Changes In Surface Topography Research Articles

Changes in Surface Topography and Light Load Hardness in Thrust Bearings as a Reason for Tribo-Electric Loads

The article focuses on the findings of endurance tests on thrust bearings. In addition to the mechanical load (axial load: 10 ≤ C0/P ≤ 19, lubrication gap: 0.33 µm ≤ h0 ≤ 1.23 µm), these bearings are also exposed to electrical loads (voltage: 20 Vpp ≤ U0 ≤ 60 Vpp, frequency 5 kHz and 20 kHz), such as those generated by modern frequency converters. In a previous study, the focus was on the chemical change in the lubricant and the resulting wear particles. In contrast, this article focuses on the changes occurring in the metallic contact partners. Therefore, the changes in the surface topography are analysed using Abbott–Firestone curves. These findings show that tests with an additional electrical load lead to a significant reduction in roughness peaks. A correlation to acceleration measurements is performed. Moreover, it is shown that the electrical load possibly has an effect on the light load hardness. An increase in the occurring wear could not be detected during the test series. Also, a comparison with mechanical reference tests is made. The article finally provides an overview of different measurement values and their sensitivity to additional electrical loads in roller bearings.

Long-term evaluation of surface topographic and topsoil grain composition changes in an agricultural landscape

Understanding long-term changes in topography and topsoil grain composition is crucial for the management of agricultural landscapes, especially in areas prone to wind erosion. This study investigates long-term changes in topography and topsoil grain composition within an agricultural landscape in south-western Slovakia. To analyse topographic changes over time, we used high-precision positioning measurements and airborne laser scanning to create digital terrain models (DTM) for the years 2011, 2017 and 2020. To assess changes in soil grain composition, we performed grain size analyses on soil samples collected during three different periods: M1 (1961–1970), M2 (2009–2015) and M3 (2015–2016). Changes in soil texture were evaluated to understand the impact of wind erosion on soil composition. The influence of windbreaks was also analysed by comparing the accumulation and deflation processes. The results showed significant changes in both topography and soil texture over the study period. The DTMs showed marked differences in the accumulation and deflation processes, highlighting areas affected by wind erosion. Comparisons of soil samples showed a shift in dominant soil types from loam and clay loam to silty loam, highlighting the effects of wind erosion. Analysis revealed a decrease in clay and silt content and an increase in sand content, indicating wind-induced soil degradation. The presence of windbreaks played a crucial role in reducing soil erosion by reducing wind speed, promoting soil accumulation and stabilising the landscape up to 80 m windward and 20 m leeward. The study highlights the complex interplay of climate and wind factors in shaping topography and soil properties and emphasises the protective role of windbreaks in agricultural landscapes over time. Our results show that wind erosion significantly alters soil texture, which can affect agricultural productivity. However, windbreaks have proven to be an effective measure in reducing soil erosion and maintaining soil quality.

Effect of conventional cigarette smoking and recent heated tobacco products on CAD/CAM restorative materials

