IYTE GCRIS Database (Izmir Institute of Technology)
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A New Safe Flexible Torsion Joint Design With Softening Stiffness Characteristics
No full textThis paper introduces a novel flexible joint design that enhances mechanical versatility. The design shows how to obtain bidirectional deflections from a unidirectional spring. It enables the parallel and serial connections of springs. It features multiple stiffness regions determined by applied load levels, eliminating the need for a clutch mechanism. Mechanical limits can be added to customize stiffness, offering more hardening or softening regions. The design also allows for connecting multiple flexible joint units in series. In a case study, the series flexible joint design is developed with two flexible joint units, providing a softening stiffness characteristic. The joint has rigid, stiff, and soft regions. When used as a series elastic actuator in a robot manipulator, the rigid region aims to conduct the tasks at low torque levels, i.e., trajectory tracking. The stiff region is preserved for collaborative tasks in human-robot interaction, while the soft region enhances the robot's safety in case of control failure or collision. Static and dynamic test results comply with the ideal model. This flexible joint design improves mechanical performance, safety, and adaptability
Projectivity and Quasi-Projectivity With Respect To Epimorphisms To Simple Modules
No full textUsing the notion of relative max-projectivity, max-projectivity domain of a module is investigated. Such a domain includes the class of all modules whose maximal submodules are direct summands (this class denoted as MDMod -R). We call a module max-p-poor if its max-projectivity domain is exactly the class MDMod -R. We establish the existence of max-p-poor modules over any ring. Furthermore, we study commutative rings whose simple modules are projective or max-p-poor. Additionally, we determine the right Noetherian rings for which all right modules are projective or p-poor. Max-p-poor abelian groups are fully characterized and shown to coincide precisely with p-poor abelian groups. We also further investigate modules that are max-projective relative to themselves, which are known as simple-quasi-projective modules. Several properties of these modules are provided, and the structure of certain classes of simple-quasi-projective modules is determined over specific commutative rings including the ring of integers and valuation domains
Influence of the Heat Treatment on the Microstructure, Mechanical and High-Temperature Oxidation Behavior of Hastelloy X Alloy Fabricated Via Laser Powder Bed Fusion
No full textThe effect of building direction and heat treatment on the microstructure, mechanical properties, and high- temperature oxidation behavior of Hastelloy X (HX) alloy fabricated by the laser powder bed fusion (L-PBF) method was studied. Electron backscatter diffraction analyses revealed that the development of textured columnar grains with varying average grain sizes, boundary fractions, and dislocation densities induced the mechanical anisotropy observed in both horizontally and vertically fabricated samples. The yield strength (YS) values of the horizontally and vertically as-fabricated samples were determined as 605.7 +/- 15.9 MPa and 552.3 +/- 8.5 MPa, respectively. The post-processing heat treatment increased the ductility remarkably and reduced YS value down to similar to 445 MPa for all samples by the elimination of microstructural anisotropy and increased grain size subsequent to recrystallization. Oxidation tests conducted at 900 degrees C up to 100 h on as- fabricated samples exhibited severe intergranular oxidation, which was accompanied by the formation of large voids and microcracks as well as spallation of the oxide layer. In contrast, the heat-treatment improved the oxidation resistance of the alloy possibly due to the formation of uniform and dense Cr2O3 layer on the substrate surface
Quaternary Ammonium-Modified Cellulose: a Sustainable Strategy for Purifying Aqueous Solutions Contaminated With Sunset Yellow Dye
No full textThis study showcases the remarkable efficacy of quaternary ammonium-modified cellulose as a highly sustainable biosorbent for removing Sunset Yellow (SY) dye from water. Detailed analysis was conducted using infrared (FTIR) spectroscopy for structural changes and Scanning Electron Microscopy (SEM) for morphological changes. A minimal yet highly effective dose of 0.05 g was identified through dedicated optimization experiments, achieving near-complete removal (99 %) of SY. The biosorbent demonstrated exceptional performance across a broad pH range (2-10), accomplishing remarkable removal within just 5 min. Langmuir modeling uncovered a monolayer sorption mechanism with a high maximum capacity (107.08 mg g- 1), and thermodynamic analysis affirmed the spontaneity and favorability of the sorption process. Noteworthy is the biosorbent's impressive regeneration capabilities (up to 95 %) using 1.0 M NaOH or HCl solutions and its sustained performance over three sorption-regeneration cycles, highlighting its exceptional stability and reusability. The modified cellulose exhibited remarkable resistance to common interfering ions (chloride, nitrate, and sulfate) at 10 and 100 mg L- 1 concentrations. These combined features position quaternary ammonium-modified cellulose as a promising, sustainable, and efficient option for dye wastewater treatment
