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Reduced graphene oxide supported MnO2 nanorods as recyclable and efficient adsorptive photocatalysts for pollutants removal
摘要： The emerging concept of two dimensional (2D) hybrid materials with large surface area and good interfacial contacts is highly desirable for diverse catalytic applications. Herein, we have designed and developed novel 1D-2D nanocomposite by loading manganese dioxide (MnO2) nanorods over reduced graphene oxide (RGO) nanosheets by facile hydrothermal synthesis method to exploit the large surface area, close contact of 1D-2D components with abundant reaction sites. The as prepared MnO2-RGO nanocomposite has been characterized in detail using state-of-art techniques and has been successfully utilized efficient adsorptive photocatalysts for the removal of a colored dye (neutral red) and a colorless pollutant (ciprofloxacin) from water. In addition, the stability and recyclability of this catalyst has also been demonstrated. This work is expected to pave way for the development of many new 1D-2D binary nanocomposite catalysts for environmental remediation applications.
关键词： Reduced graphene oxide,MnO2 nanorods,Photocatalysis,Pollutants removal,Ciprofloxacin,Neutral red
更新于2025-09-23 15:21:21
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Improving the Visible-Light Photocatalytic Activity of Graphitic Carbon Nitride by Carbon Black Doping
摘要： Hydrogen production by water splitting and the removal of aqueous dyes by using a catalyst and solar energy are an ideal future energy source and useful for environmental protection. Graphitic carbon nitride can be used as the photocatalyst with visible light irradiation. However, it typically suffers from the high recombination of carriers and low electrical conductivity. Here, we have developed a facile mix-thermal strategy to prepare carbon black-modified graphitic carbon nitrides, which possess high electrical conductivity, a wide adsorption range of visible light, and a low recombination rate of carriers. With the help of carbon black, highly crystallized graphitic carbon nitrides with built-in triazine and heptazine heterojunctions are obtained. Improved photocatalytic activities have been achieved in carbon black-modified graphitic carbon nitride. The dye removal rate can be three times faster than that of pristine graphitic carbon nitride and the photocatalytic H2 generation is 234 μmol h?1 g?1 under visible light irradiation.
关键词： aqueous dyes removal,hydrogen production,carbon black doping,graphitic carbon nitride,visible-light photocatalytic activity
更新于2025-09-23 15:21:21
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Research on image de-disturbing algorithm based on dark channel prior and anisotropic Gaussian filtering
摘要： In order to solve the problem of serious degradation of images collected outdoors in dense fog weather, a defogging algorithm for dense fog images was proposed. The fog-day imaging physical model was simplified; the concept of fog concentration factor was proposed. The single image de-hazing algorithm based on dark channel priors solves the problem of estimating the transmittance of fog and sky scenes. The image recovered by the algorithm is clear and natural. The algorithm has high computational complexity. It takes a long time to meet real-time requirements. The principle of anisotropic Gaussian filtering is introduced. It combines with the dark channel. The value of the fog concentration coefficient is obtained by estimating the visibility value of a single fog image. It is then combined with an anisotropic Gaussian filter of the image to estimate the atmospheric light value. Defogging of the fog image is performed by using the repair function. It is necessary to perform effective de-hazing processing on smog images. Experiments show that the improved algorithm can greatly reduce the complexity of the algorithm while ensuring the defogging effect of the original algorithm.
关键词： anisotropy,Gaussian filter,foggy image removal,dark channel prior principle
更新于2025-09-23 15:21:21
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Disinfection of Contaminated Metal Implants with an Er:YAG Laser
摘要： Infections related to orthopedic procedures are considered particularly severe when implantation materials are used, because effective treatments for biofilm removal are lacking. In this study, the relatively new approach for infection control by using an erbium:yttrium‐aluminum‐garnet (Er:YAG) laser was tested. This laser vaporizes all water containing cells in a very effective, precise, and predictable manner and results in only minimal thermal damage. For preliminary testing, 42 steel plates and 42 pins were seeded with mixed cultures. First, the minimally necessary laser energy for biofilm removal was determined. Subsequently, the effectiveness of biofilm removal with the Er:YAG laser and the cleansing of the metal implants with octenidine‐soaked gauze was compared. Then, we compared the effectiveness of biofilm removal on 207 steel pins from 41 patients directly after explantation. Sonication and scanning electron microscopy were used for analysis. Laser fluences exceeding 2.8 J/cm2 caused a complete extinction of all living cells by a single‐laser impulse. Cleansing with octenidine‐soaked gauze and irradiation with the Er:YAG laser are both thoroughly effective when applied to seeded pins. In contrast, when explanted pins with fully developed biofilms were analyzed, we found a significant advantage of the laser procedure. The Er:YAG laser offers a secure, complete, and nontoxic eradication of all kinds of pathogens from metal implants without damaging the implant and without the possible development of resistance. The precise noncontact removal of adjacent tissue is a decisive advantage over conventional disinfectants. Therefore, laser irradiation could become a valuable method in every debridement, antibiotics, and implant retention procedure.