ObjectiveTo determine the effects of conventional cigarette smoking (CS) and recent heated tobacco products (HTPs) on the surface roughness and color stability of different indirect restorative materials.Materials and methodsOne hundred disc-shaped samples were constructed of three different restorative CAD/CAM materials: lithium disilicate glass–ceramic (IPS e.max CAD; Ivoclar Vivadent, Liechtenstein), zirconia (BruxZir® Zirconia, Glidewell, USA) and polyetheretherketone (BioHPP® bredent GmbH, Germany). Of the IPS e.max CAD and the Bruxzir samples, 20 samples were glazed, and 20 samples were polished, while the BioHPP samples were all polished according to the manufacturer’s instructions.Fifty samples were subjected to conventional cigarette smoking (LM, Philip Morris International Inc., Egypt) (Groups: IPS e.max CAD_Glazed exposed to CS (LD_G_Cig), IPS e.max CAD_Polished exposed to CS (LD_P_Cig), Bruxzir_Glazed exposed to CS (Zr_G_Cig), Bruxzir _Polished exposed to CS (Zr_P_Cig) and BioHPP exposed to CS (PEEK_Cig) and fifty samples were exposed to heated tobacco product smoking (Heets, Russet selection, Philip Morris International Inc., Italy) (Groups: IPS e.max CAD_Glazed exposed to HTP (LD_G_HTP), IPS e.max CAD_Polished exposed to HTP (LD_P_HTP), Bruxzir_Glazed exposed to HTP (Zr_G_HTP), Bruxzir CAD_Polished exposed to HTP (Zr_P_HTP) and BioHPP exposed to HTP (PEEK_HTP).. Six hundred cigarettes/heets representing 30 days of medium smoking behavior (20 cigarettes/day) were used. Before and after exposure to smoke, the surface roughness of all the samples was measured using JITAI8101 surface roughness tester (Beijing Jitai Tech Detection Device Co., Ltd, China, and the color parameters were assessed using VITA Easyshade Advance 4.01 (VITA shade, VITA made, VITA). The data were analyzed using One-way ANOVA, paired sample t-test and independent sample t-test. The significance level was set at α < 0.05.The surface topography was evaluated by scanning electron microscopy (SEM) and analyzed using energy-dispersive X-ray (EDX) spectroscopy to determine changes in the surface chemical composition.ResultsBoth types of smoking caused significant increases in the surface roughness of all the samples. There was a significant difference in color change between CS and HTP for all materials with different surface finish (P < 0.01) and zirconia had the greatest effect on color change (P < 0.001). In contrast, polyetheretherketone (PEEK) “BioHPP” had the least effect (P < 0.001).ConclusionExposure to different types of smoking induce changes in the surface topography and color of different esthetic restorative materials. Compared with HTP, conventional cigarette smoke has a greater effect on the surface roughness and color stability of esthetic restorative materials. The glazed surfaces showed less change in surface topography than did the polished surfaces. Zirconia showed better color stability when compared to polyetheretherketone (PEEK).

Numerical modeling and simulation of microbially induced calcite precipitation on a cement surface at the pore scale

Accurate estimation of contaminant transport in cementitious material using numerical tools plays a key role in the risk assessments of nuclear waste disposal. At the pore scale, the increase of microbial activity, such as microbially induced calcite precipitation on cementitious material, causes changes in solid surface topography, pore network geometry, and pore water chemistry, which affect contaminant transport at the core scale and beyond. Consequently, a meaningful estimation of contaminant migration in the subsurface requires a pore-scale investigation of the influence of microbial activity on transport processes. In this study, a pore-scale reactive transport model is presented to simulate the physicochemical processes resulting from microbially induced calcite precipitation on a cement surface. Numerical investigations focus on modeling the reactive transport in a two-dimensional flow-through cell. The model results are validated by experimental data showing an increase in pH and a decrease in calcium concentration due to microbially induced calcite precipitation. Our results show heterogeneous calcite precipitation under transport-limited conditions and homogeneous calcite precipitation under reaction-limited conditions, resulting in non-uniform and uniform changes in the material surface topography. Moreover, power spectral density analysis of the surface data demonstrates that microbially induced calcite precipitation affects the surface topography via both general changes over the entire frequency and local modifications in the high-frequency region. The sensitivity studies provide a comprehensive understanding of the evolution of surface topography due to the microbially induced calcite precipitation at the pore scale, thus contributing to an improved predictability of contaminant transport at the core scale and beyond.

Rebonding of orthodontic metallic brackets: Comparative analysis of shear bond strength using different sandblasting particles

