bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant‐Available Zinc and Lead in Mine Spoils and Soils at the Mines of Spain, Iowa
Authors: Mbila Monday O. , Thompson Michael L. 
Published: July 2013

ABSTRACTTo investigate the forms of Zn and Pb and their plant availability in mine spoil long after its abandonment, we studied seven sites in the Mines of Spain, near Dubuque, IA. Ores of Zn and Pb were mined from dolomitic limestone primarily during the 19th century, and there had been no subsequent remediation of metals‐contaminated spoil. From both mine spoil and undisturbed areas, we collected root‐zone soil samples as well as samples of the dominant ground‐level, native plants, aniseroot [Osmorhiza longistylis (Torr.) DC.] and black snakeroot (Sanicular marilandica L.). We determined Zn and Pb concentrations in both the plant tissue and in the soil samples after strong‐acid digestion, and we fractionated the solid‐phase forms of Zn, Pb, and P in the soil samples by using sequential extraction. Concentrations of total Zn and Pb were 10‐ to 20‐fold greater in the spoil than in the undisturbed soils. Plants growing in the mine spoil had Zn concentrations two to four times greater and Pb concentrations more than 26 times greater than did plants growing in the undisturbed soils. The highest concentrations of Zn and Pb were in the CBD‐extractable and the residual fractions in both undisturbed and mine spoil samples. Although the mine spoil contained large amounts of P, Zn, and Pb were available for uptake by the two plant species in amounts proportional to Zn and Pb concentrations in the rooting zone.
Trophic Transition in a Lake on the Virginia Coastal Plain
Authors: Pensa Mellisa A. , Chambers Randolph M. 
Published: July 2013

ABSTRACTTo examine possible connections between lake trophic status and runoff from surrounding subwatersheds, we determined patterns of sediment and nutrient deposition in a hypereutrophic, 16‐ha impoundment on the Virginia coastal plain. Spatial survey of nutrients in surface sediments documented a strong correlation between total P and extractable Fe (r2 = 0.53). Elevated biogenic silica concentrations up to 0.25% by weight were measured in sections of the lake receiving perennial stream discharge. Sediment C to N ratios were >20 in those same sections, suggesting a large allochthonous contribution to organic matter deposition. Sediment cores 0.9 to 2.3 m in length, representing 70 years of deposition, were analyzed to develop vertical profiles of changes in sediment and nutrient deposition in deltas downstream from two more‐developed and three less‐developed subwatersheds (with 49 and 9% commercial and residential development, respectively). The average sediment weight percent ± standard deviation of biogenic silica (0.027 ± 0.037 vs. 0.009 ± 0.006%) and total P (0.040 ± 0.025 vs. 0.024 ± 0.019%) was significantly higher downstream of more‐developed subwatersheds. Using elevated P loadings and biogenic silica deposition as proxies for algal production, transition of the lake to its current hypereutrophic state appears to have occurred in the last 70 yr. Changes in trophic status as revealed by sediment analysis of this small lake on the Virginia coastal plain reflect a common pattern of eutrophication observed for the entire Chesapeake Bay drainage basin. Analysis of sediments from stream deltas appears to be a reasonable strategy for identifying and targeting subwatershed areas needing better management of nutrient runoff that otherwise would lead to eutrophication of downstream waters.
Phosphorus Leaching in Relation to Soil Type and Soil Phosphorus Content
Authors: Djodjic Faruk , Börling Katarina , Bergström Lars 
Published: July 2013

