bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical Results of Flexor Tendon Repair in Zone II Using a Six-Strand Double-Loop Technique Compared with a Two-Strand Technique
Authors: Hoffmann G. L. , Büchler U. , Vögelin E.
Published: August 2008

The clinical and functional results of 46 patients who underwent zone II flexor tendon repair using the Lim/Tsai technique combined with the Kleinert/Duran early active mobilisation regime and place and hold exercises were assessed. The results were compared with 25 patients who were treated by the modified Kessler technique and the Kleinert/Duran regime alone.

After a follow-up of 8 to 17 weeks, the Lim/Tsai group had a better grip strength and a significantly better total active motion of 141° compared with 123°. The rupture rates (Lim/Tsai: 1/51; Kessler: 3/26) and the extension deficits were not statistically different in the two groups. However, the complication rate was significantly lower and the average time of treatment was significantly shorter in the Lim/Tsai group.

These results support the use of the Lim/Tsai six-strand repair technique in zone II flexor tendon injuries and early active mobilisation without rubber-band traction.
A Report on the Early Failure of the LPM Proximal Interphalangeal Joint Replacement
Authors: HOBBY J. L. , EDWARDS S. , FIELD J. , GIDDINS G.
Published: August 2008

The LPM (Van Straten Medical, Netherlands) proximal interphalangeal joint replacement was introduced to the United Kingdom in October 2000, and 257 implants were sold. We have audited the results of this prosthesis, and obtained data for 164 of the 257 implants. Forty-seven (29%) of the 164 have been revised and another 33 (20%) are showing clinical and radiological signs of failure at a maximum follow-up of 6 years. Massive osteolysis leading to aseptic loosening is the commonest cause of failure. We believe that all patients who have had this prosthesis inserted should be kept under regular clinical and radiographic review.
Improvement on wettability between carbon nanotubes and Sn
Authors: Zhao B. , Yadian B. L. , Li Z. J. , Liu P. , Zhang Y. F.
Published: August 2008

Several metals (Sn, Cu and Ag) were coated on the surface of carbon nanotubes (CNTs) by electroless plating to improve the wettability between CNTs and the Sn matrix. The coated CNTs were characterised by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The results reveal that the metals are decorated effectively on the sidewalls of CNTs. The deposited metals are supposed to serve as the medium for interacting with the melted Sn matrix and achieve high strength interfacial adhesion. It was found that the Ag coated CNTs are wetted to a certain degree by melted Sn and embedded well in the matrix. While in the case of Sn and Cu coated CNTs, fewer CNTs are embedded in the Sn matrix because of desorption or oxidation.
Microstructure and wear resistance of Al2O3–TiB2 composite coating deposited by axial plasma spraying
Authors: Cheng H. C. , Li Z. X. , Shi Y. W.
Published: August 2008

Two Al2O3–TiB2 composite coatings were deposited by axial plasma spray using two types of feedstocks. One of the feedstocks was a conventional micrometre sized Al2O3–30 wt-%TiB2 composite powder from a self-propagating high temperature synthesis (SHS) process. The second was fabricated by spray drying SHSed Al2O3–30 wt-%TiB2 composite powder doped with 10 mass-% nanosized Al2O3 powder. The microstructure of the feedstocks and as sprayed coatings were comparatively investigated by scanning electron microscope and X-ray diffraction. Wear resistance of as sprayed coatings were assessed using block on ring wear test at room temperature. Results showed that Al2O3–TiB2 composite coatings were composed of α-Al2O3, γ-Al2O3, TiB2 and a small amount of TiO2. TiB2 that mostly remained in the shape of undeformed particle were dispersedly distributed in the matrix of the composite coatings. The coating from spray dried powder exhibited finer and denser microstructure and demonstrated better wear resistance than the coating from the SHSed powder under the same sliding conditions.
Managing by Insecurity: Work and Managerial Control under Outsourcing
Authors: Williams Glynne
Published: August 2008

This paper examines the development of managerial control throughout the course of a flagship outsourced contract and discusses the implications of outsourcing for trade union strategy. Outsourcing provides a productive insecurity, enabling the contractor to link individual performance with contract renewal. However, this needs to co-exist with some semblance of stability, and under fixed-term contracting, the inherent contradiction between these two aims is exposed over time. Employee priorities become bounded by the workplace and by the term of the contract. Consequently, bargaining relationships, which were sustainable ‘in-house’, are called into question. The dilemma for trade unions arises from the need to re-build a wider agenda from this focus on the here-and-now.
The Competitive Characteristics of US Firms in the Industrial Design Sector: Empirical Evidence from a National Survey
Authors: Vanchan Vida , Macpherson Alan
Published: August 2008

This paper examines the technological and business characteristics of US companies in the industrial design sector. Evidence from a survey of 85 design consultancies suggests that this sector has become increasingly export-active, technologically innovative and research-oriented. The vast majority of design firms are small-to-medium-sized enterprises (SMEs) that employ fewer than 20 workers. These firms supply critical innovation inputs to their clients. Potential benefits to users include reduced defect rates for new products, optimized ergonomics, aesthetic superiority, ease of manufacture and improved product performance. However, at least two problems can be anticipated for this sector over the next few years. First, domestic service vendors may soon experience significant foreign competition. Second, the de-industrialization of the US manufacturing base suggests that foreign export markets will eventually become important to the survival of US design firms. Our data suggest that export-oriented design companies exhibit stronger business performance than their domestically-focused counterparts, notably in terms of sales growth, employment creation, research spending and profitability. Most importantly, business performance is associated with investment in human capital, technology upgrades and the provision of contract R&D services.
The early development of the senate of Constantinople
Authors: Skinner Alexander
Published: August 2008