IntroductionThis study aimed to evaluate the effect of two different sandblasting particles on the shear bond strength of rebonded metallic brackets to dental enamel. MethodsForty-eight metallic orthodontic brackets were divided into 4 experimental groups (n = 12) according to the surface treatment they received at their bases: positive control group (Metal), negative control group (MetalU), sandblasted with Rocatec Soft (MetalRoc) and sandblasted with Glass beads (MetalGlas). An elementary and topographic analysis of the base of the brackets was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after the surface treatment. The brackets rebonded to dental enamel were tested for their shear bond strength. The obtained data were subjected to statistical analysis one-way ANOVA and Tukey's test (α = 0.05). The fracture surfaces of the specimens after the mechanical test were analyzed using optical microscopy to classify the failure mode. ResultsSEM photomicrographs for the MetalRoc and MetalGlas groups showed efficient removal of the remaining resin composite. In both sandblasting treatments, the presence of silicon (Si) and oxygen (O) at the base of the brackets were verified by means of the EDS, suggesting the occurrence of silica coating. MetalGlas group showed greater bond strength (9.38 ± 2.78 MPa) compared to the MetalU group (5.31 ± 1.2Mpa). Metal (8.82 ± 4.14 MPa) and MetalRoc (8.29 ± 3.95 MPa) groups showed similar bond strengths. The failure mode predominantly found in the sandblasted groups was the totally adhesive failure between resin composite and tooth. SignificanceThe sandblasting treatment using the glass beads was efficient in removing the remaining resin composite of recycled brackets and generated fewer surface defects and topographic changes in the bracket bases.

Molecular dynamics simulation of dry sliding between non-Gaussian copper rough surfaces

Friction plays a significant role in the wear and tear of sliding metallic surfaces, particularly in gears and bearings employed in nano and micro electro-mechanical systems (NEMS/MEMS). To comprehend the nature of dry sliding friction in mechanical devices, it is crucial to investigate surface interactions at the nano-scale. Molecular dynamics (MD) simulation has been utilized in this study to explore how asperities come into contact at this minute scale. Specifically, the interaction between two non-Gaussian rough surfaces is examined at varying dimensionless spacing (δ/Seq), ranging from 3.6 to 2.7. The von Mises strain, atomic wear, and changes in the atomic arrangement after sliding action are obtained for Cu-Cu (soft-to-soft) tribo-pair at a given sliding speed of 10 m/s. The average friction force on the lower surface increased when the space between surfaces was decreased. More percentage changes in surface topography are found for the lesser dimensionless spacing (δ/Seq) of 2.7. The changes in surface topography parameters during sliding action may have an immense effect on the performance of tribo-pair in NEMS/MEMS. A greater increase in autocorrelation length signifies a more pronounced flattening of the lower surface at the lower dimensionless spacing (δ/Seq).

Characterization of road surface topography changes during polishing process with characteristic roughness parameter

In this paper, three-dimensional structure feature points of the asphalt mixture were obtained based on the industrial CT. The surface morphology of the asphalt mixture was then extracted through image morphology processing and evolutionary matching algorithms. A series of accelerated polishing tests were utilized to simulate the long-term polishing effect of the tire load on the asphalt pavement. Combining with digital image analysis, the full-life morphology evolution trend of the asphalt pavement was analyzed, and the full-life surface morphology datasets of the asphalt pavement were constructed. By comparing the power spectrum density of the asphalt pavement morphology at different wear stages, a segmented evaluation method based on the spectral fractal method was proposed. Combining the spectral fractal parameters and statistical geometric parameters, a multi-scale asphalt pavement surface morphology feature evaluation index was proposed. This provides a more intricate and detailed analysis of the surface structure of asphalt mixtures.

The effect of combined atmospheric plasma/UV treatments on improving the durability of organophosphorus flame retardants applied to polyester fabrics

Following application of three commercially available, flame retardants (FR) to polyester and exposure to an atmospheric plasma in the presence or absence of simultaneous UV 308 nm excimer laser radiation, the retentions to a 30 min 40 °C water-soak for the mono- and dimeric cyclophosphonate (PE-CONC and PCO 900 respectively) and a 30 min methanol-soak treatment for the resorcinol bis(diphenyl phosphate) (RDP) agents were generally enhanced with respect to unexposed controls. These results suggested that the formation of PET-FR bonding had occurred as a consequence of plasma/UV exposure. The effect of plasma/UV process sequence (pre-exposure and/or post exposure with respect to FR impregnation) as well as plasma gas type, showed that maximum post-soaking FR retentions occurred when both pre- and post-exposure conditions operated.Plasma/UV exposed fabrics both before and after soaking treatments were examined for morphological changes by SEM and surface phosphorus retention by EDX, FTIR-ATR, XPS as well as TGA/DTG/DTA, each of which showed evidence on the surface of changes in surface topography, increased phosphorus levels and modified thermal behaviour. When subjected to vertical fabric strip flammability testing, these changes were insufficient to generate significant changes in the burning rate apart from in post-methanol soaked, RDP-containing fabrics where almost all plasma/UV process sequences reduced specimen burning rates.During all experiments, the presence or absence of the UV laser radiation appeared to have no obvious effect on post-soaking FR retentions, suggesting that its presence is not required since plasma activation alone appears to be the key to improving PET-FR bonding.

