Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395

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High Carbohydrate Diet Decreases Microbial Diversity and Increases Il-1β Levels in Mice Colon
(Korean Society Food Science & Technology-kosfost, 2024) Ulutas, Mehmet Sefa; Aydin, Erkin; Cebeci, Aysun
Western diet is known to contribute to intestinal dysbiosis and the progression of inflammation. Although the Turkish diet has different macronutrient contents, the intestinal inflammatory disease incidences in T & uuml;rkiye are comparable to Western countries. Thus, we hypothesized that high carbohydrate diets also contribute to inflammation of the colon. We compared diets with different macronutrient compositions and investigated their effects on colonic microbiota, cytokine, histology, and tight junction protein levels. High carbohydrate diet caused the lowest microbial diversity and is accompanied by the highest expression of interleukin-1 beta and claudin-1. A low carbohydrate diet with zero fiber resulted in the lowest inflammatory markers as well as the lowest occludin and claudin levels. Overall, our results indicate that carbohydrate and fiber contents of the diets are important contributors to colon health.
Citation - WoS: 5
Citation - Scopus: 4
Cyclists as Intelligent Carriers of Space-Time Environmental Information: Crowd-Sourced Sensor Data for Local Air Quality Measurement and Mobility Analysis in the Netherlands
(Routledge Journals, Taylor & Francis Ltd, 2023) Kourtit, Karima; Nijkamp, Peter; Osth, John; Turk, Umut
In recent years, slow travel modes (walking, cycling) have gained much interest in the context of urban air quality management. This article presents the findings from a novel air quality measurement experiment in the Netherlands, by regarding cyclists as carriers and transmitters of real-world information on fine-grained air quality conditions. Using individual sensors on bicycles-connected to a GPS positioning system-online local pollution information originating from cyclists' detailed spatial mobility patterns is obtained. Such air quality surface maps and cyclists' mobility maps are then used to identify whether there are significant differences between the actual route choice and the cyclists' shortest route choice, so as to identify the implications of poor air quality conditions for their mobility choices. Thus, the article seeks to present both a detailed pollution surface map and the complex space-time mobility patterns of cyclists in a region, on the basis of online quantitative data-at any point in time and space-from bicycle users in a given locality. In addition, the article estimates their response-in terms of route choice-to detailed air-quality information through the use of a novel geoscience-inspired analysis of space-time "big data." The empirical test of our quantitative modeling approach was carried out for the Greater Utrecht area in the Netherlands. Our findings confirm that spatial concentration of air pollutants have great consequences for bike users' route choice patterns, especially in the case of non-commuting trips. We also find that cyclists make longer trips on weekends and in the evenings, especially towards parks and natural amenities.
Citation - WoS: 35
Citation - Scopus: 35
Glucose-Dependent Anaplerosis in Cancer Cells Is Required for Cellular Redox Balance in the Absence of Glutamine
(Nature Portfolio, 2016) Cetinbas, Naniye Malli; Sudderth, Jessica; Harris, Robert C.; Cebeci, Aysun; Negri, Gian L.; Yilmaz, Oemer H.; Sorensen, Poul H.
Cancer cells have altered metabolism compared to normal cells, including dependence on glutamine (GLN) for survival, known as GLN addiction. However, some cancer cell lines do not require GLN for survival and the basis for this discrepancy is not well understood. GLN is a precursor for antioxidants such as glutathione (GSH) and NADPH, and GLN deprivation is therefore predicted to deplete antioxidants and increase reactive oxygen species (ROS). Using diverse human cancer cell lines we show that this occurs only in cells that rely on GLN for survival. Thus, the preference for GLN as a dominant antioxidant source defines GLN addiction. We show that despite increased glucose uptake, GLN addicted cells do not metabolize glucose via the TCA cycle when GLN is depleted, as revealed by C-13-glucose labeling. In contrast, GLN independent cells can compensate by diverting glucose-derived pyruvate into the TCA cycle. GLN addicted cells exhibit reduced PDH activity, increased PDK1 expression, and PDK inhibition partially rescues GLN starvation-induced ROS and cell death. Finally, we show that combining GLN starvation with pro-oxidants selectively kills GLN addicted cells. These data highlight a major role for GLN in maintaining redox balance in cancer cells that lack glucose-dependent anaplerosis.
