Search Results (239)

This study investigates water-based gel and gel-like cleaning treatments on Superficie 553, an oil painting on canvas by Giuseppe Capogrossi, using portable NMR to assess their impact. The objective was to evaluate the effects of four cleaning systems composed of a buffer solution released in free form and combined with xanthan gum, a cross-linked silicone polymer gel, and an agar gel matrix. Two distinct NMR experiments were conducted. The first involved the acquisition of ¹H depth profiles to detect the distribution of the cleaning solution within the painted layer and the thickness variations resulting from cleaning procedures. The second employed the acquisition of relaxation times, facilitating the investigation of molecular mobility within the organic components of the paint layer. NMR results indicated that the agar gel system caused negligible structural changes, whereas the silicone gel induced rigidification, and the other systems permanently increased molecular mobility. These measurements provided insights into alterations in the dynamic behavior of the polymerized oil. A key strength of this investigation lies in the direct application of diagnostic methods on Superficie 553, made possible by the non-invasive nature and portability of the NMR-MOUSE system. Additionally, portable FTIR was used to detect residues and obtain chemical information, confirming that the silicone gel left detectable residues and identifying the agar gel as the most conservative cleaning method. This enabled in situ analysis of the original artwork without sampling or relocation—a crucial advantage given the difficulty of replicating the complex physicochemical conditions of historical paint surfaces under laboratory constraints. Such real-time, on-site monitoring ensured an authentic evaluation of the treatment effects, preserving the integrity of the artwork throughout the conservation process. Full article

This study evaluated the effect of incorporating chia seed gel powder (CSGP) as a natural, clean-label stabilizer on the physicochemical, functional, microbiological, microstructural, antioxidant, and sensory properties of probiotic low-fat yogurt (PLFY) during 21 days of refrigerated storage. Six formulations were prepared using 0–2.5% CSGP, including Control (0% CSGP), YOG1 (0.5% CSGP), YOG2 (1.0% CSGP), YOG3 (1.5% CSGP), YOG4 (2.0% CSGP), and YOG5 (2.5% CSGP). Results showed that increasing CSGP levels noticeably enhanced the total solids, protein content, viscosity, hardness, and water-holding capacity of the PLFY (p < 0.05), while consistently reducing syneresis. Antioxidant activity also rose with higher CSGP concentrations, with YOG5 exhibiting the greatest DPPH scavenging activity (35.12%). Confocal laser scanning microscopy revealed a denser and more uniform protein network in PLFY fortified with CSGP, consistent with rheological measurements showing increased storage (G′) and loss (G″) moduli. Probiotic viability significantly increased (p < 0.05) in CSGP-added samples, indicating a potential prebiotic effect of CSGP. Sensory results demonstrated that although higher CSGP levels slightly darkened the yogurt color, body, texture, flavor, and total sensory scores improved markedly, with YOG5 gaining the highest total score (81.77). The results demonstrate that CSGP acts as a highly effective, multifunctional ingredient that enhances texture, stability, probiotic viability, and antioxidant capacity, making it a strong clean-label candidate for developing high-quality, functional probiotic low-fat yogurt. Full article

