Search Results (998)

This study addresses the critical issue of environmental pollution from plastic waste by investigating an effective chemical recycling method for polyethylene terephthalate (PET) via neutral catalytic hydrolysis. We utilized a recoverable and regenerable composite catalyst based on cracking zeolite and γ-Al₂O₃, which possesses both Brønsted and Lewis acidic sites that facilitate the depolymerization of PET into its constituent monomers, terephthalic acid (TPA) and ethylene glycol (EG). This investigation reveals that the catalytic performance is strongly dependent on the total acid site concentration and the specific nature of these sites. A key finding is that a balanced acidic profile with a high proportion of Brønsted acid sites is crucial for enhancing PET hydrolysis attributed to a significant decrease in the activation energy of the reaction. The experiments were conducted in a stirred stainless-steel autoclave reactor, where key parameters such as temperature (210–230 °C), the PET-to-water ratio (1:2 to 1:5), and reaction time were systematically varied. Under optimal conditions of 210 °C and a 6 h reaction time, the process achieved near-complete PET depolymerization (99.5%) and a high TPA yield (90.24%). The catalyst demonstrated remarkable recyclability, maintained its activity over multiple cycles and was easily regenerated. Furthermore, the recovered TPA was of high quality, with a purity of 98.74% as confirmed by HPLC, and exhibited a melt crystallization temperature 14 °C lower than that of the commercial standard. These results not only demonstrate the efficiency and sustainability of neutral catalytic hydrolysis using zeolite/alumina composites but also provide valuable insights for designing advanced catalysts with tunable acidic properties. By demonstrating the importance of tuning acidic properties, specifically the balance between Brønsted and Lewis sites, this work lays a foundation for developing more effective catalysts that can advance circular economy goals for PET recycling. Full article

Large-format additive manufacturing (LFAM) is an enabling manufacturing technology capable of producing large parts with highly complex geometries for a wide variety of applications, including automotive, infrastructure/construction, and aerospace mold and tooling. In the past decade, the LFAM industry has seen widespread use of bio-based, glass, and/or carbon fiber reinforced thermoplastic composites which, when printed, serve as a lower-cost alternative to metallic parts. One of the highest-volume materials utilized by the industry is carbon fiber (CF)-filled polycarbonate (PC), which in out-of-autoclave applications can achieve comparable mechanical performance to metal at a significantly lower cost. Previous work has shown that if this material is recovered at various points throughout the manufacturing process for both the lab and pilot scale, it can be mechanically recycled with minimal impacts on the functional performance and printability of the material while significantly reducing the feedstock costs. End-of-life (EOL) CF-PC components were processed through industrial shredding, melt compounding, and LFAM equipment, followed by evaluation of the second-life material properties. Experimental assessments included quantitative analysis of fiber length attrition, polymer molecular weight degradation using gel permeation chromatography (GPC), density changes via pycnometry, thermal performance using dynamic mechanical analysis (DMA), and mechanical performance (tensile properties) in both the X- and Z-directions. Results demonstrated a 24.6% reduction in average fiber length compared to virgin prints, accompanied by a 21% decrease in X-direction tensile strength and a 39% reduction in tensile modulus. Despite these reductions, Z-direction tensile modulus improved by 4%, density increased by 6.8%, and heat deflection temperature (HDT) under high stress retained over 97% of its original value. These findings underscore the potential for integrating mechanically recycled CF-PC into industrial LFAM applications while highlighting the need for technological innovations to mitigate fiber degradation and enhance material performance for broader adoption. This critical step toward circular material practices in LFAM offers a pathway to reducing feedstock costs and environmental impact while maintaining functional performance in industrial applications. Full article

