Aperta Turkish Open Archive
Not a member yet
83692 research outputs found
Sort by
Realization of a wideband three-axis horizontal vibration isolator with adjustable stiffness and damping
No full text<p>Horizontal vibration isolators (HVIs) designed to be on the verge of elastic instability offer many opportunities for isolating a variety of vibration-sensitive instruments, such as atomic force microscopes and laser/optical systems from ambient excitations at very low frequencies (0.5 - 5 Hz). These HVI systems are designed to have very low natural frequencies and can achieve quasi-zero-stiffness (QZS) in the horizontal axes when they support payloads close to their maximum payload-carrying capacities. Payloads of different sizes and weights necessitate to have adjustable stiffness and damping to operate in very wide bandwidths. To address these issues, a QZS HVI using axially compressed elastic columns is designed, optimized and fabricated. The system has adjustable natural frequencies in three axes (two translational and one torsional) via a string tensioning mechanism. Besides, the system enables the torsional natural frequency to be adjusted independently of the two translational natural frequencies by means of novel column sliding mechanisms that can change the radial positions of the elastic columns from the center axis of the system. Amplitude-dependent damping and stiffness characteristics of this variable natural frequency system are determined under various axial preload conditions. The system also involves an adjustable eddy current damper to effectively suppress low frequency resonance peaks. Finally, a methodology is proposed to modify the ideally clamped boundary conditions of the elastic columns, resulting in very good agreement between the analytical, numerical, and experimental results. The results show that the proposed HVI can achieve bandwidths between 1.6 - 311 Hz in the translational axes and 0.7 - 311 Hz in the torsional axis for payloads between 0 - 45 kg, providing a very large isolation bandwidth in three axes for a wide range of payload masses.</p>
Advancing sustainable packaging through self-assembly induced amyloid fibrillization of soy and pea protein nanofilms
No full text<p>This study explored protein fibrillization and characterization, demonstrating significant enhancements in the structural, mechanical, and functional properties of soy and pea protein fibrils for biodegradable food packaging. The fibrillizationprocess increased /3-sheet alignment by 1.3-fold for soy protein fibrils (SPF) and 1.2-fold for pea protein fibrils (PPF). ThT fluorescence assays revealed higher /3-sheet alignment in SPF compared to PPF. Structural analysis showed flexible, worm-like fibrils in SPF and PPF. Mechanical tests indicated significant improvements: tensile strength increased to 4.88 MPa for SPF and 3.83 MPa for PPF films, with elongation at break reaching 221 % for SPF and 101.62 % for PPF films. Amyloid fibrillation reduced water solubility and water vapor permeability while increasing the swelling degree of protein films. Optical analysis revealed decreased lightness, intensified green and yellow hues, and increased transparency. These findings highlight the potential of amyloid fibrillation to enhance protein films for sustainable packaging applications.</p>
Development of a sensitive and simple method for the analysis of upadacitinib in biological samples using two different electrodes
No full text<p>This study explains the electrochemical application using a glassy carbon electrode (GCE) and boron-doped diamond electrode (BDDE) to determine upadacitinib (UPA), which is a selective inhibitor of Janus kinase 1 (JAK1) protein from the standard solution and serum sample. Electrochemical oxidation behavior was evaluated regarding pH and scan rate effect, and the oxidation mechanism was found to be a mixture of adsorption/diffusion for BDDE and diffusion-controlled for GCE. The possible oxidation mechanism was explained in detail using indole, zolmitriptan, ruxolitinib, and tofacitinib. UPA was determined using GCE and BDDE in pH 4.7 acetate buffer solution (ABS). The linear concentration range was 8.0 x 10-7 - 6.0 x 10-5 M for GCE and 4.0 x 10-6 - 6.0 x 10-5 M for BDDE in standard solution. The obtained limit of detection (LOD) values are 1.91 x 10-8 M and 3.69 x 10-8 M for GCE and BDDE, respectively. Furthermore, the feasibility and accuracy of both electrodes were demonstrated through commercial human serum sample application and recovery studies, and the recovery% value was between 100.76% and 102.96%. For the precision evaluation, the repeatability and reproducibility values for GCE were 0.96-1.36 (standard solution-serum) and 1.48-1.99 (standard solution-serum); for BDDE were 0.42-0.85 (standard solution-serum) and 1.13-1.37 (standard solution-serum), respectively. Compared to the literature, this study stands out as an easier, environmentally friendly, affordable, and sensitive electrochemical option for UPA determination using GCE and BDDE.</p>
Detection and Whole-Genome Analysis of tigecycline resistant<i> Escherichia</i><i> coli</i> in poultry and meat samples in Türkiye
