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Journal of Chemical Education Oct 2022Electrochromism encompasses reversible changes of material's optical properties (color, opacity) under the influence of an external electric current or applied voltage....
Electrochromism encompasses reversible changes of material's optical properties (color, opacity) under the influence of an external electric current or applied voltage. The effect has been known for decades, but its importance continues to grow due to the rapid development of smart systems and the accompanying demand to build devices that consume less power. Most commercial electrochromic devices (ECDs) require sophisticated chemicals and advanced material preparation techniques. Also, the demonstration of electrochromism in chemistry classes mainly uses expensive WO films, intrinsically conductive polymers, and/or optically transparent electrodes (OTEs). The aim of this article is to present a simple and fast educational method to build ECDs from household materials without the need for OTEs: unsharpened kitchen knives are used as electrodes, curcumin from turmeric is used as the electrochromic dye, and baking soda is used as the electrolyte. The laboratory experiments presented will help students gain a deeper understanding of the fundamentals of electrochemistry (electrolysis, pH change) and electrochromism (in our case, color changes due to pH-induced keto-enol tautomerism of curcumin).
PubMed: 36246424
DOI: 10.1021/acs.jchemed.2c00176 -
Preparation and Performance of Water-Active Polyurethane Grouting Material in Engineering: A Review.Polymers Nov 2022Polyurethane foam materials have broad application prospects in practical engineering as flame retardants, waterproof coatings, and grout repair materials due to... (Review)
Review
Polyurethane foam materials have broad application prospects in practical engineering as flame retardants, waterproof coatings, and grout repair materials due to advantages such as light weight, quick forming, and good durability. Due to water's low cost and convenience, water-reactive Polyurethane foam materials are widely used in engineering. The content of the water has a significant effect on the performance of polyurethane foams after molding. Polyurethane foams with anti-seepage and reinforcement effects are used in complex water environments for long durations. This study analyzed the effects of water content on properties and the diffusion mechanism of polyurethane foam materials in water. Additionally, the effect of the water environment on the polyurethane grouting material's properties was summarized. Finally, this study discussed the future research directions of polyurethane foam materials in a water environment.
PubMed: 36501494
DOI: 10.3390/polym14235099 -
Micromachines Jun 2022The machining of micro/nano periodic surface structures using a femtosecond laser has been an academic frontier and hotspot in recent years. With an ultrahigh laser... (Review)
Review
The machining of micro/nano periodic surface structures using a femtosecond laser has been an academic frontier and hotspot in recent years. With an ultrahigh laser fluence and an ultrashort pulse duration, femtosecond laser machining shows unique advantages in material processing. It can process almost any material and can greatly improve the processing accuracy with a minimum machining size and heat-affected zone. Meanwhile, it can fabricate a variety of micro/nano periodic surface structures and then change a material's surface performance dramatically, such as the material's wetting performance, corrosive properties, friction properties, and optical properties, demonstrating great application potential in defense, medical, high-end manufacturing, and many other fields. In recent years, the research is gradually deepening from the basic theory to optimization design, intelligent control, and application technology. Nowadays, while focusing on metal structure materials, especially on stainless steel, research institutions in the field of micro and nano manufacturing have conducted systematic and in-depth experimental research using different experimental environments and laser-processing parameters. They have prepared various surface structures with different morphologies and periods with sound performance, and are one step closer to many civilian engineering applications. This paper reviews the study of micro/nano periodic surface structures and the performance of stainless steel machined using a femtosecond laser, obtains the general evolution law of surface structure and performance with the femtosecond laser parameters, points out several key technical challenges for future study, and provides a useful reference for the engineering research and application of femtosecond laser micro/nano processing technology.
PubMed: 35744590
DOI: 10.3390/mi13060976 -
Global Challenges (Hoboken, NJ) Feb 2023Photovoltaic silicon converts sunlight in 95% of the operational commercial solar cells and has the potential to become a leading material in harvesting energy from... (Review)
Review
Photovoltaic silicon converts sunlight in 95% of the operational commercial solar cells and has the potential to become a leading material in harvesting energy from renewable sources, but silicon can hardly convert clean energy due to technologies required for its reduction from sand and further purification. The implementation of the novel materials into photovoltaic systems depends on their conversion efficiency limited by the material's inherent properties, longevity dependent on internal stability, and ease of manufacturing process. A major challenge is discovering a multilayered set of different photovoltaic materials capable of converting clean energy from a wider spectra range since emerging materials and technologies such as dye-sensitized and quantum dots suffer from low conversion efficiencies while perovskite and organic cells have short longevity in atmospheric conditions. Presently, improving technologies for commercialized materials and creating multijunction solar cells enhanced by new photovoltaic materials is a path toward cleaner energies. With the rapid development of the integrative technologies and challenges that photovoltaics for clean energy conversion are facing, the entire clean photovoltaic industry could arise by bottom-up course as a part of integrative technologies rather than erecting large power plants.
