Carbons from furan-polymers prepared in the presence of a double-chain amphiphile

Furfuryl alcohol was polymerized in the presence of a double-chain amphiphile using malonic acid or phosphoric acid as the catalyst, leading to an aggregate of spherical particles with a long period of 2.6 nm. On calcination at 1000 °C in nitrogen gas, the polymer particles were converted into lamella-patterned carbons with a long spacing of some micrometers that are composed of carbon layers 0.4 nm in spacing. The lamella-patterned carbon particles were further developed into a highly ordered structure in an appreciable portion on calcination at 2800 °C in argon gas. The present results demonstrate that the presence of a double-chain amphiphile in the polymerization process is effective for the synthesis of such a structurally modified carbon from non-graphitizable furan polymers.     

Oxidation of toluene to benzoic acid over modified V2O5-TiO2 catalyst with SeO2, TeO2 and Sb2O3

It was found that the addition of SeO₂, TeO₂ or Sb₂O₃ to a V₂O₅/TiO₂ catalyst greatly improved the catalytic activity in the vapor phase oxidation of toluene to selectively form benzoic acid.     

Direct Measurement of Crack Tip Stresses

Raman microprobe spectroscopy was used to measure the crack tip stress distribution in single-crystalline silicon using a wedge-loaded double cantilever beam (dcb) specimen. The wedge was advanced until the crack just propagated. After the crack arrested, the stresses were measured between 3 and 20 μm directly ahead of the crack. An average value of –0.43 was obtained for the slope of log stress vs log distance from the crack tip, rather than the theoretical value of –0.5. The value of K _I was determined from (1) the intercept of this curve and (2) the slope of stress against     . The values were in good agreement. The average experimental value of K _I was determined to be 0.71 MPa · m^1/2, compared to literature values for the K _IC ranging from silicon of 0.8 to 0.94 MPa · m^1/2. The value measured with the Raman is the arrest value of K _I and is expected to be lower from kinetic energy considerations associated with wedge-loaded dcb specimens.     

Cloning and sequence analysis of D-erythrulose reductase from chicken: its close structural relation to tetrameric carbonyl reductases

Sequence analysis of a cDNA for D-erythrulose reductase fromchicken liver showed that the deduced open reading frame encodesthe protein with a molecular mass of 26 kDa consisting of 246amino acids. Although the reductase shares more than 60% identityin the amino acid sequence with the mouse tetrameric carbonylreductase, these two enzymes have many biochemical differences;their substrate specificity, subcellular localization, organdistribution, etc. A three-dimensional structure of D-erythrulosereductase was predicted by comparative modeling based on thestructure of the tetrameric carbonyl reductase (PDB entry =1CYD). Most of the residues at the active site (within 4 Åfrom the ligand) of the carbonyl reductase were also conservedin the D-erythrulose reductase. Nevertheless, Val190 and Leu146in the active site of the tetrameric carbonyl reductase weresubstituted in the D-erythrulose reductase by Asn192 and His148,respectively. The substitutions in the active sites may be relatedto the difference in substrate specificity of the two enzymes.The phylogenic analysis of D-erythrulose reductase and the otherrelated proteins suggests that the protein described as a carbonylreductase D-erythrulose reductase.     

Role of supported metals in the selective reduction of nitrogen monoxide with hydrocarbons over metal/alumina catalysts

The promoting effect of supported metals on alumina catalyst was investigated for the reduction of nitrogen monoxide in oxygen-rich atmospheres. For NO reduction with propene over impregnated CoO/A1₂O₃, the first reaction step was found to be the oxidation of NO to NO₂ probably catalyzed by dispersed cobalt species. The next reaction step, which is the reaction of NO₂ with propene to form N₂, was considered to take place on the alumina surface. Although the activity of impregnated FeO/A1₂O₃ was low because of the presence of large iron oxide particles catalyzing propene oxidation with dioxygen, FeO/A1₂O₃ prepared with sol-gel method showed excellent deNO_x activity.     

