Peeling Mechanism Research Articles

A distinctive material removal mechanism in the diamond grinding of (0001)-oriented single crystal gallium nitride and its implications in substrate manufacturing of brittle materials

Single crystal gallium nitride (GaN) substrates are highly demanded for fabricating advanced optoelectronic devices. It is thus essential to develop high efficiency machining technologies for this difficult-to-machine material, which in turn necessitates a thorough understanding of its deformation mechanism. In this study, the deformation and removal characteristics of (0001)-oriented single crystal GaN involved in diamond grinding were systematically investigated. The material removal exhibited a brittle mode when using relatively coarse diamond abrasives of 2000 in mesh size, while ductile removal was achieved when diamond abrasives of 6000 in mesh size were utilized. A novel peeling phenomenon was observed along (0001) lattice plane (c-plane) in the coarse grinding, as the crystal has a hexagonal crystal structure with c-planes serving as the preferable slip/cracking planes. Peeling observed in material removal agrees well with the findings that lateral planar defects were prone to initiate in nanoscratching in comparison to nanoindentation in the ductile regime, indicating that the effect of tangential grinding force is significant. The application of Molecular dynamics (MD) simulations, employing smaller indentation/scratching models, provided additional confirmation of the crucial role played by lateral force in initiating planar defects on c-planes. Furthermore, larger-scale MD scratching models substantiated the occurrence of peeling in the deformation process on c-plane, a finding corroborated by scratching experiments conducted in the brittle regime. Conversely, such peeling is absent on m- and a- planes. Complementary to the simulations, specifically designed grinding experiments were conducted to empirically demonstrate that peeling phenomena were intensified with elevated rotational wheel speeds. This enhancement was attributed to the increased tangential grinding force associated with higher speeds. These findings contribute to a comprehensive understanding of the intricate relationship between rotational wheel speed, tangential grinding force, and the observed peeling mechanisms in the context of single crystal GaN machining.

Study on the Metabolic Basis of the Color Formation of Two Color-Presenting Types of Jujube Fruits.

Jujube is a plant of the genus Ziziphus in the family Rhamnaceae; its fruit has high nutritional value, and it is rich in polyphenols, flavonoids, and other secondary metabolites. The color of its peel is an important indicator for evaluating the appearance of the fruit. However, the mechanism of the difference in color presentation between the seedling offspring of the 'Red Fruit' (TLHH) and the 'Green Fruit' (TLHL) of the fresh jujube cultivar 'Tailihong' is not clear. Therefore, this study used targeted metabolomics techniques to accurately and quantitatively analyze the metabolic pathways of carotenoid and anthocyanin metabolites during the ripening process of two color-presenting types of jujube fruits. Through the analysis of the dynamic changes in the pigment content of the jujube peel, it was found that 30 DAP (days after pollination), 80 DAP, and 110 DAP were the key periods for the development of the color of the peel of 'TLHL' and 'TLHH' jujube and that the substances responsible for the main differences were chlorophyll, carotenoids, and anthocyanins. Furthermore, we used an LC-MS/MS metabolic analysis to compare the differences in the carotenoids and anthocyanin metabolites between the two color-presenting types of jujube peels at the key periods of 30 DAP, 80 DAP, and 110 DAP. We detected 32 carotene metabolites and 75 anthocyanin metabolites, respectively, among which lutein had the highest content of carotenoids; it reached the maximum value (93.05 µg/g) and was higher than that of 'TLHH' (74.14 µg/g) at 30 DAP of 'TLHL'. Both showed a decreasing trend with fruit ripening. The anthocyanin with the highest content was cyanidin-3-O-(tartaryl)rhamnoside-5-O-glucoside, which reached the maximum value (258.32 µg/g) at 30 DAP of 'TLHH' and was 51.6 times that of 'TLHL'; similarly, both showed a decreasing trend with fruit ripening. These results elucidate the main metabolites of carotenoids and anthocyanins in the two types of jujube peel and their accumulation characteristics, suggesting that the key metabolites of the difference in color between 'TLHL' and 'TLHH' jujube fruits were lutein and cyanidin-3-O-(tartaryl)rhamnoside-5-O-glucoside, increasing the understanding of the color mechanism of jujube peel and providing a reference for targeted genetic breeding of jujube peel color.

