Search Results (647)

Objectives: Fixed-dose combination tablets containing sitagliptin hydrochloride (SG) and metformin hydrochloride (MF) are a mainstay in the clinical management of type 2 diabetes. However, SG is highly susceptible to chemical degradation during storage, particularly in the presence of MF. Herein, a bilayer tablet in which SG and MF are physically separated into distinct layers was designed to enhance the chemical stability of SG while ensuring pharmacokinetic equivalence to the marketed reference product Janumet^®. Methods: The compositions of individual SG and MF compartments were selected based on evaluations of their physical properties and dissolution profiles. Critical process parameters, including the pre- and main compression forces and coating levels of bilayer tablets, were fine-tuned to achieve dissolution characteristics comparable to those of the reference product. Results: Under accelerated storage conditions (40 °C, 75% relative humidity), the optimized bilayer tablet exhibited superior stability, with total SG-related impurity levels of 0.18% compared with 0.86% in the reference product after six months. Furthermore, in a randomized bioequivalence study in healthy volunteers (n = 30), the SG/MF bilayer tablet was pharmacokinetically equivalent to the reference product, with all parameters falling within the Food and Drug Administration-mandated regulatory criteria. Conclusions: In conclusion, this SG/MF bilayer tablet has better storage stability than the reference product and may be an alternative to conventional SG/MF combination tablets. Full article

In alkaline soils rich in residual phosphorus, phosphorus availability to plants depends not only on the existing reserve, but also on the redistribution of the extractable fraction within the root-explored zone. This study evaluated the effects of water regime, fertilizer treatment, and wheat presence on the distribution of ammonium lactate-extractable phosphorus (P-AL) within the 2–8 cm layer of an alkaline calcareous Chernozem with high initial P availability (P-AL = 178.1 mg kg⁻¹). The pot experiment compared plant-free soil (S0) and wheat-planted soil (SP), four water regimes (H0–H150; 0–150 L m⁻²), and four fertilization treatments: an unfertilized control (F0), a solid NPK fertilizer (FS), and a liquid NP fertilizer applied at low and high rates (FL1 and FL2). These treatments represented practical fertilization options and were not equivalent in P input, supplying 51.8, 13.9, and 27.9 mg P pot⁻¹ for FS, FL1, and FL2, respectively. Soil and plant samples were collected at BBCH 21–22, 20 days after fertilization. Water regime was a major factor shaping P-AL redistribution, significantly affecting P-AL at all three analyzed soil depths (p < 0.001), with its effect depending on vegetation condition and fertilization treatment. Wheat presence reduced P-AL relative to S0, and apparent P-AL depletion (ΔP-AL = S0 − SP) was greatest under H0, ranging from 83 to 99 mg kg⁻¹. FL2 produced the largest S0–SP contrasts under H0–H100, whereas under H150 the largest difference was associated with FS. Under high water input, the higher-input solid NPK treatment (FS), which supplied the largest P input and was the only treatment supplying K, was associated with the highest shoot biomass (16.7 g), root biomass (6.92 g), and root P accumulation (25.2 mg pot⁻¹). The results indicate that P fertilization in high-P alkaline soils should be adapted to water regime, fertilizer input and application method, without allowing for direct conclusions regarding phosphorus use efficiency, total plant P uptake, or leaching losses. Full article

