Solvother mal synthesis of Co1-xNixFe2O4 nanoparticles and its application in ammonia vapors detection

Magnetic Co1-xNixFe2O4 nanoparticles (NPs) were successfully synthesized via a solvothermal method using ethylene glycol as solvent.The samples were characterized by X-ray diffraction (XRD),field emiss...     

稀土元素Gd、Ho和Dy在磁共振成像应用的研究进展

Gd、Ho和Dy因其独特的光学和磁学性质而在生物成像等方面有着广泛的应用.在镧系元素中,Gd~(3+)具有7个不成对的电子,可以提供高的弛豫度,已被广泛地用于磁共振成像(MRI)造影剂,而Ho~(3+)和Dy~(3+)具有最短的电子弛豫时间和最高的有效磁矩,因此有良好的高场T_2弛豫效果.介绍了基于这3种稀土元素的纳米材料在MRI方面的应用.     

Subsolidus phase relations in the system MgO-ZnO-SiO2 at high pressure

The subsolidus phase relations were determined experimentally in the system MgO-ZnO-SiO2 at 1.0 GPa and 1 200℃, by use of the high-pressure apparatus "piston-cylinder". The results showed characteristics of the phases assemblage different from that in similar ternary systems. It is impossible to form complete Mg2SiO4-Zn2SiO4 olivine and Mg2Si2O6-Zn2Si2O6 pyroxene solid solution. This is controlled by the properties of Zn2+ with an outer layer of electron (Ar)3d10, different from others transition metal ions, like Fe2+ , Ni2+ , Co2+ .     

Preparation of monodisperse,superparamagnetic, luminescent,and multifunctional PGMA microspheres with amino-groups

Micron-sized, monodisperse, superparamagnetic, luminescent composite poly（glycidyl methacrylate） （PGMA） microspheres with functional amino-groups were successfully synthesized in this study. The process of preparation was as follows： preparation of monodisperse poly（glycidyl methacrylate） microspheres by dispersion polymerization method; modification of poly（glycidyl methacrylate） microspheres with ethylene diamine to form amino-groups; impregnation of iron ions （Fe^2＋ and Fe^3＋） inside the microspheres and subsequently precipitating them with ammonium hydroxide to form magnetite （Fe3O4） nanoparticles within the polymer microspheres; infusion of CdSe/CdS core-shell quantum dots （QDs） into magnetic polymer microspheres. Scanning electron microscopy （SEM） was used to characterize surface morphology and size distribution of composite microspheres. The average size of microspheres was 1.42 μm with a size variation of 3.8%. The composite microspheres were bright enough and easily observed using a conventional fluorescence microscope. The composite microspheres were easily separated from solution by magnetic decantation using a permanent magnet. The new multifunctional composite microspheres are promising to be used in a variety of bioanalyUcal assays involving luminescence detection and magnetic separation.     

Multi-color long-lasting phosphorescence of rare earth ions in CdSiO<Subscript>3</Subscript> matrix

A series of rare earth ions doped CdSiO3:RE^3 (RE=Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho,Er, Tin, Yb, Lu) multi-color long-lasting phosphorescence phosphors are prepared by the conventional hightemperature solid-state method. The results of XRD measurement indicate that the products fired under 1050~C for 3h have a good crystallization without any detectable amount of impurity phase. Rare earth ions doped CdSiO3 phosphors possess excellent Inmiuescence properties. When rare earth ions such as Y^3 , La^3 , Gd^3 , Lu^3 , Ce^3 , Nd^3 , Ho^3 , Er^3 ,Tm^3 and Yb^3 are introduced into the CdSiO3 host, one broadband centered at about 420 nm resulting from traps can be observed. In the case of other earth ions such as Pr^3 ,Sm^3 , Eu^3 , Tb^3 and Dy^3 , their characteristic line emitting as well as the -420 nm broadband luminescence can be obtained. The mixture of their characteristic line emitting with the -420 nm broadband Inminescence results in various afterglow color.     

Analysis of the factors affecting the magnetic characteristics of nano-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> particles

We prepared Fe3O4 nanoparticles using chemical coprecipitation and studied the factors affecting the magnetic characteristics of nano-Fe3O4 particles.We identified four factors and three levels of an orthogonal experiment and investigated these four factors that affect the magnetic characteristics of the Fe3O4 particles.We obtained important information from this investigation.The Fe3+ to Fe2+ molar ratio,the iron precursor salt,the amount of surfactant and the amount of alkali were found to be important.We also studied the influence of the order of alkali and surfactant addition,the aging time and the stirring speed on the magnetic characteristics of the nano-Fe3O4 particles.The Fe3O4 preparation process was also analyzed.     

