Tübitak National Metrology Institute

The correct identification of the knee joint line is essential for successful primary and revision total knee arthroplasty (TKA). Small misalignments can cause restricted range of motion, patellofemoral maltracking, and extensor mechanism imbalance leading to pain and functional impairment. This study aimed to evaluate the reliability of five radiographic anatomical landmarks - the fibular head, inferior patellar pole, tibial tubercle, and both femoral epicondyles - for estimating the joint line level in healthy Turkish adults. A retrospective radiographic analysis was conducted on 100 healthy adults (61 male, 39 female; 18-50 years). Perpendicular distances from these five bony landmarks to the joint line were measured digitally by two independent observers using a PACS system under standardized calibration to minimize projection errors. Inter-observer reliability was assessed by the intraclass correlation coefficient (ICC). Power analysis was based on the fibular-head-joint-line (FH-JL) distance as the primary outcome measure. The FH-JL distance measured 11.4 ± 1.8mm with a coefficient of variation of 15.8%, showing the highest reliability. Sex-based differences were significant (11.8mm in men vs. 10.7mm in women, p = 0.002). ICC values for all measurements ranged from 0.91 to 0.96, indicating excellent agreement between observers. No age-related differences were found (p = 0.835). The fibular head showed strong correlations with both epicondyles (r = 0.724 and r = 0.689). In healthy adults, the fibular head serves as a reliable radiologic landmark that may assist in joint line restoration during revision TKA, pending validation in clinical settings. The study also acknowledges its limitations of using plain radiographs and excluding the adductor tubercle as a reference point.

The paper presents the results of the influence of SiC dopant, annealing temperature, and annealing time on the morphology of MgB2 material in superconducting wires. The results of measurements of critical temperature (Tc), irreversible magnetic field (Birr), resistance in the normal state (Rn), and transport critical current density (Jct) at the temperature range from 15 K to 30 K are presented. The MgB2 material is characterized by the presence of two specific regions. The first region with high density, excess Mg, and rectangular MgB2 grains is located outside the voids surrounding them. The second region occurs inside the ceramic core, away from voids, and its chemical composition corresponds to a stoichiometric Mg to B ratio (1:2), and it is characterized by the presence of spherical grains and lower material density. A higher amount of SiC admixtures (6 at.%) causes an increase in the first region surface area. This kind of structure observation in MgB2 superconducting wires has never been reported previously. The transport measurements showed that higher SiC dopant leads to lower Jct at higher temperatures and high magnetic fields. The studies showed that the point-dominant mechanism and the first region allow for obtaining high Jct at 30 K.

We aimed to investigate the changes in renal aquaporins (AQP) of rats in renal ischemia-reperfusion (I/R) injury and the protective effects of caffeic acid phenethyl ester (CAPE) against these changes. Forty-five adult rats were divided into six groups: control, sham (right nephrectomy), I/R (right nephrectomy + left kidney I/R), I/R+CAPE (I/R procedure after i.p. CAPE), sham + CAPE, and sham + dimethyl sulfoxide. Blood urea nitrogen, Cr, and K+ levels were measured in the sera. Tissues were stained with hematoxylin and eosin for histopathological examination. For immunohistochemical analysis, AQP2 was applied using the streptavidin/biotin/peroxidase system. AQP2 gene expression in kidney tissues was examined by polymerase chain reaction (PCR). In the I/R, congestion, inflammation, and necrosis were found to increase compared to the control. In the I/R+CAPE, improvement was observed in necrosis compared to the I/R. There was a decrease in AQP2 expression in the I/R. In PCR, no significant difference was observed in AQP2 gene expression between the I/R and control and between the I/R+CAPE and I/R. Renal I/R inhibits the production of AQP2 in the kidney and causes histological and biochemical damage. CAPE administration before I/R has a protective effect on the kidney.

In this study, an aeroelastic smart structure exhibiting regular vibrations induced by vortex shedding was developed. Two types of beam elements—straight and auxetic—were fabricated using additive manufacturing techniques. The structure incorporates beam elements along with a flow-disturbing geometry designed to induce galloping behavior. The damping and stiffness properties of the fabricated beams were determined experimentally. Additionally, the natural frequencies of the structure were identified through free, forced, and modal vibration tests and validated by comparing the results with numerical simulations. Piezoelectric actuators made from the same material were bonded to both beam types and used to suppress vibrations through a feedback control loop. Displacement feedback for the control system was provided by a laser displacement sensor measuring the vibrations of the aeroelastic structure. To induce continuous vibrations, an external aerodynamic load was applied using a centrifugal fan. A proportional–integral–derivative controller was then designed and implemented to control the vibrations. Vibration control experiments were conducted for both beam types, with and without control activated. Displacement of the beams and the control voltages applied to the actuators were recorded as functions of time. When examining the control experiment results, the control effort used to suppress the vibrations of the straight beam is higher compared to the auxetic beam. This is consistent with the results obtained from the mechanical properties, free vibration responses, damping factor, and natural frequency values derived from the experiments. The experimental results highlight the influence of varying beam stiffness on the effectiveness of vibration control.

