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Supercapacitor devices based on multiphase MgTiO3 perovskites doped with Mn2+ ions
No full textRecently, perovskites have become a hotspot for researchers attempting to exploit metal and oxygen vacancies in structures of the form MTiO3, facilitating the convenient electron/hole migration, thus displaying interesting properties. Magnesium Titanate (MgTiO3) is a prominent part of the perovskite class, exhibiting remarkable electrical, thermal, and chemical properties. Undoped and Mn-doped MgTiO3 samples were obtained using a solid-state reaction starting from previously synthesized MgO and TiO2 powders, which were separately doped with different Mn ion concentrations. The resulting multiphase materials with a major MgTiO3 phase were thoroughly morpho-structurally analyzed employing XRD, STEM, Raman, PL, XPS, and EPR spectroscopy. The electrochemical results indicate that they show superior performance when used as electrode materials for supercapacitor application due to the high defect concentration as shown in EPR and PL spectroscopy and the ferroelectric behavior observed in XPS and XRD. When used in symmetric and asymmetric supercapacitor devices, they show promising results, with specific capacity values reaching up to 109 F/g for the symmetric and 609 F/g for the asymmetric devices, while energy and power density values reached 84.7 Wh/kg and 90.8 kW/kg respectively, proving a great potential in the energy storage field
Strategic autonomy in Turkish foreign policy in an age of multipolarity: lineages and contradictions of an idea
No full textStrategic autonomy has become a guiding principle for several states as the international order moves toward multipolarity. Turkey has also attempted to carve out a more autonomous space from its traditional Western allies by building new ties in the non-Western world, ranging from the Russia–China axis to the Middle East and beyond. This paper explores the idea and practice of strategic autonomy in Turkish foreign policy. We argue that strategic autonomy is not pre-determined or mechanically driven by ‘hedging’ behavior. We conceptualize strategic autonomy with reference to its three fundamental dimensions: structural orientation, political motive, and economic infrastructure. In this context, we highlight two soft spots in Turkish foreign policy since 2011. First, geopolitical imperatives and domestic policy priorities often contradict each other, which prevents the country from effectively implementing autonomy-seeking policies. Second, strategic autonomy is mainly associated with ‘high politics’ without paying proper attention to its geoeconomic dimension in the form of solid political economy fundamentals and economic security
Sustainable ion exchange-based remediation of per- and polyfluoroalkyl substances; recent progress and future prospects
No full textThis review presents recent advances and future directions in sustainable ion exchange (IEX)-based remediation of per- and polyfluoroalkyl substances (PFAS) in wastewater and freshwater. IEX resins demonstrate high efficiency in PFAS removal, either as standalone solutions or in combination with complementary techniques such as membrane filtration or activated carbon. Despite their effectiveness, challenges remain in enhancing PFAS selectivity, improving resin regenerability, and managing end-of-life options for spent resins and concentrated PFAS streams. In the context of PFAS selectivity, future research directions include investigating hydrophobic and hydrogen-bonding interactions in PFAS uptake, developing PFAS-selective resins, and examining the effects of inorganic anions on short-chain PFAS removal. Additionally, in the areas of regeneration and disposal methods for PFAS-laden IEX resins and PFAS-containing regeneration streams, innovative approaches such as thermal volatilization, oxidative treatments, advanced sonochemical techniques, and plasma treatments hold promise. Advancing these methods will be crucial for closing knowledge gaps and developing next-generation solutions for IEX-based PFAS remediation
Evaluation and performance optimization of a hydrogen peroxide-based green monopropellant thruster for steady-state operations
No full textHydrogen peroxide (High Test Peroxide, HTP) emerges as a promising candidate for green space propulsion applications due to its lower toxicity compared to liquid conventional propellants such as hydrazine and nitrogen tetroxide. This study aims to optimize the performance and reliability of HTP monopropellant thrusters, focusing on catalyst bed stability, efficiency, and durability during extended steady-state operations. Key parameters, including catalyst bed packing, pellet size, bed load, and HTP concentration, were investigated in this study for their impact on the steady-state performance, using the pressure loss across the catalyst bed as an indicator of catalyst deterioration. Results indicate that an optimal pressure drop of 1–1.5 bar across the catalyst bed provides optimal stability and durability. To evaluate transient characteristics, effects of bed load, HTP concentration, and pre-heating temperature on thruster response times were investigated. Following the optimization process, a lifetime test with an HTP throughput of 6 kg was conducted to monitor performance variations over time. Additionally, the blowdown characteristics of the thruster were analyzed to assess performance under end-of-life conditions. The experiments in this study demonstrate that HTP monopropellant thrusters are viable candidates for reliable space missions, particularly for long-duration operations such as station-keeping maneuvers
On torsion subgroups of elliptic curves over quartic, quintic and sextic number fields
No full textThe list of all groups that can appear as torsion subgroups of elliptic curves over number fields of degree d, d=4,5,6, is not completely determined. However, the list of groups Φ∞(d), d=4,5,6, that can be realized as torsion subgroups for infinitely many non-isomorphic elliptic curves over these fields is known. We address the question of which torsion subgroups can arise over a given number field of degree d. In fact, given G∈Φ∞(d) and a number field K of degree d, we give explicit criteria telling whether G is realized finitely or infinitely often over K. We also give results on the field with the smallest absolute value of its discriminant such that there exists an elliptic curve with torsion G. Finally, we give examples of number fields K of degree d, d=4,5,6, over which the Mordell-Weil rank of elliptic curves with prescribed torsion is bounded from above
Effect of Pinus radiata extract on the properties and performance of sodium alginate and kappa-carrageenan composite films
