Search Results (6,442)

Traditional leaf chlorophyll estimation using Soil Plant Analysis Development (SPAD) devices and spectrophotometers is a high-cost mechanism in agriculture. Recently, research on chlorophyll estimation using leaf camera images and machine learning has been seen. However, these techniques use self-defined image color combinations where the system performance varies, and the potential utility has not been well explored. This paper proposes a new method that combines an improved contact imaging technique, the images’ original color parameters, and a 1-D Convolutional Neural Network (CNN) specifically for tea leaves’ chlorophyll estimation. This method utilizes a smartphone and flashlight to capture tea leaf contact images at multiple locations on the front and backside of the leaves. It extracts 12 different original color features, such as the mean of RGB, the standard deviation of RGB and HSV, kurtosis, skewness, and variance from images for 1-D CNN input. We captured 15,000 contact images of tea leaves, collected from different tea gardens across Assam, India to create a dataset. SPAD chlorophyll measurements of the leaves are included as true values. Other models based on Linear Regression (LR), Artificial Neural Networks (ANN), Support Vector Regression (SVR), and K-Nearest Neighbor (KNN) were also trained, evaluated, and tested. The 1-D CNN outperformed them with a Mean Absolute Error (MAE) of 2.96, Mean Square Error (MSE) of 15.4, Root Mean Square Error (RMSE) of 3.92, and Coefficient of Regression ($R^2$) of 0.82. These results show that the method is a digital replication of the traditional method, while also being non-destructive, affordable, less prone to performance variations, and simple to utilize for sustainable agriculture. Full article

The focus of the study in this article is analyzing the electrochemical properties of molybdenum disulfide on miscible poly(methyl methacrylate)-poly(lactic acid) blends for supercapacitors. The interaction between molybdenum disulfide and miscible poly(methyl methacrylate)-poly(lactic acid) blends, affinity toward water, surface morphology, and mechanical properties are inspected by Fourier transform infrared spectroscopy, water contact angle, scanning electron microscopy, and universal testing machine, respectively. Among the developed membranes, 0.75 wt% of molybdenum disulfide on poly(methyl methacrylate)-poly(lactic acid) shows better electrochemical performances. It exhibits a maximum specific capacitance of 255.5 F g⁻¹ at a current density of 1.00 mA g⁻¹, maximum energy density of 22.7 Wh kg⁻¹, and maximum power density of 360 W kg⁻¹. A cycle study reveals 92% capacitance retention after 2500 cycles. The designed supercapacitor device shows a maximum specific capacitance of 1240 μF g⁻¹ at a current density of 0.5 μA g⁻¹, maximum energy density of 43 μWh kg⁻¹, and maximum power density of 700 μW kg⁻¹. Flexible membranes of molybdenum disulfide are expected to be a potent combination for supercapacitor applications. Full article

Piston–cylinder pairs are very common in industrial mechanisms. While a piston is primarily designed for axial reciprocating motion, the occurrence of secondary motions—lateral and rotational—due to the small clearance between the piston and the cylinder may lead to frictional contact, energy loss, wear and an increase in unwanted leakage. This study focuses on mitigating the secondary motion of a ringless piston. The influence of a Rayleigh step bearing and partial surface texturing with numerous micro-dimples on the dynamic stability of the secondary motion is studied. A linear model was used to obtain the trajectory of the secondary motion and Floquet theory was applied to analyze the stability and draw stability maps. The influence of various texturing and step parameters, including the dimple area density and aspect ratio for partial texturing, as well as the length and depth of treatment for both partial texturing and step profiles, on the stability of the secondary motion was examined. The normalization method is presented, enabling the expansion of the results for various operating conditions and geometries. Conclusions and guidelines regarding the optimal parameters, in terms of a wider stability range and higher decay rate, are formulated. Full article

