Irregular Surface Research Articles

Single motor driven soft actuator design based on nonuniform sheering auxetic structure

Abstract Grasping functionality is one of the core functionalities that a manipulator needs to possess. Traditional rigid manipulators are typically composed of rigid materials. However, when dealing with objects of complex shapes, irregular surfaces, or soft materials, rigid manipulators often face challenges in effectively grasping and stably holding objects due to their rigidity, which can lead to damage or failure. To address these issues, constructing manipulators using soft actuators can be highly advantageous. In most current research, soft actuators are typically composed of flexible materials and fluids, which can result in highly complex dynamic behaviors and nonlinear characteristics. This complexity makes precise modeling and control of soft actuators more challenging, necessitating the use of advanced control algorithms and techniques to mitigate nonlinear effects. In this study, we first establish a mathematical model for the torsional and bending deformations of non-uniform shearing-auxetic structures. Subsequently, we validate the reliability of the mathematical model through simulation. Finally, we design a soft actuator that requires only single-motor control, which is based on the structural design of non-uniform shearing-auxetic structures. This type of soft actuator not only simplifies control aspects but also facilitates practical modeling and manufacturing processes. Moreover, it’s capable of achieving spiral grasping functionality.

Abstract 4134589: Evaluating risk factors of embolism in patients with cardiac myxoma: A systematic review and meta-analysis

Background: Risk stratification for embolism in cardiac myxomas remains poorly explored. Goals: By this meta-analysis we studied the risk factors assicated with embolism among patients with cardiac myxoma. Methods: A comprehensive search was conducted across PubMed, Embase, Cochrane Library, and Google Scholar from their inception until January 2024. Statistical analyses were performed using Cochrane's RevMan 5.4 software. For each risk factor, the pooled odds ratio or mean difference was calculated along with the corresponding 95% confidence interval. Results: We included 18 studies in our analysis with a total population of 2601 out of which 525 patients (20.1%) had at least one episode of embolism. The pooled analyses showed that hypertension (p = 0.001), New York Heart Association I/II (p = 0.03), irregular tumor surface (p <0.00001), hyperlipidemia (p < 0.0001), coronary artery disease (p=0.01), high mean platelet volume (p=0.02), high tumor mobility (p<0.00001), were significantly associated with increased incidence of embolism. Female gender (p = 0.03) was the only risk factor associated with reduced risk. Other factors like smoking, atrial fibrillation, tumor size, age, body mass index (BMI), diabetes, left ventricular ejection fraction (LVEF), left atrial diameter (LAD) were not significantly associated with embolism (p > 0.05). Conclusion: Our study is the first to report significant pooled outcomes for gender, hyperlipidemia, coronary artery disease, mean platelet volume, and tumor mobility in the population discussed. Hypertension, New York Heart Association I/II, irregular tumor surface, hyperlipidemia, coronary artery disease, mean platelet volume and tumor mobility were significantly associated with high risk while female gender was associated with low risk of embolism. Patients with high-risk factors might benefit from early evaluation and definitive treatment (surgery).

Unripe Plantain Peel Biohydrogel for Methylene Blue Removal from Aqueous Solution

Dye contamination is a serious environmental issue, particularly affecting water bodies, driving efforts to synthesize adsorbent materials with high dye-removal capacities. In this context, eco-friendly and cost-effective materials derived from bioresidues are being explored to recycle and valorize waste. This study investigates the synthesis, characterization, and application of a biohydrogel made from unripe plantain peel (PP), modified with carboxymethyl groups and crosslinked using varying concentrations of citric acid (CA), an eco-friendly and economical organic acid. The materials were characterized by ATR-FTIR, TGA, and SEM, confirming the successful synthesis of hydrogels, which exhibited rough, irregular surfaces with micropores. Additionally, the materials were analyzed for their pH point of zero charge, swelling capacity, and methylene blue (MB) dye removal efficiency. The results indicate that the biohydrogel formed with 1% CA exhibited the most favorable characteristics for MB removal. Kinetic studies revealed that the adsorption mechanism is pH-dependent, with equilibrium being reached in 720 min. The Freundlich isotherm model provided the best fit for the adsorption data, suggesting a heterogeneous surface and a multilayer adsorption process, with a maximum retention capacity of 600.8 ± 2.1 mg/g at pH 4. These findings contribute to the development of cost-effective and efficient materials for dye removal, particularly from water bodies.