Polycaprolactone-Based Composite Electrospun Nanofibers as Hybrid Biomaterial Systems Containing Hydroxyl- or Carboxylic Acid-Functionalized Multiwall Carbon Nanotubes

Composite electrospun nanofibers based on polycaprolactone (PCL) have shown promise in various biomedical applications due to their unique properties. This study investigates the effects of incorporating hydroxyl (–OH)- or carboxylic acid (–COOH)-functionalized multiwall carbon nanotubes (MWCNTs) into PCL matrices. Two types of functionalized additives, MWCNT-OH and MWCNT-COOH, were used at different concentrations (0.06 and 0.12 wt%). Various characterization techniques including FTIR, XRD, AFM, SEM, water contact angle analysis, and tensile strength testing were employed to evaluate changes in nanofiber morphology, crystallinity, surface topography, wettability, and mechanical properties. In addition, in vitro cytotoxicity assays were conducted using HUVECs and L929 fibroblasts over 1-, 3-, and 5-day intervals. This study represents a novel examination of (–OH)- and (–COOH)-functionalized MWCNTs as additives in electrospun PCL biopolymer matrices. The findings indicate that incorporating small amounts of (–OH)- or (–COOH)-functionalized MWCNTs enhances the physicochemical characteristics of PCL nanofibers, making them more suitable for biomedical applications. While both types of functionalized MWCNT additives improved properties compared to pure PCL nanofibers, (–COOH)-functionalized MWCNT-incorporated nanofibers exhibited the most favorable features. In conclusion, this research highlights the potential of tailored PCL-based composite nanofibers containing functionalized MWCNTs as advanced biomaterial systems for biomedical applications, contributing to the development of innovative biomaterials for diverse biomedical contexts.

Electrochemical dissolution and retrieval of broken NiTi endodontic files from root canal using chloride based isotonic fluids as electrolytes - An in vitro study.

The electrochemical dissolution method of instrument retrieval emphasizes on the dissolution of the instrument rather than sacrificing dentine. Most of the studies conducted for electrochemical dissolution used fluoride-containing electrolytes and were performed inside a beaker. In this study, we used chloride-based fluids as electrolytes. Fifty extracted mandibular first premolars were divided into five groups based on the electrolytes used. Canals were enlarged to ProTaper Universal F2, and files were intentionally broken inside the canal. These specimens were subjected to electrochemical characterization by applying the potential of 9V for 20 min. Optical images were taken to assess the change in surface topography. The results were analyzed statistically by one-way analysis of variance (analysis of variance [ANOVA]). The rate of dissolution based on the electrolyte used decreased in the following order, viz. Tyrode's solution>artificial saliva>normal saline>Ringer's lactate/physiological serum. Apart from fluoride, chloride-based electrolytes could be an efficient alternative.

A framework for automated landslide dating utilizing SAR-Derived Parameters Time-Series, An Enhanced Transformer Model, and Dynamic Thresholding

