Structural disturbances

Heusler alloys have a rich variety of apphcations, owing to some of their unique properties. Some of these phases are half-metallic ferromagnets, exhibiting semiconductor properties for the majority-spin electrons and normal metallic behavior for the minority-spin electrons. Therefore, the conduction electrons are completely polarized. The Ni2MnGa phase is used as a magnetic shape memory alloy and single crystals of Cu2MnAl are used to produce monochromatic beams of polarized neutrons. 

Inhomogeneous structural disturbances, of course, can only be understood by comparison to a reference standard, or ideal stmcture. The types of disturbances discussed will 

Defects can be further classified into point defects and extended defects. Unassociated point defects are associated with a single atomic site and are thus zero-dimensional. These include vacancies, interstitials, and impurities, which can be intrinsic or extrinsic in nature. Extended defects are multi-dimensional in space and include dislocations and stacking faults. These tend to be metastable, resulting from materials processing. The mechanical properties of solids are intimately related to the presence and dynamics of extended defects. A discussion of extended defects is deferred until Chapter 10. For now, only point defects are covered. Their importance in influencing the physical and chemical properties of materials cannot be overemphasized. 

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A number of mechanisms have been proposed by which this common irradiated state is obtained. The most widely accepted is the thermal spike theory, which considers the heat generated in the wake of a fast particle passing through a solid as being sufficient to cause severe structural disturbances which are then frozen in by rapid cooling. Many property changes can be explained by this theory (146). 

In animals, manganese deficiency results in wide-ranging disorders, e.g,. impaired growth, abnormal skeletal structure, disturbances of reproduction, and defective lipid and carbohydrate metabolism. Although overt manganese deficiency has nol been induced in humans, some forms of epilepsy... 

The retardation corresponds to a salt-in effect by water becoming more hydrophilic by large anions. The same series is obtained by hindering the gel formation228,240, 241 because structure-disturbing ions increase the content of non H-bonded OH groups in water. 

After thermalization, the electron may recombine with a positive ion or be captured by a molecule forming a negative ion, or it may be locked in a trap the role of which may be played by fluctuation cavities or structural disturbances in the medium, or by polarization pits that the electron digs when it interacts with surrounding molecules. Such captured electrons are called solvated electrons (in water they are sometimes called hydrated electrons).31,32 According to the data obtained in picosecond pulsed-radiolysis sets,33 34 the solvation time of an electron is 2 x 10-12 s in water and —10 11 s in methanol. 

In the case of some high-if experiments the uncertainty due to the nuclear structure disturbs any interpretations in terms of a test of quantum electrodynamics. However, the QED calculations are still important for the study of nuclear structure. 

There is a further analogy between the solvent actions exercised by water and a fused nonmetallic oxide. Just as water dissolves an electrolyte at the price of having its structure disturbed, so also the reaction resulting from the addition of a metallic oxide to a fused nonmetallic oxide like silica is equivalent to a bond mpture between the Si04 tetrahedra (Fig. 5.70). Solvent action occurs in fused oxide systems along with a certain breakdown of the network structures present in the pure liquid solvent (e.g., in pure liquid silica). 

Structural Disturbance and Lattice Relaxation in Molecular Crystal Packing Calculations. 

Sidorowicz V, Budziszewska D, Murawska T, et al. 1980. Structural disturbances in erythrocytes in workers exposed to carbon disulfide (CS2). Arh Hig Rada Toksikol 31 125-129. 

The effectiveness of the light in causing structural disturbances correlated with the effectiveness of light in mediating the photodestruction of chlorophyll. The structural disintegration was not related to the effect of the pyridazinones on the lipid composition of the plastid membrane si.nce structural changes did not occur in the presence of BASF 13 338 even though the lipid compositional effects had occurred. 

Some changes in side-chain can cause considerable structural disturbances in saccharides, some of which may exert important chemical and biological impact. Hu et have investigated NMR /-couplings involving the... 

The conditions for the formation of kink-bands within HM-HT fibres are the first part of the problem. The second part is what happens in repeated cycling. The axial compressive force causes the molecular buckling, and superficially the internal kink appears to be pulled out on retensioning. However, it seems likely that there is some residual structural disturbance, which becomes more severe after repeated cycling and leads to what appears to be crazing. Eventually failure occurs in the characteristic angled form of kink-band breaks, being the Achilles heel of HM-HT fibres. 

The APAA derivative has another virtue. Since it is an oxygen ester, it can be readily cleaved by alkali after the insertion reaction has taken place. Thus, after covalent linking, isolation, and characterization of the product, one macromolecule can be cleaved from the other, leaving only part of the probe with each. As each part can be separately labeled in the synthesis of APAA (Sections II,C, and II,D), it should be possible to label the contact site on each macromolecule with minimal structural disturbance. This feature may be important both for the test of regeneration of functional activity as well as for analysis of the site of attachment in certain cases. 

Disturbances in the steam supply can be suppressed at an early stage by the slave controller. This controller is trimmed by the master controller, which controls the temperature of the reactor. The reactor temperature controller has considerably slower dynamics. Through the use of this cascade control structure disturbances are eliminated. Without this structure, the reactor temperature would first have to change before control action is taken. 

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