The present paper represents an extension of recent work that considered the partitioning response of binary solvents placed into contact with charged, expandable clays. Previous theoretical work yielded a model of partitioning by performing a thermodynamic analysis, involving the work of polarization, on a binary solvent, treated as a continuum and residing within the interlayer space of a layered aluminosilicate clay. Partitioning, or the tendency for sorbed and bulk phases to have different compositions, was shown to be sensitive to the dielectric properties of the 2 solvents of the binary mixture and to the surface charge density on the clay, among other factors. Although previous experimental work has helped to validate the theory, additional work is reported here that looks at hysteresis effects, the role of the exchangeable cation (usually organic), the prediction of adsorption isotherms and the contribution that partitioning, or sorption, makes to the disjoining pressure that develops in binary solvent systems. In this current study, 3 different organo-clays were considered: Cetyltrimethylammonium (CTMA), Isopropanolammonium (IPA), and Benzylammonium (BA) montmorillonite. Solvent systems under study included: acetone/chloroform (a-c), acetone/quadricyclane (a-q) and acetonitrile/chloroform (an-c). While partitioning of the a-c system on CTMA-clay follows theory quite well, theory tends to over-predict partitioning for the a-q system on the same clay and under-predict partitioning for the an-c system on all clays. Predicted adsorption isotherms range from highly nonlinear to nearly linear. Finally, the delamination and subsequent swelling processes of BA-clay in a water/acetonitrile binary solvent system are very sensitive to composition, a result that is directly linked to the partitioning process.

Metal–silicate partitioning studies performed in high-pressure, laser-heated diamond anvil cells (DAC) are commonly used to explore element distribution during planetary-scale core–mantle differentiation. The small run-products contain suitable areas for analysis commonly less than tens of microns in diameter and a few microns thick. Because high spatial resolution is required, quantitative chemical analyses of the quenched phases is usually performed by electron probe microanalysis (EPMA). Here, EPMA is being used at its spatial limits, and sample thickness and secondary fluorescence effects must be accounted for. By using simulations and synthetic samples, we assess the validity of these measurements, and find that in most studies DAC sample wafers are sufficiently thick to be characterized at 15 kVacc. Fluorescence from metal-hosted elements will, however, contaminate silicate measurements, and this becomes problematic if the concentration contrast between the two phases is in excess of 100. Element partitioning experiments are potentially compromised; we recommend simulating fluorescence and applying a data correction, if required, to such DAC studies. Other spurious analyses may originate from sources external to the sample, as exemplified by 0.5 to >1 wt% of Cu arising from continuum fluorescence of the Cu TEM grid the sample is typically mounted on.

Allanite is present in most samples of the tonalitic Bell Island Pluton, with an average mode near 0.05 wt.%. Allanite occurs as cores in igneous epidote-clinozoisite and exhibits characteristic and consistent zoning patterns. REE-rich cores (All40-70) grade out towards epidote-clinozoisite with REE below electron microprobe detection limits. La, Ce and Pr contents are highest in the REE-rich cores of zoned crystals. Nd and Sm contents both initially increase as total REE decreases and are highest in intermediate zones. Y contents are generally low throughout, but tend to be highest in analyses with A115-20. The zoning behaviour exhibited by the allanite, specifically the rimward increases in Nd, Sm, and Y, cannot be accounted for by simple fractionation and are best explained by increases in allanite/ melt partition coefficients (Kd values) for these elements during crystallization. We propose that the variation in Kd values reflects modification of the allanite structure with changing REE content. These modifications are manifested by changes in colour, extinction, and pleochroism within the zoned crystals and include changes in unit-cell volume and dimensions. The changes in Kd values are large enough to result in crossing REE patterns within single allanite crystals. Fractional crystallization of zoned allanite can have noticeable effects on LREE contents and La/Sm (and almost certainly La/Lu) in magmas. In the Bell Island pluton, 80% of La, but <3% of Y is contained in allanite. Although some of the variation in the LREE chemistry of the pluton is attributable to statistical sampling error, much of it appears to reflect petrogenetic processes that controlled LREE abundance and, ultimately, allanite mode. One sample of Bell Island tonalite is depleted in LREE and has low La/Lu and La/Sm. These chemical features can be modelled by fractionation of zoned allanite.

