DSpace @ Recep Tayyip Erdoğan Üniversitesi Akademik Açık Arşiv
Not a member yet
12203 research outputs found
Sort by
Nonlinear phase and group velocity analyses of hybrid nanocomposite-reinforced sports stadium roofs under aerodynamic pressures
No full textThe nonlinear performance of a hybrid nanocomposite-stadium roof in terms of group and phase velocity under aerodynamic pressure is being studied in this paper. The composite material is an epoxy matrix that is reinforced with graphene nanoplatelets (GNP) and carbon nanotubes (CNT) in a blend, thus having improved mechanical properties overall. The study uses the sinusoidal shear deformation theory, including a nonlinear shear function, and also Von Kármán’s geometric nonlinear effects are included. Based on Hamilton’s principle, the governing equations are derived, and the aerodynamic pressure is considered to be constant using the first-order piston theory. A notable aspect of the model is the auxetic foundation made of a Haber–Schaim foundation material, and these properties will have a major impact on the overall dynamic characteristics of the system. The harmonic method of balancing the problem’s geometry is also applied to nonlinear equations. An awesome iterative method is given for precise nonlinear phase and group velocity solutions. The results imply that the combination of a hybrid nanocomposite and an auxetic base influences the dynamic response of the roof system greatly. The roof’s nonlinear phase and group velocities display this intricacy, and the strengthening of the material and foundation markedly influences them. This study brings about a new direction for the design and analysis of future stadium roofs and also offers a firm basis for dynamically optimizing the performance under wind load. The results are of particular significance for the development of structural systems with nanocomposite reinforcements that are always exposed to aerodynamic forces
Identification of urinary incontinence prevalence, risk factors, awareness and attitude levels in turkish women: single center cross-sectional study
No full textUrinary incontinence (UI) is a prevalent health issue worldwide, with its frequency increasing with age and negatively impacting individuals across various aspects of life. This study aims to determine the prevalence of UI, identify risk factors, and assess awareness and attitudes in women aged 18–65. This research, conducted as a descriptive and cross-sectional case study, was conducted with 294 randomly selected women working in a hospital in a province of Turkey. Data was collected using face-to-face interviews using the Introductory Information Form and the Urinary Incontinence Awareness and Attitude Scale (URINAS). UI was found in 29% of women aged 18–65. Among those with UI, 34% consulted a physician, and 22% received treatment. Factors influencing UI include age, BMI, vaginal delivery, menopause, family history, having constipation, lifting heavy objects, urinary tract infections, and a desire for Kegel exercise training (p < 0.05). Approximately one-third of women aged 18–65 experience UI. However, only one-third of those seek medical advice and one-fifth receive treatment. Factors that affect UI include age, body mass index, vaginal delivery, menopause, urinary tract infections, heavy lifting, and doing kegel exercises. Women generally accepted UI as a health issue, had high health motivation, did not experience significant restrictions, and displayed moderate levels of coping and fear
Novel azo-substituted metallophthalocyanines (M: Co, Ni, Cu, Zn) bearing hydroxy, carbonyl, and methoxy groups: Synthesis and evaluation as pre-catalysts for the transfer hydrogenation of aldehydes and ketones
No full textIn this study, four novel metallophthalocyanine (MPc) compounds derived from phthalonitrile ligands incorporating o-vanillin were synthesized, characterized, and evaluated as pre-catalysts in the acetophenone and benzaldehyde transfer hydrogenation (TH) reactions. The molecular structures of the complexes were confirmed by FTIR and UV–Visible spectroscopy and elemental analysis. Among the complexes, copper phthalocyanine compound (5) exhibited the highest catalytic efficiency, promoting the acetophenone and benzaldehyde transfer hydrogenation reactions in propan-2-ol under inert conditions, and the corresponding alcohols have a 98 % conversion rate within 1 h (A1) and 99 % conversion within 6 h (K1). The results show that both the electronic effects of substituents on the phthalonitrile ligands and the central metal nature play key roles in determining the catalytic performance of the MPc complexes in TH reactions
Enhancing the structural integrity of sport stadium roof panels using nano-reinforced composites and machine learning techniques
No full textThe rising demand for strong lightweight materials which can withstand test of time has resulted in using nano-reinforced composite materials for roof panel systems which protect current sports stadiums against intense dynamic forces. The researchers created an analytical-computational framework which enhances stadium roof panel strength through graphene platelet-reinforced composite materials and deep neural network verification which functions as an advanced machine learning method. The roof system is modeled as a doubly curved graphene platelet-reinforced composite panel exposed to dynamic loading conditions that simulate wind gusts and seismic excitations. The effective material properties of the nano-reinforced composite are evaluated by incorporating the contribution of graphene platelets within the polymeric matrix. The panel's structural behavior operates under first-order shear deformation theory which defines transverse shear deformation through a specific shear correction factor. The researchers use energy principles to derive governing equations of motion which they solve analytically using Navier's solution technique that employs double trigonometric series expansions. The Laplace transform handles analytical work for dynamic system behavior through its ability to evaluate transient response which needs its inverse transformation to be solved using a modified Dubner and Abate numerical method. The research confirms roof panel dynamic response through deep neural network training which uses analytical method datasets to produce fast computational results. The research findings demonstrate that analytical methods and machine learning approaches generate identical results which confirm the system's accuracy. The results deliver important information which assists in designing nano-reinforced stadium roof panels that provide superior stability and strength, and vibration control performance
The worldwide prevalence of radix molaris in mandibular second molars assessed by cone beam computed tomography: systematic review and meta-analysis
No full textIntroduction: This study aimed to investigate the worldwide prevalence of radix entomolaris (RE) and paramolaris (RP) in mandibular second molars via cone beam computed tomography.