The development of the senate of Constantinople as an imperial senate, on a par with the senate of Rome, has been attributed to Constantius II to the exclusion of Constantine and dated to 357. The present paper argues that the evidence for this dating is fundamentally flawed and that the decisive change came at the outset of the reign of Constantius II, while developments under Constantine foreshadowed it in significant respects. Conclusions are also drawn about what the evidence reveals of relations between Hellenic gentry and imperial rule in the fourth century.
A history of the caesar John Doukas in Nikephoros Bryennios’ Material for History?
Authors: Neville Leonora
Published: August 2008

This article suggests that the history of Nikephoros Bryennios draws on a now lost text that told the history of the 1070s from the perspective of the caesar John Doukas. Changes in perspective, narrative style, and vocabulary in the sections dealing predominantly with John suggest that Bryennios was incorporating portions of a written text rather than orally preserved stories. These stylistic arguments are not definitive but, especially in light of the way the author freely included portions of Psellos’ and Skylitzes’ histories, they lead to the supposition that Bryennios also used a text about John Doukas that no longer survives.
Central administration versus provincial arbitrary governance: Patmos and Mount Athos monasteries in the 16th century
Authors: Kermeli Eugenia
Published: August 2008

The confiscation of monastic properties ordered by Selim II in 1568 served as a catalyst precipitating a process of negotiation and mutual accommodation between the centre – represented by the sultan and his jurisconsult- and the periphery articulated by the monks. Even in formulaic imperial orders, it is apparent that the monastic communities successfully negotiated the terms for the normalisation of the affair, whereas the jurisconsult accommodated the Porte’s interests to the local society’s needs. On the local level, the judge functioned as a mediator, addressing the monks’ requirements, even if he had to transgress a number of Islamic rules and imperial orders. Thus, this case study illustrates the gradual transformation of a polity in dialogue with local communities.
Ectomycorrhizal weathering, a matter of scale?
Authors: Smits M. M. , Bonneville S. , Haward S. , Leake J. R.
Published: August 2008

Boreal forest trees influence mineral weathering rates via exudation and uptake processes. Most trees in the boreal forest live in symbiosis with ectomycorrhizal (EcM) fungi that sheath most of the root tips and form the main interface between the tree and the soil. Current weathering models do not take into account the nature and scale of fungal-mineral interactions. Here we show for the first time grain-scale effects of EcM fungi in symbiosis with a host plant on mineral weathering under sterile conditions. EcM fungi actively direct their growth and energy flow towards mineral grains containing essential nutrient elements for the tree and fungus.
Macro- to nanoscale study of the effect of aqueous sulphate on calcite growth
Authors: Vavouraki A. I. , Putnis C. V. , Putnis A. , Oelkers E. H. , Koutsoukos P. G.
Published: August 2008

Calcite growth rates were measured in the presence of sulphate using mixed-flow reactors and in situ Atomic Force Microscopy. Preliminary observations reveal that the kinetics and mechanism of the calcite growth was altered by the presence of sulphate. Calcite growth rates in the presence of sulphate (≥ mM) were decreased and two-dimensional nuclei tend to grow on top of existing nuclei, rather than spreading. The height of new nuclei was ~4 Å, 1 Å greater than that of pure calcite growth. This difference reflects the incorporation of tetrahedral SO2-4 anions into the calcite lattice.
Etch pits on naturally altered olivine from dunites of the Appalachian Blue Ridge Mountains, North Carolina, USA
Authors: Velbel M. A. , Ranck J. M.
Published: August 2008

Naturally weathered olivine from metamorphosed, tectonized metadunite is corroded by funnel-shaped etch pits. Large etch pits form by weathering, and are not inherited from pre-weathering alteration of these rocks. Comparison of etch pits on olivine in naturally weathered metadunite with naturally weathered olivine phenocrysts from volcanic rocks suggests that olivine etch pits are similar in all sample suites, despite differences in crystallization and weathering/exposure ages, and regolith history.
Formation of hydroxysulphate and hydroxycarbonate green rusts in the presence of zinc using time-resolved in situ small and wide angle X-ray scattering
Authors: Ahmed I. A. M. , Shaw S. , Benning L. G.
Published: August 2008

The formation and transformation of hydroxysulphate (GRSO4) and hydroxycarbonate (GRCO3) Green Rusts were studied in situ using synchrotron-based time-resolved small and wide angle X-ray scattering. The time-resolved data revealed, for the first time, the pH dependent transition from poorly-ordered schwertmannite (pH <6.5) into GRSO4 (pH ~6.8) followed by GRCO3 (at pH ~9.6). These data also showed that the addition of Zn to the starting sulphate Fe2+/Fe3+ solution resulted in a change in size of the GR unit-cell due to substitution of Zn into the GR structure.
The blue colouring of beryls from Licungo, Mozambique: an X-ray absorption spectroscopy study at the iron K-edge
Authors: Figueiredo M. O. , Pereira da Silva T. , Veiga J. P. , Leal Gomes C. , De Andrade V.
Published: August 2008

The colours of natural and synthetic beryl (ideally Be3Al2Si6O18) have been attributed either tothe presence of chromophore ions partially replacing Al and/or Be (Cr3+, Fe2+/3+, Mn2+) or to the occurrence of colour centres related to the presence of multi-atomic groups. However, no full explanation has been proposed for the blue colour in natural beryl gemstones (aquamarine) despite it being well established that bluish-green synthetic aquamarines containing Fe turn blue when heated for 1 h at 400°C.

