Bremsstrahlung in alpha-Decay Reexamined

A high-statistics measurement of bremsstrahlung emitted in the alpha decay of 210Po has been performed, which allows to follow the photon spectra up to energies of ~ 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasi classical approximation as well as with the exact quantum mechanical calculation. It is shown that due to the small effective electric dipole charge of the radiating system a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon.Comment: 10 pages, 5 figures, v2: fix of small typo

Bathymetry and Sediment Geochemistry of Lake Hazen (Quttinirpaaq National Park, Ellesmere Island, Nunavut)

Arctic lakes can provide a long-term perspective on environmental change, including trends in long-range atmospheric transport and deposition of contaminants, inferred from studies of sediment cores. In this study, we conducted the first detailed bathymetric survey of Lake Hazen (Quttinirpaaq National Park, Ellesmere Island, Nunavut), the world’s largest lake north of 74˚ latitude. With these data we were able to determine optimal locations for sediment coring and to collect and analyze profundal sediment cores. A bathymetric map of Lake Hazen was developed on the basis of 362 spot soundings obtained with GPS-coupled sounding equipment placed directly on the ice combined with additional soundings from a small boat. The deepest point in the lake (81˚49.5ʹ N; 70˚42.8ʹ W) was found to be 267 m deep. The lake volume was estimated to be 5.14 × 1010 m3, about 10% larger than previous estimates. Using estimates of the discharge of Lake Hazen from the Water Survey of Canada, we estimated the water retention time to be 89 years. Sediment cores were dated using 210Pb and 137Cs. Sedimentation rates at the deep point, estimated using the Constant Rate of Supply model for excess 210Pb, were relatively high (1260 g m-2yr-1) in the period 2005 – 1963 and lower (650 ± 100 g m-2yr-1) in horizons dated to 1950 – 1880. The majority of elements measured in sediment (24 of 29 consistently above detection limits), as well as organic carbon, showed less than 20% variation in concentrations in the top 10 cm (compacted depth), which represent deposition over approximately 140 years. Geochemical characteristics of the sediment suggest that erosional inputs from annual glacial melting are the major source of essentially all elements and that anthropogenic inputs from long-range transport of toxic metals such as mercury and lead are very low.Les lacs de l’Arctique peuvent fournir une perspective à long terme en matière de changement environnemental, notamment en ce qui a trait aux tendances relatives au transport atmosphérique et au dépôt de contaminants sur de longues périodes, tendances inférées à partir d’études de carottes de sédiments. Dans le cadre de la présente étude, nous avons effectué le premier levé bathymétrique détaillé du lac Hazen (parc national Quttinirpaaq, île d’Ellesmere, Nunavut), le plus grand lac de la planète situé au nord de 74˚ de latitude. Grâce aux données prélevées, nous avons réussi à déterminer les meilleurs emplacements pour le prélèvement de carottes de sédiments de même que pour la collecte et l’analyse de carottes de sédiments profonds. Une carte bathymétrique du lac Hazen a été dressée en fonction de 362 sondages obtenus au moyen de matériel d’appareils phoniques dotés de GPS placés directement sur la glace et supplémentés par des sondages recueillis à partir d’un petit bateau. Le point le plus profond du lac (81˚49,5ʹ N; 70˚42,8ʹ O) a été trouvé à 267 m de profondeur. Le volume du lac a été évalué à 5,14 × 1010 m3, soit 10 % de plus que les évaluations précédentes. À l’aide d’estimations du déversement du lac Hazen obtenues auprès de la Division des relevés hydrologiques du Canada, nous avons évalué que la durée de rétention de l’eau était de 89 ans. La datation des carottes de sédiments a été faite à l’aide de 210Pb et de 137Cs. Les taux de sédimentation au point profond, estimés en s’appuyant sur le modèle CRS (Constant Rate of Supply) pour l’excédent 210Pb, étaient relativement élevés (1260 g m-2an-1) pour la période allant de 2005 à 1963, et moins élevés (650 ± 100 g m-2an-1) pour la période de 1950 à 1880. La majorité des éléments mesurés dans les sédiments (24 sur 29 étaient uniformément au-dessus des seuils de détection) ainsi que dans le carbone organique ont produit une variation de concentrations de moins de 20 % dans les 10 cm supérieurs (profondeur compactée), ce qui représente des dépôts s’échelonnant sur environ 140 ans. Les caractéristiques géochimiques des sédiments laissent présumer que les matières d’érosion découlant de la fonte glaciaire annuelle constituent la source principale de sensiblement tous les éléments, et que les matières anthropiques provenant du transport à grande distance de métaux toxiques, tels que le mercure et le plomb, sont très faibles

