Thin films of iron doped hydroxyapatite have been prepared by nanosecond Pulsed Laser Deposition (PLD). The composite target used for the deposition has been obtained by mixing commercial ...hydroxyapatite powder with iron-based nanoparticles produced by femtosecond laser ablation in liquid (LAL) (4% of iron nanoparticles). In fact, LAL technique allows to obtain metallic nanostructures without any toxic chemicals and reagents, with a green approach that is crucial for application in biological and medical technologies. Films have been prepared with substrate temperature growing from room temperature (RT) to 500 °C. The effect of deposition temperature on morphology, composition and structural properties of coatings has been investigated. Films deposited at higher temperature result dense and crystalline, they present microscale and nanoscale structures, an average surface roughness of 0.3 μm and magnetic properties suitable for biomedical applications.
•Fe nanoparticles obtained by laser ablation in liquid has been used to prepare a Fe@HA composite.•Rough, crystalline, magnetic films have been obtained by nanosecond PLD.•Only magnetite phase is present in films deposited at higher temperature.
The electrolyte filling process of battery cells is one of the time-critical bottlenecks in cell production. Wetting is of particular importance here, since only completely wetted electrode sections ...are working. In order to accelerate and facilitate this process, the authors of this study developed a method to significantly increase the wettability of graphite-based anodes by a laser surface modification using low energy nanosecond laser pulses. The anode surface microstructure was evaluated by means of white-light interferometry and scanning electron microscopy. The assessment of wettability was done by drop test and capillary rise test of the liquid electrolyte. The results show that there is a predominantly selective ablation process for laser energy inputs below 2 J/m by which the graphite active material remains unaffected and the binder material is decomposed. The observed increase in surface roughness correlates with the increasing wettability. Investigations using Raman spectroscopy showed that laser treatment leads to a damage on the crystalline structure of the graphite particle surface. However, treating an entire anode including 6 wt% binder and conductive carbon black has shown that the overall amorphous content of the anodes surface can be reduced by 32% through treating the surface with a laser energy of 1.29 J/m. Up to that point, which is the resulting parameter range for the selective process, it is possible to ablate the amorphous binder and carbon black phase coevally exposing graphite particles while keeping their crystalline structure. Exceeding that range, ablation of the whole anode composite dominates and amorphization of the graphite surface occurs. The electrode’s capacity was tested on half-cells in coin cell format. For the whole laser parameter range investigated, the anodes capacity matches the mass loss caused by laser ablation. No additional capacity loss was observed due to amorphization of the exterior graphite particle’s surface.
Microglia sense their environment using an array of membrane receptors. While P2Y12 receptors are known to play a key role in targeting directed motility of microglial processes to sites of damage ...where ATP/ADP is released, little is known about the role of P2Y13, which transcriptome data suggest is the second most expressed neurotransmitter receptor in microglia. We show that, in patch‐clamp recordings in acute brain slices from mice lacking P2Y13 receptors, the THIK‐1 K+ current density evoked by ADP activating P2Y12 receptors was increased by ~50%. This increase suggested that the P2Y12‐dependent chemotaxis response should be potentiated; however, the time needed for P2Y12‐mediated convergence of microglial processes onto an ADP‐filled pipette or to a laser ablation was longer in the P2Y13 KO. Anatomical analysis showed that the density of microglia was unchanged, but that they were less ramified with a shorter process length in the P2Y13 KO. Thus, chemotactic processes had to grow further and so arrived later at the target, and brain surveillance was reduced by ~30% in the knock‐out. Blocking P2Y12 receptors in brain slices from P2Y13 KO mice did not affect surveillance, demonstrating that tonic activation of these high‐affinity receptors is not needed for surveillance. Strikingly, baseline interleukin‐1β release was increased fivefold while release evoked by LPS and ATP was not affected in the P2Y13 KO, and microglia in intact P2Y13 KO brains were not detectably activated. Thus, P2Y13 receptors play a role different from that of their close relative P2Y12 in regulating microglial morphology and function.
Main points
KO of P2Y13 receptors decreases microglial ramification and surveillance, slows chemotaxis to ADP and brain injury, and increases baseline release of interleukin 1β in brain slices.
P2Y13 KO microglia generate larger ADP‐evoked THIK‐1 K+ currents.
