Effects of Amino Acids and Peptide on Lipid Oxidation in Emulsion Systems

We investigated the effects of amino acids and peptide on lipid oxidation in emulsion systems. For comparative purposes, we also tested the antioxidant activity of ferulic acid, a typical phenolic antioxidant. Histidine and cysteine retarded lipid oxidation (the amount of thiobarbituric acid [TBA]-reactive substances reached approximately 13 and 18 μM after 7 days, respectively), whereas arginine, methionine, and tryptophan did not inhibit the progression of oxidation. Soy peptide also inhibited lipid oxidation. Ferulic acid was found to be the most effective suppressor of lipid oxidation (TBA-reactive substances were suppressed to <3 μM over 7 days). The antioxidant activities of soy peptide and ferulic acid were related to the purity of the emulsifier used. The radical scavenging activities of soy peptide and ferulic acid were closely related to their inhibitory effects on lipid oxidation. However, this was not the case for amino acids. Decreases in the turbidity of emulsions were closely related to increases in TBA values.     

Aluminum-doped ceria-zirconia solid solutions with enhanced thermal stability and high oxygen storage capacity

A facile solvothermal method to synthesize aluminum-doped ceria-zirconia (Ce_0.5Zr_0.5-xAl_xO_2-x/2, x = 0.1 to 0.4) solid solutions was carried out using Ce(NH₄)₂(NO₃)₆, Zr(NO₃)₃·2H₂O Al(NO₃)₃·9H₂O, and NH₄OH as the starting materials at 200°C for 24 h. The obtained solid solutions from the solvothermal reaction were calcined at 1,000°C for 20 h in air atmosphere to evaluate the thermal stability. The synthesized Ce_0.5Zr_0.3Al_0.2O_1.9 particle was characterized for the oxygen storage capacity (OSC) in automotive catalysis. For the characterization, X-ray diffraction, transmission electron microscopy, and the Brunauer-Emmet-Teller (BET) technique were employed. The OSC values of all samples were measured at 600°C using thermogravimetric-differential thermal analysis. Ce_0.5Zr_0.3Al_0.2O_1.9 solid solutions calcined at 1,000°C for 20 h with a BET surface area of 18 m² g⁻¹ exhibited a considerably high OSC of 427 μmol-O g⁻¹ and good OSC performance stability. The same synthesis route was employed for the preparation of the CeO₂ and Ce_0.5Zr_0.5O₂. The incorporation of aluminum ion in the lattice of ceria-based catalyst greatly enhanced the thermal stability and OSC.     

Hydrolytic degradation of poly(L-lactic acid): Combined effects of UV treatment and crystallization

Amorphous and crystallized poly(L -lactic acid) (PLLA) films were prepared and the hydrolytic degradation of the ultraviolet (UV)-treated and UV-nontreated films was investigated. This study reveals that the combination of UV and thermal treatments can produce the PLLA materials having different hydrolytic degradation profiles and that the UV-irradiation in the environment will affect the design of recycling process for PLLA articles. In an early stage, the degrees of hydrolytic degradation monitored by weight loss (W_loss), number-average molecular weight (M _n), and melting temperature (T _m) were higher for the UV-treated films than for the UV-nontreated films. In a late stage, the trend traced by W_loss was reversed, and the difference in the degrees of hydrolytic degradation between the UV-treated and UV-nontreated films monitored by M _n and T _m became smaller, with the exception of the degrees of hydrolytic degradation of the amorphous films traced by T _m. Also, in the early stage, the degrees of hydrolytic degradation monitored by W_loss and M _n were higher for the crystallized films than for the amorphous films. In the late stage, this trend was reversed, with the exception of the degrees of hydrolytic degradation of the UV-treated films monitored by M _n. The main factors that determined the W_loss and T _m were the molecular weight and initial crystallinty but not the molecular structures such as terminal CC double bonds and crosslinks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Spray-dry synthesis of β-Cu1.8Zn0.2V2O7 ceramic fine particles showing giant negative thermal expansion

We used spray-dry method to synthesize fine powder of β-Cu_1.8Zn_0.2V₂O₇ showing large negative thermal expansion (NTE) linearly to temperature over a wide temperature range. The NTE of β-Cu_1.8Zn_0.2V₂O₇ is produced by microstructures consisting of voids and anisotropic thermal deformation of crystal grains in ceramics. By reducing the size of the microstructures that produce NTE, large NTE equivalent to that of bulk was realized, even for ceramic particles of about 2 μm size. Comparison with particles produced using a conventional method demonstrates that the particle size distribution is narrow and that the particles are nearly spherical. This achievement is expected to pave the way to use of NTE materials in micrometer-scale control of thermal expansion.     

