IYTE GCRIS Database (Izmir Institute of Technology)
Not a member yet
11968 research outputs found
Sort by
Integration of Conductive Additives To Pla-Based Biodegradable Composite Films To Improve Their Electrical, Mechanical, and Physical Characteristics
No full textIn this study, Oltu stone powder (OS) and Fe3O4/mica-based conductive pigment (CP) were compounded with polylactic acid (PLA) to develop bio-based conductive films. Four different concentrations of 1%, 10%, 20%, and 30% of powders were applied to determine their optimal concentration in the PLA matrix. The mechanical, thermomechanical, electrical conductivity, melt-flow, and morphological properties of composite films were reported using the tensile, hardness, and impact tests, dynamic mechanical analyses test, linear four-probe method, and atomic force microscopy (AFM), melt-flow index measurements, and scanning electron microscopy methodology, respectively. According to tensile test results, tensile strength and modulus characteristics of PLA decrease with additive integration. However, the elongation value of PLA declined as OS and CP loadings increased. The maximum tensile performance was attained for composites filled with 20% of both CP and OS. The unfilled PLA's Shore D value rose by including OS and CP. At the same loading levels, carbon-based OS produced comparatively higher hardness values than CP, which comprised iron oxide and alumina silicate. AFM analysis revealed that both CP and OS inclusions caused enhancements in surface roughness as their filling amounts increased. In summary, composite samples exhibiting a 20% loading ratio of both OS and CP showed significantly improved mechanical and thermomechanical performances compared to other composites. Composite films with 1% additives have the potential to be applied in electrostatic packing. Additionally, 3D-printed components can be fabricated using composites for applications where appropriate mechanical resistance and electrical conductivity specifications are required
Diaph1-Deficiency Is Associated With Major T, Nk and Ilc Defects in Humans (vol 44, 175, 2024)
No full text[No Abstract Available
Laser Surface Treatment Optimization of 1.2379 (Aisi D2) Tool Steel
No full textIndustrial applications require materials with specific surface quality and hardness properties. Laser surface treatment stands out as a cost-effective and effective method that improves surface performance by changing the structural and physical properties of the material. 1.2379 cold work tool steel is a commonly used material in die and mold industries for injection mold inserts; therefore, the surface properties of the material play a significant role. In this study, it is aimed to optimize laser parameters; the laser power, pulse duration, repetition rate and line spacing for the responses such as hardness and surface roughness. For this purpose, 1.2379 cold work tool surfaces were treated using a commercially available industrial ytterbium low-power pulsed fiber laser experimentally. Experiments were conducted based on 34 full factorials. Vickers hardness and micro-roughness measurements were performed on the laser-treated surfaces. Regression models were developed using experimental data and the appropriate models were selected for each response. The response variables were then optimized based on stochastic optimization methods: Nelder-Mead, Differential Evolution, Random Search and Simulated Annealing. The results indicate that a maximum hardness of 495 HV0.5 and a minimum surface roughness of 0.277 mu m were achieved, corresponding to a 61% increase and a 43% decrease, respectively, compared to the base metal
Utilization of Black Cumin (nigella Sativa L.) Cake Proteins as a Sustainable Food Ingredient: a Comparative Study With Commercial Proteins for Antioxidant, Techno-Functional and Vegan Cheese Properties
No full textThis study aimed to compare the antioxidant, techno-functional and vegan cheese properties of black cumin cake protein concentrate (BPC) with those of commercial proteins. The BPC (63% protein, w/w) showed greater antioxidant potential (TEAC: 247 mu mol Trolox/g; ORAC: 211 mu mol Trolox/g; iron chelation capacity: 35.5 mu mol Trolox/g) than potato protein isolate (PPI), but comparable antioxidant potential with soy protein isolate (SPI). The BPC had slightly lower water binding capacity (7 g/g) than SPI (8.8 g/g), but 1.7 and 1.9-fold higher oil binding capacity (5.4 g/g) than PPI and SPI, respectively. All proteins showed similar emulsion capacity (EC) and stability (ES) at high protein concentrations (>= 1%), but BPC showed the highest EC and ES at low protein concentrations (= 0.5%). BPC showed higher least gelling concentration (LGC: 14%) than PPI and SPI (LGCs for both 10%). However, the texture profile analysis showed that the heat-induced gels of BPC were firm but easily chewable. Moreover, BPC gels showed the highest springiness and resilience. The BPC-based spreadable vegan cheese was softer (firmness: 5.52 N), more easily spreadable (spreadability value: 6.23 N s), but less adhesive and sticky than SPI- and PPI-based spreadable vegan cheeses. SPI-based cheese showed the highest viscoelastic moduli followed by PPI and BPC with similar viscoelastic moduli. SPI-based cheese demonstrated the most favorable sensory properties, but BPC showed acceptable overall sensory properties. This work proved that black cumin proteins could be utilized to novel spreadable black vegan cheese. Further studies are needed to develop novel black-colored vegan food such as black milk, ice-cream, sausage, cake, crackers etc