Interpreting the Initial Growth Process of Surface Peeling: Microstructural Evolutions of Soil Deterioration on Archaeological Sites

ABSTRACT Few previous studies have investigated the mechanism of surface peeling from the perspective of soil microstructure. This study investigated surface peeling patterns and their growth feature in a large-size archaeological site, and SEM-EDS observed microstructure characteristics towards soil samples collected at different stages. Muddy Peeling (MP) irregular crusts with curling edges and Peeling with Salt Efflorescence (PSE) triggered by salt accumulation and formation of flakes in different shapes and thicknesses were the two main surface peeling patterns on the site. The average particle size of MP and PSE decreased from 6.0 μm to about 3.1 μm and 2.5 μm, respectively. Average pore size (4.5 μm) in unweathered soil decreased to 2.21 μm (MP) and 2.36 μm (PSE), and then rose to 4.86 μm (MP) and 5.74 μm (PSE), respectively. Micro-observation showed that the formation of flocculated calcium secondary minerals in MP and CaSO4 in PSE triggered by different water impacts caused different surface peeling patterns. This is the first study to reveal the differences lying in the initial growth process of archaeological site’s surface peeling in depth.

Bioactive Compounds and Industrial Peeling Applications of Inner and Outer Shells of Chestnuts (Castanea spp.)

The aim of this review is to provide information concerning the types of chestnut shells (inner and outer), their compositions and bioactive compounds, as well as to mention industrial peeling applications. These shells are comprised of high-valued natural active compounds, such as polyphenols (phenolic acids, flavonoids, tannins, hydroxycoumarins -scopoletin, scoparone-), pigments (melanin) and minor compounds (minerals, dietary fiber, vitamin C and E, essential amino acids and fatty acids). The total phenolic acids and flavonoid content of C. sativa shell were ranged between 119.17-223.62 mg/kg db and 330 – 503 mg CE/g. It is also a good source of vitamin C with reported levels of 15.57 and 28.97 mg AA/100 mg db in water and ethanol extracts, respectively. The shells are used as food additives due to their colorant, antioxidant and antimicrobial properties. The shells are exposed by the peeling process applied to obtain the fruit without the shell which is mainly used. The most frequently used technique in chestnut peeling is the Brulage peeling method. However, in this technique, used peeling mechanism is insufficient to obtain both inner and outer shells separately at the same time. Moreover, further research is needed to obtain the shells individually, to analyse each shell in detail, and to increase the industrial use of shells.

Innovative recycling of high purity silver from silicon solar cells by acid leaching and ultrasonication

Precious and scarce silver (Ag) is used as a front electrical contact in silicon solar panels. With massive amounts of solar panel waste coming to end-of-life, it is imperative to recover all the Ag from these modules. In this paper, we propose a novel method to easily reclaim Ag from end-of-life silicon solar cells using low concentration sulfuric acid (H2SO4) leaching followed by ultrasonication. Our process simplifies the Ag recycling procedure by directly recovering the Ag contacts from solar cells, eliminating the need for secondary precipitation/electrodeposition. First, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) was used to study the leaching and ultrasonication process on rejected solar wafers. Next, a solar panel from landfill was heated in a furnace to burn off the polymer encapsulant. The silicon wafers were then collected from the burning process and leached in 2 M H2SO4 at two different shaking speeds for 48 h at room temperature. Finally, the end-of-life silicon wafer pieces were collected, sonicated in water, and then the sonication water was centrifuged to show a proof-of-concept to recover the Ag contacts. Inductively coupled plasma optical emission spectroscopy (ICPOES) is used to monitor dissolved elements in the leachate as a function of time and shaking speed. XPS is used to evaluate the composition of the silicon cell wafer surface before and after H2SO4 leaching. SEM is used to image the recovered Ag contacts morphology and EDX confirms the recovered particles contain high amounts of Ag. A proposed schematic illustrates the authors’ hypothesis for the peeling mechanism.