In this reconnaissance study, skeletal materials from people, dating from ∼1500 B.P., who lived by or worked at the ancient copper mines and furnaces of the Wadi Faynan in southern Jordan, were analysed using atomic absorption spectrophotometry (AAS) to determine the intensities of accumulation of copper and lead in their bones. Many of the bones analysed contained concentrations of these metals which are comparable to those of modern individuals who are heavily exposed to metals through contemporary industrial processes.

Patterns of partitioning throughout the skeleton of a number of individuals were also studied. These AAS data suggest that within the human organism there may be some ability to influence the patterns of accumulation of copper within the skeleton. The humerus was frequently found to contain more copper than other bones studied. Within the humerus itself, the medial epicondyle frequently contained the highest concentrations, which may indicate a significant degree of organization or control of the process. These metal concentration data together with their toxicological consequences suggest that the health of the ancient human populations must have been adversely affected by exposure during life to copper in the environment. They also point to the need for further detailed studies of metal partitioning within the bones of the human skeleton.

The gastropod shell influences important aspects of the hermit crab's life; however, the shells are commonly a limited resource. Therefore, different hermit crab species that coexist in intertidal areas are commonly involved in intraspecific and interspecific competition for shells. We assess if differences in shell preference, exploitation ability, or competition by interference can explain the partitioning of shells between the coexisting species Calcinus californiensis and Clibanarius albidigitus. Clibanarius preferred shells of Nerita funiculata among the six gastropod shells tested, while Calcinus did not establish a hierarchy in shell preference. Therefore, the preference for gastropod shell species does not seem to diminish the competition for shells in the wild. Clibanarius identified and attended to chemical cues signalling potential sites of available shells (chemical cues of dead gastropods); Calcinus did not respond to these cues (competition by exploitation). However, Calcinus was more successful in obtaining a new shell by interspecific shell fighting than Clibanarius. Consequently, the use of better quality shells (intact shells) by Calcinus in the wild can be explained by its greater fighting ability compared with Clibanarius. The bias in shell distributions through dominance by shell fighting, more than by exploitation ability, has also been suggested for other hermit crab species of these genera.

Purple nutsedge (Cyperus rotundus L.) and yellow nutsedge (C. esculentus L.) appeared to be equally acceptable for oviposition by caged Bactra verutana Zeller, but purple nutsedge was significantly more suitable as a host: 90% of the larvae survived to maturity on purple nutsedge compared with 65% on yellow nutsedge. Responses of the plant species to both larval feeding injury and plant density were similar but purple nutsedge tended to be injured more than yellow nutsedge. At a high shoot density (nine shoots per pot), production of tubers by purple nutsedge was more adversely affected by feeding of five larvae per shoot than was production by yellow nutsedge: tuber dry weights were reduced 93 and 80% and numbers of tubers per pot were reduced 77 and 62%, respectively. Production of inflorescences was greatly reduced in both species. The effect of B. verutana on inflorescences may be more important for yellow nutsedge, which is generally considered to reproduce freely by seeds. Both species of nutsedge probably would be about equally affected by augmentation of B. verutana populations as a method of biological control.

The effects of 8-, 12-, and 16-h photoperiods on the growth and reproductive biology of purple nutsedge (Cyperus rotundus L.) were investigated over a 3-month period. Plants under the 8-h photoperiod produced the least total, shoot, root, rhizome, and tuber dry weight. Flowering occurred only at the 12-h photoperiod; thus, purple nutsedge is intermediate in flowering response to daylength. Although the total dry weight varied with photoperiod, the relative amount of dry weight (as percent of total weight) partitioned to shoots, roots, rhizomes, and tubers was constant.

Food partitioning between species is a common strategy for avoiding resource competition which allows the coexistence of two or more species in the same place. In order to evaluate the feeding of four species of batoids regularly caught by artisanal fisheries in southern Brazil, the present study aimed to analyse and compare the diet of the four batoid species. The Chola guitarfish, Rhinobatos percellens, had a specialized diet, consisting predominantly of blue crabs Callinectes sp., followed by teleost fish. The Lesser guitarfish Zapteryx brevirostris also had a very specialized diet, consuming mainly on Polychaeta, followed by Caridea shrimp. The Cownose ray, Rhinoptera bonasus, fed mainly on Ophiuroidea, followed by Gastropoda and Bivalvia. Finally, the Rio skate Rioraja agassizi, fed on teleost fish, Gammaridae, Caridea shrimp and Dendrobranchiata shrimp. An analysis of similarity showed significant differences among species in their diet. The trophic levels of the batoids in this study are <4.0, placing them in intermediate trophic levels. The analysis of the diets indicates that feeding differs substantially among the four species, suggesting a partitioning of food resources available in the environment.

