bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoelastic Analysis of the Influence of Platform Switching on Stress Distribution in Implants
Authors: Pellizzer Eduardo Piza , Falcón-Antenucci Rosse Mary , de Carvalho Paulo Sérgio Perri , Santiago Joel Ferreira , de Moraes Sandra Lúcia Dantas , de Carvalho Bruno Machado 
Published: June 2010

AbstractThe aim of this study was to evaluate the stress distribution of platform switching implants using a photoelastic method. Three models were constructed of the photoelastic resin PL-2, with a single implant and a screw-retained implant-supported prosthesis. These models were Model A, platform 5.0 mm/abutment 4.1 mm; Model B, platform 4.1 mm/abutment 4.1 mm; and Model C, platform 5.00 mm/abutment 5.00 mm. Axial and oblique (45°) loads of 100 N were applied using a Universal Testing Machine (EMIC DL 3000). Images were photographed with a digital camera and visualized with software (AdobePhotoshop) to facilitate the qualitative analysis. The highest stress concentrations were observed at the apical third of the 3 models. With the oblique load, the highest stress concentrations were located at the implant apex, opposite the load application. Stress concentrations decreased in the cervical region of Model A (platform switching), and Models A (platform switching) and C (conventional/wide-diameter) displayed similar stress magnitudes. Finally, Model B (conventional/regular diameter) displayed the highest stress concentrations of the models tested.
Comparison of Cellular Response to Anorganic Bone Matrix/Cell Binding Peptide and Allogenic Cranial Bone After Sinus Augmentation in Rhesus Monkeys
Authors: El-Madany Ihab , Emam Hany , Sharawy Mohamed 
Published: June 2010

AbstractThis study compared cellular responses of maxillary sinuses after augmentation with anorganic bovine-derived hydroxyapatite matrix linked to the cell binding polypeptide P-15 (ABM/P-15) or PepGen P-15 and allogenic freeze-dried cranial bone slabs. Five adult Macaque fascicularis monkeys were used. On one side, the floor of the sinus was augmented with ABM/P-15, while the other side was augmented with 2 cranial bone slabs. Trephine bone biopsies were obtained 6, 12, and 24 weeks postgrafting. Animals were sacrificed 8 months after grafting. Soft X-ray microradiography was used to determine bone density. The volume fraction (Vv) of regenerated bone, the number of mesenchymal cells, and the numbers of proliferating cell nuclear antigen (PCNA)- and alkaline phosphatase–positive cells at different augmentation sites were measured and compared. Basal bone heights were calculated at surgery and compared with total heights of the augmented sinus floors 8 months postgrafting. Bone formation, number of mesenchymal cells, PCNA index, and alkaline phosphatase index were significantly higher for the ABM/P-15 side than for the allogenic bone–augmented side. Both sides ended with a significant increase in bone height. The PCNA index decreased significantly over time (P &lt; .05), while the alkaline phosphatase index increased significantly (P &lt; .05) over time on both sides. Both graft materials have led to significant augmentation of the floor of the maxillary sinus with new bone; however, new bone formation and maturation were faster on the ABM/P-15 sites.
Methane Oxidation and Production Activity in Soils from Natural and Agricultural Ecosystems
Authors: Chan A.S.K. , Parkin T.B. 
Published: June 2010

ABSTRACTMethane (CH4) flux from soil to the atmosphere is the result of two microbial processes, methanogenesis and CH4oxidation. Land use may have a profound impact on the relative activities of these groups of organisms. In this study, the CH4production and consumption potentials of soils from agricultural and nonagricultural ecosystems were assessed in laboratory incubations. Methane production potentials of most soils were low and in the range of 0.02 to 0.35 nmol CH4g soil−1h−1; however, soils from two of the agricultural sites that experience periodic water saturation had CH4production potentials from 100 to 300 nmol CH4g soil−1h−1The high methanogenic potential suggests that CH4consumers may not be wholly dependent on atmospheric CH4for their survival and maintenance. The prairie soils exhibited the highest CH4oxidation under ambient atmospheric CH4concentrations, and CH4oxidation activity was markedly enhanced in incubations with an atmosphere enriched in CH4This stimulated CH4oxidation activity was generally greater in the agricultural soils as compared with the forest and prairie soils. Methane oxidation appeared to be related to soil nitrogen status. Under ambient atmospheric CH4concentrations, CH4oxidation was negatively related to soil mineral N NO−2+ NO−3+ NH+4concentration. However, a positive relationship between soil mineral N status and CH4oxidation activity was observed in incubations with atmospheres enriched in CH4This pattern suggests that the agricultural lands contain different populations of CH4oxidizers than the natural systems.
A Field Study of Virus Removal in Septic Tank Drainfields
Authors: Nicosia L.A. , Rose J.B. , Stark L. , Stewart M.T. 
Published: June 2010

