Search Results (12)

In conventional hydrology, a short-duration design rainstorm is typically used to estimate the design discharge in urban sewer systems. The reason for using a short duration is that engineers believe the time of concentration in urban watersheds is relatively small. The short-duration hyetograph is supposed to generate a flow hydrograph that accurately reflects the rainfall-runoff processes. In this study, we developed a street-sewer runoff model for an urban district of 2470 hectares. Detailed field flooding records were utilized to verify the stormwater model’s capability for inundation simulations. Subsequently, different rainfall series extracted from the recorded rainstorm data were used to investigate the causes of flooding corresponding to different durations of rainstorms. The results indicate that a 90 min main concentrated rainstorm causes small-scale flooding only; however, a 24 h rainfall series results in an extensive range of inundations. We further conducted similar short- and long-duration hyetograph tests in 16 urban drainage partitions (ranging from 2.3 to 193.5 hectares) to confirm the above findings. The results indicate that the maximum discharge in most partitions can only be found when the hyetograph duration exceeds 1080 min, which essentially contradicts previous engineering designs in urban watersheds in Taiwan. Full article

In the present study, a nanocrystalline Ni-Fe matrix with reinforced TiO₂ nanoparticles as a functional nanocomposite material was fabricated by pulsed current electroforming in UV-LIGA (lithography, electroplating, and molding). The influences of TiO₂ nanoparticles on the Ni-Fe nanocomposite deposition were also investigated using scanning electron microscopy, transmission electron microscopy, and in vitro cytotoxicity assay. It was found that the Ni-Fe nanocomposite with 5 wt.% TiO₂ nanoparticles showed a smooth surface and better dispersion property. When the Ni-Fe nanocomposite is combined with 20 wt.% TiO₂, it resulted in congeries of TiO₂ nanoparticles. In addition, TiO₂ nanoparticles possessed better dispersion properties as performed in pulse current electrodeposition. The microstructure of the electrodeposited Ni-Fe-TiO₂ nanocomposite was a FeNi3 phase containing anatase nano-TiO₂. Moreover, the electrodeposited Ni-Fe-5 wt.% TiO₂ nanocomposite exhibited a smooth surface and structural integrity. Cytotoxicity assay results also proved that the Ni-Fe nanocomposite with different concentrations of TiO₂ nanoparticles had good biocompatibility. Therefore, the optimization of pulse current electroforming parameters was successfully applied to fabricate the Ni-Fe-TiO₂ nanocomposite, and thus could be used as an endodontic file material for dental applications. Full article

This study optimized the ultrasound image of carotid artery stenosis using Taguchi dynamic analysis and an indigenous water phantom. Eighteen combinations of seven essential factors of the ultrasound scan facility were organized according to Taguchi’s L₁₈ orthogonal array. The seven factors were assigned as follows: (1) angle of probe; (2) signal gain; (3) resolution vs. speed; (4) dynamic range; (5) XRES; (6) zoom; (7) time gain compensation. An indigenous water phantom was customized to satisfy the quantified need in Taguchi’s analysis. Unlike the conventional dynamic Taguchi analysis, an innovative quantified index, the figure of merit (FOM), was proposed to integrate four specific quality characteristics, namely (i) average difference between the practical scan and theoretically preset area (78.5, 50.2 and 12.6 mm²) of stenosis, (ii) standard deviation of the average, (iii) practical scan’s sensitivity β to various stenosis diameters (10, 8, and 4 mm), and (iv) correlation coefficient r² of the linear regressed sensitivity curve. The highest value (FOM = 0.413) was furnished by the optimal combination of factors on 18 groups under study, yielding high r² and low β or standard deviation values and the best quality of ultrasound images for the further clinical diagnosis. The comparison between FOM and the conventional signal-to-noise (S/N) ratio in Taguchi’s analysis revealed that FOM compiled more quality characteristics that were superior by nature to fulfill the practical need in clinical diagnosis. The alternative choice in ultrasound scan optimization can be based on stenosis diameter variation from a different perspective to be explored in the follow-up study. Full article

The present study was to investigate the rheological property, printability, and cell viability of alginate–gelatin composed hydrogels as a potential cell-laden bioink for three-dimensional (3D) bioprinting applications. The 2 g of sodium alginate dissolved in 50 mL of phosphate buffered saline solution was mixed with different concentrations (1% (0.5 g), 2% (1 g), 3% (1.5 g), and 4% (2 g)) of gelatin, denoted as GBH-1, GBH-2, GBH-3, and GBH-4, respectively. The properties of the investigated hydrogels were characterized by contact angle goniometer, rheometer, and bioprinter. In addition, the hydrogel with a proper concentration was adopted as a cell-laden bioink to conduct cell viability testing (before and after bioprinting) using Live/Dead assay and immunofluorescence staining with a human corneal fibroblast cell line. The analytical results indicated that the GBH-2 hydrogel exhibited the lowest loss rate of contact angle (28%) and similar rheological performance as compared with other investigated hydrogels and the control group. Printability results also showed that the average wire diameter of the GBH-2 bioink (0.84 ± 0.02 mm (*** p < 0.001)) post-printing was similar to that of the control group (0.79 ± 0.05 mm). Moreover, a cell scaffold could be fabricated from the GBH-2 bioink and retained its shape integrity for 24 h post-printing. For bioprinting evaluation, it demonstrated that the GBH-2 bioink possessed well viability (>70%) of the human corneal fibroblast cell after seven days of printing under an ideal printing parameter combination (0.4 mm of inner diameter needle, 0.8 bar of printing pressure, and 25 °C of printing temperature). Therefore, the present study suggests that the GBH-2 hydrogel could be developed as a potential cell-laden bioink to print a cell scaffold with biocompatibility and structural integrity for soft tissues such as skin, cornea, nerve, and blood vessel regeneration applications. Full article

