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Effect of thulium substitution on conductivity and dielectric belongings of nanospinel cobalt ferrite

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Journal of Rare Earths 2020年第10期38卷 1103-1113,I0003页

作者： b.Unal M.A Almessiere A.demir Korkmaz Y.Slimani A.baykale Institute of Forensic Sciences and Legal Medicine Istanbul University-CerrahpasaBuyukcekmece CampusAlkent 2000BuyukcekmeceIstanbul 34500Turkey Department of biophysics.Institute for Research&Medical Consultations(IRMC) Imam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 198231441DammamSaudi Arabia Department of Chemistry Istanbul Medeniyet University34700 IstanbulUskudarTurkey Department of Nano-Medicine Research Institute for Research&Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 198231441 DammamSaudi Arabia

The CoTmx Fe2-x O4(x≤0.1) NPs were synthesized sonochemically.X-ray powder diffraction patterns and TEM images of the samples prove their chemical purity and cubic structure-morphology,*** substitution ratio of thulium ions to cobalt ferrites have an important effect on the characteristic evaluation of both electrical and dielectric characteristic measured at frequencies up to 3.0 MHz between room temperature and 120℃.Since the thulium substitution has a very strong effect on the characteristic evaluation of both electrical and dielectric properties of cobalt-ferrite samples,four substitutio nal ranges-none,small,medium and high were determined for the interpretation of contribution of thulium ratio to ac/dc conductivity,dielectric constant,dielectric loss and tangent *** increases with the incremental frequencies,in general depending on a variety of tendencies of both temperature and substitutional Tm ratios while the activation energy varies with a high dependency to the regional level of Tm substitution in Co-ferrites *** Arrhenius graph appears to provide us with a single activation energy much higher than 400 meV for x=0.02,which can be attributed to electron hopping mechanisms,apart from other substituted spinel ferrites.

关键词： Spinel ferrites Dielectric properties Conductivity CoFe2O4 Tm3+substitution Rare earths

Measurement of L X-Ray Intensity Ratios for^92U and ^90Th Elements Using Photoionization in an External Magnetic Field

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Chinese Physics Letters 2007年第3期24卷 668-671页

作者： D.demir Y. Sahin Department of Physics Faculty of Arts and Science Ataturk University 25240 Erzurum Turkey

L x-ray intensity ratios Le/Lγ, Lα/L7 and Lβ/Lγ for ^92U and ^90Th are measured by using 59.5keV incident photon energy at 110° and 125° scattering angles. The samples are located in the external magnetic field of intensities ±0.15T, ±0.30T, ±0.45T, ±0.60T and ±0.75T. The experimental results obtained for b = 0 are compared with the theoretical values calculated using Scofield＇s tables based on the Hartree Slater theory. The contribution to the alignment of the external magnetic field is discussed. It is observed that the L x-ray intensity ratios decrease with the increasing magnetic field intensity.

关键词： PHOTOIONIZATION MAGNETIC fields PHOTONS SCATTERING (Physics) NUMERICAL calculations HARTREE-Fock approximation

Electrical and dielectric properties of Ni_(0.5)Co_(0.5)Ga_(x)Fe_(1.8-x)O_(4)(x≤1.0)spinel ferrite microspheres

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Journal of Rare Earths 2023年第2期41卷 259-267页

作者： S.Akhtar M.A.Almessiere b.Unal A.demir Korkmaz Y.Slimani N.Tashkandi A.baykal A.Ul-Hamid A.Manikandan Department of biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Institute of Forensic Sciences and Legal Medicine Istanbul University-CerrahpasaBuyukcekmece CampusBuyukcekmece-Istanbul34500Turkey Department of Chemistry Istanbul Medeniyet UniversityUskudar/Istanbul34700Turkey Department of Nanomedicine Research Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Core Research Facilities King Fahd University of Petroleum&MineralsDhahran13261Saudi Arabia Department of Chemistry Bharath Institute of Higher Education and Research(BIHER)Bharath UniversityChennaiTamil Nadu600073India Center for Catalysis and Renewable Energy Bharath Institute of Higher Education and Research(BIHER)ChennaiTamil Nadu600073India

