Visible Light Irradiation of [60]Fullerene Causes Killing and Initiation of Transformation in Balb/3T3 Cells

Cell transformation in vitro is a model of carcinogenesis in vivo. Two-stage transformation assay increases the sensitivity of cells to chemicals and permits detection of carcinogens acting as initiating agents. [60]Fullerene (C₆₀) was cytotoxic in BALB/3T3 cells when it was irradiated by visible light, but not without light irradiation. Under conditions when C₆₀ was cytotoxic, it acted as an initiating agent for cell transformation, but it did not act as a complete transforming agent. the initiating activity of visible-light-irradiated C₆₀ was statistically significant in a modified two-stage transformation assay including a procedure for replating cells treated by C₆₀ and light, but it was equivocal in the standard two-stage transformation assay.     

Analysis of proton exchange membrane fuel cell catalyst layers for reduction of platinum loading at Nissan

The biggest issue that must be addressed in promoting widespread use of fuel cell vehicles (FCVs) is to reduce the cost of the fuel cell system. Especially, it is of vital importance to reduce platinum (Pt) loading of catalyst layers (CLs) in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC). In order to lower the Pt loading of the MEA, mass transport of reactants related to the performance in high current density should be enhanced significantly as well as kinetics of the catalyst, which can result in the better Pt utilization and effectiveness. In this study, we summarized our analytical approach and methods for reduction of Pt loading in CLs. Microstructure, mass transport properties of the reactants, and their relation in CLs were elucidated by applying experimental analyses and computational methods. A simple CL model for I–V performance prediction was then established, where experimentally elucidated parameters of the microstructure and the properties in CLs were taken into account. Finally, we revealed the impact of lowering the Pt loading on the transport properties, polarization, and the I–V performance.     

Supercritical CO2 extraction of pigment components with pharmaceutical importance from Chlorella vulgaris

BACKGROUND: Chlorella vulgaris is a green microalgae that contains various pigment components of carotenoids and chlorophylls. Supercritical CO₂ is widely used for extraction of pharmaceutical compounds because it is non‐oxic and easily separated from extracted material by simply depressurizing. In this work, pharmaceutical compounds from Chlorella vulgaris have been extracted using supercritical CO₂ with or without entrainer at various extraction conditions. RESULTS: Based on high performance liquid chromatography (HPLC) analysis, the extracts contained pigment components, such as lutein, β‐carotene, chlorophyll a and b. Higher extraction pressure and temperature promoted higher lutein extraction by supercritical CO₂. The optimum pressure and temperature for extraction were obtained as 50 MPa and 80 °C. Ethanol as an entrainer was more effective than acetone for the extraction of pigment components. Pigment components in the extract obtained by supercritical CO₂ with and without entrainer were compared with the extract obtained by a conventional extraction method. CONCLUSION: Supercritical CO₂ has been successfully applied for the extraction of pigment components from Chlorella vulgaris. Supercritical CO₂ enabled high selectivity for lutein extraction; however, the lutein yield was lower than that obtained by extraction using supercritical CO₂ with ethanol and soxhlet. Copyright © 2008 Society of Chemical Industry     

Comparison of the surface changes on cathode during long term storage testing of high energy density cylindrical lithium-ion cells

Nickel-based oxide cathode material taking out from lithium-ion cell after storage for 2 years at 45 °C is analyzed by electron energy-loss spectroscopy in a scanning transmission electron microscope (STEM-EELS) and the result of STEM-EELS is compared with cobalt-based oxide cathode material which is treated as same manor as nickel-based oxide cathode material. The Ni-L_2,3 energy-loss near-edge structure (ELNES) spectra of nickel-based oxide cathode material show peak positions similar to original material before storage. This result indicates that nickel-based oxide material has no significant change in the surface structure. On the other hand, a remarkable shift to low energy is observed in the Co-L_2,3 ELNES spectra of the cobalt-based oxide cathode material after storage. The cycle test at 60 °C under the conditions of aggressive driving cycle (US06) mode for the nickel-based oxide cathode/graphite cell is also carried out. It is clear that cycle performance of the nickel-based oxide cathode/graphite cell is dependent on the depth of discharge (DOD).     

