bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzyme‐Based Resource Allocated Decomposition and Landscape Heterogeneity in the Florida Everglades
Authors: Penton C. Ryan , Newman Susan 
Published: May 2008

AbstractEnzyme catalyzed reactions are generally considered the rate‐limiting step in organic matter degradation and may be significantly influenced by the structure and composition of plant communities. Changes in these rates have the potential to effect long‐term peat accumulation and influence the topography of a wetland ecosystem. To determine habitat influences on enzyme activities, we examined slough and sawgrass plots within enriched and reference phosphorus (P) sites in the Everglades. Assays were performed for the enzymes involved in carbon (C), nitrogen (N), and P cycling and lignin depolymerization. Enzyme activities were normalized and analyzed in terms of a resource allocation strategy. Plant composition was found to significantly alter the allocation of enzymatic resources due to varying substrate complexities. Potential decomposition in the slough was less influenced by lignin than in the sawgrass habitats. Additionally, an index relating hydrolytic and oxidative enzymes was significantly greater in the slough habitats, whereas C/N ratios were significantly lower. These indices suggest more favorable decomposition conditions and thus slower peat accretion within the slough communities, which may contribute to the development of elevation differences within the sawgrass ridge and slough topography of the Everglades.
Comparative Study of Transport Processes of Nitrogen, Phosphorus, and Herbicides to Streams in Five Agricultural Basins, USA
Authors: Domagalski Joseph L. , Ator Scott , Coupe Richard , McCarthy Kathleen , Lampe David , Sandstrom Mark , Baker Nancy 
Published: May 2008

AbstractAgricultural chemical transport to surface water and the linkage to other hydrological compartments, principally ground water, was investigated at five watersheds in semiarid to humid climatic settings. Chemical transport was affected by storm water runoff, soil drainage, irrigation, and how streams were linked to shallow ground water systems. Irrigation practices and timing of chemical use greatly affected nutrient and pesticide transport in the semiarid basins. Irrigation with imported water tended to increase ground water and chemical transport, whereas the use of locally pumped irrigation water may eliminate connections between streams and ground water, resulting in lower annual loads. Drainage pathways in humid environments are important because the loads may be transported in tile drains, or through varying combinations of ground water discharge, and overland flow. In most cases, overland flow contributed the greatest loads, but a significant portion of the annual load of nitrate and some pesticide degradates can be transported under base‐flow conditions. The highest basin yields for nitrate were measured in a semiarid irrigated system that used imported water and in a stream dominated by tile drainage in a humid environment. Pesticide loads, as a percent of actual use (LAPU), showed the effects of climate and geohydrologic conditions. The LAPU values in the semiarid study basin in Washington were generally low because most of the load was transported in ground water discharge to the stream. When herbicides are applied during the rainy season in a semiarid setting, such as simazine in the California basin, LAPU values are similar to those in the Midwest basins.
Contribution of Hydrolysis in the Abiotic Attenuation of RDX and HMX in Coastal Waters
Authors: Monteil‐Rivera Fanny , Paquet Louise , Giroux Romain , Hawari Jalal 
Published: May 2008

AbstractSinking of military ships, dumping of munitions during the two World Wars, and military training have resulted in the undersea deposition of numerous unexploded ordnances (UXOs). Leaching of energetic compounds such as hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) and octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) from these UXOs may cause adverse ecological effects so that the long‐term fate of these chemicals in the sea should be known. The present study assesses the contribution of alkaline hydrolysis into the natural attenuation of RDX and HMX in coastal waters. Alkaline hydrolysis rates were shown to be unaffected by the presence of sodium chloride, the most common component in marine waters. Kinetic parameters (Ea, ln A, k2) quantified for the alkaline hydrolysis of RDX and HMX in deionized water (30–50°C, pH 10–12) agreed relatively well with abiotic degradation rates determined in sterilized natural coastal waters (50 and 60°C, variable salinity) even if the latter were generally slightly faster than the former. Furthermore, similar products (HCHO, NO2−, O2NNHCH2NHCHO) were obtained on alkaline hydrolysis in deionized water and abiotic degradation in coastal waters. These two findings suggested that degradation of nitramines in sterilized natural coastal waters, away from light, was mainly governed by alkaline hydrolysis. Kinetic calculations using the present parameters showed that alkaline hydrolysis of RDX and HMX in marine waters at 10°C would respectively take 112 ± 10 and 2408 ± 217 yr to be completed (99.0%). We concluded that under natural conditions hydrolysis should not contribute significantly to the natural attenuation of HMX in coastal waters whereas it could play an active role in the natural attenuation of RDX.
Rethinking the Contribution of Drained and Undrained Grasslands to Sediment‐Related Water Quality Problems
Authors: Bilotta G. S. , Brazier R. E. , Haygarth P. M. , Macleod C. J. A. , Butler P. , Granger S. , Krueger T. , Freer J. , Quinton J. 
Published: May 2008

