Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution

The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.     

Heavy‐metal mobilization and uptake by mycorrhizal and nonmycorrhizal willows (Salix × dasyclados)

Ectomycorrhizal fungi have been shown to affect metal transfer from the soil to the host plant, but the use of these fungi for increased phytoextraction of heavy metals has been scarcely investigated. Therefore, a two‐factorial pot experiment was conducted with Salix × dasyclados and (1) two contaminated soils with different concentrations of NH₄NO₃‐extractable metals and (2) two strains of the ectomycorrhizal fungus Paxillus involutus (one strain originating from a noncontaminated site—Pax1, and another from a contaminated site—Pax2). The inoculation with Pax2 increased the phytoavailability of Cd in the soils. Inoculation with both fungal strains increased the stem and root biomass, but had no effect on metal concentrations in the stems. Decreased Cd and increased Cu concentrations were observed in the roots of inoculated willows. The inoculation with P. involutus increased Cd (up to 22%), Zn (up to 48%), and Cu content in the stems. Decreased Pb content (Cu and Pb content were always <1 mg per plant) occurred in the stems from plants at the soil with the higher concentration of NH₄NO₃‐extractable metals. Contrary to this, in the soil with lower concentrations of NH₄NO₃‐extractable metals, the inoculation had no significant effects on the total uptake of Zn and Cu and even caused decreased Cd (Pax2) and Pb (Pax1) contents in the stems. Strain Pax2 had higher colonization densities, but the plants had lower mycorrhizal dependencies in the contaminated soils than after inoculation with the strain Pax1. Generally, metal extractability in the soils substantially affected the mycorrhizal dependency and heavy‐metal uptake of the willows. We concluded, that the inoculation with P. involutus offers an opportunity to particularly increase the phytoextraction of Zn, but the metal extractability and fungal strain effects have to be tested.     

Patterns of microarthropod abundance in oak-hickory forest ecosystems in relation to prescribed fire and landscape position

We examined patterns of microarthropod abundance in oak-hickory (Quercus-Carya) forest ecosystems in southern Ohio (USA) in relation to landscape position and fire frequency. Abundances of various suborders of Acari and Collembola were determined in samples taken in June 1999 in three forested watersheds, one that had been burned annually for four consecutive springs (1996-1999), one that had been burned periodically (1996 and 1999), and an unburned control. Microarthropod abundance was significantly lower in the annually burned watershed than the periodically burned and control watersheds. Since both the periodically burned and annually burned watersheds were burned in April 1999, the lower microarthropod abundance in the annually burned watershed was not simply an immediate effect of burning. At the landscape scale, the abundance of oribatid mites was greater in xeric than intermediate or mesic landscape positions. Within any single watershed, there was no significant linear relationship between litter mass and microarthropod abundance. However, when all three watersheds were combined, there was a significant, positive relationship between litter mass and microarthropod abundance, mainly due to the annually burned watershed where there was very low litter mass and low microarthropod abundance. Both fire frequency and landscape position have significant effects on microarthropod abundance; however, those effects cannot be robustly predicted based solely on forest floor litter mass differences.     

Modelling of snowmelt erosion and sediment yield in a small low-mountain catchment in Germany

