Structure-controlled materials

The University developed a method of determination of the material residual strength, based on measurement of the change of phase velocity of ultrasonic waves, as well as an ultrasonic flaw detector-tomograph with multi-element transducers of the type of phased acoustic array. It enables control of the internal structure of materials and products of up to 300 mm thickness, with the resolution of up to 0.5 mm. In the same university, work on NDT is also carried out in the welding and electro-acoustic departments. 

For a given amplitude of the quasi-elastic release wave, the more the release wave approaches the ideal elastic-plastic response the greater the strength at pressure of the material. The lack of an ideally elastic-plastic release wave in copper appears to suggest a limited reversal component, however, this is much less than in the silicon bronze. Collectively, the differences in wave profiles between these two materials are consistent with a micro-structurally controlled Bauschinger component as supported by the shock-recovery results. Further study is required to quantify these findings and... 

The development of rubbers with a more closely controlled molecular structure. Such materials are made using anionic or Ziegler-Natta catalysts and are polymerised in solution (solution SBRs). 

Lipson (1943, 1944), who had examined a copper-nickeMron ternary alloy. A few years ago, on an occasion in honour of Mats Hillert, Cahn (1991) mapped out in masterly fashion the history of the spinodal concept and its establishment as a widespread alternative mechanism to classical nucleation in phase transformations, specially of the solid-solid variety. An excellent, up-to-date account of the present status of the theory of spinodal decomposition and its relation to experiment and to other branches of physics is by Binder (1991). The Hillert/Cahn/Hilliard theory has also proved particularly useful to modern polymer physicists concerned with structure control in polymer blends, since that theory was first applied to these materials in 1979 (see outline by Kyu 1993). 

To recapitulate, the legs of the imaginary tripod on which the structure of materials science is assembled are atoms and crystals phase equilibria microstructure. Of course, these are not wholly independent fields of study. Microstructure consists of phases geometrically disposed, phases are controlled by Gibbsian thermodynamics. 

The recent development of structurally controlled dendrimers has led to the development of a wide range of new functional macromolecules. These dendrimers were first applied in the fields of chemistry, including catalysis, pharmacology, and materials science [23-26]. More recently there have been several reports of dendrimers having electro active, photoactive, and recognition elements [27-34]. Important applications in photonics have recently been exploited, though the number of reports is still limited. 

Shenhar, R., Norsten, T.B. and Rotello, V.M. (2005) Polymer-mediated nanoparticle assembly structural control and applications. Advanced Materials, 17, 657-669. 

It is important that the method used to detach cells from their growing surface is compatible with end use. For final use as cell control material, it is important to use a methodology that preserves structural integrity and membrane protein localization. Enzymatic-based reagents may affect proteins on the surface of cells. 

Nanotechnology involves the manipulation of matter on atomic and molecular scales. This technology combines nanosized materials in order to create entirely new products ranging from computers to micromachines and includes even the quantum level operation of materials. The structural control of materials on the nanometer scale can lead to the realization of new material characteristics that are totally different from those realized by conventional methods, and it is expected to result in technological innovations in a variety of materials including metals, semiconductors, ceramics, and organic materials. 

The architecture of macromolecules is another important synthetic variable. New materials with controlled branching sequences or stereoregularity provide tremendous opportunity for development. New polymerization catalysts and initiators for controlled free-radical polymerization are driving many new materials design, synthesis, and production capabilities. Combined with state-of-the-art characterization by probe microscopy, radiation scattering, and spectroscopy, the field of polymer science is poised for explosive development of novel and important materials. New classes of nonlinear structured polymeric materials have been invented, such as dendrimers. These structures have regularly spaced branch points beginning from a central point—like branches from a tree trunk. New struc-... 

Harman, H. D., Jr., 1986, Detailed Stratigraphic and Structural Control The Key to Complete and Successful Geophysical Surveys of Hazardous Waste Sites In Proceedings of the Hazardous Materials Control Research Institute Conference on Hazardous Wastes and Hazardous Materials, Atlanta, GA, pp. 19-21. 

Zeolite catalysts play a vital role in modern industrial catalysis. The varied acidity and microporosity properties of this class of inorganic oxides allow them to be applied to a wide variety of commercially important industrial processes. The acid sites of zeolites and other acidic molecular sieves are easier to manipulate than those of other solid acid catalysts by controlling material properties, such as the framework Si/Al ratio or level of cation exchange. The uniform pore size of the crystalline framework provides a consistent environment that improves the selectivity of the acid-catalyzed transformations that form C-C bonds. The zeoHte structure can also inhibit the formation of heavy coke molecules (such as medium-pore MFl in the Cyclar process or MTG process) or the desorption of undesired large by-products (such as small-pore SAPO-34 in MTO). While faujasite, morden-ite, beta and MFl remain the most widely used zeolite structures for industrial applications, the past decade has seen new structures, such as SAPO-34 and MWW, provide improved performance in specific applications. It is clear that the continued search for more active, selective and stable catalysts for industrially important chemical reactions will include the synthesis and application of new zeolite materials. 

The binary representation is applicable to various other oxide materials. However, an important distinction can be made between borates and other main group element oxide systems, such as aluminates and silicates. In the latter systems cations predominantly reside at sites created by the demands of rigid anionic oxide frameworks. Although some degree of structural control may be obtained by varying cations or by use of template synthesis, the oxide frameworks of these systems tend to be relatively inflexible in comparison with... 

J. C.M. van Hest, D.A. Tirrell, Protein-based materials, tow/ard a new level of structural control, Chem. Common. 19 (2001) 1897-1904. 

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