With the continuous advancement of deep and ultra-deep well drilling technologies, formations with complex pressure windows are becoming increasingly common. During casing running operations, it is necessary to ensure both leak prevention in loss-prone formations and pressure stabilization in high-pressure formations, demanding increasingly higher accuracy in wellbore pressure calculation. This study establishes a wellbore pressure calculation model for managed pressure casing (MPC) running in deep wells, specifically addressing the scenario where a multi-density gradient drilling fluid column exists in the annulus after tripping out. The model’s novelty lies in integrating transient surge pressure calculation with a dynamic fluid column structure model that tracks the displacement of multi-density drilling fluid layers during casing running. The governing equations based on one-dimensional unsteady flow theory are solved using the method of characteristics with adaptive time stepping and a grid independence study confirming the discretization scheme. Quantitative analysis reveals that casing running speed is the dominant factor affecting surge pressure; when the speed increases from 0.5 m/s to 1.5 m/s, the surge pressure increases from approximately 1.2 MPa to 3.5 MPa at a 2000 m depth. Drilling fluid properties also significantly influence surge pressure: increasing the density from 2.0 g/cm³ to 2.22 g/cm³ results in a surge pressure increase of approximately 0.6 MPa; increasing the yield value from 2.85 Pa to 15 Pa leads to an increase of about 1.1 MPa; the surge pressure shows a clear increasing trend with both the consistency coefficient and flow behavior index. Casing running depth affects the buffering effect of the bottomhole flow channel; when the casing is run to 7000 m, the surge pressure is approximately 0.5 MPa higher than at 2000 m. Taking a typical deep well (8578 m) with a negative pressure window of −0.008 g/cm³ as an example, three casing running speed plans were designed and evaluated. Plan 1 was selected with running speeds ranging from 0.16 m/s in the upper section to 0.115 m/s in the lower section, maintaining the equivalent circulating density (ECD) within the safe density window throughout the entire operation. Field application of this plan proceeded smoothly without any occurrences of lost circulation or overflow. This provides a practical basis for MPC running technology in deep wells with narrow or negative pressure windows. Full article

Background: The fibrovascular stalk is characteristic of papillary bladder tumors and may be visualized on MRI as the inchworm sign. Contrast-enhanced ultrasound (CEUS) may depict the same structure dynamically by demonstrating pedicle perfusion before tumor enhancement. We hypothesized that CEUS would be more sensitive than the MRI inchworm sign for detecting a histologically confirmed fibrovascular stalk and that stalk presence would be associated with non-muscle-invasive bladder cancer without completely excluding detrusor muscle invasion. Methods: This retrospective study assessed 80 consecutive patients with one focal bladder lesion; 69 patients with technically adequate imaging and an adequate TURBT reference standard were included in the final paired analysis. Dedicated retrospective rereads of anonymized stored CEUS cine loops and complete mpMRI datasets were independently performed by two experienced readers per modality, who were blinded to the other imaging modality, histopathology, and each other’s assessments. A blinded pathologist assessed fibrovascular stalk presence and detrusor muscle invasion. Paired performance was evaluated using exact McNemar testing. Results: Histopathology identified a stalk in 48 lesions. CEUS detected 46 of 48 stalks, and MRI detected 36, corresponding to sensitivities of 95.8% and 75.0%, specificities of 90.5% and 81.0%, and accuracies of 94.2% and 76.8%, respectively. Interobserver agreement was 94.2% for both signs, with almost-perfect agreement for the CEUS vascular stalk sign (κ = 0.86) and the MRI inchworm sign (κ = 0.88). For MIBC detection, overall CEUS impression and VI-RADS 4–5 showed sensitivities of 66.7% and 87.5% (paired p = 0.063), specificities of 88.9% and 68.9% (paired p = 0.004), and accuracies of 81.2% and 75.4% (paired p = 0.424), respectively. Conclusions: However, the two signs are not operationally equivalent because the MRI inchworm sign additionally requires preservation of the underlying muscular layer, a criterion that may have contributed to its lower observed sensitivity. The stalk strongly favored non-muscle-invasive disease but did not exclude detrusor invasion. CEUS provides complementary perfusion information, whereas MRI-based VI-RADS remains central to local staging. Full article

