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The adaptation of teak to acid soils was tested by studying physiological responses of teak clones to varying concentrations of Ca, H (pH) and Al in solution and soil culture. Nutrient solutions containing 0.05, 0.8 or 10 mM Ca were adjusted to pH 4, 5, 6, or 7. Overall, the greatest growth was obtained with nutrient solutions containing 0.8 mM Ca at pH 6. Foliar Ca deficiency symptoms developed at 0.05 mM Ca. Sensitivity of teak clones to Al was tested at pH 4 and 0, 50 or 300 µM Al by staining of roots. Roots that were stained with Chromezurol S (CAS) also stained with hematoxylin, but not necessarily with Eriochrome Cyanine R (ECR). On the other hand, roots that stained with hematoxylin did not necessarily stain with CAS or ECR. This indicates that hydrolysis of Al (as detected by CAS) leads to membrane damage which is detected by hematoxylin. A selection of clones were grown in split pots containing either limed or non-limed soil, and Al activity in the soil solution related to root biomass. Five clones were identified as Al resistant in the solution screening, and two clones were Al resistant in the soil screen, with two clones resisting low pH and Al toxicity in soil and solution screens. This study revealed that some teak clones tolerate low pH soils and moderately toxic 25 µM {Al} activity, and may be suitable for poor soils, but soils used in Australia for teak plantations are often too hostile and would require amelioration. [ABSTRACT FROM AUTHOR]

We consider the energy difference restricted to a finite volume for certain pairs of incongruent ground states (if they exist) in the d-dimensional Edwards-Anderson Ising spin glass at zero temperature. We prove that the variance of this quantity with respect to the couplings grows proportionally to the volume in any $$d \ge 2$$ . An essential aspect of our result is the use of the excitation metastate. As an illustration of potential applications, we use this result to restrict the possible structure of spin glass ground states in two dimensions. [ABSTRACT FROM AUTHOR]

We consider the free energy difference restricted to a finite volume for certain pairs of incongruent thermodynamic states (if they exist) in the Edwards-Anderson Ising spin glass at nonzero temperature. We prove that the variance of this quantity with respect to the couplings grows proportionally to the volume in any dimension greater than or equal to two. As an illustration of potential applications, we use this result to restrict the possible structure of Gibbs states in two dimensions. [ABSTRACT FROM AUTHOR]

Background and aims: Close regulation of cellular Ca in roots is required in the face of marked changes in soil solution Ca over time and space. This study's aims were to quantify and gain insights into the ways in which roots respond to changes in solution Ca. Methods: Root elongation rate (RER) of cowpea ( Vigna unguiculata (L.) Walp.) seedlings was determined at 0.05 to 15 mM Ca for up to 24 h both without and with added K, Mg, or Na. Root tip concentrations of Ca, K, Mg, and Na were determined and binding of cations by root tips estimated by subsequent Cu sorption. Results: Transfer from higher to lower Ca solutions (and with added K at high Ca) resulted in RER ≥ 2 mm h within minutes. This was attributed to greater cell wall relaxation through lower Ca binding aided by a decrease to pH ≤ 5.1 in solution. Transfer to higher Ca solutions, which remained at ~pH 5.6, led to an equally rapid decrease in RER to ~0.5 mm h, an effect ascribed to greater cell wall binding of Ca. Thereafter, a gradual increase in RER to ~1.8 mm h occurred over 24 h, an effect likely due to reduced cell wall Ca binding as shown by decreasing Cu sorption at a rate of 0.027 mmol Cu kg FM h over 24 h. Conclusion: The kinetics of changes in RER and cations in root tips suggest that roots respond to changes in solution Ca through effects on cell wall relaxation of the rhizodermis and outer cortex in the elongation zone. [ABSTRACT FROM AUTHOR]