This study addresses the challenges of low-pressure oil well workover operations, namely, severe loss of water-based workover fluid, significant reservoir damage from conventional temporary plugging agents, and slow production recovery, by focusing on the yet-mechanistically unclear “fuzzy-ball workover fluid.” Laboratory experiments combined with field data were used to evaluate its plugging performance and reservoir-protective mechanisms. In sand-filled tubes (diameter 25 mm, length 20–100 cm) sealed with the fuzzy-ball fluid, the formation’s bearing capacity increased by 3.25–18.59 MPa, showing a positive correlation with the plugging radius. Compatibility tests demonstrated that mixtures of crude oil and workover fluid (1:1) or crude oil, workover fluid, and water (1:1:1) held at 60 °C for 80 h exhibited only minor apparent viscosity reductions of 4 mPa·s and 2 mPa·s, respectively, indicating good stability. After successful plugging, a 1% ammonium persulfate solution was injected for 2 h to break the gel; permeability recovery rates reached 112–127%, confirming low reservoir damage and effective gel-break de-blocking. Field data from five wells (formation pressure coefficients 0.49–0.64) showed per-well fluid consumption of 33–83 m³ and post-workover liquid production index recoveries of 5.90–53.30%. Multivariate regression established mathematical relationships among bearing capacity, production index recovery, and fourteen geological engineering parameters, identifying the plugging radius as a key factor. Larger radii enhance both temporary plugging strength and production recovery without harming the reservoir, and they promote production by expanding the cleaning zone. In summary, the fuzzy-ball workover fluid achieves an integrated “high-efficiency plugging–low-damage gel-break–synergistic cleaning” mechanism, resolving the trade-off between temporary-plugging strength and production recovery in low-pressure wells and offering an innovative, environmentally friendly solution for the sustainable and efficient exploitation of oil–gas resources. Full article

The environmental sustainability of cleaning materials used in heritage conservation remains poorly quantified despite growing attention to the replacement of hazardous petroleum-based solvents with bio-based alternatives. This study applies a comprehensive Life Cycle Assessment (LCIA) to compare conventional solvents with innovative bio-based formulations, including Fatty Acid Methyl Esters (FAMEs), Deep Eutectic Solvents (DES), and aqueous or organogel systems used for cleaning painted surfaces. Following ISO 14040/14044 standards and using the Ecoinvent v3.8 database with the EF 3.1 impact method, three functional units were adopted to reflect material and system-level scales. Results demonstrate that water-rich systems, such as agar gels and emulsified organogels, yield significantly lower climate and toxicity impacts (up to 85–90% reduction) compared with petroleum-based benchmarks, while FAME and DES exhibit outcomes highly dependent on allocation rules and baseline datasets. When including application materials, cotton wipes dominate total environmental burdens, emphasizing that system design outweighs solvent substitution in improving sustainability. The study provides reproducible data and methodological insights for integrating LCIA into conservation decision-making, contributing to the transition toward evidence-based and environmentally responsible heritage practices. Full article

LACMA’s 19th-century Tibetan Altar Table with Auspicious Symbols is characterized by a complex stratigraphy comprising animal glue-based ground and paint layers, a presumably original tung oil-based varnish, and a dark surface layer composed of a complex mixture of paraffinic wax, shellac, and rapeseed oil, which obscures the object’s original decorative scheme. This study examines the use of nanostructured fluids and organic solvents confined within hydrogels and organogels for the selective removal of the dark surface layer while preserving the underlying paint and varnish. Following the analysis of the artwork’s constituent materials, cleaning tests were conducted and evaluated using visible and ultraviolet fluorescence (UVF) imaging, spectrophotometry, and digital microscopy. The homogeneous absorption of solvent mixtures by the organogels was assessed through gas chromatography–mass spectrometry (GC–MS). Results indicate that confining cleaning fluids within the gels’ porous networks significantly improved solvent retention and control of fluid release. While conventional cleaning methods proved insufficiently selective, the gradual release of a nanostructured fluid containing a small amount of benzyl alcohol, combined with the nanostructural properties of the poly(vinyl alcohol)–sebacic acid (PSA2) hydrogel, enabled targeted removal of the surface layer while preserving the integrity of the underlying layers. Full article

