High-rate properties of LiFePO4/carbon composites as cathode materials for lithium-ion batteries

Electrochemical properties of LiFePO₄/carbon composites were investigated to achieve a high-rate lithium electrode performance. LiFePO₄/carbon composites were synthesized by a hydrothermal reaction of a solution of FeSO₄·7H₂O, H₃PO₄, and LiOH·H₂O mixed with carbon powders under nitrogen atmosphere followed by annealing under 1% H₂–99% Ar atmosphere. Particle size of the obtained LiFePO₄/carbon composites observed by scanning electron microscopy was less than 100 nm. At a high current density of 1000 mA g⁻¹, the LiFePO₄/carbon composites showed a high discharge capacity of 113 mA h g⁻¹, and a flat discharge potential plateau was observed around 3.4 V. The discharge capacity at the high current density, 85% of that at a low current density of 30 mA g⁻¹, is a quite high value for LiFePO₄ cathodes. Homogeneous microstructure consisting of small particles contributed to the high-rate properties of the LiFePO₄/carbon composites.     

Electrochemically Assisted Photocatalysis of Hybrid WO3/TiO2 Films: Effect of the WO3 Structures on Charge Separation Behavior

In this study, the photocatalysis of hybrid WO₃/TiO₂ films with different loadings of WO₃ were investigated with and without potential bias. It was clearly indicated that hybrid WO₃/TiO₂ films show less photo-reactivity under only UV-irradiation, while more effective photocatalysis under potential bias than either TiO₂ or WO₃ by themselves, their photocatalytic performance depending on the loadings of WO₃. In particular, a hybrid WO₃/TiO₂ film involving an amorphous-like WO₃ phase plays a significant role in an enhancement of the electrochemically assisted photocatalysis.     

Site-specific protein modification on living cells catalyzed by Sortase

The use of enzymes is a promising approach for site-specific protein modification on living cells owing to their substrate specificity. Herein we describe a general strategy for the site-specific modification of cell surface proteins with synthetic molecules by using Sortase, a transpeptidase from Staphylococcus aureus. The short peptide tag LPETGG is genetically introduced to the C terminus of the target protein, expressed on the cell surface. Subsequent addition of Sortase and an N-terminal triglycine-containing probe results in the site-specific labeling of the tagged protein. We were successful in the C-terminal-specific labeling of osteoclast differentiation factor (ODF) with a biotin- or fluorophore-containing short peptide on the living cell surface. The labeling reaction occurred efficiently in serum-containing medium, as well as serum-free medium or PBS. The labeled products were detected after incubation for 5 min. In addition, site-specific protein-protein conjugation was successfully demonstrated on a living cell surface by the Sortase-catalyzed reaction. This strategy provides a powerful tool for cell biology and cell surface engineering.     

Synthesis and application of fluorescein- and biotin-labeled molecular probes for the chemokine receptor CXCR4

The design, synthesis, and bioevaluation of fluorescence- and biotin-labeled CXCR4 antagonists are described. The modification of D-Lys8 at an epsilon-amino group in the peptide antagonist Ac-TZ14011 derived from polyphemusin II had no significant influence on the potent binding of the peptide to the CXCR4 receptor. The application of the labeled peptides in flow cytometry and confocal microscopy studies demonstrated the selectivity of their binding to the CXCR4 receptor, but not to CXCR7, which was recently reported to be another receptor for stromal cell-derived factor 1 (SDF-1)/CXCL12.     

Viscoelastic properties of concentrated aqueous ethanol suspensions of α-zein

Viscoelastic properties of α-zein dispersed in aqueous ethanol were studied using oscillatory strain rheometry. In 55-80% v/v aqueous ethanol, zein was only partially soluble, forming a gel at a sufficiently high zein concentration. The strain dependence of the storage modulus and the loss modulus of gelled systems exhibited features characteristic to closely-packed swollen particles. Close-packing was found to occur at a lower zein concentration with increasing ethanol concentration as the threshold for gelation decreased from a zein concentration of ca. 29 to 20% w/v with increasing ethanol concentration from 55 to 80% v/v. A contrasting trend in the effect of the solvent quality was revealed at a constant zein concentration of 30% w/v, at which the storage modulus decreased from ca. 12,000-700 Pa with increasing ethanol concentration from 55 to 80% v/v. The two major factors determining viscoelastic properties of the partially solvated zein systems were identified to be: (1) the degree of dissolution of zein into the continuous phase that was negatively correlated with the volume fraction of the dispersed phase and positively correlated with the osmotic pressure of the continuous phase; and (2) the degree of swelling of partially solvated zein particles that was positively and negatively correlated with the volume fraction and the storage modulus of the dispersed phase, respectively.     