Temporal variability and spatial heterogeneity of surface runoff generation triggers the dynamics of source areas of sediment and sediment-associated nutrient transport. Reliable modelling of hydrological special situations i.e. snowmelt is of high importance for the quality of erosion and sediment yield modelling. Data from the research catchment Schäfertal demonstrate the individuality of snowmelt events in terms of runoff coefficient and delivery ratio. This 1.44 km² low mountain catchment is characterised by a high portion of arable land with a winter grain/winter rape crop rotation. The integrated winter erosion and nutrient load model (IWAN) considers these dynamic aspects by coupling a hydrological model with a sediment load model. Cell size of this raster-based approach is 10 × 10 m². Additionally, snowmelt rill erosion is simulated with a newly developed physically based model that is firstly applied on a catchment scale. A sensitivity analysis of this model system component demonstrates the plausibility of the model approach and the overall robustness of the model system IWAN. The results of the long-term hydrological modelling from 1991 to 2003 are reliable and form the basis for the simulation of six snowmelt events which were observed in the Schäfertal catchment. The estimated total runoff volumes for these events match the observations well. The modelled overland runoff coefficients vary from 0.001 to 0.72. The mean values of cell erosion, which were modelled with one set of parameters for all six events range from 0.0006 to 0.96 t ha^− 1. The total modelled erosion for the events with unfrozen soil and low amount of surface runoff is of a factor 50 below those with partly frozen soil. In addition to these distinctions, the major differences are caused by flow accumulation in shallow depressions in variable parts of the catchment. However, the validation of these results on the single event scale is restricted due to limited spatial data. Total simulated sediment yield at the catchment outlet was as high as 13.84 t which underestimates the observed values, with the exception of one event. Oversimplification of the modelled channel processes may be a reason. The temporal variability and spatial heterogeneity of the surface roughness parameter, which was identified to be sensitive, also causes uncertainty in the parameter estimation. Despite these findings, the model system IWAN was applied successfully on the catchment scale and the simulated results are reliable.     

Enzyme-electropolymer-based amperometric biosensors: an innovative platform for time-temperature integrators

A novel exogenous time-temperature integrator (TTI) based on an amperometric glucose oxidase biosensor is presented. The TTI consists of the enzyme entrapped within an electrochemically generated poly(o-phenylenediamine) (PoPD) thin film deposited on the interior wall of a platinum (Pt) or a platinized stainless steel (Pt-SS) capsule. After thermal treatment, the TTI is mounted in a continuous flow system and connected to a potentiostat for amperometric detection of residual enzyme activity. A measurement is completed within 10 min. Isothermal treatments were carried out between 70 and 79.7 degrees C. Thermal inactivation of the immobilized enzyme followed apparent first-order kinetics with z values of 6.2 +/- 0.6 and 6.6 +/- 0.8 degrees C for Pt and Pt-SS capsules, respectively. These z values suggest that the proposed TTIs have the potential to assess pasteurization processes that target microorganism such as Listeria monocytogenes and Escherichia coli O157:H7.     

Hydroxylysyl pyridinoline cross-link concentration affects the textural properties of fresh and smoked Atlantic salmon (Salmo salar L.) flesh

A simple HPLC method is presented to quantify the low concentration of hydroxylysyl pyridinoline (PYD) cross-links in Atlantic salmon (Salmo salar L.) muscle. The method involved the extraction of tissue with NaOH prior to hydrolysis, which greatly reduced the amount of protein to be hydrolyzed and made downstream operations easier and more reproducible. The concentration of PYD was 426 pmol g(-)(1) dry mass muscle in post-rigor muscle stored at 0 degrees C and sampled 3 d after death. Hydroxproline (HYP) concentration was determined following NaOH extraction as a measure of collagen content. In post-rigor samples, the alkaline-insoluble HYP fraction comprised 18.3% of the total HYP. Scanning electron microscopy revealed shrinkage of muscle fibers and a retraction of the connective tissue matrix in smoked salmon. PYD concentration was relatively resistant to processing to the smoked product, decreasing by around 11.7%, as compared to a 22.2% decrease in HYP. There was a positive correlation between PYD concentration and the firmness of post-rigor muscle samples as measured by an instrumental texture analyzer, explaining 25% of the total variation. A weaker but still significant correlation was found between PYD concentration and firmness in the smoked product. There was no relationship between fillet firmness and total collagen concentration, although the correlation with HYP in the alkaline-insoluble fraction was significant at the 6% level (P = 0.057). Our results indicate that only 1-3% of collagen molecules are linked by nonreducible mature cross-links in harvest size farmed Atlantic salmon and that PYD concentration is an important raw material characteristic for flesh quality.     

