Reduction of U(VI) Complexes by Anthraquinone Disulfonate: Experiment and Molecular Modeling

Past studies demonstrate that complexation will limit abiotic and biotic U(VI) reduction rates and the overall extent of reduction. However, the underlying basis for this behavior is not understood and presently unpredictable across species and ligand structure. The central tenets of these investigations are: (1) reduction of U(VI) follows the electron-transfer (ET) mechanism developed by Marcus; (2) the ET rate is the rate-limiting step in U(VI) reduction and is the step that is most affected by complexation; and (3) Marcus theory can be used to unify the apparently disparate U(VI) reduction rate data and as a computational tool to construct a predictive relationship

Global surveillance of cancer survival 1995-2009: analysis of individual data for 25,676,887 patients from 279 population-based registries in 67 countries (CONCORD-2)

BACKGROUND: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control. METHODS: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease. INTERPRETATION: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems

Interfacial reactivity of radionuclides: emerging paradigms from molecular-level observations

Over the past few decades an increasing array of molecular-level analytical probes has provided new detailed insight into mineral and radionuclide interfacial reactivity in subsurface environments. This capability has not only helped change the way mineral surface reactivity is studied but also how field scale contaminant migration problems are addressed and ultimately resolved. Here we review relatively new interfacial reactivity paradigms and assess their implications for future research directions. Specific examples include understanding the following: the role of site-to-site electron conduction at mineral surfaces and through bulk mineral phases and the effects of local chemical environment on the stability of intermediate species in oxidation-reduction reactions and the importance of mechanistic reaction pathways for defining possible reaction products and thermodynamic driving force. The discussion also includes examples of how detailed molecular/microscopic characterization of field samples has changed the way complex contaminant migration problems are conceptualized and modeled

Redox cycling of Fe(II) and Fe(III) in magnetite by Fe-metabolizing bacteria

Building a biogeochemical battery Iron acts as both a source and sink of electrons for microorganisms in the environment. Some anaerobic bacteria use oxidized Fe(III) as an electron acceptor, whereas phototrophic bacteria can use reduced Fe(II) as an electron donor. Byrne et al. show that the iron-bearing mineral magnetite, which contains both Fe(II) and Fe(III), can serve as both an electron acceptor and donor. Cocultures of iron-reducing and iron-oxidizing bacteria exposed to simulated day/night cycles or changes in organic matter altered the ratio of Fe(II) to Fe(III) in magnetite particles. Science , this issue p. 1473 </jats:p

CO2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements

Geologic storage of CO2 requires that the caprock sealing thestorage rock is highly impermeable to CO2. Swelling clays, which are important components of caprocks, may interact with CO2 leading to volume change and potentially impacting the seal quality. The interactions of supercritical sc CO2 with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques.The excess sorption isotherms show maxima at bulk CO2 densities of amp; 8776;0.15 g cm3, followed by an approximately linear decrease of excess sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d 001 spacing by ca. 0.5 . The density of CO2 in the clay pores is relatively stable over a wide range of CO2 pressures at a given temperature, indicating the formation of a clay CO2 phase. At the excess sorption maximum, increasing CO2 sorption with decreasing temperature is observed while the high pressure sorption properties exhibit weak temperature dependenc

Genomic changes underlying host specialization in the bee gut symbiont Lactobacillus Firm5.

Bacteria that engage in long-standing associations with particular hosts are expected to evolve host-specific adaptations that limit their capacity to thrive in other environments. Consistent with this, many gut symbionts seem to have a limited host range, based on community profiling and phylogenomics. However, few studies have experimentally investigated host specialization of gut symbionts and the underlying mechanisms have largely remained elusive. Here, we studied host specialization of a dominant gut symbiont of social bees, Lactobacillus Firm5. We show that Firm5 strains isolated from honey bees and bumble bees separate into deep-branching host-specific phylogenetic lineages. Despite their divergent evolution, colonization experiments show that bumble bee strains are capable of colonizing the honey bee gut. However, they were less successful than honey bee strains, and competition with honey bee strains completely abolished their colonization. In contrast, honey bee strains of divergent phylogenetic lineages were able to coexist within individual bees. This suggests that both host selection and interbacterial competition play important roles in host specialization. Using comparative genomics of 27 Firm5 isolates, we found that the genomes of honey bee strains harbour more carbohydrate-related functions than bumble bee strains, possibly providing a competitive advantage in the honey bee gut. Remarkably, most of the genes encoding carbohydrate-related functions were not conserved among the honey bee strains, which suggests that honey bees can support a metabolically more diverse community of Firm5 strains than bumble bees. These findings advance our understanding of the genomic changes underlying host specialization