关键词： implant‐related infection,DAIR,Er:YAG laser,laser disinfection,pin‐tract infection,biofilm removal
更新于2025-09-23 15:21:01
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The First Commercial 730a??nm Picosecond-Domain Laser is Safe and Effective for Treating Multicolor Tattoos
摘要： Background and Objectives: Laser‐pumped lasers enable driving a secondary wavelength through pumping with a primary device. Here we investigate the first 730 nm laser‐pumped laser for efficacy in tattoo removal. Study Design/Materials and Methods: Fifteen subjects with 20 tattoos were enrolled to investigate the effect of a new 730 nm, titanium‐sapphire laser‐pumped laser at removing decorative tattoos. A total of four treatments were administered and photographic improvement of pre‐ and post‐treatment cross‐polarized digital images was evaluated by four blinded physician observers using an 11‐point scale. Results: Blinded assessment of pre‐ and post‐treatment images found 70%, 77%, 83%, 83%, 26%, and 8% clearance from baseline images for black, green, blue, purple, red and yellow pigments, respectively. Side effects were limited to pinpoint bleeding and erythema immediately after treatment and some crusting and scale up to 1–2 weeks following treatment, and a localized allergic reaction in a single subject. There was no scarring or pigmentary alteration visible in any follow‐up images. Conclusion: The new 730 nm, picosecond‐domain, titanium‐sapphire, laser‐pumped laser is safe and effective for removing multicolored tattoos. Green, blue, and purple pigments cleared the most as expected, but black ink cleared more completely than was predicted.
关键词： 730 nm,laser,ink,green,blue,removal,picosecond,tattoo
更新于2025-09-23 15:21:01
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Deformation and removal of semiconductor and laser single crystals at extremely small scales
摘要： Semiconductor and laser single crystals are usually brittle and hard, which need to be ground to have satisfactory surface integrity and dimensional precision prior to their applications. Improvement of the surface integrity of a ground crystal can shorten the time of a subsequent polishing process, thus reducing the manufacturing cost. The development of cost-effective grinding technologies for those crystals requires an in-depth understanding of their deformation and removal mechanisms. As a result, a great deal of research efforts were directed towards studying this topic in the past two or three decades. In this review, we aimed to summarize the deformation and removal characteristics of representative semiconductor and laser single crystals in accordance with the scale of mechanical loading, especially at extremely small scales. Their removal mechanisms were critically examined based on the evidence obtained from high-resolution TEM analyses. The relationships between machining conditions and removal behaviors were discussed to provide a guidance for further advancing of the grinding technologies for those crystals.
关键词： semiconductor,laser crystal,deformation and removal,transmission electron microscopy (TEM),grinding
更新于2025-09-23 15:21:01
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Numerical studies of metal particle behaviors inside the selective laser melting (SLM) chamber through computational fluid dynamics (CFD)
摘要： The flow behavior of the shielding gas has been a key factor to improve the quality of products manufactured by the selective laser melting (SLM) technology as it is a major mechanism to remove the ejected metal particles away from the working plane. In this study, to obtain a proper flow field, computational fluid dynamics (CFD) with the application of the Taguchi method was employed to investigate the flow field across the working chamber, with the variations in the geometries of the blowing nozzle, the widths of the suction tunnel, the suction-to-plane distances, and the Reynolds numbers of the blowing flow. The simulation was first verified with experimental measurements. The ejecting motions of the metal powders were also taken into consideration to study the interactions between the shielding gas and the ejected particles. The results demonstrated that axis switching as well as the suction-to-plane distance are the important factors for improving the particle removal efficiency during the SLM operation.