The high‐performance unidirectional manipulation of microdroplets is crucial for many vital applications including water collection and bioanalysis. Among several actuation methods (e.g., electric, ...magnetic, light, and thermal actuation), mechanical vibration is pollution‐free and biocompatible. However, it suffers from limited droplet movement mode, small volume range (VMax/VMin < 3), and low transport velocity (≤11.5 mm s−1) because the droplet motion is a sliding state caused by the vertical vibration on the asymmetric hydrophobic microstructures. Here, an alternative strategy is proposed—horizontal vibration for multimode (rolling, bouncing/reverse bouncing, converging/diffusing, climbing, 90o turning, and sequential transport), large‐volume‐range (VMax/VMin ≈ 100), and high‐speed (≈22.86 mm s−1) unidirectional microdroplet manipulation, which is ascribed to the rolling state on superhydrophobic slant microwall arrays (SMWAs) fabricated by the one‐step femtosecond laser oblique ablation. The unidirectional transport mechanism relies on the variance of viscous resistance induced by the difference of contact area between the microdroplet and the slant microwalls. Furthermore, a circular, curved, and “L”‐shaped SMWA is designed and fabricated for droplet motion with particular paths. Finally, sequential transport of large‐volume‐range droplets and chemical mixing microreaction of water‐based droplets are demonstrated on the SMWA, which demonstrates the great potential in the field of microdroplet manipulation.
The high‐performance unidirectional manipulation of microdroplets, such as multimode (rolling, bouncing/reverse bouncing, converging/diffusing, climbing, 90° turning, and sequential transport), large‐volume‐range and high‐speed transport, by horizontal vibration is achieved on a polymeric substrate with slant microgroove arrays fabricated by femtosecond laser oblique ablation technology, demonstrating great potential in the field of liquid microreactions.
The copper isotopic compositions of 12 copper-rich minerals (including native copper, sulfides, carbonates, oxides, and copper chloride) have been determined using a 206 nm ultraviolet femtosecond ...laser ablation multi-collector inductively coupled plasma mass spectrometry (UV-fs-LA-MC-ICP-MS). A pure copper wire NWU-Cu-B and a natural chalcopyrite TC1725 were used as bracketing standards for calibration. Reliable and precise (2SD<0.07‰)
δ
65
Cu values can be obtained using matrix-matched standards under dry plasma condition and calibrated by the standard-sample bracketing method (SSB). However, the
δ
65
Cu values calibrated by non-matrix-matched standards were seriously affected by matrix effect, with a deviation of up to 1.42‰. Therefore, matrix-matched standards are necessary for reliable
in situ
Cu isotope ratio measurement. Although the analytical precision (2SD) is slightly improved, the use of Ga as an internal standard combined with the SSB correction does not reduce the deviation caused by the matrix effect. However, the matrix effect can be significantly suppressed by adding 8.6 µL min
−1
water into the carrier gas. The matrix-induced
δ
65
Cu deviation of the TC1725 calibrated against the pure copper NWU-Cu-B was reduced from 0.99‰ in dry plasma mode to 0.03‰ in wet plasma mode and achieved a long-term reproducibility of 0.10‰ (2SD). For the Cu isotopic compositions of 12 natural copper-rich minerals determined under wet plasma mode, the deviation of
δ
65
Cu was less than 0.13‰ if the mineral is homogeneous. These results indicate that the non-matrix-matched standardization can be achieved by fs-LA-MC-ICP-MS under wet plasma condition, whether using chalcopyrite or pure copper as the external bracketing standards.
This study aimed to investigate the influence of texture structure on the tribological property of diamond coating on the various surface texture of WC-Co cemented carbide surfaces. The surface ...texture was fabricated by laser ablation technology. The diamond coating was coated on the textured cemented carbide surface by adopting the hot filament chemical vapor deposition (HFCVD) method. The tribological properties of untextured and textured diamond coatings were measured utilizing a reciprocating ball-on-plate friction test against GCr15 bearing ball. The test was done under the condition of dry frictions at room temperature. The experimental results revealed that the diamond coatings were perfectly superimposed on the surface texture. The diamond coating's secondary nucleation rate at the edge of the texture was more obvious than other places. Furthermore, the texture type and texture surface area had a conspicuous impact on the friction coefficient and wear resistance of diamond coating under dry friction state. For the same type of textures, the friction coefficient of textured diamond coating considerably decreased with the increase of texture surface area. The elliptical textures were found to further reduce the friction coefficient of diamond coatings by capturing abrasive particles, compared to the grooved texture. Machining textures on diamond films was an effective method to improve the tribological properties of the friction pair.
Brazed monolayer diamond grinding wheels have advantages of a high abrasive bonding strength, high protrusion, and a large chip disposal space. However, it is difficult to prepare ordered and ...fine-grained brazed diamond grinding wheels. This study presents a new method for grain-arranged, brazed diamond grinding wheels with microtextures with similar performance to ordered and fine-grained brazed diamond grinding wheels. First, coarse diamond grains (18/20 mesh) were orderly brazed to fabricate the end grinding wheels. Next, a series of microtextures were ablated on the diamond grains using a pulsed laser, and two types of textured end grinding wheels—TG-G (ablated microgrooves only) and TG-GH (ablated microgrooves and microholes)—were prepared. Then, an experiment involving the grinding of alumina ceramics was performed, and the grinding characteristics and grinding mechanism were analyzed. The results indicated that compared with untextured diamond end grinding wheels (TG), the textured diamond grinding wheels (TG-G and TG-GH) significantly reduced the grinding force and the roughness of the machined surface. The local stress concentration at the microtextures promoted the formation of microcracks in the diamond grains of TG-G and TG-GH, and the self-sharpness of the grinding wheel was significantly improved. The brittle fracture mode of ceramic materials in grinding included intergranular fracture and transgranular fracture. Ironing pressure action was a key material-removal mechanism. It had an important influence on the cutting force and plasticity characteristics of the TG machined surface. For the surfaces processed by TG-G and TG-GH, the effect of ironing was weakened, while shearing played a more important role. The TG-GH grinding wheel ablated with microgrooves and microholes was superior to the TG-G grinding wheel ablated with only microgrooves, with regard to the grinding force, roughness, and self-sharpening.
