Search Results (146)

This work investigates the potential of wollastonite-based brushite cement (WBC) for the stabilization and solidification of radioactive waste contaminated by ⁹⁰Sr. This phosphate binder was formed by the reaction of wollastonite (CaSiO₃) with a phosphoric acid solution containing borax and metallic cations (Al³⁺, Zn²⁺). Two cement pastes were investigated: a commercial binder (WBC-C) and an optimized formulation (WBC-O), produced using a zinc-free mixing solution with a higher aluminum content than that of WBC-C. Mineralogical characterizations using XRD, TGA, XRF, SEM-EDX, and Raman spectroscopy showed that both materials mainly contained amorphous hydrated silica and calcium aluminophosphate, along with crystalline brushite, residual wollastonite, and quartz. The stability of WBC-C under γ-irradiation was evaluated up to a dose of 1 MGy. The only observable effect was water radiolysis, leading to dihydrogen production at yields comparable to Portland cement matrices and geopolymers. Strontium leaching, assessed using the ANSI/ANS-16.1-2003 (R2008) procedure, followed a two-stage release mechanism combining surface wash-off and diffusion. The apparent diffusion coefficient D_a of Sr in WBC-C was markedly lower than typical values reported for Portland cement matrices. WBC-O exhibited enhanced Sr retention, possibly due to its higher aluminum content, which refines mesopores and reduces diffusion pathways accessible to Sr. WBC binders therefore appear to be promising candidates for strontium immobilization. Full article

Hydrogels have attracted significant interest in multifunctional applications. Among them, self-healing hydrogel stands out for its ability to autonomously repair damage through reversible interactions, yet achieving both rapid self-healing and superior mechanical strength remains challenging. In this study, we report the fabrication of a dual cross-linked hydrogel (PAA-Alg-B) prepared via free radical polymerization of acrylic acid and alginic acid, employing N,N′-methylenebisacrylamide, or vinyl-modified nanocellulose as primary cross-linker, with Fe³⁺ or borax serving as an additional dynamic cross-linker. The resulting borax based hydrogel (PAA-Alg-B) exhibits remarkable fast self-healing efficiency enabled by reversible borate ester bonds and hydrogen bonding. It demonstrates tunable mechanical strength with toughness of 137 kJ/m³ and elongation at break up to 1117%, alongside exceptional swelling capacity (448 g/g). The adsorption studies reveal high removal efficiencies for heavy metals, with maximum capacities of 87.57 mg/g (Cr³⁺), 114.02 mg/g (Ni²⁺), and 99.42 mg/g (Cu²⁺), governed by chemisorption kinetics. The PAA-Alg-B can also be used as a promising solid-state electrolyte and separator for flexible supercapacitors. Protonic modulation via H₂SO₄ soaking significantly enhances ionic conductivity, electrochemical performance, and cycling stability. These findings highlight the potential of natural polymer-based, mechanically robust, self-healing hydrogels for sustainable wastewater treatment and advanced energy storage applications. Full article

Two commercial adhesive tape strips (Fungi-Tape^TM and Filmoplast^® P) and a polyvinyl alcohol–borax (PVA-B) gel were tested as novel physical cleaning alternatives to micro-aspiration for removing visible fungal colonisation from a cotton canvas. In addition, clove essential oil (CEO) and Cyrene™ were incorporated in the PVA-B gel for testing the potential of each to improve fungal cleaning. For the trials, canvas mock-ups were separately inoculated with two fungal species identified as Penicillium chrysogenum and Aspergillus westerdijkiae. Removal of fungi and related impacts were evaluated by DOM, FESEM, ATR-FTIR and ImageJ software. Inhibition of fungal spores and residual growth were assessed by in vitro growth tests and CLSM. Removal of A. westerdijkiae was more effective than removal of P. chrysogenum, especially for dense coverage. Both tape strips removed slightly more fungus than micro-aspiration, except for dense coverage of P. chrysogenum. The PVA-B gel, both with and without CEO or Cyrene™, yielded the best (similar) results, removing the fungal material found on the surface and subsurface of canvas without damaging the canvas fibres. Although further testing is required, the antifungal activity of PVA-B gel+ Cyrene™ seems comparable to that of PVA-B gel+ CEO, the former being especially effective against A. westerdijkiae. Full article

