One-step synthesis of single-phase (Co,Mg, Ni,Cu, Zn) O High entropy oxide nanoparticles through SCS procedure: Thermodynamics and experimental evaluation

Evaluation of the thermodynamic aspects of the synthesis process offers a better insight through the single-step synthesis of high entropy oxide particles. The thermodynamic calculations were used to specify the required conditions (fuel type and fuel amount) for the synthesis of single-phase (Co, Mg, Ni, Cu, Zn) O particles. Moreover, the impact of the activities coefficients alteration on the formation of (Co, Mg, Ni, Cu, Zn) O single-phase was calculated. Experiments were carried out using glycine, urea, citric acid, and hexamine at various fuel to oxidizer ratios (φ = 1.05, 1, 0.95, and 0.9) to explore the effect of fuel type and φ values on physicochemical properties of final product. Obtained results indicated that single-phase (Co, Mg, Ni, Cu, Zn) O powders were synthesized using glycine at the fuel-lean condition. Prepared powders exhibited promising crystallinity (59%), the thermal stability of 400 °C, 28 nm particle size, high porosity, and 15 m². g^?1 surface area.     

Investigation of the socio-economic feasibility of installing wind turbines to produce hydrogen: Case study

The objective of this study is to socially and economically investigate installation of wind turbines in Iran in order to produce hydrogen using its electricity. Due to adequate condition of wind blow in Manjil, Zabol, and Ardebil, these cities were chosen as the case studies and sample society. To scrutinize the acceptance of wind power among the sample members, first, data was gathered through questionnaires and analyzed by Partial Least Squares (PLS) approach to Structural Equations Modeling (SEM). The results showed that the first hypothesis (H1), positive effect of financial condition of households on wind power acceptance, was rejected with the coefficient of 1.184. On the other hand, the second hypothesis (H2) was approved with a meaningful coefficient of 3.159, that is, the social awareness of wind energy has a positive effect on its acceptance as an electricity generating source. Costs and Incomes Chart was utilized to estimate the payback period of investing in the wind power site project. Five wind turbines with different nominal capacities were tested and the results showed that the payback period for Manjil is shorter than that of others’ in a way that for turbines with 5, 30, 50, 60 and 100 kW nominal capacity is 3.1, 2.4, 2.3, 1.9, 2.6 years respectively. Finally, Hummer H25.0–60 KW wind turbine was selected due to its payback time which was less than other turbines to estimate the amount of hydrogen produced. The results showed that with installing one set of this turbine in Manjil, Zabol, and Ardebil 7.12, 5.82 and 5.72 ton hydrogen per year will be produced, respectively.     

Heat transfer enhancement of serpentine channels with twisted tape insert by computational fluid dynamics and artificial intelligence

Improving the thermal–hydraulic performance of heat exchangers is a critical challenge. In this study, we investigated the impact of twisted tape insert geometrical variables, namely pitch length (P) and diameter (W), on the Nusselt number (Nu) and friction factor (f) within serpentine channels. To accomplish this, we employed computational fluid dynamics (CFD) as our simulation technique, with water as the working fluid. The validity of the CFD data was confirmed, leading to the development of artificial intelligence (AI) subsets: artificial neural network (ANN) and genetic algorithm (GA). In the prediction models, the following input variables were considered: Reynolds number (Re), (P/D_h), and (W/D_h). The ANN and GA models achieved a mean relative error (MRE) of 0.125% and 1.326% for Nu, and 0.139% and 4.104% for f, respectively. These results demonstrate the high accuracy of the correlations, with the ANN model showcasing superior performance.     

TBM performance estimation using a classification and regression tree (CART) technique

Bulletin of Engineering Geology and the Environment - With widespread increasing applications of mechanized tunneling in almost all ground conditions, prediction of tunnel boring machine (TBM)...     

Working conditions of Iranian hand-sewn shoe workers and associations with musculoskeletal symptoms

The working conditions and the prevalence of self-reported musculoskeletal symptoms among 180 Iranian hand-sewn shoe workers were evaluated in this cross-sectional study. Data were collected using both questionnaire (for assessing musculoskeletal symptoms and associated risk factors) and direct observations of posture (by the Rapid Upper Limb Assessment [RULA] method). The prevalence and severity of symptoms was very high among the study population. The mean RULA grand score of 6.2 indicates that in most cases the workers' postures at their workstations need to be investigated and some changes are required immediately. Multiple logistic regression models indicated that the job experience, daily working hours, duration of continuous work without breaks, feeling pressure due to work and working postures were significantly associated with musculoskeletal symptoms of different body regions. The results are discussed in terms of their implications for hand-sewing tasks. These findings can help to better understand the working conditions of those jobs involving hand-sewing operation and highlight the potential for ergonomic interventions to reduce musculoskeletal symptoms among these working groups.

Practitioner Summary: Working conditions of hand-sewn shoe workers and their musculoskeletal symptoms were investigated. The prevalence and severity of musculoskeletal symptoms was very high among the study population. Poor working postures, feeling pressure due to work, long duration of work without breaks and prolonged daily working hours were positively associated with musculoskeletal symptoms.     

