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31.
Fatma Kiliç Dokan 《International Journal of Applied Ceramic Technology》2022,19(3):1756-1765
This work reports the combined effect of the morphology and crystallization to investigate the role of Yb3+ as an additive in Li4Ti5O12 crystals on its photocatalytic and photoluminescence (PL) properties. With the pure phase, the synthesized samples have a spherical morphology and spherical structure with good crystallinity and uniform particle size distribution. Li4Ti5O12 doped with ytterbium (Yb3+), were obtained by a new optimized hydrothermal approach. The crystal properties and surface morphology of the synthesized compounds were examined by X-ray diffraction method and field emission scanning electron microscopy. Bond structures and surface areas were investigated by Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller analyses. Finally, the excitation and emission spectra were obtained by a PL spectrophotometer. The PL results show that room-temperature PL of Yb3+ doped Li4Ti5O12 phosphor has an emission peak at 710 nm which can be attributed to Li4Ti5O12 crystal defect emission. Moreover, it has been found that Yb doping resulted in enhancement of photocatalytic activity, evaluated by monitoring the degradation of methylene blue solution. Note that, 0.01% Yb doped lithium titania phosphor exhibited excellent photocatalytic activity. 相似文献
32.
Fatma H. Abd El-Salam 《Journal of surfactants and detergents》2009,12(4):363-370
New gemini anionic surfactants were prepared from sodium salts of monoalkyl sulfosuccinate esters of ethylene glycol having
variably long tails (C12, C16, C18) and dichloroethane. The chemical structures of the prepared surfactants were confirmed using different spectroscopic techniques.
The surfaces tension values of the synthesized surfactants were measured at 25 °C individually or mixing at different molar
fractions with ethoxylated alkylphenol. In all cases, mixed micellar aggregates were formed and critical micellar concentrations
of binary mixtures containing different mole fractions of the surfactants were measured. The micellization processes of the
individual and mixed surfactants were investigated. The effect of different alkyl chains of gemini anionic surfactants on
properties of binary systems and molar ratio in the mixed aggregates were deduced. The critical micelle concentration of mixed
surfactants shifted to lower values compared to those of the single surfactants. Effectiveness values increased with decreases
in the mole fraction of gemini anionic surfactants. The negative values of interaction parameter (β) increased with increases
in the chain length of anionic surfactants. The activity coefficient (f
1, f
2) and total minimum surface area of mixed solution were calculated. Also, the gemini anionic surfactants prepared have moderate
antimicrobial activity towards bacteria and not active towards fungi. 相似文献
33.
Blends based on various compositions of low‐density polyethylene (LDPE) and plasticized starch (PLST) were prepared by melt extrusion and molding in the form of sheets under hot press. The rheology properties during mixing were studied in terms of torque and temperature against mixing time. The structural properties of LDPE/PLST blends before and after electron beam irradiation was characterized by IR spectroscopy, tensile mechanical testing, and scanning electron microscopy (SEM). The torque‐time curves during the mixing process showed that the values of torque in the first region of mixing for pure LDPE or LDPE/PLST blends are higher in the presence of the compatibilizer PEMA than that in the presence of EVA. In addition, the stability of mixing was attained after a short time in the presence of PEMA. The IR spectroscopy suggests that the compatibilization by EVA and PEMA compounds proceeds through the formation of hydrogen bonding during mixing and this compatibility was improved after electron beam irradiation. The stress–strain curves of pure LDPE and its blends with PLST showed the behavior of tough polymers with yielding properties. The SEM micrographs of the fracture surfaces give supports to the effect of EVA and PEMA as compatibilizers and the effect of electron beam irradiation. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers 相似文献
34.
Fatma Karipcin Bülent Dede Sabriye Percin-Ozkorucuklu Eser Kabalcilar 《Dyes and Pigments》2010,84(1):14-18
Manganese(II), cobalt(II) and nickel(II) acetates react with the ligand, 4-(2-thiazolylazo)resorcinol, to form complexes of general formula [ML2] for MCo(II), Ni(II) and [ML2]·2H2O for MMn(II). Each of the azo complexes was characterized using elemental analysis, electrolytic conductance, UV–visible spectroscopy and magnetic susceptibility. An octahedral structure is proposed for all complexes prepared, which molar conductance data revealed to be non-electrolytes. IR spectra reveal that the ligand is coordinated to the metal ions in a tridentate manner via the resorcinol OH, azo N and thiazole N groups as donor sites. The electrochemical behaviour of the ligand and its complexes were obtained by cyclic voltammetry. Thermal decomposition studies were undertaken to secure additional information on the structure of the investigated compounds. The manganese(II) complex catalysed the disproportionation of hydrogen peroxide in the presence of imidazole. 相似文献
35.