To address the challenges of difficult recovery, significant environmental hazards associated with homogeneous catalysts, and insufficient catalytic activity of heterogeneous supports in the catalytic dehydration of fructose to produce 5-hydroxymethylfurfural (5-HMF), this study employs a straightforward nitric acid modification method to prepare an acid-activated silica gel catalyst for application in this reaction system. Through systematic investigation of the influence of modification conditions on catalyst performance and economic benefits, optimal reaction conditions were determined: DMSO as the solvent, nitric acid-modified silica gel as the catalyst, a reaction temperature of 120 °C, a solid–liquid ratio of 1:30 (g∙mL⁻¹), and a fructose-to-catalyst mass ratio of 1:1. Under these conditions, the maximum 5-HMF yield reached 91.6%. Characterization via specific surface area, pore size analysis, and acid/base site characterization (NH₃-TPD) revealed that nitric acid modification preserved the silica gel’s pore structure. Through oxidative cleaning, etching to expose silanol groups, and inducing surface defects, this process significantly increased the number of acid sites on the silica gel surface, thereby enhancing catalytic activity. This study presents a low-cost, easily recoverable, and environmentally friendly heterogeneous catalytic strategy for the efficient conversion of fructose into 5-HMF. It also provides experimental guidance for the targeted functionalization of silica-based catalytic materials, holding significant implications for advancing the high-value utilization of biomass resources. Full article

This study aimed to evaluate the effect of adding extracts obtained from by-products on the physicochemical and functional properties of cleansing gels. Micellar extraction (2% decyl glucoside solution in water) was performed on secondary raw materials: banana peel (BP), pomegranate peel (PP), tomato pomace (TP), and grape pomace (GP). The extracts were analyzed for soluble substances and active compounds (polyphenols, carotenoids, and vitamin C). Cleansing gels containing plant extracts were also prepared and evaluated for their color and physicochemical and functional properties. The extracts contained natural polyphenols (10.99–16.54 mg·100 mL⁻¹), carotenoids (1.391–2.402 mg·mL⁻¹), and vitamin C (0.651–1.529 mg·100 mL⁻¹). The extract-enriched gels showed altered color (lower brightness, greater redness and yellowness), enhanced foaming properties, and modified viscosity (402.9–416.8 mPA for BP and GP; lower for PP and TP). The pH of the gels ranged from 5.391 to 5.917, which is within the physiological range of human skin. Dissolution times were reduced by up to 60% compared to the control, with PP extract producing the shortest time of 15.7 min. These results indicate that plant by-product extracts can improve both the functional performance and skin compatibility of cleaning gels. Full article

We present an exploration of an overlooked process in gel cleaning that promotes efficient cleaning of discoloration and stains from artworks on paper: adsorption. Agarose, in both solid and gelled forms, is an efficient adsorbent of crystal violet, which is used here as a marker to assess the capability of a system to immobilize solutes. Incorporating additional adsorbents, either 1% by mass microcellulose or silica gel, into the gel before casting greatly improves the efficiency of removing and retaining dye from water. This addition induces a slight (2×) increase in the elastic modulus but results in no impactful change in the handling properties for conservation practice. We show that the addition of silica gel increases the efficacy of removing water-soluble degradation products from a sheet of historic book paper. A case study of a water-damaged eighteenth-century print, with element maps collected using mapping µX-ray fluorescence analysis before and after gel cleaning, demonstrates that microcellulose-containing gels can be used to remove water-soluble salts from the print. This work provides a new methodology for tailoring gels to target specific conservation treatment outcomes. Specifically, efficient adsorption of solubilized material increases the efficacy of the gel cleaning and minimizes redeposition. Full article

Background: scleroglucan, an extracellular polysaccharide with gel-forming, thickening, and stabilizing properties, was used as a structure-forming agent in low-fat yogurt formulations. The aim of this study was to evaluate its influence on the fermentation process and the physicochemical, rheological, textural, microstructural, and sensory properties of the yogurts. Methods: control samples were formulated with the addition of skim milk powder (SMP), whereas experimental yogurts contained scleroglucan at concentrations of 0.25%, 0.5%, and 1.0% (w/w). The fermentation kinetics, acidity, color, syneresis, rheological behavior, texture profile, microstructure, and volatile compounds were analyzed during storage. Results: the results showed that scleroglucan slowed acidification and increased the apparent viscosity, yield stress, and firmness of yogurts, while completely eliminating syneresis. Scleroglucan also modified the volatile profile by decreasing acetaldehyde and increasing 2,3-pentanedione levels during storage. The survival of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was not affected. Conclusions: the yogurt containing 1.0% scleroglucan was rated highest in overall acceptability. These findings demonstrate that scleroglucan can serve as a natural, clean-label stabilizer and an alternative to skim milk powder in low-fat set-style yogurts. 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

