Different Concentrations Of Ce Research Articles

Cerium improves the vase life of Lilium longiflorum cut flowers through ascorbate-glutathione cycle and osmoregulation in the petals

Abstract The present study investigated the role of cerium nitrate (Ce(NO3)3) in regulating the ascorbate-glutathione (AsA-GSH) cycle, the relative water content (RWC), and the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2), soluble sugar and proline in the petals, and the contents of chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoids (Car) in the leaves of Lilium longiflorum cut flowers. The findings showed that Ce(NO3)3 markedly improved the activities of ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR), the ratios of AsA/DHA and GSH/GSSG, RWC, and the contents of proline and soluble sugar in the petals, and markedly reduced the contents of MDA and H2O2 in the petals, compared with the control. Meanwhile, Ce(NO3)3 markedly improved the contents of Chl a, Chl b and Car in the leaves. Among different concentrations of Ce(NO3)3, 40 μM Ce(NO3)3 is the most effective treatment for the improvement of the vase life of Lilium longiflorum cut flowers. Above results indicated that Ce(NO3)3 improves the vase life of Lilium longiflorum cut flowers by enhancing the AsA-GSH cycle and water retaining capacity.

Photoluminescence and radioluminescence properties of (Gd8Ca2)(SiO4)6O2 crystals with different concentrations of Ce

(Gd8Ca2)(SiO4)6O2 apatite crystals doped with different concentrations of Ce were synthesized by the Floating Zone (FZ) method, and we have evaluated the photoluminescence (PL) and radioluminescence (RL) properties. In PL, an emission band appeared around 400 nm under excitation at 300 nm due to the 5d-4f transitions of Ce3+. The PL decay curves were approximated by a second-order exponential decay function, and the derived decay time constants ranged around 20–25 ns and 40–480 ns. Similar emission was observed in RL, but the decay time constants were much longer than those in PL. The RL afterglow was the lowest in the 1.0% Ce-doped sample. The 1.0% and 2.0% Ce-doped samples showed a full-energy peak in the pulse height spectrum measured under 241Am 5.5 MeV α-ray irradiation, and the absolute scintillation light yields were estimated to be around 55 and 36 ph/5.5 MeV-α, respectively.

Luminescence studies of zinc borates activated with different concentrations of Ce and La under x-ray and electron excitation

Several ZnB2O4 powder samples having dopants concentrations of 0.1, 0.01, 0.04wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL) techniques were used. Unique luminescence properties of Ce doped ZnB2O4 powder samples are reported for the first time. A new luminescence bands appearing in red part of the spectrum and having all the characteristics of Ce3+ were obtained from RL results. Changing the Ce and La concentration of 0.01–0.1wt% leads to an increase in RL and CL intensities of Ce3+ and La3+ ions and also CL emission spectra of ZnB2O4 show gradual shift towards longer wavelength. When we compare the luminescence intensity of the samples it is seen that Ce doped ZnB2O4 has the highest intense whereas La doped ZnB2O4 has the lowest one. However, emission spectra of both Ce and La doped samples kept unchanged.

Scintillation properties of Ce-doped Tb3Al5O12

Tb3Al5O12 (TbAG) crystalline materials doped with different concentrations of Ce were prepared by the floating zone (FZ) method to evaluate their basic optical and scintillation properties. In photoluminescence (PL), a broad emission due to the 5d-4f f transition of Ce3+ appeared around 550 nm, and the decay time was approximately 40 ns. Under X-ray irradiation, the scintillation due to the 5d-4f transition of Ce3+ was also observed around 550 nm, but the decay time appeared to be much longer 376–599 ns than that of PL and it depended on the concentration of Ce. The pulse height spectroscopy analyses revealed that 3.0% Ce-doped TbAG showed the highest light yield of 30,100 ph/MeV under 137Cs γ-ray irradiation among the samples investigated in this work.

