activity relationship in model hydrogenation reactions; (2) a strategy for designing a concave Pt-Ni alloy using controllable chemical etching; (3) defect-dominated shape recovery of nanocrystals, which is a new synthesis strategy for trimetallic catalysts; (4) a sophisticated construction of Au islands on Pt Ni, which is an ideal trimetallic nanoframe catalyst. This thesis inspires researchers working in materials, catalysis as well as other interdisciplinary areas.
Polymer electrolyte fuel cells (PEFCs) or proton exchange m- brane fuel cells (PEMFCs) have been suggested as alternatives to replace many existing energy conversion technologies, incl- inginternalcombustionenginesandbatteries.Themostsigni?cant advances in PEFC technology achieved in the last decade have occurredinareasrelatedtoautomotiveapplications,namelyco- start capabilities, enhanced durability and better understanding of watermanagementandmasstransportlosses. This volume of Modern Aspects of Electrochemistry is intendedtoprovideanoverviewofadvancementsinexperimental diagnosticsandmodelingofpolymerelectrolytefuelcells.Chapters byHuangandReifsniderandGuetal.provideanin-depthreview of the durability issues in PEFCs as well as recent developments in understanding and mitigation of degradation in the polymer membraneandelectrocatalyst. Enabling cold start, the startup of PEFC stacks from subzero temperatures, is a very important capability achieved only within thelastfewyears.TajiriandWangprovideatutorialoverviewofthe requirementsforcoldstart,andprovideasummaryofexperimental diagnosticsandcold-startmodelingstudies. Chapters 4-6 address speci?c diagnostic methods in PEFCs. Martin et al. provide a detailed review of methods for distributed diagnostics of species, temperature, and current in PEFCs in Chapter 4.In Chapter 5, Hussey and Jacobson describe the op- ationalprinciplesofneutronradiographyforin-situvisualizationof liquidwaterdistribution,andalsooutlineissuesrelatedtotemporal andspatialresolution.TsushimaandHiraidescribebothmagnetic resonance imaging (MRI) technique for visualization of water in PEFCsandtunablediodelaserabsorptionspectroscopy (TDLAS) formeasurementofwatervaporconcentrationinChapter6. Diffusionmedia(DM)areproneto?oodingwithliquidwater. AlthoughtheDMisanessentialcomponentofPEFCsthatenable distributionofspeciesandcollectionofcurrentandheat,littlewas knownaboutcapillarytransportinDMsuntilrecently.InChapters7 Gostick et al. provide a description of liquid water transport in porousDMduetocapillarityanddescribeexperimentaltechniques usedtocharacterizeDMproperties. v vi Preface The?naltwochaptersdiscussmodelingofPEFCs.Mukherjee and Wang provide an in-depth review of meso-scale modeling of two-phase transport, while Zhou et al. summarize both the s- ulation of electrochemical reactions on electrocatalysts and the transport of protons through the polymer electrolyte using at- isticsimulationtoolssuchasmoleculardynamicsandMonteCarlo techniques. Eachchapterinthevolumeisself-contained;thereforetheydo notneedtobereadinacertainorder. Special thanks are due to 23 authors who contributed to this volume.
In this book, the problem of electron and hole transport is approached from the point of view that a coherent and consistent physical theory can be constructed for transport phenomena. Along the road readers will visit some exciting citadels in theoretical physics as the authors guide them through the strong and weak aspects of the various theoretical constructions. Our goal is to make clear the mutual coherence and to put each theoretical model in an appropriate perspective. The mere fact that so many partial solutions have been proposed to describe transport, be it in condensed matter, fluids, or gases, illustrates that we are entering a world of physics with a rich variety of phenomena. Theoretical physics always seeks to provide a unifying picture. By presenting this tour of many very inventive attempts to build such a picture, it is hoped that the reader will be inspired and encouraged to help find the unifying principle behind the many faces of transport.