Surfactant-Assisted Purification of Hydrophobic DNA Nanostructures

Purification of functional DNA nanostructures is an essential step in achieving intended functions because misfolded structures and the remaining free DNA strands in a solution can interact and affect their behavior. However, due to hydrophobicity-mediated aggregation, it is difficult to purify DNA nanostructures modified with hydrophobic molecules by conventional methods. Herein, we report the purification of cholesterol-modified DNA nanostructures by using a novel surfactant-assisted gel extraction. The addition of sodium cholate (SC) to the sample solution before structure folding prevented aggregation; this was confirmed by gel electrophoresis. We also found that adding sodium dodecyl sulfate (SDS) to the sample inhibited structural folding. The cholesterol-modified DNA nanostructures prepared with SC were successfully purified by gel extraction, and their ability to bind to the lipid membrane surfaces was maintained. This method will facilitate the purification of DNA nanostructures modified with hydrophobic molecules and expand their applicability in the construction of artificial cell-like systems.     

Catalyst Design of Pt-Modified Ni/Al2O3 Catalyst with Flat Temperature Profile in Methane Reforming with CO2 and O2

Pt(0.3)/Ni(10)/Al₂O₃, prepared by a sequential impregnation method, exhibited a more excellent performance in methane reforming with CO₂ and O₂ in terms of the catalytic activity and the temperature profile of the catalyst bed than Pt(0.3) + Ni(10)/Al₂O₃ prepared by a coimpregnation method, Ni(10)/Al₂O₃, Pt(0.3)/Al₂O₃, and Pt(10)/Al₂O₃. It is thought that this is because the surface Pt atoms on Ni catalyst can contribute to the enhancement of the catalyst reducibility.     

XAFS Analysis for Niobium Carbide Particle Growth on Silica Support During Preparation Process

SiO₂-supported NbC catalysts were prepared by using temperature-programmed reactions (TPR). XAFS analysis confirmed that Nb₂O₅ was reduced to NbO₂ in the first TPR stage and converted into NbC in the second TPR stage. Nb particles grew only in the second TPR stage. Formation of highly dispersed NbC particles on SiO₂ surfaces was achieved.     

Binary phase behavior of 1,3-distearoyl-2-oleoyl-sn-glycerol (SOS) and 1,3-distearoyl-2-linoleoyl-sn-glycerol (SLS)

The binary phase behavior of SOS (1,3-distearoyl-2-oleoyl-sn-glycerol) and SLS (1,3-distearoyl-2-linoleoyl-sn-glycerol) was examined by using DSC and conventional and synchrotron radiation X-ray diffraction. The solid-solution phases were observed in the metastable α and γ forms in all concentration ranges. Results indicated that the miscible γ form did not transform to the β′ form when the mixtures were subjected to simple cooling from a high-temperature liquid to a low-temperature solid phase. However, and α-melt-mediated transformation into β′ and β₂ resulted in the formation of immiscible phases in concentration ranges of SLS below 30%. By contrast, at SLS concentration ranges above 30%, the α-melt-mediated transformation caused crystallization of only the γ form, and β′ and β₂ crystals did not appear. These results show that the specific interactions between SOS and SLS are operative in the phase behavior of the mixture states of SOS and SLS.     

Decoupling between Enthalpy Relaxation and Viscous Flow and Its Structural Origin in Fragile Oxide Glass-Forming Liquids

The structural relaxation kinetics at the glass transition in tellurium oxide (TeO₂)-based glasses has been examined from viscosity and heat-capacity measurements to clarify the features of the structural relaxation in fragile oxide glass-forming liquids. A large decoupling between enthalpy relaxation and viscous flow, i.e., a large discrepancy between the activation energies for the enthalpy relaxation (recovery), Δ H , and viscous flow, E _η, has been demonstrated in TeO₂-based glasses. The values in x K₂O· x MgO·(100 − 2 x )TeO₂ glasses, for example, are ∼919–1051 kJ/mol for Δ H and ∼ 577–701 kJ/mol for E _η, given the ratio of Δ H/E _η≈ 1.44–1.59. Some viscosity and heat-capacity data (all data have been reported previously) obtained from similar experiments in Sb₂O₃–B₂O₃ glasses belonging to the category of strong glass-forming liquids have been reanalyzed in this paper for comparison; a strong coupling was found to exist between Δ H and E _η, i.e., Δ H/E _η≈ 0.98–1.18. An origin of decoupling between Δ H and E _η in fragile glass-forming systems such as TeO₂-based glasses has been discussed by considering the glass structure model for fragile glasses; strongly bonded correlated (highly constrained) regions are surrounded or connected by weakly bonded noncorrelated (unconstrained) parts.     

Ketones from carboxylic acids over supported magnesium oxide and related catalysts

Silica-supported alkaline earth oxides revealed excellent activity to convert acetic acid selectively into acetone in a vapor-phase fixed-bed flow system. Acetone was obtained through the cyclic formation of alkaline earth acetate followed by decomposition. Magnesium oxide should be supported on the silica surface without formation of magnesium silicate, which was inactive for the present reaction. Attempted syntheses of benzophenone and acetophenone are also described.