This study presents a solvothermal approach starting from micron-sized hydroxide precursors, which combines features of top-down size reduction and bottom-up recrystallization, leading to nanoscale hydroxide particles. The method is based on autoclave treatment at a moderate temperature (180 °C) and a pressure of 8 bar, using different mixtures of water and isopropanol. The hydroxide precursors, used in micrometric form without surfactants or additives, were converted into nanoscale particles through a one-pot, one-step process. The nanomaterials obtained were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), optical microscopy (MO), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface area analysis to assess their structural, morphological and textural characteristics. The results show that solvent composition and precursor concentration strongly influence the crystalline phase, particle morphology, dispersion stability and surface area. Well-defined acicular and fibrous morphologies were obtained for Ba(OH)₂ and Sr(OH)₂, while Mg(OH)₂ formed spherical and hexagonal structures, respectively. Of all the conditions tested, the 75:25 water/isopropanol ratio produced the most stable systems. This work provides a method to produce alkaline earth hydroxide nanoparticles with tunable properties. Full article

High-strength concrete (HSC) is widely used in coastal regions, but its durability and structural safety is threatened by chloride ingress in marine environments. This study investigates the effects of different curing methods, normal, steam, and high-temperature autoclave on the chloride resistance of HSC using the electric flux test. A critical chloride concentration of 4.5% was identified, and accelerated deterioration tests were conducted to evaluate mechanical properties development (compressive strength, elastic modulus, toughness, specific toughness) under the various curing conditions. Additionally, the development of hydration products and microstructural characteristics were analyzed to elucidate the mechanisms underlying the observed differences. The results indicate that steam and autoclave curing enhance cement hydration and the initial mechanical properties of HSC but also increase permeability and susceptibility to chloride ion penetration compared to normal curing. Chloride penetration was found to be most severe at moderate chloride concentrations (~4.5%), while higher concentrations resulted in reduced ion migration. Although intensive curing under elevated temperature and pressure improves early strength and stiffness, it accelerates mechanical degradation under chloride exposure, highlighting a trade-off between short-term performance and long-term durability. Full article

Rapid urbanization in developing regions presents a critical challenge to the provision of affordable housing. This systematic review, conducted following the PRISMA 2020 guidelines, analyzed 91 studies (2013–2024) from Scopus and Google Scholar to identify cost-effective materials and innovative techniques suitable for the developing context. Findings reveal that achieving affordability in developing regions requires a holistic approach that integrates material innovation with human capacity building. The analysis of critical success factors (CSFs) in the Rumah Unggul Sistem Panel Instant (RUSPIN) system from Indonesia and the Recycled Plastic Formwork (RPF) system from South Africa exemplifies this integration. Both systems show high potential for scalability and technological transfer using local materials and labor training. The review also highlights that materials commonly used in developed countries (e.g., autoclaved aerated concrete, expanded polystyrene, and light steel gauge framing) face adoption barriers in developing regions due to challenges related to supply chains, industry capacity, and regulatory frameworks. Conversely, locally available materials (e.g., earth, bamboo, and recycled waste) require ongoing research to enhance their availability and structural performance. Ultimately, achieving affordable housing depends on an integrated approach that combines locally sourced materials, innovative construction techniques, and the strategic application of critical success factors. Full article

Sterilization of medical devices is a critical process to ensure patient safety. However, traditional steam autoclaves may be unsuitable for heat-sensitive materials. In this study, we evaluated an innovative cold sterilization system based on the controlled generation of free radicals with reducing properties. The system has already been validated and marketed following the completion of numerous microbiological tests in compliance with UNI EN standards (13727, 13624, 17126, 14476, 14348). A quantitative suspension test was conducted under controlled conditions, comparing the microbial reduction achieved with the cold system to that obtained with a standard autoclave cycle. The system demonstrated bactericidal efficacy exceeding 6 log₁₀, comparable to that of the autoclave cycle. The results suggest that the free radical system represents a safe, rapid, and effective alternative for the sterilization of heat-sensitive materials, with potential applications in both healthcare and industrial settings. Full article