A X-ray absorption near-edge spectroscopy (XANES) study at the Fe K-edge was performed on blue beryl crystals from Licungo pegmatite (Mozambique) to ascertain the speciation state of this colouring element, reported in blue sapphire (ideally Al2O3) as a mixture of Fe2+ and Fe3+ in octahedral coordination. The general trend of the spectra is the same when synchrotron radiation (SR) impinges along the c axis of the hexagonal crystal, as well as along the a axis with c vertical. Conversely, a shoulder in the absorption edge is noticed when the incident beam is perpendicular to c, with this axis horizontal in the polarization plane of the SR beam, a reverse in the relative intensities of the two post-edge features is simultaneously observed. Pre-edge features accounting for Fe speciation (valence plus coordination) are identical in all three situations. Considering previous approaches which account for polarization, an explanation is suggested for the special effects observed on the Fe K-edge XANES spectra of analysed blue beryl crystals. Ideas on the origin of the blue colour of this mineral are also presented.
Application of synchrotron methods to assess the uptake of roadway-derived Zn by earthworms in an urban soil
Authors: Lev S. M. , Landa E. R. , Szlavecz K. , Casey R. , Snodgrass J.
Published: August 2008

The impact of human activities on biogeochemical cycles in terrestrial environments is nowhere more apparent than in urban landscapes. Trace metals, collected on roadways and transported by storm water, may contaminate soils and sediments associated with storm water management systems. These systems will accumulate metals and associated sediments may reach toxic levels for terrestrial and aquatic organisms using the retention basins as habitat. The fate and bioavailability of these metals once deposited is poorly understood. Here we present results from a dose-response experiment that examines the application of synchrotron X-ray fluorescence methods (μ-SXRF) to test the hypothesis that earthworms will bio-accumulate Zn in a roadway-dust contaminated soil system providing a potential pathway for roadway contaminants into the terrestrial food web, and that the storage and distribution of Zn will change with the level of exposure reflecting the micronutrient status of Zn.

Lumbricus friendiwas exposed to Zn-bearing roadway dust amended to a field soil at six target concentrations ranging from background levels (45 mg/kg Zn) to highly contaminated levels (460 mg/ kg Zn) designed to replicate the observed concentration range in storm-water retention basin soils. After a 30 day exposure, Zn storage in the intestine is positively correlated with dose and there is a change in the pattern of Zn storage within the intestine. This relationship is only clear when μ-SXRF Zn map data is coupled with a traditional toxicological approach, and suggests that the gut concentration inL. friendiis a better indicator of Zn bioaccumulation and storage than the total body burden.
Green rust as a precursor for magnetite: an in situ synchrotron based study
Authors: Sumoondur A. , Shaw S. , Ahmed I. , Benning L. G.
Published: August 2008

In this study, direct evidence for the formation of magnetite via a green rust intermediate is reported. The Fe(II) induced transformation of ferrihydrite, was quantified in situ and under O2-free conditions using synchrotron-based time-resolved energy dispersive X-ray diffraction. At pH 9 and Fe(II)/Fe(III) ratios of 0.5 and 1, rapid growth (6 min) of sulphate green rust and its subsequent transformation to magnetite was observed. Electron microscopy confirmed these results, showing the initial rapid formation of hexagonal sulphate green rust particles, followed by the corrosion of the green rust as magnetite growth occurred, indicating that the reaction proceeds via a dissolution-reprecipitation mechanism. At pH 7 and Fe(II)/Fe(III) ratio of 0.5, sulphate green rust was the stable phase, with no transformation to magnetite.
Antimony(V) complexing with O-bearing organic ligands in aqueous solution: an X-ray absorption fine structure spectroscopy and potentiometric study
Authors: Tella M. , Pokrovski G. S.
Published: August 2008

