Marine ferromanganese crusts and nodules as potential mineral deposits have received increasing attention. However, much less knowledge is available concerning the incorporation and enrichment ...mechanisms for antimony (Sb) and arsenic (As) in marine ferromanganese oxides. In this study, the surface complexations of Sb(V) and As(V) on synthetic ferrihydrite and Mn oxides (δ-MnO2 and birnessite) were investigated by a combination of adsorption experiments, extended X-ray absorption fine structure (EXAFS) analyses, and quantum chemical calculations. The speciation, distribution, and local structure of Sb and As in different types of natural marine ferromanganese oxides were determined by X-ray absorption near edge structure (XANES) and EXAFS analyses to reveal the enrichment mechanisms for the two elements in ferromanganese oxides at the molecular level. To the best of our knowledge, the Sb EXAFS analyses for different types of marine ferromanganese oxides are herein reported for the first time. Results showed that Sb(V) is preferentially adsorbed on Mn oxides through energetically favorable bidentate–mononuclear complexation because of the structural similarity between the octahedron SbV(OH)6− and MnO6 unit, although bidentate–binuclear (corner-sharing) and bidentate–mononuclear (edge-sharing) complexes can be formed on ferrihydrite and Mn oxides for the adsorption of Sb(V). By contrast, tetrahedral AsVO43− is mostly adsorbed on ferrihydrite and Mn oxides with the formation of bidentate–binuclear complexes. In natural marine ferromanganese oxides, Sb and As can be retained by Fe and Mn (oxyhydr)oxide components, and the disparate distribution of the two elements to Mn oxides may largely depend on the Mn/Fe ratio and constituent minerals. The larger enrichment factor of Sb than that of As in marine ferromanganese oxides may result from their preferential attachment modes onto the Fe and Mn phases and different inhibition effects from coexisting anions in seawater. Compared with As, a part of Sb may be strongly associated with the lateral sites in Mn oxides via the formation of bidentate edge-sharing complexes, with which anions such as sulfate in seawater do not significantly compete. The findings from this study provide the molecular-scale insights into the enrichment processes and mechanisms of Sb and As in marine ferromanganese oxides. Our study also helps elucidate the incorporation mechanisms and geochemical behaviors of other oxyanions in marine and surface environments.
This study analyzes the impact of experiencing a disaster on subsequent risk recognition and evacuation behavior using data collated from the interview of victims of the flood and landslides that ...followed the 2014 Hiroshima Heavy Rain Disaster. The high accuracy of the storm and flood damage prediction system has made it possible to limit human casualties by routinizing advance evacuation behavior. The study explores conditions for the routinization of evacuation behavior and its findings are as follows: (i) a series of experiences such as timing of incidental awareness, evacuation, housing damage, and human damage define the damage recognition of each victim. The difference between each damage recognition has different influences on their post-disaster risk recognition and behaviors; (ii) experiencing severe disasters generally enhances disaster risk recognition. However, whether it promotes advanced evacuation behavior is dependent on the magnitude of the damage and pre-disaster risk recognition. If risk recognition is ambiguous, the effect of the experience is minimal even if the damage is severe; (iii) for disaster victims to inculcate an evacuation behavior in preparation for the next disaster, they must first have clear pre-disaster risk recognition mechanisms. It is also necessary to have a reliable destination that is incorporated into the daily life of the residents, which can serve as an evacuation site.
Apoptotic cells expose phosphatidylserine and are swiftly engulfed by macrophages. Milk fat globule epidermal growth factor (EGF) factor 8 (MFG-E8) is a protein that binds to apoptotic cells by ...recognizing phosphatidylserine and that enhances the engulfment of apoptotic cells by macrophages. We report that tingible body macrophages in the germinal centers of the spleen and lymph nodes strongly express MFG-E8. Many apoptotic lymphocytes were found on the$MFG-E8^{-/-}$tingible body macrophages, but they were not efficiently engulfed. The$MFG-E8^{-/-}$mice developed splenomegaly, with the formation of numerous germinal centers, and suffered from glomerulonephritis as a result of autoantibody production. These data demonstrate that MFG-E8 has a critical role in removing apoptotic B cells in the germinal centers and that its failure can lead to autoimmune diseases.
Several recent studies have reported a strong association between Sc and goethite (α-FeOOH) in synthetic analogs and natural samples. However, the mechanism of Sc immobilization by goethite and ...controlling factors remain unclear. This study investigated the adsorption behavior and molecular-scale immobilization mechanisms of Sc at water/goethite interfaces through a combination of batch adsorption and desorption experiments, X-ray absorption fine structure (XAFS) analyses, and density functional theory (DFT) calculations. Results indicate that Sc is preferentially adsorbed on goethite with the formation of bidentate-binuclear inner-sphere complexes at the corner-sharing sites. Bulk Sc K-edge XAFS analyses suggest that Sc is incorporated into the goethite structure by substituting for Fe(III) within the crystal in synthetic Sc-substituted goethite, which is further confirmed in natural goethite particles in the laterite by using micro-focused XAFS (μ-XAFS). Furthermore, we demonstrate that the adsorbed Sc on the goethite surface can be structurally incorporated into the goethite lattice in the presence of aqueous Fe(II) possibly through goethite recrystallization induced by aqueous Fe(II). This process may affect the (re)partitioning of Sc between the goethite surface and the mineral bulk, which could be used to rationally explain disparate Sc speciation in laterites from different regions. Our study elucidates the molecular-scale mechanisms underlying Sc adsorption on and structural incorporation into goethite, providing critical insights into the understanding of geochemical behavior and environmental fates of Sc.