This study develops an analytical model for a mid-deep U-shaped borehole heat exchanger (UBHE) based on the segmented finite line source method, integrating geothermal gradient, five-layer geological stratification, and groundwater seepage within a unified framework. The injection, horizontal, and extraction sections are represented by independent local coordinates and coupled through the position- and time-dependent unit-length heat-transfer rate $q_l\left(s_n,t\right)$. Validation against the benchmark results of Bao et al. yields a mean absolute error of 0.87 °C and a mean relative error of 1.6%. Numerical-independence tests identify a 1 h time step and 100/50 m vertical/horizontal segment lengths as the adopted settings, and the iterative residual reaches 10⁻⁴ °C within eight iterations for the representative case. In a homogeneous, no-seepage limiting case, the model agrees with the classical finite line-source solution with an MAE of 0.012 °C and a maximum relative-error magnitude of 0.41%. The extraction-well fluid-temperature peak occurs at 600–800 m depth, whereas the local heat-transfer direction changes near 1600 m. For the investigated 2500–650–2500 m geometry, the highest cycle-averaged outlet temperature is obtained at an insulation length of 1600 m. Sensitivity analyses further quantify the effects of seepage velocity, equivalent thermal conductivity, geothermal gradient, and the validation insulation-length assumption. Full article

Calcium-rich industrial wastes may serve as low-cost sorbents for near-source CO₂ capture, but their practical potential depends on the reactive calcium species and cyclic stability. This study compares steel slag (SS), air pollution control residue (APCr), and cement kiln dust (CKD) under controlled thermogravimetric analysis (TGA) conditions for direct gas–solid carbonation and calcination looping. X-ray diffraction identified Ca(OH)₂ in SS, CaClOH in APCr, and calcite-derived CaO in the calcined CKD as the principal reactive calcium species, corresponding to theoretical CO₂ sequestration capacities of 117.0, 58.2, and 365.2 g CO₂ kg⁻¹ waste, respectively, based on the reference intensity ratio method. After the isothermal carbonation for 1 h, experimental carbon sequestration capacities or CO₂ uptakes were 84, 39, and 201 g CO₂ kg⁻¹ waste, equivalent to conversion rates of 71.8, 67.0, and 55.0%. The CO₂ uptake curves showed that the carbonation kinetics of these wastes obeys a two-stage regime featuring an initial rapid carbonation stage followed by a slower one restricted by the product-layer diffusion of CO₂. Among the investigated industrial wastes, CKD exhibited the highest cyclic uptake of CO₂ and the lowest observed cyclic deactivation, whereas the lower cyclic performance of SS and APCr was largely limited by the calcium encapsulation and chloride-induced high-temperature sintering, respectively. This study provides an alternative solution for the valorization of industrial solid waste according to the “waste-for-waste” concept. Full article

Joint active and passive beamforming in an intelligent reflecting surface (IRS)-assisted non-orthogonal multiple-access (NOMA) downlink is a non-convex constrained problem whose Karush–Kuhn–Tucker (KKT) points are generally non-isolated. We formulate the normalized beamformers, continuous IRS angles, and inequality multipliers as one coupled projected primal–dual dynamical state. Here, single-layer means simultaneous primal–dual evolution; the numerical integrator may still contain multiple stages. Angle coordinates remove the unit-modulus equalities, while an adjacent-chain representation reduces the received-power ordering constraints without changing their feasible set for a fixed decoding order. We prove equilibrium–KKT equivalence and local transverse exponential attraction of the KKT equilibrium set under strict complementarity, locally constant active rank, nonzero streams, a quotient second-order condition, and a sufficiently large finite penalty parameter. A stiff-ODE warm-up followed by a nonmonotone semismooth pseudo-transient continuation (PTC) method computes a steady-state root. Full article