Atherosclerotic Calcifications Have a Local Effect on the Peel Behavior of Human Aortic Media.

Aortic dissections, characterized by the propagation of a tear through the layers of the vessel wall, are critical, life-threatening events. Aortic calcifications are a common comorbidity in both acute and chronic dissections, yet their impact on dissection mechanics remains unclear. Using micro-computed tomography (CT) imaging, peel testing, and finite element modeling, this study examines the interplay between atherosclerotic calcifications and dissection mechanics. Samples cut from cadaveric human thoracic aortas were micro-CT imaged and subsequently peel-tested to map peel tension curves to the location of aortic calcifications. Empirical mode decomposition separated peel tension curves into high and low-frequency components, with high-frequency effects corresponding to interlamellar bonding mechanics and low-frequency effects to peel tension fluctuations. Finally, we used an idealized finite element model to examine how stiff calcifications affect aortic failure mechanics. Results showed that atherosclerosis influences dissection behavior on multiple length scales. Experimentally, atherosclerotic samples exhibited higher peel tensions and greater variance in the axial direction. The variation was driven by increased amplitudes of low-frequency tension fluctuations in diseased samples, indicating that more catastrophic propagations occur near calcifications. The simulations corroborated this finding, suggesting that the low-frequency changes resulted from the presence of a stiff calcification in the vessel wall. There were also modifications to the high-frequency peel mechanics, a response likely attributable to alterations in the microstructure and interlamellar bonding within the media. Considered collectively, these findings demonstrate that dissection mechanics are modified in aortic media nearby and adjacent to aortic calcifications.

High-quality and efficient large-area copper removal utilizing laser-induced active mechanical peeling

Large-area copper layer removal is one of the essential processes in manufacturing printed circuit boards (PCB) and frequency selective surfaces (FSS). However, laser direct ablation (LDA) with one-step scanning is challenging in resolving excessive substrate damage and material residue. Here, this study proposes a laser scanning strategy based on the laser-induced active mechanical peeling (LIAMP) effect generated by resin decomposition. This scanning strategy allows the removal of large-area copper layers from FR-4 copper-clad laminates (FR-4 CCL) in one-step scanning without additional manual intervention. During the removal process, the resin decomposition in the laser-irradiated area provides the mechanical tearing force, while the resin decomposition in the laser-unirradiated area reduces the interfacial adhesion force and provides recoil pressure. By optimizing scanning parameters to control the laser energy deposition, the substrate damage and copper residue can be effectively avoided. In our work, the maximum removal efficiency with different energy densities, pulse duration, and repetition frequency are 31.8 mm2/ms, 30.25 mm2/ms, and 82.8 mm2/ms, respectively. Compared with the reported copper removal using laser direct write lithography technology combined with wet chemical etching (LDWL+WCE) and LDA, the efficiency improved by 8.3 times and 66 times. Predictably, the laser scanning strategy and the peeling mechanism are simple and controllable, which have potential in electronics, communications, and aerospace.

Peeling mechanism of tomato induced by HHAIB: Microscopic, ultrastructure, chemical, physical and mechanical properties perspectives

In order to better manage the peeling degree and avoid unnecessary losses, the current work aimed to explore the peeling mechanism of a novel peeling technology, high-humidity hot air impingement blanching (HHAIB). The relationships between HHAIB peeling performance and the changes in skin temperature, skin structure, water state, pectin fractions content, and skin mechanical properties of tomatoes were analyzed. Results showed, after HHAIB treatment, the epicuticular wax was disrupted, the skin exhibited more and longer random cracks, the degradation of inner skin tissue was observed by transmission electron microscopy, the free water percentage increased resulting in water loss in the whole tomato, the water-soluble pectin contents decreased in tomato fleshes, while the contents of chelate-soluble pectin and sodium-carbonate-soluble pectin increased. HHAIB heating reduced the elongation at break, and increased Young's Modulus of tomato peel. This study revealed the HHAIB peeling mechanism and provided new insights for developing HHAIB peeling technology.

