Observation of New Longitudinal and Transverse Josephson Plasma Modes in the Parallel Magnetic Fields: Underdoped YBCO

Josephson plasma reflectivity edge in YBa₂Cu₃O_6.6 (T _c=59 K) was measured in parallel magnetic fields HCuO₂ up to 7 T. Upon application of the field, the Josephson plasma edge splits to two reflectivity edges, forming a new peak at finite frequency. Optical conductivity obtained by Kramers–Kronig analysis indicates that a new transverse Josephson plasma mode appears under parallel fields. We propose that the new mode originates from the modulation of the insulating layers with and without Josephson vortices, as has been suggested by free-energy calculations of Josephson vortices with moderate densities.     

Analysis of glycopeptides using lectin affinity chromatography with MALDI-TOF mass spectrometry

Glycopeptides prepared from 1 nmol of a mixture of glycoproteins, transferrin, and ribonuclease B by lysylendopeptidase digestion were isolated by lectin and cellulose column chromatographies, and then they were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and MALDI-quadrupole ion trap (QIT)-TOF mass spectrometry which enables the performance of MS ( n ) analysis. The lectin affinity preparation of glycopeptides with Sambucus nigra agglutinin and concanavalin A provides the glycan structure outlines for the sialyl linkage and the core structure of N-glycans. Such structural estimation was confirmed by MALDI-TOF MS and MALDI-QIT-TOF MS/MS. Amino acid sequences and location of glycosylation sites were determined by MALDI-QIT-TOF MS/MS/MS. Taken together, the combination of lectin column chromatography, MALDI-TOF MS, and MALDI-QIT-TOF MS ( n ) provides an easy way for the structural estimation of glycans and the rapid analysis of glycoproteomics.     

Novel drug delivery system by surface modified magnetic nanoparticles

In the recent progress of gene and cell therapy, novel drug delivery system (DDS) has been required for efficient delivery of small molecules/drugs and also the safety for clinical usage. We have already developed the unique transfection technique by preparing magnetic vector and using permanent magnet. This technique can improve the transfection efficiency. In this study, we directly associated plasmid DNA with magnetic nanoparticles, which can potentially enhance their transfection efficiency by magnetic force. Magnetic nanoparticle, such as magnetite, its average size of 18.7 nm, can be navigated by magnetic force and is basically consisted with oxidized Fe that is commonly used as the supplement drug for anemia. The magnetite particles coated with protamine sulfate, which gives a cationic surface charge onto the magnetite particle, significantly enhanced the transfection efficiency in vitro cell culture system. The magnetite particles coated with protamine sulfate also easily associated with cell surface, leading to high magnetic seeding percentage. From these results, it was found that the size and surface chemistry of magnetic particles would be tailored to meet specific demands on physical and biological characteristics accordingly. Overall, magnetic nanoparticles with different surface modification enhance the association with plasmid DNA and cell surface as well as HVJ-E, which potentially help to improve the drug delivery system.     

Detection of microbubble position by a digital hologram

This paper reports on a new technique of measurements of microbubble position in three dimensions with high time-resolution. The technique is based on micro digital holographic particle tracking velocimetry. In this technique, an intensity profile is constructed from a holographic image of a microbubble where the profile results in showing two peaks. The distance between the two peaks appears to relate to the size of the microbubble's diameter. The three-dimensional position of the bubble can be detected by the center of the two peaks and the center point of the bubble image focused by a digital hologram. We also theoretically obtained the intensity profile of a microbubble by considering a refraction of light on a bubble surface to a ring-shaped aperture model. The theoretically obtained distance between the two peaks is found to be in good agreement with the values obtained experimentally.     

