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1.
《Ceramics International》2020,46(15):24194-24203
In this article, we have reported an effective, rapid as well as economical Er3+ substituted Ni0.4Co0.6Fe2O4 ferrite nanoparticles synthesized via surfactant-assisted co-precipitation route. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), dielectric properties, current-voltage (I–V) measurements, and vibrating sample magnetometry (VSM). XRD and FTIR confirmed the face-centered (FCC) spinel structure of all compositions of the synthesized spinel ferrite nanoparticles. The deviations in the lattice constant granted with the variation in size of the guest (Er3+) and host (Fe3+) cations. These ferrites were also subjected for electrical, magnetic and dielectric investigations. I–V measurements showed that resistivity values decreased from 6.20 × 107 Ω cm to 0.03 × 107 Ω cm with the increased Er3+ contents. Saturation magnetization increased from 35.99 to 39.95 emu/g. This high value of saturation magnetization suggested the possible utilization of such ferrites for practical applications such as microwave and recording devices fabrication. Interestingly, the magnetic and dielectric properties of nickel-cobalt ferrite nanoparticles showed ample improvement upon Er3+ substitution. The results clearly indicate the potential of Er+3 substituted spinel ferrite particles in various advanced technological devices fabrication. 相似文献
2.
P. Khemthong W. Klysubun S. Prayoonpokarach F. Roessner J. Wittayakun 《Journal of Industrial and Engineering Chemistry》2010,16(4):531-538
This work investigated reducibility of cobalt species in monometallic Co/NaY and bimetallic CoPt/NaY catalysts with various Co loading (1, 6 and 10 wt.%) and fixed Pt loading (1 wt.%). The form and environment of Co species after reduction was determined by X-ray absorption spectroscopy including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The cobalt species in the mono- and bimetallic catalyst with Co loading of 1 wt.% was not reducible whereas those with Co loading of 6 and 10 wt.% were partially reduced. The extent of reduction increased with Co loading and enhanced by the presence of Pt. Catalytic performance for n-butane hydrogenolysis mono- and bimetallic catalysts were compared. The higher extent of Co reduction in 6CoPt/NaY and 10CoPt/NaY resulted in higher conversions than the monometallic counterpart. Sequential hydrogenolysis was favored on the monometallic catalysts because methane was the only product. The presence of Pt suppressed such reaction resulting in ethane and propane. The effect of Pt on such effect was most prominent in 6CoPt/NaY. 相似文献
3.
Neda Khorshidi 《分离科学与技术》2016,51(10):1675-1683
A new aeration-assisted homogeneous liquid–liquid microextraction using high-density solvent for determination of copper, nickel and cobalt, as a prior step to their determination, coupled to flame atomic absorption spectrometry is presented. Under the optimum conditions, the calibration graphs were linear in the range of 5.0–600.0 ng/mL for copper, 10.0–450.0 ng/mL for nickel and 8.0–500.0 ng/mL for cobalt. The limits of detection were 1.3, 3.6 and 2.7 ng/mL and the enrichment factor estimated to be 350, 340 and 360, for copper, nickel and cobalt, respectively. The proposed method was successfully applied for the determination of these cations in different samples. 相似文献
4.
Majid Darroudi Zahra Sabouri Reza Kazemi Oskuee Ali Khorsand Zak Hadi Kargar Mohamad Hasnul Naim Abd Hamid 《Ceramics International》2013,39(8):9195-9199
The use of plant extract in the synthesis of nanomaterials can be a cost effective and eco-friendly approach. In this work we report the “green” and biosynthesis of zinc oxide nanoparticles (ZnO-NPs) using gum tragacanth. Spherical ZnO-NPs were synthesized at different calcination temperatures. Transmission electron microscopy (TEM) imaging showed the formation most of nanoparticles in the size range of below 50 nm. The powder X-ray diffraction (PXRD) analysis revealed wurtzite hexagonal ZnO with preferential orientation in (101) reflection plane. In vitro cytotoxicity studies on neuro2A cells showed a dose dependent toxicity with non-toxic effect of concentration below 2 µg/mL. The synthesized ZnO-NPs using gum tragacanth were found to be comparable to those obtained from conventional reduction methods using hazardous polymers or surfactants and this method can be an excellent alternative for the synthesis of ZnO-NPs using biomaterials. 相似文献
5.
