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Deep geological repository (DGR) is one of the internationally accepted options to dispose radioactive wastes. Bentonite formations from Almeria, Spain, were selected as reference material for artificial barriers for the future Spanish repository. However, the safety of this long-term disposal could be compromised not only by physicochemical factors but also by microbial processes. The highly radioactive waste must be safely stored at least for 100,000 years for the radioactivity to decrease to similar levels to those of natural uranium. To simulate a scenario where the mobilization of radionuclides from the repository to the host formations may occur, long-term microcosms were studied. After being exposed to uranyl nitrate for 5 months, the response of the bentonite microbial community to the addition of this radionuclide was evaluated. High throughput 16S rRNA gene sequencing revealed that the structure of the microbial community after the uranyl nitrate treatment differs to that of the control microcosms. The microbial diversity was dominated by Firmicutes and Proteobacteria. Moreover, after the uranyl nitrate treatment OTUs annotated as Paracoccus and Bacillus were highly enriched. The mineralogy of bentonites was not affected by the uranyl nitrate treatment as was demonstrated by X-ray diffraction analysis. In addition, the study of uranium-bacteria interaction revealed the ability of isolates to biomineralize uranium as uranium phosphate mineral phases. Thus, the changes induced by the release of uranium in the microbial population may also affect the mobility of this radionuclide, making it less mobile and therefore less harmful for this environment. [ABSTRACT FROM AUTHOR]

This study presents the effect of aqueous uranium speciation (U-hydroxides and U-hydroxo-carbonates) on the interaction of this radionuclide with the cells of the yeast Rhodotorula mucigilanosa BII-R8. This strain was isolated from Spanish bentonites considered as reference materials for the engineered barrier components of the future deep geological repository of radioactive waste. X-ray absorption and infrared spectroscopy showed that the aqueous uranium speciation has no effect on the uranium binding process by this yeast strain. The cells bind mobile uranium species (U-hydroxides and U-hydroxo-carbonates) from solution via a time-dependent process initiated by the adsorption of uranium species to carboxyl groups. This leads to the subsequent involvement of organic phosphate groups forming uranium complexes with a local coordination similar to that of the uranyl mineral phase meta-autunite. Scanning transmission electron microscopy with high angle annular dark field analysis showed uranium accumulations at the cell surface associated with phosphorus containing ligands. Moreover, the effect of uranium mobile species on the cell viability and metabolic activity was examined by means of flow cytometry techniques, revealing that the cell metabolism is more affected by higher concentrations of uranium than the cell viability. The results obtained in this work provide new insights on the interaction of uranium with bentonite natural yeast from genus Rhodotorula under deep geological repository relevant conditions. [ABSTRACT FROM AUTHOR]

Abstract: The problem of signal enhancement has been addressed by several authors in the past and continues to be of particular interest in many applications. In this respect, the present authors have been exploring the effect of the model based signal enhancement (MBSE) approach to recover the signal of blood glucose dynamics from noise contaminated measurements collected from seven healthy patients after an intravenous glucose tolerance test (IVGTT). These observations correspond to a system with an impulse–response behaviour for which it is often hypothesized that a sum of exponential signals can be used for modeling the data. The exponential model order has been derived from the singular value decomposition analysis of these data set. A linear version of the classic minimal model, known as the linear minimal model (LMM), has been used to model the patient’s behaviour. After fitting the LMM first to the experimental data and then to the MBSE signal obtained from the exponential modelling approximation, the effect on the precision of the LMM parameters has been statistically assessed. A non-parametric test has been devised to evaluate the significance of the differences between the precision obtained when no MBSE is applied and the precision after MBSE is performed. The results obtained suggest that the precision of the LMM parameters can be improved by more than 50% (p-value<0.01) for all the model parameters. In particular, the insulin sensitivity S I and glucose effectiveness S G parameters that are useful diagnostic indices in Type 2 Diabetes Mellitus are improved by 50% and 62% respectively. [Copyright &y& Elsevier]

This study demonstrates that the classic minimal model (MM) and the linear minimal model (LMM) are able to follow the dynamics of glucose in Type I diabetes. LMM precision is better than the MM with systematic lower mean values for the coefficient of variation (CV) in all characteristic model parameters. LMM is not significantly different from MM (units 1/min per , ) with a strong correlation ( = 0.83, ). LMM appears to be significantly different to (units 1/min, ) but correlates very well . Since residuals appear to be heteroscedastic, further work is required to address the effect of modeling and signal processing on them. For the data under study, the models are not able to fit two-thirds of the data windows available. This is because none of the models are able to follow complex situations such as the presence of several bolus injections, the absence of insulin supply or inappropriate insulin dosage. A synthesis of the patterns found in these windows is presented which would be useful for the development of new models for fitting these data. [Copyright &y& Elsevier]