Low-temperature thermionic emission from nitrogen-doped nanocrystalline diamond films on n-type Si grown by MPCVD

Temperature-dependent emission current–voltage measurements were carried out for nitrogen (N)-doped nanocrystalline diamond (NCD) films grown on n-type Si substrates by microwave plasma-assisted chemical vapor deposition (MP-CVD). Low threshold temperature (~ 260 °C) and low threshold electric field (~ 5 × 10^− 5 V/µm) were observed. Both the temperature dependence and the electric field dependence have shown that the obtained emission current was based on electron thermionic emission from N-doped NCD films. We have also studied the relation between nitrogen concentration and the saturation emission current. The saturation current obtained was as high as 1.4 mA at 5.6 × 10^− 3 V/µm at 670 °C when the nitrogen concentration was 2.4 × 10²⁰ cm^− 3. Low value of effective work function (1.99 eV) and relatively high value of Richardson constant (~ 70) were estimated by well fitting to Richardson–Dushman equation. The results of smaller φ and larger A′ suggest that N-doped NCD has great possibility of being a highly efficient thermionic emitter material.     

Confinement of surface state electrons on Cu and Au field emitters.

Field-emission images of clean Cu and Au emitters show a peculiar halo-like ring centered at the [1 1 1] pole. Typical diameter and width of the ring are approximately 10 nm and approximately 2 nm, respectively. Since we found no geometrical features around the [1 1 1] pole that gives rise to such a ring pattern, we interpreted the ring pattern as representing enhanced emission from an annular terrace that resonantly confines surface electrons. A simple analysis shows that the observed ring pattern appears at a terrace whose width nearly matches the confinement condition.     

Isolation, DNA sequence and regulation of a new cell division cycle gene from the yeast Saccharomyces cerevisiae

A new complementation group of temperature-sensitive mutants of the yeast Saccharomyces cerevisiae (ts26-1 and ts26-2) has been isolated and characterized. This mutation maps at 40.7 cM from arg8 and 48.9 cM from arg1 on the left arm of chromosome XV of yeast, providing that it is a newly identified gene. The dumbbell-shape terminal morphology of the mutant cells at the restrictive temperatures is a characteristic of mutants defective in DNA replication. To study the defect of macromolecule synthesis in the mutant cells, DNA, RNA, and protein synthesis were measured at both permissive and restrictive temperatures. The data suggest that the primary defect of this mutation is at the initiation step of DNA synthesis. The gene has been cloned from an S. cerevisiae genomic library by rescue of the conditional lethality of the mutants. It is present as a single copy in the haploid genome. DNA-RNA hybridization of the gene has identified 1 kb RNA, which is under cell-division-cycle control. DNA sequence analysis of the gene has identified an open reading frame capable of encoding a protein of molecular weight 25,055 (214 amino acids).     

Phase diagram calculations of ZrO2-based ceramics with an emphasis on the reduction/oxidation equilibria of cerium ions in the ZrO2-YO1.5-CeO2-CeO1.5 system

Phase diagram calculations that were made previously for the ZrO₂-MO _m/2 (m = 2, 3, 4) systems and for the ZrO₂-YO_1.5-MO _m/2 (M = transition metals) systems have been extended to the ZrO₂-YO_1.5-CeO₂(-CeO_1.5) system to make an attempt to explain (1) thermogravimetric (TG) results as a function of oxygen potential, (2) electronic conductivity as a function of oxygen potential, and (3) a miscibility gap observed in air. The interaction parameters for the CeO₂-CeO_1.5-YO_1.5 system were obtained from the reported oxygen nonstoichiometry in CeO_2−x and rate earth doped ceria, (Ce,RE)O_2−δ . The interaction parameters for the ZrO₂-CeO₂ subsystem were obtained so as to reproduce the observed miscibility gap at 1273 K. Those thermodynamic properties can reproduce consistently the experimental behaviors of the electronic conductivity and the TG results in the (Zr_1−x Ce _x )_0.8Y_0.2O_1.9 solid solutions; these indicate the enhancement of reduction of CeO₂.