Efficiency of food and nutrient (including energy) use are considered the key factors in the economic and environmental performance of livestock systems. The aim of this paper is to consider the basis of genetic variation in the components that constitute dietary nutrient efficiency; and to conclude whether there would be benefit, in any relevant terms, in including these components in breeding programmes that aim to improve nutrient efficiency within pig and poultry systems of production. The components considered are (i) external, pre-ingestion losses, such as food spillage and its relation to feeding behaviour traits, (ii) digestive efficiency, (iii) maintenance requirements, (iv) net efficiency of energy and nutrient utilisation and (v) partitioning of scarce resources within productive and between productive and fitness functions. It is concluded that opportunities to exploit genetic variation exist mainly in the potential to improve the digestive efficiency of pigs and to reduce the maintenance requirements for resources mainly in hens, but also potentially in pigs. Current evidence suggests that there are very weak genetic and phenotypic correlations between components of feeding behaviour and productive traits, and little genetic variation in the net efficiency of nutrient utilisation among poultry and pig genotypes. The implication of the latter is that there would be little exploitable genetic variation in the partitioning of scarce nutrients between productive functions. Currently, there is a lack of understanding of the genetic basis of the partitioning of scarce nutrients between productive and fitness functions, and how this may impact upon the efficiency of nutrient use in pig and poultry systems. This is an area of research to which further effort might usefully be devoted.

This paper demonstrates the development of a simple model of carbon flow during plant growth. The model was developed by six undergraduate students and their instructor as a project in a plant ecophysiology course. The paper describes the structure of the model including the equations that were used to implement it in Excel®, the plant growth experiments that were conducted to obtain information for parameterizing and testing the model, model performance, student responses to the modeling project, and potential uses of the model by other students.

The mechanisms and regulation of storage lipid formation in seeds are reviewed. Seed storage lipids are ultimately derived from simple carbon compounds, such as sucrose, which are imported into seeds from source tissues, such as leaves or pods. The partitioning of this important carbon towards storage lipid, carbohydrate or protein is regulated by a complex interaction between genetically-determined endogenous factors and external environmental influences. Storage lipids are synthesized from fatty acids, derived from acetyl-CoA, and glycerol 3-phosphate. Fatty acid biosynthesis and probably acetyl-CoA formation, occurs within the plastids to produce oleoyl-CoA. Further elaboration of oleoyl-CoA to produce polyunsaturates, hydroxylates or very long chain acyl-CoAs occurs on the endoplasmic reticulum, as does the esterification of acyl-CoAs to glycerol-3-phosphate to produce the final triacylglycerol storage oil. The temporal and hormonal regulation of storage lipid accumulation in seeds is discussed.

A core part of any animal growth model is how it predicts the partitioning of dietary protein and energy to protein and lipid retention for different genotypes at different degrees of maturity. Rules of partitioning need to be combined with protein and energy systems to make predictions. The animal needs describing in relation to its genotype, live weight and, possibly, body composition. Some existing partitioning rules will apply over rather narrow ranges of food composition, animal and environment. Ideally, a rule would apply over the whole of the possible experimental space (scope). The live weight range over which it will apply should at least extend beyond the ‘slaughter weight range’, and ideally would include the period from the start of feeding through to maturity. Solutions proposed in the literature to the partitioning problem are described in detail and criticised in relation to their scope, generality and economy of parameters. They all raise the issue, at least implicitly, of the factors that affect the net marginal efficiency of using absorbed dietary protein for protein retention. This is identified as the crucial problem to solve. A problem identified as important is whether the effects of animal and food composition variables are independent of each other or not. Of the rules in the literature, several could be rejected on qualitative grounds. Those rules that survived were taken forward for further critical and quantitative analysis in the companion paper. (Sandberg et al. 2005)

