bluuebunny/crossref_metadata_2025 huggingface dataset:
Major Effects of Sensory Experiences on the Neocortical Inhibitory Circuits
Authors: Jiao Yuanyuan , Zhang Chunzhao , Yanagawa Yuchio , Sun Qian-Quan
Published: August 2006

During postnatal development, sensory experiences play critical roles in the refinement of cortical connections. However, both the process of postnatal experience-dependent maturation of neocortical inhibitory networks and its underlying mechanisms remain elusive. Here, we examined the differential properties of intracortical inhibitory networks of layer IV in “sensory-spared” and “sensory-deprived” cortices of glutamate acid decarboxylase 67 (GAD67)–green fluorescent protein (GFP) (Δneo) and wild-type mouse. Our results showed that row D whisker trimming (WT) begun at postnatal day 7 (P7), but not after P15, induced a robust reduction of parvalbumin (PV) expression, measured by the PV/GFP ratio and PV cell densities, in the deprived barrels. WT also induced a robust reduction in the number of inhibitory perisomatic varicosities and synaptic GAD65/67 immunoreactivities in spiny neurons of the deprived barrels. Although the GAD65/67 expressions in interneurons were also downregulated in the deprived barrels, the GFP expression remained unchanged. Patch-clamp recording from spiny cells showed a 1.5-fold reduction of intracortical evoked IPSCs (eIPSCs) in deprived versus spared cortices. The reduction in eIPSCs occurred via changes in presynaptic properties and unitary IPSC amplitudes. Miniature IPSCs showed subtle but significant differences between the two experimental conditions. In addition, properties of the IPSCs in deprived barrels resemble those of IPSCs recorded in immature brains (P7). Together, these results suggest that the properties of local intracortical inhibitory networks are modified by sensory experiences. Perisomatic inhibition mediated by PV-positive basket cells is pruned by sensory deprivation.
Phenotype of Striatofugal Medium Spiny Neurons in Parkinsonian and Dyskinetic Nonhuman Primates: A Call for a Reappraisal of the Functional Organization of the Basal Ganglia
Authors: Nadjar Agnes , Brotchie Jonathan M. , Guigoni Celine , Li Qin , Zhou Shao-Bo , Wang Gui-Jie , Ravenscroft Paula , Georges François , Crossman Alan R. , Bezard Erwan
Published: August 2006

The classic view of anatomofunctional organization of the basal ganglia is that striatopallidal neurons of the “indirect” pathway express D2dopamine receptors and corelease enkephalin with GABA, whereas striatopallidal neurons of the “direct” pathway bear D1dopamine receptors and corelease dynorphin and substance P with GABA. Although many studies have investigated the pathophysiology of the basal ganglia after dopamine denervation and subsequent chronic levodopa (l-dopa) treatment, none has ever considered the possibility of plastic changes leading to profound reorganization and/or biochemical phenotype modifications of medium spiny neurons. Therefore, we studied the phenotype of striatal neurons in four groups of nonhuman primates, including the following: normal, parkinsonian, parkinsonian chronically treated withl-dopa without exhibiting dyskinesia, and parkinsonian chronically treated withl-dopa exhibiting overt dyskinesia. To identify striatal cells projecting to external (indirect) or internal (direct) segments of the globus pallidus, the retrograde tracer cholera toxin subunit B (CTb) was injected stereotaxically into the terminal areas. Using immunohistochemistry techniques, brain sections were double labeled for CTb and dopamine receptors, opioid peptides, or the substance P receptor (NK1). We also used HPLC-RIA to assess opioid levels throughout structures of the basal ganglia. Our results suggest that medium spiny neurons retain their phenotype because no variations were observed in any experimental condition. Therefore, it appears unlikely that dyskinesia is related to a phenotype modification of the striatal neurons. However, this study supports the concept of axonal collateralization of striatofugal cells that project to both globus pallidus pars externa and globus pallidus pars interna. Striatofugal pathways are not as segregated in the primate as previously considered.
The Chk1/Cdc25A Pathway as Activators of the Cell Cycle in Neuronal Death Induced by Camptothecin
Authors: Zhang Yi , Qu Dianbo , Morris Erick J. , O’Hare Michael J. , Callaghan Steven M. , Slack Ruth S. , Geller Herbert M. , Park David S.
Published: August 2006

Cell cycle regulators appear to play a paradoxical role in neuronal death. We have shown previously that cyclin-dependent kinases (CDKs), along with their downstream effectors, Rb (retinoblastoma) and E2F/DP1 (E2 promoter binding factor/deleted in polyposis 1), regulate neuronal death evoked by the DNA damaging agent camptothecin. However, the mechanism by which CDKs are activated in this model is unclear. The cell division cycle 25A (Cdc25A) phosphatase is a critical regulator of cell cycle CDKs in proliferating cells. In cortical neurons, we presently show that expression of Cdc25A promotes death even in the absence of DNA damage. Importantly, Cdc25A activity is rapidly increased during DNA damage treatment. Inhibition of Cdc25A blocks death and reduces cyclin D1-associated kinase activity and Rb phosphorylation. This indicates that endogenous Cdc25A activity is important for regulation of cell cycle-mediated neuronal death. We also examined how Cdc25A activity is regulated after DNA damage. Cultured embryonic cortical neurons have a significant basal activity of checkpoint kinase 1 (Chk1), a kinase that regulates cell cycle arrest. During camptothecin treatment of neurons, this activity is rapidly downregulated with a concomitant increase in Cdc25A activity. Importantly, expression of wild-type Chk1, but not kinase-dead Chk1, inhibits the camptothecin-induced increase in Cdc25A activity. In addition, Chk1 expression also promotes survival in the presence of the DNA-damaging agent. Together, our data suggest that a Chk1/Cdc25A activity participates in activation of a cell cycle pathway-mediated death signal in neurons. These data also define how a proliferative signal may be abnormally activated in a postmitotic environment.
The Calcium Channel α2δ-2 Subunit Partitions with CaV2.1 into Lipid Rafts in Cerebellum: Implications for Localization and Function
Authors: Davies Anthony , Douglas Leon , Hendrich Jan , Wratten Jack , Tran Van Minh Alexandra , Foucault Isabelle , Koch Dietlind , Pratt Wendy S. , Saibil Helen R. , Dolphin Annette C.
Published: August 2006

