Crystallinity early investigations

Early investigations indicated the presence of an alkaloid in G. fremontii and G. racemosa. Six species were examined recently by Oneto, who found no alkaloid in G. jiavescens, amorphous bases in G. fremontii and G. buxifolia, and alkaloids yielding crystalline hydrochlorides in G. elliptica, G. wrightii and G. veatchii. The bark of the last-mentioned species was worked up for total alkaloids, which on fractionation yielded two crystalline bases. 

The hydrolysis of C-curarine to C-fluorocurarine (Vol. VIII, p. 569) with concentrated hydrochloric acid produces smaller amounts of two other compounds, ultracurine A and ultracurine B, notable for their very intense blue fluorescence in UV-light. The early investigations (16) led to the isolation of both of these degradation products as crystalline j8-anthraquinonesulfonates and the empirical formula C40H44N4++ or C44H44N4O++ was tentatively proposed for ultracurine A analyses of... 

Early investigators showed that superficially purified cholesterol and activatable foods contained a provitamin, or precursor, which was converted into the vitamin on irradiation. Ultimately, two vitamin D precursors were identified. Provitamin D2 was found to be ergosterol (la). WiNDHAUS 194) and Askew (6) independently isolated pure crystalline vitamin D2 (2 a) via its 3,5-dinitrobenzoate from the complex and unstable irradiation products of ergosterol. Provitamin D3 was more difficult to identify, but it was found by Windhaus 195) to be 7-dehydro-cholesterol (lb). On irradiation crystalline vitamin D3 (2b) was obtained, which was identical with that isolated from tuna-liver oil by Brock-MANN 29). Vitamins D4 and D5 have been found in nature, each one differing from the other and the ones mentioned above in the constitution of the side chain. 

Detailed measurements of the extensional modulus of monofilaments have been made by longitudinal wave-propagation methods, where the relationship of the extensional modulus to molecular orientation and crystallinity has been examined. Early investigations using this technique were made by Hillier and Kolsky [24], Ballou and Smith [25], Nolle [26] and Hamburger [27]. 

The dominating S2-layer contains the cellulose micro fibrils orientated under an acute angle toward the fiber axis. Such orientation of the microfibrils imparts to natural cellulose fibers increased mechanical properties. The microfibrils of the cell wall consist of elementary nanofibrils, and each such fibril is built of ordered nanocrystallites and low ordered non-crystalline (amorphous] domains statistically alternated along the fibril. The early investigations supposed the presence in various cellulose samples of elementary nanofibrils having a constant lateral size of 3.5 nm (Manley, 1964 Muhlenthaler, 1969]. However, recent... 

Variable temperature study with a subsequent line shape analysis enables a clear insight of the temperature-dependent dynamics of the system, where the glass transition temperature (Tg) of the amorphous phase, melting point or a crystallization onset of a present crystalline phase, or any other changes caused by altered dynamics of the involved species can be assessed. This was recognized by early investigations of polymer electrolytes and will be discussed in greater detail later. 

One class of large molecules that was investigated relatively early was liquid crystals [37, 38], and in particular the group 4-n-alkyl-4 -cyanbiphenyl (mCB). These molecules fonu a highly crystalline surface adlayer, and STM images clearly show the characteristic shape of the molecule (figure B 1.19.8). 

In Parenteral and Enteral Nutrition. Amino acid transfusion has been widely used since early times to maintain basic nitrogen metaboHsm when proteinaceous food caimot be eaten. It was very difficult to prepare a pyrogen-free transfusion from protein hydrolysates. Since the advances in L-amino acid production, the crystalline L-amino acids have been used and the problem of pyrogen in transfusion has been solved. The formulation of amino acid transfusion has been extensively investigated, and a solution or mixture in which the ratio between essential and nonessential amino acid is 1 1, has been widespread clinically. Special amino acid mixtures (eg, branched chain amino acids-enriched solution) have been developed for the treatment of several diseases (93). 

In spite of the slow development of crystal structure analysis, once it did take olT it involved a huge number of investigators tens of thousands of crystal structures were determined, and as experimental and interpretational techniques became more sophisticated, the technique was extended to extremely complex biological molecules. The most notable early achievement was the structure analysis, in 1949, of crystalline penicillin by Dorothy Crowfoot-Hodgkin and Charles Bunn this analysis achieved something that traditional chemical examination had not been able to do. By this time, the crystal structure, and crystal chemistry, of a huge variety of inorganic compounds had been established, and that was most certainly a prerequisite for the creation of modern materials science. 

Aconitine, C34H47O11N. After early indications of the presence of alkaloids in A. Napellus L. by Geiger and Hesse, and by von Planta, crystalline aconitine was probably first prepared in 1860 by Groves. The alkaloid was investigated by Wright et al., and later on by Dunstan et al. and by Freund and co-workers. ... 

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