Citation - WoS: 53
Citation - Scopus: 59
Thickness-Tunable Self-Assembled Colloidal Nanoplatelet Films Enable Ultrathin Optical Gain Media
(Amer Chemical Soc, 2020) Erdem, Onur; Foroutan, Sina; Gheshlaghi, Negar; Guzelturk, Burak; Altintas, Yemliha; Demir, Hilmi Volkan
We propose and demonstrate construction of highly uniform, multilayered superstructures of CdSe/CdZnS core/shell colloidal nanoplatelets (NPLs) using liquid interface self-assembly. These NPLs are sequentially deposited onto a solid substrate into slabs having monolayer-precise thickness across tens of cm(2) areas. Because of near-unity surface coverage and excellent uniformity, amplified spontaneous emission (ASE) is observed from an uncharacteristically thin film having 6 NPL layers, corresponding to a mere 42 nm thickness. Furthermore, systematic studies on optical gain of these NPL superstructures having thicknesses ranging from 6 to 15 layers revealed the gradual reduction in gain threshold with increasing number of layers, along with a continuous spectral shift of the ASE peak (similar to 18 nm). These observations can be explained by the change in the optical mode confinement factor with the NPL waveguide thickness and propagation wavelength. This bottom-up construction technique for thickness-tunable, three-dimensional NPL superstructures can be used for large-area device fabrication.
Apatinib Sensitizes Human Breast Cancer Cells Against Navitoclax and Venetoclax Despite Up-Regulated Bcl-2 and Mcl-1 Gene Expressions
(Kare Publ, 2021) Kavakcioglu Yardimci, Berna; Ozgun Acar, Ozden; Semiz, Asli; Sen, Alaattin
OBJECTIVE Defects in apoptotic cell death which restrict the success of conventional cytotoxic therapies have pivotal roles in a number of pathological conditions including cancer. However, a novel drug class targeting pro-survival Bcl-2 protein family members has been developed with the understanding of the structures and interactions of Bcl-2 proteins. Within this new class, Bcl-2/Bcl-xL inhibitor Navitoclax and Bcl-2 specific inhibitor Venetoclax have been shown to demonstrate strong anticancer activities on several types of cancers. But their low affinity to other anti-apoptotic proteins limits their clinical usage. Here, we investigated the cytotoxic and apoptotic effects of Navitoclax/Venetoclax and their combinations with specific tyrosine kinase inhibitor Apatinib on estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cell lines. METHODS MTT assay was used for the evaluation of the inhibition of cancer cell proliferation. ELISA test and Quantitative real-time PCR assay was performed to determine the role of caspase-3, Bak, Bax, Bcl-2, Bcl-xL and Mcl-1 proteins in the inhibition of cell proliferation triggered by the tested agents. RESULTS We found that aggressive MDA-MB-231 cell line was more sensitive to all tested agents. Apatinib significantly enhanced Navitoclax/Venetoclax mediated inhibition of cell viability in both cancer cell lines despite up-regulation in the expression levels of Bcl-2 and Mcl-1 genes. We further demonstrated significant Bak/Bax and caspase-3 expression in less aggressive MCF-7 cells. CONCLUSION Our findings have impacts on Navitoclax/Venetoclax plus Apatinib based therapy for breast adenocarcinoma. On the other hand, further studies should be conducted to elucidate the mechanisms underlying synergistic effects of Navitoclax/Venetoclax plus Apatinib combinations.