Oguzhan Oguz Nicolas Candau Adrien Demongeot Mehmet Kerem Citak Fatma Nalan Cetin Grégory Stoclet Véronique Michaud Yusuf Z. Menceloglu 《Polymer Engineering and Science》2021,61(4):1028-1040
There is currently considerable interest in developing stiff, strong, tough, and heat resistant poly(lactide) (PLA) based materials with improved melt elasticity in response to the increasing demand for sustainable plastics. However, simultaneous optimization of stiffness, strength, and toughness is a challenge for any material, and commercial PLA is well-known to be inherently brittle and temperature-sensitive and to show poor melt elasticity. In this study, we report that high-shear mixing with cellulose nanocrystals (CNC) leads to significant improvements in the toughness, heat resistance, and melt elasticity of PLA while further enhancing its already outstanding room temperature stiffness and strength. This is evidenced by (i) one-fold increase in the elastic modulus (6.48 GPa), (ii) 43% increase in the tensile strength (87.1 MPa), (iii) one-fold increase in the strain at break (∼6%), (iv) two-fold increase in the impact strength (44.2 kJ/m2), (v) 113-fold increase in the storage modulus at 90°C (787.8 MPa), and (vi) 103-fold increase in the melt elasticity at 190°C and 1 rad/s (∼105 Pa) via the addition of 30 wt% CNC. It is hence possible to produce industrially viable, stiff, strong, tough, and heat resistant green materials with improved melt elasticity through high-shear mixing. 相似文献
36.
37.
Nermin Tansuğ Muzaffer Polat Selcan Çeşme Fatma Taneli Salih Gözmen Özlem Tokuşoğlu Dilek Yılmaz Gönül Dinç 《Nutrition journal》2010,9(1):34
Background
Vitamin A deficiency is a major public health nutrition problem in the developing world. Even subclinical Vitamin A deficiency is associated with increased childhood mortality. Severe maternal vitamin A deficiency may cause increased mortality in the first months of life. There have been a limited number of studies regarding vitamin A status in Turkey. The aim of this study was to assess vitamin A status of healthy children in Manisa, Turkey. 相似文献38.
39.
Ahmed E. Awadallah Fatma Kh. Gad Ateyya A. Aboul-Enein Mahmoud R. Labib Ahmed K. Aboul-Gheit 《Egyptian Journal of Petroleum》2013,22(1):27-34
A commercial hydrotreating nickel molybdate/alumina catalyst was used for the direct conversion of natural gas (NG) into COx-free hydrogen and a co-valuable product of multi-walled carbon nanotubes (MWCNTs). The catalytic runs were carried out atmospherically in a fixed-bed flow reactor. The effect of reaction temperature between 600 and 800 °C, and dilution of the NG feed with nitrogen as well as pretreatment of the catalyst with hydrogen were investigated. At a reaction temperature of 700 °C and dilution ratio of NG/N2 = 20/30, the optimum yield of H2 (~80%) was obtained with higher longevity. However, using the feed ratio of NG/N2 = 30/20, the optimum yield of MWCNTs was obtained (669%). X-ray diffraction pattern for the catalyst after the reaction showed that the MWCNTs were grown on the catalyst at all reaction temperatures under study. TEM pictures revealed that the as-grown MWCNTs at 600, 650 and 800 °C are short and long with a low graphitization degree. At 700 °C a forest of condensed CNTs is formed, whereas both carbon nanofibers and CNTs were formed at 750 °C. 相似文献
40.
Fatma Tosun Çiğdem Akyüz Kızılay Kevser Erol Fatma Sultan Kılıç Mine Kürkçüoğlu Kemal Hüsnü Can Başer 《Food chemistry》2008
The anticonvulsant activity of furanocoumarins, coumarin mixture and the essential oil obtained from the fruits of Heracleum crenatifolium was examined against maximal electroshock (MES)-induced seizures in mice. Bergapten showed significant anticonvulsant activity. The furanocoumarins isolated from the fruits of the plant were identified using thin-layer chromatography, melting points and spectroscopic methods (IR, MS, 1H NMR) as isobergapten (1), pimpinellin (2), bergapten (3), isopimpinellin (4), sphondin (5) and byak-angelicol (6). The essential oil content of the fruits were found as 5.5%. Twenty-two compounds representing 99.3% of the essential oil obtained from the fruits of H. crenatifolium were determined and the major components were identified as octanol and octyl acetate (3.1% and 88.4% respectively) by GC and GC–MS. 相似文献