- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Morphology Controlling of ZnO Sub-Micron- and Micro-Structures from Sub-Micron Zinc Citrate Precursor
摘要： A wet-chemical route has been demonstrated to investigate the morphology evolution of high crystalline ZnO sub-micron- and micro-structures created from a zinc citrate precursor consisted of zinc citrate nanoparticles. The concentrations of precursor zinc citrate and the addition of trisodium citrate were key factors in the controlling of ZnO micro-morphology. Assembled growth resulted in the formation of ZnO sub-micron- and micro-structure with twin-cone and flower-like morphologies. The ZnO flower was consisted of cone petals. The shape of ZnO microstructures was further adjusted using trisodium citrate to created thin and thick hexagonal-plates. In the case of a high Zn concentration, thick hexagonal-plates were split into a flower-like morphology. The investigation of morphological evolution indicated that trisodium citrate is critical to control the growth rate of polar (0001) plane. The formation of a flower-like structure is ascribed to the assembly of crystal units with a high zinc citrate concentration.
关键词： Semiconductors,Morphology,Sub-Micron- and Micro-Structures,ZnO
更新于2025-09-19 17:15:36
-
Green Synthesis of Bismuth Sulfide Nanostructures with Tunable Morphologies and Robust Photoelectrochemical Performance
摘要： Manipulating the morphology of chalcogenide semiconductor crystals to tailor their shape- and size-dependent properties is much desired but remains a grand challenge. Herein, we for the first time develop a green, facile and surfactant-free hydrothermal approach for the synthesis of bismuth sulfide (Bi2S3) with highly tunable morphologies in H2WO4 aqueous solution. The H2WO4 is prone to balance the concentration of Bi3+ to S2- in aqueous solution, thus modulating the nucleation and epitaxial growth of Bi2S3. Specifically, in the presence of lower H2WO4 concentration, low number of Bi2S3 nuclei facilitates the preferred growth of nanorod structures along [001] direction, while the Bi-deficient, S-rich conditions in higher H2WO4 concentration give rise to Bi2S3 nanotubes, presumably due to the stronger interlayer interaction and preferred growth in [hk0] direction. The resulting Bi2S3 nanostructures exhibit broad absorption overlapping UV-Visible-NIR regions and red-shifted absorption edges owing to the increased S/Bi molar ratio in Bi2S3 lattices. The Bi2S3 nanorods with higher aspect ratio demonstrate an enhanced photocurrent response by virtue of the improved charge carrier mobility along [001] direction. Different from previous synthetic methodologies, this work details a facile, effective, and environmentally-benign protocol for the synthesis of Bi2S3 nanomaterials in the aqueous medium without any organic reagents. Noteworthy, the excellent and tailorable photoelectrochemical (PEC) performance endows these Bi2S3 nanostructures with vast potential in solar cell and photodetector applications.
关键词： Photoelectrochemical performance,Morphology control,Nanostructures,Green synthesis,Bismuth sulfide
更新于2025-09-19 17:15:36
-
Root canal morphology of permanent teeth in a Malaysian subpopulation using cone-beam computed tomography
摘要： Background: To determine the root canal morphology of human permanent maxillary and mandibular teeth in a Malaysian subpopulation using cone-beam computed tomography (CBCT). Methods: A total of 208 CBCT images were examined retrospectively. Prevalence of an extra root/canal and internal morphology based on Vertucci’s classification were observed in human maxillary and mandibular permanent teeth. Variations in the external and internal morphology were compared in relation to gender and tooth side (left vs right) using Pearson Chi-square and Fisher’s exact tests with significance level set at p < 0.05. Results: In the maxillary arch, the prevalence of three canals were observed in 0.3% of first premolars and two canals in 46.5% of second premolars. Males displayed significantly higher prevalence of two canals in maxillary second premolars than females (p < 0.05). The prevalence of a second mesiobuccal canal in maxillary first and second molars were 36.3 and 8.5%, respectively. Males displayed significantly higher prevalence of a second mesiobuccal canal in maxillary second molars than females (p < 0.05). The prevalence of a second palatal canal in maxillary first and second molars were 0.9 and 0.6%, respectively. In the mandibular arch, the prevalence of two canals were observed in 5.1% of central incisors, 12.3% of lateral incisors, 6.1% of canines, 18.7% of first premolars and 0.5% of second premolars. The prevalence of a middle mesial canal, second distal canal and extra root (radix entomolaris) were detected in 1.9, 19.5 and 21.4% of mandibular first molars, respectively. The prevalence of a C-shaped canal was observed in 48.7% of mandibular second molars. Females displayed significantly higher prevalence of a C-shaped canal in the right mandibular second molars than males (p < 0.05). No other statistically significant differences in root anatomy and root canal morphology were observed in relation to gender and tooth side. Conclusions: Wide variations in the root canal morphology exist among Malaysians. CBCT is a clinically useful tool in the identification of external and internal morphological variations in the human teeth.