The accessory α2δ subunits of voltage-gated calcium channels are highly glycosylated transmembrane proteins that interact with calcium channel α1 subunits to enhance calcium currents. We compared the membrane localization and processing of native cerebellar α2δ-2 subunits with α2δ-2 stably expressed in tsA-201 cells. We identified that α2δ-2 is completely concentrated in cholesterol-rich microdomains (lipid rafts) in cerebellum, in which it substantially colocalizes with the calcium channel α1 subunit CaV2.1, although CaV2.1 is also present in the Triton X-100-soluble fraction. In tsA-201 cells, unlike cerebellum, α2δ-2 is not completely proteolytically processed into α2-2 and δ-2. However, this processing is more complete in the lipid raft fraction of tsA-201 cells, in which α2δ-2 also colocalizes with CaV2.1. Cholesterol depletion of intact cells disrupted their lipid rafts and enhanced CaV2.1/α2δ-2/β4 currents. Furthermore, α2δ-2 coimmunoprecipitates with lipid raft-associated proteins of the stomatin family. The apparent affinity of α2δ-2 for its ligand gabapentin is increased markedly in the cholesterol-rich microdomain fractions, in both cerebellum and the stable α2δ-2 cell line. In contrast, α2δ-2 containing a point mutation (R282A) has a much lower affinity for gabapentin, and this is not enhanced in the lipid raft fraction. This R282A mutant α2δ-2 shows reduced functionality in terms of enhancement of CaV2.1/β4 calcium currents, suggesting that the integrity of the gabapentin binding site may be important for normal functioning of α2δ-2. Together, these results indicate that both α2δ-2 and CaV2.1 are normally associated with cholesterol-rich microdomains, and this influences their functionality.
Axon Guidance by Diffusible Chemoattractants: A Gradient of Netrin Protein in the Developing Spinal Cord
Authors: Kennedy Timothy E. , Wang Hao , Marshall Wallace , Tessier-Lavigne Marc
Published: August 2006

Gradients of diffusible long-range attractant and repellent proteins have been proposed to guide growing axons during nervous system development, but such gradients have never been visualized directly. In the embryonic spinal cord, commissural axons pioneer a circumferential trajectory to the floor plate at the ventral midline directed by secreted proteins of the netrin family. In the embryonic chick spinal cordnetrin-1mRNA is expressed by floor plate cells andnetrin-2mRNA by neural epithelial cells. Antibodies to the two netrins reveal a gradient of netrin protein directly in the path of commissural axons. The netrin-1 gradient itself extends many cell diameters dorsal to the floor plate, the site ofnetrin-1expression. A similar distribution of netrin-1 protein has been detected in embryonic rat and mouse spinal cord. The detection of a gradient of netrin-1 protein supports the operation of long-range chemotropic mechanisms in the developing nervous system.
About the reliability of the Maximum Entropy Method in reconstructing electron density: the case of MgO
Authors: Merli Marcello , Pavese Alessandro
Published: August 2006

The reliability of the Maximum Entropy Method (MEM) to reconstruct finite temperature electron density (ED) is here discussed, investigating the case of periclase (MgO). A theoretical electron density has been generated by quantum mechanic calculations and folded with a function simulating atomic thermal motion, in order to produce a reference errorless ED [ρ(r)REF]. The Fourier coefficients of ρ(r)REF have been calculated, and used as “observed” diffraction intensities to reconstruct via MEM the original ED. The electron density attained by MEM [ρ(r)MEM] and ρ(r)REF have been compared with each other (pixel-by-pixel and critical points) to assess the ability of MEM to retrieve EDs, on the basis of a set of observed structure factors. We have carried out our study varying the number of observed structure factors [i.e. sin (θ)/λ cut-off], the nature of the prior-density [uniform density and procrystal-like model] and the way in which the prior-density is treated during MEM maximization [fixed or free to change]. We observe that (i) it is recommendable to use the prior-density as a start point only, and allow it to change during maximization; (ii) the closer is the prior-density to ρ(r)REF, the easier one attains by MEM a correct ED; (iii) if the prior-density is varied and a sufficient large number of observed structure factors used, then MEM tends to yield converging EDs, regardless of the prior-density chosen as a start point.
Deformed model sets and distorted Penrose tilings
Authors: Sing Bernd , Welberry T. Richard
Published: August 2006

