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Multifunctional 3D micro-nanostructures fabricated through temporally shaped femtosecond laser processing for preventing thrombosis and bacterial infection
摘要： Blood-contacting medical devices that directly inhibit thrombosis and bacterial infection without using dangerous anticoagulant and antibacterial drugs can save countless lives but have proved extremely challenging. Here, a useful methodology is proposed that employs temporally shaped femtosecond laser ablation combined with fluorination to fabricate a multifunctional three-dimensional (3D) micro-nanostructures with excellent hemocompatibility, zero cytotoxicity, outstanding biocompatibility, bacterial infection prevention, and long-term effectiveness on NiTi alloys. This multifunctional 3D micro-nanostructures presents 0.1% hemolysis ratio, almost no platelet adhesion and activation, repels blood to inhibit blood coagulation in vitro, maintains 100% cell viability and has exceptional stability over 6 months. Moreover, the multifunctional 3D micro-nanostructures simultaneously suppresses bacterial colonization to form biofilm and kills 100% colonized P. aeruginosa and 95.6% colonized S. aureus after 24h incubation, and bacterial residues can be easily removed. The fabrication method in this work has the advantages of simple processing, high efficiency, high quality and high repeatability, and the new multifunctional 3D micro-nanostructures can effectively prevent thrombosis and bacterial infection, which can be widely applied to various clinical needs such as biomedical devices and implants.
关键词： excellent-hemocompatibility,temporally shaped femtosecond laser,no-contamination,bacterium-free,multifunctional 3D micro-nanostructures
更新于2025-09-19 17:13:59
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A comparison of sLASER and MEGA-sLASER using simultaneous interleaved acquisition for measuring GABA in the human brain at 7T
摘要： γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter, is challenging to measure using proton spectroscopy due to its relatively low concentration, J-coupling and overlapping signals from other metabolites. Currently, the prevalent methods for detecting GABA at ultrahigh field strengths (≥ 7 T) are GABA-editing and model fitting of non-editing single voxel spectra. These two acquisition approaches have their own advantages: the GABA editing approach directly measures the GABA resonance at 3 ppm, whereas the fitting approach on the non-editing spectrum allows the detection of multiple metabolites, and has an SNR advantage over longer echo time (TE) acquisitions. This study aims to compare these approaches for estimating GABA at 7 T. We use an interleaved sequence of semi-LASER (sLASER: TE = 38 ms) and MEGA-sLASER (TE = 80 ms). This simultaneous interleaved acquisition minimizes the differential effect of extraneous factors, and enables an accurate comparison of the two acquisition methods. Spectra were acquired with an 8 ml isotropic voxel at six different brain regions: anterior-cingulate cortex, dorsolateral-prefrontal cortex, motor cortex, occipital cortex, posterior cingulate cortex, and precuneus. Spectral fitting with LCModel quantified the GABA to total Cr (tCr: Creatine + Phosphocreatine) concentration ratio. After correcting the T2 relaxation time variation, GABA/tCr ratios were similar between the two acquisition approaches. GABA editing showed smaller spectral fitting error according to Cramér–Rao lower bound than the sLASER approach for all regions examined. We conclude that both acquisition methods show similar accuracy but the precision of the MEGA-editing approach is higher for GABA measurement. In addition, the 2.28 ppm GABA resonance was found to be important for estimating GABA concentration without macromolecule contamination in the GABA-edited acquisition, when utilizing spectral fitting with LCModel.
关键词： GABA,proton spectroscopy,sLASER,MEGA-sLASER,T2 relaxation,macromolecule contamination,7T,LCModel,human brain
更新于2025-09-19 17:13:59
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Impact of Postplating Annealing on Defect Activation in Boron-Doped PERC Solar Cells
摘要： The cold calibration count from the Advanced Technology Microwave Sounder (ATMS) space view increases when the lunar radiation intrudes its antenna field of view (FOV). This increase is referred to as lunar contamination since the cold count is not matched with the specified brightness temperature of 2.73 K. For ATMS, it is found that the elapse time of lunar intrusion (LI) and the magnitude of the cold count increase are channel dependent. If the lunar-affected calibration counts are rejected in the processing, a data gap can be shown in brightness temperature at all channels. At ATMS channels 1 and 2, which have a large FOV, the LI can result in an increase of 40 counts in cold calibration. At higher frequency channels which have a smaller FOV size, the LI intensity is much stronger and can be as large as a few hundred counts. The LI becomes significant when its radiation appears in the ATMS antenna main beam. In the current ATMS operational calibration algorithm, the cold count anomaly is detected when the intensity of LI exceeds a certain threshold. The lunar radiation can be also corrected in the ATMS calibration. In doing so, a lunar radiation term is derived as a function of antenna gain, the solid angle of the Moon, and the brightness temperature of the Moon disk. This algorithm is applied in an ATMS calibration system developed at NOAA and shows a successful removal of all the lunar contamination on the earth-scene brightness temperature.