Two-dimensional thickness measurements based on internal reflection ellipsometry

An imaging ellipsometer technique on internal reflection geometry that can measure the thickness distribution of a thin film possessing an assumed refractive index is described. Because a prism is used for the internal reflection geometry, it was theoretically predicted that angular derivation from the normal incidence on the prism surface affects only the psi value by a factor of 0.97 at maximum. Measurements were carried out for an optical system of silica substrate-TiO2 layer-silica layer-protein film-air, with a thin-film array of dried protein as the sample film. Thickness of the protein films was two-dimensionally estimated only from the measured map of the delta value by use of the simulated relationship between the thickness and the delta value. The thickness map obtained was coincident on the whole with the results according to a mechanical scanning. The detection limit was approximately +/- 0.2 nm. These findings validate the optical effect of a high-index additional layer to improve the sensitivity and precision of thickness measurements of the sample film on transparent substrates.     

Fabrication of hierarchically porous spherical particles by assembling mesoporous silica nanoparticles via spray drying

A new type of hierarchically porous materials is fabricated by assembling mesoporous nanoparticles via spray drying. Well-dispersed mesostructured silica nanoparticles (MSN), whose particle size distribution was narrow in the range of 20 nm and 50 nm, were prepared by a thermal deposition method. By spray drying a MSN suspension, MSN were assembled into spherical secondary particles. After calcination, the spherical particles have two types of mesopores, mesopores of 3 nm in size inside of calcined MSN and larger inter-nanoparticle mesopores of about 15-20 nm. This hierarchical pore system should provide nanospaces for efficient mass transport of guest species with different sizes.     

基于物性推算法的膜分离材料设计

针对渗透汽化或蒸汽渗透法进行有机溶剂混合物分离,首次提出基于物性推算法的膜分离材料设计方法。基于溶解－扩散机理模型,使用统计热力学和状态方程式为基础的GCLF－EOS模型进行溶解度计算,自由体积模型推算扩散系数,同时考虑填充型复合膜的基膜影响,建立膜渗透通量计算模型。溶解性、扩散性的物性推算结果,较好地再现芳香族有机溶剂在高分子材料中的溶解和扩散行为,复合膜的渗透通量计算值与实验测定结果基本一致。由于计算模型中不包含任何从实验直接回归参数,本设计法具有可预测性和普遍适用性。     

Quantum Phase Transition in the Infinite Dimensional Hubbard Model

We investigated the ground state of the infinite dimensional Hubbard model for both attractive and repulsive interactions by applying Gutzwiller type variational wave functions. Our variational wave functions have lower energies than the simple BCS wave function for the attractive case, and lower energies than the Brinkman-Rice state for the repulsive case. We found that the system has several phases depending on the density of electrons and the interaction strength. Investigated phases include antiferromagnetic, Fermi liquid, superconducting, charge density wave, and supersolid phases. The last one is a coexistence phase of superconducting and charge density wave states.     

In-Situ Observation of SiC Bulk Single Crystal Growth by XRD System

In-situ analysis for SiC bulk single crystal growth was reported using vertical X-ray diffractometer system. A furnace for SiC sublimation growth combined with the XRD system which possessed three kinds of functions including topography, rocking curve measurement and crystal growth rate monitoring was developed. These functions could contribute as a powerful tool finding the optimum growth condition by dynamic observation in the crucible. In this study, the in-situ X-ray topographs succeeded to capture dynamic elongation of defects and dislocation generated in the SiC growing crystals. The in-situ rocking curve measurement reviled appearance of mosaic structure in the SiC crystal grown with high growth rate. The in-situ growth rate monitoring also succeeded very precisely using the direct X-ray beam absorption. On the base of findings and facts obtained by the in-situ observations, the importance for the SiC growth was discussed.     

A Comparison of Equating Methods and Linking Designs for Developing an Item Pool under Item Response Theory

The existence of an item pool can bring out the various merits of using item response theory (IRT). This study considered the case where the development of an item pool is in progress. We examined the robustness of four calibration methods in three linking designs using simulated data. The data were generated assuming that a small-sized item pool had already been developed and new items were to be added to that item pool. The results suggested that the item characteristic curve method generally performed well. The performance of the fixed common item parameter calibration method and the concurrent calibration method worsened in one of the linking designs where the number of common items was small. The results also suggested that performance was better when the sample size per form and the number of common items were large.