Naomi E. Chayen, John R. Helliwell, and Edward H. Snell
- Published in print:
- 2010
- Published Online:
- May 2010
- ISBN:
- 9780199213252
- eISBN:
- 9780191707575
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199213252.003.0020
- Subject:
- Physics, Crystallography
This chapter summarizes the state‐of‐the‐art in the field and discusses upcoming techniques to solve and to improve the current problems.
This chapter summarizes the state‐of‐the‐art in the field and discusses upcoming techniques to solve and to improve the current problems.
William Clegg, Alexander J Blake, Jacqueline M Cole, John S O Evans, Peter Main, Simon Parsons, and David J Watkin (eds)
- Published in print:
- 2009
- Published Online:
- September 2009
- ISBN:
- 9780199219469
- eISBN:
- 9780191722516
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199219469.001.0001
- Subject:
- Physics, Crystallography
This book presents a less mathematical approach to X-ray crystal structure determination than is given in some detailed texts and concentrates on practical aspects. The book provides the necessary ...
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This book presents a less mathematical approach to X-ray crystal structure determination than is given in some detailed texts and concentrates on practical aspects. The book provides the necessary conceptual framework for understanding and applying the techniques described, but also gives practical advice on topics such as growing crystals, solving and refining structures, and understanding and using the results. There are also plenty of worked examples and problems provided (with answers), to reinforce the material presented. The book is based on the intensive course run by the Chemical Crystallography Group of the British Crystallographic Association every two years, and the material is drawn from the 2007 and 2009 courses. Much of the material of the first edition in 2001 has been significantly updated and expanded, and some new topics have been added. The approach to several of the topics is somewhat different as a result of changes in the authorship and the course teaching team. These changes reflect developments in the subject.Less
This book presents a less mathematical approach to X-ray crystal structure determination than is given in some detailed texts and concentrates on practical aspects. The book provides the necessary conceptual framework for understanding and applying the techniques described, but also gives practical advice on topics such as growing crystals, solving and refining structures, and understanding and using the results. There are also plenty of worked examples and problems provided (with answers), to reinforce the material presented. The book is based on the intensive course run by the Chemical Crystallography Group of the British Crystallographic Association every two years, and the material is drawn from the 2007 and 2009 courses. Much of the material of the first edition in 2001 has been significantly updated and expanded, and some new topics have been added. The approach to several of the topics is somewhat different as a result of changes in the authorship and the course teaching team. These changes reflect developments in the subject.
Naomi E. Chayen, John R. Helliwell, and Edward H. Snell
- Published in print:
- 2010
- Published Online:
- May 2010
- ISBN:
- 9780199213252
- eISBN:
- 9780191707575
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199213252.003.0012
- Subject:
- Physics, Crystallography
Macromolecular crystal structure analyses can be severely hampered by cases of twinning or of multiple crystals. However, increasingly, twinning can readily be recognized, notably when the X‐ray ...
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Macromolecular crystal structure analyses can be severely hampered by cases of twinning or of multiple crystals. However, increasingly, twinning can readily be recognized, notably when the X‐ray diffraction data are analyzed using intensity statistics. Remediation of such cases is possible via alteration of crystal‐growth conditions including use, mainly, of chemical additives. The case of multiple crystal growths likewise can hamper crystal‐structure analysis and although not necessarily associated with twinning is a crystal‐growth situation where similar remediation methods can be adopted, or portions of crystals ‘cut out’ or selected through use of X‐ray ‘microbeams’. There is also a nice body of case studies now in the crystallographic literature and several of these are highlighted in this chapter. Practical details of use of MAD, SAD or molecular replacement with different degrees of crystal twinning, as well as software to diagnose such cases, are described.Less
Macromolecular crystal structure analyses can be severely hampered by cases of twinning or of multiple crystals. However, increasingly, twinning can readily be recognized, notably when the X‐ray diffraction data are analyzed using intensity statistics. Remediation of such cases is possible via alteration of crystal‐growth conditions including use, mainly, of chemical additives. The case of multiple crystal growths likewise can hamper crystal‐structure analysis and although not necessarily associated with twinning is a crystal‐growth situation where similar remediation methods can be adopted, or portions of crystals ‘cut out’ or selected through use of X‐ray ‘microbeams’. There is also a nice body of case studies now in the crystallographic literature and several of these are highlighted in this chapter. Practical details of use of MAD, SAD or molecular replacement with different degrees of crystal twinning, as well as software to diagnose such cases, are described.