How do ordinary place names make a major river legible as heritage? This article examines Yellow River toponyms as everyday infrastructures through which hydrological space becomes spatialized memory in contemporary China. The study uses a nested mixed-methods design rather than treating every record as equivalent evidence. Its administrative frame contains 2249 unique current statutory township-level units in 178 county-level targets across all nine Yellow River province-level regions. A record-level audit links 1039 of the original 1314 survey records to 1008 unique current units, while 1215 units contain at least one place-specific interpretive field. Six non-exclusive tags identify hydrological space, multi-ethnic interaction, transport and trade, historical memory, state governance, and cross-cutting heritage activation. An E0–E3 rubric separates administrative identity from externally corroborated explanation, traceable survey narrative, and structural context. Forty-five cases form an evidence-graded pool, but only seven core and eleven qualified cases carry the main qualitative argument. Hydrological and historical narratives are the most widely supported layers, while interpretive coverage remains geographically and evidentially uneven. Place names make river heritage through localization, multilingual translation, mobility, temporal layering, and administrative circulation. Official standardization can preserve recognized forms, but it also produces selective legibility by making some variants, scripts, meanings, and origin accounts easier to retrieve than others. The article contributes to critical toponymy and critical heritage studies by showing how ordinary names mediate between local memory and national spatial infrastructures. It reframes the Global East as a setting where heritage is produced through accretion, translation, and database-mediated standardization, not only spectacular renaming. Full article

To address the difficulty in accurately characterizing the fault current response of renewable energy grid-connected devices during high-/low-voltage ride-through, this paper proposes a fault current response modeling and parameter identification method based on adaptive nonlinear compensation. First, with the fault voltage and pre-fault operating point as input variables, a basic quadratic equivalent model is established to describe the main variation characteristics of active and reactive currents during high-/low-voltage ride-through. Second, nonlinear compensation terms are introduced into the basic model to correct the response deviation caused by the simplification of fast electromagnetic control links in the electromechanical transient equivalent process, thereby improving the representation capability of the model for complex fault current characteristics. Furthermore, considering that the structural parameters of the nonlinear compensation terms are difficult to directly identify using the traditional least squares method, a differential evolution–ridge regression (DE–Ridge) hierarchical identification method is proposed. In this method, the differential evolution algorithm is used in the outer layer to adaptively optimize the nonlinear structural parameters, while ridge regression is used in the inner layer to solve the corresponding linear coefficients. Case study results show that, compared with the traditional quadratic equivalent model and the fixed nonlinear compensation model, the proposed method further reduces the fault current identification error on the validation set and improves the identification accuracy and generalization capability of fault current responses during high-/low-voltage ride-through. Full article

Many scientific and engineering domains rely on simple models whose usefulness is limited by uncertain parameters and incompatible formulations. We present a computational framework that converts deterministic, semi-empirical, and heuristic equations into stochastic model families by using bounded parameter representations and Monte Carlo sampling. An explicit semantic layer preserves differences in variable meaning, enabling comparison without forcing structural equivalence. The framework also supports supermodels—weighted mixtures of heterogeneous model families evaluated in a shared diagnostic space. The method is implemented as a reproducible pipeline for five structurally distinct Drake–Fermi–Brin models, with joint and marginal distribution analysis, exploratory clustering, parameter-importance diagnostics, and layered uncertainty decomposition. Results show that model structure and epistemic parameterization materially shape the induced distributions. Comparisons therefore remain conditional on the declared parameter bounds, sampling families, semantic bridges, and model-family weights. Nevertheless, ensemble integration can reveal behavior not visible within individual models. The space of possible supermodel configurations exceeds ${10}^{27}$, illustrating both the scale of the problem and the value of a structured probabilistic workflow. The framework provides an extensible basis for uncertainty propagation and comparison across incompatible models. Full article