EFFECT OF CE3+ METAL IONS ON THE ANTIBACTERIAL AND ANTICANCER ACTIVITY OF ZINC OXIDE NANOPARTICLES PREPARED BY COPRECIPITATION METHOD

ABSTRACTObjective: This study was undertaken to know about the antibacterial and anticancer activity of synthesized zinc oxide (ZnO) nanoparticles (NPs).Methods: The ZnO NPs and different concentration of Ce3+ (0.05M, 0.10M, and 0.15M)-doped ZnO NPs were synthesized by coprecipitation method.The synthesized nanoparticles were analyzed by X-ray diffraction (XRD) and HRSEM. The antibacterial studies were performed against a set ofbacterial strains as Gram-positive bacteria (Streptococcus aureus and Streptococcus pneumonia) and Gram-negative (Escherichia coli, Pseudomonasaeruginosa, Proteus vulgaris, Klebsiella pneumonia, and Shigella dysenteriae) bacteria. The cytotoxic effect of ZnO and Ce-doped ZnO was analyzed incultured (A549) human lung cancer cell line.Result: The XRD studies showed the wurtzite structure of nanoparticles. HRSEM analysis showed the spherical shape of ZnO and Ce-doped ZnO. TheZn0.85Ce0.15O NPs possessed more antibacterial effect as compared to the other ZnO and Ce-doped ZnO NPs. The Zn0.90Ce0.10O NPs created the highestcytotoxicity activity. With respect to cell death, as low a concentration of 68±0.05 μg/ml of Zn0.90Ce0.10O NPs was good enough to cause loss of viabilityof 50% of the cell as compared to ZnO and Zn1-xCexO (x=0.05 and 0.15) NPs.Conclusion: Results from this work concluded that Zn0.85Ce0.15O and Zn0.90Ce0.10O NPs possess antibacterial and anticancer activity, respectively.Keywords: Zinc oxide nanoparticles, Coprecipitation method, Antibacterial activity and anticancer activity, Human lung cancer cell line.

Scintillation, TSL and OSL properties of Ce-doped 30Zn3(PO4)2-70Al(PO3)3 glasses

In this study, we have synthesized 30Zn3(PO4)2-70Al(PO3)3 glass samples doped with different concentrations of Ce (0, 0.1, 0.3, 1.0, and 3.0 mol%) by the conventional melt quenching method, and we have evaluated the optical, scintillation and dosimeter properties such as thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL). The photoluminescence (PL) spectrum showed an intense emission band due to the 5d–4f transitions of Ce3+ ion peaking at 330 nm as well as a weak emission due to the host at 440 nm. The decay times of corresponding emissions were 20–24 ns and 7 ns, respectively. The scintillation emissions also showed intense emissions at 330 and 440 nm due to the Ce3+ ion and host, and the decay times were 7–13 ns and 31–35 ns, respectively. The TSL glow peaks were observed mainly around 150–190 °C for Ce-doped samples while the non-doped sample showed a glow peak around 300–400 °C. The TSL intensity increases with increasing the X-ray dose delivered, and the dose response curve showed a good linearity over the dose range of 0.01–10 Gy. The OSL was observed around 330 nm during the stimulation at 410 nm.

Preparation and photocatalytic property of Ce3+-doped titanium dioxide nanotubes

ABSTRACTTo enhance the photocatalytic efficiency of TiO2, different concentration of Ce3+-doped TiO2 nanotubes were prepared using a sol-gel method combined with a hydrothermal process. After being calcined at 450°C, the morphology, composition, and crystal structures were investigated by SEM, TEM, XRD, and EDS. The samples' photocatalytic performance was characterized by degrading methylene blue under illumination of a 250 W UV-light. The result showed that both ends of the nanotubes were ringent and consisted of many layers. Their length could reach to hundred nanometers and the thickness of the walls was about 9 nm. The low-concentration Ce3+ did not influence the nanostructure and crystal structure but has a large correlation with the photocatalytic efficiency. The sample with the concentration of 1.5% performed best in photocatalytic reaction.

Evaluation of Ce:SrAl2O4 crystalline scintillators

In this study, Ce-doped SrAl2O4 (Ce:SrAl2O4) crystals were prepared by a floating zone (FZ) method and experimental evaluations were performed for scintillator applications. In photoluminescence (PL) with an excitation around 320nm, an intense broad emission peak appears around 380nm due to the 5d-4f transitions. The PL decay time constants are approximately 30ns. The X-ray induced scintillation spectrum also shows an intense broad emission peak around 380nm. Among the samples evaluated with different concentrations of Ce, the absolute light yield under 137Cs is considerably high (∼3900ph/MeV) when the concentration of Ce is 1.0%. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 110, 210 and 330°C. The samples also shows optically stimulated luminescence (OSL) after X-ray irradiation, in which the emission appears around 380nm due to the 5d-4f emission bands of Ce3+ while the samples is exposed to the stimulation light at 655nm.

