A Facile Solvothermal Method for Synthesis of CuInS2 Nanostructures

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M. Mousavi-Kamazani

2012-09-01

Full Text Available CuInS2 nanostructures were  synthesized  via  a  simple  surfactant-free solvothermal  route.  In  this  synthesis,  thiosemicarbazide  and thioglycolic acid were used as sulfur sources. The effects of different parameters such as type of precursor and time on the morphology and particle  size  of  the  samples  have  been  investigated.  The nanostructures  were  characterized  by  means  of  X-ray  diffraction (XRD,  scanning  electron microscopy  (SEM,  energy-dispersive X- ray  analysis  (EDX,  Fourier  transform  infrared  (FT-IR  and photoluminescence  (PL  spectroscopy.  The  fill  factor  (FF,  open circuit voltage  (Voc, and  short circuit current  (Isc were obtained by I–V characterization.

Modified solvothermal synthesis and characterization of CdS/ZnS core/shell nanorods

International Nuclear Information System (INIS)

Baby Suganthi, A.R.; Sagayaraj, P.

2013-01-01

Core/shell CdS/ZnS nanorods were synthesized using a two-step solvothermal approach. The first step is the formation of CdS nanoparticles initiated using nucleation followed by growth through coalescence-exchange and particle coagulation. The second step leads to the formation of ZnS and further coalescence-exchange leading to deposition and growth of a ZnS shell around CdS nanoparticles. The structural, morphological and chemical studies were performed using X-ray diffraction, Energy Dispersive X-ray spectroscopy (EDX) Scanning electron Microscopy (SEM), UV–vis absorption spectra and Transmission Electron Microscopy (TEM), provide direct evidence for shell growth. The present synthesis provides a rational approach to the design of novel core/shell nanomaterials with appealing applications in optoelectronic devices. - Graphical abstract: From the resulting TEM images, the formation of core/shell could be observed. The apparent microscopy contrast between the CdS core and the ZnS shell offers evidence for the formation of CdS/ZnS core/shell nanostructures. It is clearly evident that the surfaces of the nanorods became rough after coating and also the diameter of the nanorod is seen increased up to 40–50 nm. Highlights: ► CdS/ZnS core/shell nanorods were synthesized using two-step solvothermal approach. ► The nanoparticles were characterized by XRD, EDX, SEM, UV–vis and TEM. ► SEM images revealed the surface roughness after ZnS shell growth. ► TEM microscopy offers evidence for the formation of core/shell nanostructures

Microwave solvothermal synthesis and characterization of manganese-doped ZnO nanoparticles

Directory of Open Access Journals (Sweden)

Jacek Wojnarowicz

2016-05-01

Full Text Available Mn-doped zinc oxide nanoparticles were prepared by using the microwave solvothermal synthesis (MSS technique. The nanoparticles were produced from a solution of zinc acetate dihydrate and manganese(II acetate tetrahydrate using ethylene glycol as solvent. The content of Mn2+ in Zn1−xMnxO ranged from 1 to 25 mol %. The following properties of the nanostructures were investigated: skeleton density, specific surface area (SSA, phase purity (XRD, lattice parameters, dopant content, average particle size, crystallite size distribution, morphology. The average particle size of Zn1−xMnxO was determined using Scherrer’s formula, the Nanopowder XRD Processor Demo web application and by converting the specific surface area results. X-ray diffraction of synthesized samples shows a single-phase wurtzite crystal structure of ZnO without any indication of additional phases. Spherical Zn1−xMnxO particles were obtained with monocrystalline structure and average particle sizes from 17 to 30 nm depending on the content of dopant. SEM images showed an impact of the dopant concentration on the morphology of the nanoparticles.

Solvothermal preparation of micro/nanostructured TiO_2 with enhanced lithium storage capability

International Nuclear Information System (INIS)

Li, Jie; Wang, Chao; Zheng, Ping; Zhang, Lei; Chen, Gongxuan; Tang, Chengchun; Wu, Tian

2017-01-01

Facile and controllable preparation of TiO_2 is of prime importance to elaborately tailor and then fully exploit its intriguing functionalities in energy storage, catalysis and environmental remediation. Herein, a solvothermal method combined with post annealing is conducted, in which the hydrolysis of tetrabutyl titanate is controlled by the in-situ generated water during solvothermal treatment. By controlling synthetic conditions (i.e. reactant ratio, solvothermal temperature and reaction time), we manage to tailor the morphologies of TiO_2. Specially, three typical structures (nanoparticle, nanoneedle and nanorod) are studied to reveal the growth mechanism and the effects of the synthesis conditions. Nanoneedle-structured TiO_2 shows higher specific capacity and enhanced cycle stability as anode material for lithium ion batteries. - Highlights: • Controllable preparation of nano-TiO_2 is achieved by a solvothermal method. • TiO_2 morphology is tailored by tuning reactant ratio, temperature and duration. • Needle structured TiO_2 shows enhanced lithium storage capability.

Surfactant-ligand co-assisted solvothermal technique for the synthesis of different-shaped CdS nanorod-based materials

International Nuclear Information System (INIS)

Bao Chunyan; Jin Ming; Lu Ran; Xue Pengchong; Zhang Qinglin; Wang Dejun; Zhao Yingying

2003-01-01

1-D nanorods, twinrods, golfclubs, and tripods of CdS were prepared via a surfactant-ligand co-assisted solvothermal method at 160 deg. C. The surfactant of S-dodecylisothiounium bromide (C 12 ) used in the process was favorable for synthesis of different-shaped CdS nanorod with high aspect ratio. X-ray diffraction (XRD) and TEM images showed that the 1-D nanorods had wurtzite phase and others had a zinc blende core and wurtzite arms. The morphologies of CdS prepared under different conditions suggested the 'template-assistance' of the surfactant and that the nonaqueous organic media are important for the self-assembling of inorganic components at atomic level

Solvothermal synthesis of nanorods of ZnO, N-doped ZnO and CdO

International Nuclear Information System (INIS)

Varghese, Neenu; Panchakarla, L.S.; Hanapi, M.; Govindaraj, A.; Rao, C.N.R.

2007-01-01

ZnO nanorods with diameters in the 80-800 nm range are readily synthesized by the reaction of zinc acetate, ethanol and ethylenediamine under solvothermal conditions. The best products are obtained at 330 deg. C with a slow heating rate. Addition of the surfactant Triton -X 100 gave nanorods of uniform (300 nm) diameter. By adding a small amount of liquid NH 3 to the reaction mixture, N-doped ZnO nanorods, with distinct spectroscopic features are obtained. CdO nanorods of 80 nm diameter have been prepared under solvothermal conditions using a mixture of cadmium cupferronate, ethylenediamine and ethanol at 330 deg. C. Similarly, Zn 1-x Cd x O nanorods of a 70 nm diameter are obtained under solvothermal conditions starting with a mixture of zinc acetate, cadmium cupferronate, ethanol and ethylenediamine

Controllable 5-sulfosalicylic acid assisted solvothermal synthesis of monodispersed superparamagnetic Fe{sub 3}O{sub 4} nanoclusters with tunable size

Energy Technology Data Exchange (ETDEWEB)

Wang, Wentao [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Tang, Bingtao, E-mail: tangbt@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Wu, Suli; Gao, Zhanming; Ju, Benzhi [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Teng, Xiaoxu [School of Chemistry and Chemical Engineering, Yangtze Normal University, Chongqing 408100 (China); Zhang, Shufen [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)

2017-02-01

Monodispersed Fe{sub 3}O{sub 4} nanoclusters were synthesized in a one-pot solvothermal route with 5-sulfosalicylic acid (SSA) as the functional ligand in a mixed-solvent system of diethylene glycol/ethylene glycol (DEG/EG). Nucleation and aggregation growth model was responsible for the formation of secondary structure of the clusters. In the process, the size of the clusters can be effectively controlled by varying the amounts of SSA and the volume ratio of DEG/EG. The nanoclusters exhibited superparamagnetic properties with high saturation magnetization value of about 68.7 emu g{sup −1} at room temperature. The water-soluble small-molecule SSA grafted on the surface of Fe{sub 3}O{sub 4} nanocrystals rendered the superparamagnetic clusters dispersible in water, which is crucial for potential applications in biomedical fields. - Graphical abstract: 5-sulfosalicylic acid assisted solvothermal synthesis of monodispersed superparamagnetic Fe{sub 3}O{sub 4} nanoclusters with tunable size by a mixed-solvent system of DEG/EG. - Highlights: • Monodispersed Fe{sub 3}O{sub 4} nanoclusters were synthesized in a one-pot 5-sulfosalicylic acid assisted solvothermal route. • The size of the clusters are tunable by varying the amounts of 5-sulfosalicylic acid and the volume ratio of DEG/EG. • The nanoclusters exhibited superparamagnetic properties with high saturation magnetization value. • The 5-sulfosalicylic acid grafted Fe{sub 3}O{sub 4} nanoclusters can be dispersed in water.

Green, one-step and template-free synthesis of silver spongelike networks via a solvothermal method

International Nuclear Information System (INIS)

Yi, Zao; Xu, Xibin; Zhang, Kuibao; Tan, Xiulan; Li, Xibo; Luo, Jiangshan; Ye, Xin; Wu, Weidong; Wu, Jie; Yi, Yougen; Tang, Yongjian

2013-01-01

Silver spongelike networks were synthesized from an alkaline pH solution of silver nitrate and glucose under solvothermal conditions. The products were characterized by X-ray powder diffraction, UV–visible spectroscopy, transmission electron microscopy, scanning electron microscopy and selected area electron diffraction. These Ag nanoparticles (NPs) appear to undergo sequentially linear aggregation and welding initially, and then, they randomly cross link into self-supporting, three-dimensional (3D) networks with time. The carboxylate groups, generated by glucose oxidation, interacted with the Ag nanostructures, resulting in formation of silver spongelike networks having very uniform wire diameters distributions (about 20 nm in diameter). A new plasmon band was observed in the longer-wavelengths region (565–912 nm) of the conventional transverse plasmon resonance band at 430 nm. In principle, this one-step, template-free approach can also be extended to large-scale 3D organizations of other transition/noble metal NPs. - Graphical abstract: Silver spongelike networks were synthesized from an alkaline pH solution of silver nitrate and glucose under solvothermal conditions, with any other reducing or capping agent. These Ag nanoparticles appear to undergo sequentially linear aggregation and welding initially, and then, they randomly cross link into self-supporting, three-dimensional spongelike networks with time. Highlights: ► Silver spongelike networks were synthesized using eco-friendly glucose. ► This synthesis was a seedless process, and did not need any other surfactant or capping agent. ► The process was initial reduction – nucleation – adsorption – growth – branching

Solvothermal preparation of micro/nanostructured TiO{sub 2} with enhanced lithium storage capability

Energy Technology Data Exchange (ETDEWEB)

Li, Jie [School of Physics and Mechanical & Electronical Engineering, Hubei University of Education, Wuhan, 430205 (China); Wang, Chao [Department of Architecture and Material Engineering, Hubei University of Education, Wuhan, 430205 (China); Zheng, Ping; Zhang, Lei; Chen, Gongxuan [College of Chemistry and Life Science, Hubei University of Education, Wuhan, 430205 (China); Tang, Chengchun [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Wu, Tian, E-mail: twu@whu.edu.cn [School of Physics and Mechanical & Electronical Engineering, Hubei University of Education, Wuhan, 430205 (China); College of Chemistry and Life Science, Hubei University of Education, Wuhan, 430205 (China); Department of Architecture and Material Engineering, Hubei University of Education, Wuhan, 430205 (China)

2017-04-01

Facile and controllable preparation of TiO{sub 2} is of prime importance to elaborately tailor and then fully exploit its intriguing functionalities in energy storage, catalysis and environmental remediation. Herein, a solvothermal method combined with post annealing is conducted, in which the hydrolysis of tetrabutyl titanate is controlled by the in-situ generated water during solvothermal treatment. By controlling synthetic conditions (i.e. reactant ratio, solvothermal temperature and reaction time), we manage to tailor the morphologies of TiO{sub 2}. Specially, three typical structures (nanoparticle, nanoneedle and nanorod) are studied to reveal the growth mechanism and the effects of the synthesis conditions. Nanoneedle-structured TiO{sub 2} shows higher specific capacity and enhanced cycle stability as anode material for lithium ion batteries. - Highlights: • Controllable preparation of nano-TiO{sub 2} is achieved by a solvothermal method. • TiO{sub 2} morphology is tailored by tuning reactant ratio, temperature and duration. • Needle structured TiO{sub 2} shows enhanced lithium storage capability.

Synthesis and optical properties of CuS nanoplate-based architectures by a solvothermal method

International Nuclear Information System (INIS)

Li Fei; Kong Tao; Bi Wentuan; Li Dachang; Li Zhen; Huang Xintang

2009-01-01

The controlled synthesis of copper sulfide (CuS) nanoplate-based architectures in different solvents has been realized at low cost by simply reaction of Cu(NO 3 ) 2 .3H 2 O and S under solvothermal conditions without the use of any template. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectrometer and fluorescence measurement were used to characterize the products. The products were all in hexagonal phase with high crystallinity and the morphology was significantly influenced by the solvents. The CuS products synthesized in dimethylformamide (DMF) were nanoplates and the samples prepared in ethanol were flower-like morphology composed of large numbers of nanoplates, but those synthesized in ethylene glycol (EG) were CuS architectures with high symmetry made up of several nanoplates arranged in a certain mode. The optical properties were investigated and the growth mechanisms of these CuS crystals were also proposed.

One-pot solvothermal synthesis of ordered intermetallic Pt2In3 as stable and efficient electrocatalyst towards direct alcohol fuel cell application

Science.gov (United States)

Jana, Rajkumar; Peter, Sebastian C.

2016-10-01

Ordered intermetallic Pt2In3 nanoparticles have been synthesized by superhydride reduction of K2PtCl4 and InCl3.xH2O precursors using facile, one-pot solvothermal method. We report surfactant free solvothermal synthesis of a novel ordered Pt2In3 intermetallic nanoparticles for the first time. The structure and morphology of the catalyst has been confirmed by powder X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive spectrometry and X-ray photoelectron spectroscopy. The electrocatalytic properties of the catalysts have been investigated by cyclic voltammetry and chronoamperometry. The as prepared Pt2In3 catalyst exhibit far superior electrocatalytic activity and stability towards alcohol oxidation over commercial Pt/C. The specific activity of as synthesized catalyst was found to be 3.2 and 2.3 times higher than commercial Pt/C for methanol and ethanol oxidation, respectively. This improved activity and durability of the Pt2In3 nanoparticles can make the catalyst an ideal catalyst candidate for direct alcohol fuel cell.

Polyol-mediated synthesis of copper indium sulphide by solvothermal process

International Nuclear Information System (INIS)

Gorai, S.; Chaudhuri, S.

2005-01-01

A simple polyol-mediated solvothermal method has been proposed to synthesize copper indium sulphide. XRD studies reveal that the products are well crystallized. SEM indicates rod-like (with different aspect ratio) and star-shaped flake-like morphology of the products. The products are also characterized by optical studies and compositional analysis (XRF). XRF results show the formation of stoichiometric and non-stoichiometric copper indium sulphides depending on the reaction conditions

Solvothermal synthesis of LiFePO4 nanoplates with (010) plane and the uniform carbon coated on their surface by esterification reaction

International Nuclear Information System (INIS)

Ma, Zhipeng; Shao, Guangjie; Wang, Xu; Song, Jianjun; Wang, Guiling; Liu, Tingting

2014-01-01

A facile solvothermal synthesis and esterification reaction combined with a high temperature calcination technique has been developed to prepare the uniform carbon coating LiFePO 4 nanoplates. The carbon coating LiFePO 4 nanoplates are investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatic intermittent titration technique (GITT) and galvanostatic charge–discharge test. A reasonable growth mechanism of LiFePO 4 nanoplates is proposed on the basis of time dependent experimental results. The results show that each nanoplate is a LiFePO 4 single crystal with the large (010) plane. According to Raman spectroscopy analysis, carbon is uniformly coated on the surface of LiFePO 4 nanoplates. Electrochemical test results also indicate that the carbon coating LiFePO 4 nanoplates exhibit a high reversible specific capacity of 144.8 mAh g −1 at 0.5 C and 116.9 mAh g −1 under lower discharging rate at −20 °C. - Highlights: • LiFePO 4 nanoplates prepared by facile solvothermal synthesis expose large (010) plane. • The polyester network formed by the esterification reaction could entirely wrap LiFePO 4 . • The polyester wrapped on the surface of LiFePO 4 transformed into the uniform carbon layer after calcination. • LiFePO 4 /C nanoplates have good high-rate and low-temperature performance

Water-assisted and surfactant-free synthesis of cobalt ferrite nanospheres via solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Bi, Yiqing [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Ren, Yanan [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); Bi, Feng [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); He, Tao, E-mail: het@nanoctr.cn [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China)

2015-10-15

With ethylene glycol as the solvent, monodispersed cobalt ferrite nanospheres were prepared via a solvothermal method assisted by water. The samples were mainly characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. The size of as-prepared products ranges from 10 nm to 200 nm. Size distribution and chemical composition were controlled by the amount of water and pH value in the reaction system. More important, suitable amount of water can avoid the use of surfactant. - Highlights: • Cobalt ferrite nanospheres were synthesized via solvothermal method assisted by water. • An introduction of suitable amount of water can avoid the use of surfactant. • The pH value of the precursor can be used to adjust the product composition.

Solvothermal Synthesis of Copper Indium Diselenide in Toluene

International Nuclear Information System (INIS)

Chang, Ju Yeon; Han, Jae Eok; Jung, Duk Young

2011-01-01

Polycrystalline CuInSe 2 (CIS) was synthesized through solvothermal reactions in toluene with selected alkyl amines as complexing agents. The alkyl amines were used as reducing agent of selenium and catalytic ligands, enhancing the formation of CIS compounds in the colloidal solution. Toluene does not contribute the syntheses directly but minimizes the amounts of amines required for single phase CIS. We systematically studied the reactivity of amine compounds for the solovothermal syntheses, determined critical concentration of amine and the shortest reaction time. Crystallinity, morphology, chemical composition, and band gap of the prepared CuInSe 2 were respectively measured by X-ray diffraction, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy and UV-vis spectroscopy

One-pot solvothermal synthesis of ordered intermetallic Pt{sub 2}In{sub 3} as stable and efficient electrocatalyst towards direct alcohol fuel cell application

Energy Technology Data Exchange (ETDEWEB)

Jana, Rajkumar; Peter, Sebastian C., E-mail: sebastiancp@jncasr.ac.in

2016-10-15

Ordered intermetallic Pt{sub 2}In{sub 3} nanoparticles have been synthesized by superhydride reduction of K{sub 2}PtCl{sub 4} and InCl{sub 3}.xH{sub 2}O precursors using facile, one-pot solvothermal method. We report surfactant free solvothermal synthesis of a novel ordered Pt{sub 2}In{sub 3} intermetallic nanoparticles for the first time. The structure and morphology of the catalyst has been confirmed by powder X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive spectrometry and X-ray photoelectron spectroscopy. The electrocatalytic properties of the catalysts have been investigated by cyclic voltammetry and chronoamperometry. The as prepared Pt{sub 2}In{sub 3} catalyst exhibit far superior electrocatalytic activity and stability towards alcohol oxidation over commercial Pt/C. The specific activity of as synthesized catalyst was found to be ~3.2 and ~2.3 times higher than commercial Pt/C for methanol and ethanol oxidation, respectively. This improved activity and durability of the Pt{sub 2}In{sub 3} nanoparticles can make the catalyst an ideal catalyst candidate for direct alcohol fuel cell. - Graphical abstract: The ordered structure of Pt{sub 2}In{sub 3} nanoparticles synthesized by solvothermal method has confirmed through XRD and TEM. Cyclic voltametry and chronoamperometry showed improved catalytic activity and stability compared to commercial Pt/C. - Highlights: • Ordered Pt{sub 2}In{sub 3} nanoparticles were synthesized by solvothermal method. • Electrooxidation of alcohols on Pt{sub 2}In{sub 3} catalyst was investigated in acidic medium. • Pt{sub 2}In{sub 3} catalyst has superior catalytic activity compared to commercial Pt/C. • Pt{sub 2}In{sub 3} catalyst exhibited much higher stability than commercial Pt/C.

Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors.

Science.gov (United States)

Santos, Lídia; Nunes, Daniela; Calmeiro, Tomás; Branquinho, Rita; Salgueiro, Daniela; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

2015-01-14

Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 × 10(6), threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm(2)/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping.

Solvothermal synthesis of copper sulfide semiconductor micro/nanostructures

International Nuclear Information System (INIS)

Liu, Jun; Xue, Dongfeng

2010-01-01

Covellite copper sulfide (CuS) micro/nanometer crystals in the shape of hierarchical doughnut-shaped, superstructured spheric-shaped and flowerlike architectures congregated from those nanoplates with the thickness of 20-100 nm have been prepared by a solvothermal method. The as-obtained CuS products were characterized by means of scanning electron microscopy (SEM), X-ray diffractometry (XRD) and energy-dispersive X-ray spectroscopy (EDS). A systematic investigation has been carried out to understand the factors influencing the evolution of CuS particle morphology which found to be predominant by solvent, surfactant, sulfur resource and copper salt. The possible formation mechanism for the nanostructure formation was also discussed. These CuS products show potential applications in solar cell, photothermal conversion and chemical sensor.

Low-temperature solvothermal approach to the synthesis of La4Ni3O8 by topotactic oxygen deintercalation.

Science.gov (United States)

Blakely, Colin K; Bruno, Shaun R; Poltavets, Viktor V

2011-07-18

A chimie douce solvothermal reduction method is proposed for topotactic oxygen deintercalation of complex metal oxides. Four different reduction techniques were employed to qualitatively identify the relative reduction activity of each including reduction with H(2) and NaH, solution-based reduction using metal hydrides at ambient pressure, and reduction under solvothermal conditions. The reduction of the Ruddlesden-Popper nickelate La(4)Ni(3)O(10) was used as a test case to prove the validity of the method. The completely reduced phase La(4)Ni(3)O(8) was produced via the solvothermal technique at 150 °C--a lower temperature than by other more conventional solid state oxygen deintercalation methods.

Novel Evaporation Process for Deposition of Kesterite Thin Films Synthesized by Solvothermal Method

Directory of Open Access Journals (Sweden)

J. A. Estrada-Ayub

2017-01-01

Full Text Available Kesterite, a quaternary compound of Cu2ZnSnS4, is a promising option as a material absorber to reduce the cost of photovoltaic solar cells. The solvothermal method is a way to synthesize nanoparticles of this material. In this work, once synthesized, particles were deposited on a substrate through evaporation, and their morphological, structural, and optical properties were studied. Results show that changes of precursor ratios during solvothermal synthesis result in a modification of particle morphology but not on its size. The deposition of already synthesized kesterite through evaporation preserves kesterite structure and permits the formation of a homogenous film on a substrate. Optical reflectance and transmittance measurements allowed estimating the band-gap energy between 1.41 and 1.46 eV for representative samples, which is near the optimum for the absorber material.

Hierarchical structures of ZnO spherical particles synthesized solvothermally

Science.gov (United States)

Saito, Noriko; Haneda, Hajime

2011-12-01

We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.

Solvothermal synthesis and electrochemical performance of Li2MnSiO4/C cathode materials for lithium ion batteries

International Nuclear Information System (INIS)

Wang, Yan-Chao; Zhao, Shi-Xi; Zhai, Peng-Yuan; Li, Fang; Nan, Ce-Wen

2014-01-01

Highlights: • Li 2 MnSiO 4 /C nanocomposite has been synthesized by the solvothermal method. • The particles of Li 2 MnSiO 4 /C are much smaller and more uniform. • The presence of Ni improves discharge capacity of Li 2 MnSiO 4 /C cathode material. • The initial discharge capacity of Ni-modified Li 2 MnSiO 4 /C is 274.5 mAh g −1 at 25 °C. - Abstract: Orthorhombic structure Li 2 MnSiO 4 /C with Pmn2 1 space group is synthesized by the solvothermal method. Carbon coating and Ni 2+ doping are used to improve the electronic conductivity and the cycling performance of Li 2 MnSiO 4 cathode material, respectively. The particles of Li 2 MnSiO 4 /C are much smaller and more uniform than those of Li 2 MnSiO 4 due to the carbon coating. It is shown that Ni 2+ has been reduced into metal Ni during the synthesis process. The synthesized Ni-modified Li 2 MnSiO 4 /C (denoted as (LMS@Ni)/C) cathode material exhibits better electrochemical performance in comparison with Li 2 MnSiO 4 /C, attributing to higher lithium ion diffusion coefficient as well as electronic conductivity. The initial discharge capacity of (LMS@Ni)/C is 274.5 mA h g −1 and the reversible capacity after 20 cycles is 119.8 mA h g −1 at 25 °C

Effects of hydrazine on the solvothermal synthesis of Cu2ZnSnSe4 and Cu2CdSnSe4 nanocrystals for particle-based deposition of films

International Nuclear Information System (INIS)

Chiang, Ming-Hung; Fu, Yaw-Shyan; Shih, Cheng-Hung; Kuo, Chun-Cheng; Guo, Tzung-Fang; Lin, Wen-Tai

2013-01-01

The effects of hydrazine on the synthesis of Cu 2 ZnSnSe 4 (CZTSe) and Cu 2 CdSnSe 4 (CCTSe) nanocrystals in an autoclave as a function of temperature and time were explored. On heating at 190 °C for 24-72 h, pure CZTSe and CCTSe nanocrystals could readily grow in the hydrazine-added solution, while in the hydrazine-free solution the intermediate phases such as ZnSe, Cu 2 Se, and Cu 2 SnSe 3 , and Cu 2 SnSe 3 and CdSe associated with the CZTSe and CCTSe nanocrystals grew, respectively. This result reveals that hydrazine can speed up the synthesis of pure CZTSe and CCTSe nanocrystals via a solvothermal process. The mechanisms for the hydrazine-enhanced growth of CZTSe and CCTSe nanocrystals were discussed. The pure CZTSe and CCTSe nanocrystals were subsequently fabricated to the smooth films by spin coating without further annealing in selenium atmosphere. This processing may be beneficial to the fabrication of the absorber layer for solar cells and thermoelectric devices. - Highlights: • Hydrazine enhances the growth of pure Cu 2 ZnSnSe 4 and Cu 2 CdSnSe 4 nanocrystals. • The nanocrystals can be fabricated to films by spin coating without annealing. • This solvothermal processing is promising for the fabrication of thin film devices

Scaled-up solvothermal synthesis of nanosized metastable indium oxyhydroxide (InOOH) and corundum-type rhombohedral indium oxide (rh-In{sub 2}O{sub 3})

Energy Technology Data Exchange (ETDEWEB)

Schlicker, Lukas; Bekheet, Maged F.; Gurlo, Aleksander [Technische Univ. Berlin (Germany). Fachgebiet Keramische Werkstoffe

2017-03-01

Phase pure metastable indium oxyhydroxide (InOOH) with crystallite size in the range ca. 2-7 nm is synthesized by a nonaqueous solvothermal synthesis route in ethanol. The influence of synthesis parameters such as temperature, basicity (pH), synthesis time, and water content is carefully addressed. T-pH maps summarize the impact of synthesis temperature and pH and reveal that phase pure InOOH is obtained in water-free solutions at mild temperatures (150-180 C) in highly basic conditions (pH>12). Subsequent calcination of InOOH at 375-700 C in ambient air atmosphere results in metastable nanoscaled rhombohedral indium oxide (rh-In{sub 2}O{sub 3}). The synthesis protocol for phase pure nanocrystalline InOOH material was successfully upscaled allowing for obtaining ca. 3 g of phase-pure InOOH with a yield of ca. 78%. The upscaled InOOH and rh-In{sub 2}O{sub 3} batches are now available for a detailed in-situ characterization of the mechanism of decomposition of InOOH to rh-In{sub 2}O{sub 3} to c-In{sub 2}O{sub 3} as well as for the characterization of the functional properties of InOOH and rh-In{sub 2}O{sub 3} materials.

Simple synthesis of ultra-long Ag2Te nanowires through solvothermal co-reduction method

International Nuclear Information System (INIS)

Xiao Feng; Chen Gang; Wang Qun; Wang Lin; Pei Jian; Zhou Nan

2010-01-01

Ultra-long single crystal β-Ag 2 Te nanowires with the diameter of about 300 nm were fabricated through a solvothermal route in ethylene glycol (EG) system without any template. The long single crystal wires were curves, with high purity, well-crystallized, and dislocation-free and characterized by using X-ray powder diffraction (XRD), Differential scanning calorimetry (DSC) analysis, X-ray photoelectron spectroscope (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission microscopy (HRTEM). The detailed topotactic transformation process from particles into single crystal wires was studied. Furthermore, the electrical conductivity and Seebeck coefficient have been systematically studied between 300 and 600 K. - Graphical abstract: Ultra-long single crystal β-Ag 2 Te nanowires with the diameter of about 300 nm were fabricated by the solvothermal route in ethylene glycol (EG) system without any template. The diagram displays the variation of the phases and morphologies of products with different reaction time.

Solvothermal synthesis of hierarchical TiO{sub 2} nanostructures with tunable morphology and enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Fan, Zhenghua [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Meng, Fanming, E-mail: mrmeng@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Key laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Zhang, Miao [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Wu, Zhenyu [College of Chemistry & Chemical Engineering, Anhui University, Hefei 230601 (China); Sun, Zhaoqi; Li, Aixia [School of Physics and Materials Science, Anhui University, Hefei 230601 (China)

2016-01-01

Graphical abstract: - Highlights: • Hierarchical anatase TiO{sub 2} nanostructures with enhanced photocatalytic activity are synthesized by solvothermal method. • A mechanism for enhanced photocatalytic activity of chrysanthemum-like hierarchical TiO{sub 2} nanostructures is proposed. • A possible formation mechanism is suggested to explain the transformation from rose-like to chrysanthemum-like, and to sea-urchin-like. - Abstract: This paper presents controllable growth and photocatalytic activity of TiO{sub 2} hierarchical nanostructures by solvothermal method at different temperatures. It is revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the morphology of TiO{sub 2} can be effectively controlled as rose-like, chrysanthemum-like and sea-urchin-like only changing solvothermal temperature. BET surface area analysis confirms the presence of a mesoporous network in all the nanostructures, and shows high surface area at relatively high temperature. The photocatalytic activities of the photocatalysts are evaluated by the photodegradation of RhB under UV light irradiation. The TiO{sub 2} samples exhibit high activity on the photodegradation of RhB, which is higher than that of the commercial P25. The enhancement in photocatalytic performance can be attributed to the synergetic effect of the surface area, crystallinity, band gap and crystalline size.

Solvothermal crystallization of nanocrystals of metal oxides

International Nuclear Information System (INIS)

Furukawa, S; Amino, H; Iwamoto, S; Inoue, M

2008-01-01

Solvothermal crystallization of the hydroxide gels obtained by hydrolysis of alkoxides (Zr, Ta, Nb, ln, Sn, Ti and Al) was examined. Nanocrystals having high surface areas (S BET > 170 m 2 g -1 ) were obtained except for the product derived from indium isopropoxide. The effect of water in organic solvent upon the crystallinity of the product was investigated. The increase in the activity of water by using high concentration of alkoxide or intentional addition of water to the solvothermal medium led to crystal growth of the products. In contrast, decrease in activity of water by adding ethylene glycol before solvothermal treatment caused a decrease in crystallinity of the product

Solvothermal crystallization of nanocrystals of metal oxides

Science.gov (United States)

Furukawa, S.; Amino, H.; Iwamoto, S.; Inoue, M.

2008-07-01

Solvothermal crystallization of the hydroxide gels obtained by hydrolysis of alkoxides (Zr, Ta, Nb, ln, Sn, Ti and Al) was examined. Nanocrystals having high surface areas (SBET > 170 m2 g-1) were obtained except for the product derived from indium isopropoxide. The effect of water in organic solvent upon the crystallinity of the product was investigated. The increase in the activity of water by using high concentration of alkoxide or intentional addition of water to the solvothermal medium led to crystal growth of the products. In contrast, decrease in activity of water by adding ethylene glycol before solvothermal treatment caused a decrease in crystallinity of the product.

Solvothermal synthesis and electrochemical performance of hollow LiFePO{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zheng, Zhenmiao [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Pang, Wei Kong [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Tang, Xincun, E-mail: tangxincun@163.com [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Jia, Dianzeng; Huang, Yudai [Institute of Applied Chemistry, Xinjiang University, Urumqi 840046 (China); Guo, Zaiping [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia)

2015-08-15

Highlights: • Hollow LiFePO{sub 4} nanoparticles were successfully synthesized via solvothermal method. • The shorter b lattice parameter allows the shorter diffusion path of lithium ion. • Hollow LiFePO{sub 4} nanoparticles show better rate capability than solid LiFePO{sub 4}. - Abstract: Hollow LiFePO{sub 4} nanoparticles were synthesized via a solvothermal technique, using ammonium tartrate as additive and carbon source, and ethylene glycol/water as solvent. The as-prepared samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning and transmission electron microscopies, and Brunauer–Emmett–Teller specific surface area measurements. The electrochemical properties of the LiFePO{sub 4} cathode were examined in coin-type cell configuration and the cathode exhibited excellent rate capability (i.e., discharge capacity of 120.9 mA h g{sup −1} at 10 C) and cycling performance (i.e., >98% of capacity retention rate after 50 cycles). It is believed that the enhanced performance is correlated to the hollow structure, small crystallite and particle sizes, and relatively shorter lattice parameter b.

TiO2 synthesized by microwave assisted solvothermal method: Experimental and theoretical evaluation

International Nuclear Information System (INIS)

Moura, K.F.; Maul, J.; Albuquerque, A.R.; Casali, G.P.; Longo, E.; Keyson, D.; Souza, A.G.; Sambrano, J.R.; Santos, I.M.G.

2014-01-01

In this study, a microwave assisted solvothermal method was used to synthesize TiO 2 with anatase structure. The synthesis was done using Ti (IV) isopropoxide and ethanol without templates or alkalinizing agents. Changes in structural features were observed with increasing time of synthesis and evaluated using periodic quantum chemical calculations. The anatase phase was obtained after only 1 min of reaction besides a small amount of brookite phase. Experimental Raman spectra are in accordance with the theoretical one. Micrometric spheres constituted by nanometric particles were obtained for synthesis from 1 to 30 min, while spheres and sticks were observed after 60 min. - Graphical abstract: FE-SEM images of anatase obtained with different periods of synthesis associated with the order–disorder degree. Display Omitted - Highlights: • Anatase microspheres were obtained by the microwave assisted hydrothermal method. • Only ethanol and titanium isopropoxide were used as precursors during the synthesis. • Raman spectra and XRD patterns were compared with quantum chemical calculations. • Time of synthesis increased the short-range disorder in one direction and decreased in another

Ultra-flexible lithium ion batteries fabricated by electrodeposition and solvothermal synthesis

International Nuclear Information System (INIS)

Wang, Jian; Zhang, Lei; Zhou, Qingwen; Wu, Wenlu; Zhu, Chao; Liu, Ziqiang; Chang, Shaozhong; Pu, Jun; Zhang, Huigang

2017-01-01

Cathodes have been one of the major challenges of flexible batteries. The traditional slurry-based technologies lead to loose interparticle connection, which is vulnerable upon bending. The direct fabrication of cathode materials requires high temperatures, which may destroy flexible substrates. Here we developed an electrodepostion and solvothermal route to conformally coat cathode material on a flexible scaffold. The monolithic electrode enables an ultra-flexible lithium ion battery because of the close attachment of active materials to flexible scaffolds and the interlock effect between the hard shell and soft core. This ultra-flexible battery retains 58.8% of initial capacity even after bending 4000 cycles.

Silver nanoparticles: Large scale solvothermal synthesis and optical properties

Energy Technology Data Exchange (ETDEWEB)

Wani, Irshad A.; Khatoon, Sarvari [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmed, Jahangeer; Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmad, Tokeer, E-mail: tokeer.ch@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)

2010-08-15

Silver nanoparticles have been successfully synthesized by a simple and modified solvothermal method at large scale using ethanol as the refluxing solvent and NaBH{sub 4} as reducing agent. The nanopowder was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-visible and BET surface area studies. XRD studies reveal the monophasic nature of these highly crystalline silver nanoparticles. Transmission electron microscopic studies show the monodisperse and highly uniform nanoparticles of silver of the particle size of 5 nm, however, the size is found to be 7 nm using dynamic light scattering which is in good agreement with the TEM and X-ray line broadening studies. The surface area was found to be 34.5 m{sup 2}/g. UV-visible studies show the absorption band at {approx}425 nm due to surface plasmon resonance. The percentage yield of silver nanoparticles was found to be as high as 98.5%.

Facile solvothermal synthesis of graphene-MnOOH nanocomposites

International Nuclear Information System (INIS)

Chen Sheng; Zhu Junwu; Huang Huajie; Zeng Guiyu; Nie Fude; Wang Xin

2010-01-01

In this paper, we report a facile solvothermal route capable of aligning MnOOH nanocrystals on graphene. X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations indicate that the exfoliated graphene sheets are decorated randomly by MnOOH nanocrystals, forming well-dispersed graphene-MnOOH nanocomposites. Dissolution-crystallization and oriented attachment are speculated to be the vital mechanisms in the synthetic process. The attachment of additives, such as MnOOH nanoparticles, are found to be beneficial for the exfoliation of GO as well as preventing the restack of graphene sheets. Moreover, cyclic voltammetry (CV) analyses suggest that the electrochemical reversibility is improved by anchoring MnOOH on graphene. Notably, the as-fabricated nanocomposites reveal unusual catalytic performance for the thermal decomposition of ammonium perchlorate (AP) due to the concerted effects of graphene and MnOOH. This template-free method is easy to reproduce, and the process proceeds at a low temperature and can be readily extended to prepare other graphene-based nanocomposites. - Graphical abstract: Manganese oxyhydroxide nanocrystals have been successfully attached onto the graphene sheets via an oriented attachment and dissolution-crystallization process, forming a nanocomposite with unusual catalytic capabilities. Display Omitted

Utilization of solvothermally grown InP/ZnS quantum dots as wavelength converters for fabrication of white light-emitting diodes.

Science.gov (United States)

Jang, Eun-Pyo; Yang, Heesun

2013-09-01

This work reports on a simple solvothermal synthesis of InP/ZnS core/shell quantum dots (QDs) using a much safer and cheaper phosphorus precursor of tris(dimethylamino)phosphine than the most popularly chosen tris(trimethylsilyl)phosphine. The band gap of InP QDs is facilely controlled by varying the solvothermal core growth time (4 vs. 6 h) with a fixed temperature of 150 degrees C, and the successive solvothermal ZnS shelling at 220 degrees C for 6 h results in green- and yellow-emtting InP/ZnS QD with emission quantum yield of 41-42%. The broad size distribution of as-synthesized InP/ZnS QDs, which appears to be inherent in the current solvothermal approach, is improved by a size-selective sorting procedure, and the emission properties of the resulting size-sorted QD fractions are investigated. To produce white emission for general lighting source, a blue light-emitting diode (LED) is combined with non-size-soroted green or yellow QDs as wavelength converters. Furthermore, the QD-LED that includes a blend of green and yellow QDs is fabricated to generate a white lighting source with an enhanced color rendering performance, and its electroluminescent properties are characterized in detail.

Tin phosphide-based anodes for sodium-ion batteries: synthesis via solvothermal transformation of Sn metal and phase-dependent Na storage performance

Science.gov (United States)

Shin, Hyun-Seop; Jung, Kyu-Nam; Jo, Yong Nam; Park, Min-Sik; Kim, Hansung; Lee, Jong-Won

2016-01-01

There is a great deal of current interest in the development of rechargeable sodium (Na)-ion batteries (SIBs) for low-cost, large-scale stationary energy storage systems. For the commercial success of this technology, significant progress should be made in developing robust anode (negative electrode) materials with high capacity and long cycle life. Sn-P compounds are considered promising anode materials that have considerable potential to meet the required performance of SIBs, and they have been typically prepared by high-energy mechanical milling. Here, we report Sn-P-based anodes synthesised through solvothermal transformation of Sn metal and their electrochemical Na storage properties. The temperature and time period used for solvothermal treatment play a crucial role in determining the phase, microstructure, and composition of the Sn-P compound and thus its electrochemical performance. The Sn-P compound prepared under an optimised solvothermal condition shows excellent electrochemical performance as an SIB anode, as evidenced by a high reversible capacity of ~560 mAh g−1 at a current density of 100 mA g−1 and cycling stability for 100 cycles. The solvothermal route provides an effective approach to synthesising Sn-P anodes with controlled phases and compositions, thus tailoring their Na storage behaviour. PMID:27189834

Facile and low temperature route to synthesis of CuS nanostructure in mesoporous material by solvothermal method.

Science.gov (United States)

Sohrabnezhad, Sh; Zanjanchi, M A; Hosseingholizadeh, S; Rahnama, R

2014-04-05

The synthesis of CuS nanomaterial in MCM-41 matrix has been realized by chemical synthesis between MCM-41, copper sulfate pentahydrate and thiourea via a solvothermal method in ethylene glycol and water, separately. X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared (FT-IR) were used to characterize the products. At synthesized CuS/MCM-41 sample in ethylene glycol, X-ray diffraction and diffuse reflectance spectroscopy showed pure covellite phase of copper sulfide with high crystality. But prepared CuS/MCM-41 sample in water shows the covellite, chalcocite and the djurleite phase of copper sulfide nanostructures. The formation of CuS nanostructures was confirmed by FT-IR. Photocatalytic activity of CuS/MCM-41 nanocomposites was studied for degradation of Methylene Blue (MB) under visible light. The CuS/MCM-41 nanocomposite is more effective nanocatalyst than synthesized CuS/MCM-41 sample in water for degradation of methylene blue. Several parameters were examined, catalyst amount (0.1-1gL(-1)), pH (1-13) and initial concentration of MB (0.96-10ppm). The extent of degradation was estimated from the residual concentration by spectrophotometrically. The support size was obtained in the range 60-145nm by TEM. In the same way, the average size of copper sulfide in CuSMCM-41E and CuS/MCM-41W nanostructures were obtained about 10nm and 16nm, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation and thermoelectric properties of sulfur doped Ag2Te nanoparticles via solvothermal methods.

Science.gov (United States)

Zhou, Wenwen; Zhao, Weiyun; Lu, Ziyang; Zhu, Jixin; Fan, Shufen; Ma, Jan; Hng, Huey Hoon; Yan, Qingyu

2012-07-07

In this work, n-type Ag(2)Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 10(20) cm(-3). This allows us to achieve the desired electrical resistivities of nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K.

The role anions on the synthesis of AlOOH nanoparticles using simple solvothermal method

Directory of Open Access Journals (Sweden)

Mozaffar Abdollahifar

2018-03-01

Full Text Available Effect of aluminium salts on the synthesis of AlOOH nanostructures has been successfully investigated in detail using solvothermal method, when ethanol and NaOH are solvent and pH adjusting agent, respectively. Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, and field emission scanning electron microscopy (FESEM, were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore structure of the different AlOOH structures were also discussed by the N2 adsorption/desorption test. According to our experimental results, the structure characterization revealed that for synthesized AlOOH nanostructures no obvious XRD peaks arising from other phases of alumina are found indicating pure AlOOH phase of products. Furthermore, the nitrogen adsorption and desorption measurements indicated that the obtained AlOOH nanoparticles from aluminium chloride at basic condition possess a high BET surface area of approximately 90 m2/g. Resumen: El efecto de las sales de aluminio sobre la síntesis de las nanoestructuras de AlOOH ha sido analizado en detalle satisfactoriamente usando el método solvotérmico, cuando el etanol y el NaOH son el disolvente y el agente de regulación del pH, respectivamente. Para clasificar las muestras sintetizadas se utilizaron la espectroscopia infrarroja por transformada de Fourier (FTIR, difracción de rayos X por polvo (XRD y microscopia electrónica de barrido de emisión de campo (FESEM. El área superficial específica, la distribución del tamaño del poro y la estructura de poros de las diferentes estructuras de AlOOH también se debatieron mediante la prueba de adsorción/desorción de N2. De acuerdo con nuestros resultados experimentales, la clasificación de la estructura reveló que en las nanoestructuras de AlOOH sintetizadas no se observan picos XRD evidentes derivados de otras fases de la alúmina que indican la fase pura de AlOOH de los productos

One-step solvothermal synthesis, a worm-shaped morphology and luminescence properties of green-emitting Y2O2S:Tb3+ nanophosphors

Science.gov (United States)

Liu, Fan; Lian, Jingbao; Wu, Nianchu; He, Jiao; Zhang, Xue; Liu, Feng

2018-02-01

The worm-shaped Y2O2S:Tb3+ nanophosphors have been successfully prepared via one-step solvothermal synthesis, using ethanediamine as the main solvent and sublimed sulfur powder as the source of sulfur without adding additional structure-directing reagents. XRD, FT-IR, FESEM, PL and CIE chromaticity diagram were used to characterize the obtained products. XRD results demonstrate that all diffraction peaks of the sample can be well indexed to pure hexagonal phase of Y2O2S with optimal condition, i.e. the molar ration of S/Y3+m = 10, solvothermal temperature T = 220 °C and synthetic time t = 24 h. When t varies from 2 h to 24 h, the morphology of Y2O2S transforms from cauliflower-like structure to worm-shaped nanoparticles with the length of ∼80 nm. The formation mechanism depending on t has also been proposed. Upon 250 nm ultraviolet (UV) light excitation, the worm-shaped Y2O2S:Tb3+ nanophosphors exhibit green emissions, corresponding to the 5D4 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ions. The quenching concentration is 7% and its corresponding lifetime is 1216 μs. The CIE chromaticity coordinates show the tuneable emission shifting from yellow green to yellowish green with increasing concentration of Tb3+ions from 1% to 7%. Those results suggest that the worm-shaped Y2O2S:Tb3+ nanophosphors may have potential applications in X-ray intensifying screens, fluorescence and biomedical fields.

Phase controlled solvothermal synthesis of Cu_2ZnSnS_4, Cu_2ZnSn(S,Se)_4 and Cu_2ZnSnSe_4 Nanocrystals: The effect of Se and S sources on phase purity

International Nuclear Information System (INIS)

Pal, Mou; Mathews, N.R.; Paraguay-Delgado, F.; Mathew, X.

2015-01-01

In this study, we have reported the synthesis of Cu_2ZnSnSe_4 (CZTSe), Cu_2ZnSnS_4 (CZTS) and Cu_2ZnSn(S,Se)_4 (CZTSSe) nanocrystals with tunable band gap and composition obtained by solvothermal method. The crystalline structure, composition, morphology and optical properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman scattering, energy dispersive X-ray spectroscopy, transmission electron microscopy and diffuse reflectance (DR) spectroscopy. While the XRD patterns of CZTS and CZTSe nanoparticles prepared with elemental S/Se powder revealed the presence of phase pure nanoparticles, the CZTSSe nanoparticles obtained using a mixture of S and Se, were found to contain many secondary phases under the same synthesis protocol. Formation of impurity phases in CZTSSe sample, can be avoided by using a mixture of 1-dodecanethiol (DT; CH_3(CH_2)_1_1SH)/oleylamine (OLA) instead of S powder and following the same experimental procedure. The incorporation of S in CZTSe nanocrystals prepared in presence of DDT/OLA mixture was confirmed through structural and optical characterizations. The optical properties of the quaternary chalcogenide nanocrystals were found to vary with the chemical composition of the material. - Highlights: • Solvothermal synthesis of CZTS, CZTSSe and CZTSe nanocrystals and discussion on possible formation mechanism. • Use of dodecanethiol/oleylamine mixture to synthesize phase-pure CZTSSe nanocrystals. • Formation of impurity phases can be controlled with proper S and Se sources.

Facile Solvothermal Synthesis of BiOCl/ZnO Heterostructures with Enhanced Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Yong-Fang Li

2014-01-01

Full Text Available Well-defined nanosheet-assembled (BiOClx(ZnO1−x nanoflowers were synthesized by a solvothermal method. It was found that ZnO nanoparticles were anchored on the flower-like BiOCl nanostructures, as demonstrated by varying the initial compositions of the Bi precursor and the volume ratios of mixed solvents (ethylene glycol to water. The as-prepared (BiOCl0.6(ZnO0.4 nanocomposites showed enhanced photocatalytic activity toward rhodamine B degradation under ultraviolet (UV irradiation. And the photocatalytic mechanism was discussed in detail.