The stabilityand structure of aqueous complexes formed by pentavalent antimony (SbV) with simple organic ligands (acetic, adipic, oxalic, citric acids, catechol and xylitol) having O-functional groups (carboxyl, alcoholic hydroxyl, aliphatic and aromatic hydroxyl) typical of natural organic matter (NOM), were determined at 25°C from potentiometric and X-ray absorption fine structure spectroscopy (XAFS) measurements. In organic-free aqueous solutions, spectroscopic data are consistent with the dominant formation of SbV hydroxide species, Sb(OH)5 and Sb(OH)6-, at acid and near-neutral to basic pH, respectively. Potentiometric measurements demonstrate negligible complexing with mono-functional organic ligands (acetic) or those having non-adjacent carboxylic groups (adipic). In contrast, in the presence of poly-functional carboxylic, hydroxyl carboxylic acids and aliphatic and phenolic hydroxyl, SbV forms stable 1:1 or 1:3 complexes in coordination 6 with the studied organic ligands, over a wide pH range pertinent to natural waters (3 ≤ pH ≤ 9). The XAFS measurements show that in these species the central SbV atom has an octahedral geometry with 6 oxygen atoms from hydroxyl moieties and adjacent functional groups (O = C—OH and/or C—OH) of the ligand, forming bidendate chelate cycles. Stability constants for SbV-oxalate complexes generated from potentiometric experiments were used to model SbV complexing with di-carboxylic functional groups of natural humic acids. Our predictions show that in an aqueous solution of pH between 1 and 4 containing 1 μg/l of Sb and 5 mg/l of dissolved organic carbon (DOC), up to 15% of total dissolved Sb maybe bound to aqueous organic matter via di-carboxylic groups.
The metagenomics of biosilicification: causes and effects
Authors: Benning L. G. , Tobler D. J.
Published: August 2008

In order to determine the links between geochemical parameters controlling the formation of silica sinter in hot springs and their associated microbial diversity, a detailed characterisation of the waters and of in situ-grown silica sinters was combined with molecular phylogenetic analyses of the bacterial communities in Icelandic geothermal environments. At all but one site, the microorganisms clearly affected, and in part controlled, the formation of the macroscopic textures and structures of silica sinter edifices. In addition, the class and genera level phylogenetic diversity and distribution appeared to be closely linked to variations in temperature, salinity and pH regimes.
Weathering of sandstones studied from the composition of stream sediments of the Kupa River (Croatia)
Authors: Bilinski H.
Published: August 2008

Elemental compositions of the <2mm fraction of three sediments sampled along the Kupa River are presented. On plots of log(SiO2/Al2O3) vs. log(CaO+Na2O)/K2O, the sediments plot closest to average sandstone compositions. On plots of weathering indices A vs. B (Kronberg and Nesbitt, 1981) the sediments plot close to basalt, terrestrial crust and granite. X-ray diffraction of the <63 μm fraction suggests chlorite, vermiculite and mica are present as weathering products in the upper, middle and lower stream sediments. Depletion of some elements in the sediments suggests loss of elements from the sediments due to dissolution of minerals.
Chemical composition of enamel and dentine in modern reptile teeth
Authors: Dauphin Y. , Williams C. T.
Published: August 2008

Elemental distribution maps by wavelength-dispersive electron microprobe of enamel and dentine in modern crocodile teeth illustrate variations in both minor and major elements. Mg has the largest difference between the enamel and dentine, being enriched in the dentine. Mg, Ca and P are not homogeneously distributed in the dentine, but their distribution reflects changes during growth of the teeth. These variations in compositional differences of teeth from modern samples potentially can assist in establishing growth rates in fossil teeth samples, and thereby provide information on the physiology of extant species.
Calcite crystal growth orientation: implications for trace metal uptake into coccoliths
Authors: Payne V. E. , Rickaby R. E. M. , Benning L. G. , Shaw S.
Published: August 2008

Inorganic calcite precipitation experiments were conducted to determine whether inducing specific orientations of calcite crystal growth can cause the enrichment of cations larger than Ca. Malonic acid (CH2(COOH)), a di-carboxylic acid, was used to poison growth on acute kink sites, promoting growth on obtuse kink sites, causing calcite crystals elongated along their c-axes to form in a mechanism similar to that seeninthe growth of E. huxleyi coccoliths. Calcite was precipitated with a range of malonic acid concentrations (0 to 10-1 M), and 9x10-5 M of either SrCl2 or MgCl2. The results show that calcite crystals precipitated in the presence of large malonic acid concentrations show significant elongation along the c axis, and suggest that increasing malonate concentrations corresponded with increasing DSr. Experiments with 10-1 M malonic acid caused elevated DSr comparable to that predicted for E. huxleyi coccolith calcite (Langer et al., 2006).
Kinetic and structural constraints during glauconite dissolution: implications for mineral disposal of CO2
Authors: Fernandez-Bastero S. , Gil-Lozano C. , Briones M. J. I. , Gago-Duport L.
Published: August 2008

The kinetics of glauconite dissolution have been determined in the pH range 2—10 (T = 25°C) using flow-batch reactor experiments. Besides the kinetic characteristics, the structural and textural aspects which could influence its long-term reactivity have also been characterized by means of X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and BET surface area measurements. The results from these analyses showed that glauconite follows a dual dissolution pathway which is pH-dependent, being more stable at neutral or slightly alkaline pH values. Under acidic conditions, glauconite is slightly more soluble than other ubiquitous silicates present in the marine sediments. The dissolution mechanism is incongruent at very acid pH values and tends to be congruent for intermediate and neutral ones. In addition, the results from the structural analyses suggest that the dissolution is a two-step process: the first one involves the disorder of the octahedral and tetrahedral layers, probably following a turbostratic mechanism which is evident in the XRD spectra as selective broadening of several reflections. In the second step, the dissolution of the cations from interlayer positions takes place and leads to the formation of an amorphous residue which acts as a passivating layer and reduces the reactive surface considerably. The influence of these aspects on CO2 capture via carbonation reactions is discussed.
Trees and late Palaeozoic CO2 and O2
Authors: Berner R. A.
Published: August 2008

