Electrochemically modulated liquid chromatography coupled on-line with electrospray mass spectrometry

Electrochemically modulated liquid chromatography (EMLC) has been coupled to an electrospray mass spectrometer. This combination takes advantage of the ability of EMLC to manipulate retention and enhance separation efficiency solely through changes in the potential applied to a conductive stationary phase, thereby minimizing complications because of possible changes in analyte ionization efficiencies when gradient elution techniques are used. Three examples are presented that demonstrate the attributes of this EMLC/electrospray mass spectrometry (ES-MS) coupling. The first two examples involve the separation of mixtures of corticosteroids or of benzodiazepines, showing the general utility of the union for eluent identification and low-level detection. The ability to identify products from on-column redox transformations is also demonstrated using the benzodiazepine mixture. The third example investigates the electrooxidation of aniline by utilizing an EMLC column as an on-line electrochemical reactor and product separator and ES-MS for detection and product identification.     

In situ Observation of the Growth of Ribbon-like Thin Films of Bi-2212 on an Ag Substrate

We have developed a simple technique to grow ribbon-like single crystalline films of Bi- 2212 on Ag substrates. The process is performed under ambient pressure only by heating a Bi-2212 pellet on the edge of the substrates. ¹ The ribbon-like films thus grown showed sharp superconducting transitions with an onset temperature of 80K. The formation of the ribbons was studied by observing their growth with a high- temperature microscope. In situ observation with the microscope revealed that most of the ribbon crystals grew during the 10 minutes of the plateau at 905° C. In particular, the early part of the plateau was the dominant stage of growth.     

Chlorination of UO2 and (U,Zr)O2 solid solution using MoCl5

Conversion of UO₂ and (U_0.5Zr_0.5)O₂ solid solution into chlorides by MoCl₅ was performed in order to confirm the applicability of the chlorination by MoCl₅ to a pretreatment of fuel debris by pyrochemical methods. Chlorination of (U_0.5Zr_0.5)O₂ powders and dense pieces was successfully achieved at 573 and 773 K, respectively, based on the following chemical reaction: 2(U_0.5Zr_0.5)O₂ + 4MoCl₅ = UCl₄ + ZrCl₄ + 4MoOCl₃. Rough separation of MoCl₅, ZrCl₄ and MoOCl₃ from UCl₄ was achieved by volatilization under temperature gradient. From these results, fundamental feasibility of the chlorination method using MoCl₅ as a pretreatment of fuel debris was shown.     

Highly efficient reverse transfection with siRNA in multiple wells of microtiter plates

We have developed an efficient and inexpensive method of reverse transfection from the solid phase to suppress genes with siRNA. The method enabled the realization of (i) a high efficiency of transfection; (ii) transfection of various types of cell; (iii) a high efficiency of gene knockdown by siRNA; (iv) a low toxicity to cells; and (v) a long-term stabilization (more than 210 d) of attached transfection mixture including siRNA in multiple wells. Although array-based reverse transfection has advantages in terms of miniaturization, the method has the advantage of enabling the inclusion of various soluble factors, such as humoral factors, drugs and ligands that affect gene expression, because the liquid phase is partitioned within the individual wells of each microtiter plate. Our method of reverse transfection with siRNA in multiple wells is a powerful and high-throughput tool for the analysis of signaling pathways.     

Study on rapid analysis method of pesticide contamination in processed foods by GC-MS and GC-FPD

A simple and rapid method using GC-MS and GC-FPD for the determination of pesticide contamination in processed food has been developed. Pesticides were extracted from a sample with ethyl acetate in the presence of anhydrous sodium sulfate, then cleaned up with a combination of mini-columns, such as macroporous diatomaceous earth, C18, GCB (graphite carbon black) and PSA. Recovery tests of 57 pesticides (known to be toxic or harmful) from ten kinds of processed foods (butter, cheese, corned beef, dried shrimp, frozen Chinese dumplings, grilled eels, instant noodles, kimchi, retort-packed curry and wine) were performed, and the recovery rates were mostly between 70% and 120%. This method can be used to judge whether or not processed foods are contaminated with pesticides at potentially harmful levels.     

