The Nature Of The Hydrogen Bond

The Nature of the Hydrogen Bond PDF
Author: Gastone Gilli
Publisher: OUP Oxford
Category : Science
Languages : en
Pages : 330
View: 605

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Book Description:
Hydrogen bond (H-bond) effects are known: it makes sea water liquid, joins cellulose microfibrils in trees, shapes DNA into genes and polypeptide chains into wool, hair, muscles or enzymes. Its true nature is less known and we may still wonder why O-H...O bond energies range from less than 1 to more than 30 kcal/mol without apparent reason. This H-bond puzzle is re-examined here from its very beginning and presented as an inclusive compilation of experimental H-bond energies and geometries. New concepts emerge from this analysis: new classes of systematically strong H-bonds (CAHBs and RAHBs: charge- and resonance-assisted H-bonds); full H-bond classification in six classes (the six chemical leitmotifs); and assessment of the covalent nature of strong H-bonds. This leads to three distinct but inter-consistent models able to rationalize the H-bond and predict its strength, based on classical VB theory, matching of donor-acceptor acid-base parameters (PA or pKa), or shape of the H-bond proton-transfer pathway. Applications survey a number of systems where strong H-bonds play an important functional role, namely drug-receptor binding, enzymatic catalysis, ion-transport through cell membranes, crystal design and molecular mechanisms of functional materials.


Tools And Modes Of Representation In The Laboratory Sciences

Tools and Modes of Representation in the Laboratory Sciences PDF
Author: U. Klein
Publisher: Springer Science & Business Media
Category : Philosophy
Languages : en
Pages : 264
View: 6184

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Book Description:
constitutive of reference in laboratory sciences as cultural sign systems and their manipulation and superposition, collectively shared classifications and associated conceptual frameworks,· and various fonns of collective action and social institutions. This raises the question of how much modes of representation, and specific types of sign systems mobilized to construct them, contribute to reference. Semioticians have argued that sign systems are not merely passive media for expressing preconceived ideas but actively contribute to meaning. Sign systems are culturally loaded with meaning stemming from previous practical applications and social traditions of applications. In new local contexts of application they not only transfer stabilized meaning but also can be used as active resources to add new significance and modify previous meaning. This view is supported by several analyses presented in this volume. Sign systems can be implemented like tools that are manipulated and superposed with other types of signs to forge new representations. The mode of representation, made possible by applying and manipulating specific types of representational tools, such as diagrammatic rather than mathematical representations, or Berzelian fonnulas rather than verbal language, contributes to meaning and forges fine-grained differentiations between scientists' concepts. Taken together, the essays contained in this volume give us a multifaceted picture of the broad variety of modes of representation in nineteenth-century and twentieth-century laboratory sciences, of the way scientists juxtaposed and integrated various representations, and of their pragmatic use as tools in scientific and industrial practice.


Early Days Of X Ray Crystallography

Early Days of X ray Crystallography PDF
Author: André Authier
Publisher: OUP Oxford
Category : Science
Languages : en
Pages : 464
View: 2675

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Book Description:
The year 2012 marked the centenary of one of the most significant discoveries of the early twentieth century, the discovery of X-ray diffraction (March 1912, by Laue, Friedrich and Knipping) and of Bragg's law (November 1912). The discovery of X-ray diffraction confirmed the wave nature of X-rays and the space-lattice hypothesis. It had two major consequences: the analysis of the structure of atoms, and the determination of the atomic structure of materials. This had a momentous impact in chemistry, physics, mineralogy, material science, biology and X-ray spectroscopy. The book relates the discovery itself, the early days of X-ray crystallography, and the way the news of the discovery spread round the world. It explains how the first crystal structures were determined by William Bragg and his son Lawrence, and recounts which were the early applications of X-ray crystallography in chemistry, mineralogy, materials science, physics, biological sciences and X-ray spectroscopy. It also tells how the concept of space lattice developed since ancient times up to the nineteenth century, and how our conception of the nature of light has changed over time. The contributions of the main actors of the story, prior to the discovery, at the time of the discovery and immediately afterwards, are described through their writings and are put into the context of the time, accompanied by brief biographical details. This thoroughly researched account on the multiple faces of a scientific specialty, X-ray crystallography, is aimed both at the scientists, who rarely subject the historical material of past discoveries in their field to particular scrutiny with regard to the historical details and at the historians of science who often lack the required expert knowledge to scrutinize the involved technical content in sufficient depth (M. Eckert - Metascience).


