Search Results (107)

Pineapple waste is an underexplored source for producing nanocomposites, from which nanocellulose, namely cellulose nanocrystals (CNCs) or cellulose nanofibers (CNFs), can be produced. This review summarizes extraction methods from different pineapple residues (leaves, crown leaves, stem, peel, pulp, and pomace), covering top-down processes (hydrolysis, oxidation, carboxymethylation, and mechanical fibrillation) and bottom-up strategies (ionic liquids and deep eutectic solvents). The review examines the influence of the morphology and crystallinity of nanocellulose on the functional performance of the nanocomposites. Strategies for processing pineapple-derived nanocellulose composites are analyzed by technique (solution casting, film stacking, and melt blending/extrusion) and polymer matrices (starch, PVA, chitosan, PLA, PHBV, PBAT, proteins, and polysaccharides), including typical loading levels for most polymer-reinforced systems (0.5–5 wt.%), while higher levels (15–50 wt.%) are used in particular cases such as PVA, CMC, and cellulosic matrices. The impact on mechanical strength, barrier behavior, UV shielding, and optical properties is summarized, along with reports of self-reinforced and hybrid cellulose-derived matrices. A benchmarking section was prepared to show nanocellulose loading ranges, trends in properties, and processing-relevant information categorized by type of matrix. Finally, the review describes the potential roles of pineapple waste within a bioeconomy context and identifies some extraction by-products that could be incorporated into diverse value chains. Full article

The high material waste, long execution times, and lack of adoption of technological solutions hinder the construction process in the building sector. In response, this project proposes the development and validation of parametric digital tools to optimize the design and CNC fabrication of WikiHouse prototypes, an open-source modular system that enables precise assemblies without the need for additional metal joints. The main objective is to optimize the architectural design process through tools such as Grasshopper and Python, increasing precision, reducing material waste, and shortening the manufacturing times of CNC components for WikiHouse. The results include drastic time reductions when shifting from manual workflows to CAD–CAM parameterized workflows, with processing times of approximately 1 min (≈0:32–1:16) compared to 63–109 min using manual methods. This study demonstrates that parameterization—rather than robotization—is a realistic pathway to transfer open systems like WikiHouse to low-tech contexts: it reduces preparation times to minutes, cuts waste, and decreases variability among operators. Full article

This study demonstrates the valorization of orange peel waste as a sustainable feedstock for the production of cellulose nanocrystals (CNCs). Compositional analysis revealed a cellulose content up to 10.0% in the raw material. After performing the alkaline/peroxide treatment, CNCs were isolated via acid hydrolysis. Different inorganic acids were compared, namely sulfuric, phosphoric, and hydrochloric acids at low molar concentrations. The resulting CNCs showed distinct morphological and physicochemical properties, with sulfuric acid treatment yielding the highest crystallinity index (TCI) of 0.86 under conditions of 3.0 mol/L, 80 °C, and 225 min. Additionally, the presence of sulfate or phosphate groups significantly influenced the thermal degradation behavior and the inorganic residue content in the obtained CNCs. Finally, the CNCs were successfully tested as co-initiator for lactide ring-opening polymerization. The results show that the molecular weights of the resulting polylactide varied depending on the CNC dispersion. This work supports the use of orange peel waste as a bio-source for CNC production and their potential application as a co-initiator in the synthesis of polyesters. Full article

Cellulose nanocrystals (CNCs), derived from renewable cellulose sources, have emerged as a versatile class of nanomaterial with exceptional mechanical strength, tuneable surface chemistry and inherent biocompatibility. In the scenario of contemporary commercial hydrogel products, which are expensive and rely on synthetic materials, the sustainable origin and unique physicochemical properties have positioned CNCs as promising sustainable functional building blocks for next-generation hydrogels in biomedical applications. Over the past decade, CNC-based hydrogels have gained momentum as soft biomaterials capable of interacting with diverse tissue types, predominantly demonstrated through in vitro cell line studies. This review critically examines the current landscape of research on biomedical applications of CNC-based hydrogels, focusing on their biomedical utility across 22 systematically screened studies. It revealed applications spanning around bone and cartilage tissue engineering, wound healing, medical implants and sensors, and drug delivery. We highlight the predominance of microcrystalline cellulose as the CNC source and sulfuric acid hydrolysis as the preferred extraction method, with several studies incorporating surface modifications to enhance functionality. Despite growing interest, there remains a lack of data for transitioning towards human clinical studies and commercialisation. Hence, this review highlights the pressing need for scalable, sustainable, and affordable CNC-based hydrogel systems that can democratise access to advanced biomedical technologies. Full article

