Showing papers by "Commonwealth Scientific and Industrial Research Organisation published in 1975"
TL;DR: In this paper, it was shown that the error due to heat conduction to the supports is particularly important with natural convection, especially where the heat loss and the temperature rise of the cylinder are calculated from the voltage drop across it.
Abstract: Publisher Summary Accurate knowledge of the overall convective heat transfer from circular cylinders is of importance in a number of fields, such as boiler design, hotwire anemometry, and the rating of electrical conductors. The wide dispersion in the published experimental data for the heat transfer from smooth circular cylinders by natural and forced convection is attributed to various factors associated with the experiments. The error due to heat conduction to the supports is particularly important with natural convection, especially where the heat loss and the temperature rise of the cylinder are calculated from the voltage drop across it. A common cause of error is the use of too small a space ratio, so that the temperature and velocity fields are distorted. To reduce this error to less than l%, the space ratio D c /D for natural convection or D T /D for forced convection should exceed 100. The error caused by blockage with wind tunnel measurements can be calculated depending on the type of tunnel. One of the greatest sources of error with forced convection is the failure to allow for the effect of stream turbulence.
761 citations
TL;DR: A method has been developed to stain rapidly protein zones not only in standard but also in isoelectric focusing polyacrylamide gels that selectively visualizes the arginine- rich histones because of the solubility of the lysine-rich histones in PCA.
589 citations
TL;DR: Previous and new infrared spectroscopic studies on collagen are considered and the infrared spectra of a number of polymers with collagen‐like features are presented.
Abstract: The set of synthetic polytripeptides and polyhexapeptides which can adopt a triple-helical form constitute a good model system for investigating collagen structure. Here we consider previous and new infrared spectroscopic studies on collagen and present the infrared spectra of a number of polymers with collagen-like features.
The amide A band position for all triple-helical polypeptides is higher than that observed for most proteins and polypeptides, and this high frequency appears to be related to the degree of supercoiling of the triple helix. It is possible that with increased supercoiling of the three chains the angles between the groups involved in the intramolecular hydrogen bonds become less favorable, or these bonds may become unusually long.
The frequency of the amide I band varies considerably for triple-helical polypeptides with different amino acid sequences, and often minor bands are observed. This finding contrasts with the observations for polypeptides in a pleated sheet or α-helical form, where the same amide I frequency is observed regardless of the amino acid composition. An explanation for this variation is proposed in terms of the hydrogen bonding properties of imino acids.
Significant spectral changes in the amide I region are observed on hydration in the spectra of some triple-helical polypeptides, but corresponding changes have not been found in the collagens examined.
499 citations
249 citations
TL;DR: By using a suitable heating time, approximately equal colour yields can be obtained from glucose and fructose using the anthrone reagent and the colour yield is more than doubled in the presence of hydrochloric and formic acids.
236 citations
TL;DR: The point-diffraction interferometer as discussed by the authors is an inter-ferometer for measuring phase variations in which the reference wave is produced by a point discontinuity in the path of the beam.
Abstract: The point-diffraction interferometer is an interferometer for measuring phase variations in which the reference wave is produced by a point discontinuity in the path of the beam. Its simplicity makes it very suitable for testing instruments in situ, and some such tests are described. The general theory shows that other diffracting apertures can be used and relates the technique to phase-contrast microscopy and to scatter-plate interferometry.
235 citations
TL;DR: This chapter discusses the way the performance of these may vary according to the insect's state of deprivation, and the number of behavioral components involved in the total feeding behavior of an insect depends upon its temporal and spatial relationships with its food.
Abstract: Publisher Summary There is abundant evidence that insects possess mechanisms that enable them to regulate their intake of food and water with a considerable degree of precision. The total feeding behavior of most insects is made up of a number of components, and this chapter discusses the way the performance of these may vary according to the insect's state of deprivation. A discussion of the long-term regulation of feeding in relation to the behavioral variations in the components of feeding is presented in the chapter. The number of behavioral components involved in the total feeding behavior of an insect depends upon its temporal and spatial relationships with its food. It is well known that the locomotor behavior of a number of insects changes according to their state of deprivation in ways that enhance the deprived insect's chances of making contact with food. Changes have been demonstrated in the general level of spontaneously directed locomotor activity, in behavior involving usually orientated movement in response to stimuli, provided by the food itself, and in orientated behavioral responses to physical factors of the environment.