In this article, we show how the mathematical concept of a deformed model set can be used to gain insight into the diffraction pattern of quasicrystalline structures. We explain what a deformed model set is, what its characteristic features are and how it relates to certain disorder phenomena in solids. We then apply this concept to distorted Penrose tilings, i.e., Penrose tilings where we apply size-effect-like distortions. While the size effect in crystals only operates on the diffuse scattering, there is also an intensity transfer on the Bragg peaks in distorted Penrose tilings. The persistence of pure point diffraction in distorted Penrose tilings can be explained by interpreting such tilings as deformed model sets.
Structural variations in the solid solution series of sodalite-type |(Eu
x
Ca2–x
)4(OH)8|[(Al2+x
Si1–x
)4O24]-SOD with 0 ≤ x ≤ 1, determined by X-ray powder diffraction and 27Al MAS NMR spectroscopy
Authors: Peters Lars , Knorr Karsten , Fechtelkord Michael , Appel Peter , Depmeier Wulf
Published: August 2006

The mineral bicchulite, |Ca8(OH)8|[Al8Si4O24]-SOD, has sodalite-(SOD)-type structure. It is one of the few minerals contradicting Loewenstein’s rule, as it contains twice as much Al as Si at the topologically unique tetrahedrally coordinated position, with both species being randomly distributed. The solid solution series |(EuxCa2–x
)4(OH)8|[(Al2+x
Si1–x
)4O24]-SOD with 0 ≤ x ≤ 1 and Δx = 0.125, was synthesized in order to clarify, whether the continuous violation of Loewenstein's rule is possible in an aluminosilicate framework structure like SOD, or whether the reported examples of SOD-type compounds with an Al : Si-stoichiometry of 2 : 1 represent a preferred composition on the tetrahedrally coordinated site of the structure. Here, we report on the variation of the lattice parameter and of some structural parameters in the series, determined by X-ray powder diffraction and results of 27Al MAS NMR spectroscopy. We found Loewenstein's rule to be systematically and continuously violated in this series. The observed structural variations mainly reflect stronger electrostatic interactions between the cage cations and the sodalite framework with increasing (Al + Eu)-content. While the evaluation of the X-ray diffraction data indicate a global adaptation of the sodalite framework to the cage guest size, the significant line-broadening of the NMR spectra with increasing (Al + Eu)-content points towards local adaptations of the framework to the shape of the cage guests.
New isostructural ethylenediammonium diphosphates (NH3(CH2)2NH3)2[Me(HP2O7)2 · 2 H2O] [Me = Co, Ni]: X-ray crystal structure and vibrational spectroscopy
Authors: Capitelli Francesco , El Bali Brahim , Essehli Rachid , Lachkar Mohammed , Valentini Veronica , Mattei Giorgio , Taraba Jan , Zak Zdirak
Published: August 2006

New ethylenediammonium diphosphates (NH3(CH2)2NH3)2[Me(HP2O7)2 · 2 H2O] [Me = Co (1), Ni (2)] have been synthesized and investigated by single-crystal X-ray diffractometry. The two structures resulted to be isostructural within triclinic space group P-1. The unit-cell parameters are: a = 7.5211(6) Å, b = 7.5574(3) Å, c = 9.7689(7) Å, α = 103.6(1)°, β = 111.14(1)°, γ = 98.04(1)°, V = 486.9(1) Å3 (1) and a = 7.4631(15) Å, b = 7.5274(12) Å, c = 9.743(3) Å, α = 104.28(2)°, β = 110.75(2)°, γ = 97.50(2)°, V = 481.4(2) Å3 (2). The three-dimensional network is built up by discrete Me(HP2O7)2 · 2 H2O moieties, which, via strong O—H … O bonds, form layers parallel to ab plane. Ethylenediammonium groups are located between such layers, stabilizing the framework via N—H … O bonds. The hydrogendiphosphate group presents bent eclipsed conformation, while the Me ion lies on inversion centre. The structural data, as the bent POP configuration, have been confirmed by the Raman and infrared spectra of the title compounds. In particular, the non-coincidence between the infrared and Raman bands supports the centrosymmetric structure of the investigated crystals.
Experimental charge density of an L-phenylalanine formic acid complex with a short hydrogen bond determined at 25 K
Authors: Mebs Stefan , Messerschmidt Marc , Luger Peter
Published: August 2006

The experimental charge density and related atomic and bond topological properties of an L-phenylalanine formic acid complex were derived from a high resolution X-ray data set (sin θ/λ = 1.18 Å–1/d = 0.42 Å) measured at 25 K. The complex consists of a zwitterionic and a cationic phenylalanine molecule with formate as counterion. Special focus was directed on the density distribution in the region of a strong O—H ·· O hydrogen bond (O ·· O = 2.491(1) Å) which is formed between the two phenylalanine units. The obtained results are compared with the 15 previously derived experimental amino acid charge density data, with various theoretical calculations at experimental geometries and with the complete set of topological descriptors based on ab initio calculations of the neutral forms of all 20 amino acids published recently in the literature. A comparison of all available data in this biologically important class of compounds gives an impression about the significance of the quantitative results from experimental and theoretical charge density determinations.
Structural repair of elevated Harrow Road (westbound), UK
Authors: Yeoell D. , Parasram T. , Hodgkinson B.
Published: August 2006

