Effect Of Skin Layer Research Articles

Programmable Dual‐Responsive Actuation of Single‐Hydrogel‐Based Bilayer Actuators by Photothermal and Skin Layer Effects with Graphene Oxides

AbstractShape morphing of stimuli‐responsive composite hydrogels has received considerable attention in different research fields. Although various multilayer structures with dissimilar materials are studied to achieve shape morphing, combining swellable hydrogel layers with non‐swellable layers results in issues with interface adhesion and structural integrity. In this study, single‐hydrogel‐based bilayer actuators comprising poly(N‐isopropylacrylamide) (PNIPAM) matrices and graphene oxide (GO)–PNIPAM hinges are presented. Upon temperature rising, the PNIPAM hydrogel acts as the passive layer due to the formation of dense microstructures near the surface (i.e., the skin layer effect), whereas the GO‐PNIPAM hydrogel functions as the active layer, maintaining porous due to structural modification by the presence of GO. Under light exposure, the GO‐PNIPAM hinges experience selective heating due to the photothermal effect of GO. Consequently, the resulting bilayer structures exhibit programmable dual‐responsive 3D shape morphing. Additionally, the folding kinetics of these actuators can be adjusted based on the applied stimulus (temperature changes or light), as they are driven by different mechanisms, the skin layer, or photothermal effects, respectively. Furthermore, the hinge‐based bilayer structures demonstrate walking and steering locomotion by light exposure. This approach can lead to advances in soft robotics, biomimetic systems, and autonomous soft actuators in hydrogel‐based systems.

Effect of Skin Layer on Brush Loading, Cross-Contamination, and Cleaning Performance during Post-CMP Cleaning

The use of polyvinyl acetal (PVA) brushes is one of the most effective and prominent techniques applied for the removal of chemical mechanical planarization (CMP) contaminants. However, the brush can be a source of defects by entrapping the abrasives inside its porous structure during brush scrubbing. In this study, the effect of brush top skin layer was extensively studied on contamination, cross-contamination, and cleaning performance by comparing brushes with and without skin layer. The presence of a dense top skin layer resulted in larger contact areas and high ceria particle adsorption on the skin layer. This leads to higher cross-contamination of the wafers during scrubbing along with high cleaning performances. Conversely, the brushes without skin layer showed lower contamination and negligible cross-contamination with a reduced cleaning performance (removal of ceria particles from oxide surface). Therefore, the role of the brush skin layer is significant and needs to be considered while designing a post-CMP cleaning process.

Skin Layer Effects on Adhesion Forces of PVA Brushes and Its Temperature Dependence

Semiconductor devices have been achieved high performance by improving processing speed and integration degree due to downsize and multilayer wiring structure. Along with this tendency, the importance of CMP processing is increasing. In addition, due to many particles are generated after CMP process, post-CMP cleaning is also very important process. In the post-CMP cleaning, PVA (PolyVinyl Acetal) brush have been widely used. However, in this scrub cleaning, problems have been reported that many particles are generated from the PVA brush itself by adhesion of PVA brush onto surface and contaminated the wafer surface. Therefore, it is necessary to control adhesion between PVA brushes and semiconductor surfaces. In our early study, adhesion of PVA brush was evaluated by rotating torques or frictional forces. In this study, we tried to measure directly adhesion forces between PVA brush and several solid surfaces with a high response load cell. We believe that the measurement of the adhesion force can discriminate the material that is likely to adhere to the PVA brush. We compared the adhesion forces for two types of brushes with or without a skin layer. Moreover, we investigated whether adhesion force could be controlled by changing brush temperature. Because of the PVA brushes are porous polymer, mechanical properties change with its temperature. We consider that the temperature also affects adhesion force onto solid surfaces. In this study, we measured the adhesion forces between PVA brushes and solid surfaces in the atmosphere. The adhesion forces Fa were measured with a load cell. PVA brush was pressed against the test surfaces and releasing it at high speed after relaxing for a certain period of time tw . We used three types of test surfaces, Glass, Polymethyl methacrylate (PMMA) and Polytetrafluoroethylene (PTFE). The contact angles were 28°, 61° and 97°, respectively. The temperature of test surfaces were controlled with a Peltier device and were set to 20 degrees to 50 degrees. Attached figure shows an example of relationship between the adhesion force Fa of PVA brush with skin layer and relaxation time tw on the different surfaces. As shown in the figure, Fa increased with increase tw in the all surface cases. We consider that this cause is real contact area increased as the tw increased. In the dependence of test surfaces material, Glass and PTFE case showed similar adhesion force values. On the other hand, the forces of PMMA case showed larger values than other test surfaces. This result indicates that there are materials that strongly interacts with skin layer PVA brushes. In the experiments using without skin layer case, however, we could not measure the adhesion force in the all experimental conditions. This result suggests that without skin layer brush is maybe not contact onto surface and the adhesion force is strongly depended on the existence of skin layer. Next, we focus on temperature dependence of the adhesion forces. In the all test surface cases, adhesion force decreased with increase temperature. Particularly the adhesion force of the PMMA case was greatly decreased at 50 degrees. These results suggest that the temperature may control the adhesion force of PVA brush onto solid surface. Figure 1

