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Creating an antibacterial surface on beta TNZT alloys for hip implant applications by laser nitriding
摘要： The National Joint Registry reported that the main causes for hip implant revision surgery include aseptic loosening, infection and adverse soft tissue reaction to particulate debris. There is a great need to improve the implant properties which can be achieved through a combined solution of beta titanium alloy (TNZT) with low elastic modulus and laser surface nitriding to improve mechanical properties and biological response. While titanium nitride (TiN) possesses good biocompatibility and remarkable antibacterial properties; its effectiveness as a coating on Ti-35Nb-7Zr-6Ta has not been investigated in relation to stem cell response and antibacterial laser power, specifically 35, 40 and 45 W. capability. TNZT surfaces were laser-nitrided in incremental Investigation included surface roughness and topography in microscale (WLI and SEM), microstructure (XRD) and wettability (water contact angle). Biological studies of the laser-nitrided surfaces included in vitro culture for 24 h using mesenchymal stem cell (MSC) fluorescence staining and Staphylococcus aureus (S. aureus) Live/Dead staining. Sample groups consisted of control base metal (BM), laser-nitrided at 35 W (LT35), 40 W (LT40) and 45 W (LT45). Results revealed that laser nitriding generates significantly rougher surfaces (Ra value of BM was 199.3 nm, LT35 was 722.8 nm, LT40 was 458.4 nm and LT45 was 1180.2 nm) with distinctive surface features (Rsk < 0 and Rku > 3). Surfaces after laser nitriding, regardless of laser power, can be tailored to become hydrophilic (27.1–34.2°). Fibre laser nitriding can be used to create antibacterial surface patterns on TNZT in a high power regime. A laser power of 45 W proved to be the most effective in this study, creating an overlapping crescent shape which becomes more obvious with increasing power. To summarise, laser-nitrided surfaces led to a significant antibacterial effect but offered no particular advantage to MSC response.
关键词： Fibre laser nitriding,TNZT,Antibacterial performance,Mesenchymal stem cell (MSC),Beta titanium
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Direct mapping of Li-enabled octahedral tilt ordering and associated strain in nanostructured perovskites
摘要： Self-assembled nanostructures are promising for creating 2D and 3D superlattices with exceptional functionalities. Understanding the mechanisms driving the superlattice formation demands the underlying structural information. However, nanoscale structural modulations intrinsic to these superlattices are difficult to be characterized by conventional diffraction-based structure determination. A real-space, direct imaging method is necessary to probe the local structure characteristics, providing essential information for theoretical understanding and subsequent design of structure-property correlations. Using the aberration-corrected scanning transmission electron microscopy (STEM), we developed an optimized atomic-level bright-field (BF) condition to image the oxygen octahedra in perovskite oxides. We used multislice calculations to determine detector collection angles that allow oxygen octahedra to be imaged sensitively and robustly over large specimen thicknesses. These calculations also provided a calibration by which the octahedral-tilt angle can be measured quantitatively from the image of each octahedron. Applying this real-space octahedral-tilt mapping on Li0.5–3xNd0.5+xTiO3, a promising solid electrolyte in Li-ion batteries, we directly revealed an unconventional superlattices with 2D modulated octahedral tilting. A mathematical description of the octahedral-tilt modulation was derived based on the quantitative tilt maps, which explicitly identified the high-order harmonic character of the modulation. Using simultaneous annular-dark-field (ADF) imaging, we also mapped the lattice parameters unit-cell by unit-cell, uncovering highly-localized strain associated with the tilt modulation. Furthermore, we demonstrate the tunability of the tilt modulation by changing Li stoichiometry. Fascinatingly, we observe a reversible annihilation/reconstruction of the tilt modulation correlated with delithiation/lithiation process, suggesting the structural transformation that is associated with Li-ion conduction in this promising Li-ion conductor. The above observations are largely inaccessible from conventional diffraction analysis, and lead to an unprecedented mechanically-coupled tilting competition model to explain the superlattice formation. Our real-space approach to quantify local octahedral structure and correlate it with strain can be applied to other advanced oxide systems.
关键词： 2D modulated structure,STEM,Li-ion solid electrolyte,perovskite oxides,oxygen octahedral tilting
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Laser induced yellowing of stonework: a combined TEM imaging and STEM-EELS study on model samples
摘要： Nd-YAG Q-Switched laser devices operating at 1064 nm have been considered in the 1990s as the most promising tool for cleaning stone sculptures, and more particularly eliminating indurated black gypsum crusts. However, the spreading of this laser technology has been undermined because of the yellow hue it occasionally conveys to the cleaned surfaces as seen on Figure 1. Especially in France, this yellowing effect is considered as a major esthetic issue by conservators and the laser technique has gradually disappeared from the restoration sites. This discoloration issue remains partly unexplained: a currently admitted hypothesis states that the iron containing compounds present in the black crusts would transform, upon laser irradiation, into yellow iron-rich nanophase(s) that would re-deposit on the cleaned substrate. To verify this hypothesis, model black crusts have been elaborated by mixing hematite α-Fe2O3 and gypsum CaSO4.2H2O in different proportions. The model crusts were irradiated using a Nd-YAG QS laser resulting in ablation of numerous particles in a visible smoke and the color of the samples shifted instantaneously from red to a bright yellow. Transmission electron microscopy (TEM) has been used to characterize the morphology of the nanostructures generated by the laser, both in the smoke and on the surface of the samples as observed in Figure 2. In addition, the chemical composition of the neo-formed nanophases was determined by aberration corrected scanning transmission electron microscopy in combination with electron energy loss spectroscopy (STEM-EELS) and high angle annular dark field imaging (HAADF) as seen on Figure 3. It was found that both the surface of the samples and the ablated micro-materials are covered by an irregular nano-film and by dispersed spherical nanoparticles, all containing iron and oxygen. These results ascertain the link between the yellowing effect and the presence of iron containing nanophases after irradiation.