Determining the timing of landslide occurrence is crucial for establishing an accurate, comprehensive and systematic landslide inventory while assessing the potential for reducing landslide risk. Unfortunately, many existing landslide inventories lack temporal information such as the precise time of landslide events. Optical and Synthetic Aperture Radar (SAR) sensors are the most commonly used remote sensing technologies for landslide detection. Unlike optical sensors, SAR sensors are not affected by cloudy conditions and provide valuable imagery regardless of sunlight availability. Therefore, SAR-derived parameters, i.e., SAR amplitude, interferometric coherence, and polarimetric features (alpha and entropy), offer a higher temporal resolution for detecting landslide occurrence times compared to optical data. Despite the advantages, there is currently no universally accepted automatic method for determining the time of landslide events using SAR data. This is due to the lack of anomaly labels and the high time-series volatility in detecting landslide occurrence times. Despite advances in deep-learning methods for anomaly detection in time-series, only a few of them can address these challenges in our case. In this paper, we propose an unsupervised multivariate transformed-based deep-learning model to automatically and efficiently estimate landslide occurrence times using multivariate SAR-derived parameters time-series analysis. The designed gated relative position can increase robustness and temporal context information, by learning global temporal trends in the time-series. Subsequently, the time-series of the anomaly score derived from the proposed Transformer model is analyzed using an adaptive thresholding strategy to dynamically and automatically mark anomalies related to the landslide occurrence. Our research focuses on collapsed landslides characterized by dramatic changes in ground surface topography, with a particular attention for the need of a prior knowledge about landslide boundaries. We assess the performance of the proposed methodology for several collapsed landslides including the July 21, 2020 Shaziba and 23 July, 2019 Shuicheng landslides in China, March 19, 2019 Takht landslide in Iran, June 15, 2018 Jalgyz-Jangak and May 25, 2018 Kugart landslides in Kyrgyzstan, July 7, 2018 Hitardalur landslide in Iceland, and January 25, 2019 Brumadinho landslide in Brazil. In comparison to commonly used neural networks like the LSTM algorithm, our proposed framework leads to a more accurate estimate for the time of landslide failure using time-series of SAR-derived parameters. Furthermore, our results suggest the great potential of SAR data to narrow the time period detected from optical data when used in conjunction with them.

Study on the surface topography changes of photoresist in the design and fabrication of microlens array

Study on the surface topography changes of photoresist in the design and fabrication of microlens array

Spray-deposition of graphene/polymer thin coatings on polyimide sheets for lunar dust adhesion mitigation

NASA seeks to develop technologies to mitigate dust accumulation from planetary surfaces on robotic and human systems hardware during planned space exploration missions. With a return to the Lunar surface, lunar dust threatens the durability and reusability of components and vehicles due to its fine, jagged morphology and highly abrasive nature. Lunar dust consists of particles less than 60 μm in size that are chemically reactive, electrostatically and sometimes magnetically charged. Unique materials and technologies that reduce or mitigate lunar dust adhesion will be critical to support long duration missions and eventual sustained presence on the lunar surface. The goal of this work was to prepare dust resistant, space durable polymer films to satisfy dust accumulation mitigation needs for future NASA missions. In this regard, several graphene coated polyimide thin films have been developed with surface resistivity properties in the range of 103 Ω/sq to 1011 Ω/sq and evaluated for their dust adhesion performance. Raman spectroscopy was used to characterize and assess the quality of graphene ink coated sheets while surface resistivity measurements were used to assess electrical conductivity. Scratch testing and abrasion resistance measurements were used to evaluate overall abrasion performance. Water contact angle and optical microscopy were used to evaluate changes in surface topography and chemistry. Graphene coated polyimide surfaces with charge dissipative resistivity (106 Ω/sq) demonstrated a minimum in residual particle areal coverage compared to conductive and insulating surfaces.

Surface topography and microstructure changes of ultrafine-grained graphite prepared from filler of onion-like carbon spheres by Xe ions irradiation

Onion-like carbon spheres (OLC) were doped into the traditional graphite raw material system to decrease the pore diameter to ∼400 nm, with potential for use in molten salt reactors. The obtained graphite (OLCG) prepared from OLC was subjected to 7 MeV Xe26+ irradiation in this work, and a systematic investigation was conducted to verify its irradiation behavior. The surface morphology and microstructural evolution in graphite samples under different irradiation conditions were studied with different characterization methods. The surface roughness of OLCG increased and the hill appeared at lower irradiation doses, which was similar to that of IG-110, but the filler particles of OLCG gradually become spherical at 2.5 dpa. The analysis by X-ray diffraction reveals that OLCG's graphitization degree is approaching but slightly worse compared to IG-110. Raman studies indicate that the irradiation causes an increase in defect density and in-plane disorder both in graphite. The OLC filler exhibits a greater sensitivity to radiation, leading to OLCG being slightly sensitive to radiation as compared to IG-110. Neutron irradiation of the resulting graphite should be continued as OLCG showed good irradiation resistance at low irradiation doses and had a much smaller pore diameter.

