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Physical, Chemical, and Mechanical Characterization of Okra (Abelmoschus Esculentus) Fibers from the Littoral Region of Cameroon for Composite
Ninon Rosine Nkoulou Nkoulou
,Solange Bassok
,Paul Etouke Owoundi
,Salomé Essiane Ndjakomo
,Jean Mbihi
Okra (Abelmoschus esculentus) stems constitute an abundant lignocellulosic biomass with significant potential for sustainable composite reinforcement. In this study, okra fibers were extracted using biological retting, alkaline treatment (1-7.5 wt% NaOH), and combined extraction processes. The influence of extraction conditions on the physicochemical, mechanical, thermal, and structural properties of the fibers was investigated. FTIR analysis revealed the progressive removal of hemicellulose and lignin after alkaline treatment, while XRD results showed an increase in cellulose crystallinity. Optical microscopy observations revealed progressive fiber separation and cleaner surface morphology after alkaline treatment. Fiber density increased with NaOH concentration, whereas water absorption and moisture regain decreased due to the reduction of hydrophilic amorphous components. Mechanical properties, particularly tensile strength and Young’s modulus, improved under moderate treatment conditions but decreased under severe alkaline conditions because of partial cellulose degradation. The optimal treatment condition (1 wt% NaOH for 60 min) provided the best balance between delignification, structural preservation, and mechanical performance. These results demonstrate that okra fibers are promising lightweight reinforcements for sustainable bio-composite and technical textile applications.
Okra (Abelmoschus esculentus) stems constitute an abundant lignocellulosic biomass with significant potential for sustainable composite reinforcement. In this study, okra fibers were extracted using biological retting, alkaline treatment (1-7.5 wt% NaOH), and combined extraction processes. The influence of extraction conditions on the physicochemical, mechanical, thermal, and structural properties of the fibers was investigated. FTIR analysis revealed the progressive removal of hemicellulose and lignin after alkaline treatment, while XRD results showed an increase in cellulose crystallinity. Optical microscopy observations revealed progressive fiber separation and cleaner surface morphology after alkaline treatment. Fiber density increased with NaOH concentration, whereas water absorption and moisture regain decreased due to the reduction of hydrophilic amorphous components. Mechanical properties, particularly tensile strength and Young’s modulus, improved under moderate treatment conditions but decreased under severe alkaline conditions because of partial cellulose degradation. The optimal treatment condition (1 wt% NaOH for 60 min) provided the best balance between delignification, structural preservation, and mechanical performance. These results demonstrate that okra fibers are promising lightweight reinforcements for sustainable bio-composite and technical textile applications.
Posted: 11 May 2026
Adolescent Suicide During the COVID-19 Pandemic: Bullying Dynamics, Risk Factors, and Prevention Strategies: An Updated Narrative Review
José Miguel Pérez-Jiménez
,Andrea Feria Dávila
Posted: 11 May 2026
Constructing Brain-Inspired Sparse Topologies for Energy-Efficient ANN-to-SNN Conversion via Cannistraci-Hebb Training
Kangyou Bao
,Wenqi Gu
,Jiaqing Lyu
,Xizheng Deng
,Carlo Vittorio Cannistraci
Posted: 11 May 2026
VOCs Emission Idle Rates and Differentiated Control Strategies for Chemical Enterprises Under China’s Discharge Permit System: Evidence from Jiangsu Province
Xuemei Liu
,Xiufang Zhu
,Jianfeng Pang
,Xijun Ma
Posted: 11 May 2026
Frequency-Informed Vision and Learning: A Survey
Lei Zhang
,Tianyu Zhang
,Xiaowei Fu
,Fuxiang Huang
,Wenguan Wang
,David Zhang
Posted: 11 May 2026
Beyond Entropy Magnitude: Directional Symmetry Breaking, Temporal Memory, and Entropy Production Rate as Early Warning Signals in Complex System Collapse
Hikmat Karimov
