Search Results (64)

Titanium implants are widely used in orthopedic and dental fields but often face challenges such as insufficient osseointegration and peri-implant inflammation. While Strontium (Sr) possesses potent bioactive properties, achieving its controlled delivery at the implant-tissue interface remains technically challenging. To address this, we engineered a multidimensional composite coating by constructing a micro/nano-porous TiO₂ substrate via micro-arc oxidation (MAO), followed by polydopamine (PDA)-assisted Sr immobilization. This integrated architecture significantly enhanced surface hydrophilicity and facilitated high-content Sr loading with sustained release kinetics. Biological evaluations demonstrated that the PDA-mediated interface promoted superior initial adhesion and spreading of bone marrow mesenchymal stem cells (BMSCs), synergizing with released Sr²⁺ to markedly upregulate core osteogenic markers (Runx2, ALP). Crucially, the functionalized surface actively optimized the immune microenvironment by inducing M1-to-M2 macrophage polarization and comprehensively suppressing RANKL-induced osteoclastogenesis via the downregulation of TRAP and DC-STAMP. By integrating these pro-osteogenic, anti-inflammatory, and anti-resorptive capabilities, this tri-functional system effectively rebalances the bone remodeling microenvironment. Consequently, it provides a robust, universally applicable strategy for enhancing the therapeutic efficacy of next-generation orthopedic and dental implants. Full article

The placement technique of resin composites may significantly influence marginal integrity, wear resistance, and operative efficiency. This in vitro study evaluated the influence of different placement techniques for a bulk-fill resin composite on marginal integrity, wear behavior, and application time. Standardized Class I cavities were prepared in extracted human molars and restored using the same bulk-fill composite (Filtek One Bulk Fill, 3M, USA) applied with four techniques: incremental placement, incremental placement with a modeling liquid (GC Modeling Liquid, GC Corp., Tokyo, Japan), bulk placement, and the stamp technique. Application time was recorded in seconds. All specimens underwent combined mechanical and thermal aging (SD Mechatronik, Germany). Marginal integrity was assessed three-dimensionally using micro-computed tomography, while surface wear was quantified through computer-based digital analysis with OraCheck software (Dentsply Sirona, Germany). Bulk placement exhibited significantly higher microleakage scores than the other techniques while demonstrating the shortest application time. Incremental placement, incremental placement with modeling liquid, and the stamp technique showed comparable microleakage results (p > 0.05). Although the use of modeling liquid did not increase microleakage, it resulted in significantly greater wear. Placement technique significantly influences marginal integrity, wear behavior, and application time of bulk-fill composite restorations. Full article

Microcontact stamping is a promising microfabrication technique for producing functional patterned thin films on flexible substrates; however, systematic optimization of its process parameters for thermochromic applications remains limited. In this study, we present a comprehensive parametric optimization of the microcontact stamping process to fabricate thermochromic pigment-coated thin films with rapid and reversible color responses. The effects of liquid resin type, SU-8 mold thickness, polydimethylsiloxane (PDMS) mixing ratio, and pattern size on pattern fidelity and thermochromic performance were systematically investigated. The optimal conditions were identified as a UV-curable resin, a 600 µm-thick SU-8 mold, a PDMS base-to-curing-agent ratio of 5:1, and a pattern size of 125 × 125 µm². Under these conditions, the stamped thermochromic films exhibited uniform micro-patterns, rapid response and recovery behavior, and stable reversible color changes over 20 consecutive thermal cycles. This work provides practical guidelines for parameter-controlled microcontact stamping of functional thin films and demonstrates its potential for scalable fabrication of thermochromic micro-patterns. The proposed approach is expected to contribute to the development of flexible and wearable electronic devices, smart displays, and thermally responsive sensing platforms. Full article