234 citations
TL;DR: In this paper, it was shown that if the space is a normed topological space, then under some continuity conditions on the transition probabilities of {Xn} the conditions for ergodicity will be met if there is a compact set K and an ϵ > 0 such that E {X n+1 ‖ − ‖X n ‖ ∣ X n = x} ⩽ −ϵ whenever x lies outside K and is bounded, x ∈ K.
233 citations
TL;DR: Several plant metabolites, including sugars known to favour rhizobial growth and citric acid cycle intermediates, were examined for their effect on this latter system and as possible direct inducers of nitrogenase activity in cultured rhizobia.
Abstract: IT has been widely believed that the legume root-nodule bacteria (Rhizobium spp.; rhizobia) fix N2 only within the tissues of the host plant1. There have however been recent reports that a strain of cowpea rhizobia, 32H1, developed nitrogenase activity when grown in association with legume or non-legume plant cells2,3. The induction of nitrogenase was apparently due to a diffusible factor(s) secreted by the plant cells, since nitrogenase activity was detected when strain 32H1 was grown adjacent to, but not in contact with, tobacco cells3. Several plant metabolites, including sugars known to favour rhizobial growth4,5 and citric acid cycle intermediates6,7, were examined for their effect on this latter system and as possible direct inducers of nitrogenase activity in cultured rhizobia. This led to the formulation of a defined medium on which strain 32H1 fixed N2 in the absence of plant cells.
217 citations
TL;DR: A survey of the occurrence and relative amounts of 3-isopropyl-, 3-sec-butyl- and 3isobutyl-2-methoxypyrazines in a broad selection of raw vegetables was made in this paper.
Abstract: A survey has been made of the occurrence and relative amounts of 3-isopropyl-, 3-sec-butyl- and 3-isobutyl-2-methoxypyrazines in a broad selection of raw vegetables. At least one of these compounds was detected in all but four and all three were identified in 13 of the 27 vegetable tissues examined. The technique is described for their separation, identification and estimation. This involved headspace collection of total volatiles on porous polymer traps, separation by trapping and transfer between capillary columns and mass spectral identification. A general synthesis of 3-substituted-2-methoxypyrazines giving high yields and single end products is described. A possible biogenesis of the named compounds is discussed.
205 citations
TL;DR: In this paper, the slow reactions between phosphate and soil were studied by incubating, at a range of temperatures, soils to which phosphate had been added in solution, after various intervals, solutions which were 0.01 M with respect to calcium chloride and which contained phosphate, were shaken briefly.
Abstract: The slow reactions between phosphate and soil were studied by incubating, at a range of temperatures, soils to which phosphate had been added in solution. After various intervals, solutions which were 0.01 M with respect to calcium chloride, and which contained phosphate, were shaken briefly
TL;DR: Estimates of the degree of nonrandom association among genes (linkage disequilibrium) can provide evidence of the role of natural selection in maintaining allozyme polymorphisms in natural populations and the maximum likelihood procedures for such estimates based on gametic or zygotic frequencies at the level of two loci are outlined.
TL;DR: A theoretical treatment of light attenuation within suspensions of phytoplankton, which takes account of the heterogeneous distribution of pigment in the system, is described, and a standardized procedure for calculating the spectral distribution of, and the vertical attenuation coefficients for, photo-synthetically active radiation within model phy Topolankton suspensions is outlined.
Abstract: SUMMARY
A theoretical treatment of light attenuation within suspensions of phytoplankton, which takes account of the heterogeneous distribution of pigment in the system, is described. As a measure of the effect of canopy structure on light attenuation, a new parameter, the penetration coefficient (Pλ) is introduced, this being defined as the ratio of the downward monochromatic radiation flux at a given depth in the suspension to that within an equivalent solution of the algal pigments. A set of rules is established, applicable to cells of any shape or orientation, which characterizes the relationship between the penetration coefficient and the parameters of canopy structure (cell number, size, pigment composition etc.). A standardized procedure for calculating the spectral distribution of, and the vertical attenuation coefficients for, photo-synthetically active radiation within model phytoplankton suspensions, is outlined.
01 Feb 1975
TL;DR: In this paper, the aggregation of ultrafine scheelite (CaWO4) suspensions in turbulent flow was simulated by a single bladed paddle stirrer in a baffled beaker, a system chosen to simulate industrial practice.