Literature solutions to the problem of protein and energy partitioning in the growing pig are quantitatively examined. Possible effects of live weight, genotype and food composition on the marginal response in protein retention to protein and energy intakes, on protein and energy-limiting foods are quantified. No evidence was found that the marginal response in protein retention to ideal protein supply, when protein intake is limiting, is affected by live weight, genotype or environmental temperature. There was good evidence that live weight does not affect the marginal response in protein retention to energy intake when protein intake is not limiting. Limited data for different genotypes suggested no effects on this response. A general quantitative partitioning rule is proposed that has two key parameters; ep* (the maximum marginal efficiency for retaining the first limiting amino acid) and R* (the maximum value of R, the energy to protein ratio of the food, MJ metabolisable energy (ME)/kg digestible crude protein (DCP), when ep* is just achieved). When R<R* the material efficiency of using ideal protein is (ep*/R*)× R. The value of ep* was determined to be 0·763 (se 0·0130). There was no good experimental evidence that ep* is different for different amino acids. The best estimate of R* was 67·9 (se 1·65) MJ ME/kg DCP. Live weight, genotype and temperature did not affect the values of either parameter. A more general understanding of partitioning, including the effects of ‘stressors’ such as disease, may be achieved by using the preferred rule as a starting point.

The present study provides comparative data on the types and microhabitats of animal prey captured by associating saddleback Saguinus fuscicollis and moustached Saguinus mystax tamarins. The main prey items were katydids (Tettigoniidae, Orthoptera), stick grasshoppers (Proscopiidae, Orthoptera) and spiders (Araneida), although lizards (Squamata) and frogs (Anura) were also taken. The tamarins foraged for, and captured prey from, significantly different substrates. This resulted in a significant partitioning of the prey spectrum between the two species. Sylvan katydids (Pseudophyllinae) accounted for most of the prey of both species, but the moustached tamarins captured more bush katydids (Phaneropterinae) than the saddlebacks. The degree of dietary overlap was less for animal prey than the plant-based portion of the tamarins' diet.

Whereas much is known of the short-term growth response to elevated atmospheric CO2 concentrations, [CO2]elev, there is relatively little information on how the response of native species is modified by temperature, despite the fact that an increase in global mean temperature is expected to accompany the rise in [CO2]. In this study, five functionally related annual native species were exposed to different combinations of ambient and elevated [CO2] and temperatures in order to assess their response in terms of growth and allometry. Fast-growing annuals were selected for the study because their growth responses could be assessed over a major portion of the plant's life cycle and in as short a period as 8 wk. Plants were grown in eight hemi-spherical glasshouses, programmed to track outside ambient conditions and provide a replicated experimental design. Treatments comprised (i) current ambient [CO2] and temperature, (ii) elevated [CO2] (ambient+34 kPa), and ambient temperature (iii) ambient [CO2] and elevated temperature (ambient+3°C) and (iv) elevated [CO2] and elevated temperature (T°Celev). All five species responded positively to [CO2]elev, although the response was statistically significant for only one, Poa annua L. Averaged over all five species, [CO2]elev increased total plant biomass by 25% (P=0·005) at 56 d, reflecting a proportionally greater increase in leaf and stem mass relative to root weight. Elevated [CO2] had no effect on leaf area, either at the individual species level or overall. Elevated T°C, by contrast, had little effect on shoot growth but increased root mass on average by 43% and leaf area by 22%. Few interactions between elevated [CO2] and T°C were observed, with the CO2 response generally greater at elevated than ambient T°C. Both [CO2]elev and T°Celev resulted in a transient increase in relative growth rate, (rgr), during the first 14 d exposure and a 3°C increase in temperature had no effect on the duration of the response. CO2 stimulation of growth operated through a sustained increase in net assimilation rate. (nar), although the potential benefit to rgr was offset by a concurrent decline in leaf area ratio (lar), as a result of a decrease in leaf area per unit leaf mass (sla). The response to T°Celev was generally opposite of that to [CO2]elev. For example, T°Celev increased lar through an increase in sla and this, rather than any effect on nar, was the major factor responsible for the stimulation of rgr. Allometric analysis of CO2 effects revealed that changes in allocation observed at individual harvests were due solely to changes associated with plant size. Elevated T°C, by contrast, had a direct effect on allocation patterns to leaves, with an increase in leaf area expansion relative to whole plant mass during the initial stages of growth and subsequent increased allocation of biomass away from leaves to other regions of the plant. No change in the allometric relation between roots and shoots were observed at either elevated [CO2] or T°C. We conclude, therefore, that allocation of biomass and morphological characteristics such as sla, are relatively insensitive to [CO2], at least when analysed at the whole-plant level, and where changes have been observed, these are the product of comparing plants of the same age but different size.