This paper provides a review of the structural problems regarding repair and refurbishment of the Elevated Harrow Road (westbound). The step-by-step approach taken to investigate the causes of the defects and for the development of the successful repair strategy is examined. The problems faced by the city council, consultant and contractor leading to the adopted solutions, culminated in the successful delivery of a complex repair to a concrete structure which supports one of the key highway routes out of central London.
Design and construction of two launched bridges
Authors: Beavor N. , Cai J.
Published: August 2006

The 194 m long A500 railway bridge and the 63 m long New Relley bridge are both steel concrete composite bridges constructed using longitudinal launching with the concrete deck slab cast prior to the launch. This paper describes the design and construction of the two bridges and contrasts the different launching techniques used. The reasons for launching as opposed to conventional crane erection are explained, as are the design and fabrication details required. Information is given on the contract and planning framework for both schemes. The A500 railway bridge, passing over a total of 14 overhead electrified tracks, is believed to be the first example in the UK of a major steel–concrete composite bridge launched with the concrete deck in place. Both launches were successfully completed within tight railway possession periods. The safety advantages of having the permanent vehicle parapets in place directly after the deck installation are emphasised. This form of construction has proved itself to be effective for road-over-rail bridges where only short track possession periods are available and also where headroom constraints hinder normal crane operations.
Load-carrying capacity of flooded masonry arch bridges
Authors: Hulet K. M. , Smith C. C. , Gilbert M.
Published: August 2006

Many existing codes of practice for masonry arch bridge assessment fail to provide engineers with adequate guidance on the adverse effects that saturated environmental or flood conditions are likely to have on load-carrying capacity. Analysis indicates that the load-carrying capacity of a fully flooded arch bridge backfilled with cohesionless fill could typically be reduced by a factor of 1·6–1·8, or even more in specific circumstances. The significant influence of flooding on load-carrying capacity has now been verified using small-scale experiments which are described in the paper. The effects of flooding on waterproofed and unwaterproofed bridges are also analysed numerically and the circumstances under which capacity reductions are likely to be highest are identified. This paper should be useful to engineers dealing with bridges which are at risk of flooding.
Phosphorus Concentrations and Loads in Runoff Water under Crop Production
Authors: He Z. L. , Zhang M. K. , Stoffella P. J. , Yang X. E. , Banks D. J.
Published: August 2006

Transport of phosphorus (P) through surface runoff from agriculture is suspected to contribute to the eutrophication of surface waters in South Florida and elsewhere. There is minimal quantitative information on the concentrations and loads of various P forms in surface runoff water on a field‐scale. The objective of this study was to evaluate the annual loads of various P forms in runoff water from citrus and vegetable crop production systems in sandy soil regions in Florida and their relations to soil P status, fertilizer P input, and environmental conditions. Eleven field sites (four on vegetable farms and seven in citrus groves) were selected for this monitoring study over a 2‐yr period. The concentrations of total P (TP) in the runoff water samples varied widely from 0.01 to 22.74 mg L−1, with approximately half of the samples having the TP over 1 mg L−1 Eighty‐three percent of the samples had orthophosphate (PO4–P) higher than 0.02 mg L−1 The mean proportion of total dissolved P (TDP) in the TP was higher than that of the total particulate P (TPP). The TDP constituted the major proportion of P in runoff water from most of the sites. The PO4–P accounted for approximately 64% of the TDP. The annual median concentrations of various P forms in the runoff water varied spatially and temporally and were correlated with total and labile P in the soils (water‐P, Olsen‐P, Mehlich 1‐P, and Mehlich 3‐P) as well as fertilizer P rate. The vegetable farms had higher concentrations of P in the runoff water than citrus groves due to their more severe soil erosion and higher fertilizer P input, which resulted in higher soil P accumulation and availability. The annual loads of TP, TDP, and PO4–P varied among the field sites and between the 2 yr. The TP loads were significantly correlated with soil labile P estimated by the four extraction procedures, but the Olsen‐P was best related to runoff P. Runoff P concentrations and the annual discharge rate accounted for 55 to 64% of the variance in the annual P loads. These results indicate that P transport through surface runoff from agriculture is affected by soil P status and water management, and merits attention in the development of best management practices.
Gypsum Amendment and Exchangeable Calcium and Magnesium Affecting Phosphorus and Nitrogen in Runoff
Authors: Favaretto N. , Norton L. D. , Joern B. C. , Brouder S. M.
Published: August 2006

Loss of N and P from soil to water is not only an agronomic but also an environmental and human health problem. The main objective of this study was to evaluate the effect of gypsum amendment and soil‐exchangeable Ca and Mg on the concentration and loss of nutrients in runoff, sediment, and soil. The experiment was performed in the laboratory using a programmable rainfall simulator and erosion pans. The soil was a Miami silt loam, and treatments were (i) gypsum amendment, (ii) five target exchangeable Ca/Mg ratios, and (iii) a control. Nitrogen, P, and K were applied in all treatments based on soil test results and standard recommendations for corn (Zea mays L.). The fertilizers were mixed to a 2.5‐cm depth before pre‐wetting the soil. Gypsum was applied to the surface just before the rain. Two rainfall intensities (30 and 60 mm h−1) were simulated, and infiltrated water and runoff samples were taken every 5 min over 2 h. Nitrate N, NH4–N, and P in runoff, sediment, and soil were determined. The results showed that gypsum, as compared with the control, significantly decreased the mass loss in runoff of dissolved reactive P (DRP), total P (TP), soluble NH4–N, and total N by 85, 60, 80, and 59%, respectively. The concentration of these constituents was also significantly decreased by 83, 52, 79, and 50%, respectively. Nitrate N concentration in runoff was not decreased by gypsum. Gypsum also affected sediment and soil water–extractable P. The only significant effect of exchangeable Ca/Mg ratios was observed in the sediment water–extractable P, where Ca‐treated soil decreased by 50% the concentration of P compared with Mg‐treated soil. The results of this study demonstrated the potential of gypsum to decrease transport of total N and total P in runoff and the importance of Ca in the soil solution to decrease P solubility.
Release Behavior of Copper and Zinc from Sandy Soils
Authors: He Z. L. , Zhang M. , Yang X. E. , Stoffella P. J.
Published: August 2006