There is an increasing challenge for chemical industry and research institutions to find cost-efficient and environmentally sound methods of converting natural resources into fuels chemicals and energy. Catalysts are essential to these processes and the Catalysis Specialist Periodical Report series serves to highlight major developments in this area. This series provides systematic and detailed reviews of topics of interest to scientists and engineers in the catalysis field. The coverage includes all major areas of heterogeneous and homogeneous catalysis and also specific applications of catalysis such as NOx control kinetics and experimental techniques such as microcalorimetry. Each chapter is compiled by recognised experts within their specialist fields and provides a summary of the current literature. This series will be of interest to all those in academia and industry who need an up-to-date critical analysis and summary of catalysis research and applications. Catalysis will be of interest to anyone working in academia and industry that needs an up-to-date critical analysis and summary of catalysis research and applications. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading experts in their specialist fields, this series is designed to help the chemistry community keep current with the latest developments in their field. Each volume in the series is published either annually or biennially and is a superb reference point for researchers. www.rsc.org/spr
The need for properties is ever increasing to make processes more economical. A good survey of the viscosity data, its critical evaluation and correlation would help design engineers, scientists and technologists in their areas of interest. This type of work assumes more importance as the amount of experimental work in collection and correlation of properties such as viscosity, thermal conductivity, heat capacities, etc has reduced drastically both at the industry, universities, and national laboratories. One of the c o-authors, Professor Viswanath, co-authored a book jointly with Dr. Natarajan Data Book on the Viscosity of Liquids in 1989 which mainly presented collected and evaluated liquid viscosity data from the literature. Although it is one of its kinds in the field, Prof. Viswanath recognized that the design engineers, scientists and technologists should have a better understanding of theories, experimental procedures, and operational aspects of viscometers. Also, rarely the data are readily available at the conditions that are necessary for design of the equipment or for other calculations. Therefore, the data must be interpolated or extrapolated using the existing literature data and using appropriate correlations or models. We have tried to address these issues in this book."
Hydrogen bonds represent type of molecular interaction that
determines the structure and function of a large variety of
molecular systems. The elementary dynamics of hydrogen bonds and
related proton transfer reactions, both occurring in the ultra fast
time domain between 10-14 and 10-11s, form a research topic of high
current interest.
A thermodynamically consistent description of the transport across interfaces in mixtures has for a long time been an open issue. This research clarifies that the interface between a liquid and a vapor in a mixture is in local equilibrium during evaporation and condensation. It implies that the thermodynamics developed for interfaces by Gibbs can be applied also away from equilibrium, which is typically the case in reality. A description of phase transitions is of great importance for the understanding of both natural and industrial processes. For example, it is relevant for the understanding of the increase of CO2 concentration in the atmosphere, or improvements of efficiency in distillation columns. This excellent work of luminescent scientific novelty has brought this area a significant step forward. The systematic documentation of the approach will facilitate further applications of the theoretical framework to important problems.
Specialist Periodical Reports provide systematic and detailed review coverage of progress in the major areas of chemical research. Written by experts in their specialist fields the series creates a unique service for the active research chemist, supplying regular critical in-depth accounts of progress in particular areas of chemistry. For over 80 years the Royal Society of Chemistry and its predecessor, the Chemical Society, have been publishing reports charting developments in chemistry, which originally took the form of Annual Reports. However, by 1967 the whole spectrum of chemistry could no longer be contained within one volume and the series Specialist Periodical Reports was born. The Annual Reports themselves still existed but were divided into two, and subsequently three, volumes covering Inorganic, Organic and Physical Chemistry. For more general coverage of the highlights in chemistry they remain a 'must'. Since that time the SPR series has altered according to the fluctuating degree of activity in various fields of chemistry. Some titles have remained unchanged, while others have altered their emphasis along with their titles; some have been combined under a new name whereas others have had to be discontinued. The current list of Specialist Periodical Reports can be seen on the inside flap of this volume.
