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Background252Cf is a high-intensity isotope neutron source in great demand for scientific research and device development. Currently, it is produced only in high-flux reactors in the United States and Russia, which rely on imports in China for a long time.PurposeThis study aims to analyze key factors of 252Cf production by irradiation based on the preliminary design scheme of a high-flux fast reactor.MethodsFirstly, an irradiation target design was implemented, and the fission deposition energies and energy spectra were calculated for three irradiated target designs using different zirconium hydride and Eu2O3 absorbers. Then, burnup calculations for heavy and light curium targets were performed using a burnup calculation program STEP, which was developed by China Institute of Atomic Energy. The experimental values for 252Cf produced by irradiation in the United States were then compared. Finally, the calculation results were analyzed using the energy spectrum and cross-section.ResultsComparison results between simulation and experiment indicate that 245Cm is the key nuclide affecting the production of 252Cf. Utilizing the hard-energy spectral characteristics of high-flux fast reactors can effectively reduce the fission loss of the target and increase the production of 252Cf.ConclusionsThe calculations and analysis in this study can provide theoretical and technical support for the high-flux fast neutron research reactor irradiation production of 252Cf.

The concept of the inherent safety characteristic on thermal-hydraulic of the pool-type sodium-cooled fast reactor was proposed and its formation mechanism was analyzed. That is, the excellent physical properties of sodium (high thermal conductivity, large difference value between melting point and boiling point at atmospheric pressure, and good fluidity) combined with the reasonable design of pool-type reactor (large sodium capacity, height arrangements between heat exchangers as well as cold sodium pool and core), make the reactor has a characteristic: In the early stage of reactor scrams, the sodium and metal components in the reactor vessel can be used as the effective heat sink of the core decay heat, and the heat generated in core can be removed into the sodium pool in time by heat conduction and natural circulation flow to ensure the core safety. Based on the actual reactor natural circulation test data of BN-600 and Phenix reactors, the natural circulation experiment data in the test device with sodium as working fluid and the natural circulation condition predictive calculation of the sodium-cooled fast reactors with typical layout using the different codes, the characteristic and its formation mechanism were demonstrated. The core decay heat can be transferred to the pool in time under the natural circulation condition because the good thermal conductivity of sodium and the natural circulation flow due to the reasonable reactor design result in the establishment of a good heat exchange relationship among assemblies by the wrapper walls and the sodium in inter-wrappers, then, on the one hand, the heat of the assemblies is discharged by the combined action of the sodium in the wrappers and inter-wrappers, on the other hand, the outlet temperature differences among assemblies are leveled to a certain extent, then the peak temperature is lowered. Based on the above research, for the pool-type sodium-cooled fast reactor, in the early stage of reactor emergency shutdown, the reactor’s inherent thermal-hydraulic safety characteristic alone can ensure the core safety without other heat sink, and in the later stage, it is only necessary to establish an effective heat sink from outside the reactor before the sodium temperature in the reactor rises to the safety limit. The effective heat sink can be the specially arranged decay heat removal system or the reactor vessel conventional heat loss item etc. And for the typical decay heat removal system setting heat exchangers in cold sodium pool or hot sodium pool, the system cannot play a role to removal core heat in the early stage of operation, at this time it must to rely on the inherent thermal-hydraulic safety characteristic as heat sink to ensure core safety.

Objective In the theories of pulse disgnosis in traditional Chinese medicine (TCM), it is emphasized that pulse manifestations at the radial artery within the wrist (called Cunkou) signify the physiological and pathological conditions of different internal organs in the human body. However, different opinions exist among researchers about the objectiveness of the pulse diagnosis technique. Some researchers mentioned that no significant differences were observed in pulse manifestations at various Cunkou areas, hence there might be some difficulty in evaluating the status of different organs through checking pulse manifestations at Cunkou. This research aims to analyze the pulse response at Cunkou from the aspect of the characteristics of tactile sensing, thus to give a preliminary explanation to the above question. Methods This research utilized the Weber-Fechner law to model the tactile sensing as a dynamic low-pass signal filter with varying bandwidths under different compression levels during pulse diagnosis. The model was applied to analyzing the clinical data collected previously by our group. The arterial pressures measured invasively with equipment from 14 patients with aorta coarctation were processed to simulate different pulse manifestations at Cun, Guan, and Chi positions of Cunkou when different compression levels were applied. Results Due to the characteristics of tactile sensing, significant variations were observed in pulse manifestations at different pulse-depths under the application of changing compression levels; while no such changes in pulse manifestations were observed from the employment of transducer only, without tactile sensing involved. The results explained why different understandings on pulse manifestations were formed between direct pulse-taking technique in TCM and modern sphygmography using transducers. The features of pulse manifestations at Cunkou, using direct pulse-taking technique but at different depths, superficial, middle, and deep positions, respectively, predicted by the developed tactile sensing model were in line with those described in TCM pulse theories. Conclusion Based on the developed tactile sensing model, this study preliminarily explains the phenomenon that pulse manifestation at Cunkou changes in response to the compression force applied during TCM pulse-taking. Integrating the tactile sensing model with the study of TCM pulse diagnosis opens a new chapter for visualizing and quantitatively interpreting pulse manifestations. This not only expands the scope of pulse diagnosis study effectively, but also provide a scientific basis for further technical upgrading and optimization of existing pulse diagnosis equipment. [ABSTRACT FROM AUTHOR]

We developed and validated a sensitive, heart-cutting, two-dimensional liquid chromatography–tandem mass spectrometry (2D-LC‒MS/MS) method to determine the concentration of mometasone furoate in human plasma after nasal spray administration. Isotopically labeled mometasone furoate-13C,d6 was used as an internal standard (IS). Plasma samples were prepared using a solid-phase extraction (SPE) method. With this 2D-LC strategy, the analytes were trapped in the first dimension (1D) column, and only judiciously selected portions of the 1D effluent were transferred to the second dimension (2D) column for further separation to obtain high-resolution information. MS/MS quantification was performed in positive ionization mode via multiple-reaction monitoring (MRM). This analytical method was fully validated according to related regulatory guidance, and the results showed that the method is robust and sensitive enough for pharmacokinetic investigation of mometasone furoate with satisfactory linearity from 0.25 to 30 pg mL−1. This method was successfully applied to a bioequivalence (BE) study of mometasone furoate aqueous nasal sprays in healthy volunteers. [ABSTRACT FROM AUTHOR]