Microspheres of Ni_(0.5)Co_(0.5)Ga_(x)Fe_(2-x)O_(4)(x≤1.0)microsphere spinel ferrites(NiCoGaFe-MSFs)and carbon spheres were prepared via a hydrothermal *** micro structure of microspheres was investigated through scanning and transmission electron microscopy(SEM and TEM),respectively,and X-ray diffraction(XRD).The electrical and dielectric properties of NiCoGaFe-MSF at temperatures ranging from20 to 120℃(between 293,1×10^(3)and 393.1×10^(3))for f≤3.0 MHz were systematically studied as a result of 3D graphical drawing of the data obtained from an impedance *** parameters such as ac/dc conductivity,dielectric loss,dielectric constant,activation energy,dissipation factor and Cole-Cole impedance spectra were extensively evaluated for various Ga ion mole ratios in the substitution where x≤*** notice that the ac conductivity mostly obeys exponential power law rules,which vary significantly with the substitution ratios of Ga *** analyses confirm that differences in conduction mechanisms in NiCoGaFe-MSFs are mainly due to grain-to-grain boundaries related to Ga ion substitution *** change in dielectric constant of NiCoGaFe-MSFs is strongly dependent on the substitution rates and results in a normal dielectric distribution with *** tangential loss for all micro spheres is observed to vary with measured temperatures and their frequency dependencies can be attributed to the conduction mechanism similar to Koop’s phenomenological *** is clearly seen that the formation of semicircles is dominated by all the NiCoGaFe-MSFs and the diameter of the semicircles mostly decreases with increasing temperature,as evidence of a temperaturedependent relaxation mechanism.

关键词： Spinel ferrites Microspheres Electrical properties Ac/dc conductivity Dielectric properties Rare earths

Fabrication of coconut shell-derived porous carbons for CO_(2) adsorption application

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Frontiers of Chemical Science and Engineering 2023年第8期17卷 1122-1130页

作者： Jiali bai Jiamei Huang Qiyun Yu Muslum demir Eda Akgul bilge Nazli Altay Xin Hu Linlin Wang Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Zhejiang Normal UniversityJinhua 321004China Department of Chemical Engineering Osmaniye Korkut Ata UniversityOsmaniye 80000Turkey College of Engineering Technology Print and Graphic Media ScienceRochester Institute of TechnologyNew York 14623USA Institute of Pure and Applied Sciences Marmara UniversityIstanbul 34722Turkey Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology and Equipment of Zhejiang Province College of EngineeringZhejiang Normal UniversityJinhua 321004China

biomass-derived porous carbons have been considered as the most potential candidate for effective CO_(2) adsorbent thanks to being widely-available precursor and having highly porous structure and stable chemical/physical ***,the biomass-derived porous carbons still suffer from the poor optimization process in terms of the synthesis ***,we have successfully fabricated coconut shell-derived porous carbon by a simple one-step synthesis *** as-prepared carbon exhibits advanced textual activity together with well-designed micropore morphology and possesses oxygen-containing functional groups(reached 18.81 wt%)within the carbon *** on the different activating temperatures(from 700 to 800℃)and KOH/biomass mass ratios(from 0.3 to 1),the 750℃ and 0.5 mass ratio were found to be enabling the highest CO_(2) capture *** optimal adsorbent was achieved a high CO_(2) uptake capacity of 5.92 and 4.15 mmol·g^(−1) at 0 and 25℃(1 bar),*** importantly,as-prepared carbon adsorbent exhibited moderate isosteric heat of adsorption and high CO_(2)/N_(2) *** results were revealed not only the textural feature but also the surface functional groups critically determine the CO_(2) capture performance,indicating coconut shell-derived porous carbon has a considerable potential as a solid-state adsorbent for the CO_(2) capture.

关键词： porous carbons CO_(2)adsorption KOH activation single step reaction biomass

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Pain sensation in pancreatic diseases is not uniform: The different facets of pancreatic pain

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World Journal of Gastroenterology 2014年第27期20卷 9154-9161页

作者： Jan G D'Haese Mark Hartel Ihsan Ekin demir Ulf Hinz Frank bergmann Markus W büchler Helmut Friess Güralp O Ceyhan Department of Surgery Klinikum Rechts der Isar Technische Universit?t München Unit for Documentation and Statistics Department of General Surgery University of Heidelberg Institute of Pathology University of Heidelberg Department of General Surgery University of Heidelberg

AIM: To systematically characterize specific pain patterns in the most frequent pancreatic diseases.

关键词： Abdominal pain Pancreatic neoplasm Chronic pancreatitis Intraductal papillary mucinous neoplasia Pancreatic cancer

Interaction between seed size and NaCl on germination and early seedling growth of some Turkish cultivars of chickpea(Cicer arietinum L.)

