Gels are transversal materials with key applications in multiple scientific and technological sectors, including the preservation of Cultural Heritage that is a fundamental drive for socioeconomic resilience. Recently, the new class of twin-chain (TC) polymer gel networks was developed, using freeze-thaw (FT) cycles on solutions of polyvinyl alcohol (PVA) with two different hydrolysis degree and molar mass. Taking advantage of polymerpolymer phase separation in the pre-gel solutions, a sponge-like, interconnected porosity is templated in the hydrogels during FT, which concurs to boost the cleaning capability of the gels versus soil and aged coatings that jeopardize paintings and other iconic artworks. This review covers the latest developments in this new class of gels, and their use in the conservation of works of art. The TC gels allowed time-effective restoration of masterpieces (paintings by Picasso, Pollock, Lichtenstein), which would have been risky and time-consuming with conventional restoration materials in wet cleaning. The review discusses gelation mechanisms, the partial replacement or decoration of PVA with non-toxic synthetic or bio-based polymers, the counterintuitive role of gels' tortuosity in the cleaning process, and the upload of these gels with nanostructured cleaning fluids (microemulsions, micelles). Overall, the TC PVA hydrogels constitute an advanced tool to preserve Cultural Heritage and transfer it to future generations; moreover, they represent a class of sustainable soft matter materials with potential impact in several fields, spanning from detergency to the cosmetic, pharmaceutical and food industries, tissue engineering, and others.

This study focused on synthesizing polyvinyl alcohol (PVA) utilizing glutaraldehyde (GA) as a crosslinking agent and silicon dioxide (SiO2) nanopowder with titanium dioxide (TiO2) nanopowder to reduce or prevent the hydrophilic property of PVA. Integrating SiO2 and TiO2 into the PVA boosted the hydrophobicity, thermal properties, and self-cleaning of the PVA film. The characteristic properties of PVA/GA, PVA/SiO2/GA, and PVA/SiO2/TiO2/GA nanocomposites polymer membranes were investigated by gel content, swelling capacity, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction patterns (XRD), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and contact angle. The resulting PVA/5%SiO2/1%TiO2/GA nanocomposite exhibits much better physical properties than PVA/GA hydrogel (water absorbency from 3.1 g/g to 0.07 g/g and contact angel from 0 degrees to 125 degrees). In addition, the nanocomposite retains very low swelling properties. These prepared nanocomposites are promising in a variety of applications such as sand soil stabilizers, construction, and building works where they exhibit excellent water resistance performance. This study introduces a novel approach for creating hydrophobic polymeric membranes from hydrophilic polymeric materials to stabilize sandy soil effectively.

Given the significant damage rate observed during the transportation of current garlic combine harvesters in China, this study aims to design a new garlic combine harvester capable of achieving minimal harvest losses. The designed machine can simultaneously complete operations for garlic digging, clamping transport, seedling-bulb separation, soil cleaning, and fruit collection across two rows. Through the use of theoretical analysis and calculation of garlic harvesting operations, the key parameters of soil-breaking device, clamping transport device, length-limiting cutting device, and soil cleaning conveyor were determined. The BoxBehnken test technique was utilized within Design-Expert software, and orthogonal experiments were conducted with the unit's forward speed, digging depth, and soil-breaking angle as test factors, and the stem cutting rate and bulb damage rate as test indices. The test results showed that when the unit's forward speed, digging depth, and soil-breaking angle were 0.49 m/s, 100 mm, and 20 degrees, respectively, the working parameter combination was the best, and the rate of stem cutting and damage were 95.71% and 3.10%, respectively. The findings from the field experiment and optimization aligned closely. This study can provide reference for the development of mechanized garlic harvesting.