Novel near E-Field Topography Sensor for Human-Machine Interfacing in Robotic Applications.

This work investigates a new sensing technology for use in robotic human-machine interface (HMI) applications. The proposed method uses near E-field sensing to measure small changes in the limb surface topography due to muscle actuation over time. The sensors introduced in this work provide a non-contact, low-computational-cost, and low-noise method for sensing muscle activity. By evaluating the key sensor characteristics, such as accuracy, hysteresis, and resolution, the performance of this sensor is validated. Then, to understand the potential performance in intention detection, the unmodified digital output of the sensor is analysed against movements of the hand and fingers. This is done to demonstrate the worst-case scenario and to show that the sensor provides highly targeted and relevant data on muscle activation before any further processing. Finally, a convolutional neural network is used to perform joint angle prediction over nine degrees of freedom, achieving high-level regression performance with an RMSE value of less than six degrees for thumb and wrist movements and 11 degrees for finger movements. This work demonstrates the promising performance of this novel approach to sensing for use in human-machine interfaces.

Investigating the structure under the Pingting Terrace from the co-seismic surface rupture of the 2022 Guanshan earthquake

AbstractOn September 17th and 18th, 2022, shallow earthquakes with magnitudes of 6.6 (ML) and 6.8 (ML) occurred in the eastern Taiwan Longitudinal Valley, which marks the collision zone between the Philippine Sea plate and the Eurasian plate, and led to noticeable surface deformation and ruptures within 70 km. This study primarily focuses on the southernmost section of the rupture zone—the Pingting Terrace. Surface rupture locations and behaviors correspond to changes in topography, providing mutual confirmation that the deformation behavior of Pingting Terrace is complex. Based on the distribution of surface ruptures and topography changes, this study roughly divides the Pingting Terrace into northern and southern segments, using the central concave feature as a boundary. The Riedel shear model analysis results show that the principal shear directions in the northern and southern segments are N–S trending and azimuth 20°, respectively. The maximum principal stress orientations are around 135° for the northern and 155° for the southern segments. These findings align with the fault mechanical investigation of the Lichi Mélange in the northern Muken River area of the Pingting Terrace. This suggests spatial changes in shear zone orientations within the Lichi Mélange, which contribute to developing pressure ridges due to transpressional forces. As a result, the Pingting Terrace experiences rapid uplift, causing the Luliao River to migrate southward into the Beinan River, while the eastern Beinan River turns to the eastward edge of the Pingting Terrace.

Experimental study on the influence of blasting time on the surface topography of machined steel samples

The surface topography of workpieces is generated by and related to the manufacturing process. The blasting process specifically leads to dimples caused by accelerated particles hitting the surface. As the number of impacts increases over time, the surface topography changes. The scope of the study was to find a suitable areal roughness parameter or parameter set that correlates with this change. Additionally, the optimal time for creating a uniformly covered surface was analyzed. To conduct the research, an automated blast wheel process was applied. The workpieces were set on a rotating carrier with the spin wheel in the middle to ensure uniform coverage. 1.4301 steel specimens were blasted with spherical blast media at a spin wheel speed of 9000 min-1. The time varied between 1 and 20 minutes. The areal measurement was carried out by confocal microscopy. After obtaining the areal surface data, areal roughness parameters according to ISO 25178-2 and additional parameters based on motif analysis were calculated. For each measurement, 75 parameters are analyzed. The paper will present the applicability and correlation of the chosen parameters to the various blasting times.