As semiconductor integration scales expand and chip sizes shrink, Through Silicon Via (TSV) technology advances towards smaller diameters and higher aspect ratios, posing significant challenges in thermo-mechanical reliability, particularly within interposer substrates where mismatched coefficients of thermal expansion exacerbate issues. This study conducts a thermo-mechanical analysis of TSV structures within multi-layered complex interposers, and analyzes the thermal stress behavior and reliability under variable temperature conditions (−55 °C to 85 °C), taking into account the typical electroplating defects within the copper pillars in TSVs. Initially, an overall model is established to determine the critical TSV locations. Sub-model analysis is then employed to investigate the stress and deformation of the most critical TSV, enabling the calculation of the temperature cycle life accordingly. Results indicate that the most critical TSV resides centrally within the model, exhibiting the highest equivalent stress. During the temperature cycling process, the maximum deformation experiences approximately periodic variations, while the maximum equivalent stress undergoes continuous accumulation and gradually diminishes. Its peak occurs at the contact interface corner between the TSV and Redistribution Layer (RDL). The estimated life of the critical point is 3.1708 × ${10}^5$ cycles. Furthermore, it is observed that electroplating defect b alleviates thermal stress within TSVs during temperature cycling. This study provides insights into TSV thermal behavior and reliability, which are crucial for optimizing the design and manufacturing processes of advanced semiconductor packaging. Full article

Polarization and charge-transfer interactions play an important role in ligand–receptor complexes containing metals, and only quantum mechanics methods can adequately describe their contribution to the binding energy. In this work, we selected a set of benzenesulfonamide ligands of human Carbonic Anhydrase II (hCA II)—an important druggable target containing a Zn²⁺ ion in the active site—as a case study to predict the binding free energy in metalloprotein–ligand complexes and designed specialized computational methods that combine the ab initio fragment molecular orbital (FMO) method and GRID approach. To reproduce the experimental binding free energy in these systems, we adopted a machine-learning approach, here named formula generator (FG), considering different FMO energy terms, the hydrophobic interaction energy (computed by GRID) and logP. The main advantage of the FG approach is that it can find nonlinear relations between the energy terms used to predict the binding free energy, explicitly showing their mathematical relation. This work showed the effectiveness of the FG approach, and therefore, it might represent an important tool for the development of new scoring functions. Indeed, our scoring function showed a high correlation with the experimental binding free energy (R² = 0.76–0.95, RMSE = 0.34–0.18), revealing a nonlinear relation between energy terms and highlighting the relevant role played by hydrophobic contacts. These results, along with the FMO characterization of ligand–receptor interactions, represent important information to support the design of new and potent hCA II inhibitors. Full article

The present work investigates the physicochemical stability of spray paints when irradiated with artificial solar light (at spectral range 300–800 nm). This research highlights the importance of understanding the materials used in street art and public murals, recognising them as a significant component of contemporary cultural heritage. By examining the stability and degradation of spray paints toward solar light exposure, the study aims to contribute to the preservation of contemporary murals, which reflect current social and cultural narratives. A physicochemical approach was employed for the study of spray paints’ physical and thermal properties, as well as the effect of specific photochemical ageing reactions/processes. The photochemical ageing results were compared with reference (unaged) samples. Specifically, a multi-technique approach was applied using stereo microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, colorimetry, glossimetry, differential scanning calorimetry (DSC), UV-Vis spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and pyrolysis-GC/MS (Py-GC/MS). The photodegradation of the spray paints occurred from the first 144 h of solar light irradiation, resulting in changes in morphology, colour, gloss, roughness, and wettability. Regarding photochemical stability, ageing seems to affect the binders more than the synthetic organic pigments and the inorganic fillers. In particular, acrylic binders showed small chemical changes, whereas the alkyd, nitrocellulose, and styrene binders underwent severe chemical modification. The results suggest that simulated daylight irradiation prompts the migration of additives toward the surface of the spray paint films. In addition, the results of the analyses on the white spray paints in comparison with the coloured paints (from the same manufacturer) showed that there seems to be an active distinct photoageing mechanism involving titanium dioxide, but the whole issue needs further investigation. Full article

In this paper, a new method involving a wear-resistant and reusable template is proposed for the preparation of high-mechanical-strength superhydrophobic polymer film based on wire electrical discharge machining (WEDM). A solid−liquid-contact-angle simulation model was established to obtain surface-texture types and sizes that may achieve superhydrophobicity. The experimental results from template preparation show that there is good agreement between the simulation and experimental results for the contact angle. The maximum contact angle on the template can reach 155.3° given the appropriate triangular surface texture and WEDM rough machining. Besides, the prepared superhydrophobic template exhibits good wear resistance and reusability. PDMS superhydrophobic polymer films were prepared by the template method, and their properties were tested. The experimental results from the preparation of superhydrophobic polymer films show that the maximum contact angle of the polymer films can be up to 154.8° and that these films have good self-cleaning and anti-icing properties, wear resistance, bending resistance, and ductility. Full article

