The Physics of Complex Materials: Macroscopic Approaches

MRS Bulletin ◽  
1991 ◽  
Vol 16 (1) ◽  
pp. 17-19
Author(s):  
P.E. Cladis

The goal of this issue of the MRS BULLETIN, with its focus on the physics of complex materials, is to point out some of the fascinating features, both fundamental and applied, of complex materials: liquid crystals and polymers. Over the past 20 years, we have witnessed impressive advances in the understanding of liquid crystals and polymers on all fronts—physics, chemistry, materials research, and applications.Physicists are interested in the fundamentals of a phenomenon. Our assumption is that once we understand how the pieces of a System work, the understanding of how the whole System works immediately follows. However, those of us who have been involved in materials physics research quickly learn that complexity generates rules of its own on scales much larger than the microscopic scale of the molecules involved. Some-times these rules are beautifully simple and elegantly described, but most often they are not. The following articles high-light some important current research in the domain of complex materials, particularly for liquid crystals and polymers.Contributing to this special issue are: Pierre-Gilles de Gennes; J. William Doane; Wolfgang Meier and Heino Finkelmann; Paul Keyes; Patrick Oswald, John Bechhoefer and Francisco Melo; and Walter Zimmerman. They give us their current thinking on polymers in shear, novel electro-mechanical effects observed in polymeric liquid crystals, and how liquid crystals in a solid polymer matrix make useful high-speed color displays.

MRS Bulletin ◽  
2004 ◽  
Vol 29 (5) ◽  
pp. 308-313 ◽  
Author(s):  
Karen Scrivener ◽  
Henri Van Damme

AbstractThis article serves to introduce the May 2004 issue of MRS Bulletin on Construction Materials: From Innovation to Conservation. By volume, building materials are by far the most widely used type of materials. The most common construction materials—concrete and wood—are paradigms of complex and hierarchical materials, with a microstructure extending quasi-continuously down to the nanoscale. In the past, most improvements have been obtained by modifying the microstructure at the largest scales, for instance, by reducing the macroporosity. Recent advances in our understanding of the interactions and microstructure development show that the major levers for improvement from now on will rely on surface and colloid science and the science of complex materials, often at the nanoscale. This can lead to remarkable properties, such as self-compaction and ultrahigh strength, and even new functionality, such as self-cleaning through photocatalysis. Construction materials face a wide range of challenges today, many of which are linked to the need for more sustainable development: reducing the consumption of raw materials, reducing the energy used in processing, and increasing service life. In many parts of the world, there is also an increasing need to repair, rehabilitate, and conserve old buildings. The articles in this issue touch on these challenges as well as the advances being made in construction materials through materials research.


Author(s):  
William Krakow

In the past few years on-line digital television frame store devices coupled to computers have been employed to attempt to measure the microscope parameters of defocus and astigmatism. The ultimate goal of such tasks is to fully adjust the operating parameters of the microscope and obtain an optimum image for viewing in terms of its information content. The initial approach to this problem, for high resolution TEM imaging, was to obtain the power spectrum from the Fourier transform of an image, find the contrast transfer function oscillation maxima, and subsequently correct the image. This technique requires a fast computer, a direct memory access device and even an array processor to accomplish these tasks on limited size arrays in a few seconds per image. It is not clear that the power spectrum could be used for more than defocus correction since the correction of astigmatism is a formidable problem of pattern recognition.


Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions


1983 ◽  
Vol 80 ◽  
pp. 25-30 ◽  
Author(s):  
E.T. Samulski ◽  
D.B. Dupré

2013 ◽  
Vol 10 (2) ◽  
pp. 115-124
Author(s):  
Philip L. Martin

Japan and the United States, the world’s largest economies for most of the past half century, have very different immigration policies. Japan is the G7 economy most closed to immigrants, while the United States is the large economy most open to immigrants. Both Japan and the United States are debating how immigrants are and can con-tribute to the competitiveness of their economies in the 21st centuries. The papers in this special issue review the employment of and impacts of immigrants in some of the key sectors of the Japanese and US economies, including agriculture, health care, science and engineering, and construction and manufacturing. For example, in Japanese agriculture migrant trainees are a fixed cost to farmers during the three years they are in Japan, while US farmers who hire mostly unauthorized migrants hire and lay off workers as needed, making labour a variable cost.


CounterText ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 26-32
Author(s):  
Norbert Bugeja

In this retrospective piece, the Guest Editor of the first number of CounterText (a special issue titled Postcolonial Springs) looks back at the past five years from various scholarly and personal perspectives. He places particular focus on an event that took place mid-way between the 2011 uprisings across a number of Arab countries and the moment of writing: the March 2015 terror attack on the Bardo National Museum in Tunis, which killed twenty-two people and had a profound effect on Tunisian popular consciousness and that of the post-2011 Arab nations. In this context, the author argues for a renewed perspective on memoir as at once a memorial practice and a political gesture in writing, one that exceeds concerns of genre and form to encompass an ongoing project of political re-cognition following events that continue to remap the agenda for the region. The piece makes a brief final pitch for Europe's need to re-cognise, within those modes of ‘articulacy-in-difficulty’ active on its southern borders, specific answers to its own present quandaries.


2020 ◽  
Vol 50 (1-2) ◽  
pp. 58-66
Author(s):  
Giuliano Pancaldi

Here I survey a sample of the essays and reviews on the sciences of the long eighteenth century published in this journal since it was founded in 1969. The connecting thread is some historiographic reflections on the role that disciplines—in both the sciences we study and the fields we practice—have played in the development of the history of science over the past half century. I argue that, as far as disciplines are concerned, we now find ourselves a bit closer to a situation described in our studies of the long eighteenth century than we were fifty years ago. This should both favor our understanding of that period and, hopefully, make the historical studies that explore it more relevant to present-day developments and science policy. This essay is part of a special issue entitled “Looking Backward, Looking Forward: HSNS at 50,” edited by Erika Lorraine Milam.


Author(s):  
Peter H. Wiebe ◽  
Ann Bucklin ◽  
Mark Benfield

This chapter reviews traditional and new zooplankton sampling techniques, sample preservation, and sample analysis, and provides the sources where in-depth discussion of these topics is addressed. The net systems that have been developed over the past 100+ years, many of which are still in use today, can be categorized into eight groups: non-opening/closing nets, simple opening/closing nets, high-speed samplers, neuston samplers, planktobenthos plankton nets, closing cod-end samplers, multiple net systems, and moored plankton collection systems. Methods of sample preservation include preservation for sample enumeration and taxonomic morphological analysis, and preservation of samples for genetic analysis. Methods of analysis of zooplankton samples include determination of biomass, taxonomic composition, and size by traditional methods; and genetic analysis of zooplankton samples.


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