PubMed: 36778780
DOI: 10.1002/gch2.202200146 -
Journal of the Mechanical Behavior of... Sep 2022Numerical simulations are a valuable tool in the field of tissue engineering for cartilage repair and can help to understand which mechanical properties affect the...
Numerical simulations are a valuable tool in the field of tissue engineering for cartilage repair and can help to understand which mechanical properties affect the behavior of chondrocytes and contribute to the success or failure of surrogate materials as implants. However, special attention needs to be paid when identifying corresponding material parameters in order to provide reliable numerical predictions of the material's response. In this study, we identify hyperelastic material parameters for numerical simulations in COMSOL Multiphysics® v. 5.6 for human articular cartilage and two surrogate materials, commercially available ChondroFiller, and oxidized alginate-gelatin (ADA-GEL) hydrogels. We consider several hyperelastic isotropic material models and provide separate parameter sets for the unconditioned and the conditioned material response, respectively, based on previously generated experimental data including both compression and tension experiments. We compare a direct parameter identification approach assuming homogeneous deformation throughout the specimen and an inverse approach, where the experiments are simulated using a finite element model with realistic boundary conditions in COMSOL Multiphysics® v. 5.6. We demonstrate that it is important to consider both compression and tension data simultaneously and to use the inverse approach to obtain reliable parameters. The one-term Ogden model best represents the unconditioned response of cartilage, while the conditioned response of cartilage and ADA-GEL is equally well represented by the two-term Ogden and five-term Mooney-Rivlin models. The five-term Mooney-Rivlin model is also most suitable to model the unconditioned response of ADA-GEL. For ChondroFiller, we suggest using the five-term Mooney-Rivlin or two-term Ogden model for the unconditioned and the two-term Ogden model for the conditioned material response. These results will help to choose appropriate material models and parameters for simulations of whole joints or to advance mechanical-stimulation assisted cartilage tissue engineering in the future.
Topics: Cartilage, Articular; Chondrocytes; Elasticity; Finite Element Analysis; Gelatin; Humans; Hydrogels; Stress, Mechanical; Tissue Engineering
PubMed: 35689988
DOI: 10.1016/j.jmbbm.2022.105292 -
BioRxiv : the Preprint Server For... May 2024We can visually discriminate and recognize a wide range of materials. Meanwhile, we use language to express our subjective understanding of visual input and communicate...
We can visually discriminate and recognize a wide range of materials. Meanwhile, we use language to express our subjective understanding of visual input and communicate relevant information about the materials. Here, we investigate the relationship between visual judgment and language expression in material perception to understand how visual features relate to semantic representations. We use deep generative networks to construct an expandable image space to systematically create materials of well-defined and ambiguous categories. From such a space, we sampled diverse stimuli and compared the representations of materials from two behavioral tasks: visual material similarity judgments and free-form verbal descriptions. Our findings reveal a moderate but significant correlation between vision and language on a categorical level. However, analyzing the representations with an unsupervised alignment method, we discover structural differences that arise at the image-to-image level, especially among materials morphed between known categories. Moreover, visual judgments exhibit more individual differences compared to verbal descriptions. Our results show that while verbal descriptions capture material qualities on the coarse level, they may not fully convey the visual features that characterize the material's optical properties. Analyzing the image representation of materials obtained from various pre-trained data-rich deep neural networks, we find that human visual judgments' similarity structures align more closely with those of the text-guided visual-semantic model than purely vision-based models. Our findings suggest that while semantic representations facilitate material categorization, non-semantic visual features also play a significant role in discriminating materials at a finer level. This work illustrates the need to consider the vision-language relationship in building a comprehensive model for material perception. Moreover, we propose a novel framework for quantitatively evaluating the alignment and misalignment between representations from different modalities, leveraging information from human behaviors and computational models.
PubMed: 38328102
DOI: 10.1101/2024.01.25.577219 -
PloS One 2023Gas drainage materials are one critical aspect of preventing coal mine gas explosions. Here, a novel dual-liquid gas sealing material was developed to improve gas...
