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Showing papers by "Royal Holloway, University of London published in 1974"


Journal ArticleDOI
TL;DR: In this article, the chemical potential of hard-sphere fluids over the reduced density range 0·1⩽ σ 3 ρ ⩽ 0·8 was derived by means of Monte Carlo sampling.
Abstract: The ‘potential distribution’ expressions derived by Widom for the pressure and chemical potential of a fluid are developed for the special case of a hard-sphere fluid. The exact equations produced are closely related to those used in Scaled Particle Theory. They have been used to determine the chemical potential of hard-sphere fluids over the reduced density range 0·1 ⩽ σ 3 ρ ⩽ 0·8 by means of Monte Carlo sampling. The chemical potential so obtained is in excellent agreement with that found by integrating over pressure as a function of volume. It is found, however, that the chemical potential is considerably more dependent on the sample size than the pressure. The Monte Carlo results for the nearest-particle distribution around random points in the fluid are compared with the predictions of Scaled Particle Theory. The agreement is close, particularly at low densities. Two simple methods of Monte Carlo sampling of the grand canonical ensemble—an exact method and a more convenient, though inexact, modificat...

310 citations


Journal ArticleDOI
TL;DR: The relationship of total body length to formalin dry weight for individuals of Thermo-cyclops hyalinus and Mesocyclops leuckarti, from the tropical Lake George, Uganda, is given and shows that previous estimates of individual biomass and, therefore, of zooplankton standing crop and production based on them, were too high.
Abstract: Summary The relationship of total body length to formalin dry weight for individuals of Thermo-cyclops hyalinus and Mesocyclops leuckarti, from the tropical Lake George, Uganda, is given and shows that previous estimates of individual biomass and, therefore, of zooplankton standing crop and production based on them, were too high. The annual mean standing crop of total Crustacea, in 1969–70 was 828 mg (dw) m−2 and for T. hyalinus, the dominant species, 559 mg (dw) m−2 Biomass tended to be higher in the mid-lake area than inshore. The annual mean production of T. hyalinus is now estimated to be 44 mg (dw) m−2 day.

99 citations


Journal ArticleDOI
TL;DR: Methylation studies have established the major linkages and electron-microscope autoradiography shows that the mucilage is packaged in the Golgi bodies, passing to the plasmalemma in large vesicles.
Abstract: 35SO42- has been used to investigate the production of extracellular mucilage by log-phase cells. Uptake of isotope occurs most rapidly in the light, when cells are actively dividing. The mucilage comprises about 50% carbohydrate, 16% protein and 10% sulphate. The major sugar is xylose; uronic acid, a small amount of galactose, glucose (trace) and 2 reducing substances are also present. Methylation studies have established the major linkages. Electron-microscope autoradiography shows that the mucilage is packaged in the Golgi bodies, passing to the plasmalemma in large vesicles. Sulphation of the mucilage occurs in the Golgi cisternae.

78 citations


Journal ArticleDOI
TL;DR: In this paper, the velocity autocorrelation function and the dynamical structure factor of the classical one-component plasma were computed for high densities, and the resulting dispersion curve was discussed.
Abstract: We present molecular-dynamics computations of the velocity autocorrelation function and the dynamical structure factor of the classical one-component plasma. At high densities, the former exhibits marked oscillations, whereas the latter consists of very sharp peaks near the plasma frequency, up to wave vectors of order $\frac{1}{a}$, where $a$ is the ion-sphere radius. The resulting dispersion curve is discussed.

58 citations


Journal ArticleDOI
TL;DR: Carotenoids in 38 species of Lepidoptera have been examined qualitatively and quantitatively and it was found that the Large White (Pieris brassicae), a toxic species, stored more carotenoid than the less toxic Small White ( P. rapae) while ab.
Abstract: Carotenoids in 38 species of Lepidoptera have been examined qualitatively and quantitatively. Comparisons are made between cryptic and aposematic species, pupae and adult, dried and fresh material, males and females, and certain polymorphic species. Although some selective storage is demonstrated, Lepidoptera chiefly store the carotenoids present in their food plants unchanged. It was found that the Large White (Pieris brassicae), a toxic species, stored more carotenoids than the less toxic Small White (P. rapae) while ab. coerulea (P. brassicae) contained only 25 % of the carotenoids found in typical specimens.