Background/Objectives: In Italy, Ministerial Decree 77/2022 provides the regulatory framework for reorganizing community-based care around community health centers and hub-and-spoke territorial networks. However, translating territorial allocation into specialist working-hour requirements remains a key operational challenge, particularly in low-density and mountainous areas. This study developed an activity-based workload model to translate observed outpatient cardiology activity into estimated specialist working-hour requirements within the hub-and-spoke community health center network of local health authority (ASL 1) Avezzano-Sulmona-L’Aquila, Abruzzo, Italy. Methods: A second-stage workforce planning analysis was conducted using the baseline 30 min territorial configuration from a previously defined allocation framework. Municipal-level outpatient cardiology administrative data for 2019 were linked to standardized procedure scheduling durations and aggregated across the catchments of three hub centers and eight spoke centers according to predefined municipality-to-node assignments. Procedure volumes were converted into annual and weekly workload hours and then into nominal 36 h weekly specialist-schedule equivalents. The resulting estimates represent a pre-pandemic, utilization-based workload scenario derived from observed activity; they should not be interpreted as direct measures of underlying population demand, epidemiological need, or unmet need, nor as validated staffing requirements. Results: The reference network covered 286,832 residents and included 44,039 outpatient cardiology procedures, corresponding to 12,719.8 annual workload hours. These volumes generated 244.6 weekly workload hours, equivalent to 6.79 nominal 36 h weekly specialist-schedule equivalents. Workload was unevenly distributed across the network: the L’Aquila and Sulmona hubs accounted for the largest annual workloads, with 3014.9 and 2894.3 h, respectively, whereas Trasacco was the spoke center with the highest observed workload, with 1775.5 h. Population-standardized indicators showed substantial variation in workload intensity across the catchments, indicating that catchment population size alone did not adequately capture the observed workload differences. Conclusions: Activity-based workload estimation adds an operational workforce layer to hub-and-spoke territorial planning. By translating observed outpatient service-use volumes into specialist working-hour requirements, the model provides a transparent and potentially transferable framework to support the operational planning of community health centers in geographically complex settings. The approach is adaptable to other specialties, territories, and service configurations where comparable activity data, standardized scheduling durations, and territorial assignment inputs are available. Full article

Background and Objectives: The radiographic interpretation of restorative materials may be influenced not only by their intrinsic composition but also by external substances positioned within the X-ray beam path. Mineral-containing sunscreens (MSs) include metal oxides such as zinc oxide, which may attenuate X-rays and alter radiographic image intensity. This in vitro study evaluated the effects of MS and non-mineral sunscreen (NMS) on the mean gray values (MGVs) and aluminum-equivalent radiopacity of restorative materials. Materials and Methods: Specimens of glass ionomer cement (GIC), flowable composite resin (FC), and resin composite (RC) were covered with a 5 mm polymethyl methacrylate block for soft-tissue simulation. Sunscreens were applied as standardized 1 mm layers, and each material was radiographed under control, NMS, and MS conditions using identical parameters. An 11-step aluminum wedge was used for calibration. MGVs were measured using ImageJ and converted to millimeters of aluminum (mm Al). Results: Restorative material, sunscreen condition, and their interaction significantly affected MGVs (all p < 0.05). NMS produced no significant change compared with control. MS significantly increased the MGVs of GIC, FC, and RC from 67.56, 63.89, and 83.56 to 97.56, 90.00, and 104.11, respectively. Corresponding radiopacity values increased from 2.02, 1.78, and 2.79 mm Al to 3.58, 3.12, and 3.98 mm Al. Conclusions: Under the conditions of this in vitro study, the tested MS significantly increased the apparent radiopacity of all restorative materials, whereas the tested NMS had no significant effect. These findings indicate that the tested mineral-containing formulation, when positioned within the X-ray beam path, can alter the radiographic appearance of dental restorations. Awareness of this potential superimposition effect may help reduce the risk of misinterpretation during radiographic evaluation. Full article

