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Digital economy and carbon dioxide emissions:Examining the role of threshold variables

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Geoscience Frontiers 2024年第3期15卷 389-400页

作者： Qiang Wang Jiayi sun Ugur Korkut Pata Rongrong Li Mustafa Tevfik kartal school of Economics and Management China University of Petroleum(East China)Qingdao 266580China Osmaniye Korkut Ata University Faculty of Economics and Administrative sciences Department of EconomicsMerkez80000 OsmaniyeTurkey Department of Banking and Finance European University of LefkeLefkeNorthern CyprusTR-10 MersinTürkiye Adnan Kassar school of Business Lebanese American UniversityBeirutLebanon Department of Economics and Management Khazar UniversityBakuAzerbaijan

Considering that previous literature has mainly focused on the impact of the digital economy(DE)on environmental degradation,ignoring the role of natural resources,this study uses two key factors(natural resource rent and anticorruption regulation)as threshold variables to reveal the effect of natural resources on the association between DE and carbon dioxide(CO_(2))*** doing so,the study covers 97 countries,uses annual data between 2003 and 2019,and applies a panel threshold *** outcomes present that the influence of the DE on CO_(2)emissions has a single-threshold effect(i.e.,there is an inverted U-shaped link between the DE and CO_(2)emissions)when natural resource rent is the threshold ***,the DE significantly increases CO_(2)emissions when the natural resource rent is at a low-to-medium level,but the DE suppresses CO_(2)emissions growth when natural resource rent exceeds the ***,the DE drives overall CO_(2)emissions growth when anticorruption regulation is the threshold variable and there are double thresholds for its impact on CO_(2)***,a rise in anticorruption regulation initially exacerbates the contribution of DE impact on CO_(2)emissions and then weakens it over *** on the results,the study proposes various implications,such as formulating a DE development strategy,considering natural resources in the development of the DE,and strengthening anti-corruption efforts in the field of environmental protection.

关键词： Digital economy Natural resource rent Anticorruption regulation CO_(2)emissions Threshold regression

The role of disaggregated renewable energy consumption on income and load capacity factor:A novel inclusive sustainable growth approach

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Geoscience Frontiers 2024年第1期15卷 39-49页

作者： Ugur Korkut Pata Qiang Wang Mustafa Tevfik kartal Arshian sharif Osmaniye Korkut Ata University Faculty of Economics and Administrative SciencesDepartment of EconomicsMerkez80000 OsmaniyeTurkey Adnan Kassar school of Business Lebanese American UniversityBeirutLebanon school of Economics and Management China University of Petroleum(East China)Qingdao 266580People’s Republic of China Borsa Istanbul strategic Planning Financial Reportingand Investor Relations Directorate34467İstanbulTurkey sunway University Department of Economics&Finance Subang JayaMalaysia University of Economics and Human sciences in Warsaw WarsawPoland

stimulating renewable energy consumption is a major focus of the sustainable Development Goals in combating climate change and global *** International Energy Agency estimates that renewable energy consumption should be doubled to achieve the COP21 *** this context,the question is whether renewable energy types promote the improvement of ecological quality and economic *** studies have investigated the influence of renewable energy on ecological pollution using carbon dioxide emissions or ecological footprint indicators,which only represent the pollution caused by human consumption patterns,and these indicators neglect the supply *** by this point,this study uses the LCF(Load Capacity Factor)as an environmental indicator and examines the causality relationship among different types of renewable energy,income,and environmental quality in the UsA,while also incorporating employment and capital stock into the *** using the Fourier causality test with the wavelet-decomposed series,the study explores for the validity of the renewable energy-based growth hypothesis and answers to the question of whether there is a causal effect of renewable energy types on environmental *** results demonstrate that there is a bidirectional causality between total renewable energy,wood,biomass,and economic growth as well as between these renewable energy types and the LCF.

关键词： Load capacity factor Economic growth Renewable energy Fourier approximation Emvironmental quality

Complex dynamics of COVID-19 mathematical model on Erdos-Rényi network

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生物数学学报:英文版 2023年第5期16卷 193-215页

作者： Neriman kartal senol kartal Department of science and Mathematics Education Faculty of Education Nevsehir Haci Bektas Veli University Nevsehir 50300Turkey

In this study,a conformable fractional order Lotka-Volterra predator-prey model that describes the COVID-19 dynamics is *** using a piecewise constant approximation,a discretization method,which transforms the conformable fractional-order differential equation into a difference equation,is *** conditions for ensuring the stability of the equilibrium points of the discrete system are determined by using schur-Cohn *** analysis shows that the discrete system exhibits Neimark-sacker bifurcation around the positive equilibrium point with respect to changing the parameter d and *** Lyapunov exponents show the complex dynamics of the discrete *** addition,the COVID-19 mathematical model consisting of healthy and infected populations is also studied on the Erdos Rényi *** the coupling strength reaches the critical value,then transition from nonchaotic to chaotic state is observed in complex dynamical ***,it has been observed that the dynamical network tends to exhibit chaotic behavior earlier when the number of nodes and edges *** these theoretical results are interpreted biologically and supported by numerical simulations.

