Showing papers by "Imperial Chemical Industries published in 1962"

Sequential Application of Simplex Designs in Optimisation and Evolutionary Operation

Abstract: A technique for empirical optimisation is presented in which a sequence of experimental designs each in the form of a regular or irregular simplex is used, each simplex having all vertices but one in common with the preceding simplex, and being completed by one new point. Reasons for the choice of design are outlined, and a formal procedure given. The performance of the technique in the presence and absence of error is studied and it is shown (a) that in the presence of error the rate of advance is inversely proportional to the error standard deviation, so that replication of observations is not beneficial, and (b) that the “efficiency” of the technique appears to increase in direct proportion to the number of factors investigated. It is also noted that, since the direction of movement from each simplex is dependent solely on the ranking of the observations, the technique may be used even in circumstances when a response cannot be quantitatively assessed. Attention is drawn to the ease with which second-o...

Note on a Method for Calculating Corrected Sums of Squares and Products

Abstract: (1962). Note on a Method for Calculating Corrected Sums of Squares and Products. Technometrics: Vol. 4, No. 3, pp. 419-420.

The solubility of oxygen in transition metal alloys

Abstract: The solubility of oxygen in niobium and solid-solution alloys of mobium with other transition metals of Groups IVA, VIA, VIIA, and VIIIA was measured. The solubility of oxygen in niobium over the temperature range 700 -1550 deg C obeys the relation: -log/sub e/N = 8600/RT + 0.516 where N is the atomic fraction of oxygen in solution. Additions of molybdenum, rhenium, and ruthenium to niobium all reduce oxygen solubility, zero solubility being reached when the electron/atom ratio of the alloy is about 5.75. Additions of titanium increase the oxygen solubility, but zirconium, which forms a very stable oxide ZrO/sub 2/, reduces oxygen solubility markedly. It is concluded that the solubility of oxygen in transition metal alloys is largely electronic in nature, solubility being small if the electron/atom ratio of the alloy exceeds 5.75, and being very much larger in alloys of a lower electron/atom ratio, the oxygen dissolving with a positive charge. (auth)

On the Mechanism of the Thermal Transformations in Solid Ammonium Nitrate

Abstract: The thermal transformations which take place in solid ammonium nitrate have been studied with the following techniques: differential thermal analysis, measurement of d.c. electrical conductance, optical microscopy, X-ray diffraction and nuclear magnetic resonance. It has been found that in dry ammonium nitrate, transformations between forms V, IV, II and I only take place and that the transformations appear to be of the order-disorder type. The transformations IV ⇌ III only take place in the presence of moisture and the mechanism appears to be one of dissolution and recrystallization.

Sprout development and subsequent plant growth

Abstract: During storage sprout growth was linearly related to the amount of available tuber substrate. Plants grown in nutrient solution were also highly dependent on the reserves of the parent tuber until a relatively late stage of development. Light intensity and daylength only slightly influenced sprout growth: temperature and variety were of considerable importance. Increase in sprout size at the time of planting caused earlier emergence and tuber initiation but the relative rate of plant growth was reduced. The principal weather factors which modified tuber initiation and growth were temperature and radiation: daylength was relatively unimportant. The different optimum temperatures during development suggest a technique for obtaining higher tuber yields.

Some Chemical Reactions of Sulphur Hexafluoride

Abstract: SULPHUR hexafluoride has customarily been considered to be chemically inert. It is unaffected by aqueous or fused alkali, ammonia or oxygen. The earliest report1 states that sulphur hexafluoride is reductively degraded by sulphur and selenium, vapours, and hydrogen sulphide at elevated temperatures, but these reactions have never been reinvestigated. The only substantiated chemical reaction of sulphur hexafluoride is that with a hot alkali metal, reaction with a film of sodium commencing at 200° 2. The great stability of sulphur hexafluoride is kinetic rather than thermodynamic in origin since it is thermodynamically unstable with respect to water3. The inability of nucleophilic reagents to attack the sulphur hexafluoride molecule can be ascribed to their failure to form an SN2 type transition state because the sulphur atom has no orbital of sufficiently low energy to permit its coordination with the unshared electron pair of the entering nucleophile. Attack by a nucleophilic reagent on a fluorine atom of sulphur hexafluoride is improbable for the same reason. However, there still remains the possibility of reaction with an electrophilic reagent, for example, a strong Lewis acid, the transition state of which is formed by co-ordination of the reagent with a fluorine atom using one of its lone electron pairs. This possibility does not appear to have been investigated until now.