Rhizotoxic effects of many trace metals are known, but there is little information on recovery after exposure. Roots of 3-d-old cowpea ( Vigna unguiculata (L.) Walp. cv. Caloona) seedlings were grown for 4 or 12 h in solutions of 960 μM Ca and 5 μM B at two concentrations (which reduce growth by 50 or 85%) of nine trace metals that rupture the outer layers of roots. Measured concentrations were 34 or 160 μM Al, 0.6 or 1.6 μM Cu, 2.2 or 8.5 μM Ga, 2.3 or 12 μM Gd, 0.8 or 1.9 μM Hg, 1.0 or 26 μM In, 2.4 or 7.3 μM La, 1.8 or 3.8 μM Ru, and 1.3 or 8.6 μM Sc. Roots were rinsed, transferred to solutions free of trace metals, and regrowth monitored for up to 48 h. Recovery from exposure to Hg occurred within 4 h, but regrowth was delayed for ≥ 12 h with Al, Ga, or Ru. There was poor regrowth after 4 or 12 h exposure to Cu, Gd, In, La, or Sc. Roots recovered after being grown for 12 to 48 h in 170 μM Al, 5.1 μM Ga, 2.0 μM Hg, or 1.4 μM Ru, but the extent of recovery was reduced with longer exposure time. Microscopy showed marked differences in symptoms on roots recovering from exposure to the various trace metals. Differences in (i) concentrations that are toxic, (ii) ability of roots to recover, (iii) time for recovery to occur, and (iv) symptoms that develop, suggest that each trace metal has a unique combination of rhizotoxic effects. [ABSTRACT FROM AUTHOR]

Pectin, which is an important component of plant cell walls, strongly binds Al and this may play a role in expression of Al toxicity. Sorption of aluminium (Al) and lanthanum (La) from aqueous solutions onto pectic acid, Ca-pectate and plant cell wall material was pH dependent. For Al at pH 3, sorption was less than the available sorption sites (i.e., the cation exchange capacity) on all three sorbents, whereas at pH 4, sorption of Al was in excess of available sorption capacity. By contrast, sorption of the trivalent Al analogue La corresponded to the available sorption capacity on all three sorbents at pH 5. This indicates, therefore, that Al hydrolyses at ≥ pH 4, and hydrolysis increases with Al concentration in solution. Further, it is proposed that the sorption of Al to pectin leads to deprotonation of the galacturonic acid (GalA) residues. Sorption of Al to pectin limits hydrolysis of Al, thereby shifting the pH of hydrolysis to a higher value. Hydrolysis of Al results in its sorption in excess of the stoichiometric equivalent (assuming the free Al3+ ion), leading to oversaturation of the pectin with Al. Staining of the metal-pectate complexes with the metachromatic dye eosin showed that with increasing Al saturation (but not La saturation), the complex developed a positive net charge, due to formation of some positively charged Al-complexes. The development of a positive charge on the Al-pectate complex may have major effects on cellular transmembrane potential and nutrient acquisition by plant roots. This is the first report of Al binding in excess of binding sites and development of a net positive charge on Al-pectate. [ABSTRACT FROM AUTHOR]

Mechanical properties of hydrated bacterial cellulose have been tested as a function of fermentation time and following the alkali treatment required for sterilisation prior to biomedical applications. Bacterial cellulose behaves as a viscoelastic material, with brittle failure reached at approximately 20% strain and 1.5 MPa stress under uniaxial tension. Treatment with 0.1 M NaOH resulted in minimal effects on the mechanical properties of bacterial cellulose. Fermentation time had a large effect on both bacterial numbers and cellulose yield but only minor effects on mechanical properties, showing that the fermentation system is a robust method for producing cellulose with predictable materials properties. The failure zone in uniaxial tension was shown to be associated with large-scale fibre alignment, consistent with this being the major determinant of mechanical properties. Under uniaxial tension, elastic moduli and failure stresses are an order of magnitude lower than those obtained under biaxial tension, consistent with the fibre alignment mechanism which is not available under biaxial tension. [ABSTRACT FROM AUTHOR]

Low concentrations of Al, Cu and La rapidly decrease root elongation and cause transverse ruptures to the rhizodermis and outer cortex, but it is not known if other trace metals have similar effects. Six trace metals, Ga, Gd, Hg, In, Ru, and Sc, decreased cowpea root growth and caused ruptures similar to those caused by Al, Cu and La. Calculated speciation of the metals showed that only Gd was almost exclusively present as the trivalent ion (Gd3+), but the other test solutions were dominated by Ga(OH)2 +, HgCl2 0, either In3+, In(OH)2+, In(OH)2 +, In(OH)3 0, or InCl2+, and Sc3+ or ScOH2+ (no thermodynamic constants were available for Ru). The results from this and other studies suggest that the ability of these trace metals (plus Al, Cu, and La) to cause ruptures is related to the strength to which the trace metals bind to the cell wall. Therefore, it is proposed that the toxic effects of trace metals results from (1) the strength of binding (either ionically or covalently), and (2) other toxic effects of the metals not dependent on cell wall interactions. [ABSTRACT FROM AUTHOR]

