Search Results (476,528)

The effect of reversible addition–fragmentation chain transfer (RAFT) polymerization on the structure, morphology, and thermal degradation behavior of polypropylene glycol maleate–acrylic acid copolymers (p-PGM:AA) was investigated using 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) as the RAFT agent. Copolymers synthesized at different CPDT concentrations were characterized by ¹H/¹³C NMR spectroscopy, gel permeation chromatography (GPC), transmission electron microscopy (TEM), thermogravimetric analysis coupled with mass spectrometry (TG–MS), isoconversional kinetic methods, and density functional theory (DFT) calculations. ¹H NMR spectroscopy revealed a progressive decrease in the relative intensity of vinyl proton signals with increasing CPDT concentration, indicating enhanced conversion of unsaturated fragments during copolymerization. Alkaline hydrolysis followed by ¹H NMR and GPC analysis of the degradation products confirmed cleavage of polyester segments and yielded low-molecular-weight fragments with M_n = 1370 g mol⁻¹ and narrow dispersity (Đ = 1.035), providing additional information on the architecture of the vinyl-polymerized segments. Increasing CPDT concentration resulted in lower molecular weights and narrower molecular weight distributions of the soluble copolymer fractions. TEM analysis demonstrated broader domain size distributions and increased morphological heterogeneity in RAFT-modified samples, accompanied by an increase in swelling degree. Thermogravimetric analysis showed that RAFT-modified systems undergo multi-stage thermal degradation with the appearance of an additional low-temperature stage associated with thermolabile fragments. TG–MS revealed earlier evolution of CO₂ and oxygen-containing species and changes in the distribution of volatile products. DFT calculations indicated a decrease in the HOMO–LUMO energy gap and suggested the participation of RAFT-derived fragments in the energetic characteristics of decarboxylation processes. Isoconversional and nonlinear kinetic analyses demonstrated increased kinetic heterogeneity for branched copolymer s synthesized at elevated CPDT concentrations, whereas cross-linked systems exhibited more uniform degradation behavior. The combined experimental and theoretical results demonstrate that RAFT polymerization provides an effective route for tuning the macromolecular architecture, morphology, and thermal degradation pathways of p-PGM:AA copolymers. Full article

This article introduces explanatory entitlement as an epistemic category: the inferential right to deploy a construct as a basis for causal inference in a given domain. Drawing on Woodward’s interventionist account and Cartwright’s analysis of causal portability the article argues that this entitlement is conferred by demonstrated invariance and does not transfer automatically across levels or domains. When constructs are projected beyond their invariance conditions without bridging support, they undergo conceptual inflation: retention of explanatory authority without the evidential conditions that license it. The article formalizes this failure, distinguishes it from seven neighboring frameworks, and proposes a diagnostic structure. Full article

Determining the internal oceanic gravity corresponds to solving for the Earth’s internal gravitational potential, for which traditional geodetic theories (Stokes’ and Molodenskii’s theorems) are not directly applicable. To overcome this constraint, the concept of “seawater layer” is introduced. The first original global three-dimensional internal oceanic gravity field model WHU-IOGM was constructed using four key methods: (1) sliding-window Newtonian integration, (2) multi-node parallel computing on a high-performance supercomputing platform, (3) an ellipsoidal harmonic expansion algorithm with improved convergence properties, and (4) a spherical-to-ellipsoidal harmonic coefficient transformation algorithm. Compared with underwater gravity measurement continuation, the “seawater layer” method has more advantages in theoretical rigor and accuracy. The theoretical systematic error of WHU-IOGM was evaluated, with the global RMSE of about 6.28 mGal and a mean error of about 0.19 mGal. Based on the WOA18 deep stratification framework, we added a grid layer corresponding to the actual seabed depth, expanding the original 102-layer system to a total of 103 layers. The inclusion enhances the model’s conformity with actual seabed topography. This structural refinement enables a more accurate and detailed representation of the ocean’s internal gravity field, providing a theoretical basis and algorithmic models for underwater gravity measurement and underwater navigation. Full article

A recurring challenge in the development of information systems (ISs) across complex organizational domains is the lack of integration and alignment between strategic, tactical, and operational levels, resulting in methodological fragmentation that constrains traceability, innovation, and organizational value generation. This study proposes and applies to the Integrated Innovation Framework for Information System Development (IIF-ISD) to overcome this gap. The research was structured through a systematic literature review, following the PRISMA and ROSES protocols, and validated through an exploratory single-case study involving the development of an IS supporting the Selo Casa Azul (SCA) environmental certification process in a Brazilian construction company, a context chosen for its multi-level organizational complexity and ESG compliance requirements, representative of broader certification IS development challenges. The framework integrates DSRM, agile methodologies, Design Thinking, and Lean Startup through three governing principles—Hierarchical Embedding, Functional Complementarity, and Traceability by Design—achieving cross-level alignment between strategic objectives, tactical performance monitoring, and operational execution. Empirical evaluation (n = 9; 14 weeks) yielded SUS scores of 76.8–82.1/100, a 76% reduction in data entry error rates, and a 78% stakeholder engagement rate, providing initial support for the framework’s practical effectiveness. Full article

