Search Results (44)

Objective: This study evaluated the efficacy of a novel interproximal fluoride delivery device, Cav-Aid^®, in remineralizing initial proximal caries, comparing it with conventional fluoride treatments. Methods: Initial caries lesions were produced on bovine enamel blocks by subjecting the blocks to a 3-day demineralization process by plaque growth in a mixed-species microbial caries model. After demineralization, the baseline surface microhardness (SMHb) was measured. The blocks were embedded into cavities prepared on the proximal surfaces of extracted human teeth to simulate natural interproximal contacts. The teeth were randomly assigned to six treatment groups (20/group): artificial saliva (AS), Cav-Aid^® only (CA), Cav-Aid^®/fluoride toothpaste (CA+F), fluoride varnish applied via flossing (FV-Floss), fluoride varnish applied via painting on the interdental cleavage (FV-Paint), and daily fluoride mouthrinse (F-Mouthrinse). The samples then underwent a 14-day pH cycling protocol to simulate remineralization conditions. The post-treatment SMH (SMHr) was measured. Statistical analysis comprised paired t-tests and ANOVA/Tukey’s post hoc comparisons (p < 0.05). Results: All fluoride-treated groups exhibited significant increases in SMHr compared with SMHb (p < 0.001). CA+F group showed the highest percentage remineralization (27.39%), followed by CA (22.16%), then the FV and mouthrinse groups (9.25–11.80%). The AS group exhibited the lowest remineralization (4.89%). CA+F demonstrated significantly greater remineralization than FV or mouthrinse (p < 0.05). However, there was no significant difference between CA alone and CA+F. Also, there was no significant difference between CA alone and FV-Floss or FV-Paint (p > 0.05). Conclusions: Within the limit of the present study, the Cav-Aid^® targeted fluoride delivery system demonstrated greater efficacy than FV alone in interproximal remineralization. Dual-modality fluoride treatments (CA+F) provided the greatest remineralization benefits, highlighting the importance of sustained fluoride exposure. Full article

Cultural Heritage is a vital socioeconomic driver that must contend with works of art continuously exposed to degradation processes, which are further exacerbated by climate change. Aged coatings, varnishes, and soil can compromise the appearance of artworks, preventing their preservation and valorization. In response, soft matter and colloidal systems, such as nanostructured cleaning fluids (NCFs), have proved to be valuable solutions for safely and effectively cleaning works of art. Here, a novel cleaning system is proposed, for the first time employing microgels of poly(N-isopropylacrylamide) (PNIPAM) with surface chains of oligoethylene glycol methyl ether methacrylate (OEGMA) to favor shear deformation by lubrication. These microgels are loaded with NCFs featuring “green” solvents and different kinds of bio-derived or petroleum-based surfactants (non-ionic, zwitterionic). Rheological characterization of the combined systems highlighted a sharp transition from solid to liquid-like state in the 21–24 °C range when the zwitterionic surfactant dodecyldimethylamine oxide was used; the system displays a solid-like behavior at rest but flows easily at intermediate strains. At slightly higher temperature (>24 °C), an inversion of the G′, G″ values was observed, leading to a system that behaves as a liquid. Such control of rheological behavior is significant for feasible and complete removal of soiled polymer coatings from textured ceramic surfaces, which are difficult to clean with conventional gels, without leaving residues. These results position the PNIPAM-OEGMA microgels as promising cleaning materials for the conservation of Cultural Heritage, with possible applications also in fields where gelled systems are of interest (pharmaceutics, cosmetics, detergency, etc.). Full article

