Single-step sandwich immunoreaction in a square glass capillary immobilizing capture and enzyme-linked antibodies for simplified enzyme-linked immunosorbent assay

To simplify the complicated operation steps and to minimize sample and reagent amounts for enzyme-linked immunosorbent assays (ELISA), we developed a square glass capillary immunosensor containing both covalently immobilized capture antibodies and physically adsorbed enzyme-linked antibodies. The immobilization of capture antibodies (anti-human IgG) was carried out by the treatment of 3-aminopropyltriethoxy silane, glutaraldehyde, and protein-A, followed by affinity capture of the antibody. In contrast, the enzyme-linked antibodies (alkaline phosphatase (ALP)-linked anti-human IgG) were physically adsorbed on the four corners of the capillary with the aid of polyethylene glycol (PEG) acting as a scaffold. A nanoliter volume of antigen (human IgG)-containing sample solution was introduced via capillary action. This addition resulted in the release and diffusion of ALP-linked anti-human IgG into the bulk solution. This event led to a 20-min single-step sandwich immunoreaction at the inner wall of capillary; the reaction was detected through the reaction with fluorescein diphosphate (FDP) which generated a fluorescent product, fluorescein. Using this technique, we obtained an intra-capillary precision with a coefficient of variation of 9.7%. In addition, the specificity study showed that the human IgG capillary immunosensor did not respond to rabbit IgG. Quantitative analysis was possible within the response range of 10 - 5000 ng mL(-1) anti-human IgG. This capillary immunosensor can act as a single analytical unit or can be integrated into a capillary array for multiple bioanalysis.     

Enhancement in thermal stability and resistance to denaturants of lipase encapsulated in mesoporous silica with alkyltrimethylammonium (CTAB)

We assembled a highly durable conjugate with both a high-density accumulation and a regular array of lipase, by encapsulating it in mesoporous silica (FSM) with alkyltrimethylammonium (CTAB) chains on the surface. The activity for hydrolyzing esters of the lipase immobilized in mesoporous silica was linearly related to the concentration of lipase, whereas that of non-immobilized lipase showed saturation due to self-aggregation at a high concentration. The lipase conjugate also had increased resistance to heating when stayed in the silica coupling with CTAB. In addition, encapsulating the enzyme with FSM coupled CTAB caused the lipase to remain stable even in the presence of urea and trypsin, suggesting that the encapsulation prevented dissociation and denaturing. This conjugate had much higher activity and much higher stability for hydrolyzing esters when compared to the native lipase. These results show that FSM provides suitable support for the immobilization and dispersion of proteins in mesopores with disintegration of the aggregates.     

Proton radiation effects in quantum dot lasers

Proton beams with energies of 10 and 200 MeV were irradiated onto InAs quantum dot lasers with a wavelength of 1.3 μm. The increase in threshold current by proton irradiation was small compared with those of the previously reported other quantum dot lasers with larger active region and 1.3-μm InGaAsP quantum well lasers. These results were discussed by taking account of non-ionizing energy loss and effective volume of active region.     

Lebesgue piecewise affine approximation of nonlinear systems

This paper addresses a piecewise affine (PWA) approximation problem, i.e., a problem of finding a PWA system model which approximates a given nonlinear system. First, we propose a new class of PWA systems, called the Lebesgue PWA approximation systems, as a model to approximate nonlinear systems. Next, we derive an error bound of the PWA approximation model, and provide a technique for constructing the approximation model with specified accuracy. Finally, the proposed method is applied to a gene regulatory network with nonlinear dynamics, which shows that the method is a useful approximation tool.     