Background: The most frequent body composition alterations in post-COVID-19 syndrome include low muscle mass, dynapenia, sarcopenia, and obesity. These conditions share interconnected pathophysiological mechanisms that exacerbate each other. The relationship between body composition phenotypes and metabolic abnormalities in post-COVID-19 syndrome remains unclear. Objective: To evaluate the association between body composition phenotypes and insulin resistance (IR) and metabolic abnormalities in non-diabetic individuals with post-COVID-19 syndrome. Methods: A cross-sectional, single-center study involving 483 subjects with post-COVID-19 syndrome following moderate to severe acute COVID-19 requiring hospitalization. Individuals with diabetes, those who declined to participate, or those who could not be contacted were excluded. Body composition phenotypes were classified as normal weight, dynapenia, sarcopenia, dynapenic obesity, and sarcopenic obesity (SO). Results: The average age was 52.69 ± 14.75 years; of note, 67.08% were male. The prevalence of body composition phenotypes was as follows: 13.25% were of normal weight, 9.52% had dynapenia, 9.94% had sarcopenia, 43.69% had obesity, 18.84% had dynapenic obesity, and 4.76% had SO. Additionally, 58.18% had IR. Obesity (OR: 2.98, CI95%; 1.64–5.41) and dynapenic obesity (OR: 4.98, CI95%; 1.46–6.88) were associated with IR. Conclusion: The most common body composition phenotypes were obesity, dynapenic obesity, and dynapenia. Furthermore, obesity and dynapenic obesity were associated with IR in post-COVID-19 syndrome. Full article

There is a need for the assessment of respiratory hazard potential and mode of action of carbon nanotubes (CNTs) before their approval for technological or medical applications. In CNT-exposed lungs, both alveolar macrophages (MФs), which phagocytose CNTs, and alveolar epithelial type II cells (AECII cells), which show tissue injury, are impacted but cell–cell interactions between them and the impacted mechanisms are unclear. To investigate this, we first optimized an air–liquid interface (ALI) transwell coculture of human AECII cell line A549 (upper chamber) and human monocyte cell line THP-1 derived macrophages (lower chamber) in a 12-well culture by exposing macrophages to CNTs at varying doses (5–60 ng/well) for 12–48 h and measuring the epithelial response markers for cell differentiation/maturation (proSP-C), proliferation (Ki-67), and inflammation (IL-1β). In optimal ALI epithelial-macrophage coculture (3:1 ratio), expression of Ki-67 in AECII cells showed dose dependence, peaking at 15 ng/well CNT dose; the Ki-67 and IL-1β responses were detectable within 12 h, peaking at 24–36 h in a time-course. Using the optimized ALI transwell coculture set up with and without macrophages, we demonstrated that direct interaction between CNTs and MФs, but not a physical cell–cell contact between MФ and AECII cells, was essential for inducing immunotoxicity (proliferative and inflammatory responses) in the AECII cells. Full article

In the past decade, triboelectric nanogenerators (TENGs) have attracted significant attention across various fields due to their compact size, light weight, high output voltage, versatile shapes, and strong compatibility. However, substantial wear at solid–solid contact interfaces presents a major obstacle to the electrical output stability of TENGs. The objective of this study is to investigate the output performances of TENGs lubricated with TiO₂-doped oleic acid. The results suggest that the triboelectrical performances of the polyimide (PI) film sliding against a steel ball under 0.1 wt% TiO₂-doped oleic acid are significantly improved compared to those under dry conditions; the growth rates are 35.2%, 103.6, and 85.6%, respectively. Moreover, the coefficient of friction dropped from 0.31 to 0.066. The wear and performance enhancement mechanism are also analyzed. This study provides an effective approach to improve both the electrical performances and tribological behaviors. Full article

Background: Fibromyalgia is a complex multifaceted syndrome primarily characterised by chronic musculoskeletal pain, fatigue, and functional symptoms. Although FM is known to be associated with several comorbidities, the aim of this systematic review was to comprehensively examine the available evidence regarding the relationship between FM and dermatological manifestations. Methods: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and MedLine and Web of Science (WOS) databases were searched up to June 2023. After removing duplicate records, 21 articles were deemed eligible for inclusion in the qualitative synthesis. Results: Overall, the included studies revealed an increased frequency of FM among patients with cutaneous diseases, including psoriasis, chronic urticaria, contact allergy, acneiform disorders, hidradenitis suppurativa, and vitiligo. Additionally, the presence of comorbid FM may intensify skin conditions, which has a negative impact on quality of life and vice versa. Conclusions: Although the causal mechanisms of FM are still far from being understood, this systematic review suggests a relationship between FM and skin disorders. However, further research is encouraged in this area. Full article

