bluuebunny/crossref_metadata_2025 huggingface dataset:
An entropic‐stochastic representation of rainfall intermittency: The origin of clustering and persistence
Authors: Koutsoyiannis Demetris
Published: January 2006

The well‐established physical and mathematical principle of maximum entropy, interpreted as maximum uncertainty, is used to explain the observed dependence properties of the rainfall occurrence process, including the clustering behavior and persistence. The conditions used for the maximization of entropy are as simple as possible, i.e., that the rainfall processes is intermittent with dependent occurrences. Intermittency is quantified by the probability that a time interval is dry, and dependence is quantified by the probability that two consecutive intervals are dry. These two probabilities are used as constraints in a multiple‐scale entropy maximization framework, which determines any conditional or unconditional probability of any sequence of dry and wet intervals at any timescale. Thus the rainfall occurrence process including its dependence structure is described by only two parameters. This dependence structure appears to be non‐Markovian. Application of this theoretical framework to the rainfall data set of Athens indicates good agreement of theoretical predictions and empirical data at the entire range of scales for which probabilities dry and wet can be estimated (from one hour to several months).
Sphingolipids differentially regulate mitogen‐activated protein kinases and intracellular Ca2+in vascular smooth muscle: effects on CREB activation
Authors: Mathieson Fiona A , Nixon Graeme F
Published: January 2006

Related sphingolipids, sphingosine 1‐phosphate (S1P) and sphingosylphosphorylcholine (SPC), have important effects on vascular smooth muscle. The aim of this study was to investigate the intracellular pathways regulated by S1P and SPC in rat cerebral artery.

In cerebral arteries, S1P increased extracellular signal‐regulated kinase (ERK)1/2 phosphorylation (5.2±1.4‐fold increase) but did not activate p38 mitogen‐activated protein kinase (p38MAPK) as assessed by immunoblotting. In contrast, SPC increased p38MAPK phosphorylation (3.0±0.3‐fold increase) but did not stimulate ERK1/2. This differential activation was confirmed by measuring activation of heat shock protein (HSP) 27, a known downstream target of p38MAPK. Only SPC, but not S1P, activated HSP27.

In enzymatically dispersed cerebral artery myocytes, SPC increased [Ca2+]iin a concentration‐dependent manner (peak response at 10 μM: 0.4±0.02 ratio units) as determined using the Ca2+indicator, Fura 2. In contrast to S1P, the SPC‐induced [Ca2+]iincrease did not involve intracellular release but was due to Ca2+influxviaL‐type Ca2+channels.

Despite differences in signalling, both S1P and SPC phosphorylated the transcription factor cAMP response element‐binding protein (CREB). S1P‐induced CREB activation was dependent on ERK1/2 and Ca2+‐calmodulin‐dependent protein kinase (CaMK) activation. CREB activation by SPC required both p38MAPK and CaMK activation, but not ERK1/2.

In conclusion, S1P and SPC activate distinct MAP kinase isoforms and increase [Ca2+]iviadifferent mechanisms in rat cerebral artery. This does not affect the ability of S1P or SPC to activate CREB, although this occursviadifferent pathways.

British Journal of Pharmacology(2006)147, 351–359. doi:10.1038/sj.bjp.0706600
Agonist activity of naloxone benzoylhydrazone at recombinant and native opioid receptors
Authors: Olianas Maria C , Concas Danilo , Onali Pierluigi
Published: January 2006

In the present study, we examined the pharmacological activity of the putativeκ3‐opioid receptor agonist naloxone benzoylhydrazone (NalBzoH) at recombinant human opioid receptors individually expressed in Chinese hamster ovary (CHO) cells and native opioid receptors present in rat striatum.

At theμ‐opioid receptor (MOR), NalBzoH stimulated guanosine‐5′‐O‐(3‐[35S]thio)triphosphate ([35S]GTPγS) binding (pEC50=8.59) and inhibited cyclic AMP accumulation (pEC50=8.74) with maximal effects (Emax) corresponding to 55 and 65% of those obtained with the MOR agonist DAMGO, respectively. The MOR antagonist CTAP blocked the stimulatory effects of NalBzoH and DAMGO with similar potencies.

At theκ‐opioid receptor (KOR), NalBzoH stimulated [35S]GTPγS binding (pEC50=9.70) and inhibited cyclic AMP formation (pEC50=9.45) as effectively as the selective KOR agonist (−)‐U‐50,488. The NalBzoH effect was blocked by the KOR antagonist nor‐binaltorphimine (nor‐BNI) (pKi=10.30).

In CHO cells expressing theδ‐opioid receptor (DOR), NalBzoH increased [35S]GTPγS binding (pEC50=8.49) and inhibited cyclic AMP formation (pEC50=8.61) almost as effectively as the DOR agonist DPDPE. Naltrindole (NTI), a selective DOR antagonist, completely blocked the response to NalBzoH (pKiof 10.40).

In CHO cells expressing the nociceptin/orphanin FQ (N/OFQ) receptor (NOP), NalBzoH failed to exert agonist effects and antagonized the agonist‐induced receptor activation.

When compared to other opioid receptor ligands, NalBzoH showed an efficacy that was lower than that of morphine at MOR, but higher at KOR and DOR.

In rat striatum, NalBzoH enhanced [35S]GTPγS binding and inhibited adenylyl cyclase activity. These effects were antagonized by either CTAP, nor‐BNI or NTI, each antagonist blocking a fraction of the NalBzoH response.

