Keratanase II-catalyzed synthesis of keratan sulfate oligomers by using sugar oxazolines as transition-state analogue substrate monomers: a novel insight into the enzymatic catalysis mechanism

Keratan sulfate (KS) oligomers with well-defined structures were synthesized by keratanase II (KSase II)-catalyzed transglycosylation. N-Acetyllactosamine [Galbeta(1-->4)GlcNAc; LacNAc] oxazoline derivatives with sulfate groups at the C-6 (1 a) and both the C-6 and the C-6' (1 b) were prepared as transition-state analogue substrate monomers for KSase II. Monomer 1 a was effectively oligomerized by the enzyme under weak alkaline conditions, to give alternating 6-sulfated KS oligomers (2 a) in good yields, and with total control of regioselectivity and stereochemistry. KSase II also recognized 1 b, which provided fully 6-sulfated KS oligomers (2 b) in good yields under similar conditions. Nonsulfated LacNAc oxazoline was difficult to oligomerize enzymatically. These results imply that the catalysis mechanism of KSase II involves a sugar oxazolinium ion that requires the 6-sulfate group in the GlcNAc residue not only in hydrolysis of KS chains, but also in oligomerization of oxazoline monomers. This is the first report of KSase II-catalyzed transglycosylation to form beta(1-->3)-glycosidic bond through a substrate-assisted mechanism.     

Reduction of nitric oxide with activated PAN fibres

The reductive removal of nitric oxide from flue gases by reaction with polyacrylonitrile-based active carbon fibres (PAN-ACF) activated with sulphuric acid has been studied at 423–632 K, using a circulating flow reactor. Nitric oxide (0.67 mmol) was completely removed via reduction with 1 g activated carbon under optimum conditions in 210 and 60 min at 423 and 623 K, respectively. N₂ was formed as NO was removed. Some oxygen remained on the carbon surface at 423 K, but was desorbed as CO or CO₂ on subsequent heating to 623 K. The bimolecular reaction of NO reduction over PAN-ACF, and the possible active sites of oxygen surface groups are discussed in the light of a kinetic study and a comparison of the fibre activation at different temperatures.     

Chemospecific ring-opening polymerization of α-methylenemacrolides

α-Methylenemacrolides having various groups, such as aromatic, ether, and amine, were enzymatically, anionically, and radically polymerized. The polymerization with the lipase catalyst successfully afforded polymers only through the ring-opening process, whereas the vinyl polymerizations selectively proceeded by using anionic and radical initiators. The polyesters obtained by the enzymatic polymerization have a polymerizable methacrylic methylene group in the main-chain, in addition to the aromatic and polar groups, and were further radically polymerized to quantitatively produce a cross-linked polymer gel.     

Preparation of micrometer‐sized,multifunctional capsule particles for cosmetic by microsuspension polymerization utilizing the self‐assembling of phase separated polymer method

Micrometer‐sized polymer particles with encapsulated ultraviolet (UV) absorbent, fluorescent agent, and blue pigment were successfully prepared by microsuspension polymerization utilizing the Self‐assembling of Phase Separated Polymer method. The particles were characterized by optical microscope and particle size distribution analysis, and they were evaluated on their usefulness for cosmetic using UV spectrometry, colorimetry, VISIA? Evolution, and bioassay. The capsule particles had multifunctional properties, which are very attractive in the cosmetic field, especially in whitening, brightening, the improvement of face‐texture, and less noticeable pores in face, as well as the protection from UV. Moreover, bioactivities of the particles under the UV irradiation, which were examined with the films prepared from capsule components, revealed not only makeup effect but also the activation of human epidermal keratinocytes. The results suggest the importance of blue light in the field of cosmetics. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

High-Temperature Oxidation at 1500° and 1600°C of SiC/Graphite Coated with Sol–Gel-Derived HfO2

Oxidation of SiC compositionally graded (SCGed) graphite coated with HfO₂ derived from HfCl₄ by a sol–gel process was performed at 1500° and 1600°C in a flowing gas mixture of Ar and O₂ (80/20 kPa). SCGed graphite was produced by reaction of graphite with either molten Si or SiO gas at 1450°C. The sol–gel-derived HfO₂ precursor was deposited on SCGed graphite by a dip-coating method. Isothermal and cyclic oxidation of uncoated- and HfO₂-coated SCGed graphite was studied by monitoring overall weight change using an electro-microbalance. Scanning electron microscopy with energy-dispersive X-ray analysis was used to observe the surfaces and cross-sections of the oxidized HfO₂-coated SCGed graphite. The formation of HfSiO₄ was confirmed on the outer layer of the oxidized sample, beneath which a thin silica layer was formed. The improved oxidation resistance of SCGed graphite by coating with HfO₂ is discussed on the basis of the formation of these two layers.     

High-efficiency GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy

We report the initial results of GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy (MBE) technique. For GaAs single-junction solar cell, with the application of AlInP as the window layer and GaInP as the back surface field layer, the photovoltaic conversion efficiency of 26% at one sun concentration and air mass 1.5 global (AM1.5G) is realized. The efficiency of 16.4% is also reached for GaInP solar cell. Our results demonstrate that the MBE-grown phosphide-contained III-V compound semiconductor solar cell can be quite comparable to the metal-organic-chemical-vapor-deposition-grown high-efficiency solar cell.     