Micromolar determination of sulfur oxoanions and sulfide at a renewable sol-gel carbon ceramic electrode modified with nickel powder

The sol-gel technique was used to fabricate nickel powder carbon composite electrode (CCE). The nickel powder successfully used to deposit NiO_x thin film on conductive carbon ceramic electrode for large surface area catalytic application. Repetitive cycling in potential range −0.2 to 1.0 V was used to form of a thin nickel oxide film on the surface carbon composite electrode. The thin film exhibits an excellent electro-catalytic activity for oxidation of SO₃²⁻, S₂O₄²⁻, S₂O₃²⁻, S₄O₆²⁻ and S²⁻ in alkaline pH range 10-14. Optimum pH values for detection of all sulfur derivatives is 13 and catalytic rate constants are in range 2.4 × 10³-8.9 × 10³ M⁻¹ s⁻¹. The hydrodynamic amperometry at rotating modified CCE at constant potential versus reference electrode was used for detection of sulfur derivatives. Under optimized conditions the calibration plots are linear in the concentration range 10 μM-15 mM and detection limit 1.2-34 μM and 0.53-7.58 nA/μM (sensitivity) for electrode surface area 0.0314 cm². The nickel powder doped modified carbon ceramic electrode shows good reproducibility, a short response time (2.0 s), remarkable long term stability, less expense, simplicity of preparation, good chemical and mechanical stability, and especially good surface renewability by simple mechanical polishing and repetitive potential cycling. This sensor can be used into the design of a simple and cheap chromatographic amperometry detector for analysis of sulfur derivatives.     

Bioactive Carboxymethyl Starch-Based Hydrogels Decorated with CuO Nanoparticles: Antioxidant and Antimicrobial Properties and Accelerated Wound Healing In Vivo

In this study, nanocomposite hydrogels composed of sodium carboxymethylated starch (CMS)-containing CuO nanoparticles (CMS@CuO) were synthesized and used as experimental wound healing materials. The hydrogels were fabricated by a solution-casting technique using citric acid as a crosslinking agent. They were characterized by Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) to evaluate their physicochemical properties. In addition, swelling, antibacterial activities, antioxidant activities, cytotoxicity, and in vivo wound healing were investigated to evaluate the wound healing potential of the CMS@CuO nanocomposite hydrogels. Growth inhibition of the Gram-positive and Gram-negative pathogens, antioxidant activity, and swelling were observed in the CMS@CuO nanocomposite hydrogels containing 2 wt.% and 4 wt.% CuO nanoparticles. The hydrogel containing 2 wt.% CuO nanoparticles displayed low toxicity to human fibroblasts and exhibited good biocompatibility. Wounds created in rats and treated with the CMS@2%CuO nanocomposite hydrogel healed within 13 days, whereas wounds were still present when treated for the same time-period with CMS only. The impact of antibacterial and antioxidant activities on accelerating wound healing could be ascribed to the antibacterial and antioxidant activities of the nanocomposite hydrogel. Incorporation of CuO nanoparticles in the hydrogel improved its antibacterial properties, antioxidant activity, and degree of swelling. The present nanocomposite hydrogel has the potential to be used clinically as a novel wound healing material.     

Floodplain Inundation Analysis Combined with Contingent Valuation: Implications for Sustainable Flood Risk Management

This study presents the results of open-ended contingent valuation method (CVM) to estimate the residents’ maximum willingness to pay (WTP) for flood insurance and structural flood control measures in the Neka River Basin in Northern Iran. Flood inundation analysis and floodplain risk mapping were conducted by applying the HEC-RAS model combined with GIS analysis. A calibrated 100-year flood risk inundation map was considered as a basis for this research. This paper demonstrates applicability of CVM combined with flood inundation analysis to understand public participation for flood risk management, and their perception of flooding, considering associated socioeconomic and environmental factors. The results have shown that stated WTPs significantly varies with household income, distance people live from the river and the land use type of properties. Findings of this study suggest that the majority of respondents view flood hazard as the most important natural disaster. Furthermore, WTPs are significantly higher for those who have high level of flood risk perception. Three policy options for flood risk management are discussed, which include flood zoning and land use regulation, flood insurance program, and structural measure of levee construction. The advantages and disadvantages of each option are explored. It was concluded that a combination of possible mitigation options should be considered in order to achieve sustainable flood risk management in the Neka River Floodplain.     

Numerical Simulation of Droplet Impact on Patterned Surfaces

This work presents numerical simulation results for molten nickel and zirconia (YZS) droplets impacting on different microscale-patterned surfaces of silicon. The numerical simulation clearly showed the effect of surface roughness and solidification on the shape of the final splat, as well as the pore creation beneath the sprayed material. Simulations were performed using computational fluid dynamic software, SimDrop. The code uses a three-dimensional finite-difference algorithm solving the full Navier-Stokes equation, including heat transfer and phase change. A volume of fluid (VOF) tracking algorithm is used to track the droplet-free surface. Thermal contact resistance at the droplet-substrate interface is also included in the model. Specific attention is paid to the simulation of droplet impact under plasma spraying conditions. Droplet sizes ranged from 15 to 60 microns with initial velocities of 70-250 m/s. Substrate surfaces were patterned with regular arrays of cubes 1-3 μm high, spaced either 1 μm or 5 μm from each other. Different splat morphologies produced by simulations are compared with those obtained from the experiment conducted under the same impact and surface conditions. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.