FLASH-INDUCED FAST CHANGE IN SURFACE POTENTIAL AND FLUIDITY OF PURPLE MEMBRANE STUDIED BY SPIN LABEL METHOD

Abstract— Flash-induced changes in surface potential and fluidity of purple membrane were studied by a spin label method. Changes in surface potential and fluidity were monitored by observing the distribution of charged and uncharged spin labels between the purple membrane and the aqueous phase.
On flash illumination, a transient hyperpolarization of the surface potential and a transient fluidization of the membrane hydrophobic region are induced. The former may probably reflect the proton movement near the purple membrane surface, while the latter may result from photo-induced conformational changes of bacteriorhodopsin.
The two events are different in time course. The relationships between the two events, and the formation and decay of the intermediates of bacteriorhodopsin in the photoreaction cycle are discussed.     

Numerical modelings of superconducting wires for AC loss calculations

Superconducting properties of superconducting wires as well as the influence of their composite structure and twisting should be taken into account for their numerical modeling for AC loss calculations. Furthermore, complicated electromagnetic conditions in electrical apparatuses under which superconducting wires are used influence their AC loss properties; superconducting wires carry their transport current and are exposed to the external magnetic field whose direction and magnitude vary spatially. A series of numerical models of superconducting tapes based on the finite element method has been developed. In each model, some of the above-mentioned factors that could influence the AC loss properties are taken into account. The models are formulated with the current vector potential and the scalar magnetic potential (T–Ω method). Superconducting property is given by the E–J characteristic represented by a power law. The current distributions in non-twisted and twisted superconducting tapes carrying their transport current and/or exposed to the external magnetic field are calculated with these models to estimate their AC loss. The current distribution in a short piece of superconducting tape exposed to AC magnetic field is also calculated.     

Finite element analysis of AC loss in non-twisted Bi-2223 tape carrying AC transport current and/or exposed to DC or AC external magnetic field

AC losses in Bi-2223 superconducting tapes carrying AC transport current and/or exposed to DC or AC magnetic field are calculated with a numerical model based on the finite element method. Superconducting property is given by the E–J characteristic represented by a power law using equivalent conductivity. First, transport loss and magnetization loss are calculated numerically and compared with measured values. The calculated losses almost agree with the measured losses. Frequency dependencies of calculated and measured transport losses are compared with each other. Next, the influence of DC external magnetic field on the transport loss is studied. DC external magnetic field reduces n that is an exponent in the power law connecting resistivity and current density. The numerically calculated transport loss increases with increasing DC magnetic field. Finally, the total loss of superconducting tape carrying AC transport current in AC magnetic field is calculated. In the perpendicular magnetic field, the calculated total loss is lager than the sum of the transport loss and the magnetization loss, while they almost agree with each other in the parallel magnetic field.     

Structure of the jet-cooled 1-naphthol dimer studied by IR dip spectroscopy: cooperation between the pi-pi interaction and the hydrogen bonding

The structure of a jet-cooled 1-naphthol (1-NpOH) dimer was investigated by using resonant-enhanced two-photon ionization (R2PI) and ion-detected infrared (IR) dip spectroscopy. A geometrical optimization and a frequency calculation in (1-NpOH)2 were also performed at the MP2/cc-pVDZ level. Stable isomers in the MP2/cc-pVDZ calculation were classified into a structure dominated only by the pi-pi interaction and structures formed by cooperation between the pi-pi interaction and hydrogen bonding. On the basis of a comparison between the observed and calculated IR spectra, the geometry of (1-NpOH)2 was concluded to be a pi-pi stacking structure supported by hydrogen bonding.     

Highly sensitive fluorescence microscope system for single biological cell using laser excitation and digital image processing and display

A novel type of laser-excited fluorescence microscope system is reported, which, for the first time, realizes excellent sensitivity and spatial resolution in biological and medical applications using an ultra-high sensitivity image camera and digital image processing technique for three-dimensional display of the detected fluorescence intensity across a single cell. Experimental studies are also presented on the fluorescence intensity distribution of Rhodamine 6G adsorbed in an OH gel as a simple cell model and also of a hematoporphyrin-derivative (HpD) taken up by a cultured esophagus cancer cell.