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Journal of Zhejiang University-Science b(biomedicine & biotechnology) 2008年第5期9卷 371-377页

作者： Muharrem KAYA Gamze KAYA Mehmet demir KAYA Mehmet ATAK Sevil SAGLAM Khalid Mahmood KHAWAR Cemalettin Yasar CIFTCI Department of Field Crops Faculty of AgricultureSuleyman Demirel University Central Research Institute for Field Crops Ministry of Agriculture and Rural Affairs Department of Field Crops Faculty of AgricultureMustafa Kemal University Department of Field Crops Faculty of AgricultureUniversity of Ankara

Chickpea is an important food legume crop of Turkey and is largely grown for human consumption on low moisture or salt-affected soils. The objective of the study was to find the effects of NaCl stress at electrical conductivities of 4.5, 8.6, 12.7 and 16.3 dS/m and seed sizes （7, 8 and 9 mm） on germination and early seedling growth of three popular chickpea cultivars （AKN-97, Gokce and Uzunlu-99）. Mean frequency of germination, germination time, germination index, root length, shoot length and seedling fresh weight showed seed size-dependent responses ofcultivars to salt stress. In general, small seeds germinated and grew more rapidly compared to medium and large seeds of the same cultivars against all levels of salt stress, with the best results in cultivar Uzunlu-99. No effect of NaCl treatments was observed on frequency of germination; however, a drastic decrease in early seedling growth was recorded at increased NaC1 concentrations. Regression analysis results showed a significantly positive relationship （P〈0.01） between seed size and mean germination time, whereas a significantly negative relationship was recorded between seed size and germination index, root length, shoot length. Moreover, linear regression values apparently confirmed that increased seed size in each cultivar affected decreased germination index, root and shoot lengths with enhanced mean germination time. Thus, it was concluded that the use of small seeds could considerably reduce the production costs of chickpea in salt-affected soils.

关键词： Chickpea (Cicer arietinum L.) NaCl stress Cultivar Seed size Germination

Structural,morphological and magnetic properties of(Ni_(0.5)Co_(0.5))[Ga_(x)Gd_(x)Fe_(2-2x)]O_(4)nanoparticles prepared via sonochemical approach

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Journal of Rare Earths 2023年第4期41卷 561-571页

作者： Y.Slimani M.A.Almessiere A.demir Korkmaz A.baykal M.A.Gondal H.Güngünes Sagar E.Shirsath A.Manikandan Department of biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Department of Chemistry Istanbul Medeniyet UniversityUskudarIstanbul34700Turkey Department of Nanomedicine Research Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Laser Research Group Physics DepartmentIRC-Hydrogen&Energy StorageKing Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia K.A.CARE Energy Research and Innovation Center King Fahd University of Petroleum&MineralsDhahran 31261Saudi Arabia Department of Physics Hitit University19030Cevre Yolu BulvarCorumTurkey School of Materials Science and Engineering University of New South WalesKensingtonSydneyNSW2052Australia Department of Chemistry Bharath Institute of Higher Education and Research(BIHER)Bharath UniversityChennaiTamil Nadu600073India Center for Catalysis and Renewable Energy Bharath Institute of Higher Education and Research(BIHER)ChennaiTamil Nadu600073India

The impact of Ga^(3+)and Gd^(3+)co-substitution on different types of behavior of Ni-Co nanospinel ferrites(NSFs),(Ni_(0.5)Co_(0.5))[Ga_(x)Gd_(x)Fe_(2-2x)]O_(4)(0.000≤x≤0.025),was *** were fabricated through ultrasound *** structure,composition,and spherical morphology of all products were verified by numerous characterization techniques such as X-ray diffraction(XRD),scanning and transmission electron microscopes(SEM and TEM),and selected area electron diffraction(SAED).Mossbauer spectra are composed of two ferromagnetic sextets and one paramagnetic *** spectra were fitted to extract hyperfine parameters of the doped *** sublattices'hyperfine magnetic field decreases with *** isomer shift values show that the Mossbauer spectra are composed of magnetic Fe^(3+)*** magnetization measurements at variable magnetic field(M-H)were investigated via a vibrating sample magnetometer(VSM)at temperatures(T)from 300 to 10 *** NSFs disclose ferrimagnetic behavior at both 300 and 10 K at which they are soft and hard,*** determined that the remanence magnetization(M_(r)),saturation magnetization(M_(s)),and magneton number(n_(b))decrease with increasing Ga^(3+)and Gd^(3+)ions *** reduction in these values is predominantly recognized to be the impact of cation redistribution and surface spins on tetrahedral(T_(d))and octahedral(O_(h))*** the Ga^(3+)and Gd^(3+)contents increase,the coercivity(H_(c))is also found to decrease.