This study investigates the post-liquefaction monotonic undrained shearing behavior of cemented sand at the macro- and microscales, using the discrete element method. A series of cyclic undrained triaxial tests with different stress amplitudes and post-liquefaction monotonic undrained triaxial tests were simulated on cemented sand with diverse cement contents (CCs). For comparison, a series of monotonic undrained triaxial tests on cemented sand without liquefaction (virgin cemented sand) were also modeled. The macroscopic behavior was analyzed in conjunction with the microscopic characteristics of the assembly, such as the deviator fabric of contact normal orientation, mechanical coordination number, energy components, and bond breakage. The results show that the DEM model can capture the effect of CC and cyclic stress ratio (CSR) on the undrained shear strength, stiffness, and pore pressure observed in laboratory experiments. Referring to the virgin specimen, with an increase in CC, the mechanical coordination number and the input work increment increase, while the deviator fabric for total contacts changes irregularly, leading to a greater initial stiffness and shear strength. In the case of the liquefied specimen, the smaller initial mechanical coordination number results in a very low initial stiffness regardless of CC. Contrary to the uncemented sand, both the mechanical coordination number and the input work increment decrease with an increasing CSR for the cemented sand. The microstructure evolution governs the effect of cementation level and liquefaction history on the macroscopic post-liquefaction behavior. Full article

Hot water treatment (HWT) is a versatile technique for synthesizing metal oxide nanostructures (MONSTRs) by immersing metal substrates in hot water, typically in glass beakers. The proximity of substrates to the heat source during HWT can influence the temperature of the substrate and subsequently impact MONSTR growth. In our study, zinc (Zn) substrates underwent HWT at the base of a glass beaker in contact with a hot plate and at four different vertical distances from the base. While the set temperature of deionized (DI) water was 75.0 °C, the substrate locations exhibited variations, notably with the base reaching 95.0 °C. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy showed stoichiometric and crystalline zinc oxide (ZnO) nanorods. ZnO rods on the base, exposed to higher temperatures, displayed greater growth in length and diameter, and higher crystallinity. Nanorods with increasing vertical distances from the base exhibited a logarithmic decrease in length despite identical temperatures, whereas their diameters remained constant. We attribute these findings to crucial HWT growth mechanisms like surface diffusion and “plugging”, influenced by temperature and water flow within the beaker. Our results provide insights for optimizing synthesis parameters to effectively control MONSTR growth through HWT. Full article

This paper proposes a novel finger-individuating exoskeleton system with a non-contact leader–follower control strategy that effectively combines motion functionality and individual adaptability. Our solution comprises the following two interactive components: the leader side and the follower side. The leader side processes joint angle information from the healthy hand during motion via a Leap Motion Controller as the system input, providing more flexible and active operations owing to the non-contact manner. Then, as the follower side, the exoskeleton is driven to assist the user’s hand for rehabilitation training according to the input. The exoskeleton mechanism is designed as a universal module that can adapt to various digit sizes and weighs only 40 g. Additionally, the current motion of the exoskeleton is fed back to the system in real time, forming a closed loop to ensure control accuracy. Finally, four experiments validate the design effectiveness and motion performance of the proposed exoskeleton system. The experimental results indicate that our prototype can provide an average force of about 16.5 N for the whole hand during flexing, and the success rate reaches 82.03% in grasping tasks. Importantly, the proposed prototype holds promise for improving rehabilitation outcomes, offering diverse options for different stroke stages or application scenarios. Full article

Transparent films with excellent antibacterial properties and strong mechanical properties are highly sought after in packaging applications. In this study, Ag/SiO₂ nanoparticles were introduced into a mixed solution of chitosan (CS) and polyvinyl alcohol (PVA) and a Ag/SiO₂-CS-PVA transparent film was developed. The excellent properties of the film were confirmed by light transmittance, water contact angle tests and tensile tests. In addition, for the antibacterial test, the antibacterial properties of the sample against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were explored, and the average size of the bacteriostatic circle was measured by the cross method. The final results show that Ag/SiO₂-CS-PVA transparent film has the advantages of good antibacterial properties, high transparency and high mechanical strength. Full article