Search Results (107)

Three-dimensional printing is commonly used to fabricate provisional dental restorations. Studies have reported that changes in printing orientation affect the physical and mechanical properties of 3D-printed polymeric provisional restorations; however the findings have been inconsistent. Therefore, this systematic review and meta-analysis aims to analyze the articles evaluating the influence of printing orientation on the physical and mechanical properties of 3D-printed polymeric provisional dental restorations. Recommendations provided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to structure and compose the review. The PICO (Participant, Intervention, Comparison, Outcome) question ordered was: ‘Do 3D-printed provisional dental restorations (P) printed at various orientations (except 0°) (I) exhibit similar physical and mechanical properties (O) when compared to those printed at a 0° orientation (C)?’. An electronic search was conducted on 28 and 29 April 2025, by two independent researchers across four databases (MEDLINE/PubMed, Scopus, Cochrane Library, and Web of Science) to systematically collect relevant articles published up to March 2025. After removing duplicate articles and applying predefined inclusion and exclusion criteria, twenty-one articles were incorporated into this review. Self-designed Performa’s were used to tabulate all relevant information. For the quality analysis, the modified CONSORT scale was utilized. The quantitative analysis was performed on only fifteen out of twenty-one articles. It can be concluded that the printing orientation affects some of the tested properties, which include fracture strength (significantly higher for specimens printed at 0° when compared to 90°), wear resistance (significantly higher for specimens printed at 90° when compared to 0°), microhardness (significantly higher for specimens printed at 90°and 45° when compared to 0°), color stability (high at 0°), and surface roughness (significantly higher for specimens printed at 45° and 90° when compared to 0°). There were varied outcomes in terms of flexural strength and elastic modulus. Full article

The innovation of multi-material offers significant benefits to architectural systems. The fusion of multiple materials, transitioning from one to another in a graded manner, enables the creation of fused space without the need for mechanical connections. Given that plastic is a major contributor to ecological imbalance, this research on fused space aims to recycle plastic and use it as a multi-material for building applications, due to its capacity for being 3D printed and fused with other materials. Furthermore, to generate diverse properties for the fused space, several nature-inspired forming algorithms are employed, including Swarm Behavior, Voronoi, Game of Life, and Shortest Path, to shape the building enclosure. Subsequently, digital analyses, such as daylight analysis, structural analysis, porosity analysis, and openness analysis, are conducted on the enclosure, forming the color mapping digital diagram, which determines the distribution of varying thickness, density, transparency, and flexibility gradation parameters, resulting in spatial diversity. During the fabrication process, Dual Force V1 and Dual Force V2 were developed to successfully print multi-material gradations with fused plastic following an upgrade to the cooling system. Finally, three test sites in London were chosen to implement the fused space concept using multi-material. Full article

The aim of this study was to compare the types, textile structures, labels, and fiber compositions of 64 red garments submitted as evidence in selected criminal cases between 2022 and 2024. The research enhanced the current knowledge of the characteristics of red clothing available to consumers and demonstrated the relevance of textile analysis in forensic science. Knitted fabrics were the most commonly used in the garments, followed by woven fabrics, nonwovens, and felts. Fiber identification focused on color and shade, generic classification, morphological structure, and chemical composition, revealing both similarities and distinctions among the samples. In a small percentage of cases, label information was found to be inaccurate. The study also examined the fiber content of threads, patches, logos, prints, and embroidery, underscoring the forensic potential of these often-overlooked elements. The identification of over 300 individual fibers enabled a critical evaluation of the analytical procedures and confirmed their effectiveness in forensic contexts. Full article

3D printing (3DP) enables the development of highly customizable skincare solutions, offering precise control over formulation, structure, and aesthetic properties. Therefore, this study explores the impact of patches’ microstructure on hydration efficacy using conventional and advanced chemical/morphological confocal techniques. Moreover, it advances to the personalization of under-eye 3D-printed skincare patches and assesses consumer acceptability through emotional sensing, providing a comparative analysis against a non-3D-printed market option. The results indicate that increasing the patches’ internal porosity enhances water retention in the stratum corneum (53.0 vs. 45.4% µm). Additionally, patches were personalized to address individual skin needs/conditions (design and bioactive composition) and consumer preferences (color and fragrance). The affective analysis indicated a high level of consumer acceptance for the 3D-printed option, as evidenced by the higher valence (14.5 vs. 1.1 action units) and arousal (4.2 vs. 2.7 peaks/minute) scores. These findings highlight the potential of 3DP for personalized skincare, demonstrating how structural modifications can modulate hydration. Furthermore, the biometric-preference digital approach employed offers unparalleled versatility, enabling rapid customization to meet the unique requirements of different skin types. By embracing this advancement, a new era of personalized skincare emerges, where cutting-edge science powers solutions for enhanced skin health and consumer satisfaction. Full article