This book contains 99 of the papers that were presented at the 6th in the series of Symposia on Characterization of Porous Solids held in Alicante, Spain, May 2002. <br><br>Written by leading international specialists in the subject, the contributions represent an up-to-date and authoritative account of recent developments around the world in the major methods used to characterize porous solids. The book is a useful work of reference for anyone interested in characterizing porous solids, such as MCM-41 mesoporous materials, pillared clays, etc. Papers on pore structure determination using gas adsorption feature strongly, together with papers on small angle scattering methods, mercury porosimetry, microcalorimetry, scanning probe microscopies, and image analysis.
The author provides a unified account of the electrochemical material science of metal chalcogenide (MCh) compounds and alloys with regard to their synthesis, processing and applications. Starting with the chemical fundamentals of the chalcogens and their major compounds, the initial part of the book includes a systematic description of the MCh solids on the basis of the Periodic Table in terms of their structures and key properties. This is followed by a general discussion on the electrochemistry of chalcogen species, and the principles underlying the electrochemical formation of inorganic compounds/alloys. The core of the book offers an insight into available experimental results and inferences regarding the electrochemical preparation and microstructural control of conventional and novel MCh structures. It also aims to survey their photoelectrochemistry, both from a material-oriented point of view and as connected to specific processes such as photocatalysis and solar energy conversion. Finally, the book illustrates the relevance of MCh materials to various applications of electrochemical interest such as (electro)catalysis in fuel cells, energy storage with intercalation electrodes, and ion sensing.
I ?rst heard of k.p in a course on semiconductor physics taught by my thesis adviser William Paul at Harvard in the fall of 1956. He presented the k.p Hamiltonian as a semiempirical theoretical tool which had become rather useful for the interpre- tion of the cyclotron resonance experiments, as reported by Dresselhaus, Kip and Kittel. This perturbation technique had already been succinctly discussed by Sho- ley in a now almost forgotten 1950 Physical Review publication. In 1958 Harvey Brooks, who had returned to Harvard as Dean of the Division of Engineering and Applied Physics in which I was enrolled, gave a lecture on the capabilities of the k.p technique to predict and 't non-parabolicities of band extrema in semiconductors. He had just visited the General Electric Labs in Schenectady and had discussed with Evan Kane the latter's recent work on the non-parabolicity of band extrema in semiconductors, in particular InSb. I was very impressed by Dean Brooks's talk as an application of quantum mechanics to current real world problems. During my thesis work I had performed a number of optical measurements which were asking for theoretical interpretation, among them the dependence of effective masses of semiconductors on temperature and carrier concentration. Although my theoretical ability was rather limited, with the help of Paul and Brooks I was able to realize the capabilities of the k.p method for interpreting my data in a simple way."
This text is designed as a practical introduction to quantum chemistry. Quantum chemistry is applied to explain and predict molecular spectroscopy and the electronic structure of atoms and molecules. In addition, the text provides a practical guide to using molecular mechanics and electronic structure computations including ab initio, semi-empirical, and density functional methods. The use of electronic structure computations is a timely subject as its applications in both theoretical and experimental chemical research is increasingly prevalent. This text is written in a format that fosters mastery of the subject both in competency in the mathematics and in obtaining a conceptual understanding of quantum mechanics. The chemistry student's interest is maintained early on in the text where quantum mechanics is developed by applying it to molecular spectroscopy and through conceptual questions labeled as Chemical Connection. Questions throughout the text labeled as Chemical Connection and Points of Further Understanding focus on conceptual understanding and consequences of quantum mechanics. If an Instructor chooses, these questions can be used as a basis for classroom discussion encouraging cooperative learning techniques. This text provides a solid foundation from which students can readily build further knowledge of quantum chemistry in more advanced courses. In cases where this is a final course in quantum chemistry, this text provides the student not only with an appreciation of the importance of quantum mechanics to chemistry, but also with a practical guide to using electronic structure computations.
Chirality and stereogenicity are closely related concepts and their differentiation and description is still a challenge in chemoinformatics. In his 2015 book, Fujita developed a new stereoisogram approach that provided theoretical framework for mathematical aspects of modern stereochemistry. This new edition includes a new chapter on Computer-Oriented Representations developed by the author based on Groups, Algorithms, Programming (GAP) system.
