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An investigation into the use of 3d printing technology for geogrids
No full textThree-dimensional (3D) printers with large-scale printing capabilities may enable engineers to print their geogrids, which would be especially useful at outlying construction sites where acquiring geogrid can be challenging or expensive. Nevertheless, for 3D geogrids to be used effectively for geotechnical applications like mechanically stabilised earth walls (MSE walls) or ground improvement, they must be able to interlock with soils in a manner similar to factory-made geogrids. The aim of this study is to comprehensively investigate the interlocking mechanisms of 3D-printed geogrids with different soils by comparing them with factory-made geogrids. To achieve this, tensile tests were conducted to determine the tensile characteristics of the 3D-printed geogrids produced in the study. In addition, large-scale direct shear tests were performed by placing 3D geogrids with soils of different grain roundness values. All test results were presented by comparing them with the test results conducted on factory-made geogrids with properties similar to the 3D-printed geogrids. The 3D-printed geogrid improved the soil shear strength; however, it was found to be more brittle and provided less interlock with soils than the factory-made geogrid. These results suggest that the production method of the geogrid was a significant factor
Staged-construction shrinkage in high-rise reinforced concrete buildings
No full textShrinkage-induced vertical shortening in reinforced concrete (RC) columns and shear walls of high-rise buildings was investigated through staged-construction analyses using the fib Model Code 1990 implemented in two structural analysis programs. As a baseline reference, representative shortening under typical conditions (relative humidity (RH) of about 70%) for a 50-storey building is about 33 mm in columns and 30 mm in shear walls. In this study, parameter variations included RH (40-90%), building height (30, 40 and 50 storeys), concrete strength (C70/85, C60/75 and C50/60) and slab thickness (250, 300 and 350 mm). Lowering the RH from 90% to 40% increased the maximum shortening by approximate to 44% in columns and approximate to 49% in shear walls, while increasing the number of storeys from 30 to 50 increased mid-height column shortening by roughly 30%. The use of higher strength concrete (C70/85) reduced the maximum shortening by up to 18% and thicker slabs reduce it by approximate to 12% in columns and approximate to 9% in shear walls through enhanced diaphragm stiffness. Shortening was found to be concentrated in the upper-middle floors, and evolves rapidly during the early years, underscoring the need for staged analysis. Unlike previous studies, this work provides quantified parametric relationships that can support design applications. The findings offer practical guidance for serviceability assessment, fa & ccedil;ade alignment and construction-tolerance planning in tall RC buildings
Comparison of stress protein (hsp70) levels in the brain and hypopharyngeal glands, morphology of malpighian tubules, and behavioral traits in honeybees fed on different patties
No full textHoneybees (Apis mellifera) play a crucial role in agricultural productivity and the sustainability of ecosystems. However, environmental stressors and insufficient nutrition can adversely affect the health and colony resilience of these important insects. This study investigated the effects of different protein substitute patties on honeybees' physiological and behavioral responses. The research evaluated levels of the HSP70 stress protein in the bees' brain tissues, HSP70 immunohistochemical staining in hypopharyngeal glands (to assess tissue-specific stress localization), Malpighian tubule diameters, and aggression scores. Statistically significant differences were observed among groups. Patty consumption levels and gut weights also varied significantly. Patties containing spirulina (Patty II) were associated with beneficial effects on Malpighian tubule length and stress protein levels, whereas patties containing active fresh yeast (Patty V) induced elevated HSP70 levels, potentially signifying metabolic stress. Increased aggression levels were observed in groups fed with type II and type III patties. In contrast, the control group, fed natural pollen, displayed low HSP70 levels and balanced aggression scores. These findings highlight that protein substitute patties on honeybee health and colony performance are relatively multifaceted and that patties ought to be optimized considering palatability, bioavailability, and physiological effects. Our study provides valuable insights for the improvement of bee nutrition strategies and the enhancement of their resistance against environmental stressors
Eeg/meg-based biomarkers of cognitive training effects in schizophrenia: A systematic review