The study presented in this paper investigates the influence of coating polymers on the acoustic properties of resonant spruce wood. It evaluates absorption, acoustic reflection, and resonance frequency spectrum characteristics in both unvarnished and varnished samples, with the interface between the coating polymer and the wood modifying the acoustic response. The novelty of the research consists in evaluating the acoustic and dynamic parameters of resonant spruce wood boards, varnished with varnishes with different chemical properties (oil-based varnish, spirit varnish, nitrocellulose varnish). The study focuses on the influence of the type of varnish and the thickness of the varnish film on the frequency spectrum, damping coefficient, quality factor, acoustic absorption coefficient, and sound reflection. The sound absorption coefficient increases with the number of varnish layers and is influenced by the sound’s frequency range, the type of varnish, and the quality of the wood—factors that collectively enhance acoustic performance. For instance, oil-based varnish applied in 5 or 10 layers contributes to a fuller sound at a frequency of 1.5 kHz. In contrast, spirit varnish, which has a lower acoustic absorption coefficient at this frequency, and a reduced damping coefficient, can lead to a nasal tone, although the frequency spectrum turns out to have the richest. Applying more than 10 layers of varnish softens the sound when using oil-based varnish but sharpens it with spirit varnish on resonant wood. Thus, the acoustic performance of a soundboard can be tailored by selecting the appropriate varnishing system and number of layers applied. However, a detailed analysis of the timbre of musical instruments finished with these varnishes is necessary to confirm their influence on the acoustic quality of the instruments. Full article

The curing process of hair-pin motor stator insulation is critical, as residual stress increases the risk of partial discharge and shortens a motor’s lifespan. However, studies on the stress-induced defects during insulation varnish curing remain limited. This research integrates three-dimensional numerical simulations and experimental analysis to develop a curing model based on unsaturated polyester imide resin, aiming to explore the mechanisms of residual stress formation and optimization strategies. A dual fiber Bragg grating (FBG) sensor system is employed for simultaneous temperature and strain monitoring, while curing kinetics tests confirm the self-catalytic nature of the process and yield the corresponding kinetic equations. The multi-physics simulation model demonstrates strong agreement with the experimental data. The results show that optimizing the curing process reduces the maximum stress from 45.1 MPa to 38.6 MPa, effectively alleviating the stress concentration. These findings highlight the significant influence of the post-curing temperature phase on residual stress. The proposed model offers a reliable tool for stress prediction and process optimization in various insulating materials, providing valuable insights for motor insulation system design. Full article

The use of organic solvents, particularly those of a non-polar nature, is a common practice during cleaning operations in the restoration of polychrome artworks and metallic artifacts. However, these solvents pose significant risks to the health of operators and the environment. This study explores the formulation of innovative gels based on non-polar solvents and cellulose derivatives, proposing a safe and effective method for cleaning metallic artworks. The study is focused on a toxic apolar solvent, Ligroin, identified as one of the most widely used solvents in the cultural heritage treatments, and some “green” alternatives such as Methyl Myristate and Isopropyl Palmitate. The main challenge lies in overcoming the chemical incompatibility between non-polar solvents and polar thickening agents like cellulose ethers. To address this problem, the research was based on a hydrophilic–lipophilic balance (HLB) system and Hansen solubility parameters (HSPs) to select appropriate surfactants, ensuring the stability and effectiveness of the formulated gels. Stability, viscosity, and solvent release capacity of gels were analyzed using Static Light Multiple Scattering (Turbiscan), viscometry, and thermogravimetric analysis (TGA). The efficacy of cleaning in comparison with Ligroin liquid was evaluated on a metal specimen treated with various apolar protective coatings used commonly in the restoration of metallic artifacts, such as microcrystalline waxes (Reswax, Soter), acrylic resins (Paraloid B44), and protective varnishes (Incral, Regalrez). Multispectral analysis, digital optical microscopy, FTIR spectroscopy, and spectrocolorimetry allowed for the assessment of the gels’ ability to remove the different protective coatings, the degree of cleaning achieved, and the presence of any residues. The results obtained highlight the ability of the formulated gels to effectively remove protective coatings from metallic artifacts. Cetyl Alcohol proved to be the most versatile surfactant to realize a stable and efficient gel. The gels based on Methyl Myristate and Isopropyl Palmitate showed promising results as “green” alternatives to Ligroin, although in some cases, they exhibited less selectivity in the removal of protective coatings. Full article