Methods: The electronic databases MEDLINE, Web of Science, Scopus, and Embase were searched using related MeSH keywords. In vivo cone-beam computed tomography-based studies that evaluated the prevalence of RE and RP in mandibular second molars were retrieved and assessed. The included studies were quantitatively analyzed via a meta-analysis to determine the pooled prevalence rates of RE and RP. Furthermore, the studies were qualitatively assessed using the Newcastle‒Ottawa quality assessment scale.
Results: Twenty-six studies were eligible for this review and a meta-analysis of 21,383 mandibular second molars was performed. All the studies involved were ranked as high quality with no evidence of publication bias. The global prevalence of RE was 0.72% (95% confidence interval: 0.45% to 1.04%) and that of RP was 0.17% (95% confidence interval: 0.004% to 0.36%). Sex and geographical location did not significantly influence RE or RP incidence.
Conclusion: The prevalence of radix molaris is not infrequent. The incidence of RE is higher than that of RP, and neither sex nor country influences the incidence rate of either presentation
Evaluation of protein profile in vitreous samples of patients with naive age-related macular degeneration using proteomic approaches (vol 25, 1019, 2025)
No full text..
Diclofenac-Copper(II) complex and Kigelia pinnata-derived Ag/Mn nanocomposites: Synthesis, characterization, molecular docking and comparative antibacterial activity
No full textThe development of new antimicrobial agents remains important in the context of drug-resistant infections. In this study, a diclofenac-based copper (II) complex was synthesized and characterized using liquid chromatography–mass spectrometry (LC–MS) and ultraviolet–visible (UV–Vis) spectroscopy, and its antibacterial activity was compared with two green-synthesized nanocomposites prepared from Kigelia pinnata extracts. Molecular docking indicated interactions between the diclofenac–Cu (II) complex and bacterial nutrient-sensing proteins, including PfkB kinases as well as Staphylococcus ECF transporters. Antimicrobial activity was assessed using agar well diffusion and minimum inhibitory concentration (MIC) assays against Escherichia coli and Staphylococcus vitulinus. The silver nanocomposite (AgNC) produced the widest inhibition zones (approximately 20–24 mm) and showed the lowest MIC values (≤ 15.63/µg/mL for S. vitulinus and 62.5 µg/mL for E. coli). The manganese nanocomposite (MnNC) demonstrated moderate activity, with MIC values of 31.25 µg/mL for E. coli and 62.5 µg/mL for S. vitulinus. The diclofenac–Cu (II) complex was active only against Gram-positive bacteria, producing inhibition zones of 10–12 mm and an MIC of 256 µg/mL. Overall, AgNCs showed the strongest activity against both test organisms, MnNCs displayed intermediate inhibition, and the diclofenac–Cu (II) complex remained selectively active against Gram-positive strains
Recent advancements in perovskite thin film technology: From solar cells to optoelectronic devices
No full textPerovskite thin film (PTF) technology is a rapidly developing field that has made significant strides, leading to breakthroughs in many applications. In this way, PTFs are widely acknowledged for their remarkable optoelectronic characteristics, which have been instrumental in advancing perovskite solar cells (PSCs), photodetectors (PDs), light-emitting diodes (LEDs), and memory devices. This review first comprehensively introduces PTFs production from lab-scale to large-scale, then addresses the challenges of PTFs and discusses ways to overcome these challenges. Moreover, this review combines significant discoveries from current studies to clarify perovskite-based solar cells’ improved scalability, stability, and efficiency. Additionally, the use of PTFs in developing technologies-such as memory devices, LEDs, and PDs-is discussed, highlighting their role in improving the functionality and performance of these devices. Furthermore, it explains the investigation of PTFs in specific applications, such as x-ray detection, imaging sensing, and polarized detection, highlighting their potential to push the limits of detection technologies. Finally, we discuss the challenges in implementing PTFs for optoelectronic device systems uses and provide our opinions on potential future projects and lines of inquiry
Frictional moving load-induced dynamic response of a porous piezoelectric micro/nano plate with superficial parabolic discontinuity