An in vitro study of orthodontic brackets bonded to transition dental zirconia: Shear bond strength, adhesive remnant index, and surface irregularities

Orthodontic treatment often involves bonding brackets to teeth, and the protocols for natural enamel differ from those for prosthodontically restored teeth. With the rising number of adult orthodontic patients, many present with zirconia crowns. This study aimed to evaluate the shear bond strength (SBS) of ceramic orthodontic brackets bonded to transition dental zirconia, which combines 3Y-TZP and 5Y-TZP powders. Ninety zirconia substrates were divided into three groups (n=30) based on transition zirconia brands (3M ESPE Lava™ Plus, Cercon® ht ML, and Katana™ Zirconia UTML) and bonded with ceramic brackets (CHIC Ceramic Roth Maxillary and Symetri Clear) using 3M™ Transbond™ XT. A control group used traditional zirconia and metal brackets. Surface treatments included 50-micron aluminium oxide abrasion and Z-Prime™ Plus application. SBS was tested post-thermocycling. Adhesive Resin Index (ARI) was scored and surface roughness was evaluated pre- and post-bonding. Group 1 (3M ESPE Lava™ Plus with CHIC Ceramic Roth Maxillary brackets) had a significantly lower SBS (mean 13.27MPa) compared to the other groups, which all had SBS values above 18.80MPa (P≤.023). Group 2 (3M ESPE Lava™ Plus with Symetri™ Clear) demonstrated a significantly higher mean ARI compared to the control group (Cercon® XT with Victory Series™ Roth), (P=.027). Additionally, significant changes in surface roughness were observed in Groups B (Cercon® ht ML) (P=.008) and C (Katana™ Zirconia UTML) (P=.016). This study determined that the shear bond strength of various transitional zirconia substrates with ceramic brackets exceeded the clinically acceptable SBS levels. The combination of 3M ESPE Lava™ Plus and Symetri™ Clear exhibited significant variation in ARI. Additionally, significant surface irregularities were observed in 3M ESPE Lava™ Plus and Cercon® ht ML following air abrasion, compared to other transitional zirconia brands.

Vehicle flow indication and identification using FBG sensors

Abstract This paper proposes a vehicle flow monitoring system utilizing fiber Bragg grating (FBG) sensor technology. The system comprises a prototype road model along with a car with varying loads. The FBG sensor is embedded in the road surface for sensing the strain induced by the vehicle movement. The laboratory experiments were conducted using an embankment model equipped with FBG sensor to identify vehicle movement under static and movable loads. Under static condition, different loads were applied on the car and the corresponding wavelength shifts have been measured using FBG-interrogator. Under dynamic condition, the vehicle was moved with certain speed and the corresponding wavelength shifts were recorded over time. The sensitivity of FBG for vehicle load sensing has been obtained as 0.3 pm/N. The proposed vehicle flow sensor system offers good accuracy and sensitivity and has potential applications for real-time vehicle flow monitoring. The proposed sensor system can be used to analyze road surface irregularities, crucial for assessing heavy-vehicle fatigue.

Comparison of intraoral and extraoral scanners for volumetric assessment before and after caries removal by the ICDAS score: a quantitative analysis.

Aimed to compare the volumetric calculations (VC) of intra-and-extraoral scanners on carious teeth before/after caries removal. 120 extracted human molars with ICDAS scores of 3, 4, and 5 were included. The teeth were scanned using an extraoral scanner (Ineos-X5, Dentsply Sirona) and three intraoral scanners (IOS) (iTero Element-5D, Align Technology; Primescan, Dentsply Sirona; Trios 4, 3Shape) before-and-after caries removal (CR). Eight Standard Tessellation Language (STL) data of each tooth sample were overlapped in Meshmixer (Autodesk) software for VC. Shapiro-Wilk, Paired Two-Sample T-test, repeated analysis of variance test statistics, and intraclass correlation coefficient (ICC) were used (p < 0.05). In initial VC, a significant difference observed between Ineos-X5 and iTero Element-5D (p < 0.001) and Ineos-X5 and Primescan (p < 0.001), regardless of the ICDAS score. No significant difference observed after CR between Ineos-X5 and iTero Element-5D (p = 0.917), Ineos-X5 and Primescan (p = 0.936), and Ineos-X5 and Trios 4 (p = 0.727) respectively. There was also no difference between the three IOS after CR (p ≥ 0.05), whereas the iTero Element-5D scanner significantly calculated less volume than Primescan and Trios-4 initially (p = 0.003). Maximum ICC was observed between the Ineos-X5 and Primescan in the ICDAS 5 score, before CR (ICC = 1, p < 0.001) and triple comparisons of iTero Element-5D, Primescan, and Trios-4 (ICC = 1, p < 0.001). Carious and irregular surfaces might affect the data collection of IOS. Intra-and-extraoral data may present negligible differences in the volumetric calculation, depending on the caries status and anatomical properties. These differences and factors may be important for future artificial intelligence networks that simulate the aftermath of caries removal. The IOSs tested in the current study can successfully collect data from irregular, deep and shallow cavities after caries removal.