ABSTRACTTwo field studies were conducted at a research station in Tampa, Florida to assess the removal of bacteriophage PRD1 from wastewater in septic tank drainfields. Infiltration cells were seeded with PRD1 and bromide and the effects of effluent hydraulic loading rate and rainfall on virus removal were monitored. Septic tank effluent samples were collected after passage through 0.6 m of unsaturated fine sand and PRD1 was detected over an average of 67 d. Bacteriophage PRD1 breakthrough was detected at approximately the same time as bromide in all three cells except for the low‐load cell (Study 1), where bromide was never detected. Log10 removals of PRD1 were 1.43 and 1.91 for the high‐load cells (hydraulic loading rate = 0.063 m/d) and 2.21 for the low‐load cell (hydraulic loading rate = 0.032 m/d). Virus attenuation is attributed to dispersion, dilution, and inactivation. Significant increases in PRD1 elution with rainfall were observed in the first 10 d of the study. Approximately 125 mm of rainfall caused a 1.2 log10 increase of PRD1 detected at the 0.6‐m depth. Current Florida on‐site wastewater disposal standards, which specify a 0.6‐m distance from the drainfield to the water table, may not provide sufficient removal of viruses, particularly during the wet season.
Hydrologic Response and Radionuclide Transport Following Fire at Semiarid Sites
Authors: Johansen Mathew P. , Hakonson Thomas E. , Whicker F. Ward , Simanton J. Roger , Stone Jeffery J. 
Published: June 2010

ABSTRACTInfrequent, high‐impact events such as wildfires, droughts, biological shifts, floods, and mechanical disturbances can greatly change land surfaces, including vegetative cover and soil characteristics, which in turn can trigger high rates of hydrologic erosion and associated transport of sediments and sediment‐sorbed contaminants. Where persistent soil contamination exists, infrequent mobilization of contaminants may dominate in determining long‐term risks to human and ecological receptors. Among these infrequent events, fire stands out as having the capacity to cause large increases in sediment transport. This study measured runoff, sediment yield, and mobility of sediment‐sorbed contamination (137Cs) on burned and unburned plots at the Waste Isolation Pilot Plant, New Mexico (WIPP), and the Rocky Flats Environmental Technology Site, Colorado (RFETS). Results showed that 137Cs transport from burned plots was up to 22 times greater than that from unburned plots at WIPP and 4 times greater at RFETS. Associated runoff was up to 12 times greater on burned plots at WIPP and sediment yields up to 6 times greater. Further, 137Cs concentrations in transported sediments were enriched compared with parent soils (expressed as enrichment ratio) by a factor of 2.3 at WIPP, and 1.3 at RFETS. However, enrichment ratios were not significantly different in sediments from burned and unburned plots. Our results provide new data on the effects of fire on the transport of sediment‐sorbed contaminants, and demonstrate that rare events such as fire can greatly increase contaminant mobility.
Fluorescence Analysis of a Standard Fulvic Acid and Tertiary Treated Wastewater
Authors: Westerhoff Paul , Chen Wen , Esparza Mario 
Published: June 2010

