Conventional Gaussian Restricted Boltzmann Machines (GRBMs) and Discriminative Restricted Boltzmann Machines (DRBMs) process continuous data using deterministic parameters, making it difficult to capture the parameter uncertainty commonly encountered in practical applications. Existing fuzzy RBM models based on type-1 fuzzy sets enhance robustness to some extent, but they treat the membership functions as precisely defined, so the uncertainty inherent in the membership functions themselves remains unrepresented. To address this, this study proposes Interval Type-2 Gaussian Fuzzy Restricted Boltzmann Machine (IT2GFRBM) and Interval Type-2 Discriminative Fuzzy Restricted Boltzmann Machine (IT2DFRBM), which extend the model parameters to interval type-2 symmetric triangular fuzzy numbers (IT2STFNs). This study extends the crisp possibilistic mean defuzzification method, derives the approximate free energy function along with a sharp, computable bound on its approximation error and an exact error ledger, and presents a training algorithm based on Contrastive Divergence (CD). Experimental results on the MNIST, Fashion-MNIST, CIFAR-10, and BloodMNIST datasets demonstrate that the proposed models outperform GRBM, DRBM, their fuzzy variants, and several baseline methods in terms of reconstruction quality, classification accuracy, and noise robustness, with one MNIST comparison excepted. These results validate the effectiveness of the interval type-2 fuzzy mechanism in capturing the uncertainty inherent in the membership functions.
Heterocyclic-linked covalent organic frameworks (COFs) integrate organic units into extended structures, offering enhanced π-conjugation, stability, light absorption, and charge separation. Leveraging these properties, this perspective explores COF design for photocatalytic uranium extraction, highlighting the design strategy, photocatalytic performance, and future challenges. It guides the development of photocatalytic uranium extraction, promoting both environmental remediation and the security of nuclear fuel supply.
Scar formation results from nonregenerative healing after tissue injury. Complications may occur if the scar grows beyond a certain threshold. Superficial X-ray radiotherapy offers significant advantages as an adjuvant method for surgical treatment of scars. Following the widespread application of the superficial X-ray radiotherapy system SRT-100, accurate dose measurements are key to the implementation of superficial X-ray radiotherapy. In this study, the absorbed dose measured in superficial X-ray radiotherapy was traced to the primary standard based on air kerma. According to this principle, based on the technical parameters of the SRT-100 system, this study establishes the corresponding reference radiation qualities by relying on an industrial X-ray tube and uses a free-air ionization chamber to obtain the corresponding correction factors through experiments and simulations to realize absolute air kerma measurements and uncertainty evaluations. In this context, air kerma calibration and associated uncertainty evaluations were performed for the parallel-plate transfer ionization chambers PTW23342 and PTW23344. The results show that the mean energies of the fluence spectra simulated at the X-ray tube voltages of 50, 70, and 100 kV were 26.2, 34.1, and 44.7 keV, respectively. The measured results of the first half-value layer at the three tube voltages were 0.538, 1.146, and 2.190 mmAl. The air kerma of three radiation qualities were 1.487, 1.436, and 1.268 mGy/s. The expanded measurement uncertainty of air kerma by the free-air ionization chamber was 0.94 k = 2 ), and the expanded uncertainties of the calibration factor in the two transfer ionization chambers were 1.00 k=2 ) and 0.96 k=2 ).
The sustainable development of nuclear energy requires efficient and reusable materials for uranium extraction from seawater, where uranyl species exist at ultra-trace levels within complex coordination environments. To overcome the limitations of empirical, trial-and-error design, this study establishes U-Predict v1.0, a structure-performance database for uranium adsorbents, and introduces an interpretable machine learning framework for adsorption performance prediction and mechanistic analysis. Trained on over 220 samples and 54 structural descriptors, the Light Gradient Boosting Machine (LightGBM) model with engineered features and optimized hyperparameters achieved a training R2 of 0.9887 and a test R2 of 0.7501, indicating robust predictive performance under heterogeneous and literature-derived conditions. SHapley Additive exPlanations (SHAP) interpretation revealed that structural and environmental variables, particularly functional group chemistry, solution pH, and surface area, jointly govern uranium the maximum adsorption capacity (qmax) through nonlinear interactions, emphasizing the dual control of material composition and adsorption environment. Experimental validation using a representative high-performance covalent organic frameworks-based adsorbent confirmed the model’s predictive reliability, with the measured qmax of 342.2 mg g−1 showing reasonable agreement with the predicted value (449.3 mg g−1; 23.8
Atomic clocks have made time and frequency the most precisely measured quantities in physics, progressing from microwave standards that realize the SI second1 to optical clocks with unprecedented precision2. A nuclear clock transfers the frequency reference from an electronic to a nuclear transition and the uniquely low-lying, laser-accessible, isomeric transition in 229Th currently offers the most practical route to compact, robust timekeeping and sensitive tests of fundamental physics3, 4, 5, 6, 7-8. Realizing such a clock requires turning spectroscopy of the 229Th nuclear resonance9, 10, 11, 12, 13, 14, 15, 16-17 into a stable discriminator for steering a traceable oscillator. Here we demonstrate a 229Th nuclear clock by stabilizing a continuous-wave, narrow-linewidth 148.4 nm vacuum-ultraviolet (VUV) laser18 to a resolved, weakly temperature-sensitive nuclear transition17,19 in 229Th:CaF2 crystals20, 21-22. A 10-mu W VUV source generated by four-wave mixing in cadmium vapour18,23,24 and phototube-based frequency modulation absorption readout provide a fast, high-signal-to-noise nuclear discriminator. The clock reaches a fractional frequency instability of 5 & times;10-13/tau/s for averaging time tau. Clock-transition frequencies measured in two independently fabricated crystals agree at the 10-13 level and are consistent with previous VUV-comb measurements on other 229Th:CaF2 crystals17. These results establish laser-addressed nuclei as operational clock references and provide a reproducible solid-state platform for compact nuclear clocks, nuclear quantum sensors and precision tests of fundamental physics.