This paper presents the removal of a non-original varnish from the surface of a painting by Wassily Kandinsky based on prior experimentation carried out on mock-ups, which were made according to the original artistic technique and painting stratigraphy. Due to a generally serious state of conservation, the artwork underwent several treatments over the years that have changed its original appearance. This work focused on the study and characterization of the ketone-based varnish present on the surface to outline how this non-original film layer interacted with paint layers and increased deterioration phenomena. Aiming to identify the most suitable approach for the artwork, some preliminary cleaning tests were made on artificially aged mock-ups. A multi-analytical investigation was carried out through non-invasive and invasive techniques to support all steps of the conservation treatment. By comparing cleaning results on mock-ups, a suitable protocol was developed and applied to the original painting. The best results were obtained by using the Nanorestore Gel^® Dry MWR (Medium Water Retention) with ethanol. The project has shown that the dissolving power of the solvent can effectively be controlled and limited at the surface by confining it to the nanostructure of the gel, thus minimizing the risk of interaction with the original paint layers. Full article

This study analyzes the influence of energy generated by emitters on the adhesive properties of varnish coatings in multilayer UV systems. The experimental material, in the form of a cell board finished with UV varnish products, was prepared on a prototype line under the conditions of Borne Furniture in Gorzów Wielkopolski. The roughness and wettability were measured using a OneAttension tensiometer integrated with a topographic module, taking into account the Wenzel coefficient. The adhesion of the examined systems was verified using the PositiTest AT-A automatic pull-off device. Energy consumption by the prototype production line was compared to the standard line, utilizing mercury emitters and mercury emitters with added gallium. Energy consumption was calculated for selected variants. The influence of the Wenzel coefficient on the wettability angle was observed. Significant differences between contact angles (CA and CAc) were noted for coatings formed with sealers (stages I and II). The largest discrepancies, reaching up to 30 degrees, were recorded at the lowest UVA and UVV doses of 26 mJ/cm². In adhesion tests, values below 1 MPa were obtained. Insufficient energy doses in the curing process of UV systems led to delamination between the coatings. Five variants were selected where delamination within the substrate predominated (˃90% A) and were characterized by the lowest energy consumption in the processes. Topographic images helped identify the presence of various surface microstructures at different stages of the production cycle. The greatest energy savings, up to 50%, were achieved in stages III and IV of the technological process. Full article

This study aimed to assess the antibiofilm effects of dentin desensitizers using a modified Robbins device flow cell system. The test desensitizers were Saforide, Caredyne Shield, and Clinpro White Varnish. Standardized dentin specimens were prepared from human single-rooted premolars, treated with one of the materials, and mounted on the modified Robbins device flow cell system. Streptococcus mutans biofilms were developed for 24 h at 37 °C under anaerobic conditions. Scanning electron microscopy, fluorescence confocal laser scanning microscopy, viable and total cell counts, acid production, and gene expression analyses were performed. A wavelength-dispersive X-ray spectroscopy electron probe microanalyzer was used to analyze the ion incorporations. Clinpro White Varnish showed the greatest inhibition, suggesting its suppression of bacterial adherence and transcription of genes related to biofilm formation. Saforide reduced only the number of viable bacteria, but other results showed no significant difference. The antibiofilm effects of Caredyne Shield were limited. The uptake of ions released from a material into dentin varies depending on the element. Clinpro White Varnish is effective for the short-term treatment of tooth sensitivity due to dentin demineralization. It prioritizes remineralization by supplying calcium and fluoride ions while resisting biofilm formation. Full article