关键词： EELS,TEM,STEM,nano materials,iron,yellowing,laser
更新于2025-09-11 14:15:04
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Direct Observation of Infrared Plasmonic Fano Antiresonances by a Nanoscale Electron Probe
摘要： In this Letter, we exploit recent breakthroughs in monochromated aberration-corrected scanning transmission electron microscopy (STEM) to resolve infrared plasmonic Fano antiresonances in individual nanofabricated disk-rod dimers. Using a combination of electron energy-loss spectroscopy and theoretical modeling, we investigate and characterize a subspace of the weak coupling regime between quasidiscrete and quasicontinuum localized surface plasmon resonances where infrared plasmonic Fano antiresonances appear. This work illustrates the capability of STEM instrumentation to experimentally observe nanoscale plasmonic responses that were previously the domain only of higher-resolution infrared spectroscopies.
关键词： STEM,infrared,Fano antiresonances,plasmonic,EELS
更新于2025-09-11 14:15:04
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PS02.062: CONFOCAL LASER ENDOMICROSCOPY IN THE ASSESSMENT OF PERSISTENT/RECURRENT INTESTINAL METAPLASIA/NEOPLASIA AFTER ENDOSCOPIC TREATMENT OF BORN
摘要： Recent studies revealed that membrane proteins, such as ion transporters, are specifically activated in cancer stem cells (CSCs). Therefore, these molecules are receiving a great attention as new chemotherapeutic targets of malignant tumor. This study aimed to investigate the expression and activity of ion transport-related molecules in CSCs of esophageal squamous cell carcinoma (ESCC).
关键词： Esophageal squamous cell carcinoma,FDG-PET/CT,esophageal cancer,Esophageal cancer,stem cell,TRPV2,Tranilast,False positive,LncRNA
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Improving Reliability of InAs Quantum Dot Lasers on Silicon Substrates
摘要： Using correlated electron microscopy techniques, we structural properties of characterize optoelectronic and dislocation in InAs quantum dots (QD) structures. Results indicate that although dislocations significantly affect QD luminescence, the rate of recombination enhanced dislocation climb slows noticeably during the aging process from quantum well structures.
关键词： quantum dot laser,STEM,dislocation,silicon photonics,cathodoluminescence,III-V on Si
更新于2025-09-11 14:15:04
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Combination of laser and human adipose-derived stem cells in repair of rabbit anal sphincter injury: a new therapeutic approach
摘要： Background: Anal sphincter injury leads to fecal incontinence. Based on the regenerative capability of laser and human adipose-derived stem cells (hADSCs), this study was designed to assess the effects of co-application of these therapies on anal sphincter recovery after injury. Design: Male rabbits were assigned to equal groups (n = 7) including control, sphincterotomy, sphincterotomy treated with laser (660 nm, 90 s, immediately after sphincterotomy, daily, 14 days), hADSCs (2 × 106 hADSCs injected into injured area of the sphincter immediately after sphincterotomy), and laser + hADSCs. Ninety days after sphincterotomy, manometry and electromyography were performed, sphincter collagen content was evaluated, and Ki67, myosin heavy chain (MHC), skeletal muscle alpha-actin (ACTA1), vascular endothelial growth factor A (VEGFA), and vimentin mRNA gene expression were assessed. Results: The laser + hADSCs group had a higher resting pressure compared with the sphincterotomy (p < 0.0001), laser (p < 0.0001), and hADSCs (p = 0.04) groups. Maximum squeeze pressure was improved in all treated animals compared with the sphincterotomized animals (p < 0.0001), without a significant difference between treatments (p > 0.05). In the laser + hADSCs group, motor unit numbers were higher than those in the laser group (p < 0.0001) but did not differ from the hADSCs group (p = 0.075). Sphincterotomy increased collagen content, but the muscle content (p = 0.36) and collagen content (p = 0.37) were not significantly different between the laser + hADSCs and control groups. Laser + hADSCs increased ACTA1 (p = 0.001) and MHC (p < 0.0001) gene expression compared with laser or hADSCs alone and was associated with increased VEGFA (p = 0.009) and Ki67 mRNA expression (p = 0.01) and decreased vimentin mRNA expression (p < 0.0001) compared with laser. Conclusion: The combination of laser and hADSCs appears more effective than either treatment alone for promoting myogenesis, angiogenesis, and functional recovery after anal sphincterotomy.