From dihydrated iron(III) phosphate to monohydrated ammonium-iron(II) phosphate: Solvothermal reaction mediated by acetone-urea mixtures

Energy Technology Data Exchange (ETDEWEB)

Alfonso, Belen F., E-mail: mbafernandez@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain); Trobajo, Camino [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo-CINN, Julian Claveria 8, 33006 Oviedo (Spain); Pique, Carmen [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain); Garcia, Jose R. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo-CINN, Julian Claveria 8, 33006 Oviedo (Spain); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain)

2012-12-15

By reaction between synthetic phosphosiderite FePO{sub 4}{center_dot}2H{sub 2}O, urea (NH{sub 2}){sub 2}CO, and acetone (CH{sub 3}){sub 2}CO, we report a novel solvothermal synthesis of polycrystalline NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O. The preparation of other two individual phases, NH{sub 4}Fe{sub 2}(OH)(PO{sub 4}){sub 2}{center_dot}2H{sub 2}O and NH{sub 4}Fe{sub 2}(PO{sub 4}){sub 2}, is also described. The obtained product is a function of the reaction time and the N/P molar ratio in the reagent mixture, and the existence of structural memory in the dissolution-precipitation processes is discussed. Below 25 K, NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O behaves magnetically in a complex way, because both ferromagnetic and antiferromagnetic signals are superimposed, suggesting the existence of a canting of iron(II) magnetic moments. - Graphical abstract: Solvothermal synthesis of polycrystalline NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O is presented. The preparation of other two individual phases, NH{sub 4}Fe{sub 2}(OH)(PO{sub 4}){sub 2}{center_dot}2H{sub 2}O and NH{sub 4}Fe{sub 2}(PO{sub 4}){sub 2} as a function of the N/P molar ratio in the reagent mixture and the reaction time, is also described. Highlights: Black-Right-Pointing-Pointer Solvothermal synthesis of NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O from an Fe(III) phosphate: reduction process. Black-Right-Pointing-Pointer Formation of two intermediate metastable phases: phase diagram. Black-Right-Pointing-Pointer Thermal decomposition in two steps: mass loss of both water and ammonia. Black-Right-Pointing-Pointer Magnetic behaviour: AF+constant spontaneous magnetization.

Solvothermal synthesis and enhanced CO2 adsorption ability of mesoporous graphene oxide-ZnO nanocomposite

International Nuclear Information System (INIS)

Li, Weidong; Jiang, Xia; Yang, Huayun; Liu, Qi

2015-01-01

Highlights: • GO–ZnO nanocomposite was prepared by solvothermal method. • Several technologies have been used to ensure and analyze the composite. • GO–ZnO has CO 2 adsorption capacity of up to 44.8 cm 3 /g at 298 K and 1 bar. • The composite has excellent adsorption/desorption recycling ability. - Abstract: Mesoporous graphene oxide–ZnO (GO–ZnO) nanocomposite has been synthesized by GO and ZnO which was prepared by solvothermal method. Power X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to characterize the structure and morphology of the porous GO–ZnO hybrid. With visible porosity of ZnO and GO–ZnO, N 2 adsorption–desorption measurements and pore size analysis have been investigated and compared. Comparing to ZnO, GO–ZnO showed larger Brunauer–Emmett–Teller (BET) surface area and enhanced ability on capturing CO 2 at different temperatures. Several cycles of adsorption–desorption experiments on CO 2 have been tested and it proved GO–ZnO to be potential adsorbent material with excellent cycling stability.

Effects of hydrazine on the solvothermal synthesis of Cu{sub 2}ZnSnSe{sub 4} and Cu{sub 2}CdSnSe{sub 4} nanocrystals for particle-based deposition of films

Energy Technology Data Exchange (ETDEWEB)

Chiang, Ming-Hung [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan 701 (China); Fu, Yaw-Shyan, E-mail: ysfu@mail.nutn.edu.tw [Department of Greenergy, National University of Tainan, Tainan, Taiwan 700 (China); Shih, Cheng-Hung; Kuo, Chun-Cheng [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan 701 (China); Guo, Tzung-Fang [Department of Photonics, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan 701 (China); Lin, Wen-Tai, E-mail: wtlin@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan 701 (China)

2013-10-01

The effects of hydrazine on the synthesis of Cu{sub 2}ZnSnSe{sub 4} (CZTSe) and Cu{sub 2}CdSnSe{sub 4} (CCTSe) nanocrystals in an autoclave as a function of temperature and time were explored. On heating at 190 °C for 24-72 h, pure CZTSe and CCTSe nanocrystals could readily grow in the hydrazine-added solution, while in the hydrazine-free solution the intermediate phases such as ZnSe, Cu{sub 2}Se, and Cu{sub 2}SnSe{sub 3}, and Cu{sub 2}SnSe{sub 3} and CdSe associated with the CZTSe and CCTSe nanocrystals grew, respectively. This result reveals that hydrazine can speed up the synthesis of pure CZTSe and CCTSe nanocrystals via a solvothermal process. The mechanisms for the hydrazine-enhanced growth of CZTSe and CCTSe nanocrystals were discussed. The pure CZTSe and CCTSe nanocrystals were subsequently fabricated to the smooth films by spin coating without further annealing in selenium atmosphere. This processing may be beneficial to the fabrication of the absorber layer for solar cells and thermoelectric devices. - Highlights: • Hydrazine enhances the growth of pure Cu{sub 2}ZnSnSe{sub 4} and Cu{sub 2}CdSnSe{sub 4} nanocrystals. • The nanocrystals can be fabricated to films by spin coating without annealing. • This solvothermal processing is promising for the fabrication of thin film devices.

Annealing-free synthesis of C-N co-doped TiO{sub 2} hierarchical spheres by using amine agents via microwave-assisted solvothermal method and their photocatalytic activities

Energy Technology Data Exchange (ETDEWEB)

Wu, Yu-Chun, E-mail: yuchunwu@mail.ncku.edu.tw; Ju, Lung-Shen

2014-08-01

Highlights: • The synthesis method for C-N co-doped TiO{sub 2} hierarchical spheres is proposed. • Microwave-assisted solvothermal method is applied. • C and N are doped into TiO{sub 2} via a direct chelating reaction of amine compounds. • The photodegradation rate is eightfold higher than the commercial P25 powders. - Abstract: The annealing-free synthesis of C-N co-doped TiO{sub 2} hierarchical spheres is proposed in this study. C and N were doped into the TiO{sub 2} structure via a direct chelating process to the Ti-precursor by using different amine agents, including hexadecylamine (HDA), diethylamine (DEA), trimethylamine (TMA), and diethylenetriamine (DETA). C-N co-doped TiO{sub 2} spheres (300 nm to 500 nm) composed of nanoparticles approximately 11 nm to 13 nm in size were obtained via an efficient microwave-assisted solvothermal reaction at 190 °C for 60 min. The effects of C and N doping by using different amine compounds on the bandgap energy and photocatalytic performance of TiO{sub 2} were investigated. Among the amine compounds, DETA provided the highest chelating efficiency because it provides two primary amine groups, which resulted in the highest C and N doping concentrations and the largest degree of bandgap narrowing (2.77 eV); nevertheless, the high chelating ratio of C and N restrained the crystallization of TiO{sub 2} and considerably decreased its photocatalytic activity. The use of TMA produced optimal C and N doping concentrations, which effectively reduced the bandgap of TiO{sub 2} to 2.85 eV without affecting its crystallization. Its photodecomposition activity to rhodamine B was eightfold of that of commercial Degussa P25 powders under visible light irradiation.

Facile and efficient one-pot solvothermal and microwave-assisted synthesis of stable colloidal solutions of MFe2O4 spinel magnetic nanoparticles

International Nuclear Information System (INIS)

Solano, Eduardo; Perez-Mirabet, Leonardo; Martinez-Julian, Fernando; Guzmán, Roger; Arbiol, Jordi; Puig, Teresa; Obradors, Xavier; Yañez, Ramón; Pomar, Alberto; Ricart, Susagna; Ros, Josep

2012-01-01

Well-defined synthesis conditions of high quality MFe 2 O 4 (M = Mn, Fe, Co, Ni, Zn, and Cu) spinel ferrite magnetic nanoparticles, with diameters below 10 nm, have been described based on facile and efficient one-pot solvothermal or microwave-assisted heating procedures. Both methods are reproducible and scalable and allow forming concentrated stable colloidal solutions in polar solvents, but microwave-assisted heating allows reducing 15 times the required annealing time and leads to an enhanced monodispersity of the nanoparticles. Non-agglomerated nanoparticles dispersions have been achieved using a simple one-pot approach where a single compound, triethyleneglycol, behaves at the same time as solvent and capping ligand. A narrow nanoparticle size distribution and high quality crystallinity have been achieved through selected nucleation and growth conditions. High resolution transmission electron microscopy images and electron energy loss spectroscopy analysis confirm the expected structure and composition and show that similar crystal faceting has been formed in both synthetic approaches. The spinel nanoparticles behave as ferrimagnets with a high saturation magnetization and are superparamagnetic at room temperature. The influence of synthesis route on phase purity and unconventional magnetic properties is discussed in some particular cases such as CuFe 2 O 4 , CoFe 2 O 4 , and ZnFe 2 O 4 .

Solvothermal tuning of photoluminescent graphene quantum dots: from preparation to photoluminescence mechanism

Science.gov (United States)

Qi, Bao-Ping; Zhang, Xiaoru; Shang, Bing-Bing; Xiang, Dongshan; Zhang, Shenghui

2018-02-01

Solvothermal synthesis was employed to tune the surface states of graphene quantum dots (GQDs). Two series of GQDs with the particle sizes from 2.6 to 4.5 nm were prepared as follows: (I) GQDs with the same size but different oxygen degrees; (II) GQDs with different core sizes but the similar surface chemistry. Both the large sizes and the high surface oxidation degrees led to the redshift photoluminescence (PL) of GQDs. Electrochemiluminescence (ECL) spectra from two series of GQDs were all in accordance with their PL spectra, respectively, which provided good evidence for the conjugated structures in GQDs responsible for PL. [Figure not available: see fulltext.

Structural and optical characterization of CdS nanorods synthesized by a PVA-assisted solvothermal method

International Nuclear Information System (INIS)

Wang Hongmei; Fang Pengfei; Chen Zhe; Wang Shaojie

2008-01-01

Cadmium sulphide (CdS) 1D nanocrystals were prepared using a simple poly(vinyl-alcohol) (PVA)-assisted solvothermal method which employed ethylenediamine (en) as solvent. The obtained nanorods were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-vis) absorption, and photoluminescence (PL) spectra. XRD results show that the nanorods are hexagonal phase. The TEM results indicate that the synthesized CdS nanorods with PVA-assisted showed larger aspect ratio and uniform faces compared with the sample prepared in the absence of PVA. The results of the photoluminescence and UV-vis spectroscopy measurements reveal that the as-prepared CdS nanorods show a quantum confinement effect. It is also found that the dosage of PVA is a vital factor in the morphology and optical properties of CdS nanorods. Moreover, when the best dosage of 3 g PVA/70 ml en was used, CdS nanorods with regular morphology and longer length were obtained. The probable mechanism for PVA-assisted solvothermal synthesis of CdS nanorods was also discussed

Indium telluride nanotubes: Solvothermal synthesis, growth mechanism, and properties

Energy Technology Data Exchange (ETDEWEB)

Zhou, Liyan [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yan, Shancheng, E-mail: yansc@njupt.edu.cn [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Lu, Tao; Shi, Yi; Wang, Jianyu [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yang, Fan [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China)

2014-03-15

A convenient solvothermal approach was applied for the first time to synthesize In{sub 2}Te{sub 3} nanotubes. The morphology of the resultant nanotubes was studied by scanning electron microscopy and transmission electron microscopy. Nanotubes with a relatively uniform diameter of around 500 nm, tube wall thickness of 50–100 nm, and average length of tens of microns were obtained. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to study the crystal structures, composition, and optical properties of the products. To understand the growth mechanism of the In{sub 2}Te{sub 3} nanotubes, we studied the influences of temperature, reaction time, and polyvinylpyrrolidone (PVP) and ethylene diamine (EDA) dosages on the final products. Based on the experimental results, a possible growth mechanism of In{sub 2}Te{sub 3} nanotubes was proposed. In this mechanism, TeO{sub 3}{sup −2} is first reduced to allow nucleation. Circumferential edges of these nucleated molecules attract further deposition, and nanotubes finally grow rapidly along the c-axis and relatively slowly along the circumferential direction. The surface area of the products was determined by BET and found to be 137.85 m{sup 2} g{sup −1}. This large surface area indicates that the nanotubes may be suitable for gas sensing and hydrogen storage applications. The nanotubes also showed broad light detection ranging from 300 nm to 1100 nm, which covers the UV–visible–NIR regions. Such excellent optical properties indicate that In{sub 2}Te{sub 3} nanotubes may enable significant advancements in new photodetection and photosensing applications. -- Graphical abstract: A convenient solvothermal approach was applied to synthesize In{sub 2}Te{sub 3} nanotubes, which has not been reported in the literature for our knowledge. Surface area of this material is 137.85 m{sup 2} g{sup −1} from the BET testing, and such a high value makes it probably suitable for gas sensing and

Enhanced photocatalytic CO₂-reduction activity of electrospun mesoporous TiO₂ nanofibers by solvothermal treatment.

Science.gov (United States)

Fu, Junwei; Cao, Shaowen; Yu, Jiaguo; Low, Jingxiang; Lei, Yongpeng

2014-06-28

Photocatalytic reduction of CO2 into renewable hydrocarbon fuels using semiconductor photocatalysts is considered as a potential solution to the energy deficiency and greenhouse effect. In this work, mesoporous TiO2 nanofibers with high specific surface areas and abundant surface hydroxyl groups are prepared using an electrospinning strategy combined with a subsequent calcination process, followed by a solvothermal treatment. The solvothermally treated mesoporous TiO2 nanofibers exhibit excellent photocatalytic performance on CO2 reduction into hydrocarbon fuels. The significantly improved photocatalytic activity can be attributed to the enhanced CO2 adsorption capacity and the improved charge separation after solvothermal treatment. The highest activity is achieved for the sample with a 2-h solvothermal treatment, showing 6- and 25-fold higher CH4 production rate than those of TiO2 nanofibers without solvothermal treatment and P25, respectively. This work may also provide a prototype for studying the effect of solvothermal treatment on the structure and photocatalytic activity of semiconductor photocatalysts.

Facile Synthesis of Long, Straight and Uniform Copper Nanowires via a Solvothermal Method

Institute of Scientific and Technical Information of China (English)

Chunfu Lin; Hong Lin; Ning Wang; Xing Zhang; Jun Yang; Jianbo Li; Xiaozhan Yang

2006-01-01

Copper nanowires were facilely prepared via a solvothermal method. In this method, cetyltrimethylammonium bromide (CTAB) was used as a soft template, copper nitrate was an inorganic precursor, and absolute ethanol served as a reducing agent as well as a solvent. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the as-prepared copper nanowires. The as-prepared copper nanowires are fairly uniform and long. The majority of them are longer than 100 μm and some even longer than 200 μm. Furthermore, most nanowires are quite straight. In addition,The mechanism of the growth process of copper nanowires was discussed.

Morphological evolution of Bi2Se3 nanocrystalline materials synthesized by microwave assisted solvothermal method

Science.gov (United States)

Bera, Sumit; Behera, P.; Mishra, A. K.; Krishnan, M.; Patidar, M. M.; Singh, D.; Gangrade, M.; Venkatesh, R.; Deshpande, U. P.; Phase, D. M.; Ganesan, V.

2018-04-01

Structural, morphological and spectroscopic properties of Bi2Se3 nanoparticles synthesized by microwave assisted solvothermal method were investigated systematically. A controlled synthesis of different morphologies by a small variation in synthesis procedure is demonstrated. Powder X-ray diffraction (XRD) confirmed the formation of single phase. Crystallite and particle size reductions were studied with XRD and AFM (Atomic Force Microscopy). Different morphologies such as hexagonal nanoflakes with cross section of around˜6µm, nanoflower and octahedral agglomerated crystals of nearly ˜60 nm size have been observed in scanning electron microscope while varying the microwave assisted synthesis procedures. A significant blue shift observed in diffuse reflectance spectroscopy evidences the energy gap tuning as a result of morphological evolution. The difference in morphology observed in this three fast, facile and scalable synthesis is advantageous for tuning the thermoelectric figure of merit and for probing the surface states of these topological insulators. Low temperature resistivity remains similar for all three variants depicting a 2D character as evidenced by a -lnT term of localization.

Solvothermal synthesis and high optical performance of three-dimensional sea-urchin-like TiO2

International Nuclear Information System (INIS)

Zhou, Yi; Wang, Yutang; Li, Mengyao; Li, Xuzhi; Yi, Qin; Deng, Pan; Wu, Hongyan

2015-01-01

Graphical abstract: I–V characteristics of different TiO 2 microspheres based DSSCs (a) 3D sphere-like, (b) 3D flower-like, (c) 3D sea-urchin-like. - Highlights: • 3D sea-urchin-like TiO 2 was synthesized by solvothermal method. • The effects of preparation parameters on the microstructure of the microspheres were investigated. • The photoelectric properties of 3D sea-urchin-like TiO 2 were studied upon DSSCs. • The PCE of the 3D sea-urchin-like TiO 2 was higher than that of other morphologies. - Abstract: Three-dimensional (3D) sea-urchin-like TiO 2 microspheres were successfully synthesised by solvothermal method. The effects of preparation parameters including reaction temperature, concentration and mass fraction of precursor, and solvent volume on the microstructure of the microspheres were investigated. Results of scanning electron microscopy showed that the preparation parameters played a critical role in the morphology of 3D sea-urchin-like TiO 2 . In addition, when the sea-urchin-like TiO 2 nanostructures were used as the dye-sensitized solar cells (DSSCs) anode, the power-conversion efficiency was higher than that of other morphologies, which was due to the special 3D hierarchical nanostructure, large specific surface area, and enhanced absorption of UV–vis of the TiO 2 nanostructures

Facile solvothermal synthesis of highly active and robust Pd1.87Cu0.11Sn electrocatalyst towards direct ethanol fuel cell applications

Science.gov (United States)

Jana, Rajkumar; Dhiman, Shikha; Peter, Sebastian C.

2016-08-01

Ordered intermetallic Pd1.87Cu0.11Sn ternary electrocatalyst has been synthesized by sodium borohydride reduction of precursor salts Pd(acac)2, CuCl2.2H2O and SnCl2 using one-pot solvothermal synthesis method at 220 °C with a reaction time of 24 h. To the best of our knowledge, here for the first time we report surfactant free synthesis of a novel ordered intermetallic ternary Pd1.87Cu0.11Sn nanoparticles. The ordered structure of the catalyst has been confirmed by powder x-ray diffraction, transmission electron microscopy (TEM). Composition and morphology of the nanoparticles have been confirmed through field emission scanning electron microscopy, energy-dispersive spectrometry and TEM. The electrocatalytic activity and stability of the ternary electrocatalyst towards ethanol oxidation in alkaline medium was investigated by cyclic voltammetry and chronoamperometry techniques. The catalyst is proved to be highly efficient and stable upto 500th cycle and even better than commercially available Pd/C (20 wt%) electrocatalysts. The specific and mass activity of the as synthesized ternary catalyst are found to be ∼4.76 and ∼2.9 times better than that of commercial Pd/C. The enhanced activity and stability of the ordered ternary Pd1.87Cu0.11Sn catalyst can make it as a promising candidate for the alkaline direct ethanol fuel cell application.

Mixed-solvothermal synthesis of CdS micro/nanostructures and their optical properties

International Nuclear Information System (INIS)

Zhong Shengliang; Zhang Linfei; Huang Zhenzhong; Wang Shangping

2011-01-01

Several novel cadmium sulfide (CdS) micro/nanostructures, including cauliflower-like microspheres, football-like microspheres, tower-like microrods, and dendrites were controllably prepared via an oxalic acid-assisted solvothermal route using ethylene glycol (EG) and H 2 O as pure and mixed solvents with different S sources. The as-prepared products were characterized by X-ray powder diffraction (XRD), scanning electronic microscope (SEM) and UV-vis spectrophotometer (UV). It was found that CdS micro/nanostructures can be selectively obtained by varying the composition of solvent, concentration of oxalic acid, and sulfur sources. UV-vis absorption spectra reveal that their absorption properties are shape-dependent. The possible formation process of the CdS micro/nanostructures was briefly discussed. This route provides a facile way to tune the morphologies of CdS over a wide range.

One-pot solvothermal synthesis of highly efficient, daylight active and recyclable Ag/AgBr coupled photocatalysts with synergistic dual photoexcitation

International Nuclear Information System (INIS)

Zhang, Caihong; Ai, Lunhong; Li, Lili; Jiang, Jing

2014-01-01

Highlights: • Ag/AgBr photocatalysts were controllably synthesized by solvothermal process. • Ag/AgBr composites showed excellent daylight driven photocatalytic activity. • The remarkable activity is attributed to the synergistic dual photoexcitation. -- Abstract: Efficient light harvesting has been considered to be critical for manipulating the photocatalytic behavior of photocatalysts, because it directly determines the generation of reactive redox charge carriers involved in photoreaction process. In this study, we present a successful example on efficient conversion of solar energy by Ag/AgBr coupled photocatalysts that hold unique synergistic dual photoexcitation. A series of Ag/AgBr coupled photocatalysts were controllably synthesized by an easily manipulated mild solvothermal process. The physicochemical properties of the as-prepared Ag/AgBr coupled photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and UV–vis diffuse reflectance spectroscopy (DRS). The results showed the solvothermal reaction time played key role for control of crystalline structure, morphology, composition, and visible light absorption ability of the resulting photocatalysts. The as-prepared Ag/AgBr coupled photocatalysts exhibited remarkable photocatalytic performance and good reusability for decomposing organic dyes in aqueous solution under the irradiation of commercial 20 W cool daylight fluorescent lamp, owing to the synergistic dual photoexcitation cooperating between plasmonic Ag nanoparticles and narrow-band-gap AgBr

Mixed-solvothermal synthesis of CdS micro/nanostructures and their optical properties

Energy Technology Data Exchange (ETDEWEB)

Zhong Shengliang, E-mail: zslxhx@yahoo.com.cn [College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022 (China); Zhang Linfei; Huang Zhenzhong; Wang Shangping [College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022 (China)

2011-01-15

Several novel cadmium sulfide (CdS) micro/nanostructures, including cauliflower-like microspheres, football-like microspheres, tower-like microrods, and dendrites were controllably prepared via an oxalic acid-assisted solvothermal route using ethylene glycol (EG) and H{sub 2}O as pure and mixed solvents with different S sources. The as-prepared products were characterized by X-ray powder diffraction (XRD), scanning electronic microscope (SEM) and UV-vis spectrophotometer (UV). It was found that CdS micro/nanostructures can be selectively obtained by varying the composition of solvent, concentration of oxalic acid, and sulfur sources. UV-vis absorption spectra reveal that their absorption properties are shape-dependent. The possible formation process of the CdS micro/nanostructures was briefly discussed. This route provides a facile way to tune the morphologies of CdS over a wide range.

Iron (III) oxyhydroxide in isopropyl alcohol preparation, characterization and solvothermal treatment

International Nuclear Information System (INIS)

Carvalho, E.L.C.N.; Jafelicci Junior, M.

1989-01-01

Iron (III) nitrate hydrolysis was carried out in isopropyl alcohol solution by an aqueous amonia gas stream resulting in iron (III) oxyhydroxide sol. It has been investigated in this work the solvothermal treatment of this colloidal system at 120 0 C and 24 hours. Iron (III) oxyhydroxide freshly obtained and solvothermally treated. Samples were dryed by lyophilization. Products obtained were characterized by the following techniques: spectrophotometric iron analysis by 1,10-orthophenantroline complexation method, powder X-ray diffraction, vibrational infrared spectra and differential thermal analysis. After solvothermal treatment resulting product was crystallized into hematite, while freshly iron (III) oxyhydroxide was non crystalline. Both of them are very active powder, showing high water adsorption [pt

Solvothermal synthesis of 3D photonic crystals based on ZnS/opal system

Energy Technology Data Exchange (ETDEWEB)

Chang Xin [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Cao Jieming [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)]. E-mail: jmcao@nuaa.edu.cn; Ji Hongmei [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Fang Baoqing [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Feng Jie [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Pan Lijia [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhang Fang [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Haiyan [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2005-01-15

We made photonic crystals composed of artificial opals infiltrated with ZnS semiconductor nanocrystals by using self-assembly and solvothermal methods. SEM images show that the silica spheres exhibit a well-ordered arrangement and the ZnS nanocrystals infiltrate within the opal templates by heterogeneous nucleation and growth processing, and the as-synthesized ZnS nanocrystals reveal a cubic phase from X-ray diffraction pattern. Furthermore, the optical properties of the infiltrated opals with different ZnS filling ratio are also studied by transmission spectroscopy, respectively. It is proposed that the position of the stop band can be easily designed by controlling the infiltration ratio of ZnS. These results demonstrate an easy-to-handle and efficient route to obtain high performance photonic crystal structures.

Solvothermal synthesis of 3D photonic crystals based on ZnS/opal system

International Nuclear Information System (INIS)

Chang Xin; Cao Jieming; Ji Hongmei; Fang Baoqing; Feng Jie; Pan Lijia; Zhang Fang; Wang, Haiyan

2005-01-01

We made photonic crystals composed of artificial opals infiltrated with ZnS semiconductor nanocrystals by using self-assembly and solvothermal methods. SEM images show that the silica spheres exhibit a well-ordered arrangement and the ZnS nanocrystals infiltrate within the opal templates by heterogeneous nucleation and growth processing, and the as-synthesized ZnS nanocrystals reveal a cubic phase from X-ray diffraction pattern. Furthermore, the optical properties of the infiltrated opals with different ZnS filling ratio are also studied by transmission spectroscopy, respectively. It is proposed that the position of the stop band can be easily designed by controlling the infiltration ratio of ZnS. These results demonstrate an easy-to-handle and efficient route to obtain high performance photonic crystal structures

Solvothermal synthesis and high optical performance of three-dimensional sea-urchin-like TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yi, E-mail: zhouyihn@163.com; Wang, Yutang; Li, Mengyao; Li, Xuzhi; Yi, Qin; Deng, Pan; Wu, Hongyan

2015-06-15

Graphical abstract: I–V characteristics of different TiO{sub 2} microspheres based DSSCs (a) 3D sphere-like, (b) 3D flower-like, (c) 3D sea-urchin-like. - Highlights: • 3D sea-urchin-like TiO{sub 2} was synthesized by solvothermal method. • The effects of preparation parameters on the microstructure of the microspheres were investigated. • The photoelectric properties of 3D sea-urchin-like TiO{sub 2} were studied upon DSSCs. • The PCE of the 3D sea-urchin-like TiO{sub 2} was higher than that of other morphologies. - Abstract: Three-dimensional (3D) sea-urchin-like TiO{sub 2} microspheres were successfully synthesised by solvothermal method. The effects of preparation parameters including reaction temperature, concentration and mass fraction of precursor, and solvent volume on the microstructure of the microspheres were investigated. Results of scanning electron microscopy showed that the preparation parameters played a critical role in the morphology of 3D sea-urchin-like TiO{sub 2}. In addition, when the sea-urchin-like TiO{sub 2} nanostructures were used as the dye-sensitized solar cells (DSSCs) anode, the power-conversion efficiency was higher than that of other morphologies, which was due to the special 3D hierarchical nanostructure, large specific surface area, and enhanced absorption of UV–vis of the TiO{sub 2} nanostructures.

Solvothermal synthesis and electrical conductivity model for the zinc oxide-insulated oil nanofluid

International Nuclear Information System (INIS)

Shen, L.P.; Wang, H.; Dong, M.; Ma, Z.C.; Wang, H.B.

2012-01-01

A new kind of nanofluid, ZnO-insulated oil nanofluid was prepared from ZnO nanoparticles synthesized by solvothermal method. Electrical property measurement shows that the electrical conductivity increases by 973 times after adding 0.75% volumetric fraction of ZnO nanoparticles into the insulated oil. A linear dependence of the electrical conductivity on the volumetric fraction has been observed, while the temperature dependence of the electrical conductivity reveals a nonlinear relationship. An electrical conductivity model is established for the nanofluid by considering both the Brownian motion and electrophoresis of the ZnO nanoparticles. -- Highlights: ► Stable ZnO-insulated oil nanofluid was successfully prepared. ► The electrical conductivity of the ZnO nanofluid is investigated. ► A new model is established to explain the electrical properties of the nanofluid.

Phase controlled solvothermal synthesis of Cu{sub 2}ZnSnS{sub 4}, Cu{sub 2}ZnSn(S,Se){sub 4} and Cu{sub 2}ZnSnSe{sub 4} Nanocrystals: The effect of Se and S sources on phase purity

Energy Technology Data Exchange (ETDEWEB)

Pal, Mou [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, 62580 Temixco, Morelos (Mexico); Instituto de Física, BUAP, Av. San Claudio y Blvd. 18 Sur Col. San Manuel, Ciudad Universitaria, C.P. 72570, Puebla (Mexico); Mathews, N.R. [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, 62580 Temixco, Morelos (Mexico); Paraguay-Delgado, F. [Departamento de Materiales Nanoestructurados, Centro de Investigación en Materiales Avanzados (CIMAV), Chihuahua (Mexico); Mathew, X., E-mail: xm@ier.unam.mx [Instituto de Energías Renovables, Universidad Nacional Autónoma de México, 62580 Temixco, Morelos (Mexico)

2015-09-15

In this study, we have reported the synthesis of Cu{sub 2}ZnSnSe{sub 4} (CZTSe), Cu{sub 2}ZnSnS{sub 4} (CZTS) and Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) nanocrystals with tunable band gap and composition obtained by solvothermal method. The crystalline structure, composition, morphology and optical properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman scattering, energy dispersive X-ray spectroscopy, transmission electron microscopy and diffuse reflectance (DR) spectroscopy. While the XRD patterns of CZTS and CZTSe nanoparticles prepared with elemental S/Se powder revealed the presence of phase pure nanoparticles, the CZTSSe nanoparticles obtained using a mixture of S and Se, were found to contain many secondary phases under the same synthesis protocol. Formation of impurity phases in CZTSSe sample, can be avoided by using a mixture of 1-dodecanethiol (DT; CH{sub 3}(CH{sub 2}){sub 11}SH)/oleylamine (OLA) instead of S powder and following the same experimental procedure. The incorporation of S in CZTSe nanocrystals prepared in presence of DDT/OLA mixture was confirmed through structural and optical characterizations. The optical properties of the quaternary chalcogenide nanocrystals were found to vary with the chemical composition of the material. - Highlights: • Solvothermal synthesis of CZTS, CZTSSe and CZTSe nanocrystals and discussion on possible formation mechanism. • Use of dodecanethiol/oleylamine mixture to synthesize phase-pure CZTSSe nanocrystals. • Formation of impurity phases can be controlled with proper S and Se sources.

Solvothermal synthesis of graphene-Sb2S3 composite and the degradation activity under visible light

International Nuclear Information System (INIS)

Tao, Wenguang; Chang, Jiuli; Wu, Dapeng; Gao, Zhiyong; Duan, Xiaoli; Xu, Fang; Jiang, Kai

2013-01-01

Graphical abstract: Display Omitted Highlights: ► Graphene-Sb 2 S 3 composites were synthesized through a facile solvothermal method. ► Hydroxyl radicals are the main species responsible for the photodegradation activity. ► Graphene-Sb 2 S 3 demonstrated dramatically improved visible light degradation activity. -- Abstract: Novel graphene-Sb 2 S 3 (G-Sb 2 S 3 ) composites were synthesized via a facile solvothermal method with graphene oxide (GO), SbCl 3 and thiourea as the reactants. GO played an important role in controlling the size and the distribution of the formed Sb 2 S 3 nanoparticles on the graphene sheets with different density. Due to the negative surface charge, smaller Sb 2 S 3 particles size and efficient electrons transfer from Sb 2 S 3 to graphene, the composites demonstrated improved photodegradation activity on rhodamine B (RhB). Among these composites, the product G-Sb 2 S 3 0.1, which was synthesized with the GO concentration of 0.1 mg/mL, exhibited the highest photodegradation activity owing to the considerable density of Sb 2 S 3 nanoparticles onto graphene sheet free of aggregation. Hydroxyl radicals (·OH) derived from conduction band (CB) electrons of Sb 2 S 3 is suggested to be responsible for the photodegradation of RhB. The high visible light degradation activity and the satisfactory cycling stability made the as-prepared G-Sb 2 S 3 0.1 an applicable photocatalyst.

Solvothermal synthesis of uranium(VI) phases with aromatic carboxylate ligands: A dinuclear complex with 4-hydroxybenzoic acid and a 3D framework with terephthalic acid

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yingjie, E-mail: yzx@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Karatchevtseva, Inna [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Bhadbhade, Mohan [Mark Wainwright Analytical Centre, University of New South Wales, Kensington, NSW 2052 (Australia); Tran, Toan Trong; Aharonovich, Igor [School of Physics and Advanced Materials, University of Technology Sydney, Ultimo, NSW 2007 (Australia); Fanna, Daniel J.; Shepherd, Nicholas D. [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lu, Kim [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Li, Feng [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lumpkin, Gregory R. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

2016-02-15

With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H{sub 2}phb) or terephthalic acid (H{sub 2}tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO{sub 2}){sub 2}(Hphb){sub 2}(phb)(DMF)(H{sub 2}O){sub 3}]·4H{sub 2}O (1) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ{sub 2}-bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO{sub 2})(tph)(DMF)] (2) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ{sub 4}-terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1, and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been investigated. - Graphical abstract: With the coordination of dimethylformamide, two new uranyl complexes with either 4-hydroxybenzoate or terephthalate have been synthesized under solvothermal conditions and structurally characterized. - Highlights: • Solvent facilitates the synthesis of two new uranium(VI) complexes. • A dinuclear complex with both penta- and hexagonal bipyramidal uranium polyhedral. • A unique µ{sub 2}-bridging mode of 4-hydroxybenzoate via alcohol oxygen for 5 f ions. • A 3D framework with uranium polyhedra and µ{sub 4}-terephthalate ligands. • Vibration modes and photoluminescence properties are reported.

Solvothermal synthesis of Zinc sulfide decorated Graphene (ZnS/G) nanocomposites for novel Supercapacitor electrodes

International Nuclear Information System (INIS)

Ramachandran, Rajendran; Saranya, Murugan; Kollu, Pratap; Raghupathy, Bala P.C.; Jeong, Soon Kwan; Grace, Andrews Nirmala

2015-01-01

Highlights: • ZnS/G nanocomposites were prepared by a simple solvothermal process. • Electrochemical measurements were carried out in 6 M KOH electrolyte. • Cyclic voltammetry showed the excellent capacitive behavior of the composites. • A specific capacitance of 197.1 F/g was observed for ZnS/G-60 nanocomposites. - Abstract: Zinc sulfide decorated graphene nanocomposites are synthesized by a facile solvothermal approach and the prepared composites are analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High Resolution Transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), Ultraviolet visible spectroscopy (UV), Photoluminescence spectroscopy (PL) and Raman spectrum. Results show the effective reduction of graphene oxide (GO) to graphene and decoration of ZnS nanoparticles on graphene sheets. Towards supercapacitor applications, the electrochemical measurements of different electrodes are performed in 6 M KOH electrolyte. A series of composites with different loadings of graphene is synthesized and tested for its electrochemical properties. The specific capacitance of the electrodes are evaluated from cyclic voltammetry (CV) studies and a maximum specific capacitance of 197.1 F/g is achieved in ZnS/G-60 electrode (60 indicates the weight ratio of GO) at scan rate of 5 mV s"−"1. A capacitance retention of about 94.1% is observed even after 1000 cycles for ZnS/G-60 electrode, suggesting the long time cyclic stability of the composite electrode. Galvanostatic charge–discharge curves show the highly reversible process of ZnS/G-60 electrode. Electrochemical Impedance Spectrum (EIS) shows a high conductivity of composite electrode suggesting that the composites are good candidates for energy storage.

One-pot solvothermal synthesis of highly water-dispersible size-tunable functionalized magnetite nanocrystal clusters for lipase immobilization.

Science.gov (United States)

Zhu, Hao; Hou, Chen; Li, Yijing; Zhao, Guanghui; Liu, Xiao; Hou, Ke; Li, Yanfeng

2013-07-01

A facile one-pot synthesis of highly water-dispersible size-tunable magnetite (Fe3O4) nanocrystal clusters (MNCs) end-functionalized with amino or carboxyl groups by a modified solvothermal reduction reaction has been developed. Dopamine and 3,4-dihydroxyhydroxycinnamic acid were used for the first time as both a surfactant and interparticle linker in a polylol process for economical and environment-friendly purposes. Morphology, chemical composition, and magnetic properties of the prepared particles were investigated by several methods, including FESEM, TEM, XRD, XPS, Raman, FTIR, TGA, zeta potential, and VSM. The sizes of the particles could be easily tuned over a wide range from 175 to 500 nm by varying the surfactant concentration. Moreover, ethylene glycol/diethylene glycol (EG/DEG) solvent mixtures with different ratios could be used as reductants to obtain the particles with smaller sizes. The XRD data demonstrated that the surfactants restrained the crystal growth of the grains. The nanoparticles showed superior magnetic properties and high colloidal stability in water. The cytotoxicity results indicated the feasibility of using the synthesized nanocrystals in biology-related fields. To estimate the applicability of the obtained MNCs in biotechnology, Candida rugosa lipase was selected for the enzyme immobilization process. The immobilized lipase exhibited excellent thermal stability and reusability in comparison with the free enzyme. This novel strategy would simplify the reaction protocol and improve the efficiency of materials functionalization, thus offering new potential applications in biotechnology and organocatalysis. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and Morphological Tuning of LiCoPO4 Materials Synthesized by Solvo-Thermal Methods for Li-Cell Applications

Directory of Open Access Journals (Sweden)

Jessica Manzi

2015-12-01

Full Text Available Olivine-type lithium metal phosphates (LiMPO4 are promising cathode materials for lithium-ion batteries. LiFePO4 (LFP is commonly used in commercial Li-ion cells but the Fe3+/Fe2+ couple can be usefully substituted with Mn3+/Mn2+, Co3+/Co2+, or Ni3+/Ni2+, in order to obtain higher redox potentials. In this communication we report a systematic analysis of the synthesis condition of LiCoPO4 (LCP using a solvo-thermal route at low temperature, the latter being a valuable candidate to overcome the theoretical performances of LFP. In fact, LCP shows higher working potential (4.8 V vs. 3.6 V compared to LFP and similar theoretical capacity (167 mAh·g−1. Our goal is to show the effect of the synthesis condition of the ability of LCP to reversibly cycle lithium in electrochemical cells. LCP samples have been prepared through a solvo-thermal method in aqueous-non aqueous solvent blends. Different Co2+ salts have been used to study the effect of the anion on the crystal growth as well as the effect of solution acidity, temperature and reaction time. Materials properties have been characterized by Fast-Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopies. The correlation between structure/morphology and electrochemical performances has been investigated by galvanostatic charge-discharge cycles.

Solvothermal Synthesis of One-Dimensional Transition Metal Doped ZnO Nanocrystals and Their Applications in Smart Window Devices

OpenAIRE

Šutka, A; Timusk, M; Kisand, V; Saal, K; Joost, U; Lõhmus, R

2015-01-01

Oxide semiconductor nanowire (NW) suspension based devices have been attracted growing interest in smart window applications due to their great controllability of light transmittance, simplicity and long term stability. Recently, we demonstrated smart window device using the suspension of electrospun TiO2 or solvothermally synthesized ZnO NWs in viscous polydimethylsiloxane (PDMS) matrix. The operating principle of the oxide semiconductor NW and PDMS device is based on the alterable orientati...

Surfactant-free solvothermal synthesis of Hydroxyapatite nested bundles for the effective photodegradation of cationic dyes

Science.gov (United States)

Reeta Mary, I.; Sonia, S.; Navadeepthy, D.; Mangalaraj, D.; Viswanathan, C.; Ponpandian, N.

2018-05-01

In this study, hydroxyapatite nested bundles (HNBs) were successfully constructed from nanosticks as nanoscale building blocks via a facile, solvothermal process without using any surfactant. The fabricated HNBs were structurally analyzed using X-ray diffraction and Fourier transform infrared spectroscopy, which confirmed the purity of the HNBs. The surface characteristics were determined by field emission scanning electron microscopy and Brunauer-Emmett-Teller analysis, and the optical characteristics by ultraviolet (UV)-visible spectroscopy. The synthesized HNBs were tested to determine their activity during the degradation of methylene blue, methylene violet, and rhodamine B via photocatalysis under UV irradiation. The degradation efficiency of HNBs and the rate of degradation can be explained based on the properties of the HNBs and cationic dyes.

Solvothermal preparation and fluorescent properties of color-tunable InP/ZnS quantum dots

Energy Technology Data Exchange (ETDEWEB)

Lee, Ju Chul; Jang, Eun-Pyo [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of); Jang, Dong Seon; Choi, Yoonyoung; Choi, Moongoo [Materials and Devices Laboratory, LGE Advanced Research Institute, LG Electronics, Seoul 137-724 (Korea, Republic of); Yang, Heesun, E-mail: hyang@hongik.ac.kr [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of)

2013-02-15

This work reports on the solvothermal preparation and optical properties of InP core and InP/ZnS core/shell quantum dots (QDs). InP QDs are synthesized using a phosphorus (P) source of tris(dimethylamino)phosphine (P(N(CH{sub 3}){sub 2}){sub 3}) under the solvothermal conditions in the range of reaction temperature of 120-180 Degree-Sign C and reaction time of 12 h-1 week to tune their size. ZnS shelling is also solvothermally performed by varying the shell growth temperature from 180 to 220 Degree-Sign C for 6 h, and then respective InP and InP/ZnS QDs are subjected to the size-sorting procedure. Effects of the shelling temperature on the fluorescent attributes (emission peak wavelength, bandwidth, and quantum yield) of the resulting size-sorted InP/ZnS QD fractions are investigated. The qualitative information on the shell thickness as a function of shelling temperature is furthermore provided by x-ray diffraction and x-ray photoelectron spectroscopy. - Highlights: Black-Right-Pointing-Pointer InP/ZnS core/shell QDs are prepared using a P source of P(N(CH{sub 3}){sub 2}){sub 3} by a stepwise solvothermal approach. Black-Right-Pointing-Pointer Widely emission-tuable InP/ZnS QDs are realized by varying the solvothermal condition for core QD growth. Black-Right-Pointing-Pointer Effects of ZnS shelling temperature on fluorescent properties of InP/ZnS QDs are investigated.

Solvothermal preparation and fluorescent properties of color-tunable InP/ZnS quantum dots

International Nuclear Information System (INIS)

Lee, Ju Chul; Jang, Eun-Pyo; Jang, Dong Seon; Choi, Yoonyoung; Choi, Moongoo; Yang, Heesun

2013-01-01

This work reports on the solvothermal preparation and optical properties of InP core and InP/ZnS core/shell quantum dots (QDs). InP QDs are synthesized using a phosphorus (P) source of tris(dimethylamino)phosphine (P(N(CH 3 ) 2 ) 3 ) under the solvothermal conditions in the range of reaction temperature of 120–180 °C and reaction time of 12 h−1 week to tune their size. ZnS shelling is also solvothermally performed by varying the shell growth temperature from 180 to 220 °C for 6 h, and then respective InP and InP/ZnS QDs are subjected to the size-sorting procedure. Effects of the shelling temperature on the fluorescent attributes (emission peak wavelength, bandwidth, and quantum yield) of the resulting size-sorted InP/ZnS QD fractions are investigated. The qualitative information on the shell thickness as a function of shelling temperature is furthermore provided by x-ray diffraction and x-ray photoelectron spectroscopy. - Highlights: ► InP/ZnS core/shell QDs are prepared using a P source of P(N(CH 3 ) 2 ) 3 by a stepwise solvothermal approach. ► Widely emission-tuable InP/ZnS QDs are realized by varying the solvothermal condition for core QD growth. ► Effects of ZnS shelling temperature on fluorescent properties of InP/ZnS QDs are investigated.

Solvothermal indium fluoride chemistry: Syntheses and crystal structures of K5In3F14, β-(NH4)3InF6 and [NH4]3[C6H21N4]2[In4F21

International Nuclear Information System (INIS)

Jayasundera, Anil C.A.; Goff, Richard J.; Li Yang; Finch, Adrian A.; Lightfoot, Philip

2010-01-01

The solvothermal syntheses and crystal structures of three indium fluorides are presented. K 5 In 3 F 14 (1) and β-(NH 4 ) 3 InF 6 (2) are variants on known inorganic structure types chiolite and cryolite, respectively, with the latter exhibiting a complex and apparently novel structural distortion. [NH 4 ] 3 [C 6 H 21 N 4 ] 2 [In 4 F 21 ] (3) represents a new hybrid composition displaying a unique trimeric metal fluoride building unit. - Graphical abstract: Solvothermal synthesis has been used to prepare three indium fluorides, including a novel hybrid material containing a unique [In 3 F 15 ] trimer templated by tren.

Synthesis of nano γ-alumina by the solvothermal technique

International Nuclear Information System (INIS)

Meor Yusoff Meor Sulaiman; Masliana Muslimin

2006-01-01

The paper describes work done on synthesis of γ-alumina by using the solvo thermal technique. Synthesis of γ-alumina involves the transition reactions of the aluminium hydroxide into alumina by a dehydroxylation process. As there are many forms of transition aluminas produced during this process, a x-ray diffraction (XRD) technique was used to identify γ-alumina and the other forms of alumina. After establishing the optimum conditions for the production of a single-phase γ-alumina, characteristic study on the product was performed. An important parameter in establishing nanosized powders is their crystallite size and analysis of the γ-alumina shows that it is a nanosized powder with a size of 28 nm. Other properties analysed include morphology, surface area and particle size. (Author)

Solvothermal Synthesis of Fe2O3 Loaded Activated Carbon as Electrode Materials for High-performance Electrochemical Capacitors

International Nuclear Information System (INIS)

Li, Ying; Kang, Litao; Bai, Gailing; Li, Peiyang; Deng, Jiachun; Liu, Xuguang; Yang, Yongzhen; Gao, Feng; Liang, Wei

2014-01-01

This article describes a facile solvothermal synthesis method to prepare Fe 2 O 3 /AC composites for electrochemical capacitors from Iron (III) chloride hexahydrate (FeCl 3 ·6H 2 O), activated carbon (AC, from petroleum coke), and four different precipitants (i.e., NaOH, CH 3 COONa, HMT, CO(NH 2 ) 2 ). X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Thermogravimetric (TG) analysis show that the products consisted of nanosized α-Fe 2 O 3 (weight ratios: 48.1, 47.9, 44.2, 44.3%) loaded onto AC particles (∼ 20 μm). Significantly, both kind and dosage of precipitants exhibit effects on the specific capacitances of Fe 2 O 3 /AC composites. The highest specific capacitance reaches up to 240 F g −1 (at a current density of 1 A g −1 in 6 M KOH aqueous electrolyte) when the molar ratio of CH 3 COONa: FeCl 3 is 9. On the other hand, the sample prepared with NaOH: FeCl 3 molar ratio being 1.5 exhibits excellent rate capability with specific capacitance of 215 F g −1 at 1 A g −1 , and 89.3, 82.3, 78.1, 72.6 and 65.1% capacity retention at 2, 5, 10, 20, and 40 A g −1 , respectively. These electrochemical performances are superior to other materials consisted of Fe 2 O 3 /carbon nanotube (CNT), graphene oxide (GO) or reduced graphene oxide (rGO) composites, demonstrating the great potential of Fe 2 O 3 /AC composites in the development of high-performance electrode materials for electrochemical capacitors

Solvothermal synthesis of tetravalent uranium with isophthalate or pyromellitate ligands

Energy Technology Data Exchange (ETDEWEB)

Falaise, Clement; Delille, Jason; Volkringer, Christophe; Loiseau, Thierry [Contribution from Unite de Catalyse et Chimie du Solide (UCCS) - UMR CNRS 8181, Universite de Lille, USTL-ENSCL, Villeneuve d' Ascq (France)

2015-06-15

Three new coordination polymers bearing tetravalent uranium have been isolated with the O-donor ligands such as isophthalate (1,3-bdc) or pyromellitate (btec). The compounds 1 and 3 have been solvothermally synthesized in N,N-dimethylformamide (DMF). The crystal structure of U(1,3-bdc){sub 2}(DMF) (1) is built up from discrete tricapped trigonal-primastic UO{sub 9} units, for which one carbonyl oxygen atom from DMF is bound to uranium. The connection of the UO{sub 9} units with the isophthalate linkers occurs in a chelating and bidentate fashion and gives rise to the formation of a 3D framework, delimiting narrow channels running along the [101] direction. Upon heating, the DMF molecules are removed, generating the second phase U(1,3-bdc){sub 2} (2) compound, closely related to 1. Indeed, the coordination environment of uranium is reduced to eight with a distorted square-antiprismatic geometry. This transition induces the relative shrinkage of the network (ΔV = 23 %). The structure of the compound U(btec)(DMF){sub 2} (3) also exhibits a 3D framework composed of an isolated bicapped square-antiprismatic UO{sub 10} unit, for which two carbonyl oxygen atoms from DMF are bonded to uranium. Pyromellitate ensures the connection of the UO{sub 10} units through the carboxylate arms in a chelating mode. This results in the formation of a network with diamond-shaped channels, developed along the c axis and encapsulating the DMF molecules. In contrast to 1, no stable phase is observed upon removing the DMF species by heating. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

One-pot solvothermal synthesis of three-dimensional (3D) BiOI/BiOCl composites with enhanced visible-light photocatalytic activities for the degradation of bisphenol-A

International Nuclear Information System (INIS)

Xiao, Xin; Hao, Rong; Liang, Min; Zuo, Xiaoxi; Nan, Junmin; Li, Laisheng; Zhang, Weide

2012-01-01

Highlights: ► Synthesis of 3D BiOI/BiOCl microspheres by a one-pot template-free solvothermal method. ► Photocatalyst is BiOI/BiOCl composites. ► BiOI/BiOCl composites have enhanced visible-light photocatalytic ability to bisphenol-A. ► A simple and direct photodegradation pathway of bisphenol-A is proposed. - Abstract: Three-dimensional (3D) BiOI/BiOCl composite microspheres with enhanced visible-light photodegradation activity of bisphenol-A (BPA) are synthesized by a simple, one-pot, template-free, solvothermal method using BiI 3 and BiCl 3 as precursors. These 3D hierarchical microspheres with heterojunction structures are composed of 2D nanosheets and have composition-dependent absorption properties in the ultraviolet and visible light regions. The photocatalytic oxidation of BPA over BiOI/BiOCl composites followed pseudo first-order kinetics according to the Langmuir–Hinshelwood model. The highest photodegradation efficiency of BPA, i.e., nearly 100%, was observed with the BiOI/BiOCl composite (containing 90% BiOI) using a catalyst dosage of 1 g L −1 in the BPA solution (C 0 = 20 mg L −1 , pH = 7.0) under visible light irradiation for 60 min. Under these conditions, the reaction rate constant was more than 4 and 20 times greater than that of pure BiOI and the commercially available Degussa P25, respectively. The superior photocatalytic activity of this composite catalyst is attributed to the suitable band gap energies and the low recombination rate of the photogenerated electron–hole pairs due to the presence of BiOI/BiOCl heterostructures. Only one intermediate at m/z 151 was observed in the photodegradation process of BPA by liquid chromatography combined with mass spectrometry (LC–MS) analysis, and a simple and hole-predominated photodegradation pathway of BPA was subsequently proposed. Furthermore, this photocatalyst exhibited a high mineralization ratio, high stability and easy separation for recycling use, suggesting that it is a

Removal of brominated flame retardant from electrical and electronic waste plastic by solvothermal technique

International Nuclear Information System (INIS)

Zhang, Cong-Cong; Zhang, Fu-Shen

2012-01-01

Highlights: ► A process for brominated flame retardants (BFRs) removal in plastic was established. ► The plastic became bromine-free with the structure maintained after this treatment. ► BFRs transferred into alcohol solvent were easily debrominated by metallic copper. - Abstract: Brominated flame retardants (BFRs) in electrical and electronic (E and E) waste plastic are toxic, bioaccumulative and recalcitrant. In the present study, tetrabromobisphenol A (TBBPA) contained in this type of plastic was tentatively subjected to solvothermal treatment so as to obtain bromine-free plastic. Methanol, ethanol and isopropanol were examined as solvents for solvothermal treatment and it was found that methanol was the optimal solvent for TBBPA removal. The optimum temperature, time and liquid to solid ratio for solvothermal treatment to remove TBBPA were 90 °C, 2 h and 15:1, respectively. After the treatment with various alcohol solvents, it was found that TBBPA was finally transferred into the solvents and bromine in the extract was debrominated catalyzed by metallic copper. Bisphenol A and cuprous bromide were the main products after debromination. The morphology and FTIR properties of the plastic were generally unchanged after the solvothermal treatment indicating that the structure of the plastic maintained after the process. This work provides a clean and applicable process for BFRs-containing plastic disposal.