关键词： Root canal,Cone-beam computed tomography,Malaysian,Morphology
更新于2025-09-19 17:15:36
-
Morphology of CdSe-Based Coatings Formed on Polyamide Substrate
摘要： Cadmium selenide (CdSe)-based layers were formed on the surface of polyamide 6 (PA) substrate film by treating PA film samples with potassium selenotrithionate (K2SeS2O6) solution (seleniumization) and then with cadmium(II) acetate, Cd(CH3COO)2, solution (cadmiumization). The morphology of CdSe-based layers was investigated by atomic force and scanning electron microscopies. It was determined that the formation of CdSe-based layers proceeds unevenly in the form of islands, which later tends to agglomerate. Therefore the surface of the layers formed is relatively uneven and rather rough. After seleniumization and cadmiumization procedures the average height of this layer have tendency to decrease from 337 after 1 h of seleniumization to 153 nm at 2.5 and 3.5 h of seleniumization. It was also determined that the RMS of formed layers slightly increases (from 32 to 42 nm) with the prolongation of PA seleniumization (from 1 to 2.5 hours) and it decreases (from 43 to 22 nm) with the increase of the temperature (from 50 °C to 70 °C) of seleniumized PA treatment by the solution containing Cd(II) salt. XPS data show that in coatings, substantial amounts of both cadmium hydroxide (Cd(OH)2) and cadmium oxide (CdO) are formed on the surface and within deeper layers of formed coatings. It was also determined that only a small fraction (～0.1%–2%) of cadmium selenide is present on the surface of formed coating after seleniumization and cadmiumization, while within in the deeper layers the concentrations of both Cd and Se were much higher and the fractions of Cd(OH)2 and CdO decreased.
关键词： SEM,Polyamide,Potassium Selenotrithionate,AFM,Morphology,CdSe-Based Layers
更新于2025-09-19 17:15:36
-
Segmentation of the Optic Nerve Head Based on Deep Learning to Determine its Hemoglobin Content in Normal and Glaucomatous Subjects
摘要： Objective: To determine the limits of the optic nerve head (ONH) in color fundus images using Deep learning (DL) for the estimation of its hemoglobin topographic distribution. Also, to evaluate the usefulness of that distribution in glaucoma diagnosis singly or in association with perimetry. Methods: A DL method was trained using 40000 fundus images and applied to 89 normal eyes and 77 confirmed or suspect glaucomas. DL and manual segmentation were compared. The eyes were also examined once with TOP perimetry (Octopus 300) and Spectralis-OCT and twice with Cirrus-OCT and Laguna ONhE, a program which estimates hemoglobin from color photographs, using improved criteria from previous studies. Results: The Sorensen-Dice similarity index between manual and automatic segmentations was 0.993. Intra-class correlation coefficients were similar when comparing the results of the Laguna ONhE indices using the manual and automatic segmentations (confidence intervals: 0.933-0.978). For specificity close to 95%, the GDF index, a factor that measures the distribution of hemoglobin at the nerve, obtained sensitivities between 70.1 and 74.0% (manual vs. automatic segmentations). The retinal nerve fiber layer thickness (RNFLT) of both OCTs provided sensitivities between 67.1 and 68.8% and the BMO-RMW of Spectralis-OCT 69.7%. Associating several normalized indices, e.g. a new visual field harmony index (Threshold Coefficient of Variation, TCV) and GDF, provided 85.7% sensitivity for 97.8% specificity. GDF correlation with Spectralis-OCT BMO-RMW index was similar to that obtained between this index and the RNFLT of the same instrument. For 95% specificity, the diagnostic concordance (kappa value) between both Spectralis-OCT indices was 0.694 and between its BMO-RMW and Laguna ONhE GDF 0.804-0.828. Conclusion: A fully automatic delimitation of the optic nerve head allows the correct, reproducible and efficient use of the Laguna ONhE method, and its effectiveness is greatly increased if associated with a perimetric harmony index.
