Author: Abena Dove Osseo-Asare
Publisher: Cambridge University Press
ISBN: 1108471242
Category : History
Languages : en
Pages : 299
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Book Description
An innovative account of the first nuclear programme in independent Africa, centring on the promises and perils of atomic research in Ghana.
Author: Satoshi Kaneko
Publisher: Springer
ISBN: 9811044120
Category : Science
Languages : en
Pages : 92
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Book Description
This thesis describes improvements to and control of the electrical conductance in single-molecule junctions (SMJs), which have potential applications in molecular electronics, with a focus on the bonding between the metal and molecule. In order to improve the electrical conductance, the π orbital of the molecule is directly bonded to the metal orbital, because anchoring groups, which were typically used in other studies to bind molecule with metal electrodes, became resistive spacers. Using this direct π-binding, the author has successfully demonstrated highly conductive SMJs involving benzene, endohedral metallofullerene Ce@C82, and nitrogen. Subsequently, the author investigated control of the electrical conductance of SMJs using pyrazine. The nitrogen atom in the π-conjugated system of pyrazine was expected to function as an anchoring point, and two bonding states were expected. One originates primarily from the π orbital, while the other originates primarily from an n state of the nitrogen. Measurements of conductance and dI/dV spectra coupled with theoretical calculations revealed that the pyrazine SMJ has bistable conductance states, in which the pyrazine axis is either tilted or parallel with respect to the junction axis. The bistable states were switched by changing the gap size between the metal electrodes using an external force. Notably, it is difficult to change the electrical properties of bulk-state materials using mechanical force. The findings reveal that the electron transport properties of a SMJ can be controlled by designing a proper metal–molecule interface, which has considerable potential for molecular electronics. Moreover, this thesis will serve as a guideline for every step of SMJ research: design, fabrication, evaluation, and control.
Author: Abena Dove Osseo-Asare
Publisher: University of Chicago Press
ISBN: 022608616X
Category : Science
Languages : en
Pages : 309
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Book Description
For over a century, plant specialists worldwide have sought to transform healing plants in African countries into pharmaceuticals. And for equally as long, conflicts over these medicinal plants have endured, from stolen recipes and toxic tonics to unfulfilled promises of laboratory equipment and usurped personal patents. In Bitter Roots, Abena Dove Osseo-Asare draws on publicly available records and extensive interviews with scientists and healers in Ghana, Madagascar, and South Africa to interpret how African scientists and healers, rural communities, and drug companies—including Pfizer, Bristol-Myers Squibb, and Unilever—have sought since the 1880s to develop drugs from Africa’s medicinal plants. Osseo-Asare recalls the efforts to transform six plants into pharmaceuticals: rosy periwinkle, Asiatic pennywort, grains of paradise, Strophanthus, Cryptolepis, and Hoodia. Through the stories of each plant, she shows that herbal medicine and pharmaceutical chemistry have simultaneous and overlapping histories that cross geographic boundaries. At the same time, Osseo-Asare sheds new light on how various interests have tried to manage the rights to these healing plants and probes the challenges associated with assigning ownership to plants and their biochemical components. A fascinating examination of the history of medicine in colonial and postcolonial Africa, Bitter Roots will be indispensable for scholars of Africa; historians interested in medicine, biochemistry, and society; and policy makers concerned with drug access and patent rights.
Author: D. Hull
Publisher: Cambridge University Press
ISBN: 1107393183
Category : Technology & Engineering
Languages : en
Pages : 334
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Book Description
This edition has been greatly enlarged and updated to provide both scientists and engineers with a clear and comprehensive understanding of composite materials. In describing both theoretical and practical aspects of their production, properties and usage, the book crosses the borders of many disciplines. Topics covered include: fibres, matrices, laminates and interfaces; elastic deformation, stress and strain, strength, fatigue crack propagation and creep resistance; toughness and thermal properties; fatigue and deterioration under environmental conditions; fabrication and applications. Coverage has been increased to include polymeric, metallic and ceramic matrices and reinforcement in the form of long fibres, short fibres and particles. Designed primarily as a teaching text for final-year undergraduates in materials science and engineering, this book will also interest undergraduates and postgraduates in chemistry, physics, and mechanical engineering. In addition, it will be an excellent source book for academic and technological researchers on materials.