Surface-imprinted polymer (SIP)-based biomimetic sensors are promising for direct whole-bacteria detection; however, the commonly used fabrication approach (micro-contact imprinting) often suffers from limited imprint density, heterogeneous template distribution, and poor reproducibility. Here, we introduce a photolithography-defined master stamp featuring E. coli mimics, enabling high-density, well-oriented cavity arrays (3 × 10⁷ imprints/cm²). Crucially, the cavity arrangement is engineered such that the SIP layer functions simultaneously as the bioreceptor and as a diffraction grating, enabling label-free optical quantification by reflectance changes without additional transduction layers. Finite-difference time-domain (FDTD) simulations are used to model and visualize the optical response upon bacterial binding. Proof-of-concept experiments using a differential two-well configuration confirm concentration-dependent detection of E. coli in PBS, demonstrating a sensitive, low-cost, and scalable sensing concept that can be readily extended to other bacterial targets by redesigning the photolithographic master. Full article

In this study, the asymmetrical rolling technique was employed to fabricate 75 μm-thick Ti-6Al-4V ultra-thin strips from the initial 0.45 mm sheet without intermediate annealing, aiming for applications in fuel cell bipolar plates. The rolled strips exhibited good surface quality without cracking. In order to enhance both the mechanical response and the shaping capability of Ti-6Al-4V strips produced by asymmetric rolling, the material was subjected to annealing at various temperatures, and the resulting changes in microstructural features and mechanical performance were systematically examined. The findings indicated that the cold-rolled Ti-6Al-4V exhibited a microstructure primarily composed of subgrains with an average size of approximately 0.41 μm, a feature that contributed to improved corrosion resistance and enhanced ductility after annealing. When the alloy was subjected to heat treatment within the range of 650–800 °C, it was observed that annealing temperatures below 700 °C favored microstructural changes governed predominantly by recovery processes and the onset of recrystallization. At 700 °C, the grains became equiaxed and uniformly distributed, and the dislocation density significantly decreased. The tensile strength reached 887 MPa, while the elongation increased to 13.7%, achieving an excellent strength-ductility balance. Once the annealing temperature rose above 700 °C, noticeable grain growth took place, accompanied by a more pronounced grain-size gradient and a renewed increase in dislocation density. Meanwhile, the dimples observed on the fracture surface became finer, collectively contributing to a decline in tensile elongation. The Ti-6Al-4V ultra-thin strip annealed at 700 °C was used for bipolar plate stamping, producing fine micro-channels with an aspect ratio of 0.43. Finally, TiN coating was applied to the surface, which significantly improved the corrosion resistance and reduced the interfacial contact resistance (ICR), meeting the performance requirements for bipolar plates. Full article

In the production of modern nongxiangxing daqu, mechanical stamping is utilized to compact raw materials into daqu bricks. Nevertheless, variations in stamping frequencies may modify the initial physicochemical properties of daqu, which in turn influence its physicochemical and biochemical parameters, and ultimately affect the quality of baijiu. This study systematically evaluated daqu samples prepared with different stamping frequencies (2 to 5 cycles) in terms of (1) physicochemical and biochemical parameters, (2) volatile compound profiles, (3) microbial community dynamics, and (4) interspecific interactions. The results showed that with the increase in stamping frequency, the moisture content, fermentative power, esterifying power, and liquefying power of daqu were all enhanced, with respective increases of 20.11%, 67.16%, 12.24-fold, and 36.27%. Specifically, the relative abundances of Weissella, Lactobacillus, Aspergillus, and Rasamsonia in daqu exhibited a significant increase with the elevation of pressing cycles. With the reduction in stamping frequency, the primary producers of flavor compounds shifted gradually from bacteria to fungi. These findings verify that stamping frequency exert a substantial regulatory impact on the physicochemical and biochemical parameters, microbial community dynamics, accumulation of flavor substances, and abundance of functional enzymes in daqu. Through a systematic elucidation of the mechanistic links between stamping parameters and daqu functionalities, this research offers actionable insights for optimizing industrial pressing processes and establishes a scientific basis for modern daqu production. Full article

