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The Effect of Copper Oxide Nanoparticles on the Thermal Behavior of Silica Aerogel/Paraffin as a Phase Change Material in a Cylindrical Channel With Molecular Dynamics Simulation
No full textSawaran Singh, Narinderjit Singh/0000-0001-7067-5239; Atiah, Younis M./0000-0003-2861-6643The thermal conductivity of phase change materials was substantially enhanced by nanoparticles, improving the overall performance of thermal energy storage systems through more efficient heat transfer during the phase change process. This study investigates the effect of varying amounts of copper oxide nanoparticles on the thermal behavior of silica aerogel/paraffin as a phase change material in a cylindrical channel. LAMMPS and molecular dynamics simulations were employed to analyze this using a computer program. Results show that the atomic sample density and velocity reached 0.1393 & Aring;3 and 0.0119 & Aring;/fs, respectively, with the addition of 5% nanoparticles to the target structure. The atomic samples also reached a maximum temperature of 635 K when 5% of nanoparticles were added. The heat flux and thermal conductivity increased from 66.43 W/m2 and 1.74 W/m center dot K to 71.25 W/m2 and 1.82 W/m center dot K with a CuO-NP concentration increase of 3%. Adding nanoparticles enhanced thermal conduction, improving the overall interaction between the PCM and the nanoparticles. This led to better thermal contact and reduced thermal resistance at interfaces. However, adding more nanoparticles may lead to agglomeration, where the nanoparticles cluster together instead of remaining evenly dispersed. This can negatively affect thermal properties, as agglomerated particles create larger voids in the material, reducing the effective contact area for heat transfer. Using molecular dynamics simulations provided valuable insights into optimizing nanoparticle concentration for improved thermal performance in energy storage applications.Science Citation Index Expande
Evaluating the Effects of Different Polishing Methods on Color Stability of Dental Restorations in Pediatric Dentistry
No full textThe aim of this study was to evaluate the impact of various polishing methods on the color stability of compomer and composite resin restorations used in anterior restorations within pediatric dentistry. One hundred and twenty disc-shaped specimens (8 mm diameter x 4 mm thickness) were prepared from A2 shade compomer and nanohybrid composite resin to assess color stability in four different polishing systems. Sixty specimens from each material were randomly distributed into five groups (n = 12) according to the polishing method used. Group 1: four-step aluminum oxide discs, Group 2: aluminum oxide discs and rubber kit, Group 3: aluminum oxide discs and felt discs, Group 4: aluminum oxide discs and spiral wheels, and Group 5: no polishing. The specimens were immersed in cherry juice solution for 7 days. The color changes (Delta E) for all materials were assessed using a spectrophotometer at baseline and after 7 days of staining. The collected data were analyzed with the Shapiro-Wilk test, along with the Mann-Whitney U test for comparing two independent groups and the Kruskal-Wallis test for comparing three or more independent groups. Post hoc Bonferroni Corrections were applied to identify the groups causing the differences. As a result of the analyses, statistically significant differences were determined between the staining measurements of the compomer and composite materials across the groups (p < 0.05). The highest level of discoloration for the compomer was in the control group. In conclusion, the selected polishing method influences the degree of discoloration in the compomer groups. In the composite group, polishing methods showed variable effects. Differences were found between the compomer and composite groups. Understanding these effects is crucial for maintaining the esthetic longevity of restorations in young patients.Science Citation Index Expande
Ag and Al2o3/Water Two-Phase Transient Flow Analysis in a Double-Pipe Heat Exchanger Equipped With Baffles and Rotating Inner Tube