The global rise in obesity contributes to an increased prevalence of diabetes and a higher incidence of chronic wounds that are difficult to heal and often do not respond adequately to conventional treatments. This underscores the need for advanced wound-healing strategies. In this study, we designed and fabricated a novel three-layer hydrogel dressing based on poly(vinyl alcohol) (PVA), cross-linked with borax, and enriched with freeze-dried camel milk and vitamin B6. We prepared the hydrogels by dissolving PVA and borax in water, incorporating bioactive additives, and sequentially assembling individual layers. We evaluated the hydrogels for antibacterial activity using agar diffusion assays, cytocompatibility with human keratinocytes (NHEK), and mechanical and thermal properties. The results demonstrated that the PVA/borax hydrogel matrix exhibited inherent antibacterial activity that could be modulated by the addition of camel milk and vitamin B6. Certain formulations showed selective efficacy against the tested strains, and hydrogels containing bioactive components supported higher cell viability and exhibited favorable mechanical stability and water-retention characteristics. These findings suggest that the composite dressing developed combines antimicrobial properties with multifunctional bioactivity and structural integrity, supporting its potential as a comprehensive therapeutic system for managing diabetic wounds and justifying further preclinical investigations toward clinical application. Full article

This study proposes an innovative process of low-temperature soda roasting followed by water leaching to extract boron and produce borax from boron-rich slag. To further enhance the leaching rate of boron, pretreatment of the boron-rich slag with the nucleating agent TiO₂ was conducted. The effects of roasting temperature and Na₂CO₃ addition on the boron leaching rate, as well as the roasting kinetics of the TiO₂-nucleated furnace-cooled slag, were investigated. The results indicate that at a roasting temperature of 700 °C for 150 min, the maximum boron leaching rate can reach 88.65%. The reaction of low-temperature soda roasting for TiO₂-nucleated furnace-cooled slag to produce Na₂B₆O₁₀ is controlled by interfacial chemical reaction, with an apparent activation energy of 88.677 kJ/mol. Full article

Cleaning historical silk textiles is a particularly sensitive operation that requires precise control to prevent mechanical or chemical damage. In this study, we investigate using flexible PVA–borax-based gels to remove soot from silk, i.e., polyvinyl alcohol–borax (PVA-B) gels and polyvinyl alcohol–borax–agarose double network gels (PVA-B/AG DN) loaded with different cleaning agents—namely, 30% ethanol and 1% Ecosurf EH-6—in addition to plain gels loaded with water. These gel formulations were tested on simplified model systems (SMS) and were applied using two methods: placing and tamping. The cleaning results were compared with a traditional contact-cleaning approach; micro-vacuuming followed by sponging. Visual inspection, 3D opto-digital microscopy, colorimetry, and machine-learning-assisted (ML) soot counting were exploited for the assessment of cleaning efficacy. Rheological characterization provided information about the flexibility and handling properties of the different gel formulations. Among the tested systems, the DN gel containing only water, applied by tamping, was easy to handle and demonstrated the highest soot-removal effectiveness without leaving residues, as confirmed by micro-Fourier Transform Infrared (micro-FTIR) analysis. Scanning electron microscope (SEM) micrographs proved the structural integrity of the treated silk fibers. Overall, this work allows us to conclude that PVA–borax-based gels offer an effective, adaptable, and low-risk cleaning strategy for historical silk fabrics. Full article

Calcium magnesium phosphate cements (CMPCs) were obtained starting from dolomite (alone or mixed with fly ash) thermally treated at two different temperatures. Dolomite calcination at 750 °C for 3 h determined the formation of a mixture of MgO and CaCO₃. The mixing of dolomite with fly ash and the increase in the calcination temperature at 1200 °C determined the formation of new compounds (calcium aluminum silicate and calcium magnesium silicates), which are present along with MgO and small amounts of CaO in the thermally treated material. These two precursors were mixed with KH₂PO₄ solution and borax (as a retardant admixture) to obtain the CMPCs. The setting time and compressive strengths of these CMPCs were assessed and the XRD analyses provided insights into their mineralogical composition after hardening and thermal treatment. The cements, as so or mixed with perlite, were applied on steel plates, to assess their behavior when put in direct contact with a flame. The compatibility of these materials with the steel substrate was evaluated by scanning electron microscopy (SEM). The direct contact with the flame up to 60 min provided information regarding the CMPCs’ ability to prevent the rapid increase in the substrate (steel plate) temperature. The findings indicate that CMPC pastes and composites containing perlite can offer a degree of protection for steel structures in the event of a fire. Full article