A reliable and secure communication design for underwater sensor networks concerning energy efficiency
(Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2023) UYAN, Osman Gökhan
Underwater Acoustic Sensor Networks (UASNs) recently attract scientists because of its wide range of applications and emerging technology. A design challenge in UASN's is the limited network lifetime and poor reliability caused by limited battery supply of sensors and harsh channel conditions in underwater environment. Moreover, sensors might transmit sensitive data that must be disguised against eavesdropping attacks. To maintain a reliability level, packet-duplication and multi-path routing method are suggested, which renders eavesdropping attacks easier. For data security, cryptographic encryption is the most acclaimed method. However, encryption needs extra computations, which consume extra energy and cause a decrease in the network lifetime. As a countermeasure along with encryption against silent listening, fragmenting data and transmitting in pieces over different paths has been proposed. To address these challenges, an optimization framework has been developed to analyze the effects of multi-path routing, packet duplication, encryption, and data fragmentation on network lifetime. However, the solution time of the proposed optimization model is quite high, and sometimes it cannot come up with feasible solutions. To this end, in this study, different regression and neural network methods have been proposed to predict the energy consumptions of underwater nodes as supplementary methods to optimization models. Performance evaluations show that the proposed methods yield remarkably accurate predictions and can be used for energy consumption prediction in UASNs.
Citation - WoS: 75
Citation - Scopus: 74
Perfluoroalkyl-Functionalized Thiazole Thiophene Oligomers as N-Channel Semiconductors in Organic Field-Effect and Light-Emitting Transistors
(Amer Chemical Soc, 2014) Usta, Hakan; Sheets, William Christopher; Denti, Mitchell; Generali, Gianluca; Capelli, Raffaella; Lu, Shaofeng; Facchetti, Antonio
Despite their favorable electronic and structural properties, the synthetic development and incorporation of thiazole-based building blocks into n-type semiconductors has lagged behind that of other pi-deficient building blocks. Since thiazole insertion into pi-conjugated systems is synthetically more demanding, continuous research efforts are essential to underscore their properties in electron-transporting devices. Here, we report the design, synthesis, and characterization of a new series of thiazolethiophene tetra- (1 and 2) and hexa-heteroaryl (3 and 4) co-oligomers, varied by core extension and regiochemistry, which are end-functionalized with electron-withdrawing perfluorohexyl substituents. These new semiconductors are found to exhibit excellent n-channel OFET transport with electron mobilities (mu(e)) as high as 1.30 cm(2)/(V center dot s) (I-on/I-off > 10(6)) for films of 2 deposited at room temperature. In contrary to previous studies, we show here that 2,2'-bithiazole can be a very practical building block for high-performance n-channel semiconductors. Additionally, upon 2,2'- and 5,5'-bithiazole insertion into a sexithiophene backbone of well-known DFH-6T, significant charge transport improvements (from 0.0010.021 cm(2)/(V center dot s) to 0.200.70 cm(2)/(V center dot s)) were observed for 3 and 4. Analysis of the thin-film morphological and microstructural characteristics, in combination with the physicochemical properties, explains the observed high mobilities for the present semiconductors. Finally, we demonstrate for the first time implementation of a thiazole semiconductor (2) into a trilayer light-emitting transistor (OLET) enabling green light emission. Our results show that thiazole is a promising building block for efficient electron transport in ?-conjugated semiconductor thin-films, and it should be studied more in future optoelectronic applications.