Effect of bismuth oxide on radiation shielding and interaction characteristics of polyvinyl alcohol-based polymer: Potential use in medical apron design

This study evaluated radiation shielding and interaction characteristics of polyvinyl alcohol (PVA) polymer separately doped with 10% and 20% Bi2O3 respectively for medical apron design and shielding special electronic installations. Prepared samples were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The EDS results showed that Carbon (C), Oxygen (O), and bismuth (Bi) elements were the predominant elements present in the prepared samples. The SEM result displaced surface irregularities due to a special bonding matrix between PVA and Bi2O3. Mass attenuation coefficient (MAC), effective atomic number (Zeff), Half value layer (HVL), Mean free path (MFP), Fast neutron removal cross-section (R), Total Mass Stopping Power (TSP), and photon Range (R) of the prepared polymer composites (PV-1Bi and PV-2Bi) were evaluated with XCOM and PHITS computer programs. Results showed that the MAC of the prepared polymer samples was significantly higher than some recently developed composites at 0.662 MeV and 1.25 MeV gamma energy. Therefore, polyvinyl alcohol (PVA) polymer doped with Bi2O3 should be deployed in medical apron design and shielding special electronic installations where flexibility and high adhesion abilities are crucial.

Flexible Au@Ag/PDMS SERS imprinted membrane combined with molecular imprinting technology for selective detection of MC-LR

In this study, a core–shell structured bimetallic nano-cube, Au@Ag NCs, was prepared by seed-mediated growth procedure. The array structure of Au@Ag NCs was achieved at the interface through the autonomous assembly technique at the three-phase boundary. Employing polydimethylsiloxane (PDMS) as a flexible carrier, the array structure was effortlessly transferred to the PDMS membrane, bypassing the need for rigid substrates through a simple “pasting” method. This yielded a highly flexible and transparent SERS substrate with an array structure (Au@Ag NCs/PDMS membrane, AAP). In order to promote the selective detection property to the practical samples, molecularly imprinted polymers (MIPs) were coated on the surface of membrane to prepare the imprinted membrane (Au@Ag NCs/PDMS-MIMs, AAP-MIMs). It was demonstrated from the results that the AAP-MIMs exhibited high SERS sensitivity, stability, and uniformity. Furthermore, the flexible substrate possessed commendable mechanical strength, and facilitated the detection of analytes on irregular surfaces. In summary, this substrate held promising potential for practical on-site detection and analysis of specific target substances.

Environmental associations and the paleoecological significance of the genus Pyxidicula Ehrenberg,1838 and Pyxidicula muskegii sp. nov. in the Hudson and James Bay region peatlands, Canada

An environmental proxy routinely used in paleoecological studies of peatlands is testate amoebae, which are used to infer successional and hydrological shifts through time. However, since many species of protists globally remain undescribed, important ecological information about community assemblages and their interaction with environmental conditions in both the past and present has potential gaps. During the analysis of testate amoeba assemblages from peat cores across the Hudson and James Bay region of Canada, a testate amoeba that has not been formally described was discovered with high abundance in subfossil assemblages (up to 50%). We describe this new species, Pyxidicula muskegii sp. nov., using morphometric measurements of tests from these peat core records and demonstrate its environmental preferences using modern samples collected from the same region. The hemispheric shape and irregular areolar surface pattern on the test, along with its preference for lawns in both fens and bogs, support that P. muskegii is a new species. This species is also found in much lower relative abundance in modern samples (&lt;3%) than in paleo-peat core records. This difference in modern and paleo-assemblage suggests that there is a taphonomic bias in their relative abundance with depth, which we attribute to their organic test that is less prone to decomposition. Therefore, it is critical to include rare taxa within future transfer function models to incorporate their environmental tolerances and improve model predictions.

