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Synthesis and Characterizations of DOPO Substituted Polyesters
No full textGrowing environmental and health concerns regarding the use of halogenated flame retardants have led to an increased interest in phosphorus-based alternatives, which are recognized for their environmentally friendly properties. In this study, phosphorus-functional monomers, obtained via phospho-Michael addition of DOPO to unsaturated compounds such as maleic anhydride and itaconic acid, were incorporated into polyester matrices to impart intrinsic flame retardancy through covalent integration into the polymeric network. The influence of terephthalic acid on the thermal behavior of these polyesters is also explored. A range of analytical techniques are employed to inform the study, including 1H and 31P NMR spectroscopy, FTIR, viscosity evaluation, and inductively coupled plasma optical emission spectrometry (ICP-OES). Thermogravimetric analysis in combination with evolved gas analysis is used to assess thermal stability in both nitrogen and air environments. Furthermore, microscale combustion calorimetry is employed to examine flammability characteristics. For cone calorimetry tests, polyester samples are applied onto glass fibers to evaluate their flame-retardant efficacy, smoke generation, and overall fire safety performance
Optimizing mandibular second molar mesialization: A comparative analysis of stress distribution and displacement using tie-back and temporary skeletal anchorage device-assisted mechanisms with a nonlinear finite element model
No full textIntroduction: This study aimed to determine the optimal approach for mandibular second molar (M2M) mesialization in mandibular first molar extraction patients under 3 distinct scenarios—corticotomy-assisted or nonassisted—by evaluating 2 mesialization techniques (temporary skeletal anchorage device [TSAD]) supported coil spring and tie-back). The finite element method was used to compare stress distribution and displacement patterns. Methods: Six models were designed to simulate M2M mesialization. In the first 3 models (hook models), the force was applied using posted arches with tie-backs to the M2M hook. In the final 3 models (TSAD models), a force was applied using a TSAD placed between the canine and premolar teeth, employing power arms extending from the M2M with closed-coil springs targeting the molar's center of resistance. The tie-back and power arm mechanism was tested and compared alone (models I-IV), with mesial incision (models II-V) and circumferential incision (models III and VI). Both decreasing (200, 100, and 50 g) and continuous (200 g) forces were used along 3 s/steps. In the nonlinear analysis, the total and directional displacement (along the x-, y-, and z-axes) and von Mises stress values were measured. Results: TSAD models exhibited greater tooth displacement across all 3 axes with crown and roots translated mesially while showing minimal distal tipping (2.27° × 10−2 to 2.63° × 10−2). In addition, these models demonstrated greater lingual rotation and more pronounced extrusion on the mesial side. In contrast, hook models primarily exhibited mesial tilting rather than uniform mesial translation, with approximately 7-fold less overall extrusion and half the amount of lingual rotation compared with TSAD models. Piezocision failed to accelerate tooth displacements in both models. TSAD models generated slightly higher stress on the molar tooth and alveolar socket. In TSAD models, mesial and circumferential incisions reduced miniscrew stress by nearly half. Conclusions: TSAD mechanics enabled greater mesial translation with minimal distal tipping, whereas hook models exhibited more mesial tilting but reduced overall extrusion and rotation. TSAD models showed greater alveolar bone stress response. Circumferential incisions with TSAD anchorage minimized unwanted movements and alveolar bone stress response. Given the inherent limitations of the finite element method in fully replicating clinical outcomes, these findings should be interpreted with caution and validated through clinical studies
Dust, truck, sand, breath, buffaloes, milk, excavation, mine, sea, grass, yoghurt...