Naomi E. Chayen, John R. Helliwell, and Edward H. Snell
- Published in print:
- 2010
- Published Online:
- May 2010
- ISBN:
- 9780199213252
- eISBN:
- 9780191707575
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199213252.003.0001
- Subject:
- Physics, Crystallography
Macromolecules are the machinery of life and their function is determined by their 3D structure. Visual observation with a light microscope is not possible as the sizes of macromolecules are well ...
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Macromolecules are the machinery of life and their function is determined by their 3D structure. Visual observation with a light microscope is not possible as the sizes of macromolecules are well below the wavelength of visible light. X‐rays and neutrons allow visualization but they cannot be focused, so diffraction techniques have to be used. An understanding of the three‐dimensional macromolecular structure gives us a deeper understanding of basic biological concepts and processes, and reveals the cause of diseases, helps rational pharmaceutical design and can lead to the design of macromolecules with novel properties. Visualizing these macromolecules is a complex ballet involving diverse but interrelated fields of endeavour. In this chapter we cover an introduction to crystallization and X‐ray and neutron diffraction techniques. We distinguish between long‐ and short‐range order and introduce the rest of the book.Less
Macromolecules are the machinery of life and their function is determined by their 3D structure. Visual observation with a light microscope is not possible as the sizes of macromolecules are well below the wavelength of visible light. X‐rays and neutrons allow visualization but they cannot be focused, so diffraction techniques have to be used. An understanding of the three‐dimensional macromolecular structure gives us a deeper understanding of basic biological concepts and processes, and reveals the cause of diseases, helps rational pharmaceutical design and can lead to the design of macromolecules with novel properties. Visualizing these macromolecules is a complex ballet involving diverse but interrelated fields of endeavour. In this chapter we cover an introduction to crystallization and X‐ray and neutron diffraction techniques. We distinguish between long‐ and short‐range order and introduce the rest of the book.
John Jenkin
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780199235209
- eISBN:
- 9780191715631
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199235209.003.0008
- Subject:
- Physics, History of Physics
William explored teaching problems beyond the textbooks and was encouraged by AAAS meetings and the need to nominate students for the new 1851 Exhibition Research Scholarships. Lawrence began his ...
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William explored teaching problems beyond the textbooks and was encouraged by AAAS meetings and the need to nominate students for the new 1851 Exhibition Research Scholarships. Lawrence began his education, loved his grandparents' rambling home, and enjoyed family holidays by the sea. William led the development of a student union. His extension lectures were over-subscribed, particularly those on radio and the new X-rays. Willie fractured an elbow, which was X-rayed in his father's laboratory, a sign of the collaboration to come. William continued to facilitate University/School of Mines interaction and to foster teacher training and support. Ernest Rutherford, on his way to Cambridge, visited William at the university. Sir Thomas Elder's will funded a new Conservatorium of Music.Less
William explored teaching problems beyond the textbooks and was encouraged by AAAS meetings and the need to nominate students for the new 1851 Exhibition Research Scholarships. Lawrence began his education, loved his grandparents' rambling home, and enjoyed family holidays by the sea. William led the development of a student union. His extension lectures were over-subscribed, particularly those on radio and the new X-rays. Willie fractured an elbow, which was X-rayed in his father's laboratory, a sign of the collaboration to come. William continued to facilitate University/School of Mines interaction and to foster teacher training and support. Ernest Rutherford, on his way to Cambridge, visited William at the university. Sir Thomas Elder's will funded a new Conservatorium of Music.
Yoshio Suzuki, Hiroyuki Toda, and Christian Schroer
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780199213245
- eISBN:
- 9780191707582
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199213245.003.0007
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter describes the principles of Fresnel zone-plate (FZP) optics and imaging properties of FZP microscopy in the context of tomographic application. The limitation of zone-plate optics is ...
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This chapter describes the principles of Fresnel zone-plate (FZP) optics and imaging properties of FZP microscopy in the context of tomographic application. The limitation of zone-plate optics is discussed, and some typical examples of tomographic imaging experiment are shown. A brief introduction to reflective and refractive X-ray optics is presented since they are used for X-ray microscopy in the hard X-ray range relevant for materials research.Less
This chapter describes the principles of Fresnel zone-plate (FZP) optics and imaging properties of FZP microscopy in the context of tomographic application. The limitation of zone-plate optics is discussed, and some typical examples of tomographic imaging experiment are shown. A brief introduction to reflective and refractive X-ray optics is presented since they are used for X-ray microscopy in the hard X-ray range relevant for materials research.