Fast microwave-assisted solvothermal synthesis of metal nanoparticles (Pd, Ni, Sn) supported on sulfonated MWCNTs: Pd-based bimetallic catalysts for ethanol oxidation in alkaline medium

CSIR Research Space (South Africa)

Ramulifho, T

2012-01-01

Full Text Available The preparation of metal nanoparticles (Pd, Ni, Sn) supported on sulfonated multi-walled carbon nanotubes (SF-MWCNTs) using a very rapid microwave-assisted solvothermal strategy has been described. Electrocatalytic behaviour of the SF...

Facile preparation of porous carbon from coffee bean waste using low temperature solvothermal method

Science.gov (United States)

Baroroh, L. A. Al; Fitria, D.; Amal, M. I.; Wismogroho, A. S.; Widayatno, W. B.

2018-03-01

In this study, porous carbon made from coffee bean waste (CBW) was carbonized at 500 °C, 600 °C, and 700 °C to find effective temperature. It is verified from the IR spectrum that carbonization process at certain temperature can effectively break cellulose bonding and make aromatics functional group while preserving its carbon structure. The TG-DTA curve shows four stages of decomposition process and confirms most effective carbonization temperature. Activation process of as-carbonized CBW was carried out using solvothermal method in KOH and NH4OH steam environment at 200 °C with variation of 30%, 40%, and 50% solvothermal volume. Scanning electron micrographs reveals significant increase of porosity on the carbon surface and differences of structural pores between the variations. The results show the possible potential of utilizing low temperature-solvothermal method for nanoporous carbon material.

Removal of brominated flame retardant from electrical and electronic waste plastic by solvothermal technique

Energy Technology Data Exchange (ETDEWEB)

Zhang, Cong-Cong [Research Center For Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Zhang, Fu-Shen, E-mail: fszhang@rcees.ac.cn [Research Center For Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)

2012-06-30

Highlights: Black-Right-Pointing-Pointer A process for brominated flame retardants (BFRs) removal in plastic was established. Black-Right-Pointing-Pointer The plastic became bromine-free with the structure maintained after this treatment. Black-Right-Pointing-Pointer BFRs transferred into alcohol solvent were easily debrominated by metallic copper. - Abstract: Brominated flame retardants (BFRs) in electrical and electronic (E and E) waste plastic are toxic, bioaccumulative and recalcitrant. In the present study, tetrabromobisphenol A (TBBPA) contained in this type of plastic was tentatively subjected to solvothermal treatment so as to obtain bromine-free plastic. Methanol, ethanol and isopropanol were examined as solvents for solvothermal treatment and it was found that methanol was the optimal solvent for TBBPA removal. The optimum temperature, time and liquid to solid ratio for solvothermal treatment to remove TBBPA were 90 Degree-Sign C, 2 h and 15:1, respectively. After the treatment with various alcohol solvents, it was found that TBBPA was finally transferred into the solvents and bromine in the extract was debrominated catalyzed by metallic copper. Bisphenol A and cuprous bromide were the main products after debromination. The morphology and FTIR properties of the plastic were generally unchanged after the solvothermal treatment indicating that the structure of the plastic maintained after the process. This work provides a clean and applicable process for BFRs-containing plastic disposal.

Heterometallic clusters arising from cubic Ni3M'O4 (M'=K and Na) entity: Solvothermal synthesis with/without the assistance of microwave

International Nuclear Information System (INIS)

Zhang Shuhua; Zhou Yanling; Sun Xiaojun; Wei, Lian-Qiang; Zeng Minghua; Liang Hong

2009-01-01

Solvothermal reaction assisted with microwave leads to the formation of two unique heterometallic cubic clusters [Ni 3 M'(L) 3 (OH)(CH 3 CN) 3 ] 2 .CH 3 CN (M'=K for 1 and M'=Na for 2, where L is an anion of 2-[(2-hydroxy-3-methoxy-benzylidene)-amino]-ethanesulfonate) with higher efficiency, yields and purity than those without it. The 6-metallacrown-3 [Ni 3 (OH)(L) 3 ] - groups exhibit interesting ion trapping and self-assembly of size-different Na + and K + through form recognition and coordination activity in 1 and 2. The magnetic studies for 1 and 2 suggest that the {Ni 3 M'O 4 } (M'=K and Na) cores both display dominant ferromagnetic interactions from the nature of the binding modes of μ 3 -O (oxidophenyl) and μ 3 -OH. - Graphical abstract: Solvothermal reaction assisted with microwave leads to two heterometallic cubic clusters with 6-metallacrown-3 structure [Ni 3 O 3 (OH)] - acting as a host for a K + or Na + ion. The {Ni 3 M'O 4 } (M'=K, Na) cores display dominant ferromagnetic interactions.

Positron annihilation spectroscopic studies of solvothermally synthesized ZnO nanobipyramids and nanoparticles

Science.gov (United States)

Ghoshal, Tandra; Biswas, Subhajit; Kar, Soumitra; Chaudhuri, Subhadra; Nambissan, P. M. G.

2008-02-01

Zinc oxide (ZnO) samples in the form of hexagonal-based bipyramids and particles of nanometer dimensions were synthesized through solvothermal route and characterized by x-ray diffraction and transmission electron microscopy. Positron annihilation experiments were performed to study the structural defects such as vacancies and surfaces in these nanosystems. From coincidence Doppler broadening measurements, the positron trapping sites were identified as Zn vacancies or Zn-O-Zn trivacancy clusters. The positron lifetimes, their relative intensities, and the Doppler broadened lineshape parameter S all showed characteristic changes across the nanobipyramid size corresponding to the thermal diffusion length of positrons. In large nanobipyramids, vacancies within the crystallites also trapped positrons and the effects of agglomeration of such vacancies due to increased temperatures of synthesis were reflected in the variation of the annihilation parameters with their base diameters. The sizes of the nanoparticles used were all in the limit of thermal diffusion length of positrons and the annihilation characteristics were in accordance with the decreasing contribution from surfaces with increasing particle size.

Synthesis of belt-like BiOBr hierarchical nanostructure with high photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Li, Haiping [National Engineering Technology Research Center for Colloidal Materials, Shandong University, Jinan 250100 (China); Liu, Jingyi; Hu, Tingxia [Environment Research Institute, Shandong University, Jinan 250100 (China); Du, Na; Song, Shue [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China); Hou, Wanguo, E-mail: wghou@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China)

2016-05-15

Highlights: • BiOBr hierarchical nanobelts (NBs) were solvothermally prepared. • NBs show higher specific surface area and photoabsorption than BiOBr nanosheets. • NBs exhibit higher photoactivity than the nanosheets. - Abstract: One-dimensional (1D) bismuth oxyhalide (BiOX) hierarchical nanostructures are always difficult to prepare. Herein, we report, for the first time, a simple synthesis of BiOBr nanobelts (NBs) via a facile solvothermal route, using bismuth subsalicylate as the template and bismuth source. The BiOBr nanobelts are composed of irregular single crystal nanoparticles with highly exposed (0 1 0) facets. Compared with the BiOBr nanosheets (NSs) with dominant exposed (0 0 1) facets, they exhibit higher photocatalytic activity toward degradation of Rhodamine B and Methylene Blue under visible light irradiation. The higher photocatalytic performance of BiOBr NBs arises from their larger specific surface area and higher photoabsorption capability. This study provides a simple route for synthesis of belt-like Bi-based hierarchical nanostructures.

Green synthesis of CuInS2/ZnS core-shell quantum dots by facile solvothermal route with enhanced optical properties

Science.gov (United States)

Jindal, Shikha; Giripunje, Sushama M.; Kondawar, Subhash B.; Koinkar, Pankaj

2018-03-01

We report an eco-friendly green synthesis of highly luminescent CuInS2/ZnS core-shell quantum dots (QDs) with average particle size ∼ 3.9 nm via solvothermal process. The present study embodies the intensification of CuInS2/ZnS QDs properties by the shell growth on the CuInS2 QDs. The as-prepared CuInS2 core and CuInS2/ZnS core-shell QDs have been characterized using a range of optical and structural techniques. By adopting a low temperature growth of CuInS2 core and high temperature growth of CuInS2/ZnS core-shell growth, the tuning of absorption and photoluminescence emission spectra were observed. Optical absorption and photoluminescence spectroscopy probe the effect of ZnS passivation on the electronic structure of the CuInS2 dots. In addition, QDs have been scrutinized using ultra violet photoelectron spectroscopy (UPS) to explore their electronic band structure. The band level positions of CuInS2 and CuInS2/ZnS QDs suffices the demand of non-toxic acceptor material for electronic devices. The variation in electronic energy levels of CuInS2 core with the coating of wide band gap ZnS shell influence the removal of trap assisted recombination on the surface of the core. QDs exhibited tunable emission from red to orange region. These studies reveal the feasibility of QDs in photovoltaic and light emitting diodes.

In situ XAS of the solvothermal decomposition of dithiocarbamate complexes

NARCIS (Netherlands)

Islam, H.-U.; Roffey, A.; Hollingsworth, N.; Catlow, R.; Wolthers, M.; de Leeuw, N.H.; Bras, W.; Sankar, G.; Hogarth, G.

2012-01-01

An in situ XAS study of the solvothermal decomposition of iron and nickel dithiocarbamate complexes was performed in order to gain understanding of the decomposition mechanisms. This work has given insight into the steps involved in the decomposition, showing variation in reaction pathways between

Synthesis and characterization of the ternary telluroargentate K4[Ag18Te11

KAUST Repository

Davaasuren, Bambar; Dashjav, Enkhtsetseg; Rothenberger, Alexander

2014-01-01

The ternary potassium telluroargentate(I), K4[Ag18Te11], was prepared by solvothermal synthesis in ethylenediamine at 160 °C. It crystallizes in the cubic space group Fm3¯ m (no. 225) with the cell parameter a = 18.6589(6) Å. The crystal structure

One-pot solvothermal synthesis of three-dimensional (3D) BiOI/BiOCl composites with enhanced visible-light photocatalytic activities for the degradation of bisphenol-A

Energy Technology Data Exchange (ETDEWEB)

Xiao, Xin [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Hao, Rong; Liang, Min; Zuo, Xiaoxi [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Nan, Junmin, E-mail: jmnan@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Li, Laisheng [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Zhang, Weide [Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China)

2012-09-30

Highlights: Black-Right-Pointing-Pointer Synthesis of 3D BiOI/BiOCl microspheres by a one-pot template-free solvothermal method. Black-Right-Pointing-Pointer Photocatalyst is BiOI/BiOCl composites. Black-Right-Pointing-Pointer BiOI/BiOCl composites have enhanced visible-light photocatalytic ability to bisphenol-A. Black-Right-Pointing-Pointer A simple and direct photodegradation pathway of bisphenol-A is proposed. - Abstract: Three-dimensional (3D) BiOI/BiOCl composite microspheres with enhanced visible-light photodegradation activity of bisphenol-A (BPA) are synthesized by a simple, one-pot, template-free, solvothermal method using BiI{sub 3} and BiCl{sub 3} as precursors. These 3D hierarchical microspheres with heterojunction structures are composed of 2D nanosheets and have composition-dependent absorption properties in the ultraviolet and visible light regions. The photocatalytic oxidation of BPA over BiOI/BiOCl composites followed pseudo first-order kinetics according to the Langmuir-Hinshelwood model. The highest photodegradation efficiency of BPA, i.e., nearly 100%, was observed with the BiOI/BiOCl composite (containing 90% BiOI) using a catalyst dosage of 1 g L{sup -1} in the BPA solution (C{sub 0} = 20 mg L{sup -1}, pH = 7.0) under visible light irradiation for 60 min. Under these conditions, the reaction rate constant was more than 4 and 20 times greater than that of pure BiOI and the commercially available Degussa P25, respectively. The superior photocatalytic activity of this composite catalyst is attributed to the suitable band gap energies and the low recombination rate of the photogenerated electron-hole pairs due to the presence of BiOI/BiOCl heterostructures. Only one intermediate at m/z 151 was observed in the photodegradation process of BPA by liquid chromatography combined with mass spectrometry (LC-MS) analysis, and a simple and hole-predominated photodegradation pathway of BPA was subsequently proposed. Furthermore, this photocatalyst

Solvothermal and electrochemical synthetic method of HKUST-1 and its methane storage capacity

Science.gov (United States)

Wahyu Lestari, Witri; Adreane, Marisa; Purnawan, Candra; Fansuri, Hamzah; Widiastuti, Nurul; Budi Rahardjo, Sentot

2016-02-01

A comparison synthetic strategy of Metal-Organic Frameworks, namely, Hongkong University of Techhnology-1 {HKUST-1[Cu3(BTC)]2} (BTC = 1,3,5-benzene-tri-carboxylate) through solvothermal and electrochemical method in ethanol:water (1:1) has been conducted. The obtained material was analyzed using powder X-ray diffraction, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA) and Surface Area Analysis (SAA). While the voltage in the electrochemical method are varied, ranging from 12 to 15 Volt. The results show that at 15 V the texture of the material has the best degree of crystallinity and comparable with solvothermal product. This indicated from XRD data and supported by the SEM image to view the morphology. The thermal stability of the synthesized compounds is up to 320 °C. The shape of the nitrogen sorption isotherm of the compound corresponds to type I of the IUPAC adsorption isotherm classification for microporous materials with BET surface area of 629.2 and 324.3 m2/g (for solvothermal and electrochemical product respectively) and promising for gas storage application. Herein, the methane storage capacities of these compounds are also tested.

Controlled synthesis of multi-morphology Te crystals by a convenient Lewis acid/base-assisted solvothermal method

International Nuclear Information System (INIS)

Wu Xiaoping; Yuan Lin; Zhou Shaomin; Lou Shiyun; Wang Yongqiang; Gao Tao; Liu YuBiao; Shi Xiaojing

2012-01-01

This paper reports on the controlled growth of multi-morphology Te crystals by a convenient Lewis acid/base-assisted solvothermal method for the first time. The morphological transformation from one-dimension (1D) nanostructures to 2D hierarchical flowerlike microarchitecture has been observed. The nanorods and nanowires with a well-defined crystallographical structure and the hierarchical flowers microarchitecture were obtained by changing the Lewis acids/bases. Lewis acids/bases were found to be crucial for the formation of the products by not only acting as the pH regulator but also as the shape controller, owing to their hydrolysis in the solvent to in situ form H + /OH − and hydrates. The results suggest that this should be an effective approach to the control the growth of t-Te crystals with interesting multiple morphologies, which are of interest for both theoretical investigations and practical applications.

Shape-Evolution Control of hybrid perovskite CH3NH3PbI3 crystals via solvothermal synthesis

Science.gov (United States)

Zhang, Baohua; Guo, Fuqiang; Yang, Lianhong; Jia, Xiuling; Liu, Bin; Xie, Zili; Chen, Dunjun; Lu, Hai; Zhang, Rong; Zheng, Youdou

2017-02-01

We systematically synthesized CH3NH3PbI3 crystals using solvothermal process, and the reaction conditions such as concentration of the precursor, temperature, time, and lead source have been comprehensively investigated to obtain shape-controlled CH3NH3PbI3 crystals. The results showed that the CH3NH3PbI3 crystals exhibit tetragonal phase and the crystals change from nanoparticles to hopper-faced cuboids. Photoluminescence spectra of the crystals obtained with different lead sources show a blue shift due to the presence of defects in the crystals, and the peak intensity is very sensitive to the lead sources. Moreover, impurities (undesirable byproducts and excess components like HI or CH3NH2) presented during crystal growth can result in hopper growth.

Solvothermal synthesis of mesoporous magnetite nanoparticles for Cr(IV) ions uptake and microwave absorption

Energy Technology Data Exchange (ETDEWEB)

Shen, Peng; Zhang, Haitao, E-mail: htzhang@ipe.ac.cn; Zhang, Suojiang, E-mail: sjzhang@ipe.ac.cn; Yuan, Pei [Chinese Academy of Sciences, Beijing Key Laboratory of Ionic Liquids Clean Process Institute of Process Engineering, Key Laboratory of Green Process and Engineering, Institute of Process Engineering (China); Yang, Yang [China Building Materials Academy, State Key Laboratory of Green Building Materials (China); Zhang, Qiang; Zhang, Xixiang [King Abdullah University of Science and Technology, Physical Science and Engineering (Saudi Arabia)

2016-05-15

Colloidal mesoporous magnetite nanoparticles with tunable porosity were realized by a simple and scalable solvothermal route with the aid of AOT as ligands. AOT was used to induce the anisotropic crystal growth of smaller nanocrystals and restrain their tight aggregation so as to form more mesoscale pores. Morphologies and microstructures investigation by SEM and TEM revealed that the bigger nanoparticles were composed of smaller nanocrystals with an average size of 18 nm. A possible formation mechanism was proposed for the mesoporous nanoparticles. Study of nitrogen adsorption–desorption isotherm revealed that the Brunauer–Emmett–Teller (BET) specific surface area of mesoporous nanoparticles is up to 209 m{sup 2}/g, resulting from the slit-shaped pores created by the aggregation of polyhedral nanocrystals. Magnetic properties study indicated that the as-prepared nanoparticles are superparamagnetic at room temperature. Optimized mesoporous magnetite nanoparticles exhibit a maximum Cr(VI) ion sorption capacity of 12.9 mmol/g, and its absorption behavior followed a Freundlich model. Microwave absorption study indicated that porous nanoparticles own higher permeability values than that of solid nanoparticles, leading to a higher dielectric loss in the frequency range of 2–18 GHz.Graphical Abstract.

A Comparative Study of Solvothermal and Sol-Gel-Derived Nanocrystalline Alumina Catalysts for Ethanol Dehydration

Directory of Open Access Journals (Sweden)

Mingkwan Wannaborworn

2015-01-01

Full Text Available The ethanol dehydration to ethylene over alumina catalysts prepared by solvothermal and sol-gel methods was investigated. Also, a commercial alumina was used for comparison purposes. The results showed that the catalytic activity depends on the properties of catalyst derived from different preparation methods and reaction temperature. The alumina synthesized by solvothermal method exhibited the highest activity. This can be attributed to the higher surface area and larger amount of acid site, especially the ratio of weak/strong acid strength as determined by N2 physisorption and NH3-TPD studies. The solvothermal-derived catalyst exhibited an excellent performance with complete ethanol conversion and 100% selectivity to ethylene at 350°C in comparison with other ones. In addition, we further studied the catalytic dehydration of alumina catalyst modified with Fe. The presence of 10 wt.% Fe decreased both conversion and ethylene selectivity. However, the acetaldehyde selectivity apparently increased. It was related to the dehydrogenation pathway that takes place on Fe species.

Investigation on development of advanced materials by solvothermal technique; Sorubo thermal hanno riyo senshin zairyo kaihatsu ni kansuru chosa

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

Solvothermal reaction is reaction under high temperature and high pressure, which is expected to fabricate new functional materials. In this study, the materials are classified into two fields, i.e., inorganic materials, metals and their composites and organic materials and their composites. The current status of R and D of production and processing technology in each field is surveyed and the prospect of it is discussed. For the inorganic materials, metals and their composites, it is explained that very fine metal oxide particles, complex oxides, single crystals, whiskers, compounds with layer structure, metastable compounds, ion conductors and catalysts with high ability could be produced only by controlling the solvothermal reactions in atomic order. For the organic materials and their composites, surveyed results of the solvothermal technique using non-aqueous solutions are mainly provided. The necessity of a national project for researches on the solvothermal reactions is proposed from the viewpoint of resource, environment and energy. 777 refs., 38 figs., 26 tabs.

Improved electrochemical performance of Li4Ti5O12 with a variable amount of graphene as a conductive agent for rechargeable lithium-ion batteries by solvothermal method

International Nuclear Information System (INIS)

Rai, Alok Kumar; Gim, Jihyeon; Kang, Sung-Won; Mathew, Vinod; Anh, Ly Tuan; Kang, Jungwon; Song, Jinju; Paul, Baboo Joseph; Kim, Jaekook

2012-01-01

We report on the solvothermal preparation of pure Li 4 Ti 5 O 12 and Li 4 Ti 5 O 12 /graphene (15 wt% and 30 wt%) nanocomposites anode for high-performance lithium-ion batteries. Structure and morphology studies of the nanocomposites by X-ray diffraction, field-emission scanning electron microscopy and field-emission transmission electron microscopy reveal Li 4 Ti 5 O 12 nanoparticles embedded onto the graphene nanosheets. On comparison to pure spinel Li 4 Ti 5 O 12 , the electrochemical performances of the Li 4 Ti 5 O 12 /graphene nanocomposites indicate higher capacities and enhanced cycle performances within the voltage domain of 1.0–2.5 V, under current rates as high as 10.4 C. The production of phase pure Li 4 Ti 5 O 12 nanoparticles ensures the short ion-diffusion paths while the presence of graphene facilitates improved structural network and hence enhanced electronic transport in the prepared nanocomposites. These factors eventually amount to impressive electrochemical properties. Highlights: ► A simple polyol-based approach to obtain the graphene nanosheets. ► Li 4 Ti 5 O 12 /graphene nanocomposites synthesis by polyol-based solvothermal process. ► Low temperature solvothermal strategy is one-step process to control nanoparticle sizes. ► The nanoparticles are well anchored onto the graphene nanosheets in the nanocomposites. ► Li 4 Ti 5 O 12 /graphene nanocomposites exhibit impressive electrochemical performances.

Solvothermal Synthesis of Zn2SnO4 Nanocrystals and Their Photocatalytic Properties

Directory of Open Access Journals (Sweden)

Guang Sun

2014-01-01

Full Text Available Crystalline Zn2SnO4 nanoparticles were successfully synthesized via a simple solvothermal route by using Zn(CH3COO2·2H2O and SnCl4·5H2O as source materials, NaOH as mineralizing agent, and water and ethanol as mixed solvents. The used amount of NaOH was found to have an important influence on the formation of Zn2SnO4. When the molar ratio of OH− : Zn2+ : Sn4+ was set in the range from 4 : 2 : 1 to 8 : 2 : 1, Zn2SnO4 nanoparticles with different shape and size were obtained. However, when the molar ratio of OH− : Zn2+ : Sn4+ was set as 10 : 2 : 1, a mixture phase of ZnO and ZnSn(OH6 instead of Zn2SnO4 was obtained. Photodegradation measurements indicated that the Zn2SnO4 nanoparticles own better photocatalytic property to depredate methyl orange than the Zn2SnO4 nanopolyhedrons. The superior photocatalytic properties of Zn2SnO4 nanoparticles may be contributed to their small crystal size and high surface area.

The iron member of the CPO-27 coordination polymer series: Synthesis, characterization, and intriguing redox properties

DEFF Research Database (Denmark)

Märcz, Matthias; Johnsen, Rune; Dietzel, Pascal D.C.

2012-01-01

The microporous coordination polymer CPO-27-Fe was synthesized from iron salts and 2,5-dihydroxyterephthalic acid by microwave assisted solvothermal synthesis. The crystal structures of the as-synthesized compounds were determined by Rietveld refinement from powder X-ray diffraction data using...

Solvothermal synthesis and good microwave absorbing properties for magnetic porous-Fe3O4/graphene nanocomposites

Directory of Open Access Journals (Sweden)

Xiaojun Zeng

2017-05-01

Full Text Available The magnetic porous-Fe3O4/graphene nanocomposites have been fabricated by a facile solvothermal method. The porous Fe3O4 nanospheres are embedded uniformly in the graphene oxide (GO sheets to form a 3D Fe3O4/GO nanocomposite network. The dielectric properties for the Fe3O4/GO composites can be greatly improved by the 7 wt% GO additions. Good impedance matching can be also obtained in these Fe3O4/GO composites, which is proved to dominate their excellent microwave absorbing properties including the minimum reflection loss (RL value of -43.7 dB at 6.8 GHz with a sample thickness of 5 mm and a broad absorption bandwidth of 5.92 GHz (below -10 dB. These porous-Fe3O4/GO composites also exhibit the good structural stability and low density, which shows their great potential application in high-performance electromagnetic microwave-absorbing materials.

Characterization of crystalline silica nanorods synthesized via a solvothermal route using polyvinylbutyral as a template

International Nuclear Information System (INIS)

Chen, Lin-Jer; Liao, Jiunn-Der; Chuang, Yu-Ju; Fu, Yaw-Shyan

2011-01-01

The preparation of crystalline silica nanorods is presented. Crystalline silica nanorods were synthesized via a simple solvothermal route using polyvinylbutyral (PVB) as a template in an autoclave with ethylenediamine as a solvent at 180 °C for 25 h. Silica nanorods with diameters in the range of 50–80 nm were obtained. The solvothermal route with a PVB template played affected the crystallization process and the growth of the silica nanorods. The as-synthesized products were characterized using X-ray diffraction, energy dispersive spectrometry, scanning electron microscopy, and transmission electron microscopy.

One-pot, template- and surfactant-free solvothermal synthesis of high-crystalline Fe{sub 3}O{sub 4} nanostructures with adjustable morphologies and high magnetization

Energy Technology Data Exchange (ETDEWEB)

Zong, Yan; Xin, Hongna; Zhang, Jiarui [School of Physics, Northwest University, Xi’an 710000 (China); Li, Xinghua, E-mail: lixinghua04@gmail.com [School of Physics, Northwest University, Xi’an 710000 (China); Feng, Juan [School of Physics, Northwest University, Xi’an 710000 (China); Deng, Xia [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Sun, Yong [School of Physics, Northwest University, Xi’an 710000 (China); Zheng, Xinliang, E-mail: zhengxl@nwu.edu.cn [School of Physics, Northwest University, Xi’an 710000 (China)

2017-02-01

In the present study, high-crystalline and well-defined Fe{sub 3}O{sub 4} nanostructures with tunable morphologies were fabricated through a facile one-pot solvothermal approach. The morphology, crystal structure and chemical compositions of the products were characterized at the nanoscale. X-ray diffraction and selected area electron diffraction patterns indicate that the products have a pure spinel phase without the presence of any other impurity. Based on the transmission electron microscope technology, shape evolution of the products were investigated. Several morphologies including irregular particles, clusters, hollow sphere and octahedrons can be obtained by only adjusting the amount of NaOH without using any surfactant. Magnetism investigations show that all the products perform ferromagnetic behavior with high saturation magnetization at room temperature, which mainly originates from their high crystalline nature and template-free fabrication process. - Highlights: • Fe{sub 3}O{sub 4} were prepared by a template- and surfactant-free solvothermal route. • The shapes of Fe{sub 3}O{sub 4} nanostructures can be controlled by changing the amount of NaOH. • All the Fe{sub 3}O{sub 4} nanostructures with different shapes have high magnetization values.

Solvothermal synthesis of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanophosphor in water/diethylene glycol system

Energy Technology Data Exchange (ETDEWEB)

Takeshita, Satoru; Honda, Joji [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Isobe, Tetsuhiko, E-mail: isobe@applc.keio.ac.jp [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Sawayama, Tomohiro; Niikura, Seiji [SINLOIHI Company, Limited, 2-19-12 Dai, Kamakura 247-8550 (Japan)

2012-05-15

The influence of aging of the suspension containing the amorphous precusors on structural, compositional and photoluminescent properties is studied to understand the mechanism on the formation of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanoparticles during the solvothermal reaction in the water/diethylene glycol mixed solvent. Aging at 200 Degree-Sign C for 20 min forms the crystalline Zn{sub 2}GeO{sub 4} nanorods and then they grow up to {approx} 50 nm in mean length after aging for 240 min. Their interplanar spacing of (410) increases with increasing the aging time. The photoluminescence intensity corresponding to the d-d transition of Mn{sup 2+} increases with increasing the aging time up to 120 min, and then decreases after aging for 240 min. The photoluminescence lifetime decreases with increasing the aging time, indicating the locally concentrated Mn{sup 2+} ions. These results reveal that Mn{sup 2+} ions gradually replace Zn{sup 2+} ions near surface through repeating dissolusion and precipitation processes during prolonged aging after the complete crystallization of Zn{sub 2}GeO{sub 4}. - Graphical abstract: TEM images of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanoparticles aged at 200 Degree-Sign C for different aging times in the mixed solvent of water and diethylene glycol. Highlights: Black-Right-Pointing-Pointer Mechanism on formation of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanophosphor under solvothermal condition. Black-Right-Pointing-Pointer Zn{sub 2}GeO{sub 4} nanorods crystallize via amorphous precursors. Black-Right-Pointing-Pointer Gradual substitution of Mn{sup 2+} during prolonged aging. Black-Right-Pointing-Pointer Such an inhomogeneous Mn{sup 2+} doping process results in concentration quenching.

Solvothermal synthesis of mesoporous magnetite nanoparticles for Cr(IV) ions uptake and microwave absorption

KAUST Repository

Shen, Peng; Zhang, Haitao; Zhang, Suojiang; Yuan, Pei; Yang, Yang; Zhang, Qiang; Zhang, Xixiang

2016-01-01

Abstract: Colloidal mesoporous magnetite nanoparticles with tunable porosity were realized by a simple and scalable solvothermal route with the aid of AOT as ligands. AOT was used to induce the anisotropic crystal growth of smaller nanocrystals and restrain their tight aggregation so as to form more mesoscale pores. Morphologies and microstructures investigation by SEM and TEM revealed that the bigger nanoparticles were composed of smaller nanocrystals with an average size of 18 nm. A possible formation mechanism was proposed for the mesoporous nanoparticles. Study of nitrogen adsorption–desorption isotherm revealed that the Brunauer–Emmett–Teller (BET) specific surface area of mesoporous nanoparticles is up to 209 m2/g, resulting from the slit-shaped pores created by the aggregation of polyhedral nanocrystals. Magnetic properties study indicated that the as-prepared nanoparticles are superparamagnetic at room temperature. Optimized mesoporous magnetite nanoparticles exhibit a maximum Cr(VI) ion sorption capacity of 12.9 mmol/g, and its absorption behavior followed a Freundlich model. Microwave absorption study indicated that porous nanoparticles own higher permeability values than that of solid nanoparticles, leading to a higher dielectric loss in the frequency range of 2–18 GHz. Graphical Abstract: [Figure not available: see fulltext.] © 2016, Springer Science+Business Media Dordrecht.

Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

International Nuclear Information System (INIS)

Wang Huanwen; Hu Zhongai; Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying

2010-01-01

This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 o C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g -1 (based on composite) is obtained at a specific current of 1 A g -1 as compared with 71 F g -1 for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g -1 even at 10 A g -1 . In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

Solvothermal synthesis of mesoporous magnetite nanoparticles for Cr(IV) ions uptake and microwave absorption

KAUST Repository

Shen, Peng

2016-05-12

Abstract: Colloidal mesoporous magnetite nanoparticles with tunable porosity were realized by a simple and scalable solvothermal route with the aid of AOT as ligands. AOT was used to induce the anisotropic crystal growth of smaller nanocrystals and restrain their tight aggregation so as to form more mesoscale pores. Morphologies and microstructures investigation by SEM and TEM revealed that the bigger nanoparticles were composed of smaller nanocrystals with an average size of 18 nm. A possible formation mechanism was proposed for the mesoporous nanoparticles. Study of nitrogen adsorption–desorption isotherm revealed that the Brunauer–Emmett–Teller (BET) specific surface area of mesoporous nanoparticles is up to 209 m2/g, resulting from the slit-shaped pores created by the aggregation of polyhedral nanocrystals. Magnetic properties study indicated that the as-prepared nanoparticles are superparamagnetic at room temperature. Optimized mesoporous magnetite nanoparticles exhibit a maximum Cr(VI) ion sorption capacity of 12.9 mmol/g, and its absorption behavior followed a Freundlich model. Microwave absorption study indicated that porous nanoparticles own higher permeability values than that of solid nanoparticles, leading to a higher dielectric loss in the frequency range of 2–18 GHz. Graphical Abstract: [Figure not available: see fulltext.] © 2016, Springer Science+Business Media Dordrecht.

Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

Energy Technology Data Exchange (ETDEWEB)

Wang Huanwen [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Hu Zhongai, E-mail: zhongai@nwnu.edu.c [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

2010-12-01

This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 {sup o}C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g{sup -1} (based on composite) is obtained at a specific current of 1 A g{sup -1} as compared with 71 F g{sup -1} for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g{sup -1} even at 10 A g{sup -1}. In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

Solvothermal synthesis of carbon coated N-doped TiO{sub 2} nanostructures with enhanced visible light catalytic activity

Energy Technology Data Exchange (ETDEWEB)

Yan Xuemin, E-mail: yanzhangmm2002@163.com [College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023 (China); Kang Jialing; Gao Lin; Xiong Lin; Mei Ping [College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023 (China)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Chitosan was used as carbon and nitrogen resource to modify TiO{sub 2} nanostructure. Black-Right-Pointing-Pointer Nanocomposites with mesostructure were obtained by one-step solvothermal method. Black-Right-Pointing-Pointer Carbon species were modified on the surface of TiO{sub 2}. Black-Right-Pointing-Pointer Nitrogen was doped into the anatase titania lattice. Black-Right-Pointing-Pointer CTS-TiO{sub 2} nanocomposites show superior visible light photocatalytic activity. - Abstract: Visible light-active carbon coated N-doped TiO{sub 2} nanostructures(CTS-TiO{sub 2}) were prepared by a facile one-step solvothermal method with chitosan as carbon and nitrogen resource at 180 Degree-Sign C. The as-prepared samples were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N{sub 2} adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. The CTS-TiO{sub 2} nanocomposites possess anatase phase of nanocrystalline structure with average particle size of about 5-7 nm. A wormhole mesostructure can be observed in the CTS-TiO{sub 2} nanocomposites due to the constituent agglomerated of nanoparticles. It has been evidenced that the nitrogen was doped into the anatase titania lattice and the carbon species were modified on the surface of TiO{sub 2}. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methylene blue (MB) under visible light irradiation at {lambda} {>=} 400 nm. The results show that CTS-TiO{sub 2} nanostructures display a higher visible light photocatalytic activity than pure TiO{sub 2}, commercial P25 and C-coated TiO{sub 2} (C-TiO{sub 2}) photocatalysts. The higher photocatalytic activity could be attributed to the band-gap narrowed by N-doping and the accelerated separation of the photo-generated electrons

Large scale solvothermal synthesis and a strategy to obtain stable Langmuir–Blodgett film of CoFe2O4 nanoparticles

International Nuclear Information System (INIS)

Thampi, Arya; Babu, Keerthi; Verma, Seema

2013-01-01

Highlights: • Large scale, monodisperse CoFe 2 O 4 nanoparticles by solvothermal route. • LB technique to obtain stable film of CoFe 2 O 4 nanoparticles over a large area. • Hydrophobicity of substrate was enhanced utilizing LB films of cadmium arachidate. • P–A isotherm and AFM cross sectional height profile analysis confirms stability. • Large scale organization of nanoparticles for surface pressure higher than 15 mN/m. -- Abstract: Nearly monodisperse oleic acid coated cobalt ferrite nanoparticles were synthesized in large scale by a simple solvothermal method utilizing N-methyl 2-Pyrrolidone (NMP) as a high boiling solvent. The magnetic oxide was further investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Langmuir–Blodgett (LB) technique is discussed to obtain a 2D assembly of oleic acid coated CoFe 2 O 4 nanoparticles over a large area. We describe a method to obtain stable, condensed three layers of cadmium arachidate on a piranha treated glass substrate. The hydrophobic surface thus obtained was subsequently used for forming a stable monolayer of oleic acid stabilized cobalt ferrite nanoparticles at the air–water interface. The stability of the LB films at the air–water interface was studied by pressure–area isotherm curves and atomic force microscopy (AFM) cross sectional height profile analysis. 2D organization of the magnetic nanoparticles at different surface pressures was studied by TEM. Preparation of large area LB films of CoFe 2 O 4 nanoparticles is reported for a surface pressure more than 15 mN/m

Copper-indium-gallium-diselenide nanoparticles synthesized by a solvothermal method for solar cell application

Directory of Open Access Journals (Sweden)

Chiou Chuan-Sheng

2017-01-01

Full Text Available Chalcopyrite copper-indium-gallium-diselenide (CIGS nanoparticles are useful for photovoltaic applications. In this study, the synthesis of CIGS powder was examined, and the powder was successfully synthesized using a relatively simple and convenient elemental solvothermal route. From the reactions of elemental Cu, In, Se and Ga(NO33 powders in an autoclave with ethylenediamine as a solvent, spherical CIGS nanoparticles, with diameters ranging from 20-40 nm, were obtained using a temperature of 200°C for 36h. The structure, morphology, chemical composition and optical properties of the as-synthesized CIGS were characterized using X-ray diffraction, transmission electron microscopy, selected area electron diffraction, scanning electron microscopy, inductively coupled plasma-mass spectrometry. In this sample, the mole ratio of Cu:In:Ga:Se was equal to 0.89:0.71:0.29:2.01, and the optical band gap was found to be 1.18 eV. The solar cell obtained a power conversion efficiency of 5.62% under standard air mass 1.5 global illumination.

Solvothermal synthesis of V2O5/graphene nanocomposites for high performance lithium ion batteries

International Nuclear Information System (INIS)

Chen, Da; Yi, Ran; Chen, Shuru; Xu, Terrence; Gordin, Mikhail L.; Lv, Dongping; Wang, Donghai

2014-01-01

Highlights: • A homogeneous V 2 O 5 /graphene nanocomposite is successfully synthesized. • V 2 O 5 nanoparticles are highly encapsulated in the 2D graphene matrix. • V 2 O 5 /graphene nanocomposite shows much better performance than bare V 2 O 5 . - Abstract: In this work, V 2 O 5 /graphene nanocomposites have been synthesized by a facile solvothermal approach. The V 2 O 5 nanoparticles, around 20–40 nm in size, were encapsulated in the 2D graphene matrix. The reversible Li-cycling properties of V 2 O 5 /graphene have been evaluated by galvanostatic discharge–charge cycling, cyclic voltammetry, and impedance spectroscopy. Compared with the bare V 2 O 5 nanoparticles, the V 2 O 5 /graphene nanocomposites exhibited enhanced electrochemical performance with higher reversible capacity and improved cycling stability and rate capability. The graphene nanosheets act not only as an electronically conductive matrix to improve the electronic and ionic conductivity of the composite electrode, but also as a flexible buffer matrix to maintain the structural integrity of the composite electrodes by preventing particle agglomeration, thus leading to the improvement of the electrochemical performance of V 2 O 5

The synthesis of porous Co3O4 micro cuboid structures by solvothermal approach and investigation of its gas sensing properties and catalytic activity

International Nuclear Information System (INIS)

Jamil, Saba; Jing, Xiaoyan; Wang, Jun; Li, Songnan; Liu, Jingyuan; Zhang, Milin

2013-01-01

Graphical abstract: - Highlights: • Micro cuboid Co 3 O 4 particle prepared by solvothermal method. • Study of morphology of synthesized cuboids before and after calcinations. • Investigation of formation mechanism of porous Co 3 O 4 from cuboid CoCO 3 . • Investigation of gas sensing properties of porous Co 3 O 4 . • Study of catalytic activity of product. - Abstract: The cobalt carbonate cuboids are prepared by adopting a simple solvothermal approach by using diethylene glycol and water in specific ratio as solvent. The prepared cobalt carbonate is subjected to different instrumentation to investigate its morphology and other properties. It is clear from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the product is distinct cuboid in shape with a size of approximately 3 μm from each face of the cube. Each particle of cuboid cobalt carbonate seems to comprise of layer by layer assembly of unit cells that consequently leads to a cuboid geometry. The cuboid cobalt carbonate was calcined at 700 °C in a furnace under argon atmosphere that decompose cobalt carbonate into porous Co 3 O 4 with the loosely packed arrangement of nano architectures. The gas sensing properties and catalytic activity of porous cuboids Co 3 O 4 are also investigated

Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

International Nuclear Information System (INIS)

Li, Tingting; Luo, Shenglian; Yang, Lixia

2013-01-01

Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O 2 · − , Br 0 and photogenerated h + play key roles in the photocatalytic degradation process

A facile solvothermal synthesis of large-grain iron cubes and cuboids with enhanced performances

International Nuclear Information System (INIS)

Yang, Bai; Yang, Xueying; Li, Xiaopan; Cao, Ying; Yu, Ronghai

2016-01-01

The cubic and cuboid pure iron particles with particle size ranging from 500 nm to 2 μm have been fabricated using a solvothermal method in ethanol solution. The controlled morphology and size distribution can be easily tuned by adjusting the reaction temperatures. The morphologies of the as-synthesized iron particles can be transformed from cubes to cuboids with the reaction temperature increasing from 100 to 150 °C. Uniform particles with narrow size distribution and good dispersion can be obtained under 120 °C. These chemically synthesized Fe particles exhibit good air stability and very slight surface oxidation. High saturation magnetization of 208–211 A m 2 /kg and very low coercivity of 19–26 Oe can be achieved in these micron-level iron particles due to their high purity and small shape anisotropy. The relatively simple preparation process with low cost, good air stability and high saturation magnetization for these large-grain pure iron particles promise their great potential applications in complicated shape and miniaturized Fe-based composite magnetic components. - Highlights: • The micron-level cubic and cuboid pure iron particles have been prepared. • The morphologies of the large-grain iron particles can be tuned. • These iron particles show slight surface oxidation and good air stability. • These iron particles exhibit high saturation magnetization of 208–211 A m 2 kg −1 .

Novel multiform morphologies of hydroxyapatite: Synthesis and growth mechanism

Energy Technology Data Exchange (ETDEWEB)

Mary, I. Reeta [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India); Department of Physics, Government Arts College, Coimbatore 641018 (India); Sonia, S.; Viji, S.; Mangalaraj, D.; Viswanathan, C. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India); Ponpandian, N., E-mail: ponpandian@buc.edu.in [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India)

2016-01-15

Graphical abstract: - Highlights: • Novel multiform morphologies of hydroxyapatite from nanoscale building blocks. • Facile hydro/solvothermal method under mild reaction conditions without the necessity of post-annealing treatment. • Growth mechanism by Ostwald ripening and self-assembly processes. - Abstract: Morphological evolution of materials becomes a prodigious challenge due to their key role in defining their functional properties and desired applications. Herein, we report the synthesis of hydroxyapatite (HAp) microstructures with multiform morphologies, such as spheres, cubes, hexagonal rods and nested bundles constructed from their respective nanoscale building blocks via a simple cost effective hydro/solvothermal method. A possible formation mechanism of diverse morphologies of HAp has been presented. Structural analysis based on X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirms the purity of the HAp microstructures. The multiform morphologies of HAp were corroborated by using Field emission scanning electron microscope (FESEM).

One-step synthesis of hierarchically porous hybrid TiO2 hollow spheres with high photocatalytic activity

Science.gov (United States)

Liu, Ruiping; Ren, Feng; Yang, Jinlin; Su, Weiming; Sun, Zhiming; Zhang, Lei; Wang, Chang-an

2016-03-01

Hierarchically porous hybrid TiO2 hollow spheres were solvothermally synthesized successfully by using tetrabutyl titanate as titanium precursor and hydrated metal sulfates as soft templates. The as-prepared TiO2 spheres with hierarchically pore structures and high specific surface area and pore volume consisted of highly crystallized anatase TiO2 nanocrystals hybridized with a small amount of metal oxide from the hydrated sulfate. The proposed hydrated-sulfate assisted solvothermal (HAS) synthesis strategy was demonstrated to be widely applicable to various systems. Evaluation of the hybrid TiO2 hollow spheres for the photo-decomposition of methyl orange (MO) under visible-light irradiation revealed that they exhibited excellent photocatalytic activity and durability.

Synthesis and characterization of ester and amide derivatives of titanium(IV) carboxymethylphosphonate

International Nuclear Information System (INIS)

Melánová, Klára; Beneš, Ludvík; Trchová, Miroslava; Svoboda, Jan; Zima, Vítězslav

2013-01-01

A set of layered ester and amide derivatives of titanium(IV) carboxymethylphosphonate was prepared by solvothermal treatment of amorphous titanium(IV) carboxymethylphosphonate with corresponding 1-alkanols, 1,ω-alkanediols, 1-aminoalkanes, 1,ω-diaminoalkanes and 1,ω-amino alcohols and characterized by powder X-ray diffraction, IR spectroscopy and thermogravimetric analysis. Whereas alkyl chains with one functional group form bilayers tilted to the layers, 1,ω-diaminoalkanes and most of 1,ω-alkanediols form bridges connecting the adjacent layers. In the case of amino alcohols, the alkyl chains form bilayer and either hydroxyl or amino group is used for bonding. This simple method for the synthesis of ester and amide derivatives does not require preparation of acid chloride derivative as a precursor or pre-intercalation with alkylamines and can be used also for the preparation of ester and amide derivatives of titanium carboxyethylphosphonate and zirconium carboxymethylphosphonate. - Graphical abstract: Ester and amide derivatives of layered titanium carboxymethylphosphonate were prepared by solvothermal treatment of amorphous solid with alkanol or alkylamine. - Highlights: • Ester and amide derivatives of titanium carboxymethylphosphonate. • Solvothermal treatment of amorphous solid with alkanol or alkylamine. • Ester and amide formation confirmed by IR spectroscopy

Solvothermal synthesis of Ni(HCO{sub 3}){sub 2}/graphene composites toward supercapacitors and the faradiac redox mechanism in KOH solution

Energy Technology Data Exchange (ETDEWEB)

Sun, Jinfeng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100080 (China); Li, Zhangpeng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Jinqing, E-mail: jqwang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Zhaofeng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Niu, Lengyuan; Gong, Peiwei [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100080 (China); Liu, Xiaohong; Wang, Honggang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yang, Shengrong, E-mail: sryang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2013-12-25

Highlights: •Ni(HCO{sub 3}){sub 2}/GS composites were prepared by a simple solvothermal method. •Ni(HCO{sub 3}){sub 2}/GS composites exhibited good supercapacitive performance. •Ni(HCO{sub 3}){sub 2}/GS2 presented the highest capacitance of 1200 F g{sup −1} at 4 A g{sup −1}. -- Abstract: In this work, a series of composites consisting of Ni(HCO{sub 3}){sub 2} and graphene nanosheets (GS) have been prepared by a facile solvothermal method, and then their application as electrode materials for supercapacitors has been investigated by cyclic voltammetry (CV) and galvanostatic charge–discharge tests. Morphological and structural analyses by field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy indicated that Ni(HCO{sub 3}){sub 2} particles deposited on the GS and formed a loosely packed microstructure, actualizing the successful combination of Ni(HCO{sub 3}){sub 2} particles with GS. Among the prepared composites, the sample of Ni(HCO{sub 3}){sub 2}/GS2 exhibited the highest capacitance of 1200 F g{sup −1} at a current density of 4 A g{sup −1}, illustrating that such composite is a promising candidate as electrode material for supercapacitors. Moreover, the Faradic redox mechanism of the Ni(HCO{sub 3}){sub 2}/GS composite was further studied in virtue of XRD analysis, which revealed that the Ni(HCO{sub 3}){sub 2} phase could be quickly transformed into Ni(OH){sub 2} phase by an electrochemically induced phase transformation process during the galvanostatic charge–discharge tests.

