Variations In Sulfur Content Research Articles

The Influence of Sulphur-Containing Amino Acids on the Biosynthesis of High-Sulphur Wool Proteins

The sulphur content of wool can vary within the range of about 2·7-4·2% depending on the diet of the sheep. The lower limit may represent a limiting fundamental structure for wool as it has not been possible to produce wool of sulphur content lower than 2·7% during sulphur-deprivation experiments. There is a highly significant linear relationship between the sulphur content of wool and its content of high-sulphur proteins. The major part of this variation in sulphur content is due to alterations in the extent of biosynthesis of proteins of extremely high sulphur content having about one-third of the amino acid residues presen1, as half cystine. The biosynthesis of these proteins may be under separate metabolic control for they can be produced at maximum rate under conditions where the synthesis of other highsulphur proteins is partly inhibited by a sulphur-deficient diet or by high levels of DL-methionine supplementation

Defect equilibria in cubic high temperature copper sulfide (digenite)

Within the homogeneity region of the cubic high temperature copper sulfide the variation of sulfur content with sulfur pressure was measured under isothermal conditions. From the results were deduced the equilibria involving atomic disorder. Probably the most important atomic imperfections giving rise to deviations from stoichiometry are the effectively neutral copper vacancy (generated by replacing two Cu + ions by one Cu 2+ ion), the effectively negatively charged copper vacancy (represented by one Cu + ion missing), and an association of these two imperfections. If high temperature Digenite is to be denoted by a chemical formula, then Cu 7S 4 is preferable to Cu 2S or Cu 9S 5.

High temperature equilibrium of atomic disorder in SnS

Within the homogeneity region of SnS the variation of sulphur pressure with variation of sulphur content has been measured at the equilibrium temperature by chemical means. The results, together with values already known are compared with some models of atomic disorder. From this discussion it follows that the doubly negatively charged tin vacancy is probably the prevailing imperfection in equilibrium.

High-sulphur Proteins as a Major Cause of Variation in Sulphur Content between α-Keratins

A COMMON feature of the wide variety of mammalian tissues classified as α-keratins is that they may be split into two separate protein fractions1–3 bearing a general resemblance to the ‘high-sulphur’ and ‘low-sulphur’ protein fractions first recognized in wool4,5. However, in these α-keratins which include hair, fur, wool, horn, nail, hoof, quill and baleen, the percentage of sulphur present varies greatly and covers the approximate range 2–6 per cent6–9 (Table 1). In general the horny keratins contain smaller amounts of sulphur than do the hairs and so the sulphur content of sheep horn, for example, is often lower than the sulphur content of wool from the same animal. It has been suggested7 that these differences in sulphur content can be used as a means of distinguishing keratins from one another, but in the case of wool it is now well established that there is a characteristic range of values of sulphur content (about 2.9–4.2 per cent) rather than a particular value for this keratin. A review of the relevant literature is given by Reis and Schinckel10,11. A sheep will produce wool with a high sulphur content during high levels of nutrition or during the abomasal infusion of sulphur-containing amino-acids; on the other hand, wool with a much lower sulphur content will be produced when the animal is on a copper-deficient or low-nutritional diet10–13. Moreover, these variations in the sulphur content of wool have been shown to originate primarily in the ‘high-sulphur’ proteins which change both in amount and in sulphur content1,14–16.

Crosslinking in keratins. III. Acid hydrolysis of keratins

The fraction soluble during hydrolysis in an HCOOH–HCl–H2O mixture was measured as a function of time for Lincoln wool, human hair, and kid mohair. Evaluation by crosslinking theory of the equivalent relative increase in sulfur content of the three insoluble residues shows the likely presence of two components in each with equal sulfur content although the less abundant component differs by having mainly intramolecular crosslinking. Overall variation in sulfur content entirely accounts for the variation in rate of hydrolysis among these α-keratins. The data of Leach, Rogers, and Filshie for the amino acid content of the insoluble residue following hydrolysis of wool in dilute HCl also depend in a simple way on the amount dissolved; in this case the disproportionation of amino acids between the residue and extract depends on the degree of their affiliation with the crosslink-containing cystine.