Harnessing strong and asymmetric adhesion by combining film heterogeneity and substrate morphology

We use a combined theoretical and experimental approach to investigate the quasi-static peeling behaviors of heterogeneous films from corrugated substrates. The heterogeneity is involved in films through two different methods, i.e., local stiffening and kirigami patterning, and the substrate surface is assumed to adopt a sinusoidal profile. Our results show that the spatial variation in film's bending stiffness, caused by the elastic heterogeneity with period form, can significantly enhance the peak peel force and give rise to asymmetric adhesion performance. The substrate's roughness can further amplify such adhesion enhancement and asymmetry by affecting the local peel angle at the peel front. The adhesion performance depends sensitively on the relative position between the heterogeneous films and corrugated substrates, and our results show that a combination of film heterogeneity and substrate undulation can enhance the adhesive strength by more than 100 times, compared with the case of homogeneous film and flat substrate. This study provides a theoretical framework to reveal multiple peeling mechanisms in the problem and can guide the design of film-substrate systems with tunable and anisotropic adhesion.

Numerical simulation of the oil peeling mechanism on a hydrophilic plate dipping underwater

Peeling is a fundamental physical behavior involving the removal of foreign substances attached to a surface, and it finds applications in various engineering problems. Most previous studies have focused on peeling thin solid films from solid surfaces. However, ocean pollution has emerged as a serious environmental concern, making it critical to effectively and continuously remove highly viscous oil from oil recovery devices to prevent oil fouling. To address this, recent technological advancements have introduced an oil recovery technique that utilizes a hydrophilic surface capable of detaching, and even peeling, oil when dipped into water. In this study, we analyzed the underlying peeling mechanism by numerically simulating the oil peeling process from a vertically situated dipping plate with hydrophilic treatment. The present work expanded the level contour reconstruction method, originally developed for two-phase interface tracking, to handle the three-phase flow involved in the peeling of oil attached to the plate by an air–water meniscus. We properly validated the proposed numerical model and investigated the effects of various input conditions, including oil thickness, descending plate speed, and oil viscosity, in detail. Furthermore, force analysis during the oil peeling process was performed, and a regime map is provided to offer a comprehensive understanding of the overall peeling process. This research aims to contribute to the development of efficient and reliable oil recovery methods, particularly in combating ocean pollution caused by viscous oil residues.

Resistance index and browning mechanism of apple peel under high temperature stress

Apples are one of the most important economic crops worldwide. Because of global warming and an aggravation of environmental, abnormally high temperatures occur frequently in fruit-growing season and seriously affect normal fruit growth and reduce fruit quality and yield. We took five-year-old ‘Ruixue’ (Qinfu 1 × Pink Lady; CNA20151469.1) fruits as test materials, and the ambient temperature during fruit development was monitored. The results showed that during the fruit-growing season, especially during the rapid growth stage (July to August), the maximum daily temperature exceeded 30 °C and lasted for more than 40 days. To determine the effects of high temperature stress on the apple fruit resistance, we treated expanding, veraison, and maturity-period fruits at different temperatures. It was found that the fruits of the expanding period showed strong resistance to high temperature stress, whereas during veraison and maturity, fruit resistance to high temperature stress decreased, and the fruit peel browning phenotype appeared. Meanwhile, the content of malonaldehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion (O2.-) in the peel gradually increased with increasing temperature. The content of total phenols, flavanol, and flavonoids in the peel decreased substantially at 45 °C. Moreover, it was found that polyphenol oxidase gene (MdPPO1) was most sensitive to high temperature stress in apple. Furthermore, transient and stable MdPPO1 overexpression significantly promoted peel browning. The transgenic materials were more sensitive to high temperatures, and browning was more severe compared to non-genetically modified organism (WT). Stable MdPPO1 knockout calli obtained via clustered regularly interspersed short palindromic repeats (CRISPR/Cas9) gene knockout technology reduced the browning phenotype, and the resultant fruits were not sensitive to the effects of high temperature stress. Thus, MdPPO1 expression may be a key factor of high temperature–related changes observed in the browning phenotype that provides a scientific theoretical basis for the selection of high temperature–resistant varieties and apple cultivation and management in the future.