This work presents the design and implementation of an automated, digital, and modular system to address a real-world industrial challenge: the automation and optimization of production schedules for Computer Numerical Control (CNC) machines in a factory in Portugal. The goal is to replicate and enhance the existing manual scheduling process by integrating multiple data sources and formulating a general Mixed-Integer Linear Programming (MILP) model with constraints. This model can be solved using MILP optimization methods to produce efficient scheduling solutions that minimize machine downtime, reduce tool change frequency, and lower operator workload. The proposed system is implemented using open-source Python abstraction interfaces (Python-MIP), employing state-of-the-art of MILP optimization solvers such as CBC and HiGHS for solution validation. The system is designed to accommodate a wide range of constraints and operational factors, which can be switched on or off as needed, thereby enhancing its flexibility and decision-support capabilities. Additionally, a user-friendly graphical application is developed to facilitate the input of specific scheduling data and constraints, enabling flexible and efficient formulation of diverse scheduling scenarios. The proposed system is validated through multiple case studies, demonstrating its effectiveness in optimizing industrial CNC scheduling tasks and providing a scalable, practical tool for real-world factory operations. Full article

The overuse of nonrenewable resources has motivated intensive research and the development of new types of green bio-based and degradable feedstocks derived from natural sources, such as cellulose derivates, also in nanoforms. The inclusion of such nanoparticles in bio-based polymers with the aim of providing reinforcement is a trend, which, when associated with the incorporation active compounds, creates active packaging suitable for the packaging of highly perishable food, thus contributing to the product’s shelf-life extension. Chitosan (Ch)/sage essential oil (SEO) bionanocomposite reinforced with nanocrystalline cellulose (CNC) was cast as active packaging for the preservation of fresh poultry meat. Meat samples were wrapped in different bioplastics (pristine chitosan, chitosan with commercial CNC, chitosan with CNC obtained from three different lignocellulosic crops, giant reed (G), kenaf (K), and miscanthus (M), chitosan with SEO, and chitosan with SEO and CNC), while unwrapped samples were tested as the control. Periodically, samples were evaluated in terms of their physicochemical properties and microbial growth. Additionally, bionanocomposites were also evaluated in terms of their in situ antimicrobial properties, as well as migration toward food simulants. Meat samples protected with bionanocomposites showed lower levels of microbiological growth (2–3 logs lower than control) and lipid oxidation (20–30% lower than in control), over time. This was attributed to the intrinsic antimicrobial capacity of chitosan and the high oxygen barrier properties of the films resulting from the CNC inclusion. The SEO incorporation did not significantly improve the material’s antimicrobial and antioxidant activity yet interfered directly with the meat’s color as it migrated to its surface. In the in vitro assays, all bionanocomposites demonstrated good antimicrobial activity against B. cereus (reduction of ~8.2 log) and Salmonella Choleraesuis (reduction of ~5–6 log). Through the in vitro migration assay, it was verified that the SEO release rate of phenolic compounds to ethanol 50% (dairy products simulate) was higher than to ethanol 95% (fatty food simulate). Furthermore, these migration tests proved that nanocellulose was capable of delaying SEO migration, thus reducing the negative effect on the meat’s color and the pro-oxidant activity recorded in TBARS. It was concluded that the tested chitosan/nanocellulose bionanocomposites increased the shelf life of fresh poultry meat. Full article

Cellulose nanocrystals (CNCs) have attracted growing interest in optics and electronics, extending beyond their traditional applications. They are considered key materials due to their fast computing, sensing adhesion, and emission of circularly polarized luminescence with high dissymmetry factors. This interest arises from their unique chemical structure, which gives rise to structural color, a chiral nematic phase, and high mechanical strength. In this perspective, we first introduce the definition, sources, and fundamental properties of CNCs to explain the basis for their unique and effective use in optics and electronics. Next, we review recent research on the application of CNCs in these fields. We then analyze the current limitations that hinder further advancement. Finally, we offer our own perspective on future directions for the CNC-enabled advanced optics and electronics. Full article