Characterization of terraces and steps on Cl-terminated Ge(111) surfaces after HCl treatment in N2 ambient

Germanium (Ge) is a promising substrate for semiconductor devices in the near future. However, wet-chemical preparations that enable the control of the structure of the Ge surface have not yet been developed. In this study, the surface structure of Ge(111) after HCl treatment is characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning tunneling microscopy (STM). XPS spectra revealed that purging with inert gas, such as nitrogen, is necessary to obtain a Ge surface free of oxide, probably because dissolved oxygen from air rapidly oxidizes the surface. Cl-terminated Ge surfaces are microscopically rough, but are composed of terraces and steps, as revealed by magnified STM images. Step edges run not along specific directions reflecting the crystallographic nature of the (111) surface but randomly. Many atomic-scale protrusions with the height of around 0.1 nm are dispersed on terraces. They are likely to be impurities such as carbon contaminants and water on Cl-terminated terraces attracted by Cl atoms with high electronegativity.     

Buckling of thin and moderately thick anisotropic cylinders under combined torsion and axial compression

The effects of anisotropy, transverse shear stiffness, length, and their interactions on buckling under pure torsion and under combined axial compression and torsion were investigated using a previously derived analytical model based on deep shell theory including anisotropy and transverse shear stiffness. The model was verified only for buckling under pure axial compression, hence results for buckling under torsion have now been compared with the results of previous analyses, and the comparison showed that the model has good accuracy for buckling under torsion. Investigation showed that the buckling loads of a cylindrical shell are affected not only by anisotropy and transverse shear stiffness but also by shell length. This means that the shallow shell theory (Donnell-type theory) is not appropriate and deep shell theory including anisotropy and transverse shear stiffness must be used.     

Survey of pesticide residues in baby foods (1996.4-1998.6)

Between April 1996 to June 1998, 133 samples of 9 food commodities were analyzed for pesticide residues. In 8 samples of 5 commodities, 5 kinds of pesticides residues were detected. The baby foods in which the pesticides were detected were produced from vegetables and fruits. In our investigations, pesticide residues have been frequently detected in the raw materials. For the baby foods containing pesticides, intake amounts of the pesticides calculated from the daily feeding volume and the ADI were compared. Residual pesticide levels in baby food commodities are low, and it was concluded that they are not likely to present any problem in normal usage.     

The structures of integration sites in transgenic rice

Extensive genomic sequencing and sequence motif analysis have been conducted over the integration sites of two transgenic rice plants, #478 and #559, carrying the luciferase gene and/or hygromycin phosphotransferase gene. The transgenes reside in a region with inverted structure and a large duplication of rice genome over 2 kb. Integration was found at the AT-rich region and/or at the repetitive sequence region, including a SAR-like structure, retrotransposon and telomere repeats. The presence of a patch of sequence homology between plasmid and target DNA, and a small region of duplication involving the target DNA around the recombination site, implicated illegitimate recombination in the process of gene integration. Massive rearrangement of genomic DNA including deletion or translocation was also observed at the integration site and the flanking region of the transgene. The recognition sites of DNA topoisomerases I or II were observed in the rearranged sequences. Since only three junctions of transgenic rice were implicated in the illegitimate recombination and extensive rearrangement of the rice genome, rice protoplasts may be active in this process.     

Roles of Macrophages in Advanced Liver Fibrosis,Identified Using a Newly Established Mouse Model of Diet-Induced Non-Alcoholic Steatohepatitis

Macrophages play critical roles in the pathogenesis of non-alcoholic steatohepatitis (NASH). However, it is unclear which macrophage subsets are critically involved in the development of inflammation and fibrosis in NASH. In TSNO mice fed a high-fat/cholesterol/cholate-based diet, which exhibit advanced liver fibrosis that mimics human NASH, we found that Kupffer cells (KCs) were less abundant and recruited macrophages were more abundant, forming hepatic crown-like structures (hCLS) in the liver. The recruited macrophages comprised two subsets: CD11c⁺/Ly6C⁻ and CD11c⁻/Ly6C⁺ cells. CD11c⁺ cells were present in a mesh-like pattern around the lipid droplets, constituting the hCLS. In addition, CD11c⁺ cells colocalized with collagen fibers, suggesting that this subset of recruited macrophages might promote advanced liver fibrosis. In contrast, Ly6C⁺ cells were present in doughnut-like inflammatory lesions, with a lipid droplet in the center. Finally, RNA sequence analysis indicates that CD11c⁺/Ly6C⁻ cells promote liver fibrosis and hepatic stellate cell (HSC) activation, whereas CD11c⁻/Ly6C⁺ cells are a macrophage subset that play an anti-inflammatory role and promote tissue repair in NASH. Taken together, our data revealed changes in liver macrophage subsets during the development of NASH and shed light on the roles of the recruited macrophages in the pathogenesis of advanced fibrosis in NASH.