ABSTRACTPhosphorus losses from arable soils contribute to eutrophication of freshwater systems. In addition to losses through surface runoff, leaching has lately gained increased attention as an important P transport pathway. Increased P levels in arable soils have highlighted the necessity of establishing a relationship between actual P leaching and soil P levels. In this study, we measured leaching of total phosphorus (TP) and dissolved reactive phosphorus (DRP) during three years in undisturbed soil columns of five soils. The soils were collected at sites, established between 1957 and 1966, included in a long‐term Swedish fertility experiment with four P fertilization levels at each site. Total P losses varied between 0.03 and 1.09 kg ha−1yr−1, but no general correlation could be found between P concentrations and soil test P (Olsen P and phosphorus content in ammonium lactate extract [P‐AL]) or P sorption indices (single‐point phosphorus sorption index [PSI] and P sorption saturation) of the topsoil. Instead, water transport mechanism through the soil and subsoil properties seemed to be more important for P leaching than soil test P value in the topsoil. In one soil, where preferential flow was the dominant water transport pathway, water and P bypassed the high sorption capacity of the subsoil, resulting in high losses. On the other hand, P leaching from some soils was low in spite of high P applications due to high P sorption capacity in the subsoil. Therefore, site‐specific factors may serve as indicators for P leaching losses, but a single, general indicator for all soil types was not found in this study.
Comparison of Estimates of First‐Year Dairy Manure Nitrogen Availability or Recovery Using Nitrogen‐15 and Other Techniques
Authors: Muñoz G. R. , Kelling K. A. , Powell J. M. , Speth P. E. 
Published: July 2013

ABSTRACTMeasurements of dairy manure nutrient availability to crops typically show great variability. Approaches that are more accurate are needed to improve manure management and reduce nutrient loss to the environment. In this study, we compared direct (15N recovery) and indirect (difference method [Diff Meth] and fertilizer equivalence [FE] approach) methods of determining first‐year dairy manure N availability or recovery during three cropping seasons. A field experiment was conducted on a Plano silt loam (fine‐silty, mixed, superactive, mesic Typic Argiudolls) planted to corn (Zea maysL.). Plots received either manure, fertilizer N, or no N. Microplots receiving15N‐labeled manure were also established each study year. Manure was applied to a new plot each cropping season. Whole‐plant N uptake was the best crop parameter to use for FE estimates. Estimates of N availability by relative effectiveness (Rel Eff), which are derived from the Diff Meth, and FE were similar (32 and 41%, respectively) and higher than unlabeled N or15N recovery measurements because these indices factor in N use efficiency. Measures of the Rel Eff of manure N use were highly affected by control plot N uptake. The FE approach is less influenced by control plots, but it requires the inclusion of several more treatments and use of mathematical functions to describe crop response to N. These limitations are reflected in the wide ranges obtained for N availability estimates (−60 to 148%). Although apparent N recovery by the Diff Meth (14%) or direct measurements of15N recovery (16%) were close on average, variability tended to be much lower for the15N method. In addition, the Diff Meth was highly dependent on initial soil conditions. Use of15N‐labeled manure, although more costly and time‐consuming, provided more consistent and reliable results.
Fate of Phosphorus in Dairy Wastewater and Poultry Litter Applied on Grassland
Authors: Johnson A. F. , Vietor D. M. , Rouquette F. M. , Haby V. A. 
Published: July 2013

ABSTRACTLarge and repeated manure applications can exceed the P sorption capacity of soil and increase P leaching and losses through subsurface drainage. The objective of this study was to evaluate the fate of P applied with increasing N rates in dairy wastewater or poultry litter on grassland during a 4‐yr period. In addition to P recovery in forage, soil‐test phosphorus (STP) was monitored at depths to 180 cm in a Darco loamy sand (loamy, siliceous, semiactive, thermic Grossarenic Paleudults) twice annually. A split‐plot arrangement of a randomized complete block design comprised four annual N rates (0, 250, 500, and 1000 kg ha−1) for each nutrient source on coastal bermudagrass [Cynodon dactylon (L.) Pers.] over‐seeded with ryegrass (Lolium multiflorum L. cv. TAM90). Increasing annual rates of N and P in wastewater and poultry litter increased P removal in forage (P = 0.001). At the highest N rate of each nutrient source, less than 13% of applied P was recovered in forage. The highest N rates delivered 8 times more P in wastewater or 15 times more P in poultry litter than was removed in forage harvests during an average year. Compared with controls, annual P rates up to 188 kg ha−1 in dairy wastewater did not increase STP concentrations at depths below 30 cm. In contrast, the highest annual P rate (590 kg ha−1) in poultry litter increased STP above that of controls at depth intervals to 120 cm during the first year of sampling. Increases in STP at depths below 30 cm in the Darco soil were indicative of excessive P rates that could contribute to nonpoint‐source pollution in outflows from subsoil through subsurface drainage.
Bermudagrass Management in the Southern Piedmont, USA
Authors: Franzluebbers A. J. , Wilkinson S. R. , Stuedemann J. A. 
Published: July 2013