This study examined the radiocesium (RCs) interception potential (RIP), cation exchange capacity (CEC), total organic carbon (TOC) content, and adsorption species in soils and minerals by using ...extended X-ray absorption fine structure (EXAFS) spectroscopy. The RIP related to Cs+ adsorption by frayed-edge site (FES) has often been used to measure the mobility and bioavailability of RCs in the environment. This study found that the presence of organic matter (OM) can reduce RIP to a certain extent. The adsorption amount (=QT) in soil was obviously correlated to RIP at a small Cs+ region, whereas a linear relationship between QT and CEC was observed at a large Cs+ region. Both the inner-sphere (IS) and outer-sphere (OS) complexes of Cs+ were observed through EXAFS at a molecular scale. The linear correlation between log (RIP/CEC) and the ratio of the coordination number (CN) of IS (=CNIS) and OS (=CNOS) complexes noted as CNIS/(CNIS + CNOS) suggested that the ratio of CN is very sensitive to Cs+ adsorption species with variable RIP and CEC. The adsorption species of Cs+ in soil was mainly dependent on the clay mineral content of soil. RIP was affected not only by FES but also by other strong adsorption sites, such as the interlayers and cavities identified as the IS complex in EXAFS analysis. Findings indicated that the EXAFS approach is a powerful and efficient tool to explore the behavior of Cs+ in a given environment.
Display omitted
•The relationship of Cs+ species on soils and minerals and RIP was firstly clarified in this study.•Coordination number of Cs+ was very sensitive to Cs+ adsorption species with variable RIP and CEC.•This finding can be used as a basis for understanding of Cs+ behavior in nature.
Consecutive cohort study.
To reconsider effects of the Second National Acute Spinal Cord Injury Study.
High dose methylprednisolone sodium succinate (MPSS) for the patients with acute spinal cord ...injury has been considered standard treatment in the several countries. However, many authors have criticized the effect of MPSS because of lack of evidence about neurologic improvement and the high incidence of complications.
During 2-year, all patients with cervical cord injury were treated with MPSS within 8 hours of their injuries based on the Second National Acute Spinal Cord Injury Study protocol (MPSS group). During the next 2-year, all patients were treated without MPSS (non-MPSS group). There were 38 patients in the MPSS group and 41 in the non-MPSS. Early spinal decompression and stabilization was performed as soon after injury in both the groups.
According to The American Spinal Injury Association (ASIA) motor score, there was an average improvement by 3 months postinjury of 12.4 points in the MPSS group and 13.8 points in the non-MPSS group. In patients with complete motor loss, average ASIA motor score improved 9.0 points in the MPSS group and 12.6 points in the non-MPSS group. For patients with incomplete motor loss, average ASIA motor score improvement was 14.1 and 15.5 points in the MPSS and non-MPSS groups, respectively.In the MPSS group, 19 patients developed pneumonia, 13 developed urinary tract infections, and 5 developed wound infections. Incidence of pneumonia was significantly increased with the use of MPSS medication.
We found no evidence supporting the opinion that high-dose MPSS administration facilitates neurologic improvement in patients with spinal cord injury. We believe MPSS should be used under limited circumstances because of the high incidence of pulmonary complication.
In this paper, novel implementation schemes for the automatic calculation of internal variables, stresses and consistent tangent moduli for incremental variational formulations (IVFs) describing ...inelastic material behavior are proposed. IVFs recast inelasticity theory as an equivalent optimization problem where the incremental stress potential within a discrete time interval is minimized in order to obtain the values of internal variables. In the so-called Multilevel Newton–Raphson method for the inelasticity theory, this minimization problem is typically solved by using second derivatives with respect to the internal variables. In addition to that, to calculate the stresses and moduli further second derivatives with respect to deformation tensors are required. Compared with classical formulations such as the return mapping method, the IVFs are relatively new and their implementation is much less documented. Furthermore, higher order derivatives are required in the algorithms demanding increased implementation efforts. Therefore, even though IVFs are mathematically and physically elegant, their application is not standard. Here, novel approaches for the implementation of IVFs using HDNs of second and higher order are presented to arrive at a fully automatic and robust scheme with computer accuracy. The proposed formulations are quite general and can be applied to a broad range of different constitutive models, which means that once the proposed schemes are implemented as a framework, any other dissipative material model can be implemented in a straightforward way by solely modifying the constitutive functions. These include the Helmholtz free energy function, the dissipation potential function and additional side constraints such as e.g. the yield function in the case of plasticity. Its uncomplicated implementation for associative finite strain elasto-plasticity and performance is illustrated by some representative numerical examples.
Injection of apoptotic cells can induce suppression of immune responses to cell-associated antigens. Here, we show that intravenous injection of apoptotic cells expressing a fragment of myelin ...oligodendrocyte glycoprotein (MOG) reduced MOG-specific T cell response and prevented the development of EAE. Since injected apoptotic cells accumulated initially in the splenic marginal zone (MZ), the role of macrophages in the MZ in immune suppression was examined using transgenic mice in which these cells could be transiently deleted by diphtheria toxin (DT) injection. DT-treated mice became susceptible to EAE even though MOG-expressing apoptotic cells were preinjected. Deletion of the macrophages caused delayed clearance of injected dying cells in the MZ. In wild-type mice, injected apoptotic cells were selectively engulfed by CD8 alpha(+) DCs, which are responsible for suppression of immune responses to cell-associated antigens. In contrast, deletion of macrophages in the MZ caused aberrant phagocytosis of injected dying cells by CD8 alpha(-)CD11b(+) DCs. These results indicate that macrophages in the MZ regulate not only efficient clearance of apoptotic cells but also selective engulfment of dying cells by CD8 alpha(+) DCs and that functional failure of these unique macrophages impairs suppression of immune responses to cell-associated antigens.
PDF