Effect of Yttrium/Lanthanum-Doped Ultrasonically Assisted Nano-Hydroxyapatite on Remineralization and Bracket Bond Strength in Artificial Enamel Lesions
(BMC, 2025) Ozturk, Taner; Mammadov, Elshan; Bulduk Karakaya, Humeyra; Yagci, Filiz; Dayan, Serkan; Yagci, Ahmet
Background This in vitro study aimed to evaluate the remineralization efficacy of ultrasonically assisted yttrium fluoride-doped (Ult-YF3-nHAP) and lanthanum fluoride-doped (Ult-LaF3-nHAP) nano-hydroxyapatite (nHAP) on artificially induced enamel lesions (aWSLs), and to compare their performance with acidulated phosphate fluoride (APF) gel, fluoride varnish, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and resin infiltrant (ICON). Methods This in vitro study followed a four-phase design: enamel lesion creation, application of remineralization agents, a 14-day treatment protocol, and post-treatment analyses using QLF, Micro-CT, SEM-EDX, and SBS testing. This study included 168 extracted human premolars, divided into eight experimental groups (n = 21 per group): (1) Demineralized control (no remineralization treatment), (2) Acidulated phosphate fluoride (APF) gel, (3) Fluoride varnish, (4) Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), (5) Ultrasonically assisted nHAP (Control nHAP), (6) Ult-YF3-nHAP, (7) Ult-LaF3-nHAP, and (8) Resin infiltrant (ICON). The aWSLs were created under laboratory conditions. Brackets were bonded to the teeth with composite material, and aWSLs were created under laboratory conditions. After lesion formation and at the end of the experimental process, micro-computed tomography (Micro-CT) and laser-assisted quantitative light fluorescence (QLF) analysis were performed to assess lesion progression and remineralization. Additionally, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and shear bond strength (SBS) tests were conducted at the end of the study. Statistical analysis was performed using one-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests, with a significance level of p < 0.05. Results The bracket bond strength test data showed no significant differences between the groups (p = 0.156). Significant differences were found among groups for QLF fluorescence recovery (Delta F, p < 0.001), with the Ult-YF3-nHAP group showing the greatest increase (median: +0.5, IQR: -1.4 to + 0.7), while the control group showed the greatest decrease (median: -12.1, IQR: -12.4 to -10.2). Micro-CT analysis also revealed significant differences between groups (p = 0.008). The APF Gel group showed values comparable to those of all other experimental groups. The highest remineralization values were recorded in the Ult-YF3-nHAP group (6.87 +/- 3.03 mm(3)), whereas the lowest values were found in the Varnish group. The demineralized control group had significantly higher values than the Varnish group, but lower than the Ult-LaF3-nHAP group. SEM-EDX analysis revealed that fluoride weight was significantly lower in the Tooth Mousse and Varnish groups compared to the other experimental groups (p < 0.001). Ca/P ratio was significantly lower in the demineralized control, Varnish, and Ult-YF3-nHAP groups than in other experimental groups (p = 0.002). Conclusion Ult-YF3-nHAP showed higher efficacy in remineralization of aWSLs compared to fluoride-based treatments, CPP-ACP, and resin infiltrant. The highest remineralization was detected in the Ult-YF3-nHAP group by micro-CT and QLF analysis, while fluoride varnish gave the lowest result.
Citation - WoS: 37
Citation - Scopus: 39
Spectrally Wide-Range Efficient, and Bright Colloidal Light-Emitting Diodes of Quasi-2D Nanoplatelets Enabled by Engineered Alloyed Heterostructures
(Amer Chemical Soc, 2020) Altintas, Yemliha; Liu, Baiquan; Hernandez-Martinez, Pedro Ludwig; Gheshlaghi, Negar; Shabani, Farzan; Sharma, Manoj; Demir, Hilmi Volkan
Recently, there has been tremendous interest in the synthesis and optoelectronic applications of quasi-two-dimensional colloidal nanoplatelets (NPLs). Thanks to the ultranarrow emission linewidth, high-extinction coefficient, and high photostability, NPLs offer an exciting opportunity for high-performance optoelectronics. However, until now, the applications of these NPLs are limited to available discrete emission ranges, limiting the full potential of these exotic materials as efficient light emitters. Here, we introduce a detailed systematic study on the synthesis of NPLs based on the alloying mechanisms in core/shell, core/alloyed shell, alloyed core/shell, and alloyed core/alloyed shell heterostructures. Through the engineering of the band gap supported by the theoretical calculations, we carefully designed and successfully synthesized the NPL emitters with continuously tunable emission. Unlike conventional NPLs showing discrete emission, here, we present highly efficient core/shell NPLs with fine spectral tunability from green to deep-red spectra. As an important demonstration of these efficient emitters, the first-time implementation of yellow NPL light-emitting diodes (LEDs) has been reported with record device performance, including the current efficiency surpassing 18.2 cd A(-1), power efficiency reaching 14.8 lm W-1, and record luminance exceeding 46 900 cd m(-2). This fine and wide-range color tunability in the visible range from stable and efficient core/shell NPLs is expected to be extremely important for the optoelectronic applications of the family of colloidal NPL emitters.