Hydro- and solvothermally-prepared ZnO and its catalytic effect on photodegradation of reactive orange 16 dye

Directory of Open Access Journals (Sweden)

Simović Bojana

2014-01-01

Full Text Available In this work, zinc oxide powders were obtained by two different techniques: hydro- and solvothermal synthesis starting from Zn(NO32 and Zn(CH3COO2, respectively. The influence of synthetic procedure on the structural, microstructural, thermal and photocatalytic properties of the prepared ZnO powders was investigated. Both ZnO samples were further annealed at moderate conditions (300°C to avoid grain growth and to remove traces of impurities. In all four cases a single-phase hexagonal ZnO was confirmed by X-ray powder diffraction. The morphology of prepared ZnO powders was different and it varied from rounded nanograins to microrods. All prepared samples showed higher photocatalytic efficiency in degradation of textile azo-dye Reactive Orange 16(RO16 than the commercial ZnO. In addition, the non-annealed samples had better photocatalytic properties than the commercial Degussa P25 TiO2 powder. [Projekat Ministarstva nauke Republike Srbije, br. III45007, br. ON171032 i br. ON172013

Solvothermal synthesis of size-tunable ZnFe{sub 2}O{sub 4} colloidal nanocrystal assemblies and their electrocatalytic activity towards hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Liu, Ruirui, E-mail: liurui1114@outlook.com; Lv, Meng, E-mail: lm199133@126.com; Wang, Qianbin, E-mail: material_wqb@163.com; Li, Hongliang, E-mail: lhl@qdu.edu.cn; Guo, Peizhi, E-mail: pzguo@qdu.edu.cn; Zhao, X.S., E-mail: chezxs@qdu.edu.cn

2017-02-15

Three ZnFe{sub 2}O{sub 4} colloidal nanocrystal assemblies (CNAs), namely CNA1, CNA2 and CNA3, have been synthesized solvothermally with the size of 560 nm, 460 nm and 330 nm and are formed by the self-assembly of primary nanocrystals with the crystallite sizes of 19.2 nm, 15.5 nm and 21.8 nm, respectively. It was found that CNA2 performed superparamagnetic behavior with a saturation magnetization value of 36.9 emu g{sup −1} while either CNA1 or CNA3 exhibited weak ferromagnetic with a small hysteresis loop and large saturation magnetization. Electrochemical sensing measurements toward the reduction of hydrogen peroxide showed that the peak currents of the CNAs in cyclic voltammograms showed a linear relationship with the concentration of hydrogen peroxide in the experimental conditions and the peak potentials were increased with the order of CNA3, CNA2 and CNA1. The formation mechanism of ZnFe{sub 2}O{sub 4} CNAs had been discussed based on the experimental data. The magnetism and electrocatalysis of the ZnFe{sub 2}O{sub 4} CNAs were supposed to be dependent on the size of primary nanoparticles and the structure of the CNAs. - Highlights: • Size-tunable ZnFe{sub 2}O{sub 4} colloidal nanocrystal assemblies were synthesized solvothermally. • Magnetic properties of ZnFe{sub 2}O{sub 4} assemblies are depended on the size and self-assembly of primary nanoparticles. • Electrocatalytic activity of ZnFe{sub 2}O{sub 4} assemblies is determined by their structure.

Large-scale solvothermal synthesis of fluorescent carbon nanoparticles

International Nuclear Information System (INIS)

Ku, Kahoe; Park, Jinwoo; Kim, Nayon; Kim, Woong; Lee, Seung-Wook; Chung, Haegeun; Han, Chi-Hwan

2014-01-01

The large-scale production of high-quality carbon nanomaterials is highly desirable for a variety of applications. We demonstrate a novel synthetic route to the production of fluorescent carbon nanoparticles (CNPs) in large quantities via a single-step reaction. The simple heating of a mixture of benzaldehyde, ethanol and graphite oxide (GO) with residual sulfuric acid in an autoclave produced 7 g of CNPs with a quantum yield of 20%. The CNPs can be dispersed in various organic solvents; hence, they are easily incorporated into polymer composites in forms such as nanofibers and thin films. Additionally, we observed that the GO present during the CNP synthesis was reduced. The reduced GO (RGO) was sufficiently conductive (σ ≈ 282 S m −1 ) such that it could be used as an electrode material in a supercapacitor; in addition, it can provide excellent capacitive behavior and high-rate capability. This work will contribute greatly to the development of efficient synthetic routes to diverse carbon nanomaterials, including CNPs and RGO, that are suitable for a wide range of applications. (paper)

Hexagonal-layered Na{sub 0.7}MnO{sub 2.05} via solvothermal synthesis as an electrode material for aqueous Na-ion supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Hou, Yan; Tang, Hongwei; Li, Bao; Chang, Kun [Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007 (China); Chang, Zhaorong, E-mail: czr_56@163.com [Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007 (China); Yuan, Xiao-Zi; Wang, Haijiang [National Research Council of Canada, V6T 1W5, Vancouver, BC (Canada)

2016-03-01

The layered sodium manganese oxides Na{sub 0.7}MnO{sub 2.05} material was synthesized using Na{sub 2}CO{sub 3} and Mn{sub 3}O{sub 4} precursors via a solvothermal method at different temperatures. The X-ray diffraction (XRD) shows that the Na{sub 0.7}MnO{sub 2.05} sample has a high crystallinity with hexagonal crystal system. The electrochemical performance was characterized by cyclic voltammetry (CV), impedance measurements and galvanostatic charge–discharge tests in symmetric Na-ion supercapacitors with 1 mol L{sup −1} Na{sub 2}SO{sub 4} solution as electrolyte. The Na{sub 0.7}MnO{sub 2.05} material shows a high specific capacity of about 162.5 F g{sup −1} at a current density of 50 mA g{sup −1} and a high coulombic efficiency approaching 100%. Even at a current density of 200 mA g{sup −1}, the discharge capacity of the material can reach to 146 F g{sup −1}. This electrode material holds great promise for practical applications. - Highlights: • Novel electrode material for supercapacitor: hexagonal-layered Na{sub 0.7}MnO{sub 2.05}. • Na{sub 0.7}MnO{sub 2.05} is synthesized using Mn{sub 3}O{sub 4} precursors via solvothermal method. • Obtained Na{sub 0.7}MnO{sub 2.05} exhibits superior electrochemical performance.

Solvothermally synthesized europium-doped CdS nanorods: applications as phosphors

International Nuclear Information System (INIS)

Kumar, Sunil; Jindal, Zinki; Kumari, Nitu; Verma, Narendra Kumar

2011-01-01

To exploit the photoluminescent behavior of CdS at nanoscale with different doping concentration of europium—a rare earth element, we report the synthesis of Eu-doped CdS nanorods by using low temperature solvothermal process by using ethylenediamine. The outcomes can have future applications as phosphors, photovoltaic cells, lasers, light emitting diodes, bio-imaging, and sensors. The doping was confirmed by electron dispersive spectroscopy supported by X-ray diffraction. From scanning electron microscopy and transmission electron microscopy analysis it was observed that the average diameter of the Cd 1−x Eu x S nanorods is about 10–12 nm having lengths in the range of 50–100 nm. UV–Visible spectroscopy study was carried out to determine the band gap of the nanorods and the absorbance peaks showed blue shift with respect to the bulk CdS. The blue shift was also observed as the doping concentration of Eu increases. From photoluminescence (PL) studies at λ ex = 450 nm, peaks at 528 and 540 nm were observed due to CdS, peak at 570 nm is due to defects related transitions, while the peak at 613 nm is due to Eu. As the doping concentration of Eu is increased the intensity of the luminescent peak at 613 nm is increased. Thermogravimetric analysis showed the nanorods are thermally stable up to 300 °C. The traces of impurities adsorbed on the nanorods were confirmed by Fourier transform infrared spectroscopy.

Review on the progress in synthesis and application of magnetic carbon nanocomposites

Science.gov (United States)

Zhu, Maiyong; Diao, Guowang

2011-07-01

This review focuses on the synthesis and application of nanostructured composites containing magnetic nanostructures and carbon-based materials. Great progress in fabrication of magnetic carbon nanocomposites has been made by developing methods including filling process, template-based synthesis, chemical vapor deposition, hydrothermal/solvothermal method, pyrolysis procedure, sol-gel process, detonation induced reaction, self-assembly method, etc. The applications of magnetic carbon nanocomposites expanded to a wide range of fields such as environmental treatment, microwave absorption, magnetic recording media, electrochemical sensor, catalysis, separation/recognization of biomolecules and drug delivery are discussed. Finally, some future trends and perspectives in this research area are outlined.

Rapid synthesis of zeolitic imidazolate framework-8 (ZIF-8) nanocrystals in an aqueous system

KAUST Repository

Pan, Yichang; Liu, Yunyang; Zeng, Gaofeng; Zhao, Lan; Lai, Zhiping

2011-01-01

We report here the first example of ZIF materials synthesized in aqueous solution. The synthesis was performed at room temperature and typically took several minutes compared to hours and days in non-aqueous conditions. The obtained product were ZIF-8 nanocrystals having size of ∼85 nm and showed excellent thermal, hydrothermal and solvothermal stabilities. © 2011 The Royal Society of Chemistry.

Solvothermal Synthesis of Hierarchical Colloidal Nanocrystal Assemblies of ZnFe₂O₄ and Their Application in Water Treatment.

Science.gov (United States)

Guo, Peizhi; Lv, Meng; Han, Guangting; Wen, Changna; Wang, Qianbin; Li, Hongliang; Zhao, Xiusong

2016-09-29

Hierarchical colloidal nanocrystal assemblies (CNAs) of ZnFe₂O₄ have been synthesized controllably by a solvothermal method. Hollow ZnFe₂O₄ spheres can be formed with the volume ratios of ethylene glycol to ethanol of 1:4 in the starting systems, while solid ZnFe₂O₄ CNAs are obtained by adjusting the volume proportion of ethylene glycol to ethanol from 1:2 to 2:1. Magnetometric measurement data showed that the ZnFe₂O₄ CNAs obtained with the volume ratios of 1:2 and 1:1 exhibited weak ferromagnetic behavior with high saturation magnetization values of 60.4 and 60.3 emu·g -1 , respectively. However, hollow spheres showed a saturation magnetization value of 52.0 emu·g -1 , but the highest coercivity among all the samples. It was found that hollow spheres displayed the best ability to adsorb Congo red dye among all the CNAs. The formation mechanisms of ZnFe₂O₄ CNAs, as well as the relationship between their structure, crystallite size, and properties were discussed based on the experimental results.

Effect of solvent medium on the structural, morphological and optical properties of ZnS nanoparticles synthesized by solvothermal route

Energy Technology Data Exchange (ETDEWEB)

Mendil, R., E-mail: radia.mendil@yahoo.fr [Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l' Environnement, Université de Gabès, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Ben Ayadi, Z. [Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l' Environnement, Université de Gabès, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Djessas, K. [Laboratoire Procédés, Matériaux et Energie Solaire (PROMES-CNRS), TECNOSUD, Rambla de la thermodynamique, 66100 Perpignan (France); Université de Perpignan Via Domitia, 52 avenue Paul Alduy, 68860, Perpignan Cedex9 (France)

2016-09-05

Different morphologies of ZnS have been synthesized by a facile solvothermal approach in a mixed solvent made of Ethylenediamine (EN) and distilled water. The effect of solvent medium on the structural, morphological and optical properties of ZnS nanoparticles were investigated. The formation mechanism of different morphologies was proposed based on the experiment results. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), Raman spectroscopy and UV-Vis-IR spectrophotometer. The results show that phase transformation is easily induced and there is a strong correlation between morphology and structure of the ZnS nanocrystals by changing the solvent. The results also show that we have successfully produced hexagonal phase ZnS nanorods with mixed solvent. The grain sizes in the range of 17–22 nm were obtained according to elaboration conditions. Raman spectra show the intense peak at 346 cm{sup −1}, which is a typical Raman peak of bulk ZnS crystal, no signature of secondary phases. The band gap of ZnS increased from 3.49 to 3.74 eV with an increase in the EN composition in the solvent, implying that the optical properties of these materials are clearly affected by the synthesis medium. - Highlights: • ZnS was prepared at low temperature using solvothermal method. • The phase transformation and shape evolution processes were studied. • The role of solvent (EN/W) has been discussed for formation of ZnS nanostructures with different morphology. • The properties and growth mechanism of ZnS nanoparticles were investigated. • Optical band gap of ZnS powder were investigated using UV vis spectroscopy.

Solvothermal synthesis, characterization and optical properties of ZnO, ZnO-MgO and ZnO-NiO, mixed oxide nanoparticles

International Nuclear Information System (INIS)

Aslani, Alireza; Arefi, Mohammad Reza; Babapoor, Aziz; Amiri, Asghar; Beyki-Shuraki, Khalil

2011-01-01

ZnO-MgO and ZnO-NiO mixed oxides nanoparticles were produced from a solution containing Zinc acetate, Mg and Ni nitrate by Solvothermal method. The calcination process of the ZnO-MgO and ZnO-NiO composites nanoparticles brought forth polycrystalline two-phase ZnO-MgO and ZnO-NiO nanoparticles of 40-80 nm in diameters. ZnO, MgO and NiO were crystallized into wuertzite and rock salt structures, respectively. The optical properties of ZnO-MgO and ZnO-NiO nanoparticles were obtained by solid state UV and solid state florescent. The XRD, SEM and Raman spectroscopies of these nanoparticles were analyzed.

Solvothermal synthesis, characterization and optical properties of ZnO, ZnO-MgO and ZnO-NiO, mixed oxide nanoparticles

Science.gov (United States)

Aslani, Alireza; Arefi, Mohammad Reza; Babapoor, Aziz; Amiri, Asghar; Beyki-Shuraki, Khalil

2011-03-01

ZnO-MgO and ZnO-NiO mixed oxides nanoparticles were produced from a solution containing Zinc acetate, Mg and Ni nitrate by Solvothermal method. The calcination process of the ZnO-MgO and ZnO-NiO composites nanoparticles brought forth polycrystalline two-phase ZnO-MgO and ZnO-NiO nanoparticles of 40-80 nm in diameters. ZnO, MgO and NiO were crystallized into würtzite and rock salt structures, respectively. The optical properties of ZnO-MgO and ZnO-NiO nanoparticles were obtained by solid state UV and solid state florescent. The XRD, SEM and Raman spectroscopies of these nanoparticles were analyzed.

Solvothermal synthesis, characterization and optical properties of ZnO, ZnO-MgO and ZnO-NiO, mixed oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Aslani, Alireza, E-mail: a.aslani@vru.ac.ir [Department of Chemistry, Faculty of Science, Vali-E-Asr University of Rafsanjan, Rafsanjan, PO Box: 77176 (Iran, Islamic Republic of); Arefi, Mohammad Reza [Islamic Azad University, Yazd Brunch, Young researchers Club, Yazd (Iran, Islamic Republic of); Babapoor, Aziz [Department of Chemical Engineering, Ahar Branch, Islamic Azad University, Ahar, PO Box: 54516 (Iran, Islamic Republic of); Amiri, Asghar; Beyki-Shuraki, Khalil [Department of Chemistry, Faculty of Science, Vali-E-Asr University of Rafsanjan, Rafsanjan, PO Box: 77176 (Iran, Islamic Republic of)

2011-03-15

ZnO-MgO and ZnO-NiO mixed oxides nanoparticles were produced from a solution containing Zinc acetate, Mg and Ni nitrate by Solvothermal method. The calcination process of the ZnO-MgO and ZnO-NiO composites nanoparticles brought forth polycrystalline two-phase ZnO-MgO and ZnO-NiO nanoparticles of 40-80 nm in diameters. ZnO, MgO and NiO were crystallized into wuertzite and rock salt structures, respectively. The optical properties of ZnO-MgO and ZnO-NiO nanoparticles were obtained by solid state UV and solid state florescent. The XRD, SEM and Raman spectroscopies of these nanoparticles were analyzed.

Large scale solvothermal synthesis and a strategy to obtain stable Langmuir–Blodgett film of CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Thampi, Arya; Babu, Keerthi; Verma, Seema, E-mail: sa.verma@iiserpune.ac.in

2013-07-05

Highlights: • Large scale, monodisperse CoFe{sub 2}O{sub 4} nanoparticles by solvothermal route. • LB technique to obtain stable film of CoFe{sub 2}O{sub 4} nanoparticles over a large area. • Hydrophobicity of substrate was enhanced utilizing LB films of cadmium arachidate. • P–A isotherm and AFM cross sectional height profile analysis confirms stability. • Large scale organization of nanoparticles for surface pressure higher than 15 mN/m. -- Abstract: Nearly monodisperse oleic acid coated cobalt ferrite nanoparticles were synthesized in large scale by a simple solvothermal method utilizing N-methyl 2-Pyrrolidone (NMP) as a high boiling solvent. The magnetic oxide was further investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Langmuir–Blodgett (LB) technique is discussed to obtain a 2D assembly of oleic acid coated CoFe{sub 2}O{sub 4} nanoparticles over a large area. We describe a method to obtain stable, condensed three layers of cadmium arachidate on a piranha treated glass substrate. The hydrophobic surface thus obtained was subsequently used for forming a stable monolayer of oleic acid stabilized cobalt ferrite nanoparticles at the air–water interface. The stability of the LB films at the air–water interface was studied by pressure–area isotherm curves and atomic force microscopy (AFM) cross sectional height profile analysis. 2D organization of the magnetic nanoparticles at different surface pressures was studied by TEM. Preparation of large area LB films of CoFe{sub 2}O{sub 4} nanoparticles is reported for a surface pressure more than 15 mN/m.

Facile solvothermal synthesis of monodisperse Pt2.6Co1 nanoflowers with enhanced electrocatalytic activity towards oxygen reduction and hydrogen evolution reactions

International Nuclear Information System (INIS)

Jiang, Liu-Ying; Lin, Xiao-Xiao; Wang, Ai-Jun; Yuan, Junhua; Feng, Jiu-Ju; Li, Xin-Sheng

2017-01-01

Highlights: • Uniform Pt 2.6 Co 1 nanoflowers were prepared by a simple solvothermal method. • Glucose and CTAC were used as the green reductant and structure director, respectively. • The architectures had the enlarged ECSA. • The architectures exhibited excellent catalytic performances for HER in acid and alkaline media. • The architectures showed highly catalytic performances for ORR in acid media. - Abstract: Herein, uniform Pt 2.6 Co 1 nanoflowers (NFs) were synthesized in oleylamine by a one-pot solvothermal method, using cetyltrimethylammonium chloride (CTAC) and glucose as the capping agent and green reducing agent. The samples were mainly characterized by transmission electron microscopy (TEM), high angle annular dark-field scanning TEM (HAADF-STEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The architectures had larger electrochemically active surface area (ECSA) of 23.84 m 2 g −1 Pt than Pt 1.2 Co 1 nanocrystals (NCs, 14.96 m 2 g −1 Pt ), Pt 3.7 Co 1 NCs (16.96 m 2 g −1 Pt ) and commercial Pt black (20.35 m 2 g −1 Pt ). And the as-obtained Pt 2.6 Co 1 catalyst displayed superior catalytic performance and better durability for hydrogen evolution reaction (HER) as compared to Pt 1.2 Co 1 NCs, Pt 3.7 Co 1 NCs, commercial 50% Pt/C and Pt black catalysts in acid and alkaline media. Meanwhile, the electrocatalytic performance of Pt 2.6 Co 1 NFs for oxygen reduction reaction (ORR) is better in acid media as compared with that in alkaline media. It indicates the great potential applications of the as-prepared catalyst in fuel cells.

Synthesis of monodisperse MFe{sub 2}O{sub 4} (M = Fe and Zn) nanoparticles for polydiethylsiloxane-based ferrofluid with a solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Zhuang, Lin, E-mail: stszhl@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Zhang, Yong [Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Shen, Hui [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

2015-09-15

Highlights: • MFe{sub 2}O{sub 4} nanoparticles were synthesized through a facile solvothermal method. • The relationship between viscosity and temperature of the polydiethylsiloxane-based ferrofluid is discussed. • Fe{sub 3}O{sub 4} nanoparticles have a saturation magnetization of 73.06 emu/g at room temperature. - Abstract: Monodisperse MFe{sub 2}O{sub 4} (M = Fe, Zn) nanoparticles were successfully synthesized for the application of polydiethylsiloxane-based (PDES) ferrofluids (FFs) via a novel solvothermal method, with which 1-octanol and 1-octanamine act as binary solvent, oleic acid (OA) as the surfactant and metal acetylacetonate [M(acac){sub 3}](M = Fe and Zn) as the metal source. X-ray diffractometer confirms that the resultant nanoparticles are pure MFe{sub 2}O{sub 4} with a spinel structure. Infrared spectroscopy indicates that oleic acid is bound to the surface of MFe{sub 2}O{sub 4} through a covalent bond between carboxylate (COO{sup −}) and metal cations. The ratio of 1-octanol and 1-octanamine plays a key role in the formation of the sphere-shaped morphology. Transmission electron microscopy (TEM) images confirm that the Fe{sub 3}O{sub 4} particles are of 4–11 nm with good monodispersity and a narrow size distribution. The saturation magnetization of Fe{sub 3}O{sub 4} nanoparticles with sizes of 7 nm can reach up to 73.06 emu/g. Polydiethylsiloxane-based (PDES) FFs show relatively smaller changes of the viscosity with low temperatures (from −7 to 20 °C) than the polydimethylsiloxane-based (PDMS) FFs. For FFs applications, the relationship between viscosity and temperature is also discussed.

Particle size-controllable microwave-assisted solvothermal synthesis of the high-voltage cathode material LiCoPO4 using water/ethylene glycol solvent blends

Science.gov (United States)

Ludwig, Jennifer; Haering, Dominik; Doeff, Marca M.; Nilges, Tom

2017-03-01

Particle size-tuned platelets of the high-voltage cathode material LiCoPO4 for Li-ion batteries have been synthesized by a simple one-step microwave-assisted solvothermal process using an array of water/ethylene glycol (EG) solvent mixtures. Particle size control was achieved by altering the concentration of the EG co-solvent in the mixture between 0 and 100 vol%, with amounts of 0-80 vol% EG producing single phase, olivine-type LiCoPO4. The particle sizes of the olivine materials were significantly reduced from about 1.2 μm × 1.2 μm × 500 nm (0 vol% EG) to 200 nm × 100 nm × 50 nm (80 vol% EG) with increasing EG content, while specific surface areas increased from 2 to 13 m2 g-1. The particle size reduction could mainly be attributed to the modified viscosities of the solvent blends. Owing to the soft template effect of EG, the crystals exhibited the smallest dimensions along the [010] direction of the Li diffusion pathways in the olivine crystal structure, resulting in enhanced lithium diffusion properties. The relationship between the synthesis, crystal properties and electrochemical performance was further elucidated, indicating that the electrochemical performances of the as-prepared materials mainly depend on the solvent composition and the respective particle size range. LiCoPO4 products obtained from reaction media with low and high EG contents exhibited good electrochemical performances (initial discharge capacities of 87-124 mAh g-1 at 0.1 C), whereas materials made from medium EG concentrations (40-60 vol% EG) showed the highest capacities and gravimetric energy densities (up to 137 mAh g-1 and 658 Wh kg-1 at 0.1 C), excellent rate capabilities, and cycle life.

Solvothermal synthesis of Zn1−xMnxO nanoparticles using oxalate precursor route: Optical and magnetic properties

Directory of Open Access Journals (Sweden)

Tokeer Ahmad

2017-05-01

Full Text Available Nanoparticles of Zn1−xMnxO (x = 0.022, 0.061 and 0.098 were synthesized by a modified solvothermal method through the oxalate precursor route. The precursors were characterized by TG/DTA analysis. Their kinetics has also been studied using the Freeman and Carroll method. The prepared oxide nanoparticles were investigated by powder X-ray diffraction (PXRD, transmission electron microscopy (TEM, optical and BET surface area studies. PXRD patterns were matched with hexagonal ZnO structure, however few impurity peaks of ZnMnO3 appeared. Reflectance measurements showed that Mn2+ is incorporated in the Zn matrix. The band gap decreases on increasing Mn concentration. The particle size decreases from 18 to 9 nm and the surface area increases (255.4–582.9 m2g−1 on increasing Mn concentration. All these solid solutions show paramagnetic behaviour with very weak antiferromagnetic interactions. The effective magnetic moment of these nanoparticles comes out to be 4.91, 4.77 and 4.18 μB/Mn2+.

Synthesis and Piezoelectric Properties of Li, Ca and Mn-codoped BaTiO3 by a Solvothermal Approach

International Nuclear Information System (INIS)

Kimura, T; Dong, Q; Yin, S; Sato, T; Hashimoto, T; Sasaki, A; Aisawa, S

2013-01-01

3 at.% Li-doped (Ba 1-x Ca x )(Ti 1-y Mn y )O 3 particles with the Ca 2+ mole fraction, x, of 0–0.09 and Mn mole fraction, y, of 0 and 0.0005 were synthesized by a solvothermal approach at 200°C. The products consisted of nanoparticles of 50–100 nm in diameter, and did not change very much depending on the amount of Li, Ca and Mn-codoping. The change in relative dielectric constant, Δε r , in around room temperature decreased by doping Ca 2+ , and the lowest Δε r (4.51%) could be realized at x value of 0.03. The mechanical quality factor, Q m , of 3 at.% Li-doped (Ba 0.97 Ca 0.03 )(Ti 0.9995 Mn 0.0005 )O 3 increased to 521, and Δε r decreased to 1.72%, while the piezoelectric constant, d 33 (234pC/N), and electromechanical coupling factor, k p (40.0%), did not change very much compared with 3 at.% Li-doped BaTiO 3

A strategy of combining SILAR with solvothermal process for In2S3 sensitized quantum dot-sensitized solar cells

International Nuclear Information System (INIS)

Yang, Peizhi; Tang, Qunwei; Ji, Chenming; Wang, Haobo

2015-01-01

Graphical abstract: - Highlights: • In 2 S 3 sensitized TiO 2 anode is prepared by combining SILAR with solvothermal process. • The deposition cycle in SILAR process has an impact on cell performances. • A promising conversion efficiency of 1.39% is obtained for the optimal device. • The cell performances are markedly increased compared with SILAR technique. - Abstract: Pursuit of an efficient strategy for quantum dot-sensitized photoanode has been a persistent objective for enhancing photovoltaic performances of quantum dot-sensitized solar cell (QDSC). We present here the fabrication of the indium sulfide (In 2 S 3 ) quantum dot-sensitized titanium dioxide (TiO 2 ) photoanode by combining successive ionic layer adsorption and reaction (SILAR) with solvothermal processes. The resultant QDSC consists of an In 2 S 3 sensitized TiO 2 photoanode, a liquid polysulfide electrolyte, and a Co 0.85 Se counter electrode. The optimized QDSC with photoanode prepared with the help of a SILAR method at 20 deposition cycles and solvothermal method yields a maximum power conversion efficiency of 1.39%.

The synthesis of porous Co{sub 3}O{sub 4} micro cuboid structures by solvothermal approach and investigation of its gas sensing properties and catalytic activity

Energy Technology Data Exchange (ETDEWEB)

Jamil, Saba, E-mail: saba_hrb@yahoo.com [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Jing, Xiaoyan [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Institute of Advanced Marine Materials, Harbin Engineering University, 150001 (China); Wang, Jun, E-mail: zhqw1888@sohu.com [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Li, Songnan; Liu, Jingyuan [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Zhang, Milin [Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001 (China); Institute of Advanced Marine Materials, Harbin Engineering University, 150001 (China)

2013-11-15

Graphical abstract: - Highlights: • Micro cuboid Co{sub 3}O{sub 4} particle prepared by solvothermal method. • Study of morphology of synthesized cuboids before and after calcinations. • Investigation of formation mechanism of porous Co{sub 3}O{sub 4} from cuboid CoCO{sub 3}. • Investigation of gas sensing properties of porous Co{sub 3}O{sub 4}. • Study of catalytic activity of product. - Abstract: The cobalt carbonate cuboids are prepared by adopting a simple solvothermal approach by using diethylene glycol and water in specific ratio as solvent. The prepared cobalt carbonate is subjected to different instrumentation to investigate its morphology and other properties. It is clear from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the product is distinct cuboid in shape with a size of approximately 3 μm from each face of the cube. Each particle of cuboid cobalt carbonate seems to comprise of layer by layer assembly of unit cells that consequently leads to a cuboid geometry. The cuboid cobalt carbonate was calcined at 700 °C in a furnace under argon atmosphere that decompose cobalt carbonate into porous Co{sub 3}O{sub 4} with the loosely packed arrangement of nano architectures. The gas sensing properties and catalytic activity of porous cuboids Co{sub 3}O{sub 4} are also investigated.

Low temperature synthesis and characterization of Na–M–(O)–F phases with M=Ti, V

Energy Technology Data Exchange (ETDEWEB)

Nava-Avendaño, Jessica [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Ayllón, José A. [Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Frontera, Carlos; Oró-Solé, Judith [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Estruga, Marc [Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Molins, Elies [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Palacín, M. Rosa, E-mail: rosa.palacin@icmab.es [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain)

2015-03-15

Na{sub 5}Ti{sub 3}O{sub 3}F{sub 11} was prepared by the microwave assisted method, and presents a chiolite related structure with cell parameters a=10.5016(5), b=10.4025(5), and c=10.2911(5) Å and Cmca (no. 64) space group. From solvothermal synthesis at 100 °C the cryolite Na{sub 3−δ}VO{sub 1−δ}F{sub 5+δ} was prepared, which crystallizes in the monoclinic system with a=5.5403(2), b=5.6804(2), c=7.9523(2) Å, β=90.032(7)° cell parameters and P2{sub 1}/n (no. 14) space group. Under similar synthesis conditions but with higher HF concentration the chiolite-type phase Na{sub 5−δ}V{sub 3}F{sub 14} was achieved, which exhibits a=10.5482(2), b=10.4887(1) and c=10.3243(1) Å cell parameters and Cmc2{sub 1} (no. 36) space group. A single crystal also having the chiolite structure was synthesized at 200 °C which exhibits tetragonal symmetry (a=7.380(3) and c=10.381(11) Å and space group P4{sub 2}2{sub 1}2 (no. 94)). Bond valence sum indicates that it contains V{sup 4+} and therefore can be formulated as Na{sub 5}V{sub 3}O{sub 3}F{sub 11}. - Graphical abstract: Na{sub 5}M{sub 3}(O,F){sub 14} with M=Ti and V having chiolite structure and Na{sub 3−δ}VO{sub 1−δ}F{sub 5+δ} cryolite were prepared by means of microwave-assisted and solvothermal synthesis. - Highlights: • Na{sub 5}Ti{sub 3}O{sub 3}F{sub 11} chiolite was prepared by a microwave assisted method and characterized. • Na{sub 3−δ}VO{sub 1−δ}F{sub 5+δ} and Na{sub 5−δ}V{sub 3}F{sub 14} were prepared by solvothermal synthesis. • The compounds were structurally characterized by diffraction techniques. • O/F distribution was estimated by applying Pauling’s second rule.

Solvothermal synthesis and characterisation of new one-dimensional indium and gallium sulphides: [C1N4H26]0.5[InS2] and [C1N4H26]0.5[GaS2

International Nuclear Information System (INIS)

Vaqueiro, Paz

2006-01-01

Two new main group metal sulphides, [C 1 N 4 H 26 ] 0.5 [InS 2 ] (1) and [C 1 N 4 H 26 ] 0.5 [GaS 2 ] (2) have been prepared solvothermally in the presence of 1,4-bis(3-aminopropyl)piperazine and their crystal structures determined by single-crystal X-ray diffraction. Both compounds are isostructural and crystallise in the monoclinic space group P2 1 /n (Z=4), with a=6.5628(5), b=11.2008(9), c=12.6611(9) A and β=94.410(4) o (wR=0.035) for compound (1) and a=6.1094(5), b=11.2469(9), c=12.7064(10) A and β=94.313(4) o (wR=0.021) for compound (2). The structure of [C 1 N 4 H 26 ] 0.5 [MS 2 ] (M=In,Ga) consists of one-dimensional [MS 2 ] - chains which run parallel to the crystallographic a axis and are separated by diprotonated amine molecules. These materials represent the first example of solvothermally prepared one-dimensional gallium and indium sulphides. -- Graphical abstract: [C 1 N 4 H 26 ] 0.5 [InS 2 ] and [C 1 N 4 H 26 ] 0.5 [GaS 2 ], prepared under solvothermal conditions, consist of one-dimensional [MS 2 ] - chains separated by diprotonated 1,4-bis(3-aminopropyl)piperazine molecules

Synthesis of Cu-Poor Copper-Indium-Gallium-Diselenide Nanoparticles by Solvothermal Route for Solar Cell Applications

Directory of Open Access Journals (Sweden)

Chung Ping Liu

2014-01-01

Full Text Available Copper-indium-gallium-diselenide (CIGS thin films were fabricated using precursor nanoparticle ink and sintering technology. The precursor was a Cu-poor quaternary compound with constituent ratios of Cu/(In+Ga=0.603, Ga/(In+Ga=0.674, and Se/(Cu+In+Ga=1.036. Cu-poor CIGS nanoparticles of chalcopyrite for solar cells were successfully synthesized using a relatively simple and convenient elemental solvothermal route. After a fixed reaction time of 36 h at 180°C, CIGS nanocrystals with diameters in the range of 20–70 nm were observed. The nanoparticle ink was fabricated by mixing CIGS nanoparticles, a solvent, and an organic polymer. Analytical results reveal that the Cu-poor CIGS absorption layer prepared from a nanoparticle-ink polymer by sintering has a chalcopyrite structure and a favorable composition. For this kind of sample, its mole ratio of Cu : In : Ga : Se is equal to 0.617 : 0.410 : 0.510 : 2.464 and related ratios of Ga/(In+Ga and Cu/(In+Ga are 0.554 and 0.671, respectively. Under the condition of standard air mass 1.5 global illumination, the conversion efficiency of the solar cell fabricated by this kind of sample is 4.05%.

Solvothermal synthesis of InP quantum dots and their enhanced luminescent efficiency by post-synthetic treatments.

Science.gov (United States)

Byun, Ho-June; Lee, Ju Chul; Yang, Heesun

2011-03-01

InP quantum dots (QDs) were solvothermally synthesized by using a greener phosphorus source of P(N(CH(3))(2))(3) instead of highly toxic P(TMS)(3) widely used, and subsequently subjected to a size-sorting processing. While as-grown QDs showed an undetectably low emission intensity, post-synthetic treatments such as photo-etching, photo-radiation, and photo-assisted ZnS shell coating gave rise to a substantial increase in emission efficiency due to the effective removal and passivation of surface states. The emission efficiency of the photo-etched QDs was further enhanced by a consecutive UV photo-radiation, attributable to the photo-oxidation at QD surface. Furthermore, a relatively thick ZnS shell on the surface of InP QDs that were surface-modified with hydrophilic ligands beforehand was photochemically generated in an aqueous solution at room temperature. The resulting InP/ZnS core/shell QDs, emitting from blue to red wavelengths, were more efficient than the above photo-treated InP QDs, and their luminescent properties (emission bandwidth and quantum yield) were comparable to those of InP QDs synthesized with P(TMS)(3). Structural, size, and compositional analyses on InP/ZnS QDs were also conducted to elucidate their core/shell structure. Copyright © 2010 Elsevier Inc. All rights reserved.

Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source.

Science.gov (United States)

Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun

2011-06-10

The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 °C for 24 h by using a P source of P(N(CH(3))(2))(3). The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source

International Nuclear Information System (INIS)

Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun

2011-01-01

The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 deg. C for 24 h by using a P source of P(N(CH 3 ) 2 ) 3 . The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source

Science.gov (United States)

Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun

2011-06-01

The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 °C for 24 h by using a P source of P(N(CH3)2)3. The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source

Energy Technology Data Exchange (ETDEWEB)

Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun, E-mail: hyang@hongik.ac.kr [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of)

2011-06-10

The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 deg. C for 24 h by using a P source of P(N(CH{sub 3}){sub 2}){sub 3}. The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Antifungal activity of gold nanoparticles prepared by solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

2013-01-15

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

Antifungal activity of gold nanoparticles prepared by solvothermal method

International Nuclear Information System (INIS)

Ahmad, Tokeer; Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna; Manzoor, Nikhat; Ahmad, Aijaz; Ahmed, Jahangeer; Al-Shihri, Ayed S.

2013-01-01

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m 2 /g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m 2/ g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl 2 and NaBH 4 as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl 2 , however, NaBH 4 produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m 2 /g for 7 nm and 269 m 2 /g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H + efflux of the Candida species than 15 nm sized gold nanoparticles.

Silent cries, dancing tears: the metapsychology of art revisited/revised.

Science.gov (United States)

Aragno, Anna

2011-04-01

Against the backdrop of a broad survey of the literature on applied psychoanalysis, a number of concepts underpinning the metapsychology of art are revisited and revised: sublimation; interrelationships between primary and secondary processes; symbolization; "fantasy"; and "cathexis." Concepts embedded in dichotomous or drive/energic contexts are examined and reformulated in terms of a continuum of semiotic processes. Freudian dream structure is viewed as a biological/natural template for nonrepressive artistic forms of sublimation. The synthesis presented proposes a model of continuous rather than discontinuous processes, in a nonenergic, biosemiotic metatheoretical framework.

Solvothermal synthesis of TiO2 nanocrystals with {001} facets using titanic acid nanobelts for superior photocatalytic activity

Science.gov (United States)

Cao, Yuhui; Zong, Lanlan; Li, Qiuye; Li, Chen; Li, Junli; Yang, Jianjun

2017-01-01

Anatase TiO2 nanocrystals exposed with {001} facets were fabricated by solvothermal strategy in HF-C4H9OH mixed solution, using titanic acid nanobelts (TAN) as a precursor. The shape of TAN is a long flat plane with a high aspect ratio, and F- is easily adsorbed on the surface of the nanobelts, inducing a higher exposure of {001} facet of TiO2 nanoparticles during the structure reorganization. The exposed percentage of {001} facets could vary from 40 to 77% by adjusting the amount of HF. The as-prepared samples were characterized by transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscope. The photocatalytic measurement showed that TiO2 nanocrystals with 77% {001} facets exhibited much superior photocatalytic activity for photodegradation of methyl orange, methylene blue, and rhodamine B. And what's more, the mineralization rate of methyl orange was as high as 96% within 60 min. The photocatalytic enhancement is due to a large amount of the high energetic {001} facets exposing, the special truncated octahedral morphology and a stronger ability for dyes adsorption.

Solvo-thermal in situ transesterification of wet spent coffee grounds for the production of biodiesel.

Science.gov (United States)

Park, Jeongseok; Kim, Bora; Son, Jeesung; Lee, Jae W

2018-02-01

This work addresses non-catalytic biodiesel production from spent coffee ground (SCG) by integrating solvo-thermal effect of 1,2-dichloroethane (DCE) with in situ transesterification over 160 °C. The SCG water content has a positive effect on the DCE hydrolysis up to 60 wt% due to the bimolecular substitution mechanism. The hydrolysis gives an acidic environment favorable for cellulose decomposition, SCG particle size reduction and lipid conversion. The optimal fatty acid ethyl ester yield was 11.8 wt% based on the mass of dried SCG with 3.36 ml ethanol and 3.16 ml DCE at 196.8 °C through the response surface methodology. Using the solvo-thermal effect, direct utilization of wet SCG as a biodiesel feedstock provides not only economic feasibility without using drying process and additional acid catalyst but also environmental advantage of recycling the municipal waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

Self-assembly of Fe3O4 nanocrystal-clusters into cauliflower-like architectures: Synthesis and characterization

International Nuclear Information System (INIS)

Zhu Luping; Liao Guihong; Bing Naici; Wang Linlin; Xie Hongyong

2011-01-01

Large-scale cauliflower-like Fe 3 O 4 architectures consist of well-assembled magnetite nanocrystal clusters have been synthesized by a simple solvothermal process. The as-synthesized Fe 3 O 4 samples were characterized by XRD, XPS, FT-IR, SEM, TEM, etc. The results show that the samples exhibit cauliflower-like hierarchical microstructures. The influences of synthesis parameters on the morphology of the samples were experimentally investigated. Magnetic properties of the Fe 3 O 4 cauliflower-like hierarchical microstructures have been detected by VSM at room temperature, showing a relatively low saturation magnetization of 65 emu/g and an enhanced coercive force of 247 Oe. - Graphical Abstract: Cauliflower-like Fe 3 O 4 architectures consist of well-assembled magnetite nanocrystal clusters have been synthesized by a simple solvothermal process, using FeCl 3 .6H 2 O and EDA as the starting materials. Highlights: → Cauliflower-like Fe 3 O 4 architectures were successfully prepared by a simple solvothermal route. → The cauliflower-like Fe 3 O 4 architectures have a size in the range of 200-300 nm. → They show a low saturation magnetization of 65 emu/g and an enhanced coercive force of 247 Oe. → These Fe 3 O 4 architectures may have potential applications in catalysis and biological fields.

Surface-roughness-assisted formation of large-scale vertically aligned CdS nanorod arrays via solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Zhou, Minmin [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yan, Shancheng, E-mail: yansc@njupt.edu.cn [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Shi, Yi, E-mail: yshi@nju.edu.cn [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yang, Meng; Sun, Huabin; Wang, Jianyu; Yin, Yao; Gao, Fan [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

2013-05-15

Large-scale cadmium sulfide (CdS) nanorod arrays were successfully synthesized on several different substrates through solvothermal reaction. During the growth experiments, we observed that the adhesion strength of the CdS nanorod arrays to different substrates differed dramatically, causing some of the CdS coating being easily flushed away by deionized water (DI water). With doubts and suspicions, we seriously investigate the original morphology of all the substrates by using atomic force microscopy (AFM). The phase, morphology, crystal structure and photoelectric property of all the products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and current–voltage (I–V) probe station. The growth mechanism of solvothermal reaction was proposed on the basis of all the characterizations. Our approach presents a universal method of liquid phase epitaxy of 1D material on a wide range of substrates of any shape.

A strategy of combining SILAR with solvothermal process for In2S3 sensitized quantum dot-sensitized solar cells

Science.gov (United States)

Yang, Peizhi; Tang, Qunwei; Ji, Chenming; Wang, Haobo

2015-12-01

Pursuit of an efficient strategy for quantum dot-sensitized photoanode has been a persistent objective for enhancing photovoltaic performances of quantum dot-sensitized solar cell (QDSC). We present here the fabrication of the indium sulfide (In2S3) quantum dot-sensitized titanium dioxide (TiO2) photoanode by combining successive ionic layer adsorption and reaction (SILAR) with solvothermal processes. The resultant QDSC consists of an In2S3 sensitized TiO2 photoanode, a liquid polysulfide electrolyte, and a Co0.85Se counter electrode. The optimized QDSC with photoanode prepared with the help of a SILAR method at 20 deposition cycles and solvothermal method yields a maximum power conversion efficiency of 1.39%.

MIL-125-NH2@TiO2 Core-Shell Particles Produced by a Post-Solvothermal Route for High-Performance Photocatalytic H2 Production.

Science.gov (United States)

Zhang, Bingxing; Zhang, Jianling; Tan, Xiuniang; Shao, Dan; Shi, Jinbiao; Zheng, Lirong; Zhang, Jing; Yang, Guanying; Han, Buxing

2018-05-02

Metal-organic frameworks (MOFs) have proven to be an interesting class of sacrificial precursors of functional inorganic materials for catalysis, energy storage, and conversion applications. However, the controlled synthesis of MOF-derived materials with desirable compositions, structures, and properties still remains a big challenge. Herein, we propose a post-solvothermal route for the outer-to-inner loss of organic linkers from MOF, which is simple, rapid, and controllable and can be operated at temperature much lower than that of the commonly adopted pyrolysis method. By such a strategy, the MIL-125-NH 2 particles coated by TiO 2 nanosheets were produced, and the thickness of TiO 2 shell can be easily tuned. The MIL-125-NH 2 @TiO 2 core-shell particles combine the advantages of highly active TiO 2 nanosheets, MIL-125-NH 2 photosensitizer, plenty of linker defects and oxygen vacancies, and mesoporous structure, which allows them to be utilized as photocatalysts for the visible-light-driven hydrogen production reaction. It is remarkable that the hydrogen evolution rate by MIL-125-NH 2 @TiO 2 can be enhanced 70 times compared with the pristine MIL-125-NH 2 . Such a route can be easily applied to the synthesis of different kinds of MOF-derived functional materials.

Effect of Cu/In molar ratio on the microstructural and optical properties of microcrystalline CuInS2 prepared by solvothermal route

International Nuclear Information System (INIS)

Das, Kajari; Panda, Subhendu K.; Gorai, Soma; Mishra, Pratima; Chaudhuri, Subhadra

2008-01-01

Synthesis and characterization of CuInS 2 powder sample prepared by a simple and convenient solvothermal method is reported. The influence of the variation of Cu/In molar ratio from 0.69 to 1.25 on the particle morphology, crystal structure and optical properties of CuInS 2 samples was studied. The X-ray diffraction studies indicated that the samples were polycrystalline in nature. SEM images of the samples revealed that the copper-rich products were uniform microspheres with smooth surfaces, whereas microspheres formed by network of interconnected flakes were obtained for indium-rich products. The optical band gaps (E g ) of the products decreased from 1.60 to 1.43 eV with variation of Cu/In molar ratio. The variation of the Urbach tail width with Cu/In molar ratio indicated that the density of the defects is much higher for the indium-rich CuInS 2 , which was clearly revealed from Raman measurements

Preparation of weak-light-driven TiO2-based catalysts via adsorbed-layer nanoreactor synthesis and enhancement of their photo-degradation performance in seawater

Science.gov (United States)

Wang, Ting; Xu, Zhi-yong; Zhu, Yi-chen; Wu, Li-guang; Yuan, Hao-xuan; Li, Chang-chun; Liu, Ya-yu; Cai, Jing

2017-11-01

Graphene oxide (GO) was first employed as a support in preparing TiO2 nanoparticles by adsorbed-layer nanoreactor synthesis (ALNS). Both TiO2 crystallization and GO reduction simultaneously occurred during solvothermal treatment with alcohol as a solvent. By transmission electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy, the results showed that TiO2 nanoparticles with less than 10 nm of size distributed very homogeneously on the GO surface. Tight interaction between TiO2 particles and GO surface could effectively inhibit the aggregation of TiO2 particles, during solvothermal treatment for anatase TiO2 formation. Alcohol could also reduce oxygenated functional groups on GO surface after solvothermal treatment. TiO2 particles with small size and the decrease in oxygenated functional groups on the GO surface both caused high separation efficiency of photo-generated charge carriers, thus resulting in high photo-degradation performance of catalysts. Strong phenol adsorption on photocatalyst was key to enhancing photo-degradation efficiency for phenol in seawater. Moreover, the change in catalyst structure was minimal at different temperatures of solvothermal treatment. But, the degradation rate and efficiency for phenol in seawater were obviously enhanced because of the sensitive structure-activity relationship of catalysts under weak-light irradiation.

Solvothermal Synthesis of Hierarchical Colloidal Nanocrystal Assemblies of ZnFe2O4 and Their Application in Water Treatment

Directory of Open Access Journals (Sweden)

Peizhi Guo

2016-09-01

Full Text Available Hierarchical colloidal nanocrystal assemblies (CNAs of ZnFe2O4 have been synthesized controllably by a solvothermal method. Hollow ZnFe2O4 spheres can be formed with the volume ratios of ethylene glycol to ethanol of 1:4 in the starting systems, while solid ZnFe2O4 CNAs are obtained by adjusting the volume proportion of ethylene glycol to ethanol from 1:2 to 2:1. Magnetometric measurement data showed that the ZnFe2O4 CNAs obtained with the volume ratios of 1:2 and 1:1 exhibited weak ferromagnetic behavior with high saturation magnetization values of 60.4 and 60.3 emu·g−1, respectively. However, hollow spheres showed a saturation magnetization value of 52.0 emu·g−1, but the highest coercivity among all the samples. It was found that hollow spheres displayed the best ability to adsorb Congo red dye among all the CNAs. The formation mechanisms of ZnFe2O4 CNAs, as well as the relationship between their structure, crystallite size, and properties were discussed based on the experimental results.