Gas drainage materials are one critical aspect of preventing coal mine gas explosions. Here, a novel dual-liquid gas sealing material was developed to improve gas extraction. The mechanical properties and hydration mechanism of the proposed material were determined. The novel dual-liquid gas sealing material's performance was verified experimentally and with field testing, with practical application explored in the YunGaiShan 2 coal mine. The results showed that the main factor responsible for gas drainage leakage was the poor sealing effect of the sealing materials on the cracks around the borehole. The novel dual-liquid gas sealing material reduced damage to the rock surrounding the borehole and significantly improved the gas drainage performance. The initial and final setting times of the novel dual-liquid material were shown to be controllable, and the slurry exhibited good fluidity, with a 28-day uniaxial compressive strength of 11.06 MPa. The analysis of the microscopic hydration mechanism showed that the production of ettringite (AFt) in the dual-liquid material increased significantly, forming a denser network interlace that functioned as a network skeleton, improving the compressive strength of the material and achieving the characteristics of plastic deformation. Field-based analysis was performed to verify the practical applicability of the proposed material, showing that the gas drainage concentration increased by 200.5% compared to the original sealing material. Moreover, the average gas drainage negative pressure increased from 7.8 kPa (using the conventional sealing technique) to 16.6 kPa using the proposed material. Overall, the proposed materials are suitable for sealing materials for effective gas drainage performance and can help control gas disasters.
Topics: Mining; Coal
PubMed: 37043500
DOI: 10.1371/journal.pone.0284140 -
IScience Apr 2023A transition from a linear to a circular economy is the only alternative to reduce current pressures in natural resources. Our society must redefine our material... (Review)
Review
A transition from a linear to a circular economy is the only alternative to reduce current pressures in natural resources. Our society must redefine our material sources, rethink our supply chains, improve our waste management, and redesign materials and products. Valorizing extensively available biomass wastes, as new carbon mines, and developing biobased materials that mimic nature's efficiency and wasteless procedures are the most promising avenues to achieve technical solutions for the global challenges ahead. Advances in materials processing, and characterization, as well as the rise of artificial intelligence, and machine learning, are supporting this transition to a new materials' mining. Location, cultural, and social aspects are also factors to consider. This perspective discusses new alternatives for carbon mining in biomass wastes, the valorization of biomass using available processing techniques, and the implementation of computational modeling, artificial intelligence, and machine learning to accelerate material's development and process engineering.
PubMed: 37123246
DOI: 10.1016/j.isci.2023.106549 -
Additively manufactured unimorph dielectric elastomer actuators: Design, materials, and fabrication.Frontiers in Robotics and AI 2022Dielectric elastomer actuator (DEA) is a smart material that holds promise for soft robotics due to the material's intrinsic softness, high energy density, fast...
Dielectric elastomer actuator (DEA) is a smart material that holds promise for soft robotics due to the material's intrinsic softness, high energy density, fast response, and reversible electromechanical characteristics. Like for most soft robotics materials, additive manufacturing (AM) can significantly benefit DEAs and is mainly applied to the unimorph DEA (UDEA) configuration. While major aspects of UDEA modeling are known, 3D printed UDEAs are subject to specific material and geometrical limitations due to the AM process and require a more thorough analysis of their design and performance. Furthermore, a figure of merit (FOM) is an analytical tool that is frequently used for planar DEA design optimization and material selection but is not yet derived for UDEA. Thus, the objective of the paper is modeling of 3D printed UDEAs, analyzing the effects of their design features on the actuation performance, and deriving FOMs for UDEAs. As a result, the derived analytical model demonstrates dependence of actuation performance on various design parameters typical for 3D printed DEAs, provides a new optimum thickness to Young's modulus ratio of UDEA layers when designing a 3D printed DEA with fixed dielectric elastomer layer thickness, and serves as a base for UDEAs' FOMs. The FOMs have various degrees of complexity depending on considered UDEA design features. The model was numerically verified and experimentally validated through the actuation of a 3D printed UDEA. The fabricated and tested UDEA design was optimized geometrically by controlling the thickness of each layer and from the material perspective by mixing commercially available silicones in non-standard ratios for the passive and dielectric layers. Finally, the prepared non-standard mix ratios of the silicones were characterized for their viscosity dynamics during curing at various conditions to investigate the silicones' manufacturability through AM.
PubMed: 36591410
DOI: 10.3389/frobt.2022.1034914 -
Cureus Aug 2023Addition silicones have revolutionized the field of fixed prosthodontics because of their dimensional stability, sufficient tear strength and excellent detail... (Review)
Review
Addition silicones have revolutionized the field of fixed prosthodontics because of their dimensional stability, sufficient tear strength and excellent detail reproduction. This review study aims to provide a detailed description of the essential variables to be taken into account during the process of making addition silicone impressions in fixed prosthodontics. These variables include the selection of appropriate tray type, size, and fabrication; the use of tray adhesive; gingival displacement techniques; manipulation of the impression material; the choice of the impression material's viscosity; impression techniques; and the proper insertion, removal, disinfection, and pouring of the cast. Additionally, this review aims to help doctors produce high-quality impressions by empowering them to critically assess the impressions to spot mistakes and motivating them to redo impressions that have serious problems before submitting them to the laboratory.
PubMed: 37746395
DOI: 10.7759/cureus.44014