These data demonstrate that NalBzoH displays agonist activity at MOR, DOR and KOR expressed either in a heterologous cell system or in a native environment.

British Journal of Pharmacology(2006)147, 360–370. doi:10.1038/sj.bjp.0706601
Has the sun set on κ3‐opioid receptors?
Authors: Connor Mark , Kitchen Ian
Published: January 2006

μ‐Opioid receptor agonists are a mainstay of clinical analgesia, despite the significant unwanted effects and dependence liability associated with drugs like morphine. The quest for opioids that produce analgesia with fewer undesirable effects has lead to the putative identification of multiple opioid receptor subtypes, despite the identification of only four opioid‐related receptor genes. One such putative receptor subtype is the κ3 receptor, activation of which supposedly produces analgesia in animals. In the present issue of this Journal, Olianas and co‐workers have demonstrated that the prototypic κ3 agonist naloxone benzoylhydrazone is actually a partial agonist at the cloned μ, δ, and κ opioid receptors and an antagonist at opioid‐like NOP receptors. Together with a recent study that showed that high‐affinity naloxone benzoylhydrazone binding is abolished in triple μ/δ/κ receptor knockout mice, the present study provides strong evidence that in vivo effects attributed to κ3 receptor activation probably just reflect the combined actions of a particularly nonselective opioid drug. Indeed, molecular identification of any of the proposed subtypes of μ, δ, and κ opioid receptors has proven elusive, suggesting that it is perhaps time to retire the notion of opioid receptor subtypes until definitive evidence for their existence is provided.

British Journal of Pharmacology (2006) 147, 349–350. doi:10.1038/sj.bjp.0706603
TC‐2559 excites dopaminergic neurones in the ventral tegmental area by stimulatingα4β2‐like nicotinic acetylcholine receptors in anaesthetised rats
Authors: Wang Yun , Sherwood John L , Miles Colin P , Whiffin Gary , Lodge David
Published: January 2006

Thein vivoeffects of a selective partial agonist for neuronal nicotinic acetylcholine receptor (nAChRs)α4β2 subtype, TC‐2559, characterised recently inin vitropreparations, have been profiled. The brain bioavailability of TC‐2559 and its effects on the spontaneous firing and bursting properties of the dopaminergic (DAergic) neurones recorded extracellularly in the ventral tegmental area (VTA) were studied following systemic administration in anaesthetised rats.

Cumulative doses of TC‐2559 (0.021–1.36 mg kg−1, i.v.) increased both the firing and bursting activities of VTA DA neurones. The effect of bolus doses of TC‐2559 of 0.66 or 1.32 mg kg−1, i.v., was approximately equivalent to that of 0.0665 mg kg−1, i.v. nicotine.

The excitation evoked by both nicotine and TC‐2559 was fully reversed by DHβE (0.39–0.77 mg kg−1, i.v.), anα4β2‐subtype‐preferring nicotinic antagonist, and application of nicotine after DHβE failed to evoke any excitation. MLA (0.23 mg kg−1, i.v.), anα7 selective antagonist, failed to alter TC‐2559‐evoked excitation and bursting activities, and a novelα7 agonist (PSAB‐OFP; 0.23 mg kg−1, i.v.) was also without effect.

The present results indicated that TC‐2559 fully mimics nicotine by increasing both the excitability and bursting behaviour of VTA DA neurones, effects that are predominantly due to activation ofα4β2‐like nAChRs.

TC‐2559 has been demonstrated to be a usefulin vivopharmacological tool for studying theα4β2 subtype of nicotinic receptor.

British Journal of Pharmacology(2006)147, 379–390. doi:10.1038/sj.bjp.0706621
Role of NK1and NK2receptors in mouse gastric mechanical activity
Authors: Mulè Flavia , Amato Antonella , Vannucchi Maria Giuliana , Faussone‐Pellegrini Maria Simonetta , Serio Rosa
Published: January 2006

The aim of the present study was to examine the role of NK1and NK2receptors in the control of mechanical activity of mouse stomach. In this view, the motor effects induced by NK1and NK2receptor agonists and antagonists were analyzed, measuring motility as intraluminal pressure changes in mouse‐isolated stomach preparations. In parallel, immunohistochemical studies were performed to identify the location of NK1and NK2receptors on myenteric neurons and smooth muscle cells.

Substance P (SP) induced biphasic effects: a contraction followed by relaxation; neurokinin A (NKA) and [β‐Ala8]‐NKA(4−10), selective agonist of NK2receptors, evoked concentration‐dependent contractions, whereas [Sar9, Met(O2)11]‐SP, selective agonist of NK1receptors, induced concentration‐dependent relaxation.

SR48968, NK2receptor antagonist, did not modify the spontaneous activity and reduced the contractile effects induced by tachykinins without affecting the relaxation. SR140333, NK1receptor antagonist, did not modify the spontaneous activity and antagonized the relaxant response to tachykinins, failing to affect the contractile effects.

The relaxation to SP or to [Sar9, Met(O2)11]‐SP was abolished by tetrodotoxin (TTX) and significantly reduced byN‐nitro‐L‐arginine methyl ester (L‐NAME).

NK2‐immunoreactivity (NK2‐IR) was seen at the level of the smooth muscle cells of both circular and longitudinal muscle layers. NK1‐immunoreactive (NK1‐IR) neurons were seen in the myenteric ganglia and NK1/nNOS double labeling revealed that some neurons were both NK1‐IR and nNOS‐IR.