Impact of concentration and Si doping on the properties and phase transformation behavior of nanocrystalline alumina prepared via solvothermal synthesis

International Nuclear Information System (INIS)

Mekasuwandumrong, Okorn; Tantichuwet, Panutin; Chaisuk, Choowong; Praserthdam, Piyasan

2008-01-01

Solvothermal reaction of 20 g aluminum isopropoxide (AIP) in mineral oil at 300 deg. C for 2 h gave χ-alumina showing high thermal stability while the reaction with higher amounts of starting AIP (30 and 40 g) contributed contamination of pseudoboehmite. The χ-alumina thus obtained directly transformed into α-alumina completely at approximately 1400 deg. C bypassing the other transition alumina phases whereas some part of the contaminated product transformed to γ-alumina through θ-alumina and finally α-alumina. When silicon was doped in the alumina matrix (5, 10, 20 and 50 at.%) using tetraethylorthosilicate as the silicon (Si) precursor, χ-alumina was still observed without any contaminations at low concentration doping (5-20 at.%). Amorphous structure was obtained by doping 50 at.% Si. The phase transformation temperature was shifted to the high temperature after loading the Si. The α-phase transformation did not go to completion even after calcinations at 1500 deg. C. This could be due to the incorporation of Si atom in alumina lattice forming SiO 2 -Al 2 O 3 solid solution

Capacitive and photocatalytic performance of Bi_2S_3 nanostructures synthesized by solvothermal method

International Nuclear Information System (INIS)

Liang, Kangqiang; Wang, Chenggang; Xu, Xijin; Leng, Jiancai; Ma, Hong

2017-01-01

Different Bi_2S_3 nanoarchitectures (nanorods and nanobelts) were successfully synthesized with a facile solvothermal method at different temperature. The nanobelts transformed into nanorods when the temperature was 200 °C increased from 150 °C. The nanorod-morphology was kept even the temperature was further increased. The galvanostatic charge/discharge performance showed that the prepared Bi_2S_3 nanorods had good performance of discharge efficiency at current density from 1 A g"−"1 to 4 A g"−"1. The specific capacitance was 270 F g"−"1 at a current density of 1 A g"−"1. Furthermore, the nanorods were also used as the efficient UV-light photocatalysts for the degradation of Rhodamine B (RhB), which showed almost complete degradation (∼87%) of RhB dye at 100 min. - Highlights: • Bi_2S_3 nanorods were successfully synthesized with a facile solvothermal method. • The specific capacitance can be 270 F g"−"1 at a current density of 1 A g"−"1. • 87% of RhB dye can be degraded at 100 min.

[Cu(I)(bpp)]BF4: the first extended coordination network prepared solvothermally in an ionic liquid solvent.

Science.gov (United States)

Jin, Kun; Huang, Xiaoying; Pan, Long; Li, Jing; Appel, Aaron; Wherland, Scot; Pang, Long

2002-12-07

Use of an ionic liquid [bmim][BF4] (bmim = 1-butyl-3-methylimidazolium) as solvent has resulted in the first extended coordination structure, the two-dimensional network [Cu(bpp)]BF4 [bpp = 1,3-bis(4-pyridyl)propane], produced via a solvothermal route.

A strategy of combining SILAR with solvothermal process for In{sub 2}S{sub 3} sensitized quantum dot-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Yang, Peizhi, E-mail: pzhyang@hotmail.com [Key Laboratory of Advanced Technique & Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming 650500 (China); Tang, Qunwei, E-mail: tangqunwei@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Ji, Chenming; Wang, Haobo [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China)

2015-12-01

Graphical abstract: - Highlights: • In{sub 2}S{sub 3} sensitized TiO{sub 2} anode is prepared by combining SILAR with solvothermal process. • The deposition cycle in SILAR process has an impact on cell performances. • A promising conversion efficiency of 1.39% is obtained for the optimal device. • The cell performances are markedly increased compared with SILAR technique. - Abstract: Pursuit of an efficient strategy for quantum dot-sensitized photoanode has been a persistent objective for enhancing photovoltaic performances of quantum dot-sensitized solar cell (QDSC). We present here the fabrication of the indium sulfide (In{sub 2}S{sub 3}) quantum dot-sensitized titanium dioxide (TiO{sub 2}) photoanode by combining successive ionic layer adsorption and reaction (SILAR) with solvothermal processes. The resultant QDSC consists of an In{sub 2}S{sub 3} sensitized TiO{sub 2} photoanode, a liquid polysulfide electrolyte, and a Co{sub 0.85}Se counter electrode. The optimized QDSC with photoanode prepared with the help of a SILAR method at 20 deposition cycles and solvothermal method yields a maximum power conversion efficiency of 1.39%.

Key insights on the structural characterization of textured Er2O3–ZrO2 nano-oxides prepared by a surfactant-free solvothermal route

International Nuclear Information System (INIS)

Julián-López, Beatriz; Luz, Verónica de la; Gonell, Francisco; Cordoncillo, Eloisa; López-Haro, Miguel; Calvino, Jose J.; Escribano, Purificación

2012-01-01

Highlights: ► Structural resolution of fluorite vs. pyrochlore in small nanocrystals. ► Simple template-free solvothermal synthesis of Er 2 O 3 –ZrO 2 nanooxides. ► Good control over size, morphology and surface properties (280 m 2 g −1 ). - Abstract: Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er 2 O 3 –ZrO 2 oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 °C) with spherical morphology, and high surface area (∼280 m 2 g −1 ). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N 2 adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced that the material is constituted, irrespective of the temperature of the final calcination step, by an ensemble of randomly

Highly effective synthesis of a cobalt(ii) metal-organic coordination polymer by using continuous flow chemistry.

Science.gov (United States)

Gong, Chunhua; Zhang, Junyong; Zeng, Xianghua; Xie, Jingli

2016-12-20

The coordination polymer [Co 2 L 4 (H 2 O) 2 ]·CH 3 CN·H 2 O (HL = (E)-2-[2-(4-chlorophenyl)vinyl]-8-hydroxyquinoline) has been achieved with 95% yield by using an Asia flow synthesis system (chip reactor). Compared with the conventional batch-type methods such as diffusion, reflux and solvothermal reactions, higher yielding reactions carried out in a flow reactor have demonstrated that this technique is a powerful strategy to obtain coordination compounds.

Solution-phase synthesis of nanomaterials at low temperature

Science.gov (United States)

Zhu, Yongchun; Qian, Yitai

2009-01-01

This paper reviews the solution-phase synthesis of nanoparticles via some routes at low temperatures, such as room temperature route, wave-assisted synthesis (γ-irradiation route and sonochemical route), directly heating at low temperatures, and hydrothermal/solvothermal methods. A number of strategies were developed to control the shape, the size, as well as the dispersion of nanostructures. Using diethylamine or n-butylamine as solvent, semiconductor nanorods were yielded. By the hydrothermal treatment of amorphous colloids, Bi2S3 nanorods and Se nanowires were obtained. CdS nanowires were prepared in the presence of polyacrylamide. ZnS nanowires were obtained using liquid crystal. The polymer poly (vinyl acetate) tubule acted as both nanoreactor and template for the CdSe nanowire growth. Assisted by the surfactant of sodium dodecyl benzenesulfonate (SDBS), nickel nanobelts were synthesized. In addition, Ag nanowires, Te nanotubes and ZnO nanorod arrays could be prepared without adding any additives or templates.

Solvothermal preparation of nanocrystalline anatase containing TiO{sub 2} and TiO{sub 2}/SiO{sub 2} coating agents for application of photocatalytic treatments

Energy Technology Data Exchange (ETDEWEB)

Mahltig, B., E-mail: boris.mahltig@hs-niederrhein.de [University of Applied Sciences Niederrhein, Faculty of Textile and Clothing Technology, Webschulstrasse 31, D-41065 Moenchengladbach (Germany); Gesellschaft zur Foerderung von Medizin-, Bio- und Umwelttechnologien e.V., GMBU e.V., Postfach 520165, D-01317 Dresden (Germany); Gutmann, E. [Technische Universitaet Dresden, Institut fuer Strukturphysik, D-01062 Dresden (Germany); Meyer, D.C. [Technische Universitaet Dresden, Institut fuer Strukturphysik, D-01062 Dresden (Germany); Technische Universitaet Bergakademie Freiberg, Institut fuer Experimentelle Physik, D-09596 Freiberg (Germany)

2011-05-16

Research highlights: {yields} TiO{sub 2} and TiO{sub 2}/SiO{sub 2} materials prepared by a solvothermal sol-gel process. {yields} Photodecomposition with oxygen increases with increasing solvothermal process temperature. {yields} In presence of H{sub 2}O{sub 2} the dye decomposition is observed even without UV light illumination. {yields} The materials contain potential for cleaning waste water containing dye stuffs. - Abstract: This paper reports on TiO{sub 2} and TiO{sub 2}/SiO{sub 2} materials prepared by a sol-gel process under solvothermal conditions with process temperatures between 120 deg. C and 180 deg. C. Under the preparation conditions chosen, the formation of anatase crystallites starts at a process temperature of 160 deg. C, as observed by X-ray diffraction. From TiO{sub 2} and TiO{sub 2}/SiO{sub 2} sols coatings on viscose fabrics and powders have been prepared. The photoactivity of both materials - coated textiles and powders - is determined by the decomposition of the dye AcidOrange under UV light illumination. Significant dye decomposition is only observed for samples containing a high ratio of TiO{sub 2} and that are solvothermally prepared at 180 deg. C. In contrast, when the photoactivity is determined in presence of H{sub 2}O{sub 2} totally different results are obtained and the degree of AcidOrange decomposition is higher for most of the samples. Furthermore, in presence of H{sub 2}O{sub 2} the dye decomposition is observed even without UV light illumination. Especially samples prepared with the polymer Pluronic P123 under lower solvothermal process temperatures exhibit strong dye decomposition without illumination in presence of H{sub 2}O{sub 2}. Therefore, these materials could be of high interest for cleaning waste water containing dye stuffs from textile industry.

Solvothermal synthesis of NiAl double hydroxide microspheres on a nickel foam-graphene as an electrode material for pseudo-capacitors

International Nuclear Information System (INIS)

Momodu, Damilola; Bello, Abdulhakeem; Dangbegnon, Julien; Barzeger, Farshad; Taghizadeh, Fatimeh; Fabiane, Mopeli; Manyala, Ncholu; Johnson, A. T. Charlie

2014-01-01

In this paper, we demonstrate excellent pseudo-capacitance behavior of nickel-aluminum double hydroxide microspheres (NiAl DHM) synthesized by a facile solvothermal technique using tertbutanol as a structure-directing agent on nickel foam-graphene (NF-G) current collector as compared to use of nickel foam current collector alone. The structure and surface morphology were studied by X-ray diffraction analysis, Raman spectroscopy and scanning and transmission electron microscopies respectively. NF-G current collector was fabricated by chemical vapor deposition followed by an ex situ coating method of NiAl DHM active material which forms a composite electrode. The pseudocapacitive performance of the composite electrode was investigated by cyclic voltammetry, constant charge–discharge and electrochemical impedance spectroscopy measurements. The composite electrode with the NF-G current collector exhibits an enhanced electrochemical performance due to the presence of the conductive graphene layer on the nickel foam and gives a specific capacitance of 1252 F g −1 at a current density of 1 A g −1 and a capacitive retention of about 97% after 1000 charge–discharge cycles. This shows that these composites are promising electrode materials for energy storage devices

eWOM, Revisit Intention, Destination Trust and Gender

OpenAIRE

Abubakar, Abubakar Mohammed; Ilkan, Mustafa; Al-Tal, Raad Meshall; Eluwole, Kayode

2017-01-01

This article investigates the impact of eWOM on intention to revisit and destination trust, and the moderating role of gender in medical tourism industry. Result from structural equation modeling (n=240) suggests the following: (1) that eWOM influences intention to revisit and destination trust; (2) that destination trust influences intention to revisit; (3) that the impact of eWOM on intention to revisit is about 1.3 times higher in men; (4) that the impact of eWOM on destination trust is ab...

Key insights on the structural characterization of textured Er{sub 2}O{sub 3}-ZrO{sub 2} nano-oxides prepared by a surfactant-free solvothermal route

Energy Technology Data Exchange (ETDEWEB)

Julian-Lopez, Beatriz, E-mail: julian@qio.uji.es [Departamento de Quimica Inorganica y Organica, Universitat Jaume I, Avda. Vicente Sos Baynat s/n, 12071 Castellon (Spain); Luz, Veronica de la; Gonell, Francisco; Cordoncillo, Eloisa [Departamento de Quimica Inorganica y Organica, Universitat Jaume I, Avda. Vicente Sos Baynat s/n, 12071 Castellon (Spain); Lopez-Haro, Miguel; Calvino, Jose J. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Campus Rio San Pedro, Puerto Real, 11510 Cadiz (Spain); Escribano, Purificacion [Departamento de Quimica Inorganica y Organica, Universitat Jaume I, Avda. Vicente Sos Baynat s/n, 12071 Castellon (Spain)

2012-04-05

Highlights: Black-Right-Pointing-Pointer Structural resolution of fluorite vs. pyrochlore in small nanocrystals. Black-Right-Pointing-Pointer Simple template-free solvothermal synthesis of Er{sub 2}O{sub 3}-ZrO{sub 2} nanooxides. Black-Right-Pointing-Pointer Good control over size, morphology and surface properties (280 m{sup 2} g{sup -1}). - Abstract: Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er{sub 2}O{sub 3}-ZrO{sub 2} oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 Degree-Sign C) with spherical morphology, and high surface area ({approx}280 m{sup 2} g{sup -1}). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N{sub 2} adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced

Single-step solvothermal synthesis of mesoporous Ag-TiO2-reduced graphene oxide ternary composites with enhanced photocatalytic activity

Science.gov (United States)

Arif Sher Shah, Md. Selim; Zhang, Kan; Park, A. Reum; Kim, Kwang Su; Park, Nam-Gyu; Park, Jong Hyeok; Yoo, Pil J.

2013-05-01

With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction of AgNO3 and graphene oxide and the hydrolysis of titanium tetraisopropoxide were spontaneously performed in a mixed solvent system of ethylene glycol, N,N-dimethylformamide and a stoichiometric amount of water without resorting to the use of typical reducing agents. The nanocomposites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, along with different microscopic and spectroscopic techniques, enabling us to confirm the successful reduction of AgNO3 and graphite oxide to metallic Ag and reduced graphene oxide, respectively. Due to the highly facilitated electron transport of well distributed Ag nanoparticles, the synthesized ternary nanocomposite showed enhanced photocatalytic activity for degradation of rhodamine B dye under visible light irradiation.With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction

Synthesis and magnetic properties of superparamagnetic CoAs nanostructures

Science.gov (United States)

Desai, P.; Ashokaan, N.; Masud, J.; Pariti, A.; Nath, M.

2015-03-01

This article provides a comprehensive guide on the synthesis and characterization of superparamagnetic CoAs nanoparticles and elongated nanostructures with high blocking temperature, (TB), via hot-injection precipitation and solvothermal methods. Cobalt arsenides constitute an important family of magnetically active solids that find a variety of applications ranging from magnetic semiconductors to biomedical imaging. While the higher temperature hot-injection precipitation technique (300 °C) yields pure CoAs nanostructures, the lower temperature solvothermal method (200 °C) yields a mixture of CoAs nanoparticles along with other Co-based impurity phases. The synthesis in all these cases involved usage of triphenylarsine ((C6H5)3As) as the As precursor which reacts with solid Co2(CO)8 by ligand displacement to yield a single source precursor. The surfactant, hexadecylamine (HDA) further assists in controlling the morphology of the nanostructures. HDA also provides a basic medium and molten flux-like conditions for the redox chemistry to occur between Co and As at elevated temperatures. The influence of the length of reaction time was investigated by studying the evolution of product morphology over time. It was observed that while spontaneous nucleation at higher temperature followed by controlled growth led to the predominant formation of short nanorods, with longer reaction time, the nanorods were further converted to nanoparticles. The size of the nanoparticles obtained, was mostly in the range of 10-15 nm. The key finding of this work is exceptionally high coercivity in CoAs nanostructures for the first time. Coercivity observed was as high as 0.1 T (1000 Oe) at 2 K. These kinds of magnetic nanostructures find multiple applications in spintronics, whereas the superparamagnetic nanoparticles are viable for use in magnetic storage, ferrofluids and as contrast enhancing agents in MRI.

Solvothermal synthesis of nanocrystalline KTaO.sub.3./sub. : Effect of solvent dielectric constant

Czech Academy of Sciences Publication Activity Database

Makarova, Marina; Bykov, Pavlo; Drahokoupil, Jan; Čerňanský, Marian; Dlabáček, Zdeněk; Dejneka, Alexandr; Jastrabík, Lubomír; Trepakov, Vladimír

2012-01-01

Roč. 47, č. 7 (2012), s. 1798-1773 ISSN 0025-5408 R&D Projects: GA AV ČR KAN301370701; GA ČR GAP108/12/1941 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z10100520 Keywords : nanostructures * chemical synthesis * Raman spectroscopy * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.913, year: 2012

Solvothermal preparation of nano-β-HgS from a precursor, bis(dibenzyldithiocarbamato)mercury(II)

International Nuclear Information System (INIS)

Marimuthu, G.; Ramalingam, K.; Rizzoli, C.; Arivanandhan, M.

2012-01-01

A simple solvothermal method for the selective synthesis of β-HgS (meta cinnabar) nanoparticles in aqueous solutions is reported with bis(dibenzyldithiocarbamato)mercury(II) as the precursor. Crystal structure, size, morphology and composition of the products are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, high-resolution transmission electron microscopy (HRTEM), SAED and X-ray photoelectron spectroscopy (XPS). PXRD shows (111), (220), (200), (311), (222), (400), (331), (420) reflections characteristic of β-HgS. SEM micrographs display the spherical nature of the nano-β-HgS. EDX analysis showed the presence of Hg and S. HRTEM images indicate the spherical nature of the nanoparticles with their size in the range of 10–15 nm and the FFT pattern shows the crystalline nature of the spherical particles. The results are in agreement with those estimated from the XRD pattern. XPS signals observed at 162.6 and 162.8 eV are due to S2p 3/2 and S2p 1/2 electrons and the S2s was observed at 222.3 eV. The band gap of nano-β-HgS has been found to be 3.6 eV from the UV–visible spectral measurement. The blue-shifted band gap compared to the bulk HgS is a consequence of “size quantization” effect. A comprehensive characterization of the precursor by IR and single crystal X-ray crystallography shows the presence of HgS 4 coordination environment, with a distinct Hg–S bond asymmetry.

Capacitive and photocatalytic performance of Bi{sub 2}S{sub 3} nanostructures synthesized by solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Liang, Kangqiang, E-mail: liang_kangqiang@126.com [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Wang, Chenggang, E-mail: ujnsps_wangchg@163.com [School of Physics and Technology, University of Jinan, 336 West Road of Nan Xinzhuang, Jinan, 250022, Shandong Province (China); Xu, Xijin, E-mail: sps_xuxj@ujn.edu.cn [School of Physics and Technology, University of Jinan, 336 West Road of Nan Xinzhuang, Jinan, 250022, Shandong Province (China); Key Laboratory for Photonic and Electric Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin, 150025 (China); Leng, Jiancai, E-mail: jiancaileng@qlu.edu.cn [School of Science, Qilu University of Technology, Jinan 250353 (China); Ma, Hong, E-mail: mahong@sdnu.edu.cn [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)

2017-02-12

Different Bi{sub 2}S{sub 3} nanoarchitectures (nanorods and nanobelts) were successfully synthesized with a facile solvothermal method at different temperature. The nanobelts transformed into nanorods when the temperature was 200 °C increased from 150 °C. The nanorod-morphology was kept even the temperature was further increased. The galvanostatic charge/discharge performance showed that the prepared Bi{sub 2}S{sub 3} nanorods had good performance of discharge efficiency at current density from 1 A g{sup −1} to 4 A g{sup −1}. The specific capacitance was 270 F g{sup −1} at a current density of 1 A g{sup −1}. Furthermore, the nanorods were also used as the efficient UV-light photocatalysts for the degradation of Rhodamine B (RhB), which showed almost complete degradation (∼87%) of RhB dye at 100 min. - Highlights: • Bi{sub 2}S{sub 3} nanorods were successfully synthesized with a facile solvothermal method. • The specific capacitance can be 270 F g{sup −1} at a current density of 1 A g{sup −1}. • 87% of RhB dye can be degraded at 100 min.

Preparation of flower-like CuS by solvothermal method and its photodegradation and UV protection

Energy Technology Data Exchange (ETDEWEB)

Hu, Xiao-Sai; Shen, Yong, E-mail: shenyong@sues.edu.cn; Xu, Li-Hui; Wang, Li-Ming; Xing, Ya-Jun

2016-07-25

The flower-like CuS with hierarchical structures were synthesized by a solvothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, UV–vis optical absorption spectroscopy and thermogravimetric analysis (TGA) and ultraviolet transmittance analyzer labsphere were used to characterize the as-prepared products. The results of photocatalytic degradation of Methylene blue (MB) demonstrated that the as-prepared flower-like CuS possessed high photocatalytic performance in UV and visible range and its band gap was 1.45 eV. The degradation rate of MB by CuS with the absence of H{sub 2}O{sub 2} was 98.23% and 100% under xenon lamp and Mercury tungsten blended lamp for 30 min, respectively. And a new approach for ultraviolet (UV) protection of cotton fabrics treated by flower-like CuS microspheres was innovatively investigated and the results showed that flower-like CuS was a good UV resistant material. - Highlights: • The flower-like CuS was prepared via solvothermal method. • The as-prepared CuS showed better photodegradation of MB solution under visible region. • The cotton fabric treated by the obtained flower-like CuS was proved to have a potential application in anti-UV field.

Solvothermal synthesis of monodisperse LiFePO4 micro hollow spheres as high performance cathode material for lithium ion batteries.

Science.gov (United States)

Yang, Shiliu; Hu, Mingjun; Xi, Liujiang; Ma, Ruguang; Dong, Yucheng; Chung, C Y

2013-09-25

A microspherical, hollow LiFePO4 (LFP) cathode material with polycrystal structure was simply synthesized by a solvothermal method using spherical Li3PO4 as the self-sacrificed template and FeCl2·4H2O as the Fe(2+) source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the LFP micro hollow spheres have a quite uniform size of ~1 μm consisting of aggregated nanoparticles. The influences of solvent and Fe(2+) source on the phase and morphology of the final product were chiefly investigated, and a direct ion exchange reaction between spherical Li3PO4 templates and Fe(2+) ions was firstly proposed on the basis of the X-ray powder diffraction (XRD) transformation of the products. The LFP nanoparticles in the micro hollow spheres could finely coat a uniform carbon layer ~3.5 nm by a glucose solution impregnating-drying-sintering process. The electrochemical measurements show that the carbon coated LFP materials could exhibit high charge-discharge capacities of 158, 144, 125, 101, and even 72 mAh g(-1) at 0.1, 1, 5, 20, and 50 C, respectively. It could also maintain 80% of the initial discharge capacity after cycling for 2000 times at 20 C.

One-pot solvothermal synthesis of graphene wrapped rice-like ferrous carbonate nanoparticles as anode materials for high energy lithium-ion batteries

Science.gov (United States)

Zhang, Fan; Zhang, Ruihan; Feng, Jinkui; Ci, Lijie; Xiong, Shenglin; Yang, Jian; Qian, Yitai; Li, Lifei

2014-11-01

Well dispersed rice-like FeCO3 nanoparticles were produced and combined with reduced graphene oxide (RGO) via a one-pot solvothermal route. SEM characterization shows that rice-like FeCO3 nanoparticles are homogeneously anchored on the surface of the graphene nanosheets; the addition of RGO is helpful to form a uniform morphology and reduce the particle size of FeCO3 to nano-grade. As anode materials for lithium-ion batteries, the FeCO3/RGO nanocomposites exhibit significantly improved lithium storage properties with a large reversible capacity of 1345 mA h g-1 for the first cycle and a capacity retention of 1224 mA h g-1 after 50 cycles with a good rate capability compared with pure FeCO3 particles. The superior electrochemical performance of the FeCO3/RGO nanocomposite electrode compared to the pure FeCO3 electrode can be attributed to the well dispersed RGO which enhances the electronic conductivity and accommodates the volume change during the conversion reactions. Our study shows that the FeCO3/RGO nanocomposite could be a suitable candidate for high capacity lithium-ion batteries.

A template-free solvothermal synthesis and photoluminescence properties of multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres

Science.gov (United States)

Sang, Xiaotong; Xu, Guangxi; Lian, Jingbao; Wu, Nianchu; Zhang, Xue; He, Jiao

2018-06-01

The multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres were successfully synthesized via a template-free solvothermal route without the use of surfactant from commercially available Ln (NO3)3·6H2O (Ln = Gd, Tb and Eu), absolute ethanol, ethanediamine and sublimed sulfur as the starting materials. The phase, structure, particle morphology and photoluminescence (PL) properties of the as-obtained products were investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectra. The influence of synthetic time on phase, structure and morphology was systematically investigated and discussed. The possible formation mechanism depending on synthetic time t for the Gd2O2S phase has been presented. These results demonstrate that the Gd2O2S hollow spheres could be obtained under optimal condition, namely solvothermal temperature T = 220 °C and synthetic time t = 16 h. The as-obtained Gd2O2S sample possesses hollow sphere structure, which has a typical size of about 2.5 μm in diameter and about 0.5 μm in shell thickness. PL spectroscopy reveals that the strongest emission peak for the Gd2O2S:xTb3+ and the Gd2O2S:yEu3+ samples is located at 545 nm and 628 nm, corresponding to 5D4→7F5 transitions of Tb3+ ions and 5D0→7F2 transitions of Eu3+ ions, respectively. The quenching concentration of Tb3+ ions and Eu3+ ions is 7%. In the case of Tb3+ and Eu3+ co-doped samples, when the concentration of Tb3+ or Eu3+ ions is 7%, the optimum concentration of Eu3+ or Tb3+ ions is determined to be 1%. Under 254 nm ultraviolet (UV) light excitation, the Gd2O2S:7%Tb3+, the Gd2O2S:7%Tb3+,1%Eu3+ and the Gd2O2S:7%Eu3+ samples give green, yellow and red light emissions, respectively. And the corresponding CIE coordinates vary from (0.3513, 0.5615), (0.4120, 0.4588) to (0.5868, 0.3023), which is also well consistent with their luminous photographs.

Growth of ZnO nanoparticles from nanowhisker precursor with a simple solvothermal route

International Nuclear Information System (INIS)

Wang Chunlei; Wang Enbo; Shen Enhong; Gao Lei; Kang Zhenhui; Tian Chungui; Zhang Chao; Lan Yang

2006-01-01

Methods of preparing nanoparticles have long been a topic experiencing extensive investigation. Among those methods developed, using template or polymer and surfactant as capping reagents were often effective. However, obtaining nanoparticles in high amounts and high purity still remains an unresolved challenge. Here, a simple two-step solvothermal method without using any surfactant or coating reactant to prepare ZnO nanoparticles with high purity in large scale was developed. X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the as-prepared ZnO nanoparticles, and the formation process of the nanoparticles was discussed finally

Solvothermal synthesis of TiO{sub 2} nanocrystals with {001} facets using titanic acid nanobelts for superior photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Cao, Yuhui; Zong, Lanlan [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Li, Qiuye, E-mail: qiuyeli@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); Li, Chen; Li, Junli [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Yang, Jianjun, E-mail: yangjianjun@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China)

2017-01-01

Highlights: • TiO{sub 2} exposed with {001} facets were firstly prepared using TAN as Ti source. • The mineralization rate of MO on sample with 77% {001} facets was as high as 96%. • The superior photocatalytic activity was greatly due to {001} facets exposing. - Abstract: Anatase TiO{sub 2} nanocrystals exposed with {001} facets were fabricated by solvothermal strategy in HF-C{sub 4}H{sub 9}OH mixed solution, using titanic acid nanobelts (TAN) as a precursor. The shape of TAN is a long flat plane with a high aspect ratio, and F{sup −} is easily adsorbed on the surface of the nanobelts, inducing a higher exposure of {001} facet of TiO{sub 2} nanoparticles during the structure reorganization. The exposed percentage of {001} facets could vary from 40 to 77% by adjusting the amount of HF. The as-prepared samples were characterized by transmission electron microscopy, N{sub 2} adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscope. The photocatalytic measurement showed that TiO{sub 2} nanocrystals with 77% {001} facets exhibited much superior photocatalytic activity for photodegradation of methyl orange, methylene blue, and rhodamine B. And what’s more, the mineralization rate of methyl orange was as high as 96% within 60 min. The photocatalytic enhancement is due to a large amount of the high energetic {001} facets exposing, the special truncated octahedral morphology and a stronger ability for dyes adsorption.

Solvothermal synthesis of Mg-doped Li2FeSiO4/C nanocomposite cathode materials for lithium-ion batteries

Science.gov (United States)

Kumar, Ajay; Jayakumar, O. D.; Naik, V. M.; Nazri, G. A.; Naik, R.

Lithium transition metal orthosilicates, such as Li2FeSiO4 and Li2MnSiO4, as cathode material have attracted much attention lately due to their high theoretical capacity ( 330 mAh/g), low cost, and environmental friendliness. However, they suffer from poor electronic conductivity and slow lithium ion diffusion in the solid phase. Several cation-doped orthosilicates have been studied to improve their electrochemical performance. We have synthesized partially Mg-substituted Li2Mgx Fe1-x SiO4-C, (x = 0.0, 0.01, 0.02, and 0.04) nano-composites by solvothermal method followed by annealing at 600oC in argon flow. The structure and morphology of the composites were characterized by XRD, SEM and TEM. The surface area and pore size distribution were measured by using N2 adsorption/desorption curves. The electrochemical performance of the Li2MgxFe1-x SiO4-C composites was evaluated by Galvanostatic cycling against metallic lithium anode, electrochemical impedance spectroscopy, and cyclic voltammetry. Li2Mg0.01Fe0.99SiO4-C sample shows a capacity of 278 mAh/g (at C/30 rate in the 1.5-4.6 V voltage window) with an excellent rate capability and stability, compared to the other samples. We attribute this observation to its higher surface area, enhanced electronic conductivity and higher lithium ion diffusion coefficient.

Solution-based synthesis and design of late transition metal chalcogenide materials for oxygen reduction reaction (ORR).

Science.gov (United States)

Gao, Min-Rui; Jiang, Jun; Yu, Shu-Hong

2012-01-09

Late transition metal chalcogenide (LTMC) nanomaterials have been introduced as a promising Pt-free oxygen reduction reaction (ORR) electrocatalysts because of their low cost, good ORR activity, high methanol tolerance, and facile synthesis. Herein, an overview on the design and synthesis of LTMC nanomaterials by solution-based strategies is presented along with their ORR performances. Current solution-based synthetic approaches towards LTMC nanomaterials include a hydrothermal/solvothermal approach, single-source precursor approach, hot-injection approach, template-directed soft synthesis, and Kirkendall-effect-induced soft synthesis. Although the ORR activity and stability of LTMC nanomaterials are still far from what is needed for practical fuel-cell applications, much enhanced electrocatalytic performance can be expected. Recent advances have emphasized that decorating the surface of the LTMC nanostructures with other functional nanoparticles can lead to much better ORR catalytic activity. It is believed that new synthesis approaches to LTMCs, modification techniques of LTMCs, and LTMCs with desirable morphology, size, composition, and structures are expected to be developed in the future to satisfy the requirements of commercial fuel cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In Situ Studies and Magnetic Properties of the Cmcm Polymorph of LiCoPO4 with a Hierarchical Dumbbell-Like Morphology Synthesized by Easy Single-Step Polyol Synthesis

Directory of Open Access Journals (Sweden)

Carlos Alarcón-Suesca

2016-11-01

Full Text Available LiCoPO4 (LCP exists in three different structural modifications: LCP-Pnma (olivine structure, LCP-Pn21a (KNiPO4 structure type, and LCP-Cmcm (Na2CrO4 structure type. The synthesis of the LCP-Cmcm polymorph has been reported via high pressure/temperature solid-state methods and by microwave-assisted solvothermal synthesis. Phase transitions from both LCP-Pn21a and LCP-Cmcm to LCP-Pnma upon heating indicates a metastable behavior. However, a precise study of the structural changes during the heating process and the magnetic properties of LCP-Cmcm are hitherto unknown. Herein, we present the synthesis and characterization of LCP-Cmcm via a rapid and facile soft-chemistry approach using two different kinetically controlled pathways, solvothermal and polyol syntheses, both of which only require relatively low temperatures (~200 °C. Additionally, by polyol, method a dumbbell-like morphology is obtained without the use of any additional surfactant or template. A temperature-dependent in situ powder XRD shows a transition from LCP-Cmcm at room temperature to LCP-Pnma and finally to LCP-Pn21a at 575 and 725 °C, respectively. In addition to that, the determination of the magnetic susceptibility as a function of temperature indicates a long-range antiferromagnetic order below TN = 11 K at 10 kOe and 9.1 K at 25 kOe. The magnetization curves suggests the presence of a metamagnetic transition.

Solvothermal one-step synthesis of Ni-Al layered double hydroxide/carbon nanotube/reduced graphene oxide sheet ternary nanocomposite with ultrahigh capacitance for supercapacitors.

Science.gov (United States)

Yang, Wanlu; Gao, Zan; Wang, Jun; Ma, Jing; Zhang, Milin; Liu, Lianhe

2013-06-26

A Ni-Al layered double hydroxide (LDH), mutil-wall carbon nanotube (CNT), and reduced graphene oxide sheet (GNS) ternary nanocomposite electrode material has been developed by a facile one-step ethanol solvothermal method. The obtained LDH/CNT/GNS composite displayed a three-dimensional (3D) architecture with flowerlike Ni-Al LDH/CNT nanocrystallites gradually self-assembled on GNS nanosheets. GNS was used as building blocks to construct 3D nanostructure, and the LDH/CNT nanoflowers in turn separated the two-dimensional (2D) GNS sheets, which preserved the high surface area of GNSs. Furthermore, the generated porous networks with a narrow pore size distribution in the LDH/CNT/GNS composite were also demonstrated by the N2 adsorption/desorption experiment. Such morphology would be favorable to improve the mass transfer and electrochemical action of the electrode. As supercapacitor electrode material, the LDH/CNT/GNS hybrid exhibited excellent electrochemical performance, including ultrahigh specific capacitance (1562 F/g at 5 mA/cm(2)), excellent rate capability, and long-term cycling performance, which could be a promising energy storage/conversion material for supercapacitor application.

Solvothermal synthesis of mesoporous slabstone-like TiO{sub 2} and its photodegradation preference in a methyl orange-rhodamine B mixture solution

Energy Technology Data Exchange (ETDEWEB)

Liu, Kun; Zhu, Lianjie; Li, Naixuan; Sun, Youguang; Li, Hongbin; Zhu, Xuchen [School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2012-10-15

Mesoporous slabstone-like anatase TiO{sub 2} micro-nanometer composite structure has been successfully synthesized by a facile solvothermal method at 180 C using polyethylene glycol (PEG) as a structure-directing agent, followed by calcination at 400 C for 2 h. The crystal structure and morphology of the product were characterized by XRD, SEM, TEM and HRTEM. Its BET specific surface area was obtained from N{sub 2} adsorption-desorption isotherm measurement. Rhodamine B (RB) aqueous solution was used to evaluate the photocatalytic activity of the as-prepared TiO{sub 2} under simulated sunlight irradiation and compared with that of commercial TiO{sub 2} (P25). A RB and methyl orange (MO) coexisting solution was chosen to investigate the photodegradation preference of the slabstone-like TiO{sub 2} on these two dyes. The results show that the photocatalytic activity of the as-prepared TiO{sub 2} is much higher than that of P25, and MO is the preferential degradation species in the MO-RB mixture solution. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and characterization of the ternary telluroargentate K4[Ag18Te11

KAUST Repository

Davaasuren, Bambar

2014-10-19

The ternary potassium telluroargentate(I), K4[Ag18Te11], was prepared by solvothermal synthesis in ethylenediamine at 160 °C. It crystallizes in the cubic space group Fm3¯ m (no. 225) with the cell parameter a = 18.6589(6) Å. The crystal structure can be described as a [Ag18Te11]4- three-dimensional anionic framework with the voids accommodating potassium cations. Chemical bonding analysis reveals polar covalent Ag-Te bonds and considerable Ag-Ag interactions, which support the complex anionic character of the structure. The compound is thermally stable up to 450 °C in an inert atmosphere.

Lakatos Revisited.

Science.gov (United States)

Court, Deborah

1999-01-01

Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social…

Microstructure and electrical-optical properties of cesium tungsten oxides synthesized by solvothermal reaction followed by ammonia annealing

International Nuclear Information System (INIS)

Liu Jingxiao; Ando, Yoshihiko; Dong Xiaoli; Shi Fei; Yin Shu; Adachi, Kenji; Chonan, Takeshi; Tanaka, Akikazu; Sato, Tsugio

2010-01-01

Cesium tungsten oxides (Cs x WO 3 ) were synthesized by solvothermal reactions using ethanol and 57.1 vol% ethanol aqueous solution at 200 o C for 12 h, and the effects of post annealing in ammonia atmosphere on the microstructure and electrical-optical properties were investigated. Agglomerated particles consisting of disk-like nanoparticles and nanorods of Cs x WO 3 were formed in the pure ethanol and ethanol aqueous solutions, respectively. The samples retained the original morphology and crystallinity after annealing in ammonia atmosphere up to 500 o C, while a small amount of nitrogen ion were incorporated in the lattice. The as-prepared Cs x WO 3 sample showed excellent near infrared (NIR) light shielding ability as well as high transparency in the visible light region. The electrical resistivity of the pressed pellets of the powders prepared in pure ethanol and 57.1 vol% ethanol aqueous solution greatly decreased after ammonia annealing at 500 o C, i.e., from 734 to 31.5 and 231 to 3.58 Ω cm, respectively. - Graphical abstract: Cesium tungsten oxides (Cs x WO 3 ) with different morphology were synthesized by solvothermal reaction, and the effects of post-ammonia annealing on the microstructure and electrical-optical properties were investigated.

Preparation of Hierarchical BiOBr Microspheres for Visible Light-Induced Photocatalytic Detoxification and Disinfection

Directory of Open Access Journals (Sweden)

Ayla Ahmad

2016-01-01

Full Text Available Photocatalytic degradation is a promising alternative to traditional wastewater treatment methods. Recently developed visible light-responsive photocatalyst, BiOBr, has attracted extensive attentions. Hereby, a detailed investigation of application of BiOBr to bacterial inactivation and organic pollutants degradation is reported. Hydrothermal catalyst was prepared using template-free method. While, for solvothermal synthesis, CTAB was used as a template. Results indicate a higher photocatalytic activity by the solvothermally prepared catalyst. Solvothermally prepared BiOBr exhibited high photocatalytic activities in both water detoxification and disinfection.

Oxidative phosphorylation revisited

DEFF Research Database (Denmark)

Nath, Sunil; Villadsen, John

2015-01-01

The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic...

Optimization on electrochemical synthesis of HKUST-1 as candidate catalytic material for Green diesel production

Science.gov (United States)

Lestari, W. W.; Nugraha, R. E.; Winarni, I. D.; Adreane, M.; Rahmawati, F.

2016-04-01

In the effort to support the discovery of new renewable energy sources in Indonesia, biofuel is one of promising options. The conversion of vegetable oil into ready-biofuel, especially green diesel, needs several steps, one of which is a hydrogenation or hydro-deoxygenation reaction. In this case, the catalyst plays a very important role regarding to its activity and selectivity, and Metal-Organic Frameworks (MOFs) becoming a new generation of heterogeneous catalyst in this area. In this research, a preliminary study to optimize electrochemical synthesis of the catalytic material based on MOFs, namely HKUST-1 [Cu3(BTC)2], has been conducted. Some electrochemical reaction parameters were tested, for example by modifying the electrochemical synthetic conditions, i.e. by performing variation of voltages (12, 13, 14, and 15 Volt), temperatures (RT, 40, 60, and 80 °C) and solvents (ethanol, water, methanol and dimethyl-formamide (DMF)). Material characterization was carried out by XRD, SEM, FTIR, DTA/TG and SAA. The results showed that the optimum synthetic conditions of HKUST-1 are performed at room temperature in a solvent combination of water: ethanol (1: 1) and a voltage of 15 Volt for 2 hours. The XRD-analysis revealed that the resulted peaks are identical to the simulated powder pattern generated from single crystal data and comparable to the peaks of solvothermal method. However, the porosity of the resulting material through electrochemical method is still in the range of micro-pore according to IUPAC and 50% smaller than the porosity resulted from solvothermal synthesis. The corresponding compounds are thermally stable until 300 °C according to TG/DTA.

Circular revisit orbits design for responsive mission over a single target

Science.gov (United States)

Li, Taibo; Xiang, Junhua; Wang, Zhaokui; Zhang, Yulin

2016-10-01

The responsive orbits play a key role in addressing the mission of Operationally Responsive Space (ORS) because of their capabilities. These capabilities are usually focused on supporting specific targets as opposed to providing global coverage. One subtype of responsive orbits is repeat coverage orbit which is nearly circular in most remote sensing applications. This paper deals with a special kind of repeating ground track orbit, referred to as circular revisit orbit. Different from traditional repeat coverage orbits, a satellite on circular revisit orbit can visit a target site at both the ascending and descending stages in one revisit cycle. This typology of trajectory allows a halving of the traditional revisit time and does a favor to get useful information for responsive applications. However the previous reported numerical methods in some references often cost lots of computation or fail to obtain such orbits. To overcome this difficulty, an analytical method to determine the existence conditions of the solutions to revisit orbits is presented in this paper. To this end, the mathematical model of circular revisit orbit is established under the central gravity model and the J2 perturbation. A constraint function of the circular revisit orbit is introduced, and the monotonicity of that function has been studied. The existent conditions and the number of such orbits are naturally worked out. Taking the launch cost into consideration, optimal design model of circular revisit orbit is established to achieve a best orbit which visits a target twice a day in the morning and in the afternoon respectively for several days. The result shows that it is effective to apply circular revisit orbits in responsive application such as reconnoiter of natural disaster.

Challenges in TEM sample preparation of solvothermally grown CuInS2 films.

Science.gov (United States)

Frank, Anna; Changizi, Rasa; Scheu, Christina

2018-06-01

Transmission electron microscopy (TEM) is a widely used tool to characterize materials. The required samples need to be electron transparent which should be achieved without changing the microstructure. This work describes different TEM sample preparation techniques of nanostructured CuInS 2 thin films on fluorine-doped tin oxide substrates, synthesized solvothermally using l-cysteine as sulfur source. Focused ion beam lamellae, conventional cross section samples and scratch samples have been prepared and investigated. It was possible to prepare appropriate samples with each technique, however, each technique brings with it certain advantages and disadvantages. FIB preparation of solvothermally synthesized CuInS 2 suffers from two main drawbacks. First, the whole CuInS 2 layer displays a strongly increased Cu content caused by Cu migration and preferential removal of In. Further, electron diffraction shows the formation of an additional CuS phase after Ga + bombardment. Second, diffraction analysis is complicated by a strong contribution of crystalline Pt introduced during the FIB preparation and penetrating into the porous film surface. The conventional cross sectional CuInS 2 sample also shows a Cu signal enhancement which is caused by contribution of the brass tube material used for embedding. Additionally, Cu particles have been observed inside the CuInS 2 which have been sputtered on the film during preparation. Only the scratch samples allow an almost artefact-free and reliable elemental quantification using energy-dispersive X-ray spectroscopy. However, scratch samples suffer from the drawback that it is not possible to determine the layer thickness, which is possible for both cross sectional preparation techniques. Consequently, it is concluded that the type of sample preparation should be chosen dependent on the required information. A full characterization can only be achieved when the different techniques are combined. Copyright © 2018 Elsevier Ltd. All

Method to synthesize metal chalcogenide monolayer nanomaterials

Science.gov (United States)

Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.

2016-12-13

Metal chalcogenide monolayer nanomaterials can be synthesized from metal alkoxide precursors by solution precipitation or solvothermal processing. The synthesis routes are more scalable, less complex and easier to implement than other synthesis routes.

p-type ZnS:N nanowires: Low-temperature solvothermal doping and optoelectronic properties

International Nuclear Information System (INIS)

Wang, Ming-Zheng; Xie, Wei-Jie; Hu, Han; Yu, Yong-Qiang; Wu, Chun-Yan; Wang, Li; Luo, Lin-Bao

2013-01-01

Nitrogen doped p-type ZnS nanowires (NWs) were realized using thermal decomposition of triethylamine at a mild temperature. Field-effect transistors made from individual ZnS:N NWs revealed typical p-type conductivity behavior, with a hole mobility of 3.41 cm 2 V −1 s −1 and a hole concentration of 1.67 × 10 17  cm −3 , respectively. Further analysis found that the ZnS:N NW is sensitive to UV light irradiation with high responsivity, photoconductive gain, and good spectral selectivity. The totality of this study suggests that the solvothermal doping method is highly feasible to dope one dimensional semiconductor nanostructures for optoelectronic devices application

One-pot solvothermal route to self-assembly of cauliflower-shaped CdS microspheres

Energy Technology Data Exchange (ETDEWEB)

Ge Ming [Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071 (China); Cui Yao [Institute of New Energy Material Chemistry, and Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China); Liu Lu, E-mail: liul@nankai.edu.cn [Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071 (China); Zhou Zhen, E-mail: zhouzhen@nankai.edu.cn [Institute of New Energy Material Chemistry, and Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China)

2011-05-15

Nearly monodispersed cauliflower-shaped CdS microspheres were prepared through a simple one-step solvothermal route on a large scale by employing sodium dodecyl sulfate (SDS) as the surfactant. Images by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) indicate that cauliflower-shaped CdS microspheres with diameters in the range from 1.3 to 4.5 {mu}m are assembled by nanoparticles with an average diameter of approximately 30 nm. The possible formation mechanism of the cauliflower-shaped CdS microspheres was also proposed. The photovoltaic activity of cauliflower-shaped CdS architectures has been investigated, indicating that the as-obtained CdS microspheres exhibited higher photovoltaic performance in comparison with CdS nanoparticles.

Synthesis of uniform CdS nanowires in high yield and its single nanowire electrical property

International Nuclear Information System (INIS)

Yan Shancheng; Sun Litao; Qu Peng; Huang Ninping; Song Yinchen; Xiao Zhongdang

2009-01-01

Large-scale high quality CdS nanowires with uniform diameter were synthesized by using a rapid and simple solvothermal route. Field emission scan electron microscopy (FESEM) and transmission electron microscopy (TEM) images show that the CdS nanowires have diameter of about 26 nm and length up to several micrometres. High resolution TEM (HRTEM) study indicates the single-crystalline nature of CdS nanowires with an oriented growth along the c-axis direction. The optical properties of the products were characterized by UV-vis absorption spectra, photoluminescence spectra and Raman spectra. The resistivity, electron concentration and electron mobility of single NW are calculated by fitting the symmetric I-V curves measured on single NW by the metal-semiconductor-metal model based on thermionic field emission theory. - Graphical abstract: Large-scale high quality CdS nanowires (NWs) with uniform diameter were synthesized by using a rapid and simple solvothermal route. The reaction time is reduced to 2 h, comparing to other synthesis which needed long reaction time up to 12 h. In addition, the as-prepared CdS nanowires have more uniform diameter and high yield. More importantly, the I-V curve of present single CdS nanowire has a good symmetric characteristic as expected by the theory.

Solvothermal growth of a ruthenium metal-organic framework featuring HKUST-1 structure type as thin films on oxide surfaces.

Science.gov (United States)

Kozachuk, Olesia; Yusenko, Kirill; Noei, Heshmat; Wang, Yuemin; Walleck, Stephan; Glaser, Thorsten; Fischer, Roland A

2011-08-14

Phase-pure crystalline thin films of a mixed-valence Ru(2)(II,III) metal-organic framework with 1,3,5-benzenetricarboxylate (btc) as a linker were solvothermally grown on amorphous alumina and silica surfaces. Based on the Rietveld refinement, the structure of Ru-MOF was assigned to be analogous to [Cu(3)(btc)(2)] (HKUST-1). This journal is © The Royal Society of Chemistry 2011

Solvothermal-induced 3D macroscopic SnO2/nitrogen-doped graphene aerogels for high capacity and long-life lithium storage.

Science.gov (United States)

Wang, Ronghua; Xu, Chaohe; Sun, Jing; Gao, Lian; Yao, Heliang

2014-03-12

3D macroscopic tin oxide/nitrogen-doped graphene frameworks (SnO2/GN) were constructed by a novel solvothermal-induced self-assembly process, using SnO2 colloid as precursor (crystal size of 3-7 nm). Solvothermal treatment played a key role as N,N-dimethylmethanamide (DMF) acted both as reducing reagent and nitrogen source, requiring no additional nitrogen-containing precursors or post-treatment. The SnO2/GN exhibited a 3D hierarchical porous architecture with a large surface area (336 m(2)g(-1)), which not only effectively prevented the agglomeration of SnO2 but also facilitated fast ion and electron transport through 3D pathways. As a result, the optimized electrode with GN content of 44.23% exhibited superior rate capability (1126, 855, and 614 mAh g(-1) at 1000, 3000, and 6000 mA g(-1), respectively) and extraordinary prolonged cycling stability at high current densities (905 mAh g(-1) after 1000 cycles at 2000 mA g(-1)). Electrochemical impedance spectroscopy (EIS) and morphological study demonstrated the enhanced electrochemical reactivity and good structural stability of the electrode.