关键词： Glaucoma,Visual field,Hemoglobin,Perfusion,Morphology,Perimetry,Optic nerve head
更新于2025-09-19 17:15:36
-
A data-driven framework to predict the morphology of interfacial Cu6Sn5 IMC in SAC/Cu system during laser soldering
摘要： A data-driven approach combining together the experimental laser soldering, finite element analysis and machine learning, has been utilized to predict the morphology of interfacial intermetallic compound (IMC) in Sn-xAg-yCu/Cu (SAC/Cu) system. Six types of SAC solders with varying weight proportion of Ag and Cu, have been processed with fiber laser at different magnitudes of power (30-50 W) and scan speed (10-240 mm/min), and the resultant IMC morphologies characterized through scanning electron microscope are categorized as prismatic and scalloped ones. For the different alloy composition and laser parameters, finite element method (FEM) is employed to compute the transient distribution of temperature at the interface of solder and substrates. The FEM-generated datasets are supplied to a neural network that predicts the IMC morphology through the quantified values of temperature dependent Jackson parameter (αJ). The numerical value of αJ predicted from neural network is validated with experimental IMC morphologies. The critical scan speed for the morphology transition between prismatic and scalloped IMC is estimated for each solder composition at a given power. Sn-0.7Cu having the largest critical scan speed at 30 W and Sn-3.5Ag alloy having the largest critical scan speed at input power values of 40 W and 50 W, thus possessing the greatest likelihood of forming prismatic interfacial IMC during laser soldering, can be inferred as most suitable SAC solders in applications exposed to shear loads.
关键词： Neural network,Intermetallic compound,Lead-free solders,Finite element method (FEM),Laser parameters,Morphology
更新于2025-09-19 17:13:59
-
Surface morphology evolution with laser surface re-melting in selective laser melting
摘要： Laser surface re-melting (LSR) is a promising method for improving the surface quality of parts fabricated via selective laser melting (SLM). In this research, LSR under different linear energy densities (LEDs) was conducted numerically and experimentally. Additionally, double LSR using an LED of 225 J/m was conducted, and the surface morphology, melt pool flow behavior, melt pool size, and thermal behavior was investigated. The results show that for LSR with a low LED, the maximum flow velocity and maximum temperature was rather low, such that the surface was not reconfigured sufficiently. Furthermore, the surface between adjacent scan paths may not be entirely re-melted with a low LED, because the melt pool width was insufficient. However, when the LED was high, the maximum temperature gradient was rather large, giving rise to cracks. For double LSR with a moderate LED, the surface morphology was quite smooth and did not contain obvious defects. The results indicate that LSR is a feasible method for improving the surface quality, and repeated LSR with a moderate LED and small hatch space is recommended in SLM.