No full textI have been reflecting on the ecological crises confronting our planet, focusing on northern Istanbul, where I live amidst large-scale mega-projects. These include a new shipping canal parallel to the Bosphorus, the Istanbul Airport, and the North Marmara Highway, all of which disrupt local communities, traditional water buffalo grazing lands, and sensitive ecosystems while accelerating the city’s northward expansion. Living between these projects, I encounter at least 20 excavation trucks daily. Inspired by Jane Hutton’s (2019) concept of reciprocal landscapes, which highlights the territorial consequences of material extraction and transportation, I decided to follow an excavation truck one day, uncertain of what I might discover.As an architect ‘living in the end times’ (Žižek, 2010), I interrogate my position through a subjective, situated, by-design methodology. My research focuses on an architectural essay film, portraying architecture as a malevolent character exploiting resources under the guise of progress and glamour. The film employs essayistic making as creative research to shape its narrative using three modes of recording: from inside a car in inaccessible geographies for woman and queer bodies, on foot where cars cannot proceed, and collectively walking to explore water buffalo habitats and their intertwined relationships with the land.Intuitive and experiential, my research and filmmaking seek to question how we engage with our environment, how we repair and maintain it, and how we might live together with trouble (Haraway, 2016). Through this lens, my work explores entanglements between humans and non-humans, inviting reflection on co-existence within reciprocal and exhausted landscapes.</p
Seasonal distribution and removal efficiency of microplastics in landfill leachate treatment plants in Istanbul, Turkiye
No full textDue to inadequate management, plastic waste accumulates in landfills and transforms into microplastics (MPs), which concentrate in leachate and pose risks to ecosystems and human health. This study examines the seasonal variation, size, type, and removability of MPs in leachate from the Kömürcüoda (LTP-1) and Odayeri (LTP-2) landfill leachate treatment plants in Istanbul. Seasonal samples from raw leachate (RL), membrane bioreactor (MBR), ultrafiltration (UF), nanofiltration (NF), and nanofiltration concentrate (NFC) units were analyzed in spring and autumn. The highest MP concentrations were found in MBR units, with 29 particles/L in autumn and 11 particles/L in spring at LTP-1. In LTP-2, MP concentrations in anoxic and aerobic units were 20 and 24 particles/L in autumn and 17 and 26 particles/L in spring. Significant MP reduction was observed in UF and NF outlets, with an MP removal efficiency of approximately 97 % between RL and NF units at both sites. The predominant MPs were blue, black, and transparent fibers, ranging from 500 to 1999 µm in autumn and 1000 to >2000 µm in spring. Polymeric analysis identified polyamide (PA) as the most prevalent material at LTP-1 (42 %), followed by polypropylene (PP) and polyisoprene (PI), while at LTP-2, PP was dominant (46 %), followed by polyethylene (PE), PI, and PA. Despite high removal efficiencies, daily MP release after treatment was estimated at 5 × 10⁵ and 13 × 10⁵ particles for LTP-1 and LTP-2, respectively, indicating continued MP discharge. The high number of MPs detected in untreated landfill leachate, along with their persistence even after treatment processes, highlights the potential accumulation and toxicity risks posed by MPs released into aquatic ecosystems. Further research should focus on understanding the long-term environmental behaviour of these pollutants in receiving environments, as well as on improving advanced treatment technologies for MP removal
New FOPID Control Design for Flight Dynamics With Special Phenomena
No full textThe design of a flight control system (FCS) for aircraft altitude change dynamics presents significant challenges due to the inherent non-minimum phase (NMP) behavior. This behavior leads to undesirable initial undershoot responses, imposing significant limitations on internal stability and severely restricting the performance and robustness of directly applying conventional control methods. Despite the widespread use of proportional–integral–derivative (PID) controllers in industrial applications, their robustness, performance, and disturbance rejection deteriorate when applied to systems exhibiting NMP characteristics. This paper highlights the practical importance of upgrading PID-based controllers for flight dynamics with NMP behavior by addressing these challenges, with a particular focus on tracking and stability issues under direct feedback control. To overcome these limitations, we propose a modified control architecture incorporating a fractional-order PID (FOPID) controller, augmented with a fractional-order derivative filtering component (FD). This design aims to enhance transient response, noise immunity, and adaptability without adding significant complexity. The control problem is framed as a single-objective optimization task, where the Particle Swarm Optimization (PSO) algorithm is used to simultaneously tune the proposed controller gains, minimizing the error between the actual and desired altitude commands. The performance of the proposed controller was compared to traditional PID and FOPID controllers through both time and frequency domain analyses, under scenarios involving parametric uncertainty and 50% and 80% loss of effectiveness in the actuator (elevator) fault. The performance evaluation was based on transient response criteria, while robustness was assessed in terms of delay, phase, and gain margins. The simulation results show that under nominal flight conditions, the proposed controller significantly outperforms conventional FOPID controllers, reducing the percent overshoot from 52% to 2% for the Integral Absolute Error (IAE), from 44% to 2% for the Integral Time Squared Error (ITSE), and from 60% to 3% for the Integral Time Absolute Error (ITAE) performance metrics. The robustness analysis reveals that even under extreme conditions, such as system uncertainties, 50% and 80% actuator loss, the proposed controller maintains stability. Across these cases, it achieves a minimum phase margin of 158° and a gain margin of 13.3 dB, in contrast to the 27.8° and 16.4 dB observed with conventional controllers. These findings underscore the controller's efficacy in providing reliable and robust altitude control in real-world flight conditions, even under significant actuator degradation and system uncertainties
Advancing Geopolymer Mortars with Recycled Concrete Aggregates Through Electrical Curing
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Prognostic Value of Non-Traditional Lipid Indices for In-Hospital Mortality in Patients with Acute Coronary Syndromes
No full textBackground and Objectives: Acute coronary syndrome (ACS) is a life-threatening cardiovascular condition with high mortality rates, necessitating accurate and early risk assessment to optimize patient outcomes. While traditional lipid markers, such as low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol (HDL-C), are widely used, non-traditional lipid indices, including the lipoprotein combined index (LCI), atherogenic index of plasma (AIP), atherogenic index (AI), Castelli risk indices (CRI-I, CRI-II), and atherogenic combined index (ACI) may offer additional prognostic insights by reflecting the underlying atherogenic and inflammatory processes. This study aimed to assess the prognostic value of these non-traditional lipid indices, along with traditional lipid and biochemical markers, for in-hospital mortality in ACS patients. Materials and Methods: This retrospective observational study analyzed data from ACS patients admitted to the coronary care unit (CCU) between January 2019 and September 2024. A cohort of 920 patients was divided into survivor (n = 823, 89.46%) and non-survivor (n = 97, 10.54%) groups based on in-hospital mortality outcomes. Demographic, hematological, biochemical, and lipid profile data, including traditional and non-traditional lipid indices, were collected. Separate logistic regression models were developed for each index, adjusting for demographic and clinical variables in order to assess the independent predictive power of each non-traditional lipid index. Results: Significant differences were observed between survivor and non-survivor groups in terms of age, c-reactive protein (CRP), white blood cell count (WBC), hemoglobin (HGB), and creatinine levels (all p-values < 0.05). While traditional lipid markers, such as LDL-C and HDL-C, showed limited predictive value, non-traditional lipid indices demonstrated stronger associations. The highest Exp (Beta) values were observed for the CRI-II, AI, and CRI-I. An ROC analysis further confirmed that the CRI-II, AI, and CRI-I had the highest AUC values, with pairwise comparisons underscoring the CRI-II’s superior accuracy. These findings suggest that non-traditional lipid indices predict atherogenic risk better than traditional markers alone. Conclusions: Non-traditional lipid indices, particularly the CRI-I and II, AI, LCI, ACI, and AIP, were found to be significantly associated with in-hospital mortality in ACS patients. These indices may provide additional prognostic value beyond traditional lipid parameters; however, further prospective studies are needed to confirm their clinical utility. These results underscore the importance of integrating non-traditional lipid indices into routine risk assessments to improve mortality predictions and inform targeted interventions in high-risk ACS patients