Unusual magneto-optical behavior induced by local dielectric variations under localized surface plasmon excitations

We study the effect of global and local dielectric variations on the polarization conversion rps response of ordered nickel nanowires embedded in an alumina matrix. When considering local changes, we observe a non-monotonous behavior of the rps, its intensity unusually modified far beyond to what it is expected for a monotonous change of the whole refractive index of the embedding medium. This is related to the local redistribution of the electromagnetic field when a localized surface plasmon is excited. This finding may be employed to develop and improve new biosensing magnetoplasmonic devices

Magnetic circular dichroism study on YIG films

This paper presents the temperature dependence (300 — 1.8 K) of the magnetic circular dichroism (MCD) spectrum of YIG in the 19 000-33 000 cm -1 energy range. MCD data are analysed in terms of a model of two sublattices with additive contributions. This analysis provides strong support to the current picture that optical transitions involve simultaneous excitations on the two sublattices. Furthermore, our MCD data enable several new excited states to be located accurately.Nous présentons la dépendance en temperature (300 — 1,8 K) des spectres de dichroisme circulaire magnétique (DCM) de films de YIG entre 19 000 et 33 000 cm-1. Nos résultats sont analyses à l'aide d'un modele à deux sous-réseaux dont les contributions sont additives. Nous montrons ainsi que les transitions optiques du YIG mettent en jeu simultanément des excitations sur les deux sous-réseaux. Par ailleurs, nos spectres de DCM permettent de localiser avec precision des bandes non observées dans le spectre d'absorption

Immobilization of Pseudomonas sp. strain ADP: a stable inoculant for the bioremediation of atrazine

Storage and delivery of beneficial microorganisms are fundamental issues determining their value and effectiveness for a wide range of industrial and environmental purposes. One such application is the use of bacteria for the remediation of soil pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and persistent pesticides. Liquid cultures of a candidate for atrazine degradation in soil and water, Pseudomonas sp. strain ADP (3.67 × 109 colony-forming units, cfu/mL), when stored at 4 and 25 °C, showed a 1 log reduction in cfu/mL occurs after approximately 4 and 2 weeks, respectively. When immobilized onto natural zeolite from two sources (a New Zealand and an Australian quarry) and stored in open containers exposed to the atmosphere, survival at 25 °C was poor. However, when the cells were immobilized onto the Australian zeolite with xanthan gum and stored in closed containers, survival at 25 °C was superior to control cells stored at 4 °C. The initial growth medium, zeolite substratum and immobilization matrix excipients all appear to play an important role in the stabilization of Pseudomonas sp. strain ADP. The bacteria immobilized onto Australian zeolite with xanthan remained viable within 1 log unit of initial cfu/g loading and retained their ability to degrade atrazine (as measured by zone clearance on atrazine containing plates) for at least 10 weeks at 25 °C

Magnetooptical Kerr spectra in sputtered strontium ferrite films

Magnetooptic (MO) polar Kerr effect spectra and MO hysteresis loops of SrFe12O19 hexagonal ferrite films are presented. The films were prepared by rf sputtering and subsequently annealed at 800 or 900 degrees C in O-2/Ar. The crystallographic orientation with the c-axis perpendicular to the film plane was checked using XRD. The films display perpendicular magnetic anisotropy and rectangular hysteresis loops with a remanence ratio close to one. At low photon energies below the absorption edge of SrFe12O19 at 2 5 eV MO spectra are affected by the radiation penetration into the film and the quartz substrate. Above this energy they display the features typical for bulk SrFe12O19 crystals. The coercive field, structure of the MO spectra and the magnitude of the prominent peak in the spectra near 4.5 eV can be correlated with the structural quality of the films. Consequently, the magnetooptics can serve as a diagnostics tool for these films

Characterization of Pseudomonas syringae strains from cherry orchards in Central Otago

Bacterial canker of cherry, caused by Pseudomonas syringae pathovars, is a major constraint to cherry growing in New Zealand. The prevalence and pathogenicity of strains from cherry orchards in Central Otago were studied, with the aim of better understanding the epidemiology of the disease. Pseudomonas spp. isolates were collected from symptomatic and asymptomatic cherry tissue in 2015. Isolates were classified into strains belonging to three different taxonomic groups by determining the phylogeny of the gltA gene for all the strains and the Multi Locus Sequence Analysis (MLSA)¹ of four housekeeping genes for 35 strains. Pathogenicity tests in plant tissue were carried out to further characterise the strains. The two main taxonomic groups were P. syringae pv. syringae (Pss) and P. syringae pv. morsprunorum (Psm), in Phylogroup 2 and Phylogroup 3, respectively². The third group comprised non-pathogenic strains classified as Pseudomonas spp. It was concluded that Pss is the predominant pathovar in Central Otago. Lesions caused by Pss on inoculated-immature cherry fruit were observed as being black/necrotic, while Psm caused watersoaked lesions. Lesions on fruit inoculated with Pss strains increased rapidly in size, having a larger area under the disease progress curve (AUDPC) at 10 days post inoculation (dpi), compared with fruit inoculated with Psm strains. Symptoms on leaves infiltrated with Pss appeared within 1-dpi. At 7 dpi, the necrosis caused by most Pss strains, had extended considerably from the inoculation site and into the leaf veins, while necrosis caused by Psm strains remained restricted to the inoculation site. On 1-year-old cherry shoots, the smallest lesions were for strains classified as non-pathogenic Pseudomonas spp. Larger lesions were associated with Pss and Psm strains, which did not differ significantly in this assay. This is the first detailed study of the P. syringae species complex in cherry orchards in New Zealand and it provides the basis for future epidemiology studies

Draft genome sequences of two New Zealand Xanthomonas campestris pv. campestris isolates, ICMP 4013 and ICMP 21080

Xanthomonas campestris pv. campestris is a necrotrophic bacterial pathogen of crucifers. We report here the draft genome sequences of isolates ICMP 4013 and ICMP 21080 from New Zealand. These sequences will facilitate the identification of race-specific factors in X. campestris pv. campestris

Influence of Co on the Magnetic and Magneto-Optical Properties of Co-Ni/Pt and Co-Ni/Au Multilayers

Nous décrivons nos études magnétiques et magnéto-optiques sur des multicouches Co-Ni/M (M = Pt, Au) préparées par évaporation sous ultra vide. L'anisotropie de surface Ks augmente linéairement avec la teneur en Co ce qui vérifie le modèle à un ion. La teneur relative de Ni permet d'ajuster la température de Curie afin de pouvoir utiliser ces matériaux pour l'enregistrement thérmomagnétique. La rotation Kerr présente un pic vers 4 eV pour les multicouches à base de Pt, qui se situe vers 2,5 eV pour celles d'or. On discute des résultats