In this work the results of a TPR and XPS investigation of CoxOy–CuO mixed oxides in the range of composition Co : Cu=100:0–8:92 are reported and compared. The final catalysts were obtained by thermal decomposition in air and N2 at 723 K for 24 h of singlephase cobalt–copper hydroxycarbonates prepared by coprecipitation at constant pH. The Co : Cu=100 : 0 specimen calcined in air formed the Co2+[Co3]2O4 (Co3O4) spinel phase. The coppercontaining catalysts (Co : Cu=85 : 15–8 : 92) showed mainly two phases: (i) spinels, like Co2+[Co3+]2O4, Co
1-x
2+
Cu
x
2+
[Co3+]2O4 and (ii) pure CuO, the relative amount of each phase depending on the Co : Cu atomic ratio. The results of the XPS study are consistent with the bulk findings and revealed the presence of Co2+, Co3+ and Cu2+ species at the catalyst surface. Moreover, the surface quantitative analysis evidenced a cobalt enrichment, in particular for the most diluted cobalt samples. The TPR study showed that the catalyst reduction is affected by a strong mutual influence between cobalt and copper. The reducibility of the mixed oxide catalysts was always promoted with respect to that of the pure Co3O4 and CuO phases and the reduction of cobalt was markedly enhanced by the presence of copper. Cobalt and copper were both reduced to metals regardless of the catalyst composition. On the other hand, the Co : Cu=100 : 0 specimen calcined in N2 formed, as expected, CoO. The initial addition of copper resulted in the formation of the Cu+Co3+O2 compound, besides CoO, up to a Co/Cu=1 atomic ratio at which the CuCoO2 phase was the main component. A further addition of copper led to the formation of CuCoO2 and CuO phases. The XPS results were in good agreement with these findings and the surface quantitative analysis revealed a less enrichment of cobalt with respect to the catalysts calcined in air. The TPR analysis confirmed that the reduction of the N2calcined catalysts was also remarkably promoted by the presence of copper. Also in this case cobalt and copper metal were the final products of reduction. 相似文献
6.
LiNi1?yCoyO2 (y = 0.1, 0.3 and 0.5) were synthesized by solid state reaction method at 800 °C and 850 °C from Li2CO3, NiO and CoCO3 as starting materials. The electrochemical properties of the synthesized LiNi1?yCoyO2 were investigated. As the content of Co decreases, particle size decreases rapidly and particle size gets more homogeneous. When the particle size is compared at the same composition, the particles synthesized at 850 °C are larger than those synthesized at 800 °C. Among LiNi1?yCoyO2 (y = 0.1, 0.3 and 0.5) synthesized at 850 °C, LiNi0.7Co0.3O2 has the largest intercalated and deintercalated Li quantity Δx at the first charge–discharge cycle, followed in order by LiNi0.9Co0.1O2 and LiNi0.5Co0.5O2. LiNi0.7Co0.3O2 synthesized at 850 °C has the largest first discharge capacity (142 mAh/g), followed in order by LiNi0.9Co0.1O2 synthesized at 850 °C (113 mAh/g), and LiNi0.5Co0.5O2 synthesized at 800 °C (109 mAh/g). 相似文献
7.
Savita Khare Priti Shrivastava Rajendra Chokhare Jagat Singh Kirar Swati Parashar 《Journal of Porous Materials》2017,24(4):855-866
Metal–salen intercalated α-zirconium phosphate, abbreviated as {α-ZrP·M(Salen), where M = Fe(III) and Mn(II)} was synthesized insitu by the flexible ligand method. The structure of resulting compounds was characterized by BET surface area, powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis and UV–visible spectroscopy. The catalytic activity of α-ZrP·M(Salen) was tested for the oxidation of cyclohexane using dry tert-butylhydroperoxide as an oxidant. In the oxidation reaction, cyclohexane was oxidized to cyclohexanol (A), cyclohexanone (K) and some unidentified products. It was found that the reactivity of α-ZrP·Fe(Salen) is greater than α-ZrP·Mn(Salen) in the oxidation reaction. Influence of various reaction parameters viz. reaction temperature, catalyst concentration, substrate to oxidant molar ratio was studied using α-ZrP·Fe(Salen) catalyst to obtain maximum conversion (29.30%) of cyclohexane. The catalyst was reused for five cycles without significant loss of catalytic activity. 相似文献
8.