We present state-of-the-art kinetic theory determination of the neutron abundance available for the Big-Bang nucleosynthesis (BBN). This paper is motivated by the study of the neutron lifespan measured in the laboratory and the unknown strength of weak interactions coupling constant $G_{\mathrm{F}}$ at finite temperature in the primordial Universe. We draw attention to the relevant dependence of $G_{\mathrm{F}}$ on the symmetry breaking Weinberg angle $s_{\mathrm{W}}^2$, which is a free parameter in the standard model of particle physics. We establish how the value of $s_{\mathrm{W}}^2$ by way of $G_{\mathrm{F}}$ modification influences the neutron abundance available for BBN and neutron lifetime. Full article

We develop a quantitative Hardy scale for mixed quadratic energies combining the classical Dirichlet form and a fractional Dirichlet form, ${\mathcal{E}}_{\lambda ,s}\left(u\right)={\int }_{{\mathbb{R}}^n}{|\nabla u\left(x\right)|}^2\mathrm{d}x+\lambda {\int }_{{\mathbb{R}}^n}{\left|{(-\Delta )}^{s/2}u\left(x\right)\right|}^2\mathrm{d}x,0<s<1,\lambda >0.$ Here, the word scale denotes a parameterized family with a fixed interpolation variable, explicit constants, and the scaling exponent forced by the coexistence of the orders 2 and $2s$. For $n\ge 3$, we prove weighted $L^2$ inequalities indexed by $\gamma \in [s,1]$, which control ${\left|x\right|}^{-2\gamma }$ by ${\mathcal{E}}_{\lambda ,s}$ with the factor ${\lambda }^{-\theta }$, where $\theta =(1-\gamma )/(1-s)$. In dimension $n=2$, the local endpoint is replaced by the logarithmic Hardy weight and gives a mixed log–power family governed by the same parameter. The novelty lies in organizing the endpoint Hardy estimates into a $\lambda$-adapted form suitable for mixed-order operators, with explicit constants, scaling-level optimality of the $\lambda$ exponent, a planar endpoint formulation, and directly usable singular-potential thresholds. The operator consequences are stated at the level of form boundedness, coercivity, spectral lower bounds on bounded domains, semigroup generation, and variational well-posedness; they are presented as consequences of the Hardy scale rather than as a separate spectral theory. Full article

Background: Mechanical complications remain a concern after vertebral body replacement (VBR), especially during rehabilitation. Yet exercise prescription is often guided by body posture or single loading measures. This study characterized mechanical demands during rehabilitation exercises after VBR and examined the effects of posture and postoperative time. Methods: Telemetric in vivo load data from instrumented VBRs in the OrthoLoad database were analyzed. A total of 119 trials across 21 exercises, performed in supine, prone, seated, and standing positions, were collected from five patients over 0.1–63 postoperative months. Mechanical demand was quantified across six biomechanical domains and integrated into a composite SafetyIndex. Posture- and time-related effects were assessed using linear mixed-effects models. Worst-case demand was defined as the 95th percentile of SafetyIndex values. Results: SafetyIndex showed a right-skewed distribution (median 8.5, IQR 3.7–14.1), with marked inter-exercise variability. Composite SafetyIndex did not differ between postures (all p > 0.13). However, posture-dependent effects emerged at the domain level: peak shear ratio was greater in prone than in sitting, standing, and supine positions (all p < 0.05); peak force was greater in standing than prone (p = 0.007 and p = 0.013 in unadjusted and adjusted models); and peak resultant moment was smaller in supine than prone (p = 0.036 and p = 0.046). Postoperative time was positively associated with peak force (β = +0.40 %BW/month, p = 0.042), peak resultant moment (β = +0.025 Nm/month, p < 0.001), and SafetyIndex (β = +0.25/month, p = 0.011), but not peak shear ratio (p = 0.879). Worst-case SafetyIndex_P95 values ranged from 0.6 to 85.0, with stable ranking across percentile thresholds (Spearman’s ρ = 0.995–0.997). Conclusions: Mechanical demand after VBR is task-specific and domain-dependent and cannot be inferred from posture alone. Axial and bending-related components increased over postoperative time, whereas shear-related loading remained task-dependent. Full article