Excessive osteoclast activity in bone remodeling can lead to an imbalance between bone resorption and formation, a common occurrence in abnormal bone metabolic diseases. This research investigates the effect of Coptidis rhizoma water extract (CRW) on osteoclastogenesis provoked by RANKL in vitro and bone destruction mediated by ovariectomy (OVX) in vivo. CRW, prepared from dried Coptidis rhizoma (CR), was analyzed for its active compounds—coptisine and berberine—using HPLC analysis. CRW markedly decreased the size and number of TRAP-positive multinucleated cells (TRAP⁺ MNCs), suppressed F-actin ring formation, and diminished bone resorption in RANKL-treated cultures. In the early phase of differentiation, CRW suppressed the phosphorylation of MAPKs p38, JNK, and ERK, as well as NF-κB p65, Iκ-Bα, and Akt. CRW also down-regulated RANKL-mediated induction of c-Fos and NFATc1 and attenuated the activation of NFATc1- dependent genes, such as OSCAR, ATP6V0D2, ACP5 (TRAP), OC-STAMP, DC-STAMP, CTSK (cathepsin K), CALCR (calcitonin receptor), and MMP-9. In ovariectomized rats, micro-CT and histological analyses showed that CRW alleviated femoral bone destruction. These findings indicate that CRW restrains osteoclast differentiation and function and may have therapeutic potential for disorders driven by excessive osteoclast activity. Full article

The stamp technique with bulk-fill composites aims to enhance occlusal surface replication in Class I restorations. Limited research exists on its void formation and volumetric changes. This study measures internal and external voids as well as volumetric changes in occlusal surfaces for both the stamp and conventional bulk-fill techniques. Materials and methods: Twenty-four permanent molars were divided into two groups (n = 12 each): Group 1 (conventional bulk fill) and Group 2 (stamp technique with bulk-fill composite). Standardized Class I cavities were prepared and restored using Tetric EvoCeram^® Bulk Fill composite. Micro-CT scanning was performed before and after restoration to quantify internal and external void percentages and volumetric changes. An independent samples t-test (α = 0.05) was used to compare void percentages and volumetric changes between groups. Results: The mean internal void percentage was similar between groups (Group 1: 0.38 ± 0.22%; Group 2: 0.39 ± 0.30%; p = 0.914), indicating comparable internal adaptation. Group 2 showed a significantly higher external void percentage (17.59 ± 1.76%) compared to Group 1 (9.05 ± 1.98%; p < 0.001), attributed to the stamp technique’s precise replication of occlusal micromorphology, misinterpreted as porosity by analysis software. Fractal dimension analysis revealed that the stamp technique resulted in the formation of a more complex structure. Restoration volumes (Group 1: 34.10 ± 8.09 mm³; Group 2: 35.52 ± 4.80 mm³; p = 0.639) and volumetric changes (Group 1: 5.91 ± 2.72 mm³; Group 2: 4.64 ± 1.31 mm³; p = 0.199) showed no significant differences. in conclusion, the stamp technique produced internal void percentages comparable to the conventional bulk-fill method in Class I restorations. The significantly higher external void percentage in the stamp technique group was due to the accurate replication of occlusal micromorphology, which was detected as porosity by analysis software. No significant differences were observed in volumetric changes of the occlusal surface before and after restoration between the two techniques, supporting the clinical viability of the stamp technique for precise occlusal restorations. Full article

