Showing papers by "Imperial Chemical Industries published in 1971"

A Bayesian Approach to Short-term Forecasting

Abstract: A new approach to short-term forecasting is described, based on Bayesian principles. The performance of conventional systems is often upset by the occurrence of changes in trend and slope, or transients. In this approach events of this nature are modelled explicitly, and successive data points are used to calculate the posterior probabilities of such events at each instant of time. The system produces not only single-figure forecasts but distributions of trend and slope values which are relevant to subsequent decisions based on forecasts.

Factorial Designs, the |X′X| Criterion, and Some Related Matters

Abstract: Two of the basic approaches to choosing an n-point experimental design in many industrial situations are (i) to set down a simple factorial or fractional factorial design in the factors being studied, or (ii) to choose a design based on the well-known |X′X| criterion. Experimenters often prefer (i) due to its simplicity; our viewpoint here is that (ii) is much better. We first indicate some situations for which (when all the factors are restricted to a cuboidal region) the factorial approach is optimal, as judged by the |X′X| criterion, but the assumed models are often not sensible ones in practical work. We then examine what (similarly restricted) designs are optimal under the |X′X| criterion for the standard linear models of first and second order; because of the very rapid increase in computational difficulties, we consider only “cube plus star” type designs for k ≥ 3 (except for k = 3, n = 10). In spite of computational requirements, we recommend use of the |X′X| criterion in general rather than the i...

Pharmacology of 4-hydroxypropranolol, a metabolite of propranolol

Abstract: 1. 4-Hydroxypropranolol, a metabolite produced after oral administration of propranolol, has been shown to be a β-adrenoceptor blocking drug. It is of similar potency to propranolol in antagonizing the effects of isoprenaline on heart rate and blood pressure in cats and against isoprenaline protection of guinea-pigs from bronchospasm. It is not cardioselective. 2. In rats depleted of catecholamine 4-hydroxypropranolol produced an increase in heart rate, suggesting that it has intrinsic sympathomimetic activity. 3. In anaesthetized dogs 4-hydroxypropranolol produced a decrease in heart rate and dP/dt and an increase in A-V conduction time at doses within the range 0·09-1·25 mg/kg. These effects are a result of β-adrenoceptor blockade. In dogs depleted of catecholamines these same doses produced an increase in heart rate and dP/dt and a decrease in A-V conduction time. These responses were antagonized by propranolol, and were due to the intrinsic sympathomimetic activity of the compound. At higher doses (5·25 and 13·25 mg/kg) a further dose dependent decrease in heart rate and dP/dt and an increase in A-V conduction time occurred. This trend was also seen in animals depleted of catecholamines. These changes represent membrane stabilizing activity of 4-hydroxypropranolol. 4. 4-Hydroxypropranolol is a potent β-adrenoceptor blocking drug with both intrinsic sympathomimetic activity and membrane stabilizing activity.

The rheology of filled polymers

Abstract: The flow properties of polymer melts containing fillers of various shapes and sizes have been examined. If there is no failure of either the filler or polymer in the solid state, then the modulus enhancement for randomly distributed filler is equal to the melt viscosity enhancement under medium shear stress conditions (104 Nm−2) in simple shear flow or in oscillatory shear flow. Submicron-size fillers, in particular, can form weak structures in the melt that greatly increase the low shear rate viscosity without changing the modulus of the solid proportionately. The highly pseudo-plastic nature of polymer melts at shear stresses of 106 Nm−2 means that, even without orientation of filler particles toward the flow direction, the viscosity enhancement is less than at lower shear stresses.

Modulus of short carbon and glass fiber reinforced composites

Abstract: A theoretical model for a short fiber reinforced composite is proposed The composite is assumed to consist of an aggregate of sub-units, each sub-unit possessing the elastic properties of a reinforced composite in which the fibers are continuous and fully aligned The elastic constants of a partially oriented composite are then calculated by the Voigt and Reuss averaging procedures, giving upper and lower bounds respectively for the composite modulus Comparison is made with experimental data for such composites The measured modulus of glass and carbon fiber composites is found to be given by the Reuss or lower bound, to a good approximation compared with the difference between the bounds, for fiber orientations ranging from almost isotropic to highly aligned

‘Doubly charged ion’ mass spectra of some simple aromatic compounds

Abstract: Benzene, toluene, phenol, diphenyl ether and the three isomeric dihydroxy-benzenes have been examined using an MS-9 mass spectrometer under conditions that allowed only ions having twice the normal amount of kinetic energy to be detected. These ions are, in fact, singly charged ions arising from charge exchange reactions of doubly charged ions of the same mass, occuring in the first field free region of the Spectrometer. It is argued that the spectra obtained yield essentially the distribution of doubly charged ions in the source region. These ‘doubly charged ion’ mass spectra are compared with the normal singly charged ion spectra of the compounds and the implications of the significant differences that are found, are discussed.

