Multi-channel plastic-scintillator-based detection system for monitoring tritium in air

To overcome the limitations of the ionization chamber-based tritium monitor, a design for a multichannel plastic scintillator-based detection chamber for monitoring tritium in air is proposed. The performance of the chamber was characterized by Monte Carlo-based calculations with various design parameters such as thickness of the plastic scintillator (t) and number of channels (n). We considered the volume and detection efficiency of the chamber to evaluate the performance of the detector. The expected counting rate curve was in good agreement with the expected simplified physical model. The minimum detectable activity (MDA) was shown at t = 0.5 mm and n = 48 and estimated to be 29.9 kBq/m3. Compared with the experimentally estimated MDA, the relative difference was approximately 24%. However, this difference is understandable considering the different lower level of discrimination and light loss during transportation assumed in the model. The proposed tritium detection chamber is expected to be useful for environmental monitoring at some level as well as for monitoring of tritium leaks from fusion or CANada Deuterium Uranium (CANDU)-type reactors

Synthesis of Azulen-1-yl Ketones via Oxidative Cleavage of C–C Multiple Bonds in <i>N</i>‑Sulfonyl Enamides and 1‑Alkynes under Air and Natural Sunlight

A synthetic method to prepare azulen-1-yl ketones was developed via oxidative cleavage of the C–C double bond in the reaction of easily obtainable <i>N</i>-sulfonyl enamides with Cs₂CO₃ under air and natural sunlight and in the absence of a photosensitizer. Oxidative cleavage of C–C triple bonds was also demonstrated for the synthesis of azulen-1-yl ketones via a tandem Cu-catalyzed [3 + 2] cycloaddition, Rh-catalyzed arylation, photooxygenation, and ring-opening reaction in one pot under air and natural sunlight

Synthesis of Phosphaisocoumarins through Rhodium-Catalyzed Cyclization Using Alkynes and Arylphosphonic Acid Monoesters

A rhodium-catalyzed cyclization using alkynes and arylphosphonic acid monoesters for the synthesis of phosphaisocoumarins is reported. A number of arylphosphonic acid monoesters were selectively cyclized in high yields with functional group tolerance. In addition, unsymmetrical alkynes are applied in high regioselectivity

Synthesis of Diaryl Ketones through Oxidative Cleavage of the C–C Double Bonds in <i>N</i>‑Sulfonyl Enamides

An oxidative cleavage of a C–C double bond is developed from the photochemical [2+2]-cycloaddition of diaryl <i>N</i>-tosyl enamides, aryl heteroaryl <i>N</i>-tosyl enamides, and <i>N</i>-tosyl cyclic enamides with singlet molecular oxygen, followed by a ring-opening reaction mediated by Cs₂CO₃ under air and sunlight without the use of photosesitizer, producing symmetrical and unsymmetrical diaryl, heterodiaryl, and cyclic ketones in good to excellent yields. Moreover, the oxidative cleavage of C–C triple bonds from 1-alkynes is demonstrated for the synthesis of symmetrical and unsymmetrical ketones from the Cu-catalyzed [3+2]-cycloaddition, Rh-catalyzed alkoxyarylation, photooxygenation, and ring-opening reaction in one-pot. Because the synthesis of the symmetrical and unsymmetrical diaryl and/or heterodiaryl ketones bearing an electron-donating group is not easy, the present method is notable