This study uses hyperspectral imaging (HSI) and a deep learning diagnosis model that can identify the stage of esophageal cancer and mark the locations. This model simulates the spectrum data from the image using an algorithm developed in this study which is combined with deep learning for the classification and diagnosis of esophageal cancer using a single-shot multibox detector (SSD)-based identification system. Some 155 white-light endoscopic images and 153 narrow-band endoscopic images of esophageal cancer were used to evaluate the prediction model. The algorithm took 19 s to predict the results of 308 test images and the accuracy of the test results of the WLI and NBI esophageal cancer was 88 and 91%, respectively, when using the spectral data. Compared with RGB images, the accuracy of the WLI was 83% and the NBI was 86%. In this study, the accuracy of the WLI and NBI was increased by 5%, confirming that the prediction accuracy of the HSI detection method is significantly improved. Full article

In order to select the best mixed amines in the CO₂ capture process, the absorption of CO₂ in mixed amines was explored at the required concentrations by using monoethanolamine (MEA) as a basic solvent, mixed with diisopropanolamine (DIPA), triethanolamine (TEA), 2-amino-2-methyl-1-propanol (AMP), and piperazine (PZ). Here, a bubble column was used as the scrubber, and a continuous operation was adopted. The Taguchi method was used for the experimental design. The conditional factors included the type of mixed amine (A), the ratio of the mixed amines (B), the liquid feed flow (C), the gas-flow rate (D), and the concentration of mixed amines (E). There were four levels, respectively, and a total of 16 experiments. The absorption efficiency (E_F), absorption rate (R_A), overall mass transfer coefficient (K_Ga), and scrubbing factor ($\varphi$) were used as indicators and were determined in a steady-state by the mass balance and two-film models. According to the Taguchi analysis, the importance of the parameters and the optimum conditions were obtained. In terms of the absorption efficiency (E_F), the absorption rate (absorption factor) (R_A/$\varphi$), and the overall mass transfer coefficient (K_Ga), the order of importance is D > E > A > B > C, D > E > C > B > A, and D > E > C > A > B, respectively, and the optimum conditions are A1B4C4D3E3, A1B3C4D4E2, A4B2C3D4E4, and A1B1C1D4E1. The optimum condition validation results showed that the optimal values of E_F, R_A, and K_Ga are 100%, 30.69 × 10⁻⁴ mol/s·L, 1.540 l/s, and 0.269, respectively. With regard to the selection of mixed amine, it was found that the mixed amine (MEA + AMP) performed the best in the CO₂ capture process. Full article

The present study established a maximum standard for printing quality and developed a preliminary ideal index to print three-dimensional (3D) construct using the Gly-Arg-Gly-Asp (GRGD) peptide modified Pluronic-F127 hydrogel (hereafter defined as 3DG bioformer (3BE)) as bioink. In addition, the biocompatibility of 3BE for 3D printing applications was carefully investigated. For biocompatibility study and ideal printing parameter, we used the formulation of 3BE in three different concentrations (3BE-1: 25%, 3BE-2: 30%, and 3BE-3: 35%). The 3BE hydrogels were printed layer by layer as a cube-like construct with all diameters of the needle head under the same feed (100 mm/s). The printing parameters were determined using combinations of 3BE-1, 3BE-2, and 3BE-3 with three different standard needle sizes (Φ 0.13 mm, Φ 0.33 mm, and Φ 0.9 mm). The printed constructs were photographed and observed using optical microscopy. The cell viability and proliferation were evaluated using Live/Dead assay and immunofluorescence staining. Results showed that a stable of printed line and construct could be generated from the 3BE-3 combinations. Cytotoxicity assay indicated that the 3BE hydrogels possessed well biocompatibility. Bioprinting results also demonstrated that significant cell proliferation in the 3BE-3 combinations was found within three days of printing. Therefore, the study discovered the potential printing parameters of 3BE as bioink to print a stable construct that may also have high biocompatibility for cell encapsulation. This finding could serve as valuable information in creating a functional scaffold for tissue engineering applications. Full article