55 citations


Journal ArticleDOI
TL;DR: In this paper, the conformal solution approach is used to relate the distribution functions g αβ(r) for a fluid mixture to those of a pure fluid, g x(r).
Abstract: The conformal solution approach is used to relate the distribution functions g αβ(r) for a fluid mixture to those of a pure fluid, g x(r). The procedure is to expand g αβ(r) about the corresponding function for an ideal solution, using σ αβ 3 and eαβσαβ 3 as expansion parameters; the expansion of the function y αβ(r) is also considered. Molecular dynamics results are reported for the tg αβ for argon-krypton liquid mixtures using the Lennard-Jones (12, 6) potential. These results are used to test the conformal solution expansions to first order; the g αβ expansion is found to be superior to that for y αβ for most r values of interest. The second order term in the conformal solution expansion for the Helmholtz free energy is also calculated for argon-krypton mixtures, and found to be about 10 per cent of the value of A E given by the van der Waals 1 theory.

49 citations


Journal ArticleDOI
TL;DR: In this article, the polymeric, halogen-bridged complex (diene)RuX2]n (where diene = 1,5-cyclooctadiene) reacts with acetylacetone, benzoylacetone and salicylaldehyde in hot dimethylformamide in the presence of sodium carbonate, to give chelate complexes (Diene)ruthenium(chel)2.

44 citations


Journal ArticleDOI
TL;DR: The European partition of Africa: Coincidence or conjuncture? The Journal of Imperial and Commonwealth History: Vol. 3, The Partition of Africa, pp. 1-54.
Abstract: (1974). The European partition of Africa: Coincidence or conjuncture? The Journal of Imperial and Commonwealth History: Vol. 3, The Partition of Africa, pp. 1-54.

38 citations


Journal ArticleDOI
TL;DR: The results obtained suggest that hydrophobic interactions plays a significant role in stabilizing insoluble collagen, and may account for about 25% of the total stabilizing energy.

35 citations


Journal ArticleDOI
TL;DR: In this paper, Mannitol, sucrose, and laminitol have been isolated from ethanolic extracts of the brown seaweed Desmarestia aculeata and characterised.

28 citations




Journal ArticleDOI
TL;DR: In this article, a method for incorporating ionic polarization into molecular dynamics calculations is described and is shown to yield good results for the optical phonon frequencies in solid NaCl, and the method can be used to calculate the frequency of the phonon frequency in the case of any NaCl.

Journal ArticleDOI
TL;DR: This paper proves a conjecture of C. St. J. Nash-Williams giving necessary and sufficient conditions for an arbitrary countable system of sets to have a transversal.

Journal ArticleDOI
TL;DR: The polymeric chain consists, principally, of segments of isomaltose homologues which are mutually linked through positions 1 and 2 of their terminal D -glucose residues, and possesses five branches which occur at each position 6 of such segments and at positions 2.

Journal ArticleDOI
TL;DR: The optical constants n, k and sigma ( omega) of paramagnetic gadolinium and terbium have been determined from in situ reflection measurements on opaque films prepared in ultra high vacuum ( approximately 10-10 Torr) as mentioned in this paper.
Abstract: The optical constants n, k and sigma ( omega ) of paramagnetic gadolinium and terbium have been determined from in situ reflection measurements on opaque films prepared in ultra high vacuum ( approximately 10-10 Torr). Optimized reflection ratio measurements at oblique incidence in the photon energy range 1.8 to 3.1 eV give evidence of direct optical transitions at 1.95, 2.15, 2.50, 2.75 and 3.1 eV for gadolinium and at 1.90, 2.20 and 2.45 for terbium. Deductions from electronic band structure calculations for the bulk materials predict optical transitions at 2.0, 2.2, 2.4 to 2.6, 2.8 and 3.1 eV for gadolinium, and at 1.9, 2.2 and 2.5 eV and other energies for terbium.

Journal ArticleDOI
TL;DR: A study of the hydrolyzability of α-d-galactoside, α- d-fucoside and β-l-arabinoside showed that the presence of primary alcoholic group in the sugar was important for faster hydrolysis and a stronger binding.
Abstract: α-Galactosidase from Lens esculanta (red lentils) was purified 4090-fold through a multistep process involving acidification, ammonium sulphate fractionation, Sephadex gel filtration, DEAE-cellulose and CM-cellulose chromatography. The purified enzyme is stable at 4°C for nearly six months with only a small loss of activity. It showed a pH optimum of 5.5 with raffinose as the substrate and 6.0 with p-nitrophenyl-α-d-galactoside. The Km for the former substrate was 40 mM and for the latter, 0.26 mM. The enzyme failed to liberate galactose from guar gum, tara gum and locust bean gum galactomannans. A study of the hydrolyzability of α-d-galactoside, α-d-fucoside and β-l-arabinoside showed that the presence of primary alcoholic group in the sugar was important for faster hydrolysis and a stronger binding. The substrate specificity studies indicated the absence of any related glycosidase activity in the α-galactosidase preparation.

