Production of FAME from acid oil model using immobilized <Emphasis Type="Italic">Candida antarctica</Emphasis> lipase

Acid oil is a by-product in the neutralization step of vegetable oil refining and is an alternative source of biodiesel fuel. A model substrate of acid oil, which is composed of TAG and FFA, was used in experiments on the conversion to FAME by immobilized Candida antarctica lipase. FFA in the mixture of TAG/FFA were efficiently esterified with methanol (MeOH), but the water generated by the esterification significantly inhibited methanolysis of TAG. We thus attempted to convert a mixture of TAG/FFA to FAME by a two-step process comprising methyl esterification of FFA and methanolysis of TAG by immobilized C. antarctica lipase. The first reaction was conducted at 30°C in a mixture of TAG/FFA (1∶1, wt/wt) and 10 wt% MeOH using 0.5 wt% immobilized lipase, resulting in efficient esterification of FFA. The reaction mixture after 24 h was composed of 49.1 wt% TAG, 1.3 wt% FFA, 49.1 wt% FAME, and negligible amounts of DAG and MAG (<0.5 wt%). The reaction mixture was then dehydrated and used as a substrate for the second reaction, which was conducted at 30°C in a solution of the dehydrated mixture and 5.5 wt% MeOH using 6 wt% immobilized lipase. The activity of the lipase increased gradually when the reaction was repeated by transferring the enzyme to a fresh substrate mixture. The activity reached a maximum after 6 cycles, and the content of FAME achieved was >98.5 wt% after a 24-h reaction. The immobilized lipase was very stable in the first-and second-step reactions and could be used for >100 d without significant loss of activity.     

Oxygen Uptake and Release Mechanism of Lithium Manganese Ferrite in the Low Temperature Range of 573–773 K

Oxygen uptake and release of (Li,Mn) ferrite [LMF; (Li_0.60Mn_1.20Fe_1.20)_1−δO₄; δ= 0.007 to 0.033] was investigated concerning the relations between redox reactions of ferrite and cation migration. Mössbauer spectroscopy and X-ray diffractometry showed that some of the Li⁺ and Fe³⁺ ions migrated from the A sites to the B sites of the spinel-type structure and Mn⁴⁺ ions migrated from the B sites to the A sites during oxygen uptake at 573 K. The cation-deficient LMF formed by the oxygen uptake released oxygen molecules in He gas only at 660 K. The cation migration during the oxygen release was in the opposite direction of the movement during oxygen uptake at 573 K.     

Transmission Electron Microscopy Characterization of Hot-Pressed ZrB2 with MoSi2 Additive

Microstructure of the hot-pressed ZrB₂ with MoSi₂ additive was investigated by transmission electron microscopy (TEM). The effect of MoSi₂ addition on the microstructure of the ceramic was assessed. For the pure ZrB₂, the microstructure consisted of the equiaxed ZrB₂ grains and a few elongated ZrB₂ grains. For the ZrB₂ with MoSi₂ additive, the microstructure consisted almost entirely of equiaxed ZrB₂ grains. A few dislocations were present in the ZrB₂ grains. In addition, high-resolution TEM observations showed that the intergranular amorphous phase was absent at two ZrB₂ grain boundaries in the ZrB₂ with MoSi₂ additive.     

Size Controlled Synthesis of Gold Nanoparticles by Porphyrin with Four Sulfur Atoms

Tetradentate thioacetyl porphyrin ligand (1) was synthesized to protect gold nanoparticles. 1-protected gold nanoparticles were characterized by UV-vis spectroscopy and XPS. Analysis by XPS showed that all of four thioacetyl groups of 1 were dissociated and bound to the surface of gold nanoparticles in thiolate form. The size of 1-protected gold nanoparticles (GN:1) was controlled by thioacetyl group/HAuCl₄ molar ratio and approached to 2 nm. Compared with a protecting ligand without porphyrin plane (2) or dodecanethiol, 1 can control the size of gold nanoparticles efficiently probably due to the tetradentate ligation effect.     

Development of anchored oligothiophenes on substrates for the application to the tunable transparent conductive films

Bis(triethoxysilyl)-substituted oligothiophene with a moderate π-conjugation length was newly synthesized and polymerized to give a polysilsesquioxane network having oligothiophene units dispersed homogeneously without phase separation. The polymer was fixed on glass or ITO substrate by spin-coating and annealing. The resulting film exhibited a high mechanical strength due to the covalent bonding with the substrates, and was electrochemically stable even after 300 redox cycles in electrolyte solution. Chemical oxidation of the polymer films yielded electrically conductive and almost transparent films.     