ABSTRACTFluorescence measurements (emission scan, synchronous scan, and excitation–emission matrix [EEM] scan) were used to compare characteristics of two sources of dissolved organic carbon (DOC) from distinctly different origins: (i) a standard fulvic acid from the Suwannee River (SRF sample) and (ii) an unfractionated DOC sample from a tertiary wastewater treatment plant (MWW sample). Two methods were demonstrated that quantitatively differentiated allochthonous DOC (e.g., SRF) from autochthonous DOC (e.g., MWW). The MWW sample exhibited fluorescence peaks undetected in the SRF sample, at shorter wavelength pairs (e.g., 220 nm:300 to 350 nm) than the dominant peaks in the SRF sample (e.g., 220 nm:450 nm). These peaks may be associated with base or neutral fractions, potentially enriched in organic nitrogen. Effects of DOC concentration and solution pH were discussed. A simple procedure was recommended (pH = 3; DOC = 1 mg/L; dilution with 0.01 M KCl) that minimizes the need to correct spectra for inner‐filter absorbance effects. A method, using synchronous fluorescence, to estimate the percentage of DOC from different sources when mixed together was also presented. Further work to understand the structural properties of DOC that fluoresce in wastewater samples, especially at shorter EEM wavelength pairs, will enable water managers to better understand the influence of wastewater on DOC in receiving waters (e.g., rivers, lakes).
Herbicide Banding and Tillage System Interactions on Runoff Losses of Alachlor and Cyanazine
Authors: Hansen N. C. , Moncrief J. F. , Gupta S. C. , Capel P. D. , Olness A. E. 
Published: June 2010

ABSTRACTHerbicides transported to surface waters by agricultural runoff are partitioned between solution and solid phases. Conservation tillage that reduces upland erosion will also reduce transport of herbicides associated with the solid phase. However, transport of many herbicides occurs predominantly in solution. Conservation tillage practices may or may not reduce transport of solution‐phase herbicides, as this depends on the runoff volume. Reducing herbicide application rate is another approach to minimize off‐site transport. Herbicide banding can reduce herbicide application rates and costs by one‐half or more. Our objective was to compare herbicide losses in runoff from different tillage practices and with band‐ or broadcast‐applied herbicides. The herbicides alachlor [2‐chloro‐2′,6′‐diethyl‐N‐(methoxymethyl)acetanilide] and cyanazine [2‐[[4‐chloro‐6‐(ethylamino)‐1,3,5‐triazin‐2‐yl]amino]2‐methylpropionitrile] were broadcast‐ or band‐applied to plots managed in a moldboard plow, chisel plow, or ridge till system. Herbicide concentration in runoff was largest for the first runoff event occurring after application and then decreased in subsequent events proportional to the cumulative rain since the herbicide application. When herbicides were broadcast‐applied, losses of alachlor and cyanazine in runoff followed the order: moldboard plow > chisel plow > ridge till. Conservation tillage systems reduced runoff loss of herbicides by reducing runoff volume and not the herbicide concentration in runoff. Herbicide banding reduced the concentration and loss of herbicides in runoff compared with the broadcast application. Herbicide losses in the water phase averaged 88 and 97% of the total loss for alachlor and cyanazine, respectively. Cyanazine was more persistent than alachlor in the soil.
Effects of Spent Mushroom Substrate Weathering on the Chemistry of Underlying Soils
Authors: Guo Mingxin , Chorover Jon , Fox Richard H. 
Published: June 2010

ABSTRACTPassive weathering of heaped material in the field is a popular method for treating spent mushroom substrate (SMS) before its reuse. During the weathering process, leachate containing high concentrations of dissolved organic matter and inorganic salts is released into the underlying soils, but effects on soil and ground water quality remain uncertain. We conducted a field study to measure the effects of SMS weathering on chemical and morphological properties of underlying soils. Two SMS piles, 20 m long, 6 m wide, and either 90 or 150 cm high, were placed in a fallow agricultural field dominated by grasses and weathered for 24 mo. Soil samples were taken from each genetic horizon under the SMS piles following their removal and analyzed for pH, total organic carbon (TOC), electrical conductivity (EC), water‐soluble organic carbon (WSOC), water‐soluble inorganic cations and anions, and exchangeable inorganic cations. Compared with an unaffected control, SMS weathering did not raise soil TOC, but did alter soil pH, and significantly increased EC, WSOC, and water‐soluble and exchangeable inorganic ions. At 200 cm below the soil surface, the EC, WSOC, and water‐soluble Cl−, NO−3, Ca2+, Mg2+, Na+, and K+ under SMS piles were 4 to 20 times higher than in unaffected soils. Water‐soluble NO−3 was minimal in the surface soil but peaked in the C horizon (120–180 cm) under the 90‐cm SMS pile, indicating that these soils may have little capacity for retaining NO−3 Concentration profiles of the different solutes reflect their relative mobilities in the soil environment and indicate the potential for effects on subsurface water supplies.
Effects of Sample Storage on Biosolids Compost Stability and Maturity Evaluation
Authors: Wu L. , Ma L. Q. 
Published: June 2010

