Hakim Sabzevari University

The limited availability of natural gas (NG) and its associated emissions raise concerns about meeting residential energy demand.This work investigates the feasibility of hydrogen blending (HB) in a specified urban NG network from energy, economic, and environmental perspectives.First, the impact of 1-20 % volumetric hydrogen blending on gas composition and thermophys. properties is analyzed.The TOPSIS decision-making method then determines the optimal HB percentage for cold and hot months.Finally, dynamic network parameters-including volumetric flow, energy contribution, hydrogen production power requirements, efficiencies, CO₂ emissions, and costs-are evaluated based on the optimal HB percentages.Results illustrated that optimal HB levels of 12 % in winter and 13 % in summer (totaling 23024 m³ of hydrogen annually) could save 7044 m³ of NG.This integration required 93.4 MWh of PEM electrolyzer power to supply 70 MWh of hydrogen energy to end users annually (4.34 % of the total natural gas demand), while reducing CO₂ emissions by 13 tons.However, economic anal. showed that annual expenses were four times higher than revenues, with grid electricity purchasing costs being the most significant expense.Finally, to deliver the blended natural gas with hydrogen to end users with the same energy content as pure NG, an addnl. 27.2 % annual cost was incurred, resulting in a levelized cost of energy (LCOE) of 54.7 $/MWh.

Thermoluminescence dosimeters (TLDs) are widely used for radiation dose measurement in various applications, including radiation protection, radiotherapy, and diagnostic radiology. Therefore, efforts to improve TLD response and reduce uncertainty in measurements are highly valuable. This study aims to evaluate the effect of adding silver (Ag) nanoparticles to LiF:Mg,Ti TLD in terms of their structural characteristics, thermoluminescence (TL) properties, and dosimetric performance. The TLD samples were first synthesized, and Ag nanoparticles were subsequently incorporated as a third impurity. Both prepared samples (with and without Ag nanoparticles) were irradiated with predefined dose levels of 6 MV photons and corresponding glow curves and dose-response curves were compared. XRD, FESEM, and EDS analyses confirmed the proper formation of the LiF TLD structure. The presence of Ag nanoparticles was verified without any alteration in the overall crystalline structure of LiF. The obtained elemental correction coefficient (ECC) values were close to unity, indicating a nearly uniform distribution of impurities in the LiF structure. TLD glow curve at the same dose level enhanced when Ag nanoparticles were added to the TLD. Furthermore, the dose-response curve improved in the presence of Ag nanoparticles. Based on the results, it can be concluded that incorporating Ag nanoparticles into LiF:Mg,Ti enhances its thermoluminescence response and sensitivity.

An enzyme-free photoelectrochemical (PEC) sensor with a simple structure and excellent stability was developed for the detection of ascorbic acid (AA). The sensing platform was constructed based on the in-situ preparation and deposition of a mesoporous BiVO₄ layer using an innovative technique. The sensor exhibited high selectivity, repeatability, and outstanding long-term stability, with a linear detection range of 0.5-430 μM and a detection limit of 0.13 μM. Notably, the sensor retained 93 % of its initial photocurrent after 90 reuse cycles over 90 days and 98 % of its photoactivity after 6 months of storage under ambient conditions, setting a benchmark performance among PEC sensors. The superior stability and sensing performance are attributed to the mesoporous electrode structure and strong adhesion of the BiVO₄ thin film to the substrate, facilitated by the unique deposition method, eliminating the need for further modifications or enzymatic additives.