These results suggest that, in mouse stomach, NK1receptors, causing relaxant responses, are present on nitrergic inhibitory myenteric neurons, whereas NK2receptors, mediating contractile responses, are present at muscular level.

British Journal of Pharmacology(2006)147, 430–436. doi:10.1038/sj.bjp.0706645
Thermally activated escape rate for a Brownian particle in a double-well potential for all values of the dissipation
Authors: Kalmykov Yu. P. , Coffey W. T. , Titov S. V.
Published: January 2006

The translational Brownian motion in a (2-4) double-well potential is considered. The escape rate, the position correlation function and correlation time, and the generalized susceptibility are evaluated from the solution of the underlying Langevin equation by using the matrix-continued fraction method. The escape rate and the correlation time are compared with the Kramers theory of the escape rate of a Brownian particle from a potential well as extended by Mel’nikov and Meshkov [J. Chem. Phys. 85, 1018 (1986)]. It is shown that in the low-temperature limit, the universal Mel’nikov and Meshkov expression for the escape rate provides a good estimate of both escape rate and inverse position correlation time for all values of the dissipation including the very low damping (VLD), very high damping (VHD), and turnover regimes. Moreover, for low barriers, where the Mel’nikov and Meshkov method is not applicable, analytic equations for the correlation time in the VLD and VHD limits are derived.
Temperature- and solvation-dependent dynamics of liquid sulfur dioxide studied through the ultrafast optical Kerr effect
Authors: Jaye Andrew A. , Hunt Neil T. , Meech Stephen R.
Published: January 2006

The ultrafast dynamics of liquid sulphur dioxide have been studied over a wide temperature range and in solution. The optically heterodyne-detected and spatially masked optical Kerr effect (OKE) has been used to record the anisotropic and isotropic third-order responses, respectively. Analysis of the anisotropic response reveals two components, an ultrafast nonexponential relaxation and a slower exponential relaxation. The slower component is well described by the Stokes-Einstein-Debye equation for diffusive orientational relaxation. The simple form of the temperature dependence and the agreement between collective (OKE) and single molecule (e.g., NMR) measurements of the orientational relaxation time suggests that orientational pair correlation is not significant in this liquid. The relative contributions of intermolecular interaction-induced and single-molecule orientational dynamics to the ultrafast part of the spectral density are discussed. Single-molecule librational-orientational dynamics appear to dominate the ultrafast OKE response of liquid SO2. The temperature-dependent OKE data are transformed to the frequency domain to yield the Raman spectral density for the low-frequency intermolecular modes. These are bimodal with the lowest-frequency component arising from diffusive orientational relaxation and a higher-frequency component connected with the ultrafast time-domain response. This component is characterized by a shift to higher frequency at lower temperature. This result is analyzed in terms of a harmonic librational oscillator model, which describes the data accurately. The observed spectral shifts with temperature are ascribed to increasing intermolecular interactions with increasing liquid density. Overall, the dynamics of liquid SO2 are found to be well described in terms of molecular orientational relaxation which is controlled over every relevant time range by intermolecular interactions.
Photofragment alignment in the photodissociation of I2 from 450to510nm
Authors: Chestakov D. A. , Parker D. H. , Vidma K. V. , Rakitzis T. P.
Published: January 2006

A combination of velocity map imaging and slicing techniques have been used to measure the product recoil anisotropy and angular momentum polarization for the photodissociation process I2→I(P3∕22)+I(P3∕22) and I2→İ(P3∕22)+I(P1∕22) in the 450–510nm laser wavelength region using linearly polarized photolysis and probe laser light. The former channel is produced predominantly via perpendicular excitation to the Πu1 state, and the latter is predominantly parallel, via the BΠ3(0u)+ state. In both cases we observe mostly adiabatic dissociation, which produces electronically aligned iodine atoms in the ∣m∣=1∕2 states with respect to the recoil direction.
Cage motions induced by electronic and vibrational excitations: Cl2 in Ar
Authors: Fushitani M. , Schwentner N. , Schröder M. , Kühn O.
Published: January 2006

Femtosecond dynamics of molecular vibrations as well as cage motions in the B←X transition of Cl2 in solid Ar have been investigated. We observed molecular vibrational wave-packet motion in experimental pump-probe spectra and an additional oscillation with a 500fs period which is assigned to the zone-boundary phonon of the Ar crystal. The cage motion is impulsively driven by the B←X transition due to the expansion of the electronic cloud of the chromophore. To clarify the underlying mechanism, we performed simulations based on the diatomics-in-molecules method which takes into account the different shapes of the Cl2 electronic wave function in the B and X states as well as the anisotropic interaction with the matrix. The simulation results show that Ar atom motion in the (100) plane is initiated by the electronic transition and that only those Ar atoms oscillate coherently with an ∼500fs period which are essentially decoupled from the molecular vibration. Their phase and time evolution are in good agreement with the experimentally observed oscillation, supporting the assignment as a displacive excitation of coherent phonons.
Nuclear-spin relaxation in nonrigid molecules: Discrete multisite local dynamics combined with anisotropic molecular reorientation
Authors: Bernatowicz Piotr , Kowalewski Jozef , Szymanski Slawomir
Published: January 2006