As critical transition zones between the land and the sea, estuaries are not only hotspots of hydrogeochemical and microbial processes/reactions, but also play a vital role in processing and transferring terrestrial fluxes of metals and nutrients to the sea. This study focused on three estuaries in the Gulf of Bothnia. All of them experience frequent inputs of acidic and Mn/metal-rich creek waters due to flushing of acid sulfate soils that are widespread in the creekś catchments. Analyzing existing long-term water chemistry data revealed a strong seasonal variation of Mn loads, with the highest values in spring (after snow melt) and autumn (after heavy rains). We sampled surface waters, suspended particulate matter (SPM), and sediments from the estuarine mixing zones and determined the loads and solid-phase speciation of Mn as well as the composition and metabolic potentials of microbial communities. The results showed that the removal, cycling, and lateral transport of Mn were governed by similar phases and processes in the three estuaries. Manganese X-ray absorption spectroscopy data of the SPM suggested that the removal of Mn was regulated by silicates (e.g., biotite), organically complexed Mn(II), and MnOx (dominated by groutite and phyllomanganates). While the fractional amounts of silicate-bound Mn(II) were overall low and constant throughout the estuaries, MnOx was strongly correlated with the Mn loadings of the SPM and thus the main vector for the removal of Mn in the central and outer parts of the estuaries, along with organically complexed Mn(II). Down estuary, both the fractional amounts and average Mn oxidation state of the MnOx phases increased with (i) the total Mn loads on the SPM samples and (ii) the relative abundances of several potential Mn-oxidizing bacteria (Flavobacterium, Caulobacter, Mycobacterium, and Pedobacter) in the surface waters. These features collectively suggested that the oxidation of Mn, probably mediated by the potential Mn-oxidizing microorganisms, became more extensive and complete towards the central and outer parts of the estuaries. At two sites in the central parts of one estuary, abundant phyllomanganates occurred in the surface sediments, but were converted to surface-sorbed Mn(II) phases at deeper layers (>3–4 cm). The occurrence of phyllomanganates may have suppressed the reduction of sulfate in the surface sediments, pushing down the methane sulfate transition zone that is typically shallow in estuarine sediments. At the outermost site in the estuary, deposited MnOx were reduced immediately at the water–sediment interface and converted most likely to Mn carbonate. The mobile Mn species produced by the Mn reduction processes (e.g., aqueous Mn(II) and ligand complexed Mn(III)) could partly diffuse into the overlying waters and, together with the estuarine Mn loads carried by the surface waters, transfer large amounts of reactive Mn into open coastal areas and subsequently contribute to Mn shuttling and inter-linked biogeochemical processes over the seafloor. Given the widespread occurrence of acid sulfate soils and other sulfidic geological materials on many coastal plains worldwide, the identified Mn attenuation and transport mechanisms are relevant for many estuaries globally. [ABSTRACT FROM AUTHOR]

The multi-barrier deep geological repository system is currently considered as one of the safest option for the disposal of high-level radioactive wastes. Indigenous microorganisms of bentonites may affect the structure and stability of these clays through Fe-containing minerals biotransformation and radionuclides mobilization. The present work aimed to investigate the behavior of bentonite and its bacterial community in the case of a uranium leakage from the waste containers. Hence, bentonite microcosms were amended with uranyl nitrate (U) and glycerol-2-phosphate (G2P) and incubated aerobically for 6 months. Next generation 16S rRNA gene sequencing revealed that the bacterial populations of all treated microcosms were dominated by Actinobacteria and Proteobacteria, accounting for >50% of the community. Additionally, G2P and nitrate had a remarkable effect on the bacterial diversity of bentonites by the enrichment of bacteria involved in the nitrogen and carbon biogeochemical cycles (e.g. Azotobacter). A significant presence of sulfate-reducing bacteria such as Desulfonauticus and Desulfomicrobium were detected in the U-treated microcosms. The actinobacteria Amycolatopsis was enriched in G2P‑uranium amended bentonites. High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy analyses showed the capacity of Amycolatopsis and a bentonite consortium formed by Bradyrhizobium-Rhizobium and Pseudomonas to precipitate U as U phosphate mineral phases, probably due to the phosphatase activity. The different amendments did not affect the mineralogy of the bentonite pointing to a high structural stability. These results would help to predict the impact of microbial processes on the biogeochemical cycles of elements (N and U) within the bentonite barrier under repository relevant conditions and to determine the changes in the microbial community induced by a uranium release. Unlabelled Image • U and G2P exposure shaped the bentonite bacterial community under DGR concept. • Stability of bentonite mineralogy was showed. • Bacteria with impact on the biogeochemical cycle of U and N were enriched. • U phosphate biomineralization by bentonite isolates was demonstrated. [ABSTRACT FROM AUTHOR]

