Laser grooving of surface cracks on hot work tool steel

The paper presents the analysis of laser grooving of 1.2343 tool steel hardened to 46 HRC. The effect of laser power and grooving speed on groove shape (i.e. depth and width), the material removal rate and the purity of produced groove as a measure of groove quality was investigated and analyzed using response surface methodology. Optimal parameters of laser grooving were found, which enables pure grooves suitable for laser welding

Optodynamic Characterization of Laser-Induced Bubbles

Laser-induced bubbles can be caused by an optical breakdown in water. They are a result of the optodynamical process where the energy of a high intensity laser pulse is converted into the mechanical energy through an optodynamic conversion. At this process the absorbed optical energy causes plasma expansion that in turn initiates dynamic phenomena: spreading of a shock wave and the development of a cavitation bubble. When the cavitation bubble reaches its maximum radius it starts to collapse due to the pressure of the surrounding liquid. This collapse in turn initiates a new bubble growth and bubble collapse. The process therefore repeats itself, resulting in so-called cavitation-bubble oscillations, with a new shock wave being emitted after every collapse. We present an optodynamic characterization of cavitation bubble's oscillations based on a laser beam-deflection probe. Employed setup enabled us one-or two-dimensional scanning with deflections of a laser probe beam. Deflections were detected with a fast quadrant photodiode. PACS numbers: 42.62.-b, 47.40.-x, 47.55.d

Virulence and antimicrobial resistance determinants of verotoxigenic Escherichia coli (VTEC) and of ESBL-producing multidrug resistant E. coli from foods of animal origin illegally imported to Europe

Microbial risk due to illegal food import has not been investigated so far. Here we aimed to reveal frequency, phenotype and genotype of verotoxigenic E. coli (VTEC) and ESBL-producing multidrug resistant (MDR) E. coli isolated from foods of animal origin confiscated at the EU airport borders. Of the 1500 food samples confiscated at the airports of Austria, Germany and Slovenia, the most frequent were cheese and meat products primarily from Turkey and from Balkan countries. The VTEC bacteria were isolated using ISO 16654:2001 for O157 and Ridascreen® ELISA based PCR testing of stx genes or ISO/ TS13136 for non-O157 VTEC, resulting in 15 isolates of VTEC (1%). In addition 600 samples from the Vienna airport were also tested for ESBL-producing MDR E. coli, using cefotaxime-McConkey agar. We identified 14 E. coli strains as ESBL/MDR E. coli. (0,9%) for phenotyping for antimicrobial resistance and for genotypiing by microarray (Identibac®,AMR05). The 15 VTEC isolates were phenotyped as Stx toxin producing non-O157 strain. Only one isolate, from Turkish cheese, proved to be EHEC (O26:H46). The remaining 14 strains represent uncommon VTEC serotypes with stx1 and/or stx2 genes. Microarray analysis (Identibac®, Ec03) revealed a wide range of other non-LEE encoding virulence genes. Pulsed field electrophoresis (PFGE) showed high genetic diversity of the strains. Multilocus sequence typing (MLST) established three new ST types (ST4505, 4506 and 4507) in the MLST database, and indicated the existence of 5 small clusters with no relation to origin or serotype/genotype of the strains, but representing several human-related ST types. All VTEC isolates were sensitive to 18 antimicrobials relevant to human and/or animal health, and did not contain resistance genes. ESB/MDR E. coli were resistant to at least 3 classes of antimicrobials. Microarray analysis detected TEM-1 in all but one strain and a variety of genes encoding resistances to other ESBLs (CTXM-1, OXA-1), trimethromprim, tetracycline, aminoglycosides and class1/class2 integrons (8/14 isolates). E.coli virulence microarray detected 2-6 virulence genes in all but one MDR E. coli, and one of the strains qualified as an atypical EPEC . Even though the frequency and attributes of isolated VTEC and ESBL/MDR E. coli did not represent an immediate major risk through illegal food import for the countries involved, it is suggested that the unusual serovars of VTEC as well as the virulence and antimicrobial resistance determinants of ESBL/MDR E. coli detected here, may indicate a future emerging threat by strains in illegally imported foods. Acknowledgement is due to: EU FP7 PROMISE (Grant No: 265877), to Dr. Mária Herpay, National Institute for Epidemiology, Budapest

The global distribution of pteropods and their contribution to carbonate and carbon biomass in the modern ocean