Henning Friis Poulsen
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780199213245
- eISBN:
- 9780191707582
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199213245.003.0009
- Subject:
- Physics, Condensed Matter Physics / Materials
Three-dimensional X-ray diffraction (3DXRD) is a novel technique aimed at quick and non-destructive characterization of the individual elements within millimetre- to centimetre-sized specimens. It is ...
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Three-dimensional X-ray diffraction (3DXRD) is a novel technique aimed at quick and non-destructive characterization of the individual elements within millimetre- to centimetre-sized specimens. It is based on two principles: the use of highly penetrating hard X-rays from a synchrotron source (X-ray energies above 30 keV) and the application of ‘tomographic” reconstruction algorithms for the analysis of the diffraction data. This chapter outlines the 3DXRD methodology with the focus on characterizing grains and orientations. The chapter is organized as follows. The 3DXRD setup is presented and 3DXRD strategies discussed. Then, the standard modes of operation are presented in more detail with emphasis on reconstruction principles and providing selected examples of use. Next, a novel method called diffraction contrast tomography is proposed — this is related to 3DXRD in the same way as bright-field and dark-field images are in transmission electron microscopy. Finally, the mathematics underlying the 3DXRD diffraction geometry and the representation of the crystallographic orientation are summarized.Less
Three-dimensional X-ray diffraction (3DXRD) is a novel technique aimed at quick and non-destructive characterization of the individual elements within millimetre- to centimetre-sized specimens. It is based on two principles: the use of highly penetrating hard X-rays from a synchrotron source (X-ray energies above 30 keV) and the application of ‘tomographic” reconstruction algorithms for the analysis of the diffraction data. This chapter outlines the 3DXRD methodology with the focus on characterizing grains and orientations. The chapter is organized as follows. The 3DXRD setup is presented and 3DXRD strategies discussed. Then, the standard modes of operation are presented in more detail with emphasis on reconstruction principles and providing selected examples of use. Next, a novel method called diffraction contrast tomography is proposed — this is related to 3DXRD in the same way as bright-field and dark-field images are in transmission electron microscopy. Finally, the mathematics underlying the 3DXRD diffraction geometry and the representation of the crystallographic orientation are summarized.
John Jenkin
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780199235209
- eISBN:
- 9780191715631
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199235209.003.0013
- Subject:
- Physics, History of Physics
Radioactive ores discovered in outback South Australia were found by William to contain uranium minerals, and not developed commercially until many years later. At home he welcomed the birth of a ...
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Radioactive ores discovered in outback South Australia were found by William to contain uranium minerals, and not developed commercially until many years later. At home he welcomed the birth of a daughter, Gwendolen (‘Gwendy’), and began a new research project, the nature of X- and γ-rays, while at the university. European scientists believed they were waves, William suggested they were a neutral pair of positive and negative particles. The Englishman Charles Barkla vigorously promoted a wave picture of X-rays, while William defended his ‘neutral pair hypothesis’ for γ-rays, each presenting experimental evidence to support their position. A vigorous debate developed in the scientific literature, neither man giving way, and the dispute was unresolved.Less
Radioactive ores discovered in outback South Australia were found by William to contain uranium minerals, and not developed commercially until many years later. At home he welcomed the birth of a daughter, Gwendolen (‘Gwendy’), and began a new research project, the nature of X- and γ-rays, while at the university. European scientists believed they were waves, William suggested they were a neutral pair of positive and negative particles. The Englishman Charles Barkla vigorously promoted a wave picture of X-rays, while William defended his ‘neutral pair hypothesis’ for γ-rays, each presenting experimental evidence to support their position. A vigorous debate developed in the scientific literature, neither man giving way, and the dispute was unresolved.
William H. Boothby
- Published in print:
- 2009
- Published Online:
- May 2009
- ISBN:
- 9780199569946
- eISBN:
- 9780191705250
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199569946.003.0012
- Subject:
- Law, Public International Law
After a brief introduction to the topic, this chapter discusses three classes of weapon for which specific provision is made in Protocols to the Conventional Weapons Convention. In each case, the ...