Finite element analysis of energy absorption mechanism of durian peel and durian thorns under compressive load

This study aims to investigate the energy absorption mechanism of durian peel under compression using finite element analysis. The durian peel comprises four substructures: thorn skin, thorn core, locule, and membrane. Their mechanical properties were measured experimentally and used as inputs for finite element models. Three-dimensional solid models of the durian peel were created and compared to the corresponding macroscopic responses. Good agreements between the experimental results and model predictions validate the measured properties. Energy analysis of the substructures shows that thorn skins and cores are the dominant components of energy absorption in durian peel under large deformation. Single thorn models with various aspect ratios were created to analyze their influence on energy absorption. The single thorn models were compressed at four angles of attack to capture the effect of peel curvature. The analysis shows that the aspect ratio of a single thorn that balances energy absorption at all angles of attack falls between 1 and 1.25, which is consistent with the experimentally measured values.

Visualization-based experimental investigation of microscopic sand production characteristics and mechanisms in weakly consolidated sandstone reservoirs

Sand production is a troublesome problem in the petroleum industry, especially in relation to weakly consolidated formations. In this work, a visual experimental apparatus, which allows sand particles to be observed, has been constructed to simulate sand production in weakly consolidated sandstone core. The experimental apparatus can accommodate sandstone core flakes as a reactor. The experiment aims to investigate the microscopic sand production mechanism of the weakly consolidated sandstone reservoir under the influence of high water cut, high clay content and polymer aging blockage. Core flakes were produced using simulated formation sands with median particle sizes of 160 μm and uniformity coefficients of 2.5, 4.6, 7.3 and 12.6, as well as clay (content 5%, 10%, 20%, 30%, respectively) and aged polymers in the wells. A total of 17 sets of experimental tests were carried out with water injection. The visual experimental results show that sand morphology presents complex wormhole. Morphology is particularly affected by core strength and heterogeneity. Based on dynamic differential pressure of experimental results, most sand production process is divided into two obvious stages, that is, the cavities formation stage of sharp sand production and the stable sand production stage. Analysis of sensitive factors revealed that the sand production rate is strongly influenced by the core strength and related to clay content, formation heterogeneity and production program. The volumetric sand production ratio decreases with the increase of core strength, with the volumetric sand production ratio (VSPR) reaching up to 0.24%. It is found that about 38% clay (1–3.91 μm) was produced in the initial stage of low flow, which is particularly evident in cores with high clay content. Moreover, for weakly consolidated reservoir, the particle competition peeling mechanism of wormhole front is proposed, and the strengthening bonding effect of aging polymer and the pore blockage effect of fine clay are clarified. The findings could contribute to better understanding of the mechanisms underlying sand production in weakly consolidated sandstone reservoirs, which also provide a solid evidence base for accurate sand production prediction and more targeted sand control.

Dynamic peeling process of IC chip from substrate based on a 3D analytical model

A 3D analytical approach is proposed to investigate the peeling mechanism of IC chip from substrate, which is important for reliable electronic packaging. Chip-adhesive-substrate system is considered as a composite structure composed of a rectangular plate of free edges and a clamped circular plate bonded with an interfacial layer. Peeling a chip from substrate is treated as the interfacial fracture of this structure. Based on the theory of elasticity, the problem of interfacial fracture is reduced to a set of coupled integral and differential equations. An analytical scheme is developed to solve these equations. With the approach, dynamic evolution process of peeling is analyzed due to various needle ejecting and vacuum absorption. Stress distributions of both chip and adhesive at different stages of peeling process are obtained. It is shown that stresses of both chip and adhesive are nonuniformly distributed in the whole region. As a result, peeling initiates from four corners, and propagates toward the center of interface with a very complex advancing front. For a definite displacement of needle point, peeling process is determined by both the magnitude and application time of vacuum absorption. When these two parameters locate in a specific region, a chip can be separated completely from substrate without damage. Furthermore, peeling process is sensitive to the position deviation of needle point. In case the position deviation is beyond a certain range, peeling process is incomplete.