To study the role of fructan in leaf development of barley seedlings, fructan contents and the activities of enzymes involved in fructan metabolism were measured in segments of the third leaf at the stage of maximal growth. Fructans amounted to more than 10% of the d. wt in the growth zone at the base of the developing leaf and decreased sharply in the zone above. The specific activities of sucrose[ratio ]sucrose 1-fructosyltransferase (1-SST) and sucrose[ratio ]fructan 6-fructosyltransferase (6-SFT), two key enzymes in fructan synthesis, also peaked in the growth zone but decreased more slowly in the zone above. By contrast, the specific activities of invertase and fructan exohydrolase (FEH) were low in the growth zone at the leaf base and had their peak just above it. The specific activity of fructan[ratio ]fructan 1-fructosyltransferase (1-FFT) was approx. constant over the whole leaf. These results indicate that transitory accumulation of fructans in the growth zone plays a key role in the development of barley leaves.

This study investigated the mechanisms which control the partitioning between roots and shoots in plants subjected to changes in environment. Two types of analyses were used: firstly, an examination of the cost and revenue associated with investment in different plant parts, and secondly, a test of the principle of functional equilibrium between roots and shoots, i.e. whether root dry matter × root specific activity balances shoot dry matter × shoot specific activity. Measurements were made on individual plants of Lolium perenne in sunlit controlled environments, grown from germination to canopy closure under optimal nitrogen supply. At the final harvest, increased air temperature (+4 °C above ambient) reduced whole-plant dry matter by 12% relative to the control, whereas elevated CO2 mole fraction (700 μmol mol−1) led to a 38% gain. The combined treatment yielded an intermediate result (+19%). Plants grown at +4 °C maintained balanced activity between roots and shoots throughout the experimental period, irrespective of CO2 concentration. This required enhanced allocation to roots in young plants to compensate for a strong negative effect of higher temperature on root specific activity, which suggests that plants conserve balanced activity by adjusting dry matter partitioning. The extra cost involved with the adjustment at +4 °C significantly enhanced the cost[ratio ]revenue ratio of plant investment. In ambient temperature, the balance between roots and shoots departed from equilibrium, slightly at ambient but substantially at elevated CO2: the plants accumulated excess carbon relative to nitrogen, and this imbalance increased with plant age. At elevated CO2, the cost[ratio ]revenue ratio increased in young plants but this was later reversed owing to loss of root specific activity, which explains the gradually declining CO2 stimulation with time. The strategies in equilibrating root and shoot functioning observed in the different treatments are discussed in the light of whole plant performance.

The zoned McMurry Meadows Pluton has been examined for REE and trace element variations in hornblende, sphene, apatite, allanite and zircon. Mineral separates (17), were analysed by INAA from four granitoids spanning the compositional range of the pluton (60%–75% SiO2). All of the phases examined exhibit significant compositional variations, with sphene having the largest changes in chondrite normalised REE patterns. Compositional variations in these minerals are related to paragenetic sequence and, as the whole rocks become more evolved, increases in partition coefficients; not subsolidus re-equilibration. Hornblende is only a dominant site for REE in granites where sphene is a later crystallising phase, otherwise allanite (LREE only) and sphene are the dominant whole rock sites for REE. Zircon and apatite normally contribute less than 10% each to the whole rock abundance of REE. Three zircon samples contain only small compositional differences and are interpreted as having crystallised from the bulk magma prior to differentiation. Zr variation in the pluton is nonlinear, first increasing and then decreasing with whole rock fractionation. A simple process, analogous to “restite unmixing” applied to the Zr variation, defines a bulk magma composition of about 63% SiO2, before differentiation of the zoned pluton. The modelled bulk magma need only have evolved by about 2·5% silica and still have produced the entire compositional range (60–75% SiO2) observed in the pluton.