Gamma crystallinity

Xu J, Chen J, Toptygin D, Tcherkasskaya O, Callis PR, King J, Brand L, Knutson J (2009) Femtosecond fluorescence spectra of tryptophan in human gamma-crystallin mutants site-dependent ultrafast quenching. J Am Chem Soc 131(46) 16751-16757... 

Chen J, Callis PR, King J (2009) Mechanism of the very efficient quenching of tryptophan fluorescence in human gamma D- and gamma S-crystallins the gamma-crystallin fold may have evolved to protect tryptophan residues from ultraviolet photodamage. Biochemistry 48(17) 3708-3716... 

Udupa, P.E., and Sharma, K.K. (2005) Effect of oxidized betaB3-crystallin peptide (152-166) on thermal aggregation of bovine lens gamma-crystallins identification of peptide interacting sites. Exp. Eye. Res. 80(2), 185-196. 

In addition to bulk density, particle crystallinity is another physical property that can be related to its hardness and potential effectiveness in providing the mechanical force in CMP. For example, alpha alumina abrasive has a higher hardness, thereby producing higher removal rate in comparison to its gamma crystalline counterpart [80]. As expected, the number of defects is also higher for alpha alumina due to the inherent hardness [81]. 

Ferro, D. R., Bruckner, S., Meille, S. V. and Ragazzi, M. (1992). Energy calculations for isotactic polypropylene—a comparison between models of the alpha-crystalline and gamma-crystalline structures. Macromolecules, 25, 5231-5. [182]... 

Figure 19.5 Microstructure of gamma crystalline isotactic polypropyiene...

Gamma-crystalline PA6 (Pleated sheet H-bonded slniclure)... 

There are at least three different classes of crystallins. The a and (3 are heterogeneous assemblies of different subunits specified by different genes, whereas the gamma (y) crystallins are monomeric proteins with a polypeptide chain of around 170 amino acid residues. The structure of one such Y crystallin was determined in the laboratory of Tom Blundell in London to 1.9 A resolution. A picture of this molecule generated from a graphics display is shown in Figure 5.11. 

Alumina is not widely used in modem HPLC [48]. Porous gamma alumina is prepared by dehydration and thermal treatment of crystalline bayerite [8,49]. It is available in several types with pore diameters from 6-lS nm, surface areas 70-250 m /g and pore volumes 0.2-0.3 ml/g. After conditioning with acid or base its apparent surface pH can be adjusted between pH 3-9. The alumina surface is more heterogeneous than silica containing both hydroxyl... 

Porter, R.R. Hydrolysis of rabbit gamma-globul in and antibodies with crystalline papain. Biochem J. 73 119-126, 1959. 

Isotactic polypropylene exhibits four crystalline structures alpha, beta, gamma and mesomorphic. Each of these structures forms under specific processing conditions and defines the properties of the polypropylene. In polypropylene containing the alpha, beta, and gamma... 

There are numerous examples of solid state polymerizations. Here we will briefly describe examples based on addition polymers. Generally, the crystalline monomer is irradiated with electrons or some form of high-energy radiation, such as gamma or x-rays. Since many monomers are solids only below room temperature, it is customary to begin irradiation at lower temperatures with the temperature raised only after initial polymerization occurs. (Some reactions are carried to completion at the lower temperature.) After polymerization, the monomer is removed. Table 6.10 contains a list of some of the common monomers that undergo solid-state irradiation polymerization. 

White crystals exists in three crystalline modifications alpha-, beta-, and gamma-Ga203 while the alpha-form is analogous to the corundum form of alumina, the beta-Ga203 is isomorphous with theta-alumina alpha-form converts to beta-modification on calcination at high temperatures (600°C) gamma form is stable at low temperatures density 6.44 g/cm (alpha-Ga203),... 

Silvery-white metal exhibits three crystalline modifications an orthorhombic alpha form, stable at ordinary temperatures and density 20.45 g/cm the alpha-form transforms to a tetragonal beta allotrope of density 19.36 g/cm when heated at 280°C the beta form converts to a body-centered cubic crystaUine gamma modification at 577°C, having a density 18.0 g/cm . 

Trigonal crystalline solid or amorphous powder mineral millerite has a yellow metallic luster color varies from yellow to brownish black density 5.30 to 6.65 g/cm3 exhibits three allotropic modifications (1) the acid-soluble amorphous alpha form obtained from nickel salt solution by precipitation with ammonium sulfide, (2) the alpha form rapidly transforms to a crystalline beta form as a brown colloidal dispersion upon exposure to air, and (3) a rhombo-hedral gamma modification found native as mineral millerite, which also can be prepared artificially under certain conditions. 

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