Avoided metallicity in a hole-doped Mott insulator on a triangular lattice.

Doping of a Mott insulator gives rise to a wide variety of exotic emergent states, from high-temperature superconductivity to charge, spin, and orbital orders. The physics underpinning their evolution is, however, poorly understood. A major challenge is the chemical complexity associated with traditional routes to doping.

Interfacial charge transfer complex formation between silver nanoparticles and aromatic amino acids.

The optical properties of surface-modified silver nanoparticles (Ag NPs) with aromatic amino acids tryptophan (Trp) and histidine (His) were examined using the cluster model for density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Also, the redistribution of electronic charges upon chemisorption of ligand molecules onto silver's surfaces is determined. The obtained theoretical data, on one side, undoubtedly indicate the the formation of an interfacial charge transfer (ICT) complex between silver and this type of ligand, and, on the other side, partial oxidation of surface silver atoms accompanied by an increase of electron density in ligand molecules.

Carbide coating on nickel to enhance the stability of supported metal nanoclusters.

The influence on the growth of cobalt (Co)-based nanostructures of a surface carbide (NiC) layer formed at the Ni(100) surface is revealed complementary scanning tunneling microscopy (STM) measurements and first-principles calculations. On clean Ni(100) below 200 °C in the sub-monolayer regime, Co forms randomly distributed two-dimensional (2D) islands, while on NiC it grows in the direction perpendicular to the surface as well, thus forming two-atomic-layers high islands. We present a simple yet powerful model that explains the different Co growth modes for the two surfaces.

Spin Excitations in a 4f-3d Heterodimer on MgO.

We report on the magnetic properties of HoCo dimers as a model system for the smallest intermetallic compound of a lanthanide and a transition metal atom. The dimers are adsorbed on ultrathin MgO(100) films grown on Ag(100). New for 4f elements, we detect inelastic excitations with scanning tunneling spectroscopy and prove their magnetic origin by applying an external magnetic field.

Osteonecrosis of the Jaw After Bisphosphonates Treatment in Patients with Multiple Myeloma.

Background: Bone lytic lesion in Multiple myeloma are the most commonly presented symptoms which require treatment with bisphosphonates (BPs). BPs are providing supportive care, reducing the rate of skeletal morbidity but evidently not abolishing it, the criteria for stopping their administration have to be different from those used for classic antineoplastic drugs, and they should not be stopped when metastatic bone disease is progressing. Osteonecrosis of the jaw (ONJ) has been associated recently with the use of BPs.

Does Vibrio vulnificus present a health threat to Canadians?

Objective: To review recent data on Vibrio vulnificus and its properties, characteristics of disease and epidemiology, sources of infection, population at risk, infectious dose, documented cases of infection and health risk from V vulnificus infection in Canada.

Data Source: A MEDLINE and CURRENT CONTENTS search (1981 through September 1996) using the main heading 'Vibrio vulnificus', 'Vibrio species', 'seafood', etc. Relevant articles were also selected from the literature collection in the authors' laboratory.

Intestinal colonization of young chicks with Escherichia coli O157:H7 and other verotoxin-producing serotypes.

The susceptibility of chicks to colonization with Escherichia coli O157:H7 and other verotoxin-producing serotypes was studied. The E. coli colonized the caeca of both broilers and layers after oral administration of the challenge.

Undefined and Defined Bacterial Preparations for the Competitive Exclusion of Salmonella in Poultry - A Review.

During the past two decades, there have been many studies on the efficacy of competitive exclusion for the control of Salmonella in poultry. Undefined preparations of cultured fecal or cecal microflora generally reduce the prevalence of infected chicks upon challenge with a standard dose of Salmonella under laboratory conditions; in contrast, results under field conditions are more variable. The protective capacity of undefined cultures can be affected by several factors including the source of microflora, method for protective culture administration, presence of poultry feed additives, in-laboratory or natural environmental challenge, and hygienic practices on the farm.

Defined cultures and prospects.

Resistance of young chicks to Salmonella colonization can be increased by treating them with suspensions or anaerobic cultures of gut content from healthy, adult birds. Unfortunately, such treatments have an unknown bacterial composition and are therefore not acceptable to regulatory agencies in some countries. Efforts are continuing to identify components in the gut microflora that are involved in the protective process.

Comparison of a competitive enzyme immunoassay kit and the infant mouse assay for detecting Escherichia coli heat-stable enterotoxin.

A commercial competitive enzyme immunoassay kit, Escherichia coli ST EIA, was compared with the conventional infant mouse assay for sensitivity and specificity in detecting E. coli heat-stable enterotoxin. Thirty-one of 46 strains of E.

Assessment of two commercial agglutination kits for detecting Escherichia coli heat-labile enterotoxin.

Two commercial agglutination kits, a reserved passive agglutination test (VET-RPLA) and a staphylococcal coagglutination test (Phadebact ETEC-LT Test), were compared with two cell culture assays (Y-1 and Vero) and GM1 ganglioside enzyme-linked immunosorbent assay (GM1-ELISA) for sensitivity in detecting Escherichia coli heat-labile enterotoxin (LT). Of 48 toxigenic strains, 23 were positive by all assays. One strain was negative only by the Phadebact test.

Effect of avian intestinal microflora possessing adhering and hydrophobic properties on competitive exclusion of Salmonella typhimurium from chicks.

The role of adherence and hydrophobic properties of native gut microflora in competitive exclusion of salmonellas from chicks is reported. Pure bacterial strains were isolated from washed caeca of 3-d-old chicks which had been treated on the day of hatch with a microflora from salmonella-free adult birds. These strains, when added to known mixtures of pure cultures, improved the efficacy of the mixtures in protecting chicks against a challenge of 10(5) cfu of Salmonella typhimurium.