关键词： Selective laser melting,Computational fluid dynamics,Particle removal efficiency,3-D printing,Axis switching,Taguchi method
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Improvement of Ohmic Behavior of Back Contact in ZnSnP <sub/>2</sub> Solar Cells by Inserting Cu <sub/>3</sub> P
摘要： We propose a sampling scheme that can perfectly re- construct a collection of spikes on the sphere from samples of their lowpass-?ltered observations. Central to our algorithm is a gen- eralization of the annihilating ?lter method, a tool widely used in array signal processing and ?nite-rate-of-innovation (FRI) sam- pling. The proposed algorithm can reconstruct spatial samples. For large, this sampling require- ment improves over previously known FRI sampling schemes on the sphere by a factor of four. We showcase the versatility of the proposed algorithm by applying it to three problems: 1) sampling diffusion processes induced by localized sources on the sphere, 2) shot noise removal, and 3) sound source localization (SSL) by a spherical microphone array. In particular, we show how SSL can be reformulated as a spherical sparse sampling problem.
关键词： sparse sampling,spherical harmonics,sphere,Annihilation ?lter,?nite rate of innovavtion,diffusion sampling,shot noise removal,sound source localization
更新于2025-09-23 15:21:01
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Hybrid Ligand Exchange of Cu(In,Ga)S <sub/>2</sub> Nanoparticles for Carbon Impurity Removal in Solution Processed Photovoltaics
摘要： The solution processing of Cu(In,Ga)(S,Se)2 photovoltaics from colloidal nanoparticles has long suffered from deleterious carbonaceous residues originating from long chain native ligands. This impurity carbon has been observed to hinder grain formation during selenization and leave a discrete residue layer between the absorber layer and the back contact. In this work, organic and inorganic ligand exchanges were investigated to remove tightly bound native oleylamine ligands from Cu(In,Ga)S2 nanoparticles, thereby removing the source of carbon contamination. However, incomplete ligand removal, poor colloidal stability, and/or selective metal etching was observed for these methods. As such, an exhaustive hybrid organic/inorganic ligand exchange was developed to bypass the limitations of individual methods. A combination of microwave-assisted solvothermal pyridine ligand stripping followed by inorganic capping with diammonium sulfide was developed and yielded greater than 98% removal of native ligands via a rapid process. Despite the aggressive ligand removal, the nanoparticle stoichiometry remained largely unaffected when making use of the hybrid ligand exchange. Furthermore, highly stable colloidal ink formulations using non-toxic dimethyl sulfoxide were developed, supporting stable nanoparticle mass concentrations exceeding 200 mg/mL. Scalable blade coating of the ligand exchanged nanoparticle inks yielded remarkably smooth and microcrack free films with RMS roughness less than 7 nm. Selenization of ligand exchanged nanoparticle films afforded substantially improved grain growth as compared to conventional non-ligand exchanged methods yielding an absolute improvement in device efficiency of 2.8%. Hybrid ligand exchange nanoparticle based devices reached total-area power conversion efficiencies of 12.0%, demonstrating the feasibility and promise of ligand exchanged colloidal nanoparticles for the solution processing of Cu(In,Ga)(S,Se)2 photovoltaics.
关键词： hybrid ligand exchange,blade coating,diammonium sulfide,carbon impurity removal,photovoltaics,grain growth,Cu(In,Ga)(S,Se)2,solution processing,ligand exchange,selenization,microwave-assisted solvothermal,colloidal nanoparticles,device efficiency
更新于2025-09-23 15:21:01
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Spherical Mirror and Surface Patterning on Silicon Carbide (SiC) by Material Removal Rate Enhancement Using CO2 Laser Assisted Polishing
摘要： Silicon carbide (SiC) is well known as an excellent material for high performance optical applications because it offers many advantages over other commonly used glasses and metals. The excellent attributes of SiC include high strength, high hardness, low density, high thermal resistance, and low coefficient of thermal expansion. The effect of CO2 laser and its tool path on SiCwere investigated. The process started by creating laser pre-cracks on the desired pattern. Subsequently, laser assisted polishing was conducted on the same tool path. The surface showed a sharp increase in material removal in the areas with laser pre-cracks. This high difference in material removal was used not only to fabricate a ? 1100?mm concave mirror with 127?μm in depth but also to generate macro and micro patterns. Grooves from 2?mm to 200?μm in width and 5?μm to 20?μm depth were successfully generated.
关键词： Material removal rate,CO2 laser,Patterning,Polishing,Hybrid
更新于2025-09-23 15:21:01