Citation - WoS: 1
Citation - Scopus: 2
Investigating the Role of Stator Slot Indents in Minimizing Flooded Motor Fluid Damping Loss
(MDPI, 2023) Tekgun, Didem; Tekgun, Burak
This research examines how fluid damping loss affects the operation of a two-pole, 5.5 HP (4 kW) induction machine (IM) within the context of different slot opening configurations developed for downhole water pump applications. Since these motors operate with their cavities filled with fluid, the variations in fluid viscosity and density, compared to air, result in the occurrence of damping losses. Furthermore, this loss can be attributed to the motor's stator and rotor surface geometry, as the liquid within the motor cavity moves unrestrictedly within the motor housing. This study involves the examination of the damping loss in a 24-slot IM under different stator slot indentations. The investigation utilizes computational fluid dynamics (CFD) finite element analysis (FEA) and is subsequently validated through experiments. The aim of this work is to emphasize the significance of fluid damping loss in submerged machines. Results reveal that the damping loss exceeds 8% of the motor output power when the stator surface has indentations, and it diminishes to 3.2% of the output power when a custom wedge structure is employed to eliminate these surface indentations.
Citation - Scopus: 12
CoviDetector: A Transfer Learning-Based Semi Supervised Approach to Detect COVID-19 Using CXR Images
(Elsevier B.V., 2023) Chowdhury, Deepraj; Das, Anik; Dey, Ajoy; Banerjee, Soham; Golec, Muhammed; Kollias, Dimitrios; Arya, Rajesh Chand
COVID-19 was one of the deadliest and most infectious illnesses of this century. Research has been done to decrease pandemic deaths and slow down its spread. COVID-19 detection investigations have utilised Chest X-ray (CXR) images with deep learning techniques with its sensitivity in identifying pneumonic alterations. However, CXR images are not publicly available due to users’ privacy concerns, resulting in a challenge to train a highly accurate deep learning model from scratch. Therefore, we proposed CoviDetector, a new semi-supervised approach based on transfer learning and clustering, which displays improved performance and requires less training data. CXR images are given as input to this model, and individuals are categorised into three classes: (1) COVID-19 positive; (2) Viral pneumonia; and (3) Normal. The performance of CoviDetector has been evaluated on four different datasets, achieving over 99% accuracy on them. Additionally, we generate heatmaps utilising Grad-CAM and overlay them on the CXR images to present the highlighted areas that were deciding factors in detecting COVID-19. Finally, we developed an Android app to offer a user-friendly interface. We release the code, datasets and results’ scripts of CoviDetector for reproducibility purposes; they are available at: https://github.com/dasanik2001/CoviDetector © 2024 Elsevier B.V., All rights reserved.
Citation - WoS: 4
Citation - Scopus: 9
Are We Ready for the New Normal in E-Business Education? Sentiment Analysis of Learners' Opinions on MOOCs
(Russian State Vocational Pedagogical Univ, 2021) Derindag, O. F.; Cizmeci, B.