Surface chemistry and stability of metastable corundum-type In2O3

To account for the explanation of an eventual sensing and catalytic behavior of rhombohedral In2O3 (rh-In2O3) and the dependence of the metastability of the latter on gas atmospheres, in situ electrochemical impedance spectroscopic (EIS), Fourier-transform infrared spectroscopic (FT-IR), in situ X-ray diffraction and in situ thermogravimetric analyses in inert (helium) and reactive gases (hydrogen, carbon monoxide and carbon dioxide) have been conducted to link the gas-dependent electrical conductivity features and the surface chemical properties to its metastability towards cubic In2O3. In particular, for highly reducible oxides such as In2O3, for which not only the formation of oxygen vacancies, but deep reduction to the metallic state (i.e. metallic indium) also has to be taken into account, this approach is imperative. Temperature-dependent impedance features are strongly dependent on the respective gas composition and are assigned to distinct changes in either surface adsorbates or free charge carrier absorbance, allowing for differentiating and distinguishing between bulk reduction-related features from those directly arising from surface chemical alterations. For the measurements in an inert gas atmosphere, this analysis specifically also included monitoring the fate of differently bonded, and hence, differently reactive, hydroxyl groups. Reduction of rh-In2O3 proceeds to a large extent indirectly via rh-In2O3 → c-In2O3 → In metal. As deduced from the CO and CO2 adsorption experiments, rhombohedral In2O3 exhibits predominantly Lewis acidic surface sites. The basic character is less pronounced, directly explaining the previously observed high (inverse) water–gas shift activity and the low CO2 selectivity in methanol steam reforming.DFG, SPP 1415, Kristalline Nichtgleichgewichtsphasen - Präparation, Charakterisierung und in situ-Untersuchung der Bildungsmechanisme

Generation of Covalently Closed Circular DNA of Hepatitis B Viruses via Intracellular Recycling Is Regulated in a Virus Specific Manner

Persistence of hepatitis B virus (HBV) infection requires covalently closed circular (ccc)DNA formation and amplification, which can occur via intracellular recycling of the viral polymerase-linked relaxed circular (rc) DNA genomes present in virions. Here we reveal a fundamental difference between HBV and the related duck hepatitis B virus (DHBV) in the recycling mechanism. Direct comparison of HBV and DHBV cccDNA amplification in cross-species transfection experiments showed that, in the same human cell background, DHBV but not HBV rcDNA converts efficiently into cccDNA. By characterizing the distinct forms of HBV and DHBV rcDNA accumulating in the cells we find that nuclear import, complete versus partial release from the capsid and complete versus partial removal of the covalently bound polymerase contribute to limiting HBV cccDNA formation; particularly, we identify genome region-selectively opened nuclear capsids as a putative novel HBV uncoating intermediate. However, the presence in the nucleus of around 40% of completely uncoated rcDNA that lacks most if not all of the covalently bound protein strongly suggests a major block further downstream that operates in the HBV but not DHBV recycling pathway. In summary, our results uncover an unexpected contribution of the virus to cccDNA formation that might help to better understand the persistence of HBV infection. Moreover, efficient DHBV cccDNA formation in human hepatoma cells should greatly facilitate experimental identification, and possibly inhibition, of the human cell factors involved in the process