Geopolymers, as sustainable alternatives to traditional cementitious materials, offer superior mechanical and durability properties; however, they face challenges with rapid setting, particularly in fly ash–slag systems. Retarders play a crucial role in tailoring the setting behavior and workability of geopolymers, especially in applications where extended setting time or placement under challenging conditions is required. Geopolymers, unlike traditional Portland cement, undergo a rapid alkali-activation process involving dissolution, polymerization, and hardening of aluminosilicate materials. This can lead to very short setting times, particularly at elevated temperatures. In this scenario, the present study investigates the effect of different retarders-including cellulose, starch, borax, and their different combinations the setting time. The effectiveness of a retarder depends on the geopolymer formulation, including the type of precursor, activator, and curing conditions. The initial and final setting times improved by the addition of retarders, whereas most of the retarders had a negative effect on compressive strength. The optimum retarder combination was starch and borax, with a remarkable improvement in setting time and a positive result on the compressive strength, while maintaining reasonable workability. The retarder was equally effective under both ambient and oven-cured conditions and for different mix proportions of fly ash (FA) and slag, indicating that its effectiveness depends only on the type of precursors used. The study reveals the use of borax along with cellulose- or sugar-based compounds, which balances the reaction kinetics, resulting in balanced mechanical characteristics. Full article

Background: Conventional insulin injections cannot mimic physiological pancreatic function and often lead to dangerous hypoglycemic events that glucose-responsive systems aim to prevent. Glucose-responsive microneedles (MNs) offer a promising closed-loop alternative. We developed an enzyme-free, glucose-responsive MN patch composed of a PVA/Dextran hydrogel dynamically crosslinked with borax, and evaluated its performance, biosafety, and in vivo efficacy. Methods: MNs were fabricated from PVA/Dextran via micromolding and crosslinked with borax. The formulation was systematically optimized based on mechanical properties and glucose-responsive release kinetics. Physicochemical properties, biosafety (cytotoxicity, skin barrier recovery, boron leaching), and in vivo efficacy in a type 1 diabetic mouse model were evaluated in comparison to a subcutaneous (SC) insulin injection. Results: The optimized MNs showed robust mechanics (per-needle fracture force approximately 1.0 N) for reliable skin penetration. The system demonstrated clear glucose sensitivity, with a release flux ratio ≥1.5 between hyperglycemic (e.g., 400 mg·dL⁻¹) and normoglycemic (100 mg·dL⁻¹) conditions and exhibited excellent reversibility under alternating glucose levels. The patch was highly biocompatible, with >95% cell viability, the only transient skin barrier disruption that fully recovered within 24 h, and had low boron release from patches in vitro. In vivo, the optimized sI-MN patch demonstrated a sustained, glucose-responsive release profile, maintaining blood glucose in diabetic mice near 100 mg·dL⁻¹ for approximately 8 h. This pharmacokinetic profile contrasts markedly with the rapid hypoglycemic nadir and rebound hyperglycemia observed with a standard subcutaneous insulin bolus, highlighting the patch’s potential for mitigating hypoglycemia. Conclusions: The enzyme-free PVA/Dextran/borax MN patch enables autonomous, glucose-responsive insulin delivery. It provides more stable and safer glycemic control than conventional injections by mitigating the risk of hypoglycemia. By mitigating the hypoglycemic risk associated with bolus injections, this systematically optimized platform represents a potential step toward a safer, patient-friendly diabetes therapy, though significant challenges in duration and dose scaling remain. Full article

Cellulose acetate (CA) is a semi-synthetic polymer widely present in modern and contemporary collections, yet its conservation poses major challenges due to its chemical and physical instability. Hydrolytic degradation, acetic acid release, plasticizer loss, and embrittlement compromise both structure and surface, making cleaning particularly difficult. Conventional cleaning methods may cause abrasion, extract additives, or alter gloss. Although hydrogels have shown promise for CA cleaning, the literature remains extremely limited. This study reports a preliminary investigation of gel-based cleaning on Le Rituel (1968), a heavily soiled cellulose acetate (CA) artwork by José Escada. The object’s condition was assessed through visual inspection, pH measurements, volatile acidity testing, and infrared spectroscopy. Cleaning tests were conducted on a CA replica (2006) with superficial soiling and on selected artwork areas. Two gel formulations were evaluated: the biopolymer agar-agar rigid gel and the synthetic viscoelastic poly(vinyl alcohol)-borax (PVAl-Borax) gel. Agar-agar was effective as a first step, reducing superficial soiling and humidifying adherent residues for subsequent removal, while PVAl-Borax was advantageous in the second step, as its viscoelastic properties enabled controlled mechanical action and facilitated the removal of more adherent residues. This case study demonstrates the potential of combined gel systems as versatile tools for CA conservation. Full article