The Chemistry Of Weathering

The Chemistry of Weathering PDF
Author: J.I. Drever
Publisher: Springer Science & Business Media
Category : Science
Languages : en
Pages : 324
View: 3913

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Book Description:
Several important developments in our understanding of the chemistry of weathering have occurred in the last few years: 1. There has been a major breakthrough in our understanding of the mechanisms controlling the kinetics of sil icate dissolution, and there have been major advances in computer modeling of weathering processes. 2. There has been a growing recognition of the importance of organic solutes in the weathering process, and hence of the inter-relationships between mineral weathering and the terrestrial ecosystem. 3. The impact of acid deposition ("acid rain") has been widely recognized. The processes by which acid deposition is neutral ized are closely related to the processes of normal chemical weathering; an understanding of the chemistry of weathering is thus essential for predicting the effects of acid deposition. 4. More high-qual ity data have become available on the chemical dynamics of smal I watersheds and large river systems, which represent the integrated effects of chemical weathering.


The Man In The Monkeynut Coat

The Man in the Monkeynut Coat PDF
Author: Kersten T. Hall
Publisher: OUP Oxford
Category : Science
Languages : en
Pages : 256
View: 780

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Book Description:
Sir Isaac Newton once declared that his momentous discoveries were only made thanks to having 'stood on the shoulders of giants'. The same might also be said of the scientists James Watson and Francis Crick. Their discovery of the structure of DNA was, without doubt, one of the biggest scientific landmarks in history and, thanks largely to the success of Watson's best-selling memoir 'The Double Helix', there might seem to be little new to say about this story. But much remains to be said about the particular 'giants' on whose shoulders Watson and Crick stood. Of these, the crystallographer Rosalind Franklin, whose famous X-ray diffraction photograph known as 'Photo 51' provided Watson and Crick with a vital clue, is now well recognised. Far less well known is the physicist William T. Astbury who, working at Leeds in the 1930s on the structure of wool for the local textile industry, pioneered the use of X-ray crystallography to study biological fibres. In so doing, he not only made the very first studies of the structure of DNA culminating in a photo almost identical to Franklin's 'Photo 51', but also founded the new science of 'molecular biology'. Yet whilst Watson and Crick won the Nobel Prize, Astbury has largely been forgotten. The Man in the Monkeynut Coat tells the story of this neglected pioneer, showing not only how it was thanks to him that Watson and Crick were not left empty-handed, but also how his ideas transformed biology leaving a legacy which is still felt today.


The Physical Chemistry Of Solids

The Physical Chemistry of Solids PDF
Author: Richard John Borg
Publisher: Academic Press
Category : Science
Languages : en
Pages : 584
View: 1283

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Book Description:
The Physical Chemistry of Solids represents one of the first integrated textbooks available on solid state chemistry at an introductory level. Coauthored by two well-known experts, this textbook will provide instructors with the opportunity to develop a unified course on solid state chemistry at the upper-undergraduate/lower graduate level. All major aspects of solid state chemistry are covered as are the principles of chemical bonding and related mathematical concepts and operations. The book concludes each chapter with problem sets to facilitate teaching or self study.