The mechanical and microstructural properties of monolithic zirconia ceramics are significant factors for their long-term clinical performance. This study aims to investigate the effects of hydrothermal aging on these properties for the 3Y-TZP, 4Y-TZP, and 5Y-TZP formulations. Specimens were prepared from 3 different zirconia blocks: 3Y-TZP (HT), 4Y-TZP (ST), and 5Y-TZP (XT). Half of the specimens were aged in an autoclave (134 °C, 2 bar, 5 h) while the others remained as controls. Three-point flexural strength, Vickers hardness, and surface roughness tests, as well as XRD, AFM, and SEM/EDS analysis, were performed. The material type significantly affected the flexural strength, Vickers hardness, and surface roughness. Aging did not significantly affect the flexural strength or surface roughness but reduced the Vickers hardness in the 3Y-TZP sample. The 3Y-TZP and 5Y-TZP samples displayed the highest and lowest flexural strength, respectively. In the non-aged groups, 3Y-TZP and 5Y-TZP exhibited higher hardness than 4Y-TZP, and after aging, 3Y-TZP displayed the lowest hardness. Further, 5Y-TZP showed the highest surface roughness before and after aging. XRD revealed an increased monoclinic phase in the aged 3Y-TZP and 4Y-TZP. No monoclinic phase was observed in 5Y-TZP. According to AFM measurements, aging led to a smoother surface in 3Y-TZP but increased roughness in 4Y-TZP and 5Y-TZP. SEM/EDS revealed changes in the elemental compositions following aging. According to the results of this study, different material formulations affect the mechanical behavior and microstructural properties of monolithic zirconia ceramics. Further, hydrothermal aging displayed effects on the Vickers hardness and phase transformations. Full article

Macroalgae have low nutrient bioavailability, often requiring pretreatments—physical, chemical, or biological—typically using low-solid loading hydrolysis, which produces separate liquid and solid phases. In contrast, high-solid loading hydrolysis offers a single-phase alternative, though it remains underexplored for macroalgae. This study evaluated the effectiveness of high-solid loading hydrolysis for breaking polysaccharides and increasing the availability of nutrients and antioxidant compounds in Codium tomentosum. Treatments using mixtures containing 25% dry biomass and 75% water or 0.5N and 1N NaOH, autoclaved for 30 or 60 min, were performed. Among the tested treatments, high-solid loading alkaline autoclaved treatment (1N NaOH, 60 min) was most effective in reducing neutral detergent fiber and enhancing the availability of bioactive compounds, particularly soluble proteins and phenols. Based on these results, a sequential enzymatic hydrolysis with Natugrain^® at 0.2 and 0.4% was also applied to pre-treated C. tomentosum with water or 1N NaOH. Enzymatic hydrolysis after autoclaving had no major effect on fiber, soluble protein, or ash, but increased phenol levels. In conclusion, high-solid loading alkaline treatment (1N NaOH) followed by enzymatic hydrolysis with Natugrain^® enzyme reduced fiber content and enhanced soluble protein and phenolic compounds, thereby improving the nutritional and functional potential of C. tomentosum for inclusion in animal feeds. Full article

Background/Objectives: Juzentaihoto (JTT), a traditional Kampo formula composed of ten medicinal herbs, is widely prescribed in Japan for immune enhancement and general health maintenance. This exploratory, open-label pilot study aimed to evaluate the feasibility and immunomodulatory effects of JTT in cancer patients and to explore its potential mechanisms of action. Methods: Ten cancer patients received oral JTT (7.5 g/day) for 14 days, while healthy volunteers served as a reference group. Peripheral natural killer (NK) cell phenotypes and CD95 expression were analyzed by flow cytometry, and serum Fas ligand (FasL) concentrations were measured by ELISA. Complementary in vitro assays using PBS-extracted, autoclaved JTT were conducted to assess Fas/FasL-mediated apoptosis in Jurkat and primary T cells by flow cytometry and Western blotting for cleaved caspase-8 and -3. Additional experiments with staurosporine (intrinsic apoptosis) and TRAIL in OSC-19 carcinoma cells were performed to determine pathway specificity. Results: In patients, most NK-cell markers showed no statistically significant within-subject changes, although a trend-level increase in NKp46 and a significant reduction in NK-cell CD95 expression (paired p = 0.014) were observed. Between-group differences primarily reflected baseline disparities between cancer patients and healthy controls. In vitro, JTT (50–100 µg/mL) partially attenuated FasL-induced apoptosis and reduced cleaved caspase-3 without affecting cleaved caspase-8, suggesting selective downstream modulation of the extrinsic pathway. Conclusions: Within the limitations of a small, non-randomized cohort without placebo, these findings are hypothesis-generating and indicate that JTT selectively modulates Fas-mediated lymphocyte apoptosis without promoting tumor immune evasion. Further randomized trials and mechanistic studies incorporating co-culture or 3D tumor–immune models are warranted to confirm these observations and identify active constituents. Full article