Introduction. The new digital economy and its constantly evolving paradigm have completely transformed the model of doing business and the learning methods. MOOCs (massive-open-online-courses) and micro-credentials are the educations interfaces, have become an important teaching environment tool. Distance learning has become an indispensable alternative teaching method in updating and transferring classical education materials according to real-world settings, especially for learners in higher education. Aim. The current research is aimed to address the society's readiness and attitude direction to the concept of MOOCs and distance learning, highlighting its emergence and inevitability for educational institutions of all types in order to make a fundamental change in their curricula, especially in e-business courses, which are the most demanded training courses on MOOCs platforms. Methodology and research methods. In the study, the awareness and recognition of the online community on the MOOCs concept is examined. in this direction, Turkish people's perception and attitudes toward MOOCs have been addressed via sentiment analysis on Eksi Sozluk, the largest social communication and discussion platform in Turkey. Results. According to the sentiment analysis results, it has been determined that 52% of respondents have positive judgments on distance education and MOOCs, 29% of responses are neutral and 18% are negative. In general, distance education and MOOCs are perceived as a useful new education model by the Turkish people. Scientific novelty. This paper is the first sentiment analysis of learners' opinions on MOOCs and distance learning in Turkey. Considering the increasing awareness of MOOCs and the need for e-business education, as the most demanded type of MOOCs, this is the first study investigating the priority of these two phenomena within the context of COVID-19. Practical significance. It is thought that this study will contribute to the stakeholders in terms of showing how MOOCs and micro-credentials have a high potential to understanding trends in education especially in the new normal after the COVID-19 pandemic. The holistic education model of institutions has difficulty meeting the competitive nature and result-oriented approach of the e-business ecosystem. This market reality requires the institutions to offer more to-the-point and applied education solutions. In terms of e-business (e-commerce, digital marketing) education, the importance of MOOCs as a solution-focused on "how" rather than "what." has been comprehensively discussed in the paper.
Citation - WoS: 36
Citation - Scopus: 34
A Dopant-Free 2,7-Dioctyl[1]Benzothieno[3,2 (C8-BTBT) Hole Transporting Layer for Highly Stable Perovskite Solar Cells With Efficiency Over 22%
(Royal Soc Chemistry, 2022) Kaya, Ismail Cihan; Ozdemir, Resul; Usta, Hakan; Sonmezoglu, Savas
In this study, for the first time, n-i-p PSCs were fabricated using dopant-free 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as the solution-processed hole transporting layer (HTL). The power conversion efficiency (PCE) of the optimized device with the C8-BTBT film that favored edge-on molecular alignment was 22.45% with negligible hysteresis. A thinner dopant-free C8-BTBT HTL effectively protected the perovskite layer from moisture resulting in better shelf-life stability for un-encapsulated PSCs, which maintained >80% of its initial PCE (after a period of 120 days) at a relative humidity level of 40-45%. In addition, the C8-BTBT-based PSCs kept their high performance with no obvious PCE loss at 60 degrees C for 20 days in the ambient atmosphere and retained 82% of their initial PCE at 85 degrees C for 10 days. Overall, our findings revealed that a thin solution-processed C8-BTBT HTL plays a critical role not only in hole extraction and transport but also in greatly improving the ambient and thermal stability of n-i-p PSCs.
Citation - WoS: 1
Citation - Scopus: 2
Complementary Medicines Used in Ulcerative Colitis and Unintended Interactions With Cytochrome P450-Dependent Drug-Metabolizing Enzymes
(Tubitak Scientific & Technological Research Council Turkey, 2022) Sen, Alaattin
Ulcerative colitis (UC) is an idiopathic, chronic inflammatory disease with multiple genetic and a variety of environmental risk factors. Although current drugs significantly aid in controlling the disease, many people have led to the application of complementary therapies due to the common belief that they are natural and safe, as well as due to the consideration of the side effect of current drugs. Curcumin, cannabinoids, wheatgrass, Boswellia, wormwood and Aloe vera are among the most commonly used complementary medicines in UC. However, these treatments may have adverse and toxic effects due to unintended interactions with drugs or drug-metabolizing enzymes such as cytochrome P450s; thus, being ignorant of these interactions might cause deleterious effects with severe consequences. In addition, the lack of complete and controlled long-term studies with the use of these complementary medicines regarding drug metabolism pose additional risk and unsafety. Thus, this review aims to give an overview of the potential interactions of drug-metabolizing enzymes with the complementary botanical medicines used in UC, drawing attention to possible adverse effects.