《Inorganic chemistry communications》2008,11(10):1159-1161
Thin films of halide free Cu–Co mixed metal oxide have been prepared at 390 °C from the heterobimetallic complex Co4(THF)4(TFA)8(μ-OH)2Cu2(dmae)2 · 0.5C7H8 (1) [dmae = N,N-dimethylaminoethanol ((CH3)2NCH2CH2O−), TFA = triflouroacetate (CF3COO−), THF = tetrahydrofurane (C4H8O)] which was prepared by the reaction of [Cu(dmae)Cl]4 and Co(TFA)2 · 4H2O. The precursor was characterized for its melting point, elemental composition, FTIR and X-ray single crystal structure determination. Thin films grown on glass substrate by using AACVD out of complex 1 were characterized by XRD and SEM. TGA and AACVD experiments reveal it to be a suitable precursor for the deposition of halide free Cu–Co mixed-metal oxide thin films at relatively low temperatures. 相似文献
9.
《Inorganic chemistry communications》2000,3(6):322-324
The copper(II) complex [Cu(salgly)(bpy)]·4H2O (1), where salgly is a tridentate glycinatosalicylaldimine Schiff base ligand, is prepared and structurally characterized. The complex is found to be catalytically active in the oxidation of ascorbic acid by dioxygen and the process is also effective in the presence of benzylamine giving benzaldehyde as a product, thus modeling the activity of the CuB site of dopamine β-hydroxylase. 相似文献
10.
We studied the separation and recovery of copper(Ⅱ), nickel(Ⅱ), cobalt(Ⅱ), zinc(Ⅱ), and cadmium(Ⅱ) from magnesium and calcium, using synergistic solvent extraction(SSX) in a typical hydrometallurgical waste solution. A mixture of Versatic 10 acid and Mextral 984 H, diluted with Mextral DT100, was used to obtain fundamental data on p H and distribution isotherms, as well as the kinetics of extraction and stripping. We also investigated the main effects and interactions of common solvent extraction factors: the extraction p H at equilibrium, the temperature, and the extractant concentration. The synergistic effect for extracting metals was confirmed. The results showed that the addition of Mextral 984 H enhanced the separation factors of copper, nickel, cobalt,zinc, and cadmium over magnesium and calcium. Compared with Versatic 10 acid alone, for a mixture of0.5 mol·L~(-1) Versatic 10 acid/0.5 mol·L~(-1)Mextral 984 H, Δp H50 values of copper, nickel, cobalt, zinc, and cadmium were found to be N 2.0, 3.30, 2.85, 0.95, and 1.32 p H units, respectively. The Δp H_(50)(Zn–Mg)and Δp H_(50)(Zn–Ca)values were 3.27 and 2.25, respectively, indicating easy separation and recovery of copper, nickel, zinc, cobalt,and cadmium. The extraction and stripping of copper, cobalt, zinc, and cadmium were fast, with 90% of the metal transferred in 2 min. We next studied whether the metals could be stripped from the extracted liquid selectively in sequence, by using sulfuric acid at different concentrations. The influence of the molecular structure of the oxime and carboxylic acid components upon the synergistic effects was identified by numerical analysis.Excellent separation of copper, nickel, cobalt, and zinc over magnesium and calcium was achieved with this synergistic solvent extraction system. 相似文献
11.
Narendar Nasani Srinivas R. Gavinola Vanessa Graca Amarnath R. Allu Raghu C. Reddy Bharat B. Kale 《Journal of the American Ceramic Society》2021,104(11):5689-5697
The ABO3 type perovskite oxide-based ceramic membranes are one of the most important classes of materials for high-temperature solid oxide fuel cell applications. The acceptor-doped calcium titanate (CaTiO3) perovskite has attracted considerable attention as an oxide ion-conducting membrane due to its potentially high ionic conductivity and excellent stability. Nonetheless, the ionic conductivity of the material must still be improved. Following the strategy of the substitution of dopants on the B-site, the current work is focused on exploring the effect of Al and Ni additions on electrical properties, by studying the nominal compositions CaTi0.7Al0.3–xNixO3−δ (x = 0, 0.1, 0.2 and 0.3). The materials were synthesized by the sol–gel method and studied as a function of phase composition, microstructure, and electrical properties. The results demonstrate an increase of both total and specific grain boundary conductivity with increasing Ni content, while predominant p-type behavior is shown under oxygen-rich atmosphere. 相似文献
12.