In recent years, visual deep learning-based methods have achieved significant successes in medical analysis, particularly producing successful results in disease detection using visual data. Although current CNN-based approaches offer high performance in disease detection, they fall short in providing understandable and accessible explanations related to the diagnosed diseases. To address this deficiency, this study proposes a two-stage framework that integrates automatic eye disease detection with an information retrieval-based question-answering system.In the first stage, a multi-label classification task is performed on retinal images to detect eight eye diseases. For this purpose, various advanced Convolutional Neural Network (CNN) architectures have been evaluated. In the second stage, a Retrieval-Augmented Generation (RAG) method, powered by GPT-4o, is employed to provide users with information about the detected diseases and answers to their questions.This approach combines high-accuracy CNN-based classification with a semantically rich RAG question-answering system, enabling both reliable detection of eye diseases and the delivery of meaningful, contextually appropriate explanations to end users. Comparisons and objective evaluations of both stages of the proposed framework have been conducted, leading to the conclusion that the system is applicable in real-world settings.

By examining the navigation records on websites that contain large amounts of information, it is possible to extract information from visitors' navigation on these sites that can facilitate users' access to the information they are looking for. One way to make sense of navigation data is to test assumptions about users' navigation. In this way, users' navigation behavior can be better understood, and the way can be opened to increase the accessibility performance of the site and, accordingly, to improve the user experience.In this study, an application was carried out to compare hypotheses regarding category-based web navigation with the Bayesian approach. The results obtained from the navigation data of the Gebze Technical University homepage showed that the site's navigation is not hierarchical; visitors generally reach the targeted area directly or in a single step and remain in that region.

The conversion of the waste of wet silica sand sludge (W3S) into useful products, such as bricks, glassware, and ceramics, is an alternative solid waste management method. The aim of this study is to determine the effect of silica sand wet sludge additive on brick quality. For this purpose, laboratory-scale brick manufacturing was implemented by using 10%, 30%, 50%, and 100% sludge in clay brick. For proper characterization to understand brick quality, the water absorption, shrinkage, bulk density, compressive strength, and SEM analysis of sintered samples were performed. At the end of the experimental procedure, no negative effects of sludge addition were determined in terms of mechanical strength, porosity, water absorption, or structural integrity. In addition, the incorporation of W3S contributed to sustainable waste management and helped mitigate its environmental impact. Experimental studies revealed that a product with the desired color could be obtained when 50% W3S was used in the mixture. In addition, the optimal composition for making bricks was found to be a mixture of 50% W3S and 50% brick clay, fired at 850 °C. With this mixture, not only is the preferred color achieved, but an optimum balance between mechanical strength, durability, and minimization of environmental damage is also attained. Such a formulation ensures high compressive strength, low porosity, and low water absorption, making it sustainable and a better choice in construction with industrial by-product use. The results obtained are useful in showing possibilities for the solution of environmental problems to utilize waste materials in useful products.

Monoelemental calibration solutions are the most common reference in elemental analysis, linking measurement results to the International System of Units (SI). National Metrology Institutes (NMI) prepare these solutions as certified reference materials (CRM) and determine their elemental mass fraction with high accuracy. Characterization with high accuracy is one of the most critical steps in CRM production. This report compares the approaches taken by the NMIs of Türkiye (TÜBİTAK-UME) and Colombia (INM(CO)) in preparing and characterizing cadmium calibration solutions with a nominal value of 1 g kg−1. Each NMI produced CRMs using an independent batch of cadmium calibration solution and assigned mass fraction values to both their own solutions and those of the other NMIs. TÜBİTAK-UME employed a primary difference method (PDM) to assess the purity of a cadmium metal standard, quantifying all possible impurities using a combination of instrumental analytical techniques. The defined purity standard was used for both the gravimetric preparation of the CRM and the calibration of high-performance inductively coupled plasma optical emission spectrometry (ICP-OES) measurements. On the other hand, INM(CO) used gravimetric titration with EDTA to assay cadmium in the CRM solutions. The EDTA salt was previously characterized by titrimetry. Despite the fundamentally different measurement methods and independent metrological traceability paths to the SI, the measurement results exhibited excellent agreement within the stated uncertainties. This comparative analysis demonstrates the effectiveness of varied characterization approaches and underscores the reliability of the cadmium calibration solutions prepared by TÜBİTAK-UME and INM(CO). This collaborative effort highlights the reliability and adaptability of various measurement techniques in fulfilling rigorous metrological standards for elemental calibration solutions. Furthermore, this approach enhances the robustness of the measurements in the field of elemental analysis and contributes traceability to the SI.Graphical