This article concerns research into the influence of the energy dose distributed by UV lamps on selected parameters of varnish coatings formed during the varnishing process of lightweight cellular panels. The lightweight cellular board used in the study was made according to an innovative solution. The surface finishing of the boards was carried out using the roller method in combination with digital and analogue printing under industrial conditions. Contact angle measurements of the obtained varnish coatings were carried out, from which the surface free energy was calculated. In addition, interlayer adhesion was assessed by pull-off tests. Irrespective of the radiation dose, higher contact angle values (54.3–89.9°) were recorded for the last two applied layers (base coat 2 and base coat 3) than for the other coatings (39.6–64.1°). For all systems tested, the γs^p component showed lower values (2.25–28.99 mJ/m²) than γs^d (28.66–32.80 mJ/m²). The adhesion test results ranged from 0.5 to 0.9 MPa, although with varying types of delamination. Based on the test results, the most favourable variants from the furniture manufacturer’s point of view were selected that provided the desired level of adhesion, in which cohesive damage located within the substrate (A) predominated. Full article

In this work, we present a compact LIBS sensor developed for characterization of samples on a crime scene following requirements of law enforcement agencies involved in the project. The sensor operates both in a tabletop mode, for aside measurements of swabbed materials or taken fragments, and in handheld mode where the sensor head is pointed directly on targets at the scene. The sensor head is connected via an umbilical to an instrument box that could be battery-powered and contains also a color camera for sample visualization, illumination LEDs, and pointing system for placing the target in focus. Here we describe the sensor’s architecture and functionalities, the optimization of the acquisition parameters, and the results of some LIBS measurements. On nano-plotted traces at silica wafer and in optimized conditions, for most of the elements the detection limits, in term of the absolute element masses, were found to be below 10 picograms. We also show results obtained on some representative materials, like fingerprints, swabbed soil and gunshot residue, varnishes on metal, and coated plastics. The last, solid samples were used to evaluate the depth profiling capabilities of the instrument, where the recognition of all four car paint layers was achieved. Full article

In this study, various diamine monomers were used to synthesize aramid polymer films via a low-temperature solution condensation reaction with diacid chloride. For diamines with relatively high basicity, the reaction system became opaque because amine salt formation inhibited polymer synthesis. Meanwhile, low-basicity diamines with strong electron-withdrawing groups, such as CF₃ and sulfone, were smoothly polymerized without amine salt formation to provide highly viscous solutions. The acid byproduct HCl generated during polymerization was removed by adding propylene oxide to the reaction vessel and converting the acid into highly volatile inert substances. The resulting solutions were used as varnishes without any additional purification, and polymer films with an excellent appearance were easily obtained through a conventional casting and convection drying process. The films neither tore nor broke when pulled or bent by hand; furthermore, even when heated up to 400 °C, they did not decompose or melt. Moreover, polymers prepared from 2,2-bis(trifluoromethyl)benzidine (TFMB) and bis(4-aminophenyl)sulfone (pAPS) did not exhibit glass transition until decomposition. The prepared polymer films showed a high elastic modulus of more than 4.1 GPa and a high tensile strength of more than 52 MPa. In particular, TFMB-, pAPS-, and 2,2-bis(4-aminophenyl)hexafluoropropane-based polymer films were colorless and transparent, with very high light transmittances of 95%, 96%, and 91%, respectively, at 420 nm and low yellow indexes of 2.4, 1.9, and 4.3, respectively. Full article

In analogue and digital printing technologies, from 3 up to 12 layers of lacquer products are applied. Technological parameters significantly influence the adhesion in the coating system. This article refers to the analysis of the influence of selected technological parameters, such as the number of layers, energy doses distributed by the radiators, and line speed, on the topography and adhesion of varnish coatings formed in the process of varnishing with rollers and UV-curing systems. The appropriately prepared surface can be used as a background layer for the analogue and digital printing technology. Manufacturers must adapt the production process to the particular varnish to obtain finished products with the best possible performance properties. The state of surface free energy and finally adhesion can be assessed by theoretically determining the possibility of an adhesive bonding between the product and the substrate, taking into account the assumptions of the adsorption theory of adhesion and measurement of the contact angle (Θ). An experimental confirmation of adhesion measurements included removing the coatings from the substrate via stamps glued to the coating. Full article

