Regression and neural network modeling of resilient modulus based on routine soil properties and stress states.

The laboratory results from the fourteen sites from fourteen counties were used to develop the relationships or models.In order to illustrate the application of the developed model, the AASHTO flexible pavement design methodology was used to design asphalt concrete pavement sections. The design MR values from three soil specimens from the evaluation dataset were calculated from the MLPN-2 model. The pavement sections determined from the experimental MR values were compared with the pavement sections determined from the MR values predicted by the MLPN-2 model. (Abstract shortened by UMI.)Based on the ODOT specifications, two specimens were prepared and tested for resilient modulus (MR) for each soil. One of the MR specimens was prepared at the Optimum Moisture Content (OMC) and 95% of the maximum dry density, while the other specimen was prepared at maximum dry density and 2% wet of the OMC. This yielded one hundred twenty six M R specimens tests for the development dataset. The MR test results were evaluated for quality assurance.Sixty-three (63) soil samples from fourteen (14) different sites throughout Oklahoma were collected and tested for the development of the database and the statistical models and the ANN models.A more complex modeling technique, Artificial Neural Network (ANN), was employed. Six different models were considered in this phase, namely, Linear Network (LN), Generalized Regression Neural Networks (GRNN), Radial Basic Function Networks (RBFN), and Multi-Layer Perceptrons Networks (MLPN) with one, two and three hidden layers (MLPN-1, MLPN-2, and MLPN-3).The routine material parameters selected in the development of the models include moisture content (w), dry density (gammad), plasticity index (PI), percent passing No. 200 sieve (P200), and unconfined compressive strength (Uc).Resilient modulus (MR) is one of the fundamental material properties in the mechanistic analysis and structural design of roadway pavements. In the current and the proposed mechanistic-empirical design guides by AASHTO, MR is used to characterize subgrade soils. To this end, a combined laboratory and modeling study was undertaken to develop a database for subgrade soils in Oklahoma and to develop relationships or models that could be used to estimate MR from commonly used subgrade soil properties in Oklahoma. Specifically, two categories of models, namely statistical models and Artificial Neural Network (ANN) models, are employed for the determination of M R based on routine laboratory test results

Chemically and Biologically Harmless versus Harmful Ferritin/Copper–Metallothionein Couples

"This is the peer reviewed version of the following article: Carmona Rodríguez-Acosta, F.; et al. Chemically and Biologically Harmless versus Harmful Ferritin/Copper–Metallothionein Couples. Chemistry A European Journal, 21(2): 808-813 (2015), which has been published in final form at http://dx.doi.org/10.1002/chem.201404660. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."The simultaneous measurement of the decrease of available FeII ions and the increase of available FeIII ions allowed the analysis of the ferroxidase activity of two distinct apoferritins. Although recombinant human apoferritin (HuFtH) rapidly oxidizes FeII to FeIII, this iron is not properly stored in the ferritin cavity, as otherwise occurs in horse-spleen H/L-apoferritin (HsFt; H=heavy subunit, L=light subunit). Iron storage in these apoferritins was also studied in the presence of two copper-loaded mammalian metallothioneins (MT2 and MT3), a scenario that occurs in different brain-cell types. For HuFtH, unstored FeIII ions trigger the oxidation of Cu–MT2 with concomitant CuI release. In contrast, there is no reaction with Cu–MT2 in the case of HsFt. Similarly, Cu–MT3 does not react during either HuFtH or HsFt iron reconstitution. Significantly, the combination of ferritin and metallothionein isoforms reported in glia and neuronal cells are precisely those combinations that avoid a harmful release of FeII and CuI ions.Work supported by the Spanish MINECO and FEDER funds with grants CTQ2012–32236 to J.M.D.-V., BIO2012–39682-C02–01 to S.A., and BIO2012–39682-C02–02 to M.C. The authors from the Barcelona universities are members of the Grup de Recerca de la Generalitat de Catalunya (refs. 2014SGR-00423). F.C. is grateful to the Spanish MINECO for a FPI Fellowship

Inhibition and stimulation of formation of the ferroxidase center and the iron core in Pyrococcus furiosus ferritin

Ferritin is a ubiquitous iron-storage protein that has 24 subunits. Each subunit of ferritins that exhibit high Fe(II) oxidation rates has a diiron binding site, the so-called ferroxidase center (FC). The role of the FC appears to be essential for the iron-oxidation catalysis of ferritins. Studies of the iron oxidation by mammalian, bacterial, and archaeal ferritin have indicated different mechanisms are operative for Fe(II) oxidation, and for inhibition of the Fe(II) oxidation by Zn(II). These differences are presumably related to the variations in the amino acid residues of the FC and/or transport channels. We have used a combination of UV–vis spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry to study the inhibiting action of Zn(II) ions on the iron-oxidation process by apoferritin and by ferritin aerobically preloaded with 48 Fe(II) per 24-meric protein, and to study a possible role of phosphate in initial iron mineralization by Pyrococcus furiosus ferritin (PfFtn). Although the empty FC can accommodate two zinc ions, binding of one zinc ion to the FC suffices to essentially abolish iron-oxidation activity. Zn(II) no longer binds to the FC nor does it inhibit iron core formation once the FC is filled with two Fe(III). Phosphate and vanadate facilitate iron oxidation only after formation of a stable FC, whereupon they become an integral part of the core. These results corroborate our previous proposal that the FC in PfFtn is a stable prosthetic group, and they suggest that its formation is essential for iron-oxidation catalysis by the protein

