- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Selective Transfer of Rotationally Commensurate MoS <sub/>2</sub> from an Epitaxially Grown van der Waals Heterostructure
摘要： Large-scale synthesis of high quality two-dimensional (2D) semiconductors are critical for their incorporation in emerging electronic and optoelectronic technologies. In particular, chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDs) via van der Waals epitaxy on epitaxial graphene (EG) leads to rotationally commensurate TMDs in contrast to randomly aligned TMDs grown on amorphous oxide substrates. However, the interlayer coupling between TMDs and EG hinders the investigation and utilization of the intrinsic electronic properties of the resulting TMDs, thus requiring their isolation from the EG growth substrate. To address this issue, we report here a technique for selectively transferring monolayer molybdenum disulfide (MoS2) from CVD-grown MoS2-EG van der Waals heterojunctions using copper (Cu) adhesion layers. The choice of Cu as the adhesion layer is motivated by density functional theory calculations that predict the preferential binding of monolayer MoS2 to Cu in contrast to graphene. Atomic force microscopy and optical spectroscopy confirm the large-scale transfer of rotationally commensurate MoS2 onto SiO2/Si substrates without cracks, wrinkles, or residues. Furthermore, the transferred MoS2 shows high performance in field-effect transistors with mobilities up to 30 cm2/Vs and on/off ratios up to 106 at room temperature. This transfer technique can likely be generalized to other TMDs and related 2D materials grown on EG, thus offering a broad range of benefits in nanoelectronic, optoelectronic, and photonic applications.
关键词： molybdenum disulfide,van der Waals epitaxy,two-dimensional semiconductors,field-effect transistors,copper adhesion layers,transition metal dichalcogenides,chemical vapor deposition
更新于2025-09-23 15:21:21
-
CFRP laser texturing to increase the adhesive bonding: morphological analysis of treated surfaces
摘要： Surface roughness of the adherends represents an important factor for manufacturing a reliable bonded joint in structural applications. In case of bonding of parts in carbon fibre reinforced polymer (CFRP), an increase of roughness parameters can be obtained with various techniques. In this paper, the morphology obtained from a CO2 laser texturing on CFRP laminates were investigated. CFRP laminates were manufactured and subjected to laser texturing with various densities. In particular, the densities of treatment have been defined as a function of the grid dimensions of the texture. Subsequently, non-contact measurements were carried out to evaluate the evolution of the surface roughness parameters as a function of the density of the laser treatment. Results showed a strong correlation between surface roughness and density of treatment. In conclusion, these results were compared with experimental tests, which showed that the mechanical performance for ENF bonded joints was limited only by the flexural mechanical resistance of the CFRP adherends. As a result of this work, the developed laser texturing approach is potentially able to increase the mechanical resistance in the function of the real local load acting on the complex bonded joint, optimizing time and cost process.
关键词： surface modification,surface roughness/morphology,Composites,adhesion by mechanical interlocking
更新于2025-09-23 15:21:01
-
Ultrafast Laser Processing of Nanostructured Patterns for the Control of Cell Adhesion and Migration on Titanium Alloy
摘要： Femtosecond laser texturing is a promising surface functionalization technology to improve the integration and durability of dental and orthopedic implants. Four different surface topographies were obtained on titanium-6aluminum-4vanadium plates by varying laser processing parameters and strategies: surfaces presenting nanostructures such as laser-induced periodic surface structures (LIPSS) and ‘spikes’, associated or not with more complex multiscale geometries combining micro-pits, nanostructures and stretches of polished areas. After sterilization by heat treatment, LIPSS and spikes were characterized to be highly hydrophobic, whereas the original polished surfaces remained hydrophilic. Human mesenchymal stem cells (hMSCs) grown on simple nanostructured surfaces were found to spread less with an increased motility (velocity, acceleration, tortuosity), while on the complex surfaces, hMSCs decreased their migration when approaching the micro-pits and preferentially positioned their nucleus inside them. Moreover, focal adhesions of hMSCs were notably located on polished zones rather than on neighboring nanostructured areas where the protein adsorption was lower. All these observations indicated that hMSCs were spatially controlled and mechanically strained by the laser-induced topographies. The nanoscale structures influence surface wettability and protein adsorption and thus influence focal adhesions formation and finally induce shape-based mechanical constraints on cells, known to promote osteogenic differentiation.