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After a brief introduction to the topic, this chapter discusses three classes of weapon for which specific provision is made in Protocols to the Conventional Weapons Convention. In each case, the relevant protocol's provisions are given and their meaning is discussed. The participation of states in that protocol is revealed and the status of the relevant rule in customary law is explained. The applicability of the rule in non-international armed conflicts is then assessed, and the relevant section concludes with a brief discussion of the compliance arrangements relating to that Protocol. The weapons discussed in this chapter are weapons that primarily injure using fragments not detectable using X-rays, incendiary weapons, and blinding lasers. In each case, care is taken to explain which weapons are and are not caught by the relevant legal rules, noting that some of the rules prohibit the weapon affected by them while others consist of restrictions on the lawful use of such weapons.Less
After a brief introduction to the topic, this chapter discusses three classes of weapon for which specific provision is made in Protocols to the Conventional Weapons Convention. In each case, the relevant protocol's provisions are given and their meaning is discussed. The participation of states in that protocol is revealed and the status of the relevant rule in customary law is explained. The applicability of the rule in non-international armed conflicts is then assessed, and the relevant section concludes with a brief discussion of the compliance arrangements relating to that Protocol. The weapons discussed in this chapter are weapons that primarily injure using fragments not detectable using X-rays, incendiary weapons, and blinding lasers. In each case, care is taken to explain which weapons are and are not caught by the relevant legal rules, noting that some of the rules prohibit the weapon affected by them while others consist of restrictions on the lawful use of such weapons.
Dennis Sherwood and Jon Cooper
- Published in print:
- 2010
- Published Online:
- January 2011
- ISBN:
- 9780199559046
- eISBN:
- 9780191595028
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199559046.003.0001
- Subject:
- Physics, Crystallography
This chapter provides an introduction to the fundamental states of matter and the phenomenon of anisotropy which is attributable to the ordered solid state. Solids which possess molecular order over ...
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This chapter provides an introduction to the fundamental states of matter and the phenomenon of anisotropy which is attributable to the ordered solid state. Solids which possess molecular order over macroscopic distances are referred to as crystals. The remainder of the chapter introduces experimental methods of analysing the structure of crystals at the molecular level. The necessity for using electromagnetic radiation of a wavelength comparable to the dimensions of the molecule under study is explained, as is the need to use diffraction methods rather than microscopy for analysing their structures. The chapter concludes with a brief introduction to the properties of protein crystals, such as their fragility and high solvent content.Less
This chapter provides an introduction to the fundamental states of matter and the phenomenon of anisotropy which is attributable to the ordered solid state. Solids which possess molecular order over macroscopic distances are referred to as crystals. The remainder of the chapter introduces experimental methods of analysing the structure of crystals at the molecular level. The necessity for using electromagnetic radiation of a wavelength comparable to the dimensions of the molecule under study is explained, as is the need to use diffraction methods rather than microscopy for analysing their structures. The chapter concludes with a brief introduction to the properties of protein crystals, such as their fragility and high solvent content.
Graeme K. Hunter
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529217
- eISBN:
- 9780191712937
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529217.001.0001
- Subject:
- Physics, History of Physics
This book is a biography of William Lawrence Bragg, who was only twenty-five when he won the 1915 Nobel Prize in physics — the youngest person ever to win a Nobel Prize. It describes how Bragg ...
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This book is a biography of William Lawrence Bragg, who was only twenty-five when he won the 1915 Nobel Prize in physics — the youngest person ever to win a Nobel Prize. It describes how Bragg discovered the use of X-rays to determine the arrangement of atoms in crystals and his pivotal role in developing this technique to the point that structures of the most complex molecules known to man — the proteins and nucleic acids — could be solved. Although Bragg's Nobel Prize was for physics, his research profoundly affected chemistry and the new field of molecular biology, of which he became a founding figure — he was director of the research department where Crick and Watson discovered the structure of DNA. He held a number of important scientific posts, including Cavendish Professor of Experimental Physics at Cambridge University and Director of the Royal Institution of Great Britain. This book explains how these revolutionary scientific events occurred while Bragg struggled to emerge from the shadow of his father, Sir William Bragg, and amidst a career-long rivalry with the brilliant American chemist, Linus Pauling.Less
This book is a biography of William Lawrence Bragg, who was only twenty-five when he won the 1915 Nobel Prize in physics — the youngest person ever to win a Nobel Prize. It describes how Bragg discovered the use of X-rays to determine the arrangement of atoms in crystals and his pivotal role in developing this technique to the point that structures of the most complex molecules known to man — the proteins and nucleic acids — could be solved. Although Bragg's Nobel Prize was for physics, his research profoundly affected chemistry and the new field of molecular biology, of which he became a founding figure — he was director of the research department where Crick and Watson discovered the structure of DNA. He held a number of important scientific posts, including Cavendish Professor of Experimental Physics at Cambridge University and Director of the Royal Institution of Great Britain. This book explains how these revolutionary scientific events occurred while Bragg struggled to emerge from the shadow of his father, Sir William Bragg, and amidst a career-long rivalry with the brilliant American chemist, Linus Pauling.