ABSTRACTCompost stability and maturity are important parameters of compost quality. To date, nearly all compost characterization has been performed using samples freshly collected because sample storage can affect compost stability and maturity evaluation. However, sample preservation is sometimes necessary, especially for scientific research purposes. There is little information available on the effects of sample storage on compost stability and maturity. Samples of biosolids compost with different levels of stability and maturity were collected from four compost facilities in Florida (referred to as Register, Winslow, Sunset, and Meadow). Comparisons of CO2evolution, seed germination rate, and water‐soluble organic carbon (WSOC) were made between fresh samples with short storage at 4°C for less than 1 wk and air‐dried or frozen compost samples stored for 1 yr. The effects of storage (air‐dry or frozen) on the measured parameters depended on compost stability and maturity and on the compost material source. Frozen storage reduced the peak CO2evolution of Register samples by 12 to 29%, while accumulated CO2evolution was reduced by 43 to 64% and 110 to 277% with air‐dry and frozen storage, respectively. The storage effect on CO2evolution with more stable compost was inconsistent. Storage did not affect compost phytotoxicity, except for samples from the Sunset facility. Air‐drying reduced the WSOC by up to 35%, and freezing increased it by up to 34%, while both storage methods had no significant effect on samples of low WSOC. Despite all these variations, WSOC had a significant and consistent relation to CO2evolution and seed germination rates withR2of 0.78 and 0.57, respectively, regardless of storage methods.
Phosphorus Flux from Wetland Soils Affected by Long‐Term Nutrient Loading
Authors: Fisher M. M. , Reddy K. R. 
Published: June 2010

ABSTRACTWetland soils play a key role in the cycling of nutrients within an ecosystem. Since soils are potentially a source or a sink for inorganic nutrients, it is important to quantify their influence on overlying water quality in order to understand their importance in overall ecosystem nutrient budgets. Laboratory and field studies were performed in the northern Everglades (WCA‐2A) to determine the magnitude of phosphorus (P) flux between the soil and the overlying water column, under various redox conditions. The P flux was estimated using three techniques: intact soil cores, in situ benthic chambers, and porewater equilibrators. There was reasonable agreement between the P flux estimated using intact soil cores and benthic chambers; however, P flux estimates using the porewater equilibrators were considerably lower than the other two techniques. Models of solute flux, based solely on soil physico–chemical characteristics, may substantially underestimate soil–water nutrient exchange processes. Phosphorus flux measured with the intact soil cores varied from 6.5 mg m−2 d−1 near nutrient inflow areas to undetectable flux 4 km away from the inflow. Oxygen consumption varied from 4 mg m−2 d−1 near the inflow to a constant 1 to 2 mg m−2 d−1 at a distance of 4 km from the inflow. Rate of consumption of NO−3–N and SO2−4 showed no significant trend with respect to distance from inflow. Nitrate N and SO4 consumption rates averaged 120 and 130 mg m−2 d−1, respectively. Consumption of O2 was correlated with P flux, whereas NO−3–N and SO2−4 consumption were not.
Implementation of Sulfate Adsorption in the SAFE Model
Authors: Fumoto Tamon , Sverdrup Harald 
Published: June 2010

ABSTRACTAn SO2−4 adsorption submodel has been implemented in the dynamic soil chemistry model SAFE. The submodel calculates pH‐dependent SO2−4 and H+ adsorption to the soil, as well as the net surface charge development due to uneven adsorption of SO2−4 and H+, using the empirical equations derived from an electrostatic model (Extended Constant Capacitance Model, ECCM) of SO2−4 adsorption. The resulting new SAFE model was applied on a roof experiment plot in the Norway spruce [Picea abies (L.) H. Karst.] stand at Solling, Germany, where atmospheric S and N deposition was artificially reduced by the roof construction. The model performance was compared with the previous versions that used a pH‐independent Freudlich model of SO2−4 adsorption or assumed no SO2−4 adsorption. With the ECCM‐based SO2−4 adsorption submodel, SAFE simulated soil solution SO2−4 concentration and base saturation better, in comparison with measured data, than with the previous SO2−4 adsorption formulations. Through the model application, also, need of additional improvement was suggested, such as calibration of mass transfer coefficients.
Cupric Ion Activity in Peat Soil as a Toxicity Indicator for Maize
Authors: McBride M.B. 
Published: June 2010