The color tuning and mechanism of upconversion emission from green to red in NaLuF4:Yb3+/Ho3+ nanocrystals by codoping with Ce3+

The upconversion (UC) luminescence nanocrystals of hexagonal phase NaLuF4:Yb3+/Ho3+ were prepared by a solvothermal process at 300 °C. The visible upconversion emission from green to red in Yb3+ and Ho3+ codoped β-NaLuF4 nanoparticles is successfully achieved by tridoping with Ce3+ ions (0–12 mol%) and the red emission intensity is enhanced gradually with the increasing Ce3+ concentration. In this work, results of XRD, SEM, EDS and TRES upconversion data demonstrate that Ce3+ ions are successfully incorporated into NaLuF4:Yb3+/Ho3+ nanoparticles. UC emissions at 541 nm and 644 nm of all prepared nanoparticles under 980 nm excitation correspond to the transitions of 5S2/5F4 → 5I8 and 5F5 → 5I8 of Ho3+ ions respectively. The decay curves of 541 nm emission under 980 nm pulse excitation are detected. The 541 nm emission decays fast when Ce3+ concentration increases. All results show that tuning from green to red upconversion can be realized in NaLuF4:Yb3+/Ho3+ nanocrystals via tridoping with different concentration of Ce3+ ions.

Structural and optical properties of SrS nanophosphors influenced by Ce3+ ions concentrations and particle size reduction

The SrS nanophosphors doped with different concentrations of Ce3+ are synthesized by solid state diffusion method (SSDM). Various characterization and spectral studies are reported in the light of varied dopant concentrations and reduction in particle size by milling. The as-obtained phosphors are characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) including selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopic (EDX) studies. The FESEM and HRTEM results explain the surface morphology, agglomeration of particles, crystallite size, etc. The results of XRD studies confirm the cubic structure of most intense SrS: Ce3+ nanophosphors and exhibit wider diffraction peaks for 4h milled sample. The EDX profiles are used to authenticate the occurrence of different starting materials in final products. Upon excitation with UV light (375nm), two emission peaks are observed at around 459nm and 551nm due to transitions of electrons from the 2T2g(5d)→2F5/2(4f) and 2T2g(5d)→2F7/2(4f) energy levels. The afterglow decay behavior of different SrS: Ce3+ nanophosphors is presented and discussed systematically.

UV ray-induced thermoluminescence study of Y2SiO5:Ce3+ phosphor

This paper reports thermoluminescence (TL) properties of Ce 3? doped yttrium silicate phosphor. The phosphor is synthesized by a solid state reaction method which is suitable for large scale production. Starting materials used for sample preparation were Y2O3, SiO2 ,C eO2 and a fixed concentration of boric acid used as a flux. The prepared phosphors for different concentrations of Ce 3? were examined by observing their TL glow curves for UV irradiation (254-nm source). The samples show a well resolved broad peak covering a temperature range of 50-375 C. The kinetic parameters such as activation energy, order of kinetics and frequency factor were calculated by the peak shape method. Most of the peaks show general order kinetics. The effect of UV exposure on TL was also examined and a linear response to dose was shown, indicating the sample may be useful for a TL dosimeter. The kinetic parameters were calculated using a computerized glow curve de-convolution (CGCD) technique.

Influence of Ce2O3 and CeO2 promoters on Pd/MgO catalysts in the dry-reforming of methane

In this study, the conversion of methane and CO2 to synthesis gas using dry reforming over Pd/MgO catalysts using different concentrations of Ce3+ and Ce4+ was investigated.