Revisiting Okun's Relationship

NARCIS (Netherlands)

Dixon, R.; Lim, G.C.; van Ours, Jan

2016-01-01

Our paper revisits Okun's relationship between observed unemployment rates and output gaps. We include in the relationship the effect of labour market institutions as well as age and gender effects. Our empirical analysis is based on 20 OECD countries over the period 1985-2013. We find that the

Tourists' perceptions and intention to revisit Norway

OpenAIRE

Lazar, Ana Florina; Komolikova-Blindheim, Galyna

2016-01-01

Purpose - The overall purpose of this study is to explore tourists' perceptions and their intention to revisit Norway. The aim is to find out what are the factors that drive the overall satisfaction, the willingness to recommend and the revisit intention of international tourists that spend their holiday in Norway. Design-Method-Approach - the Theory of Planned Behavior (Ajzen 1991), is used as a framework to investigate tourists' intention and behavior towards Norway as destination. The o...

Uniform hollow Fe3O4 spheres prepared by template-free solvothermal method as anode material for lithium-ion batteries

International Nuclear Information System (INIS)

Zhang Jingjing; Yao Yu; Huang Tao; Yu Aishui

2012-01-01

Graphical abstract: Unique hollow Fe 3 O 4 spheres assembled by Fe 3 O 4 nanoparticles prepared by a simple template-free solvothermal reaction are tested as anode material for lithium-ion batteries. The results show that the material delivers reversible specific capacities of 870 mA h g −1 even after 50 cycles at 100 mA g −1 and 836 mA h g −1 at 500 mA g −1 . The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability. Highlights: ► Uniform hollow Fe 3 O 4 spheres were prepared by a template-free solvothermal method. ► The hollow Fe 3 O 4 spheres have the capacity of 870 mA h g −1 at 50th cycle. ► The specific capacity can be well maintained at a large current density. ► The hollow Fe 3 O 4 spheres exhibit enhanced rate capability. ► Electrochemical performance of hollow Fe 3 O 4 spheres is better than Fe 3 O 4 powders. - Abstract: Unique hollow Fe 3 O 4 spheres are prepared by a simple template-free solvothermal reaction. In the reaction, ethylene glycol (EG) and polyvinylpyrrolidone (PVP) serve as the reducing agent and surface stabilizer, respectively. NH 4 Ac plays the role of the structure-directing agent, which combines with the Ostwald ripening process, resulting in the favored formation of hollow structures. The morphologies and structures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The hollow Fe 3 O 4 spheres exhibit excellent cycling and rate performance as anode material for lithium-ion batteries, delivering reversible specific capacities of 870 mA h g −1 even after 50 cycles at 100 mA g −1 and 836 mA h g −1 at 500 mA g −1 . The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability.

A multi-paradigm language for reactive synthesis

Directory of Open Access Journals (Sweden)

Ioannis Filippidis

2016-02-01

Full Text Available This paper proposes a language for describing reactive synthesis problems that integrates imperative and declarative elements. The semantics is defined in terms of two-player turn-based infinite games with full information. Currently, synthesis tools accept linear temporal logic (LTL as input, but this description is less structured and does not facilitate the expression of sequential constraints. This motivates the use of a structured programming language to specify synthesis problems. Transition systems and guarded commands serve as imperative constructs, expressed in a syntax based on that of the modeling language Promela. The syntax allows defining which player controls data and control flow, and separating a program into assumptions and guarantees. These notions are necessary for input to game solvers. The integration of imperative and declarative paradigms allows using the paradigm that is most appropriate for expressing each requirement. The declarative part is expressed in the LTL fragment of generalized reactivity(1, which admits efficient synthesis algorithms, extended with past LTL. The implementation translates Promela to input for the Slugs synthesizer and is written in Python. The AMBA AHB bus case study is revisited and synthesized efficiently, identifying the need to reorder binary decision diagrams during strategy construction, in order to prevent the exponential blowup observed in previous work.

Annealing temperatures influence luminescence of YBO{sub 3}: Ce{sup 3+}, Yb{sup 3+} prepared by solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Wang, Yue [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China); Hu, Xiaoyun, E-mail: hxy3275@nwu.edu.cn [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China); Zhan, Suchang; Sun, Xiao; Wang, Zhizhong; Miao, Tian; Miao, Hui [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China); Fan, Jun [School of Chemical Engineering, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China)

2014-08-01

Near-infrared (NIR) quantum cutting (QC) YBO{sub 3}: Ce{sup 3+}, Yb{sup 3+} phosphors have been synthesized by solvothermal method with further heat treatment. The emission spectrum shows the Vis and NIR emission intensity of samples are both increasingly strong as annealing temperature rises when the annealing temperature is above 600 °C. Meanwhile the Vis emission of unannealed sample is observed. SEM images show that the sample annealed at different temperatures (200–900 °C) is mainly composed of nanosheets like potato chips, which is melt down granules after annealing treatment above 1000 °C.The crystal texture of all samples whether annealed or not is hexagonal through the analysis of XRD. The Raman and infrared spectrums indicate that the boron ions exist of BO{sub 4} units when the annealing temperature is above 600 °C. The infrared profile of unannealed sample shows that there are N–H units in the samples without annealing treatment. - Highlights: • The nanosheets like potato chips are synthesized by solvothermal method. • Annealing temperature is a great effect for luminescence of sample. • The boron ions exist of BO{sub 4} when the annealing temperature is above 600 °C, whose quantity determines the luminescent intensity. • According to the infrared profile of unannealed sample, there are N–H units, which are beneficial to the Vis emission.

Predictors and Outcomes of Revisits in Older Adults Discharged from the Emergency Department.

Science.gov (United States)

de Gelder, Jelle; Lucke, Jacinta A; de Groot, Bas; Fogteloo, Anne J; Anten, Sander; Heringhaus, Christian; Dekkers, Olaf M; Blauw, Gerard J; Mooijaart, Simon P

2018-04-01

To study predictors of emergency department (ED) revisits and the association between ED revisits and 90-day functional decline or mortality. Multicenter cohort study. One academic and two regional Dutch hospitals. Older adults discharged from the ED (N=1,093). At baseline, data on demographic characteristics, illness severity, and geriatric parameters (cognition, functional capacity) were collected. All participants were prospectively followed for an unplanned revisit within 30 days and for functional decline and mortality 90 days after the initial visit. The median age was 79 (interquartile range 74-84), and 114 participants (10.4%) had an ED revisit within 30 days of discharge. Age (hazard ratio (HR)=0.96, 95% confidence interval (CI)=0.92-0.99), male sex (HR=1.61, 95% CI=1.05-2.45), polypharmacy (HR=2.06, 95% CI=1.34-3.16), and cognitive impairment (HR=1.71, 95% CI=1.02-2.88) were independent predictors of a 30-day ED revisit. The area under the receiver operating characteristic curve to predict an ED revisit was 0.65 (95% CI=0.60-0.70). In a propensity score-matched analysis, individuals with an ED revisit were at higher risk (odds ratio=1.99 95% CI=1.06-3.71) of functional decline or mortality. Age, male sex, polypharmacy, and cognitive impairment were independent predictors of a 30-day ED revisit, but no useful clinical prediction model could be developed. However, an early ED revisit is a strong new predictor of adverse outcomes in older adults. © 2018 The Authors. The Journal of the American Geriatrics Society published by Wiley Periodicals, Inc. on behalf of The American Geriatrics Society.

Sensemaking Revisited

DEFF Research Database (Denmark)

Holt, Robin; Cornelissen, Joep

2014-01-01

We critique and extend theory on organizational sensemaking around three themes. First, we investigate sense arising non-productively and so beyond any instrumental relationship with things; second, we consider how sense is experienced through mood as well as our cognitive skills of manipulation ...... research by revisiting Weick’s seminal reading of Norman Maclean’s book surrounding the tragic events of a 1949 forest fire at Mann Gulch, USA....

All-gas-phase synthesis of UiO-66 through modulated atomic layer deposition

Science.gov (United States)

Lausund, Kristian Blindheim; Nilsen, Ola

2016-11-01

Thin films of stable metal-organic frameworks (MOFs) such as UiO-66 have enormous application potential, for instance in microelectronics. However, all-gas-phase deposition techniques are currently not available for such MOFs. We here report on thin-film deposition of the thermally and chemically stable UiO-66 in an all-gas-phase process by the aid of atomic layer deposition (ALD). Sequential reactions of ZrCl4 and 1,4-benzenedicarboxylic acid produce amorphous organic-inorganic hybrid films that are subsequently crystallized to the UiO-66 structure by treatment in acetic acid vapour. We also introduce a new approach to control the stoichiometry between metal clusters and organic linkers by modulation of the ALD growth with additional acetic acid pulses. An all-gas-phase synthesis technique for UiO-66 could enable implementations in microelectronics that are not compatible with solvothermal synthesis. Since this technique is ALD-based, it could also give enhanced thickness control and the possibility to coat irregular substrates with high aspect ratios.

Study of structural and optical properties of CaMoO{sub 4} nanoparticles synthesized by the microwave-assisted solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Botelho, G., E-mail: gleice.lorena@gmail.com [INCTMN-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, 13565-905, São Carlos, SP (Brazil); Nogueira, I.C. [Instituto Federal do Maranhão, PPG em Engenharia de Materiais, 65030-005, São Luís, MA (Brazil); Moraes, E. [INCTMN-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, 13565-905, São Carlos, SP (Brazil); Longo, E. [INCTMN-UNESP, Universidade Estadual Paulista, P.O. Box 355, CEP, 14801-907, Araraquara, SP (Brazil)

2016-11-01

Calcium molybdate (CaMoO{sub 4}) nanoparticles were synthesized by using a rapid assisted-microwave solvothermal method. X-ray diffraction measurements, Fourier transform Raman and Fourier transform infrared spectroscopies, revealed that the samples all have a scheelite-type tetragonal structure. In addition, the data obtained from the Rietveld refinements revealed distortions of the [Ca−O] and [Mo−O] bonds that led, in turn, to distortions of the [CaO{sub 8}] and [MoO{sub 4}] clusters. The presence of irregular spherical-like CaMoO{sub 4} nanoparticles and the corresponding crystallographic arrangement were confirmed and determined via transmission electron microscopy and high resolution transmission electron microscopy, respectively. First-principles quantum mechanical calculations based on the density functional theory at the B3LYP level were employed in order to understand the band structure and density of states of CaMoO{sub 4} in the excited singlet and triplet states. Furthermore, the optical properties were investigated by performing ultraviolet–visible spectroscopy and photoluminescence (PL) measurements. Maximum PL emission of CaMoO{sub 4} powders was detected in the green-region wavelength of the electromagnetic spectrum; this emission was attributed to the distorted [MoO{sub 4}] clusters. - Highlights: • Effect of propane-1,3-diol in the synthesis of nanoparticles by a rapid method. • Utilization of first-principles quantum mechanical calculations. • Investigation of photoluminescent properties of CaMoO{sub 4} nanoparticles.

Solvothermal Synthesis of Three-Dimensional Hierarchical CuS Microspheres from a Cu-Based Ionic Liquid Precursor for High-Performance Asymmetric Supercapacitors.

Science.gov (United States)

Zhang, Jing; Feng, Huijie; Yang, Jiaqin; Qin, Qing; Fan, Hongmin; Wei, Caiying; Zheng, Wenjun

2015-10-07

It is meaningful to exploit copper sulfide materials with desired structure as well as potential application due to their cheapness and low toxicity. A low-temperature and facile solvothermal method for preparing three-dimensional (3D) hierarchical covellite (CuS) microspheres from an ionic liquid precursor [Bmim]2Cu2Cl6 (Bmim = 1-butyl-3-methylimidazolium) is reported. The formation of CuS nanostructures was achieved by decomposition of intermediate complex Cu(Tu)3Cl (thiourea = Tu), which produced CuS microspheres with diameters of 2.5-4 μm assembled by nanosheets with thicknesses of 10-15 nm. The ionic liquid, as an "all-in-one" medium, played a key role for the fabrication and self-assembly of CuS nanosheets. The alkylimidazolium rings ([Bmim](+)) were found to adsorb onto the (001) facets of CuS crystals, which inhibited the crystal growth along the [001] direction, while the alkyl chain had influence on the assembly of CuS nanosheets. The CuS microspheres showed enhanced electrochemical performance and high stability for the application in supercapacitors due to intriguing structural design and large specific surface area. When this well-defined CuS electrode was assembled into an asymmetric supercapacitor (ASC) with an activated carbon (AC) electrode, the CuS//AC-ASC demonstrated good cycle performance (∼88% capacitance after 4000 cycles) and high energy density (15.06 W h kg(-1) at a power density of 392.9 W kg(-1)). This work provides new insights into the use of copper sulfide electrode materials for asymmetric supercapacitors and other electrochemical devices.

Facile synthesis of zinc oxide nanoparticles decorated graphene oxide composite via simple solvothermal route and their photocatalytic activity on methylene blue degradation.

Science.gov (United States)

Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Perumal, Suguna; Karthikeyan, Dhanapalan; Lee, Yong Rok

2016-09-01

Zinc oxide nanoparticles decorated graphene oxide (ZnO@GO) composite was synthesized by simple solvothermal method where zinc oxide (ZnO) nanoparticles and graphene oxide (GO) were synthesized via simple thermal oxidation and Hummers method, respectively. The obtained materials were thoroughly characterized by various physico-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Raman spectrum shows the intensity of D to G value was close to one which confirms the obtained GO and ZnO@GO composite possesses moderate graphitization. TEM images shows the ZnO nanoparticles mean size of 15±5nm were dispersed over the wrinkled graphene layers. The photocatalytic performance of ZnO@GO composite on degradation of methylene blue (MB) is investigated and the results show that the GO plays an important role in the enhancement of photocatalytic performance. The synthesized ZnO@GO composite achieves a maximum degradation efficiency of 98.5% in a neutral solution under UV-light irradiation for 15min as compared with pure ZnO (degradation efficiency is 49% after 60min of irradiation) due to the increased light absorption, the reduced charge recombination with the introduction of GO. Moreover, the resulting ZnO@GO composite possesses excellent degradation efficiency as compared to ZnO nanoparticles alone on MB. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly biocompatible, nanocrystalline hydroxyapatite synthesized in a solvothermal process driven by high energy density microwave radiation

Science.gov (United States)

Smolen, Dariusz; Chudoba, Tadeusz; Malka, Iwona; Kedzierska, Aleksandra; Lojkowski, Witold; Swieszkowski, Wojciech; Kurzydlowski, Krzysztof Jan; Kolodziejczyk-Mierzynska, Małgorzata; Lewandowska-Szumiel, Małgorzata

2013-01-01

A microwave, solvothermal synthesis of highly biocompatible hydroxyapatite (HAp) nanopowder was developed. The process was conducted in a microwave radiation field having a high energy density of 5 W/mL and over a time less than 2 minutes. The sample measurements included: powder X-ray diffraction, density, specific surface area, and chemical composition. The morphology and structure were investigated by scanning electron microscopy as well as transmission electron microscopy (TEM). The thermal behavior analysis was conducted using a simultaneous thermal analysis technique coupled with quadruple mass spectrometry. Additionally, Fourier transform infrared spectroscopy tests of heated samples were performed. A degradation test and a biocompatibility study in vitro using human osteoblast cells were also conducted. The developed method enables the synthesis of pure, fully crystalline hexagonal HAp nanopowder with a specific surface area close to 240 m2/g and a Ca/P molar ratio equal to 1.57. TEM measurements showed that this method results in particles with an average grain size below 6 nm. A 28-day degradation test conducted according to the ISO standard indicated a 22% loss of initial weight and a calcium ion concentration at 200 μmol/dm3 in the tris(hydroxymethyl)aminomethane hydrochloride test solution. The cytocompatibility of the obtained material was confirmed in a culture of human bone derived cells, both in an indirect test using the material extract, and in direct contact. A quantitative analysis was based on the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide. Viability assay as well as on DNA content measurements in the PicoGreen test. Indirect observations were performed at one point in time according to the ISO standard for in vitro cytotoxicity (ie, after 24 hours of cell exposure to the extracts). The direct contact tests were completed at three time points: after 24 hours, on day 7, and on day 14 of a culture in an osteogenic

Structure-directing effects of ionic liquids in the ionothermal synthesis of metal-organic frameworks.

Science.gov (United States)

Vaid, Thomas P; Kelley, Steven P; Rogers, Robin D

2017-07-01

Traditional synthesis of metal-organic frameworks (MOFs) involves the reaction of a metal-containing precursor with an organic linker in an organic solvent at an elevated temperature, in what is termed a 'solvothermal' reaction. More recently, many examples have been reported of MOF synthesis in ionic liquids (ILs), rather than an organic solvent, in 'ionothermal' reactions. The high concentration of both cations and anions in an ionic liquid allows for the formation of new MOF structures in which the IL cation or anion or both are incorporated into the MOF. Most commonly, the IL cation is included in the open cavities of the MOF, countering the anionic charge of the MOF framework itself and acting as a template around which the MOF structure forms. Ionic liquids can also serve other structure-directing roles, for example, when an IL containing a single enantiomer of a chiral anion leads to a homochiral MOF, even though the IL anion is not itself incorporated into the MOF. A comprehensive review of ionothermal syntheses of MOFs, and the structure-directing effects of the ILs, is given.

A Structural Equation Model of Risk Perception of Rockfall for Revisit Intention

OpenAIRE

Ya-Fen Lee; Yun-Yao Chi

2014-01-01

The study aims to explore the relationship between risk perception of rockfall and revisit intention using a Structural Equation Modeling (SEM) analysis. A total of 573 valid questionnaires are collected from travelers to Taroko National Park, Taiwan. The findings show the majority of travelers have the medium perception of rockfall risk, and are willing to revisit the Taroko National Park. The revisit intention to Taroko National Park is influenced by hazardous preferences, willingness-to-pa...

The Faraday effect revisited

DEFF Research Database (Denmark)

Cornean, Horia; Nenciu, Gheorghe

2009-01-01

This paper is the second in a series revisiting the (effect of) Faraday rotation. We formulate and prove the thermodynamic limit for the transverse electric conductivity of Bloch electrons, as well as for the Verdet constant. The main mathematical tool is a regularized magnetic and geometric...

Remembered Experiences and Revisit Intentions

DEFF Research Database (Denmark)

Barnes, Stuart; Mattsson, Jan; Sørensen, Flemming

2016-01-01

Tourism is an experience-intensive sector in which customers seek and pay for experiences above everything else. Remembering past tourism experiences is also crucial for an understanding of the present, including the predicted behaviours of visitors to tourist destinations. We adopt a longitudinal...... approach to memory data collection from psychological science, which has the potential to contribute to our understanding of tourist behaviour. In this study, we examine the impact of remembered tourist experiences in a safari park. In particular, using matched survey data collected longitudinally and PLS...... path modelling, we examine the impact of positive affect tourist experiences on the development of revisit intentions. We find that longer-term remembered experiences have the strongest impact on revisit intentions, more so than predicted or immediate memory after an event. We also find that remembered...

Revisiting the Okun relationship

NARCIS (Netherlands)

Dixon, R. (Robert); Lim, G.C.; J.C. van Ours (Jan)

2017-01-01

textabstractOur article revisits the Okun relationship between observed unemployment rates and output gaps. We include in the relationship the effect of labour market institutions as well as age and gender effects. Our empirical analysis is based on 20 OECD countries over the period 1985–2013. We

Bounded Intention Planning Revisited

OpenAIRE

Sievers Silvan; Wehrle Martin; Helmert Malte

2014-01-01

Bounded intention planning provides a pruning technique for optimal planning that has been proposed several years ago. In addition partial order reduction techniques based on stubborn sets have recently been investigated for this purpose. In this paper we revisit bounded intention planning in the view of stubborn sets.

Graphene-supported SnO2 nanoparticles prepared by a solvothermal approach for an enhanced electrochemical performance in lithium-ion batteries

OpenAIRE

Wang, Bei; Su, Dawei; Park, Jinsoo; Ahn, Hyojun; Wang, Guoxiu

2012-01-01

SnO2 nanoparticles were dispersed on graphene nanosheets through a solvothermal approach using ethylene glycol as the solvent. The uniform distribution of SnO2 nanoparticles on graphene nanosheets has been confirmed by scanning electron microscopy and transmission electron microscopy. The particle size of SnO2 was determined to be around 5 nm. The as-synthesized SnO2/graphene nanocomposite exhibited an enhanced electrochemical performance in lithium-ion batteries, compared with bare graphene ...

Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

Science.gov (United States)

Liu, Yang; Zhang, Jieyu; Li, Ying; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Hu, Pengfei; Chou, Shulei; Wang, Guoxiu

2017-01-01

To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C), good high-rate discharge capacity (118 mAh g−1 at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure. PMID:29099814

Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Yang Liu

2017-11-01

Full Text Available To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG as the solvent medium and cetyltrimethylammonium bromide (CTAB as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C, good high-rate discharge capacity (118 mAh g−1 at 10 C, and fine cycling stability (99.2% after 200 cycles at 0.1 C. The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure.

Revisiting Nursing Research in Nigeria

African Journals Online (AJOL)

2016-08-18

Aug 18, 2016 ... health care research, it is therefore pertinent to revisit the state of nursing research in the country. .... platforms, updated libraries with electronic resource ... benchmarks for developing countries of 26%, [17] the amount is still ...

Time functions revisited

Science.gov (United States)

Fathi, Albert

2015-07-01

In this paper we revisit our joint work with Antonio Siconolfi on time functions. We will give a brief introduction to the subject. We will then show how to construct a Lipschitz time function in a simplified setting. We will end with a new result showing that the Aubry set is not an artifact of our proof of existence of time functions for stably causal manifolds.

Crystal structure, solvothermal synthesis, thermogravimetric studies and DFT calculations of a five-coordinate cobalt(II) compound based on the N,N-bis-(2-hy-droxy-eth-yl)glycine anion.

Science.gov (United States)

Zhou, Yanling; Liu, Xianrong; Wang, Qijun; Wang, Lisheng; Song, Baoling

2016-10-01

The reaction of CoCl 2 ·6H 2 O, N , N -bis-(2-hy-droxy-eth-yl)glycine and tri-ethyl-amine (Et 3 N) in ethanol solution under solvothermal conditions produced crystals of [ N , N -bis-(2-hy-droxy-eth-yl)glycinato]chloridocobalt(II), [Co(C 6 H 12 NO 4 )Cl]. The Co II ion is coordinated in a slightly distorted trigonal-bipyramidal environment which is defined by three O atoms occupying the equatorial plane and the N and Cl atoms in the apical sites. In the crystal, two types of O-H⋯O hydrogen bonds connect the mol-ecules, forming a two-dimensional network parallel to (001). The mol-ecular structure of the title compound confirms the findings of FTIR, elemental analysis, ESI-MS analysis and TG analysis. By using the density functional theory (DFT) (B3LYP) method with 6-31G(d) basis set, the molecular structure has been calculated and optimized.

Facile synthesis of morphology-controlled Co3O4 nanostructures through solvothermal method with enhanced catalytic activity for H2O2 electroreduction

Science.gov (United States)

Cheng, Kui; Cao, Dianxue; Yang, Fan; Xu, Yang; Sun, Gaohui; Ye, Ke; Yin, Jinling; Wang, Guiling

2014-05-01

Hydrogen peroxide (H2O2) replaced oxygen (O2) as oxidant has been widely investigated due to its faster reduction kinetics, easier storage and handling than gaseous oxygen. The main challenge of using H2O2 as oxidant is the chemical decomposition. In this article, by using different C2H5OH/H2O volume ratio as the solvent, Co3O4 with different morphologies (nanosheet, nanowire, ultrafine nanowire net, nanobelts, and honeycomb-like) direct growth on Ni foam are synthesized via a simple solvothermal method for the first time. Results show that the introduction of ethanol could obviously improve the catalytic performance toward H2O2 electroreduction. The sample prepared in the solution with the C2H5OH/H2O volume ratio of 1:2 shows the best catalytic performance among the five samples and a current density of 0.214 A cm-2 is observed in 3.0 mol L-1 KOH + 0.5 mol L-1 H2O2 at -0.4 V (vs. Ag/AgCl KCl), which is much larger than that on the other metal oxides reported previously, almost comparable with the precious metals. This electrode of Co3O4 directly grown on Ni foam has superior mass transport property, which combining with its low-cost and facile preparation, make it a promising electrode for fuel cell using H2O2 as the oxidant.

Immobilizing ternary Zn{sub X}Cd{sub 1−X}S on graphene via solvothermal method for enhanced photoelectric properties

Energy Technology Data Exchange (ETDEWEB)

Lei, Yun, E-mail: leiyun@whut.edu.cn; Chen, Feifei; Xu, Jun

2015-12-01

Graphical abstract: - Highlights: • Composition-tunable Zn{sub X}Cd{sub 1−X}S-graphene were prepared with a one-step solvothermal process by varying Zn/Cd ratios. • The diffraction peaks move to higher angle and UV–vis spectra present a progressive blue-shift with the increase of x value. • A more efficient separation of photo-induced carriers and a faster interfacial charge transfer occurs on graphene-Zn{sub 0.8}Cd{sub 0.2}S. - Abstract: Ternary Zn{sub X}Cd{sub 1−X}S particles were directly immobilized on graphene sheets by a facile solvothermal route with zinc acetate, cadmium acetate and thiourea as precursors, ethylene glycol as reaction solvent and graphene oxide as support. The value of x could be adjusted by controlling the molar ratio of Zn and Cd precursors. The products were characterized by X-ray diffraction, scanning electron microscope and ultraviolet–visible absorption. The photoelectric properties of the graphene-Zn{sub X}Cd{sub 1−X}S composites were investigated by transient photocurrent responses and electrochemical impedance spectra, and the results show that the obvious increase in the photocurrent density and decrease in electron-transfer resistance can be seen for graphene-Zn{sub 0.8}Cd{sub 0.2}S composites as compared to graphene-Zn{sub X}Cd{sub 1−X}S composites with other Zn/Cd ratios.

Preparation of low valent technetium metal-metal bonded species via solvothermal reduction of pertechnetate salts

International Nuclear Information System (INIS)

Kerlin, W.M.; Poineau, F.; Forster, P.M.; Czerwinski, K.R.; Sattelberger, A.P.

2013-01-01

A new one-step solvothermal synthesis route for reduction of pertechnetate salts to low valent technetium metal-metal bonded dimers will be presented. The reaction of potassium pertechnetate with glacial acetic acid plus either halo acids or halo salts under in-situ hydrogen production by sodium borohydride at various temperatures yields multiple products consisting of tetraacetate Tc-Tc (II,III) and Tc-Tc (III,III) paddle wheel dimers. Solid products isolated and analyzed via Single Crystal X-ray Diffraction (SC-XRD) in these reactions consist of polymeric chains Tc 2 +5 core: Tc 2 (μ-O 2 CCH 3 ) 4 (O 2 CCH 3 ), Tc 2 (μ-O 2 CCH 3 ) 4 Cl, Tc 2 (μ-O 2 CCH 3 ) 4 Br, Tc 2 (μ-O 2 CCH 3 ) 4 I, molecular Tc 2 +5 core: Tc 2 (μ-O 2 CCH 3 ) 3 Cl 2 (H 2 O) 2 ·H 2 O, K[Tc 2 (μ-O 2 CCH 3 ) 4 Br 2 ], and molecular Tc 2 +6 core: Tc 2 (μ-O 2 CCH 3 ) 4 Cl 2 , Tc 2 (μ-O 2 CCH 3 ) 4 Br 2 . Of the compounds listed, four are newly discovered using the one-step technique and two more additions to crystal database. Additional spectroscopic (X-ray Absorbance Fine Structure, UV-Vis, and FT-IR) characterization of the new compounds will be shown and used to propose a mechanism. Analysis of the mother liquor of each reaction by UV-Vis and formation of crystals over time due to oxidation of solutions affords a possible insight into mechanism of the Tc 2 +5 to Tc 2 +6 core formation. The oxidation states of Tc-Tc dimers formed is also dependent on temperature and pH of the starting solutions and will be explained in extensive detail. These one step reactions of reducing Tc(VII) to low valent technetium provides high yield intermediates for potential waste forms, use in nuclear fuel cycle separations, and radiopharmaceuticals. (author)

Preparation of flower-like CuS by solvothermal method for photocatalytic, UV protection and EMI shielding applications

Energy Technology Data Exchange (ETDEWEB)

Hu, Xiao-Sai; Shen, Yong, E-mail: shenyong@sues.edu.cn; Xu, Li-Hui; Wang, Li-Ming; Lu, Li-sha; Zhang, Ya-ting

2016-11-01

Highlights: • The flower-like CuS was synthesized by a facil solvothermal method. • The as-prepared flower-like CuS showed better solar light-driven photocatalytic activity. • The as-prepared CuS could act as a novel UV blocker. • The flower-like CuS potentially hold promise as electromagnetic shielding material. - Abstract: The flower-like CuS hierarchical structures were synthesized by solvothermal method. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared(FTIR) spectroscopy, UV–vis optical absorption spectroscopy and thermogravimetric analysis (TGA). The results demonstrated that the as-prepared flower-like CuS with the diameter of 1–5 um was pure hexagonal phase CuS and had well-defined flower-like structures. (1) The as-prepared CuS was proved to possess high photocatalytic performance with band gap of 1.45 eV. The degradation rate of Methylene blue (MB) was up to, 98.26%, 100% after 30 min under UV and visible irradiation. (2)The UPF of cotton fabric treated with CuS reached up to 174 compared with the original untreated fabric with the UPF 20.62. (3) The electromagnetic interference shielding effectiveness (EMI SE) of CuS coating was up to 27–31 dB when the content of CuS increased to 28.6%wt in the frequency of 300 KHz–3 GHz. Furthermore, the influence of reaction conditions on the morphology of the as-prepared CuS was investigated systematically and the possible formation mechanism of the CuS hierarchical structure was also proposed.

Solvothermal synthesis of stable nanoporous polymeric bases-crystalline TiO2 nanocomposites: visible light active and efficient photocatalysts for water treatment.

Science.gov (United States)

Liu, Fujian; Kong, Weiping; Wang, Liang; Noshadi, Iman; Zhang, Zhonghua; Qi, Chenze

2015-02-27

Visible light active and stable nanoporous polymeric base-crystalline TiO2 nanocomposites were solvothermally synthesized from in situ copolymerization of divinylbenzene (DVB) with 1-vinylimidazolate (VI) or 4-vinylpyridine (Py) in the presence of tetrabutyl titanate without the use of any other additives (PDVB-VI-TiO2-x, PDVB-Py-TiO2-x, where x stands for the molar ratio of TiO2 to VI or Py), which showed excellent activity with respect to catalyzing the degradation of organic pollutants of p-nitrophenol (PNP) and rhodamine-B (RhB). TEM and SEM images show that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x have abundant nanopores, and TiO2 nanocrystals with a high degree of crystallinity were homogeneously embedded in the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x, forming a stable 'brick-and-mortar' nanostructure. PDVB-VI and PDVB-Py supports act as the glue linking TiO2 nanocrystals to form nanopores and constraining the agglomeration of TiO2 nanocrystals. XPS spectra show evidence of unique interactions between TiO2 and basic sites in these samples. UV diffuse reflectance shows that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x exhibit a unique response to visible light. Catalytic tests show that the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were active in catalyzing the degradation of PNP and RhB organic pollutants under visible light irradiation. The enhanced activities of the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were ascribed to synergistic effects between abundant nanopores and the unique optical adsorption of visible light in the samples.

Solvothermal synthesis of stable nanoporous polymeric bases-crystalline TiO2 nanocomposites: visible light active and efficient photocatalysts for water treatment

Science.gov (United States)

Liu, Fujian; Kong, Weiping; Wang, Liang; Noshadi, Iman; Zhang, Zhonghua; Qi, Chenze

2015-02-01

Visible light active and stable nanoporous polymeric base-crystalline TiO2 nanocomposites were solvothermally synthesized from in situ copolymerization of divinylbenzene (DVB) with 1-vinylimidazolate (VI) or 4-vinylpyridine (Py) in the presence of tetrabutyl titanate without the use of any other additives (PDVB-VI-TiO2-x, PDVB-Py-TiO2-x, where x stands for the molar ratio of TiO2 to VI or Py), which showed excellent activity with respect to catalyzing the degradation of organic pollutants of p-nitrophenol (PNP) and rhodamine-B (RhB). TEM and SEM images show that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x have abundant nanopores, and TiO2 nanocrystals with a high degree of crystallinity were homogeneously embedded in the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x, forming a stable ‘brick-and-mortar’ nanostructure. PDVB-VI and PDVB-Py supports act as the glue linking TiO2 nanocrystals to form nanopores and constraining the agglomeration of TiO2 nanocrystals. XPS spectra show evidence of unique interactions between TiO2 and basic sites in these samples. UV diffuse reflectance shows that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x exhibit a unique response to visible light. Catalytic tests show that the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were active in catalyzing the degradation of PNP and RhB organic pollutants under visible light irradiation. The enhanced activities of the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were ascribed to synergistic effects between abundant nanopores and the unique optical adsorption of visible light in the samples.

Revisiting tourist behavior via destination brand worldness

Directory of Open Access Journals (Sweden)

Murat Kayak

2016-11-01

Full Text Available Taking tourists’ perspective rather than destination offerings as its core concept, this study introduces “perceived destination brand worldness” as a variable. Perceived destination brand worldness is defined as the positive perception that a tourist has of a country that is visited by tourists from all over the world. Then, the relationship between perceived destination brand worldness and intention to revisit is analyzed using partial least squares regression. This empirical study selects Taiwanese tourists as its sample, and the results show that perceived destination brand worldness is a direct predictor of intention to revisit. In light of these empirical findings and observations, practical and theoretical implications are discussed.

Zeolite Y: Synthesis, Modification, and Properties—A Case Revisited

Directory of Open Access Journals (Sweden)

Wolfgang Lutz

2014-01-01

Full Text Available Y zeolites dealuminated by steaming were introduced as fluid-cracking catalysts in the year 1970. Extensive research has been done to develop suitable dealumination techniques, to investigate crystal structure, and to characterize catalytic behaviour. However, the origin of the secondary pore system formed in the zeolite structure during dealumination process remained completely obscure over a period of four decades. Open questions concerned also the existence of extraframework siliceous admixture in addition to extraframework aluminium species which can dramatically change the catalytic properties of these zeolites. This paper gives a review on the synthesis of DAY materials and provides some answers to several open questions.

Revisiting the safety of aspartame.

Science.gov (United States)

Choudhary, Arbind Kumar; Pretorius, Etheresia

2017-09-01

Aspartame is a synthetic dipeptide artificial sweetener, frequently used in foods, medications, and beverages, notably carbonated and powdered soft drinks. Since 1981, when aspartame was first approved by the US Food and Drug Administration, researchers have debated both its recommended safe dosage (40 mg/kg/d) and its general safety to organ systems. This review examines papers published between 2000 and 2016 on both the safe dosage and higher-than-recommended dosages and presents a concise synthesis of current trends. Data on the safe aspartame dosage are controversial, and the literature suggests there are potential side effects associated with aspartame consumption. Since aspartame consumption is on the rise, the safety of this sweetener should be revisited. Most of the literature available on the safety of aspartame is included in this review. Safety studies are based primarily on animal models, as data from human studies are limited. The existing animal studies and the limited human studies suggest that aspartame and its metabolites, whether consumed in quantities significantly higher than the recommended safe dosage or within recommended safe levels, may disrupt the oxidant/antioxidant balance, induce oxidative stress, and damage cell membrane integrity, potentially affecting a variety of cells and tissues and causing a deregulation of cellular function, ultimately leading to systemic inflammation. © The Author(s) 2017. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Revisiting Inter-Genre Similarity

DEFF Research Database (Denmark)

Sturm, Bob L.; Gouyon, Fabien

2013-01-01

We revisit the idea of ``inter-genre similarity'' (IGS) for machine learning in general, and music genre recognition in particular. We show analytically that the probability of error for IGS is higher than naive Bayes classification with zero-one loss (NB). We show empirically that IGS does...... not perform well, even for data that satisfies all its assumptions....

A Hydrostatic Paradox Revisited

Science.gov (United States)

Ganci, Salvatore

2012-01-01

This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

THE INFLUENCE OF DESTINATION IMAGE AND TOURIST SATISFACTION TOWARD REVISIT INTENTION OF SETU BABAKAN BETAWI CULTURAL VILLAGE

OpenAIRE

Wibowo, Setyo Ferry; Sazali, Adnan; Kresnamurti R. P., Agung

2016-01-01

The purpose of this research are: 1) To find out the description of destination image, tourist satisfaction, and revisit intention of Betawi cultural village Setu Babakan, 2) test empirically the influence of destination image toward revisit intention of Betawi cultural village Setu Babakan, 3) test empirically the influence of tourist satisfaction toward revisit intention of Betawi cultural village Setu Babakan, 4) test empirically the influence of destination image toward revisit intention ...

Seven Issues, Revisited

OpenAIRE

Whitehead, Jim; De Bra, Paul; Grønbæk, Kaj; Larsen, Deena; Legget, John; schraefel, monica m.c.

2002-01-01

It has been 15 years since the original presentation by Frank Halasz at Hypertext'87 on seven issues for the next generation of hypertext systems. These issues are: Search and Query Composites Virtual Structures Computation in/over hypertext network Versioning Collaborative Work Extensibility and Tailorability Since that time, these issues have formed the nucleus of multiple research agendas within the Hypertext community. Befitting this direction-setting role, the issues have been revisited ...

'Felson Signs' revisited

International Nuclear Information System (INIS)

George, Phiji P.; Irodi, Aparna; Keshava, Shyamkumar N.; Lamont, Anthony C.

2014-01-01

In this article we revisit, with the help of images, those classic signs in chest radiography described by Dr Benjamin Felson himself, or other illustrious radiologists of his time, cited and discussed in 'Chest Roentgenology'. We briefly describe the causes of the signs, their utility and the differential diagnosis to be considered when each sign is seen. Wherever possible, we use CT images to illustrate the basis of some of these classic radiographic signs.

THE INFLUENCE OF DESTINATION IMAGE AND TOURIST SATISFACTION TOWARD REVISIT INTENTION OF SETU BABAKAN BETAWI CULTURAL VILLAGE

Directory of Open Access Journals (Sweden)

Setyo Ferry Wibowo

2016-04-01

Full Text Available The purpose of this research are: 1 To find out the description of destination image, tourist satisfaction, and revisit intention of Betawi cultural village Setu Babakan, 2 test empirically the influence of destination image toward revisit intention of Betawi cultural village Setu Babakan, 3 test empirically the influence of tourist satisfaction toward revisit intention of Betawi cultural village Setu Babakan, 4 test empirically the influence of destination image toward revisit intention of Betawi cultural village Setu Babakan. The object of this research was 200 respondents who have ever visit to Betawi cultural village Setu Babakan at one time. The results of descriptive test explained that the destination image provided is good according to the tourist, so that the tourist is satisfied and want to revisit intention of Betawi cultural village Setu Babakan. The hypothesis test shows: 1 the influence of destination image toward revisit intention by -30%, 2 the influence of tourist satisfaction toward revisit intention by 118%, 3 the influence of destination image toward tourist satisfaction by 92%.

Raman scattering investigation of Bi2Te3 hexagonal nanoplates prepared by a solvothermal process in the absence of NaOH

International Nuclear Information System (INIS)

Liang Yujie; Wang Wenzhong; Zeng Baoqing; Zhang Guling; Huang Jing; Li Jin; Li Te; Song Yangyang; Zhang Xiuyu

2011-01-01

Research highlights: → Hexagonal Bi 2 Te 3 thin nanoplates were synthesized by a simple solvothermal method. → Optical properties of the nanoplates were investigated by micro-Raman spectroscopy. → Infrared (IR) active mode (A 1u ) is greatly activated in Raman scattering spectrum. → Infrared (IR) active mode (A 1u ) shows up in Raman spectrum of hexagonal nanoplates. → Raman spectrum clearly shows crystal symmetry breaking of hexagonal nanoplates. - Abstract: Hexagonal Bi 2 Te 3 nanoplates were synthesized by a simple solvothermal process in the absence of NaOH. The composition, morphology and size of the as-prepared products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Raman scattering optical properties of the as-prepared Bi 2 Te 3 nanoplates were investigated by micro-Raman spectroscopy. The Raman spectrum shows that infrared (IR) active mode (A 1u ), which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is greatly activated and shown up clearly in Raman scattering spectrum. We attribute the appearance of infrared active (A 1u ) in Raman spectrum to crystal symmetry breaking of Bi 2 Te 3 hexagonal nanoplates. The as-grown Bi 2 Te 3 hexagonal nanoplates, exhibiting novel Raman optical properties compared with bulk crystals, may find potential applications in thermoelectric devices.

Solvothermal syntheses and characterization of three new silver(I)/copper(I)-thioarsenates based on As{sup 2+}/As{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Yao, Hua-Gang, E-mail: hgyao@gdpu.edu.cn [School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458 (China); Guangdong Cosmetics Engineering & Technology Research Center, Zhongshan 528458 (China); Tang, Cheng-Fei [School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458 (China); An, Yong-Lin [Department of Chemistry, Dalian University of Technology, Dalian 116024 (China); Ou, Zi-Jian; Wu, Guo-Hao; Lan, Pei; Zheng, Yi-Long [School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458 (China)

2017-02-15

Three new silver(I)/copper(I)-thioarsenates KAgAs{sup II}S{sub 2} (1), RbCu{sub 2}As{sup III}S{sub 3} (2) and RbCu{sub 4}As{sup III}S{sub 4} (3) have been solvothermally synthesized and structurally characterized. 1 exhibits a two-dimensional anionic network built up by As−As bond connecting the left- and right-handed helical [AgS{sub 2}]{sup 4−} chains, and represents the first examples of thioarsenates(II). The structure of 2 consists of two kinds of helical [Cu{sub 2}S{sub 3}]{sup 4–} chains linked by the arsenic atoms to form double layers with rubidium ions between the layers. Compound 3 is built up of infinite [Cu{sub 2}S{sub 2}]{sup 2–} chain and layered [Cu{sub 6}As{sub 2}S{sub 6}] linked to form a three-dimensional anionic framework, [Cu{sub 4}AsS{sub 4}]{sup –}, and containing channels in which the rubidium cations reside. The optical properties of 1–3 have been investigated by UV–vis spectroscopy. - Graphical abstract: Three new silver(I)/copper(I)-thioarsenates have been solvothermally synthesized and structurally characterized. 1 represents the first examples of thioarsenates(II) while compounds 2 and 3 possess noncondensed pyramidal AsS{sub 3}{sup 3–} unit.

Leadership and Management Theories Revisited

DEFF Research Database (Denmark)

Madsen, Mona Toft

2001-01-01

The goal of the paper is to revisit and analyze key contributions to the understanding of leadership and management. As a part of the discussion a role perspective that allows for additional and/or integrated leader dimensions, including a change-centered, will be outlined. Seemingly, a major...

Structure-directing effects of ionic liquids in the ionothermal synthesis of metal–organic frameworks

Directory of Open Access Journals (Sweden)

Thomas P. Vaid

2017-07-01

Full Text Available Traditional synthesis of metal–organic frameworks (MOFs involves the reaction of a metal-containing precursor with an organic linker in an organic solvent at an elevated temperature, in what is termed a `solvothermal' reaction. More recently, many examples have been reported of MOF synthesis in ionic liquids (ILs, rather than an organic solvent, in `ionothermal' reactions. The high concentration of both cations and anions in an ionic liquid allows for the formation of new MOF structures in which the IL cation or anion or both are incorporated into the MOF. Most commonly, the IL cation is included in the open cavities of the MOF, countering the anionic charge of the MOF framework itself and acting as a template around which the MOF structure forms. Ionic liquids can also serve other structure-directing roles, for example, when an IL containing a single enantiomer of a chiral anion leads to a homochiral MOF, even though the IL anion is not itself incorporated into the MOF. A comprehensive review of ionothermal syntheses of MOFs, and the structure-directing effects of the ILs, is given.

Schroedinger's variational method of quantization revisited

International Nuclear Information System (INIS)

Yasue, K.

1980-01-01

Schroedinger's original quantization procedure is revisited in the light of Nelson's stochastic framework of quantum mechanics. It is clarified why Schroedinger's proposal of a variational problem led us to a true description of quantum mechanics. (orig.)

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

Soft chemistry has emerged as an important means of generating nanocrystals, nanowires and other nanostructures of semiconducting materials. We describe the synthesis of CdS and other metal chalcogenide nanocrystals by a solvothermal route. We also describe the synthesis of nanocrystals of AlN, GaN and InN by the ...

A novel solvothermal route for obtaining strontium titanate nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Marquez-Herrera, A., E-mail: alfredo.marquez@uaslp.mx [Universidad Autonoma de San Luis Potosi, Departamento de Ingenieria Mecanica Administrativa, Coordinacion Academica Region Altiplano (COARA) (Mexico); Ovando-Medina, Victor M.; Corona-Rivera, Miguel A. [Universidad Autonoma de San Luis Potosi, Departamento de Ingenieria Quimica, Coordinacion Academica Region Altiplano (COARA) (Mexico); Hernandez-Rodriguez, E.; Zapata-Torres, M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria IPN (Mexico); Campos-Gonzalez, E.; Guillen-Cervantes, A.; Zelaya-Angel, O.; Melendez-Lira, M. [CINVESTAV-IPN, Departamento de Fisica (Mexico)

2013-04-15

Strontium titanate (SrTiO{sub 3}) has attracted a lot of attention because of its possible applications in new microelectronic devices. It is a material with a high dielectric constant, low leakage current, and some of its properties can be changed by adding or modifying the concentration of a dopant, which can be used for a wide range of functional purposes, from simple capacitors to complicated microwave devices. Therefore, in this work, we report the development of a new route to synthesize SrTiO{sub 3} nanoparticles based on the solvothermal method by employing two precursor solutions: strontium chloride and titanium(IV) butoxide. Our route allows the production of cubic SrTiO{sub 3} nanoparticles with a narrow size distribution. The particle sizes range between 8 and 24 nm, forming agglomerates of SrTiO{sub 3} in the range of 128-229 nm. It was demonstrated that the Ti/Sr molar ratio employed into the precursor solution has an important effect onto the chemical composition of the resulting SrTiO{sub 3} nanoparticles: when using Ti/Sr < 1, the formation and incorporation of the SrCO{sub 3} compound into the nanoparticles was observed while with Ti/Sr {>=} 1 nanoparticles are free of contaminants. The as-prepared nanoparticles were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, high-resolution TEM, selected area electron diffraction, scanning electron microscopy, and dynamic light scattering.

Controlling the morphology and properties of solvothermal synthesized Cu2ZnSnS4 nanoparticles by solvent type

International Nuclear Information System (INIS)

Bahramzadeh, Saeid; Abdizadeh, Hossein; Golobostanfard, Mohammad Reza

2015-01-01

Highlights: • CZTS nanoparticles are fabricated by solvothermal method with different solvents. • Different morphologies are achieved by EDA, TETA, EG, and OA solvents. • Property and chelating ability of the solvents have a key role on nanoparticles formation. • TETA and OA are strongly recommended for solar cell applications. - Abstract: The copper–zinc–tin sulfide Cu 2 ZnSnS 4 (CZTS) semiconductors are recently considered as one of the favorable materials for application as absorber layers in solar cells due to their appropriate direct band gap energy and high optical absorption coefficient. In this study, the effect of solvent type on properties of solvothermal synthesized CZTS nanoparticles has been investigated. Ethylenediamine (EDA), triethylenetetramine (TETA), ethylene glycol (EG), and oleic acid (OA) have been used as the solvent. X-ray diffraction technique and Raman spectroscopy confirmed the formation of crystalline CZTS nanoparticles with kesterite crystal structure in these solvents with the exception of EDA, which forms wurtzite crystal structure. Morphological characterizations show that several distinct morphologies including spherical (70–160 nm), nanoplates (∼45 nm thickness and more than 1 μm length), peculiar flower-like particles (with diameter of ∼0.4–1.5 μm), truncated hexagonal disks, irregular particles, and hexagonal microdisks are obtained by varying the solvent type. Optical studies revealed broad absorption of the CZTS particles in the visible region. Compared with other solvents, OA synthesized CZTS particles show higher absorption in the visible region. However, CZTS nanoparticles synthesized by TETA solvent show the most appropriate properties for application as an absorber materials in solar cells due to high crystallinity, low impurity phases, suitable size, and proper band gap energy

Controllable synthesis of TiO2 nanomaterials by assisting with l-cysteine and ethylenediamine

KAUST Repository

Tao, Yugui

2013-11-21

This paper reports a facile l-cysteine-assisted solvothermal synthesis of TiO2 nanomaterials using ethylenediamine (En) and distilled water as solvent. The influence of reaction time, temperature, l-cysteine and solvent was initially investigated. Results demonstrated the reaction temperature, l-cysteine and En significantly imposed impact on the phase and morphology of the particles. Amorphous nanosheets, mixed-crystal nanorods and pure anatase nanoparticles were controllably synthesized by varying reaction temperature. The formation of the amorphous nanosheets and mixed-crystal nanorods were directly affected by the presence of l-cysteine and En. And the presence of En distinctly affected the crystal phase of the products, which was rarely mentioned in other studies. Moreover, the photocatalytic activities of three typical samples were excellent. The possible formation mechanism of the sample was also discussed. © 2013 Springer Science+Business Media New York.