关键词： Spinel ferrites Rare earth substitution Sonochemical synthesis Mossbauer analysis Magnetic properties

Intrahepatic and peripheral T-cell responses in genotype 1b hepatitis C virus-infected patients with persistently normal and elevated aminotransferase levels

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World Journal of Gastroenterology 2005年第45期11卷 7188-7191页

作者： Filiz Akyüz Nuray Polat Sabahattin Kaymakoglu Nevzat Aksoy Kadir demir Fatih besisik Selim badur Yilmaz Cakaloglu Atilla (O|¨)kten Department of Gastroenterohepatology Department of Microbiology

AIM： To evaluate whether the cytokine responses in liver and serum differ in chronic hepatitis C patients with normal and high alanine aminotransferase （ALT） levels. METHODS： Thirty-three （16 with normal ALT level as group 1 and 17 with elevated ALT level as group 2） patients infected with genotype lb hepatitis C virus （HCV） were examined. Liver infiltrating lymphomononuclear cells （LILMCs） were isolated from liver biopsy by collagenase type 1 and stimulated with phytohemagglutinin and interleukin 2 （IL-2）. IL-10, IL-12, interferon gamma （IFN-γ） and tumor necrosis factor alpha （TNF-α were determined in serum and LILMCs by ELISA. RESULTS： Serum cytokine levels were similar in both groups （P〉0.05）. Stimulated IFN-γ and TNF-α levels in LILMCs were increased in both groups. IL-12 and IL-10 levels stimulated with IL-2 were higher in group 1 than in group 2 （P = 0.023）. Histological activity index （HAI） and stage had a negative correlation with TNF-α and IFN-γ levels in group 2. CONCLUSION： Increased T-helper type 2 （Th2） cytokine response may regress inflammatory and biochemical activity. Progression of histological abnormalities in persons with elevated ALT probably depends on insufficient Th2 cytokine response, which does not balance Th1 cytokine response.

关键词： Liver cytokines HCV, ALT

Sweet plasmonics： Sucrose macrocrystals of metal nanoparticles

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Nano Research 2015年第3期8卷 860-869页

作者： Talha Erdem Zeliha Soran-Erdem Pedro Ludwig Hernandez-Martinez Vijay Kumar Sharma Halil Akcali Ibrahim Akcali Nikolai Gaponik Alexander Eychmeller Hilmi Volkan demir Departments of Electrical and Electronics Engineering Physics UNAM-National Nanotechnology Research Center and Institute ot Materials Science and Nanotechnology Bilkent University Ankara 06800 Turkey School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences Nanyang Technological University Singapore 639798 Singapore Physical Chemistry TU Dresden Bergstrasse 66b D-O 1062 Dresden Germany

The realization of plasmonic structures generally necessitates expensive fabrication techniques, such as electron beam and focused ion beam lithography, allowing for the top-down fabrication of low-dimensional structures. Another approach to make plasmonic structures in a bottom-up fashion is colloidal synthesis, which is convenient for liquid-state applications or very thin solid films where aggregation problems are an important challenge. The architectures prepared using these methods are typically not robust enough for easy handling and convenient integration. Therefore, developing a new plasmonic robust platform having large-scale dimensions without adversely affecting the plasmonic features is in high demand. As a solution, here we present a new plasmonic composite structure consisting of gold nanoparticles （Au NPs） incorporated into sucrose macrocrystals on a large scale, while preserving the plasmonic nature of the Au NPs and providing robustness in handling at the same time. As a proof of concept demonstration, we present the fluorescence enhancement of green CdTe quantum dots （QDs） via plasmonic coupling with these Au NPs in the sucrose crystals. The obtained composite material exhibits centimeter scale dimensions and the resulting quantum efficiency （QE） is enhanced via the interplay between the Au NPs and CdTe QDs by 58% （from 24% to 38%）. Moreover, a shortening in the photoluminescence lifetime from 11.0 to 7.40 ns, which corresponds to a field enhancement factor of 2.4, is observed upon the introduction of Au NPs into the QD incorporated macrocrystals. These results suggest that such ＂sweet＂ plasmonic crystals are promising for large-scale robust platforms to embed plasmonic nanoparticles.

关键词： plasmonics macrocrystals metal nanoparticles metal enhancedfluorescence colloidal quantum dots