Assessing the Spatial and Temporal Characteristics of Meteorological Drought in Afghanistan
No full textAfghanistan is suffering from periodic events of drought, which has exacerbated in recent years due to extreme climate events in the region. Having an arid to semi-arid climate, the country faces significant challenges of water resources management, especially for irrigation as reliance on agriculture is cumbersome. This study is undertaken to characterize historical meteorological drought in Afghanistan to provide an insight on where and when meteorological drought events happened in different River Basins (RBs). The study mainly employs the gamma-Standardized Precipitation Index (gamma-SPI) to analyze historical meteorological droughts across Afghanistan from 1979 to 2019. Monthly precipitation data is obtained from the Ministry of Energy and Water (MEW) of Afghanistan, which is a combination of observed data from ground stations and gap-filled data by the MEW for the study period. Gridded gamma-SPI values are interpolated and mapped to visualize patterns of spatial drought across the entire country. The results indicate that countrywide extreme drought events occurred in 1999, 2000, 2001, 2010, 2016, 2017, and 2019, particularly affecting southern, western, and southwestern regions. Decreasing rainfall occurred in all five RBs, with the most considerable decline observed in the 1999–2008 period. The study reveals the increasing frequency and severity of meteorological droughts in Afghanistan. It also emphasizes on the vulnerability of agriculture and water sectors due to the drought events. The findings of the study suggest the need for better drought monitoring, preparedness, awareness, and adaptation of strategies to ensure water security and agricultural sustainability in the face of climate change. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024
Valorization of Black Carrot Pomace and Pea Powder for Co-Production of Polygalacturonase and Pectin Lyase
No full textPectic enzyme groups, particularly polygalacturonase and pectin lyase, are vital components of a high-value microbial enzyme category widely employed in applications within the fruit juice and wine industries. The exploration of alternative carbon and nitrogen sources remains crucial for enhancing enzyme production while reducing costs. This study evaluates the impact of carbon (black carrot pomace) and nitrogen (pea protein) loading on fermentable sugar content, protein content, and enzyme activities during both batch and fed-batch cultivation. Additionally, three distinct valorization techniques—thermal (steam), thermochemical (steam assisted with dilute acid), and microwave-assisted with dilute acid pretreatments—were assessed for their effectiveness in hydrolyzing black carrot pomace as a carbon source. The findings indicate that microwave-assisted dilute acid, coupled with enzymatic saccharification, resulted in the highest fermentable sugar production (0.493 g/g), achieving an 87.3% conversion yield. Pea protein demonstrated more favorable outcomes with the highest polygalacturonase activity (20.50 ± 0.52 U/L) and pectin lyase activity (46.44 ± 3.45 U/L) compared to whey protein and yeast extract used as nitrogen sources. Meanwhile, the highest polygalacturonase and pectin lyase activity, along with the highest total protein content (52.25 ± 0.06 mg/L), was recorded under the same culture conditions, reaching 164.34 ± 2.26 and 188.22 ± 1.72 U/L, respectively, after 72 h, representing approximately 1.18- and 1.34-fold increases from the batch system. Consequently, these results prove that fed-batch cultivation, utilizing black carrot pomace hydrolyzate as a feeding substrate and pea protein as a nitrogen source, significantly increases polygalacturonase and pectin lyase activity compared to batch cultivation. © The Author(s) 2024
Towards Sustainable Manufacturing: a Review and Future Directions in Additive Manufacturing of Fiber-Reinforced Polymer Composites