Skin Layer Effects on Adhesion Forces of PVA Brushes and Its Temperature Dependence

In this study, the adhesion forces between PVA (PolyVinyl Acetal) brushes and solid surfaces were measured directly using a highly responsive load cell. The adhesion forces were compared based on contact time, and the influence of skin layer existence on PVA brush surface was investigated. In addition, the surface temperature dependence of the adhesion forces was also studied. Results showed that the adhesion force increased with increasing surface contact time. For a PMMA surface, significantly large adhesion forces were observed. It was also seen that the adhesion force decreased with increasing temperature. However, by using the present setup, the adhesion forces in all experimental conditions without skin layer brush cases could not be measured.

Effect of Skin Layer on Electric Impedance Scanning Imaging

In study of Electric Impedance Scanning Imaging (EISI), some scholars believe that low electrical impedance of skin layer will reduce detection sensitivity of imaging system. However, in the previous numerical model analysis, there is little work to analyze the influence of skin layer. Based on actual size, electrical parameters of Chinese female breasts and detection probe structure, static electric field equation was solved by finite element method. Results show that skin layer not only reduces current detected by probe, but also significantly reduces sensitivity of probe. The smaller the conductivity of skin layer, the more obvious decrease in sensitivity. In practice, if conductivity of skin layer can be improved by some means, sensitivity of probe can be increased. Furthermore, if thickness and conductivity parameters of skin layer can be accurately obtained, and then influence of skin layer in overall EISI image can be eliminated, imaging quality and detection sensitivity of system should be significantly improved.

Association between collagen production and mechanical stretching in dermal extracellular matrix: In vivo effect of cross-linked hyaluronic acid filler. A randomised, placebo-controlled study

BackgroundThe effects of hyaluronic acid (HA) injection on tissue collagen anabolism are suggested to be related to the induction of mechanical stress, causing biochemical changes in skin physiology. ObjectivesTo ascertain the association between dermal mechanics modulated by a hyaluronic acid-based filler effect and metabolism. MethodsSixty females were randomised to receive a 0.5mL injection of HA gel or isotonic sodium chloride (control) in the arm. Skin biopsies were taken at baseline and after 1, 3 and 6 months. Protein and gene expression of procollagen, matrix metalloproteinases (MMP) and MMP tissue inhibitors (TIMP1) were measured blind by ELISA and qPCR, respectively. Injected volumes were measured by high-frequency ultrasound and radiofrequency analysis. Skin layer effects of injections were analysed by finite element digital modelling. ResultsOne month after injection, the filler induced an increase in procollagen (p=0.0016) and TIMP-1 (p=0.0485) levels and relative gene expression of procollagen III and I isoforms compared with the controls. After 3 months, procollagen levels remained greater than in the controls (p=0.0005), whereas procollagen expression and TIMP-1 and MMP content were no longer different. Forty-three percent of the injected filler volume was found at 1 month, 26% after 3 months and 20% after 6 months. LimitationsThe ultrasound imaging technique limited the scope of the investigation and precluded an evaluation of the action of the filler at the hypodermic level. ConclusionsIntegrating both mechanical and biological aspects, our results suggest that mechanical stress generated by cross-linked HA plays a role in dermal cell biochemical response.

