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1.
Two sets of indium oxide thin films (~150 nm) grown on quartz substrates using thermal evaporation technique were processed separately with 25‐keV Co? and N+ ions with several fluences ranging from 1.0 × 1015 to 1.0 × 1016 ions/cm2. The pristine and the ion implanted films were characterized by Rutherford backscattering spectroscopy (RBS), X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV–Vis spectrometry. The RBS spectra reveal signature of only cobalt and nitrogen in accordance to their fluences confirming absence of any contamination arising due to ion implantation. An increase in the average crystallite size (from 13.7 to 15.3 nm) of Co? ions implanted films was confirmed by XRD. On the other hand, the films implanted with N+ ions showed a decrease in the average crystallite size from 20.1 to 13.7 nm. The XRD results were further verified by SEM micrographs. As seen in AFM images, the RMS surface roughness of the samples processed by both ion beams was found to decrease a bit (29.4 to 22.2 nm in Co? implanted samples and 24.2 to 23.3 nm in N+ implanted samples) with increasing fluence. The Tauc's plot deduced from UV–visible spectroscopy showed that the band gap decreases from 3.54 to 3.27 eV in Co? implanted films and increases from 3.38 to 3.58 eV for films implanted with N+ ions. The experimental results suggest that the modifications in structural and optical properties of indium oxide films can be controlled by optimizing the implantation conditions. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

2.

Nano‐size calcium phosphate is prepared via solvothermal synthesis methods, using a reverse micelles solution. The influence of pH value on the crystallinity, morphology, and composition of the nanoparticles are investigated. It was found that the crystallinity increased as pH increased. However, notable changes in the morphology of the final products can be observed. At pH 6.0, long nanowires (800 nm long and 30~100 nm wide) are observed. For pH=7.5, the nanowires are straight with 60 nm diameter and a length>1500 nm. The materials prepared at pH=8.5 exhibit short‐rod morphologies with a dimension of 130~160 nm in length and 20~30 nm in width. As for those prepared at pH=9.5, short rods 80~100 nm in length and 20~50 nm in width can be observed. The influence of pH value on the interaction between surfactant molecules and reactant ions are responsible for these differences. In addition, the composition of the finial precipitation also depends on pH. Meanwhile, the ability to generate high axial ratio and well‐crystallized nanowires, by coorganization of reverse micelles solutions and hydrothermal synthesis techniques, as described in this work, could offer an approach to the fabrication of one dimension nanomaterials.  相似文献   

3.
Fe@Fe2O3 core-shell nanowires were synthesized via the reduction of Fe3+ ions by sodium borohydride in an aqueous solution with a subsequent heat treatment to form Fe2O3 shell and employed as a cathode catalyst for non aqueous Li-air batteries. The synthesized core-shell nanowires with an average diameter of 50–100 nm manifest superior catalytic activity for oxygen evolution reaction (OER) in Li-O2 batteries with the charge voltage plateau reduced to ~3.8 V. An outstanding performance of cycling stability was also achieved with a cutoff specific capacity of 1000 milliampere hour per gram over 40 cycles at a current density of 100 mA g?1. The excellent electrochemical properties of Fe@Fe2O3 as an O2 electrode are ascribed to the high surface area of the nanowires’ structure and high electron conductivity. This study indicates that the resulting iron-containing nanostructures are promising catalyst in Li-O2 batteries.  相似文献   

4.
CdS nanowires doped with different contents of Eu dopant were synthesized by solvothermal method. XRD, SEM, TEM and Raman analyses certified that the as-synthesized samples were hexagonal CdS uniform nanowires. The pure CdS nanowires were 1–3 ?μm long and 80 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 298 and 594 ?cm?1. The 3% Eu-doped CdS wires were 800 ?nm–2.5 ?μm long and 75 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 296 and 593 ?cm?1. CdS nanowires grew along the [001] direction due to the surface energy effect. The photocatalytic properties of CdS and Eu-doped CdS nanowires were investigated for the degradation of rhodamine B (RhB) illuminated by visible radiation. In this research, Eu dopant played the role in promoting the photocatalytic kinetics because Eu3+ ions act as an electron acceptor to promote charge separation and photocatalytic activity. Both OH and O2? were the main active radicals used to transform RhB molecules into CO2, H2O and other intermediates.  相似文献   

