Isomorphism crystals

Hundreds of crystals were exposed in several synchrotron beam time periods, bearing in mind that there was little chance to solve the inherent problem of how to produce derivative crystals. It was a relief though, that 508 particles from a mutant of B. stearothermophilus lacking protein LI 1 could be crystallized isomorphously which might serve as a low resolution deficiency derivative. 

Fm-thermore, there is a good correlation between recovery of activity and ability to crystallize. Thus, particles lacking protein BL12, which are inactive biologically, could not be crystallized, whereas the reconstituted particles produce crystals isomorphous with the native form. 

In terms of copolymerization, the addition of a comonomer to a crystalline polymer usually causes a marked loss in crystallinity, unless the second monomer crystallizes isomorphously with the first. Crystallinity typically decreases very rapidly, accompanied by reductions in stiffness, hardness, and softening point, as relatively small amounts (10-20 mol%) of the second monomer are added. In many cases, a rigid, fiber-forming polymer is converted to a highly elastic, rubbery product by such minor... 

CRYSTAL (Isomorphous). One of two or more crystals which are similar in crystalline form and in chemical properties and are related in chemical composition in that one or more of the atoms and radicals in one are of similar chemical lype to the corresponding aioms or radicals in the other. Usually, one or more of their other atoms or radicals are identical. 

Cobalt Arsenates.—The ortho-arsenate, Co3(As04)2.8IT20, occurs in nature as erythrite or cobalt bloom in the form of monoclinic crystals isomorphous with vivianite, Fes(P04)2.8lI20, and perhaps with nickel ochre, Ni3(As04)z.8H20. Its crystallographic elements are ... 

Upon evaporation the salt may be obtained in yellow, anhydrous crystals isomorphous with potassium ferrieyanide.1 Density 1-906. 

Ammonium Osmyl Chloride,(NH4)20s02. Cl4,obtained1 by the action of hydrochloric acid upon ammonium osmyl oxy-nitrite, yields red crystals isomorphous with the corresponding potassium salt, than which, however, they are rather less soluble in water. 

The salt yields orthorhombic crystals isomorphous with the corresponding nitrosochlor-ruthenate (see p. 150). It is very stable for a compound of osmium. Its aqueous solution is quite stable, and even nitric acid does not attack the salt as vigorously as usual. 

The monohydrate, K3IrCl6.H20, was prepared by Duff our 2 by the action of hydrochloric acid upon the double oxalates of iridium and potassium at boiling temperature. It yields greenish brown orthorhombic crystals, isomorphous with its rhodium analogue, K3EhClg. H20. 

Lithium permanganate, LiMn04.—The trihydrate, LiMn04,3H20, forms dark-violet crystals, isomorphous with the perchlorate.4 The manganate has not been isolated. 

Rubidium periodate, RbI04.—When a mixture of rubidium iodate and hydroxide in hot concentrated solution is oxidized with chlorine, the periodate is formed in colourless quadratic crystals isomorphous with those of potassium periodate, and with the density 3-918 at 16° C. At 13° C. its solubility is 0-65 gram in 100 grams of water.18... 

Rubidium sulphate, Rb2S04.—The sulphate forms rhombic crystals isomorphous 2 with those of potassium sulphate, melting3 at 1074° C., the density at 20° C. being 3-6113, and at 60° C. 3-5943.4 It exists in two modifications,5 the transition-point being 657° C. The heat of formation from the elements is 344-68 Cal., and the heat of solution —6-66 Cal. at 15° C.6 The solubility 7 is given in the appended table ... 

In presence of sulphurous acid a similar reaction takes place. The trithionate forms rhombic crystals isomorphous with those of the corresponding potassium salt, the density being 2-845.4... 

Caesium iodate, CsI03.—The iodate is precipitated by the action of chlorine on a hot concentrated solution of caesium iodide and hydroxide.6 It yields monoclinic crystals, isomorphous with the corresponding salts of rubidium and potassium, and of density 4-831 at 16° C. At 24° C. its solubility is 2-6 grams in 100 grams of water.7... 

Ammonium periodate, NH4I04.—Neutralization of periodic acid with ammonia yields the periodate in tetragonal crystals isomorphous with the corresponding potassium, sodium, and rubidium salts,13 and also with the periodates of silver and lithium.14 Its density at 18° C. is 3-056 and its solubility at 16° C. i i of water.15... 

The hexagonal (Pbjmc = Qv or P62c = or P63/mmc crystallizes isomorphous with the mineral burbankite. 

Silver chromate is almost insoluble in water, glacial acetic acid, and in solutions of potassium chromate, but soluble in those of ammonia, caustic alkalies, nitrates, and in dilute acetic acid. A concentrated solution of ammonium nitrate is a good crystallising medium for silver chromate. With chlorine, above 200° C., silver chloride, chromium trioxide, and oxygen are produced. The solution in ammonia contains the compound Ag2Cr04.4NH3, which forms crystals isomorphous with the corresponding ammoniacal sulphate. ... 

Chromous Sulphate, CrSOi.VHgO, is produced by dissohdng chromous acetate in dilute sulphuric acid, or by interaction of chromium and sulphuric acid. It forms blue crystals, isomorphous with those of FeSO. THjO, and is soluble in water, though not in alcohol. It is readily oxidised by the oxygen of the air. Moissan describes a hydrate, CrSO. HgO, as a white powder, which with water regenerates the hepta-hydrate. ... 

The liquid mixtures rich in silver nitrate (X near to 0) furnish mixed crystals, which are hexagonal crystals, isomorphous with those which are furnished by fused silver nitrate at its freezing-point. 

MIXED CRYSTALS. ISOMORPHOUS MIXTURES. 281 and of a, crystals, having the formula... 

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