This study evaluated the effect of two cooking methods on food quality indicators in eight varieties of lima bean (Phaseolus lunatus L.), a species that in its raw state is characterized by high hardness and elevated levels of antinutritional compounds. After washing and soaking in distilled water (1:4 grain/water ratio, 3 h), two cooking methods were applied: autoclaving at 121 °C (steam cooking) and boiling in an open system at 91 °C, until reaching a defined hardness endpoint. Both cooking techniques significantly reduced grain hardness, from 2975 to 427.26 kgf in variety V3 (Torta IM. 003 red). Protein content increased up to 33.48% in V5 (Torta IM. 006 cream-black), while protein digestibility reached 89% in V1 (Pallar PE. 001), with steam cooking showing superior results. Likewise, non-nutritional components predominant in raw grains were more effectively reduced by steam cooking. The findings highlight varietal differences in response to processing and confirm steam cooking as the most efficient method to enhance nutritional quality and minimize non-nutritional components in P. lunatus. These results provide relevant insights for improving the use of P. lunatus in human nutrition. Full article

Pakistan’s housing sector faces a significant shortfall alongside growing climate risks. This study assesses climate-smart construction options autoclaved aerated concrete (AAC) blocks, interlocking bricks, and rat-trap bond masonry through energy simulations, cost modeling, and expert consultations. A 10-Marla residential unit in Islamabad was used as the reference case. Results indicate AAC reduces cooling energy by 22%, interlocking bricks reduce construction costs by 26.6%, and rat-trap masonry lowers electricity use by 12–16%. Despite technical viability, adoption remains limited due to financing and regulatory barriers. The study proposes a phased policy roadmap to integrate low-carbon materials into Pakistan’s housing and climate adaptation strategies. Full article

Despite the widespread use of surgical guides, there is no universal sterilization protocol. Surgical guides are often designed for single use, but can become contaminated, which increases the risks of infection and implant failure. Purpose: This study evaluates the effects of alcohol immersion, alcohol spray, low temperature, and steam sterilization on the dimensional stability of surgical guides to ensure accurate implant placement and reduce failure. Material and Methods: One standard dental model was scanned using a laboratory scanner. Ninety guides were printed and were then divided into six groups allocated as control, alcohol spray, alcohol immersion with ultrasonication, low-temperature dry sterilization, and two autoclave methods. Specimens were stored in dry–dark media and scanned at 0, 3, and 7 days, with dimensional changes assessed using CloudCompare. The Shapiro–Wilk, Levene’s, Repeated measures one-way ANOVA, and Tukey’s post hoc tests were used to determine statistical differences. Results: Time significantly affects stability, with RMS values improving over time. Autoclave 121 °C and low-temperature 54 °C sterilization showed the lowest RMS values, indicating better stability. Conclusions: Within the limitations of the present study, the most effective approach for maintaining the dimensional stability of surgical guides was autoclaving at 121 °C, +1 bar for 20 min, and the second-best technique was low-temperature dry sterilization at 54 °C for 1 h. Full article