The book deals with recent scientific highlights on molecular magnetism in Europe. Molecular magnetism is a new interdisciplinary discipline gathering together chemists and physicists, theoreticians and experimentalists. The book intends to provide the reader with documented answers to some current questions. How chemists can use soft conditions to transform molecules in light and transparent magnets? How a molecular system can behave as a single molecule magnet? How to combine several functions in the same molecular system? How light can be used to switch molecular magnetic properties? How can molecules be used for ultimate high density information storage or in quantum computing? What kind of methods do physicists develop and use to explore these new properties of matter? What kind of concepts and calculations can be provided for theoreticians to design new objects and to better understand the field and to enlarge its exciting developments?
Multiphase catalysis is a key technology for the competitive and sustainable production of fine chemicals in coming decades. A joint academic and industry consortium has developed tools for considering complex chemical and process-based requirements when setting up a catalytic system. This book shows how the resulting competence covers such supercritical fluid (SCF) technology in catalysis, ionic liquids (Il), ligand design for SFCs and Ils, thermomorphic solvent systems, reactor design and more.
Over the past 20 years aqueous organometallic catalysis has found applications in small- scale organic synthesis in the laboratory, as well as in the industrial production of chemicals with a combined output close to one million tons per year. Aqueous/organic two-phase reactions allow easy product-catalyst separation and full catalyst recovery which mean clear benefits not only in economic but also in environmental and green chemistry contexts. Instead of putting together a series of expert reviews of specialized fields, this book attempts to give a comprehensive yet comprehensible description of the various catalytic transformations in aqueous systems as seen by an author who has been working on aqueous organometallic catalysis since its origin. Emphasis is put on the discussion of differences between related non-aqueous and aqueous processes due to the presence of water. The book will be of interest to experts and students working in catalysis, inorganic chemistry or organic synthesis, and may serve as a basis for advanced courses.
In 2001 Wyn Roberts celebrated both his 70th birthday and 50 years of working in surface science, to use the term "surface science" in its broadest meaning. This book aims to mark the anniversary with a contribution of lasting value, something more than the usual festschrift issue of a relevant journal. The book is divided into three sections: Surface Science, Model Catalysts and Catalysis, topics in which Wyn has always had interests. The authors for each chapter were chosen from some of the many eminent scientists who have worked with Wyn in various ways and are all internationally acknowledged as leaders in their field. The authors have produced authoritative reviews of their own specialties which together result in a book with an unrivalled combination of breadth and depth exploring the most recent developments in surface chemistry and catalysis.
Crystal growth and nucleation are treated in the specialized literature in different ways depending on the discipline in question (physics, physical chemistry, chemical engineering) and on the theoretical approaches (atomistic vs continuum approach as regards crystal growth, phase vs chemical concept as regards nucleation). This book relates the different approaches to one another, giving preference to atomistic treatments by the methods of statistical thermodynamics and chemical kinetics. This unified approach also facilitates an understanding of some related phenomena of surface physics, such as adsorption, wetting etc. The book allows research novices and graduate students to get an insight into the physics of the phenomena and to interpret some of the experimental results.
Provides historical perspective as well as current data Abundantly illustrated with figures redrawn from literature data Covers all pertinent theory and physical chemistry Catalytic and chemotherapeutic applications are included
This volume of Modern Aspects contains a remarkable spread of topics covered in an authoritative manner by some internationally renowned specialists. In a seminal chapter Drs. Babu, Oldfield and Wieckowski demonstrate eloquently the strength of electrochemical nuclear magnetic resonance (EC-NMR) to study in situ both sides of the electrochemical interface via the simultaneous use of and This powerful non-invasive technique brings new insights to both fundamental and practical key aspects of electrocatalysis, including the design of better anodes for PEM fuel cells. The recent impressive advances in the use of rigorous ab initio quantum chemical calculations in electrochemistry are described in a remarkable chapter by Marc Koper, one of the leading protagonists in this fascinating area. This lucid chapter is addressed to all electrochemists, including those with very little prior exposure to quantum chemistry, and demonstrates the usefulness of ab initio calculations, including density functional theory (DFT) methods, to understand several key aspects of fuel cell electrocatalysis at the molecular level. The most important macroscopic and statistical thermodynamic models developed to describe adsorption phenomena on electrodes are presented critically in a concise and authoritative chapter by Panos Nikitas. The reader is guided through the seminal contributions of Frumkin, Butler, Bockris, Guidelli and others, to the current state of the art adsorption isotherms, which are both rigorous, and in good agreement with experiment.
