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Bumpy Hollow Gold Nanospheres for Theranostic Application: Effect of Surface Morphology on Photothermal Conversion Efficiency
摘要： The combination of hollow core and rugose surface morphology is highly attractive for photoactive near-infrared (NIR) nanomaterials. Here, we present a facile pH modification to hollow gold nanosphere (HGN) synthesis to enable controlled tuning of the surface morphology from smooth to very bumpy. Unlike other methods, the synthetic protocol does not require harsh surfactants, secondary reducing agents, or organic solvents. The resultant bumpy HGNs (bHGNs) are highly monodisperse with little variation in protrusion length from particle to particle. Mechanistic studies suggest that surface rugosity is mainly controlled by the presence of free OH- ions in solution. We also present the first systematic investigation into the effect of surface morphology on the photothermal conversion efficiency (PCE) of bumpy as well as smooth HGNs, with a maximum PCE reaching 99%. Although expected to have a higher scattering component, the bHGNs retain the excellent PCE of their smooth counterparts, which may be due to efficient reabsorption of scattered light.
关键词： surface plasmon resonance,photothermal conversion efficiency,heat generation,surface morphology,hollow gold nanospheres
更新于2025-09-23 15:23:52
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Bio-Inspired Structural Colors based on Linear Ultra-High Molecular Weight Block Copolymers
摘要： Ultra-high molecular weight (UHMW) block copolymers (BCPs) are promising candidates for the fabrication of photonic materials. Here, we demonstrate the synthesis and self-assembly capability of well-defined amphiphilic UHMW BCPs with overall molar masses up to 4432 kg mol-1 obtained via living anionic polymerization. BCP micelles featuring hydrodynamic diameters in the range of the wavelength of the visible light to the near infrared region (300-1143 nm) are used for colloidal crystal formation. By varying the BCP composition brilliant structural colours can be observed. Microphase separation of the UHMW BCPs in the bulk state reveals uniform domains and showing blue to green structural color transitions. Finally, we provide examples of how BCP structural control can be used to generate reversibly switchable solvatochromatic optical sensors.
关键词： morphology,block copolymers,structural colors,self-assembly,anionic polymerization,micellar photonic crystals,photonic materials
更新于2025-09-23 15:23:52
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Effects of precursors and caustic bases on structural and vibrational properties of ZnO nanostructures elaborated by hydrothermal method
摘要： The effects of zinc ions source (zinc acetate and zinc sulfate) and caustic bases (sodium and potassium hydroxides) on structural, morphological and vibrational properties of ZnO nanostructures elaborated by simple low temperature wet chemical process are studied. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared (FTIR) and Raman spectroscopies. XRD results show that ZnO structures are polycristalline hexagonal wurtzite with high crystal quality. SEM images reveal that the morphologies of the nanostructures are nanopencils except in those synthesized with zinc sulfate precursor and sodium hydroxide caustic base, where pencils agglomerate to form sand rose-like morphologies. EDAX measurements confirm the purity of the elaborated specimens by the presence of only Zn and O atoms in the samples. Raman spectroscopy studies show that the peaks, related to E2 high mode, are more intense in ZnO structures elaborated with zinc acetate when NaOH is used, and in ZnO structures elaborated with zinc sulfate when KOH is employed.
关键词： alkali hydroxides,hydrothermal synthesis,ZnO,structure,morphology,source precursor
更新于2025-09-23 15:23:52
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Synthesis and photocatalytic properties of biomimetic morphology silicon carbide
摘要： Silicon carbide materials with bionic morphology are prepared by impregnation-calcination method using the template of leaf vein. The microstructure, element composition, and band gap of biomimetic morphology silicon carbide are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS). Photocatalytic property of biomimetic morphology silicon carbide has been measured by the dye decolorization reaction. The results demonstrate that calcination temperature has the important effect on the formation of silicon carbide. The morphology of silicon carbide can keep the original biomimetic shape of leaf vein template, and there is meosporous structure with a diameter of 2-4 nm on the interior of material. The average gain size of materials is about 16.9 nm and the specific surface area of materials is about 84.7 m2/g. After calculation, the band gap of material is 3.02 eV. For performance testing, the degradation rate of silicon carbide is 92.86% for the first time, and after the fourth repetition, the degradation rate decreased to 86.74%.
关键词： Biological Template,Silicon Carbide,Biomimetic Morphology,Photocatalytic Property
更新于2025-09-23 15:23:52
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Investigation on tool wear process of milling wave-transmitting Si <sub/>3</sub> N <sub/>4</sub> ceramics
摘要： Due to the low fracture toughness of wave-transmitting Si3N4 ceramics, the special material removal mechanism causes the tool wear to be different. The paper presents the tool wear forms and mechanism under different milling depth. The effect of tool wear on cutting force and machined surface morphology is discussed. Tests have been performed under typical conditions of cutting depth of 0.3 mm (in plastic-domain processing) and 0.4 mm (in brittle-domain processing). The results show that the abrasive wear caused by the chips is the main mechanism of the cutting edge wear and the flank wear, the increase of the side edge rear angle with tool wear is the main cause of the chipping phenomenon. The cutting depth is a significant influence parameter to the wear characteristics, and two types have been distinguished. As the material removal volume ascending, the cutting edge wear and the flank face wear has a stable period, and the root-mean-square deviation of processing surface increases to 1.6 μm, while that increase with the material removal volume continuously, and the processing surface decreases to 1.4 μm. It has been proved that the cutting force tends to increase first and then decrease as the material removal volume is about 4320 mm3.