Nuclear-spin relaxation is considered in a molecular system undergoing two types of dynamic processes: asymmetric-top small-step rotational diffusion and discrete multisite local jumps. The two processes are assumed to be uncorrelated. Time correlation functions for relevant rank-two interactions and corresponding spectral density functions are derived for a general relation between the characteristic rate constants. In addition, limiting cases of fast and slow local motions and of some specific jump conditions are also investigated.
Structure and binding energies of unsaturated hydrocarbons on Si(001) and Ge(001)
Authors: Cho Jun-Hyung , Kim Kwang S. , Morikawa Yoshitada
Published: January 2006

The adsorption of acetylene, ethylene, and benzene on the Si(001) and Ge(001) surfaces is investigated by first-principles density-functional calculations within the generalized-gradient approximation. We find that the adsorption energies of the three hydrocarbons containing a triple bond, a double bond, and a π-conjugated aromatic ring decrease as the sequence of C2H2>C2H4>C6H6. We also find that the bondings of acetylene, ethylene, and benzene to Ge(001) are much weaker than those to Si(001). As a result, benzene is weakly bound to Ge(001) while it is chemisorbed on Si(001), consistent with temperature-programed desorption data.
Two-state versus three-state quantization: An ab initio study of the three lower states of the {N,H2∣A′} system
Authors: Vibók Á. , Halász G. J. , Suhai S. , Hoffman D. K. , Kouri D. J. , Baer M.
Published: January 2006

In this article we present the first ab initio study of the conical intersections (cis) and their electronic nonadiabatic coupling terms (NACTs) for the {N,H2} system. Efforts were made to reveal the location of cis between the two lower, 1A′2 and 2A′2 states—to be designated as (1,2) cis—and the cis between the two upper, 2A′2 and 3A′2 states—to be designated as the (2,3) cis—of this system. We found that these cis are located along the collinear {NHH) arrangement. The study is carried out by analyzing two-state magnitudes such as the (1,2) and (2,3) adiabatic-to-diabatic transformation angles (known also as the mixing angles) and the corresponding topological phases (known also as the Berry phases or the Longuet-Higgins phases). In addition, a detailed three-state study is carried out. Here the emphasis is on driving the diagonal elements of the topological D matrix and analyzing situations for which the corresponding nonadiabatic coupling matrix is quantized. The reliability of two-state results is carefully examined by comparing them with corresponding outcomes derived for the three-state study. In addition we also calculated the potential-energy surfaces related to the two lower states and studied to what extent they are affected by the (1,2) ci. The results obtained in this treatment were found to be in full agreement with the NACT’s calculations.
Holographically generated twisted nematic liquid crystal gratings
Authors: Choi Hyunhee , Wu J. W. , Chang Hye Jeong , Park Byoungchoo
Published: January 2006

A reflection holographic method is introduced to fabricate an electro-optically tunable twisted nematic (TN) liquid crystal (LC) grating, forgoing the geometrical drawing. The photoisomerization process occurring on the LC alignment layers of an LC cell in the reflection holographic configuration gives a control over the twist angle, and the grating spacing is determined by the slant angle of reflection holographic configuration. The resulting diffraction grating is in a structure of a reverse TN LC, permitting a polarization-independent diffraction efficiency. The electro-optic tunability of the diffraction efficiency is also demonstrated.
Surface-enhanced Raman spectroscopy employing monodisperse nickel nanowire arrays
Authors: Sauer G. , Brehm G. , Schneider S. , Graener H. , Seifert G. , Nielsch K. , Choi J. , Göring P. , Gösele U. , Miclea P. , Wehrspohn R. B.
Published: January 2006

We have prepared two-dimensional arrays of hexagonally arranged, monodisperse nickel nanowires embedded in an alumina template. The degree of template filling is nearly 100% using an improved electrochemical deposition technique. Optical transmission measurements in the direction parallel to the long axis of the nickel nanowires show a plasmon-enhanced absorption around 400nm. We observe for typically surface-enhanced Raman spectroscopy (SERS) inactive metals like nickel a strong, but locally strongly inhomogeneous SERS signal during in situ Raman microspectroscopy. Supported by our numerical modeling, we suggest that significant SERS enhancement factors are possible only when nanowires in bundles are touching each other.
Surface termination and roughness of Ge(100) cleaned by HF and HCl solutions
Authors: Sun Shiyu , Sun Yun , Liu Zhi , Lee Dong-Ick , Peterson Samuel , Pianetta Piero
Published: January 2006

Oxide removal from Ge(100) surfaces treated by HCl and HF solutions with different concentrations are systematically studied by synchrotron radiation photoelectron spectroscopy (SR-PES). SR-PES results show that clean surfaces without any oxide can be obtained after wet chemical cleaning followed by vacuum annealing with a residual carbon contamination of less than 0.02 monolayer. HF etching leads to a hydrogen-terminated Ge surface whose hydrogen coverage is a function of the HF concentration. In contrast, HCl etching yields a chlorine-terminated surface. Possible etching mechanisms are discussed. Surface roughness after HF and HCl treatments is also investigated by atomic force microscopy which shows that HF treatment leaves a rougher surface than HCl.
Tight-binding modeling of thermoelectric properties of bismuth telluride
Authors: Lee Seungwon , von Allmen Paul
Published: January 2006