Copper (Cu) and zinc (Zn) transport after agricultural applications have accumulated in the sediments and are suspected to affect fish health in the Indian River Lagoon and St. Lucie Estuary, South Florida. Minimal information is available on the release of soil Cu and Zn to water and its relation to their concentrations and physicochemical forms in the soils. Sandy soil samples (n = 13) with a wide range of total Cu and Zn content were collected from forestland and commercial citrus groves in the Indian River area, Florida. The soils were subjected to column leaching and batch extractions to understand the release behavior of Cu and Zn as affected by soil‐water contact time, soil/water ratio, pH, and electrolyte concentration and cations. Copper released in batch extractions that simulated long‐term leaching was primarily from exchangeable and carbonate‐bound fractions, whereas Zn was primarily from the carbonate‐bound fraction. The Cu and Zn released from the column represented short‐term leaching and were primarily from their exchangeable fractions. Leached Zn decreased linearly as the solution pH was raised from 3.0 to 9.0. Leached Cu was at a minimum at pH 5 to 7 and increased at higher or lower pH beyond that range. These results indicate that long‐term saturated conditions after precipitation enhanced Cu and Zn release to water from the sandy soils. The released Cu decreased with increasing Ca concentration but increased with sodium (Na) concentration in the soil solution because of their differential effects on soil colloids, especially organic matter (flocculated by Ca2+ and dispersed by Na+) because organically bound Cu is the dominant fraction in the soils. Increasing Ca, K, Na, or NH4+ concentration generally increased Zn release through cation exchange. These findings merit attention in the development of best management practices to reduce transport of heavy metals from land to water.
Management of Irrigation with Saline Water in Cracking Clay Soils
Authors: Crescimanno Giuseppina , Garofalo Paolo
Published: August 2006

Management scenarios aimed at optimizing irrigation in a Sicilian vineyard characterized by a cracking clay soil irrigated with saline water were explored for seven soil profiles (Baglio 1–Baglio 7), by using the simulation model soil‐water‐atmosphere‐plant environment (SWAP), which accounts for shrinkage and cracking. Accurate prediction of water content, θ, was obtained for the seven profiles by expressing the soil hydraulic properties according to the Brutsaert retention equation coupled with the hydraulic conductivity model proposed by Gardner (B‐G model). A satisfactory prediction of the electrical conductivity of saturated extract (ECsat) was obtained using for the dispersivity (Ldis), a calibration value of 20 cm. Different irrigation schedulings and alternating waters of different quality were then explored as viable management options. The results showed that bypass flow determined a favorable water distribution, and that the best irrigation strategy was to make a minimum number of irrigations, by maximizing at the same time the amount of water supplied at each irrigation. Water storage in cracks was found to promote salt‐leaching; neglecting cracks and bypass flow was shown to overestimate salinization. Alternating two different irrigation waters proved to be the best strategy, which could be adopted to reduce soil salinization and enhance crop transpiration. Findings concerning the role of cracks in the process of salt‐leaching suggested that, under field conditions, application of a leaching solution was more efficient if the soil presented a considerable degree of cracking.
Soil Properties and Carbon Sequestration of Afforested Pastures in Reclaimed Minesoils of Ohio
Authors: Ussiri D. A. N. , Lal R. , Jacinthe P. A.
Published: August 2006

Land‐use change affects many soil properties, including soil organic carbon (SOC) pool, and the transfer of atmospheric CO2 to terrestrial landscapes. The objective of this study was to evaluate the effects of converting pastureland to Australian pine (Casuarina spp) and Black locust (Robinia pseudoacacia L) forest on selected soil physical and chemical properties and SOC sequestration in reclaimed minesoils (RMS) of southeastern Ohio. The study sites were surface mined for coal, reclaimed and managed as pasture, and then converted into woodland 10 yr before the present study. Soil pH and electrical conductivity (EC) were higher in the RMS than in a nearby undisturbed hardwood forest. Conversion to Australian pine decreased soil pH and EC in the top 20 cm. Bulk densities of the RMS ranged from 1.24 to 1.82 Mg m−3, and only minor changes were observed in soil bulk density after land‐use conversion. Mean weight diameter (MWD) and root biomass increased significantly (P < 0.05) with conversion of pasture to Australian pine or Black locust. In addition, aggregate stability was greater in RMS under hardwood forest than under pasture. Conversion to the Australian pine forest increased the SOC pool in the top 50 cm by 6 Mg ha−1 (11%) in 10 yr. However, the N pool in the top 50 cm was not affected by the land‐use conversion from pasture to Australian pine. Conversion to Black locust increased the SOC pool in the top 50 cm by 24 Mg ha−1 (42%), while the N pool increased by 10% under Black locust in 10 yr. The increase in the SOC pool was accompanied by an increase in the C/N ratios and root biomass in both Australian pine and Black locust sites in the 20‐ to 50‐cm depth. Establishment of tree plantation has a greater potential for SOC sequestration than pastures in the RMS.
Black Carbon Increases Cation Exchange Capacity in Soils
Authors: Liang B. , Lehmann J. , Solomon D. , Kinyangi J. , Grossman J. , O'Neill B. , Skjemstad J. O. , Thies J. , Luizão F. J. , Petersen J. , Neves E. G.
Published: August 2006

