Impact of single atomic defects and vacancies on the magnetic anisotropy energy of CoPt thin films.

The impact of surface vacancies and single adatoms on the magnetic properties of tetragonal L1 CoPt thin films is investigated from first principles. We consider Co and Fe single adatoms deposited on a Pt-terminated thin film while a Pt adatom is assumed to be supported by a Co-terminated film. The vacancy is injected in the top-surface layer of the films with both types of termination.

Giant perpendicular magnetic anisotropy energies in CoPt thin films: impact of reduced dimensionality and imperfections.

The impact of reduced dimensionality on the magnetic properties of the tetragonal L1 CoPt alloy is investigated from ab initio considering several kinds of surface defects. By exploring the dependence of the magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films, we demonstrate the crucial role of the chemical nature of the surface. For instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger than those of Co-terminated films.

Angular Leaf Spot of Cucurbits is Associated With Genetically Diverse Pseudomonas syringae Strains.

Angular leaf spot of cucurbits is generally considered to be caused by Pseudomonas syringae pv. lachrymans. It has a worldwide distribution and has been observed to emerge sporadically under humid and wet conditions.

Evidence for the Preemptive Nature of Tomato Race 3 of Xanthomonas campestris pv. vesicatoria in Florida.

ABSTRACT Until recently, tomato race 1 (T1) of Xanthomonas campestris pv. vesicatoria was the only race causing bacterial spot of tomato in Florida. In 1991, tomato race 3 (T3) was first identified in 3 of 13 tomato production fields surveyed.

Multiphasic analysis of xanthomonads causing bacterial spot disease on tomato and pepper in the Caribbean and central america: evidence for common lineages within and between countries.

ABSTRACT Four hundred thirty-three xanthomonad strains isolated from tomato or pepper plants from 32 different fields in four Caribbean and Central American countries were screened for the ability to hydrolyze starch and sodium polypectate and for resistance to copper and streptomycin. Of these, 95 representative strains were further characterized by various phnetic tests, and 63 of these strains were then analyzed by genomic fingerprinting. Most of the strains (>90%) were tolerant to copper.

Reclassification of the xanthomonads associated with bacterial spot disease of tomato and pepper.

Four phenotypic xanthomonad groups have been identified that are pathogenic to pepper, tomato, or both hosts. These include groups A and C which are found in Xanthomonas axonopodis pv. vesicatoria, group B found in X.

Diversity among xanthomonads pathogenic on pepper and tomato.

Xanthomonas campestris pv. vesicatoria, causal agent of bacterial spot of tomato and pepper, had been considered for nearly 70 years to be a relatively homogeneous organism. However, in the past decade this bacterium was determined to be composed of two genetically and phenotypically distinct groups.

A New Bacterial Leaf Spot Disease of Broccolini, Caused by Pseudomonas syringae pathovar maculicola, in California.

In 1998, a new disease was detected on 3-week-old commercial broccolini (Brassica oleracea L. var. botrytis × B.

Agrobacterium larrymoorei sp. nov., a pathogen isolated from aerial tumours of Ficus benjamina.

Tumorigenic Agrobacterium strains isolated from tumours growing on pruned branches of Ficus benjamina have previously been shown to have unique opine metabolism and sufficient 16S rRNA sequence differences to suggest that they belong to a new species. DNA-DNA hybridization results confirmed that these strains represent a new species and Agrobacterium larrymoorei sp. nov.

Systematic analysis of xanthomonads (Xanthomonas spp.) associated with pepper and tomato lesions.

The taxonomy and evolutionary relationships among members of the genus Xanthomonas associated with tomato and pepper have been a matter of considerable controversy since their original description in 1921. These bacteria, which are a major affliction of tomato and pepper crops in warm and humid regions, were originally described as a single species, but subsequent research has shown the existence of at least two genetic groups differentiated by physiological, biochemical and pathological characteristics. This work synthesizes the findings from several approaches, including pathogenicity tests, enzymic activity, restriction fragment analysis of the entire genome, DNA-DNA hybridization and RNA sequence comparisons based on a 2097 base sequence comprising the 16S rRNA gene, the intergenic spacer located between the 16S and 23S rRNA genes and a small region of the 23S rRNA gene.

Stem Blight of Eustoma grandiflorum Caused by Sclerotium rolfsii.

During a 4-week period in May through June 1996, 15% of 50 mature lisianthus (Eustoma grandiflorum) 'Maurine Blue' and 'Maurine White' plants exhibited stem blight in a landscape planting in west-central Florida. Initial disease symptoms included stem necrosis at the soil line, and yellowing and tan discoloration of leaves. As blighting of the stem progressed, infected plants wilted and died.

Relatedness of strains of xanthomonas fragariae by restriction fragment length polymorphism, DNA-DNA reassociation, and fatty acid analyses.

The levels of relatedness of strains of Xanthomonas fragariae collected over several years from locations in Canada and the United States were compared by determining fatty acid methyl ester profiles, restriction fragment length polymorphisms (RFLP) based on pulsed-field gel electrophoresis (PFGE) analysis, and DNA-DNA reassociation values. Based on qualitative and quantitative differences in fatty acid profiles, the strains were divided into nine groups and four groups by the MIDI "10% rule" and unweighted pair analysis, respectively. Restriction analysis of genomic DNA by PFGE with two endonucleases (XbaI and SpeI) revealed four distinct profiles.

Novel Ti plasmids in Agrobacterium strains isolated from fig tree and chrysanthemum tumors and their opinelike molecules.

Galls naturally induced on Fig and chrysanthemum plants by strains of Agrobacterium contained, in addition to other well-characterized opines such as nopaline, three tumor-specific opinelike molecules. These molecules were identified as deoxy-fructosyl-glutamine (dfg), deoxy-fructosyl-5-oxo-proline (dfop), and chrysopine (Chilton et al., unpublished).

A new Agrobacterium strain isolated from aerial tumors on Ficus benjamina L.

Crown gall tumors, collected from branches of 1-year-old weeping fig (Ficus benjamina L.) trees, yielded both tumorigenic and nonpathogenic agrobacteria. On the basis of classical diagnostic tests, the nonpathogenic strains were identified as Agrobacterium tumefaciens, whereas the tumorigenic strains could not be assigned to any of the known terrestrial Agrobacterium spp.

Correlative Association between Resident Plasmids and the Host Chromosome in a Diverse Agrobacterium Soil Population.

Soil samples collected from a fallow field which had not been cultivated for 5 years harbored a population of Agrobacterium spp. estimated at 3 x 10 CFU/g. Characterization of 72 strains selected from four different isolation media showed the presence of biovar 1 (56%) and bv.

Complementary methodologies to identify specific agrobacterium strains.

Serological techniques and restriction enzyme cleavage patterns of total DNA were used to differentiate strains of Agrobacterium spp. Forty-five wild-type and plasmid-cured Agrobacterium strains were tested by immunodiffusion and immunofluorescence against polyclonal antisera to a crude ribosome preparation from Agrobacterium strains K84, U11, B6, A323, NT1, and C58. In immunodiffusion gels, these antisera reacted only with water-phenol extracts of the homologous strain, producing a single, strain-specific precipitin line.

Isolation of different agrobacterium biovars from a natural oak savanna and tallgrass prairie.

Populations of agrobacteria in excess of 10 CFU/g were recovered from 12 soil and root samples obtained from the Allison Savanna, Minn., a natural oak savanna and tallgrass prairie which has never been disturbed agriculturally. Of 126 strains picked randomly from selective media, 54 were identified as Agrobacterium spp.