Adaptive Reuse of Industrial Heritage in Crises Zones: the Soap Factories in the Levant
No full textThis paper articulates critical considerations for policies related to the adaptive reuse of industrial heritage, particularly in contexts affected by crises, such as conflicts, wars, and natural disasters using the soap factories of the Levant as a case study. It critically investigates the role of adaptive reuse in conserving industrial heritage buildings impacted by crises. The Levant provides a unique context for examining the intersection of cultural heritage and resilience; soap factories, reflective of the region's olive-oil-rich history and industrial legacy dating back to the 18th century, symbolise the conservation challenges and opportunities posed by ongoing regional conflict. The study systematically analyses existing literature on adaptive reuse and questions conventional paradigms in crisis environments, particularly the suitability of standard transformations such as converting industrial heritage into museums or exhibition spaces. Instead, it aims to broaden the dialogue on adaptive reuse by offering context-sensitive policy recommendations. These strategies balance the imperatives of heritage conservation, sustainable development, and contemporary community demands, contributing to a nuanced understanding of industrial heritage preservation in crisis-affected regions
Lessons equitable open access for the to global transition to research
No full textOpen access unlocks research and facilitates collaborations to address the world’s greatest challenges. It allows the public to engage with research and supports policymakers, journalists, medical professionals, teachers, students and the general public to translate research into action. Since open access (OA) was defined by the Budapest Open Access Initiative (BOAI) in 2002, a global movement has driven OA from an untested concept into the mainstream. Yet to fully realize the promise of OA that was envisioned when the BOAI was launched, we must ensure that the systems we are building are equitable and enable anyone,
anywhere to both access and contribute to the global record of scholarship. To achieve this goal, we can take lessons from countries that pioneered the equitable development of scholarly communications. This paper is based on a series of interviews conducted with OA leaders who are implementing equitable OA models.
Today, approximately half of all research articles are OA and freely available to read, yet new barriers have been created for authors to publish. These barriers, including Article Processing Charges (APCs) and the current research assessment system, are not impacting authors evenly.
APCs are fees charged by publishers to authors (or their institution) to make their research articles OA. The rise in use of APCs essentially shifts the paywall from the reader to the author. There is growing recognition that OA publishing models that rely on APCs paid by authors are neither equitable nor sustainable. Researchers, including those early in their careers, as well as those in the Global South, often lack the financial resources necessary to pay APCs.
Globally, there is a need to reform research assessment and rewards to improve incentives. The current assessment system faces challenges including a focus on metrics over quality, marginalization of important research areas, and a lack of recognition for diverse research outputs and contributions. Many countries in the Global South now use the Web of Science, 1a commercial platform which uses the Journal Impact Factor. While there are myriad problems with the use of such metrics, including a bias towards English-language research, these metrics are often used to determine university rankings.
In the Global South, where some institutions do not have the funds to purchase journal subscriptions, leaders have developed their own systems and structures, including publishing platforms and repositories. What they have created is an ecosystem of community-led infrastructure, institutional support for publishing and alternative forms of research assessment which have allowed academics to be involved in the creation of the publishing enterprise and not simply to adopt the governance structures imposed by private interests.
Yet these successful initiatives, such as the publishing platforms, Redalyc and SciELO in Latin America, are under threat from commercial models, particularly the APC-based business model, being driven from the Global North. The BOAI20 Recommendations emphasize that “OA is not an end in itself, but a means to
further ends. Above all, it is a means to the equity, quality, usability, and sustainability of research.” Equitable models of OA do not charge authors to publish and are openly available online. OA journals which do not charge fees to read or publish in have become known as diamond journals. In addition, depositing versions of articles into institutional or subject based repositories, known as the green route, also represent an equitable form of OA. These equitable models of OA are supported by community-governed infrastructure, akin to a Public Digital Infrastructure for OA.