Competing crystallite size and zinc concentration in silica coated cobalt ferrite nanoparticles

Silica coated(30 wt%) cobalt zinc ferrite(Co1 xZnxFe2O4, x?0, 0.2, 0.3, 0.4, 0.5 and 1) nanoparticles were synthesized by using sol–gel method. Silica acts as a spacer among the nanoparticles to avoid the agglomeration. X-ray diffraction(XRD) reveals the cubic spinel ferrite structure of nanoparticles with crystallite size in the range 37–45 nm. Fourier transform infrared(FTIR) spectroscopy confirmed the formation of spinel ferrite and SiO2. Scanning electron microscopy(SEM) images show that the nanoparticles are nearly spherical and non-agglomerated due to presence of non-magnetic SiO2 surface coating. All these measurements signify that the structural and magnetic properties of Co1 xZnxFe2O4 ferrite nanoparticles strongly depend on Zn concentration and nanoparticle average crystallite size in different Zn concentration regimes.& 2014 Chinese Materials Research Society. Production and hosting by Elsevier B.V. All rights reserved.     

Single-negative properties of Ba2Co1.8Cu0.2Fe12O22 and Ba3Co2Fe23.4Zn0.6O41 hexagonal ferrites

The electromagnetic properties of Ba₂Co_1.8Cu_0.2Fe₁₂O₂₂ (Co₂Y) and Ba₃Co₂Fe_23.4Zn_0.6O₄₁ (Co₂Z) were studied by measuring microwave scattering parameters. In the transmission spectra of Ba₂Co_1.8Cu_0.2Fe₁₂O₂₂, a forbidden band emerges due to ferromagnetic resonance, and the permeability will turn to negative in the vicinity of the ferromagnetic resonance frequency. In the complex permittivity spectra of Ba₃Co₂Fe_23.4Zn_0.6O₄₁, the negative permittivity can be obtained due to dielectric resonance. Therefore, Co₂Y and Co₂Z can be used to construct left-handed materials possessing negative permeability and negative permittivity simultaneously.     

水溶性磁性Fe_3O_4纳米粒子对小麦生长影响的研究

水溶性磁性Fe_3O_4纳米颗粒由于其良好的生物相容性、超顺磁性等特征,在生物领域常被用来作为磁性载体材料,其广泛的生产和应用增加了它们在环境中释放的可能性,需对其环境生物安全性进行评价.首先合成了水溶性磁性Fe_3O_4纳米纳米粒子,并用透射电子显微镜和马尔文粒度分析仪对其进行形貌分析和表征.然后在不同的浓度下(0、0.72、1.44、3.6 mg/mL)研究了水溶性磁性Fe_3O_4纳米粒子对小麦生长的影响,结果显示随着浓度的增加,磁性Fe_3O_4纳米纳米粒子对小麦生长的抑制越明显,造成生长抑制和根结构损伤.结果证明了水溶性磁性Fe_3O_4纳米颗粒对小麦植物存在一定的生物毒性,其环境排放应该严格限制.     

NO adsorption study on the distribution of Ni2 + ions on the various micro-environments of carriers

The decrease of the electron density in the d orbits of Ni2+ ions, resulting from the disturbance of micro-environments in which Ni2+ ions are located, makes the frequency of adsorbed NO shift higher. The shift degree is determined mainly by the property of the microenvi-ronments. When Ni2+ ions are located on SII , SII · (SI ·) sites of Y zeolite or on the surface of γ-alumina, their NO adsorption gives rise to IR bands at 1 905, 1 900 and 1 855-1 875 cm-1, respectively. The distribution of Ni2 + ions on the various micro-environments of USY zeolite, AI2O3 and MS mixed carrier has also been discussed according to the different frequencies of adsorbed NO, as well as the influence of NiO loading.     

Spectroscopic properties of Er3+/Ho3+/Tm3+ doped α-SiAlON ceramics under 793 ​nm excitation

This paper reports the first demonstration of super broadband infrared downshifting emission extending from 1640 ​nm to 2200 ​nm with the full width at half maximum of ∼ 417 ​nm in lanthanides (Er³⁺, Ho³⁺, and Tm³⁺)-doped α-SiAlON ceramics upon 793 ​nm excitation. Using α-Si₃N₄ ceramic as a precursor the lanthanides-doped α-SiAlON ceramics were synthesized by the hot-press method. The lanthanides induced no significant secondary phases in the sintered α-SiAlON ceramics. Strong two-photon upconversion emission bands centered at 547, 671 and 694 ​nm have also been observed upon 793 ​nm excitation. The time-resolved measurements of the upconversion emissions confirm that the efficient energy transfer among the Er³⁺, Ho³⁺ and Tm³⁺ ions as well as the ground state absorption in Er³⁺ and Tm³⁺ are responsible for the observed spectroscopic properties.     