Cross-linking of maize walls by ferulate dimerization and incorporation into lignin

Cross-linking of xylans and lignin by ferulates was investigated with primary maize walls acylated with 2% ferulate and with ferulate ethyl esters. Peroxidase-mediated coupling of wall ferulate and ethyl ferulate yielded mostly 8-coupled products, including three new dehydrodimers. Significant quantities of 5-5-coupled diferulate formed only within walls, suggesting that matrix effects influence dimer formation. Over 60% of wall ferulate dimerized upon H2O2 addition, suggesting that xylan feruloylation is highly regulated during wall biosynthesis to permit extensive dimer formation at the onset of lignification. During lignification, ferulate and 5-5-coupled diferulate copolymerized more rapidly and formed fewer ether-linked structures with coniferyl alcohol than 8-5-, 8-O-4-, and 8-8-coupled diferulates. The potential incorporation of most ferulates and diferulates into lignin exceeded 90%. As a result, xylans become extensively cross-linked by ferulate dimerization and incorporation to lignin, but only a small and variable proportion of these cross-links is measurable by solvolysis of lignified walls.     

Effects of mustard residues on the carbon and nitrogen turnover in undisturbed soil microcosms

The C- and N-turnover of undisturbed, irrigated 25 cm soil microcosms of a Typic Agrudalf from loess were followed during a laboratory incubation of about 200 days. Besides the untreated control columns two treatments were installed to test the effects of the application of white mustard (Sinapis alba L.) on both nutrient cycles (either mixing the dried plant residues to 0–8 cm or surface application). Each of the treatments is represented by 4 soil columns to account for soil variability. The C-budget was mainly altered for soil respiration, which increased for the microcosms treated with mustard rapidly after application. After 4 weeks no differences could be proved however. The loss of soluble C-compounds, which was unimportant for the budget, reflected no one of the treatments with mustard. Net N mineralization, as calculated from the NO₃-leaching, could be well fitted by zero-order kinetics. Although the high variability of the net N mineralization of the replicates mustard application significantly rises the N-release. No difference could be proved for the different techniques of application however. In the mixed treatment 38% of the nitrogen added with the mustard was decomposed during the incubation period, in the surface treatment 34%.     

Real-time monitoring of 4-vinylguaiacol,guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry

The formation of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting was monitored in real-time, using resonance enhanced multiphoton ionization and time-of-flight mass spectrometry. A model is proposed, based on two connected reaction channels. One channel, termed the "low activation energy" channel, consists of ester hydrolysis of 5-FQA followed by decarboxylation of the ferulic acid to form 4-vinylguaiacol, and finally polymerization at the vinyl group to form partly insoluble polymers (coffee melanoidins). The second "high activation energy" channel opens up once the beans have reached higher temperatures. It leads to formation of guaiacol, via oxidation of 4-vinylguaiacol, and subsequently to phenol and other phenolic VOCs. This work aims at developing strategies to modify the composition of coffee flavor compounds based on the time-temperature history during roasting.     

The impact of urban development and human disturbance on the numbers of nightjar Caprimulgus europaeus on heathlands in Dorset, England

The factors influencing the number of nightjars on 36 heathland sites (referred to as patches) in Dorset, England were examined using novel spatial integration of existing datasets. Surrogate measures of human density and settlement, including the amount of developed land at different distances from the heath (obtained from aerial photographs) and the actual number of buildings (obtained from Post Code databases) were all found to be highly correlated with each other and to show a strong negative relationship with the density of nightjars present on a patch, regardless of patch size. The amount of woodland (the preferred foraging habitat) surrounding each patch (within 500 m of the patch boundary) was also a significant predictor of nightjar numbers. When used together, the extent of woodland and developed land both gave significant improvements to predictions of nightjar density. The results indicate that the number of nightjars present on a heathland patch is influenced by the surrounding land-use and that the effect of urban development is more than just habitat loss. We suggest that trends identified are at least partly due to actual human presence on the heathlands and as such, human disturbance is potentially a problem for this species.