,Rahid Zahid Alekberli
Posted: 11 May 2026
Anxiety Trait as a Potential Endophenotype in First-Degree Relatives of Bipolar Disorder Type I Patients
Inés Figuereo
,Esther Patró
,Lourdes Villegas
,Touba Borji
,Maria Mata
,Yolanda Mata
,Noèlia Ortuño
,Jesus Cobo
Posted: 11 May 2026
A Study on Dynamic Dimming Strategies for Tunnel Lighting Based on the PPO Algorithm
Jiangrui Huang
,Zhuozhuo Bai
,Zhi Chen
,Bailiang Lu
Posted: 11 May 2026
A Simpson–Type Decomposition of the Euler–Mascheroni Constant
Kazuharu Misawa
Posted: 11 May 2026
Research on Tunnel Traffic Flow Prediction Model Based on Graph Neural Networks
Yang Yang
,Zhuozhuo Bai
,Zhi Chen
,Xiaoxue Cao
,Zhitao Chen
,Guo Chen
Posted: 11 May 2026
A Three-Dimensional Laser Scanning-Based Method for Dimensional Inspection of Large-Scale High-Speed Railway Precast Box Girders
Zhiguo Zhang
,Shihao Dou
,Shaopeng Zhang
,Kang Chen
Posted: 11 May 2026
Finite-Capacity Corona Governance: Body Fluids as Biological Identity-Assignment Systems for Nanoscale Interfaces
Cheng Wang
Posted: 11 May 2026
Intervention-Based Time Series Causal Discovery via Simulator-Generated Interventional Distributions
Tsuyoshi Okita
In many scientific domains, physics-based simulators—programs that compute system behaviour from governing equations, such as density functional theory for materials or fluid dynamics solvers—encode causal mechanisms and can predict system behaviour under hypothetical interventions. Machine learning extracts patterns from observational time series at scale, but those patterns reflect statistical associations ($P(Y \mid X)$), not causal effects ($P(Y \mid \mathrm{do}(X))$): in the presence of latent confounders, the structural VAR is provably non-identifiable from observational data alone (Fact 3.3), and no amount of statistical sophistication can substitute for genuine interventional data. Bridging these two traditions has so far been limited to using simulators for prediction; no existing framework uses them for causal structure discovery in time series. We propose SVAR-FM (Structural VAR with Flow Matching), a framework that treats a physical simulator as a mechanical realization of Pearl's $\mathrm{do}(\cdot)$ operator. Clamping a variable in the simulator physically severs confounding paths, producing interventional data by construction rather than by statistical argument. Conditional Flow Matching then parameterizes the interventional conditionals, enabling nonlinear mechanism learning. This yields four results. (1) The full structural VAR—contemporaneous and lagged edges jointly—becomes identifiable under a coverage condition on the simulator-clampable variables, verifiable a priori from domain knowledge alone (Theorem 4.1). The argument is intrinsic to the time series setting and has no i.i.d.\ counterpart. (2) An end-to-end error bound $|\hat{e}_{i\to j} - e^{*}_{i\to j}| \le O(M^{-1/2}) + O(\delta_{\mathcal{S}}) + O(\varepsilon_{\mathrm{FM}})$ (Theorem 5.2) cleanly separates Monte Carlo sampling, simulator fidelity $\delta_{\mathcal{S}}$, and Flow Matching approximation. A sharp consequence is a sign-flip regime (Corollary 5.5): when $\delta_{\mathcal{S}}$ exceeds a threshold set by the signal magnitude, the estimated causal effect reverses sign—a prediction that the prevailing forward-prediction view of simulators cannot produce. (3) The CausalSim benchmark confirms that SVAR-FM recovers the correct causal sign across four scientific domains (macroeconomics, iabetes, cosmic ray physics, and battery degradation) where observational methods produce sign-reversed estimates due to confounding. (4) A case study in ultrafast laser physics tests the sign-flip prediction by physically varying $\delta_{\mathcal{S}}$ through the accuracy level of a first-principles quantum solver: the low-accuracy setting produces a sign-reversed estimate, while the high-accuracy setting recovers the correct positive slope ($R^2 = 0.983$, zero bias relative to ground truth), providing the first experimental demonstration of a simulator-fidelity-dominated failure mode in causal discovery.