In vivo visual reporter system for detection of estrogen-like substances by transgenic medaka

Detection of endocrine disrupting chemicals, in particular, environmental estrogens with living organisms, has many advantages if compared to chemical analysis. The screening of novel pollutants with meaningful endpoints, the integration of uptake, bioconcentration, and excretion as well as the evaluation of endocrine disrupting effects with respect to toxicity require in vivo biotests for estrogen-like substances (ELSs). Critical disadvantages of whole organism biotests are their low sensitivity and the need for laborious and time-consuming work. To overcome these problems, we have developed a transgenic medaka strain harboring the green fluorescence protein (GFP) gene driven by choriogenin H gene regulatory elements. Choriogenin H is an egg envelope protein induced by estrogens in the liver. With yolk sac larvae of this strain, GFP induction in liver was observed 24 h after onset of aqueous exposure to 0.63 nM 17beta-estradiol (E2), 0.34 nM ethynylestradiol, or 14.8 nM estrone. Furthermore, concentrated sewage treatment effluent induced GFP expression. Comparison of E2 equivalents estimated by GFP-induction in transgenic medaka, a YES assay, and GC/MS showed detection limits in the same order of magnitude. These results indicated that the sensitivity of the transgenic medaka strain was sufficient for application as an alternative model in monitoring environmental water samples for ELSs.     

Less Carcinogenic Chlorinated Estrogens Applicable to Hormone Replacement Therapy

Human estrogens prescribed for hormone replacement therapy (HRT) are known to be potent carcinogens. To find safer estrogens, several chlorinated estrogens were synthesized and their carcinogenic potential were determined. A pellet containing either 2-chloro-17β-estradiol (2-ClE₂) or 4-chloro-17β-estradiol (4-ClE₂) was implanted subcutaneously for 52 weeks into August Copenhagen Irish (ACI) rats, a preferred animal model for human breast cancer. 17β-Estradiol (E₂) frequently induced mammary tumors while both 2-ClE₂ and 4-ClE₂ did not. Their 17α-ethinyl forms, thought to be orally active estrogens, were also synthesized. Neither 2-chloro-17α-ethinylestradiol (2-ClEE₂) nor 4-chloro-17α-ethinylestradiol (4-ClEE₂) induced tumors. The less carcinogenic effects were supported by histological examination of mammary glands of ACI rats treated with the chlorinated estrogens. A chlorine atom positioned at the 2- or 4-position of E₂ may prevent the metabolic activation, resulting in reducing the carcinogenicity. 2-ClE₂ and 4-ClE₂ administered subcutaneously and 2-ClEE₂ and 4-ClEE₂ given orally to ovariectomized rats all showed uterotrophic potency, albeit slightly weaker than that of E₂. Our results indicate that less carcinogenic chlorinated estrogens retaining estrogenic potential could be safer alternatives to the carcinogenic estrogens now in use for HRT.     

Influence of xyloglucan on gelatinization and retrogradation of tapioca starch

Dynamic and steady shear rheometry and differential scanning calorimetry (DSC) were used to investigate effects of xyloglucan (XG) on gelatinization and retrogradation of tapioca starch (TS). The viscosity of TS/XG pastes immediately after gelatinization increased with increasing XG content at the total polysaccharide concentration of 3.5%. Gelatinized TS alone showed pseudoplastic flow at low shear rates and dilatant behavior at higher shear rates (about >1 s⁻¹), while mixtures with XG did not show dilatancy. Mechanical spectra of TS pastes containing XG were more liquid-like than those of TS pastes without XG. XG provides shear stability to the TS during storage. Increases in dynamic moduli during storage at 5 °C were suppressed in the presence of XG. In contrast, the retrogradation ratio determined based on DSC increased more rapidly in the presence of XG. These results suggest that XG forms a continuous liquid phase in a mixture to impart better mechanical stability during storage but to accelerate re-ordering of starch polysaccharides by effectively reducing the amount of water available for starch.