In this study, the Pluronic F127 with modified tripeptide Gly-Arg-Gly-Asp copolymer (hereafter defined as 3BE) hydrogel was evaluated in terms of its biocompatibility potentials. The fibroblasts (Swiss 3T3 cell line) and human hair follicles-derived mesenchymal stem cells (HFMSCs) were cultured in different concentrations of the 3BE hydrogel (0%, 0.05%, 0.1%, 0.25%, and 0.5%, respectively). The cell morphology and differentiation potential of HFMSCs were observed through optical microscopy, and the cell viability was investigated via Live/Dead Kit and Cell Counting Kit-8 assay. Analytical results showed that HFMSC can differentiate into adipogenic, chondrogenic, and osteogenic lineages. The HFMSC and Swiss 3T3 cells would properly assemble into a spherical shape as cultured with the 3BE hydrogel. Most importantly, cell viability could be maintained above 70%. The formation of spheroid structures of cells within this hydrogel is predicted to promote cell differentiation potentials of HFMSC that benefit in generating functional adipocytes, chondrocytes, and osteoblasts. Therefore, these findings demonstrate that the 3BE hydrogel has great potential as a three-dimensional cell culture scaffold for tissue engineering applications. Full article

This study aimed to analyze characteristics of an innovative α-calcium sulfate hemihydrate (α-CSH) bioceramic and bone healing and regeneration characteristics following its implantation on artificially created defects of rat models and human jaw defects. The α-CSH bioceramic was characterized using field emission scanning electron microscope (FE-SEM), energy-dispersive spectroscopy (EDS), and thermal-imaging instruments. The material was implanted on artificially created defects in a rat’s right hind leg bone and observed histologically after three days and seven weeks. The material was also implanted in patients with bone defects in the posterior maxillary, then observed immediately and six months post-treatment by panoramic and computed tomography image. The FE-SEM confirm this material is a uniform-shaped short column crystal, while the EDS measurement reveals calcium as the most component in this material. Thermal observation shows temperature change during the setting time is less than 2 °C, and the maximum temperature reached is 31 °C. In the histological analysis, α-CSH bioceramic shows new trabecular bone formation and absorbed material at seven weeks post-treatment. Moreover, panoramic and computed tomography image shows intact bone six months post-treatment. Therefore, this study suggests that the innovative α-CSH bioceramic can be useful in bone defect treatment. Full article

In this study, needle-like and pyramidal hybrid black silicon structures were prepared by performing metal-assisted chemical etching (MACE) on alkaline-etched silicon wafers. Effects of the MACE time on properties of the black silicon wafers were investigated. The experimental results showed that a minimal reflectance of 4.6% can be achieved at the MACE time of 9 min. The height of the nanostructures is below 500 nm, unlike the height of micrometers needed to reach the same level of reflectance for the black silicon on planar wafers. A stacked layer of silicon nitride (SiN_x) grown by inductively-coupled plasma chemical vapor deposition (ICPCVD) and aluminum oxide (Al₂O₃) by spatial atomic layer deposition was deposited on the black silicon wafers for passivation and antireflection. The 3 min MACE etched black silicon wafer with a nanostructure height of less than 300 nm passivated by the SiN_x/Al₂O₃ layer showed a low surface recombination rate of 43.6 cm/s. Further optimizing the thickness of ICPCVD-SiN_x layer led to a reflectance of 1.4%. The hybrid black silicon with a small nanostructure size, low reflectance, and low surface recombination rate demonstrates great potential for applications in optoelectronic devices. Full article

This paper demonstrates how firms can deal with demand uncertainty through inventory planning and demand switching, which take advantage of the risk-pooling effect and contribute to supply-chain sustainability. Considering two types of products and two outsourcing strategies (competitive bidding, and consignment stock under the (Q, R) inventory policy with variable lead times), the study helps determine the appropriate outsourcing strategy when a firm practices demand switching. Under certain conditions, the study further identifies the proper demand-switching direction and optimum switching-rate to achieve the minimum total purchase and inventory costs in association with outsourcing. Prior research generally implies that demand switching increases costs or profit benefits. This implication, however, does not hold true in the present context. The study presents numerical examples to illustrate the derived models. The findings enrich the extant literature by incorporating demand switching into the outsourcing practices, which is beneficial to both practitioners and scholars. Full article

Recombination of charge carriers at silicon surfaces is one of the biggest loss mechanisms in crystalline silicon (c-Si) solar cells. Hafnium oxide (HfO₂) has attracted much attention as a passivation layer for n-type c-Si because of its positive fixed charges and thermal stability. In this study, HfO₂ films are deposited on n-type c-Si using remote plasma atomic layer deposition (RP-ALD). Post-annealing is performed using a rapid thermal processing system at different temperatures in nitrogen ambient for 10 min. The effects of post-annealing temperature on the passivation properties of the HfO₂ films on c-Si are investigated. Personal computer one dimension numerical simulation for the passivated emitter and rear contact (PERC) solar cells with the HfO₂ passivation layer is also presented. By means of modeling and numerical computer simulation, the influence of different front surface recombination velocity (SRV) and rear SRV on n-type silicon solar cell performance was investigated. Simulation results show that the n-type PERC solar cell with HfO₂ single layer can have a conversion efficiency of 22.1%. The PERC using silicon nitride/HfO₂ stacked passivation layer can further increase efficiency to 23.02% with an open-circuit voltage of 689 mV. Full article