关键词： calibration,Advanced Technology Microwave Sounder (ATMS),contamination,lunar intrusion (LI)
更新于2025-09-19 17:13:59
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Reconfigurable Optical Boolean Function Generator Based on Electro-Optical Nonlinear Dynamics
摘要： We propose an optical Boolean function generator based on an electro-optical nonlinear feedback loop. Theoretically, all possible Boolean functions with optical input and output can be implemented by passing through enough iterations. By changing the control signal, the optical circuit can be con?gured to any desired Boolean function without adjusting the physical setup. Optical components with high bandwidth can improve the computing speed markedly. The impact of noise on the system is considered in detail. The results show that a substantial number of reliable Boolean functions can be obtained in the presence of noise contamination. Compared with traditional optical digital computation systems, the proposed scheme exhibits a huge advantage in multifunctional computing and ?exible con?guration.
关键词： optical Boolean function generator,noise contamination,electro-optical nonlinear feedback loop,high bandwidth,multifunctional computing
更新于2025-09-19 17:13:59
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Ultra clean manufacturing techniques for final optics assembly in high-power laser facility
摘要： Cleanliness control is one of the most important processes for final optics assembly (FOA) in high-power laser systems. In this paper, an "Ultra Clean Manufacturing (UCM)" concept is put forward for the first time to satisfy the cleanliness requirements for FOA. First, the challenges and requirements for cleanliness in FOA are introduced and the concept of UCM is proposed. Significant surface cleaning technologies for mechanical parts and optics are then expounded. Finally, surface cleanliness control techniques, such as "gas knife" and "laser cleaning", are developed as online cleaning methods for the surface cleanliness in FOA.
关键词： high-power laser facility,cleanness control,contamination,Ultra-clean manufacturing,final optics assembly
更新于2025-09-16 10:30:52
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Contamination of Coupling Glass and Performance Evaluation of Protective System in Vacuum Laser Beam Welding
摘要： Vacuum laser beam welding enables deeper penetration depth and welding stability than atmospheric pressure laser welding. However, contaminated coupling glass caused by welding fumes in the vacuum space reduces laser transmittance, leading to inconsistent penetration depth. Therefore, a well-designed protective system is indispensable. Before designing the protective system, the contamination phenomenon was quanti?ed and represented by a contamination index, based on the coupling glass transmittance. The contamination index and penetration depth behavior were determined to be inversely proportional. A cylindrical protective system with a shielding gas supply was proposed and tested. The shielding gas jet provides pressure-driven contaminant suppression and gas momentum-driven contaminant dispersion. The in?uence of the shielding gas ?ow rate and gas nozzle diameter on the performance of the protective system was evaluated. When the shielding gas ?ow was 2.0 L/min or higher, the pressure-driven contaminant suppression dominated for all nozzle diameters. When the shielding gas ?ow was 1.0 L/min or lower, gas momentum-driven contaminant dispersion was observed. A correlation between the gas nozzle diameter and the contamination index was determined. It was con?rmed that contamination can be controlled by selecting the proper gas ?ow rate and supply nozzle diameter.
关键词： welding consistency,coupling glass,shielding gas,laser welding,vacuum,protective system,contamination
更新于2025-09-16 10:30:52
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Near-Infrared Spectroscopic Study of Heavy-Metal-Contaminated Loess Soils in Tongguan Gold Area, Central China
摘要： Loess soil is a kind of widespread soil type in northwest China. Human engineering activities such as mining have caused numerous problems related to heavy metal pollution in soils, which threaten people’s health. The band formation mechanism of the near-infrared (NIR) spectral features in loess soils forms the theoretical basis for the study of the soil environment by hyperspectral remote sensing. Some NIR features of loess soils will shift because of the variations of the soil composition and microstructure after they adsorb heavy metal cations. In this study, we focused on the heavy metal adsorption of the illite, smectite, and illite–smectite (I/S) mixed layer in loess soils; evaluated the pollution by Nemerow indexing; applied X-ray diffraction (XRD), mid-infrared (MIR) spectral analysis, and inductively coupled plasma mass spectrometry (ICP-MS); and carefully observed the shift behavior of the MIR and NIR features. Then, the NIR bands were assigned to MIR bands according to the vibration behavior. Furthermore, the relationships between the NIR band positions and the six heavy metal cations as well as the Nemerow index were investigated via multiregression and simple linear correlation methods. Finally, the relationship obtained from the experiments was analyzed using the physical and chemical mechanisms of the heavy metal cations in the clay minerals. These findings may benefit the application of NIR and remote sensing techniques for detecting heavy-metal-polluted soils.