关键词： ceramics,milling,morphology,plastic-domain,chipps,wear,Tool,brittle-domain,surface
更新于2025-09-23 15:23:52
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Study of the relationship between metal-assisted chemical etching and direction of the applied electric field
摘要： Metal-assisted chemical etching (MACE) has been proposed as a promising alternative for the fabrication of micro/nano-structures on silicon with simple process and low cost. Electric field can be applied during the reaction to control the motion of charged particles so as to accelerate the reaction and form uniform vertical trenches with high aspect ratio. In this paper, boron doped p-type (100) silicon wafers with resistivity of 20～30 Ω·cm was used as substrates. After coated with layers of 5 nm Ti and 10 nm Au, the silicon substrate was immersed into the etchant containing hydrofluoric acid (HF) and hydrogen peroxide (H2O2) with high HF-to-H2O2 concentration ratio (ρ) and an applied voltage of 40 volts. It was found that the direction of the applied electric field had a great influence on morphologies of the trenches. Deeper trenches with vertical sidewalls and relatively smoother bottom were observed when silicon substrate was connected to cathode of the power supply. Possible interpretation to these phenomena was proposed, and the effect of the electric field intensity and doping concentration was further studied.
关键词： trench morphology,metal-assisted chemical etching,electric field,HF-to-H2O2 ratio,electrode connection
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Investigation of the Phase Composition and Morphology of Silicon Structures by Using the Raman Spectroscopy to Determine the Parameter of Crystallinity
摘要： This work aims to investigate the dependence of the phase composition of thin films of microcrystalline silicon deposition on process parameters. The films of microcrystalline silicon were obtained by plasma-chemical deposition method (PECVD). Phase composition and correlation between degree of crystallinity and structure of the obtained layers were analyzed by Raman Spectroscopy. The results show that the control of several technical parameters, e.g. pressure, discharge power and monosilane flow, allows to reach the crystallinity parameter in the range 50-70 %. Based on the conducted experiments, the recommendations for the control of the crystallinity parameter, which are planned to be implemented when working with silicon-based porous structures, were proposed.
关键词： Morphology,Semiconductors,Silicon,Por-silicon,Phase composition,Raman spectroscopy,Raman Crystallinity
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Experimental Characterization of Graphene Thick Films
摘要： While the plasmonic nature of graphene at terahertz frequencies has been widely reported, investigations on the practical utility of graphene at the microwave frequencies are sparse. In this paper, an ink comprising graphene thick films of different concentrations (12.5 wt.%, 25 wt.% and 33 wt.%) is prepared for deposition, by screen printing. Detailed investigation of the surface morphology of the films using SEM and AFM reveals that the graphene films present a homogeneous dispersion of the filler with a comparatively lower surface roughness at higher concentrations, and negligible agglomerates. The films are then printed in between copper electrodes on FR-4 substrate, commonly used in RF circuits, and the measured scattering parameters analyzed.
关键词： screen printing,radio frequency (RF),graphene,thick films,surface morphology
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 3rd Advanced Information Technology, Electronic and Automation Control Conference (IAEAC) - Chongqing, China (2018.10.12-2018.10.14)] 2018 IEEE 3rd Advanced Information Technology, Electronic and Automation Control Conference (IAEAC) - Medical image segmentation based on improved watershed algorithm
摘要： The watershed segmentation algorithm has the problem of over-segmentation. The paper proposed an improved watershed algorithm for medical image segmentation. Combined with improved gray morphological reconstruction and watershed algorithm, the segmentation of medical cells and brain CT images is improved, which improves the accuracy of image segmentation of medical tissues and organs and assists doctors to diagnose the diseases. The simulation results show that the improved algorithm can effectively suppress the over-segmentation for two different medical tissue images.
关键词： watershed algorithm,medical image,segmentation,grayscale morphology
更新于2025-09-23 15:23:52
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Morphology Control of Hydrothermally Grown ZnO Nanostructures by Additives and Seed Layers
摘要： We present a rational control over the morphology of hydrothermally grown ZnO nanostructures by introducing different additives, sequential seeding, and multilayer seeds. The aspect ratio of the ZnO nanorods could be tuned with different types of additives (surfactant, amine, metal salt, and polymer additives) at an appropriate concentration in solution for ZnO hydrothermal growth. Some of the metal salts induced change in both aspect ratio and coverage simultaneously. The degree of vertical alignment of the ZnO nanowires was influenced by the number of seed layers. Furthermore, hierarchical ZnO nanostructures could be fabricated for thermal annealing on a secondary seed layer. The various control parameters demonstrated in this study provide beneficial information that can be used to guide a new strategy for relevant future applications.
关键词： Seed,Additive,Morphology,Hydrothermal,Zinc Oxide
更新于2025-09-23 15:22:29