Determination of concentration and binding affinity of antibody fragments by use of surface plasmon resonance

An assay method using a surface plasmon resonance (SPR) biosensor has been developed that allows quantitative measurement of the specific antibody concentration in crude materials. By injecting non-labeled antibody samples onto a biosensor surface on which antigen was immobilized at high densities, the concentration of active antibodies can be accurately measured. To clarify applicability of this method to pharmacokinetic studies, the concentration of active antibodies in mouse plasma was measured for 4 h after injection of antibodies in mice. Although this period of measurement might be insufficient for determining the pharmacokinetics of blood pool clearance, this method has some advantages over conventional methods in measurement of single-chain antibody fragment (scFv) concentrations. Using the SPR biosensor, scFv and antibodies without epitope tag peptides were easily detected in real time, requiring as little as 20 mul of blood sample. Moreover, from the apparent dissociation rate in the dissociation phase of the sensorgrams, we could identify whether the antibody fragments existed as bivalent or monovalent in animal blood. We also evaluated the antigen binding activity of the scFvs against human CD47 and found scFvs had slightly weak affinity to their antigen (K(D), about 10 nM) compared with F(ab')2 and Fab' fragments (K(D), about 3-4 nM). This assay method promises to be a convenient tool for quality control, screening, and simple pharmacokinetic analysis of antibody fragments and other recombinant proteins not having epitope tags.     

High-speed thermal stress cleaving by moving heat with mist cooling

Two types of different trials were examined experimentally to increase a cleaving velocity in thermal stress cleaving. One is a partial cooling by water mist spray on the propagating crack surface and the other is a preformation of a slightly high-temperature zone by preheating. It is known that when other cleaving conditions are fixed, the cleaving velocity decreases with increase in width of the target object. This characteristic of thermal stress cleaving is often considered as a shortcoming for practical applications. Therefore, improvement of the cleaving efficiency by increasing a cleaving velocity is one of the important issue in the thermal stress cleaving. It was found experimentally that the maximum attainable cleaving velocity was increased from 38 to 55 mm/s when mist cooling was employed in addition to the usual laser beam heating of 10 W magnitude for 31 mm width specimen. On the other hand, the most effective preheat technique realized more than 400% increase in the cleaving velocity for 62 mm width specimen. The background why these two types of different approaches both contribute to improve the cleaving velocity was discussed based on the linear elastic fracture mechanics.     

Rheological measurements of cure rate of UV inks

The dynamic viscosity of UV inks during curing was measured at various film thickness using an oscillating plate rheometer. Logarithmic plots of the dynamic viscosity versus exposure energy are closely related by two-straight lines. A useful concept in discussing the curability is the minimum exposure energy difined as the exposure energy at the intersection of two lines. On exposure to a monochromatic light of 365 nm, the minimum exposure energy increases exponentially with film thickness; this resulting from an exponential decay of the light intensity with depth in the film. Magenta ink shows the fatest cure rate at a given thickness, followed by yellow, cyan, and black inks in that order. The difference in cure rate is attributed to different absorbances of pigments. The UV curability on direct exposure to UV lamp is predicted from the spectral sensitivity of the photoinitiator and the viscosity data obtained during curing under 365 nm light. The model calculation shows good agreement with the experimental results.     

Rheological studies of ultraviolet curing with an oscillating plate rheometer

The dynamic viscoelastic behavior during UV curing was studied for thin liquid films of epoxy acrylate prepolymer by the use of an oscillating plate rheometer. The dynamic viscosity rapidly increases after a certain period of irradiation, so that the UV curing process has the minimum exposure energy required to start polymerization. The minimum exposure energy markedly increases with increasing sample thickness; this results from the inconsistency of degree of curing in the direction perpendicular to the shearing surface. Since free radicals which initiate polymerization are formed by photochemical decomposition of initiator, the ability to cure a film depends on the light intensity at a given depth of the film. the attenuation of light in the film is primarily responsible for this inconsistency. When UV light is applied through a UV filter, the curing behavior is analyzed by a single exponential decay of light with depth because the curing is induced by absorption of a monochromatic light of 365 nm. On the other hand, when UV light from a UV lamp whose output spectrum is a continuum is directly applied, the curing behavior is explained by a combination of energy absorption at different wavelengths. In both cases, the theoretical curves of dynamic viscosity predicted in relation to spectral sensitivity show a good agreement with the experimental results.     

Viscoelastic behavior of suspensions of particles in polymer solutions

Suspensions, consisting of glass beads about 1 μm in diameter and a 20 wt percent polystyrene solution in diethyl phthalate, were prepared at concentrations up to 13 vol percent. The viscoelastic properties were measured by means of a conventional dynamic method and by the raised cosine pulse method. The relaxation intensity and relaxation times of suspensions increased with increasing particle concentration. However, at concentrations > 13 vol percent, the stress against the raised cosine pulse strain did not approach zero. It was found that concentrated suspensions were complicated by a combination of viscous, elastic, and plastic effects. The experimental results have been qualitatively explained on the base of the network structure of particles.     

Time-dependent flow of cement pastes

The time-dependent behavior of viscosity of clinker pastes was studied with a coaxial cylinder type viscometer. In order to characterize the flow behavior of cement pastes, the flow curve obtained by the minimum values of shear stresses at different shear rates was proposed. Two types of time dependence were found; the increase in viscosity caused by shearing and the increase in minimum viscosity caused by hydration. The effect of sodium lignosulfonate on the flow behavior was also considered.     

Scenario to Data Mapping for Chance Discovery Process

The mapping method between the graph generated by KeyGraph and the scenario drawn up by a user is proposed for supporting chance discovery process. Although KeyGraph is widely known as one of the effective tools that support the process of chance discovery, further improvement seems to be required, concerning the ambiguity involved in user’s interpretation of the graph. The mapping found by the proposed algorithm is used for extracting the data referred to in the scenario and for annotating those in the original data file. The annotated data files are expected to be used for further data analysis as well as for supporting group discussion. Experiments are performed in terms of scenario similarity calculation based on the annotated data set. The results are compared with typical document retrieval method based on Vector space model (VSM), which shows the availability of annotated data in chance discovery process.