The rise and evolution of large vascular land plants (mainly trees) during the mid-to-late Palaeozoic resulted in increased consumption of atmospheric CO2 by accelerated silicate rock weathering followed by further consumption due to increased terrestrially-derived organic matter burial in sediments, with the latter accompanied by increased production of O2. Changes in CO2 and O2 have been treated theoretically in terms of carbon- and sulphur-cycle modelling (Berner and Kothavala, 2001; Berner, 2006a,b). The CO2 modelling rests on the palaeobotanical record, field observations of the effect of trees on the rate of modern silicate weathering, and calculation of global organic matter burial based on the carbon isotopic record derived from carbonate fossils.
Fe isotope fractionation between inorganic aqueous Fe(III) and a Fe siderophore complex
Authors: K. Dideriksen  , Baker J. A. , Stipp S. L. S.
Published: August 2008

In oxic waters, dissolved Fe exists dominantly as Fe(III) complexes with strongly coordinating, siderophore-like ligands. In this study, we have determined an equilibrium Fe isotope fractionation of 0.6% (∆56Fe) between inorganic Fe(III) and Fe(III) siderophore complexes using the siderophore desferrioxamine B as a model compound. The 57Fe tracer experiments show that the Fe isotopes ofthe siderophores exchange readily with dissolved inorganic Fe. The results indicate that organic ligands are likely to be important in the generation ofFe isotope signatures in oxic environments. For example, the isotopic composition ofmarine Fe-Mn nodules may largely be due to the presence of strongly coordinating ligands.
The feedback between climate and weathering
Authors: Gislason S. R. , Oelkers E. H. , Eiriksdottir E. S. , Kardjilov M. I. , Gisladottir G. , Sigfusson B. , Snorrason A. , Elefsen S. , Hardardottir J. , Torssander P. , Oskarsson N.
Published: August 2008

Long-term climate moderation is commonly attributed to chemical weathering; the greater the temperature and precipitation the faster the weathering rate. To test this widely-held hypothesis, we performed a field study and determined the weathering rates of eight nearly pristine north-east Iceland river catchments with varying glacial cover over 44 y. Statistically significant linear positive correlations were found between mean annual temperature and chemical weathering in all eight catchments and between mean annual temperature and mechanical weathering and runoff in seven of the eight catchments. The runoff, mechanical weathering flux, and chemical weathering fluxes in these catchments are found to increase from 6 to 16%, 8 to 30%, and 4 to 14%, respectively, depending on the catchment for each degree of temperature increase. Positive correlations were found between time and mechanical and chemical weathering for all catchments. In summary, these results demonstrate a significant feedback between climate and Earth surface weathering, and suggest that this weathering rate is currently increasing with time due to global warming.
The role of earthworm communities in soil mineral weathering: a field experiment
Authors: Carpenter D. , Hodson M. E. , Eggleton P. , Kirk C.
Published: August 2008

Minerals are an important component of the soil environment (Dixonet al., 1977). They provide a structural framework which supports plants and contribute to the physical heterogeneity of soil. Minerals also contribute to the fertility of soils. Primary minerals are a source of essential plant nutrients (Harley and Gilkes, 2000). Clay minerals impact on the water-holding capacity of soils, affect the cation exchange capacity of soils (Brown, 1977) and are able to sequester nutrients and contaminants within the soil (Dubbin, 2001).
Phosphate mineral reactivity: from global cycles to sustainable development
Authors: Oelkers E. H. , Valsami-Jones E. , Roncal-Herrero T.
Published: August 2008

A survey of the surface-area-normalized dissolution rates of major phosphate bearing minerals shows these rates to vary by >8 orders of magnitude with a general dissolution-rate trend sturvite > britholite ∼ fluoroapatite > variscite > monazite ∼ rhabdophane. This trend reflects the relative strength of the metal-oxygen bonds holding together the phosphate tetrahedra in the mineral structure. Due to the high surface-area-normalized reactivity of fluoroapatite, and the high surface area of natural variscite and rhabdophane, it seems likely that these minerals buffer the concentration of P and the rare-earth elements in many natural waters. As such, the solubility of these minerals plays a significant role in the global phosphorus cycle, and may potentially provide clues for future sustainable phosphorus use.
Investigation of climate change and history of lead deposition using soil archives
Authors: Pampura T. , Demkin V. , Probst A.
Published: August 2008

Our study focused on the investigation of climate change and the fate of lead in soils from the Low Volga region of Russia over 3500 years. We used a comparative analysis of the modern soils and palaeosols preserved under burial mounds, which date back to the Middle Ages and the Early Iron and Bronze Ages. A climate reconstruction showed periodic changes, with the most humid climate conditions occurring during Golden Horde period. However, we could not find any consistent changes in Pb concentration and profile distribution following the climate change. We observed a clear difference in Pb isotopic ratios between the lower and upper horizons both for the modern and buried profiles, reflecting the influence of atmospheric lead depositions. However, there is no statistically significant difference in Pb isotopic ratios between the upper horizons of buried and modern soils (except modern soils collected in the vicinity of a motorway). This means that either anthropogenic input due to long range air transport was insignificant, or that airborne anthropogenic lead and natural airborne lead have similar isotopic composition.
Nanoparticulate bioavailable iron minerals in icebergs and glaciers
Authors: Raiswell R. , Benning L. G. , Davidson L. , Tranter M.
Published: August 2008