ABSTRACTAn understanding of the long‐term cycling of trace elements in soil with broiler litter fertilization under various forage utilization strategies is needed to develop sustainable agricultural production systems. We evaluated differences in Cu, Mn, Zn, and six other trace elements in response to 5 yr of bermudagrass [Cynodon dactylon (L.) Pers.] management varying in fertilization and harvest strategies on a Typic Kanhapludult in Georgia. Chicken (Gallus gallus) broiler litter was a significant source of trace elements that led to 3.4 ± 0.5 times higher Cu, 2.0 ± 0.3 times higher Mn, and 2.1 ± 0.2 times higher Zn in the surface 3 cm of soil than when forage was fertilized inorganically. There were variable effects of broiler litter fertilization on other trace elements, depending upon element, depth of sampling, and forage utilization strategy. Concentrations of all trace elements in soil were below levels considered toxic to plants. Soil at a depth of 0 to 3 cm under grazed paddocks had 33 ± 5% greater Cd, 18 ± 1% greater Cr, 53 ± 24% greater Cu, and 24 ± 7% greater Zn compared with unharvested and hayed management. Trace elements in soil were unaffected whether forage was unharvested or removed as hay. These results suggest that broiler litter is a significant source of several trace elements and that ruminant processing of forage and subsequent deposition of excreta on the paddock allow these trace elements to accumulate more at the soil surface where they might interact with the high concentration of organic matter.
Dental anomaly pattern (DAP): Agenesis of mandibular second premolar, distal angulation of its antimere and delayed tooth formation
Authors: Navarro Joana , Cavaller Maria , Luque Estela , Tobella Maria Luisa , Rivera Alejandro 
Published: July 2013

ABSTRACT

Objective:
To test the null hypotheses that children with unilateral agenesis of the mandibular second premolar (MnP2) do not show (1) greater distal angulation of the unerupted antimere and (2) delayed tooth formation compared with children without agenesis.

Materials and Methods:
Panoramic radiographs of 38 patients with unilateral aplasia of MnP2 were retrospectively examined and compared to a non-agenesic control group of 82 patients. Ages ranged from 8 to 15 years. Contralateral mandibular deciduous second molars were present for all participants. Each unerupted MnP2 was traced, and its developmental stage and angulation were recorded (measured with the distal angle and the premolar-molar angle). Dental age was evaluated using the Haavikko method. Student's t-test was performed to identify significant differences between the compared groups. The significance level for statistical testing was set at P &lt; .05.

Results:
The results indicated a 9.5° decrease in the distal angle and a 13.2° increase in the premolar-molar angle for the unerupted MnP2 in the agenesis sample. This was a highly statistically significant difference (P &lt; .001 and P &lt; .0001, respectively) compared with the MnP2 inclinations in the control sample. The delay in dental age was significantly greater in patients with agenesis (2.1 years) compared with the delay in the control group (1.5 years) (P &lt; .001).

Conclusion:
Both null hypotheses are rejected. The results of this study statistically support the hypothesis that aplasia of MnP2, distally displaced MnP2s, and delayed tooth formation are part of a genetically related pattern of dental anomalies.
Mini-implant stability at the initial healing period: A clinical pilot study
Authors: Nienkemper Manuel , Wilmes Benedict , Pauls Alexander , Drescher Dieter 
Published: July 2013

ABSTRACT

Objective:
To evaluate the changes of mini-implant stability over the initial healing period in humans.

Material and Methods:
A sample of 19 consecutively treated patients (mean age 15.5 ± 7.3 years) was examined. In each patient, a mini-implant of a size of 2 × 9 mm was inserted into the anterior palate. Implant stability was assessed using resonance frequency analysis (RFA) immediately after insertion (T0), 2 weeks later (T1), 4 weeks later (T2), and 6 weeks later (T3). Insertion depth (ID) and the maximum insertion torque (IT) were measured. Data were tested for correlations between RFA, ID, and IT. All RFA values were tested for statistically significant differences between the different times.