No full text<p>The emergence and dissemination of tigecyline resistant Enterobacterales (TRE) in animals is a critical issue. This study aimed to investigate the presence of TRE in the gut of healthy avians as well as meat samples. A total of 940 ceacal samples from 94 commercial poultry flocks were collected at slaughter and a total of 335 meat samples [(chicken (n = 159), turkey (n = 4) and beef/lamb (n = 172)] were collected from supermarkets and butcher shops. Out of 960 samples, 146 (19.21 %) samples from chicken farms and 24 (13.3 %) from turkey farms were positive for TRE. Forty-nine Escherichia coli isolates were determined to carry the tet (X4) gene by PCR and exhibited multi-drug resistance. Whole-genome short-read sequencing (WGS) on all tet (X4) positive E. coli isolates and long-read sequencing on a selection of five isolates were carried out. WGS identified four ST types (ST206 being the most dominant, ST609, ST744 and ST189), indicating significant homogeneity among tigecyline resistant E. coli strains. In 47 isolates, the tet (X4) gene was transferrable to E. coli EC600 and it was found to be located on the IncX1 plasmid. Additionally, all tet (X4)-positive E. coli isolates also harbored other resistance genes, including floR, aadA2 and tet (A). In this study, the identification of tet (X4) carrying E. coli in healthy chicken and meats suggests the likely source of food-producing animals for humans. Therefore, active surveillance of critical priority lineages of TRE should focus on to contain the potential public health risk.</p>
Enhancing the performance of 3D-printed fiber-Reinforced mortar: synergistic effects of clays and bacterial cells as viscosity modifying agents
No full text<p>The absence of standardized 3D concrete printing mixtures drives ongoing material exploration. This study investigates mineral and bio-based viscosity modifying agents (VMAs) application in fiber-reinforced cementitious mortar. Nano-montmorillonite, sepiolite, and bacterial cells function as supplementary materials, partially substituting cement with fly ash for sustainability assessment and compatibility evaluation in our study. Mechanical tests encompass compressive, flexural strength, and interlayer bonding in 3D-printed samples. Based on the results, incorporating 0.150% Polyamide (PA) fiber positively affected interlayer bonding strength and deceleration of the flow loss rate. Additionally, adding clays decreased workability and compressive strength but improved interlayer bonding and flexural properties. On the other hand, substituting 20% of cement with FA improved the flowability of the mixture and showed great compatibility with other materials during printing. Applying a cement paste layer was evaluated as a practical method for bond enhancement at the interface. Bacteria incorporation improved flexural strength but weakened interlayer bonding. However, the combination of bacteria and clays resulted in a superior improvement in mechanical properties. This study demonstrates clays and bacteria's potential in enhancing rheological and mechanical features in cementitious fiber-reinforced mortar. Notably, this study introduces bacteria cells and sepiolite as rheology modifiers in 3D concrete printing for the first time. Additionally, it presents a novel dog-bone-shaped structure test for assessing interlayer bond performance.</p>
Relcovaptan: a promising therapeutic agent in traumatic spinal cord injury that acts by modulating newly identified transcriptional regulators of aquaporins compared to tolvaptan
No full text<p><strong>Background/aim:</strong> Every year, hundreds of thousands of people worldwide suffer from traumatic spinal cord injury (tSCI), which causes irreversible damage, edema, and inflammation. Despite its devastating impact, no safe and effective medication is available. Edema formation is one of the earliest pathological events in tSCI, beginning within minutes after injury. Cytotoxic edema progresses to vasogenic edema, exacerbating irreversible damage. Our study aimed to investigate a therapeutic approach targeting cytotoxic edema in the acute phase of tSCI to improve treatment outcomes. Aquaporins (AQPs) are crucial in edema formation and tSCI pathogenesis. Vasopressin, also known as the antidiuretic hormone, modulates <em>Aqp</em> expression and translocation by initiating cell signaling via vasopressin 1a receptor (V1aR) and vasopressin 2 receptor (V2R). We investigated the effects of 2 V1aR and V2R antagonists (relcovaptan and tolvaptan, respectively) on edema formation and <em>Aqp</em> expression in tSCI.</p>
<p><strong>Materials and methods:</strong> Transcriptome analysis was performed on male Sprague Dawley rats that were traumatized to determine the effect of relcovaptan and tolvaptan after tSCI. Gene set enrichment analysis and bioinformatics approaches identified critical genes and signaling pathways associated with the drug treatment.</p>
<p><strong>Results:</strong> According to our results, tolvaptan was not suitable for the treatment of tSCI. On the other hand, relcovaptan had multiple positive effects. These include not only the positive effect on edema, which is achieved by suppression of <em>Aqp1</em>, <em>Aqp4</em>, and <em>Aqp11</em> expression, but also immunoregulation, neuroprotection, neuroregeneration, and osmoregulation via activator protein-1 and galanin.</p>