Author: Gabrielle Hecht
Publisher: MIT Press
ISBN: 0262300672
Category : History
Languages : en
Pages : 475
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Book Description
The hidden history of African uranium and what it means—for a state, an object, an industry, a workplace—to be “nuclear.” Uranium from Africa has long been a major source of fuel for nuclear power and atomic weapons, including the bomb dropped on Hiroshima. In 2003, after the infamous “yellow cake from Niger,” Africa suddenly became notorious as a source of uranium, a component of nuclear weapons. But did that admit Niger, or any of Africa's other uranium-producing countries, to the select society of nuclear states? Does uranium itself count as a nuclear thing? In this book, Gabrielle Hecht lucidly probes the question of what it means for something—a state, an object, an industry, a workplace—to be “nuclear.” Hecht shows that questions about being nuclear—a state that she calls “nuclearity”—lie at the heart of today's global nuclear order and the relationships between “developing nations” (often former colonies) and “nuclear powers” (often former colonizers). Hecht enters African nuclear worlds, focusing on miners and the occupational hazard of radiation exposure. Could a mine be a nuclear workplace if (as in some South African mines) its radiation levels went undetected and unmeasured? With this book, Hecht is the first to put Africa in the nuclear world, and the nuclear world in Africa. By doing so, she remakes our understanding of the nuclear age.
Author: James Jespersen
Publisher: Courier Corporation
ISBN: 0486409139
Category : Science
Languages : en
Pages : 322
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Book Description
Clear and accessible introduction to the concept of time examines measurement, historic timekeeping methods, uses of time information, role of time in science and technology, and much more. Over 300 illustrations.
Author: Camillo Peracchia
Publisher: Academic Press
ISBN: 0128163801
Category : Science
Languages : en
Pages : 230
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Book Description
Gap Junction Structure and Chemical Regulation: Direct Calmodulin Role in Cell-to-Cell Channel Gating describes and discusses the findings of major studies conducted during the past century on the structure and chemical regulation of direct cell-to-cell communication via gap junction channels. Chapters bring together important findings on direct cell communication, from its history, to its structure and regulation. These channels are essential for normal organ function, and mutations in their protein (connexin) cause various diseases. The book is useful for established investigators who need a review on the field and young investigators who need a thorough resource for study and comprehension. - Contains comprehensive, historical coverage on direct cell-to-cell communication - Provides detailed coverage of gap junction channel structure and regulation, with extensive coverage of the direct role of calmodulin in channel gating - Delivers a thorough description of models proposed for the chemical gating of gap junction channels
Author: Juan Carlos Cuevas
Publisher: World Scientific
ISBN: 9814282588
Category : Science
Languages : en
Pages : 724
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Book Description
This book provides a comprehensive overview of the rapidly developing field of molecular electronics. It focuses on our present understanding of the electrical conduction in single-molecule circuits and provides a thorough introduction to the experimental techniques and theoretical concepts. It will also constitute as the first textbook-like introduction to both the experiment and theory of electronic transport through single atoms and molecules. In this sense, this publication will prove invaluable to both researchers and students interested in the field of nanoelectronics and nanoscience in general. Molecular Electronics is self-contained and unified in its presentation. It may be used as a textbook on nanoelectronics by graduate students and advanced undergraduates studying physics and chemistry. In addition, included are previously unpublished material that will help researchers gain a deeper understanding into the basic concepts involved in the field of molecular electronics.
Author: Ransford Tetteh
Publisher: Graphic Communications Group
ISBN:
Category :
Languages : en
Pages : 64
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Book Description
Author: Cheol Seong Hwang
Publisher: Springer Science & Business Media
ISBN: 146148054X
Category : Science
Languages : en
Pages : 266
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Book Description
Offering thorough coverage of atomic layer deposition (ALD), this book moves from basic chemistry of ALD and modeling of processes to examine ALD in memory, logic devices and machines. Reviews history, operating principles and ALD processes for each device.
