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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
In radionuclide production the nuclear reaction always involves a change in the number of protons or neutrons. Reactions that result in a change in the number of protons are preferable because the product becomes a different element, facilitating chemical separation from the target, compared to, for example, an (n, γ)-reaction, where product and target are the same element. Even low-energy neutrons down to thermal energies can enter the nucleus and cause nuclear reactions while charged particles need to overcome the Coulomb barrier (Figure 4.5).
Radioisotopes in Biology and Medicine
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
This technique has been used extensively for the analysis of trace metal concentrations in various organs following X-irradiation, drug, or hormone treatment. The basic principle of neutron activation analysis is simple. The trace metals under investigation are made radioactive by bombarding the dry samples of liver, plasma, or spinal fluid with slow neutrons. During neutron irradiation, the stable trace metals, together with other elements, capture neutrons and become radioactive. By using a radiation detector, the amount of trace metal can be quantified. However, in organ samples, other elements (such as sodium, potassium, and chlorine, which have very high cross-sections for neutron capture) also become radioactive; this makes it impossible to quantify the radioactivity of a trace metal by single-channel analysis. Two techniques have been used to overcome the above difficulty. Use of multichannel analyzer: The multichannel analyzer separates the photopeak of radioisotopes of different energy. By stripping off the energy contribution from other radioisotopes with the help of a computer, one can get a single photopeak of the radioactive trace metal under investigation.Chemical separation of activated trace metals: Activated samples are digested in acid and mixed with a nonradioactive trace metal; the radioactive trace metal is precipitated chemically and then counted by a single-channel analyzer.
Activation Techniques
Published in Frank Helus, Lelio G. Colombetti, Radionuclides Production, 2019
Production of parent radionuclides for the preparation of radionuclide generators may be provided by either reactor (113Sn-113mIn) or gained from fission products (99Mo-99mTc), or produced by cyclotron (81Rb-81mKr). In principal in most radionuclide generators the parent radionuclide is adsorbed on a support material, such as an ion exchange resin, which is packed in a small column. The short-lived daughter radionuclide may be eluted with different solvents (prefered are physiological solutions) from support material. There are many different systems based on different chemical separation methods as ion exchange, liquid extraction method, thermochemical separation, etc.
Radiological risk assessment of the Hunters Point Naval Shipyard (HPNS)
Published in Critical Reviews in Toxicology, 2022
Dennis J. Paustenbach, Robert D. Gibbons
U-235 has a radioactive half-life of 7 × 108 years and is a naturally occurring radionuclide. U-235 accounts for 0.72 wt% of natural uranium with the remaining fractions consisting of U-238 at 99.27 wt% and U-234 at 0.006 wt%. Natural uranium is present in low amounts in rocks, soil, water, plants, and animals. Uranium and its decay products contribute to low levels of natural background radiation in the environment. U-235 transitions by alpha decay. Its decay products emit alpha, beta, and gamma radiation in various combinations depending upon which decay product of the U-235 decay series is evaluated. U-235 is primarily an internal radiation hazard if ingested or inhaled (ICRP 2008; Johnson et al. 2012). Studies of the chemical and physical characteristics of U-235 were carried out at HPNS due to its important role in nuclear fuel (USN 2004). Such studies included the chemical separation of U-235 samples irradiated at Lawrence Livermore National Laboratory, and animal research was also conducted to evaluate potential health effects from exposure to U-235, particularly highly enriched uranium in U-235. The potential for the presence of U-235 contamination at on-site laboratories was a primary reason it was identified as an ROC at HPNS (USN 2004). U-238 was not included as an ROC since results of the site investigations did not identify concentrations above risk screening criteria used by the USEPA and the Navy, and the majority of sampling results during site investigations were not statistically different from background.
Descriptive characteristics of occupational exposures and medical follow-up in the cohort of workers of the Siberian Group of Chemical Enterprises in Seversk, Russia
Published in International Journal of Radiation Biology, 2021
Andrey B. Karpov, Ravil M. Takhauov, Andrey G. Zerenkov, Yulia V. Semenova, Igor M. Bogdanov, Svetlana B. Kazantceva, Aleksey P. Blinov, Dmitriy E. Kalinkin, Galina V. Gorina, Olesya V. Litvinova, Yuriy D. Ermolaev, Elena B. Mironova, Mikhail B. Plaksin, Anas R. Takhauov, Lydia B. Zablotska
The main dose-creating radionuclide for workers employed at the SGCE is plutonium. Systematic monitoring for contamination by plutonium and uranium alpha-emitting radionuclides of SGCE workers was initiated in the mid-1950s (for uranium isotopes) and early-1960s (for plutonium) by specialized biophysical laboratory using the indirect method based on the radiochemical analysis of biological samples, and measuring levels of Pu/Am and U nuclides naturally excreted primarily with urine. Detection of Pu/Am and U activities in urine samples was based on the chemical separation of uranium and a mixture of plutonium and americium. The uranium radionuclides were precipitated with lanthanum fluoride and the mixture of plutonium americium was extracted with bismuth nitrate. Following precipitation, the activity of the sample was measured by solid scintillator.
Protective effects of total flavonoids from Alpinia officinarum rhizoma against ethanol-induced gastric ulcer in vivo and in vitro
Published in Pharmaceutical Biology, 2020
Kaiwen Lin, Yong Wang, Jingwen Gong, Yinfeng Tan, Tang Deng, Na Wei
Alpinia officinarum Hance (Zingiberaceae) is widely distributed in many tropical regions of Asia. In China, it is mainly distributed in Guangdong, Hainan and Yunnan. Its main chemical components are volatile oil, flavonoids and diarylheptanoids, which were found to treat digestive diseases such as indigestion, acid reflux and gastric ulcer. Many studies demonstrated its pharmacological activities, such as antibacterial (Zhang et al. 2010), antioxidant, (Ly et al. 2003), antitumor (Tabata et al. 2009) and anti-inflammatory effects (Lee et al. 2009). It has been proven that the extract of A. officinarum could be used as a beneficial medicine for ethanol-induced acute gastric injury (Wei et al. 2015) and indomethacin-induced gastric injury (Gong et al. 2018). In addition, it has been confirmed that the extract mainly contains galangin, kaempferol, 5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-heptanone (DPHA), 7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-4-ene-3-heptanone (DPHB) and 1,7-diphenyl-5-hydroxy-3-heptanone (DPHC). Among them, galangin and kaempferol are flavonoids. Therefore, we collected F-AOH by chemical separation and investigated its protective effect on ethanol-induced acute gastric injury, which provided a certain research basis on the effective components of F-AOH against gastric ulcer. Consequently, we evaluated the protective, healing and anti-inflammatory mechanisms of F-AOH in ethanol-induced acute gastric ulcer by conducting in vivo/in vitro experiments with histological and pathological examination and by using inflammatory factors as markers.