Oxygen

Oxygen PDF
Author: Nick Lane
Publisher: OUP Oxford
Category : Science
Languages : en
Pages : 384
View: 7424

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Book Description:
Oxygen has had extraordinary effects on life. Three hundred million years ago, in Carboniferous times, dragonflies grew as big as seagulls, with wingspans of nearly a metre. Researchers claim they could have flown only if the air had contained more oxygen than today - probably as much as 35 per cent. Giant spiders, tree-ferns, marine rock formations and fossil charcoals all tell the same story. High oxygen levels may also explain the global firestorm that contributed to the demise of the dinosaurs after the asteroid impact. The strange and profound effects that oxygen has had on the evolution of life pose a riddle, which this book sets out to answer. Oxygen is a toxic gas. Divers breathing pure oxygen at depth suffer from convulsions and lung injury. Fruit flies raised at twice normal atmospheric levels of oxygen live half as long as their siblings. Reactive forms of oxygen, known as free radicals, are thought to cause ageing in people. Yet if atmospheric oxygen reached 35 per cent in the Carboniferous, why did it promote exuberant growth, instead of rapid ageing and death? Oxygen takes the reader on an enthralling journey, as gripping as a thriller, as it unravels the unexpected ways in which oxygen spurred the evolution of life and death. The book explains far more than the size of ancient insects: it shows how oxygen underpins the origin of biological complexity, the birth of photosynthesis, the sudden evolution of animals, the need for two sexes, the accelerated ageing of cloned animals like Dolly the sheep, and the surprisingly long lives of bats and birds. Drawing on this grand evolutionary canvas, Oxygen offers fresh perspectives on our own lives and deaths, explaining modern killer diseases, why we age, and what we can do about it. Advancing revelatory new ideas, following chains of evidence, the book ranges through many disciplines, from environmental sciences to molecular medicine. The result is a captivating vision of contemporary science and a humane synthesis of our place in nature. This remarkable book will redefine the way we think about the world.


Relaxation Of The Chemical Bond

Relaxation of the Chemical Bond PDF
Author: Chang Q Sun
Publisher: Springer
Category : Science
Languages : en
Pages : 807
View: 3268

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Book Description:
The aim of this book is to explore the detectable properties of a material to the parameters of bond and non-bond involved and to clarify the interdependence of various properties. This book is composed of four parts; Part I deals with the formation and relaxation dynamics of bond and non-bond during chemisorptions with uncovering of the correlation among the chemical bond, energy band and surface potential barrier (3B) during reactions; Part II is focused on the relaxation of bonds between atoms with fewer neighbors than the ideal in bulk with unraveling of the bond order-length-strength (BOLS) correlation mechanism, which clarifies the nature difference between nanostructures and bulk of the same substance; Part III deals with the relaxation dynamics of bond under heating and compressing with revealing of rules on the temperature-resolved elastic and plastic properties of low-dimensional materials; Part IV is focused on the asymmetric relaxation dynamics of the hydrogen bond (O:H-O) and the anomalous behavior of water and ice under cooling, compressing and clustering. The target audience for this book includes scientists, engineers and practitioners in the area of surface science and nanoscience.


Chemical Sciences In The 20th Century

Chemical Sciences in the 20th Century PDF
Author: Carsten Reinhardt
Publisher: John Wiley & Sons
Category : Science
Languages : en
Pages : 297
View: 6525

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Book Description:
Chemistry in the last century was characterized by spectacular growth and advances, stimulated by revolutionary theories and experimental breakthroughs. Yet, despite this rapid development, the history of this scientific discipline has achieved only recently the status necessary to understand the effects of chemistry on the scientific and technological culture of the modern world. This book addresses the bridging of boundaries between chemistry and the other "classical" disciplines of science, physics and biology as well as the connections of chemistry to mathematics and technology. Chemical research is represented as an interconnected patchwork of scientific specialties, and this is shown by a mixture of case studies and broader overviews on the history of organic chemistry, theoretical chemistry, nuclear- and cosmochemistry, solid state chemistry, and biotechnology. All of these fields were at the center of the development of twentieth century chemistry, and the authors cover crucial topics such as the emergence of new subdisciplines and research fields, the science-technology relationship, and national styles of scientific work. This monograph represents a unique treasure trove for general historians and historians of science, while also appealing to those interested in the theoretical background and development of modern chemistry.