Ice-hosted sediments in glaciers and icebergs from Antarctica and Svalbard contain authigenic nanoparticulates of schwertmannite, ferrihydrite and goethite that formed during sulphide oxidation. These phases indicate the existence of subglacial biogeochemical hotspots containing fluids of low pH (2—4), rich in dissolved Fe(III) and sulphate. Nanophase Fe is partially bioavailable and potentially important to global biogeochemical cycles, since the flux delivered by icebergs to the Southern Ocean is comparable to the flux of soluble, bioavailable Fe from aeolian dust.
Uranium mobility in subsurface aqueous systems: the influence of redox conditions
Authors: Bots P. , Behrends T.
Published: August 2008

Uranium is a redox-sensitive element and can be immobilized by reduction from soluble U(VI) to insoluble U(IV). By performing flow-through experiments, uranium mobility was observed under different redox conditions. Inflow solutions with different electron acceptors, nitrate and sulphate, and a control inflow solution were used to obtain different sedimentary redox conditions. Uranium was about one order more mobile when nitrate was used than when sulphate or the control was used. The difference in uranium mobility is attributed to the reduction of uranium. Even though uranium mobility is heavily dependent on the redox state of uranium, sedimentary concentrations of organic matter argue that organic matter is the most important complexing agent and that this determines the retardation of uranium.
Adsorption studies of Mo and Vonto ferrihydrite
Authors: Brinza L. , Benning L. G. , Statham P. J.
Published: August 2008

In this paper, the kinetics of Mo and V (100 μM) uptake on ferrihydrite (FHY) were evaluated in batch, mono-sorbate systems at pH between 4 and 9, and in bi-sorbate systems in the presence of P (100 μM) at pH 7. In the Mo and V single-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero charge (PZC = 7.97) of FHY, the adsorption efficiency for Mo dropped dramatically (20% at pH 8) while V showed high uptake efficiencies even at pH 9 (60% efficiency). The results from the bi-sorbate experiments (Mo-P and V-P) showed that at pH 7, P out-competed (97%) Mo for binding sites on FHY, while in the V-P binary system only ∼44% of the binding sites are occupied by P with the remaining sites being occupied by V.
Uptake of Cd from seawater by calcite
Authors: Carneiro J. , Stoll H. , Prieto M.
Published: August 2008

Experimental geochemical studies have shown the effectiveness of Cd removal from freshwaters by sorption onto calcite and aragonite. The strong affinity of Cd for these minerals suggests that a similar inorganic uptake could take place in the oceans. In this study, we have carried out sorption experiments by reacting calcite particles with Cd-enriched artificial seawater. Cadmium concentrations in solution were determined by ICP-AES. Salinity-normalized Cd concentrations showed an average net decrease of 30%. Depending on several factors, this inorganic uptake could influence the seawater concentrations of Cd in certain locations, and even contribute to a natural regulation of the concentration of this metal in the oceans.
Hydrochemical characteristics of the natural waters associated with the flooding of the Meirama open pit (A Coruñ, NW Spain)
Authors: Delgado J. , Juncosa R. , Vazquez A. , Falcón I. , Canal J. , Hernández H. , Padilla F. , Rodríguez-Vellando P. , Delgado J. L.
Published: August 2008

In December, 2007, after 30 years of operations, the mine of Meirama ceased extraction of brown lignite. Since then operations have begun which will lead to the formation of a big mining lake (~2 km2 surface and up to 180 m deep) after controlled flooding of the open pit. In the process of flooding, both surface and ground waters are involved, each with their own chemical signature. According to the information available, the diversion of surface waters towards the pit hole should lead to the formation of a water body of acceptable quality. However, an unassisted flooding process could eventually form an acidic lake.
Secondary sulphate precipitates in the gravel pit at Kumpuselkä esker, northern Finland
Authors: Eskola T. , Peuraniemi V.
Published: August 2008

White and yellowish precipitates were found in a gravel pit in the Kumpuselkäesker chain during the summers of 2004—2007. The esker is located in northern Finland, in the northern Ostrobothnia schist area which contains mica schists with quartz veins, which are locally enriched in Co, Cu, Au, Zn, Pb and Ni. A thin till bed lies between the esker gravel and bedrock. Precipitates were found as small grains on the till surface, encrusting twigs and around small pebbles. Ground-water ponds in the pit measured in the summer of 2006 were very acidic as was the till material. The precipitates comprise secondary sulphates, such as gypsum, pickeringite and Mg-sulphates, which are all water-soluble.
A logistic regression method for mapping the As hazard risk in shallow, reducing groundwaters in Cambodia
Authors: Rodríguez Lado L. , Polya D. A. , Hegan A.
Published: August 2008