Abstract: Studies have been made of the aggregation of ultrafine scheelite (CaWO4) suspensions in turbulent flow. The turbulence was generated by a single bladed paddle stirrer in a baffled beaker, a system chosen to simulate industrial practice. Coagulation by an indifferent electrolyte and flocculation by a polyelectrolyte produced aggregates which were broken up by intense agitation. Quite different behavior was observed for scheelite suspended in dilute sodium oleate solutions. Aggregation occurred only at high stirring speeds, the extent of aggregation and the size of aggregates increasing the faster the suspension was stirred. Classical theories of colloid stability could not explain this “shear-flocculation” and other effects such as the higher energy of turbulent collisions and the energy of “hydrophobic association” are considered.
TL;DR: It is shown that for green algae suspended in water in which effectively all the blue light is removed by dissolved yellow substances (gelbstoff) the light attenuation properties of the suspension are rather similar to those of an equivalent solution of algal pigments: this is because the individual cells have relatively low absorption values in the spectral region (545–655 nm) in which most of the transmitted light occurs.
Abstract: SUMMARY
A theoretical treatment of light attenuation within natural phytoplankton suspensions, developed in a previous paper, has now been applied to model suspensions of green and blue-green algal cells and colonies, in order to obtain a quantitative assessment of the effects of changes in the phytoplankton canopy structure on light attenuation within the system. It is shown that for green algae suspended in water in which effectively all the blue light is removed by dissolved yellow substances (gelbstoff) the light attenuation properties of the suspension are rather similar to those of an equivalent solution of algal pigments: this is because the individual cells have relatively low absorption values in the spectral region (545–655 nm) in which most of the transmitted light occurs. With blue-green algae, which have a strong absorption in this region, there can be marked differences between the light attenuation properties of suspensions and of equivalent pigment solutions. The suspensions transmit substantially more photosynthetically active radiation than the solutions: the effect increases with cell/colony size, with algal concentration and with depth, and can amount to a difference of several-fold. Values of vertical attenuation coefficients, and increments in attenuation coefficients per unit algal concentration, for the photosynthetic waveband have been calculated, and their dependence on pigment composition and cell/colony size is demonstrated. Calculations have also been carried out to show the relationship between the phytoplankton canopy structure, and the euphotic depth and maximum sustainable standing crop, of the suspension.
Journal Article•
TL;DR: In this paper, Dyadchenko and Khatuntseva presented a complete structure analysis on a single crystal of pseudoruti le. The structure is based on hexagonal close-packed oxygens with metal atoms randomized with two thirds occupancy over half the available octahedral sites and fully ordered in the remaining sites.
Abstract: Samples of pseudoruti le from South Australian and Indonesian localit ies have been analyzed chemically and studied by X-ray diffraction techniques. A complete structure analysis has been carried out on a single crystal of the Indonesian material. The structure is based on hexagonal close-packed oxygens with metal atoms randomized with two thirds occupancy over half the available octahedral sites and fully ordered in the remaining sites. The ordered atoms form chains of alternately filled and empty octahedral sites along [001]. Poor correlation between these ordered chains leads to diffuse streaking of the metal-ordering reflections in certain planes perpendicular to [001]. We have obtained a satisfactory refinement of the single crystal intensity data for an azerage metal-ordering model defined by a hexagonal cell with a = 14.375 A and c = 4.615 A. The structural relationships between ilmenite, pseudoruti le, and ruti le are discussed. A twostage mechanism for the natural alteration of ilmenite to pseudorutile to rutile is proposed. An electrochemical corrosion model in the zone ofsaturation is suggested for the initial alteration of ilmenite to pseudorutile. Further alteration to rutile is considered to take place in a zone of oxidation via a dissolution and reprecipitation process. Introduction range of composition, e.g. Fe2Os.nTiOr.mH2O;3 I n ( 5 and I I m ( 2 (Dyadchenko and Khatuntseva, Natural weathering of i lmenite, FeTiOr, involves 1960). Much of the confusion regarding this inoxidation of the ferrous iron to ferric, and progrestermediate alteration compound resulted because the sive removal of iron by leaching, resulting eventually usual method of characterization, powder X-ray in the production of ruti le, TiOr. As early as 1909 diffraction,proved unsatisfactorybecauseof thepoor (Palmer, 1909) it was recognized that the alteration of crystall inity of the alteration phases and because of i lmenite to ruti le proceeded through a distinct inthe coincidence of many of the diffraction l ines from termediate species with approximate composition