This paper presents an overview of a research line developed at the Istituto Centrale per il Restauro within the CHANGES (Cultural Heritage Active Innovation for Next-Gen Sustainable Society) project, funded under the Italian National Recovery and Resilience Plan. The research was developed in different phases: a first one dedicated to the study of the deep background and the state of the art in the ICR background: history, methodologies and research in the field; a second phase was dedicated to the selection of a specific urban art mural, as a key study with conservation problems connected to some of the principal preservation treatments related to the outdoor context; the mural was also identified as a beloved icon in the public space with a profound socio-cultural meaning for the community. Nido di Vespe, created in 2014 by the artist Lucamaleonte is part of a broader artistic project called M.U.Ro-Museum of Urban Art of Rome, an open-air public art museum located in the Quadraro district in Rome, designed by the artist Diavù. A third phase focused on the research in ICR laboratories, specifically addressing: cleaning, reintegration, and protection strategies adapted to dynamic outdoor environments. A multi-step cleaning system based on polyvinyl alcohol-borax semi-interpenetrated hydrogels loaded with nanostructured fluids was developed to selectively remove spray-paint vandalism while preserving the chemically similar original pictorial layers. The reintegration phase investigated acrylic and urea-aldehyde resins as binders to produce compatible, reversible, and UV-traceable retouching and infilling materials. For surface protection, multilayer coating systems incorporating nanoparticles with antimicrobial, photocatalytic, and UV-stabilizing properties were formulated to enhance durability and chromatic stability. Laboratory tests on mock-ups simulating typical street and urban art materials and morphologies showed satisfactory results, while diagnostic investigations on Nido di Vespe provided the reference data to calibrate the experiments with real mural conditions. Cleaning tests demonstrated promising removal efficiency, influenced by the chemical composition, thickness of the overpainted layers, and surface roughness. The reintegration system met the expected performance requirements, as the tested binders provided good results and allowed the development of compatible, reversible, and distinguishable solutions. Protective coatings showed good results in terms of chromatic stability and surface integrity; however, the long-term behavior of both reintegration, cleaning, and protection systems requires further evaluation. The results achieved so far support the development of sustainable and flexible conservation strategies for the conservation of contemporary street and urban murals and will guide the future application of the selected materials and methodologies in pilot conservation interventions on the mural chosen as a meaningful case study within the broader research. Full article

Coal is commonly used as both fuel and reducing agent in producing synthetic rutile from ilmenite (FeTiO₃) via the Becher process, which upgrades ilmenite to high-purity TiO₂ (>88%). However, coal-based reduction generates significant carbon waste. This study investigated the effect of adding 1–5% w/w potassium hydroxide (KOH), sodium hydroxide (NaOH), and sodium tetraborate (borax) to coal during ilmenite reduction to improve metallisation and reduce carbon burn-off. Results showed that 1% w/w additives significantly increased metallisation to 96% (KOH), 95% (NaOH), and 93% (borax), compared to 80% without additives, while higher concentrations (3–5% w/w) decreased metallisation. Scanning electron microscopy (SEM)analysis showed cleaner particle surfaces and optimal metallisation at 1% w/w, whereas higher additive levels caused agglomeration or sintering due to elevated silica and alumina activity. Additive type also influenced TiO₂ quality, with KOH enhancing TiO₂ at low concentrations but causing negative effects at higher levels, while NaOH and borax reduced TiO₂ quality via sodium-based compound formation. All additives reduced carbon burn-off, with KOH producing the greatest reduction. The iodine number of the carbon residue increased with higher additive concentrations, with KOH achieving 710 mg/g at 1% w/w and 900 mg/g at 5% w/w, making the residue suitable for water treatment. Overall, KOH is the most effective additive for producing high-quality synthetic rutile while minimising carbon waste. Full article