AbstractGrass vegetation has been recommended for use in the prevention and control of soil erosion because of its dense sward characteristics and stabilizing effect on the soil. A general assumption is that grassland environments suffer from minimal soil erosion and therefore present little threat to the water quality of surface waters in terms of sediment and sorbed contaminant pollution. Our data question this assumption, reporting results from one hydrological year of observations on a field‐experiment monitoring overland flow, drain flow, fluxes of suspended solids, total phosphorus (TP), and molybdate‐reactive phosphorus (<0.45 μm) in response to natural rainfall events. During individual rainfall events, 1‐ha grassland lysimeters yield up to 15 kg of suspended solids, with concentrations in runoff waters of up to 400 mg L−1 These concentrations exceed the water quality standards recommended by the European Freshwater Fisheries Directive (25 mg L−1) and the USEPA (80 mg L−1) and are beyond those reported to have caused chronic effects on freshwater aquatic organisms. Furthermore, TP concentrations in runoff waters from these field lysimeters exceeded 800 μg L−1 These concentrations are in excess of those reported to cause eutrophication problems in rivers and lakes and contravene the ecoregional nutrient criteria in all of the USA ecoregions. This paper also examines how subsurface drainage, a common agricultural practice in intensively managed grasslands, influences the hydrology and export of sediment and nutrients from grasslands. This dataset suggests that we need to rethink the conceptual understanding of grasslands as non‐erosive landscapes. Failure to acknowledge this will result in the noncompliance of surface waters to water quality standards.
Bioreduction of ionic mercury from wastewater in a fixed-bed bioreactor with activated carbon
Authors: Głuszcz Paweł , Zakrzewska Katarzyna , Wagner-Doebler Irene , Ledakowicz Stanisław 
Published: May 2008

AbstractWide industrial use of mercury led to significant mercury pollution of the environment. It requires development of cleanup technologies which would allow treating large volumes of mercury contaminated water in a cost effective and environmentally friendly way. A novel bio-technology, developed from laboratory to industrial scale in Germany at HZI (former GBF), is based on enzymatic reduction of highly toxic Hg(II) to water-insoluble and relatively non-toxic Hg(0) using live mercury resistant bacteria immobilized on a porous carrier material in a fixed-bed bioreactor. Improvement of the original method was based on the use of activated carbon as a carrier for microorganisms and an adsorbent for mercury. Such integration of the process should increase the technology efficiency. In order to compare different carrier materials, activated carbon and pumice stones were used. The strain Pseudomonas putida was immobilized in bioreactors continuously fed with solutions of HgCl2 enriched with nutrients. Simultaneously, experiments in two more reactors were run in the absence of microorganisms to investigate the influence of nutrients on the adsorption process. In the bioreactor with activated carbon, the outlet mercury concentration was approximately 50 % of that supplied with pumice. It may be concluded that the use of activated carbon in a fixed-bed bioreactor enables improvement of the technology by process integration.
Simultaneous production of citric acid and erythritol from crude glycerol by Yarrowia lipolytica Wratislavia K1
Authors: Rymowicz Waldemar , Rywińska Anita , Gładkowski Witold 
Published: May 2008