Geothermal energy, recognized as a sustainable and clean resource, is playing an increasingly critical role in the global shift toward low-carbon energy systems. Nevertheless, the exploitation of fractured geothermal reservoirs is often impeded by severe lost circulation during drilling, where conventional plugging materials fail under high-temperature, high-salinity, and high-pressure conditions due to inadequate mechanical strength, poor thermal resistance, and lack of self-adaptive sealing behavior. In response, self-healing materials have emerged as an innovative strategy for developing intelligent lost circulation control technologies. Herein, we report a novel self-healing gel (XFFD) synthesized via inverse emulsion polymerization using acrylamide (AM), acrylic acid (AA), p-nitroblue tetrazolium (PNBT), and modified silica nanoparticles (PAS). The resulting material exhibits exceptional thermal stability, with decomposition onset above 356 °C, as determined by thermogravimetric analysis. Rheological and mechanical assessments reveal outstanding viscoelasticity, moderate swelling capacity (4.17-fold in deionized water), and a high self-recovery efficiency of 91.15%, accompanied by a bearing strength of 3.65 MPa. Mechanistic investigations indicate that the autonomous repair capability stems from dynamic non-covalent interactions—primarily hydrogen bonding and ionic associations—enabled by amide and carboxyl groups within the polymer network. Sand bed filtration tests under simulated geothermal conditions (150 °C, 8% salinity) demonstrate that XFFD forms a robust sealing barrier with significantly shallower invasion depth compared to conventional materials such as sulfonated asphalt and calcium carbonate. This work presents an effective self-healing gel system that ensures reliable wellbore strengthening and fluid loss control in challenging high-temperature, high-salinity geothermal drilling operations. Full article

Addressing the issues of low permeability, stress sensitivity in CBM reservoirs, and severe reservoir damage from traditional fracturing fluids, we prepared a Gemini surfactant (designated GEM-CBM) for CBM development using ethanolamine, epichlorohydrin, and alkylamidopropyl dimethylamine as feedstocks. On this basis, we further developed a clean fracturing fluid system. The synthesis process of GEM-CBM was optimized via single-factor and orthogonal experiments. The surface activity of GEM-CBM was assessed through surface tension measurements, whereas the sand-carrying capacity, the rheological properties, gel-breaking performance, and reservoir compatibility were comprehensively examined. The optimal conditions for GEM-CBM are listed as follows: the molar ratio of intermediate to alkylamidopropyl dimethylamine being 1:2.2, reacted at 80 °C for 20 h, with a conversion rate of 96.5%. FTIR verified the existence of characteristic functional groups, and EA results matched the theoretical molecular composition. GEM-CBM has good performance, with a critical micelle concentration (CMC) of 19.0 μmol/L and a surface tension at CMC (γCMC) of 37.44 mN/m. The optimized clean fracturing fluid (formulation: 2.3% GEM-CBM + 0.3% Tween-80 + simulated formation water with 150,000 mg/L mineralization) exhibited a viscosity of 82 mPa·s (66.7% viscosity retention rate) after being subjected to 100 min of shearing at 90 °C and 170 s⁻¹. At 90 °C, the proppant settlement velocity was less than 0.15 mm/s, and complete gel breaking was achieved within 30 min without residues. For coal cores from the Qinshui Basin, the permeability recovery rate reached 78.6%. The permeability recovery rate of coal cores from the Qinshui Basin reached 78.6%. This fracturing fluid realizes viscosity enhancement and sand carrying via the worm-like micellar network formed by GEM-CBM, inducing minimal damage to CBM reservoirs and offering technical support for efficient CBM extraction. Full article

