2D computations of FREI with cool flames for n-heptane/air mixture

Two-dimensional axisymmetric numerical simulation reproduced flames with repetitive extinction and ignition (FREI) in a micro flow reactor with a controlled temperature profile with a stoichiometric n-heptane/air mixture, which have been observed in the experiment. The ignition of hot flame occurred from consumption reactions of CO that was remained in the previous cycle of FREI. Between extinction and ignition locations of hot flames, several other heat release rate peaks related to cool and blue flames were observed for the first time. After the extinction of the hot flame, cool flame by the low-temperature oxidation of n-heptane appeared first and was stabilized in a low wall temperature region. In the downstream of the stable cool flame, a blue flame by the consumption reactions of cool flame products of CH₂O and H₂O₂ appeared. After that, the hot flame ignition occurred from the remaining CO in the downstream of the blue flame. Then after the next hot flame ignition, the blue flame was swept away by the propagating hot flame. Soon before the hot flame merged with the stable cool flame, the hot flame propagation was intensified by the cool flame. After the hot flame merged with the stable cool flame, the hot flame reacted with the incoming fresh mixture of n-C₇H₁₆ and O₂.     

Synthesis of β‐Methoxyacrylate Natural Products Based on Box‐PdII‐Catalyzed Intermolecular Methoxycarbonylation of Alkynoles

Bis(oxazoline)‐palladium(II) catalyzed carbonylation of homopropargyl alcohols afforded acyclic methoxyacrylate 2 and 6‐membered lactone 3a , 3b , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k in good combined yield. In the case of propargyl alcohols, 5‐membered lactones 3p , 3q , 16 were obtained in moderate yields. The one‐pot synthesis of kawa lactones 3a , 3r , 3s and formal synthesis of dihydroxycystothiazole A and dihydroxycystothiazole C are presented. To elucidate the stereochemistry of (+)‐annularin G and (?)‐annularin H, the first asymmetric syntheses of these natural products were achieved.     

From metal-organic framework to nanoporous carbon: toward a very high surface area and hydrogen uptake

In this work, with a zeolite-type metal-organic framework as both a precursor and a template and furfuryl alcohol as a second precursor, nanoporous carbon material has been prepared with an unexpectedly high surface area (3405 m(2)/g, BET method) and considerable hydrogen storage capacity (2.77 wt % at 77 K and 1 atm) as well as good electrochemical properties as an electrode material for electric double layer capacitors. The pore structure and surface area of the resultant carbon materials can be tuned simply by changing the calcination temperature.     

Near-infrared intersubband absorption in (CdS/ZnSe)/BeTe type-II super-lattices grown on GaAs substrate by MBE

We study the dependence of absorption wavelength on the well width in the (CdS/ZnSe)/BeTe super-lattices(SL). With well-width reduction, the wavelength decreases from 1.795 to 1.57 μm. Structural properties, strain state and interface composition are determined via XRD measurement. A (CdS/ZnSe)/Be_xMg_1−xTe structure is prepared and XRD reveals the average lattice constant match to GaAs substrate. TEM reveals that numerous stacking faults exist in the (CdS/ZnSe)/BeTe structure, and stacking faults are completely suppressed in (CdS/ZnSe)/Be_xMg_1−xTe SLs. Intersubband transition down to 1.535–1.55 μm have been observed in SLs.     

Chemoenzymatic synthesis of naturally occurring benzyl 6-O-glycosyl-beta-D-glucopyranosides

Direct beta-glucosidation between benzyl alcohol and D-glucose (5) using the immobilized beta-glucosidase from almonds with the synthetic prepolymer ENTP-4000 gave a benzyl beta-D-glucoside (1) in 53% yield. The coupling of the benzyl beta-D-glucopyranoside congener (8) derived from 1 with phenyl 2,3,4-tri-O-acetyl-1-thio-beta-D-xylopyranoside (9), ethyl 2,3,4-tri-O-acetyl-1-thio-alpha-L-rhamnopyranoside (13), and 2,3,4-tri-O-acetyl-alpha-L-arabinopyranosyl bromide (15) afforded 10, 14, and 16, respectively, as coupled products. Deprotection of 10, 14, and 16 provided the synthetic benzyl beta-D-xylopyranosyl-(1-->6)-beta-D-glucopyranoside (2), benzyl alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (3), and benzyl alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranoside (4), respectively.