In many scientific domains, physics-based simulators—programs that compute system behaviour from governing equations, such as density functional theory for materials or fluid dynamics solvers—encode causal mechanisms and can predict system behaviour under hypothetical interventions. Machine learning extracts patterns from observational time series at scale, but those patterns reflect statistical associations ($P(Y \mid X)$), not causal effects ($P(Y \mid \mathrm{do}(X))$): in the presence of latent confounders, the structural VAR is provably non-identifiable from observational data alone (Fact 3.3), and no amount of statistical sophistication can substitute for genuine interventional data. Bridging these two traditions has so far been limited to using simulators for prediction; no existing framework uses them for causal structure discovery in time series. We propose SVAR-FM (Structural VAR with Flow Matching), a framework that treats a physical simulator as a mechanical realization of Pearl's $\mathrm{do}(\cdot)$ operator. Clamping a variable in the simulator physically severs confounding paths, producing interventional data by construction rather than by statistical argument. Conditional Flow Matching then parameterizes the interventional conditionals, enabling nonlinear mechanism learning. This yields four results. (1) The full structural VAR—contemporaneous and lagged edges jointly—becomes identifiable under a coverage condition on the simulator-clampable variables, verifiable a priori from domain knowledge alone (Theorem 4.1). The argument is intrinsic to the time series setting and has no i.i.d.\ counterpart. (2) An end-to-end error bound $|\hat{e}_{i\to j} - e^{*}_{i\to j}| \le O(M^{-1/2}) + O(\delta_{\mathcal{S}}) + O(\varepsilon_{\mathrm{FM}})$ (Theorem 5.2) cleanly separates Monte Carlo sampling, simulator fidelity $\delta_{\mathcal{S}}$, and Flow Matching approximation. A sharp consequence is a sign-flip regime (Corollary 5.5): when $\delta_{\mathcal{S}}$ exceeds a threshold set by the signal magnitude, the estimated causal effect reverses sign—a prediction that the prevailing forward-prediction view of simulators cannot produce. (3) The CausalSim benchmark confirms that SVAR-FM recovers the correct causal sign across four scientific domains (macroeconomics, iabetes, cosmic ray physics, and battery degradation) where observational methods produce sign-reversed estimates due to confounding. (4) A case study in ultrafast laser physics tests the sign-flip prediction by physically varying $\delta_{\mathcal{S}}$ through the accuracy level of a first-principles quantum solver: the low-accuracy setting produces a sign-reversed estimate, while the high-accuracy setting recovers the correct positive slope ($R^2 = 0.983$, zero bias relative to ground truth), providing the first experimental demonstration of a simulator-fidelity-dominated failure mode in causal discovery.
Posted: 11 May 2026
Remifentanil: Drug of Choice for Intubation in Neonates?
Lara Garabedian
,Gerbrich E van den Bosch
,Sophie Vanhaesebrouck
,Karel Allegaert
Posted: 11 May 2026
Preparation and Application of a Novel Anti-Contamination Agent for Use in Drilling Fluids
Song Zhang
,Xi Guan
,Fei Deng
,Xiaowei Cheng
Posted: 11 May 2026
Protein Phosphatase 5 Serves as a Co-Chaperone to Regulate the Accumulation of Immune Receptor SUMM2
Xingchuan Huang
,Yanan Liu
,Yuelin Zhang
Posted: 11 May 2026
Optimizing Athletic Performance: A Systems Framework for Adaptive Training, Load Management, and Decision-Making
Dan Cristian Mănescu
,Cristina Filip
,Cristina Ionela Nae
,Rela Valentina Ciomag
Posted: 11 May 2026
Attitudes, Motivation, and Predictors of Influenza Vaccination Uptake Among Primary Healthcare Professionals in Greece
Kougioumtzoglou S. Isidoros
,Kostaki Evangelia-Georgia
,Soulis George
,Selekos Nikos
,Koulouvari Areti-Dmitra
,Kouvelas Dimitrios
,Maniadakis Nikos
,Lagiou Areti
Posted: 11 May 2026
An Exploratory Circular Economy Management Framework for Plastic Recycling SMEs: A Process Reengineering Approach for Sustainability
Oscar Gildardo Hernández Alomía
,Alicia Cristina Silva Calpa
Posted: 11 May 2026
Impact of the Menstrual Cycle on Continuous Glucose Monitoring - Derived Glycemic Parameters in Adolescent Girls With Type 1 Diabetes: A Retrospective Observational Study
Lavinia La Grasta Sabolić
,Ana Kovačević
,Marija Požgaj Šepec
,Anita Špehar Uroić
,Ana Smolić
,Bernardica Valent Morić
Posted: 11 May 2026
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