关键词： Selective laser melting,Laser surface re-melting,Melt pool flow,Surface morphology evolution
更新于2025-09-19 17:13:59
-
Influence of Perovskite Interface Morphology on the Photon Management in Perovskite/Silicon Tandem Solar Cells
摘要： Perovskite/silicon tandem solar cells are considered as one of the cost-effective solutions for determining high energy conversion efficiencies. Efficient photon management allows improving light incoupling in the solar cells by reducing optical losses. The optics relies upon the interface morphology, consequently, the growth mechanism of the top cell on the bottom cell is crucial for the implementation of efficient perovskite/silicon tandem solar cells. To describe the interface morphologies of perovskite/silicon tandem solar cells, a three-dimensional surface algorithm is used that allows investigating the perovskite solar cells deposited on the textured crystalline silicon solar cells. We distinguish between two extreme cases in which the film grows only in the direction of the substrate normal or in the direction of the local surface normal. The growth mode has a significant influence on the film roughness, the effective thickness of the film, the optics of the solar cell, and the photovoltaic parameters. The optics is investigated by finite-different time-domain simulations. The influence of the interface morphology on the photovoltaic parameters is discussed and guidelines are provided to reach high short-circuit current density and energy conversion efficiency.
关键词： photon management,light trapping,tandem solar cell,realistic interface morphology,Perovskite
更新于2025-09-19 17:13:59
-
Growth and characterization of ZnxSn1?xSe films for use in thin film solar cells
摘要： We have fabricated ZnxSn1?xSe (ZTSe) ?lms for the ?rst time. Samples were fabricated by chemical molecular beam deposition method at atmospheric pressure in hydrogen ?ow. ZnSe and SnSe powders with 99.999% purity were used as precursors. The temperature of precursors varied in the range of (850–950) °C. Films were deposited at substrate temperature of (500–600) °C. Borosilicate glass was used as a substrate. We have studied ZTSe ?lms by EDS, XRD and SEM. The samples had orthorhombic and cubic structures depending on composition. Results of EDS have shown that stoichiometric composition of samples moved to ZnSe side by increasing with substrate temperature. SEM pictures have shown that samples had polycrystalline structure. The grain size varied in the range of (2–15) μm. The grain size of samples increased from (2–5) μm to (15–20) μm for substrate temperatures of 500 °C and 550 °C respectively. While, at a substrate temperature of 600 °C the grain size decreased up to (3–5) μm, possibly, because of increasing of ZnSe content. XRD analysis has shown that samples have ZnSe, SnSe, Se and Sn phases. The band gap of samples varied in the range of 1.0–2.0 eV depending on the ?lm compositions. An inversion of the conductivity type was found: samples fabricated at 500 °C and 550 °C performed of p-type conductivity; while samples fabricated at 600 °C showed n-type conductivity.
关键词： Grain size,Conductivity,X-ray,ZnXSn1?XSe ?lms,Morphology
更新于2025-09-19 17:13:59
-
Small but powerful: Light-emitting diodes for inactivation of Aspergillus species in real water matrices
摘要： This study addressed the effectiveness of light emitting diodes to achieve inactivation of three different Aspergillus species (Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus) in a real water matrix. Three single small ultraviolet-C diodes emitting light at two different wavelengths were tested: 255 nm that is similar to the wavelength emitted by low pressure mercury lamps and 265 nm that is closer to the maximum absorbance wavelength of DNA. The ultraviolet-C diodes emitting light at 265 nm were found to be more effective than the 255 nm, achieving 3-log, 1-log and 5-log inactivations of Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus using less than 20 mJ/cm2 (13,97 mJ/cm2; 7,28 mJ/cm2; 19,74 mJ/cm2). The diodes have also affected the morphology of the fungal spores and increased the percentage of damaged and dead spores.
关键词： Aspergillus species,Membrane permeability,Enzymatic activity,Light emitting diodes,Spores morphology,Disinfection
更新于2025-09-19 17:13:59