Enhanced thermoelectric properties of Co1-x-yNix+ySb3-xSnx materials

Co_1−x−y Ni_x+y Sb_3−x Sn _x polycrystals were fabricated by vacuum melting combined with hot-press sintering. The effect of alloying on the thermoelectric properties of unfilled skutterudite Co_1−x Ni _x Sb_3−x Sn _x was investigated. A leap of electrical conductivity from the Co_0.93Ni_0.07Sb_2.93Sn_0.07 sample to the Co_0.88Ni_0.12Sb_2.88Sn_0.12 sample occurs during the measurement of electrical conductivity, indicating the adjustment of band structure by proper alloying. The results show that alloying enhances the power factor of the materials. On the basis of alloying, the thermoelectric properties of Co_0.88Ni_0.12Sb_2.88Sn_0.12 are improved by Ni-doping. The thermal conductivities of Ni-doping samples have no reduction, but their power factors have obvious enhancement. The power factor of Co_0.81Ni_0.19Sb_2.88Sn_0.12 reaches 3.0 mW·m⁻¹·K⁻² by Ni doping. The dimensionless thermoelectric figure of merit reaches 0.55 at 773 K for the unfilled Co_0.81Ni_0.19 Sb_2.88Sn_0.12.     

UV/visible spectroscopic analysis of CO<Superscript>3+</Superscript> and CO<Superscript>2+</Superscript> during the dissolution of cobalt from mixed Co-Cu oxidized ores

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H₂SO₄ and SO₂ as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solutions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO₂. Furthermore, UV/visible spectroscopy confirmed that as SO₂ was flushed into the acidified leaching solution, Co³⁺ bearing minerals were reduced to the readily soluble Co²⁺ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co³⁺ to Co²⁺ bearing minerals when SO₂ is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co³⁺, Co²⁺, and Cu²⁺ complexes, as shown by their UV/visible spectra, are also discussed.     

Photoluminescence and cathodoluminescence properties of a novel CaLaGa307：Dy3＋ phosphor

A single host white emitting phosphor, CaLaGa3O7:Dy3+, was synthesized by chemical co-precipitation. Field emission scanning electron microscopy, X-ray diffraction, laser particle size analysis, and photoluminescence and cathodoluminescence spectra were used to investigate the structural and optical properties of the phosphor. The phosphor particles were composed of microspheres with a slight tendency to agglomerate, and an average diameter was of about 1.0 μm. The Dy3+ ions acted as luminescent centers, and substituted La3+ ions in the single crystal lattice of CaLaGa3O7 where they were located in Cs sites. Under excitation with ultraviolet light and a low voltage electron beam, the CaLaGa3O7:Dy3+ phosphor exhibited the characteristic emission of Dy3+ (4F9/2-6H15/2 and 4F9/2-6H13/2 transitions) with intense yellow emission at about 573 nm. The chromaticity coordinates for the phosphor were in the white region. The relevant luminescence mechanisms of the phosphor are investigated. This phosphor may be applied in both field emission displays and white light-emitting diodes.     

分子印迹磁性荧光复合微球的制备及其性能研究

复杂生物体系中蛋白质的高效分离分析在生物分离、蛋白质纯化与检测等生命科学研究领域中具有重要的意义.本文以磁性荧光复合微球（Fe₃O₄MNP-ZnSQDs）为载体,利用表面印迹技术在Fe₃O₄MNP-ZnSQDs表面构建"核-壳"结构的磁性荧光蛋白印迹微球（Fe₃O₄MNP-ZnSQD@MIPs）,并用于溶菌酶蛋白的快速分离.结果表明,制备的Fe₃O₄MNP-ZnSQD@MIPs具有分散性好、粒径均一、荧光发射强、磁响应明显等特点.在最优条件下,该印迹微球在15 min达到吸附平衡,最大吸附容量可达645.76 m g· g-1,饱和磁强度为40 em u· g-1,且具有良好的选择性,印迹因子为2.15.该磁性荧光分子印迹微球成本低、耗时短、使用简单、吸附量高且选择性好,可用于大批量样品检测中溶菌酶的快速分离与纯化.      