Journal ArticleDOI
01 Jul 1974
TL;DR: In this article, it was shown that if X is closed and X ∈ Lm, then X is the union of finitely many convex sets, and that X is also the class of convex subsets of the real Euclidean plane.
Abstract: All the sets with which we are concerned are subsets of the real Euclidean plane E2. By Lm we denote those subsets X of E2 for which, if pl, p2, …, Pm are any m points of X, then at least one segment pipj, i ≠ j consists entirely of points of X. L2 is the class of convex subsets of E2. We shall show that if X is closed and X ∈ Lm. then X is the union of finitely many convex sets. This extends a result of Valentine (4). See also (1),(2),(3).

Journal ArticleDOI
TL;DR: The presence of isozeaxanthin and absence of cantAXanthin in the larvae while both compounds were found in the adults suggest a precursor-product relationship, in agreement with possible pathways leading to the formation of keto-carotenoids.

Journal ArticleDOI
TL;DR: The enzyme activity is not stable during heating at pH 4.6 in the presence of serum albumin, and a temperature-dependent conformational change is proposed to account for this finding.


Journal ArticleDOI
TL;DR: The relative ease of formation of five-, six-, seven-, and eight-membered cyclic benzeneboronates is discussed in this paper, where it is suggested that the oxygen atom of the hydroxyl group is intramolecularly co-ordinated with the boron atom.

Journal ArticleDOI
TL;DR: A comprehensive investigation of the formation of small diffraction gratings by the effect of laser light on a thin film external to the laser cavity is reported.
Abstract: An optical etching technique for producing small diffraction gratings, in which a thin metallic film set at an angle to the axis of a ruby laser cavity acted as a Q-switch in the operation of that laser, was previously reported. Here we report a comprehensive investigation of the formation of such etched gratings by the effect of laser light on a thin film external to the laser cavity. A time resolved investigation has been made of the development of such gratings in a number of metallic films, and the effect of film thickness, incident laser intensity, and angular orientation of the film has been studied.

Journal ArticleDOI
TL;DR: In this paper, the growth of male and female parasitic stages of Nematospiroides dubius was measured in terms of dry weight and the relationship between body size and metabolic rate was established.
Abstract: The growth of male and female parasitic stages of Nematospiroides dubius from male and female ASH/CS1 mice was measured in terms of dry weight. No sex-linked resistance of mice to infection with N. dubius was apparent, as growth was the same in both sexes of host. The growth rate did not alter when moulting occurred.All parasitic stages of N. dubius consumed oxygen in vitro and oxygen was also shown to be necessary for motility and survival.The relationship between body size and metabolic rate was established for male and female parasitic N. dubius and the b values indicated that aerobic metabolism is of functional importance to this species.The size/metabolism relationship for the whole life-cycle was established.


Journal ArticleDOI
TL;DR: The separation of Cajanus indicus α- and β-galactosidase by CM-cellulose chromatography has been studied in this article, showing that α-Galactosidease (EC 3.2.1.22) has been resolved into two isoenzymes and β -galacto-sidase (E 3.1.2.23) into three.

Journal ArticleDOI
TL;DR: In this article, the acid-catalysed reaction of galactitol with butyraldehyde yields the 1,3 and 2,3-mono- and 1, 3:4,6-di-acetals, the structures of which were proved by chemical methods.

Journal ArticleDOI
TL;DR: It was found that oxidative processes occurred at a later date than in spring- and summer-grown plants, and the increased spring production of carotenoids in cabbage, are discussed in relation to the life style of P. brassicae.
Abstract: Comparison of summer, winter and spring-grown cabbage showed that carotene synthesis differed considerably. Spring-grown cabbage was found to produce a peak of carotenoids during the first week of growth, and this decreased after one month. In comparison, winter-grown cabbage was still producing more carotenoids after 1 month and came to a peak of carotenoid production between 1 and 2 months. The winter-grown cabbage plants were maintained for 12 months and it was found that oxidative processes occurred at a later date than in spring- and summer-grown plants. It is shown that total carotenoids and interconversions of carotenoids are a useful indication of the metabolic processes, including oxidation and degradation of carotenoids, occurring in maturing and senescing plants. The effect of variation of the vitamin A potent carotenoids in the cabbage, and the increased spring production of carotenoids in cabbage, are discussed in relation to the life style of P. brassicae .

Journal ArticleDOI
TL;DR: In this article, the reactions of several open-chain pentadienyltricarbonyliron cations with 1,3-dimethoxybenzene have been studied.

Journal ArticleDOI
01 Sep 1974
TL;DR: In this article, the authors considered the total edge length of polytopes inscribed in a given sphere and which contain its center, and considered some related problems considered by various authors which may be of interest to the reader.
Abstract: All sets considered in this paper will be subsets of n -dimensional Eucidean space E n . In this paper, we shall consider the ‘total edge-lengths’ of polytopes which are inscribed in a given sphere and which contain its centre. We first, however, mention some related problems considered by various authors which may be of interest to the reader.