AbstractInnovation in synthesis methodologies is crucial for advancing the discovery of new materials. This work reports the electrosynthesis of a [Au13(4‐tBuPhC≡C)2(Dppe)5]Cl3 nanocluster (Au13 NC) protected by alkynyl and phosphine ligands. From simple precursor, HAuCl4 and ligands, the whole synthesis is driven by a constant potential in single electrolytic cell. X‐ray crystallography determines its total structure. Control experiments, cyclic voltammetry, Proton Nuclear Magnetic Resonance (1H NMR), gas chromatography, and other characterizations demonstrate that a critical tetranuclear Au(I) complex defines the electrochemical redox behavior of the reaction solution. The critical role of a base (e.g., triethylamine) is to suppress the hydrogen evolution reaction at the cathode, paving the way for the reduction of Au ions. To resolve the problem of over‐reduction and deposition of Au on the cathode, pulsed electrolysis, which is specific to electrosynthesis is employed. It significantly improves the reaction rate and the isolated yield of Au13. To extend the application scope, another four NCs protected by different ligands, [Au13(4‐FPhC≡C)2(Dppe)5]Cl3, [Au8(2‐CF3PhC≡C)2(Dppp)4](PF6)2, [Au11(Dppp)5]Cl3, and [Au8(SC2H4Ph)2(Dppp)4]Cl2 are synthesized electrochemically, demonstrating the versatility of the strategy.

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AbstractPurposeDue to the tight curvature in their design, ring applicators are usually associated with large positioning errors. The standard practice to correct for these deviations based on global offsets may not be sufficient to comply with the recommended tolerance. In this work, we investigate two methods for applicator reconstruction that implement position‐dependent source offset corrections.MethodsMeasurements were performed using the Varian Interstitial PEEK Ring 60° and a Varian BRAVOS afterloader. Source positioning was characterized by means of autoradiographs acquired for three different loading patterns and three 192Ir sources over a period of 5 months. Additionally, the actual source path was determined by means of a series of planar kV images for different dummy cable positions. The first position‐dependent correction method consists of locally modifying the radius of the reconstructed source path according to the measured offsets. The second method, recommended by Varian, simulates a bidirectional movement of the source during applicator reconstruction to compensate for positioning errors.ResultsAutoradiographs showed a quasi‐linear increase of the dwell position offsets, with a negligible error at the tip and a value close to 3 mm at the end of the ring. This result, consistent with a circular wire movement with an effective radius 0.5 mm larger than the nominal value, was in agreement with the observations from the kV images. After implementation of the position‐dependent correction methods, residual positioning errors for the two methods resulted in a mean value (±1 SD) of 0.0 (±0.3) mm, and a range of [−0.7 mm, 0.7 mm].ConclusionThe two tested methods for applicator reconstruction with position‐dependent source offset corrections were able to successfully correct the positioning errors. The method recommended by the manufacturer had the additional advantages of a more straightforward implementation and the potential for use in other applicator types.

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Abstract Background This work aimed to develop deep learning (DL) models for CT-free attenuation and Monte Carlo-based scatter correction (AC, SC) in quantitative 90Y SPECT imaging for improved dose calculation. Methods Data of 190 patients who underwent 90Y selective internal radiation therapy (SIRT) with glass microspheres was studied. Voxel-level dosimetry was performed on uncorrected and corrected SPECT images using the local energy deposition method. Three deep learning models were trained individually for AC, SC, and joint ASC using a modified 3D shifted-window UNet Transformer (Swin UNETR) architecture. Corrected and unorrected dose maps served as reference and as inputs, respectively. The data was split into train set (~ 80%) and unseen test set (~ 20%). Training was conducted in a five-fold cross-validation scheme. The trained models were tested on the unseen test set. The model’s performance was thoroughly evaluated by comparing organ- and voxel-level dosimetry results between the reference and DL-generated dose maps on the unseen test dataset. The voxel and organ-level evaluations also included Gamma analysis with three different distances to agreement (DTA (mm)) and dose difference (DD (%)) criteria to explore suitable criteria in SIRT dosimetry using SPECT. Results The average ± SD of the voxel-level quantitative metrics for AC task, are mean error (ME (Gy)): -0.026 ± 0.06, structural similarity index (SSIM (%)): 99.5 ± 0.25, and peak signal to noise ratio (PSNR (dB)): 47.28 ± 3.31. These values for SC task are − 0.014 ± 0.05, 99.88 ± 0.099, 55.9 ± 4, respectively. For ASC task, these values are as follows: -0.04 ± 0.06, 99.57 ± 0.33, 47.97 ± 3.6, respectively. The results of voxel level gamma evaluations with three different criteria, namely “DTA: 4.79, DD: 1%”, “DTA:10 mm, DD: 5%”, and “DTA: 15 mm, DD:10%” were around 98%. The mean absolute error (MAE (Gy)) for tumor and whole normal liver across tasks are as follows: 7.22 ± 5.9 and 1.09 ± 0.86 for AC, 8 ± 9.3 and 0.9 ± 0.8 for SC, and 11.8 ± 12.02 and 1.3 ± 0.98 for ASC, respectively. Conclusion We developed multiple models for three different clinically scenarios, namely AC, SC, and ASC using the patient-specific Monte Carlo scatter corrected and CT-based attenuation corrected images. These task-specific models could be beneficial to perform the essential corrections where the CT images are either not available or not reliable due to misalignment, after training with a larger dataset.

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AbstractSince its discovery in 1997, the single molecule surface‐enhanced Raman spectroscopy (SM‐SERS) has attracted wide interest owing to its enormous potential in many fields. However, the commercialized applications of SM‐SERS are still limited by the lack of a clear understanding of the relevant mechanism in the famous SM‐SERS experiments. In this study, a salt‐gradient model is proposed to deeply investigate the physical nature and update insights into the morphological, structural, and component evolution processes of Ag NPs from dispersed nanostructures to aggregation states in the salt‐induced aggregation SERS strategy. A gradient interface is observed, where an ultrahigh sensitivity approaching a single molecule level, has been achieved in Ag colloidal system. An unusual dissolution of Ag, the release of Ag+ ions from Ag NPs, and the final precipitation of AgCl can be evidenced. Thus, except for aggregation effect, the active AgCl packaging shell on the surface of Ag NPs remarkably improves the SERS property. This work not only reveals the physics processes and nature of SM‐SERS but also offers a new way to exploit the SM‐SERS into practical applications by means of designing different surface states of NPs and various activation compositions to meet diverse molecule systems.

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