关键词： loess soil,combination band,Nemerow index,heavy metal contamination,near infrared
更新于2025-09-16 10:30:52
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Polydispersed Metal Nanoparticles at the Interface for Improved Optoelectronic Properties in Perovskite Photovoltaics
摘要： This paper considers a multi-cell network with base stations (BSs) equipped with large dual-polarized antenna arrays. We derive closed-form expressions of network performance in terms of user signal-to-interference-and-noise ratio both with perfect channel state information and in the presence of pilot contamination. In general, a dual-polarized system enjoys the reduction in pilot contamination and multiuser interference due to orthogonal polarizations, while the available BS array dimension is reduced in each polarized direction compared with a monopole antenna setup. The derived results, however, reveal that the performance of a dual polarization system can be optimized by properly setting receive antenna polarizations, and fortunately, the optimal performance behaves identically to that of a monopole-antenna one in massive MIMO. We ?nally verify the observations by numerical simulations.
关键词： channel capacity,dual-polarized antenna,multi-cell,Massive MIMO,pilot contamination
更新于2025-09-16 10:30:52
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Evaluation of laser cleaning for defouling of marine biofilm contamination on aluminum alloys
摘要： The environmental friendliness short-pulsed laser removal of marine bio?lm contamination developed on the surfaces of aluminum alloy substrates was innovatively applied. Natural bio?lms were formed using a seawater immersion method. The surface state was evaluated by considering the cleaning e?ectiveness and the harm exerted on the aluminum alloy substrate surfaces. The cleaning quality was analyzed using optical microscopy (OM), ?eld emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FT-IR). The laser-induced damage/change to the substrate surface was evaluated using laser scanning confocal microscopy (LSCM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The results indicate that a nanosecond laser can be successfully used to quickly remove marine bio?lm contamination from the surface of an aluminum substrate by instantaneous thermal ablation. No clear thermal damage can be found on the laser-cleaned aluminum surface at a lower laser ?uence (1.08 J/cm2). In addition to the cleaning of marine bio?lm contamination, a higher laser ?uence (4.14 J/cm2) can also contribute to the formation of a hierarchical micro- and nanostructured oxidized layer. It is composed of amorphous-nanocrystalline phases.
关键词： Amorphous-nanocrystal,Surface characterization,Marine bio?lm contamination,Laser cleaning,Hierarchical surface structures
更新于2025-09-16 10:30:52
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Effective size separation of laser-generated, surfactant-free nanoparticles by continuous centrifugation
摘要： High-power, nanosecond, pulsed-laser ablation in liquids enables the continuous synthesis of highly-pure colloidal nanoparticles (NPs) at an application-relevant scale. The gained mass-weighted particle size distribution is however often reported to be broad, requiring post treatment like centrifugation to remove undesired particle size fractions. To date, available centrifugation techniques are generally discontinuous, limiting the throughput and hindering economic upscaling. Hence, throughout this paper, a scalable, continuously operating centrifugation of laser-generated platinum nanoparticles in a tubular bowl centrifuge is reported for the first time. To that end, using a 121 W ns-laser, a continuous production of a colloidal suspension of NPs, yet with broad particle size distribution has been employed, yielding productivities of 1 - 2 g/h for gold, silver, and platinum. Subsequent downstream systematic study of relevant centrifugation parameters involved, effective size optimization and respective size sharpness parameters for a maximum Pt nanoparticle diameter of 10 nm are reported. The results of the experimental centrifugation of laser-generated Pt-NPs were in excellent agreement with the theoretically-calculated cut-off diameter. After centrifugation with optimized parameters, the polydispersity indices of the Pt-NPs size distributions were reduced by a factor of six and higher monodispersities were observed.
关键词： continuous process chain,tubular bowl centrifugation,contamination-free nanoparticle processing,Pt-NPs,pulsed laser ablation in liquids
更新于2025-09-12 10:27:22