"Safe" Coulomb Excitation of 30Mg

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation gamma ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31) e2fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg lies still outside the ``island of inversion''

Epidemiology of Extended-Spectrum beta-Lactamase-Producing E-coli and Vancomycin-Resistant Enterococci in the Northern Dutch-German Cross-Border Region

Objectives: To reveal the prevalence and epidemiology of extended-spectrum β-lactamase (ESBL)- and/or plasmid AmpC (pAmpC)- and carbapenemase (CP) producing Enterobacteriaceae and vancomycin-resistant enterococci (VRE) across the Northern Dutch–German border region.Methods: A point-prevalence study on ESBL/pAmpC/CP producing Enterobacteriaceae and VRE was carried out in hospitalized patients in the Northern Netherlands (n = 445, 2012–2013) and Germany (n = 242, 2012). Healthy individuals from the Dutch community (n = 400, 2010–2012) were also screened. In addition, a genome-wide gene-by-gene approach was applied to study the epidemiology of ESBL-Escherichia coli and VRE.Results: A total of 34 isolates from 27 patients (6.1%) admitted to Dutch hospitals were ESBL/pAmpC positive and 29 ESBL-E. coli, three pAmpC-E. coli, one ESBL-Enterobacter cloacae, and one pAmpC-Proteus mirabilis were found. In the German hospital, 18 isolates (16 E. coli and 2 Klebsiella pneumoniae) from 17 patients (7.7%) were ESBL positive. In isolates from the hospitalized patients CTX-M-15 was the most frequently detected ESBL-gene. In the Dutch community, 11 individuals (2.75%) were ESBL/pAmpC positive: 10 ESBL-E. coli (CTX-M-1 being the most prevalent gene) and one pAmpC E. coli. Six Dutch (1.3%) and four German (3.9%) hospitalized patients were colonized with VRE. Genetic relatedness by core genome multi-locus sequence typing (cgMLST) was found between two ESBL-E. coli isolates from Dutch and German cross-border hospitals and between VRE isolates from different hospitals within the same region.Conclusion: The prevalence of ESBL/pAmpC-Enterobacteriaceae was similar in hospitalized patients across the Dutch–German border region, whereas VRE prevalence was slightly higher on the German side. The overall prevalence of the studied pathogens was lower in the community than in hospitals in the Northern Netherlands. Cross-border transmission of ESBL-E. coli and VRE seems unlikely based on cgMLST analysis, however continuous monitoring is necessary to control their spread and stay informed about their epidemiology