Peter Hoskin and Wendy Makin
- Published in print:
- 2003
- Published Online:
- November 2011
- ISBN:
- 9780192628114
- eISBN:
- 9780191730115
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780192628114.003.0005
- Subject:
- Palliative Care, Patient Care and End-of-Life Decision Making, Pain Management and Palliative Pharmacology
This chapter provides an overview of radiotherapy. Radiotherapy is the method of treatment using ionizing radiation. Normally, radiation is in the form of X-rays or gamma rays which, when directed ...
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This chapter provides an overview of radiotherapy. Radiotherapy is the method of treatment using ionizing radiation. Normally, radiation is in the form of X-rays or gamma rays which, when directed through a cell, result in the ionization and destruction of DNA. Methods of delivering radiation include external X-ray beams and the use of radioisotopes. Radiation is potentially dangerous, hence administration of radiotherapy is usually done within a radiotherapy department. Radiotherapy plays a significant role in palliative care: it aids in the management of local symptoms such as pain, haemorrhage, and obstruction. Topics discussed in the chapter include the different kinds of radiation, radioisotope therapy, biological effects of radiation, and fractionation. The chapter also discusses the practicality of radiotherapy, and the practicality and efficiency of radiotherapy in palliative care.Less
This chapter provides an overview of radiotherapy. Radiotherapy is the method of treatment using ionizing radiation. Normally, radiation is in the form of X-rays or gamma rays which, when directed through a cell, result in the ionization and destruction of DNA. Methods of delivering radiation include external X-ray beams and the use of radioisotopes. Radiation is potentially dangerous, hence administration of radiotherapy is usually done within a radiotherapy department. Radiotherapy plays a significant role in palliative care: it aids in the management of local symptoms such as pain, haemorrhage, and obstruction. Topics discussed in the chapter include the different kinds of radiation, radioisotope therapy, biological effects of radiation, and fractionation. The chapter also discusses the practicality of radiotherapy, and the practicality and efficiency of radiotherapy in palliative care.
William Clegg
- Published in print:
- 2009
- Published Online:
- September 2009
- ISBN:
- 9780199219469
- eISBN:
- 9780191722516
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199219469.003.0022
- Subject:
- Physics, Crystallography
Crystal structure determination by diffraction uses X-rays or neutrons. X-rays are readily available in laboratories from a standard X-ray tube, in which electron kinetic energy is converted to ...
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Crystal structure determination by diffraction uses X-rays or neutrons. X-rays are readily available in laboratories from a standard X-ray tube, in which electron kinetic energy is converted to X-rays by interaction with core electrons of a metal target, giving particular characteristic wavelengths (and much wasted heat). Enhancements of the basic X-ray tube include rotating anodes and microfocus tubes, and the extracted X-rays can be concentrated somewhat by modern optics methods. Far higher X-ray intensities, together with other special properties, are obtained from synchrotron storage rings, which are large-scale national and international facilities; some of the properties are described, and an account given of applications. Neutrons are available from nuclear reactors and spallation sources, in monochromatic or pulsed polychromatic modes. Some advantages and disadvantages of neutrons, compared with X-rays, are described, resulting from their different interaction with samples.Less
Crystal structure determination by diffraction uses X-rays or neutrons. X-rays are readily available in laboratories from a standard X-ray tube, in which electron kinetic energy is converted to X-rays by interaction with core electrons of a metal target, giving particular characteristic wavelengths (and much wasted heat). Enhancements of the basic X-ray tube include rotating anodes and microfocus tubes, and the extracted X-rays can be concentrated somewhat by modern optics methods. Far higher X-ray intensities, together with other special properties, are obtained from synchrotron storage rings, which are large-scale national and international facilities; some of the properties are described, and an account given of applications. Neutrons are available from nuclear reactors and spallation sources, in monochromatic or pulsed polychromatic modes. Some advantages and disadvantages of neutrons, compared with X-rays, are described, resulting from their different interaction with samples.