In‐plane dielectric and magnetoelectric studies of BiFeO3

AbstractIn‐plane temperature dependent dielectric behavior of BiFeO3 (BFO) as‐grown thin films show diffuse but prominent phase transitions near 450 (±10) K and 550 K with dielectric loss temperature dependences that suggest skin layer effects. The 450 K anomalies are near the “transition” first reported by Polomska et al. [Phys. Status Solidi 23, 567 (1974)]. The 550 K anomalies coincide with the surface phase transition recently reported [Marti et al., Phys. Rev. Lett. 106, 236101 (2011)]. In addition, anomalies are found at low temperatures: After several experimental cycles, the dielectric loss shows a clear relaxor‐like phase transition near what was previously suggested to be a spin reorientation transition (SRT) temperature (∼201 K) for frequencies 1 kHz < f < 1 MHz which follow a nonlinear Vogel–Fulcher (V–F) relation; an additional sharp anomaly is observed near ∼180 K at frequencies below 1 kHz. As emphasized recently by Cowley et al. [Adv. Phys. 60, 229 (2011)], skin effects are expected for all relaxor ferroelectrics. Using the interdigital electrodes, experimental data and a theoretical model for in‐plane longitudinal and transverse direct magnetoelectric (ME) coefficient are presented.

Effect of Skin Layer on Strength of Foamed Plastics

Effect of Skin Layer on Strength of Foamed Plastics

Sea–air flux of CO2 in the Caribbean Sea estimated using in situ and remote sensing data

Empirical relationships between sea surface carbon dioxide fugacity (fCO2sw) and sea surface temperature (SST) were applied to datasets of remotely sensed SST to create fCO2sw fields in the Caribbean Sea. SST datasets from different sensors were used, as well as the SST fields created by optimum interpolation of bias corrected AVHRR data. Empirical relationships were derived using shipboard fCO2 sw data, in situ SST data, and SST data from the remote sensing platforms. The results show that the application of a relationship based on shipboard SST data, on fields of remotely sensed SST yields biased fCO 2sw values. This bias is reduced if the fCO 2sw-SST relationships are derived using the same SST data that are used to create the SST fields. The fCO2sw fields found to best reproduce observed fCO2sw are used in combination with wind speed data from QuikSCAT to create weekly maps of the sea-air CO2 flux in the Caribbean Sea in 2002. The region to the SW of Cuba was a source of CO2 to the atmosphere throughout 2002, and the region to the NE was a sink during winter and spring and a source during summer and fall. The net uptake of CO2 in the region was doubled when potential skin layer effects on fCO2sw were taken into account. © 2003 Elsevier Inc. All rights reserved.

Satellite and Skin-Layer Effects on the Accuracy of Sea Surface Temperature Measurements from the GOES Satellites

The latest Geostationary Operational Environmental Satellites (GOES) have facilitated significant improvements in the ability to measure sea surface temperature (SST) from geostationary satellites. Nonetheless, difficulties associated with sensor calibration and oceanic near-surface temperature gradients affect the accuracy of the measurements and the estimation and interpretion of the diurnal cycle of the bulk SST. Overall, measurements of SST from the GOES imagers on the GOES-8–10 satellites are shown to have very small bias (<0.02 K) and rms differences of between 0.6 and 0.9 K relative to buoy observations. Separate consideration of individual measurement times, however, demonstrates systematic bias variations of over 0.6 K with measurement hour. These bias variations significantly affect both the amplitude and shape of estimates of the diurnal SST cycle. Modeled estimates of the temperature difference across the oceanic cool skin and diurnal thermocline show that bias variations up to 0.3 K can result from variability in the near-surface layer. Oceanic near-surface layer and known “satellite midnight” calibration effects, however, explain only a portion of the observed bias variations, suggesting other possible calibration concerns. Methods of explicitly incorporating skin layer and diurnal thermocline effects in satellite bulk SST measurements were explored in an effort to further improve the measurement accuracy. While the approaches contain more complete physics, they do not yet significantly improve the accuracy of bulk SST measurements due to remaining uncertainties in the temperature difference across the near-surface layer.

Skin layer effects on the diffusion of carbon tetrachloride into injection moulded polypropylene studied by 1H NMR microimaging

Skin layer effects on the diffusion of carbon tetrachloride into injection moulded polypropylene studied by 1H NMR microimaging