A parameterized orthogonal tight-binding model with sp3d5s* orbitals, nearest-neighbor interactions, and spin-orbit coupling is developed for bismuth telluride (Bi2Te3) and used to study its thermoelectric properties. Thermoelectric transport coefficients and figures of merit for n-doped and p-doped Bi2Te3 are calculated by solving Boltzmann’s transport equation within the constant-relaxation-time approximation. The dependence of the computed thermoelectric figure of merit on the electrical conductivity is in good agreement with experiment. The parameterized tight-binding model serves as a basis for studies of confined Bi2Te3 systems in search of enhanced thermoelectric properties.
Electron energy-loss spectrum imaging of high-k dielectric stacks
Authors: MacKenzie M. , Craven A. J. , Hamilton D. A. , McComb D. W.
Published: January 2006

Spectrum imaging combined with electron energy-loss spectroscopy is a powerful technique that can be used to examine the structural, chemical and electronic properties of materials on a subnanometer scale. We have applied this technique to investigations of high-k dielectric stacks and report results obtained from a HfO2∕HfSiO stack on Si. The results provide insight into the spatial distribution of the HfO2 and SiOx phases that result from decomposition of metastable “HfSiO.” Some of the HfO2 is observed to penetrate into the poly-Si gate electrode material.
Structure of Sc2O3 films epitaxially grown on α-Al2O3 (0001)
Authors: Kortan A. R. , Kopylov N. , Kwo J. , Hong M. , Chen C. P. , Mannaerts J. P. , Liou S. H.
Published: January 2006

The crystal structure of scandium oxide films epitaxially grown on α-Al2O3 (0001) under an ultrahigh-vacuum is studied by single-crystal x-ray diffraction. The Sc2O3 film grows in bixbyite phase on the basal (0001) surface of the sapphire substrate with its ⟨111⟩ axis aligned parallel to the substrate normal. In-plane orientation of the film, however, exhibits two distinct growth directions that are defined by the two possible surface orientations of the stepped α-Al2O3 substrate. The atomic structure of the high-quality epitaxial film is fully relaxed and the film has unusual thickness uniformity.
Relative phase tuning of coupled defects in photonic crystal vertical-cavity surface-emitting lasers
Authors: Lehman Ann C. , Raftery James J. , Danner Aaron J. , Leisher Paul O. , Choquette Kent D.
Published: January 2006

Evanescent coupling can be achieved by patterning the top facet of a vertical-cavity surface-emitting laser (VCSEL) with a multiple defect photonic crystal pattern. We show that for 2×1 coupled defect arrays, the phase between these emission sites changes as the current is varied. The phase variation is manifest in the far field pattern and may be determined using antenna array theory. It is found that the phase varies 81 deg between transversely coupled cavities as the current to the VCSEL is varied by 24 mA. This corresponds to a far field angular change of approximately 1.5 deg.
Simulation of picloram, atrazine, and simazine transport through two New Zealand soils using LEACHM
Authors: Close M. E. , Watt J. P. C. , Vincent K. W.
Published: January 2006

Picloram, atrazine, simazine, and bromide were applied to 2 sites, a Twyford
fine sandy loam and a Te Awa silt loam, located in Hawkes Bay, New Zealand,
and monitored at approximately monthly intervals using suction cup samplers
for 1200 and 800 days, respectively. Simulations using LEACHM, in combination
with the PEST nonlinear optimisation package, were used to estimate soil
sorption coefficients and degradation rates. Six different methods were used
to estimate Campbell’s a and
b coefficients for the water retention curve, and
results indicated that solute transport simulations were relatively
insensitive to the estimation method. There were indications that preferential
flow had occurred at both sites.
The Koc values for picloram at both sites were greater than the ‘best
available’ value given by Wauchope et al. (1992),
indicating less mobility, but the degradation rates were much lower at both
sites, particularly in the subsoil. The mobility for atrazine and simazine at
the Te Awa site was slightly greater than that indicated from the best
available values. The degradation rates were similar to the best available
values in the topsoil but the degradation rate for atrazine decreased in the
subsoil. The estimates from LEACHM were also compared with estimates using the
GLEAMS model.
Hydraulic conductivity in soils irrigated with wastewaters of differing strengths: Field and laboratory studies
Authors: Sparling G. P. , Williamson J. C. , Magesan G. N. , Schipper L. A. , Lloyd-Jones A. Rh.
Published: January 2006

Application of wastewater can decrease the hydraulic conductivity of soils,
and so reduce future loading rates. A possible mechanism for this decrease is
blockage of soil pores by microbial growth and extracellular carbohydrate
production. Our objective was to determine whether wastewater characteristics
that increased microbial biomass and carbohydrate also decreased soil
hydraulic conductivity. In field trials, irrigation of secondary-treated
wastewater for 7 years onto a sandy soil increased carbohydrate, but had no
effect on microbial C or unsaturated hydraulic conductivity, relative to
non-irrigated soil. Irrigation of tertiary-treated wastewater for 5 years onto
an allophanic soil had no significant effect on these soil characteristics.
Effects on soil properties of wastewater with differing carbon : nitrogen (C :
N) ratio were examined in the laboratory on repacked cores of the allophanic
soil over 14 weeks. Unsaturated hydraulic conductivity decreased significantly
in cores irrigated with the high C: N wastewater. These cores also exhibited
an increase in soil carbohydrate content, microbial biomass, and respiration
relative to cores irrigated with water. This study has demonstrated that the
land treatment of industrial wastewaters of high C: N ratio and high
biochemical oxygen demand could be problematic, even on freely draining soils.
Application of a physically based soil erosion model, GUEST, in the absence of data on runoff rates I. Theory and methodology
Authors: Yu B. , Rose C. W.
Published: January 2006

