Arak University

Accurate core-scale thermal–hydraulic prediction underpins safety margin evaluation, DNBR assessment, and PWR licensing, yet full rod-level CFD of an entire VVER-1000 core is computationally prohibitive, and prior porous-media full-core studies have often left closure coefficients and convergence criteria only partially specified. This study presents a steady-state CFD model of a VVER-1000 (V-320) core, coupling a fully specified anisotropic porous-media formulation for the 163 fuel assemblies with the RANS equations and the realizable k–ε model, at 15.7 MPa, 291.4 °C inlet, and 17,880 kg/s flow (3000 MWth). A four-level mesh study (4.2–24.3 million cells) and a Grid Convergence Index analysis (GCI_fine = 0.31 %) established numerical reliability. The predicted outlet temperature (320.5 °C) and pressure drop (135.9 kPa) agreed with plant design data within 2.18 %, and the sub-model was independently validated against coolant-mixing and pressure-drop benchmark data (deviation < 0.71 %), with a combined outlet-temperature uncertainty of ±1.88 %. This reproducible closure framework and quantified uncertainty budget distinguish the present work from earlier, less transparently documented porous-media CFD studies of VVER-1000 cores.

در این پژوهش، مدل‌سازی نیروی بحرانی منیپولیشن ذرات در فضای سه‌بعدی با استفاده از روش طراحی آزمایش‌ها موردبررسی قرار گرفته است. هدف اصلی، تحلیل تأثیر عوامل هندسی و کنترلی بر نیروی بحرانی لازم جهت منیپولیشن ذره با استفاده از میکروسکوپ نیروی اتمی (AFM) بود. پنج پارامتر کلیدی شامل شعاع ذره، ضخامت تیرک، طول تیرک، عرض تیرک و ارتفاع سوزن به‌عنوان متغیرهای ورودی انتخاب شدند و نیروهای بحرانی در راستاهای X و Y به‌عنوان پاسخ‌های خروجی مورد مدل‌سازی و تحلیل قرار گرفتند. با اجرای ۲۷ آزمایش طراحی‌شده و تحلیل آماری نتایج حاصل از مدل‌ رگرسیونی استخراج شده، مشخص شد که پارامترهای ضخامت تیرک و شعاع ذره بیشترین تأثیر را در افزایش نیروی بحرانی منیپولیشن دارند، درحالی‌که افزایش طول تیرک و ارتفاع سوزن منجر به کاهش این نیرو می‌شود. بررسی نمودارهای سه‌بعدی نشان داد که تأثیر متقابل پارامترها بر نیروی بحرانی قابل‌توجه بوده و عملکرد نهایی منیپولیشن به ترکیب مناسب ویژگی‌های هندسی و فیزیکی وابسته است. همچنین، تحلیل باقیمانده‌ها، توزیع نرمال خطا و دقت بالای مدل (R² > 99%) را تأیید کرد. نتایج این تحقیق می‌تواند به‌عنوان مبنایی برای طراحی و توسعه بهینه ابزارهای منیپولیشن مورداستفاده قرار گیرد.

Given the widespread use of caffeine among athletes, this meta-analysis quantifies the incidence of acute side effects associated with caffeine supplementation. Despite its well-established performance benefits, evidence on caffeine’s side effects remains fragmented, as these outcomes are often reported only as secondary findings. To address this gap, we systematically reviewed and meta-analyzed evidence from randomized controlled trials on acute caffeine-related side effects in athletes. Following PRISMA guidelines, we searched five databases (MEDLINE, Scopus, Web of Science, Embase, Google Scholar) up to July 2025. Eligible studies were randomized controlled trials in athletes aged ≥ 15 years examining acute caffeine ingestion versus placebo with reported side effects. Risk of bias was assessed using PEDro and Cochrane criteria. Data on frequency and magnitude of side effects were pooled using random-effects meta-analyses, with subgroup and dose–response analyses. A total of 48 studies (940 athletes; 63

Various techniques are used to introduce new cultivars, especially in ornamental species like tuberose, which have limited genetic diversity. This study employed a completely randomized design with three replications to investigate the effects of different mutagens on mutation induction in tuberose bulbs. The mutagens tested included sodium azide at concentrations of 200, 300, and 400 mg L−1, ethyl methanesulfonate at 0.25, 0.5, and 0.75 mg L−1, and gamma rays at doses of 10, 20, and 30 Gy. After exposure to the mutagens, both mother and daughter bulbs were grown for two consecutive years under greenhouse conditions. Our results indicated an increase in the number of florets in bulbs treated with sodium azide, regardless of the concentration used. The largest floret diameter, measuring 47.82 mm, was recorded in samples treated with ethyl methanesulfonate at a concentration of 0.5 mg L−1. This same concentration also resulted in an increase in the reducing sugar content within the petals. The longest vase life, recorded at 8.66 days, was observed in samples exposed to gamma radiation at a dose of 10 Gy. Significant changes in enzymatic antioxidants were noted in bulbs treated with the different mutagens, both before and after harvest. In conclusion, all three mutagens had an influence on the growth of tuberose plants, affecting various morphological, physiological, and postharvest parameters.

In this paper, we report a green synthesis of MgZnFe2O4@ZSC-Ag with a cheap and clean method. Ag ion was immolized on surface of MgZnFe2O4 modified with Ziziphus spina-christi extract (ZSC). The MNPs was thoroughly analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field emission-scanning electron microscopy (FE-SEM), Energy dispersive X-ray analyzer (EDS), Inductively coupled plasma-optical emission spectrometry (ICP-OES), Thermogravimetric (TGA), and Vibrating sample magnetometry (VSM) techniques. The catalytic activity of MgZnFe2O4@ZSC-M (M: Ag, Cu) was evaluated in the reduction of nitrophenols to aminophenols in the presence of NaBH4. The process of reduction of nitrophenols to aminophenols was determined using UV-Vis spectroscopy. The rate constant (K) calculated for 3-nitrophenol (1.25 s(-1)g(-1) (MgZnFe2O4@ZSC-Ag), 1.37 s(-1)g(-1) (MgZnFe2O4@ZSC-Cu) and 4-nitrophenol (0.58 s(-1)g(-1) (MgZnFe2O4@ZSC-Ag), 0.52 s(-1)g(-1) (MgZnFe2O4@ZSC-Cu). These catalysts offer several advantages, including easy separation using a magnet, short reaction times, suitable yield of products and the ability to reuse the catalyst for up to 15 runs. Also, the antibacterial activity of MgZnFe2O4@ZSC-M (M: Ag, Cu) was evaluated against gram positive and gram negative bacteria. MgZnFe2O4@ZSC-Ag inhibited an inhibition zone 8, 10 mm for E.coli bacteria and S.aureus bacteria, respectively. This was higher than the inhibition zone for MgZnFe2O4@ZSC-Cu (6 mm for both bacteria), MgZnFe2O4@ZSC (6 mm for both bacteria). Also, the minimum inhibitory concentration (MIC) value for MNPs showed that MgZnFe2O4@ZSC-Ag provided better results against S.aureus bacteria (16 mu g/L) compared to MgZnFe2O4@ZSC-Cu, MgZnFe2O4@ZSC MNPs.