5.
《Solid State Sciences》2012,14(6):735-738
Thin films of GaN with thickness of 2 μm were synthesized on sapphire. Cr+ ions were implanted into GaN with150 keV energy at a fluence of 3 × 1015 cm−2. The annealing of the samples was carried out for a short time using rapid thermal annealing (RTA). Structural properties of the implanted samples were undertaken by XRD and Rutherford backscattering. The annealed samples demonstrated lattice recovery and damages caused by implantation. The structural properties were also studied by High-resolution X-ray Diffraction (HRXRD). Magnetic measurements of the samples were performed by Alternating Gradient Magnetometer (AGM) at room temperature and by SQUID in the range of 5–380 K. The SQUID results showed ferromagnetic behavior at T = 5 K and above 380 K for Cr+-implanted GaN.  相似文献   

6.
During this work, size fractionation technique “ultra filtration” is used in physical speciation of thorium in organic rich groundwater. Laboratory simulated experiments were carried out to study the physical speciation of thorium in aquatic environment having elevated level of dissolved humus material classified as dissolved organic carbon (DOC). Samples were collected from organic rich environment having DOC in the range of 50–60 µg mL?1. Th(IV) ions are extremely particle reactive having K d value of the order of 105–6, hence to avoid adsorption on suspended particulate matter, spiking of the solution with Th(NO3)4 was carried out in ground water samples after filtering through 450 nm pore size using suction filtration. Particles in dissolved state (colloids) ranging between <450 and >220 nm were separated using suction filtration assembly having a membrane with a pore diameter of 220 nm. Thereafter, solution was sequentially passed through the ultra-filtration membranes having pore diameters of 14 nm [300 k NMWL (nominal molecular weight limit)], 3.1 nm (50 k NMWL), 2.2 nm (30 k NMWL), 1.6 nm (10 k NMWL) and 1.1 nm (0.5 k NMWL) by using “Stirred Ultra-filtration Cells”, operating in concentration mode. Thorium has only one stable oxidation state i.e. IV, under all redox conditions in natural waters and therefore, its speciation is dominated by its interaction with various fractions of DOC. Experimental results show 50–60 % of the spiked Th is in association with fraction enriched with particles of 10 k NMWL (1.6 nm) followed by fraction enriched with particle of 0.5 k NMWL and <220 nm.  相似文献   

7.
This study aimed at optimizing the production of hyaluronic acid by Lactobacillus acidophilus FTDC 1231 using response surface methodology and evaluating the effects of divalent metal ions along the production pathway using molecular docking. Among different divalent metal ions that were screened, only iron (II) sulphate and copper (II) sulphate significantly (P?<?0.05) affected the production of hyaluronic acid. Subsequent optimization yielded hyaluronic acid at concentration of 0.6152?mg/mL in the presence of 1.24 mol L?1 iron (II) sulphate and 0.16 mol L?1 of copper (II) sulphate (103 % increase compared to absence of divalent metal ions). Data from molecular docking showed Fe2+ improved the binding affinity of UDP-pyrophophorylase towards glucose-1-phosphate, while Cu2+ contributed towards the interaction between UDP-glucose dehydrogenase and UDP-glucose. We have demonstrated that lactobacilli could produce hyaluronic acid at increased concentration upon facilitation by specific divalent metal ions, via specific targets of enzymes and substrates along pentose phosphate pathway.  相似文献   

8.
In the present study, Acacia farnesiana (Sweet acacia) seed extract is used to reduce Ag+ → Ag0 under microwave irradiation. The formation of silver nanoparticles (AgNPs) is monitored by recording the UV–Vis absorption spectra for surface plasmon resonance (SPR) peak at ~450 nm. The absorbance of SPR increases linearly with increasing temperature of the reaction mixture. Rapid reduction of silver ions occurred to form AgNPs, 80–90 % yield in about 150 s. A marginal decrease in pH and increase in solution potential (E) of the reaction mixture during the formation of AgNPs are in agreement with the proposed mechanism. XRD pattern of the AgNPs agree with the fcc structure of Ag metal, and the calculated crystallite size is ~17 nm. FT-IR and solid-state 13C NMR spectra indicate the functional groups of flavonones and terpenoids (biomolecules from plant extract) which are adsorbed on AgNPs, thereby the present method led to in situ biofunctionalization/bio-capping of AgNPs. TG analysis shows the thermal decomposition of these plant residues present on AgNPs at about 250 °C. The spherical shape of the particles with a diameter (?) in the range of ~15–20 nm is evident from FE-SEM image. Elemental analysis by EDX analysis confirms the presence of Ag as the only major element. The in vitro antibacterial screening of AgNPs shows that these bio-capped AgNPs have higher inhibitory action for E. coli and S. aureus followed by B. subtilis and P. aeruginosa. In addition, AgNPs show very good antioxidant property.  相似文献   