Graeme K. Hunter
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780198529217
- eISBN:
- 9780191712937
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529217.003.0003
- Subject:
- Physics, History of Physics
This chapter details the life of William Lawrence Bragg from 1909–14. In the spring of 1910, Bragg competed in the Trinity scholarships examination. The Master of Trinity, Montagu Butler, read his ...
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This chapter details the life of William Lawrence Bragg from 1909–14. In the spring of 1910, Bragg competed in the Trinity scholarships examination. The Master of Trinity, Montagu Butler, read his essays and commented upon the ‘brilliant imagination’ shown in them. Bragg was awarded a College Senior Mathematical Scholarship. By the beginning of his second year Bragg had switched from the Mathematical Tripos to the Natural Sciences Tripos — in effect, dropping mathematics in favor of physics. Father and son joined forces during the Christmas holiday of 1912–13, studying the radiation reflected by crystals of rock salt.Less
This chapter details the life of William Lawrence Bragg from 1909–14. In the spring of 1910, Bragg competed in the Trinity scholarships examination. The Master of Trinity, Montagu Butler, read his essays and commented upon the ‘brilliant imagination’ shown in them. Bragg was awarded a College Senior Mathematical Scholarship. By the beginning of his second year Bragg had switched from the Mathematical Tripos to the Natural Sciences Tripos — in effect, dropping mathematics in favor of physics. Father and son joined forces during the Christmas holiday of 1912–13, studying the radiation reflected by crystals of rock salt.
André Authier
- Published in print:
- 2013
- Published Online:
- September 2013
- ISBN:
- 9780199659845
- eISBN:
- 9780191748219
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199659845.003.0004
- Subject:
- Physics, Crystallography
The circumstances surrounding Röntgen’s discovery of X-rays are related, as well as the detailed investigations he made on the properties of X-rays before announcing the discovery. An account of his ...
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The circumstances surrounding Röntgen’s discovery of X-rays are related, as well as the detailed investigations he made on the properties of X-rays before announcing the discovery. An account of his career in research before his discovery is also presented. The swift spreading of the news of the discovery throughout the world, and the general excitement it generated, are recounted. Further studies of Röntgen on the new radiation are then described, and prior observations by other investigators of what may have been X-rays are discussed. The last part of the chapter is devoted to the rays studied by Lenard, which were cathode rays. Lenard probably also observed X-rays, but he did not characterize them.Less
The circumstances surrounding Röntgen’s discovery of X-rays are related, as well as the detailed investigations he made on the properties of X-rays before announcing the discovery. An account of his career in research before his discovery is also presented. The swift spreading of the news of the discovery throughout the world, and the general excitement it generated, are recounted. Further studies of Röntgen on the new radiation are then described, and prior observations by other investigators of what may have been X-rays are discussed. The last part of the chapter is devoted to the rays studied by Lenard, which were cathode rays. Lenard probably also observed X-rays, but he did not characterize them.
Helge Kragh
- Published in print:
- 2012
- Published Online:
- May 2012
- ISBN:
- 9780199654987
- eISBN:
- 9780191741692
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199654987.003.0003
- Subject:
- Physics, History of Physics, Atomic, Laser, and Optical Physics
Bohr’s theory was generally well received, although few physicists accepted the postulates on which it rested. It was found attractive because of its explanatory and predictive power. This chapter ...
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Bohr’s theory was generally well received, although few physicists accepted the postulates on which it rested. It was found attractive because of its explanatory and predictive power. This chapter details the reception of the theory from 1913 to about 1916, mostly in England, Germany, and the United States, including the opposition it met from conservative physicists and chemists. It is argued that this opposition was substantial and often justified, but also that it had little effect on the further development of Bohr’s theory. The Stark effect, discovered in 1913, had a major impact on how the theory was received in Germany, and its role is explained. In addition, the little known case of triatomic hydrogen is considered, and also the support that Bohr’s views received from H. Moseley’s pioneering research on characteristic X-rays.Less
Bohr’s theory was generally well received, although few physicists accepted the postulates on which it rested. It was found attractive because of its explanatory and predictive power. This chapter details the reception of the theory from 1913 to about 1916, mostly in England, Germany, and the United States, including the opposition it met from conservative physicists and chemists. It is argued that this opposition was substantial and often justified, but also that it had little effect on the further development of Bohr’s theory. The Stark effect, discovered in 1913, had a major impact on how the theory was received in Germany, and its role is explained. In addition, the little known case of triatomic hydrogen is considered, and also the support that Bohr’s views received from H. Moseley’s pioneering research on characteristic X-rays.