No full textConsidering the wide application of double-pipe heat exchanger made their performance improvement very important. Employing aqueous nanofluid (NF) of Ag and Al2O3 as the working fluid inside the inner tube of the heat exchanger and its rotation as the respective passive and active enhancing methods are investigated numerically using the two-phase mixture method. The sensitivity analysis was performed to reveal the effect of Reynolds (Re) number, NF concentration and tube rotational speeds on heat transfer coefficient, heat transfer effectiveness, and efficiency ratio. The Re number, NF concentration, and rotation speed lie in 1000-3000, 0–4 %, and 300–500 rpm, respectively. The results show the higher improving effect of Ag rather than Al2O3 nanoparticle; for Re = 1000, 1500 and 2000 the efficiency ratio averaged between different concentrations are 39 %, 30 %, 20 % for Al2O3/water and 62 %, 65 % and 26 % for Ag/water NFs, respectively. By increasing the Re number, the enhancing effect of velocity increment on heat transfer rate prevails and hinders that of employing NF. Also, in rotating mode, the enhancement made by increasing the Re number is higher in the rotation speed of 500 rather than 300 rpm. The overall change of efficiency ratio versus the Re number increment is decreasing and the greatest improving effect of using NF is for the lowest Re numbers. Also, the enhancement due to increasing the Re number increment is higher at a rotational speed of 500 rather than 300 rpm. © 2025 The Author
Exploring the Potential of Solar Photovoltaic and Wind-Based Green Hydrogen Projects in ECOWAS Region: Production, Cost, and Environmental Maps
No full textThe transition to clean energy demands innovative low-carbon hydrogen production solutions, particularly in developing nations. This study explores the prospect of green hydrogen production in the Economic Community of West African States (ECOWAS) using solar photovoltaic (PV) and wind power technologies. The region, endowed with massive renewable energy resources, continues to face challenges in developing economically viable and low-carbon hydrogen production strategies. The study fills this gap by developing a comprehensive methodology combining renewable energy production, electrolysis, and economic analysis. The study examines the viability of hydrogen production in 15 West African countries according to primary indicators such as electricity production, density of hydrogen production, levelized cost of hydrogen, and reduction of carbon dioxide emission. This novel method offers a detailed geospatial and techno-economic analysis of green hydrogen production, revealing stark variations in production costs and green hydrogen potential for West African countries. The study revealed Niger, Mali, and Cape Verde to have great potential for green hydrogen development due to high renewable energy resources and low production costs. This study provides policymakers and investors with a critical roadmap based on the potential of green hydrogen as a low-carbon energy solution in West Africa. In addition, it presents a strategy for creating competitive, low-carbon hydrogen economies that can drive the energy transition and economic diversification based on the region's strengths and weaknesses. © 2025 Elsevier B.V., All rights reserved.Science Citation Index Expande
Thermal Behavior of Silica Aerogel-Paraffin Nanocomposites in a Nanochannel Under Varying Magnetic Fields: a Molecular Dynamics Study
No full textThe demand for efficient energy conservation methods is growing amid rising fuel costs and greenhouse gas emissions. Phase change materials are essential for thermal energy storage, and silica aerogels, when combined with these materials, are particularly effective for insulation. This study presented a novel analysis of how various magnetic field strengths (ranging from 0 to 0.5 T) affected the thermal behavior of a nanostructure composed of silica aerogel, paraffin, and CuO nanoparticles in a cylindrical tube. Using molecular dynamics simulations, we examined the magnetic field's effect on key thermal properties, including density, temperature, heat flux, thermal conductivity, and the charging and discharging times. Results indicate that increasing the magnetic field strength to 0.5 T led to a decrease in maximum density from 0.1385 to 0.1372 atoms/& Aring;3. Additionally, the maximum velocity increased to 0.0142 & Aring;/fs, while the maximum temperature and heat flux rose to 646 K and 72.13 W/m2, respectively. The observed charging and discharging times were 5.91 ns and 8.52 ns, with stronger magnetic fields expediting the charging phase. These findings offer valuable insights into optimizing thermal energy storage systems through magnetic field modulation.Science Citation Index Expande
The Effect of External Heat Flux and Atomic Defects on the Nano-Pumping Process of C20 Molecule Inside Carbon Nanotube Using Molecular Dynamics Method