INVESTIGATION OF THE MINERAL PROFILE, STRUCTURAL AND THERMAL PROPERTIES OF BLENDS OF TRAPIÁ POWDER WITH TROPICAL FRUITS

Trapiá is widely distributed throughout Brazilian territory and in Latin American countries, yet its commercial potential is overlooked due to insuficiente knowledge of its bioactive properties and a lack of studies on pulp processing. Aiming to enhance the value of Trapiá by improving its nutraceutical properties through the incorporation of minerals, vitamins, and the popularity of tropical fruits, this study investigated the mineral potential, structural properties, and thermal characteristics of mixtures of trapiá pulp with orange, lemon, and pineapple pulps, which were converted into powders through spray drying and freeze-drying. The powders were evaluated for their mineral profile; structural properties were assessed through scanning electron microscopy (SEM), crystallinity was determined by X-ray diffraction (XRD), and the analysis of absorption spectroscopy in the infrared region (FTIR). Finally, the thermal profile was evaluated using thermogravimetry (TG/DTG). The trapiá powders combined with orange, lemon, and pineapple were found to be sources of magnesium and potassium, with appreciable levels of calcium. The powders containing lemon also provided copper, while those mixed with pineapple were sources of manganese. SEM images revealed spherical particles with smooth surfaces in the powders obtained from spray drying, whereas the freeze-dried powders exhibited larger particle sizes with irregular dimensions and rough surfaces. The thermogravimetric analysis demonstrated that the powders possessed high thermal stability, making them suitable for use in the food industry. The data from this study indicate that these powders are promising for use in various industrial formulations, characterized by their high mineral content and notable thermal stability.

Generalizable classification methodology for quantification of atomized feedstock powder by 3D X-ray tomography data and machine learning

Laser powder bed fusion (LPBF) is currently being applied to manufacture engineering-crucial components. To maintain consistent part quality, accuracy and speed in the quality assurance of atomized metal feedstock powder is critical. 3D x-ray tomography (XRT), coupled with machine learning algorithms, provides a transformative route to powder characterization and classification. A recycled AA7050 feedstock powder was studied through XRT to demonstrate a scheme for classification of highly deformed particles which vary both in geometric morphology and degree of surface irregularity. Manual, unsupervised, and supervised classification algorithms were optimized to reproduce visual classification, demonstrating how different approaches to algorithm training may provide a balance between the amount of training data and acceptable final accuracy. The reported approach provides a robust methodology that links 3D measurements and powder classification as means to control powder-induced defects and improve mechanical performance in printed parts.

Discretization-independent node-based shape optimization with the Vertex Morphing method using design variable scaling

AbstractThe Vertex Morphing method is a node-based shape parameterization that uses an explicit filtering approach to regularize the optimization problem and generate smooth shapes. It has been successfully applied to shape optimization problems of industrial size in recent years. This work investigates in detail how irregular discretizations, design surface boundaries, and complex geometries can influence the progress of a gradient-based optimization using the standard Vertex Morphing formulation. A sensitivity weighting approach based on the available shape morphing functions is presented, which eliminates all of the aforementioned influences. Subsequently, a design variable scaling strategy is developed that transforms the optimization problem into an alternative design space and allows the use of arbitrary, even highly irregular surface discretizations in combination with black-box optimization algorithms for shape optimization with the Vertex Morphing method. Illustrative academic examples and an application case of an additively manufactured part are presented to support the work.

