Uranium Bioreduction and Biomineralization

Following the development of nuclear science and technology, uranium contamination has been an ever increasing concern worldwide because of its potential for migration from the waste repositories and long-term contaminated environments. Physical and chemical techniques for uranium pollution are expensive and challenging. An alternative to these technologies is microbially mediated uranium bioremediation in contaminated water and soil environments due to its reduced cost and environmental friendliness. To date, four basic mechanisms of uranium bioremediation-uranium bioreduction, biosorption, biomineralization, and bioaccumulation-have been established, of which uranium bioreduction and biomineralization have been studied extensively. The objective of this review is to provide an understanding of recent developments in these two fields in relation to relevant microorganisms, mechanisms, influential factors, and obstacles

Sorption of cobalt to bone char: Kinetics, competitive sorption and mechanism

Swine bone char is the combustion residues of swine bone. Cobalt adsorption to swine bone char was studied. Batch kinetics studies showed that a rapid uptake occurred during the first 5 min and was followed with a very slow intraparticle diffusion process. The sorption kinetics was ideally conformed to pseudo-second equation, indicating several mechanisms involved in the adsorption process. Equilibrium sorption isotherm studies showed that the Freundlich isotherm model satisfactorily described the sorption data. The presence of co-ions had appreciable inhibiting effects on cobalt uptake by bone char because copper and zinc had higher affinity for the bone char surface than cobalt. Calcium concentration in solution and XRD analysis showed that ion exchange was involved in the removal of Co from solution over a certain initial cobalt concentration range. (C) 2009 Elsevier B.V. All rights reserved

Toxic effects of antimony on photosystem II of Synechocystis sp as probed by in vivo chlorophyll fluorescence

It has been demonstrated that antimony (Sb) at concentrations ranging from 1.0 to 10.0 mg L-1 inhibits O-2 evolution. Deeper insight into the influence of Sb on PSII was obtained with measurements of in vivo chlorophyll fluorescence. The donor and the acceptor sides of PSII were shown to be the target of Sb. Sb treatment induces inhibition of electron transport from Q (A) (-) to Q(B)/Q (B) (-) and accumulation of P (680) (+) . S-2(Q(A)Q(B))(-) charge recombination and oxidation by PQ9 molecules became more important in Q (A) (-) reoxidation as the electron transfer in PSII was inhibited. Sb exposure caused a steady increase in the proportion of PSIIX and PSII beta. These changes resulted in increased fluxes of dissipated energy and decreased index of photosynthesis performance, of maximum quantum yield, and of the overall photosynthetic driving force of PSII

Coexisting Multiple Martensites in Ni57−xMn21+xGa22 Ferromagnetic Shape Memory Alloys: Crystal Structure and Phase Transition

A comprehensive study of the crystal structure and phase transition as a function of temperature and composition in Ni57−xMn21+xGa22 (x = 0, 2, 4, 5.5, 7, 8) (at. %) magnetic shape memory alloys was performed by a temperature-dependent synchrotron X-ray diffraction technique and transmission electron microscopy. A phase diagram of this Ni57−xMn21+xGa22 alloy system was constructed. The transition between coexisting multiple martensites with monoclinic and tetragonal structures during cooling was observed in the Ni51.5Mn26.5Ga22 (x = 5.5) alloy, and it was found that 5M + 7M multiple martensites coexist from 300 K to 160 K and that 5M + 7M + NM multiple martensites coexist between 150 K and 100 K. The magnetic-field-induced transformation from 7M martensite to NM martensite at 140 K where 5M + 7M + NM multiple martensites coexist before applying the magnetic field was observed by in situ neutron diffraction experiments. The present study is instructive for understanding the phase transition between coexisting multiple martensites under external fields and may shed light on the design of novel functional properties based on such phase transitions

Seismic Effect of Marine Corrosion and CFRP Reinforcement on Wind Turbine Tower

The offshore wind turbine tower, which has been in the marine corrosive environment for a long time, often buckles and collapses under the earthquake records. In order to study the influence of marine corrosion and CFRP reinforcement on the seismic performance of wind turbine tower structures, the horizontal displacement, horizontal acceleration and acceleration change rate of wind turbine towers are studied through numerical simulation and shaking table tests. The results show that the influence of earthquake type on the dynamic response of the wind turbine tower is different. The response values of acceleration and displacement under far-field earthquakes are larger than those of other earthquake types. The increase in PGA has a greater impact on the structural response range in the near-field earthquake. Corrosion defects not only increase the sensitivity of the wind turbine tower structure to seismic response but also have different effects on the location and development of structural plastic hinges. For the structure without corrosion defects, the plastic hinge appears at the connection between the tower and the foundation, while in the corrosion structure, the plastic hinge appears in the corrosion area. Corrosion defects increase the nonlinear development of structures, especially under far-field earthquakes. CFRP reinforcement can effectively reduce the displacement effect of the top of the structure and enhance the seismic performance of the corroded wind turbine tower

Molecular Control of Innate Immune Response to Pseudomonas aeruginosa Infection by Intestinal let-7 in Caenorhabditis elegans.

The microRNA (miRNA) let-7 is an important miRNA identified in Caenorhabditis elegans and has been shown to be involved in the control of innate immunity. The underlying molecular mechanisms for let-7 regulation of innate immunity remain largely unclear. In this study, we investigated the molecular basis for intestinal let-7 in the regulation of innate immunity. Infection with Pseudomonas aeruginosa PA14 decreased let-7::GFP expression. Intestine- or neuron-specific activity of let-7 was required for its function in the regulation of innate immunity. During the control of innate immune response to P. aeruginosa PA14 infection, SDZ-24 was identified as a direct target for intestinal let-7. SDZ-24 was found to be predominantly expressed in the intestine, and P. aeruginosa PA14 infection increased SDZ-24::GFP expression. Intestinal let-7 regulated innate immune response to P. aeruginosa PA14 infection by suppressing both the expression and the function of SDZ-24. Knockout or RNA interference knockdown of sdz-24 dampened the resistance of let-7 mutant to P. aeruginosa PA14 infection. Intestinal overexpression of sdz-24 lacking 3'-UTR inhibited the susceptibility of nematodes overexpressing intestinal let-7 to P. aeruginosa PA14 infection. In contrast, we could observed the effects of intestinal let-7 on innate immunity in P. aeruginosa PA14 infected transgenic strain overexpressing sdz-24 containing 3'-UTR. In the intestine, certain SDZ-24-mediated signaling cascades were formed for nematodes against the P. aeruginosa PA14 infection. Our results highlight the crucial role of intestinal miRNAs in the regulation of the innate immune response to pathogenic infection

pH-dependent multiple morphologies of novel aggregates of carboxyl-terminated polymide in water

Rigid low-molecular-weight polyimide with two carboxyl ends (CPI) formed pH-dependent multiple morphologies including dimpled-beads, porous aggregates and vesicles via self-assembly in aqueous media. This is a rapid and conventional approach to a series of pH-dependent morphologies of mono-component aggregates based on a readily attainable rigid homopolymer