ABSTRACTCopper phytotoxicity in soils is difficult to assess because Cu accumulates at and damages roots, and is not readily transferred to shoots. Soil chemical properties strongly influence Cu speciation, so that total soil Cu alone is not a broadly useful indicator of potential toxicity to plants. The present study measured free Cu2+ activity in Cu‐enriched peat soils using the ion selective electrode. The soil Cu2+ activity was related to the severity of phytotoxicity as measured by several indicators in a maize (Zea mays L.) bioassay, including leaf chlorosis, root stunting, and reduced shoot growth and Fe concentration. A soil Cu2+ activity of 10−7.0 to 10−7.5, corresponding to total Cu of about 275 mg/kg in the peat soil, caused phytotoxicity in maize seedlings. It is proposed that Cu2+ activity is more directly related to phytotoxic effects than other soil tests, such as extractions with strong acids or chelating agents, because it is the free Cu2+ in soil solution that has the most direct toxic effects on roots. There was very limited uptake of Cu into maize shoots, and even when Cu2+ activity and total soil Cu were raised into the extreme toxicity range of 10−5 and 4000 mg/kg, respectively, shoot Cu remained less than 35 mg/kg. These results indicate the inadequacy of the USEPA risk assessment of potential for Cu toxicity to crops amended with sewage sludge, which assumed a no‐effect level of maize shoot Cu of 40 mg/kg.
Nickel Increases Susceptibility of a Nickel Hyperaccumulator to Turnip mosaic virus
Authors: Davis Micheal A. , Murphy John F. , Boyd Robert S. 
Published: June 2010

ABSTRACTHyperaccumulated Ni can defend plant tissues against herbivores and pathogens. The effectiveness of this defense, however, has not been tested with a viral pathogen. Turnip mosaic virus (TuMV) accumulation was studied in two serpentine species of Streptanthus with different Ni uptake abilities. Plants of a Ni hyperaccumulator, milkwort jewelflower (S. polygaloides Gray), and a non‐hyperaccumulator, plumed jewelflower (S. insignis Jepson), were grown on Ni‐amended and unamended soils. Plants were inoculated with TuMV at three different phenological stages: basal rosette, bolting, and flowering. Susceptibility of experimental plants to TuMV was determined either by the magnitude of TuMV accumulation (measured by indirect enzyme‐linked immunosorbent assay [ELISA]) or by plant survival. Streptanthus polygaloides plants grown on high‐Ni soil were more susceptible to TuMV than low‐Ni S. polygaloides at all three phenological stages. All rosette and pre‐bolt S. insignis plants were infected by TuMV, but survival and TuMV accumulation were not significantly affected by soil Ni. At flowering, only high‐Ni S. polygaloides plants became infected. For S. polygaloides, elevated tissue Ni concentrations enhanced TuMV infection instead of defending plants from the virus. To reduce risks to nearby agricultural crops, future phytoremediation and phytomining operations using this species should incorporate management plans to prevent the creation of artificial reservoirs of TuMV inoculum.
Nitrate Nitrogen in Surface Waters as Influenced by Climatic Conditions and Agricultural Practices
Authors: Randall Gyles W. , Mulla David J. 
Published: June 2010

ABSTRACTSubsurface tile drainage from row‐crop agricultural production systems has been identified as a major source of nitrate entering surface waters in the Mississippi River basin. Noncontrollable factors such as precipitation and mineralization of soil organic matter have a tremendous effect on drainage losses, nitrate concentrations, and nitrate loadings in subsurface drainage water. Cropping system and nutrient management inputs are controllable factors that have a varying influence on nitrate losses. Row crops leak substantially greater amounts of nitrate compared with perennial crops; however, satisfactory economic return with many perennials is an obstacle at present. Improving N management by applying the correct rate of N at the optimum time and giving proper credits to previous legume crops and animal manure applications will also lead to reduced nitrate losses. Nitrate losses have been shown to be minimally affected by tillage systems compared with N management practices. Scientists and policymakers must understand these factors as they develop educational materials and environmental guidelines for reducing nitrate losses to surface waters.