No abstract

In this study, a sensitive fluorescence sensor was developed for the detection of small, fluorescence-labeled particles dispersed in a solution. The prototype system comprises of a laser confocal optical system and a mechanical sample stage to detect photon bursting of fluorescence-labeled small particles in sample volumes less than 5 μL within 3 minutes. To examine the feasibility of the prototype system as a diagnostic tool, assemblages of rotavirus and fluorescence-labeled antibody were analyzed. The detection sensitivity for rotavirus was 1 × 10 pfu/mL. Rotavirus in stool samples from patients with acute gastroenteritis was also detected. The advantages and disadvantages of this immunosensor with respect to ELISA and RT-PCR, the current gold standards for virus detection, are discussed.

Magnetic susceptibility and proton nuclear magnetic resonance ( 1 H-NMR) measurements were performed for the quasi-two-dimensional π -d interacting system λ-(BEDT-STF) 2 FeCl 4 at ambient pressure. Magnetic susceptibility arising from the 3d spins of the FeCl 4 anion show an anisotropy at low temperature and its temperature dependence for the external field parallel to the c axis is described as a broad peak structure at 8 K. A sharp peak in the temperature dependence of T −1 1 associated with the antiferromagnetic (AF) transition is observed at T AF = 16 K, together with the drastic splitting of the NMR spectrum below T AF . The relation between the static susceptibility and the splitting of the NMR shift suggests the existence of the relatively strong d-d AF interaction. These results can be explained by the model considering the AF-coupled d-spin system in the AF long-range-ordered π -spin system. We find that the AF phases in λ-type salts can be universally explained by this model.