State University of New York System

About: State University of New York System is a education organization based out in Albany, New York, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 54077 authors who have published 78070 publications receiving 2985160 citations.

An integrated view of the chemistry and mineralogy of martian soils

Abstract: The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.

Clonal Divergence in Escherichia coli as a Result of Recombination, Not Mutation

Abstract: Nucleotide sequence analysis was performed on 12 natural isolates of Escherichia coli in four loci located in close proximity on the chromosome. A comparison of gene genealogies indicated that three recombination events have occurred in a subset of the strains (ECOR group A) in the time since their divergence from a common ancestor, while during the same time, no mutational divergence has occurred. The common ancestor of this subset existed no more than 2400 years ago, and recombination was shown to occur at a rate of 5.0 x 10(-9) changes per nucleotide per generation--50-fold higher than the mutation rate. Thus, recombination has been the dominant force driving the clonal divergence of the ECOR group A strains and must be considered a significant factor in structuring E. coli populations.

PGM-Free Cathode Catalysts for PEM Fuel Cells: A Mini-Review on Stability Challenges

Abstract: In recent years, significant progress has been achieved in the development of platinum group metal-free (PGM-free) oxygen reduction reaction (ORR) catalysts for proton exchange membrane (PEM) fuel cells. At the same time the limited durability of these catalysts remains a great challenge that needs to be addressed. This mini-review summarizes the recent progress in understanding the main causes of instability of PGM-free ORR catalysts in acidic environments, focusing on transition metal/nitrogen codoped systems (M-N-C catalysts, M: Fe, Co, Mn), particularly MNx moiety active sites. Of several possible degradation mechanisms, demetalation and carbon oxidation are found to be the most likely reasons for M-N-C catalysts/cathodes degradation.

Nucleic acids labeled with naphthoquinone probe

Abstract: A sequence directed reagent is constructed by conjugating a methyl naphthoquinone derivative to a hexamethylamino linker attached to the 5' terminus of an oligonucleotide. Annealing this modified fragment of DNA to its complementary sequence allows for target modification subsequent to photochemical activation. The product of this reaction is a covalent crosslink between the reagent and target strands resulting from an alkylation of DNA by the photoexcited quinone. The modified sequence is not labile to acid, base or reductants, and blocks the exonuclease activity of the Klenow fragment of DNA polymerase I. In another embodiment, a highly reactive moiety, such as Br is attached to the methyl group of the naphthoquinone derivative. This reagent is similarly linked to an oligonucleotide probe. Activation of this probe linked alkylating agent is by a reductive signal which may either naturally occur within the cell, such as an enzyme, or introduced into the media containing the target molecule.