Fractions, chemical properties isolated

In 1899 Thoms isolated an alcohol from Peru balsam oil, which he termed peruviol. This body was stated to have powerful antiseptic properties, but has not been further investigated until Schimmel Co. took up the subject. The oil after saponification was fractionated, and after benzyl alcohol had distilled over, a light oil with characteristic balsamic odour passed over. It boiled at 125° to 127° at 4 mm., and had a specific gravity 0 8987, optical rotation -1- 12° 22, and refractive index 1-48982. This body appeared to be identical with Hesse s nerolidol, whilst in physical and chemical properties it closely resembles peruviol. The characters of the various preparations were as follows —... 

Tungsten-based catalysts with a Lewis base promoter are used in the polymerization of dicyclopentadiene also isolated from the C5 stream-cracker fraction.150,155 The product poly(dicyclopentadiene) or Metton resin has unusual physical and chemical properties. It is processed together with elastomers to increase viscosity of the end product by using reaction injection molding (RIM) technology.155... 

Petroleum can be fractionated into four generic types of materials representing general chemical properties. These include saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes. The standard ASTM separation procedure (D2007) for isolating the asphaltenes and the other components in petroleum is based on solubility behavior and chromatography, as shown in Fig. 5. Commerically, many refineries utilize solvent separations to produce a solvent deasphalted oil which has lower impurity levels. 

What is known for certain is that WSOM components constitute a substantial fraction of OAs. To date, only a small number of aerosol WSOM samples have been studied and characterized, and most of them were collected in European locations. Besides, each collected sample was extracted and isolated by different procedures, which hinders the comparison of the fine physical and chemical properties of the isolated organic fractions. The establishment of a standardized analytical methodology for WSOM extraction and isolation seems to be an important prerequisite for efficient further characterization of aerosol WSOM samples from different areas with different degrees of pollution (urban versus rural versus remote areas in different regions of the world). 

The information given above concerning the chemical and physico-chemical properties of the inorganic polyphosphates will assist in the better understanding and prediction of the behaviour of these compounds during their extraction from cells and their subsequent fractionation. Knowledge of these properties will facilitate the development and use of efficient and reliable biochemical procedures for the isolation, purification, identification and determination of polyphosphates. 

Phase coexistence in lipid bilayers may be an important physical property for membranes of cells. When two phases coexist in a bilayer, depending upon the relative mass fractions of the phases and the shapes of their domains, one of the phases is percolative (physically continuous) and the other is nonpercola-tive (physically discontinuous or dispersed as isolated domains). Changes in the physico-chemical properties of the membrane (lateral pressure, temperature, and chemical composition are the most relevant for biological membranes) result in interconversion between the two phases—one phase grows at the expense of the other. In phase-separated systems of this type, a critical mass ratio of phases called the percolation threshold, at which the previously continuous phase becomes discontinuous and the previously discontinuous phase becomes continuous, becomes... 

It is now very well estabhshed that DOM is the major source of trihalomethanes and other disinfection by-products in disinfected water. In fact, the measurement of THMFP is now a routine monitoring task in the water treatment industry, and suppliers in the US are required to advise consumers of the concentrations of trihalomethanes and other disinfection by-products in drinking water. Efforts to remove DOM from waters before they are chlorinated have driven much of the research that has led to advances in membrane-based methods of isolation of DOM from water (see the discussion of UF, NF, etc., in Section 5.10.4.2.2). Nikolaou and Lekkas (2001) have recently reviewed many aspects of the reactions of DOM with chlorine and other disinfectants. They review the relationships between reactivity of DOM (i.e., formation of disinfection by-products) and the chemical properties of DOM and several types of fractions of DOM. They also discuss the formation and potentially adverse effects of several classes of disinfection by-products. Urbansky and Magnuson (2002) have reviewed the subject of disinfection by-products, including a brief discussion of DOM. Both of these reviews are recommended for further up-to-date details on the role of DOM in the formation of disinfection by-products. 

Standard procedures were followed for isolation of the toxic principles from mycelium of FA 120. A methylene chloride extract of the freeze-dried hyphae was initially partitioned between hexane and aqueous methanol to separate lipids from more polar material. Bio-assay-monitored chromatographic fractionation of the hexane-soluble material led to the isolation of a fraction (ca. 5% of the hyphal weight) which could account for much of the toxicity of the hyphae of FA 120 to spruce budworm larvae. The spectroscopic and chemical properties of this material were characteristic of the enniatins, a group of cyclic hexadepsipeptide ionophore antibiotics produced by several plant pathogenic Fusarium species, including F. lateritium... 

Figure 2. Chemical properties of all the fractions isolated. The carbon aromaticity (fa) is obtained from NMR. The extent of saturated hydrogens (h8, h8 = 1 — ha) is obtained from IR.

It is a relatively recent observation that Colchicum species contain numerous chemical constituents of diverse chemical properties. Recognition of this fact has led to more efficient methods of isolation. In addition to neutral, phenolic, and basic alkaloids, 0. autumnale contains fatlike substances which are removed by a preliminary ligroin extraction of the pulverized, dry material. From such an extraction of the flowers of C. autumnale, Santavy and Herout (293) have isolated a paraffin, Ca7-28H5g 58, m.p. 58-60° an alcohol, CaaH450H, m.p. 66-67° and a phytosterol, m.p. 139-140°. Benzoic, salicylic, and 2-hydroxy-6-methoxybenzoic acids may be separated from the alkaloid mixture by virtue of their solubility in ether and aqueous base (294). The alkaloids themselves may be separated into neutral, phenolic, or basic fractions by standard extraction techniques. Pure alkaloids may be obtained from each fraction by fractional crystallization and chromatography on... 

With her husband. Professor Pierre Curie (1859-1906), she began to separate pitchblende into fractions and to determine their activity in discharging the electroscope. She isolated a fraction that was 400 times more active than uranium. This fraction consisted largely of bismuth sulfide. Since pure bismuth sulfide is not radioactive, she assumed that a new, strongly radioactive element, similar in chemical properties to bismuth, was present as a contaminant. This element, which she named polonium, was the first element discovered through its properties of radioactivity. In the same year, 1896, the Curies isolated another new radioactive element, which they named radium. 

In making studies of the possible participation of neurophysin in the mechanism of release, it should be recalled, that recent studies have indicated that the chemical properties of neurophysin may vary with the preparation technique (Dean et al. 1967). It seems that special precautions should be taken when isolating neurophysin, to obtain a product similar to the natural one. It may bevhowever, that studies of binding properties of neurophysin obtained by previous techniques have still yielded reasonable information, since nearly all of the fractions, produced by different preparation procedures, do bind hormones. There has been... 

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