Autoclaved lightweight concrete (ALC) exhibits considerable potential as a wall material in prefabricated structures, but its high water absorption and limited mechanical properties limit its widespread application. Ultra-high-performance concrete (UHPC), which possesses superior mechanical strength and durability, presents a promising reinforcement strategy. This study proposes the development of a UHPC-ALC composite wall material to enhance structural performance. The effects of shrinkage-reducing agent (SRA) content and expansive agent (EA) dosage on UHPC properties were systematically investigated. Results indicate that increasing SRA content improves the fluidity of UHPC and significantly reduces early autogenous shrinkage while the optimal EA dosage enhances both its mechanical properties and volume stability. Furthermore, an interfacial agent was employed to enhance the bonding performance between UHPC and ALC resulting in an average bonding strength of 0.93 MPa which represents a 675% increase compared with the untreated group. Finite element simulations and mechanical tests revealed that the composite material demonstrates a compressive strength of 11.2 MPa and a flexural strength of 6.8 MPa which corresponds to increases of 111.3% and 325%, respectively, relative to monolithic ALC. The composite demonstrated ductile failure and the experimental damage modes were consistent with those of the simulation results. This study offers guidance for optimizing UHPC-based composite wall materials via the multi-scale regulation of shrinkage behavior, interfacial properties, and structural design. Full article

This article provides a comprehensive review of the chemistry, production technology, and utilization of nanolime. Particular attention is given to the synthesis of Ca(OH)₂ nanoparticles through both bottom-up and top-down approaches, highlighting how modern techniques enable precise control of particle size, morphology, and stability. The physicochemical properties of nanolime are discussed in relation to its role as a highly reactive, multifunctional additive, i.a., for cementitious systems, asphalt, and autoclaved products. Its applications are explored with emphasis on performance improvement in construction engineering, including enhanced strength, durability, self-healing potential, and compatibility with low-carbon binders. Beyond construction, nanolime is also examined as a material with relevance to environmental protection, CO₂ sequestration, and heritage conservation. The review demonstrates that nanolime is a versatile and strategic material whose properties can be tailored to specific engineering needs, though challenges such as agglomeration, carbonation control, scalability, and long-term durability remain. Future research directions are outlined, focusing on sustainable production methods, functional integration into next-generation binders, and cross-disciplinary applications. Full article

Changes in the soil microbial community for studies of different novel communities can be promoted by different methodologies, among which soil autoclaving stands out as a quick and readily available tool. However, this procedure may also directly or indirectly alter nitrogen (N) and phosphorus (P) dynamics. The purposes of this study were as follows: (i) to characterize microbial activity after soil autoclaving through microbial ¹⁴CO₂-respiration; and (ii) to evaluate the effect of microbial manipulation and autoclaving on soil N and ³³P dynamics. For this, two sets of soil samples from two areas (forest and cultivated area) were used in the laboratory. Firstly, ¹⁴C-glucose was added to the soils and after 24 h five soil microbiomes were generated: AS (autoclaved soil), and AS re-inoculated with serial dilutions (w/v) prepared by successive mixing of soil suspensions in sterile deionized water obtaining 10⁻¹, 10⁻³, and 10⁻⁶, which generated the treatments AS + 10⁻¹, AS + 10⁻³, and AS + 10⁻⁶; and the treatment NS (non-autoclaved control), all incubated for 28 d. ¹⁴CO₂ emission was used to characterize microbial activity; additionally, N dynamics were assessed at the end of incubation. In a second assay, ³³P was applied to the soil before autoclaving and re-inoculation. Following further incubation (14 d), a ³³P chemical fractionation was performed. The following are based on the results: (i) ¹⁴CO₂ emission: microbial activity in the autoclaved soil is null, but after a reinoculation of AS + 10⁻¹ and AS + 10⁻³ soil dilution suspension, the ¹⁴CO₂-respiration is higher than in an NS. (ii) regarding the N dynamics, in autoclaved soils, the microbial levels increased N-NH₄⁺ concentration, with an evident increase in the AS + 10⁻³ and AS + 10⁻¹, and a reduction in the N-NO₃⁻ concentration in comparison to the NS. For ³³P, the autoclaving procedure itself reduced the ³³P lability, regardless of the levels of microbial community reinoculated. Full article