External contamination (soiling) of the incident surface is a major limiting factor for solar technologies. A 5year field glass coupon study was conducted to better understand external contamination and its effects; compare cleaning methods and the use of preventative coatings; and explore the abrasion resulting from cleaning to advise on accelerated abrasion testing. Test sites included the cities of Dubai (UAE), Kuwait City (Kuwait), Mesa (AZ), Mumbai (India), and Sacramento (CA). Through the 5-year cumulative study, dry brush, water spray, and wet sponge and squeegee cleaning methods were compared to no cleaning. Optical microscopy was used to obtain images, including representative color images, grayscale images for object analysis, and oblique images for coating integrity assessment. A thresholding protocol was developed to analyze and distinguish specimens using the ImageJ software. Optical performance was quantified using a spectrophotometer, including comprehensive optical characterization (transmittance, reflectance, and absorptance in addition to forward- and back- scattering). Atomic force microscopy was used to verify the abrasion damage morphology, including the width and depth of surface scratches. Analysis of the results included correlation of optical performance and particle area coverage, rank order (by coating or location), and the acceleration factor for abrasion damage. The efficacy of external cleaning was more readily distinguished from the effectiveness of antisoiling coatings. The acceleration factor for dry brush cleaning of a porous silica coating was found to be on the order of unity.

Removing unwanted materials, such as organic coatings and soil, from the cultural relic surface is a complex and significant task in the field of cultural heritage conservation. Microemulsion-loaded gel can effectively and safely remove those organic coatings and soil. Here, we employed a simple solvent exchange strategy to prepare a microemulsion-loaded polyvinyl alcohol/polyethyleneimine (PVA/PEI) hydrogel. First, PVA and PEI were dissolved into DMSO to form a gel. Then, the gel was immersed into a microemulsion composed of water, ethyl acetate, propylene carbonate, sodium dodecyl sulfate, and 1-pentanol to exchange DMSO. Microemulsion-loaded PVA/PEI hydrogel can be synthesized by completely substituting DMSO. To investigate the microstructure, rheological properties, and mechanical properties of the gel, scanning electron microscopy, a rheometer, and a universal testing machine were used, respectively. Fourier transform infrared (FT-IR) analysis was conducted to explore the synthesis mechanism and confirm the successful loading of microemulsion within the microemulsion-loaded PVA/PEI hydrogel. Furthermore, FT-IR, a depth-of-field microscope, and a glossmeter were utilized to evaluate the cleaning efficiency of the microemulsion-loaded PVA/PEI hydrogel for removing animal glue and soil from the surfaces of cultural relics. Moreover, an X-ray fluorescence spectrometer was used to analyze the element component of the ancient coin. The application results showed that the microemulsion-loaded PVA/PEI hydrogel can effectively remove animal glue from an ancient wall painting surface. Moreover, it is capable of removing soil from an ancient coin surface as well, which helped to confirm the age of the coin. This offers a novel method to prepare microemulsion-loaded hydrogel and demonstrates great potential in the cleaning for cultural heritage.

Nowadays, renewable energies are capturing the world's attention, particularly in light of the phenomenon of climate change and carbon dioxide emissions, which have caused major environmental damage. As a result, many investors have recently focused on developing investments in renewable energy projects worldwide, specifically photovoltaic and concentrated solar power plant projects. These solar technologies are considered among the most profitable solutions for generating power from a natural, free, and unlimited energy source. This review paper discusses one of the most significant issues affecting the performance of these solar systems, which is known as soiling. It has been supported by several studies in various nations with different climatic conditions, which offered accurate empirical data on the degradation rate of photovoltaic and concentrated solar power systems' production due to the soiling effect. Furthermore, it provides various mitigating soiling ways, including manual and autonomous cleaning methods for both solar technologies. Ultimately, it summarizes each cleaning technique's main advantages and drawbacks, specifying its applicability according to the location characteristics and climatic conditions. Additionally, the review results reported in this work are intriguing enough to warrant further development of concentrated solar power and photovoltaic technologies.

In outdoor environment, the exterior walls surface of buildings always suffers from damages caused by ultraviolet radiations, temperature variation, abrasion and erosion phenomenon, dust pollution, and microbial adhesion: Thereby reducing their durability over time. In order to overcome these obstacles, the superhydrophobic coatings can be an advantageous solution to ensure long-term stable use by improving the exterior concrete walls durability. In this line, a fluorine-free water-repellent coating was developed through sol-gel method and successfully applied to concrete substrates by dip-coating technique. The coating was formulated with low surface energy polydimethylsiloxane (PDMS) and polymeric silica (PS) to simultaneously modify the microstructure and chemical properties of concrete substrate surface. The coated concrete substrate showed super-hydrophobicity with high water contact angle (WCA) over than 150 degrees. Besides, the self-cleaning property, mechanical robustness, stability under UV irradiations, resistance to temperature and humidity were investigated. The results indicated that the coated concrete substrate cannot be soiled by dust and can resist over than 300 cycles of abrasion test. It also presents resistance to temperature of 45 degrees C associated with a humidity of 80% during 720 hours and showed excellent resistance to prolonged exposure to UV irradiations during 1440 hours. Natural out-door aging tests have shown that the superhydrophobic coating is weather resistant.

