Rapid simultaneous ultrasensitive immunodetection of five bacterial toxins

Rapid ultrasensitive detection of gastrointestinal pathogens presents a great interest for medical diagnostics and epidemiologic services. Though conventional immunochemical and polymerase chain reaction (PCR)-based methods are sensitive enough for many applications, they usually require several hours for assay, whereas as sensitive but more rapid methods are needed in many practical cases. Here, we report a new microarray-based analytical technique for simultaneous detection of five bacterial toxins: the cholera toxin, the E. coli heat-labile toxin, and three S. aureus toxins (the enterotoxins A and B and the toxic shock syndrome toxin). The assay involves three major steps: electrophoretic collection of toxins on an antibody microarray, labeling of captured antigens with secondary biotinylated antibodies, and detection of biotin labels by scanning the microarray surface with streptavidin-coated magnetic beads in a shear-flow. All the stages are performed in a single flow cell allowing application of electric and magnetic fields as well as optical detection of microarray-bound beads. Replacement of diffusion with a forced transport at all the recognition steps allows one to dramatically decrease both the limit of detection (LOD) and the assay time. We demonstrate here that application of this "active" assay technique to the detection of bacterial toxins in water samples from natural sources and in food samples (milk and meat extracts) allowed one to perform the assay in less than 10 min and to decrease the LOD to 0.1-1 pg/mL for water and to 1 pg/mL for food samples.     

Object permanence tests on gibbons (Hylobatidae).

Ten gibbons of various species (Symphalangus syndactylus, Hylobates lar, Nomascus gabriellae, and Nomascus leucogenys) were tested on object permanence tasks. Three identical wooden boxes, presented in a linear line, were used to hide pieces of food. The authors conducted single visible, single invisible, double invisible, and control displacements, in both random and nonrandom order. During invisible displacements, the experimenter hid the object in her hand before putting it into a box. The performance of gibbons was better than expected by chance in all the tests, except for the randomly ordered double displacement. However, individual analysis of performance showed great variability across subjects, and only 1 gibbon is assumed to have solved single visible and single invisible displacements without recourse to a strategy that the control test eliminated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An annotated bibliography on guaranteed graph searching

Graph searching encompasses a wide variety of combinatorial problems related to the problem of capturing a fugitive residing in a graph using the minimum number of searchers. In this annotated bibliography, we give an elementary classification of problems and results related to graph searching and provide a source of bibliographical references on this field.     

Programmable Biopolymers for Advancing Biomedical Applications of Fluorescent Nanodiamonds

A versatile biopolymer platform for advancing nanodiamonds (NDs) as unique magnetooptic materials for biomedical applications is presented here. Precision biopolymer coatings are designed by chemical reprogramming the functionalities of serum albumin via a straightforward synthesis protocol. Such biopolymers offer high biocompatibility and precise modification with various functional entities due to the large number of available reactive amino acid residues. Premodification of these biopolymers provides a convenient approach to customized surface functionalization of NDs. As an example, the anticancer drug doxorubicin (DOX) is conjugated to the biopolymer with high reproducibility and full characterization. The biopolymer‐coated NDs reveal excellent colloidal stabilities in all physiological media tested, even after loading with high numbers of hydrophobic DOX. The intracellular distribution of NDs and DOX is analyzed in living cells by recording the fluorescence spectra in different cellular compartments, which proves efficient intracellular release of DOX from the carrier. Studies in vitro as well as in a chick tumor xenograft model reveal efficient antitumor effects. The facile and versatile biopolymer coating strategy reported herein will greatly accelerate the availability of customized NDs with reliable and reproducible features to exploit their great potential in single molecular bioimaging, in vivo biosensing, and high resolution quantum optics.     

Perceptions of politics: does measuring different foci matter?

Recent research on perceptions of politics in organizations and other organizational phenomena (e.g., commitment) has suggested the use of a multiple-foci approach to understand important politics-outcome relationships. This study confirms separate measures of perceptions of politics at the organizational and work-group levels and demonstrates differential effects in the prediction of various outcomes. After controlling for the effects of the relationship with one's supervisor (leader-member exchange), perceptions of politics existing at the organizational level predicted turnover intentions, whereas citizenship behavior was predicted by perceptions of politics at the group level. Both foci of politics significantly predicted organizational commitment.     

Anisotropic Superconductivity and Vortex Dynamics in?Magnetically Coupled F/S and F/S/F Hybrids