Natural polysaccharides are used for very different applications and are particularly exploited for preparing hydrogel materials. For instance, gels based on different carbohydrate polymers have been applied to remove unwanted materials from the surface of cultural heritages items. This study was focused on the preparation of novel physical hydrogels suitable for the cleaning of sensitive materials like wood and paper, i.e., to remove the soil from their surface. For this purpose, alginate biopolymer was used and ionically crosslinked with six different amines, in the presence of N-hydroxysuccinimide as a co-gelling agent. All the synthetized gel materials were characterized by a multianalytical approach, using different techniques such as FT-IR, thermal analysis, SEM-EDS, mechanical tests, and evaluation of moisture properties. All the results showed that the introduction of the investigated amines improved the original properties of alginate and provided good cleaning properties when applied to sensitive surfaces. Full article

To address limitations such as cleaning difficulties or secondary contamination/damage of cultural relics caused by the uncontrollable diffusion of water/cleaning agent/dirty liquids during the cleaning process in traditional cleaning methods, this study, using cotton textiles as an example, systematically investigated the cleaning efficacy of four in situ methods (blank gel, cleaning gel, ultrasonic emulsification, and gel + ultrasonic emulsification synergistic cleaning) on eight types of stains, including sand, clay, rust, blood, ink, oil, and mixed solid/liquid stains. Building upon this, this study proposed an efficient, targeted, in situ, and controllable cleaning strategy tailored for fragile, stained textile relics. Results demonstrated that, regardless of the stain type, the synergistic cleaning method of G+U (gel poultice + ultrasonic emulsification) consistently outperformed the cleaning methods of blank gel poultice, cleaning gel poultice, and ultrasonic emulsification. Furthermore, the gel loaded with cleaning agents was always more effective than the blank gel (unloaded cleaning agents). The poultice methods of blank gel and cleaning gel were better suited for solid stains, while the ultrasonic emulsification cleaning method was more effective for liquid stains. Meanwhile, it was also found that the optimal cleaning method proposed in this study (the G+U synergistic cleaning method) was a cleaning method that restricted the cleaning agent within the gel network/emulsion system, and utilized the porous network physical structure of gel, the chemical action of emulsion’s wetting/dissolving dirt, and the cavitation synergistic effect of ultrasound to achieve the targeted removal of contaminants from relics’ surfaces. Crucially, the cleaning process of G+U also had the characteristics of controlling the cleaning area at the designated position and effectively regulating the diffusion rate of the cleaning solution within the treatment zone, as well as the reaction intensity. Therefore, the proposed optimal (the synergistic cleaning method of G+U) cleaning method conforms to the significant implementation of the “minimal intervention and maximal preservation” principle in modern cultural heritage conservation. Consequently, the synergistic cleaning method of G+U holds promise for practical application in artifact cleaning work. Full article

Archeological ceramics represent values that necessitate preservation from various factors of deterioration. Cleaning processes are beneficial in the preservation of these ceramics. An abundance of cleaning technique and process information exists within the literature. This study examines the current state of both traditional and advanced cleaning techniques employed for archeological ceramics. The review discusses a wide range of commonly used cleaning techniques, including mechanical, dry and wet processes, as well as chemical approaches. Additionally, more recent laser, plasma, and biocleaning methods are discussed. The effectiveness of these techniques is examined, as well as potential damage or surface modifications to the ceramics. The selection of a cleaning method for ceramics depends on the specific characteristics of the ceramic (i.e., porosity, glaze, slip red-slipped, etc.), its state of conservation, and the nature and thickness of the fouling or encrustations. Careful selection and testing of chemical solutions are crucial to prevent damage. While chelating agents like EDTA effectively dissolve crusts and salts, uncontrolled application can weaken ceramic structures. Laponite, natural clay minerals, resins and organic gels (xanthan gum, agar, cellulose powder) are effective in removing contaminants from the surfaces of without causing damage. Environmentally friendly methods such as biocleaning, Pulsed Laser Cleaning, and plasma are effective but underutilized, requiring further investigation. This review emphasizes the growing potential of sustainable and non-invasive methods to complement or replace traditional approaches. Its main contribution lies in providing a critical synthesis that bridges conventional and innovative techniques, outlining research gaps for more effective and eco-responsible conservation of archeological ceramics. Full article