FI on-line chemiluminescence reaction for determination of MCPA in water samples

This paper reports an economic, simple, and rapid FI-CL method for the determination of MCPA. This method requires simple instrumentation and it is fast enough to be used in routine analyses. A chemiluminescence signal is generated by reaction between photodegraded MCPA and ferricyanide solution in alkaline medium. All physical and chemical parameters in the flow injection chemiluminescence system were optimized in the experimental setting. To eliminate interference, a solid-phase extraction stage with SDB-1 cartridges and ethanol elution is applied. The signal-MCPA concentration relation is linear in concentration intervals between 0.0015 and 0.6 ¿g¿mL -1. The calibration lines are statistically similar in different working conditions: standards with ethanol without extraction and standards with ethanol and extraction, allowing standards to be excluded from the extraction step, which simplifies the process. The detection limit (DL) is 0.5 ng¿mL -1, which is the same order as the maximum limit established in legislation regarding pesticide limits in water destined for human consumption. A DL of 0.13 ng¿mL -1 can be reached if a sample of 100 mL is preconcentrated. The interday variance coefficient is 3% and the sample throughput is 90 h -1. The water analysis method is efficient with relative error percentages lower than 5% with respect to the added concentration. © 2011 Springer-Verlag.Authors acknowledge to the "Ministerio de Educacion y Ciencia" of Spain and FEDER funds for financial support (Project CTM2006-11991)Torres Cartas, S.; Gómez Benito, C.; Meseguer-Lloret, S. (2012). FI on-line chemiluminescence reaction for determination of MCPA in water samples. Analytical and Bioanalytical Chemistry. 402:1289-1296. https://doi.org/10.1007/s00216-011-5567-1S12891296402Navarro JS (2008) Utilización de plaguicidas en las asociaciones de tratamientos integrados en agricultura en la región de Murcia. Consejería de Sanidad Región de MurciaBarceló D, Hennion MC (1997) Trace determination of pesticide and their degradation products in water. Elsevier, AmsterdamKöck M, Farré M, Martínez E, Gajda-Schrantz K, Ginebreda A, Navarro A, López de Alda M, Barceló D (2010) J Hydrol 383(1–2):73–82Woudneh MB, Sekela M, Tuominen T, Gledhill M (2007) J Chromatogr A 1139(1):121–129Laganà A, Bacaloni A, De-Leva I, Faberi A, Fago G, Marino A (2002) Anal Chim Acta 462:187–198Comoretto L, Arfib B, Chiron S (2007) Sci Total Environ 380(1–3):124–132Kuster M, de Alda MJL, Barata C, Raldá D, Barceló D (2008) Talanta 75(2):390–401Kuster M, de Alda MJL, Hernando MD, Petrovic M, Martín-Alonso J, Barceló D (2008) J Hydrol 358(1–2):112–123Gervais G, Brosillon S, Laplanche A, Helen C (2008) J Chromatogr A 1202(2):163–172Housari F, Höhener P, Chiron S (2011) Sci Total Environ 409(3):582–587Delhomme O, Raeppel C, Briand O, Millet M (2011) Anal Bioanal Chem 399:1325–1334Royal decree 140/2003, 7th of February that establishes the health criteria for the water quality for human consumption. (BOE 21 February 2003)von-der-Ohe PC, Dulio V, Slobodnik J, de-Deckere E, Köhne R, Ebert RU, Ginebreda A, de-Cooman de-Cooman W, Schüürmann G, Brack W (2011) Sci Total Environ 409(11):2064–2077Horwitz W (ed) (2000) Official methods of analysis of AOAC International, 17th edn. AOAC International, GaithersburgMoret S, Sánchez JM, Salvadó V, Hidalgo M (2005) J Chromatogr A 1099(1–2):55–63Tran ATK, Hyne RV, Doble P (2007) Chemosphere 67(5):944–953Long F, Shi HC, He M, Zhu AN (2008) Biosens Bioelectron 23:1361–1366Meulenberg EP, Stoks PG (1995) Anal Chim Acta 311:407–413Chuang JC, Van Emon JM, Durnford J, Thomas K (2005) Talanta 67:658–666Boro RC, Kaushal J, Nangia Y, Wangoo N, Bhashi A, Suri CR (2011) Analyst 136(10):2125–2130Eremin SA, Laassis P, Aaron JJ (1996) Talanta 43:295–301Almansa-López EM, García-Campaña AM, Aaron JJ, Cuadros-Rodriguez L (2003) Talanta 60:355–367García LF, Eremin S, Aaron JJ (1996) Anal Lett 29(8):1447–1461García-Campaña AM, Aaron JJ, Bosque-Sendra JM (2002) Luminescence 17:285–287Lara FJ, García-Campaña AM, Aaron JJ (2010) Anal Chim Acta 679:17–30López-Paz J, Catalá-Icardo M (2011) Anal Lett 44(1–3):146–175Mbaye M, Gaye-Seye M, Aaron JJ, Coly A, Tine A (2011) Anal Bioanal Chem 400(2):403–410López-Paz JL, Catalá-Icardo M, Antón-Garrido B (2009) Anal Bioanal Chem 394:1073–1079López-Paz J, Catalá-Icardo M (2008) Anal Chim Acta 625(2):173–179Chen X, Lin Z, Cai Z, Chen X, Wang X (2008) Talanta 76(5):1083–1087Meseguer-Lloret S, Torres-Cartas S, Gómez-Benito M (2010) Anal Bioanal Chem 398:3175–3182Catalá-Icardo M, Martínez-Calatayud J (2008) Crit Rev Anal Chem 38(2):118–13

Prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) among pigs on German farms and import of livestock-related MRSA into hospitals

The aim of this study was to evaluate the prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) among pigs and estimate the impact of this animal reservoir on human healthcare. Nasal swabs were derived from 1,600 pigs at 40 German farms. The MRSA were characterized using S. aureus protein A (spa) typing, multilocus sequence typing (MLST) and detection of toxin genes. In a retrospective case control study, we compared risk factors for the carriage of MRSA between patients carrying spa types found among regional pigs and patients with other MRSA molecular types. Pigs carrying MRSA were identified on 70% of the farms (spa types t011, t034, t108, t1451 and t2510, all associated with MLST sequence type ST398). Contact to pigs and cattle were independent risk factors for the carriage of these spa types in patients at hospital admission. Our results indicate that livestock represents a relevant reservoir for the import of MRSA into regional German hospitals

Human Hepatitis B Virus Production in Avian Cells Is Characterized by Enhanced RNA Splicing and the Presence of Capsids Containing Shortened Genomes

Experimental studies on hepatitis B virus (HBV) replication are commonly done with human hepatoma cells to reflect the natural species and tissue tropism of the virus. However, HBV can also replicate, upon transfection of virus coding plasmids, in cells of other species. In such cross-species transfection experiments with chicken LMH hepatoma cells, we previously observed the formation of HBV genomes with aberrant electrophoretic mobility, in addition to the those DNA species commonly seen in human HepG2 hepatoma cells. Here, we report that these aberrant DNA forms are mainly due to excessive splicing of HBV pregenomic RNA and the abundant synthesis of spliced DNA products, equivalent to those also made in human cells, yet at much lower level. Mutation of the common splice acceptor site abolished splicing and in turn enhanced production of DNA from full-length pgRNA in transfected LMH cells. The absence of splicing made other DNA molecules visible, that were shortened due to the lack of sequences in the core protein coding region. Furthermore, there was nearly full-length DNA in the cytoplasm of LMH cells that was not protected in viral capsids. Remarkably, we have previously observed similar shortened genomes and non-protected viral DNA in human HepG2 cells, yet exclusively in the nucleus where uncoating and final release of viral genomes occurs. Hence, two effects reflecting capsid disassembly in the nucleus in human HepG2 cells are seen in the cytoplasm of chicken LMH cells

Transmission of highly virulent community-associated MRSA ST93 and livestock-associated MRSA ST398 between humans and pigs in Australia

Pigs have been recognised as a reservoir of livestock associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in Europe, Asia and North America. However, little is known about the presence and distribution of MRSA in the Australian pig population and pig industry. This study describes the presence, distribution and molecular characteristics of the human adapted Australian CA-MRSA ST93 isolated from pigs, people, and the environment within a piggery. Isolates were subjected to antibiotic susceptibility testing, DNA microarray, whole genome sequencing, multi locus sequence typing, virulence and resistance gene characterization and phylogenetic analysis. MRSA were isolated from 60% (n = 52) of farm workers where 84% of isolates returned ST93 and the rest ST398. Of the thirty-one pig isolates tested further, an equal number of ST398 and ST93 (15 each) and one as ST30-V were identified. Four of six environmental isolates were identified as ST93 and two as ST398. This study has identified for the first time in Australia the occurrence of CA-MRSA ST93 and LA-MRSA ST398 amongst farm workers, pigs, and the farm environment. Comparative genome analysis indicates that ST398 is likely to have been introduced into Australia from Europe or North America. This study also reports the first linezolid resistant MRSA isolated in Australia