The Square-off centrifugal cascade constitutes an important component of a flexible cascade. In practical engineering operation，during the propagation of fluid disturbances generated by the cascade，the feed pressure at the depleted-end units exceeds the operational limit. To enhance the disturbance resistance of the lean-end units in a stepped centrifugal cascade，static and dynamic hydraulic methods were employed to investigate the impact of the critical parameter α value of the electric control valve on the cascade fluid state. Results indicate that pressure disturbance fluctuations propagate to both sides of the cascade. After re-establishing steady-state conditions，these fluctuations primarily affect the separation stage on the rich-side of the disturbed stage. Similarly，pressure fluctuations caused by flow disturbances propagate to both sides of the cascade，primarily impacting the separation stage on the lean-side of the disturbed stage upon re-establishing steady-state conditions. The value of α affects the cascade's disturbance resistance capability. Through fluid disturbance hydrodynamic analysis，it was found that when α is set to 0，1，or 2 for each separation stage，the disturbance has a relatively minor impact on the system's final steady-state conditions. With α set to 3 and 4，respectively，when the feed flow rate is increased by 5%，the relative changes in the feed pressure and the depleted-stream pressure at the depleted-end separating stage decrease from 6.02% to 1.96% and from 2.66% to 0.25%，respectively; while those at the enriched-end separating stage decrease from 5.48% to 0.47% and from 2.17% to 0.14%，respectively. Dynamic analysis of pressure fluctuations caused by pressure or flow disturbances in the cascade revealed that，using the largest unit in the cascade as the boundary，setting α=0 or 1 for the separation stage on the rich-side and a=2 for the separation stage on the lean-side minimizes the impact of pressure fluctuations on each separation stage. Under a 5% increase in feed flow rate disturbance，the relative changes of the feed pressure at the depleted-end separating stage decreases from 6.49% to 4.78% and 4.92%; under the disturbance of unit bypass closure，it decreases from 11.97% to 1.46% and 1.56%. These findings provide reference for setting electric control valve parameters in practical stepped centrifugal cascades.
To fill the gap in the synthesis of polychlorinated biphenyl isotope internal standard reagents in China，this study investigates the synthesis and characterization method of stable isotope-labeled 2,3,3’,4,4’,5-hexachlorobiphenyl-2’,6,6’-D3. Using 1,2,3,4-tetrachlorobenzene-D2 as the starting material，the intermediate 1,2,3,4-tetrachloroiodobenzene-D was obtained via iodination. Meanwhile，using 3,4-dichloroaniline as the material，3,4-dichlorophenylboronic acid pinacol ester-2,6-D2 was synthesized through three steps: hydrogen/deuterium exchange，diazotization iodination，and boration. The target product 2,3,3’,4,4’,5-hexachlorobiphenyl-2’,6,6’-D3 was obtained via Suzuki coupling of the two intermediates. According to the amount of 1,2,3,4-tetrachlorobenzene-D2，the overall yield of this synthetic route was 31.14%. The structure of the target product was characterized by 1H NMR，gas chromatography and mass spectrometry. The chemical purity of the product was 99.04% and the abundance of deuterium isotope was 99.17 atom%D，and it can be used as a standard reference material for the detection of polychlorinated biphenyls.
Shielding performances of Ta-10W alloy and Pb in CT lateral-scattered radiation fields were compared using NIST XCOM data and MCNP6 models of a tungsten-target source，a PMMA phantom，and flat shielding plates. The air-kerma ratio \begin{document}$B_k $\end{document} was used to characterize transmission. As the tube voltage increased from 80 to 140 kVp，the mean energy of the 90° scattered spectrum increased from 47.01 to 57.95 keV，and the air-kerma contribution from 67.4–88.0 keV increased from 2.40% to 19.14%. For the same \begin{document}$B_k $\end{document} as 2.5 mm Pb，the equivalent Ta-10W thicknesses were 2.01，1.50，1.37，and 1.33 mm at 80，100，120，and 140 kVp，respectively，corresponding to thickness reductions of 19.56%–46.98%. At 100–140 kVp，the areal density was reduced by 10.67%–21.08%. The mass attenuation coefficient of Ta-10W at 80 keV was about 3.15 times that of Pb. The advantage is attributed to enhanced attenuation above the Ta/W K edges and below the Pb K edge，providing a numerical reference for thin local shielding in CT rooms.
Aiming at the shortage of benzidine isotope internal standard reagents in environmental monitoring and food safety detection，an efficient synthetic method for stable isotope deuterium-labeled benzidine-D8 was developed. Benzidine-D8 was synthesized via two-step reactions: reduction of nitrobenzene-D5 to hydrazobenzene-D10 under alkaline conditions with zinc powder，followed by acid-catalyzed intramolecular rearrangement. The total yield of benzidine-D8 was 50.3% based on the molar amount of starting material nitrobenzene-D5. The product was characterized by HPLC and ESI-MS，with a chemical purity of 99.7% and deuterium isotopic abundance of 99.8 atom%. The results indicate that the synthesized benzidine-D8 is suitable as an internal standard for the quantitative determination of benzidine residues in soil，water and textile samples.
Boron Neutron Capture Therapy (BNCT) is a binary targeted radiotherapeutic approach that achieves single-cell-level tumor eradication via the 10B(n,α)7Li nuclear reaction，thereby offering distinct clinical advantages for recurrent and refractory solid tumors. The performance of boron delivery agents is a pivotal factor governing both the therapeutic efficacy and safety of BNCT. Conventional boron agents are inherently constrained by inadequate tumor specificity，low boron payload，suboptimal pharmacokinetic behavior，and the absence of real-time imaging capabilities，which collectively undermine their clinical applicability in precision nuclear medicine. To overcome these shortcomings，the modular design strategy has recently been introduced into BNCT boron drug development，culminating in an integrated platform that encompasses four functional modules: targeted recognition，high-density boron loading，intelligent delivery，and multimodal imaging. This conceptual shift is progressively steering BNCT boron agents toward advanced systems featuring active tumor targeting，smart controlled release，and theranostic integration. The present review systematically examines the research landscape and key technological breakthroughs in modular BNCT boron drugs over the period from 2020 to 2026. It elucidates the design principles and optimization strategies for each individual module，with special emphasis on the scientific challenges inherent in multi-module synergistic assembly. Future perspectives are also delineated，highlighting intelligent responsive multimodal boron formulations，device-drug integrated precision theranostic systems，and cost-effective domestically manufactured solutions，with the goal of furnishing a systematic reference framework for the molecular design，process refinement，quality assurance，and clinical translation of next-generation BNCT boron agents.