Bistable microstructures are promising for implementation in many mictroelectromechanical system (MEMS)-based applications due to their ability to stay in several equilibrium states, high tunability and unprecedented sensitivity to external stimuli. As opposed to the extensively investigated one-dimensional curved beam-type devices of this kind, microfabrication of non-planar two-dimensional bistable structures, such as plates or shells, represents a remarkable challenge. Recently reported by us, a new moldless stamping procedure, based on pressing a soft stamp over a thin suspended metallic film, was demonstrated to be a feasible direction for the fabrication of initially curved micro plates. However, reliable implementation of this fabrication paradigm and its further development requires better understanding of the role of the process parameters, and of the effect of both the plate and the stamp material properties on the shape of the formed shell and on the postfabrication residual stresses, and therefore on the shell behavior. The need for an appropriate choice of these parameters requires the development of a systematic modeling approach to the stamping process. Here, we report on a finite element (FE)-based methodology for modeling the processing sequences of a successfully fabricated aluminum (Al) micro shell of realistic geometry. The model accounts for the elasto-plastic behavior of the plate material, the nonlinear material behavior of the foam and the contact between them. It was found that the stamping pressure and the plate material parameters are the key parameters affecting the residual shell curvature as well as its shape. Consistently with previously presented experimental results, we show that the fabrication procedure partially relieves the prestresses emerging during preceding fabrication steps, leaving a nontrivial distribution of residual stresses in the formed shell. The presented analysis approach and results provide tools for designers and manufacturers of systems including micro structural elements of shell type. Full article

This investigation aimed at evaluating the weldability of a 2.1 GPa-grade hot stamping steel (HSS) containing 0.40 wt.% carbon using laser butt welding. It is shown that the subject HSS can be properly joined by laser welding without welding defects, such as voids and micro-cracks. The mechanical properties of joints before and after hot stamping were examined using cross-weld uniaxial tension and Vickers hardness, while microstructure was systematically characterized using optical microscopy and electron backscatter diffraction. The experimental results demonstrate that fresh martensite was formed in the weld nugget after welding, leading to a hardness much higher than that of the base metal. Nevertheless, such cross-weld microstructural heterogeneity was erased after hot stamping and low-temperature baking heat treatments, resulting in a uniform microstructure of lath martensite across the weld. As a result, the joint after hot stamping and baking exhibited an ultimate tensile strength of 2140 MPa and a total elongation of 12.03%, with the fracture occurring in the base metal. Such excellent mechanical properties of the joint demonstrate the great weldability of the present 2.1 GPa-grade HSS during laser welding. Full article

The metal bipolar plate is a critical component of the hydrogen fuel cell stack used in proton exchange membrane fuel cells. Bipolar plates must have high accuracy micro-channels with a high aspect ratio (AR) between the channel depth and the half periodic width to achieve optimal cell performance. Conventional forming methods, such as micro-stamping, hydroforming, and rubber pad forming, cannot achieve these high ARs given that in these processes, material deformation is dominated by stretch deformation. In micro-roll forming the major deformation mode is bending, and this enables production of channels with higher ARs than is currently possible. However, micro-roll forming uses multiple sets of forming roll stands to form the part and this leads to technological challenges related to tool alignment and roll tool precision that must be overcome before widespread application can be achieved. This study presents a new methodology to achieve tight tool tolerances when producing micro-roll tooling by utilizing wire-EDM and micro-turning techniques. This is combined with a new micro-roll former design that enables high-precision tool alignment across multiple roll stations. Proof of concept is provided through micro-roll forming trials performed on ultra-thin titanium sheets that show that the proposed technology can achieve tight dimensional tolerances in the sub-millimeter scale that suits bipolar plate applications. Full article

The development of hydrophobicity on polymer surfaces in mass production is one of the most critical challenges in the plastic industry. This paper deals with a novel combined hot embossing process in which femtosecond laser ablation is utilized to texture the embossing stamps. By controlling the process temperature and axial forces, the laser textures were transferred to polymer surfaces, successfully resulting in hydrophobicity. Four different polymers, including ABS, PP, PA, and PC, along with two different laser textures, namely ball and pyramid, were tested. The laser and hot embossing parameters under which the textures were transferred to the polymers are introduced. The critical micro- and nano-features of the transferred textures that resulted in high hydrophobic contact angles are also discussed. The results indicate that PP and ABS have higher contact angles, respectively, while under the given parameters, PA and PC did not exhibit hydrophobic surfaces. Full article

