Long-range surface plasmon-enhanced fluorescence spectroscopy biosensor for ultrasensitive detection of E. coli O157:H7

A new biosensor platform for the detection of bacterial pathogens based on long-range surface plasmon-enhanced fluorescence spectroscopy (LRSP-FS) is presented. The resonant excitation of LRSP modes provides an enhanced intensity of the electromagnetic field, which is directly translated to an increased strength of fluorescence signal measured upon the capture of target analyte at the sensor surface. LRSPs originate from a coupling of surface plasmons across a thin metallic film embedded in dielectrics with similar refractive indices. With respect to regular surface plasmon-enhanced fluorescence spectroscopy, the excitation of LRSPs offers the advantage of a larger enhancement of the evanescent field intensity and a micrometer probing depth that is comparable to the size of target bacterial pathogens. The potential of the developed sensor platform is demonstrated in an experiment in which the detection of E. coli O157:H7 was carried out using sandwich immunoassays. The limit of detection below 10 cfu mL(-1) and detection time of 40 min were achieved.     

The enzymatic degradation of DDT. 3. Metabolism of DDT

DDT orally given to rats is converted into DDD by reductive dechlorination in the liver within 30 min. 6 h after a single application of 10 mg DDT per rat a quantity of 60 mg DDD/kg was indicated in the liver. DDT is stored in the adrenal glands; in the other organs an equilibrium comes up obviously, even with further application. The quantitative ratios are reported. Information on the experimental details of DDT determination and--anticipatory to the following publications--on the analysis of the most relevant metabolites is given.     

Synthesis of (Hg,X)Ba2Ca2Cu3Ox Superconductors

Synthesis and processing parameters for (Hg_1?xBi_x)Ba₂Ca₂Cu_3.1O_y were optimized for growth at temperatures suitable for growth on Ag and Au substrates (<850° C). Use of Bi₂CuO₄ as a Bi source combined with variations of BaCaCuO precursor phase assemblages allowed the formation of some liquid phase during the reaction and resulted in dense (Hg_1?xBi_x)Ba₂Ca₂Cu_3.1O_y samples with aligned colonies of grains. Magnetization measurements in fields up to 30 T indicated good intergrain coupling within the large grain colonies. The results of the Bi doped samples are compared with those of previously reported Re doped samples.     

Flow Diagram Simulator for the Cement Industry

The most important aspect of work performed in a process engineering department is the development of process flow diagrams. These diagrams display the results of energy and material balances and equipment rating calculations for a complex process plant. The development, features, and implementation of a computerized flow diagram simulation program named Fuller's interactive simulator for process engineering calculations (FISPEC) are described. FISPEC is a comprehensive flow diagram simulator which performs steady-state energy and material balance calculations for a minerals processing plant. FISPEC allows the connection of process streams (solid, gas, liquid, or fuel), with the equipment simulation models that constitute a flow diagram. The unique features of FISPEC include an interactive language that allows the process engineer to step through the flow diagram stream by stream. This language is flexible to use yet rigid enough to simulate any process found on a flow diagram. A second feature is a restore backup feature that enables the process engineer to program the flow diagram in the simulator language and then rerun this program at a later date with any modifications that might have occurred. FiISPEC also includes an interface capability between the simulator and a computer graphics system. This graphics interface eliminates the manual intervention formerly required in the construction of a process flow diagram.     

Determination of Fluorescent Whiteness: Experience in Using Linear Whiteness Formulae

Experience has been obtained in the use of two linear whiteness formulae on a varied set of near-white cloth samples. Visual assessments of whiteness were made with the aid of the Ciba-Geigy Plastic White Scale plates. These were compared with predicted whiteness values based on the tristimuhis total radiance factors (reflectance plus fluorescent emission) measured with a photometer fitted with illuminant D60. Good agreement was obtained when the parameters of the prediction formulae were determined by regression analysis, using measurements made on the plates of the White Scale with the same photometer. The closeness of agreement for the cloth samples was examined as a function of hue preference angle. It was found that the formula based on chromaticity coordinates gave superior results to the formula using the radiance factors directly. The practical application of the formula based on chromaticity coordinates is described.     

Surface plasmon and guided optical wave microscopies

This article summarizes some recent developments in the field of surface plasmon and guided optical wave microscopies. It is shown that these imaging techniques based on evanescent light allow for a quantitative optical characterization of ultrathin films with a thickness sensitivity of a few Ångstroms and a lateral resolution of μm.     

Temperature-jump experiments on thin lipid membranes in the presence of valinomycin

Temperature jump relaxation experiments on planar lipid membranes in the presence of valinomycin were performed using the absorption of a strong light flash as an energy source for the generation of the T-jump. The relaxation of the current carried by valinomycin/Rb+ complexes was measured. The results were interpreted on the basis of a transport model which was also analyzed by voltage jump relaxation experiments. The study shows that the application of the T-jump technique provides valuable information about transport kinetics as well as the dynamics of the membrane structure. At the given experimental conditions the relaxation of the current is believed to reflect a temperature-dependent transition of the membrane to a new conformational state of low order. The relaxation could be resolved with the present technique only at low temperatures and for membranes of high microviscosity.