Growth suppression of antibiotic-resistant Salmonella typhimurium DT104 by a non-DT104 strain in vitro

Growth suppression of antibiotic-resistant Salmonella typhimurium DT104 by a non-DT104 strain was investigated in vitro. Chromosomal mutants of eight antibiotic-resistant DT104 strains were generated by sub-culturing on desoxycholate hydrogen sulfide lactose agar containing 25 µg/ml of nalidixic acid. Low counts of each of these mutants (designated as “minority cultures”) were inoculated into 24-h cultures of a non-DT104 S. typhimurium strain (designated as “majority culture”) to test the ability of the majority culture to suppress the multiplication of the minority culture. Multiplication of small numbers of the antibiotic-resistant DT104 strains was significantly (P < 0.05) prevented when the DT104s were added to 24-h brain heart infusion cultures of the non-DT104 strain. This observation has practical implications for the control of the menacing antibiotic-resistant Salmonella typhimurium DT104

Oxygen vacancy segregation and space-charge effects in grain boundaries of dry and hydrated BaZrO3

A space-charge model is applied to describe the equilibrium effects of segregation of double-donor oxygen vacancies to grain boundaries in dry and wet acceptor-doped samples of the perovskite oxide BaZrO3. The grain boundary core vacancy concentrations and electrostatic potential barriers resulting from different vacancy segregation energies are evaluated. Density-functional calculations on vacancy segregation to the mirror-symmetric \Sigma 3 (112) [-110] tilt grain boundary are also presented. Our results indicate that oxygen vacancy segregation can be responsible for the low grain boundary proton conductivity in BaZrO3 reported in the literature

ESR Modes in CsCuCl3 in Pulsed Magnetic Fields

We present ESR results for 35-134GHz in the antiferromagnet CsCuCl3 at T=1.5K. The external field is applied perpendicular to the hexagonal c-axis. With our pulsed field facility we reach 50T an unprecedented field for low temperature ESR. We observe strong resonances up to fields close to the ferromagnetic region of ~30T. These results are discussed in a model for antiferromagnetic modes in a two-dimensional frustrated triangular spin system.Comment: 3 pages, RevTeX, 3 figures. to be published in Solid State Communication

Linear-response theory of the longitudinal spin Seebeck effect

We theoretically investigate the longitudinal spin Seebeck effect, in which the spin current is injected from a ferromagnet into an attached nonmagnetic metal in a direction parallel to the temperature gradient. Using the fact that the phonon heat current flows intensely into the attached nonmagnetic metal in this particular configuration, we show that the sign of the spin injection signal in the longitudinal spin Seebeck effect can be opposite to that in the conventional transverse spin Seebeck effect when the electron-phonon interaction in the nonmagnetic metal is sufficiently large. Our linear-response approach can explain the sign reversal of the spin injection signal recently observed in the longitudinal spin Seebeck effect.Comment: Proc. of ICM 2012 (Accepted for publication in J. Korean Phys. Soc.), typos correcte

Kerr Correspondence 1907

A letter from the Pacific Era Publishing Company concerning Japanese students at Utah Agricultural College, a letter from Mrs. L. B. Best concerning a copy of the catalogue, and a letter from William Kerr in response of Mrs. L. B. Best\u27s letter

Evaporative Deposition Patterns Revisited: Spatial Dimensions of the Deposit

A model accounting for finite spatial dimensions of the deposit patterns in the evaporating sessile drops of colloidal solution on a plane substrate is proposed. The model is based on the assumption that the solute particles occupy finite volume and hence these dimensions are of the steric origin. Within this model, the geometrical characteristics of the deposition patterns are found as functions of the initial concentration of the solute, the initial geometry of the drop, and the time elapsed from the beginning of the drying process. The model is solved analytically for small initial concentrations of the solute and numerically for arbitrary initial concentrations of the solute. The agreement between our theoretical results and the experimental data is demonstrated, and it is shown that the observed dependence of the deposit dimensions on the experimental parameters can indeed be attributed to the finite dimensions of the solute particles. These results are universal and do not depend on any free or fitting parameters; they are important for understanding the evaporative deposition and may be useful for creating controlled deposition patterns.Comment: 34 pages, 14 figures, LaTeX; submitted to Physical Review

Analysis of the protein profiles of the antibiotic-resistant Salmonella typhimurium definitive phage type (dt) 104

The emergent Salmonella typhimurium definitive phage type (DT) 104 is of particular global concern due to its frequent isolation and multiple antibiotic resistances. There is thus a need to know the kind of proteins expressed by S. typhimurium DT104 so as to provide a basis for developing an intervention. This study examined the protein profiles of a few isolates of S. typhimurium DT104 and a non-DT104 strain S. typhimurium L1388 (ST). Crude SDS-soluble whole cell and outer membrane protein (OMP) extracts revealed similar protein profiles for both phage types. A single major protein band (28.4 kDa) was observed in periplasmic fractions from both phage types. However, proteins released into growth medium was variable; one of the DT104 isolates had common proteins with the non-DT104 strain ST. Similar SDS-soluble whole cell protein profiles were observed for both phage types grown in a low-iron Medium A at 37oC; but a 38.5 kDa protein (observed in TSB-grown cells) was observed only in the temperature-tolerant DT104 isolate. The protein contents of cell-free ultracentrifuge supernatants of sonically disrupted cells of each of the DT104 isolates were significantly (P < 0.05) more than that from ST L1388, but the latter expressed a 51-kDa protein absent in the supernatants of all DT104 isolates. The higher protein content of DT104s provides possible indication of increased production of protein-like metabolites. Although the N-terminal sequence of the first twenty amino acids of the 51-kDa protein (Ala-Gln-Val-Ile-Asn-Thr-Asn-Ser-Leu-Ser-Leu-Leu-Thr-Gln-Trp-Ala-Ala-Ala-Ala-Ala) showed 14-amino acid overlap and resemblance with the flagillin, FLIC, only fourteen of its 104 trypsin digests were homologous with those of FLIC. Further work is being done to characterize this protein and to investigate its potential for use as vaccine target through antigenicity tests.African Journal of Biotechnology Vol. 4 (7), pp. 727-737, 200

Second-order calculation of the local density of states above a nanostructured surface

We have numerically implemented a perturbation series for the scattered electromagnetic fields above rough surfaces, due to Greffet, allowing us to evaluate the local density of states to second order in the surface profile function. We present typical results for thermal near fields of surfaces with regular nanostructures, investigating the relative magnitude of the contributions appearing in successive orders. The method is then employed for estimating the resolution limit of an idealized Near-Field Scanning Thermal Microscope (NSThM).Comment: 10 pages, 7 figure

Giant Stark effect in the emission of single semiconductor quantum dots

We study the quantum-confined Stark effect in single InAs/GaAs quantum dots embedded within a AlGaAs/GaAs/AlGaAs quantum well. By significantly increasing the barrier height we can observe emission from a dot at electric fields of -500 kV/cm, leading to Stark shifts of up to 25 meV. Our results suggest this technique may enable future applications that require self-assembled dots with transitions at the same energy