In this work, a tribological approach was used to distinguish the synergistic effects of mechanical removal and chemical removal (i.e. dissolution) of a layer of representative food soil from a solid surface, using a tribometer, Mini Traction Machine (MTM). Gravimetric and wear measurements of the soil were used to calculate the cleaning rates of burnt tomato puree on a stainless-steel disc, and the corresponding frictional characteristics offers insight of the mechanical removal. The cleaning due to soil dissolution (chemical removal) was quantified by UV-Vis measurements. The overall cleaning rates of food soil featured a linear reduction in mass over time, with a scaled removal rate k = 0.0046 s-1 (5 N applied force and 100 mm s-1 relative velocity), for most cases studied. It was observed that the cleaning rate can be improved with an increasing mechanical load or speed (50% from 1 to 2.5 N and 13% from 50 to 100 mm s-1), but is independent of the initial mass. UV-Vis measurements show that by increasing the load or speed the removal of chunks of burnt tomato puree was enhanced more than removal attributed to dissolution. Similar values of cleaning rates for most experimental parameters were extracted from both the gravimetric and wear measurements. Adhesion and cohesion measurements of the burnt tomato puree were conducted with a micromanipulator. It was found that adhesion forces are higher than cohesion for short soaking times, but for longer times the adhesion forces became weaker and with the additional shear rate in the MTM cleaning experiment, adhesion failure was observed in many cases by the end of the experiment. Indentation measurements showed the change in mechanical properties of the food foulant with a few minutes of soaking in water.

Biofouling on ships and offshore structures has always been a difficult problem to solve, which not only jeopardizes the structural strength but also brings great economic losses. Ultrasonic cavitation is expected to solve this problem due to its characteristics of no damage to structures and no pollution. Starting from the phenomenon and mechanism of ultrasonic cleaning, this paper introduces the application of ultrasonic cavitation in ship, pipeline and oil cleaning as well as ballast water treatment. By reviewing the existing studies, limitations such as insufficient ultrasonic parameter studies, lack of uniform cleanliness standards, and insufficient cavitation studies are summarized to provide traceable research ideas for improving ultrasonic cavitation technology and to guide the expansion and improvement of its applications.

Carpets are widely used in living spaces for beautiful appearance, heat, and sound insulation. Cleaning carpets is essential for both their lifespan and health and hygiene. Washing operations are carried out at regular intervals in carpet-washing factories.Industrial carpet washing operations must be done consciously because a significant amount of water and time is consumed during these processes. In addition, problems such as discoloration and strength losses may be encountered in delicate carpets. In this study, stained carpets were washed at mediums with and without ultrasound at room temperature at different times. Mud stain was used as an example of particle dirt. The original unwashed carpet without stain was taken as a reference and compared with the washed carpet by evaluating the color differences and changes in the yellowness indexto check the amount of stain removal. The color differences (Da*, Db*, DL*, DC*, Dh*, DE*) were close to zero, and the differences in the yellowness index were low, so it was concluded that the stained carpet was cleaned and turned to the original form after washing. The washing process was evaluated as successful because the color and yellowness index of the washed carpet were close to the unwashed carpet. Effects of washing type (with and without ultrasound), washing agent (with and without detergent), and washing time (30, 60, and 90 minutes) are significant for alpha=0,05 in washed carpets according to the original carpet. Interactions between parameters are also significant. If the washing conditions are consciously adjusted, ultrasonicwashing can be an alternative to the soaking process in carpet washing.With ultrasonic washing, it can be possible to shorten the duration of the wetting step and effectively clean sensitive carpets in softer conditions without damaging them.It would beuseful to carry out studies that reduce water usage by optimizing the amount of washing baths in the future.