Black Carbon (BC) may significantly affect nutrient retention and play a key role in a wide range of biogeochemical processes in soils, especially for nutrient cycling. Anthrosols from the Brazilian Amazon (ages between 600 and 8700 yr BP) with high contents of biomass‐derived BC had greater potential cation exchange capacity (CEC measured at pH 7) per unit organic C than adjacent soils with low BC contents. Synchrotron‐based near edge X‐ray absorption fine structure (NEXAFS) spectroscopy coupled with scanning transmission X‐ray microscopy (STXM) techniques explained the source of the higher surface charge of BC compared with non‐BC by mapping cross‐sectional areas of BC particles with diameters of 10 to 50 μm for C forms. The largest cross‐sectional areas consisted of highly aromatic or only slightly oxidized organic C most likely originating from the BC itself with a characteristic peak at 286.1 eV, which could not be found in humic substance extracts, bacteria or fungi. Oxidation significantly increased from the core of BC particles to their surfaces as shown by the ratio of carboxyl‐C/aromatic‐C. Spotted and non‐continuous distribution patterns of highly oxidized C functional groups with distinctly different chemical signatures on BC particle surfaces (peak shift at 286.1 eV to a higher energy of 286.7 eV) indicated that non‐BC may be adsorbed on the surfaces of BC particles creating highly oxidized surface. As a consequence of both oxidation of the BC particles themselves and adsorption of organic matter to BC surfaces, the charge density (potential CEC per unit surface area) was greater in BC‐rich Anthrosols than adjacent soils. Additionally, a high specific surface area was attributable to the presence of BC, which may contribute to the high CEC found in soils that are rich in BC.
Phosphate Desorption from Goethite in the Presence of Galacturonate, Polygalacturonate, and Maize Mucigel (Zea maysL.)
Authors: Mikutta Christian , Neumann Günter , Lang Friederike
Published: August 2006

Uronates are important constituents of maize mucilage and polyuronates are used as a simplified model of the soil–root interface. We tested whether galacturonate (GA) and polygalacturonate (PGA) impair the diffusion of phosphate (PO4) into and out of pores of a synthetic goethite (147 m2g−1) and whether the effect of maize mucigel (MU) is comparable to PGA. We measured the PO4desorption kinetics of goethites in batch experiments over 2 wk at pH 5. One part of the goethite was equilibrated with organic substances before PO4addition, another part after addition of PO4Before the desorption experiments, the porosity of our samples was analyzed by N2gas adsorption. In each treatment a rapid initial desorption was followed by a slow desorption reaction, which is assigned to the diffusion of PO4out of mineral pores. No consistent relation between the micro‐ and mesoporosity and the rate of the slow PO4desorption was observed. Compared with the C‐free control, only PGA and MU affected the fraction of PO4mobilized by the fast and slow desorption reaction: when PGA was sorbed to goethite before PO4, twice as much PO4was mobilized via the fast reaction than in the treatment where PO4was sorbed before PGA, suggesting a decreased accessibility of goethite pores to PO4Mucigel, however, showed reversed effects, which is ascribed to its differing chemical composition. In conclusion, PGA seems inappropriate as a model substance for maize MU collected from non‐axenic sand cultures. Under the experimental conditions chosen, the efficacy of all organic substances to increase PO4solution concentrations by pore clogging and sorption competition is small.
Mapping of the Soil
Authors: Kushla John D.
Published: August 2006

Jean‐Paul Legros. Translator: V.A.K. Sarma. Science Publishers, P.O. Box 699, Enfield, New Hampshire 03748. 2006. p. 422. $75.00. ISBN 1–57808–363‐X.
Carbon and Nitrogen Storage are Greater under Biennial Tillage in a Minnesota Corn–Soybean Rotation
Authors: Venterea Rodney T. , Baker John M. , Dolan Michael S. , Spokas Kurt A.
Published: August 2006