Background and Objectives: This prospective, comparative, double-cohort study aimed to compare the efficacy of silver diamine fluoride and potassium iodide (38% SDF+KI; Riva Star^®) with sodium fluoride varnish (5% NaF; Duraphat^®) in hypersensitive carious lesions in primary teeth to evaluate caries arrest and hypersensitivity relief. Materials and Methods: This study included thirty 2–5-year-olds (mean age = 3.67 ± 1.06 years; 16 males and 14 females) who required a desensitizing treatment for hypersensitive carious defects with visible dentin. A total of 15 of the participants were consecutively allocated to treatment with 5% NaF, and they were further compared to an equal number of participants treated with 38% SDF+KI solutions (n = 15). The treatments were performed following clinical evaluation of caries activity using the International Caries Classification and Management System (ICCMS^TM) and the Bjørndal criteria (score of 0–9). Parental-reported hypersensitivity was evaluated using a visual analogue scale (0–10 = no to severe pain). Results: Clinical variables were evaluated at baseline and three months after treatment. Thereafter, a significant decline in hypersensitivity/pain led to lower final scores in the Riva Star^® group (0.40 ± 1.12, p = 0.002) than in the Duraphat^® group (1.40 ± 2.20, p = 0.004). The caries arrest effect was significantly higher in the Riva Star^® group (86.7%) compared to the Duraphat^® group three months after treatment (13.3%, p < 0.001). In both groups, there were no statistically significant differences in the children’s behavior before, during, and after treatment. Conclusions: Ultimately, with both fluoride therapies reducing hypersensitivity/pain significantly, treatment with 38% SDF+KI was clearly more effective in caries arrest than 5% NaF varnish after a 3-month period. Full article

Radars in the W-band are being integrated into car bumpers for functionalities such as adaptive cruise control, collision avoidance, or lane-keeping. These Advanced Driving Assistance Systems (ADAS) enhance traffic security in coordination with Intelligent Transport Systems (ITS). This paper analyzes the attenuation effect that car bumpers cause on the signals passing through them. Using the free-space transmission technique inside an anechoic chamber, we measured the attenuation caused by car bumper samples with different material compositions. The results show level drops lower than 1.25 dB in all the samples analyzed. The signal attenuation triggered by the bumpers decreases with the frequency, with differences ranging from 0.55 dB to 0.86 dB when comparing the end frequencies within the radar band. Among the analyzed bumper samples, those with a thicker varnish layer or with talc in the composition seem to attenuate more. We also provide an estimation of the measurement uncertainty for the validation of the obtained results. Uncertainty analysis yields values below 0.21 dB with a 95% coverage interval in the measured frequency band. When comparing the measured value with its uncertainty, i.e., the relative uncertainty, the lower the frequency in the measured band, the more accurate the measurements seem to be. Full article

This study presents the current literature regarding the investigation of varnish contamination among the various types of lubricant contaminations. As the duration of use of lubricants increases, the lubricant deteriorates and may become contaminated. Varnish has been known to cause filter plugging, sticking of the hydraulic valves and fuel injection pumps, flow obstruction, clearance reduction, poor heating and cooling performance, and increased friction and wear in various lubrication systems. These problems may also result in mechanical system failures, performance degradation, and increased maintenance and repair costs. To improve the problems caused by varnish contamination, an adequate understanding of varnish is required. Therefore, in this review, the definitions and characteristics, generating machinery, generating mechanisms, causes, measurement methods, and prevention or removal methods of varnish are summarized. Most of the data presented herein are reports from manufacturers related to lubricants and machine maintenance that are included in published works. We expect that this summary will be helpful to those who are engaged in reducing or preventing varnish-related problems. Full article