When physically based erosion models such as GUEST are used to determine soil
erodibility parameters or to predict the rate of soil loss, data on runoff
rates, as distinct from event runoff amount, are often needed. Data on runoff
rates, however, are not widely available. This paper describes methods that
can be used to overcome this lack of data on runoff rates. These methods
require only rainfall rates and runoff amounts, which are usually available
for sites set up primarily to test and validate the USLE technology. In
addition, the paper summarises the data requirements for the erosion model
GUEST and application procedures. In the accompanying paper, these methods are
applied to 4 experimental sites in the ASIALAND Network.
The influence of the soil matrix on nitrogen mineralisation and nitrification V. Microporosity and manganese
Authors: Strong D. T. , Sale P. W. G. , Helyar K. R.
Published: January 2006

Small soil cubes of dimensions 12 by 12 by 12 mm were collected from the
surface of a red earth. Treatments were addition of clover substrate or urea,
drying and rewetting, or no amendment, after which soils were incubated at
either –10 or –30 kPa. Each soil cube was analysed for
NO-3 -N,
NH+4 -N, total soil N (%N),
volumetric water content (θv), microporosity (volume of pores
<0·6 µm), and Mn 2+ concentration.
Multiple regression analysis was used to determine if microporosity and Mn
2+ contributed uniquely to linear models in which
%N and qv were also used to predict N
mineralisation and nitrification. In soils incubated at –10 kPa, both
microporosity and Mn 2+ had a strong positive
influence on N mineralisation and nitrification, whereas in soils incubated at
–30 kPa no such influence could be observed. These and other
observations suggest that when soils with high microporosity were incubated at
–10 kPa, O2 supply to the microbial biomass was
limited and the reduction of Mn oxides to divalent Mn was enhanced. Increased
substitution of Mn oxides for O2 as terminal electron
acceptors in the microbially mediated oxidation of carbon substrates
considerably increases H+ consumption. We propose that
in the wetter soil (–10 kPa), this process relieves pH stress
experienced by N mineralising and nitrifying organisms, thereby increasing
their activity, but that in the drier soil (–30 kPa),
O2 diffusion is less restricted and this mechanism does
not operate appreciably. The influence of microporosity on clover-amended
soils was to decrease levels of mineral N and this was attributed to greater
denitrification in soils with high microporosity. Neither microporosity nor
Mn2+ was an important variable in the prediction of
mineral N in the urea-treated soils. This work highlights the interaction of
physical, chemical, and biological components of the soil which give rise to
microbial microsites and diffusion gradients which are important determinants
of soil function.
Kinetics of nonexchangeable potassium release from a Tropaquept as influenced by long-term cropping, fertilisation, and manuring
Authors: Rao Ch. Srinivasa , Swarup Anand , Rao A. Subba , Gopal V. Raja
Published: January 2006

We studied the effect of long-term cropping, fertilisation, and manuring on
kinetics of nonexchangeable potassium (K) release from a Tropaquept in
0·01 M CaCl2 and 0·01 M citric acid media
under a rice–rice cropping system in an experiment started in 1971.
Under continuous cropping, the cumulative K release from the soil decreased
considerably in all treatments both with and without K application. The lowest
K release from the nonexchangeable fraction of the soil was observed in the
100% optimum nitrogen+phosphorus (NP) treatment (55 and 34
mg/kg in 1980 and 1994, respectively), while the highest K release was in
the 100% optimum NPK+farmyard manure (FYM) treatment (99 and 66
mg/kg in 1980 and 1994, respectively). Statistical analysis showed that a
parabolic diffusion equation best described the K release from soil samples
collected in 1980 (r =
0·989–0·992) and 1994 (r =
0·994–0·998), thereby indicating that the K release was a
diffusion-controlled exchange. A first-order kinetic equation also explained K
release behaviour from the soil samples in both years (r
= 0·988 for 1980 and 0·971–0·988 for 1994
samples). The maximum and minimum values of rate constants were found for the
100% NPK+FYM and 100% NP treatments, respectively. A
reduction in rate constants was observed with further cropping until 1994,
with or without K supply, with the largest reduction being observed in the
100% NP treatment. Kinetic parameters of the first-order equation
showed significant correlation with conventional measures of nonexchangeable K
forms: 3 M H2SO4 and boiling 1 M
HNO3 extractable K. From these results it is concluded
that continuous cropping without K inputs through fertilisers or manure caused
a decline in nonexchangeable K reserves and release rate while application of
recommended NPK plus FYM maintained higher release rates.
Soil indicators of pre-European seabird breeding in New Zealand at sites identified by predator deposits
Authors: Holdaway R. N. , Hawke D. J. , Causer J. E. , Ogden S.
Published: January 2006