Pteropods are a group of holoplanktonic gastropods for which global biomass distribution patterns remain poorly described. The aim of this study was to collect and synthesise existing pteropod (Gymnosomata, Thecosomata and Pseudothecosomata) abundance and biomass data, in order to evaluate the global distribution of pteropod carbon biomass, with a particular emphasis on temporal and spatial patterns. We collected 25 939 data points from several online databases and 41 scientific articles. These data points corresponded to observations from 15 134 stations, where 93% of observations were of shelled pteropods (Thecosomata) and 7% of non-shelled pteropods (Gymnosomata). The biomass data has been gridded onto a 360 × 180° grid, with a vertical resolution of 33 depth levels. Both the raw data file and the gridded data in NetCDF format can be downloaded from PANGAEA, doi:10.1594/PANGAEA.777387. Data were collected between 1950–2010, with sampling depths ranging from 0–2000 m. Pteropod biomass data was either extracted directly or derived through converting abundance to biomass with pteropod-specific length to carbon biomass conversion algorithms. In the Northern Hemisphere (NH), the data were distributed quite evenly throughout the year, whereas sampling in the Southern Hemisphere (SH) was biased towards winter and summer values. 86% of all biomass values were located in the NH, most (37%) within the latitudinal band of 30–60° N. The range of global biomass values spanned over four orders of magnitude, with mean and median (non-zero) biomass values of 4.6 mg C m−3 (SD = 62.5) and 0.015 mg C m−3, respectively. The highest mean biomass was located in the SH within the 70–80° S latitudinal band (39.71 mg C m−3, SD = 93.00), while the highest median biomass was in the NH, between 40–50° S (0.06 mg C m−3, SD = 79.94). Shelled pteropods constituted a mean global carbonate biomass of 23.17 mg CaCO3 m−3 (based on non-zero records). Total biomass values were lowest in the equatorial regions and equally high at both poles. Pteropods were found at least to depths of 1000 m, with the highest biomass values located in the surface layer (0–10 m) and gradually decreasing with depth, with values in excess of 100 mg C m−3 only found above 200 m depth. Tropical species tended to concentrate at greater depths than temperate or high-latitude species. Global biomass levels in the NH were relatively invariant over the seasonal cycle, but more seasonally variable in the SH. The collected database provides a valuable tool for modellers for the study of marine ecosystem processes and global biogeochemical cycles. By extrapolating regional biomass to a global scale, we established global pteropod biomass to add up to 500 Tg C

THE DECREASE OF OPTOACOUSTIC SIGNALS INDUCED BY THE ABSORPTION OF MEDIUM INTENSITY LASER PULSES ON SOLIDS

Les mesures simultanées des signaux optoacoustiques dans le solide absorbant et dans le gaz qui l'entoure sont accomplies pour étudier les modifications de la surface causées par l'absorption des quelques impulsions initiales du laser de fluence 0,4 J/cm2 et de durée 20 ns.Simultaneous measurements of optoacoustic signals in the absorbing solid and in the surrounding gas have been performed in order to study surface modifications on various solids, caused by the absorption of the firts few laser pulses of fluence 0.4 J/cm2 and duration 20 ns

Optodynamic Characterization of Laser-Induced Bubbles

Laser-induced bubbles can be caused by an optical breakdown in water. They are a result of the optodynamical process where the energy of a high intensity laser pulse is converted into the mechanical energy through an optodynamic conversion. At this process the absorbed optical energy causes plasma expansion that in turn initiates dynamic phenomena: spreading of a shock wave and the development of a cavitation bubble. When the cavitation bubble reaches its maximum radius it starts to collapse due to the pressure of the surrounding liquid. This collapse in turn initiates a new bubble growth and bubble collapse. The process therefore repeats itself, resulting in so-called cavitation-bubble oscillations, with a new shock wave being emitted after every collapse. We present an optodynamic characterization of cavitation bubble's oscillations based on a laser beam-deflection probe. Employed setup enabled us one- or two-dimensional scanning with deflections of a laser probe beam. Deflections were detected with a fast quadrant photodiode

Optodynamic Characterization of Laser-Induced Bubbles

Laser-induced bubbles can be caused by an optical breakdown in water. They are a result of the optodynamical process where the energy of a high intensity laser pulse is converted into the mechanical energy through an optodynamic conversion. At this process the absorbed optical energy causes plasma expansion that in turn initiates dynamic phenomena: spreading of a shock wave and the development of a cavitation bubble. When the cavitation bubble reaches its maximum radius it starts to collapse due to the pressure of the surrounding liquid. This collapse in turn initiates a new bubble growth and bubble collapse. The process therefore repeats itself, resulting in so-called cavitation-bubble oscillations, with a new shock wave being emitted after every collapse. We present an optodynamic characterization of cavitation bubble's oscillations based on a laser beam-deflection probe. Employed setup enabled us one-or two-dimensional scanning with deflections of a laser probe beam. Deflections were detected with a fast quadrant photodiode. PACS numbers: 42.62.-b, 47.40.-x, 47.55.d