Atomic-scale structure of the SrTiO3(001)-c(6x2) reconstruction: Experiments and first-principles calculations

The c(6x2) is a reconstruction of the SrTiO3(001) surface that is formed between 1050-1100oC in oxidizing annealing conditions. This work proposes a model for the atomic structure for the c(6x2) obtained through a combination of results from transmission electron diffraction, surface x-ray diffraction, direct methods analysis, computational combinational screening, and density functional theory. As it is formed at high temperatures, the surface is complex and can be described as a short-range ordered phase featuring microscopic domains composed of four main structural motifs. Additionally, non-periodic TiO2 units are present on the surface. Simulated scanning tunneling microscopy images based on the electronic structure calculations are consistent with experimental images

Validated Sandwich ELISA for the Quantification of von Willebrand Factor in Rabbit Plasma

von Willebrand Factor (vWF) is a multimeric plasma protein important for platelet plug formation. As part of its haemostatic role, it is released from endothelial cells during vascular stress or injury and is considered an excellent biomarker of endothelial function. Currently, there are no validated kits available to measure vWF in rabbits. We developed a sensitive and reproducible sandwich enzyme-linked immunosorbent assay (ELISA) for detection of vWF in rabbit plasma using commercially available antibodies and reagents. Purified human vWF was used as a calibrator standard with a dynamic range of 1.56–100 ng/mL. The Minimum Required Dilution for rabbit plasma was 1:100. When plasma was spiked with 3.76 or 10 ng/mL vWF, recovery was 108 ± 2% and 93 ± 2%, respectively. Intra- and inter-assay precision for 8 rabbit plasma samples were 3% and 4%, respectively. The Minimum Detectable Concentration was 254 pg/mL for purified human vWF and 1:10,700 dilution of cholesterol-fed rabbit plasma, and the Reliable Detection Limits were 457 pg/mL and 1:5940. Three freeze-thaw cycles significantly decreased vWF concentrations for purified human vWF and 2 of 3 plasma samples assayed. This ELISA provides sensitive and reproducible measurements of rabbit plasma vWF, which is an important biomarker for cardiovascular research

Isolation of Salmonella using pooled pen feces from 37 U.S. swine farms

The purpose of this study was to culture the pooled pen feces of market weight pigs in order to determine the most common Salmonella serotypes being shed and to see if farms positive by culture were also positive by serology. Isolates were analyzed to determine if they had 0-antigens capable of inducing an immune response detectable by the Danish Mix-ELISA

Multiorgan WU polyomavirus infection in bone marrow transplant recipient

WU polyomavirus (WUPyV) was detected in a bone marrow transplant recipient with severe acute respiratory distress syndrome who died in 2001. Crystalline lattices of polyomavirus-like particles were observed in the patient’s lung by electron microscopy. WUPyV was detected in the lung and other tissues by real-time quantitative PCR and identified in the lung and trachea by immunohistochemistry. A subset of WUPyV-positive cells in the lung had morphologic features of macrophages. Although the role of WUPyV as a human pathogen remains unclear, these results clearly demonstrate evidence for infection of respiratory tract tissues in this patient

Virulence determination for rapid extraintestinal Dissemination (Acute Infection) of Common Salmonella Serotypes in Swine

Salmonella enterica (Typhimurium and Choleraesuis) have been shown to rapidly disseminate extraintestinally (RED) within 3 hours of intranasal inoculation in pigs (Fedorka-Cray et al., 1995) (Blaha et al., 1997) (Nugent et al., 2000) (Nielsen, 2000). Evaluation of RED serotypes may be an important indicator of Salmonella virulence. Experimentally, pigs were challenged with important lymph node, fecal and vaccine isolates ofSalmonella and evaluated for RED. These isolates include: Salmonella Heidelberg, Salmonella Infantis, Salmonella Derby, Salmonella Worthington, Salmonella 4, 12 i-monophasic, Salmonella untypable HL I 0416, Salmonella Typhimurium, Salmonella Typhimurium variant Copenhagen, Salmonella Bredeney, Salmonella Muenchen, Salmonella Brandenburg, Salmonella Choleraesuis SC-38, Salmonella Choleraesuis SC-54, and Salmonella Choleraesuis strain Argus. Three hours after intranasal inoculation, the pigs were euthanized, necropsied, and the following tissues were collected for qualitative isolation: tonsil, thymus, blood, mandibular lymph node, lung, spleen, liver, ileocecal lymph node, colon contents and cecum contents. Fewer tissues were positive for vaccine strains as compared to wild type or parent strains

Electronic and Structural Properties of a 4d-Perovskite: Cubic Phase of SrZrO3_3

First-principles density functional calculations are performed within the local density approximation to study the electronic properties of SrZrO$_3$, an insulating 4d-perovskite, in its high-temperature cubic phase, above 1400 K, as well as the generic 3d-perovskite SrTiO$_3$, which is also a d^0-insulator and cubic above 105 K, for comparison reasons. The energy bands, density of states and charge density distributions are obtained and a detailed comparison between their band structures is presented. The results are discussed also in terms of the existing data in the literature for both oxides.Comment: 5 pages, 2 figure

Theoretical study of the absorption spectra of the lithium dimer

For the lithium dimer we calculate cross sections for absorption of radiation from the vibrational-rotational levels of the ground X [singlet Sigma g +] electronic state to the vibrational levels and continua of the excited A [singlet Sigma u +] and B [singlet Pi u] electronic states. Theoretical and experimental data are used to characterize the molecular properties taking advantage of knowledge recently obtained from photoassociation spectroscopy and ultra-cold atom collision studies. The quantum-mechanical calculations are carried out for temperatures in the range from 1000 to 2000 K and are compared with previous calculations and measurements.Comment: 20 pages, revtex, epsf, 6 fig