Controllable synthesis of TiO2 nanomaterials by assisting with l-cysteine and ethylenediamine

KAUST Repository

Tao, Yugui; Cao, Ning; Pan, Jun; Sun, Yichen; Jin, Cheng; Song, Yang

2013-01-01

This paper reports a facile l-cysteine-assisted solvothermal synthesis of TiO2 nanomaterials using ethylenediamine (En) and distilled water as solvent. The influence of reaction time, temperature, l-cysteine and solvent was initially investigated. Results demonstrated the reaction temperature, l-cysteine and En significantly imposed impact on the phase and morphology of the particles. Amorphous nanosheets, mixed-crystal nanorods and pure anatase nanoparticles were controllably synthesized by varying reaction temperature. The formation of the amorphous nanosheets and mixed-crystal nanorods were directly affected by the presence of l-cysteine and En. And the presence of En distinctly affected the crystal phase of the products, which was rarely mentioned in other studies. Moreover, the photocatalytic activities of three typical samples were excellent. The possible formation mechanism of the sample was also discussed. © 2013 Springer Science+Business Media New York.

A practical method of predicting client revisit intention in a hospital setting.

Science.gov (United States)

Lee, Kyun Jick

2005-01-01

Data mining (DM) models are an alternative to traditional statistical methods for examining whether higher customer satisfaction leads to higher revisit intention. This study used a total of 906 outpatients' satisfaction data collected from a nationwide survey interviews conducted by professional interviewers on a face-to-face basis in South Korea, 1998. Analyses showed that the relationship between overall satisfaction with hospital services and outpatients' revisit intention, along with word-of-mouth recommendation as intermediate variables, developed into a nonlinear relationship. The five strongest predictors of revisit intention were overall satisfaction, intention to recommend to others, awareness of hospital promotion, satisfaction with physician's kindness, and satisfaction with treatment level.

Surfactant-assisted solvothermal preparation of submicrometer-sized hollow hematite particles and their photocatalytic activity

International Nuclear Information System (INIS)

Lian Suoyuan; Wang Enbo; Gao Lei; Wu Di; Song Yanli; Xu Lin

2006-01-01

Submicrometer-sized hollow hematite particles were prepared through a surfactant-assisted solvothermal process. The amount of FeCl 3 .H 2 O and cetyltrimethylammonium bromide, and the acidity of the solution were systematically altered to study their effects on the final results. Hollow hematite particles with shapes from sphere, ellipsoid to peanut were obtained. Their sizes range from 500 nm to 2 μm with shell thickness from 100 to 500 nm. Powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction were applied to investigate the products' crystallinity, purity, morphology, size and structural features. Finally, the study on the photocatalysis of Fe 2 O 3 for the destruction of diethyl phthalate in water was carried out. The result proved that Fe 2 O 3 hollow particles were effective photocatalysts for the degradation of DEP, with 96.8% destruction ratio being obtained within 60 min

Upconversion study of singly activator ions doped La2O3 nanoparticle synthesized via optimized solvothermal method

Science.gov (United States)

Tiwari, S. P.; Singh, S.; Kumar, A.; Kumar, K.

2016-05-01

In present work, an optimized solvothermal method has been chosen to synthesize the singly doped Er3+ activator ions with La2O3 host matrix. The sample is annealed at 500 °C in order to remove the moisture and other organic impurities. The sample is characterized by using XRD and FESEM to find out the phase and surface morphology. The observed particle size is found almost 80 nm with spherical agglomerated shape. Upconversion spectra are recorded at room temperature using 976 nm diode laser excitation sources and consequently the emission peaks in green and red region are observed. The color coordinate diagram shows the results that the present material may be applicable in different light emitting sources.

Structural, optical and magnetic studies of CuFe2O4, MgFe2O4 and ZnFe2O4 nanoparticles prepared by hydrothermal/solvothermal method

Science.gov (United States)

Kurian, Jessyamma; Mathew, M. Jacob

2018-04-01

In this paper we report the structural, optical and magnetic studies of three spinel ferrites namely CuFe2O4, MgFe2O4 and ZnFe2O4 prepared in an autoclave under the same physical conditions but with two different liquid medium and different surfactant. We use water as the medium and trisodium citrate as the surfactant for one method (Hydrothermal method) and ethylene glycol as the medium and poly ethylene glycol as the surfactant for the second method (solvothermal method). The phase identification and structural characterization are done using XRD and morphological studies are carried out by TEM. Cubical and porous spherical morphologies are obtained for hydrothermal and solvothermal process respectively without any impurity phase. The optical studies are carried out using FTIR and UV-Vis reflectance spectra. In order to elucidate the nonlinear optical behaviour of the prepared nanomaterial, open aperture z-scan technique is used. From the fitted z-scan curves nonlinear absorption coefficient and the saturation intensity are determined. The magnetic characterization of the samples is performed at room temperature using vibrating sample magnetometer measurements. The M-H curves obtained are fitted using theoretical equation and the different components of magnetization are determined. Nanoparticles with high saturation magnetization are obtained for MgFe2O4 and ZnFe2O4 prepared under solvothermal reaction. The magnetic hyperfine parameters and the cation distribution of the prepared materials are determined using room temperature Mössbauer spectroscopy. The fitted spectra reveal the difference in the magnetic hyperfine parameters owing to the change in size and morphology.

Synthesis and electrochemical properties of ZnMn_2O_4 anode for lithium-ion batteries

International Nuclear Information System (INIS)

Feng, Chuanqi; Wang, Wei; Chen, Xiao; Wang, Shiquan; Guo, Zaiping

2015-01-01

Graphical abstract: ZnMn_2O_4 nanoparticles were prepared through the rheological phase reaction method (R-ZMO) or the mixed solvothermal method(M-ZMO). The particles of M-ZMO were clustered together to form uniform microspheres morphology. The M-ZMO behaved higher reversible capacity and better cycle performance than that of R-ZMO. - Highlights: • ZnMn_2O_4 nanoparticles were prepared through the rheological phase reaction method (R-ZMO) or the mixed solvothermal method (M-ZMO). • The M-ZMO behaved higher reversible capacity and better cycle performance than that of R-ZMO. • The morphology and cell parameters of ZnMn_2O_4 are important effects on its electrochemical properties. • The diffusion coefficient of Li"+ in M-ZMO is beneficial for M-ZMO to be used an anode. - Abstract: The precursors of ZnMn_2O_4 were synthesized by different methods (the rheological phase reaction method or the mixed solvothermal method). The precursors were heat-treated at a suitable temperature to obtain the expected product (ZnMn_2O_4). The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the samples were also investigated. The results show that ZnMn_2O_4 was synthesized successfully. The particles of ZnMn_2O_4 were irregular quasi-spheres with sizes of about 50 nm. The ZnMn_2O_4 nanoparticles synthesized through the mixed solvothermal method were clustered together to form microspheres about 1 μm in diameter. The electrochemical testing results showed that the ZnMn_2O_4 synthesized through the mixed solvothermal method featured higher reversible capacity and better cycling performance than the sample synthesized by the rheological phase reaction method. The ZnMn_2O_4 synthesized through the mixed solvothermal method could be a promising anode material for lithium ion battery application.

One-pot solvothermal synthesis of Co{sub 1−x}Mn{sub x}C{sub 2}O{sub 4} and their application as anode materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Ang, Wei An Elijah [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute @ NTU (ERI-N), Nanyang Technological University, 50 Nanyang Drive, Singapore 637553 (Singapore); Cheah, Yan Ling; Wong, Chui Ling [Energy Research Institute @ NTU (ERI-N), Nanyang Technological University, 50 Nanyang Drive, Singapore 637553 (Singapore); Hng, Huey Hoon [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Madhavi, Srinivasan, E-mail: madhavi@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute @ NTU (ERI-N), Nanyang Technological University, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM CREATE Center for Electromobility, 1 CREATE Way, #10-02 CREATE Tower, Singapore 138602 (Singapore)

2015-07-25

Graphical abstract: MnC{sub 2}O{sub 4} exhibited good cycling stability while CoC{sub 2}O{sub 4} showed severe capacity fading phenomenon after 40 cycles. Notably, mixed solid solution having Co{sub 0.52}Mn{sub 0.48}C{sub 2}O{sub 4} composition improved the specific reversible discharge capacity to a stable value of ∼1000 mA h g{sup −1} (1 C-rate). - Highlights: • Mixed metal oxalates are synthesized by solvothermal method for the first time. • We control morphologies by varying solvent mixtures and transition metal types. • Li/Co{sub 0.52}Mn{sub 0.48}C{sub 2}O{sub 4} is the best capacity and rate-performing cell in this study. • The positive synergistic effect is attributed to optimal Co:Mn mole ratio. • Properties of Co give high capacity values while Mn give good cycling stability. - Abstract: A facile one-pot solvothermal route has been developed to synthesize phase pure M{sub x}C{sub 2}O{sub 4}⋅2H{sub 2}O (M = Mn, Co; 0 < x ⩽ 1) microstructures without employing any hard/soft template and their electrochemical performance in lithium-ion batteries has been systematically investigated. Morphology, microstructure and composition of the synthesized materials are characterized by field emission-scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Anhydrous micron-sized MnC{sub 2}O{sub 4} and CoC{sub 2}O{sub 4} exhibits specific reversible discharge capacity of ∼800 and 950 mA h g{sup −1} respectively, at 1 C-rate. MnC{sub 2}O{sub 4} exhibited good cycling stability while CoC{sub 2}O{sub 4} showed severe capacity fading phenomenon after 40 cycles, thereafter attaining 400–600 mA h g{sup −1} for all C-rates. Interestingly, mixed solid solution having Co{sub 0.52}Mn{sub 0.48}C{sub 2}O{sub 4} composition improved the specific reversible discharge capacity to a stable value of ∼1000 mA h g{sup −1} (1 C-rate), which is one of the highest reported values for such oxalates. The cycling stability of this

An Alternative Synthesis Route of LiFePO4-Carbon Composites for Li-Ion Cathodes

Directory of Open Access Journals (Sweden)

Yongbing Lou

2013-01-01

Full Text Available LiFePO4-Carbon (LFP/C composites with high purity and good crystallinity were prepared by an improved environmentally benign and low-cost solvothermal method. Capping agent polyvinylpyrrolidone (PVP and polyethylene glycol (PEG-400 showed no significant dispersive effect during the synthesis. These capping agents were converted into networking carbons after annealing, which consequently improved the charge and discharge performance. It was able to deliver a high initial discharge specific capacity of 154.1 mAh g−1 for sample prepared with PVP and 145.6 mAh g−1 for sample prepared with PEG-400 while having great capacity retention. The rate capability and cycling performance of LFP/C samples prepared with PVP or PEG-400 at high current rates were significantly improved compared to the LFP/C sample prepared without a capping agent.

The Faraday effect revisited: General theory

DEFF Research Database (Denmark)

Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse...

Revisited

DEFF Research Database (Denmark)

Tegtmeier, Silke; Meyer, Verena; Pakura, Stefanie

2017-01-01

were captured when they described entrepreneurs. Therefore, this paper aims to revisit gender role stereotypes among young adults. Design/methodology/approach: To measure stereotyping, participants were asked to describe entrepreneurs in general and either women or men in general. The Schein......Purpose: Entrepreneurship is shaped by a male norm, which has been widely demonstrated in qualitative studies. The authors strive to complement these methods by a quantitative approach. First, gender role stereotypes were measured in entrepreneurship. Second, the explicit notions of participants......: The images of men and entrepreneurs show a high and significant congruence (r = 0.803), mostly in those adjectives that are untypical for men and entrepreneurs. The congruence of women and entrepreneurs was low (r = 0.152) and insignificant. Contrary to the participants’ beliefs, their explicit notions did...

Solvothermal preparation of ZnO nanorods as anode material for improved cycle life Zn/AgO batteries.

Directory of Open Access Journals (Sweden)

Shafiq Ullah

Full Text Available Nano materials with high surface area increase the kinetics and extent of the redox reactions, thus resulting in high power and energy densities. In this study high surface area zinc oxide nanorods have been synthesized by surfactant free ethylene glycol assisted solvothermal method. The nanorods thus prepared have diameters in the submicron range (300 ~ 500 nm with high aspect ratio. They have uniform geometry and well aligned direction. These nanorods are characterized by XRD, SEM, Specific Surface Area Analysis, solubility in alkaline medium, EDX analysis and galvanostatic charge/discharge studies in Zn/AgO batteries. The prepared zinc oxide nanorods have low solubility in alkaline medium with higher structural stability, which imparts the improved cycle life stability to Zn/AgO cells.

Who should do the dishes now? Revisiting gender and housework in contemporary urban South Wales

OpenAIRE

Mannay, Dawn

2016-01-01

This chapter revisits Jane Pilcher’s (1994) seminal work ‘Who should do the dishes? Three generations of Welsh women talking about men and housework’, which was originally published in Our Sister’s Land: the changing identities of women in Wales. As discussed in the introductory chapter, I began revisiting classic Welsh studies as part of my doctoral study Mothers and daughters on the margins: gender, generation and education (Mannay, 2012); this lead to the later publication of a revisiting ...

The Faraday effect revisited: General theory

DEFF Research Database (Denmark)

Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

2006-01-01

This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. At zero temperature and zero frequency...

Highly biocompatible, nanocrystalline hydroxyapatite synthesized in a solvothermal process driven by high energy density microwave radiation

Directory of Open Access Journals (Sweden)

Smolen D

2013-02-01

Full Text Available Dariusz Smolen1, Tadeusz Chudoba1, Iwona Malka1, Aleksandra Kedzierska1, Witold Lojkowski1, Wojciech Swieszkowski2, Krzysztof Jan Kurzydlowski2, Malgorzata Kolodziejczyk-Mierzynska3, Malgorzata Lewandowska-Szumiel31Polish Academy of Science, Institute of High Pressure Physics, Warsaw, Poland; 2Faculty of Materials Engineering, Warsaw University of Technology, Warsaw, Poland; 3Department of Histology and Embryology, Center of Biostructure Research, Medical University of Warsaw, Warsaw, PolandAbstract: A microwave, solvothermal synthesis of highly biocompatible hydroxyapatite (HAp nanopowder was developed. The process was conducted in a microwave radiation field having a high energy density of 5 W/mL and over a time less than 2 minutes. The sample measurements included: powder X-ray diffraction, density, specific surface area, and chemical composition. The morphology and structure were investigated by scanning electron microscopy as well as transmission electron microscopy (TEM. The thermal behavior analysis was conducted using a simultaneous thermal analysis technique coupled with quadruple mass spectrometry. Additionally, Fourier transform infrared spectroscopy tests of heated samples were performed. A degradation test and a biocompatibility study in vitro using human osteoblast cells were also conducted. The developed method enables the synthesis of pure, fully crystalline hexagonal HAp nanopowder with a specific surface area close to 240 m2/g and a Ca/P molar ratio equal to 1.57. TEM measurements showed that this method results in particles with an average grain size below 6 nm. A 28-day degradation test conducted according to the ISO standard indicated a 22% loss of initial weight and a calcium ion concentration at 200 µmol/dm3 in the tris(hydroxymethylaminomethane hydrochloride test solution. The cytocompatibility of the obtained material was confirmed in a culture of human bone derived cells, both in an indirect test using the material

High performance of solvothermally prepared VO2(B as anode for aqueous rechargeable lithium batteries

Directory of Open Access Journals (Sweden)

Milošević Sanja

2015-01-01

Full Text Available The VO2 (B was synthesized via a simple solvothermal route at 160oC in ethanol. The initial discharge capacity of VO2 (B anode, in saturated aqueous solution of LiNO3, was 177 mAh g-1 at a current rate of 50 mA g-1. After 50 cycles capacity fade was 4%, but from 20th-50th cycle no capacity drop was observed. The VO2 (B has shown very good cyclability at current rate of even 1000 mA g-1 with initial discharge capacity of 92 mAh g-1. The excellent electrochemical performance of VO2 (B was attributed to the stability of micro-nano structures to repeated intercalation /deintercalation process, very good electronic conductivity as well as the very low charge transfer resistance in the aqueous electrolyte. [Projekat Ministarstva nauke Republike Srbije, br. III45014

Preparation of CuIn1-xGaxS2 (x = 0.5) flowers consisting of nanoflakes via a solvothermal method

International Nuclear Information System (INIS)

Liang Xiaojuan; Zhong Jiasong; Yang Fan; Hua Wei; Jin Huaidong; Liu Haitao; Sun Juncai; Xiang Weidong

2011-01-01

Highlights: → We report for the first time a small biomolecule-assisted route using L-cysteine as sulfur source and complexing agent to synthesis CuIn 0.5 Ga 0.5 S 2 crystals. → The possible mechanisms leading to CuIn 0.5 Ga 0.5 S 2 flowers consisting of nanoflakes were proposed. → In addition, the morphology, structure, and phase composition of the as-prepared CuIn 0.5 Ga 0.5 S 2 products were investigated in detail by XRD, FESEM, EDS, XPS, TEM (HRTEM) and SAED. - Abstract: CuIn 1-x Ga x S 2 (x = 0.5) flowers consisting of nanoflakes were successfully prepared by a biomolecule-assisted solvothermal route at 220 deg. C for 10 h, employing copper chloride, gallium chloride, indium chloride and L-cysteine as precursors. The biomolecule L-cysteine acting as sulfur source was found to play a very important role in the formation of the final product. The diameter of the CuIn 0.5 Ga 0.5 S 2 flowers was 1-2 μm, and the thickness of the flakes was about 15 nm. The obtained products were characterized by X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction spectroscopy (SAED), and UV-vis absorption spectroscopy. The influences of the reaction temperature, reaction time, sulfur source and the molar ratio of Cu-to-L-cysteine (reactants) on the formation of the target compound were investigated. The formation mechanism of the CuIn 0.5 Ga 0.5 S 2 flowers consisting of flakes was discussed.

Examining Relationships of Destination Image, Service Quality, e-WOM, and Revisit Intention to Sabang Island, Indonesia

Directory of Open Access Journals (Sweden)

Rangga Restu Prayogo

2016-12-01

Full Text Available The purpose of this research is to study the relationship among destination image, service quality, e-WOM, and revisit intentions in the tourism industry. A questionnaire given to tourists who visit one of the farrest island in western part of Indonesia, Sabang Island and using sampling through the convenience sampling. A structural equation model (SEM test with WarpPLS 3.0 was used to test the relationship between research variables. This research gathered from 150 respondents. The empirical results from PLS-SEM showed that; the destination image positive affect e-WOM and revisit intention; service quality affect e-WOM and revisit intention; e-WOM positive affect to revisit intention tourists. The implications and future research issues were discussed.

Solvothermal-assisted evaporation-induced self-assembly process for significant improvement in the textural properties of γ-Al2O3, and study dye adsorption efficiency

Directory of Open Access Journals (Sweden)

Sourav Ghosh

2015-06-01

Full Text Available A comparative study of the textural properties of γ-Al2O3 prepared by solvothermal-assisted evaporation-induced self-assembly (SA-EISA and conventional evaporation-induced self-assembly (EISA processes has been carried out using aluminum isopropoxide, triblock copolymer-type nonionic surfactant (Pluronic P123 and ethanol. The solvothermal reaction was carried out at 100 °C for 24 h followed by slow drying at 60 °C for 48 h. The synthesized products were characterized by thermogravimetry analysis (TGA, differential thermal analysis (DTA, X-ray diffraction (XRD analysis, N2 adsorption–desorption study and transmission electron microscopy (TEM. The γ-Al2O3 prepared by SA-EISA process became stable up to 1000 °C. The powder prepared by SA-EISA process resulted in a significant increase in textural properties (BET surface area, pore volume and pore diameter compared to that prepared by conventional EISA process. A better adsorption capacity for Congo red, a carcinogenic dye used in textile industry, was exhibited by the powders prepared by SA-EISA process. A proposed mechanism was illustrated for the formation of mesoporous γ-Al2O3 obtained by EISA and SA-EISA processes.

Deterministic Graphical Games Revisited

DEFF Research Database (Denmark)

Andersson, Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro

2008-01-01

We revisit the deterministic graphical games of Washburn. A deterministic graphical game can be described as a simple stochastic game (a notion due to Anne Condon), except that we allow arbitrary real payoffs but disallow moves of chance. We study the complexity of solving deterministic graphical...... games and obtain an almost-linear time comparison-based algorithm for computing an equilibrium of such a game. The existence of a linear time comparison-based algorithm remains an open problem....

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4) magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

Science.gov (United States)

Kalam, Abul; Al-Sehemi, Abdullah G.; Assiri, Mohammed; Du, Gaohui; Ahmad, Tokeer; Ahmad, Irfan; Pannipara, M.

2018-03-01

Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-visible (UV-vis) spectroscopy and N2 adsorption-desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590-619 cm-1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0-76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB) dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst.

Revisiting Hansen Solubility Parameters by Including Thermodynamics

NARCIS (Netherlands)

Louwerse, Manuel J; Fernández-Maldonado, Ana María; Rousseau, Simon; Moreau-Masselon, Chloe; Roux, Bernard; Rothenberg, Gadi

2017-01-01

The Hansen solubility parameter approach is revisited by implementing the thermodynamics of dissolution and mixing. Hansen's pragmatic approach has earned its spurs in predicting solvents for polymer solutions, but for molecular solutes improvements are needed. By going into the details of entropy

Bottomonium spectrum revisited

CERN Document Server

Segovia, Jorge; Entem, David R.; Fernández, Francisco

2016-01-01

We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about the better way to determine their properties experimentally.

Hospital revisit rate after a diagnosis of conversion disorder.

Science.gov (United States)

Merkler, Alexander E; Parikh, Neal S; Chaudhry, Simriti; Chait, Alanna; Allen, Nicole C; Navi, Babak B; Kamel, Hooman

2016-04-01

To estimate the hospital revisit rate of patients diagnosed with conversion disorder (CD). Using administrative data, we identified all patients discharged from California, Florida and New York emergency departments (EDs) and acute care hospitals between 2005 and 2011 with a primary discharge diagnosis of CD. Patients discharged with a primary diagnosis of seizure or transient global amnesia (TGA) served as control groups. Our primary outcome was the rate of repeat ED visits and hospital admissions after initial presentation. Poisson regression was used to compare rates between diagnosis groups while adjusting for demographic characteristics. We identified 7946 patients discharged with a primary diagnosis of CD. During a mean follow-up of 3.0 (±1.6) years, patients with CD had a median of three (IQR, 1-9) ED or inpatient revisits, compared with 0 (IQR, 0-2) in patients with TGA and 3 (IQR, 1-7) in those with seizures. Revisit rates were 18.25 (95% CI, 18.10 to 18.40) visits per 100 patients per month in those with CD, 3.90 (95% CI, 3.84 to 3.95) in those with TGA and 17.78 (95% CI, 17.75 to 17.81) in those with seizures. As compared to CD, the incidence rate ratio for repeat ED visits or hospitalisations was 0.89 (95% CI, 0.86 to 0.93) for seizure disorder and 0.32 (95% CI 0.31 to 0.34) for TGA. CD is associated with a substantial hospital revisit rate. Our findings suggest that CD is not an acute, time-limited response to stress, but rather that CD is a manifestation of a broader pattern of chronic neuropsychiatric disease. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

The Future of Engineering Education--Revisited

Science.gov (United States)

Wankat, Phillip C.; Bullard, Lisa G.

2016-01-01

This paper revisits the landmark CEE series, "The Future of Engineering Education," published in 2000 (available free in the CEE archives on the internet) to examine the predictions made in the original paper as well as the tools and approaches documented. Most of the advice offered in the original series remains current. Despite new…

development of a hydrothermal method to synthesize spherical znse

African Journals Online (AJOL)

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nanoparticles have a zinc blend structure and in a spherical form with ... optoelectronic devices such as blue-green laser diodes and turnable mid-IR ... Solvothermal methods have also been developed for the synthesis of ZnSe and CdSe. The.

Synthesis of manganese coordination polymer microspheres for lithium-ion batteries with good cycling performance

International Nuclear Information System (INIS)

Fei, Hailong; Liu, Xin; Li, Zhiwei; Feng, Wenjing

2015-01-01

Highlights: • We achieve controllable synthesis of manganese 2,5-thiophene dicarboxylate microspheres with DMF and CTABr. • We perform research on changes in morphologies and crystalline structure. • It is a new anode material for lithium-ion batteries with high capacity and good cycle stability. - Abstract: A simple and versatile method for preparation of novel manganese 2,5-thiophene dicarboxylate microspheres is developed via a surfactant-assisted solvo-thermal route, which are found to be a new high-energy anode material for lithium-ion batteries. It shows better cycling performance and higher discharge capacity than its counterpart of irregular shapes. A reversible capacity was achieved as high as 645.7 mA h g −1 after 250 cycles at a current density of 400 mA g −1 . Furthermore, the coulombic efficiency can be close to 100% even after 650 charge-discharge cycles at a current density of 500 mA g −1

Synthesis and characterization of pharmaceutical surfactant templated mesoporous silica: Its application to controlled delivery of duloxetine

Energy Technology Data Exchange (ETDEWEB)

Mani, Ganesh; Pushparaj, Hemalatha; Peng, Mei Mei; Muthiahpillai, Palanichamy [Department of Chemical Engineering, Hanseo University, Seosan-si 356 706 (Korea, Republic of); Udhumansha, Ubaidulla [Department of Chemical Engineering, Hanseo University, Seosan-si 356 706 (Korea, Republic of); Department of Pharmaceutics, C.L. Baid Metha College of Pharmacy, Chennai (India); Jang, Hyun Tae, E-mail: htjang@hanseo.ac.kr [Department of Chemical Engineering, Hanseo University, Seosan-si 356 706 (Korea, Republic of)

2014-03-01

Graphical abstract: - Highlights: • Usefulness of dual pharmaceutical surfactants in silica synthesis was evaluated. • Effects of concentration of secondary template (Tween-40) were studied. • Effects of fixed solvothermal condition on mesostructure formation were studied. • Duloxetine drug loading capability was studied. • Sustained release of duloxetine was evaluated. - Abstract: A new group of mesoporous silica nanoparticles (MSNs) were synthesized using combination pharmaceutical surfactants, Triton X-100 and Tween-40 as template and loaded with duloxetine hydrochloride (DX), for improving the sustained release of DX and patterns with high drug loading. Agglomerated spherical silica MSNs were synthesized by sol–gel and solvothermal methods. The calcined and drug loaded MSNs were characterized using X-ray diffraction (XRD), Braunner–Emmett–Teller (BET), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), diffuse reflectance ultraviolet–visible (DRS-UV–vis) spectroscopy. MSNs with high surface area and pore volume were selected and studied for their DX loading and release. The selected MSNs can accommodate a maximum of 34% DX within it. About 90% was released at 200 h and hence, the synthesized MSNs were capable of engulfing DX and sustain its release. Further form the Ritger and Peppas, Higuchi model for mechanism drug release from all the MSN matrices follows anomalous transport or Non-Fickian diffusion with the ‘r’ and ‘n’ value 0.9 and 0.45 < n < 1, respectively. So, from this study it could be concluded that the MSNs synthesized using pharmaceutical templates were better choice of reservoir for the controlled delivery of drug which requires sustained release.

Copper-based nanoparticles prepared from copper (II acetate bipyridine complex

Directory of Open Access Journals (Sweden)

Lastovina Tatiana A.

2016-01-01

Full Text Available We report the synthesis of CuO, Cu/Cu2O and Cu2O/CuO nanoparticles (NPs from the single copper (II acetate bipyridine complex by three different methods:microwave-assisted, solvothermal and borohydride. Presence of bipyridine ligand in the copper complex would impose no need in additional stabilization during synthesis. The phases of formed NPs were identified by X-ray diffraction. CuO NPs of ~11 nm were obtained via solvothermal synthesis from alkaline solution at 160°C. The Cu/Cu2O NPs of ~80 nm were produced via microwave-assisted polyol procedure at 185-200°C, where ethylene glycol can play a triple role as a solvent, a reducing agent and a surfactant. The Cu2O/CuO NPs of ~16 nm were synthesized by a borohydride method at room temperature. Interplanar spacing calculated from the selected-area electron diffraction data confirmed the formation of Cu, CuO and Cu2O phases in respective samples. All NPs are stable and can be used for various applications including biomedicine.

Revisiting Weak Simulation for Substochastic Markov Chains

DEFF Research Database (Denmark)

Jansen, David N.; Song, Lei; Zhang, Lijun

2013-01-01

of the logic PCTL\\x, and its completeness was conjectured. We revisit this result and show that soundness does not hold in general, but only for Markov chains without divergence. It is refuted for some systems with substochastic distributions. Moreover, we provide a counterexample to completeness...

Designed synthesis of tunable amorphous carbon nanotubes (a ...

Indian Academy of Sciences (India)

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The as-prepared a-CNTs were a kind of hydrogenated a-CNTs containing both ... aluminium oxide (AAO) template, solvothermal method, etc., have been developed to ... above products were treated by dilute HCl solution to remove VOx in the ...

One-step synthesis for FeBTC-MOF/iron oxide composite

Energy Technology Data Exchange (ETDEWEB)

Nascimento, R.F.F. do; Gentil, G.; Junior, S.A.; Azevedo, W.M. de; Rodrigues, A.R.; Campello, S.L. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

2016-07-01

Full text: In this work we present the assisted ultrasonic radiation synthesis for f Fe(BTC) (BTC = 1,3,5-benzenetricarboxilic acid) metal organic framework preparation. By definition Metal-organic frameworks (MOFs) belongs to a class of material prepared by the combination of metal ions and organic linkers to form a tridimensional framework which presents defined characteristics like crystallinity, high porosity and the presence of strong metal-ligand interaction. In the last decades the MOFs materials have received considerable attention not only due to scientific interest, but also because of their high potential for applications in several technological areas such as in gas storage, catalysis and drug delivery [1]. Among several Metal-organic frameworks (MOFs) the Fe-BTC structure seems to be one of promising materials, mainly due to their chemical and thermal stability, presents biocompatibility, can be used as drug delivery and as a contrast agent for magnetic resonance. Its functionalization has been reported in the literature by several works where the methods consist to mix the iron oxide Fe3O4 nanoparticles, in the solution contained the MOF'S precursor and the synthesis is prepared by solvothermal method. Typically, it has core-shell Fe3O4@MOF structures and exhibit magnetic properties. Our experimental technique proposed for the synthesis of the composite consists to use iron powder (?-Fe) as a target material dispersed in a solution of DMF/H2O (1:1) containing benzene 1,3,5 tricarboxilic acid and NaNO3. The synthesis was performed using a Ultrasound equipment model GEX500 500 W operating at 80 kHz, pulse 1s intervals for 60 min. The x-ray diffraction patterns and SEM measurements shown that the obtained materials are similar to those found in the literature and presents a rods likes morphology. The BET analysis indicate that the surface area is 1257 m²g-1 and pore volume 1.4 cm³g-1. Also the magnetic measurements indicates a paramagnetic

In Situ Tracking Kinetic Pathways of Li+/Na+ Substitution during Ion-Exchange Synthesis of LixNa1.5-xVOPO4F0.5.

Science.gov (United States)

Park, Young-Uk; Bai, Jianming; Wang, Liping; Yoon, Gabin; Zhang, Wei; Kim, Hyungsub; Lee, Seongsu; Kim, Sung-Wook; Looney, J Patrick; Kang, Kisuk; Wang, Feng

2017-09-13

Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials with metastable structure for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li + /Na + substitution during solvothermal ion-exchange synthesis of Li x Na 1.5-x VOPO 4 F 0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, reveals a selective replacement of Na + by Li + , leading to peculiar Na + /Li + /vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials.

Facile in situ solvothermal method to synthesize MWCNT/SnIn4S8 composites with enhanced visible light photocatalytic activity

International Nuclear Information System (INIS)

Ding, Chaoying; Tian, Li; Liu, Bo; Liang, Qian; Li, Zhongyu; Xu, Song; Liu, Qiaoli; Lu, Dayong

2015-01-01

Highlights: • MWCNT/SnIn 4 S 8 composites were facilely fabricated via in situ solvothermal method. • MWCNT/SnIn 4 S 8 composites exhibited significantly enhanced visible-light activity. • MWCNT/SnIn 4 S 8 composites showed remarkable visible light photocatalytic activity. • MWCNT/SnIn 4 S 8 composites exhibited excellent photo-stability. • Possible photocatalytic mechanism under visible-light irradiation was proposed. - Abstract: Superior photocatalytic activity could be achieved by multi-walled carbon nanotube (MWCNT) incorporated in the porous assembly of marigold-like SnIn 4 S 8 heterostructures synthesized by a flexible in-situ solvothermal method. The as-prepared MWCNT/SnIn 4 S 8 composites were well-characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic properties of the as-prepared samples were tested by photo-degradation of aqueous malachite green (MG) under the irradiation of visible light. It was found that the MWCNT/SnIn 4 S 8 composites showed enhanced visible light photocatalytic activity for dye degradation, and an optimum photocatalytic activity was observed over 3.0 wt.% MWCNT incorporated SnIn 4 S 8 composites. The superior photocatalytic activity of MWCNT/SnIn 4 S 8 composites could be ascribed to the existence of MWCNT which could serve as a good electron acceptor, mediator as well as the co-catalyst for dye degradation. The synergistic effect between SnIn 4 S 8 and MWCNT in the composites facilitated the interfacial charge transfer driven by the excitation of SnIn 4 S 8 under visible-light irradiation. Furthermore, a possible mechanism for the photocatalytic degradation of MWCNT/SnIn 4 S 8 composites was also discussed

Revisiting the formal foundation of Probabilistic Databases

NARCIS (Netherlands)

Wanders, B.; van Keulen, Maurice

2015-01-01

One of the core problems in soft computing is dealing with uncertainty in data. In this paper, we revisit the formal foundation of a class of probabilistic databases with the purpose to (1) obtain data model independence, (2) separate metadata on uncertainty and probabilities from the raw data, (3)

Revisiting Mutual Fund Performance Evaluation

OpenAIRE

Angelidis, Timotheos; Giamouridis, Daniel; Tessaromatis, Nikolaos

2012-01-01

Mutual fund manager excess performance should be measured relative to their self-reported benchmark rather than the return of a passive portfolio with the same risk characteristics. Ignoring the self-reported benchmark introduces biases in the measurement of stock selection and timing components of excess performance. We revisit baseline empirical evidence in mutual fund performance evaluation utilizing stock selection and timing measures that address these biases. We introduce a new factor e...

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4 magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

Directory of Open Access Journals (Sweden)

Abul Kalam

2018-03-01

Full Text Available Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4 photocatalysts were synthesized by modified Solvothermal (MST process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM, thermo gravimetric analysis (TGA, Fourier transform infrared (FT-IR, UV–visible (UV–vis spectroscopy and N2 adsorption–desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590–619 cm−1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0–76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst. Keywords: Cobalt ferrite, Photocatalysis, Kinetics, Optical properties, Surface area studies

Deterministic Graphical Games Revisited

DEFF Research Database (Denmark)

Andersson, Klas Olof Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro

2012-01-01

Starting from Zermelo’s classical formal treatment of chess, we trace through history the analysis of two-player win/lose/draw games with perfect information and potentially infinite play. Such chess-like games have appeared in many different research communities, and methods for solving them......, such as retrograde analysis, have been rediscovered independently. We then revisit Washburn’s deterministic graphical games (DGGs), a natural generalization of chess-like games to arbitrary zero-sum payoffs. We study the complexity of solving DGGs and obtain an almost-linear time comparison-based algorithm...

Metamorphosis in Craniiformea revisited

DEFF Research Database (Denmark)

Altenburger, Andreas; Wanninger, Andreas; Holmer, Lars E.

2013-01-01

We revisited the brachiopod fold hypothesis and investigated metamorphosis in the craniiform brachiopod Novocrania anomala. Larval development is lecithotrophic and the dorsal (brachial) valve is secreted by dorsal epithelia. We found that the juvenile ventral valve, which consists only of a thin...... brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda...

Solvothermal fabrication of TiO2/sepiolite composite gel with exposed {0 0 1} and {1 0 1} facets and its enhanced photocatalytic activity

Science.gov (United States)

Liu, Ruirui; Ji, Zhijiang; Wang, Jing; Zhang, Jinjun

2018-05-01

A novel TiO2/sepiolite composite gel (TiSG) was fabricated in the presence of cetyltrimethylammonium bromide (CTAB) through a simple solvothermal reaction in an acetic acid-water solvent. A homogeneous anchoring of TiO2 nanoparticles with exposed {0 0 1} and {1 0 1} facets on sepiolite nanofibers was achieved. CTAB content, solvothermal temperature/time, and HAc content play crucial roles in the morphological and facet formation of TiSG. A possible mechanism for the formation of TiSG was further proposed. CTAB as capping/shape-controlling agent can strongly bind to the more reactive (0 0 1) facet of TiO2 and then mitigate the thermodynamically favored (0 0 1) plane growth. Eventually, the truncated octahedral TiO2 was obtained by controlling the growth rates in 〈0 0 1〉 and 〈1 0 1〉 directions. Sepiolite as a cross-linking agent provides sufficient crosslinking sites for TiO2 to induce three-dimensional (3D) network formation, thereby generating the composite gel. The synthesized TiSG samples were then used as photocatalysts, which exhibited increased methyl orange removal under UV-vis light (350-780 nm) by the synergistic effect of adsorption and in-situ photocatalytic degradation as compared to P25 and bare TiO2. The excellent photocatalytic performance of TiSG was mainly ascribed to the formations of 3D gel structure and surface heterojunctions between (0 0 1) and (1 0 1) facets.

Microwave-assisted synthesis of C-doped TiO2 and ZnO hybrid nanostructured materials as quantum-dots sensitized solar cells

Science.gov (United States)

Rangel-Mendez, Jose R.; Matos, Juan; Cházaro-Ruiz, Luis F.; González-Castillo, Ana C.; Barrios-Yáñez, Guillermo

2018-03-01

The microwave-assisted solvothermal synthesis of C-doped TiO2 and ZnO hybrid materials was performed. Saccharose, titanium isopropoxide and zinc acetate were used as organic and inorganic sources for the synthesis. The influence of temperature and reaction time on the textural and optoelectronic properties of the hybrid materials was verified. Carbon quantum-dots of TiO2 and ZnO nanostructured spheres were obtained in a second pot by controlled calcination steps of the precursor hybrid materials. A carefully characterization by adsorption-desorption N2 isotherms, XRD, XPS, SEM, UV-vis/DR and electro- and photo-electrochemistry properties of the carbon quantum-dots TiO2 and ZnO spheres was performed. The photoelectrochemical activity of TiO2-C and ZnO-C films proved to be dependent on the conditions of synthesis. It was found a red-shift in the energy band gap of the semiconductors with values of 3.02 eV and 3.13 eV for the TiO2-C and ZnO-C, respectively, clearly lower than those on bare semiconductors, which is associated with the C-doping effect. From the photo-electrochemistry characterization of C-doped TiO2 and ZnO films can be concluded that the present materials have potential applications as photoelectrodes for quantum-dots sensitized solar cells.

The hard-core model on random graphs revisited

International Nuclear Information System (INIS)

Barbier, Jean; Krzakala, Florent; Zhang, Pan; Zdeborová, Lenka

2013-01-01

We revisit the classical hard-core model, also known as independent set and dual to vertex cover problem, where one puts particles with a first-neighbor hard-core repulsion on the vertices of a random graph. Although the case of random graphs with small and very large average degrees respectively are quite well understood, they yield qualitatively different results and our aim here is to reconciliate these two cases. We revisit results that can be obtained using the (heuristic) cavity method and show that it provides a closed-form conjecture for the exact density of the densest packing on random regular graphs with degree K ≥ 20, and that for K > 16 the nature of the phase transition is the same as for large K. This also shows that the hard-code model is the simplest mean-field lattice model for structural glasses and jamming

Facile Synthesis of V2O5 Hollow Spheres as Advanced Cathodes for High-Performance Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Xingyuan Zhang

2017-01-01

Full Text Available Three-dimensional V2O5 hollow structures have been prepared through a simple synthesis strategy combining solvothermal treatment and a subsequent thermal annealing. The V2O5 materials are composed of microspheres 2–3 μm in diameter and with a distinct hollow interior. The as-synthesized V2O5 hollow microspheres, when evaluated as a cathode material for lithium-ion batteries, can deliver a specific capacity as high as 273 mAh·g−1 at 0.2 C. Benefiting from the hollow structures that afford fast electrolyte transport and volume accommodation, the V2O5 cathode also exhibits a superior rate capability and excellent cycling stability. The good Li-ion storage performance demonstrates the great potential of this unique V2O5 hollow material as a high-performance cathode for lithium-ion batteries.

Synthesis of nanostructured CuInS{sub 2} thin films and their application in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yu; Zhuang, Mixue; Liu, Zhen; Wei, Aixiang [Guangdong University of Technology, Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Material and Energy, Guangzhou (China); Luo, Fazhi [Guangdong University of Technology, Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Material and Energy, Guangzhou (China); The Fifth Electronics Research Institute of Ministry of Industry and Information Technology, Guangzhou (China); Liu, Jun [Guangdong University of Technology, Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Material and Energy, Guangzhou (China); Zhejiang University, State Key Lab of Silicon Materials, Hangzhou (China)

2016-03-15

CuInS{sub 2} (CIS) nanostructure thin films were successfully synthesized on FTO conductive glass substrates by solvothermal method. It is found that the surface morphology and microstructure of CIS thin films can be tailored by simply adjusting the concentration of oxalic acid. CIS nanostructure films with texture of ''nanosheet array'' and ''flower-like microsphere'' were obtained and used as Pt-free counter electrode for dye-sensitized solar cells (DSSCs). The nanosheet array CIS was found to have a better electrocatalytic activity than the flower-like microsphere one. DSSCs based on nanosheet array CIS thin film counter electrode show conversion efficiency of 3.33 %, which is comparable to the Pt-catalyzed DSSCs. The easy synthesis, low cost, morphology tunable and excellent electrocatalytic property may make the CuInS{sub 2} nanostructure competitive as counter electrode in DSSCs. (orig.)

The Effects of Korean Medical Service Quality and Satisfaction on Revisit Intention of the United Arab Emirates Government Sponsored Patients.

Science.gov (United States)

Lee, Seoyoung; Kim, Eun-Kyung

2017-06-01

The purpose of this study was to investigate medical service quality, satisfaction and to examine factors influencing hospital revisit intention of the United Arab Emirates government sponsored patients in Korea. A total of 152 UAE government sponsored patients who visited Korean hospitals participated in the questionnaire survey from August to November 2016. Stepwise multiple regression was used to identify the factors that affected the revisit intention of the participants. The mean scores of medical service quality, satisfaction, and revisit intention were 5.72 out of 7, 88.88 out of 100, 4.59 out of 5, respectively. Medical service quality and satisfaction, Medical service quality and revisit intention, satisfaction and revisit intention were positively correlated. Medical service of physician, visiting routes and responsiveness of medical service quality explained about 23.8% of revisit intention. There are needs for physicians to communicate with patients while ensuring sufficient consultation time based on excellent medical skills and nurses to respond immediately for the patients' needs through an empathic encounter in order to improve medical service quality and patient satisfaction so that to increase the revisit intention of the United Arab Emirates government sponsored patients. Further, it is necessary for the hospitals to have support plans for providing country specialized services in consideration of the UAE culture to ensure that physicians' and nurses' competencies are not undervalued by non-medical service elements such as interpreters and meals. Copyright © 2017. Published by Elsevier B.V.

Solvothermal synthesis and theoretical study of a polypyridium ...

Indian Academy of Sciences (India)

life sciences, clinical medicine, and material chem- istry.11–14 Many .... environment and charge balance, the H3BTC should be fully deprotonated, but the ..... ous work, we now attempt to combine rare earth metal ions with adduct 1 to ...

Synthesis engineering of iron oxide raspberry-shaped nanostructures.

Science.gov (United States)

Gerber, O; Pichon, B P; Ihiawakrim, D; Florea, I; Moldovan, S; Ersen, O; Begin, D; Grenèche, J-M; Lemonnier, S; Barraud, E; Begin-Colin, S

2017-01-07

Magnetic porous nanostructures consisting of oriented aggregates of iron oxide nanocrystals display very interesting properties such as a lower oxidation state of magnetite, and enhanced saturation magnetization in comparison with individual nanoparticles of similar sizes and porosity. However, the formation mechanism of these promising nanostructures is not well understood, which hampers the fine tuning of their magnetic properties, for instance by doping them with other elements. Therefore the formation mechanism of porous raspberry shaped nanostructures (RSNs) synthesized by a one-pot polyol solvothermal method has been investigated in detail from the early stages by using a wide panel of characterization techniques, and especially by performing original in situ HR-TEM studies in temperature. A time-resolved study showed the intermediate formation of an amorphous iron alkoxide phase with a plate-like lamellar structure (PLS). Then, the fine investigation of PLS transformation upon heating up to 500 °C confirmed that the synthesis of RSNs involves two iron precursors: the starting one (hydrated iron chlorides) and the in situ formed iron alkoxide precursor which decomposes with time and heating and contributes to the growth step of nanostructures. Such an understanding of the formation mechanism of RSNs is necessary to envision efficient and rational enhancement of their magnetic properties.

Coccolithophorids in polar waters: Wigwamma spp. revisited

DEFF Research Database (Denmark)

Thomsen, Helge Abildhauge; Østergaard, Jette B.; Heldal, Mikal

2013-01-01

A contingent of weakly calcified coccolithophorid genera and species were described from polar regions almost 40 years ago. In the interim period a few additional findings have been reported enlarging the realm of some of the species. The genus Wigwamma is revisited here with the purpose of provi...... appearance of the coccolith armour of the cell...

The significance test controversy revisited the fiducial Bayesian alternative

CERN Document Server

Lecoutre, Bruno

2014-01-01

The purpose of this book is not only to revisit the “significance test controversy,”but also to provide a conceptually sounder alternative. As such, it presents a Bayesian framework for a new approach to analyzing and interpreting experimental data. It also prepares students and researchers for reporting on experimental results. Normative aspects: The main views of statistical tests are revisited and the philosophies of Fisher, Neyman-Pearson and Jeffrey are discussed in detail. Descriptive aspects: The misuses of Null Hypothesis Significance Tests are reconsidered in light of Jeffreys’ Bayesian conceptions concerning the role of statistical inference in experimental investigations. Prescriptive aspects: The current effect size and confidence interval reporting practices are presented and seriously questioned. Methodological aspects are carefully discussed and fiducial Bayesian methods are proposed as a more suitable alternative for reporting on experimental results. In closing, basic routine procedures...

A simple solvothermal process for fabrication of a metal-organic framework with an iron oxide enclosure for the determination of organophosphorus pesticides in biological samples.

Science.gov (United States)

Zhang, Suling; Jiao, Zhe; Yao, Weixuan

2014-12-05

An active magnetic metal-organic framework (MOF) hybrid material was prepared using a novel in situ solvothermal method in the presence of magnetite (Fe3O4) particles, that holds much promise for large-scale synthesis. MIL-101(Fe), an iron terephthalate with pore structure and high resistance to water and common solvents, was functionalized as a model with superparamagnetic qualities, using Fe3O4. The electrostatic interaction between Fe3O4 and metal ions was thereby used to chemically stabilize magnetic nanoparticles, and thus MOF crystals were uniformly enclosed by Fe3O4 to form a homogeneous magnetic product identified as a Fe3O4/MIL-101 composite. This hybrid material with magnetic susceptibility but with the lowest possible loading amount of Fe3O4 was examined, and its potential application for magnetic solid-phase extraction of six organophosphorus pesticides (OPPs) from human hair and urine samples, followed by gas chromatography analysis, was assessed. The main effect parameters including solution ionic strength, desorption solvent, extraction time and desorption time were investigated in sequence. Under optimized conditions, this method showed low detection limits (0.21-2.28 ng/mL), wide linearity, and good precision (1.8-8.7% for intra-day, 2.9-9.4% for inter-day). The matrix interference produced by hair or urine could be effectively eliminated using this method, and satisfactory recoveries of the spiked samples were 76.8-94.5% and 74.9-92.1%, respectively, indicating that the Fe3O4/MIL-101 sorbents are feasible for the analysis of trace analytes from biological samples. Copyright © 2014. Published by Elsevier B.V.

An Experimental Study on the Shape Changes of TiO2 Nanocrystals Synthesized by Microemulsion-Solvothermal Method

Directory of Open Access Journals (Sweden)

Wei Kong

2011-01-01

Full Text Available Titanium dioxide (TiO2 nanocrystals of different shape were successfully synthesized in a new microemulsion system through a solvothermal process. The TiO2 nanocrystals were prepared from the reaction of tetrabutyl titanate (TBT, H2O, and oleic acid (OA, which were used as solvent and surfactant at 300∘C and 240∘C in a stainless steel autoclave. The sphere, polygon, and rhombus-shaped nanocrystals have been prepared at 300∘C and the dot- and- rod shaped nanocrystals have been synthesized at 240∘C. The effect of the reaction time on the shape and size of TiO2 nanocrystals in this method was studied in the present paper. The size distribution of TiO2 nanocrystals prepared at 300∘C for different hours is also studied. In addition, an attempt to describe the mechanism of shape change of TiO2 nanocrystals was presented in this paper.

Synthesis and characterization of titanium oxide/bismuth sulfide nanorods for solar cells applications

International Nuclear Information System (INIS)

Solis, M.; Rincon, M. E.