Magnetically coupled superconductor?Cferromagnet hybrids offer advanced routes for nanoscale control of superconductivity. Magnetotransport characteristics and scanning tunneling microscopy images of vortex structures in superconductor?Cferromagnet hybrids reveal rich superconducting phase diagrams. Focusing on a particular combination of a ferromagnet with a well-ordered periodic magnetic domain structure with alternating out-of-plane component of magnetization, and a small coherence length superconductor, we find directed nucleation of superconductivity above the domain wall boundaries. We show that near the superconductor-normal state phase boundary the superconductivity is localized in narrow mesoscopic channels. In order to explore the Abrikosov flux line ordering in F/S hybrids, we use a combination of scanning tunneling microscopy and Ginzburg?CLandau simulations. The magnetic stripe domain structure induces periodic local magnetic induction in the superconductor, creating a series of pinning?Canti-pinning channels for externally added magnetic flux quanta. Such laterally confined Abrikosov vortices form quasi-1D arrays (chains). The transitions between multichain states occur through propagation of kinks at the intermediate fields. At high fields we show that the system becomes nonlinear due to a change in both the number of vortices and the confining potential. In F/S/F hybrids we demonstrate the evolution of the anisotropic conductivity in the superconductor that is magnetically coupled with two adjacent ferromagnetic layers. Stripe magnetic domain structures in both F-layers are aligned under each other, resulting in a directional superconducting order parameter in the superconducting layer. The conductance anisotropy strongly depends on the period of the magnetic domains and the strength of the local magnetization. The anisotropic conductivity of up to three orders of magnitude can be achieved with a spatial critical temperature modulation of 5% of T _c. Induced anisotropic properties in the F/S and F/S/F hybrids have a potential for future application in switching and nonvolatile memory elements operating at low temperatures.     

High thermal conductivity composites consisting of diamond filler with tungsten coating and copper (silver) matrix

Tungsten coatings with thickness of 5–500 nm are applied onto plane-faced synthetic diamonds with particle sizes of about 430 and 180 μm. The composition and structure of the coatings are investigated using scanning electron microscopy, X-ray spectral analysis, X-ray diffraction, and atomic force microscopy. The composition of the coatings varies within the range W–W₂C–WC. The average roughness, R _a, of the coatings’ surfaces (20–100 nm) increases with the weight–average thickness of the coating. Composites with a thermal conductivity (TC) as high as 900 W m⁻¹ K⁻¹ are obtained by spontaneous infiltration, without the aid of pressure, using the coated diamond grains as a filler, and copper or silver as a binder. The optimal coating thickness for producing a composite with maximal TC is 100–250 nm. For this thickness the heat conductance of coatings as a filler/matrix interface is calculated as G = (2–10) × 10⁷ W m⁻² K⁻¹. The effects of coating composition, thickness and roughness, as well as of impurities, on wettability during the metal impregnation process and on the TC of the composites are considered.     

Tokay wines as scavengers of free radicals (an EPR study)

Wines are increasingly considered to be beneficial to health, so we expanded our previous investigations of red and white wines to Tokay wines, employing electron paramagnetic resonance spectroscopy (EPR). Four sources of free radicals were used in scavenging experiments: thermally decomposed radical initiators, K₂S₂O₈ and 2,2′-azo-bis(2-methylpropionamidine) hydrochloride (AAPH), as well as the cation radical of 2,2′-azino-bis(3-ethylbenthiazoline-6-sulfonic acid) salt (ABTS), and the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The radical-scavenging abilities of 30 samples of Tokay wines from the Slovak region were compared with 10 samples of red and 10 samples of white wines originating from various regions. Tokay wines show a very good scavenging ability, positioned between white and red wines expressed as trolox equivalent antioxidant capacities (TEAC) with 14.8 ± 1.5 for red, 8.1 ± 3.4 Tokay and 3.3 ± 1.6 for white wines in mmol dm⁻³ wine.     

Processing of photonic crystal nanocavity for quantum information in diamond

The realization of photonic crystals (PC) in diamond is of major importance for the entire field of spintronics based on fluorescent centers in diamond. The processing steps for the case of diamond differ from those commonly used, due to the extreme chemical and mechanical properties of this material. The present work summarizes the state of the art in the realization of PC's in diamond. It is based on the creation of a free standing diamond membrane into which the desired nano-sized patterns are milled by the use of Focused-Ion-Beam (FIB). The optimal fabrication-oriented structure parameters are predicted by simulations. The milling strategies, the method of formation the diamond membrane, recipes for dielectric material-manipulation in FIB and optical characterization constraints are discussed in conjunction with their implication on PC cavity design. The thus produced structures are characterized via confocal photoluminescence.     

Structure‐Based Design of Small‐Molecule Ligands of Phosphofructokinase‐2 Activating or Inhibiting Glycolysis

Glycolysis lies at the basis of metabolism and cell energy supply. The disregulation of glycolysis is involved in such pathological processes as cancer proliferation, neurodegenerative diseases, and amplification of ischemic damage. Phosphofructokinase‐2 (PFK‐2), a bifunctional enzyme and regulator of glycolytic flux, has recently emerged as a promising anticancer target. Herein, the computer‐aided design of a new class of aminofurazan‐triazole regulators of PFK‐2 is described along with the results of their in vitro evaluation. The aminofurazan‐triazoles differ from other recently described inhibitors of PFK‐2 and demonstrate the ability to modulate glycolytic flux in rat muscle lysate, producing a twofold decrease by inhibitors and fourfold increase by activators. The most potent compounds in the series were shown to inhibit the kinase activity of the hypoxia‐inducible form of PFK‐2, PFKFB3, as well as proliferation of HeLa, lung adenocarcinoma, colon adenocarcinoma, and breast cancer cells at concentrations in the low micromolar range.