Protection of chicks against Salmonella infection with a mixture of pure cultures of intestinal bacteria.

A mixture of 28 pure cultures was prepared from the organisms isolated from native gut microflora (fecal and cecal contents) of adult Salmonella-free birds. This mixture was orally administered to 1-day-old chicks and examined for its efficacy against challenge with 10(5) colony-forming units of nalidixic-acid-resistant Salmonella typhimurium in six consecutive trials during a 20-month period. The efficacy of the mixture, which was prepared for each trial from stored isolates, progressively decreased, while that from stored fecal content remained unimpaired.

Recommended Assay for Treatment of Chicks to Prevent Salmonella Colonization by 'Competitive Exclusion'.

An assay is described for evaluating live-culture treatment material that may be given orally to chicks to prevent intestinal colonization by non-host-specific salmonellae. Both pre-treated and control chicks are challenged with 10 salmonellae/chick, using a strain bearing an antibiotic resistance marker. Chicks are examined 5 d after challenge to determine both the proportion of positive birds in treated and control groups and the levels of Salmonella in the caeca of infected individuals.

Role of Adhering Microflora in Competitive Exclusion of Salmonella from Young Chicks.

Adherence of gut microflora from Salmonella -free adult birds to the ceca of newly hatched chicks, and their role in protection against Salmonella was examined. The protective microflora remained attached to the cecal wall after four successive washings. Cultures of washed ceca taken from chicks 30 min to 1 h after treatment with fecal culture gave partial protection.

ICMSF Methods Studies. XVI. Comparison of Salt Polymyxin Broth with Glucose Salt Teepol Broth for Enumerating Vibrio parahaemolyticus in Naturally Contaminated Samples.

Two media, glucose salt teepol broth (GSTB) and salt polymyxin broth (SPB), were compared for their efficacy in enumerating Vibrio parahaemolyticus in naturally contaminated samples using the most probable number (MPN) procedure. Eleven laboratories in four countries participated, six of them using two analysts. One hundred ninety-six of 335 samples were found to contain V.

Competitive Exclusion of Salmonella from Newly Hatched Chicks by Mixtures of Pure Bacterial Cultures Isolated from Fecal and Cecal Contents of Adult Birds.

Oral administration of defined mixtures of bacterial isolates from fecal and cecal contents of adult chickens protected young chicks against infection with Salmonella . One-day-old chicks were treated with mixtures containing 50, 40, 25 and 10 bacterial isolates and challenged 2 d later with 10, 10 and 10 colony-forming units of nalidixic acid-resistant Salmonella typhimurium . The chicks were examined for infection 6 d after challenge.

Minimum Intestinal Inoculum for Nurmi Cultures and a New Method for Determining Competitive Exclusion of Salmonella from Chicks.

Protection of chicks against Salmonella infection was obtained by oral administration of Nurmi cultures. The Nurmi cultures were prepared by inoculating adult chicken intestinal material (10 to 10 g) into anaerobic liquid medium and incubating for 3 d at 37°C. Excellent protection was obtained with cultures initiated with as little as 10 g of fecal or cecal content; progressively less protection with 10 to 5 × 10 g; and none with cultures initiated with 10 g.

Loss of Polymyxin B From Enrichment Broth for Vibrio parahaemolyticus.

Polymyxin B sulfate (PB) added to salt broth (SB) for selective enrichment of Vibrio parahaemolyticus was destroyed by autoclaving. Losses were about 49% at pH 7.4 and 97% at pH 8.

Comparative studies of five heat-labile toxic products of Escherichia coli.

Five heat-labile, partially purified toxic products of Escherichia coli were distinguished by isoelectric focusing, molecular weight, and neutralization with homologous and heterologous antisera. Only two affected the morphology of Y-1 cells, induced fluid accumulation in rabbit ileal loops, and stimulated production of cyclic AMP in Vero cells; these two did not cross-neutralize and only one showed cross-neutralization with cholera antitoxin. The remaining three products were cytotoxic for Vero cells.

Stimulation of cyclic AMP secretion in Vero cells by enterotoxins of Escherichia coli and Vibrio cholerae.

The morphological response of Vero cells to Escherichia coli heat-labile enterotoxin was similar to that of cholera toxin and was accompanied by increases in the intracellular level of cyclic AMP. The effects of both enterotoxins were enhanced by the presence of phosphodiesterase inhibitor and inhibited by heat or specific antisera. Accumulation of cyclic AMP preceded the morphological response.

Properties of an Escherichia coli cytotoxin.

Isoelectric focusing of a heat-labile cytotoxin of Escherichia coli H30 revealed the presence of two molecular variants, pI 7.2 and a comparatively small quantity of pI 6.8.

Vero response to a cytotoxin of Escherichia coli.

A cytotoxin was found in culture filtrates of a number of Escherichia coli strains that differed from the known heat-stable and heat-labile enterotoxins of E. coli. It was cytotoxic for Vero but not for Y-1 or CHO cells, and its effect on Vero was distinctly different from that of heat-labile enterotoxin.

Assay of Escherichia coli heat-labile enterotoxin with vero cells.

The continuous cell line of African green monkey kidney, Vero, showed characteristic morphological changes in response to culture filtrates from toxigenic strains of Escherichia coli. The response compared favorably with that of Y-1 (mouse adrenal) and CHO (Chinese hamster ovary) cells. Vero cells were the simplest and most economical to maintain in the laboratory.