In this study, the surface of MWCNTs was treated with acid by adding a carboxyl group to be ready to load nanostructured materials on their surface in a novel way. The femtosecond laser ablation ...process was used for decorating magnetic nanoparticles (Fe3O4) on the functionalized carbon nanotubes (MWCNTs-COOH) to form the MWCNTs-COO@Fe3O4 nanocomposite structure to be used for the heavy metal removal of Pb(II). Different techniques have all been used to identify the functionality groups that are present on the MWCNTs. Raman spectroscopy showed the decrease of G band when Fe3O4 nanoparticles embedded MWCNTs-COOH, indicating a greater degree of defect in MWCNTs. VSM showed the magnetic characteristic properties of the composite. XRD showed the reduction of MWCNTs diffraction peaks after embedding with iron oxide, explained the partial full coverage of the MWCNTs surface by the Fe3O4 nanoparticles. FT-IR showed the composite exhibit a peak at 579 cm−1, which is brought on by the Fe–O stretching vibrational modes. Zeta potential showed the surface of the MWCNTs-COO@Fe3O4 had a more positive charge under neutral pH compared with that of MWCNTs. TGA showed the weight loss of MWCNTs-COO@Fe3O4 was greater than that of MWCNTs, confirming the interaction of some Fe3O4 on MWCNTs-COOH. Also, tested pH, contact time, initial Pb (II) concentration, and adsorbent mass were carried to improve Pb (II) ion adsorption on the nanocomposite. The optimal removal effectiveness of Pb (II) on the MWCNTs-COO@Fe3O4 nanocomposite is attained when the experiment is conducted at a pH of 6, with a contact time of 10 min, an initial concentration of 100 mg/L, and under alkaline conditions. Pb (II) ions were adsorbing using a pseudo-second-order equation to reflect their chemical adsorption, with a rate constant of (k2 = 0.00446 g mg−1 min−1). The highest adsorption capacity obtained was 66.85 mg g−1. MWCNTs-COO@Fe3O4 nanocomposite efficiently collected Pb (II) utilizing green and easy to use method to protect public health.
•Fe3O4/MWCNTs were prepared using femtosecond pulsed laser ablation.•Iron oxide decorated MWCNTs by facile one-pot synthesis.•Fe3O4/MWCNTs have good adsorption removal of Pb (II) from aqueous solution.•Fe3O4/MWCNTs were investigated by different techniques.
Femtosecond laser ablation is widely applied in the drilling of film cooling holes of turbine blades and vanes. A deep understanding of the interaction between the femtosecond laser and the target ...material is crucial for processing parameter optimization. In this work, numerical simulations are performed on the basis of a traditional two-temperature model, and laser irradiation on the surface of Ni-based and Fe-based superalloys is investigated. The evolution of electron and lattice temperature is calculated, and the crater morphology and recast layer thickness are thus determined with respect to the vaporization and melting temperatures. The depth and diameter of the crater and melting front are not greatly changed by advancing the single-pulse energy from 20 μJ to 120 μJ and 720 μJ, which is contrary to the opinion that machining efficiency is strongly determined by the applied pulse energy. However, Fe seems to be more easily ablated than Ni, resulting in a larger crater depth. By setting different values of pulse width, single-pulse energy and electron–phonon coupling strength, the evolution of electron and lattice climax temperature is investigated, and the underlying nature of energy coupling is clarified. The two temperature model is further extended to simulate the multiple-pulse laser percussion process. The crater maintains a rotating parabolic shape while deepening. Interestingly, the material removal rate is the highest at a certain depth for different single-pulse energies and target materials. The physical presence of a first increasing then decreasing trend is analysed in detail. In the end, the relationship between crater depth and pulse number indicates that the focal spot should shift downward by a feeding rate to realize high-efficiency laser ablation.
•Two temperature model is extended by quantum treatment to simulate femtosecond laser machining on Fe and Ni based super alloys.•Physical essence of different stages of electron and lattice temperature evolution over time is clarified.•The crater morphology formed and recast layer thickness are determined by the current approach.•Effective material removal rate is found to follow a first upward then downward trend with the increase of crater depth.
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