Today high magnetic fields play an increasingly important role in many scientific fields. Formerly their use was largely restricted to the measurement of physical phenomena and the characterization of materials. But more recently they have found application in many new areas such as materials processing, crystal growth, and even in chemistry and biology. This book gives a broad survey of some of the most exciting recent applications of high magnetic fields, with the emphasis on materials science. These include, among others, the study of conventional and high-Tc superconductors, semiconductors, low-dimensional organic conductors, conducting polymers and protein crystallization. Each chapter begins with a general introduction and goes on to present detailed experimental results together with their interpretation. Researchers and students alike will find this book an excellent introduction to, and overview of current applications of static high magnetic fields.
The book is about calorimetry and thermal analysis methods, alone or linked to other techniques, as applied to the characterization of catalysts, supports and adsorbents, and to the study of catalytic reactions in various domains: air and wastewater treatment, clean and renewable energies, refining of hydrocarbons, green chemistry, hydrogen production and storage. The book is intended to fill the gap between the basic thermodynamic and kinetics concepts acquired by students during their academic formation, and the use of experimental techniques such as thermal analysis and calorimetry to answer practical questions. Moreover, it supplies insights into the various thermal and calorimetric methods which can be employed in studies aimed at characterizing the physico-chemical properties of solid adsorbents, supports and catalysts, and the processes related to the adsorption desorption phenomena of the reactants and/or products of catalytic reactions. The book also covers the basic concepts for physico-chemical comprehension of the relevant phenomena. Thermodynamic and kinetic aspects of the catalytic reactions can be fruitfully investigated by means of thermal analysis and calorimetric methods, in order to better understand the sequence of the elemental steps in the catalysed reaction. So the fundamental theory behind the various thermal analysis and calorimetric techniques and methods also are illustrated.
The book is devoted to the problem of microgeometry properties and anisotropy relations in modern piezo-active composites. These materials are characterized by various electromechanical properties and remarkable abilities to convert mechanical energy into electric energy and vice versa. Advantages of the performance of the composites are discussed in the context of the orientation effects, first studied by the authors for main connectivity patterns and with due regard to a large anisotropy of effective piezoelectric coefficients and electromechanical coupling factors. The novelty of the book consists in the systematization results of orientation effects, the anisotropy of piezoelectric properties and their role in forming considerable hydrostatic piezoelectric coefficients, electromechanical coupling factors and other parameters in the composites based on either ferroelectric ceramic or relaxor-ferroelectric single crystals.
This thesis examines various aspects of excess excitation energy dissipation via dynamic changes in molecular structure, vibrational modes and solvation. The computational work is carefully described and the results are compared to experimental data obtained using femtosecond spectroscopy and x-ray scattering. The level of agreement between theory and experiment is impressive and provides both a convincing validation of the method and significant new insights into the chemical dynamics and molecular determinants of the experimental data. Hence, the method presented in the thesis has the potential to become a very important contribution to the rapidly growing field of femtosecond x-ray science, a trend reflected in the several free-electron x-ray lasers (XFELs) currently being built around the world. Light-induced chemical processes are accompanied by molecular motion of electrons and nuclei on the femtosecond time scale. Uncovering these dynamics is central to our understanding of the chemical reaction on a fundamental level. Asmus O. Dohn has implemented a highly efficient QM/MM Direct Dynamics method for predicting the solvation dynamics of transition metal complexes in solution. |
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