AbstractThis study shows a possible microbial process for utilization of crude glycerol generated by the biodiesel industry for citric acid and erythritol production. Simultaneous production of citric acid and erythritol under nitrogen-limited conditions with glycerol as the carbon source was achieved with an acetate negative mutant of Y. lipolytica Wratislavia K1 in fed-batch cultivations. The effect of the initial glycerol concentration (from 30–180 g dm−3) on the citrate and erythritol production was investigated. As a result of the experiments, maximum citric acid production (110 g dm−3) and a very high amount of erythritol (81 g dm−3) were determined after 168 h of fed-batch cultivation with the initial glycerol concentration of 150 g dm−3 and the total glycerol concentration of 250 g dm−3. In addition, the citric acid to isocitric acid ratio of the products from this strain was 35.5:1.
Preparation of α-methyl-γ-butyrolactone: Mechanism of its formation and utilization in 2-methyl-1-tetralone synthesis
Authors: Semak Vladislav , Boháč Andrej , Sališová Marta , Addová Gabriela , Danko Peter 
Published: May 2008

Abstractα-Methyl-γ-butyrolactone (III) has been prepared directly from γ-butyrolactone (I) in 89 % yield by selective monomethylation conditions: K2CO3/DMC/210°C/7 h. The reaction mechanism was elucidated and described. An intermediate and two byproducts: methyl tetrahydro-3-methyl-2-oxofuran-3-carboxylate (II), 3-(methoxycarbonyl)propyl methyl carbonate (IV) and 3-(methoxycarbonyl)butyl methyl carbonate (V) were identified. The high temperature disproportionation of K2CO3 in the presence of dimethyl carbonate to MeOK was observed. The new selective synthesis of 2-methyl-1-tetralone (VI) from α-methyl-γ-butyrolactone (III) by Friedel-Crafts conditions was performed in 79 % yield.
Prediction of excess molar volumes of binary mixtures of organic compounds from refractive indices
Authors: Radović Ivona , Kijevčanin Mirjana , Gabrijel Marijan , Šerbanović Slobodan , Djordjević Bojan 
Published: May 2008

AbstractThe excess molar volumes of 51 binary mixtures containing diverse groups of organic compounds: alcohols (methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, and heptan-1-ol), (cyclo-) alkanes (hexane, heptane, octane, nonane, decane, undecane, dodecane, and cyclohexane), esters (diethyl carbonate and ethyl chloroacetate), aromatics (o-xylene, m-xylene, p-xylene, and ethylbenzene), ketones (acetone), and ethers (anisole), were predicted from the refractive index data, using three types of equations coupled with several different mixing rules for refractive index calculations: the Lorentz-Lorenz, Dale-Gladstone, Eykman, Arago-Biot, Newton, and the Oster. These systems were chosen since they belong to different classes of organic species forming molecular interactions and intermolecular forces during mixing resulting in positive or negative, smaller or larger deviations from ideal behaviour. The obtained results were analysed in terms of the applied equation and mixing rule, the nature of compounds of the mixtures and the influence of alkyl chain length of the alkane or alcohol molecule.
In situ and ex situ characterization of a Fe-Cr-Ni alloy in mouthwashes and Hank’s solution
Authors: Cestarolli Dane , Alves Valéria , Silva Luís 
Published: May 2008

AbstractThe aim of the present study was to classify the surface oxide layers formed on a Fe-Cr-Ni alloy according to their corrosion resistance in Hank’s solution and mouthwashes by SEM and electrochemical techniques. The SEM micrographs showed the presence of localized corrosion and the polarization curves showed that the passive layer is less stable in the presence of Hank’s solution than of mouthwashes, as a result of the presence of chloride ions.
Synthesis of 2-methyl-2-propoxypropyl isocyanide and its Cu(I) tetraflouroborate complex
Authors: Al-Ktaifani Mahmoud , Nakawa Adnan , Tabbaa Zouheir , Namou Adel 
Published: May 2008

Abstract2-Methyl-2-propoxypropyl isocyanide [CNCH2C(OPr)(CH3)2] and its Cu(I) tetrafluoroborate complex [Cu{CNCH2C(OPr)(CH3)2}4]BF4 were prepared in good yields and purities. Both compounds were fully characterized by IR and NMR spectroscopy.
The natural regeneration of salt marsh on formerly reclaimed land
Authors: Garbutt Angus , Wolters Mineke 
Published: May 2008