Structural color is a kind of natural color that widely exists in nature. The ordered microstructure of nano materials can absorb or reflect light of specific wavelength, thus showing colorful colors. Structural color is an ideal choice for color contact lens pattern pigment due to its good tinting degree, stability, and nontoxicity. This paper explores a method for synthesis of zinc oxide (ZnO) nanoparticles with a high refractive index and enhancement of the brightness of the structured colors by introducing carbon black nanoparticles. This method is convenient and successful to prepare ZnO ink, which can produce bright structural colors, and to produce color patterns through rubber pad printing. It is worth mentioning that ZnO nanoparticles can be self-assembled and arranged in contact lens ink without subsequent complicated processing. At the same time, the color only comes from ZnO and carbon black. While there is no other organic matter, the presence of nanoparticles plays a certain role in sterilization. Blue contact lenses prepared by this method have bright structural color, high oxygen permeability, and high hydrophilicity. At the same time, a cell viability test showed that the contact lenses prepared by this method had low adsorption capacity for lipids and proteins, reflecting the photonic crystal’s high biocompatibility. In summary, a trend for future research is to use high-refractive-index zinc oxide nanoparticles to produce structural colors rather than employing conventional contact lens pigments. Full article

A self-tuning control strategy for Active Disturbance Rejection Control (ADRC) parameters based on a Radial Basis Function (RBF) neural network is proposed to improve the control accuracy of the roll-to-roll flexographic printing multi-color register system for its multi-input–multi-output and multi-span coupling characteristics. Firstly, according to the actual physical structure of flexographic printing equipment and the multi-physical coupling interface between adjacent spans, a mathematical model of the register system is established, and the multi-span coupling model is decoupled. Then, the ADRC decoupling controller is designed to estimate the disturbance and control the coupling model, and the RBF neural network is used to adjust the parameters of the decoupling controller in real time. Finally, the robustness, system decoupling, and anti-disturbance performance of the designed controller are verified under simulated steady speed and acceleration conditions. The simulation results show that the designed controller has better control performance than the conventional Proportional-Integral-Derivative (PID) and decoupled PID controllers. In steady state and accelerated simulations of PET/BOPP materials, respectively, the error peak is reduced by 86.7% and is controlled within ±10 μm, which satisfies the high-accuracy control requirements of the register system. Full article

Three-dimensional (3D) food printing (3DFP) is an emerging technology that enables the creation of personalized and functional foods by precisely controlling nutritional content and shape. This study investigated the 3D printability and rheological behavior of cereal–legume starch-based gels formulated with germinated brown rice (GBR) and red adzuki bean (RAB) flours, supplemented with xanthan and guar gums as functional additives. The physicochemical and structural properties of the gels were characterized through FT-IR, rheology, texture analysis, SEM, and sensory evaluation. In addition, the 3D printing fidelity, rheological behavior, color attributes, textural properties, microstructure, and sensory scoring of the printed products were evaluated. The results indicated that the gels exhibited pseudoplastic behavior, with the RABF/GBRF ratio of 1:2 (RG1:2) formulation showing optimal color properties (ΔE* = 0.60 ± 0.86) and the RABF/GBRF ratio of 2:1 (RG2:1) formulation demonstrating superior printing fidelity and structural stability (printing accuracy = 99.37 ± 0.39%). The gels’ mechanical properties, such as hardness and chewiness, were significantly influenced by the RABF and GBRF ratios, with RG2:1 exhibiting the highest hardness (1066.74 ± 102.09) and RG1:2 showing the best springiness (0.64 ± 0.10). The sensory evaluation results indicated that the RABF/GBRF ratios of 1:1 (RG1:1) and RG1:2 had relatively high overall acceptance scores. These findings indicate that specific ratios of RABF and GBRF improve the 3D printability and textural properties of cereal–legume starch-based gels, enhancing their suitability for 3D food printing applications. This study provides valuable insights into the development of personalized and functional cereal–legume starch-based foods using 3DFP technology. Full article