Citation - WoS: 27
Citation - Scopus: 22
Quantum Dot and Electron Acceptor Nano-Heterojunction for Photo-Induced Capacitive Charge-Transfer
(Nature Portfolio, 2021) Karatum, Onuralp; Eren, Guncem Ozgun; Melikov, Rustamzhon; Onal, Asim; Ow-Yang, Cleva W.; Sahin, Mehmet; Nizamoglu, Sedat
Capacitive charge transfer at the electrode/electrolyte interface is a biocompatible mechanism for the stimulation of neurons. Although quantum dots showed their potential for photostimulation device architectures, dominant photoelectrochemical charge transfer combined with heavy-metal content in such architectures hinders their safe use. In this study, we demonstrate heavy-metal-free quantum dot-based nano-heterojunction devices that generate capacitive photoresponse. For that, we formed a novel form of nano-heterojunctions using type-II InP/ZnO/ZnS core/shell/shell quantum dot as the donor and a fullerene derivative of PCBM as the electron acceptor. The reduced electron-hole wavefunction overlap of 0.52 due to type-II band alignment of the quantum dot and the passivation of the trap states indicated by the high photoluminescence quantum yield of 70% led to the domination of photoinduced capacitive charge transfer at an optimum donor-acceptor ratio. This study paves the way toward safe and efficient nanoengineered quantum dot-based next-generation photostimulation devices.
Citation - Scopus: 1
A Semi-Analytic Method for Solving Singularly Perturbed Twin-Layer Problems With a Turning Point
(Vilnius Gediminas Tech Univ, 2023) Cengizci, Suleyman; Kumar, Devendra; Atay, Mehmet Tarik
This computational study investigates a class of singularly perturbed second-order boundary-value problems having dual (twin) boundary layers and simple turning points. It is well-known that the classical discretization methods fail to resolve sharp gradients arising in solving singularly perturbed differential equations as the perturbation (diffusion) parameter decreases, i.e., epsilon -> 0(+). To this end, this paper proposes a semi-analytic hybrid method consisting of a numerical procedure based on finite differences and an asymptotic method called the Successive Complementary Expansion Method (SCEM) to approximate the solution of such problems. Two numerical experiments are provided to demonstrate the method's implementation and to evaluate its computational performance. Several comparisons with the numerical results existing in the literature are also made. The numerical observations reveal that the hybrid method leads to good solution profiles and achieves this in only a few iterations.
Citation - WoS: 16
Citation - Scopus: 17
Colloidal Aluminum Antimonide Quantum Dots
(Amer Chemical Soc, 2019) Jalali, Houman Bahmani; Sadeghi, Sadra; Sahin, Mehmet; Ozturk, Hande; Ow-Yang, Cleva W.; Nizamoglu, Sedat
AlSb is a less studied member of the III-V semiconductor family, and herein, we report the colloidal synthesis of AlSb quantum dots (QDs) for the first time. Different sizes of colloidal AlSb QDs (5 to 9 nm) were produced by the controlled reaction of AlCl3 and Sb[N(Si(Me)(3))(2)](3) in the presence of superhydride. These colloidal AlSb quantum dots showed excitonic transitions in the UV-A region and a tunable band edge emission (quantum yield of up to 18%) in the blue spectral range. Among all III-V quantum dots, these quantum dots show the brightest core emission in the blue spectral region.