Three-Dimensional Printing of Ag Nanoparticle Meshes for Antibacterial Activity

Silver nanoparticles (Ag NPs) are decorated or encapsulated for use in antibacterial applications; however, their synthesis involves complex chemical processes. In this study, we developed a facile process for printing an Ag NP 3D microstructure to be applied as an antibacterial filter. The Ag NPs were printed in a mesh form using an aerodynamically focused nanomaterial (AFN) printing system. Unlike the conventional printing method, in the proposed method, the printed Ag NP mesh was peeled from a polydimethylsiloxane substrate. To examine this printing and peeling mechanism, molecular dynamics simulations were performed. In addition, characteristics of the Ag NP mesh were analyzed. The results of the analysis confirmed that the printed mesh retained the properties of Ag NPs. Meshes with various sizes and porosities were printed and their performance as an antibacterial filter was evaluated. Finally, a straw-shaped prototype water filter with three mesh layers was fabricated. A plate cultivated from a suspension filtered using this prototype contained zero active bacteria. This result indicates that the proposed Ag NP 3D printing process, which allows the preservation of antibacterial properties and has wide application scope, is an extensively viable process for manufacturing antibacterial microstructures.

Simultaneous peeling of precious metals in cathode and anode of spent ternary batteries using electrolysis

Recycling spent lithium-ion batteries (LIBs) is of great significance for both environmental protection and resource recycling. However, there are only a few studies on the simultaneous peeling and recycling of battery anode and cathode. Thus, this work proposed a new process for peeling cathode and anode in spent LIBs to solve this problem. The cathode and anode of the spent LIBs were used to form an electrolytic cell to simultaneously realize the peeling of the electrode materials and current collectors and a large amount of Li+ leaching. The leaching rate of Li+ reached 96.19 % under optimal conditions. In addition, the Li+ in the electrolyte can be directly heated and concentrated to be recovered in the form of Li2CO3. Furthermore, the peeling of cathode materials was caused by the gas shock and defluorination of polyvinylidene fluoride (PVDF). For the Li-free materials, the chemical separation and precipitation method was used to separate and recover Ni, Co, and Mn. In conclusion, this experiment carried out an environmentally friendly electrolysis recycling technique to realize the selective pre-recovery of Li+, the separation of electrode materials with current collectors, and the high purity recovery of current collectors. A new peeling mechanism for the electrolysis recycling technique was also explored. Therefore, this study was expected to provide a useful reference for the electrolysis recycling technique.

The anti-oxidative capacity of fermented lemon peel and its inhibitory effects on Lipopolysaccharide (LPS)-induced RAW 264.7 cell inflammatory response and cell apoptosis

Chronic inflammation plays a key role in the development and progression of several chronic diseases. Inhibiting the inflammatory cascade, thereby minimising the damage caused by the inflammatory mediators, can be one of the strategies in chronic disease management. In addition, inflammation is closely related to apoptosis, and inflammation can cause apoptosis. Lemon peel has been reported to have antioxidant and anti-inflammatory biological activities. This study aimed to investigate the antioxidant activity of fermented lemon peel (FLP) by Lactobacillus plantarum PNU and the effect of its extract (FLPE) on LPS-induced inflammatory response in RAW 264.7 cells. The results show that FLP has better antioxidant activity than unfermented lemon peel (UFLP). Compared with UFLP extract, FLPE more effectively inhibited the release of NO and pro-inflammatory cytokines (IL-1β, IL-6, TNF-α and IFN-γ) and down-regulated pro-inflammatory genes (IL-1β, IL-6, NF-κB p65, COX-2, IFN-γ, iNOS, IL-5), and pro-apoptotic genes (caspase-3, caspase-9, p53, p21 and Bax), meanwhile, promoted the release of anti-inflammatory cytokine (IL-10) and up-regulated anti-inflammatory genes(IL-10 and IL-4), and anti-apoptotic gene (Bcl2) in LPS-induced RAW 264.7 cells. Therefore, this study elucidates the anti-inflammatory activity mechanism of fermented lemon peel by studying the balance of inflammatory response and the inhibition of apoptosis. It provides an important reference for the future research and treatment of chronic inflammation and related diseases, as well as the development of fermented foods with anti-inflammatory effects.