No full textInnovative designs and models are essential for contemporary drug delivery systems to minimize adverse effects, maximize therapeutic efficacy, and enhance patient satisfaction. The use of cost-effective and biodegradable carbon structures has garnered significant interest in developing pharmaceutical carriers. This study utilized the molecular dynamics method to examine the nano-pumping efficacy of C20 molecules within a carbon nanotube (CNT) at various heat fluxes and atomic defects. Increasing the external heat flux enhanced the nano-pumping process, which was completed in the ideal nanotube after 7.15 ps. The atomic behavior of the fullerene sample improved with the application of thermal sources within the MD box, generating effective force. To investigate the impact of atomic defects on the nano-pumping process, ideal nanotubes were modified with defects in proportions of 1 %, 2 %, and 3 %. The computational outputs predicted that the nano-pumping process in the modeled system was optimized at a 1 % atomic defect ratio. When a 3 % atomic defect was introduced into the CNT sample, the nano-pumping process was completed in 9.64 picoseconds. The findings of this research using CNT-based systems are anticipated to pave the way for extraordinary developments in medicine and drug delivery.Science Citation Index Expande
Behavioral Addiction Treatment Centers in the Hospitals of Türkiye: a Web-Based Research
No full textThis study investigates the current landscape of behavioral addiction treatment in Türkiye hospitals, considering both inpatient and outpatient approaches. The analysis involved examining the websites of 1393 hospitals across Türkiye based on various criteria. The review of the websites was conducted between June and September 2023. The findings reveal that out of these hospitals, comprising 822 public and 571 private institutions, only 51 provide treatment for behavioral addictions. Behavioral addiction treatments are available in 23 of the 81 provinces in Türkiye, and 24 out of the 51 hospitals offering treatment for behavioral addictions are located in İstanbul (47.1%), while three (5.9%) are located in Ankara. Among these 51 hospitals, 22 are public, and 29 are private. The primary focus of treatment revolves around internet and gambling addiction. Upon analyzing the patient groups served, it was observed that 49% (n = 25) of the hospitals specialize in treating adult patients, while 29.4% (n = 15) cater to pediatric patients. While the websites of 11 hospitals contain information about the behavioral addiction treatments offered, they lack any information on the patient groups to which they cater. The predominant treatment modalities include psychotherapy (25.49%), followed by psychopharmacotherapy (19.61%) and cognitive-behavioral therapy (17.65%). In conclusion, the treatment of behavioral addictions, such as those related to the internet, gaming, and shopping, are offered in hospitals across various regions and age groups. Considering that only 3.7% of hospitals in Türkiye treat behavioral addictions, this type of treatment is not widespread. © The Author(s) 2024.Science Citation Index Expanded - Social Science Citation Inde
Relation Between Open Leadership and Techno-Stress in the Industrial Sector of Lebanon
No full textPurposeThe aim of this research is to assess whether open leadership can serve as a strategic approach to help in reducing technostress and improving employee well-being in the context of Lebanon's industrial sector.Design/methodology/approachA descriptive, quantitative approach was used, with data collected through a questionnaire distributed to 67 randomly selected white-collar employees from various industrial companies in Lebanon.FindingsThe analysis revealed a strong negative correlation between open leadership and technostress, with a particular emphasis on collaborative leadership. Regression analysis further confirmed that open leadership is a significant predictor of reduced technostress. These findings underscore the value of open leadership in creating a supportive work environment that enhances employee well-being and reduces the negative impacts of technology-related stress.Originality/valueThis research contributes to the limited body of literature on technostress within Lebanon's industrial sector. It offers practical recommendations for leaders seeking to manage digital stressors through open leadership, highlighting its potential as a universally applicable leadership style in technology-driven workplaces.Emerging Sources Citation Inde
Üniversite Öğrencilerinde Siber Mağduriyet ile Öznel İyi Oluş Arasındaki İlişkide Öz Şefkatin Aracı Rolü