This review delves into environmentally conscious sustainable packaging materials, focusing on biodegradable polymers and innovative surface modification methodologies. Synthetic plastics have revolutionized various industries due to their physical attributes and affordability, particularly in packaging applications. Nonetheless, the substantial volume of plastic waste, especially from non-biodegradable sources, has provoked heightened environmental apprehensions. Notably, polymers derived from natural sources, such as cellulose, are classified as biopolymers and esteemed for their ecological benevolence. Among these, cellulose and its derivatives stand out as renewable and abundant substances, holding promise for sustainable packaging solutions. Nano-sized cellulose fibers’ incorporation into biodegradable films garners interest due to their remarkable surface area, robust mechanical strength, and other commendable properties. Surface modification techniques, such as a polydopamine (PDA) coating, have been explored to improve the dispersion, interfacial compatibility, and mechanical performance of cellulose nanocrystals (CNC) when incorporated into biodegradable polymer films. In this sense, PDA, derived from mussel proteins’ dopamine component, displays exceptional adhesion to diverse surfaces and has been extensively scrutinized for its distinctive attributes. Therefore, the core focus of this review was to approach ecologically friendly packaging materials, specifically investigating the synergy between CNC and PDA. The unparalleled adhesive characteristics of PDA serve as a catalyst for enhancing CNC, thereby elevating the performance of biodegradable polymers with potential implications across various domains. Full article

In this study, cellulose nanocrystals (CNCs) were successfully isolated through the acid hydrolysis of freeze-dried and oven-dried bacterial nanocellulose (BNC) recovered from the floating pellicle generated during Kombucha tea production. The influence of the BNC drying method and its concentration on the yield and main characteristics of the CNCs obtained were studied. Additionally, selected CNC suspensions at various pH levels were subjected to freeze-drying and oven-drying, followed by an assessment of their dispersibility in water after undergoing different mechanical treatments. Results demonstrate the potential of utilizing byproducts from the expanding Kombucha industry as an alternative cellulose source for CNC production. Furthermore, the drying method applied to the BNC and its initial concentration in the hydrolysis medium were found to significantly impact the properties of the resulting CNCs, which exhibited diverse size distributions and Z-potential values. Finally, the redispersion studies highlighted the beneficial effect of drying CNCs from neutral and alkaline dispersions, as well as the requirement of ultrasound treatments to achieve the proper dispersion of dehydrated CNC powders. Full article

Nitrogen (N) is critical for maize (Zea mays L.) growth and yield, necessitating precise estimation of canopy nitrogen concentration (CNC) to optimize fertilization strategies. Remote sensing technologies, such as proximal hyperspectral sensors and unmanned aerial vehicle (UAV)-based multispectral imaging, offer promising solutions for non-destructive CNC monitoring. This study evaluates the effectiveness of proximal hyperspectral sensor and UAV-based multispectral data integration in estimating CNC for spring maize during key growth stages (from the 11th leaf stage, V11, to the Silking stage, R1). Field experiments were conducted to collect multispectral data (20 vegetation indices [MVI] and 24 texture indices [MTI]), hyperspectral data (24 vegetation indices [HVI] and 20 characteristic indices [HCI]), alongside laboratory analysis of 120 CNC samples. The Boruta algorithm identified important features from integrated datasets, followed by correlation analysis between these features and CNC and Random Forest (RF)-based modeling, with SHAP (SHapley Additive exPlanations) values interpreting feature contributions. Results demonstrated the UAV-based multispectral model achieved high accuracy and Computational Efficiency (CE) (R² = 0.879, RMSE = 0.212, CE = 2.075), outperforming the hyperspectral HVI-HCI model (R² = 0.832, RMSE = 0.250, CE =2.080). Integrating multispectral and hyperspectral features yields a high-precision model for CNC model estimation (R² = 0.903, RMSE = 0.190), outperforming standalone multispectral and hyperspectral models by 2.73% and 8.53%, respectively. However, the CE of the integrated model decreased by 1.93% and 1.68%, respectively. Key features included multispectral red-edge indices (NREI, NDRE, CI) and texture parameters (R1m), alongside hyperspectral indices (SR, PRI) and spectral parameters (SDy, Rg) exhibited varying directional impacts on CNC estimation using RF. Together, these findings highlight that the Boruta–RF–SHAP strategy demonstrates the synergistic value of integrating multi-source data from UAV-based multispectral and proximal hyperspectral sensing data for enhancing precise nitrogen management in maize cultivation. Full article

Nanocellulose, including cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and bacterial nanocellulose (BNC), represents a promising class of bio-based nanomaterials derived from natural sources. These materials, derived from plant-based cellulose, are characterized by exceptional mechanical strength, high surface area, biodegradability, and the ability to form stable nanoparticle networks, making them suitable for use in composites, biomedicine, electronics, and many other fields. In this review, we present the latest advancements in the production of nanocellulose, including preparation technologies and methods for chemical and physical modifications to enhance the performance of these materials. We also discuss various applications, such as its use in nanocomposites, sustainable packaging materials, flexible electronic devices, and as a support for biological media. Additionally, the challenges and opportunities related to the scalability of production and their integration into industries with growing economic and ecological demands are explored. The review provides a comprehensive overview of the potential of nanocellulose, highlighting its importance in the context of emerging technologies and sustainability. Full article