Integrated respiratory toxicity of municipal wastewater to human bronchial epithelial cells and 3D bronchospheres

Respiratory symptoms have been reported in wastewater treatment workers and residents living close to sewage treatment plant. However, toxicological research about the respiratory hazards of municipal wastewater is scarce. The present study aims to gain insight into the comprehensive respiratory hazards induced by the contaminant mixtures in municipal wastewater. The integrated respiratory hazards of effluents from four secondary wastewater treatment plants (SWTPs), a tertiary wastewater treatment plant (TTP), and a constructed wetland (CW) were evaluated using normal human bronchial epithelial cells (NHBE) bioassay, and toxicity reduction efficiency of various treatment techniques was analyzed. Effluents caused cytotoxicity, oxidative damage, inflammation response with the increased levels of IL-6 and CXCL8, and impaired barrier integrity with decreased expressions of ZO-1 and occludin in NHBE. Further, the effluents inhibited the development of 3D bronchospheres, increased irregular surface and cell debris, and suppressed the formation of luminal structures. TTP E effluent significantly increased the expression of MUC5AC in bronchospheres. The integrated biomarker response (IBR) of the influent was removed by 40.2% at SWTPs, 18.2% at TTP, and 36.6% at CW, respectively. The IBR of the final effluents from SWTPs, TTP, and CW were 7.2, 7.7, and 7.7, respectively. Significant correlation with toxicity biomarkers was frequently observed for stearyl alcohol, o-cresol, phenanthrene, butylated hydroxytoluene, and dimethyl phthalate. The present study provided human relevant evidence concerning the adverse respiratory effects associated with discharge. The necessity for deep water treatment, performance optimization, and the potential means were suggested for improving water quality and protecting respiratory health.

Green Synthesis, Characterization and Pharmaceutical Applications of Biocompatible Zinc Oxide Nanoparticles Using Heliotropium rariflorum Stocks

Background: Zinc oxide nanoparticles are safe, non-toxic, and biocompatible. These NPs are used in food packaging materials, self-cleaning glass, ceramics, deodorants, sunscreens, paints, coatings, ointments, lotions, and as preservatives. This study explored the biological potential of ZnO nanoparticles synthesized using H. rariflorum. Methods: In vitro antibacterial and antifungal activities against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans, Penicillium notatum, Aspergillus flavus, Aspergillus niger and Aspergillus solani were determined. Antioxidant activity was explored using the DPPH radical scavenging method. In vivo analgesic, antipyretic and sedative potential of synthesized nanoparticles was investigated using a mouse model. Results: SEM with various magnification powers showed that some particles were spherical while some were aggregated, flake-shaped, and hexagonal with rough and irregular surfaces. The EDX analysis revealed Zn (12.63%), O (22.83%) and C (63.11%) with trace quantities of Si (0.40%), Ca (0.54%) and P (0.49%). The XRD pattern indicated an amorphous state, with no peaks observed throughout the spectrum. The UV–visible spectrophotometry revealed a characteristic absorption peak at 375 nm, indicating the presence of ZnO nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) displayed several small peaks between 1793 and 2370 cm−1, providing evidence of the presence of different kinds of organic compounds with different functional groups. ZnO-NPs showed dose-dependent antibacterial and antifungal potential against all strains. Staphylococcus aureus and Candida albicans were the most susceptible strains. The nanoparticles exhibited a maximum antioxidant effect of 85.28% at 100 μg/mL. In this study, the acute toxicity test showed no mortality, and normal behavior was observed in mice at ZnO-NP doses of 5, 10, and 20 mg/kg. For analgesic and antipyretic activities, a two-way ANOVA revealed that dose, time, and the interaction between dose and time were significant. In contrast, the samples had a non-significant effect on sedative activity. Conclusions: This innovative study suggests a potential use of plant resources for managing microbes and treating various diseases, providing a scientific basis for the traditional use of H. rariflorum.

Early expression of osteopontin glycoprotein on the ocular surface and in tear fluid contributes to ocular surface diseases in type 2 diabetic mice.