Abstract.Question: Does the vegetation of restored salt marshes increasingly resemble natural reference communities over time?Location: The Essex estuaries, southeast England.Methods: Abandoned reclamations, where coastal defences had been breached in storm events, and current salt marsh recreation schemes were surveyed giving a chronosequence of salt marsh regeneration from 2 to 107 years. The presence, abundance and height of plant species were recorded and comparisons were made with adjacent reference salt marsh communities at equivalent elevations.Results: Of the 18 paired sites surveyed, 13 regenerated marshes had fewer species than their adjacent reference marsh, three had an equal number and two had more. The plant communities of only two de‐embankment sites matched that of the reference community. 0–50 year old sites and 51–100 year old sites had fewer species per quadrat than the 101+ year sites and the reference salt marshes. There was a weak relationship between differences in species richness for regenerated and reference marshes and the time since sites were first re‐exposed to tidal inundation. Cover values for the invasive and recently evolved Spartina anglica were greater within regenerated than reference marshes.Conclusions: Salt marsh plants will colonise formerly reclaimed land relatively quickly on resumption of tidal flooding. However, even after 100 years regenerated salt marshes differ in species richness, composition and structure from reference communities.
The Effect of Alloying on the Bandgap Energy of Nanoscaled Semiconductor Alloys
Authors: Zhu Yong Fu , Lang Xing You , Jiang Qing 
Published: April 2008

AbstractBased on a model for the size‐dependent bandgap energy of low‐dimensional semiconductor compounds, the alloying effect on the bandgap of nanoscale semiconductors is modeled without any adjustable parameter. The model predicts not only a trend of increasing bandgap with decreasing nanocrystal size but also Végard¢s relationship between the bandgap and the alloy composition when the size drops close to twice that of the critical size for the nanocrystals. The model predictions agree with available experimental results for bandgap changes of pseudo‐binary IIB–VIB chalcogenide semiconductor nanocrystals.
Viscosity of moderately concentrated solutions of polymethyl‐methacrylate in methyl‐methacrylate
Authors: Singh Gurpreet J. , Gupta Santosh K. 
Published: May 2008

AbstractA Haake® viscometer with the NV cup‐and‐bob sensor is used to measure the viscosity, η, of polymethyl methacrylate (PMMA) solutions in methyl methacrylate (MMA) at several polymer concentrations, weight‐average molecular weights, and temperatures, and under nonreacting conditions. Six polymer samples having different average molecular weights are prepared by polymerizing MMA in a 1‐L batch reactor using 2,2′‐azoisobutyronitrile (AIBN) as the initiator. Our earlier experimental data (at moderate concentrations of the polymer) on the viscosity of PMMA solutions in MMA under reacting conditions is also used. Two general correlations are developed between $ {\eta \over \eta_{\rm sol}} $ and CpolyM with the parameters obtained using genetic algorithm. The tuned correlations for viscosity can be used over an extended range of monomer conversions for model‐based state estimation and on‐line optimal control of the bulk polymerization of MMA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of poly(methyl methacrylate)‐grafted silica microparticles
Authors: Derouet Daniel , Ha Thuc Chi Nhan 
Published: May 2008

AbstractA procedure to synthesize poly(methyl methacrylate)‐grafted silica microparticles was developed by using radical photopolymerization of methyl methacrylate (MMA) initiated from N,N‐diethyldithiocarbamate (DEDT) groups previously bound to the silica surface (grafting “from”). The functionalization of silica microparticles with DEDT groups was performed in two steps: introduction of chlorinated functions onto the surface of silica particles, and then nucleophilic substitution of chlorines by DEDT functions via a SN2 mechanism. The study was performed with a Kieselgel® S silica which was initially chlorinated in surface, either by direct chlorination of silanols with thionyl chloride, or by using a condensation reaction between silanols and a chlorofunctional trialkoxysilane reagent, 4‐(chloromethyl)phenyltrimethoxysilane and chloromethyltriethoxysilane, respectively. Three types of DEDT‐functionalized silica microparticles were prepared with a good control of the reactions, and then characterized by solid‐state 13C and 29Si CP/MAS NMR. Their ability to initiate MMA photopolymerization was studied. The kinetics of MMA photopolymerization was followed by HPLC and 1H‐NMR. Whatever the silica used the grafting progresses very slowly. On the other hand, the conversion of MMA in PMMA grafts is depending on the structure of the DEDT‐functionalized Kieselgel® S used. Poly(methyl methacrylate)‐grafted silica microparticles bearing high length grafts ($ \overline {{\rm DP}_n} $ about 100) were synthesized. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Arginine Dynamics in a Membrane‐Bound Cationic Beta‐Hairpin Peptide from Solid‐State NMR
Authors: Tang Ming , Waring Alan J. , Hong Mei 
Published: April 2008