Eui Yong Bang Daniel R. Mumm Hye Ryoung Park Myoung Youp Song 《Ceramics International》2012,38(7):5699-5705
LiNi1?yCoyO2 (y = 0.1, 0.3 and 0.5) cathode materials were synthesized by the solid-state reaction method at different temperatures from LiOH·H2O, NiO and Co3O4 and from Li2CO3, NiO and Co3O4 as the starting materials. The physical and electrochemical properties of the synthesized samples were then compared. Among LiNi1?yCoyO2 (y = 0.1, 0.3 and 0.5) synthesized for 40 h from LiOH·H2O, NiO and Co3O4, and from Li2CO3, NiO and Co3O4, LiNi0.5Co0.5O2 synthesized from Li2CO3, NiO and Co3O4 at 800 °C has relatively large first discharge capacity and relatively good cycling performance. This sample is considered the best one with relatively good electrochemical properties. 相似文献
13.
Pd–Pb/α-Al2O3 catalysts were prepared by reacting PbBu4 with supported palladium samples derived from Pd(AcAc)2, both in the presence and absence of hydrogen. The amount of lead fixed depends mainly on the concentration of palladium
on the metal–support boundary. In the presence of hydrogen, all butyl groups are released during the anchoring process. When
the Pd/α-Al2O3 was reduced and then purged with nitrogen, two butyl groups remained attached to the lead atom and a stable surface complex
was formed. The analysis of gaseous products evolved during the PbBu4–Pd/α-Al2O3 interaction and subsequent temperature‐programmed reaction experiments indicate that a (]‐L)2–Pb(Bu)3 complex was obtained. Upon reduction at 573 K, the Pd–Pb/α-Al2O3 catalysts became very selective for the hydrogenation of acetylene in the presence of ethylene.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
T. B. Mikenas V. A. Zakharov V. E. Nikitin L. G. Echevskaya M. A. Matsko 《Catalysis in Industry》2011,3(2):122-127
Summarized results are presented from studying the formation of the active component of supported Ziegler type catalysts,
investigating the effect of the composition of these catalysts on the molecular mass characteristics of PE, and seeking new
methods for producing catalysts with optimum morphology. 相似文献
15.
James Thomson 《Catalysis Letters》1996,40(1-2):119-121
1,1,1,2-tetrafluoroethane has been prepared at 473 K under static conditions, from a feedstock of carbon tetrachloride, dichloromethane and anhydrous hydrogen fluoride using a-alumina supported fluorinated Co(II, III)85Fe(II, III)15Ox catalyst. Conversion to hydrofluoroalkanes was ca. 58% efficiency as quantified by liquid phase19F NMR analysis. 相似文献
16.
Fatty acids,the immune response,and autoimmunity: A question of n−6 essentiality and the balance between n−6 and n−3 总被引:8,自引:0,他引:8
Harbige LS 《Lipids》2003,38(4):323-341
The essentiality of n−6 polyunsaturated fatty acids (PUFA) is described in relation to a thymus/thymocyte accretion of arachidonic
acid (20∶4n−6, AA) in early development, and the high requirement of lymphoid and other cells of the immune system for AA
and linoleic acid (18∶2n−6, LA) for membrane phospholipids. Low n−6 PUFA intakes enhance whereas high intakes decrease certain
immune functions. Evidence from in vitro and in vivo studies for a role of AA metabolites in immune cell development and functions shows that they can limit or regulate cellular
immune reactions and can induce deviation toward a T helper (Th)2-like immune response. In contrast to the effects of the
oxidative metabolites of AA, the longer-chain n−6 PUFA produced by γ-linolenic acid (18∶3n−6, GLA) feeding decreases the Th2
cytokine and immunoglobulin (Ig)G1 antibody response. The n−6 PUFA, GLA, dihomo-γ-linolenic acid (20∶3n−6, DHLA) and AA, and
certain oxidative metabolites of AA can also induce T-regulatory cell activity, e.g., transforming growth factor (IGF)-β-producing
T cells; GLA feeding studies also demonstrate reduced proinflammatory interleukin (IL)-1 and tumor necrosis factor (TNF)-α
production. Low intakes of long-chain n−3 fatty acids (fish oils) enhance certain immune functions, whereas high intakes are
inhibitory on a wide range of functions, e.g., antigen presentation, adhesion molecule expression, Th1 and th2 responses,
proinflammatory cytokine and eicosanoid production, and they induce lymphocyte apoptosis. Vitamin E has a demonstrable critical