Uranium (U) is the most hazardous radionuclide in nuclear waste and its harmful effects depend on its mobility and bioavailability. Microorganisms can affect the speciation of radionuclides and their migration in Deep Geological Repositories (DGR) for high level radioactive waste (HLW) storage. Consequently, a better understanding of microbe-radionuclide interactions within a DGR concept is essential for a safe storage. With that in mind, bentonite microcosms amended with uranyl nitrate and glycerol-2-phosphate were incubated for six months under anoxic conditions. Post-incubation 16S rRNA gene sequencing revealed high microbial diversities including glycerol oxidizers such as Clostridium and Desulfovibrio and nitrate reducers (Limnobacter and Brevundimonas). In addition, uranium-reducing bacteria (Desulfovibrio and Pseudomonas) were highly enriched in glycerol-2-phosphate‑uranium amended microcosms. These bacteria may contribute to uranium immobilization through enzymatic reduction and/or biomineralization. Scanning electron microscopy of colored spots on the surface of the bentonite in the microcosms indicated the probable formation of Mn(IV) oxides likely through the activity of Mn(II)-oxidizing microbes. This could affect the biogeochemical cycle of U(VI) by concentrating and immobilizing this element in the bentonites. Finally, X-ray diffraction determined a high structural stability of bentonites. The outputs of this study help to predict the impact of microbial activity (e.g. smectite alteration, metal corrosion, and radionuclides mobilization) on the long-term performance of a DGR and to develop appropriate waste treatments, remediation, and management strategies. [Display omitted] • U and G2P exposure shaped the bacterial community in anoxic bentonite microcosms. • Bacteria with the potential to affect the biogeochemical cycle of U were enriched. • Pseudomonas and Desulfovibrio were abundantly found in G2P and U-treated microcosms. • No differences to bentonite mineralogy were observed in presence of U and G2P. • Colored spots could indicate the precipitation of Mn(IV) oxides. [ABSTRACT FROM AUTHOR]

Strains of a dinoflagellate from the Salton Sea, previously identified as Protoceratium reticulatum and yessotoxin producing, have been reexamined morphologically and genetically and Pentaplacodinium saltonense n. gen. et sp. is erected to accommodate this species. Pentaplacodinium saltonense differs from Protoceratium reticulatum (Claparède et Lachmann 1859) Bütschli 1885 in the number of precingular plates (five vs. six), cingular displacement (two widths vs. one), and distinct cyst morphology. Incubation experiments (excystment and encystment) show that the resting cyst of Pentaplacodinium saltonense is morphologically most similar to the cyst-defined species Operculodinium israelianum (Rossignol, 1962) Wall (1967) and O. psilatum Wall (1967). Collections of comparative material from around the globe (including Protoceratium reticulatum and the genus Ceratocorys ) and single cell PCR were used to clarify molecular phylogenies. Variable regions in the LSU (three new sequences), SSU (12 new sequences) and intergenic ITS 1–2 (14 new sequences) were obtained. These show that Pentaplacodinium saltonense and Protoceratium reticulatum form two distinct clades. Pentaplacodinium saltonense forms a monophyletic clade with several unidentified strains from Malaysia. LSU and SSU rDNA sequences of three species of Ceratocorys ( C. armata, C. gourreti, C. horrida ) from the Mediterranean and several other unidentified strains from Malaysia form a well-supported sister clade. The unique phylogenetic position of an unidentified strain from Hawaii is also documented and requires further examination. In addition, based on the V9 SSU topology (bootstrap values >80%), specimens from Elands Bay (South Africa), originally described as Gonyaulax grindleyi by Reinecke (1967), cluster with Protoceratium reticulatum . The known range of Pentaplacodinium saltonense is tropical to subtropical, and its cyst is recorded as a fossil in upper Cenozoic sediments. Protoceratium reticulatum and Pentaplacodinium saltonense seem to inhabit different niches: motile stages of these dinoflagellates have not been found in the same plankton sample. [ABSTRACT FROM AUTHOR]