关键词： cell adhesion,multiscale-patterning,wettability,human mesenchymal stem cell,femtosecond laser,cell spreading,cell motility,protein adsorption
更新于2025-09-23 15:21:01
-
The interaction between the osteosarcoma cell and stainless steel surface, modified by high-fluence, nanosecond laser pulses
摘要： The irradiation of metallic surfaces by high-fluence laser pulses in an oxygen-containing atmosphere inevitably modifies the surface topography, chemistry, and wettability. These modifications significantly influence cell-surface interactions and, consequently, surface biocompatibility. We investigate how surface texturing by high-fluence nanosecond laser pulses from a Nd:YAG laser (wavelength of 1064 nm) influences cell adhesion and morphology with the aim of assessing its impact on initial cell behaviour. Quantitative and qualitative analysis of osteosarcoma cell adhesion, viability, and cell morphology were evaluated after 24-hour exposure to non-treated and laser-textured stainless-steel (AISI 316L) surfaces by fluorescent and scanning electron microscopy. The results reveal that this, initial interaction between the cells and the laser-textured surfaces leads to round shaped cells with a smaller footprint. Contrarily, on the non-processed stainless-steel and control-glass surfaces the polygonal, highly elongated, and flattened cells are observed. The cells on the laser-textured surfaces are less dendritic, with short tubular protrusions and an overexpression of extracellular vesicles, which are rarely found on non-treated and control samples. This likely happens due to the formation of nanostructured, high-temperature oxides that are induced by laser ablation. The analysis by X-ray photoelectron spectroscopy reveals that the laser-textured stainless-steel surfaces contain Cr hexavalent oxide, which is more toxic than the native oxide layer on the non-processed samples.
关键词： MG63 cells,cell adhesion,Laser surface engineering,laser texturing,nanosecond-laser ablation
更新于2025-09-23 15:21:01
-
Laser machined ultralow water adhesion surface by low pressure processing
摘要： Ultralow water adhesion aluminum surface has been fabricated by eco friendly low pressure processing technique. The laser patterned surface shows interconnected spongy porous nanostructures with micro packets at regular intervals. The micro volume of air present inside the interconnected porous surface structure together with the adsorbed hydrocarbons by low pressure processing leads to ultralow water adhesion surface. Application of bigger droplet volumes to the patterned surface showed a decrease in static contact angle measurement due to larger radius of curvature and axisymmetrical compared to the smaller droplets.
关键词： Sliding angle,Ultrafast laser,Low pressure,Wetting,Adhesion
更新于2025-09-23 15:21:01
-
Research on epoxy resin curing monitoring using laser ultrasonic
摘要： Adhesive bonding is widely used in the structural assembly of aircraft, and assessing the curing state of the adhesive is important to ensure the safe operation of the assembly. In this paper, the curing process of epoxy resin is monitored by laser ultrasonics. The propagation of ultrasonic waves in a composite structure is discussed, and the curing of epoxy resin and its influence on ultrasonic characteristics are studied. In the fast-drying epoxy resin, the molecular cross-linking rate is fast, the difference of acoustic impedance between the epoxy resin and aluminum gradually decreases, so the transmission coefficient becomes larger and the reflection coefficient decreases. The calculation of absorption attenuation and dispersion should take this change into account. The relationship between amplitude and reflection coefficient is established by far-field ultrasound. The difference in molecular mobility causes the relaxation process, which results in absorption and dispersion of the ultrasonic waves. Making use of the broadband characteristic of laser ultrasonics, the transmission waves are analyzed. As the epoxy resin changes from liquid to solid, the relaxation time is gradually shortened, and the center frequency of the transmitted wave is gradually increased, the absorption attenuation is approximately linear with frequency. The results show that the curing process has a significant effect on ultrasonic characteristics, and laser ultrasonics could be used as an online monitoring method.
关键词： Adhesion,Interface,Non-destructive testing,Process monitoring
更新于2025-09-23 15:21:01
-
Ultrahigh Conductivity and Superior Interfacial Adhesion of a Nanostructured, Photonic Sintered Copper Membrane for Printed Flexible Hybrid Electronics
摘要： Inkjet-printed electronics using metal particles typically lack electrical conductivity and interfacial adhesion with an underlying substrate. To address the inherent issues of printed materials, this paper introduces advanced materials and processing methodologies. Enhanced adhesion of the inkjet-printed copper (Cu) on a flexible polyimide film is achieved by using a new surface modification technique, a nanostructured self-assembled monolayer (SAM) of (3-mercaptopropyl)trimethoxysilane. A standardized adhesion test reveals the superior adhesion strength (1192.27 N/m) of printed Cu on the polymer film, while maintaining extreme mechanical flexibility proven by 100,000 bending cycles. In addition to the increased adhesion, the nanostructured SAM treatment on printed Cu prevents formation of native oxide layers. Combined with newly synthesized Cu ink and associated sintering technique with an intense pulsed ultraviolet and visible light absorption, it enables ultrahigh conductivity of printed Cu (2.3 x 10-6 ??cm), which is the highest electrical conductivity reported to date. The comprehensive materials engineering technologies offer highly reliable printing of Cu patterns for immediate use in wearable flexible hybrid electronics. In vivo demonstration of printed, skin-conformal Cu electrodes indicates a very low skin-electrode impedance (< 50 k?) without a conductive gel and successfully measures three types of biopotentials, including electrocardiograms, electromyograms, and electrooculograms.