role in long-chain n−3 PUFA interactions with immune functions, often reversing the effects of fish oil. The effect of dietary
fatty acids on animal autoimmune disease models depends on both the autoimmune model and the amount and type of fatty acids
fed. Diets low in fat, essential fatty acid deficient (EFAD), or high in long-chain n−3 PUFA from fish oils increase survival
and reduce disease severity in spontaneous autoantibody-mediated disease, whereas high-fat LA-rich diets increase disease
severity. In experimentally induced T cell-mediated autoimmune disease, EFAD diets or diets supplemented with long-chain n−3
PUFA augment disease, whereas n−6 PUFA prevent or reduce the severity. In contrast, in both T cell- and antibody-mediated
autoimmune disease, the desaturated/elongated metabolites of LA are protective. PUFA of both the n−6 and n−3 families are
clinically useful in human autoimmune-inflammatory disorders, but the precise mechanisms by which these fatty acids exert
their clinical effects are not well understood. Finally, the view that all n−6 PUFA are proinflammatory requires revision,
in part, and their essential regulatory and developmental role in the immune system warrants appreciation. 相似文献
17.
Naruo Matsumoto Kobkiet Paisancharoen Shotaro Ando 《Nutrient Cycling in Agroecosystems》2010,86(1):79-103
As the Thai economy grew rapidly after 1985, agriculture became more intensive through the increasing use of chemical fertilizer
and mechanization. This study aimed to analyze the nitrogen (N) cycle related to agricultural activities in Khon Kaen Province
in Thailand during 1990–1992 and 2000–2002, and on the changes in utilization of local organic resources and the N load to
the environment. A model of the N cycle was constructed including compartments for farmland, crop yield, crop residue, food
factory, livestock, humans, market, hydrosphere and atmosphere. N flows among the compartments in the model were estimated
from data derived from Thai agricultural statistics, related reports and journal articles, interviews with farmers and food
factory staff, field observation and information from Thai experts. N flow through livestock declined because of a decrease
in the number of buffalo raised, which reduced the production of animal manure. N returned to farmland in crop residues increased
because sugarcane cultivation, and crop residues, increased and the burning of rice straw decreased. An increase in chemical
fertilizer application increased N input to farmland for crop production. N balance in farmland changed from −27 kg ha−1 year−1 in 1990–1992 to +6 kg ha−1 year−1 in 2000–2002, which improved soil N depletion. Because N leaching and erosion from farmland were low, water pollution in
farmland is expected to be low. Human waste was not used or treated, and water pollution from human waste would be expected
in housing areas. Analysis of indices of the N cycle showed that the stock of soil N in farmland supported agricultural production
in 1990–1992, and that N inflow from outside the area (chemical fertilizer) supported agricultural production in 2000–2002.
However, efficiency of N use for agricultural production did not improve. 相似文献
18.
19.
Reihaneh Pashmineh Azar Cavus Falamaki 《Journal of Industrial and Engineering Chemistry》2012,18(2):737-743
An Iranian clinoptilolite has been modified with MnO2 for the catalytic removal of Fe2+ cations from water in a batch slurry reactor. The modified zeolite was subjected to FESEM, XRD, WDX, XRF and specific surface area analysis. A correlation for the intrinsic catalytic reaction rate incorporating both Fe2+ and dissolved oxygen concentration as a function of reaction temperature has been presented. The effect of the modified zeolite aggregate particle size on the iron removal kinetics has been investigated. It was shown that for particles larger than 150 μm, diffusion through the mesopores of the zeolite aggregate is rate controlling. The effective diffusion coefficient through the particles at RT has been calculated as 2.3 × 10?6 cm2 s?1. It is shown that liquid phase molecular diffusion within the mesopores is the dominating mass transfer mechanism. 相似文献