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The inner flow containing the ignition process of a throatless and diverging (constant diverging angle α = 5 deg) rotating detonation engine (RDE) was experimentally investigated by both optical observation and pressure measurement. An RDE that had an acrylic engine wall with a length of 70 mm and an inlet diameter of 20 mm was tested under a low back pressure condition using gaseous C 2 H 4 − O 2 as the propellants. A high-speed camera captured the ignition process, of which there were two types: deflagration-to-detonation transition and direct initiation. In addition to the visualizations of the inner flow, the pressure values in an RDE with an acrylic wall were compared with those of an RDE having a stainless steel wall with 8 pressure ports in the axial direction. The comparison revealed that the RDE exhaust flow was supersonic. A strong self-luminescence and CH* luminosity area near the injector surface during combustion suggested that the short completion of detonation combustion enabled the thermal choking of the subsonic propellant gases even when the channel was diverging. Moreover, the axial position of the erosion in the acrylic wall indicated that the heat release region was near the injector surface. Finally, a theoretical flow model for the RDE was compared to the experimental data, and the results suggested that the inner flow in the RDE can be reasonably described as a quasi-one-dimensional steady flow. [ABSTRACT FROM AUTHOR]

[Display omitted] A highly stereoselective asymmetric Henry reaction using a double fluorous-tagged Co–salen complex was conducted. The introduction of two fluorous tags into the Co–salen complex was found to be more effective in terms of improving stereoselectivity than the introduction of a strong electron-withdrawing nitro group into the same position of the salen ligand. The observed stereoselectivity was significantly higher than that when using a Jacobsen-type Co–salen complex bearing the same asymmetric source. [ABSTRACT FROM AUTHOR]

Tetrazoles were effectively synthesized from amides using diphenyl phosphorazidate or bis(p -nitrophenyl) phosphorazidate in the presence of aromatic bases. Various amides underwent the proposed cycloaddition reaction to provide the corresponding tetrazoles. Studies on the racemization of chiral substrates were also performed. Overall, the proposed synthesis method enables the preparation of 1,5-disubstituted and 1-substituted tetrazoles, and 5-substituted 1 H -tetrazoles without using toxic or explosive reagents. To create your abstract, type over the instructions in the template box below. Fonts or abstract dimensions should not be changed or altered. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The concise synthesis of fluorous Fmoc (f-Fmoc) reagents bearing C3F7 or C4F9 or C6F13 chains were achieved by fluorous mixture synthesis. The fluorous tagging process was effectively conducted using Heck type reaction of the bis-diazonium salt and the corresponding fluorous olefine, each bearing a different fluorous tag, by a one-pot double tagging strategy. At the final stage, each f-Fmoc reagent was separated from the mixture of three f-Fmoc reagents by fluorous solid phase extraction. [Copyright &y& Elsevier]

• High stereoselectivity can be achieved for asymmetric aldol reaction. • The catalyst can be recovered by immobilization on FluoroFlash®. • The catalyst can be reused up to five times with high stereoselectivity. A recyclable fluorous proline catalyst with high stereoselectivity that functions as a catalyst for asymmetric aldol reactions is described. Its high stereoselectivity and facile recovery are achieved by employing a multi-fluorous tag attachment strategy. Although a gradual decrease was observed with respect to the catalytic activity, the catalyst can be separated from the reaction mixture by adsorption onto FluoroFlash® and can be reused in that form for a maximum of five times while maintaining a high stereoselectivity.2019 Elsevier Ltd. All rights reserved. [ABSTRACT FROM AUTHOR]

Liquid propellants are commonly used in rocket engines due to their high energy density. In this study, we focused on the use of liquid ethanol and liquid nitrous oxide as propellants in a cylindrical rotating detonation engine (RDE) for practical applications, and examined the effects of various conditions on the bipropellant RDE performance. We varied the vapor quality of nitrous oxide in a mixture of liquid and gaseous nitrous oxide due to the flash boiling. In addition, we varied the liquid ethanol temperature, the injector stiffness, and momentum angle of the propellant. We then analyzed the effects of these changes on the propagation mode of the RDE under atmospheric pressure conditions. The results showed that a rotating detonation wave was observed under the combination of high vapor quality of nitrous oxide, high injector stiffness, high liquid ethanol temperature, and high momentum angle. The propagation velocity was obtained as 73∼83 % of the Chapman-Jouguet velocity. Long-duration combustion tests were also conducted, and the internal combustion structure was confirmed from the erosion of the carbon-carbon (C/C) composite material. The detonation wave was considered to propagate near the bottom of the RDE with liquid propellants from the erosion heights of the C/C composite. The erosion height was confirmed to be consistent with the fill height calculated using the sound speed of the nitrous oxide. In addition, characteristic exhaust velocity efficiencies of more than 85 % were achieved in all combustion tests. [ABSTRACT FROM AUTHOR]

An optimized, multi-gram scale synthesis of fluorous-Fmoc reagents is described. Fmoc reagents bearing C 3 F 7 , C 4 F 9 , and C 6 F 13 chains were prepared on multi-gram scale (ca. 1.0–7.0 g) in eight steps with overall yields of 73%, 60%, and 90%, respectively. The order of addition of the fluorous alkenes in a one-pot double tagging Heck reaction was also investigated in order to conduct an encoded mixture synthesis of f-Fmoc reagents. The target f-Fmoc reagents bearing C 3 F 7 , C 4 F 9 , and C 6 F 13 chains could be effectively separated based on the fluorine content of the molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple method for the synthesis of N -methylpeptides based on immobilization on TeflonTM. • During the reaction, the peptide is dissolved in solution, but after the reaction, it is immobilized and can be isolated by simple filtration. • Even an N -methylated peptide, whose synthesis is known to produce a large amount of a DKP by-product, could be easily purified. A simple and convenient TeflonTM-based method for N -methyltetrapeptide purification relying on fluorous 9-fluorenylmethanol as a C -terminal protecting group was developed. Fluorous compound–protected peptides supported on TeflonTM powder could be easily transferred between the fluorous solid phase (TeflonTM) and the liquid phase (reaction solution) by tuning the hydrophobicity of the solvent. Fluorous peptides present in a homogeneous state in solution during each elongation reaction were immobilized on TeflonTM at the end of each reaction by adjusting the hydrophobicity of the reaction solution, and they could be isolated by simple filtration, affording the facile synthesis of the corresponding N -methylated tetrapeptide. [ABSTRACT FROM AUTHOR]

To optimize the preparation methods for liposomes encapsulating mercaptoundecahydrododecaborate (BSH), we examined BSH and lipid concentrations that increased the boron content in liposomes. We improved the BSH encapsulation efficiency and boron content of the liposomes from 4.2 to 45.9 % and 9.5–54.3 μg, respectively, by changing the lipid concentration from 10 to 150 mg/mL. Notably, the boron content increased significantly from 26.2 μg to 326.3 μg at a constant lipid concentration of 30 mg/mL with increased BSH concentrations. • Preparation methods of liposomes encapsulating BSH were optimized. • Various encapsulation methods and concentrations of BSH and lipid were examined. • Liposomes prepared by this method encapsulated a high amount of boron. • The liposomes have extremely high stability in vitro. [ABSTRACT FROM AUTHOR]