Osteopontin (OPN) is a glycosylated, secreted phosphoprotein known to be elevated in both human and mouse retinas during various stages of diabetic retinopathy. However, its specific roles in modulating ocular surface dynamics and immune responses in diabetes remain unexplored. This study aims to investigate the role of OPN in the development of ocular surface disease (OSD) in type 2 diabetic (T2D) mice. Three- to four-week-old C57BL/6 wild-type (WT) and OPN-knockout (OPN-/-) mice were fed a high-fat diet (HFD) and were rendered diabetic by streptozotocin (STZ; 40 mg/kg body weight) in citrate buffer (vehicle); non-diabetic controls were injected with vehicle alone. Diabetes was confirmed if blood glucose levels were >200 mg/dL, measured 1-2 weeks post-STZ injection. Control, age- and sex-matched db/db diabetic mice fed a standard chow diet were also included in this study. Ocular surface inflammation was assessed using ELISA to quantify inflammatory cytokine proteins and wheat germ agglutinin (WGA) staining was utilized to highlight corneal surface irregularities. Clinical signs were evaluated by corneal fluorescein staining, tear production measurements, and tear sodium (Na+) concentration assessments. These evaluations were conducted 4, 6, 8 and 16-weeks post-diabetes onset in WT and OPN-/- mice and were compared to those obtained in non-diabetic controls. Statistical analysis was performed using a two-way ANOVA, with significance set at P < 0.05. Both WT and OPN-/- mice developed T2D within 4 and 8 weeks, respectively, following HFD + STZ treatment. Corneal OPN levels in WT diabetic mice increased ~2-fold at 2 weeks and ~4-fold at 16 weeks compared to non-diabetic controls, with similar elevations observed in their tear fluid. Diabetic db/db mice also exhibited elevated OPN levels in the blood and ocular surface, which persisted as diabetes progressed. Enhanced fluorescein staining, indicating corneal irregularities, appeared in WT mice at 8 weeks and in OPN-/- mice at 10 weeks post-T2D induction. Additionally, WGA staining showed a significant reduction in fluorescence intensity in WT mice treated with HFD and STZ, confirming corneal surface irregularities that were delayed in OPN-/- mice. Elevated tear sodium concentration was observed in both WT and OPN-/- diabetic mice without affecting tear production rates. Notably, OPN levels increased early, at week 2, following HFD and STZ treatment, preceding changes in interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and matrix metalloproteinase-9 (MMP-9). Upregulation of IL-6 became apparent at 6 weeks in WT mice and was delayed until 10 weeks in OPN-/- mice post-T2D induction. Elevated OPN levels were detected early post-T2D induction in diabetic WT and db/db mice corneas without initial subclinical changes. This early increase in OPN precedes other proinflammatory cytokines associated with eventual ocular surface inflammation as diabetes progresses. Persistence of OPN also correlated with clinical signs such as increased corneal surface irregularities and elevated tear Na+ concentration. Future research will explore OPN's role as a biomarker in ocular surface disease (OSD), including dry eye disease (DED), and investigate its impact on inflammatory processes and other mechanistic pathways in diabetic ocular complications.

Multilayer Bionic Tunable Strain Sensor with Mutually Non‐Interfering Conductive Networks for Machine Learning‐Assisted Gesture Recognition

AbstractFlexible strain sensors capable of acquiring tiny mechanical signals and attaching to various irregular surfaces are becoming prevalent in physiological measurement, soft robotics, and human‐machine interaction. However, the advancement of flexible strain sensors is substantially impeded by the intrinsic compromise between sensitivity and the range of detectable signals. Inspired by the multilayer structure of nacre in nature, a carbon nanotubes (CNTs)/graphene (GR)/graphene (GR)/thermoplastic polyurethane (TPU) mat (CGGTM) is prepared by electrospinning and high‐pressure spraying technology. By designing a multilayer structure with mutually non‐interfering conductive networks, the resulting CGGTM possesses a low detection limit (0.05% strain), high sensitivity (gauge factor, GF &gt; 152537), large detection range (up to 364% strain), fast response/recovery time (80 ms/100 ms), and excellent cyclic durability (up to 1000 cycles). Furthermore, the CGGTM also exhibits satisfactory triboelectric performances when assembled into a triboelectric nanogenerator (TENG, 3 × 3 cm2), including high triboelectric output (open‐circuit voltage Voc = 135.4 V, short‐circuit current Isc = 1.25 µA) and power density (88 mW m−2), enabling reliable power supply, self‐powered sensing, and pulse monitoring capability. Finally, CGGTM is successfully applied to the collection of biological signals and multi‐gesture motion recognition assisted by machine learning algorithms, which holds promise for intelligent interaction with gestures in the future.