This study presents a numerical comparison of dimensional and non-dimensional implementations of the classical benchmark problem of steady natural convection in a two-dimensional differentially heated square cavity over the Rayleigh-number range 10³ ≤ Ra ≤ 10¹². The novelty of this work lies in the systematic comparison of both formulations under identical numerical conditions, providing an implementation-oriented assessment of their benchmark accuracy, mesh sensitivity, continuation strategy, and computational efficiency. The governing equations of mass, momentum, and energy conservation were solved under the Boussinesq approximation using primitive variables and the finite-element method. Since both formulations are theoretically equivalent descriptions of the same physical problem, the purpose of this work is not to reassess their physical validity, but to examine their numerical behavior under identical benchmark conditions in terms of mesh sensitivity, continuation strategy, benchmark accuracy, and computational efficiency. In the dimensional implementation, temperature differences of 1, 10, 25, and 50 K were considered, and the corresponding cavity lengths were determined from the Rayleigh-number definition. The main calculations were performed with ΔT = 25 K, while ΔT = 50 K was retained only as an exploratory sensitivity case. Boundary-layer refinement was applied along the vertical walls over the range 10³ ≤ Ra ≤ 10¹². The results show that, once the near-wall gradients are properly resolved, both implementations predict essentially identical average Nusselt numbers, with a maximum relative difference of 0.022%. Temperature contours, stream-function distributions, and centerline profiles also exhibited the same structural behavior in both cases. For the reference mesh, the dimensional implementation exhibited a lower computational cost than the non-dimensional implementation, resulting in an approximately 31% reduction in computation time. These results demonstrate that solving the governing equations directly in dimensional variables provides a numerically efficient and physically interpretable alternative while preserving the benchmark accuracy of the classical non-dimensional formulation. Full article

To address the challenge of balancing junction temperature prediction accuracy and computational efficiency for high-power multi-chip IGBT modules in automotive applications during complex electro-thermal conversion processes, this study proposes an improved three-dimensional thermal network model based on equivalent power loss injection. Firstly, the effective heat conduction area of each packaging layer under actual heat flow distribution is extracted through three-dimensional finite element simulation, and the single-chip self-heating network parameters are constructed. Secondly, targeting the thermal cross-coupling effect among multiple chips, an elliptical thermal diffusion model is applied to accurately define the thermal coupling region, and a dynamic equivalent power loss compensation mechanism is introduced. Efficient decoupling of multi-heat-source interference is achieved without increasing the state-space dimension of the model. An experimental benchmarking results comparison indicates that the absolute error of junction temperature prediction by this model under steady-state operating conditions is 0.5 °C. Further comparative analysis under the full CLTC-P (China Light-duty Vehicle Test Cycle for Passenger Car) cycle verifies that the improved model not only overcomes the shortcomings of the traditional Foster model, which severely underestimates the transient peak junction temperature and alternating stress amplitude, but also effectively filters out non-physical overshoots caused by short-term ultra-narrow pulses, thus reasonably estimating the device’s maximum junction temperature within the real physical boundary. This method provides efficient theoretical support for accurate dynamic junction temperature predictions and reliability evaluations of electric vehicles under complex operating conditions. Full article

To address the discrepancy between the constant-power fire sources currently used in cable fire-related research and cable fire protection product testing and actual cable fires, this paper proposes a cable equivalent combustion simulation method based on electrical fault fires. The cable tunnel experiment platform was built and, based on energy equivalence, used an igniter to simulate a fault arc’s thermal effect and ignite the cable, obtaining the temperature rise characteristics at multiple points in the fire source area. Based on the experimental data, a simulation model for the mixed combustion of multiple cable materials was established and revised, and the heat release rate (HRR) under different fire scenarios was calculated. Then, an equivalent fire source device capable of simulating the aforementioned HRR curve was designed. The results indicate that under ignition conditions with an igniter power of 400 kW and duration of 90 s, the cable fire development exhibits nonlinear dynamic evolution, with a flame height of 0.63 m. The peak temperature rise rate and peak temperature at the measurement point reach 3.27 °C/s and 926 °C, respectively. When 39.4% of the insulation layer material of the cable participates in combustion, and the fuel molecular formula is C_2.28H_5.70O_1.42N_0.08Si_0.65, the relative error between simulated and experimental temperatures during stable combustion is 3.0%. Heat release rates for mild, moderate, and severe fires stabilize near 350 kW, 420 kW, and 530 kW under this calibrated cable model. The relative error between the temperature curve from the fire source device during the stable combustion stage and that from the actual combustion experiment is 3.4%, indicating favorable equivalence. Full article