Municipal organic waste management remains a major challenge for sustainable urban development, particularly in regions requiring decentralized treatment alternatives that reduce landfill dependency and promote circular resource recovery. This study compared Takakura composting and vermicomposting for the stabilization of municipal organic waste under decentralized operational conditions in the Ecuadorian Amazon and developed a Composite Circular Resource Recovery and Process Performance Index (CRRPPI) to evaluate resource recovery efficiency. Municipal organic waste was treated through Takakura composting, vermicomposting, and uncontrolled decomposition (control). Operational performance was assessed using material conversion efficiency, process productivity, nutrient recovery efficiency, nutrient productivity, and final physicochemical characteristics. These indicators were integrated into the CRRPPI framework to provide a multidimensional assessment of circular resource recovery performance. Takakura composting showed the highest operational efficiency, achieving material conversion efficiencies of up to 0.80, process productivity values of 1.23 kg day⁻¹, and superior nutrient recovery efficiencies for nitrogen (0.835), phosphorus (0.730), and potassium (0.880). The highest CRRPPI values were obtained for Takakura treatments (0.835–0.842), while vermicomposting showed intermediate performance, and the control treatment presented the lowest resource recovery efficiency (0.216). Sensitivity analysis confirmed ranking stability under ±20% weighting variations, and ANOVA followed by Tukey’s HSD test identified significant differences among treatments (p < 0.05). The results indicate that Takakura composting is an effective strategy for decentralized municipal organic waste valorization and nutrient recirculation. Furthermore, the proposed CRRPPI provides a practical exploratory framework for integrated evaluation of biological stabilization technologies by simultaneously considering operational performance and circular resource recovery. Full article

Land use planning in the Black Soil Region of Northeast China must be sustainable, taking into account food security, water use, GHG emissions, and economic returns. Current crop suitability mapping and single-objective optimization studies tend to analyze crop occurrence, crop structure, and spatial allocation independently, which is of little value in spatial planning. In this study, a three-stage integrated approach is proposed, involving deep learning crop occurrence mapping, multi-objective crop structure optimization, and suitability-guided spatial allocation. During Stage I, a lightweight U-Net semantic segmentation model, BlackSoilCropNet, is developed to provide per-pixel occurrence probabilities of rice, maize, soybean, and other types of crops based on Sentinel-2 time series and auxiliary environmental predictors. In stage II, NSGA II will optimize the area structure of the crops and reduce water consumption and GHG emissions with the maximum profit under the constraints of the cropland, water, and production. Selected Pareto optimal solutions are transformed to crop allocation maps and transition hotspot outputs in Stage III. The framework resulted in three viable planning options. The economic priority scenario resulted in the highest profit (USD 27.9 billion), with higher water consumption and emissions. The environmental-priority scenario resulted in a reduction in water use to 118.2 × 10⁹ m³ and emissions to 50.9 MtCO₂e, but at the cost of lower production and profits. There was a balance between economic stability and an improved environment in the balanced scenario. The framework provides a reproducible, geospatial decision support approach for sustainable farming planning and black soil conservation overall. Full article

The proposed approach decomposes in a special way the original two-input linear time-optimal control problem into two single-input linear time-optimal problems whose optimal solutions are subsequently recombined. A lemma and a theorem establish conditions under which the recombined control vector is a candidate for the optimal solution and provide a simple criterion, based on the Pontryagin Maximum Principle, to determine whether the obtained control is truly optimal or only near optimal. The method is illustrated on a modified canonical double integrator system with two independent inputs. The resulting control system preserves the bang-bang structure and switching sequence of the true optimal solution, while providing a transition time that exceeds the optimal value by only 0.55%. The proposed method offers a basis for developing a technique regarding the multi-input linear time-optimal control problems. Full article

The Yasuní National Park in Ecuador’s Amazon, one of Earth’s most biodiverse regions, faces unprecedented threats from oil extraction and increasing risks to Kichwa communities. This paper provides a baseline analysis of off-the-grid hydrocarbon extraction affecting ecosystems and communities living within Oil Blocks 12 and 43. Our aim is to integrate analysis of per- and polyfluoroalkyl substances (PFAS) and total petroleum hydrocarbons (TPH) to better understand the impacts of oil-extractive contamination at off-the-grid sites in sensitive Amazonian ecosystems. To achieve that, we center the Yasuní Park and Kichwa communities as a case study. Despite Kichwa environmental concerns about contamination, conventional total hydrocarbon testing has failed to detect elevated levels due to hydrocarbon degradation, necessitating testing for other contaminants associated with extractive activities, such as PFAS, a forever chemical commonly used in drilling fluids, and other contaminants from petroleum transportation via pipelines. This research was conducted at the request of and with the participation of Kichwa residents, who needed to understand the nature of contaminants in their environment. Two participatory mapping exercises were conducted in Oil Block 12 to pinpoint 16 sampling locations, given the block’s long history of contamination. In Oil Block 43, where extraction is more recent, we sampled 5 sites where community members had observed contamination in the last year. TPH and PFAS analyses were performed using EPA methods 1633 and 1664. Results revealed 7 PFAS compounds across Oil Blocks, 11 TPH compounds in Oil Block 12, and overlap between TPH and PFAS at 6 sampling locations. Contamination was detected near community housing, food gardens, and swamped forest, which is concerning because communities rely on traditional subsistence activities, including forest gathering, fishing, and gardens for survival. This is the first environmental assessment to examine the combined presence of hydrocarbons and PFAS in the Yasuní Park and the Ecuadorian Amazon, providing communities with empirical evidence of environmental contamination. Full article