Effect of the Pt oxidation state and Ce3+/Ce4+ ratio on the Pt/TiO2-CeO2 catalysts in the phenol degradation by catalytic wet air oxidation (CWAO)

Pt/TiO2-Ce catalysts were synthesized with different concentrations of Ce at 1, 3, 5 and 10wt% for being used in catalytic wet air oxidation (CWAO) of aqueous solution of phenol (1000ppm). The supports were prepared by sol–gel and impregnated to 2.5wt% of Pt. The catalysts were characterized by different techniques: specific surface areas (BET), ICP-OES, XRD, pyridine-FTIR, X-ray photoelectron spectroscopy (XPS), CO-FTIR, TPO and transmission electron microscopy (TEM). Phenol oxidation was realized in a batch reactor at 160°C and 10bar of O2. Samples taken during the reaction course were analyzed using a total organic carbon analyzer (TOC) and gas chromatography (GC). The results showed that the specific surface areas of the Pt/TiO2-Ce catalysts increased with Ce content. By XPS it was found that a ratio of Pt0/Pt2+ and Ce3+/Ce4+ of 55%/45% and 71%/29% in Pt/TiO2-Ce3% catalyst showing the highest phenol conversion (96%) and selectivity to CO2 (100%). The Pt/TiO2-Ce3% and the Pt/TiO2-Ce5% catalysts presented the lowest Pt particle size, around 3.7–5.8nm leading to high activity (96% and 92% respectively). They displayed the high Lewis acid sites and good stability to deposits of carbonaceous species on the catalysts. The responsible of the good performance of these catalysts is related to the addition to CeO2 to TiO2 that produces an increase in the oxygen storage capacity (OSC) in these catalysts.

Photoluminescence properties of Ce3+-doped SrAl2O4 prepared using the solution combustion method

SrAl2O4:Ce3+ phosphors were synthesized using the solution combustion method at a temperature of 500°C. The Ce3+ ion concentration was varied from 0.25 to 2mol%. X-ray powder diffraction (XRD) patterns exhibited the same main peaks for the lower dopant concentrations of Ce3+, and the average crystallite size was between 40nm and 43nm. The SrAl2O4:Ce3+ included a monoclinic phase. Scanning electron microscopy images revealed agglomerated particles as well as plate-like particles. Photoluminescence results demonstrated that the intensity decreased for Ce3+ concentrations up to 1mol% and then increased again due to the formation of a second phase Sr3Al2O6. The emission peaks for the different concentrations of Ce3+ consists of two peaks situated at 356nm and 380nm corresponding to the 2F7/2 and 2F5/2 transitions.

Thermoluminescence characteristics of Na3 SO4 Cl:X (X=Ce, Dy, Mn) phosphor

In the present paper Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, of Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphor were synthesized by the wet chemical method. Thermoluminescence (TL) characteristics of Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphors were studied for 5 Gy γ-ray dose. In TL glow curve, two peaks have been observed at 129°C and 224°C for different concentrations of Ce and Dy, whereas Mn peaks at 212°C. The same host is also tried for Ce, Dy (peaks at 126, 219) and Ce, Mn (248°C). A significant single peak is observed in the case of Na3SO4Cl:Mn and Na3SO4Cl:Ce, Mn. This may be due to the effect of activators. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.39 kGy h−1 for 5 Gy γ-rays dose. It is also found that all the phosphors are less sensitive as compared with Thermoluminescence dosimetry-CaSO4: Dy for the same γ-rays dose. The paper discuses the preliminary TL characteristics and effect of γ-rays on Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphors.

Microcalorimetric studies of the effect of cerium (Ш) on isolated rice mitochondria fed by pyruvate

Mitochondria were isolated from the hybrid rice Xiangzaoxian 31, then the effects of low and high concentrations of Ce (Ш) on metabolism of mitochondria fed by pyruvate were investigated respectively, by microcalorimetry and oxygen electrode method The thermogenic curve of mitochondria without Ce (Ш) could be divided into three parts: activity recovery phase, stationary phase and decline phase. And the thermokinetic parameters have been calculated through the metabolic thermogenic curves. With addition of different concentrations of Ce (Ш), the results demonstrated that low levels of cerium ion stimulated the metabolic activity of energized mitochondria and the inhibition was discovered with high concentrations of Ce (Ш). At the same time, it is shown that the effect in respiration correspond to the effect on mitochondrial metabolism on addition of different concentrations of Ce (Ш). Moreover, the addition of low and high concentrations of Ce (Ш) had no obvious effect on the total heat output (Q). The concentration-dependent effect of Ce (Ш) on metabolism of mitochondria is similar to plant growth response to rare earth elements (Hormesis effect).