Profiling and Imaging of Phospholipids in Brains of Abcd1‐Deficient Mice

ABCD1 is a gene responsible for X‐linked adrenoleukodystrophy (X‐ALD), and is critical for the transport of very long‐chain fatty acids (VLCFA) into peroxisomes and subsequent β‐oxidation. VLCFA‐containing lipids accumulate in X‐ALD patients, although the effect of ABCD1‐deficiency on each lipid species in the central nervous system has not been fully characterized. In this study, each phospholipid and lysophospholipid species in Abcd1‐deficient mice brains were profiled by liquid chromatography‐mass spectrometry. Among the phospholipid and lysophospholipid species that are significantly more enriched in Abcd1‐deficient mice brains, VLCFA were present in 75, 15, 5, 4, and 1 species of phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, lysophosphatidylcholine, and lysophosphatidylethanolamine, respectively. Most VLCFA were incorporated at the sn‐1 position of phosphatidylcholine and phosphatidylethanolamine. Among the phospholipid species that are significantly less enriched in Abcd1‐deficient mice brains, odd‐numbered saturated or mono‐unsaturated fatty acyl moieties are contained in all phosphatidylcholine species. In addition, a number of phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine species contained highly unsaturated fatty acyl moieties. Intriguingly, 44:1 phosphatidylcholine with VLCFA was mainly distributed in the gray matter, such as the cortex, but not in the white matter in the cerebrum and cerebellum. These results show that ABCD1‐deficiency causes metabolic alternation of long‐chain fatty acids and VLCFA. Moreover, our results imply a molecular mechanism for the incorporation of saturated or monounsaturated VLCFA into the sn‐1 position of phospholipids, and also indicate that the distribution of phospholipids with VLCFA may correlate with the development of X‐ALD.     

Ursodeoxycholic Acid Suppresses Lipogenesis in Mouse Liver: Possible Role of the Decrease in β-Muricholic Acid,a Farnesoid X Receptor Antagonist

The farnesoid X receptor (FXR) is a major nuclear receptor of bile acids; its activation suppresses sterol regulatory element-binding protein 1c (SREBP1c)-mediated lipogenesis and decreases the lipid contents in the liver. There are many reports showing that the administration of ursodeoxycholic acid (UDCA) suppresses lipogenesis and reduces the lipid contents in the liver of experimental animals. Since UDCA is not recognized as an FXR agonist, these effects of UDCA cannot be readily explained by its direct activation of FXR. We observed that the dietary administration of UDCA in mice decreased the expression levels of SREBP1c and its target lipogenic genes. Alpha- and β-muricholic acids (MCA) and cholic acid (CA) were the major bile acids in the mouse liver but their contents decreased upon UDCA administration. The hepatic contents of chenodeoxycholic acid and deoxycholic acid (DCA) were relatively low but were not changed by UDCA. UDCA did not show FXR agonistic or antagonistic potency in in vitro FXR transactivation assay. Taking these together, we deduced that the above-mentioned change in hepatic bile acid composition induced upon UDCA administration might cause the relative increase in the FXR activity in the liver, mainly by the reduction in the content of β-MCA, a farnesoid X receptor antagonist, which suggests a mechanism by which UDCA suppresses lipogenesis and decreases the lipid contents in the mouse liver.     

Predicting Solid–Liquid Equilibrium of Fatty Acid Methyl Ester and Monoglyceride Mixtures as Biodiesel Model Fuels

Fatty acid methyl esters from plant oils are the main component of biodiesel and used as a substitute for petroleum diesel. Biodiesel generally contains a small amount of monoglycerides as intermediate compounds, which have high melting points and often solidify and clog fuel filters. The prediction of the cold-flow property of biodiesel is of great importance for practical application. In this study, a thermodynamic study was conducted for mixtures of monoglycerides and fatty acid methyl esters. Temperatures of the solid–liquid equilibrium for the mixtures were measured by differential scanning calorimetry and visual observation, while the theoretical values were calculated using the modified Universal Quasi-chemical Functional-group Activity Coefficients (UNIFAC) model (Dortmund). The theoretical and experimental results were in good agreement, especially for binary mixtures of monoglycerides and methyl esters. The importance of monoglycerides on the cold-flow properties of biodiesel was determined, and the effects could be well described by the modified UNIFAC model (Dortmund).     

Differential Scanning Calorimetric Study of Solidification Behavior of Monoacylglycerols to Investigate the Cold-Flow Properties of Biodiesel

Monoacylglycerols (MAG) are impurities present in biodiesel as a result of incomplete reactions. MAG often solidify in biodiesel even at room temperature because of their high melting points. This worsens the cold-flow properties such as the cloud point and pour point. We hypothesized that several types of MAG solidify simultaneously; therefore, we performed differential scanning calorimetry of binary mixtures of MAG to elucidate their interactions during solidification. Three thermodynamic formulas were then applied to the experimental results: (1) non-solid-solution, (2) solid-solution, and (3) compound formation models. Binary mixtures of MAG showed complicated liquidus curves with multiple upward convex shapes, with which only the compound formation model fitted well. This model was applied to multicomponent mixtures that consisted of MAG and fatty acid methyl esters (FAME) as surrogate biodiesel fuels. We confirmed that the model still worked well. The results show that the compound formation model has good potential for predicting the cold-flow properties of biodiesel.