关键词： Piecewise constant arguments difference equation stability Neimark-sacker bifurcation complex network

Performance of fluoride and boron compounds against drywood and subterranean termites and decay and mold fungi

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Journal of Forestry Research 2020年第4期31卷 1425-1434页

作者： s.nam. kartal Evren Terzi Tsuyoshi Yoshimura Faculty of Forestry Istanbul University-Cerrahpas¸a34473 BahcekoyIstanbulTurkey RIsH Kyoto UniversityUjiKyoto 611-1100Japan

sodium fluoride(NaF)and disodium octaborate tetrahydrate(DOT)are well-known fungicides for preventing and remediating decay in wood and wood structures,due to their excellent diffusion properties in *** efficacy of both compounds against drywood termites is,however,inadequately studied;there is a lack of information on the development of proper protection and control methods against drywood termites using these diffusible *** this study,the threshold values of fluoride and boron against drywood and subterranean termites and decay and mold fungi were assessed in laboratory *** Cryptomeria japonica ***(sugi)sapwood specimens with four different concentrations of NaF and DOT applied by either dipping or vacuum processes were subjected to attack by drywood termites,Incisitermes minor(Hagen)for 6 *** specimens were also tested against subterranean termites,Coptotermes formosanus shiraki for 3 *** decay and mold resistance tests were then performed to determine the efficacy of the compounds against fungal *** showed 80%or greater drywood termite mortality in wood specimens treated with NaF at a retention level of1.7 kg m-3 or *** DOT treated groups,higher retention levels(greater than 6.8 kg m-3)were needed to reach up to 80%or more termite *** general,weight losses in NaF-treated specimens were slightly lower than those in DOT-treated *** levels of around1.2 kg m-3 for NaF and 1.6 kg m-3 for DOT were high enough to reach the JIs K 1571 threshold requirement of weight loss less than 3%in subterranean termite resistance *** higher termite mortality values were seen in the DOT than NaF treatments at respective retention *** decay resistance tests,no weight losses were seen at a NaF retention level of 2.3 kg m-3;however,a retention level of nearly 4 kg m-3 for DOT was needed for complete protection against both test *** most cases,lower weight losses were obtained i

关键词： NaF DOT Remedial treatments Termites Fungi

Direct electrochemical reduction of copper sulfide in molten borax

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International Journal of Minerals,Metallurgy and Materials 2019年第8期26卷 992-998页

作者： Levent kartal servet Timur Department of Metallurgical and Materials Engineering Hitit UniversityCorum 19030Turkey Department of Metallurgical and Materials Engineering Istanbul Technical UniversityIstanbul 34469Turkey

In this study,for the first time,direct copper production from copper sulfide was carried out via direct electrochemical reduction method using inexpensive and stable molten borax *** effects of current density(100–800 mA/cm^2)and electrolysis time(15–90 min)on both the cathodic current efficiency and copper yield were systematically investigated in consideration of possible electrochemical/chemical reactions at 1200℃.The copper production yield reached 98.09%after 90 min of electrolysis at a current density of 600 mA/cm^*** metal production was shown to be possible with 6 kWh/kg energy consumption at a 600 mA/cm2 current density,at which the highest current efficiency(41%)was *** suggested method can also be applied to metal/alloy production from single-and mixed-metal sulfides coming from primary production and precipitated sulfides,which are produced in the mining and metallurgical industries during treatment of process solutions or wastewaters.

关键词： molten salt electrolysis electro-reduction copper extraction copper sulfide borax

One-step electrochemical reduction of stibnite concentrate in molten borax

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International Journal of Minerals,Metallurgy and Materials 2019年第10期26卷 1258-1265页

作者： Levent kartal Mehmet Baris Daryal Güldem kartal sireli servet Timur Department of Metallurgical and Materials Engineering Hitit UniversityCorum 19030Turkey Department of Metallurgical and Materials Engineering Istanbul Technical UniversityIstanbul 34469Turkey

In this study,antimony production from a stibnite concentrate(sb2s3)was performed in one step using a molten salt electrolysis method and borax as an *** reduction of the stibnite concentrate was performed at 800℃under galvanostatic conditions and explained in detail by the reactions and intermediate compounds formed in the *** effects of current density(100 800 mA cm^-2)and electrolysis time(10 40 min)on cathodic current efficiency and antimony yields were systematically *** the highest current efficiency,which was obtained at 600 mA cm^-2,direct metal production was possible with 62%cathodic current efficiency and approximately 6 kWh/kg energy *** the end of the 40-min electrolysis duration at 600 mA cm^-2 current density,antimony reduction reached 30.7 g and 99%of the antimony fed to the cell was obtained as metal.