Some neurochemical effects of amphetamine, methylamphetamine and p-bromomethylamphetamine in the rat.

Abstract: 1. Low doses of D-amphetamine increased brain noradrenaline concentrations in the rat; doses greater than 5 mg/kg, however, caused a decrease. Methylamphetamine also showed this dual effect, but a reduction in brain noradrenaline concentration only occurred when doses greater than 10 mg/kg were administered. p-Bromomethylamphetamine did not significantly reduce brain noradrenaline concentrations even at a dose of 60 mg/kg. The order of potency in reducing the concentration of noradrenaline correlated with the central stimulant effects; D-amphetamine produced the greatest and p-bromomethylamphetamine the least increase in motor activity.2. D-Amphetamine and D-methylamphetamine potentiated the action of 4,alpha-dimethyl-m-tyramine (H77/77) in depleting brain noradrenaline; the greatest potentiation was produced by D-amphetamine. This suggests that the phenylethylamines may affect brain noradrenaline concentrations by acting on the reserpine resistant uptake mechanism.3. Differences were found in the effect of the three drugs on brain dopamine concentrations; D-amphetamine caused a decrease while p-bromomethylamphetamine caused an increase. Methylamphetamine had no effect on the concentration of dopamine. Only p-bromomethylamphetamine significantly reduced the depletion of brain dopamine concentrations caused by H77/77.4. Methylamphetamine and p-bromomethylamphetamine reduced the concentration of 5-hydroxytryptamine (5-HT) in the brain; administration of the same dose of D-amphetamine did not change the concentration of 5-HT.5. Changes in the blood and brain concentrations of tyrosine and tryptophan, and in the concentration of gamma-amino-n-butyric acid in the brain could not be correlated with the changes observed in the concentrations of biogenic amines in the brain.

Experimental allergic myositis in rats.

Abstract: Experimental allergic myositis (EAM) closely resembling human polymyositis was produced in rats by a single injection into two inguinal lymph nodes with either homogenates or purified subcellular fractions of homologous muscle in Freund's complete adjuvant. EAM is not necessarily accompanied by clinically evident arthritis and is manifest by elevated serum enzymes, and widespread but focal necrosis and phagocytosis of muscle fibers. EAM was transferred to normal animals of the same strain by infusion of washed lymphocytes from affected animals.

Textured core yarns

Abstract: False twist textured yarns are described which are composed of a plurality of continuous filaments forming a false twist textured core portion and a plurality of wrapper false twist textured continuous filaments, said wrapper filaments being of a higher bulk than the core filaments, said filaments periodically wrapping around the core filaments and forming reversing helices at intervals along the yarn.

An experimental design criterion for precise estimation of a subset of the parameters in a nonlinear model

Abstract: SUMMARY Ani experimental design criterion for obtaining precise estimates of a subset of the para

An investigation of mechanisms of synergistic interactions in PVC stabilization

Abstract: Synergism in poly(vinyl chloride) stabilization has been studied by measuring rates of hydrogen chloride evolution from samples of polymer in the presence of stabilizers in di-(2-ethylhexyl) phthalate solution in an inert atmosphere Barium, cadmium, calcium, and zinc laurates, when used alone, allow escape of hydrogen chloride well before stoichiometric uptake is achieved, whereas synergistic mixtures of calcium–zinc and barium–cadmium laurates absorb almost the theoretical quantity of hydrogen chloride Cadmium and zinc laurates replace labile chlorine atoms in the polymer backbone by ester groups, reducing formation of long polyene sequences: barium and calcium laurates delay the formation of cadmium and zinc chlorides, apparently by reconverting them into their respective laurates Polyols function by forming complexes with the prodegradant cadmium and zinc chlorides, but contrary to popular belief phosphites possess little activity in this respect Instead, they slow down the rate of polymer degradation by removal of labile chlorine atoms, by reaction with hydrogen chloride, and by peroxide decomposition

A new column system for isothermal gas chromatographic analysis of light gases (H 2 , O 2 , N 2 , CO, CH 4 , CO 2 , C 2 H 4 , C 2 H 6 and C 2 H 2 ) employing a column switch technique

Abstract: A new column system for the isothermal analysis of H2, O2, N2, CO, CH4, CO2, C2H4, C2H6 and C2H2 is described. Higher hydrocarbons and water are backflushed from the system. The use of 13X molecular sieve in a relatively deactivated state shortens the elution times of the light components and improves peak shapes. Both factors enable quantitative analyses to be carried out satisfactorily at lower concentrations than would otherwise be possible. Analysis of all compounds listed can be carried out in eleven minutes. Sparingly activated 13X molecular sieve columns have proved to be very stable and rarely require reactivation. The method of column switching employed avoids the use of mechanical valves in the sample path and is suitable for automatic operation.

