Biomedical subjects

J J Kai

Publications and source records attributed to J J Kai.

6 recordsLinked to original sources

PubMed2006

Quantitative analysis of defects and domain boundaries in mesoporous SBA-16 films.

Some quantitative structural analyses on defects and domain boundaries observed in SBA-16 films were performed using the lattice concept and geometric phase method. These analyses show that there exist low angle, high angle and translational anti-phase domain boundaries in SBA-16 films. While some of the domain boundaries bear analogue to those found in normal solid crystals, others are similar to that found in the liquid crystals. In particular near Sigma11 and Sigma13b high angle boundaries were observed. On the one hand the Sigma11 boundaries were found to exist with or without steps (ledge) associated with them depending on whether or not the boundary plane is parallel to the densely packed lattice plane. On the other hand segments of the boundary plane in the Sigma13b boundary were found being always associated with densely packed lattice plane, with the {011} type of lattice plane in one domain being parallel to the {112} type of plane in the other domain. The translational domain boundary was observed to have a translation vector having a projected component of (1/2) <110> on the (111) plane. The bending deformation similar to that found in the nematics liquid crystal was also observed and quantitatively analyzed using the geometric phase method, and rotational field associated with the deformation was identified.

Journal Article↗

PubMed2006

Orbital susceptibilities of PbSe quantum dots.

Different sizes of three-dimensional PbSe quantum dots have been synthesized for the study of orbital magnetic susceptibilities. Two types of orbital susceptibilities have been found, including the Curie susceptibility and finite-size corrections to the Landau susceptibility. The Curie term of a quantum dot manifests itself in the temperature dependence of magnetic susceptibility at low temperatures, while the field dependence of differential susceptibility at high temperatures shows finite-size corrections to the Landau susceptibility. Both of the two kinds of orbital susceptibility, estimated per quantum dot, show linear dependence on the size.

Journal Article↗

PubMed2005

A simple model for quantification of the radiobiological effectiveness of the 10B(n,alpha)7Li capture reaction in BNCT.

A simple model has been developed for predicting radiobiological effectiveness of the neutron capture reaction in boron neutron capture therapy. This model was derived from the relationship between the cell survival from the boron capture reaction, the intracellular boron concentration, and the thermal neutron fluence. We found that the cell-killing effect of the boron capture reaction was well described using a power function of the intracellular boron concentration. Hence the relationship between cell survival from the boron capture reaction, intracellular boron concentration, and the thermal neutron fluence could be determined using a simple mathematical equation. We consider that our current approach is more appropriate and realistic than the conventional theoretical mathematical model used to estimate the radiobiological effectiveness of the neutron capture reaction in boron neutron capture therapy.

Animals↗

PubMed2001

Four-dimensional dielectric property image obtained from electron spectroscopic imaging series.

We have demonstrated a new quantitative method to characterize two-dimensional distributions of energy-dependent dielectric function of materials from low loss electron spectroscopic image (ESI) series. Two problems associated with extracted image-spectrum from the low-loss image series, under-sampling and loss of energy resolution, were overcome by using fast Fourier transformation (FFT) interpolation and maximum entropy deconvolution method. In this study, Black Diamond/Si3N4/SiO2/Si-substrate dielectric layer designed for copper metallization was used as the sample. We show that the reconstructed (FFT interpolated and maximum entropy deconvoluted) image-spectrum obtained from ESI series images can be quantified with the same accuracy as conventional electron energy-loss spectroscopy spectra. Since the analysis of the dielectric function is sensitive to the local thickness of the specimen using Kramers-Kronig analysis, we also developed a new method to quantitatively determine the dielectric constant for low-k materials. We have determined the thickness of the Black Diamond using the extrapolated thickness method from the materials of known dielectric constants. Using Kramers-Kronig formula, the dielectric function map can be deduced from two-dimensional reconstructed single scattering spectra with providing the information of thickness. We proposed a four-dimensional data presentation for revealing the uniformity of the energy dependent property. The accuracy of our methods depends on the thickness determination and on the quality of the reconstructed spectra from the image series.

Journal Article↗

PubMed2001

Extension of HRTEM resolution by semi-blind deconvolution method and Gerchberg-Saxton algorithm: application to grain boundary and interface.

A generalized maximum entropy method coupled with Gerchberg-Saxton algorithm has been developed to extend the resolution from high-resolution TEM image(s) for weak objects. The Gerchberg-Saxton algorithm restores spatial resolution by operating real space and reciprocal space projections cyclically. In our methodology, a generalized maximum entropy method (Kullback-Leibler cross entropy) dealing with weak objects is used as a real space (P1) projection. After P1 projection, not only are the phases within the input spatial frequencies improved, but also the phases in the next higher frequencies are extrapolated. An example of semi-blind deconvolution (P1 project only) to improve the resolution in SiC twin boundary is shown. The nature of the bonding in this twin boundary is Si-C but it was rotated 180 degrees along the boundary normal. The optimum solution from P1 projection can be further improved by a P2 projection. The square roots of diffraction intensities from a diffraction pattern are then substituted to complete a cycle operation of the Gerchberg-Saxton algorithm. Application examples of Gerchberg-Saxton algorithm to solve the atomic structure of defects (2 x 1 interfacial reconstruction and dislocation) in NiSi2/Si interfaces will be shown also.

Journal Article↗

PubMedDate not supplied

Preparation and in vitro evaluation of B-lipiodol as a boron delivery agent for neutron capture therapy of hepatoma.

BACKGROUND: We prepared boron containing lipiodol (B-lipiodol), elucidated the retention of B-lipiodol in hepatoma cells and evaluated the in vitro cellular toxicity of B-lipiodol for neutron capture therapy. MATERIALS AND METHODS: Human hepatoma HepG2 cells were used to examine the uptake and retention of B-lipiodol. Light microscopes were used to examine the interaction and retention of B-lipiodol globules in individual hepatoma cells. Boron and lipiodol concentrations were determined by inductively coupled plasma-atomic emission spectroscopy and neutron activation analysis, respectively. RESULTS: The boron concentration in B-lipiodol drug could reach 2500 ppm. B-lipiodol could be stably retained in serum and culture medium. HepG2 cells appeared proficiently at internalization and persistent retention of B-lipiodol. The boron concentration reached 3.5 micrograms/10(6) cells without approaching saturation at 48 h treatment. CONCLUSION: Hepatoma cells could actively uptake B-lipiodol and a sufficient amount of boron was retained inside the HepG2 cells which could be used for neutron capture therapy.

Animals↗