Preparation and Characterization of Highly Fluorescent, Glutathione-coated Near Infrared Quantum Dots for in Vivo Fluorescence Imaging

Fluorescent probes that emit in the near-infrared (NIR, 700–1,300 nm) region are suitable as optical contrast agents for in vivo fluorescence imaging because of low scattering and absorption of the NIR light in tissues. Recently, NIR quantum dots (QDs) have become a new class of fluorescent materials that can be used for in vivo imaging. Compared with traditional organic fluorescent dyes, QDs have several unique advantages such as size- and composition-tunable emission, high brightness, narrow emission bands, large Stokes shifts, and high resistance to photobleaching. In this paper, we report a facile method for the preparation of highly fluorescent, water-soluble glutathione (GSH)-coated NIR QDs for in vivo imaging. GSH-coated NIR QDs (GSH-QDs) were prepared by surface modification of hydrophobic CdSeTe/CdS (core/shell) QDs. The hydrophobic surface of the CdSeTe/CdS QDs was exchanged with GSH in tetrahydrofuran-water. The resulting GSH-QDs were monodisperse particles and stable in PBS (phosphate buffered saline, pH = 7.4). The GSH-QDs (800 nm emission) were highly fluorescent in aqueous solutions (quantum yield = 22% in PBS buffer), and their hydrodynamic diameter was less than 10 nm, which is comparable to the size of proteins. The cellular uptake and viability for the GSH-QDs were examined using HeLa and HEK 293 cells. When the cells were incubated with aqueous solutions of the GSH-QDs (10 nM), the QDs were taken into the cells and distributed in the perinuclear region of both cells. After 12 hrs incubation of 4 nM of GSH-QDs, the viabilities of HeLa and HEK 293 cells were ca. 80 and 50%, respectively. As a biomedical utility of the GSH-QDs, in vivo NIR-fluorescence imaging of a lymph node in a mouse is presented.     

Measurement of self-diffusion coefficients in Li ionic conductors by using the short-lived radiotracer of 8Li

For the effective use of short-lived radioactive beams, soon to be available at the Tokai Radioactive Ion Accelerator Complex, the authors have developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound βLiAl using an α-emitting radiotracer of ⁸Li (T_1/2=0.84 s). It was found that the time-dependent yields of the α particles from the diffusing ⁸Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in βLiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects (i.e., the existence of the atomic vacancies of Li and the defects in Ga sites that are replaced by Li).     

A corrosion prediction method for weathering steels

Japanese Specification for Highway Bridges [Japan Road Association: Specification for Highway Bridges—I & II, 2002.3] has been revised in 2002, which clearly states that degradation of bridge members, including those of weathering steels, to occur in prolonged period of time must be taken into account at the design stage to realize long term structural durability. To cope with the revised paradigm, SABI chemistry committee in Japan Society of Corrosion Engineers has proposed durable state concept [SABI Chemistry Committee of Japan Society of Corrosion Engineers, in: Proc. 132nd Symposium for Corrosion and Protection, 2001.6.25, p. 3], which is defined as a condition in which corrosion rate of steel is slow enough not to form thick rust [H. Kihira, K. Shiotani, H. Miyuki, T. Nakayama, M. Takemura, Y. Watanabe, Doboku Gakkai Ronbun-shu (J. Japan Soc. Civil Engineers) No. 745/I-65, 2003.10, pp.77-87]. Since corrosiveness of atmosphere differs by location, a corrosion prediction method for both conventional and advanced weathering steels [H. Kihira, A. Usami, K. Tanabe, M. Ito, G. Shigesato, Y. Tomita, T. Kusunoki, T. Tsuzuki, S. Ito, T. Murata, in: Electrochemical Society Proceedings, vol. 99-26, 2000, pp. 127-136] is needed to ensure structural durability for future. Thus, versatile computational scheme for it has been derived through mathematical modeling based upon the durable state concept.     

Recovery retardation in equal channel angular pressed Al–Zr alloy during friction stir welding

The effect of Zr on reduction of hardness and microstructure in an FS weld of equal channel angular-pressed Al alloy was investigated. Zr addition to Al suppressed dynamic recovery in the thermomechanically affected zone and enabled retention of the high hardness of the ECA-pressed material throughout the weld.