We combined statistical analyses and GIS capabilities within the statistical environment R to create a semi-automated method for the assessment of As hazard risk in shallow groundwater in Cambodia. Arsenic concentration data for groundwaters of between 16 and 100 m depth were obtained from 1437 geo-referenced wells. We created a binary logistic regression model with these As measurements as the dependent variable and a number of raster maps (DEM-parameters, remote sensing images and geomorphology) as explanatory variables, and considering an As threshold of 10 ppb. This allowed us to make an As hazard map for groundwaters between 16—100 m depth: this can be used to help to identify populations vulnerable to exposure. The logistic regression analysis indicates a good correlation between topographic and geomorphologic environmental variables and the As hazard risk in groundwater. Ease of implementation, and the ability to update, along with objectivity and reproducibility are the main advantages related to this method of analysis.
Transformation of calcium carbonate polymorphs: preliminary results
Authors: Nissenbaum J. , Stipp S. L. S. , Johnnson A.
Published: August 2008

Calcium carbonate forms three polymorphic minerals that are found in a variety of environments at the Earth’s surface. Other compounds in the aqueous system can inhibit or enhance the probability of one phase or another, favour growth of specific crystal faces, and change the rate of recrystallization. Control of crystal systems requires understanding of the relationships between the foreign agent and the CaCO3 mineral surface. This work, which examines the transformation of vaterite to calcite, is part of a larger project that aims to define some of the parameters that control calcite recrystallization and grain coarsening.
Endocrine disrupting substances in the late anthropocene and breast and prostate cancer
Authors: Plant J. , Mckinlay A. R. , Voulvoulis N.
Published: August 2008

The steroid hormones and their cellular receptors responsible for the sexual development and activity ofh umans and other vertebrates evolved in the late Precambrian—Cambrian and have remained unchanged since that time. Growth factors, which are small molecular weight proteins responsible for growth, sexual maturation and also for the cell cycle whereby cells replicate themselves evolved at around the same time. The molecular structures of hormones and growth factors in different vertebrates are essentially the same, so that a chemical capable of causing harmful effects in one species is likely to cause ill effects in other, even taxonomically distinct, species. The particular effects can vary because individual hormones and growth factors are associated with different functions in different species.
Nanomaterial synthesis and characterization for toxicological studies: TiO2 case study
Authors: Valsami-Jones E. , Berhanu D. , Dybowska A. , Misra S. , Boccaccini A. R. , Tetley T. D. , Luoma S. N. , Plant J. A.
Published: August 2008

In recent years it has become apparent that the novel properties of nanomaterials may predispose them to a hitherto unknown potential for toxicity. A number of recent toxicological studies of nanomaterials exist, but these appear to be fragmented and often contradictory. Such discrepancies may be, at least in part, due to poor description of the nanomaterial or incomplete characterization, including failure to recognise impurities, surface modifications or other important physicochemical aspects of the nanomaterial. Herew em ake a casef or the importance of good quality, well-characterized nanomaterials for future toxicological studies, combined with reliable synthesis protocols, and we present our efforts to generate such materials. The model system for which we present results is TiO2 nanoparticles, currently used in a variety of commercial products.
Metal-contaminant leaching from lead smelter fly ash using pH-stat experiments
Authors: Vítková M. , Ettler V. , Šebek O. , Mihaljevič M.
Published: August 2008

Fly ash from secondary Pb metallurgy was submitted to the pH-static leaching procedure according to the PrEN 14997 European leaching standard. The 48 h pH-static leaching experiments were performed on (1) fresh untreated fly ash and (2) previously washed fly ash with a cumulative wash step of 60 l kg-1. Greater release ofmetallic contaminants (Pb, Cd, Zn) was observed in the acidic pH range for both ashes. Washing significantly reduced the release of Cd and Zn, but greater concentrations of Pb were observed in leachates from washed fly ash due to the more important leaching of anglesite (PbSO4). The PHREEQC-2 speciation-solubility calculations showed that anglesite, phosgenite (PbCl2·PbCO3) and laurionite (Pb(OH)Cl) are the most important solubility-controlling phases for Pb, which is the most important contaminant.
A computer-modelling study of CdCO3-CaCO3 solid solutions
Authors: Wang Q. , de Leeuw N. H.
Published: August 2008

We have applied atomistic simulation techniques to model the continuous CdCO3-CaCO3 solid solution and to investigate the thermodynamic properties. All inequivalent substitutional configurations were considered for the single unit cell and the (2x1x1) supercell for the full range of Cd concentrations, as well as doping between 0and 16.7 mol.% Cd for the (2x2x1) supercell. Our calculations show that segregation of Cd2+ and Ca2+ is energetically favourable when compared with any other cation distribution. No cation ordering is expected at high temperature and the system behaves as an ideal solid solution above 200 K, due to the configurational entropy. The lattice parameters change with the Cd concentration, where they are predicted to follow a linear relationship, due only to cation substitution but not cation ordering.
Numerical modelling of CO2-water-basalt interaction
Authors: Gysi A. P. , Stefánsson A.
Published: August 2008

The effects of CO2on water-basaltic glass interaction have been simulated at 25ºC. The calculations indicate that addition of CO2(2—30 bar) to water significantly changes the reaction path. Initially, the pH is buffered between 4 and 6 by CO2ionization, with dissolution of basaltic glass and the formation of secondary minerals with SiO2, Mg-Fe carbonates and dolomite predominating. Upon the dissolution of additional basaltic glass and mineral fixation of CO2, the pH increases to >8 and (Ca)-Fe-Mg smectites, SiO2, Ca-Na zeolites and calcite become the dominant secondary minerals forming. The overall reaction path depends on the initial water composition, reactive surface area, and the composition of the phyllosilicates and carbonates forming. The key factors are the mobility of Mg2+, Fe2+and Ca2+and the competing reactions for these solutes among secondary minerals.
Critical Zone Observatories: Building a network to advance interdisciplinary study of Earth surface processes
Authors: Anderson S. P. , Bales R. C. , Duffy C. J.
Published: August 2008