关键词： molten salt electrolysis electrochemical reduction antimony antimony extraction stibnite borax

Multiple bifurcations in an early brain tumor model with piecewise constant arguments

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International Journal of Biomathematics 2018年第4期11卷 197-215页

作者： senol kartal Department of science and Mathematics Education Nevsehir Haci Bektas Veli University Nevsehir 50300 Turkey

In this paper, a differential equation with piecewise constant arguments modeling an early brain tumor growth is considered. The discretization process in the interval t ∈ [n, n＋1） leads to two-dimensional discrete dynamical system. By using the schur-Cohn criterion, stability conditions of the positive equilibrium point of the system are obtained. Choosing appropriate bifurcation parameter, the existence of Neimark-sacker and flip bifurcations is verified. In addition, the direction and stability of the Neimark-sacker and flip bifurcations are determined by using the normal form and center manifold theory. Finally, the Lyapunov exponents are numerically computed to characterize the complexity of the dynamical behaviors of the system.

关键词： Piecewise constant arguments difference equation stability flip andNeimark sacker bifurcations Lyapunov exponents.

Biological performance,water absorption,and swelling of wood treated with nano-particles combined with the application of Paraloid B72~

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Journal of Forestry Research 2017年第2期28卷 381-394页

作者： Damla Muhcu Evren Terzi s.nam. kartal Tsuyoshi Yoshimura Department of Forest Biology and Wood Protection Technology Faculty of ForestryIstanbul University Laboratory of Innovative Humano-habitability Research Institute for Sustainable Humanosphere (RISH)Kyoto University

We evaluated fungal decay and mold resistance,leaching, and water absorption of nano-compounds and Paraloid B72-（PB72） in treated wood specimens to develop new methods of consolidation by combining nanoparticles and consolidants. scots pine wood specimens were treated with dispersions of nano-Cu O, nano-Zn O,nano-B2O3, nano-Ti O2, and nano-Ce O2. PB72 treatments of nano-particle-treated wood specimens were then carried out by either vacuum or immersion for 24 h. Previously,decayed wood specimens were also consolidated with the nano-compounds and PB72. PB72 treatments reduced element release from treated wood specimens. Nearly all nano-compounds ？ PB72 treatments increased the biological performance of treated wood specimens against decay fungi tested. PB72-only treated wood specimens had the highest weight losses in decay tests. No improvements were obtained in mold resistance tests when the nanocompounds and PB72 were combined. In nano-compoundonly treatments, unleached specimens showed slightly lower water absorption values compared to untreated control specimens. Incorporation of PB72 into nano-compound-treated wood specimens resulted in considerably lower water absorption and volumetric swell. In previously decayed specimens treated with the nano-compounds and PB72 solution, water absorption after 2-h immersion declined compared to control specimens.

关键词： leaching declined untreated retention fungi versicolor fungal fungus leached decay

Biological performance of particleboard incorporated with boron minerals

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Journal of Forestry Research 2017年第1期28卷 195-203页

作者： Evren Terzi s.nam. kartal Philippe Gerardin Claudia Marcela Ibanez Tsuyoshi Yoshimura Department of Forest Biology and Wood Protection Technology Faculty of ForestryIstanbul University34473 BahcekoyIstanbulTurkey Faculte des sciences et Technologies Universite de Lorraine54506 Vandoeuvre-les-Nancy CedexFrance Unidad Academica de Gestion Tecnologica Departamento TecnologicoFacultad de QuimicaUniversidad de la Republica UruguayMontevideoUruguay Laboratory of Innovative Humano-Habitability Research Institute for Sustainable Humanosphere(RISH)Kyoto UniversityUjiKyoto 611-0011Japan

We compared resistance to decay, mold fungi, termites and insect larvae of particleboards incorporated with the raw boron minerals ulexite and colemanite to that of particleboards impregnated with the commercial boron preservative zinc borate, or boric acid plus a borax mixture. We also quantified water absorption, thickness swell and boron release of particleboards. Ulexite had the best decay resistance, and colemanite had the best termite resistance. However, ulexite and colemanite were not as effective as zinc borate or the boric acid/borax mixture in preventing mold growth. In general, the boric acid/borax mixture combination was more effective against Anobium larvae than the other treatments. Less boron was released by specimens containing zinc borate and colemanite than by those containing ulexite or the boric acid/borax mixture. In general, water absorption and thickness swell were similar among the different treatments, but both were slightly higher in the ulexite-incorporated specimens. Further mechanical tests will be needed to evaluate the particle- board properties and thereby the compatibility of these boron minerals with various manufacturing processes.

关键词： Biological resistance Borax Boric acid Colemanite Particleboard Ulexite