No full textThe United Nations Sustainable Development Goals (SDGs) provide a global framework for addressing critical challenges such as climate change, resource scarcity and sustainable industrialization. With increasing demand for products and improving quality of life, linear consumption of materials and resources following the “take-make-waste” is no longer possible. As such, innovative solutions are increasingly necessary to enable circular economy in manufacturing. Additive manufacturing (AM) has emerged as a transformative technology in achieving SDGs by enhancing resource efficiency and minimizing waste. Fiber reinforced composites are a promising application of AM, as they offer the potential to optimize material use, reduce labor and support sustainable production practices. However, there is an urgent need for considering circular economy strategies, life cycle assessment (LCA) frameworks and effective recycling at the end of their lifetime. This study examines additive manufacturing systems for fiber-reinforced composites, their environmental impact and exploring the potential contributions of robotic integration in composite manufacturing to enhanced sustainability. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
Spiky Metropolitan Landscapes: an Urbanometric Analysis of Growing Agglomerations
No full textThe spatial configuration of urban systems has garnered significant interest from various disciplines, including urban planners, economists, and ecologists, due to its interconnectedness with various aspects of sustainable development. Research on urban form suggests a departure from the conventional model of a gradually declining density gradient from the city center, giving way to a "spiky" urban landscape characterized by a heterogeneous polycentric pattern. This study aims to examine the recently emerging spiky structure of an urban agglomeration and its determinants, providing insights into the potential prospects of cities. We adopt a new quantitative modeling approach inspired by spatial econometrics and coined here 'urbanometrics'. By utilizing and testing spatial dependence urbanometric models, we seek to elucidate the factors driving these changes, with a specific focus on pluriform urban sprawl in the Mediterranean region, specifically the Izmir city-region. The findings indicate that since the early 2000s, the Izmir city-region has experienced simultaneous decentralization and the emergence of multiple centers, with sharp differences. Furthermore, the results demonstrate that the expansion of highway infrastructure, population growth, and existing convertible (agricultural or forest) land contribute to urban sprawl and the emergence of a "spiky" urban landscape
The Effect of Co-Delivery of Oxygen and Antibacterial Drug Gentamicin From Alginate-Based Nanocomposite Hydrogels on Bacterial Apoptosis and Cell Viability
No full textThere is a need to develop multifunctional biomaterials that can deliver oxygen and antibacterial drugs together for effective wound healing applications. Here, we report a novel biomaterial capable of co-delivering O2 and the antibacterial drug Gentamicin (GEN) for a period of 7 and 15 days, respectively. This biomaterial is fabricated by the synthesis of perfluorocarbon-based periodic mesoporous organosilica (PMOF) and the loading of its pores with GEN (GENPMOF). The synthesized GENPMOF is incorporated in alginate hydrogel to obtain Alg-GENPMOF with O2 and GEN co-delivery ability. Our results show that PMOF and GENPMOF have concentration-dependent toxicity on both Gram-negative E. coli and Gram-positive S. aureus bacteria. The most effective concentration of PMOF and GENPMOF (0.5 mg/mL) show little toxic effect for fibroblast cells. On the other hand, Alg-PMOF and Alg-GENPMOF prepared using this concentration require a long incubation time with E. coli to induce apoptosis. However, an incubation period of 1 day is sufficient to inhibit the growth of S. Aureus. Furthermore, Alg-PMOF and Alg-GENPMOF increase fibroblast cell viability under both normoxic and hypoxic conditions while slightly decreasing cancerous Malme-3M cell viability within 5 days of incubation
High-Temperature Bose-Einstein Condensation of Dark Excitons in Holey Graphyne
No full textWe investigated the optical and excitonic properties of holey graphyne (HGY), which is a recently synthesized two-dimensional (2D) carbon allotrope, using first-principles calculations. The potential of HGY for and band-edge wave-function symmetry of HGY lead to strong Coulomb interactions and symmetry-forbidden optical transition, resulting in the formation of long-lived dark excitons. The lowest-energy dark exciton in HGY has a large binding energy of 0.63 eV and can be well described by the screened hydrogenic model. By analyzing the constraints on exciton density and temperature necessary for BEC, a phase diagram for the electron-hole system in HGY is constructed, and a maximum BEC transition temperature of 503 K is predicted. Our findings thus reveal the great possibility of achieving above-room-temperature excitonic BEC in 2D carbon materials