Olefin, Acetylene, and π-Allylic Complexes of Transition Metals

Abstract: Publisher Summary The ability of olefins and acetylenes to function as ligands towards transition metals has aroused considerable interest in the last ten years from both the theoretical and practical viewpoints. Elucidation of the nature of the bonding between the unsaturated hydrocarbon and the metal atom has made an important contribution to the modern concept of valency, and has led to a better understanding of the role metallic catalysts play in chemical reactions. This review deals with metal-hydrocarbon complexes under the following headings: (1) the nature of the metal-olefin and -acetylene bond; (2) olefin complexes; (3) acetylene complexes; (4) n-allylic complexes; and ( 5 ) complexes in which the ligand is not the original olefin or acetylene, but molecule produced from it during complex formation. n-Cyclopmtadienyl complexes, formed by the reaction of cyclopentadiene or its derivatives with metal salts or carbonyls are not discussed in this review, neither arc complexes derived from aromatic systems, e.g., benzene, the cyclopentadienyl anion, and the cycloheptatrienyl cation and from acetylides, which have been reviewed elsewhere.

Unpaired Electron in Nitroso-bis(dimethyldithiocarbamato)iron(II)

Abstract: WE have examined the electron spin resonance spectrum of [Fe(NO){S2CN(CH3)2}2] to investigate how the unpaired electron, which is in an anti-bonding orbital in free nitric oxide, distributes itself in a metal complex. The magnetic moment of a powdered sample at room temperature is 2.24 B.M., which shows the complex to have one unpaired electron with an appreciable orbital magnetic moment. The electron spin resonance spectrum of a benzene solution consists of three equally intense lines with a separation of 0.0011 cm−1. This triplet structure arises from an interaction between the unpaired electron and the nitrosyl nitrogen atom and indicates that the unpaired electron is in an orbital which embraces the nitrosyl group. This interaction is greater than that in free nitric oxide1 in which the splitting is 0.00099 cm−1.

The Measurement of Molecular Orientation in Polyethylene Terephthalate Filaments by X-Ray Diffraction

Abstract: An x-ray method has been developed to measure the over-all crystalline orientation in polyethylene terephthalate fibers. Coupled with optical birefringence studies which measure total orientation, it allows an estimate to be made of the noncrystalline orienta tion. It has been shown, for yarns drawn under the same conditions as these fibers. that it is the noncrystalline orientation which changes with draw ratio, the crystalline orientation remaining approximately constant with draw ratio and heat treatment.The results are also discussed in rotation to the theories on strain-induced crystalli zation in drawn polyethylene terephthalate fibers.1 Palmer, R. P., I.C.I. (Plastics Division), unpublished work.2 Knapp, P. E., I.C.I. (Fibres Division) unpublished work.3 Howells, E. R., I.C.I. (Plastics Division), unpublished work.

The Mechanism of Dyeing with Procion Dyes II—The Mechanism of Reaction with Water and Soluble Alcohols or Carbohydrates

Abstract: The rates of reaction of a series of dichloro-s-triazine dyes with water have been measured. The rate constants obtained at constant pH are pseudo-unimolecular. When the true second-order constants are calculated, allowing for the pH, it is found that the results are best interpreted on the basis that the dye reacts with ionised hydroxyl groups. Similarly, the reaction of a monochloro-s-triazine dye with mannitol or methanol is best explained in terms of a mechanism involving the dye and the ionised hydroxyl group of the alcohol.

Screw Extrusion of Plastics

Abstract: The main object of the work reported here was to find a rational design method for granule-fed single-screw extruders used for plastics processing.The first half of the paper contains a brief revie...

Leaf-clearing technique to assist fungal spore germination counts.

Abstract: FOR comparisons between formulations of certain fungicides, it was necessary to estimate the percentage germination of Alternaria solani and Venturia inaequalis spores inoculated on to sprayed tomato and apple leaves. Direct microscopic examination was generally difficult owing to the opacity of the leaf. When the leaves were cleared by immersion in solvents such as pyridine1 or dioxan and propionic acid2, the results were misleading because many of the spores were washed off. Pressing leaves on to gelatin or cellulose acetate3 on slides and removing them proved time consuming, and often failed to remove all of the spores. Moreover, debris and the impression of the leaf surface made it difficult to decide whether many of the spores had germinated. Stripping of a cellulose acetate film4,5 from the leaves and dissolving it in acetone on a slide was an improvement, but nevertheless tedious. As direct examination of the spores in situ would be the most rapid method of estimating the percentage germination, a technique was developed which allows accurate and rapid sporecounts on large numbers of leaves.