9.
Synthesis of copper nanoparticles was carried out with nanocrystalline cellulose (NCC) as a support by reducing CuSO4·5H2O ions using hydrazine. Ascorbic acid and aqueous NaOH were also used as an antioxidant and pH controller, respectively. The synthesized copper nanoparticles supported on NCC (CuNPs@NCC) were characterized by UV–vis, XRD, TEM, XRF, TGA, DSC, N2 adsorption-desorption method at 77 K and FTIR. The UV–vis confirmed the formation and stability of the CuNPs, which indicated that the maximum absorbance of CuNPs@NCC was at 590 nm due to the surface plasmon absorption of CuNPs. Morphological characterization clearly showed the formation of a spherical structure of the CuNPs with the mean diameter and standard deviation of 2.71 ± 1.12 nm. Similarly, XRD showed that the synthesized CuNPs@NCC was of high purity. The thermal analysis showed that the CuNPs@NCC exhibited better thermal behaviors than NCC. BET surface area revealed that the N2 adsorption–desorption isotherms of CuNPs@NCC featured a type IV isotherm with an H3 hysterisis loop. This chemical method is simple, cost effective, and environmentally friendly. Compared to NCC-supported CuNPs and unsupported CuNPs, the as-prepared CuNPs@NCC exhibit a superior catalytic activity and high sustainability for the reduction of methylene blue with NaBH4 in aqueous solution at room temperature. The CuNPs@NCC achieved complete reduction of MB with completion time, rate constant and correlation coefficient (R 2) of 12 min, 0.7421 min?1 and 0.9922, respectively.  相似文献   

10.
Ovalbumin-stabilized gold nanoclusters(OVA@AuNCs) were prepared with ascorbic acid as a reducing agent. This strategy could realize the synthesis of water-soluble OVA@AuNCs within 20 min. The asprepared fluorescent probe showed a red fluorescence emission at 630 nm. Moreover, the properties of the OVA@AuNCs were characterized by transmission electron microscope, dynamic light scattering,ultraviolet-visible spectroscopy, fluorescent spectroscopy. Based on the surface electron density decrease-induced fluorescence quenching mechanism, the OVA@AuNCs provided high sensitivity and selectivity for sensing copper ions. A good linear relationship was obtained between the fluorescence intensity of OVA@AuNCs and the concentration of copper ions in the range of 5.0-100.0 μmol/L(R~2=0.999) with a detection limit of 640 nmol/L Furthermore, the rat serum copper contents were determined by using the OVA@AuNCs based assay, indicating great potential of fluorescent probes for application in biological and clinical analysis.  相似文献   

11.
Ion implantation techniques were used to study the effect of an MgO additive on the luminescence properties induced by Cu in ZnO thin films. Cu ions (accelerating voltage of 75 keV, dose of 4.5 × 1014 ions/cm2) were implanted at room temperature in nondoped and Mg‐doped ZnO thin films. After annealing, emissions in the visible region originating from Cu phosphor were observed at 510 nm in CVD‐ZnO and at 450 nm in Mg‐doped ZnO (MZO) thin films. The Cu depth profile shows distortion in the low‐concentration region of CVD‐ZnO. After the annealing, the Cu implant was homogenized in thin films, and then the Cu concentration was determined to be 1.5 × 1019 ions/cm3 in CVD‐ZnO and 5.6 × 1018 ions/cm3 in MZO thin films. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

12.
A simple and efficient liquid-phase microextraction technique was developed using ultrasound-assisted emulsification solidified floating organic drop microextraction combined with flame atomic absorption spectrometry, for the extraction and determination of trace amounts of iron and copper in real samples. 2-Mercaptopyridine n-oxide was used as chelating agent and 1-dodecanol was selected as extraction solvent. The factors influencing the complex formation and extraction were optimized. Under optimum conditions, an enrichment factor of ~13 was obtained for both iron and copper from only 6.7 mL of aqueous phase. The analytical curves were linear between 40–800 and 20–1,200 μg L?1 for iron and copper respectively. Based on three SD of the blank, the detection limits were 8.6 and 4.1 μg L?1 for iron and copper respectively. The relative SDs for ten replicate measurements of 500 μg L?1 of metal ions were 2.9 and 1.2 for iron and copper respectively. The proposed method was successfully applied for determination of iron and copper in environmental waters and some food samples including chess, rice, honey and powdered milk. Finally, method validation was made using rock certified reference material. A student’s t test indicated that there was no significant difference between experimental results and certified values.  相似文献   