Citation - WoS: 2
Citation - Scopus: 4
Effect of Geometry Modifications on the Vectoring Performance of a Controlled Jet
(Isfahan University of Technology secretary@jafmonline.net, 2017) Tomac, Mehmet N.
Jet vectoring performances of ten different designs with various depths and geometrical outlines were quantified through constant temperature anemometry measurements for a Reynolds number range from 10,000 to 30,000 by using passive and active flow control methods at cold flow. The reference design was based on NASA's double throat nozzle concept and a self-injection double throat nozzle design that uses similar flow control concept as the reference design, were also tested for performance comparison. Furthermore, jet vectoring performance of a single throat design, utilizing Coanda effect for jet vectoring, was also quantified. Results indicated jet vectoring angles starting from 2° up to 47° for a control jet flow rate range from 1% up to 10% with respect to the primary jet flow rate in the investigated Re range. Maximum jet vectoring angle was achieved with a single throat design which incorporates small step geometry before the Coanda surface for more effective flow attachment and these results were compared with the vectoring performance of the double throat nozzle designs. © 2018 Elsevier B.V., All rights reserved.
Citation - WoS: 23
Citation - Scopus: 25
Selective Removal of Cationic Micro-Pollutants Using Disulfide-Linked Network Structures
(Royal Soc Chemistry, 2017) Atas, Mehmet Sahin; Dursun, Sami; Akyildiz, Hasan; Citir, Murat; Yavuz, Cafer T.; Yavuz, Mustafa Selman
Micropollutants are found in all water sources, even after thorough treatments that include membrane filtration. New ones emerge as complex molecules are continuously produced and discarded after used. Treatment methods and sorbent designs are mainly based on non-specific interactions and, therefore, have been elusive. Here, we developed swellable covalent organic polymers (COP) with great affinity towards micropollutants, such as textile industry dyes. Surprisingly, only cationic dyes in aqueous solution were selectively and completely removed. Studies of the COPs surfaces led to a gating capture, where negatively charged layer attracts cationic dyes and moves them inside the swollen gel through diffusive and hydrophobic interaction of the hydrocarbon fragments. Despite its larger molecular size, crystal violet has been taken the most, 13.4 mg g(-1), surpassing all competing sorbents. The maximum adsorption capacity increased from 12.4 to 14.6 mg and from 8.9 to 11.4 mg when the temperature of dye solution was increased from 20 to 70 degrees C. The results indicated that disulfide-linked COPs are attractive candidates for selectively eliminating cationic dyes from industrial wastewater due to exceptional swelling behaviour, low-cost and easy synthesis.
Citation - WoS: 1
Citation - Scopus: 2
Is Artificial Intelligence a Trustworthy Route Navigation System for Smart Urban Planning
(Univ Alexandru Ioan Cuza, Centrul Studii Europene, 2024) Kourtit, Karima; Nijkamp, Peter; Osth, John; Turk, Umut
In the age of smart or intelligent cities, the use of Artificial Intelligence (AI) presents a spectrum of new opportunities and challenges for both the research and policy community. The present study explores the intricate interplay between AI-generated content and actual choice spectra in urban planning. It focuses on the concept of 'city intelligence' and related AI concepts, underscoring the pivotal role of AI in addressing and understanding the quality of life in contemporary urban environments. As AI continues its transformative impact on communication and information systems in the realm of urban planning, this study brings to the forefront key insights into the challenges of validating AI-based information. Given the inherently subjective nature of AIgenerated content, and its influential role in shaping user-perceived value, AI will most likely be a game changer catalyzing enhancements in the urban quality of life and inducing favorable urban developments. Additionally, the study also addresses the significance of the so-called 'Garbage-in Garbage-out' (GiGo) principle and 'Bullshitin Bullshit out' (BiBo) principle in validating AI-generated content, and seeks to enhance our understanding of the spatial information landscape in urban planning by introducing the notion of an urban X'XQ' performance production function.

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