The mechanism study of laser peeling of ultra-thin polyimide film from the transparent substrate

Laser peeling of ultra-thin polyimide (PI) film from transparent substrate is a critical technology in the flexible electronics industry. This paper studies the laser ablation and interface separation of the PI film to reveal the mechanism of laser peeling. In the laser ablation process, the supercritical environment is formed, and gas bubbles appear. Then the gas bubbles fuse together and become cavitation holes. These cavitation holes fuse together and produce sparse nanopillar structures that can be seen as a blister. In the interface separation process, the blister absorbs thermal energy and expands under laser irradiation. This paper proposes a discrete quasi-static method to analyze the separation of the PI film from the transparent substrate during the blister expansion. The cohesive zone model is also introduced to predict the peeling behaviors of the PI film. The results show that the blister profile is related to the laser influence, and the blister profile obtained by the theoretical model can fit well with the experiment. When the laser fluence is larger, the blister profile is steeper, and the pressure inside the blister is larger. This paper provides a new perspective for understanding the laser peeling mechanism of ultra-thin PI film from a transparent substrate.

Effects of Surface Roughness on Direct Plasma Bonding between Silicone Rubbers Fabricated with 3D-Printed Molds.

This study presents the effects of surface roughness on the adhesion strength of plasma-treated rubbers that are widely used in soft robotics. The rubbers are designed with 11 molds of different patterns and fabricated from liquid silicones for mutual comparison. Several specimens with nonperiodic and periodic surface waveforms are quantitatively analyzed based on the correlation between surface roughness and adhesion strength. The surface roughness of three-dimensional (3D) printed molds under different printing conditions is compared to that of the standard specimens molded by a smooth acrylic plate and four sandpapers. The surface profiles are measured by a stylus profiler, analyzed using fast Fourier transform, and subsequently quantified using the experimental roughness parameters, R a and R ku *. The kurtosis ratio R ku * is proposed to simultaneously evaluate the sharpness, total height, and peak density to identify contact surfaces. A 90° peel test is also conducted to evaluate the adhesion strength, considering the designed pattern and printing orientation relative to the peeling direction. Microstructural analysis of the specimens is performed to investigate the peeling mechanism and molding quality using scanning electron and digital microscopes. Correlations between adhesion strength and surface roughness are obtained through the evaluation of the plasma-treated silicone specimens. R ku * is significant in determining the surface properties of the effective contact area, particularly for rough surfaces, and further contributes to an effective evaluation when the parameter R a is used simultaneously. The results suggest that the plasma bonding of silicone rubbers fabricated with 3D-printed molds is effective in enhancing the adhesion strength of soft robots or stretchable devices.

Citrus peel ameliorates mucus barrier damage in HFD-fed mice

Citrus peel is rich in bioactive components, especially polyphenols, which are considered to have great potential in the prevention of intestinal diseases. The intestinal mucus barrier is the first defense against the invasion of foreign substances. In this study, we aimed to explore the possibility and mechanism of citrus peel in alleviating the mucus barrier damage in high-fat-diet (HFD) mice. We found that citrus peel powder (CPP) supplementation effectively reduced body weight, fat weight, intestinal permeability, hyperlipidemia, and systemic inflammation in HFD-fed mice. In particular, CPP increased the number of goblet cells, the protein expression of Mucin-2 (Muc2), and the thickness of the mucus layer, thereby strengthening the colonic mucus barrier function. Moreover, CPP supplementation also reduced the expression of endoplasmic reticulum stress (ERS) proteins (GRP78 and CHOP) and increased the expression of T-synthase (O-glycosylation rate-limiting enzyme) and its chaperone protein (Cosmc) in the colon of HFD-fed mice, which suggested that CPP could improve the abnormal protein folding and O-glycosylation of Muc2 during processing and modification. In summary, our study indicates that CPP plays an effective role in relieving mucus barrier damage by improving the production and properties of Muc2, providing new perspectives on the development of CPP as a dietary supplement for strengthening the intestinal barrier.