different phases. These problems were overcome by FerO' ' 3TiOr. The intermediate alteration phase was Teufer and Temple ( 1966) by the application of single termed arizonite by Palmer (1909). Whether arizonite crystal X-ray diffraction techniques to single crystal is an independent mineral with a definite structure grains of altered i lmenite from commercial i lmenite and composition has been the subject of considerablb concentrates. They identif ied a new compound with debate (Miller, 1945; Lynd, Sigurdson, North, and hexagonal symmetry and with composition approxAnderson, 1954; Dyadchenko and Khatuntseva, imating FerTirO, as the main constituent of the 1960; Bykov, 1964); a number of researchers supaltered product. Small amounts of auxil iary i lmenite ported the alternative thesis that arizonite was a and ruti le gave separate, easily identif iable single polymineralic mixture of ruti le, anatase, hematite, crystal X-ray patterns. Structure factor calculations and ilmenite (Ernst, 1943; Overholt, Vaux, and were carried out for the new compound, which these Rodda, 1950). However, regardless of whether it was authors named pseudoruti le. The general structure called afizonite, proarizonite (Bykov, 1964), or was shown to consist of a hexagonal close-packed oxamorphous iron-titanate (Bailey, Cameron, Spedden, ygen lattice with metal atoms statistically distributed and Weege, 1956), most researchers were agreed that over the available octahedral sites. However, such a the alteration of i lmenite proceeded through a disdisordered model for pseudoruti le, with a random distinct intermediate isotropic material with a narrow tribution of metal atoms, does not readily explain the
TL;DR: In this article, the authors studied ammonification of soil organic N and nitrification of ammonium-N in Tindall clay loam over a range of temperatures from 20 to 60 C.
Abstract: Ammonification of soil organic N and nitrification of ammonium-N was studied in Tindall clay loam over a range of temperatures from 20–60 C. Nitrification rates at each temperature were constant throughout the 28 day incubation, whereas most of the ammonification occurred in the first 7 days. The optimum for nitrification was close to 35 C. exhibiting a sharp peak at this temperature at which the potential rate was 4.8 μg N/g day−1, compared with 0.5 μg N/g day−1 at 20°C and 0.25 μg N/g day−1 at 60°C. The optimum temperature for ammonification was approximately 50°C at which the rate was 2.8 μg N/g day−1 in the first 7 days but only 0.5 μg N/g day−1 between 14 and 28 days. The temperature responses could be described mathematically with functions of the type logo N = k × 1/T. The results are discussed in relation to daily patterns of N mineralization in the field where temperatures show diurnal fluctuation.
TL;DR: It is found that higher plants which fix carbon dioxide by way of the Calvin C3 cycle pathway differ in 13C/12C ratios from plants whichfix carbon dioxide through the C4-dicarboxylic acid pathway, and these ratios are expressed relative to a carbonate standard5.
Abstract: ABOUT 99% of all carbon is the 12C isotope while 1% is 13C. The precise ratio of the isotopes will vary depending on the material analysed. In plants, fractionation of carbon is brought about primarily by carbon dioxide assimilation in photosynthesis and is due to preferential utilisation of 12C and exclusion of 13C. Curiously enough, it has been found recently1,2 that higher plants which fix carbon dioxide by way of the Calvin C3 cycle pathway differ in 13C/12C ratios from plants which fix carbon dioxide through the C4-dicarboxylic acid pathway. Temperate pasture species fix carbon by way of the Calvin pathway and have 13C/12C ratios of approximately −28‰ (ref. 3 and M.M.L., J.H.T., and R. J. Jones, unpublished), whereas tropical pasture grasses fix carbon through the C4-dicarboxylic acid pathway4 and have 13C/12C ratios of approximately −12‰ (ref. 2 and M.M.L., J.H.T., and R.J.J., unpublished). 13C/12C ratios are expressed relative to a carbonate standard5.
TL;DR: In this paper, Pot culture experiments are described which attempt to identify the organic fractions of soil sulphur that decompose during the growing season to provide plant-available sulphur, and the effect of moisture stress on the uptake of sulphur by plants is also investigated; this treatment had little effect.
Abstract: Pot culture experiments are described which attempt to identify the organic fractions of soil sulphur that decompose during the growing season to provide plant-available sulphur. Soil organic matter was labelled with 35S by incubating soil with labelled sulphate and several organic sulphur fractions were determined before and after the growth of Sorghum vulgare and following a fallow treatment. The effect of moisture stress on the uptake of sulphur by plants was also investigated; this treatment had little effect. Changes occurred in both hydriodic acid-reducible and carbon-bonded sulphur fractions, 60 per cent of the sulphur taken up by the plants being derived from the latter. The changes in carbon-bonded sulphur involved changes in both Raney nickel-reducible and non-reducible sulphur fractions. All of the sulphur fractions investigated thus contributed available sulphur for plant uptake, and none of them are likely to be of any value for predicting the sulphur requirements of plants.