AbstractThe site‐specific motion of Arg residues in a membrane‐bound disulfide‐linked antimicrobial peptide, protegrin‐1 (PG‐1), was investigated by using magic‐angle‐spinning solid‐state NMR spectroscopy to better understand the membrane insertion and lipid interaction of this cationic membrane‐disruptive peptide. The C–H and N–H dipolar couplings and 13C chemical shift anisotropies were measured in the anionic POPE/POPG membrane, and were found to be reduced from the rigid‐limit values by varying extents; this indicates the presence of segmental motion. An Arg residue at the β‐turn region of the peptide showed much weaker spin interactions, which indicates larger amplitudes of motion than an Arg residue in the β‐strand region of the peptide. This is consistent with the exposure of the β turn to the membrane surface and the immersion of the β strand in the hydrophobic middle of the membrane, and supports the previously proposed oligomerization of the peptide into β barrels in the anionic membrane. The 13C T2 and 1H T1ρ relaxation times indicate that the β‐turn backbone undergoes large‐amplitude intermediate‐timescale motion in the fluid phase of the membrane; this causes significant line broadening and loss of spectral intensity. This study illustrates the strong correlation between the dynamics and structure of membrane proteins, and the capability of solid‐state NMR spectroscopy to provide detailed information on site‐specific dynamics in complex membrane‐protein assemblies.
Tucker1 model algorithms for fast solutions to large PARAFAC problems
Authors: Van Benthem Mark H. , Keenan Michael R. 
Published: April 2008

AbstractWe describe a method of performing trilinear analysis on large data sets using a modification of the PARAFAC‐ALS algorithm. Our method iteratively decomposes the data matrix into a core matrix and three loading matrices based on the Tucker1 model. The algorithm is particularly useful for data sets that are too large to upload into a computer's main memory. While the performance advantage in utilizing our algorithm is dependent on the number of data elements and dimensions of the data array, we have seen a significant performance improvement over operating PARAFAC‐ALS on the full data set. In one case of data comprising hyperspectral images from a confocal microscope, our method of analysis was approximately 60 times faster than operating on the full data set, while obtaining essentially equivalent results. Copyright © 2008 by John Wiley & Sons, Ltd.
To What Extent Can Viable Bacteria in Atmospheric Aerosols be Dangerous for Humans?
Authors: Safatov Alexandre S. , Andreeva Irina S. , Belan Boris D. , Buryak Galina A. , Emel'yanova Elena K. , Jaenicke Ruprecht , Panchenko Mikhail V. , Pechurkina Natalya I. , Puchkova Larisa I. , Repin Vladimir E. , Saranina Irina V. , Sergeev Alexander N. 
Published: April 2008

AbstractMulti‐year monitoring of atmospheric bioaerosol in Southwestern Siberia revealed the presence of a large number of various culturable microorganisms. It is known that viable microorganisms can cause directly or provoke different human diseases. It's very difficult to evaluate the danger represented by each microorganism to man directly. Therefore, a relatively simple method is required for evaluation of potential danger represented to man by the whole assembly of culturable microorganisms in an atmospheric aerosol sample. For bacteria, the method can be based on a number of individual characteristics of each microorganism determined in the course of biochemical and other test required for identification of the detected bacterium, and a number of other tests. It is proposed to classify the measured individual characteristics of bacteria under four groups of indices responsible for: (i) potential pathogenicity for man; (ii) the numbers of bacteria in the sample; (iii) resistance to unfavorable environmental factors; (iv) drug resistance of bacteria. Each of four groups of indices is numerically evaluated by a certain integral index, which quantitatively reflects the contribution of experimentally determined characteristics of bacteria. Expert evaluation of the contribution of each characteristic of microorganisms to the corresponding group of indices is performed. The generalized index of potential danger of culturable bacteria in atmospheric aerosols for human health is presented as the product of four integral indices summarizing the normalized individual integral indices for all bacteria detected in the sample. The work presents the results of measuring the variations of all the above indices for atmospheric air samples collected during one year.