Few studies have examined the impacts of rotational tillage regimes on soil carbon (C) and nitrogen (N). We measured the C and N content of soils managed under corn (Zea mays L.)–soybean (Glycine max L.) rotation following 10 and 15 yr of treatments. A conventional tillage (CT) regime employing moldboard and chisel plowing in alternate years was compared with both continuous no‐till (NT) and biennial tillage (BT), which employed chisel plowing before soybean only. While masses of C and N in the upper 0.3 m under both BT and NT were higher than CT, only the BT treatment differed from CT when the entire sampled depth (0.6 m) was considered. Decreased C inputs, as indicated by reduced grain yields, may have limited C storage in the NT system. Thus, while more C was apparently retained under NT per unit of C input, some tillage appears necessary in this climate and cropping system to maximize C storage. Soil carbon dioxide (CO2) fluxes under NT were greater than CT during a drier than normal year, suggesting that C storage may also be partly constrained under NT due to wetter conditions that promote increased soil respiration. Increased temperature sensitivity of soil respiration with increasing soil moisture was also observed. These findings indicate that long‐term biennial chisel plowing for corn–soybean in the upper mid‐west USA can enhance C storage, reduce tillage‐related fuel costs, and maintain yields compared with more intensive annual tillage.
Spectral and Chemical Characterization of Phosphates Associated with Humic Substances
Authors: He Zhongqi , Ohno Tsutomu , Cade-Menun Barbara J. , Erich M. Susan , Honeycutt C. Wayne
Published: August 2006

Because humic substances are involved in many processes in soils and natural waters, characterization of phosphorus (P) associated with humic substances may shed light on the function of natural organic matter in P cycling and nutrition. In this study, we investigated the spectral features and potential availability of P in the International Humic Substance Society (IHSS) Elliott Soil humic acid standard (EHa), Elliott soil fulvic acid standard II (EFa), Waskish peat humic acid reference (WHa), and Waskish peat fulvic acid reference (WFa) by fluorescence spectroscopy, Fourier‐transform infrared spectroscopy (FT‐IR), solution 31P nuclear magnetic resonance (NMR), 3‐phytase incubation, and UV irradiation. We observed more similar spectral features between EHa and EFa as well as between WHa and WFa than between the two humic acids or two fulvic acids themselves. Phosphorus in WHa and WFa was mainly present in the orthophosphate form. However, only about 5% was water soluble. After treatment by both UV irradiation and enzymatic hydrolysis, soluble orthophosphate increased to 17% of the P in WHa, and 10% of the P in WFa. Thus, it appears that a large portion of P in Waskish peat humic substances was not labile for plant uptake. On the other hand, both orthophosphate and organic phosphate were present in EHa and EFa. Treatment by both UV irradiation and enzymatic hydrolysis increased soluble orthophosphate to 67% of the P in EHa and 52% of the P in EFa, indicating that more P in Elliott soil humic substances was potentially bioavailable. Our results demonstrated that source (soil vs. peat) was a more important factor than organic matter fraction (humic acid vs. fulvic acid) with respect to the forms and lability of P in these humic substances. This work represents a much more complete characterization of humic substance‐bound P than previously reported in the literature, thus providing a comprehensive approach for improved understanding of P cycling in relation to ecosystem function.
Modeling the Transport and Retention of Arsenic (V) in Soils
Authors: Zhang Hua , Selim H. M.
Published: August 2006

Adsorption and transport of reactive solutes when nonequilibrium conditions are dominant may impact significantly their mobility in heterogeneous systems. In this study, arsenate [As(V)] sorption and transport in three soils having different properties were investigated. Kinetic batch experiments were performed to characterize arsenate [As(V)] adsorption over a wide range of concentrations. Adsorption of arsenate by all soils was strongly nonlinear and kinetic, where the rate of As(V) retention was rapid initially and was followed by gradual or somewhat slow retention behavior with increasing reaction time. Arsenic mobility in soils was investigated using the miscible displacement technique where uniformly packed soil columns under steady and water‐saturated flow were used. The column transport experiments indicated strong As(V) retardation followed by slow release or extensive tailing of the breakthrough curves (BTCs). Sharp decrease in As(V) concentration during flow interruption (no flow) further verified the extensive non‐equilibrium condition, which was likely due to the dominance of kinetic retention (sorption‐release) processes. We evaluated several formulations of a nonlinear equilibrium‐kinetic multireaction transport model (MRM) for its prediction capability of As(V) retention as well as transport in all soils. The asymmetrical and retarded BTCs for As(V) from our column experiments were well described using the MRM model. Nonlinear reversible along with a consecutive or concurrent irreversible reactions were the dominant mechanisms in the MRM model. The use of batch rate coefficients as model parameters for the predictions of As(V) BTCs underestimated the extent of retention and overestimated the extent of As(V) mobility for all soils. When utilized in an inverse mode, the MRM model provided good predictions of As(V) BTCs.
Agroforestry and Grass Buffer Influence on Macropore Characteristics
Authors: Udawatta Ranjith P. , Anderson Stephen H. , Gantzer Clark J. , Garrett Harold E.
Published: August 2006