Magnetic properties and thermal stability of sintered Nd-Fe-B magnet with Dy-Ni additive

A sintered(Nd_(0.8)Pr_(0.2))_(30.7)FebalB_(0.98)Cu_(0.2) magnet with 3% intergranular Dy_(85)Ni_(15) additive is prepared to study the magnetic properties and thermal stability of the Nd-Fe-B magnet. The results show that the magnet with or without additive obtains its optimum comprehensive magnetic properties at the sintering temperature of 1 030 ℃ and 1 040 ℃, respectively. The maximum coercivity of the magnet with additive reaches 15.16 k Oe, while that of the magnet without additive is just 11.88 k Oe. Further investigation on microstructure indicates that the grains of the magnet with additive form a modified "core shell" structure. Adding Dy_(85)Ni_(15) can significantly enhance the coercivity of Nd-Fe-B magnet and thus decrease its coercivity temperature coefficient.     

Effects of the rare earth ions on bone resorbing function of rabbit mature osteoclasts<Emphasis Type="Italic">in vitro</Emphasis>

The osteoclast plays initiating and vanguard roles in the course of bone remodeling. The resorption and formation of bone is the basic clues of bone remodeling, which results from the mutual dependent functions of osteoclasts and osteoblasts. When the osteoclasts are activated, the bone resorption function is increased. The excess bone resorption leads to osteoporosis, characterized by formation of many hollows, lacunae and tunnels on the bone surface or in depth[1,2]. The differentiation, pro…     

Bimetallic-organic coordination polymers to prepare N-doped hierarchical porous carbon for high performance supercapacitors

Single metal-organic coordination polymers have limited functions as precursors for porous carbon electrode materials.The construction of bimetallic organic coordination polymers can effectively utilize the advantages of each single metal-organic coordination polymer to improve the performance of the derived carbon materials.Herein,High performance nitrogen-doped porous carbon(BC_(Fe–Ni))have been produced by directly carbonizing bimetallic organic coordination polymers formed by 4,4'-bipyridine(BPD)reaction with Fe Cl_3and NiCl_2.The BC_(Fe–Ni) exhibits high nitrogen content(12.66 at%),large specific surface area(1049.51 m~2g~(-1))and hierarchical porous structure,which contributes to an excellent gravimetric specific gravity of 320.5 Fg~(-1)and 108%of specific capacitance retention after 10000 cycles.The BC_(Fe–Ni)assembled symmetrical supercapacitor shows an energy density of 18.3 Wh kg~(-1)at a power density of 350 W kg~(-1).It is expected that the as-prepared N-doped porous carbon derived from bimetallic-organic coordination polymer is a promising electrode material for high performance energy storage devices.     

Synthesis, conductivity and photosensitivity of 2-D conjugated polymers of metalporphyrazine with sulfur bridges

The title polymers PMS₈Pz, M=Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II, were synthesized by reaction of 2, 3, 5, 6-tetracyano-1, 4-dithiin with corresponding metal salts, respectively. The structure and properties of these polymers were characterized by elemental analysis, transmission electron microscope, DTA, IR, UV-Vis, fluorescence and EPR spectra. It has been found that these conjugated polymers have the property of intrinsic semiconductor. The conductivity σ_298K of these polymers is in the range of 10⁻⁹≈10⁻³ S·cm⁻¹ under pressure 10.63 MPa and incrementals in the metal order Mn<Co<Fe<Zn<Cu<Ni. The photosensitivity of the MS₈Pz to the CdS-PVA films is incrementals in the metal order Zn<Mn<Co<Fe<Cu<Ni. Supported by the National Natural Science Foundation of China and by the Approach Fund of State Key Laboratory of Coordination Chemistry in Nanjing University Peng Zhenghe: born in Apr. 22, 1945, Professor     

腐殖酸包覆Fe_3O_4纳米粒子类Fenton催化降解亚甲基蓝

采用共沉淀法制备腐殖酸包覆的磁性四氧化三铁纳米粒子(HA@Fe_3O_4)并将其用于类Fenton体系催化降解亚甲基蓝(MB).通过透射电子显微镜(TEM)、动态光散射(DLS)、X射线衍射仪(XRD)、傅里叶变换红外光谱(FT-IR)对样品的形貌、结构及成分进行表征.比较HA包覆前后Fe_3O_4纳米粒子的催化效果,考察HA@Fe_3O_4催化剂用量、H_2O_2浓度等因素对降解效率的影响.结果表明HA的包覆可以显著提高MB的降解效率.