André Authier
- Published in print:
- 2013
- Published Online:
- September 2013
- ISBN:
- 9780199659845
- eISBN:
- 9780191748219
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199659845.003.0005
- Subject:
- Physics, Crystallography
This chapter relates the discussions which took place before the discovery of X-ray diffraction as to the real nature, wave or corpuscular, of X-rays. Similar discussions as to the nature of ...
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This chapter relates the discussions which took place before the discovery of X-ray diffraction as to the real nature, wave or corpuscular, of X-rays. Similar discussions as to the nature of electrons are first reviewed. A pulse theory was proposed independently by Wiechert, Stokes, and Thomson for the nature of X-rays. The observation of secondary radiation by various authors is then recounted, and Thomson’s theory of X-ray scattering is summarized. The next steps were the observations by Barkla of the polarization of X-rays, and of characteristic X-rays. At the same time came W. H. Bragg’s suggestion that X-rays were in fact neutral pairs constituted by a positive and a negative particle. A sharp controversy between Bragg and Barkla ensued. In order to test the validity of the pulse theory, attempts were made to observe the diffraction of X-rays by a slit. From the results, Sommerfeld made an estimate of X-ray wavelengths. These were also estimated by Wien and Stark using the Planck—Einstein relation. Stark went further and elaborated a corpuscular theory for X-rays, about which he entered into a controversy with Sommerfeld.Less
This chapter relates the discussions which took place before the discovery of X-ray diffraction as to the real nature, wave or corpuscular, of X-rays. Similar discussions as to the nature of electrons are first reviewed. A pulse theory was proposed independently by Wiechert, Stokes, and Thomson for the nature of X-rays. The observation of secondary radiation by various authors is then recounted, and Thomson’s theory of X-ray scattering is summarized. The next steps were the observations by Barkla of the polarization of X-rays, and of characteristic X-rays. At the same time came W. H. Bragg’s suggestion that X-rays were in fact neutral pairs constituted by a positive and a negative particle. A sharp controversy between Bragg and Barkla ensued. In order to test the validity of the pulse theory, attempts were made to observe the diffraction of X-rays by a slit. From the results, Sommerfeld made an estimate of X-ray wavelengths. These were also estimated by Wien and Stark using the Planck—Einstein relation. Stark went further and elaborated a corpuscular theory for X-rays, about which he entered into a controversy with Sommerfeld.
Joe Nickell
- Published in print:
- 2009
- Published Online:
- September 2011
- ISBN:
- 9780813125343
- eISBN:
- 9780813135229
- Item type:
- chapter
- Publisher:
- University Press of Kentucky
- DOI:
- 10.5810/kentucky/9780813125343.003.0011
- Subject:
- History, Social History
This chapter investigates if the photographs and videotapes of the assassin of President John F. Kennedy really depict ex-marine Lee Harvey Oswald. The first scientific attempt to identify felons ...
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This chapter investigates if the photographs and videotapes of the assassin of President John F. Kennedy really depict ex-marine Lee Harvey Oswald. The first scientific attempt to identify felons began in 1860. Fingerprints are the mainstay of identification. However, in some cases where there are too few ridge characteristics to make a positive fingerprint identification, the pattern of tiny pores along the ridges is employed, a method known as poroscopy. Like fingerprints, the patterns of the palms and the soles of the feet may prove valuable. Lip impressions, bite marks, and dental X-rays are other methods for identification. It examines Eddowes's theory explaining that Lee Harvey Oswald has a double. However this theory was contradicted by other experts.Less
This chapter investigates if the photographs and videotapes of the assassin of President John F. Kennedy really depict ex-marine Lee Harvey Oswald. The first scientific attempt to identify felons began in 1860. Fingerprints are the mainstay of identification. However, in some cases where there are too few ridge characteristics to make a positive fingerprint identification, the pattern of tiny pores along the ridges is employed, a method known as poroscopy. Like fingerprints, the patterns of the palms and the soles of the feet may prove valuable. Lip impressions, bite marks, and dental X-rays are other methods for identification. It examines Eddowes's theory explaining that Lee Harvey Oswald has a double. However this theory was contradicted by other experts.
