At the Japan Atomic Energy Agency (JAEA), the simulation code "MUGTHES (MUlti Geometry simulation code for THErmal-hydraulic and Structure heat conduction analysis in boundary fitted coordinate)" has been developed to evaluate thermal striping phenomena that are caused by the turbulence mixing of fluids at different temperatures. In this paper, numerical schemes for thermal-hydraulic simulation employed in MUGTHES are described, including the LES model. A simple method to limit numerical oscillation is adopted in energy equation solutions. A new iterative method to solve the Poisson equation in the BFC system is developed for effective transient calculations. This method is based on the BiCGSTAB method and the SOR technique. As the code validation of MUGTHES, a numerical simulation in a T-junction piping system with the LES approach was conducted. Numerical results related to velocity and fluid temperature distributions were compared with existing water experimental data and the applicability of numerical schemes with the LES model in MUGTHES to the thermal striping phenomenon was confirmed.

Highly substituted conjugated enynes with functional groups have gained significant importance as versatile synthetic intermediates. [1] However, conventional approaches to these structures have relied on tedious multistep sequences involving the Sonogashira coupling reaction. Transition-metal-catalyzed alkynylmetalation reactions have emerged recently as novel protocols for the construction of conjugated enyne frameworks through cleavage of a C(sp)Àm bond (m = SnBu 3[2] and B(pinacol) [3] followed by addition of the resulting alkynyl and metallic moieties across alkynes; the latter is then converted further to an organic group by subsequent cross-coupling reactions. On the other hand, to our knowledge, catalytic direct insertion of alkynes into a C(sp)ÀC bond has never been achieved. Herein, we report nickel/BPh 3 -catalyzed alkynylcyanation of alkynes and 1,2-dienes as an atom-economical and stereoselective method to access functionalized conjugated enyne structures.At the onset, we anticipated the reaction mode of alkynyl cyanides in the presence of a nickel catalyst, because electrondeficient alkynes are prone to undergo homo-and/or crosscyclotrimerization reactions under nickel catalysis.[4] Indeed, the reaction of 3-phenylpropynenitrile (1 a) with 4-octyne (2 a) in the presence of [Ni(cod) 2 ] (10 mol %) (cod = cyclooctadiene) and xantphos (10 mol %) in toluene at 100 8C for 3 h gave the expected cis-alkynylcyanation product (3 aa) in only 11 % yield and a mixture of substituted benzenes in 66 % yield which arose by trimerization of 1 a [Eq. (1)]. On the other hand, the presence of BPh 3 (30 mol %) as a Lewis acid (LA) cocatalyst [5] dramatically shifted the reaction path, [6] affording 3 aa in 69 % yield with a small amount of the benzene derivatives.We then further tested the catalysis on the reactions of various alkynyl cyanides and found that aryl-, alkenyl-, alkyl-,

No abstract

No abstract

No abstract