Through interviews with OA leaders in Chile, Costa Rica, India, Indonesia, Mexico, South Africa, Türkiye, and Zimbabwe who are implementing equitable models, I offer lessons for the global transition to equitable OA
Legume and Nut Flours From the Mediterranean Area: Proximate Compositions, Techno-Functionalities, and Spectroscopy Patterns as a Function of Species, Origin, and Treatment
No full textThis study systematically evaluates proximate composition, color, techno-functionalities, and spectroscopy patterns of 19 legume and 16 nut commercial flours of the Mediterranean area. Effect of species, origin, and treatment were analyzed using a Generalized Linear Model. Except for legume proteins, species and origin significantly (p = 0.001) affected flour composition, while heat treatment only had a significant effect (p = 0.05) on nuts. A large variability was observed in fats (0.6-69 g/100g) and proteins (3.7-36 g/100g), and the FT-IR spectra reflected the 35-flours composition. Principal component model clearly distinguished flours based on their carbohydrate, fat, and protein contents. For legumes, color indices, bulk density, and emulsifying properties were significantly affected by species, origin, and treatment, while foaming properties were influenced only by species. For nuts, oil absorption capacity, emulsion properties, and foaming properties were significantly affected by species, origin, and treatment. The origin had a significant effect on water retention capacity (40-433 %) of nuts. The study findings contribute to a better knowledge of Mediterranean legume and nut flours, clarifying their distinct properties for a higher awareness in their use for the design of food products with tailored features
Unveiling the Bi-Functional Potential of Cowo4 Hybridized With Tubular G-C3n4 for Highly Photocatalytic Hydrogen Production, Water Purification and Supercapacitance Activities
No full textIn this paper, CoWO4 nanospheres were successfully hybridized with graphitic carbon nitride with tubular morphology (TCN) and the photocatalytic antibiotic degradation, hydrogen evolution and supercapacitor performances were examined in detail. The morphological, structural and optical properties were characterized. The hybrid CoWO4/TCN-2 catalyst showed the highest tetracycline degradation efficiency with the rate constant of 0.0198 min(-1) which was 3.73 and 5.21 times greater than that of CoWO4 and TCN samples, respectively. The rate of photocatalytic hydrogen evolution was found to be 1997 mu mol/g.h for CoWO4/TCN-2 which was 2.03-fold and 1.09-fold higher than of TCN and CoWO4 samples, respectively. Electrochemical analysis revealed that the charge storage in CoWO4, TCN, and CoWO4/TCN electrodes was mainly governed by faradaic processes. All electrodes showed high-rate capability (>85 %), coulombic efficiency (>90 %) and cycle stability (>100 %). While CoWO4 and TCN electrodes show higher redox activities and specific capacitances than CoWO4/TCN composites, this limitation is mitigated by enhanced wettability in CoWO4/TCN electrodes. Notably, the CoWO4/TCN-2 electrode exhibits superior long-term capacitance, surpassing the TCN electrode after 2000 GCD cycles. This work offers new application areas for the metal tungstate/carbon nitride photocatalysts with improved photocatalytic and electrochemical performances
Elastic and Anelastic Behavior Associated With Structural Transitions in CsPbBr3
No full textStrain coupling and relaxation dynamics critically influence the photovoltaic and photoluminescent performances of metal halide perovskites. Here, resonant ultrasound spectroscopy is employed to study the elastic and anelastic properties associated with the octahedral tilting transitions in the optoelectronic semiconductor CsPbBr3 over the temperature range 303-468 K. The cubic-to-tetragonal transition near 405 K is marked by pronounced elastic softening accompanied by a sharp increase in acoustic loss. High anelastic loss below this transition reveals the presence of mobile ferroelastic twin walls that become pinned by lead vacancies at a temperature interval near 380 K in the tetragonal phase. The elastic softening in the cubic phase is strongly correlated to dynamic effects such as the local polar fluctuations. This local disordered effect is further verified by the anomalously high attenuation in the orthorhombic structure, in which the ferroelastic twin walls might become mobile
Phase-Dependent Optical, Photocatalytic and Capacitive Properties of Tungsten Oxide Nanowires
No full textTransition metal oxides hold great promise across a wide range of applications due to favorable properties such as high abundance, low toxicity, and excellent stability. Nanoengineering approaches are essential for controlling the structural, optical, and electronic properties of these materials, enabling the achievement of desired characteristics in a cost-effective and environmentally friendly manner. In this study, we synthesize stoichiometric (WO3) and sub-stoichiometric (WO3-x) tungsten oxide nanowires by controlling their phases and morphologies through the hydrothermal method. This approach allows us to systematically investigate the effects of different phases and oxygen vacancies on the optical properties, as well as on photocatalytic and supercapacitance applications. We use the photodegradation of RhB as a benchmark for photocatalytic activity under various experimental conditions, revealing that oxygen vacancies significantly influence photocatalytic behavior. For example, WO3-x nanowires adsorb/degrade a substantial amount of RhB within short durations under ambient conditions, where WO3 nanowires are mostly inactive. The addition of H2O2 enhances the photocatalytic performance of WO3 nanowires over 30 minutes, with even better results under low pH conditions with H2O2. This study also explores the phase-dependent electrochemical properties of WO3 and WO3-x nanowires, providing insights into their potential for improved supercapacitor performance by leveraging their complementary properties in symmetric and asymmetric configurations. WO3-x, with a higher density of oxygen vacancies and thinner structure, offers enhanced conductivity and increased active sites for charge storage, resulting in superior specific capacitance and charge retention