Results:
The mean ID was 7.5 ± 0.6 mm, and the mean IT was 16.8 ± 0.6 Ncm. A correlation was found between RFA and ID (r  =  .726, P &lt; .0001), whereas no correlations between RFA and IT or between IT and ID were observed. From T0 to T1, the stability (36.1 ± 6.1 implant stability quotient [ISQ]) decreased nonsignificantly by 4.9 ± 6.1 ISQ values (P &gt; .05). Between T1 and T2, the stability decreased highly significantly (P &lt; .001) by 7.9 ± 5.9 ISQ values. From T2 on, RFA remained nearly unchanged (−1.7 ± 3.5 ISQ; P &gt; .05).

Conclusions:
Mini-implant stability is subject to changes during the healing process. During weeks 3 and 4, a significant decrease of the stability was observed. After 4 weeks, the stability did not change significantly.
Polyhydrated Ionogen with MgBr2 Accelerates in vitro Respiratory Epithelial Healing
Authors: DePoortere David , Chen Bei , Cohen Noam A. 
Published: July 2013

Background Remucoslization of the sinonasal cavity after sinus surgery is critical for successful outcomes. Recently, a novel antiprotease and antifibroblast compound, polyhydrated ionogen (PHI) with MgBr2, showed improved wound healing in a rabbit maxillary sinus mucosal wound model. We set out to determine if this effect was reproducible in an in vitro respiratory epithelial culture system. Methods Fully differentiated mature murine nasal septal air–liquid interface cultures were injured by creating a full-thickness 400-mM-wide scratch through the monolayer. Cultures were then treated with nothing, saline, or PHI with MgBr2for 1 hour on the apical surface. Twenty-four hours after the injury cultures were fixed and processed for immunofluorescence with type IV beta-tubulin and Hoechst stain. Results Initial injury resulted in a wound of 394 micromolar (377–411 micromoler; 95% CI; n = 8). After 24 hours with no intervention the wound closed to 161 micromolar (138–184 micromolar; 95% CI; n = 9) and treatment with saline resulted in a residual gap of 88 micromolar (60–116 micromolar; 95% CI; n = 9; p < 0.05) and treatment with PHI with MgBr2 resulted in a gap of only 30 micromolar (14–46 micromolar; 95% CI; n = 9; p < 0.05). Conclusion Poor healing of the sinonasal mucosa after surgery with loss of ciliary function results in adverse clinical outcomes. In an in vitro sinonasal respiratory epithelial injury model, a one-time treatment with PHI with MgBr2 showed significantly improved wound healing compared with saline or nothing. This is a viable model to further investigate the mechanism by which PHI with MgBr2 improves sinonasal remucosolization.
EFFECT OF POLYSULFANE SILANIZED SILICA ON THE MORPHOLOGY AND MECHANICAL PROPERTIES OF BROMBUTYL RUBBER VULCANIZATES
Authors: Liang Jiyu , Feng Na , Chang Suqin , Wang C. Xinhong , Zhang Guixia 
Published: July 2013

ABSTRACT
Polysulfane silanized white silica particles were prepared by treating with various loadings of bis(3-trie-thoxysilylpropyl)tetrasulfide (TESPT) in a high-speed mixer. Brombutyl rubber (BIIR) vulcanizates filled with the silanized silica were prepared by compression molding. Compared with BIIR/untreated silica vulcanizate, the mechanical properties of BIIR/silanized silica vulcanizates improved prominently with the increase of TESPT loading and reached peak value with the TESPT loading increasing up to 2 phr but declined slightly with the continuous increment of the TESPT. Effects of various loadings of TESPT on the mechanical properties of BIIR vulcanizates were investigated by testing mechanical properties, vulcanizing properties, bound rubber, scanning electron microscopy, and dynamic mechanical analysis (DMA) to determine the extent of rubber-filler interaction. As shown in vulcanizing properties, bound rubber, and DMA measurements, the bound rubber content, cross-link density, and storage and loss modulus of BIIR vulcanizates clearly increased with the TESPT loading increasing from 0 to 2 phr and then reduced somewhat with a continuous increase of TESPT; the tanδmax value decreased significantly with the increment of TESPT loading from 0 to 2 phr and increased sharply with the TESPT content increasing to 4 phr. These experimental results indicate that the improvement in the mechanical properties of BIIR vulcanizates was mostly attributed to a strong BIIR–silica interaction and an effective dispersion of the silica. On the other hand, the decline of mechanical properties can be explained by the excess TESPT, as a kind of physical diluent, having an adverse effect on the silica dispersion and cross-link reaction. By forming the silica aggregates on the mixing, the poor dispersion of silica could cause the decline of relative volume content of silica in the matrix.
COMPARISON OF STRESS–SOFTENINGS IN CARBON-BLACK FILLED NATURAL RUBBER AND STYRENE–BUTADIENE RUBBER
Authors: Diani Julie , Merckel Yannick , Brieu Mathias , Caillard Julien 
Published: July 2013