Structural adhesives or fixing glues are typically applied to larger components on printed circuit boards (PCBs) to increase mechanical stability and minimize damage from vibration. Existing work tends to focus on component placement verification and solder joint analysis, etc. However, the detection of structural adhesives remains largely unexplored. This paper proposes a vision-based method for detecting structural adhesive defects on PCBs. The method uses HSV color segmentation to extract PCB regions, followed by Hough-transform-based morphological analysis to identify board features. The perspective transformation then extracts and rectifies the adhesive regions, and constructs an adhesive region template by detecting the standard adhesive area ratio in its corresponding adhesive region. Finally, template matching is used to detect the structural adhesives. The experimental results show that this approach can accurately detect the adhesive state of PCBs and identify the qualified/unqualified locations, providing an effective vision-based detection scheme for PCB manufacturing. The main contributions of this paper are as follows: (1) A vision-based structural adhesive detection method is proposed, and its detailed algorithm is presented. (2) The developed system includes a user-friendly visualization interface, streamlining the inspection workflow. (3) Actual experiments are performed to evaluate this study, and the results validate its effectiveness. Full article

The adhesion of printing inks to printing substrates is a complex process influenced by both the physical and chemical properties of the printing substrate and of the printing ink. Synthetic paper, being a polymer with no absorption capability, limits the interaction between the ink and substrate, leading to lower adhesion values. On synthetic paper, the thicker polymer resin layer covering the microcapsules results in a more stable ink film and lighter print coloration. In contrast, UV-curable ink applied to bulky and recycled papers, which have porous structures, exhibits more dynamic interactions. The polymer resin in the ink penetrates the paper’s pores, forming a stronger bond with the paper fibers and improving adhesion quality. Surface roughness also plays a significant role in ink adhesion. Rough surfaces increase contact between ink and paper, enhancing mechanical adhesion by allowing the ink to “lock” into the surface’s irregularities. The surface energy (SFE) at the interphase between paper and ink is also a key factor. Low SFE promotes better wetting and ink absorption, improving adhesion. Ink penetration into the printing substrate is crucial for achieving high-quality adhesion. Full article

Printing and dyeing wastewater is known for its high color intensity, complex composition, and low biodegradability, making its treatment a significant challenge in environmental protection. Dolomite is a natural mineral with abundant reserves and can be effectively used as an adsorbent carrier. In this study, the dolomite loaded by Fe₂O₃ composites (DFC) was synthesized and systematically characterized using XRD, SEM, TEM, BET, XPS, and IR to evaluate its structural and surface properties. The adsorption performance of DFC on Congo Red (CR) was then investigated. The maximum adsorption amount of CR by DFC was 3790.06 mg⋅g⁻¹, and the removal rate was still stable at 97% after five cycles of adsorption test, which demonstrated that DFC exhibited exceptional adsorption efficacy and regeneration capability. The loaded Fe³⁺ was beneficial to improve the adsorption effect on the DFC. In addition, to evaluate the type of adsorption, kinetic calculations were performed, which indicated that the Weber–Morris diffusion modeling study showed the adsorption behavior was influenced by the interplay of many diffusion mechanisms. The study offers an innovative method for the efficient utilization of dolomite in creating renewable adsorbent materials for dye wastewater remediation. Full article

A series of compounds with both urea and urethane moieties have been developed as color developers for high-performance thermo-sensitive paper. The compounds have lower environmental loads than conventional phenolic developers. They were also found to greatly improve the speed of the printed images. In this study, we studied the coloring mechanism of the compounds when used as developers for a fluoran dye, and we investigated the stability of the colored solid state. The urea–urethane compounds were found to form black amorphous solids with the fluoran dye. Infrared (IR) measurements of the black solids, based on six urea–urethane derivatives, revealed that the colored dye has a ring-opened structure in a carboxylic acid form and that the urea group works as a proton donor for the ring-opening reaction. The stability of the black amorphous solids was also evaluated using thermal analysis and molecular orbital calculations in addition to IR data. The results indicate that the number of urea–urethane units and the planarity of the urea moiety are important parameters for the stability of the colored solid state. Full article