THE OPTIMIZATION OF P3HT:PCBM THIN FILM THICKNESS FOR ORGANIC SOLAR CELLS

This study presents the complex relationship between film thickness and the properties of P3HT:PCBM thin films, looking at how different thicknesses affected their structural and optical properties. Poly(3, hexylthiophene) (P3HT) and poly(3, hexylthiophene) (PCMB) were blended in a 0.6:1 ratio and deposited using spin coating techniques. The research involve investigating the resulting changes in surface topography, optical properties, and electrical behaviour by systematically adjusting the film thickness through multiple coating repetitions ranging from one to three repetitions. Profilometric analysis revealed a direct relationship between film thickness and surface roughness, highlighting the importance of thickness in interfacial interactions within solar cells. Optical studies revealed fascinating trends in absorbance, transmittance, absorption coefficient, and extinction coefficient, highlighting the films' behaviour at various wavelengths. Surprisingly, regardless of thickness, the optical band gap remained constant, providing valuable insights for optimizing photon energy conversion. Measurements of the Hall effect revealed the effect of thickness on carrier mobility, concentration, conductivity, resistivity, and Hall voltage. Thinner films had higher mobility but lower carrier concentration, revealing a delicate balance critical for optimizing charge transport. The comprehensive analysis of the study sheds light on the complex interplay between film thickness and various properties, providing useful guidance for designing efficient P3HT:PCBM organic solar cells. This study's findings highlight the importance of precise control over film dimensions in improving the performance and efficiency of organic photovoltaic devices. This investigation paves the way for tailored approaches in the fabrication of next-generation organic solar cells, pushing the limits of renewable energy technology.

Temporal Changes in the Surface Chemistry and Topography of Reactive Ion Plasma-Treated Poly(vinyl alcohol) Alter Endothelialization Potential.

Synthetic small-diameter vascular grafts (<6 mm) are used in the treatment of cardiovascular diseases, including coronary artery disease, but fail much more readily than similar grafts made from autologous vascular tissue. A promising approach to improve the patency rates of synthetic vascular grafts is to promote the adhesion of endothelial cells to the luminal surface of the graft. In this study, we characterized the surface chemical and topographic changes imparted on poly(vinyl alcohol) (PVA), an emerging hydrogel vascular graft material, after exposure to various reactive ion plasma (RIP) surface treatments, how these changes dissipate after storage in a sealed environment at standard temperature and pressure, and the effect of these changes on the adhesion of endothelial colony-forming cells (ECFCs). We showed that RIP treatments including O2, N2, or Ar at two radiofrequency powers, 50 and 100 W, improved ECFC adhesion compared to untreated PVA and to different degrees for each RIP treatment, but that the topographic and chemical changes responsible for the increased cell affinity dissipate in samples treated and allowed to age for 230 days. We characterized the effect of aging on RIP-treated PVA using an assay to quantify ECFCs on RIP-treated PVA 48 h after seeding, atomic force microscopy to probe surface topography, scanning electron microscopy to visualize surface modifications, and X-ray photoelectron spectroscopy to investigate surface chemistry. Our results show that after treatment at higher RF powers, the surface exhibits increased roughness and greater levels of charged nitrogen species across all precursor gases and that these surface modifications are beneficial for the attachment of ECFCs. This study is important for our understanding of the stability of surface modifications used to promote the adhesion of vascular cells such as ECFCs.

Reconciling patterns of long-term topographic growth with coseismic uplift by synchronous duplex thrusting

How long-term changes in surface topography relate to coseismic uplift is key to understanding the creation of high elevations along active mountain fronts, and remains hotly debated. Here we investigate this link by modeling the development of growth strata and the folding of river terraces above the Pishan duplex system in the southern Tarim Basin. We show that synchronous duplex thrusting of two neighboring faults with varying slip rates, associated with in-sequence propagation of the Pishan thrust system, is required to explain the presence of opposite-dipping panels of growth strata on the duplex front, and basinward migration of terrace fold crests. Importantly, this process of synchronous thrusting within the duplex reconciles the discrepancy between the deformation of terrace folds at the 10−1–100 million-year timescale and the maximum coseismic uplift of the 2015 Mw 6.4 Pishan earthquake on the frontal thrust. These results suggest that topography mismatch at different time scales can reflect the long-term kinematic evolution of fault systems. Thus, our study highlights the importance of characterizing complex subsurface fault kinematics for studying topographic growth, and motivates rethinking of the mountain building process in worldwide active fold-and-thrust belts, from short-term to long-term timescales.