ABSTRACT
The authors compared the mechanical behavior and, more precisely, the Mullins and the cyclic (post-Mullins) softenings of two filled rubbers. A crystallizing natural rubber and a noncrystallizing styrene–butadiene rubber of similar compositions resulting in similar cross-link densities and filled with 40 phr of N347 carbon-black fillers were tested in cyclic uniaxial tension at room temperature and at 85 °C. Crystallization in filled rubbers is known to increase stress at high stretch, stretch at break, cycle hysteresis, and fatigue lifetime and to reduce crack propagation. In this study, it is shown that crystallization also seems to enhance the Mullins softening (softening at the first cycle) and to favor the apparent cyclic softening. Results reveal that natural rubber shows an amplitude dependence on the cyclic softening, whereas the styrene–butadiene rubber does not. Finally, results demonstrate that studying filled rubber softening cannot help predict lifetime.
CHANGES OF CHEMICAL STRUCTURE AND MECHANICAL PROPERTY LEVELS DURING THERMO-OXIDATIVE AGING OF NBR
Authors: Zhao Jiaohong , Yang Rui , Iervolino Rossana , Barbera Stellario 
Published: July 2013

ABSTRACT
The accelerated thermo-oxidative aging of acrylonitrile–butadiene rubber (NBR) was studied at elevated temperatures. The chemical structure characterized by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) and pyrolysis gas chromatography–mass spectroscopy (PGC-MS) showed the loss of low-molecular-weight additives, such as antioxidants and paraffin, and the formation of carbonyl groups and unsaturated double bonds. The cross-linking degree characterized by NMR and a swelling test showed that aging is a competitive process of cross-linking and chain scission. Cross-linking dominated the thermal aging of NBR most of the time, whereas chain scission began to increase after a long time at high temperatures. The changes of mechanical property magnitudes during thermal aging of NBR were studied by using the recovery from bending test (RFB) and tensile test. By comparing the physical property results and the structural changes, their relationship is discussed.
STUDYING NR/ORGANO-MONTMORILLONITE NANOCOMPOSITES WITH SILANE COUPLING AGENTS VIA NETWORK VISUALIZATION TEM
Authors: Lowe David J. , Chapman Andrew V. , Cook Stuart , Busfield James J. C. 
Published: July 2013

ABSTRACT
Organo-montmorillonite (OMMT) increases the elastic modulus of elastomers such as natural rubber (NR) by a very large amount at low strains, but this decreases as the rubber is extended. Silane coupling agents, widely used with silica-filled rubbers, were added to NR/OMMT nanocomposites to increase the effects of OMMT on modulus at high strains. Both bis(triethoxysilylpropyl)tetrasulfide (TESPT) and 3-mercaptopropyl di(tridecan-1-oxy-13-penta(ethylene oxide))ethoxysilane (MPDES) increase tensile modulus significantly at strains greater than 30%. The coupling agents strengthen the rubber–filler interface, reducing cavitation around OMMT particles and preventing NR molecules from sliding at the interface. Evidence for a stronger rubber–filler interaction is provided by measurements of bound rubber content and use of network visualization transmission electron microscopy (NVTEM). OMMT also affects the dynamic properties of NR differently from other fillers. One aspect of this is the appearance of a peak in tan δ between 20 °C and 60 °C, attributed to the glass transition of intercalated and adsorbed NR molecules. The intensity of this peak is diminished by the addition of TESPT or MPDES, implying that they are restricting the intercalation of the rubber between the clay sheets. The coupling agents also have a small effect on vulcanization behavior compared with that of OMMT.