Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest. To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio calculations, we observed the formation of reduced and structurally distorted metal sites consistent with small polarons. Comparisons between different phases (hematite, maghemite, and ferrihydrite) revealed that short-range structural topology, not long-range order, dominates the electron-hopping rate.     

Clovis age Western Stemmed projectile points and human coprolites at the Paisley Caves

The Paisley Caves in Oregon record the oldest directly dated human remains (DNA) in the Western Hemisphere. More than 100 high-precision radiocarbon dates show that deposits containing artifacts and coprolites ranging in age from 12,450 to 2295 (14)C years ago are well stratified. Western Stemmed projectile points were recovered in deposits dated to 11,070 to 11,340 (14)C years ago, a time contemporaneous with or preceding the Clovis technology. There is no evidence of diagnostic Clovis technology at the site. These two distinct technologies were parallel developments, not the product of a unilinear technological evolution. "Blind testing" analysis of coprolites by an independent laboratory confirms the presence of human DNA in specimens of pre-Clovis age. The colonization of the Americas involved multiple technologically divergent, and possibly genetically divergent, founding groups.     

Involvement of Parachlamydia in bovine abortions in Scotland

Bovine abortion represents a major animal welfare issue and a cause of substantial economic loss yet the rate of successful diagnosis remains low. Chlamydia-related organisms including Parachlamydia have recently emerged as putative cattle abortifacients. Placental tissue samples and fetal lung from bovine abortion submissions across Scotland in Spring 2011 were investigated by histopathology for the presence of suspect Chlamydia-related organisms. Evidence of Chlamydia-related organisms was observed in 21/113 (18.6%) placenta samples. Thirteen of the suspect cases and 18 histopathology negative cases were analysed by molecular and immunohistochemical methods. All samples were PCR positive for Parachlamydia but sequencing revealed high homology between identified environmental 16S sequences in all but three cases. Parachlamydial antigen was detected in 10/31 placental samples (32.2%) with pathology consistent with chlamydial infection. This work supports the need for further surveillance investigations and experimental studies to determine the role of Parachlamydia in bovine abortion.     

Accumulation Capacities of Particulate Matter in an Acrocarpous and a Pleurocarpous Moss Exposed at Three Differently Polluted Sites (Industrial, Urban and Rural)

The aim of this study was to compare the capacity of two morphologically different moss species to accumulate elements when exposed to three different types of air pollution (rural, urban and industrial). Transplants of Pseudoscleropodium purum and Ceratodon purpureus were exposed for 6 months, and the concentrations of 18 elements (Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Mo, Cd, Sn, Sb, Ba, La, Pb and Bi) in the mosses samples were analysed by inductively coupled plasma–mass spectrometry. On the whole, the metals were accumulated by mosses, and this accumulation was correlated with concentrations in the atmospheric particles. Whereas P. purum is to be preferred for Al, Cu, Zn and Fe monitoring, C. purpureus was most efficient at accumulating Mo, Ti, V, As, Sn, La and Pb. In both species, a phenomenon of saturation was observed during the exposure at the most contaminated site (industrial).     

Reliable ELISAs showing differences between resistant and susceptible lines in hens orally inoculated with Salmonella Enteritidis

Reliable ELISAs were investigated with the aim to select hen lines resistant to Salmonella Enteritidis and producing high levels of antibodies. In the first experiment, the relation between the humoral response and the bacteriological results was assessed on hens from the Y11 resistant line and the L2 susceptible line, orally inoculated with 10(8) CFU S. Enteritidis per animal. Anti-lipopolysaccharide (LPS) IgG titres were higher but the liver and spleen were less contaminated in hens from the Y11 line than in hens from the L2 line (p = 0.013, 0.031 and 0.026 respectively). In the second experiment, the hens were inoculated orally with 1.7 x 10(8) CFU S. Enteritidis per animal in order to select the ELISA methods showing the more significant differences. ELISAs were based on LPS, flagella, LPS from rough (LPS-R) and smooth strains (LPS-S) and detected IgG and IgM antibodies from sera and yolks. No between-line host response variation was observed in the yolk, with LPS-S and R antigens nor with anti-LPS IgM in the sera. Otherwise, significant differences were encountered between hen lines with the ELISAs performed on the sera detecting anti-LPS IgG, anti-flagella IgG or IgM (p = 0.017, 0.017 and p < 0.001 respectively). When comparing the kinetics of the selected ELISAs, the IgG antibodies against LPS detected between-line variations as early as 1 to 4 weeks pi, whereas with IgG against flagella, the differences were only detected at 1 and 2 weeks pi and with IgM against flagella, the differences were significant at 1, 2, 4 and 8 weeks pi. In conclusion, resistant hen lines producing higher levels of antibodies than the susceptible hen lines may be selected with these ELISAs.     

Confirmation and quantification of pesticide residues by mass spectrometry

The sensitivity and specificity of mass spectrometry makes this an attractive technique for the confirmation and quantification of trace levels of pesticide residues. Two applications of mass spectrometry are outlined, that of combined headspace gas chromatography (g.c.)/mass spectrometry (m.s.), for the analysis of volatile fumigants such as ethylene dibromide (EDB) in imported fruits and multi-residue halogenated compounds in bran products, and that of quantitative g.c./m.s. for the determination of a range of organochlorine pesticide residues. The approach to setting-up a capillary g.c. multiple ion monitoring programme is described, with emphasis on quantitative aspects, and in particular the use of stable isotope internal standards. This is illustrated with an example of the quantification of organochlorine pesticide residues in eggs.