Variations in the sulphur content of wool from Merino sheep on two semi-arid grasslands

Seasonal variations in sulphur content and growth rate of wool were measured at intervals of 6 weeks over a period of 1 year on two groups, each of six Merino wethers, which grazed on two semi-arid grasslands. Each group consisted of three high-producers and three low-producers, selected on the basis of wool growth rate. There were substantial seasonal variations in sulphur content, which followed very closely the seasonal pattern of wool growth. Mean sulphur contents on the two grasslands ranged from 3.25 and 3.32% during December–April, to 3.67 and 3.79% respectively during July-October. Seasonal variations in sulphur content and growth rate of wool were related to the amount of edible forage available, and it was concluded that these seasonal variations were due mainly to variable nutrition. The range of sulphur contents was 2.93 to 3.92%, owing to seasonal nutritional variations and differences between sheep; annual mean sulphur contents of wool from individual sheep ranged from 3.22 to 3.84%. The annual mean sulphur content of the wool from high-producers (3.39%) was lower than that of wool from low-producers (3.66%). The seasonal variation in sulphur content also appeared to be greater in wool from high-producers than in wool from low-producers.

Relationship between sulfur in coals and the occurrence of marine roof beds

The hypothesis that regional variation of sulfur in coal beds is related to the influence of penecontemporaneous marine water is tested by stratigraphic and statistical methods. The Lower Kittanning coal exhibits regional variations in sulfur content which are statistically related to the regional changes in overburden, areas of marine overburden being higher in sulfur than continental areas. The Upper Freeport coal, overlain entirely by continental beds, shows no regional sulfur variation. The conclusion is made that the presence or absence of marine waters was one of the factors controlling regional variation of sulfur in coal.

Occurrence of Sulphur Waters in the Gulf Coast of Texas and Louisiana, and their Significance in Locating New Domes

Study of chemical analyses of ground waters in the coast region of Texas and Louisiana indicates that in waters from known salt domes there is a wide variation of sulphur content though higher concentration over the salt core is observed in some cases. Several small ground-water areas unrelated to known salt domes have been distinguished where abnormally high sulphur content is found. These sulphur waters appear to result from surface conditions rather than from buried domes.

Seasonal Variation of Sulphur Content in Certain Tissues of the Apple Tree

1. The sulphur content, as determined by the sodium peroxide method, is of the same order as the phosphorus content in the apple tree tissues investigated. 2. The highest percentages of sulphur are found in the leaves, and then in descending order in spurs, young bark, and old bark. 3. The sulphur content varies inversely with the phosphorus content throughout the year. 4. Sulphur resembles calcium in that it is not mobilized to any great extent. 5. The seasonal variation of sulphur is parallel with the H-ion concentration. 6. The percentage of sulphur is at a minimum in the apple spur at the time of fruit-bud differentiation.

Relation of Sulphur to Variation in the Gravity of California Petroleum

Published in Petroleum Transactions, AIME, Volume 57, 1917, pages 989–1009. Introduction One of the features of oil-field work that puzzles operator, chemist, and geologist alike, is variation in the gravity of the petroleum produced on neighboring leases or even from adjoining wells. Few fields in the United States yield oil that is of uniform gravity throughout; in some fields the different grades are produced from different sands, in a few from different formations, and in many from different areas in the same sand. In a few cases, perhaps, a common assumption that the heavier oil is derived from the lighter through the escape of the more volatile constituents is valid, but many cases can not be explained in this way. Although in the California fields the specific gravity of the oil generally decreases with depth, there are numerous exceptions to this rule; and, as in many other regions the light oil is found nearest the surface, it is evident that evaporation underground is generally an unimportant factor. It is generally recognized that the great differences between petroleum from widely separated fields are due largely to differences in age and degree of metamorphism and to variation in the composition of the original organic matter; but in the writer's opinion some of these broader differences, as well as most of the minor variations in the character of the oil from any one field, are due to the local action of natural reagents such as sulphur or oxygen. This is particularly likely to be true if the oil has migrated from one formation to another, as in the California fields; and in some arcas it appears that variation in sulphur content may even afford a rough index of the extent or distance of the migration. It is the purpose of this paper to call attention to the chemical action of sulphur and oxygen on petroleum, to show that the gravity of the oil from any one field is intimately related to its sulphur content, and to discuss the possibility that oil in its migration will encounter and take up sulphur or oxygen. Petroleum chemists have been occupied so largely in working out the complex constitution of petroleum and the processes of refining it, that we know little of the effect on petroleum of any of the substances with which it comes in contact underground. The study of petroleum from the geochemical standpoint has received slight attention except from a few chemists, and it is therefore impossible to trace in detail the natural changes that oil may undergo. Clifford Richardson however, pointed out many years ago the influence of sulphur in hardening asphalt. T.P. 057–48