Studies on the Mode of Action of the Coccidiostat Robenidene

Abstract: Robenidene has appreciable anticoccidial activity against Eimeria brunetti and E. tenella in chickens. In the case of E. tenella under continuous drug medication, this activity has been shown to be primarily coccidiostatic at the stage of the almost mature first generation schizont. The stage at which the drug acts was predicted from the mortality pattern in experiments involving restricted administration of drug and confirmed by histological examination of caeca from treated birds and by observation of parasites in tissue culture.

Inhibition of contact sensitivity in the mouse by topical application of corticosteroids.

Abstract: 1. Topical application of oxazolone to the ears of mice previously sensitized to this hapten resulted in a marked increase in ear weight 24 h later.2. Topical application of hydrocortisone, betamethasone 17-valerate, fluocinolone acetonide or triamcinolone acetonide inhibited this response in a dose dependent manner.3. The free alcohols of the three fluorinated compounds were only weakly active.4. Activity in this model was truly local. Oral administration of hydrocortisone or fluocinolone acetonide at doses comparable to those used topically failed to inhibit the ear swelling.5. Some steroids with poor anti-inflammatory properties had no significant effect.

Fungicidal composition and method containing 2-amino-pyrimidines

Abstract: Fungicidal pyrimidine derivatives and the use thereof in combatting plant diseases. Representative derivatives are 2-dimethylamino-4-methyl-5-n-pentyl-6-hydroxypyrimidine and 2-dimethylamino-4-methyl-5-n-propyl-6-hydroxypyrimidine.

The chemistry of azo dyes

Abstract: Azo dyes are characterised by presence in the molecule of one or more azo groups —N = N—, which form bridges between organic residues, of which at least one is usually an aromatic nucleus. Many methods are available for preparing azo compounds, but manufacture of azo dyes is always based on the coupling of diazonium compounds with phenols, naphthols, arylamines, pyrazolones or other suitable components to give hydroxyazo or aminoazo compounds or their tautomeric equivalents. In the resulting dyes the azo group is the chromophore and the hydroxyl or amino group is an auxochrome.

The metabolism of methoxyethylmercury salts

Abstract: The metabolism of methoxy[14C]ethylmercury chloride in the rat has been investigated. After a single subcutaneous dose a small proportion is excreted unchanged in urine and a larger amount in bile with some resorption from the gut. The greater part of the dose is rapidly broken down in the tissues with a half-time of about 1 day to yield ethylene and inorganic mercury. Ethylene is exhaled in the breath and the mercury migrates to the kidney and is excreted in urine. A small proportion of the dose appears as carbon dioxide in the breath and about 12% in urine as a mercury-free metabolite. It is possible that the breakdown of methoxyethylmercurychloride to ethylene and inorganic mercury is not catalysed by an enzyme system.

Method of producing a photographic film base having a subbing layer

Abstract: Coating of biaxially oriented polyester films with a subbing composition including a polymeric and a water-permeable component such as gelatin before the film is fully oriented

R factor with a mutation in the tetracycline resistance marker.

Abstract: THERE is evidence that resistance to tetracyclines (TCR) in Gram-negative bacteria that is mediated by R factors involves an inducible mechanism. Thus two levels of resistance to tetracyclines have been demonstrated in various strains of Escherichia coli harbouring R factors1,2. R factor bearing cells cultured in the absence of tetracycline are about 50% resistant when challenged with 50 µg of tetracycline/ml., as can be seen from the effect of the drug on the level of protein synthesis in the cells2. Cells cultured in the presence of a sub-inhibitory concentration of tetracycline, however, are not significantly inhibited by a subsequent challenge with 50 µg of tetracycline/ml.; the 50% level of inhibition is only reached at concentrations in excess of 150 µg/ml. This adaptation, which is apparently associated with a decrease in the absorption of tetracycline by the cells, can be suppressed with inhibitors of protein and RNA synthesis2. The tetracycline resistance mechanism thus resembles an inducible system although the end products of the resistance gene(s) have not yet been identified.