Soil samples (0–15 cm) from 2 sites identified by palaeontological
methods as pre-European seabird breeding sites (Annandale, Ardenest) were
compared with a control site (Ngarua; no seabird breeding). All sites had
moderately calcareous soils developed on limestone or marble. Breeding site
Kjeldahl nitrogen (range, 0·41–1·4% N) and total
phosphorus (range, 1780–5285 mg/kg P) were comparable to present-day
breeding sites and higher than the control (mean, 0·20% N, 520
mg/kg P). Total cadmium (Cd) results followed the same pattern, with
results from Ardenest (mean, 0·49 mg/kg) and Annandale (0·47
mg/kg) being similar to fertilised New Zealand pastoral soils.
Contributions from extensive pre-European seabird breeding may therefore match
superphosphate fertiliser as a Cd source. Results for
δ15N and C: N were consistent with seabird
breeding at both sites (Ardenest, δ15N =
8·4 , C:N = 10·6 g C/g N; Annandale,
δ15N = 6·9 , C: N =
10·6). Results for δ13C were consistent
with seabird breeding at Ardenest (δ13C =
–22–8 ) but not at Annandale (δ13C
= –27·0 ), indicating dilution by organic matter derived
from C3 plants at Annandale. The Cd : P ratio was
significantly lower (P = 0·05) at each of
the seabird breeding sites (Annandale, 6·5 ± 1·5 x
10-5 mol Cd/mol P; Ardenest, 2·5 ±
0·7 x 10-5) than the control (mean 10·0
± 1·6 x 10-5). This ratio has the
potential to complement δ15N,
δ13C, and C: N in identifying and mapping
pre-European seabird breeding sites, although more study is required.
Dissolution of phosphate rock fertilisers in some soils of Okinawa, Japan
Authors: Dodor Daniel E. , Tokashiki Yoshihiro , Oya Kazuhiro , Shimo Moritaka
Published: January 2006

The ability of phosphate rock (PR) to dissolve rapidly in soil is a primary
concern in its direct application as P fertiliser. The dissolution of 4 PR
materials (Togo, South Africa, Florida, Morocco PRs) in 15 soil samples in
Okinawa was investigated in a closed-incubation system for 7 days. The
fertilisers were mixed with the soils at rates of addition of 600–1200
µg Ca/g soil. The extent and rate of dissolution of the PRs were
determined by measuring the increase in extractable Ca of the fertilised soils
compared with unfertilised soils, i.e. the delta Ca (ΔCa) technique.
Generally, the amounts of dissolution of 3 of the PRs were very low (mean
6·7% for Togo PR, 13·6% for South Africa PR, and
20·8% for Florida PR). However, Morocco PR dissolved to an
appreciable extent (mean 60·8%), suggesting that it can be an
alternative P source, especially in the red and yellow soils of Okinawa. Soil
properties identified as affecting dissolution were different for the
different PRs. In order to predict the suitability of Morocco PR for Okinawan
soils, the extent of its dissolution was related to soil properties in a
multiple regression analysis. Results indicated that the best regression model
for predicting the amount of dissolution was the combination of pH, Ca
saturation, and Truog P (r2
= 0·55**). Measured values of percentage
dissolution of Morocco PR were significantly correlated with calculated
percentages (r =
0·844***), indicating that the equation obtained
could offer a rapid estimation of amount of dissolution of Morocco PR in
Okinawan soils.
Dispersed clay and organic matter in soil: their nature and associations
Authors: Nelson P. N. , Baldock . A. , Oades J. M. , Churchman G. J. , Clarke P.
Published: January 2006

Clay dispersion in soil results in structural instability and management
problems. The aim of this study was to determine whether or not the easily
dispersed colloidal materials differ in their properties from colloidal
materials that do not disperse easily. Soil samples from the topsoil of sodic
and non-sodic variants of an Alfisol under irrigated pasture (Kyabram,
Victoria, Australia), and from the topsoil and subsoil of a sodic Alfisol
under cultivation (Two Wells, South Australia) were fractionated into easily
dispersed, moderately dispersed, and difficult to disperse clay, and silt,
sand, and light fractions. As a proportion of total clay, easily dispersed
clay content was greatest in the subsoil, and least in the Kyabram topsoils.
In the topsoils, easily dispersed clay had larger particle size and lower
cation exchange capacity than difficult to disperse clay, suggesting that high
surface area and charge lead to increased inter-particle interactions and
lower dispersibility. Easily dispersed clay had lower organic C contents than
difficult to disperse clay. Organic matter was examined by
13C nuclear magnetic resonance, and the spectra were
interpreted using major groups of biomolecules as model components. In all
soils, organic matter in the easily dispersed clay fraction contained a high
proportion of amino acids, suggesting that amino acids or proteins acted as
dispersants. Difficult to disperse clay contained a high proportion of
aliphatic materials in the topsoils, and carbohydrate in the subsoil,
suggesting that these materials acted as water-stable glues. Selectivity for
Na (KG) was negatively correlated
with organic C content in the clay fractions. In the Kyabram soils,
KG was greater in easily dispersed
clay than in difficult to disperse clay. In Two Wells soil, clay with high
KG appeared to have already moved
out of the topsoil, into the subsoil. This work showed that variability in the
nature of organic matter and clay particles has an important influence on clay
dispersion in sodic and non-sodic soils.
Fertilisers and phosphorus loss from productive grazing systems
Authors: Nash David M. , Halliwell David J.
Published: January 2006

This paper reviews phosphorus loss from productive high rainfall grazing
systems. In particular it describes the processes occurring when phosphatic
fertilisers are added to soil, the different pathways through which fertiliser
and other nutrient sources may contribute to phosphorus losses, and an
evaluation of the management strategies aimed at minimising phosphorus loss.
It is now generally accepted that soil is not an endless sink for phosphorus
uptake and that at the landscape scale the highest concentrations of
phosphorus loss occur in surface runoff, followed by macropore flow and
vertical matrix flow. However, loads of phosphorus lost through these pathways
are unknown. The development of an understanding of the transport mechanisms
and phosphorus species being transported is fundamental to developing
management strategies that are effective in decreasing phosphorus losses from
grazing systems.
Nitrogen dynamics in a eucalypt plantation irrigated with sewage effluent or bore water
Authors: Smith C. J. , Snow V. O. , Polglase P. J. , Probert M. E.
Published: January 2006