Although agroforestry and grass filter strips have been identified as possible land management practices to reduce nonpoint‐source pollution from row‐crop agriculture, their effects on detailed soil pore characteristics are rare. The objective of this study was to compare the effects of agroforestry and grass buffers on computed tomography (CT)‐measured macropore (diam. > 1000 μm) and coarse mesopore (diam. 200–1000 μm) parameters and to examine relationships between CT‐measured pore parameters and saturated hydraulic conductivity (Ksat). Samples were collected from a no‐till corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotational watershed with pin oak (Quercus palustris Muenchch.) and cool season grass‐legume buffers established in 1997. Soils in the sampling region are mapped as Putnam silt loam (fine, smectitic, mesic Vertic Albaqualf). Undisturbed soil cores (76 by 76 mm) from tree buffer, grass buffer, and row crop areas were collected with six replicates. Five CT images were acquired from each soil core using a hospital CT scanner with 0.2 by 0.2 mm pixel resolution with 0.5‐mm slice thickness. Computed tomography images were compared by depth within and among treatments. Soil from the tree and grass buffer treatments had significantly (p ≤ 0.01) greater number of pores, number of macropores, area for the largest pore, macroporosity, mesoporosity and significantly lower circularity than soil from the row crop treatment. Soil under trees, grass, and crop areas on average had 207, 87, and 44 CT‐measured pores on a 3632 mm2 area, respectively. Soil under the trees had 2.5 and 3.6 times greater number of macropores than grass and crop areas, respectively. Computed tomography‐measured number of macropores explained 64% of the variation for Ksat Computed tomography‐measured parameters that were correlated with saturated hydraulic conductivity included macroporosity, mesoporosity, area of the largest pore, macropore circularity, and number of pores. Results showed that CT‐measured pore parameters can be used to predict saturated hydraulic conductivity as affected by land management practices. The study also showed that buffer practices improve soil pore parameters related to soil water infiltration.
Characterisation of the biosand filter for E. coli reductions from household drinking water under controlled laboratory and field use conditions
Authors: Stauber C.E. , Elliott M.A. , Koksal F. , Ortiz G.M. , DiGiano F.A. , Sobsey M.D.
Published: August 2006

More than a billion people in the developing world lack access to safe and reliable sources of drinking water. Point of use (POU) household water treatment technology allows people to improve the quality of their water by treating it in the home. One emerging POU technology is the biosand filter (BSF), a household-scale, intermittently operated slow sand filter. Laboratory and field studies examined Escherichia coli reductions achieved by the BSF. During two laboratory studies, mean E. coli reductions were 94% and they improved over the period of filter use, reaching a maximum of 99%. Field analysis conducted on 55 household filters near Bonao, Dominican Republic averaged E. coli reductions of 93%. E. coli reductions by the BSF in laboratory and field studies were less than those typically observed for traditional slow sand filters (SSFs), although as for SSFs microbial reductions improved over the period of filter use. Further study is needed to determine the factors contributing to microbial reductions in BSFs and why reductions are lower than those of conventional SSFs.
Does improved access to water supply by rural households enhance the concept of safe water at the point of use? A case study from deep rural South Africa
Authors: Jagals P.
Published: August 2006

The concept of safe water is defined by three principles: the health-related quality must be suitable, the supply/source must be accessible and the water must constantly be available in quantities sufficient for the intended use. If any one (or more) of these three elements is missing from a water services improvement programme, providing safe water is not successfully achieved. A study in a deep rural area in South Africa showed that providing small communities, using untreated river water as their only water source, with good quality water through a piped distribution system and accessible at communal taps did not fall within our parameters of safe water. The parameters for measuring the three principles were: absence of Escherichia coli in drinking water samples; accessibility by improving tap distances to within 200 m from each household; availability by assessing whether households have at least 25 L per person per day. Results show that although E. coli levels were reduced significantly, households were still consuming water with E. coli numbers at non-compliant levels. Access (distance) was improved from an average of 750 m from households to river source to an average of 120 m to new on-tap source points. This did not result in significant increases in household quantities, which on average remained around 18 L per person per day.
Accumulation of copper and silver onto cell body and its effect on the inactivation of Pseudomonas aeruginosa
Authors: Hwang M.G. , Katayama H. , Ohgaki S.
Published: August 2006

Pseudomonas aeruginosa, a gram-negative rod bacterium, is a causative agent of waterborne pneumonia and presents high tolerance against conventional disinfectants. The inorganic biocidal reagents, copper and silver, were applied to inactivate P. aeruginosa inoculated in a synthetic drinking water (SDW). Additionally, the relationship of the specific amount of accumulated copper and silver reagents (Cs) on P. aeruginosa with inactivation profile was elucidated in this study. Flow cytometry (FCM) following staining with SYTO 9 and PI was used for detection of bacterial viability and density. Individual copper and silver reagents, and their combination, exhibited excellent biocidal abilities even at the concentration of 0.05 mgCu/L and 0.005 mgAg/L. The critical amounts of accumulated disinfectant (Cs) were calculated at 2.82×10−7 μgCu/cellsi and 5.13×10−8 μgAg/cellsi at an incubation of 70 h. Consequently, the role of disinfectant on the inactivation of P. aeruginosa and the assessment of biocidal ability of copper, silver, and their combination were successfully explained by evaluating the terms Cs and Cc.
Combined use of microbiological and non-microbiological data to assess treatment efficacy
Authors: Smeets P.W.M.H. , Medema G.J.
Published: August 2006

The treatment efficacy for reducing Campylobacter concentrations by a drinking water treatment plant was assessed using a stochastic Monte Carlo model. The goal of the study was to reduce uncertainty of the results by combining microbiological and non-microbiological data in an advanced treatment assessment. Combining raw water Campylobacter and E. coli data reduced the uncertainty on raw water (peak) concentrations five-fold. Similar improvement was achieved for rapid sand filtration. Ozone disinfection was modelled based on ozone concentrations, contact time and temperature. Since this data was available, whereas most microbiological analyses at this point were negative, uncertainty was reduced three-fold. The slow sand filtration assessment could not be improved; however, since previous steps contained less uncertainty, this did not increase uncertainty by much. The study showed that using appropriate data for each treatment step can greatly reduce uncertainty in treatment assessment.