No full textBu çalışmanın amacı, üniversite öğrencilerinde siber mağduriyet ile öznel iyi oluş arasındaki ilişkide öz şefkatin aracı rolünün incelenmesidir. Bu araştırmanın katılımcıları uygun örnekleme yöntemi ile seçilen yaşları 18-35 arasında değişen 393 üniversite öğrencisinden oluşmaktadır. Araştırma verileri Sosyodemografik Bilgi Formu, Siber Mağduriyet Ölçeği, Öznel İyi Oluş Ölçeği ve Öz-Anlayış Ölçeği kullanılarak elde edilmiştir. Araştırma kapsamında toplanan veriler SPSS 26.0 paket programı kullanılarak analiz edilmiştir. Verilerin normal dağıldığı tespit edildikten sonra katılımcıların siber mağduriyet, öznel iyi oluş ve öz şefkat düzeylerinin demografik değişkenlere göre farklılaşıp farklılaşmadığını belirlemek için bağımsız gruplar t testi ve tek yönlü varyans analizi kullanılmıştır. Değişkenler arasındaki ilişki analizinde Pearson Korelasyon analizi ve aracılık modelini test etmek için Process Macro programı kullanılmıştır. Araştırmanın bulgularına göre, siber mağduriyet ile öznel iyi oluş arasında negatif yönde anlamlı bir ilişki olduğu bulunmuştur. Siber mağduriyet ile öz şefkat arasındaki ilişki istatistiksel olarak anlamlı değildir. Öznel iyi oluş ile öz şefkat arasında ise güçlü ve pozitif yönde bir ilişki olduğu bulunmuştur. Yapılan aracılık analizi sonuçlarına göre, siber mağduriyet ile öznel iyi oluş arasındaki ilişkide öz şefkatin aracılık rolünün istatistiksel olarak anlamlı olmadığı sonucuna ulaşılmıştır. Siber mağduriyet ve öz şefkat puanları, cinsiyete ve yaş gruplarına göre anlamlı farklılıklar göstermiştir. Öğrenim durumuna göre, siber mağduriyet ve öznel iyi oluş puanları anlamlı bir şekilde farklılaşmıştır. Araştırmadan elde edilen sonuçlar mevcut literatür kapsamında değerlendirilerek tartışılmıştır.The aim of this study is to examine the mediating role of self-compassion in the relationship between cyber victimization and subjective well-being in university students. The participants of this study consisted of 393 university students aged between 18-35, who were selected using convenience sampling method. Research data were obtained using the Sociodemographic Information Form, Cyber Victimization Scale, Subjective Well-Being Scale and Self-Compassion Scale. The data collected within the scope of the research were analyzed using SPSS 26.0 package program. After confirming that the data were normally distributed, independent groups t-test and one-way analysis of variance were used to determine whether cyber victimization, subjective well-being and self-compassion levels of the participants differed according to demographic variables. Pearson Correlation analysis was used to analyze the relationship between variables and Process Macro program was used to test the mediation model. According to the findings of the study, there was a significant negative relationship between cyber victimization and subjective well-being. The relationship between cyber victimization and self-compassion was not statistically significant. There was a strong and positive relationship between subjective well-being and self-compassion. According to the results of the mediation analysis, it was concluded that the mediating role of self-compassion in the relationship between cyber victimization and subjective well-being was not statistically significant. Cyber victimization and self-compassion scores showed significant differences according to gender and age groups. Cyber victimization and subjective well-being scores differed significantly according to educational status. The results obtained from the research were discussed within the scope of the existing literature
The Atomic and Thermal Performance of CuO Nanoparticles/Paraffin as Phase Change Materials in a Circular Tube: Molecular Dynamics Simulation Approach
No full textBackground: Using molecular dynamics simulation, this study investigates the effect of CuO nanoparticle addition on the thermodynamic and atomic properties of an octadecane that was being utilized as a phase change material within a circular tube. Methods: The results indicate that the density (D) was greatest in the vicinity of the tube walls. At its peak, D was 0.0300 atoms per square centimeter. This behavior is due to the increased attractive force that is between the structure's boundaries and its particles. Particle velocity (V) values reached their utmost attainable values in the intermediate regions of the tube, where movement was greatest. At its peak, V was 0.0078 Å/fs. The tube exhibits a maximum temperature (Max T) value of 754.43 K at its midpoint. Significant Findings: Due to the increased particle motion in the intermediate regions, the investigated structure experienced a greater number of collisions in those areas. After 10 ns, the sample's heat flux, thermal conductivity, and thermal stability converged to values of 3.94 W/m2, 1.38 W/mK, and 1821 K, respectively. The structure showed charging and discharging times of 6.41 and 7.15 ns, respectively. © 2025 Elsevier B.V