We define and study entanglement of continuous positive definite functions on products of compact groups. We formulate and prove an infinite-dimensional analog of the Horodecki Theorem, giving a necessary and sufficient criterion for separability of such functions. The resulting characterisation is given in terms of mappings of the space of continuous functions, preserving positive definiteness. A relation between the developed group-theoretical formalism and the conventional one, given in terms of density matrices, is established through the non-commutative Fourier analysis. It shows that the presented method plays the role of a “generating function” formalism for the theory of entanglement. [ABSTRACT FROM AUTHOR]

Alumina extraction from bauxite ore with strong alkali produces waste bauxite refinery residue consisting of residue sand and red mud. The amount and composition of refinery residue depend on the purity of the bauxite ore and extraction conditions, and differs between refineries. The refinery residue is usually stored in engineered disposal areas that eventually have to be revegetated. This is challenging because of the alkaline and sodic nature of the residue. At Alcan Gove’s bauxite refinery in Gove, Northern Territory, Australia, research into revegetation of bauxite residue has been conducted since the mid-1970s. In this review, we discuss approaches taken by Alcan Gove to achieve revegetation outcomes (soil capping of refinery residue) on wet-slurry disposal areas. Problems encountered in the past include poor drainage and water logging during the wet season, and salt scalding and capillary rise during the dry season. The amount of available water in the soil capping is the most important determinant of vegetation survival in the seasonally dry climate. Vegetation cover was found to prevent deterioration of the soil cover by minimising capillary rise of alkalinity from the refinery residue. The sodicity and alkalinity of the residue in old impoundments has diminished slightly over the 25 years since it was deposited. However, development of a blocky structure in red mud, presumably due to desiccation, allows root penetration, thereby supplying additional water to salt and alkali-tolerant plant species. This has led to the establishment of an ecosystem that approaches a native woodland. [ABSTRACT FROM AUTHOR]

Phytoplankton and allochthonous matter are important sources of dissolved organic carbon (DOC) for planktonic bacteria in aquatic ecosystems. But in small temperate lakes, aquatic macrophytes may also be an important source of DOC, as well as a source or sink for inorganic nutrients. We conducted micro- and mesocosm studies to investigate the possible effects of an actively growing macrophyte, Vallisneria americana, on bacterial growth and water chemistry in mesotrophic Calder Lake. A first microcosm (1 L) study conducted under high ambient NH+4 levels (NH+4 ≥ 10 µM) demonstrated that macrophytes had a positive effect on bacterial densities through release of DOC and P. A second microcosm experiment, conducted under NH+4 - depleted conditions (NH+4 < 10 µM), examined interactive effects of macrophytes and their sediments on bacterial growth and water chemistry. Non-rooted macrophytes had negative effects on bacterial numbers, while rooted macrophytes had no significant effects, despite significant increases in DOC and P. A 70-L mesocosm experiment manipulated macrophytes, as well as N and P supply under surplus NH+4 conditions (NH+4 ≥ 10 µM), and measured effects on bacterial growth, Chl a concentrations, and water chemistry. Bacterial growth and Chl a concentrations declined with macrophyte additions, while bacterial densities increased with P addition (with or without N). Results suggest that the submersed macrophyte Vallisneria exerts a strong but indirect effect on bacteria by modifying nutrient conditions and/or suppressing phytoplankton. Effects of living macrophytes differed with ambient nutrient conditions: trader NH+4 - surplus conditions, submersed macrophytes stimulated bacterioplankton through release of DOC or P, but in NH+... [ABSTRACT FROM AUTHOR]

We study the front dynamics of solutions of the initial value problem of the Burgers equation with initial data being the viscous shock front plus the white noise perturbation. In the sense of distribution, the solutions propagate with the same speed as the unperturbed front, however, the front location is random and satisfies a central limit theorem with the variance proportional to the time t, as t goes to infinity. With probability arbitrarily close to one, the front width is O(1) for large time. [ABSTRACT FROM AUTHOR]