Study of Neutron Radiation Field at the First Radioactive ion Beam Line in Lanzhou

International audienceThe first Radioactive Ion Beam Line in Lanzhou was a projectile fragment separator located in the HIRFL. The process of production and separation of radioactive ion beams can induce a strong and complex radiation field. The neutron dose equivalent rates were measured in four positions with a 70 MeV/u ^40Ar^18+ beam. The results were compared with that simulated by the FLUKA code. New shielding walls were installed to reduce the neutron background for spectroscopy measurement in the experimental terminal. In addition, the induced radioactivity of accelerator components and corresponding residual dose rates were analyzed for the radiation safety of accelerator workers. The airborne radioactivity as well as occupational exposure due to immersion in and inhalation of activated air were also estimated. This work aims to provide a valuable experience for the radiation study in the future fragment separator HFRS at HIAF

The experimental study of residual radioactivity induced in electrostatic deflector

As one of the key components of Sector Focusing Cyclotron at the Institute of Modern Physics, Chinese Academy of Sciences, the electrostatic deflector can be activated by primary and secondary particles, because of a mismatch between the actual value and the design value of the emittance and emergence angle. In addition, it will be struck by more particles, since there is a stray magnetic field and outgas from the surface of the electrostatic deflector. The residual radioactivity in the electrostatic deflector has been studied in two aspects: specific activity and residual dose rate, based on the gamma-ray spectrometry and Fluke 451p ionization chamber, respectively. The specific activity of radionuclides in the main components and the dust on the enclosure have been investigated by using gamma-ray spectrometry. The residual dose rate around the electrostatic deflector has been obtained by Fluke 451p ionization chamber. The results of the study show that there is a non-negligible radiological risk to the staff. This result can be provided as guidance for making a maintenance schedule, so that the dose received by staff can be kept as low as reasonably achievable. Based on the results, advice for "hands-on" maintenance and decommissioning of the SFC have been provided

Characterization of Total Phenolic Constituents from the Stems of Spatholobus suberectus Using LC-DAD-MSn and Their Inhibitory Effect on Human Neutrophil Elastase Activity

Spatholobus suberectus Dunn, belonging to the legume family (Fabaceae), has been used as a Traditional Chinese Medicine for the treatment of anemia, menoxenia and rheumatism. A limited number of studies report that various types of flavonoids are the main characteristic constituents of this herb. We have now found that S. suberectus contains about 2% phenolic components and characterized the major phenolic components as homogeneous B-type procyanidin conjugates using a liquid chromatography with diode-array detection-ESI mass spectrometry (LC-DAD/ESI-MS) method. This is the first report on occurrence of most B-type procyanidins in this herb. Moreover, the total phenolics extract was assayed for inhibitory activity on human neutrophil elastase and its IC50 was found to be 1.33 μg/mL

Large cell neuroendocrine carcinoma transformation: A novel acquired drug resistance mechanism in colorectal adenocarcinoma

Abstract Acquired resistance is a major problem limiting the clinical efficacy of treatments for metastatic colorectal cancer (mCRC). Histological transformation is an important mechanism underlying the acquired resistance of non‐small cell lung cancer and prostate cancer to targeted therapy. However, no report has examined the role of histological transformation in mCRC. Here, we report the first case of histologically transformed large cell neuroendocrine carcinoma from primary colon adenocarcinoma during antiangiogenesis and anti‐PD‐1 combination therapy. The histologic conversion was confirmed by the observation that the transformed large cell neuroendocrine carcinoma lesion retained the original mutational signature found in the primary tumor. Sequential tumor biopsy and dynamic changes in tumor markers demonstrated the transformed process. The histological transformation not only resulted in discordant responses to the same treatment but also significantly shortened overall survival. This case calls for more attention to histological transformation in mCRC. Tumor rebiopsy upon disease progression and monitoring dynamic changes in tumor markers would help to identify such cases