This study explores how varying chlorogenic acid levels (low—yellowish, Y; high—greenish, G) in sunflower proteins (SFs) affect the properties of eugenol-loaded oil-in-water emulsions and the resulting films, while examining the interaction of cellulose nanoparticles (from commercial (CNC) and banana peel sources (CNF)) with the film-forming matrix. This research fills gaps in literature by demonstrating how interactions among proteins, lipids, phenolic compounds, and cellulose nanoparticles influence film properties. The high chlorogenic acid content in SF reduced electrostatic repulsion between protein molecules, causing aggregation, oil droplet flocculation, and increased emulsion viscosity. The mechanical properties of emulsion-based films were significantly lower than those made with SF dispersions. Films made from low chlorogenic acid (yellowish SF) emulsions showed lower tensile strength and Young’s modulus but higher elongation at break compared to those made from high chlorogenic acid (greenish SF) emulsions. Water vapor permeability (WVP) decreased in films containing oil phases, but adding cellulose nanoparticles increased WVP. Despite this, the cellulose nanoparticles could not fully overcome the negative effects of lipid–protein interactions on mechanical properties and WVP. However, films containing eugenol exhibited significant antioxidant activity. The findings provide insights into developing sustainable, active packaging with antioxidant functionality and reduced environmental impact, opening new avenues for applications in food and other sectors requiring eco-friendly materials. Full article

As the structural complexity of machined components increases and the pace of product updates accelerates, the demands for machining precision in CNC machine tools are becoming increasingly rigorous. Consequently, the continuous enhancement of machining accuracy in machine tools presents a significant challenge that must be addressed within the realms of machine tool innovation and the development of manufacturing equipment. This paper conducts a comprehensive investigation into the tolerance optimization allocation method for geometric accuracy in precision horizontal machining centers utilizing interval theory. Initially, a mapping model is developed to represent each source of geometric error and the overall spatial error, drawing upon multi-body system theory. Subsequently, the global maximum interval sensitivity of each geometric error source in relation to the overall spatial model is analyzed. Finally, an interval optimization model for geometric accuracy is formulated based on interval optimization theory, employing a genetic algorithm to address the accuracy allocation problem associated with various error sources in machine tools. Full article

Although crystalline nanocellulose (CNCs) can be extracted from different resources, the employed pretreatments, which disrupt the inter- and intramolecular physical interactions, depend on the biomass sources. This study aims to valorize Aloe Vera (AV) rinds into cellulose and crystalline nanocellulose (CNC) employing two approaches during hydrolysis: sulfuric acid (CNC_SA) and citric acid (CNC_CA) after 30, 60, and 90 min of reaction. The effects of pretreatments and hydrolysis time on the functional groups and hydrogen bonding in biomass are discussed. Crystalline structure (polymorph type), crystallinity, thermal stability, morphology, particle size, and metal presence are also analyzed. A transformation from type I into II polymorph was achieved, where the intermolecular interactions governing cellulose were increased in CNC_SA and were almost maintained in CNC_CA. Properties based on the structure, thermal properties, particle size, and metal presence indicate that the CNC_SA30 and CNC_CA90 samples displayed potential application as reinforcement agents for other types of polymers having no more melting points of 160 and 220 °C, respectively. Full article

In CNC machines, the temperature field analysis of spindle servo permanent magnet motors (SSPMMs) under rated load, overload, and weak magnetic conditions is critical for ensuring stable operation and machining accuracy. This paper proposes a temperature calculation method for SSPMMs based on the thermal network method, which is used to quickly evaluate the temperature performance of SSPMMs under different operating conditions during design. This method can calculate the steady-state or transient temperature rise under different operating conditions. First, the electromagnetic performance and heat sources of the SSPMMs were analyzed. Then, based on the thermal network method, the equivalent thermal resistances and equivalent heat dissipation coefficients of the motor components were calculated. By iterating the heat balance equation or solving the heat conduction equation for different operating conditions, the temperature distribution of SSPMMs under different operating conditions was obtained. The accuracy of the thermal network model was validated through temperature analysis using fluid–structure interaction simulations and prototype testing. The results show that the relative error between the winding temperature calculated by the proposed equivalent thermal network model and the measured temperature under different operating conditions is less than 5%. This paper provides a theoretical basis for the thermal management of SSPMM, which can quickly and accurately evaluate the temperature rise in the motor during design. Full article