No full textThis systematic review aims to evaluate the effects of cognitive training methods on brain electrical activity in patients with schizophrenia, focusing on studies published between January 2010 and October 2025 in the PubMed and Web of Science databases. Twenty experimental and quasi-experimental studies were included in the study, examining various cognitive training methods, including auditory, visual, emotional, and social skills training. These studies measured Electroencephalography (EEG) and Magnetoencephalography (MEG) metrics, including oscillations, mismatch negativity (MMN), and event-related potentials (ERPs), to assess changes in neural activity associated with schizophrenia. Findings demonstrate that different cognitive training methods may improve neural oscillations, particularly in the gamma and alpha bands, and may enhance cognitive functions such as working memory, attention, and emotional regulation. While some studies have shown limited effects on specific EEG and MEG indices, the overall evidence suggests that personalized cognitive interventions can promote neuroplasticity and cognitive recovery in individuals with schizophrenia. These findings show the potential of integrating EEG/MEG-based biomarkers into clinical practices to enhance the effect of treatment and improve neural outcomes for schizophrenia patients
The evaluation of the dielectric responses of zinc ferrite/copper oxide nanocomposites by impedance spectroscopy analysis
No full textImproving the dielectric properties of zinc ferrite-based nanocomposites is of great interest for their potential use in advanced electronic and energy storage applications. In this study, zinc ferrite nanoparticles were synthesized by the hydrothermal method, and composites were prepared by incorporating 5%, 10%, and 15% CuO nano-particles. Structural analysis confirmed the cubic spinel structure of the ferrites and copper oxide incorporation into the matrix. The dielectric properties exhibited Maxwell-Wagner type interfacial polarization, consistent with Koop's theory. Copper oxide additives were found to significantly enhance the complex dielectric components of the zinc ferrite nanocomposites. The conduction mechanism was also analyzed through AC conductivity measurements. In light of these results, CuO incorporation improved the dielectric performance of zinc ferrite-based nanocomposites, highlighting their potential for use in energy storage devices and other room temperature electronic applications.Yildiz Technical University
FYL-2024-608
Environmental fate of pcdd/fs: Atmospheric concentrations, seasonal trends, exchanges in different environments, risk assessment and source identification
No full textThis study evaluated atmospheric gas- and particle-phase levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), including 17 individual congeners and the sum of tetra to octachloro homologues. The investigation was conducted across urban, semi-rural, and wastewater-treatment-plant-impacted areas in Bursa, T & uuml;rkiye. The annual mean concentration of Sigma 17PCDD/F in the gas phase was determined to be 82.27 f 11.97 fg/ m3, whereas the corresponding value for the particle phase was 327.53 f 130.44 fg/m3, resulting in a total concentration of 409.80 f 133.09 fg/m3. The corresponding toxic equivalent (TEQ) level was 30.30 f 5.11 fg TEQ/m3 (range: 22.58-39.21 fg TEQ/m3). Approximately 78 % of the Sigma 17PCDD/F concentrations were associated with the particulate phase, and this proportion increased further during winter due to elevated emissions and reduced atmospheric dispersion. Using the measured atmospheric data, theoretically estimated equilibrium concentrations were calculated for soil, leaves, tree bark, and water media. It was observed that highly chlorinated congeners predominated in these environments, with an increased tendency for accumulation, particularly during colder periods. Predictions of particulate-phase concentrations using a KOA-based equilibrium model were consistent with measured data for 2,3,7,8-TCDF; 2,3,7,8-TCDD; and 1,2,3,4,6,7,8-HpCDD; however, notable deviations were observed for highly chlorinated congeners. Principal Component Analysis (PCA) revealed four distinct source groups explaining 79.02 % of the total variance, highlighting waste incineration, vehicular emissions, industrial production, and biomass combustion as the predominant contributors. Inhalation-based risk assessments showed that daily intake doses were below the WHO-recommended thresholds, and the estimated cancer risks remained lower than the 10-6 benchmark level
Analysis of an internal heat exchanger (ihx) for vehicle air conditioning systems
No full textIn this study, an internal heat exchanger (IHX) was tested with R1234yf refrigerant according to data collected from a vehicle and then modeled one-dimensionally (1D) using Amesim software. The simulation results were verified with the test results, and the usability of R290 refrigerant in the same IHX was investigated with the model. Due to the higher enthalpy of R290, the desired performance was expected to be achieved with a shorter IHX, and the study was extended to include different IHX configurations. Therefore, the design of experiment (DoE) was created using the Taguchi-L16 orthogonal array, considering four IHX parameters at two levels. The Amesim model was run for 16 combinations, and the heat transfer provided by the IHX was calculated. Applying the signal-to-noise (S/N) analysis, the optimal design configuration was determined based on the larger-the-better performance criterion. Subsequently, the variance analysis (ANOVA) was performed to obtain the contribution ratios of each parameter to the heat transfer performance of the IHX. Finally, regression analysis was applied to develop analytical equations for predicting heat transfer as a function of the parameters. The heat transfer values calculated with the equations were compared with the simulation results, and a good agreement was obtained between them