关键词： Lasers,Fecal incontinence,Mesenchymal stem cells
更新于2025-09-11 14:15:04
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Energy losses and transition radiation in graphene traversed by a fast charged particle under oblique incidence
摘要： We perform fully relativistic calculations of the energy loss channels for a charged particle traversing a single layer of graphene under oblique incidence in a setting pertinent to a scanning transmission electron microscope (STEM), where we distinguish between the energy deposited in graphene in the form of electronic excitations (Ohmic loss) and the energy emitted in the far field in the form of transition radiation (TR). Our formulation of the problem uses a definition of two in-plane, dielectric functions of graphene, which describe the longitudinal and transverse excitation processes that contribute separately to those two energy loss channels. Using several models for the electric conductivity of graphene as the input in those dielectric functions enables us to discuss the effects of oblique incidence on several processes in a broad range of frequencies, from the terahertz (THz) to the ultraviolet (UV). In particular, at the THz frequencies, we demonstrate that the nonlocal effect in the graphene’s conductivity is not important in the retarded regime, and we show that the longitudinal and transverse contributions to the emitted TR spectra exhibit strongly anisotropic angular patterns that are readily distinguishable in a cathodoluminescence measurement in a STEM. Moreover, we explore the possibility of exciting the so-called transverse mode in the optical response of graphene at the mid-infrared (MIR) range of frequencies by means of a fast charged particle under oblique incidence. Finally, we demonstrate that, aside from the usual high-energy peaks in the longitudinal contribution to the Ohmic energy loss in the MIR to the UV frequency range, there may arise strongly directional features in the in-plane distribution of the transverse contribution to the Ohmic energy loss for an oblique trajectory, which could be possibly observed via momentum- and angle-resolved electron energy loss spectroscopy of graphene in STEM.
关键词： MIR,energy loss,STEM,THz,transition radiation,UV,graphene,cathodoluminescence,oblique incidence,Ohmic loss
更新于2025-09-11 14:15:04
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Radical induced cationic frontal twin polymerization of Si-spiro compound in combination with bisphenol-A-diglycidylether
摘要： The radical induced cationic frontal polymerization (RICFP) of the twin monomer with 2,2’-spirobi[4H-1,3,2-benzodioxasiline] combination (SPIRO) in bisphenol-A-diglycidylether (BADGE) has been developed to fabricate nanostructured hybrid material with domain sizes of 2–5 nm. In one reaction step, an interpenetrating network of phenolic resin, SiO2 and the epoxy resin is formed in a very short time period, initiated by UV light. That indicates that both polymerization reactions take place simultaneously. The influence of monomer composition on molecular structure was investigated by means of solid state NMR spectroscopies. The envisaged nanostructure of the resulting organic-inorganic hybrid materials is proven by transmission electron microscopy high-angle annular dark-field scanning (HAADF-STEM). The thermal properties of the hybrid materials are comparable to “state of the art” materials with the advantage that the silica quantity can be adjusted on demand.
关键词： Nanostructured hybrid material,HAADF-STEM,Solid state NMR spectroscopy,Radical induced cationic frontal polymerization,Twin polymerization
更新于2025-09-11 14:15:04
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Self-Formation of RPE Spheroids Facilitates Enrichment and Expansion of hiPSC-Derived RPE Generated on Retinal Organoid Induction Platform
摘要： PURPOSE. Retinal pigment epithelium (RPE) and neural retina could be generated concurrently through retinal organoid induction approaches using human induced pluripotent stem cells (hiPSCs), providing valuable sources for cell therapy of retinal degenerations. This study aims to enrich and expand hiPSC-RPE acquired with this platform and explore characteristics of serially passaged RPE cells. METHODS. RPE has been differentiated from hiPSCs with a published retinal organoid induction method. After detachment of neural retina on the 4th week, the remaining mixture was scraped from the dish and subjected to suspension culture for the formation of RPE spheroids. RPE sheets were isolated and digested for expansion. The cellular, molecular, and functional features of expanded RPE cells were evaluated by different assays. RESULTS. Under suspension culture, hiPSC-RPE spheroids with pigmentation self-formed were readily enriched by removing the non-retinal tissues. RPE sheets were further dissected and purified from the spheroids. The individualized RPE cells could be passaged every week for at least 5 times in serum medium, yielding large numbers of cells with high quality in a short period. In addition, when switched to a serum-free medium, the passaged RPE cells could mature in cellular, molecular, and physiological levels, including repigmentation, markers expression, and phagocytosis. CONCLUSIONS. We developed a simple and novel RPE spheroids formation approach to enrich and expand hiPSC-RPE cells generated along with retinal neurons on a universal retinal organoid induction platform. This achievement will reduce the cost and time in producing retinal cells for basic and translational researches, in particular for retinal cell therapy.
关键词： differentiation,human induced pluripotent stem cells,retinal pigment epithelium,retinal degenerations,organoids
更新于2025-09-11 14:15:04