Irrigation of treated effluent onto tree plantations is a popular method of
land treatment but can lead to unacceptable levels of groundwater degradation.
Knowledge of nitrogen transformations and balances is essential to design and
operate plantations so as to keep groundwater degradation within acceptable
limits. APSIM for Effluent, a model of water, salt, and nitrogen in
effluent-irrigated plantations was tested against data from a plantation of
Eucalyptus grandis (flooded gum) irrigated with either
secondary-treated sewage effluent or bore water. APSIM was then used for
quantifying nitrogen transformations, leaching, and balance, within the
plantation.
Summed over 5 years, the predicted nitrogen balance of the effluent-irrigated
treatment showed that the accumulation of nitrogen in the aboveground biomass
and litter (335 and 19 kg/ha) was significantly less than the amount of
nitrogen added in effluent (508 kg/ha). Denitrification at this site was
low, about 52 kg/ha over 5 years, because the soil was permeable and
unlikely to become anaerobic for substantial periods of time. After 5 years,
organic nitrogen decreased by 167 kg N/ha, and 269 kg N/ha was
leached.
In the trees irrigated with bore water, accumulation of nitrogen in the
biomass and litter (301 and 34 kg/ha) was not much less than for the
effluent-irrigated treatment and was considerably greater than the nitrogen
added in the bore water irrigation (14 kg/ha). After 5 years, the
predicted fluxes were 10 kg/ha denitrified, 389 kg/ha depleted from
soil organic matter, and about 58 kg/ha leached. About 75% of the
nitrogen leaching occurred in the first year of the experiment.
A simulation study of erosion in the Emerald Irrigation Area
Authors: Carroll C. , Connolly R. D. , Freebairn D. M. , Francis J. , Silburn D. M. , Simpson B.
Published: January 2006

Sedimentation in the drainage network of the Emerald Irrigation Area (near
Emerald, Queensland), as a result of erosion from irrigated farms, is a
serious problem. Deposited sediment changes the hydraulic characteristics of
the drains causing flooding and is difficult and expensive to remove. We used
the GLEAMS erosion model to simulate a range of management strategies aimed at
reducing sedimentation in the drains by reducing erosion at the bay/field
scale or retaining eroded sediment on-farm.
GLEAMS was set up and tested using data measured at the rainfall simulator (12
m2), furrow (0·2–0·3 ha), and bay
(20–30 ha) scales. Comparisons of measured with predicted sediment
transport indicated the model accurately reproduced effects of several
management treatments on sediment transport and the size distribution of
eroded sediment at the bay scale. To reproduce accurately size distribution of
eroded sediment, though, an important parameter, clay content of surface soil,
had to be substantially distorted from measured values. GLEAMS was used to
simulate sediment transport from a typical farm producing irrigated cotton.
Management strategies simulated included conventional (bare), stubble
retained, cover in the tail-drain, drip irrigation, and addition of a
silt-trap and storage.
The most effective management strategies for reducing erosion and sediment
transport at the bay scale were stubble retained and drip irrigation. Stubble
retained+drip irrigation almost eliminated sediment transport. Addition
of a silt-trap and storage with conventional management reduced sediment
transport off-farm by 45%. Use of a silt-trap with improved field
management further reduced sediment transport. Erosion and sediment transport
at the bay scale was sensitive to changes in the furrow/tail-drain layout.
Changes in the furrow/tail-drain layout from the original design should be
undertaken carefully so as not to increase sediment transport off-farm.
Soil acidification as influenced by crop rotations, stubble management, and application of nitrogenous fertiliser, Tarlee, South Australia
Authors: Xu R. K. , Coventry D. R. , Farhoodi A. , Schultz J. E.
Published: January 2006

Soil acidification, as influenced by N fertiliser, stubble management, and
crop rotations, was investigated using soil samples from a long-term rotation
trial at Tarlee, South Australia. With the effects of combination of treatment
inputs (wheat–lupin, stubble retention and N-fertiliser application),
the pHCa (0–10 cm depth) declined from the
starting value of 6.12 to 4.50 after a 14-year period. All of the treatments
caused the soil pH to decrease. The mean acidification rates for the period
1978–1992 varied from 0.5 to 2.22 kmol
H+/ha.year for different treatments. Although
the rainfall at Tarlee (483 mm) is not sufficient to cause regular drainage
events, it is likely that downward movement of
NO3– in the soil profile has
caused acidification in the surface soil. Also the retention of stubble caused
more acidification than where there was regular stubble burning or removal.
The acidification resulted in an increase in soil exchangeable Al and Mn and
extractable Al and Mn, and the decrease in soil exchangeable base cations. The
values for soluble Al (extracted in CaCl2) in 1992 were
1.58 and 2.45 mg/kg (0–10 cm depth) for the wheat–bean and
wheat–lupin rotations, but the percentage of Al in the ECEC was low. It
is not known whether this acidity has any impact on yields of field crops at
this stage. But with soluble Al and the percentage of Al in ECEC increasing,
it is possible that Al toxicity may occur in the high input-output cropping
soils in South Australia.
acidity, pH, aluminium, manganese.