Catalysis of iron core formation in Pyrococcus furiosus ferritin

The hollow sphere-shaped 24-meric ferritin can store large amounts of iron as a ferrihydrite-like mineral core. In all subunits of homomeric ferritins and in catalytically active subunits of heteromeric ferritins a diiron binding site is found that is commonly addressed as the ferroxidase center (FC). The FC is involved in the catalytic Fe(II) oxidation by the protein; however, structural differences among different ferritins may be linked to different mechanisms of iron oxidation. Non-heme ferritins are generally believed to operate by the so-called substrate FC model in which the FC cycles by filling with Fe(II), oxidizing the iron, and donating labile Fe(III)–O–Fe(III) units to the cavity. In contrast, the heme-containing bacterial ferritin from Escherichia coli has been proposed to carry a stable FC that indirectly catalyzes Fe(II) oxidation by electron transfer from a core that oxidizes Fe(II). Here, we put forth yet another mechanism for the non-heme archaeal 24-meric ferritin from Pyrococcus furiosus in which a stable iron-containing FC acts as a catalytic center for the oxidation of Fe(II), which is subsequently transferred to a core that is not involved in Fe(II)-oxidation catalysis. The proposal is based on optical spectroscopy and steady-state kinetic measurements of iron oxidation and dioxygen consumption by apoferritin and by ferritin preloaded with different amounts of iron. Oxidation of the first 48 Fe(II) added to apoferritin is spectrally and kinetically different from subsequent iron oxidation and this is interpreted to reflect FC building followed by FC-catalyzed core formation

Structural characterization of encapsulated ferritin provides insight into iron storage in bacterial nanocompartments

Ferritins are ubiquitous proteins that oxidise and store iron within a protein shell to protect cells from oxidative damage. We have characterized the structure and function of a new member of the ferritin superfamily that is sequestered within an encapsulin capsid. We show that this encapsulated ferritin (EncFtn) has two main alpha helices, which assemble in a metal dependent manner to form a ferroxidase center at a dimer interface. EncFtn adopts an open decameric structure that is topologically distinct from other ferritins. While EncFtn acts as a ferroxidase, it cannot mineralize iron. Conversely, the encapsulin shell associates with iron, but is not enzymatically active, and we demonstrate that EncFtn must be housed within the encapsulin for iron storage. This encapsulin nanocompartment is widely distributed in bacteria and archaea and represents a distinct class of iron storage system, where the oxidation and mineralization of iron are distributed between two proteins. DOI: http://dx.doi.org/10.7554/eLife.18972.00

Talinn Grigor, The Persian Revival: The Imperialism of the Copy in Iranian and Parsi Architecture

In three very detailed and ambitious chapters, The Persian Revival takes supposedly known episodes in Iranian art and architectural history in the nineteenth and twentieth centuries and makes them unknown to every Iranian. Grigor is quite right that “the accepted wisdom” has been that “it [the Persian Rivaval] was all Reza Shah’s idea” (p. 1). By revising this accepted wisdom, The Persian Revival would make every Iranian stop and look again the next time they visit buildings such as Baq-e Af..

Iron-Storage Mechanism of Ferritin

Storage of Fe(III) is a common mechanism by which the cellular machinery controls the availability of Fe(II) and Fe(III) for biosynthesis of iron-containing cofactors of enzymes which are involved in several essential biological processes, including oxidative phosphorylation. The conserved 24-meric iron-storage protein ferritin has been identified in many organisms to control the availability of Fe(II) by oxidizing the excess Fe(II) and storing the Fe(III) oxidation product in a soluble and nontoxic form. A conserved diiron center, the ferroxidase center, is responsible for catalytic oxidation of Fe(II), the ferroxidase reaction. The mechanism by which ferritin stores the Fe(III) is not fully understood, and the current models in the literature suggest different mechanisms for the functioning of ferritins from different Domains of life. Moreover, a structural gene for a 24-meric ferritin has not been found in some organisms including Pyrococcus abyssi or Pyrococcus horikoshii. Below we first outline methods which can be used to measure ferroxidase activity of different proteins. As an example we measure the ferroxidase activity of two proteins, human H ferritin and ceruloplasmin, and that of a synthetic peptide. Subsequently, using these techniques we study the mechanism of iron oxidation of a ferritin from hyperthermophilic archaeal anaerobe Pyrococcus furiosus. We then employ new experimental approaches using isotopically labeled 57Fe(II) to compare the iron-storage mechanism of P. furiosus ferritin with that of eukaryotic human H ferritin. We demonstrate that, conflicting with the current models in the literature these proteins employ a common mechanism to store the Fe(III) oxidation product. We suggest that this mechanism is general from archaea to eukaryotes. Finally, we carry out the in-vitro biochemical characterization of a new member of the ferritin superfamily of proteins that unlike the 24-meric ferritin is monomeric in the absence of iron. We name this protein archaeoferritin and we show that monomers oxidize Fe(II) and reversibly assemble to form Fe(III)-storing oligomeric structures comparable to that of ferritin.BiotechnologyApplied Science

Not a Security Issue: How Policy Experts De-Politicize the Climate Change–Migration Nexus

Policy experts play an important role in coping with the climate change–human migration nexus. They offer expert solutions to decision makers, and thus, they contribute to de-politicizing the issue. The aim of this paper is to find out how different policy experts envision the climate change–human migration nexus. The Netherlands has been nominated as the seat of a Global Center of Excellence for climate Adaptation and aims to become a Global Center of Excellence in the water safety and security domain. Policy experts were selected based on a structured nominee process. We conducted semistructured interviews with policy experts and analyzed policy expert documentation. Interview transcripts and documents were examined via a coding frame. Unlike policymakers who link climate change and conflict, policy experts stress the economic and political factors of migration in which climate change issues happen. The major difference between the view of policymakers and policy experts on the link between climate change and human migration emerges from the frame of the climate refugee. In the context of the climate change–human migration nexus, policy experts act as a countervailing power that prevents the political exploitation of the nexus into a security issu