James Lawrence Powell
- Published in print:
- 2014
- Published Online:
- November 2015
- ISBN:
- 9780231164481
- eISBN:
- 9780231538459
- Item type:
- chapter
- Publisher:
- Columbia University Press
- DOI:
- 10.7312/columbia/9780231164481.003.0005
- Subject:
- Environmental Science, Environmental Studies
This chapter focuses on the initiatives of various physicists and chemists to explore the strange new rays called X-rays that were discovered by Wilhelm Röntgen in 1895. The decade of the 1890s was a ...
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This chapter focuses on the initiatives of various physicists and chemists to explore the strange new rays called X-rays that were discovered by Wilhelm Röntgen in 1895. The decade of the 1890s was a time of great progress in science. No year in that decade was more eventful than 1895. In Sweden, Svante Arrhenius was calculating the effect of atmospheric carbon dioxide on global temperature, while in Britain John Perry was exposing the fallacy of Kelvin's assumptions about the age of the Earth. The Scottish chemist William Ramsay discovered helium, previously known only from the Sun's spectrum, in an earthly mineral. That same year, at the University of Wurzburg in Germany, Röntgen was investigating the properties of cathode rays that led to his discovery of X-rays. This chapter also looks at the work of Marie Curie on radioactivity and of Ernest Rutherford and Frederick Soddy on radioactive decay.Less
This chapter focuses on the initiatives of various physicists and chemists to explore the strange new rays called X-rays that were discovered by Wilhelm Röntgen in 1895. The decade of the 1890s was a time of great progress in science. No year in that decade was more eventful than 1895. In Sweden, Svante Arrhenius was calculating the effect of atmospheric carbon dioxide on global temperature, while in Britain John Perry was exposing the fallacy of Kelvin's assumptions about the age of the Earth. The Scottish chemist William Ramsay discovered helium, previously known only from the Sun's spectrum, in an earthly mineral. That same year, at the University of Wurzburg in Germany, Röntgen was investigating the properties of cathode rays that led to his discovery of X-rays. This chapter also looks at the work of Marie Curie on radioactivity and of Ernest Rutherford and Frederick Soddy on radioactive decay.
Brent R. Stockwell
- Published in print:
- 2013
- Published Online:
- November 2015
- ISBN:
- 9780231152136
- eISBN:
- 9780231525527
- Item type:
- chapter
- Publisher:
- Columbia University Press
- DOI:
- 10.7312/columbia/9780231152136.003.0007
- Subject:
- Public Health and Epidemiology, Public Health
This chapter examines why some proteins are more susceptible to modulation by small molecule drugs than other proteins. To this end, the chapter presents an atom-by-atom picture of proteins and where ...
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This chapter examines why some proteins are more susceptible to modulation by small molecule drugs than other proteins. To this end, the chapter presents an atom-by-atom picture of proteins and where and how small molecules bind to proteins. The emergence of a powerful new field of science known as structural biology in the twentieth century enabled the visualization of the atomic-level detail of proteins. The field of structural biology was born in 1895, when William Roentgen discovered X-rays. The chapter begins with an overview of the birth of X-ray crystallography and proceeds by discussing the application of X-ray methods to proteins. It then considers the development of an approach that involved the magnetic properties of atoms to determine protein structures, and how knowledge of the atom-by-atom picture of protein molecules helped to unravel disease mechanisms and to create new therapeutic agents for diseases such as sickle-cell anemia. It also looks at the use of computers, with particular emphasis on virtual screening, in drug design and concludes by turning to the advent of fragment-based drug discovery.Less
This chapter examines why some proteins are more susceptible to modulation by small molecule drugs than other proteins. To this end, the chapter presents an atom-by-atom picture of proteins and where and how small molecules bind to proteins. The emergence of a powerful new field of science known as structural biology in the twentieth century enabled the visualization of the atomic-level detail of proteins. The field of structural biology was born in 1895, when William Roentgen discovered X-rays. The chapter begins with an overview of the birth of X-ray crystallography and proceeds by discussing the application of X-ray methods to proteins. It then considers the development of an approach that involved the magnetic properties of atoms to determine protein structures, and how knowledge of the atom-by-atom picture of protein molecules helped to unravel disease mechanisms and to create new therapeutic agents for diseases such as sickle-cell anemia. It also looks at the use of computers, with particular emphasis on virtual screening, in drug design and concludes by turning to the advent of fragment-based drug discovery.