13.
采用高分子自组装ZnO纳米线及其形成机理   总被引:8,自引:3,他引:8  
介绍了一种能在各种晶面的硅衬底上制备垂直于衬底取向生长的ZnO纳米线阵列的新方法. 该法采用高分子络合和低温氧化烧结反应, 以聚乙烯醇(PVA)高分子材料作为自组装络合载体来控制晶体成核和生长. 首先通过PVA侧链上均匀分布的极性基团羟基(—OH)与锌盐溶液中的Zn2+离子发生络合作用, 然后滴加氨水调节络合溶液pH值为8.5±0.1, 使络离子Zn2+转变为Zn(OH)2, 再将硅片浸入此溶液中, 从而在硅衬底表面得到较均匀的Zn(OH)2纳米点, 随后在125 ℃左右Zn(OH)2纳米点通过热分解转化为ZnO纳米点, 其后在420 ℃烧结过程中衬底上的ZnO纳米点在PVA高分子网络骨架对其直径的限域下逐渐取向生长成ZnO纳米线, 并且烧结初期PVA碳化形成的碳通过碳热还原ZnO为Zn, 再在氧气氛中氧化为ZnO的方式在纳米线顶端形成了催化活性点, 促进了纳米线顶端ZnO的吸收. 烧结后碳逐渐氧化被完全去除. 采用场发射扫描电镜(FE-SEM)、透射电镜(TEM, HR-TEM)和X射线衍射(XRD)对纳米线的分析结果表明, ZnO纳米线在硅衬底上分布均匀, 具有六方纤锌矿结构, 并且大多沿[0001]方向择优取向生长, 直径为20~80 nm, 长度可从0.5至几微米. 提出了聚合物控制ZnO结晶和形貌的网络骨架限域模型以解释纳米线的生长行为.  相似文献   

14.
Direct comparison of key physical and chemical-engineering properties of two representative matrices for multipurpose immobilisations was performed for the first time. Polyvinyl alcohol lens-shaped particles LentiKats® and polyelectrolyte complex microcapsules were characterised by advanced techniques with respect to the size distribution of the particles, their inner morphology as revealed by fluorescent probe staining, mechanical resistance, size-exclusion properties, determination of effective diffusion coefficient and environmental scanning electron microscope imaging. While spherical polyelectrolyte complex microcapsules composed of a rigid semipermeable membrane and a liquid core are almost uniform in shape and size (diameter of 0.82 mm; RSD?=?5.6 %), lens-shaped LentiKats® are characterised by wider size distribution (diameter of 3.65 mm; RSD?=?10.3 % and height of 0.341 mm; RSD?=?32.3 %) and showed the same porous structure throughout their whole volume at the mesoscopic (micrometre) level. Despite differences in their inner structure and surface properties, the pore diameter of?~?2.75 nm for regular polyelectrolyte complex microcapsules and?~?1.89 nm for LentiKats® were similar. These results were used for mathematical modelling, which provided the estimates of the effective diffusion coefficient of sucrose. This value was 1.67?×?10?10 m2 s?1 for polyelectrolyte complex microcapsules and 0.36?×?10?10 m2 s?1 for LentiKats®. Recombinant cells Escherichia coli-overexpressing enzyme cyclopentanone monooxygenase were immobilised in polyelectrolyte complex microcapsules and LentiKats® for comparison of their operational stability using model Baeyer–Villiger oxidation of (±)-cis-bicyclo [3.2.0] hept-2-en-6-one to regioisomeric lactones as important chiral synthons for potential pharmaceuticals. Both immobilisation matrices rendered high operational stability for whole-cell biocatalyst with no reduction in the biooxidation rate over 18 repeated reaction cycles.  相似文献   

15.
Effects of Tb and transition metal (TM = Ni, Mn and Ti) ions co-doping on the structural, electrical and ferroelectric properties of the BiFeO3 thin films prepared by using a chemical solution deposition method were reported. From X-ray diffraction and Raman scattering analyses, distorted rhombohedral perovskite structures were observed for all thin films. Improved electrical and ferroelectric properties were observed for the co-doped thin films. Among the thin films, the lowest leakage current density of 2.67 × 10?6 A/cm2 (at 100 kV/cm), large remnant polarization (2P r ) of 82.2 μC/cm2 and low coercive field (2Ec) of 680 kV/cm (at 1,036 kV/cm) were measured for the (Tb, Mn) co-doped thin film.  相似文献   