We live at the dynamic interface between the solid Earth and its outer fluid envelopes. This interface, extending from the outer vegetation canopy to the base of active groundwater, was recently named the Critical Zone because it supports life and is increasingly impacted by human actions. Understanding the complex interactions between processes that operate in and shape the Critical Zone requires interdisciplinary approaches that span wide spatial and temporal scales. Tectonic processes, weathering, fluid transport, and biological processes control the function and structure of the Critical Zone. Three Critical Zone Observatories recently established by the U.S. National Science Foundation are designed to integrate studies of process interactions up to the watershed scale. A goal of the program is to build the three independently conceived observatories into a network from which broader understanding — larger spatial scales but also deeper insight — can emerge.
Biological weathering in soil: the role of symbiotic root-associated fungi biosensing minerals and directing photosynthate-energy into grain-scale mineral weathering
Authors: Leake J. R. , Duran A. L. , Hardy K. E. , Johnson I. , Beerling D. J. , Banwart S. A. , Smits M. M.
Published: August 2008

Biological weathering is a function of biotic energy expenditure. Growth and metabolism of organisms generates acids and chelators, selectively absorbs nutrient ions, and applies turgor pressure and other physical forces which, in concert, chemically and physically alter minerals. In unsaturated soil environments, plant roots normally form symbiotic mycorrhizal associations with fungi. The plants provide photosynthate-carbohydrate-energy to the fungi in return for nutrients absorbed from the soil and released from minerals. In ectomycorrhiza, one of the two major types of mycorrhiza of trees, roots are sheathed in fungus, and 15—30% of the net photosynthate of the plants passes through these fungi into the soil and virtually all of the water and nutrients taken up by the plants are supplied through the fungi. Here we show that ectomycorrhizal fungi actively forage for minerals and act as biosensors that discriminate between different grain sizes (53—90 μm, 500—1000 μm) and different minerals (apatite, biotite, quartz) to favour grains with a high surface-area to volume ratio and minerals with the highest P content. Growth and carbon allocation of the fungi is preferentially directed to intensively interact with these selected minerals to maximize resource foraging.
Unaltered repopulation properties of mouse hematopoietic stem cells transduced with lentiviral vectors
Authors: Gonzalez-Murillo Africa , Lozano M. Luz , Montini Eugenio , Bueren Juan A. , Guenechea Guillermo
Published: August 2008

Recent studies of retroviral-mediated gene transfer have shown that retroviral integrations themselves may trigger nonmalignant clonal expansion of hematopoietic stem cells (HSCs) in transplant recipients. These observations suggested that previous conclusions of HSC dynamics based on gamma-retroviral gene marking should be confirmed with improved vectors having a more limited capacity to transactivate endogenous genes. Because of the low trans-activation activity of self-inactivating lentiviral vectors (LVs), we have investigated whether the LV marking of mouse HSCs induces a competitive repopulation advantage in recipients of serially transplants. As deduced from analyses conducted in primary and secondary recipients, we concluded that lentivirally transduced HSCs have no competitive repopulation advantages over untransduced HSCs. By linear amplification-mediated polymerase chain reaction (LAM-PCR) analysis, we characterized LV-targeted genes in HSC clones that engrafted up to quaternary recipients. Although 9 clones harbored integrations close to defined retroviral insertion sites, none was characterized as a common integration site, and none was present in HSC clones repopulating quaternary recipients. Taken together, our results show unaltered repopulation properties of HSCs transduced with LVs, and confirm early studies suggesting the natural capacity of a few HSC clones to generate a monoclonal or oligoclonal hematopoiesis in transplant recipients.
Alternative splicing regulates activation-induced cytidine deaminase (AID): implications for suppression of AID mutagenic activity in normal and malignant B cells
Authors: Wu Xiaosheng , Darce Jaime R. , Chang Sook Kyung , Nowakowski Grzegorz S. , Jelinek Diane F.
Published: August 2008

The mutagenic enzyme activation-induced cytidine deaminase (AID) is required for immunoglobulin class switch recombination (CSR) and somatic hypermutation (SHM) in germinal center (GC) B cells. Deregulated expression of AID is associated with various B-cell malignancies and, currently, it remains unclear how AID activity is extinguished to avoid illegitimate mutations. AID has also been shown to be alternatively spliced in malignant B cells, and there is limited evidence that this also occurs in normal blood B cells. The functional significance of these splice variants remains unknown. Here we show that normal GC human B cells and blood memory B cells similarly express AID splice variants and show for the first time that AID splicing variants are singly expressed in individual normal B cells as well as malignant B cells from chronic lymphocytic leukemia patients. We further demonstrate that the alternative AID splice variants display different activities ranging from inactivation of CSR to inactivation or heightened SHM activity. Our data therefore suggest that CSR and SHM are differentially switched off by varying the expression of splicing products of AID at the individual cell level. Most importantly, our findings suggest a novel tumor suppression mechanism by which unnecessary AID mutagenic activities are promptly contained for GC B cells.