Direct laser writing of curved SERS for light-guided enhancement

Flexible SERS substrates, typically used on irregular surfaces, have unexplored optomechanical effects that could enhance performance. We developed a micromechanically bending structure, i.e. microbender, to study how bending affects SERS substrates’ performance. Optical simulations of nanopillar arrays on micro-curved surfaces showed a 25–134 % improvement in mean-field localization at the pillar tips for arrays with pillar diameters of 0.4–1 μm, pitches of 0.5–0.8 μm, and heights of 0.5–4.5 μm. Raman measurements showed that SERS intensity increases when in a curved state due to enhanced light scattering, guiding, and field localization. A curved array of 6 μm tall pillars (0.5 μm diameter, 1 μm spacing) produced Raman intensities similar to dense single-voxel arrays with shorter 0.8 μm pillars (0.2 μm diameter, 0.2 μm gaps) in the planar state. This finding suggests that low resolution fabrication technologies can produce curved SERS substrates with similar performance to high resolution planar SERS, offering an alternative to the current “smaller is better” trend through post-fabrication manipulation.

Multiscale Analysis of Surface Topography for Engineering Applications in the Casting Industry

This paper presents the results of studies aimed at assessing the impact of the molding process on the variability of surface irregularities of casting models. This research was conducted using a selected multiscale method, i.e., wavelet transformation, in both discrete and continuous perspective. The test samples were made both based on traditional methods of manufacturing casting models, i.e., machining of aluminum and wood, as well as using three additive technologies. The impact of the forming process on the variability of the topography of the produced models was evaluated. This research comprehensively relates to the assessment of the applicability of additive technologies, which are increasingly used in various industrial areas, as well as the impact of the process on surface topography in relation to scale. The statistical assessment based on the ANOVA analysis demonstrated that it is possible to distinguish between the surfaces before and after a specific number of forming cycles. Studies have shown that the impact of the forming process is relatively small, mainly affecting the long-term irregularity components, and there are no functional dependencies in terms of the impact of the forming process on the variation in surface topography in relation to the manufacturing method or its parameters.

Research on wheel–rail impact dynamics due to combined rail weld irregularities and polygonal wheel effects considering 3D contact geometry

The geometric irregularities of rail welds and polygonal wheels are common defects observed in high-speed railways, leading to the generation of high-frequency impact forces and vibrations in the wheel–rail contact system. This research establishes a novel vehicle-track coupled dynamic model that incorporates a 3D wheel–rail contact model using meshing grid and conjugate gradient methods to study the high-magnitude wheel–rail impact forces caused by rail weld irregularities and polygonal wheel combinations. The primary objective of this study is to develop a precise 3D contact model that incorporates the actual geometry of wheel and rail surface irregularities into the calculation of vehicle-track dynamic interactions. The study evaluates the effects of 3D rail weld irregularities and polygonal wheels on wheel–rail dynamic interaction by comparing results with those obtained from a conventional vehicle-track coupled model that considers a 2D contact model. The results show that the lengths and depths of polygonal wheels and rail weld irregularities, as well as vehicle speeds, significantly increase the wheel/rail dynamic impact forces. The results also indicate that the widening of irregularities not only significantly affects the wheel–rail contact force but also has an important influence on the contact stiffness.

Induced magnetic field and thermal regulation of synovial fluid flow through irregular surfaces with first-order slip and gold nanoparticles

ABSTRACT The current computational exploration develops a poroelastic model of the knee cartilage to elevate its temperature under cyclic sinusoidal loading. A contributing factor to the rise in temperature is this tissue’s viscous dissipation, which converts some of the mechanical energy supplied into heat. The manipulation of cartilage temperature is mostly reliant on the movement of synovial fluid inside the space between joints and within the permeable cartilage. We developed the region flow model in the presence of induced magnetic fields and gold nanoparticles, which enhanced the efficiency of joint lubrication by boosting the load-carrying capacity. We dealt with the problem for two different models. Model 1 assumes that viscosity is exponentially dependent on concentration. The shear thinning index in Model 2 is regarded as a concentration-dependent variable. We introduce these models for a complex wavy surface, where the first-order slip effect occurs. We modified the governing problem by assuming a long wavelength and a low Reynolds number. We followed up with a computational analysis utilizing the Rung–Kutta–Merson approach with Newton iteration in a shooting and matching strategy. We have conducted detailed comparisons between Model 1 and Model 2. The graphical findings have been shown for the distributions of velocity, temperature, and nanoparticle concentration. Additionally, the pressure gradients, streamlines, and axially generated magnetic fields have also been included. These results are presented for numerous physical parameters. The mechanics of trapping are thoroughly examined through the use of streamlines.