Point mutation of alanine (31) to valine prohibits the folding of reduced lysozyme by sulfhydryl--disulfide interchange

In the preceding paper in this issue, we described the overproduction of one mutant chicken lysozyme in Escherichia coil.Since this lysozyme contained two amino acid substitutions (Ala³¹ValandAsn¹⁰⁶Ser)in addition to an extra methionine residue at theNH₂-terminus the substituted amino acid residues were convertedback to the original ones by means of oligonucleotide-directedsite-specific mutagenesis and in vitro recombination. Thus fourkinds of chicken lysozyme [Met^–1 Val³¹Ser¹⁰⁶-, Met^–1Ser¹⁰⁶-,Met^–1 Val³¹-and Met^–1 (wild type)] wereexpressed in E. coli. From the results of folding experimentsof the reduced lysozymes by sulfhydryl-disulfide interchangeat pH 8.0 and 38°C, follow ed by the specific activity measurementsof the folded en zymes, the following conclusions can be drawn:(i) an extra methionine residue at the NH₂-terminus reducesthe folding rate but does not affect the lysozyme activity ofthe folded enzyme; (ii) the substitution of Asn¹⁰⁶ by Ser decreasesthe activity to 58% of that of intact native lysozyme withoutchanging the folding rate; and (iii) the substitution of Ala³¹Val prohibits the correct folding of lysozyme. Since the wildtype enzyme (Met^–1-lysozyme) was activated in vitro withoutloss of specific activity, the systems described in this study(mutagenesis, overproduction, purification and folding of inactivemutant lysozymes) may be useful in the study of folding pathways,expression of biological activity and stability of lysozyme.     

Exceptional chiroptical behavior near ceiling temperature in free radical polymerization of menthyl 2-acetamidoacrylates

Effect of polymerization conditions on chiroptical properties of polymer has been studied in the polymerization of (−)- and (+)-menthyl 2-acetamidoacrylates using radical initiators under the conditions with various temperatures, monomer concentrations, and reaction times. Specific rotation and circular dichroism of the resulting polymers indicated that a ceiling temperature (T_c) affected the chiroptical properties of the polymers and the polymerizations would give preferentially a helical polymer through a radical vinyl polymerization near T_c. In addition, the helical structure of the polymer was maintained intact even heating at 120 °C in anisole.     

Pore Structure and Shape Selectivity of Platinum-Promoted Cesium Salts of 12-Tungstophosphoric Acid

Pore-widths and pore-size distributions of 0.5 wt% Pt-Cs_xH_3-xPW₁₂O₄₀ have been studied by means of adsorption of various molecules. For the distributions of micropore and mesopore, isotherms of Ar and N₂ adsorption were analyzed, respectively. Pt-Cs_2.1H_0.9PW₁₂O₄₀ possessed only ultramicropores. On the other hand, the pores of Pt-Cs_xH_3-xPW₁₂O₄₀ (x = 2.3, 2.5, 2.8 and 3.0) showed bimodal distributions in the range from micropore to mesopore, and the widths of both pores tended to increase as the Cs content increased. From the amounts and rates of adsorption for n-butane and isobutane, the pore width of Pt-Cs_2.1H_0.9PW₁₂O₄₀ was determined to be close to the molecular size of n-butane, that is, 0.43 nm. The fraction of external surface area in the total surface area of Pt-Cs_2.1H_0.9PW₁₂O₄₀ was estimated to be only 0.06 from the adsorption of 1,3,5-trimethylbenzene and t-plot of N₂ adsorption. Pt- Cs_2.1H_0.9PW₁₂O₄₀ exhibited a shape selectivity due to the uniform ultramicropores and small external surface area; it catalyzed the oxidation of n-butane but not that of isobutane. SEM and TEM measurements revealed the primary crystallites and their aggregated states.     

Evaluation of the degree of deterioration of circuit‐breaker insulators using chemical analysis and the Mahalanobis–Taguchi (MT) method

We have developed a novel evaluation technique of the deterioration degree of insulators for breakers using a chemical analysis and the Mahalanobis–Taguchi (MT) method. It is possible to evaluate the deterioration degree with great accuracy and nondestructively on‐site by this technique without the effect of humidity and external noise such as electromagnetic waves. The mechanism of the insulator's surface resistivity reduction was clarified, and it was found that the deterioration degree of insulators could be evaluated by this technique because a linear relationship existed between the results judged by the MT method and the actual measurement results for the surface resistivity. In comparison to electrical methods, such as partial electric discharge and megohmmeters, the evaluation accuracy has been improved by three digits and the range of the deterioration degree that could be evaluated was expanded by seven digits. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(1): 11–20, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20849