No full textFrictional moving load-induced dynamic response of a porous piezoelectric micro/nano plate with superficial parabolic discontinuity. The present paper aims to analyze the complex dynamic response of micro/nano-scale components through investigating the stress distribution within a Nonlocal Porous Piezoelectric Layer (NPPEL) of finite thickness. The study specifically focuses on quantifying the combined effects of material porosity, size-dependent elasticity, and geometrical surface imperfections when the layer is subjected to a load moving across its upper boundary. This comprehensive model provides a more realistic assessment of reliability for small-scale smart devices. The layer’s constitutive behavior is modeled using Eringen’s nonlocal elasticity theory to account for the essential size effects present at the micro/nano scale. The governing equations for the coupled porous and piezoelectric medium are derived, incorporating appropriate boundary conditions for a moving load. Crucially, the superficial parabolic discontinuity on the upper surface is handled analytically through a robust perturbation technique, allowing for the derivation of closed analytical forms for the resulting shear and normal stresses. The final solutions are then computed using Mathematica to illustrate the transient stress fields. Numerical results demonstrate that the nonlocal parameter is highly effective at amplifying the magnitude of the stresses, which is characteristic of the stiffening effect in nonlocal models. The depth and factor of the parabolic irregularity significantly amplify the stress concentrations at the interface, indicating a critical pathway for potential failure. Furthermore, the frictional coefficient of the moving load plays a non-linear role in dictating the shear stress distribution, providing crucial insight into contact mechanics at the nanoscale. The core novelty lies in the simultaneous analytical incorporation of nonlocal effects, porosity, and an arbitrary surface irregularity under dynamic moving load conditions–a combination highly relevant to microfabrication. The model is directly applicable to enhancing the design and performance assessment of MEMS/NEMS pressure sensors, ultra-thin piezoelectric energy harvesters, and other micro-electromechanical devices where surface quality and size effects dictate device lifespan and reliability
Multidimensional assessment of patient-reported-outcomes in a multicenter cohort of inborn errors of immunity
No full textPatient-reported outcomes are critical to multidisciplinary, patient-centred approaches in diseases requiring lifelong management. Among inborn errors of immunity (IEIs), reports on this subject are typically limited to specific diagnostic subgroups or focus narrowly on the route of immunoglobulin replacement therapy (IgRT), offering a restricted perspective. We aimed to evaluate the health-related quality of life (HRQoL) and IgRT-related treatment satisfaction (TS) of a heterogeneous cohort of IEI patients and identify factors influencing these outcomes to guide improving the health and well-being of IEI patients. We conducted a cross-sectional survey targeting IEI patients on IgRT, assessing TS (TSQM-9) and HRQoL (KINDL/SF-36). Patient/caregiver-reported data were integrated with clinical data to identify outcomes and influencing factors. The survey included 500 IEI patients (356 children, 144 adults) diagnosed 54% Primary Antibody Deficiency (PAD), 36% combined immunodeficiency, 7% immune-dysregulation, and 3% other IEIs. Non-PAD diagnoses, comorbidities, absence of school/work attendance, and IgRT-related systemic adverse reactions negatively impacted HRQoL. Severe infections and related hospitalizations adversely influenced both HRQoL and TS. The subcutaneous route of IgRT, particularly at home, was associated with higher TS due to its convenience and reduced school/work absenteeism. However, the IgRT route did not influence adult HRQoL. Patient-reported well-being and satisfaction in IEIs are multifactorial and cannot be solely attributed to the route of IgRT. Minimizing negative experiences related to the disease or its treatment and, where possible, encouraging patients to maintain school/work attendance or engage in activities that promote societal participation can enhance self-esteem, coping abilities, and overall well-being