Schema retrieval with embeddings and vector stores using retrieval-augmented generation and llm-based sql query generation
No full textIn today's world, where the volume and variety of data are increasing at an extraordinary rate, extracting meaningful insights from data is of critical importance; however, the complexity of standard database query languages makes it difficult for users without technical expertise to access information. This study proposes an innovative Retrieval-Augmented Generation (RAG) architecture that analyzes natural language queries, identifies related database schemas, and automatically converts them to SQL. Unlike fixed schema selection (fixed-k) methods, a unique hierarchical clustering mechanism is introduced to dynamically determine the number of relevant schemas, minimizing noise. Furthermore, the architecture incorporates an iterative repair mechanism, data enrichment with sample rows, and a hybrid query strategy (Turkish + English) to overcome cross-lingual barriers. Performance evaluations on 15 databases demonstrate that the proposed method improved the schema retrieval F1 score from 0.79 to 0.88. In the SQL generation phase, the execution accuracy (EX) of the GPT-4o model increased from 0.70 to 0.78 with the proposed optimizations, representing an approximate 11% improvement relative to the baseline configuration without requiring fine-tuning.Bilimsel Araştırma Projeleri Birimi, İstanbul Teknik Üniversitesi FGA-2026-253
Prognostic value of the ratio of globally sclerotic glomeruli in patients with idiopathic iga nephropathy
No full textIgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. We assessed whether the Ratio of Globally Sclerotic Glomeruli (RoGSG) on diagnostic biopsy predicts subsequent kidney outcomes in a nationwide, multi-center registry. Among 326 adults with idiopathic IgAN (mean age 39.1 +/- 12.8 years; 60.1% male), 43 patients (13.2%) met a 5 year composite outcome defined as any of: doubling of serum creatinine or >= 50% decline in eGFR from baseline, eGFR = 28.86% versus 1.2% with RoGSG < 28.86% reached the composite outcome. In multivariable models adjusted for clinical and pathologic covariates, high RoGSG, grade 2 tubular atrophy/interstitial fibrosis, and non-response to initial immunosuppression were independent predictors of adverse outcomes. The prognostic association of RoGSG persisted in key subgroups, including those with nephrotic syndrome and those with initial treatment response. These findings support RoGSG as a readily available histopathologic marker that may improve risk stratification in IgAN; however, prospective studies and external validation in independent cohorts are required before any clinical adoption.Turkish Society of Nephrolog
Experimental and machine learning investigation of a solar air heater with a novel compact thermal absorber design
No full textThis study presents the development and evaluation of a novel and sustainable solar air heater (SAH) incorporating an enhanced compact heat-absorbing structure made from recycled aluminum radiator fins, designed to improve thermal and exergetic-performance while promoting material-reuse and sustainability. The reuse of waste radiator materials provides a multilayered-fin configuration that increases the effective heat-transfer surface area, enhances turbulence, and reduces overall heat loss without additional manufacturing cost. A comparative methodology was employed to assess the influence of this compact thermal-storage element on SAH performance under typical Autumn and Spring conditions. The baseline and modified SAH models were evaluated using dimensionless performance parameters and validated through experimental testing. The average thermal-efficiency of the baseline system was 64.81 %, while the compact heat-exchanger-integrated system reached 78.54 %, indicating a significant improvement of about 13.7 percentage points (21 % relative increase). Furthermore, the oriented-configuration (ochxSAH) provided an additional 3.23 percentage points improvement, corresponding to a further 4 % performance gain. The heat loss rate for chxSAH increase 5.9 % that accompanied a much larger rise in useful heat-gain, confirming improved energy utilization efficiency. These gains were achieved through the improved energy-saving capacity of the recycled radiator-based absorber and its ability to maintain higher outlet temperatures. To complement the experimental study, a machine-learning (ML) approach was applied to predict SAH efficiency. The ML results validated the superior thermal and exergy performance of the sustainable SAH design, demonstrating that integrating waste-material-based compact heat exchangers can enhance system efficiency while supporting circular-economy principles in solar-thermal technologies