Nanostructures with sufficiently large areas are necessary for the development of practical devices. Current efforts to fabricate large-area nanostructures using step-and-repeat nanoimprint lithography, however, result in either wide seams or low efficiency due to ultraviolet light leakage and the overflow of imprint resin. In this study, we propose an efficient method for large-area nanostructure fabrication using step-and-repeat nanoimprint lithography with a composite mold. The composite mold consists of a quartz support layer, a soft polydimethylsiloxane buffer layer, and multiple intermediate polymer stamps arranged in a cross pattern. The distance between the adjacent stamp pattern areas is equal to the width of the pattern area. This design combines the high imprinting precision of hard molds with the uniform large-area imprinting offered by soft molds. In this experiment, we utilized a composite mold consisting of three sub-molds combined with a cross-nanoimprint strategy to create large-area nanostructures measuring 5 mm × 30 mm on a silicon substrate, with the minimum linewidth of the structure being 100 nm. Compared with traditional step-and-flash nanoimprint lithography, the present method enhances manufacturing efficiency and generates large-area patterns with seam errors only at the micron level. This research could help advance micro–nano optics, flexible electronics, optical communication, and biomedicine studies. Full article

Scanning micrο X-ray fluorescence (μ-XRF) and multispectral imaging (MSI) were applied to study philately stamps, selected for their small size and intricate structures. The μ-XRF measurements were accomplished using the M6 Jetstream Bruker scanner under optimized conditions for spatial resolution, while the MSI measurements were performed employing the XpeCAM-X02 camera. The datasets were acquired asynchronously. Elemental distribution maps can be extracted from the μ-XRF dataset, while chemical distribution maps can be obtained from the analysis of the multispectral dataset. The objective of the present work is the fusion of the datasets from the two spectral imaging modalities. An algorithmic co-registration of the two datasets is applied as a first step, aiming to align the multispectral and μ-XRF images and to adapt to the pixel sizes, as small as a few tens of micrometers. The dataset fusion is accomplished by applying k-means clustering of the multispectral dataset, attributing a representative spectrum to each pixel, and defining the multispectral clusters. Subsequently, the μ-XRF dataset within a specific multispectral cluster is analyzed by evaluating the mean XRF spectrum and performing k-means sub-clustering of the μ-XRF dataset, allowing the differentiation of areas with variable elemental composition within the multispectral cluster. The data fusion approach proves its validity and strength in the context of philately stamps. We demonstrate that the fusion of two spectral imaging modalities enhances their analytical capabilities significantly. The spectral analysis of pixels within clusters can provide more information than analyzing the same pixels as part of the entire dataset. Full article

High-resolution nanotransfer printing (nTP) technologies have attracted a tremendous amount of attention due to their excellent patternability, high productivity, and cost-effectiveness. However, there is still a need to develop low-cost mold manufacturing methods, because most nTP techniques generally require the use of patterned molds fabricated by high-cost lithography technology. Here, we introduce a novel nTP strategy that uses imprinted metal molds to serve as an alternative to a Si stamp in the transfer printing process. We present a method by which to fabricate rigid surface-patterned metallic molds (Zn, Al, and Ni) based on the process of direct extreme-pressure imprint lithography (EPIL). We also demonstrate the nanoscale pattern formation of functional materials, in this case Au, TiO₂, and GST, onto diverse surfaces of SiO₂/Si, polished metal, and slippery glass by the versatile nTP method using the imprinted metallic molds with nanopatterns. Furthermore, we show the patterning results of nanoporous crossbar arrays on colorless polyimide (CPI) by a repeated nTP process. We expect that this combined nanopatterning method of EPIL and nTP processes will be extendable to the fabrication of various nanodevices with complex circuits based on micro/nanostructures. Full article