No full textComposite films of sodium alginate and kappa carrageenan (SAC) enriched with Pinus radiata bark extract (EnPBE) were fabricated using the casting method. The effects of varying EnPBE concentrations (0.1–1% v/v) on the SAC-based films were comprehensively evaluated. Assessments included surface color measurement, surface hydrophobicity, atomic force microscopy, transparency analysis, barrier properties, X-ray diffraction, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy and antioxidant analysis. Thermal properties were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, in-vitro release studies were performed to study the release behavior of the EnPBE. The findings revealed that increasing the EnPBE concentration led to a notable decrease in the swelling index and film transparency, while thickness, moisture content, water permeation, and flexibility increased. Color analysis revealed a significant increase in the red/green value (a*) and yellow/blue value (b*) of the films, consistent with visual observations. The water contact angle values decreased from 49.06° to 41.45° with the addition of EnPBE. Moreover, the release of the extract in both aqueous and methanolic environments showed a significant increase at higher concentrations. DPPH and ABTS antioxidant assays demonstrated a concentration-dependent increase in the free radical/cation scavenging capacity of the films. The surface roughness of the films increased with the addition of EnPBE, consistent with SEM results that showed particles on the surface of EnPBE-loaded films. TGA and DSC analyses demonstrated improved thermal stability of the films with the incorporation of EnPBE
Fake news in business and management literature: a systematic review of definitions, theories, methods and implications
No full textPurpose: This paper aims to conduct an interdisciplinary systematic literature review (SLR) of fake news research and to advance the socio-technical understanding of digital information practices and platforms in business and management studies. Design/methodology/approach: The paper applies a focused, SLR method to analyze articles on fake news in business and management journals from 2010 to 2020. Findings: The paper analyzes the definition, theoretical frameworks, methods and research gaps of fake news in the business and management domains. It also identifies some promising research opportunities for future scholars. Practical implications: The paper offers practical implications for various stakeholders who are affected by or involved in fake news dissemination, such as brands, consumers and policymakers. It provides recommendations to cope with the challenges and risks of fake news. Social implications: The paper discusses the social consequences and future threats of fake news, especially in relation to social networking and social media. It calls for more awareness and responsibility from online communities to prevent and combat fake news. Originality/value: The paper contributes to the literature on information management by showing the importance and consequences of fake news sharing for societies. It is among the frontier systematic reviews in the field that covers studies from different disciplines and focuses on business and management studies
Small-molecule RNA therapeutics to target prostate cancer
No full textTuning protein expression by targeting RNA structure using small molecules is an unexplored avenue for cancer treatment. To understand whether this vulnerability could be therapeutically targeted in the most lethal form of prostate cancer, castration-resistant prostate cancer (CRPC), we use a clinical small molecule, zotatifin, that targets the RNA helicase and translation factor eukaryotic initiation factor 4A (eIF4A). Zotatifin represses tumorigenesis in patient-derived and xenograft models and prolonged survival in vivo alongside hormone therapy. Genome-wide transcriptome, translatome, and proteomic analysis reveals two important translational targets: androgen receptor (AR), a key oncogene in CRPC, and hypoxia-inducible factor 1A (HIF1A), an essential cancer modulator in hypoxia. We solve the structure of the 5′ UTRs of these oncogenic mRNAs and strikingly observe complex structural remodeling of these select mRNAs by this small molecule. Remarkably, tumors treated with zotatifin become more sensitive to anti-androgen therapy and radiotherapy. Therefore, “translatome therapy” provides additional strategies to treat the deadliest cancers
Getting into top-ranked management journals from business schools at the periphery: the role of doctoral education and co-authorship
No full textDrawing upon recent extensions of the centre–periphery model, we examine research and publications by academics at the periphery within the present environment of increasing institutional pressures to publish internationally. Reviewing the emergence and the historical development of management as a discipline, we describe the fragmentation in approaches to research that has arisen in this field among countries that are typically considered as the ‘centre’ of worldwide scholarship. We propose and empirically demonstrate that the differentiation within the ‘centre’ becomes largely mirrored at the periphery with respect to attention to societal contexts, research methodology and publishing. Our companion argument that doctoral education in and/or co-authorship ties to various parts of the ‘centre’, or a lack thereof, serve as the main vehicles in generating heterogeneity and some degree of agency at the periphery receives strong support. We also find that when ties to the ‘centre’ are absent contributions from the periphery remain limited. In addition, we show that tendencies towards decontextualized research, quantitative methodologies and publishing in US-based journals have become stronger over time. The article concludes with a discussion of the theoretical contributions, main findings and the implications of our study for the possible futures of research at the periphery
Enhancing adhesive bonding and mechanical properties of composite sandwich panels through atmospheric plasma activation
No full textThis study investigates the effect of atmospheric plasma activation (APA) treatment on the thermomechanical performance of adhesively bonded skins of composite sandwich panels. The investigations show that APA treatment enhances surface wettability through the water contact angle measurements, and adhesion between the skin and honeycomb core of the panels under mechanical tests. Specifically, APA treatment results in an 11% increase in flatwise tensile strength and a 12% enhancement in the impact strength of the sandwich laminates. Flatwise tensile tests reveal superior tensile strength and toughness in APA-treated specimens, with fracture patterns suggesting more robust adhesion. Charpy impact test results confirm increased energy absorption, reflecting better mechanical resilience. Scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA) techniques are utilized to validate these findings. Overall, APA treatment proves to be an effective technique for enhancing the performance of composite sandwich panels, offering improved adhesion, strength, and impact resistance. This approach holds significant promise for advancing high-performance composite materials in various engineering applications. Highlights: APA treatment enhances wettability and adhesion in sandwich panels. Improved adhesive distribution between skin-core after sandwich manufacturing. 11% increase in tensile strength and 12% in impact strength with APA. Better toughness and energy absorption via SEM and DMA support in APA