<p><strong>Conclusion:</strong> Our study suggests that clinical application of relcovaptan may be a promising treatment option for improving tSCI.</p>
Water Insecurity
No full text<p>Water insecurity is a complex and universal problem resulting from many problems such as increasing population, climate change, pollution, and management-related problems. Since the problem is universal, the solutions to be sought should also proceed in this way. Our limited usable water resources are decreasing even more due to many reasons, such as changes in climate, urbanization, migration, deficiencies in management, and water scarcity situations. The effects of water insecurity are interconnected with each other. With water insecurity, which is vital among all living things and ecosystems, many diseases occur due to the inability to access clean water. In addition, production in agriculture will decrease and costs will increase significantly due to water scarcity. Thus, both the food industry and economic development activities will be disrupted. Migration movements will be seen since life cannot continue in areas without usable water. Serious socioeconomic problems will arise, especially in the regions that receive migration due to migration. International cooperation and global studies such as universal water laws are important steps that are effective in solving the problem of water insecurity. Improvements in infrastructure, raising public awareness, and natural methods such as afforestation are important solutions.</p>
HORIZON EUROPE RIA PROJECT - CULTURATI_Deliverable D4.8 Midway Dissemination Report
No full text<p>This report presents an overview of the communication and dissemination efforts carried out by all project partners at the midway point of the CULTURATI project. It includes a summary of activities such as social media outreach, public engagement, promotional materials, and other dissemination initiatives aimed at increasing the project's visibility and impact. The contributions from all partners highlight the collective efforts to engage stakeholders, share project developments, and foster wider awareness of CULTURATI’s objectives.</p>
Development of a mucoadhesive drug delivery system and its interaction with gastric cells
No full text<p>Drugs that are designed for local treatment of gastric diseases require increased gastric residence time for prolonged action and increased efficacy. In this study, we report a mucoadhesive drug delivery system that was developed to fulfill these requirements. Alginate nanoparticles were synthesized by water-in-oil emulsification followed by external gelation and then coated with the mucoadhesive polymer Eudragit RS100. The formulated nanoparticles had a mean size of 219 nm and positive charge. A peptide, as a model drug, was loaded onto the nanoparticles with an encapsulation efficiency of 58%. The release of the model drug from the delivery system was pH-independent and lasted for 7 days. The periodic acid–Schiff stain assay indicated 69% mucin interaction for the nanoparticles, which were also capable of diffusion through artificial mucus. The nanoparticles were not toxic to gastric epithelial cells and can be internalized by the cells within 4 h. The adsorption of nanoparticles onto mucus-secreting gastric cells was found to be correlated with cell number. The delivery system developed in this study is intended to be loaded with active therapeutic agents and has the potential to be used as an alternative drug delivery strategy for the treatment of gastric related diseases.</p>
City-company collaboration towards aligned science-based target setting
No full text<p>Cities and companies have great potential to reduce pressures on Earth system boundaries. Science-based target setting has emerged as a powerful tool to help achieve the potential, but its uptake has been limited. Moreover, cities and companies usually develop their targets separately, even though many are co-located. Focusing on the top 200 cities and 500 companies by greenhouse gas emissions, we analyse the current state and potential of adopting science-based targets for climate. Of these key actors, 110 cities with existing net-zero targets and 22 companies with existing science-based targets could together eliminate up to 3.41 GtCO2e of annual emissions. We argue that this reduction potential could increase by as much as 67% (to 5.70 GtCO2e) if the cities and companies that already have targets bring their co-located counterparts on board to keep abreast of their ambitions. Using freshwater as another example, we discuss entry points for addressing interrelated Earth system boundaries through city-company collaborations. Our findings elucidate previously untapped potentials that could accelerate transformations for operating within Earth system boundaries.</p>
<p>Many of the world's largest cities and leading companies have separately adopted targets for emissions and water-use reductions. This study examines how co-location and collaboration could enhance efforts to stay within Earth system boundaries.</p>