This study explores the use of advanced 3D imaging and printing technologies to digitally document and physically replicate cultural artifacts from the Archaeological Museum of Alexandroupolis. By employing structured light scanning and additive manufacturing techniques, detailed digital models and precise physical replicas of two significant artifacts were created—a humanoid ceramic vessel and a glass cup. A handheld 3D scanner was utilized for capturing intricate surface details, with post-processing methods to refine and colorize the digital models. Regarding 3D printing, both Fused Deposition Modeling (FDM) and Stereolithography (SLA) were employed, tailored to the artifacts’ unique requirements for resolution and material properties. This dual approach supports heritage preservation by generating tangible educational resources and providing alternative exhibits to safeguard original artifacts. Our results demonstrate that integrating 3D scanning and printing effectively enhances the accessibility, durability, and educational utility of cultural heritage assets, offering a sustainable model for artifact preservation and study. Full article

Colored 3D printing, as one of the crucial directions in 3D printing technology, has been widely applied in various fields in recent years. Compared to traditional 3D printing, colored 3D printing introduces color information to achieve multi-material identification of different regions in the model structure, enabling the fabrication of heterogeneous and complex components. This presents unique advantages in both visual effects and functionality, making it of significant value in fields such as metal manufacturing, bioengineering, and artistic design. However, during the construction of colored models, technical challenges such as low-slicing contour accuracy and poor color reproduction persist. Existing slicing methods for colored models are often accompanied by contour offset, deformation, color distortion, and low rendering efficiency, severely limiting the application scope of colored 3D printing technology. To address these challenges, this paper proposes a “Fast Slicing Method for Colored Models Based on Colored Triangular Prisms and OpenGL”. This method first constructs colored triangular prisms to effectively solve the problems of color contour offset and deformation, achieving uniform thickness offset of the colors. Then, by utilizing OpenGL rendering technology, the method overcomes color abruptness, simplifies bitmap rendering processes, and ensures smooth color transitions while significantly improving rendering efficiency. In summary, the proposed slicing method can effectively enhance the accuracy of slicing contours and color reproduction, significantly expanding the application range of colored 3D printing. Full article

Copper ions (Cu²⁺) are the third most essential transition metal ions critical to human health. Rapid detection of Cu²⁺ in water and biological fluids is of significant importance. In this study, we develop a sensitive multi-channel paper microfluidic device integrated with a 3D-printed smartphone-based colorimetric reader for the rapid detection of Cu²⁺. A novel rhodamine derivative, 1-(N,N-dichloromethine) amino-4-rhodamine B hydrazine-benzimide (RBCl), exhibiting high selectivity and sensitivity to Cu²⁺, was synthesized and applied as the detection reagent. The interaction mechanism between RBCl and Cu²⁺ was investigated, revealing a structural transition from a colorless spirolactam (closed-ring) to an open-ring amide structure, resulting in a pink color upon Cu²⁺ binding. A multi-channel paper microfluidic device with eight detection zones was fabricated, enabling the simultaneous analysis of eight samples. To enhance portability and quantification, a 3D-printed smartphone colorimetric reader was integrated, providing a rapid and efficient detection platform. The system achieved highly specific Cu²⁺ detection within 2 min, with a detection limit as low as 1.51 ng/mL, meeting water monitoring standards in most countries. Excellent recoveries were demonstrated in real samples, including tap water, river water, blood serum, and urine diluent. This integrated paper microfluidic system is highly sensitive and specific, offering a promising solution for water quality monitoring and health assessment through its rapid sample-to-answer capability. Full article

This review examines recent advancements in gel-based 3D and 4D food-printing technologies, with a focus on their applications in personalized nutrition and functional foods. It emphasizes the critical role of tunable rheological and mechanical properties in gels such as starch, protein, and Pickering emulsions, which are essential for successful printing. The review further explores 4D food printing, highlighting stimuli-responsive mechanisms, including color changes and deformation induced by external factors like temperature and pH. These innovations enhance both the sensory and functional properties of printed foods, advancing opportunities for personalization. Key findings from recent studies are presented, demonstrating the potential of various gels to address dietary challenges, such as dysphagia, and to enable precise nutritional customization. The review integrates cutting-edge research, identifies emerging trends and challenges, and underscores the pivotal role of gel-based materials in producing high-quality 3D-printed foods. Additionally, it highlights the potential of Pickering emulsions and lipid gels for expanding functionality and structural diversity. Overall, this work provides a comprehensive foundation for advancing future research and practical applications in gel-based 3D and 4D food printing. Full article