Effect of groove shape on flow characteristics around a circular cylinder with grooves

In the flow around a circular cylinder, a sudden decrease in the drag force occurs at a high Reynolds number, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the circular cylinder surface. In this paper, in order to make clear the flow characteristics around a circular cylinder in the case of changing the shapes of grooves, the drag coefficient, pressure distribution, velocity distribution and turbulent distribution were measured. Moreover the flow around the cylinder was analyzed by applying the RNGk · ∈ turbulent model, and the surface flow pattern was investigated using the oil-film technique. From these results, it is clear that the drag coefficient of a circular cylinder with triangular grooves decreases by about 15% compared with that of a circular cylinder with arc grooves.     

Airborne gaseous 13N species and noxious gases produced at the 12 GeV proton synchrotron

The irradiation of atmospheric air with high-energy protons has been performed at the 12 GeV proton synchrotron. The specific activity of ¹³N, one of the principal airborne radioactivities, was measured as a function of the irradiation time at a dose rate of about 6·10¹⁶ eV/g/s, and compared with the calculated values. The predominant chemical species of ¹³N produced were found to be ¹³N₂and ¹³NO₂. Their proportions were approximately 55% for ¹³N₂ and 45% for¹³NO₂, being almost independent of the irradiation time. Smaller quantities of ¹³NO and H¹³NO₂ were also observed. Measurements of radiolytic products showed that ozone is a main product and that NO₂predominates among the products of nitrogen compounds, including HNO₂ and HNO₃. The G-value for ozone formation in air was estimated from the experimental data as 6.4 molecules/100 eV.     

Radical and cationic polymerizations of 3‐ethyl‐3‐methacryloyloxymethyloxetane

3‐Ethyl‐3‐methacryloyloxymethyloxetane (EMO) was easily polymerized by dimethyl 2,2′‐azobisisobutyrate (MAIB) as the radical initiator through the opening of the vinyl group. The initial polymerization rate (R_p) at 50 °C in benzene was given by R_p = k[MAIB]^0.55 [EMO]^1.2. The overall activation energy of the polymerization was estimated to be 87 kJ/mol. The number‐average molecular weight (M?_n) of the resulting poly(EMO)s was in the range of 1–3.3 × 10⁵. The polymerization system was found to involve electron spin resonance (ESR) observable propagating poly(EMO) radicals under practical polymerization conditions. ESR‐determined rate constants of propagation (k_p) and termination (k_t) at 60 °C are 120 and 2.41 × 10⁵ L/mol s, respectively—much lower than those of the usual methacrylate esters such as methyl methacrylate and glycidyl methacrylate. The radical copolymerization of EMO (M₁) with styrene (M₂) at 60 °C gave the following copolymerization parameters: r₁ = 0.53, r₂ = 0.43, Q₁ = 0.87, and e₁ = +0.42. EMO was also observed to be polymerized by BF₃OEt₂ as the cationic initiator through the opening of the oxetane ring. The M?_n of the resulting polymer was in the range of 650–3100. The cationic polymerization of radically formed poly(EMO) provided a crosslinked polymer showing distinguishably different thermal behaviors from those of the radical and cationic poly(EMO)s. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1269–1279, 2001     

On the distribution coefficient of nickel dimethylglyoximate between an aqueous solution and organic solvents

The distribution coefficients of nickel dimethylglyoximate between an aqueous solution and 6 inert solvents were determined at 20°. The distribution coefficients of the nickel chelate were quantitatively interpreted in terms of solubility parameters. The solubility parameter for the nickel chelate was evaluated to be 12.9, that for the aqueous solution to be 18.6, and the molar volume of the chelate to be 182 ml/mol.