The availability of key precursors of alkali-activated binder (AAB) systems is declining, requiring sources. Calcined clays (CCs) stand out as a promising alternative due to their widespread accessibility. Although the properties of CC and blast furnace slag (BFS)-based two-part AABs have been well reported in the literature, the effect of minor additives on the properties of a one-part AAB system composed of CC and BFS remains unexplored. In this research, calcined magnesia (CM), aerial lime (AL), hydraulic lime (NHL), quicklime (QL), borax (BR), and zeolite (ZP) have been used as minor additives and incorporated into the AAB system at between 2% and 15%. The specimens were activated with sodium–metasilicate, and the fresh, physical, mechanical, durability and microstructural properties of mortars have been investigated. Key findings indicate that all minor additives, except for BR, enhanced the early- and later-age mechanical properties. Notably, 10% QL addition significantly increased compressive strength by up to 55% at 28 days (50.9 MPa), compared to the reference. BR and ZP usage eliminated the efflorescence formation without compromising other properties. Furthermore, incorporating QL, AL, CM, and BR markedly reduced the chloride permeability of the mortars and decreased D_nssm value by as much as 81%, compared to the reference. Full article

Hydrogels are crosslinked polymer chains that form a three-dimensional network, widely used for wound dressing due to their ability to absorb significant amounts of fluid. This study aimed to develop a hydrogel patch for wound dressing with self-healing properties, particularly for joints and stretchable body parts, providing a physical barrier while maintaining an optimal environment for wound healing. Polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (Na CMC) were crosslinked with borax, which reacts with the active hydroxyl groups in both polymers to form a hydrogel. The patches were loaded with ciprofloxacin HCl (CIP), a broad-spectrum antibiotic used to prevent and treat various types of wound infections. Hydrogels were subjected to rheological, morphological, antimicrobial, self-healing, ex vivo release, swelling, cytotoxicity, wound healing, and stability studies. The hydrogels exhibited shear-thinning, thixotropic, and viscoelastic properties. Microscopic images of the CIP hydrogel patch showed a porous, crosslinked matrix. The antimicrobial activity of the patch revealed antibacterial effectiveness against five types of Gram-positive and Gram-negative bacteria, demonstrating a minimum inhibitory concentration of 0.05 μg/mL against E. coli. The swelling percentage was found to be 337.4 ± 12.7%. The cumulative CIP release percentage reached 103.7 ± 3.7% after 3 h, followed by zero-order release kinetics. The stability studies revealed that the crossover point shifted toward higher frequencies after 3 months of storage at room temperature, suggesting a relaxation in the hydrogel bonds. The cytotoxicity study revealed that the CIP hydrogel patch is non-cytotoxic. Additionally, the in vivo study demonstrated that the CIP hydrogel patch possesses wound-healing ability. Therefore, the CIP PVA/Na CMC/Borax patch could be used in wound dressing. Full article

Porous aluminum alloys are widely used for lightweight structural materials such as marine structures, energy absorbers, and buoyant components. However, the conventional foaming agent TiH₂ presents limitations such as high cost and elevated decomposition temperatures, which increase manufacturing costs and restrict industrial applicability. In addition, the utilization of recycled raw materials such as aluminum machining chips has emerged as an important challenge in material development for resource efficiency and sustainability. To address these issues, porous aluminum alloys were fabricated in this study using recycled A356 aluminum chips by incorporating TiH₂ and a low-cost alternative foaming agent, Na₂B₄O₇·10H₂O (borax), either individually or in combination. The effects of foaming agent content (1, 1.5, and 3 wt.%) on pore characteristics, microstructure, hardness, and corrosion resistance were systematically investigated. TiH₂ induced an increase in porosity due to hydrogen generation and also promoted grain refinement, which contributed to the improvement of hardness and corrosion resistance, while Na₂B₄O₇·10H₂O exhibited effective pore formation and hardness improvement at 1–1.5 wt.% but tended to deteriorate corrosion resistance as its content increased. In particular, combined addition of both agents at 1.5 wt.% showed excellent pore formation and corrosion resistance properties, with a relatively high pore area fraction (2.38%), porosity (27.0%), SDAS (48.1 ± 4.8 µm), hardness (59.35 ± 6.4 HV), corrosion potential (−1.039 V), pitting potential (−0.709 V), and corrosion current density (4.956 μA/cm²). This study demonstrated that Na₂B₄O₇·10H₂O (borax) foaming agent can be an economic alternative to TiH₂, and shows that the performance of porous aluminum alloys can be effectively improved by optimizing the combination of recycled raw materials and foaming agents. Full article