Influence of Ce Doping on the Electrical and Optical Properties of TiO2and Its Photocatalytic Activity for the Degradation of Remazol Brilliant Blue R

Nanocrystalline TiO2particles doped with different concentrations of Cerium (Ce, 1–10%) have been synthesized using sol-gel method. The prepared particles were characterized by standard analytical techniques such as X-ray diffraction (XRD), FTIR and Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The XRD analysis shows no change in crystal structure of TiO2after doping with different concentrations of Ce, which indicates the single-phase polycrystalline material. The SEM analysis shows the partial crystalline nature of undoped, and doped TiO2and TEM analysis shows the particle sizes were in the range of 9–14 nm in size. The a.c. analysis shows that the dielectric constantεand dielectric loss tanδdecrease with the increase in frequency. The dielectric property decreases with the increase in dopant concentration. It is also observed that the impedance increases with an increase in dopant concentration. The photocatalytic activity of the synthesized particles (Ce-doped TiO2) with dopant concentration of 9% (Ce) showed the highest photocatalytic activity for the degradation of the dye derivative Remazol Brilliant Blue R in an immersion well photochemical reactor with 500 W halogen linear lamp in the presence of atmospheric oxygen.

Influence of an aqueous extract of Coriandrum sativum leaves on the labeling of blood constituents with technetium-99m and determination of some of its physical parameters

Coriandrum sativum (coriander) extract (leaves) (CE) is used to treat diabetes, dyspepsia, loss of appetite, seizures, insomnia, and anxiety. In the investigations about the effects of a plant extract, it is important to determine some of its physicochemical parameters. Red blood cells labeled with technetium-99m (99mTc) is used in nuclear medicine as well as in experimental models in basic research. The aim of this work was to determine some physicochemical parameters of an aqueous extract of CE and its effect on the labeling of blood constituents with 99mTc. Determinations of the absorption spectrum (AS), electric conductivity (EC), and pH have been performed using different concentrations of CE. Results showed that CE had a maximum absorbance at 480 nm. EC was inversely correlated with the concentration. We found the highest value of pH at the lower concentration of the extract (0.05 mg/ml). There was no significant (P>0.05) alteration on the labeling of the blood constituents with 99mTc. In conclusion, physicochemical parameters could be useful to characterize the CE studied. Probably, the redox properties associated with the substances of this extract could be responsible by the absence of effect on the labeling of blood constituents with 99mTc. Key words: Coriandrum sativum, coriander, labeling, technetium-99m, physicochemical parameters, blood.

Correlation between mechanoluminescence and lyoluminescence in gamma-irradiated KBr:Ce3+ phosphor for radiation dosimetry

Abstract Comparative study of mechanoluminescence (ML) and the lyoluminescence (LL) of γ-irradiated coloured powder of KBr:Ce3+ (0.1–10 mol%) phosphor is reported in this paper. Correlation between mechanoluminescence and lyoluminescence is observed, based on the formed colour centre due to γ-irradiation. All samples were prepared by a wet-chemical method. Single isolated ML and LL glow curve is observed in all samples. The variation of peak ML and LL intensities with gamma rays exposure and with different concentration of Ce3+ doped in KBr:Ce3+ is studied. The ML and LL intensities are found to be dependant on concentrations of Ce3+ and gamma radiation dose. The variation of peak ML and LL intensities of KBr:Ce3+ (0.5 mol%) with different gamma dose is found to be sublinear upto 1.5 kGy high dose and then the intensity becomes saturated. Negligible fading in the prepared sample is observed.

Mechanoluminescence characterization of γ-rays irradiated NaBr:Ce3+ phosphor for ionising radiation dosimetry

The mechanoluminescence (ML) of γ-irradiated coloured powder of NaBr:Ce(0.1–10 mol%) phosphor are reported in this paper and compared with pure NaBr material. All samples were prepared by wet-chemical method. Single isolated ML glow curve is observed in all samples. The variation of peak ML intensity with gamma exposure and with different concentration of Ce3+ doped, in NaBr:Ce are studied. ML intensities are found to be dependant on concentrations of Ce3+ and gamma radiation dose. The variation of peak ML intensity of NaBr:Ce(0.5 mol%) with different gamma dose is found as sublinear up to 2.5 kGy high dose of γ-irradiation.