TL;DR: The reactivity of silver(I) ions towards twenty amino acids has been studied in aqueous unbuffered solutions using an ion-selective electrode as a highly sensitive monitor, finding the interaction with all of these species except cysteine is too weak to affect significantly the determination of thiol in proteins by the customary argentometric titration method.
TL;DR: There were few differences due to breed, age of ewe, nutrition, climate or location in the behaviour of the ewe before and during parturition, but fewer Southdowns and Merinos pawed the ground than ewes of other breeds.
TL;DR: Results of 298 nitrogen balance studies from experiments with male cross-bred lambs, which had been either fasted, or fed entirely on liquid diets of varying protein content at various energy intakes up to ad lib, were used to quantitatively describe the effects of the amount and quality of absorbed protein, energy intake and live weight on N balance and total N requirement of lambs.
Abstract: 1. Results of 298 nitrogen balance studies from experiments with male cross-bred lambs, ranging in weight from 3 to 38 kg, which had been either fasted, or fed entirely on liqid diets of varying protein content at various energy intakes up to ad lib. intake, were used to quantitatively describe the effects of the amount and quality of absorbed protein, energy intake and live weight on N balance and total N requirement of lambs. 2. When N intake was less than the amount required, N balance was independent of energy intake, but linearly related to absorbed N and metabolic body-weight (live weight-O-75). In the fitted relationship, the coefficient of absorbed N was shown to be an estimate of the biological value of absorbed protein and the coefficient of metabolic body-weight was an estimate of the loss of endogenous N in both urine and faeces. For the milk-based diets used in the experiment biological value was 0-72 and the total endogenous N loss in urine and faeces was 148 mg N/kg per d. 3. When N intake was in excess of the amount required, N balance in lambs of a constant live weight increased linearly with metabolizable energy (ME) intake, at a rate that decreased with increasing live weight. Similarly at constant ME intake, N balance was a curvilinear decreasing function of metabolic body-weight, it was constant for lambs of all weights when ME intake was about 0-23 MJ/kg-0-75 per d, but it decreased linearly with increasing metabolic body-weight for ME intakes above this level. 4. N balance of fasted lambs was several times less than predicted by either of the relationships established for fed animals, and was found to be linearly related to metabolic body-weight. 5. The effects of energy intake and live weight on the total N requirement of lambs were determined. When total N requirement was expressed per unit of energy intake, it was found to be constant at 0-9 g N/MJ ME for all lambs irrespective of live weight when ME intake was 0-23 MJ/kg-0-75 per d. However, as ME intake/unit metabolic body-weight was raised above this level, N requirement/unit ME intake increased for lambs weighing less than c. 23 kg, but decreased for heavier animals.
01 Jan 1975
TL;DR: In this article, it is shown that the reduction of dissolved oxygen is the major cathodic component in certain of these systems, e.g. oxygen pressure leaching, the weathering of ore bodies as a consequence of differential aeration, and flotation with thiol collectors.
TL;DR: It is suggested that cytochrome P-450 is a component of the leghaemoglobin-facilitated respiration pathway and that it may act as intracellular O2 carrier rather than terminal oxidase.
TL;DR: This work has shown that nodules formed on the non-legume Trema canabina are caused by a strain of Rhizobium which nodulated Vigna unguiculata (cowpea), possess nitrogenase activity and fix atmospheric nitrogen.
Abstract: THE maxim that nitrogen fixation by the root nodule bacteria, Rhizobium, is restricted to a formal symbiotic association with specific legumes has recently been challenged. Trinick1 showed that nodules formed on the non-legume Trema canabina (previously identified as T. aspera; M. J. Trinick, personal communication) by a strain of Rhizobium which nodulated Vigna unguiculata (cowpea), possess nitrogenase activity and fix atmospheric nitrogen. Soybean tissue cultures inoculated with R. japonicum2–4, or with cowpea strains of rhizobia3, also possess apparently functional nitrogenase as determined by the acetylene reduction assay5. Several attempts have failed to demonstrate nitrogenase activity in cultured rhizobia6, including cowpea strains7.