关键词： Photonic sintering,Printed Cu membrane,Enhanced conductivity,Interfacial adhesion,Flexible hybrid electronics
更新于2025-09-23 15:21:01
-
Atomic Force Microscopy in Molecular and Cell Biology || AFM Imaging-Force Spectroscopy Combination for Molecular Recognition at the Single-Cell Level
摘要： Molecular recognition at the single-cell level is an increasingly important issue in Biomedical Sciences. With atomic force microscopy, cell surface receptors may be recognized through the interaction with their ligands, inclusively for the identification of cell-cell adhesion proteins. The spatial location of a specific interaction can be determined by adhesion force mapping, which combines topographic images with local force spectroscopy measurements. Another valuable possibility is to simultaneously record topographic and recognition images (TREC imaging) of cells, enabling the mapping of specific binding events on cells in real time. This review is focused on recent developments on these molecular recognition approaches, presenting examples of different biological and biomedical applications.
关键词： Molecular recognition,TREC imaging,Atomic force microscopy,Adhesion force mapping,Biomedical applications
更新于2025-09-23 15:21:01
-
[Advances in Experimental Medicine and Biology] || Photoresponsive Hydrogels with Photoswitchable Stiffness: Emerging Platforms to Study Temporal Aspects of Mesenchymal Stem Cell Responses to Extracellular Stiffness Regulation
摘要： An extensive number of cell-matrix interaction studies have identi?ed matrix stiffness as a potent regulator of cellular properties and behaviours. Perhaps most notably, matrix stiffness has been demonstrated to regulate mesenchymal stem cell (MSC) phenotype and lineage commitment. Given the therapeutic potential for MSCs in regenerative medicine, signi?cant efforts have been made to understand the molecular mechanisms involved in stiffness regulation. These efforts have predominantly focused on using stiffness-de?ned polyacrylamide (PA) hydrogels to culture cells in 2D and have enabled elucidation of a number of mechano-sensitive signalling pathways. However, despite proving to be a valuable tool, these stiffness-de?ned hydrogels do not re?ect the dynamic nature of living tissues, which are subject to continuous remodelling during processes such as development, ageing, disease and regeneration. Therefore, in order to study temporal aspects of stiffness regulation, researchers have developed and exploited novel hydrogel substrates with in situ tuneable stiffness. In particular, photoresponsive hydrogels with photoswitchable stiffness are emerging as exciting platforms to study MSC responses to extracellular stiffness regulation. This chapter provides an introduction to the use of PA hydrogel substrates, the molecular mechanisms of mechanotransduction currently under investigation and the development of these emerging photoresponsive hydrogel platforms.
关键词： Photoswitchable stiffness,Biophysical regulation,Photoresponsive,Cell-matrix interaction,Regenerative medicine,Polyacrylamide,Mechanotransduction,Stiffness regulation,Mesenchymal stem cells,Cell adhesion,Temporal,Hydrogel substrates
更新于2025-09-23 15:21:01
-
Adhesion Behavior between Multilayer Graphene and Semiconductor Substrates
摘要： A high bonding strength between graphene and a semiconductor surface is significant to the performance of graphene-based Micro-Electro Mechanical Systems/Nano-Electro Mechanical Systems (MEMS/NEMS) devices. In this paper, by applying a series of constant vertical upward velocities (Vup) to the topmost layer of graphene, the exfoliation processes of multilayer graphene (one to ten layers) from an Si semiconductor substrate were simulated using the molecular dynamics method, and the bonding strength was calculated. The critical exfoliation velocities, adhesion forces, and adhesion energies to exfoliate graphene were obtained. In a system where the number of graphene layers is two or three, there are two critical exfoliation velocities. Graphene cannot be exfoliated when the Vup is lower than the first critical velocity, although the total number of graphene layers can be exfoliated when the Vup is in the range between the first critical velocity and second critical velocity. Only the topmost layer can be exfoliated to be free from the Si surface if the applied Vup is greater than the second critical velocity. In systems where the number of graphene layers is four to ten, only the topmost layer can be free and exfoliated if the exfoliation velocity is greater than the critical velocity. It was found that a relatively low applied Vup resulted in entire graphene layers peeling off from the substrate. The adhesion forces of one-layer to ten-layer graphene systems were in the range of 25.04 nN–74.75 nN, and the adhesion energy levels were in the range of 73.5 mJ/m2–188.45 mJ/m2. These values are consistent with previous experimental results, indicating a reliable bond strength between graphene and Si semiconductor surfaces.
关键词： adhesion force,bonding mechanism,adhesion energy,exfoliation behavior,MEMS/NEMS,molecular dynamics,graphene
更新于2025-09-23 15:19:57