16.
A controlled synthesis method for preparing narrow-dispersed copper nanoparticles, using water and ethylene glycol as the reaction media respectively, has been reported. In order to obtain pure-phase copper nanoparticles using water, the reaction time of 8 h is essential. Owing to the reduction property of ethylene glycol, the reaction rate using ethylene glycol is higher. In addition, the amount of reduction agent can reduce largely. Polyvinyl pyrrolidone plays great role on the size of copper particles, and the increasing of polyvinyl pyrrolidone concentration attributes to the smaller dimension particles. The mean diameter is about 4 nm when the concentration of polyvinyl pyrrolidone is 0.5 mmol/L. Polyvinyl pyrrolidone acts as the polymeric capping agents in the reaction, preventing the agglomeration of the copper nanoparticles. When water is the reaction medium, Cu2+ complex is reduced to Cu+ complex firstly, and the further reduction of Cu+ forms the pure copper nanoparticle.  相似文献   

17.
Isothermal titration calorimetry, potentiometric titration and circular dichroism spectroscopy were used to study the interaction of copper(II) ions with Argireline (Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2) and three of its point mutation derivatives: Glu-Ala-Met-Gln-Arg-Arg-NH2 (AN1), Glu-Ala-His-Gln-Arg-Arg-NH2 (AN2) and Glu-Ala-Met-Gln-Ala-Arg-NH2 (AN3). Under the experimental conditions (20 mmol·L?1 Caco solution, pH 6, 298.15 K), copper(II) ions form 1:1 complexes with the peptides Argireline, AN1, and AN2. The complexation reactions are entropy-driven processes. The stability of the resulting complexes increases in the order log10KCu(AN1) < log10KCu(Argireline) < log10KCu(AN2). The relationship between the point mutations of Argireline and the binding properties of these peptides towards copper(II) ions is discussed.  相似文献   

18.
Low‐energy lead ion implantation and high‐temperature electron beam annealing were used to study the potential of producing Pb nanostructures on Si. Pb+ ions were implanted at high dose into p‐type (100) Si to the depth of 8.0 nm. The implanted samples were annealed under high vacuum conditions with an electron beam at 200–700 °C for 15 s. Rutherford Backscattering Spectrometry (RBS) shows rapid out‐diffusion of Pb atoms above 400 °C. However, some Pb atoms are still present in the near‐surface region after annealing the implanted samples at 700 °C. Lead nanostructures were found on samples annealed above 300 °C. Annealing the samples at 450 °C causes the formation of nanostructures as tall as 4.1 ± 0.1 nm. Many of these are arranged in ‘web‐like’ strings that extend over micrometer distances. Occasionally, much larger nano‐features (as wide as 500 nm in diameter, average height of 1.5 nm) appear in the centre of the strings. Annealing samples well above the melting point of lead results in randomly distributed small nanometer‐sized Si nano‐dots. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

19.
Chitosan is well known for its binding properties toward transition metal ions. We prepared a chemical hydrogel based on chitosan using as cross-linking agent a polyfunctionalized β-cyclodextrin and studied the structural and catalytic features of this hydrogel loaded with copper(II) ions in aqueous medium. Stability of the complex and its structural characteristics were determined by isothermal microcalorimetry and EPR spectroscopy, respectively. Kinetics of the oxidation of (d, l)-adrenaline and of l-adrenaline catalyzed by copper (II) bound to the matrix was monitored with a Clark-type O-2 sensitive electrode. The advantages of working with a heterogeneous system are coupled with the preservation of both structural and catalytic features of copper(II) site in the matrix with respect to copper(II) ions bound to chitosan derivatives in solution.  相似文献   

20.
A high-performance ionic polymer–metal composite (IPMC) actuator based on a polyelectrolyte membrane has been constructed from a poly((t-butyl-styrene)-b-(ethylene-r-propylene)-b-(styrene-r-styrene sulfonate)-b-(ethylene-r-propylene)-b-(t-butyl-styrene)) (tBS-EP-SS-EP-tBS; SSPB) pentablock copolymer ionomer and the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMImTFSI). The SSPB copolymer ionomer had microphase-separated morphology comprising alternating styrene-rich ionic channel regions and aliphatic EP-rich non-ionic regions, on the several tens of nanometers scale (average diameter of ionic channel regions ca. 20 nm), whereas the most commonly used Nafion contained narrow ion clusters of less than 4 nm. The large ionic channels of SSPB enabled better transport of such bulky ions as IL ions, and endowed the SSPB–BMImTFSI membrane with ionic conductivity superior to that of the Nafion–BMImTFSI membrane (SSPB–BMImTFSI: 1.01 × 10?4 S/cm, Nafion–BMImTFSI: 0.49 × 10?4 S/cm). The SSPB–BMImTFSI membrane-based IPMC actuator generated a larger and faster electromechanical response than the Nafion-based IPMC.  相似文献   

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