2008-01-01

In the present work is showed the synthesis and characterization of titanium oxide/bismuth sulfide nanowires hetero-junctions for solar cells applications. Conductive glass substrates (Corning 25 x 75 mm) were coated with a thin layer of sol-gel TiO2 and used as substrates for the subsequent deposition of bismuth sulfide nanorods (BN). TiO2 films (∼400 nm) were deposited with a semiautomatic immersion system with controlled immersion/withdraw velocity, using titanium isopropoxide as the titania precursor [1]. For BN synthesis and deposition, the solvo-thermal method was used, introducing air annealed TiO2-substrates in the autoclave. The typical bilayer TiO2/BN hetero-junction was 600 nm thick. The synthesized materials (powders and films) were characterized by X-Ray Diffraction, Scanning Electron Microscopy, and UV-Visible Spectroscopy. Anatase was the crystalline phase of TiO2, while bismuth sulfide nanotubes show a diffraction pattern characteristic of bismuthinite distorted by the preferential growth of some planes [2-4]. The optoelectronic characterization of TiO2/NB hetero-junctions was compared with hetero-junctions obtained by sensitizing TiO2 with chemically deposited bismuth sulfide films. Bismuth sulfide nanowires are 2µm long and 70nm wide (aspect ratio L/D = 43), while chemically deposited bismuth sulfide have L/D = 1, therefore the effect of particle size evaluation and geometry in the photosensitization phenomena will be discussed in the context of new materials for solar-cells applications. (Full text)

Catalytic Activity of Urchin-like Ni nanoparticles Prepared by Solvothermal Method for Hydrogen Evolution Reaction in Alkaline Solution

International Nuclear Information System (INIS)

Abbas, Syed Asad; Iqbal, Muhammad Ibrahim; Kim, Seong-Hoon; Jung, Kwang-Deog

2017-01-01

Highlights: • Urchin-like Ni is prepared in solvothermal reaction. • Urchin-like Ni is formed via Ni(OH) 2 aggregates in ethanol and oleylamine. • Exchange current density of urchin-like Ni is 0.191 mA cm −2 . • Urchin-like Ni exceeds the catalytic performance of commercial Pt/C in HER. - Abstract: Ni nanoparticles with different morphologies were synthesized for hydrogen evolution reaction (HER) in alkaline solution. Here, Ni(acac) 2 was converted into Ni metal nanoparticles in solvothermal reactions with simple alcohols and oleylamine (OAm). The morphology of the resulting Ni nanoparticles was dependent mainly on the OAm/Ni molar ratio in alcohol solvent. Aggregates of spherical Ni nanoparticles (NiEt-OAm1) were observed at the OAm/Ni molar ratio of 1.0, whereas two echinoid Ni nanoparticles (NiEt-OAm4 and NiEt-OAm6) could be prepared in ethanol at the OAm/Ni molar ratios of 4.0 and 6.0. Ni(OH) 2 formed in ethanol during a reaction time of 5 h was then reduced into echinoid Ni nanoparticles after 8 h. Echinoid Ni nanoparticles were formed by atomic addition on the tops of the multipod Ni particles formed via Ni(OH) 2 /NiO aggregates. Webbed feet-like particles (NiIPA-OAm4) with plate edges were also observed in isopropanol under the same reaction conditions. The catalytic activities of the prepared Ni nanoparticles for the hydrogen evolution reaction were evaluated in alkaline solution. The NiEt-OAm4 with urchin-like morphology was much more active than the NiIPA-OAm4 with webbed feet-like morphology. The exchange current density of Ni catalysts was increased with increasing the OAm/Ni molar ratio. The NiEt-OAm6 exhibited an exchange current of 0.191 mA cm −2 and the NiEt-OAm4 exceeded electrocatalytic performance of a commercial Pt catalysts (40% Pt on Vulcan XC 72) in a stability test for 100 kiloseconds at −1.5 V (vs. Hg/HgO) in 1.0 M NaOH due to its high stability.

One dimensional well-aligned CdO nanocrystal by solvothermal method

International Nuclear Information System (INIS)

Kaviyarasu, K.; Manikandan, E.; Paulraj, P.; Mohamed, S.B.; Kennedy, J.

2014-01-01

Graphical abstract: - Highlights: • Cadmium oxide (CdO) emerged as one of the important semiconducting materials. • Iodine concentration increases intensity of the peak around 300 cm −1 becomes stronger. • Surface morphology of these crystals has been modified by varying complexing agent. • Nanofibers structure like CdO crystals first time achieved. • The diameters of these nanofibers range mostly between 40 nm and 70 nm. - Abstract: Cadmium oxide (CdO) is a category of the practical semiconductor metal oxides, which is widely applied in various scientific and industrial fields because of its catalytic, optical, and electrical properties. CdO nanocrystal was successfully synthesized by a virtue of a single source precursor method at mild reaction conditions between cadmium oxide, and element iodine by a solvothermal route. X-ray powder diffraction (XRD), ultraviolet spectroscopy studies (UV–vis), Fourier Transform Infrared analysis (FTIR), scanning electron microscopy (SEM), μ-Raman spectroscopy and cyclic voltammogram (CV) were used to characterize the CdO nanocrystals. The ultra-violet visible absorption peaks of CdO exhibited a large blue shift and the luminescent spectra had a strong and broad emission band centered at 228 nm. The various functional groups present in the CdO nanocrystals were identified by FTIR analysis. Intense PL was also observed with some spectral tuning possibly giving a range of emission photon energies approximately spanning from 2.5 to 3.4 eV. Scanning electron microscopy and μ-Raman microscopy images indicated that the morphology of the product is spherical nanoparticles with an average particle size of 46 nm with standard deviation. The electrochemical response of CdO which is proved the nano-cadmium has high functionality due to the small size and it has higher electrochemical activity without any modifications. The above studies demonstrate the potential for the utilization of cadmium nitrite nanocrystal in visible

Satellite failures revisited

Science.gov (United States)

Balcerak, Ernie

2012-12-01

In January 1994, the two geostationary satellites known as Anik-E1 and Anik-E2, operated by Telesat Canada, failed one after the other within 9 hours, leaving many northern Canadian communities without television and data services. The outage, which shut down much of the country's broadcast television for hours and cost Telesat Canada more than $15 million, generated significant media attention. Lam et al. used publicly available records to revisit the event; they looked at failure details, media coverage, recovery effort, and cost. They also used satellite and ground data to determine the precise causes of those satellite failures. The researchers traced the entire space weather event from conditions on the Sun through the interplanetary medium to the particle environment in geostationary orbit.

Optical, magnetic and structural characterization of Zn1−xCoxO ...

Indian Academy of Sciences (India)

attracted considerable attention, both theoretically and experi- mentally, due to their ... C and finally ground to powder. Zn1−x Cox O ... Figure 1. Flowchart for solvothermal synthesis of Zn1−x Cox O (x = 0·038, 0·072 and 0·115) nanoparticles.

Pockets of Participation: Revisiting Child-Centred Participation Research

Science.gov (United States)

Franks, Myfanwy

2011-01-01

This article revisits the theme of the clash of interests and power relations at work in participatory research which is prescribed from above. It offers a possible route toward solving conflict between adult-led research carried out by young researchers, funding requirements and organisational constraints. The article explores issues of…

Faraday effect revisited: sum rules and convergence issues

DEFF Research Database (Denmark)

Cornean, Horia; Nenciu, Gheorghe

2010-01-01

This is the third paper of a series revisiting the Faraday effect. The question of the absolute convergence of the sums over the band indices entering the Verdet constant is considered. In general, sum rules and traces per unit volume play an important role in solid-state physics, and they give...

Stable and Controllable Synthesis of Silver Nanowires for Transparent Conducting Film

Science.gov (United States)

Liu, Bitao; Yan, Hengqing; Chen, Shanyong; Guan, Youwei; Wu, Guoguo; Jin, Rong; Li, Lu

2017-03-01

Silver nanowires without particles are synthesized by a solvothermal method at temperature 150 °C. Silver nanowires are prepared via a reducing agent of glycerol and a capping agent of polyvinylpyrrolidone ( M w ≈ 1,300,000). Both of them can improve the purity of the as-prepared silver nanowires. With controllable shapes and sizes, silver nanowires are grown continuously up to 10-20 μm in length with 40-50 nm in diameter. To improve the yield of silver nanowires, the different concentrations of AgNO3 synthesis silver nanowires are discussed. The characterizations of the synthesized silver nanowires are analyzed by UV-visible absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscope (AFM), and silver nanowires are pumped on the cellulose membrane and heated stress on the PET. Then, the cellulose membrane is dissolved by the steam of acetone to prepare flexible transparent conducting thin film, which is detected 89.9 of transmittance and 58 Ω/□. Additionally, there is a close loop connected by the thin film, a blue LED, a pair of batteries, and a number of wires, to determinate directly the film if conductive or not.

Synthesis and characterization of ZIF-69 membranes and separation for CO2/CO mixture

KAUST Repository

Liu, Yunyang

2010-05-01

Continuous and c-oriented ZIF-69 membranes were successfully synthesized on porous alpha-alumina substrates by an in situ solvothermal method. The membranes were characterized by XRD, SEM and single-gas permeation tests. The BET measurements on crystals taken from the same mother liquor that was used for membrane synthesis yield a Langmuir surface area of 1138 m(2)/g. The stability of the membrane towards heat and different solvents were studied. Single-gas permeation experiments through ZIF-69 membranes were carried out by a vacuum method at room temperature using H-2, CH4, CO, CO2 and SF6, respectively. The permeances were in the order of H-2 > CO2 > CH4 > CO > SF6. The separation of CO2/CO gas mixture was investigated by gas chromatograph (GC) and the permselectivity of CO2/CO was 3.5 +/- 0.1 with CO2 permeance of 3.6 +/- 0.3 x 10(-8) mol m(-2) s(-1) Pa-1 at room temperature. (C) 2010 Elsevier B.V. All rights reserved.

Fabrication and luminescence properties of Al{sub 2}O{sub 3}:Tb{sup 3+} microspheres via a microwave solvothermal route

Energy Technology Data Exchange (ETDEWEB)

Zhu Zhenfeng, E-mail: zhuzf@sust.edu.cn [School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi' an 710021 (China); Liu Dianguang; Liu Hui; Li Guangjun; Du Juan; He Zuoli [School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi' an 710021 (China)

2012-02-15

Al{sub 2}O{sub 3}:Tb{sup 3+} green phosphors were synthesized via a microwave solvothermal and thermal decomposition route, and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra, and decay curves. XRD results indicate that Tb{sup 3+} doped samples are {gamma}-Al{sub 2}O{sub 3} after being calcined at 773 K. SEM results show that the particles of Al{sub 2}O{sub 3}:Tb{sup 3+} are hierarchically nanostructured microspheres assembled from nanosheets. The PL spectra indicate that the {sup 5}D{sub 4}{yields}{sup 7}F{sub 5} (545 nm) electric dipole transition is the most intensive when excited at 235 nm. It is shown that 0.7 mol% of doping concentration of Tb{sup 3+} ions in {gamma}-Al{sub 2}O{sub 3}:Tb{sup 3+} is optimum. According to Dexter's theory, the critical distance between Tb{sup 3+} ions for energy transfer was determined to be 18.4 A. It is found that the curve followed the single-exponential decay. The excellent chromaticity coordinates of Al{sub 2}O{sub 3}:Tb{sup 3+} phosphors, as defined by the International Commission on Illumination (CIE), indicate that it is a good candidate for use in light display systems and optoelectronic devices. - Highlights: Black-Right-Pointing-Pointer Al{sub 2}O{sub 3}:Tb{sup 3+} phosphors prepared via a microwave solvothermal route. Black-Right-Pointing-Pointer The particles were hierarchically nanostructured microspheres packaged by nanosheets. Black-Right-Pointing-Pointer {sup 5}D{sub 4}{yields}{sup 7}F{sub 5} electric dipole transition is the most intensive when excited at 235 nm. Black-Right-Pointing-Pointer 0.7 mol% of doping concentration of Tb{sup 3+} ions in {gamma}-Al{sub 2}O{sub 3}:Tb{sup 3+} is optimum. Black-Right-Pointing-Pointer Critical distance between Tb{sup 3+} ions for energy transfer is 18.4 A.

Curcumin: Synthesis optimization and in silico interaction with cyclin dependent kinase.

Science.gov (United States)

Ahmed, Mahmood; Abdul Qadir, Muhammad; Imtiaz Shafiq, Muhammad; Muddassar, Muhammad; Hameed, Abdul; Nadeem Arshad, Muhammad; Asiri, Abdullah M

2017-09-01

Curcumin is a natural product with enormous biological potential. In this study, curcumin synthesis was revisited using different reaction solvents, a catalyst (n-butylamine) and a water scavenger [(n-BuO)3B], to develop the optimal procedure for its rapid acquisition. During synthesis, solvent choice was found to be an important parameter for better curcumin yield and high purity. In a typical reaction, acetyl acetone was treated with boron trioxide, followed by condensation with vanillin in the presence of tri-n-butyl borate as water scavenger and n-butylamine as catalyst at 80 °C in ethyl acetate to afford curcumin. Moreover, curcumin was also extracted from turmeric powder and spectroscopic properties such as IR, MS, 1H NMR and 13C NMR with synthetic curcumin were established to identify any impurity. The purity of synthetic and extracted curcumin was also checked by TLC and HPLC-DAD. To computationally assess its therapeutic potential against cyclin dependent kinases (CDKs), curcumin was docked in different isoforms of CDKs. It was observed that it did not dock at the active sites of CDK2 and CDK6. However, it could enter into weak interactions with CDK4 protein.

Synthesis and spectral studies on Cd(II) dithiocarbamate complexes and their use as precursors for CdS nanoparticles

Science.gov (United States)

Sathiyaraj, Ethiraj; Padmavathy, Krishnaraj; Kumar, Chandran Udhaya; Krishnan, Kannan Gokula; Ramalingan, Chennan

2017-11-01

Bis(N-cyclopropyl-N-4-chlorobenzyldithiocarbamato-S,S‧)cadmium(II) (1) and (2,2‧-bipyridine) bis(N-cyclopropyl-N-4-chlorobenzyldithiocarbamato-S,S‧)cadmium(II) (2) have been synthesized and characterized by FT-IR, 1HNMR and 13C NMR analyses. For the complex 2, single crystal X-ray diffraction analysis and computational studies (optimized geometry, HOMO-LUMO and MEP) have been executed employing DFT/B3LYP method with LANL 2DZ basic set. The optimized bond lengths and bond angles agree well with the experimental results. The complexes 1 and 2 have been used as single source precursors for the synthesis of ethyleneglycol capped CdS1 and CdS2 nanoparticles, respectively. CdS1 and CdS2 nanoparticles have been synthesized by solvothermal method. PXRD, SEM, Elemental colour mapping, EDAX, TEM and UV-Vis spectroscopy have been used to characterize the as-prepared CdS nanoparticles. The X-ray diffraction pattern confirms both their hexagonal structures.

Solvothermal synthesis, crystal structure, and second-order nonlinear optical properties of a new noncentrosymmetric gallium-organic framework material, [N(C{sub 3}H{sub 7}){sub 4}]{sub 3}Ga{sub 3}[C{sub 6}H{sub 3}(CO{sub 2}){sub 3}]{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Lee, Dong Woo; Jo, Vinna [Department of Chemistry, Chung-Ang University, Seoul, 156-756 (Korea, Republic of); Ok, Kang Min, E-mail: kmok@cau.ac.kr [Department of Chemistry, Chung-Ang University, Seoul, 156-756 (Korea, Republic of)

2012-10-15

A novel noncentrosymmetric (NCS) gallium-organic framework material, [N(C{sub 3}H{sub 7}){sub 4}]{sub 3}Ga{sub 3}[C{sub 6}H{sub 3}(CO{sub 2}){sub 3}]{sub 4} (CAUMOF-11) has been synthesized by a solvothermal reaction using Ga(NO{sub 3}){sub 3}{center_dot}xH{sub 2}O, 1,3,5-C{sub 6}H{sub 3}(CO{sub 2}H){sub 3}, N(C{sub 3}H{sub 7}){sub 4}Cl, HNO{sub 3}, and HCON(CH{sub 3}){sub 2} at 180 Degree-Sign C. The structure of the reported material has been determined by single-crystal X-ray diffraction. CAUMOF-11 has an anionic three-dimensional framework with aligned four-coordinate GaO{sub 4} tetrahedra and 1,3,5-benzenetricarboxylate groups. Tetrapropylammonim cations reside within the channel and maintain the charge balance. Detailed structural analyses with full characterization including infrared spectroscopy, thermogravimetric analysis, elemental analysis, ion-exchange reactions, topotactic decomposition, and gas adsorption experiments are reported. Powder second-harmonic generating (SHG) measurements on CAUMOF-11, using 1064 nm radiation, exhibit SHG efficiency of 15 times that of {alpha}-SiO{sub 2} and the material is phase-matchable (type-1). - Graphical Abstract: Second-order nonlinear optical measurements on CAUMOF-11 reveal that the material is phase-matchable (type-1) with SHG efficiency of 15 times that of {alpha}-SiO{sub 2}. Highlights: Black-Right-Pointing-Pointer A new NCS Ga-organic framework was solvothermally synthesized. Black-Right-Pointing-Pointer CAUMOF-11 exhibits SHG efficiency of 15 times that of {alpha}-SiO{sub 2}. Black-Right-Pointing-Pointer Thermal decomposition of CAUMOF-11 crystal maintains the original morphology.

Preparation of CuIn{sub 1-x}Ga{sub x}S{sub 2} (x = 0.5) flowers consisting of nanoflakes via a solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Liang Xiaojuan [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang Province 325035 (China); Institute of Materials and Technology, Dalian Maritime University, Dalian 116026 (China); Zhong Jiasong; Yang Fan; Hua Wei; Jin Huaidong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang Province 325035 (China); Liu Haitao, E-mail: lht@wzu.edu.cn [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang Province 325035 (China); Sun Juncai [Institute of Materials and Technology, Dalian Maritime University, Dalian 116026 (China); Xiang Weidong, E-mail: weidongxiang@yahoo.com.cn [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang Province 325035 (China)

2011-05-26

Highlights: > We report for the first time a small biomolecule-assisted route using L-cysteine as sulfur source and complexing agent to synthesis CuIn{sub 0.5}Ga{sub 0.5}S{sub 2} crystals. > The possible mechanisms leading to CuIn{sub 0.5}Ga{sub 0.5}S{sub 2} flowers consisting of nanoflakes were proposed. > In addition, the morphology, structure, and phase composition of the as-prepared CuIn{sub 0.5}Ga{sub 0.5}S{sub 2} products were investigated in detail by XRD, FESEM, EDS, XPS, TEM (HRTEM) and SAED. - Abstract: CuIn{sub 1-x}Ga{sub x}S{sub 2} (x = 0.5) flowers consisting of nanoflakes were successfully prepared by a biomolecule-assisted solvothermal route at 220 deg. C for 10 h, employing copper chloride, gallium chloride, indium chloride and L-cysteine as precursors. The biomolecule L-cysteine acting as sulfur source was found to play a very important role in the formation of the final product. The diameter of the CuIn{sub 0.5}Ga{sub 0.5}S{sub 2} flowers was 1-2 {mu}m, and the thickness of the flakes was about 15 nm. The obtained products were characterized by X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction spectroscopy (SAED), and UV-vis absorption spectroscopy. The influences of the reaction temperature, reaction time, sulfur source and the molar ratio of Cu-to-L-cysteine (reactants) on the formation of the target compound were investigated. The formation mechanism of the CuIn{sub 0.5}Ga{sub 0.5}S{sub 2} flowers consisting of flakes was discussed.

Short or Long End of the Lever? Associations between Provider Communication of the "Asthma-Action Plan" and Outpatient Revisits for Pediatric Asthma.

Science.gov (United States)

Rangachari, Pavani; Mehta, Renuka; Rethemeyer, R Karl; Ferrang, Carole; Dennis, Clifton; Redd, Vickie

2015-10-01

At the Children's Hospital of Georgia (CHOG), we found that outpatient revisits for pediatric asthma were significantly above national norms. According to the NIH, costly hospital revisits for asthma can be prevented through guidelines-based self-management of asthma, central to which, is the use of a written Asthma-Action Plan (AAP). The asthma services literature has emphasized the role of the healthcare provider in promoting asthma self-management using the AAP, to prevent hospital revisits. On the other hand, the asthma policy literature has emphasized the need for community-based interventions to promote asthma self-management. A gap remains in understanding the extent of leverage that healthcare providers may have in preventing hospital revisits for asthma, through effective communication of AAP in the outpatient setting. Our study sought to address this gap. We conducted a 6-month intervention to implement "patient-and-family-centered communication of the AAP" in CHOG outpatient clinics, based on the "change-management" theoretical framework. Provider communication of AAP was assessed through a survey of "Parent Understanding of the Child's AAP." A quasi-experimental approach was used to measure outpatient revisits for pediatric asthma, pre- and post-intervention. Survey results showed that provider communication of the AAP was unanimously perceived highly positively by parents of pediatric asthma patients, across various metrics of patient-centered care. However, there were no statistically significant differences in outpatient "revisit behavior" for pediatric asthma between pre- and post-intervention periods after controlling for several demographic variables. Additionally, revisits remained significantly above national norms. Results suggest limited potential of "effective provider communication of AAP," in reducing outpatient revisits for pediatric asthma; and indicate need for broader community-based interventions to address patient life variables

Additively homomorphic encryption with a double decryption mechanism, revisited

NARCIS (Netherlands)

Peter, Andreas; Kronberg, M.; Trei, W.; Katzenbeisser, S.

We revisit the notion of additively homomorphic encryption with a double decryption mechanism (DD-PKE), which allows for additions in the encrypted domain while having a master decryption procedure that can decrypt all properly formed ciphertexts by using a special master secret. This type of

Moral Judgment Development across Cultures: Revisiting Kohlberg's Universality Claims

Science.gov (United States)

Gibbs, John C.; Basinger, Karen S.; Grime, Rebecca L.; Snarey, John R.

2007-01-01

This article revisits Kohlberg's cognitive developmental claims that stages of moral judgment, facilitative processes of social perspective-taking, and moral values are commonly identifiable across cultures. Snarey [Snarey, J. (1985). "The cross-cultural universality of social-moral development: A critical review of Kohlbergian research."…

Solvothermal synthesis, crystal structure, and second-order nonlinear optical properties of a new noncentrosymmetric gallium-organic framework material, [N(C3H7)4]3Ga3[C6H3(CO2)3]4

Science.gov (United States)

Lee, Dong Woo; Jo, Vinna; Ok, Kang Min

2012-10-01

A novel noncentrosymmetric (NCS) gallium-organic framework material, [N(C3H7)4]3Ga3[C6H3(CO2)3]4 (CAUMOF-11) has been synthesized by a solvothermal reaction using Ga(NO3)3·xH2O, 1,3,5-C6H3(CO2H)3, N(C3H7)4Cl, HNO3, and HCON(CH3)2 at 180 °C. The structure of the reported material has been determined by single-crystal X-ray diffraction. CAUMOF-11 has an anionic three-dimensional framework with aligned four-coordinate GaO4 tetrahedra and 1,3,5-benzenetricarboxylate groups. Tetrapropylammonim cations reside within the channel and maintain the charge balance. Detailed structural analyses with full characterization including infrared spectroscopy, thermogravimetric analysis, elemental analysis, ion-exchange reactions, topotactic decomposition, and gas adsorption experiments are reported. Powder second-harmonic generating (SHG) measurements on CAUMOF-11, using 1064 nm radiation, exhibit SHG efficiency of 15 times that of α-SiO2 and the material is phase-matchable (type-1).

Radiative corrections to double-Dalitz decays revisited

Science.gov (United States)

Kampf, Karol; Novotný, Jiři; Sanchez-Puertas, Pablo

2018-03-01

In this study, we revisit and complete the full next-to-leading order corrections to pseudoscalar double-Dalitz decays within the soft-photon approximation. Comparing to the previous study, we find small differences, which are nevertheless relevant for extracting information about the pseudoscalar transition form factors. Concerning the latter, these processes could offer the opportunity to test them—for the first time—in their double-virtual regime.

Graphene Oxide-Directed Tunable Assembly of MoS₂ Ultrathin Nanosheets for Electrocatalytic Hydrogen Evolution

DEFF Research Database (Denmark)

Sun, Hongyu; Zhao, Yanyan; Mølhave, Kristian

2017-01-01

Three dimensional (3D) hierarchical architectures based onmolybdenum disulfide (MoS2) an d reduced graphene oxide (rGO) are synthesized through a mixed solvothermal method.By simply increasing the amount of graphene oxide (GO) during the synthesis, the 3D assembly of MoS2 can be tunedfrom nanoflo...

Bulletin of Materials Science | News

Indian Academy of Sciences (India)

Effect of temperature and time on solvothermal synthesis of tetragonal BaTiO3 ... Chitosan–silver oxide nanocomposite film: Preparation and antimicrobial activity .... surface coatings on wood impregnated with Cu-ethanolamine preservatives .... Structure and electric transport properties of LnSr2FeTiO7 (Ln = La, Nd and Gd).

A Feminist Revisit to the First-Year Curriculum.

Science.gov (United States)

Bernstein, Anita

1996-01-01

A seminar at Chicago-Kent College of Law (Illinois) that reviews six first-year law school courses by focusing on feminist issues in course content and structure is described. The seminar functions as both a review and a shift in perspective. Courses revisited include civil procedure, contracts, criminal law, justice and the legal system,…

Quantum duel revisited

International Nuclear Information System (INIS)

Schmidt, Alexandre G M; Paiva, Milena M

2012-01-01

We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α 1 and α 2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent. (paper)

The Importance of Being a Complement: CED Effects Revisited

Science.gov (United States)

Jurka, Johannes

2010-01-01

This dissertation revisits subject island effects (Ross 1967, Chomsky 1973) cross-linguistically. Controlled acceptability judgment studies in German, English, Japanese and Serbian show that extraction out of specifiers is consistently degraded compared to extraction out of complements, indicating that the Condition on Extraction domains (CED,…

Hierarchically porous MgCo2O4 nanochain networks: template-free synthesis and catalytic application

Science.gov (United States)

Guan, Xiangfeng; Yu, Yunlong; Li, Xiaoyan; Chen, Dagui; Luo, Peihui; Zhang, Yu; Guo, Shanxin

2018-01-01

In this work, hierarchically porous MgCo2O4 nanochain networks were successfully synthesized by a novel template-free method realized via a facile solvothermal synthesis followed by a heat treatment. The morphologies of MgCo2O4 precursor could be adjusted from nanosheets to nanobelts and finally to interwoven nanowires, depending on the volume ratio of diethylene glycol to deionized water in the solution. After calcination, the interwoven precursor nanowires were transformed to hierarchical MgCo2O4 nanochain networks with marco-/meso-porosity, which are composed of 10-20 nm nanoparticles connected one by one. Moreover, the relative formation mechanism of the MgCo2O4 nanochain networks was discussed. More importantly, when evaluated as catalytic additive for AP thermal decomposition, the MgCo2O4 nanochain networks show excellent accelerating effect. It is benefited from the unique hierarchically porous network structure and multicomponent effect, which effectively accelerates ammonia oxidation and {{{{ClO}}}4}- species dissociation. This approach opens the way to design other hierarchically porous multicomponent metal oxides.

The Effect of Brand Equity and Perceived Value on Customer Revisit Intention: A Study in Quick-Service Restaurants in Vietnam

Directory of Open Access Journals (Sweden)

Ly Thi Minh Pham

2016-10-01

Full Text Available The purpose of this study is to examine how brand equity, from a customer point of view, influences quick-service restaurant revisit intention. The authors propose a conceptual framework in which three dimensions of brand equity including brand associations combined with brand awareness, perceived quality, brand loyalty and perceived value are related to revisit intention. Data from 570 customers who had visited four quick-service restaurants in Ho Chi Minh City were used for the structural equation modelling (SEM analysis. The results show that strong brand equity is significantly correlated with revisit intention. Additionally, the effect of brand equity on revisit intention was mediated by perceived value, among others. Overall, this study emphasizes the importance of perceived value in lodging in the customer’s mind. Finally, managerial implications are presented based on the study results.

Literary Origins of the Term "School Psychologist" Revisited

Science.gov (United States)

Fagan, Thomas K.

2005-01-01

Previous research on the literary origins of the term "school psychologist" is revisited, and conclusions are revised in light of new evidence. It appears that the origin of the term in the American literature occurred as early as 1898 in an article by Hugo Munsterberg, predating the usage by Wilhelm Stern in 1911. The early references to the…

A Multi-Level Model of Moral Functioning Revisited

Science.gov (United States)

Reed, Don Collins

2009-01-01

The model of moral functioning scaffolded in the 2008 "JME" Special Issue is here revisited in response to three papers criticising that volume. As guest editor of that Special Issue I have formulated the main body of this response, concerning the dynamic systems approach to moral development, the problem of moral relativism and the role of…

Solvothermal fabrication of activated semi-coke supported TiO{sub 2}-rGO nanocomposite photocatalysts and application for NO removal under visible light

Energy Technology Data Exchange (ETDEWEB)

Yang, Weiwei; Li, Chunhu, E-mail: lichunhu@ouc.edu.cn; Wang, Liang; Sun, ShengNan; Yan, Xin

2015-10-30

Highlights: • Activated semi-coke supported TiO{sub 2}-rGO photocatalysts were fabricated by one-step solvothermal method. • The photocatalytic performance for NO removal was studied under visible light irradiation. • The introduction of rGO is responsible for superior photocatalytic activity. • Optimum operational parameters at 70 °C, with 8% O{sub 2} and 8% relative humidity were obtained. • Thermal vapor regeneration is the most suitable generation method. - Abstract: The photocatalysts of activated semi-coke supported TiO{sub 2}-rGO nanocomposite (TiO{sub 2}-rGO/ASC) with different contents of reduced graphene oxide were fabricated by one-step solvothermal method for NO removal under visible light irradiation. It was confirmed that 8% content of reduced graphene oxide presented the best NO photooxidation performance under visible light irradiation at 70 °C with 350–400 mg/m{sup 3} NO,5% O{sub 2} and 5% relative humidity. The reasons for improved activity were discussed, alloyed with the mechanism of producing CO. Detailed structural information of TiO{sub 2}-rGO/ASC photocatalysts was characterized by scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDX), X-ray diffraction analysis (XRD), UV–Vis diffuse reflectance spectra (UV–Vis DRS) and photoluminescence (PL), which indicated that the introduction of rGO was responsible for well dispersion, smaller crystalline size, red shift of absorption band and suppressing quick photo-induced charges recombination of TiO{sub 2}-rGO/ASC photocatalysts. Optimization of operational parameters with 70 °C, 8% O{sub 2} and 8% relative humidity were also obtained. Deactivation of TiO{sub 2}-rGO/ASC photocatalysts for NO removal was investigated by Fourier-transform infrared (FTIR) analysis. Regeneration experiments showed that thermal vapor regeneration would be optimal method owing to excellent regenerative capacity and inexpensive procedure.

Short or Long End of the Lever? Associations between Provider Communication of the “Asthma-Action Plan” and Outpatient Revisits for Pediatric Asthma

Science.gov (United States)

Rangachari, Pavani; Mehta, Renuka; Rethemeyer, R. Karl; Ferrang, Carole; Dennis, Clifton; Redd, Vickie

2017-01-01

Background At the Children’s Hospital of Georgia (CHOG), we found that outpatient revisits for pediatric asthma were significantly above national norms. According to the NIH, costly hospital revisits for asthma can be prevented through guidelines-based self-management of asthma, central to which, is the use of a written Asthma-Action Plan (AAP). Purpose The asthma services literature has emphasized the role of the healthcare provider in promoting asthma self-management using the AAP, to prevent hospital revisits. On the other hand, the asthma policy literature has emphasized the need for community-based interventions to promote asthma self-management. A gap remains in understanding the extent of leverage that healthcare providers may have in preventing hospital revisits for asthma, through effective communication of AAP in the outpatient setting. Our study sought to address this gap. Methods We conducted a 6-month intervention to implement “patient-and-family-centered communication of the AAP” in CHOG outpatient clinics, based on the “change-management” theoretical framework. Provider communication of AAP was assessed through a survey of “Parent Understanding of the Child’s AAP.” A quasi-experimental approach was used to measure outpatient revisits for pediatric asthma, pre- and post-intervention. Results Survey results showed that provider communication of the AAP was unanimously perceived highly positively by parents of pediatric asthma patients, across various metrics of patient-centered care. However, there were no statistically significant differences in outpatient “revisit behavior” for pediatric asthma between pre- and post-intervention periods after controlling for several demographic variables. Additionally, revisits remained significantly above national norms. Conclusions Results suggest limited potential of “effective provider communication of AAP,” in reducing outpatient revisits for pediatric asthma; and indicate need for

Reframing in dentistry: Revisited

Directory of Open Access Journals (Sweden)

Sivakumar Nuvvula

2013-01-01

Full Text Available The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child′s behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice.

Efficient solvothermal wet in situ transesterification of Nannochloropsis gaditana for biodiesel production.

Science.gov (United States)

Kim, Bora; Chang, Yong Keun; Lee, Jae W

2017-05-01

In situ transesterification of wet microalgae is a promising, simplified alternative biodiesel production process that replaces multiple operations of cell drying, extraction, and transesterification reaction. This study addresses enhanced biodiesel production from Nannochloropsis gaditana at elevated temperatures. Compared with the previously reported in situ transesterification process of conducting the reaction at a temperature ranging from 95 to 125 °C, the present work employs higher temperatures of at least 150 °C. This relatively harsh condition allows much less acid catalyst with or without co-solvent to be used during this single extraction-conversion process. Without any co-solvent, 0.58% (v/v) of H 2 SO 4 in the reaction medium can achieve 90 wt% of the total lipid conversion to biodiesel at 170 °C when the moisture content of wet algal paste is 80 wt%. Here, the effects of temperature, acid catalyst, and co-solvent on the FAEE yield and specification were scrutinized, and the reaction kinetic was investigated to understand the solvothermal in situ transesterification reaction at the high temperature. Having a biphasic system (water/chloroform) during the reaction also helped to meet biodiesel quality standard EN 14214, as Na + , K + , Ca 2+ , Mg 2+ cations and phosphorus were detected only below 5 ppm. With highlights on the economic feasibility, wet in situ transesterification at the high temperature can contribute to sustainable production of biodiesel from microalgae by reducing the chemical input and relieve the burden of extensive post purification process, therefore a step towards green process.

Graphene-supported SnO2 nanoparticles prepared by a solvothermal approach for an enhanced electrochemical performance in lithium-ion batteries.

Science.gov (United States)

Wang, Bei; Su, Dawei; Park, Jinsoo; Ahn, Hyojun; Wang, Guoxiu

2012-04-13

SnO2 nanoparticles were dispersed on graphene nanosheets through a solvothermal approach using ethylene glycol as the solvent. The uniform distribution of SnO2 nanoparticles on graphene nanosheets has been confirmed by scanning electron microscopy and transmission electron microscopy. The particle size of SnO2 was determined to be around 5 nm. The as-synthesized SnO2/graphene nanocomposite exhibited an enhanced electrochemical performance in lithium-ion batteries, compared with bare graphene nanosheets and bare SnO2 nanoparticles. The SnO2/graphene nanocomposite electrode delivered a reversible lithium storage capacity of 830 mAh g-1 and a stable cyclability up to 100 cycles. The excellent electrochemical properties of this graphene-supported nanocomposite could be attributed to the insertion of nanoparticles between graphene nanolayers and the optimized nanoparticles distribution on graphene nanosheets.

Preparation of CoFeO Nanocrystallites by Solvothermal Process and Its Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

Directory of Open Access Journals (Sweden)

Shusen Zhao

2010-01-01

Full Text Available Nanometer cobalt ferrite (CoFe2O4 was synthesized by polyol-medium solvothermal method and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and selected area electron diffraction (SAED. Further, the catalytic activity and kinetic parameters of CoFe2O4 nanocrystallites on the thermal decomposition behavior of ammonium perchlorate (AP have been investigated by thermogravimetry and differential scanning calorimetry analysis (TG-DSC. The results imply that the catalytic performance of CoFe2O4 nanocrystallites is significant and the decrease in the activation energy and the increase in the rate constant for AP further confirm the enhancement in catalytic activity of CoFe2O4 nanocrystallites. A mechanism based on an proton transfer process has also been proposed for AP in the presence of CoFe2O4 nanocrystallites.

Revisiting Jack Goody to Rethink Determinisms in Literacy Studies

Science.gov (United States)

Collin, Ross

2013-01-01

This article revisits Goody's arguments about literacy's influence on social arrangements, culture, cognition, economics, and other domains of existence. Whereas some of his arguments tend toward technological determinism (i.e., literacy causes change in the world), other of his arguments construe literacy as a force that shapes and is shaped by…

A control center design revisited: learning from users’ appropriation

DEFF Research Database (Denmark)

Souza da Conceição, Carolina; Cordeiro, Cláudia

2014-01-01

This paper aims to present the lessons learned during a control center design project by revisiting another control center from the same company designed two and a half years before by the same project team. In light of the experience with the first project and its analysis, the designers and res...

Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures.

Science.gov (United States)

Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

2011-09-01

The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

PENGARUH GUIDE PERFORMANCE DAN QUALITY TOURISM SERVICE TERHADAP REVISIT INTENTION DI KEBUN RAYA BOGOR

Directory of Open Access Journals (Sweden)

Rian Andriani

2016-11-01

ABSTRACT Bogor Botanical Gardens is one of tourist destination in Bogor City, West Java, which the geographical in a strategic location between two big cities, Jakarta and Bandung. This location factor is can become an opportunity for Bogor Botanical Gardens to become a favorite tourist destination in Bogor City. Guide Performance and Quality Tourism Service is one of part of the tourism, so the researcher focus to Guide Performance and Quality Tourism Service To Revisit Intention in Bogor Botanical Gardens. In this research, the researcher used quantitative methode with descriptive verificative. The researcher used 100 respondent for a sample. In this research, the researcher used multiple linier regresion analysis with hypotesis test used determination coefficient test and F test. The classical assumption of this research is used normality test, multicollinearity test, heteroskedastisitas test and auto correlation test. In this research, the Guide Performance and Quality Tourism Service factors has an influence 33,2% of Revisit Intention in Bogor Botanical Garden. Keywords: Guide Performance, Quality Tourism Service and Revisit Intention

Revisiting the Political Economy of Communication

Directory of Open Access Journals (Sweden)

Nicholas Garnham

2014-02-01

The task of the paper and the seminar was to revisit some of Nicholas Garnham’s ideas, writings and contributions to the study of the Political Economy of Communication and to reflect on the concepts, history, current status and perspectives of this field and the broader study of political economy today. The topics covered include Raymond Williams’ cultural materialism, Pierre Bourdieu’s sociology of culture, the debate between Political Economy and Cultural Studies, information society theory, Karl Marx’s theory and the critique of capitalism.

Synthesis of grape-like carbon nanospheres and their application as photocatalyst and electrocatalyst

Energy Technology Data Exchange (ETDEWEB)

Mahajan, Mani, E-mail: manimahajan86@gmail.com; Singla, Gourav, E-mail: gsinghla@gmail.com; Singh, K., E-mail: kusingh@thapar.edu; Pandey, O.P., E-mail: oppandey@thapar.edu

2015-12-15

Carbon nanospheres of grape-like structure (CNS) with diameter ranging from 40 to 50 nm and wall thickness of 6–8 nm were synthesized by solvothermal route. The phase structure, morphology, microstructure, thermal stability, disorder and optical properties of synthesized CNS were investigated by various characterization techniques. The possible formation and growth mechanism for CNS were discussed on the basis of the in-build reaction conditions. The degradation study of organic pollutants (methylene blue) in UV light in the presence of synthesized CNS was done. The stability of the CNS in electrochemical performance was also discussed at the different potential window and compared its electrocatalytic activity with platinum supported on CNS which shows the better response for oxygen reduction reactions (ORR) at an optimized potential window (–0.2 to 1.0 V vs SCE). - Graphical abstract: A representative synthesis mechanism of carbon nano sphere (CNS) showing spherical morphology with its photo as well as electrocatalyst properties. - Highlights: • Carbon nanospheres (CNS) have been synthesized using in situ chemical-reduction route. • The bare CNS shows good luminescence and photocatalytic applications. • The Pt/CNS shows better electrochemical performance than the reported Pt/C.

Synthesis, characterization and application of metal organic frameworks in the adsorption of dimethylamine

International Nuclear Information System (INIS)

Sun-Kou, Maria del Rosario; Bravo Hualpa, Fabiola; Beltran Suito, Rodrigo; Samanamu, Christian; Picasso Escobar, Gino

2014-01-01

This study investigated the removal of dimethylamine (DMA) by an adsorption mechanism using metal-organic frameworks (MOFs). The synthesis of the MOFs was performed by solvothermal methods. The characterization of the MOF obtained was made by attenuated total reflectance spectroscopy (ATR), proton nuclear magnetic resonance spectroscopy ("1H-NMR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The XRD diffractograms allowed to identify the structure of MOF as Dashkovaite, which has the molecular formula Mg(HCOO)_2.2H_2O; while the ATR studies revealed the presence of carbonyl group as most important functional group in the MOF structure. The morphological analysis showed that the MOF crystalline particles had a hexagonal shape, formed from filaments of around 7,5-8 microns in length. Adsorption experiments showed that the MOF had a high adsorption capacity of DMA (q_e= 307,96 mg.g"-"1). The kinetic data were fitted to the pseudo second order equation and the Elovich equation, while the adsorption isotherm was fitted to the Temkin equation and the Dubinin - Radushkevich equation, processes related to chemisorptions preferably on a heterogeneous surface. (author)

Zinc oxide hollow micro spheres and nano rods: Synthesis and applications in gas sensor

International Nuclear Information System (INIS)

Jamil, Saba; Janjua, Muhammad Ramzan Saeed Ashraf; Ahmad, Tauqeer; Mehmood, Tahir; Li, Songnan; Jing, Xiaoyan

2014-01-01

Zinc oxide nano rods and micro hollow spheres are successfully fabricated by adopting a simple solvo-thermal approach without employing any surfactant/template by keeping heating time as variable. The prepared products are characterized by using different instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to investigate the morphological dependence on the reaction time, analogous experiments with various reaction times are carried out. Depending upon heating time, different morphological forms have been identified such as hollow microsphere (4 μm to 5 μm) and nano rods with an average diameter of approximately 100 nm. The fabricated materials are also tested for ethanol gas sensor applications and zinc oxide hollow microsphere proven to be an efficient gas sensing materials. Nitrogen adsorption–desorption measurement was performed to understand better performance of zinc oxide micro hollow spheres as effective ethanol gas sensing material. - Graphical abstract: Graphical abstract is represented by zinc oxide sphere (prepared by simple solvothermal approach), its XRD pattern(characterization) and finally its application in gas sensing. - Highlights: • Zinc oxide spheres were prepared by using solvothermal method. • Detailed description of the morphology of microspheres assembled by nano rods. • Formation mechanism of zinc oxide spheres assembled by nano rods. • Zinc oxide spheres and nano rods displayed very good gas sensing ability

The vacuum structure, special relativity theory and quantum mechanics revisited: a field theory-no-geometry approach

International Nuclear Information System (INIS)

Bogolubov, N.N. Jr.; Prykarpatsky, A.K.; Ufuk Taneri

2008-07-01

The main fundamental principles characterizing the vacuum field structure are formulated and the modeling of the related vacuum medium and charged point particle dynamics by means of de- vised field theoretic tools are analyzed. The Maxwell electrodynamic theory is revisited and newly derived from the suggested vacuum field structure principles and the classical special relativity theory relationship between the energy and the corresponding point particle mass is revisited and newly obtained. The Lorentz force expression with respect to arbitrary non-inertial reference frames is revisited and discussed in detail, and some new interpretations of relations between the special relativity theory and quantum mechanics are presented. The famous quantum-mechanical Schroedinger type equations for a relativistic point particle in the external potential and magnetic fields within the quasiclassical approximation as the Planck constant (h/2π) → 0 and the light velocity c → ∞ are obtained. (author)

K Mbugua The Problem of Hell Revisited pp93-103

African Journals Online (AJOL)

K Mbugua

The Problem of Hell Revisited: Towards a Gentler Theology of Hell 93 ... One who, after He has killed, has authority to cast into hell; yes, I tell you, fear. Him! .... Suppose your spouse or parent or child goes to hell and you go to heaven.

What matters to infrequent customers: a pragmatic approach to understanding perceived value and intention to revisit trendy coffee café.

Science.gov (United States)

Ting, Hiram; Thurasamy, Ramayah

2016-01-01

Notwithstanding the rise of trendy coffee café, little is done to investigate revisit intention towards the café in the context of developing markets. In particular, there is a lack of study which provides theoretical and practical explanation to the perceptions and behaviours of infrequent customers. Hence, the study aims to look into the subject matter by using the theory of reasoned action and social exchange theory as the underpinning basis. The framework proposed by Pine and Gilmore (Strat Leadersh 28:18-23, 2000), which asserts the importance of product quality, service quality and experience quality in a progressive manner, is used to decompose perceived value in the model so as to determine their effects on intention to revisit the café. Given the importance to gain practical insights into revisit intention of infrequent customers, pragmatism stance is assumed. Explanatory sequential mixed-method design is thus adopted whereby qualitative approach is used to confirm and complement quantitative findings. Self-administered questionnaire-based survey is first administered before personal interview is carried out at various cafés. Partial least squares structural equation modelling and content analysis are appropriated successively. In the quantitative findings, although product quality, service quality and experience quality are found to have positive effect on perceived value and revisit intention towards trendy coffee café, experience quality is found to have the greater effect than the others among the infrequent customers. The qualitative findings not only confirm their importance, but most importantly explain the favourable impressions they have at trendy coffee café based on their last in-store experience. While product and service quality might not necessary stimulate them to revisit trendy coffee café, experience quality driven by purposes of visit would likely affect their intention to revisit. As retaining customers is of utmost importance to

Synthesis of highly c-oriented ZIF-69 membranes by secondary growth and their gas permeation properties

KAUST Repository

Liu, Yunyang

2011-09-01

A seeded growth procedure was successfully developed to synthesize highly c-oriented and well-intergrown zeolitic imidazolate framework-69 (ZIF-69) membranes on porous α-alumina substrates. The synthesis conditions were optimized both for seed preparation and for secondary growth. For seeding, a facile method was developed to prepare smaller and flat ZIF-69 microcrystals in order to make thin and c-oriented seed layers. While for secondary growth, a synthesis condition that favored the growth along the c-direction was chosen in order to form highly c-oriented ZIF-69 membranes after growth. As a result, the majority of ZIF-69 grains inside the membrane have their straight channels along the crystallographic c-axis aligned perpendicularly to the substrate surface. Such alignment was confirmed by both XRD and pole figure analysis. The mixture-gas separation studies that were carried out at room temperature and 1atm gave separation factors of 6.3, 5.0, 4.6 for CO2/N2, CO2/CO and CO2/CH4 respectively, and a permeance of ∼1.0×10-7molm-2s-1Pa-1 for CO2 in almost all mixtures. Both the separation factor and permeance were better than the performance of the ZIF-69 membranes prepared by the in situ solvothermal method due to improvement in the membrane microstructure by the seeded growth method. © 2011 Elsevier B.V.

Synthesis of highly c-oriented ZIF-69 membranes by secondary growth and their gas permeation properties

KAUST Repository

Liu, Yunyang; Zeng, Gaofeng; Pan, Yichang; Lai, Zhiping

2011-01-01

A seeded growth procedure was successfully developed to synthesize highly c-oriented and well-intergrown zeolitic imidazolate framework-69 (ZIF-69) membranes on porous α-alumina substrates. The synthesis conditions were optimized both for seed preparation and for secondary growth. For seeding, a facile method was developed to prepare smaller and flat ZIF-69 microcrystals in order to make thin and c-oriented seed layers. While for secondary growth, a synthesis condition that favored the growth along the c-direction was chosen in order to form highly c-oriented ZIF-69 membranes after growth. As a result, the majority of ZIF-69 grains inside the membrane have their straight channels along the crystallographic c-axis aligned perpendicularly to the substrate surface. Such alignment was confirmed by both XRD and pole figure analysis. The mixture-gas separation studies that were carried out at room temperature and 1atm gave separation factors of 6.3, 5.0, 4.6 for CO2/N2, CO2/CO and CO2/CH4 respectively, and a permeance of ∼1.0×10-7molm-2s-1Pa-1 for CO2 in almost all mixtures. Both the separation factor and permeance were better than the performance of the ZIF-69 membranes prepared by the in situ solvothermal method due to improvement in the membrane microstructure by the seeded growth method. © 2011 Elsevier B.V.

Radiative corrections to neutrino deep inelastic scattering revisited

International Nuclear Information System (INIS)

Arbuzov, Andrej B.; Bardin, Dmitry Yu.; Kalinovskaya, Lidia V.

2005-01-01

Radiative corrections to neutrino deep inelastic scattering are revisited. One-loop electroweak corrections are re-calculated within the automatic SANC system. Terms with mass singularities are treated including higher order leading logarithmic corrections. Scheme dependence of corrections due to weak interactions is investigated. The results are implemented into the data analysis of the NOMAD experiment. The present theoretical accuracy in description of the process is discussed

Doppler Processing with Ultra-Wideband (UWB) Radar Revisited

Science.gov (United States)

2018-01-01

REPORT TYPE Technical Note 3. DATES COVERED (From - To) December 2017 4. TITLE AND SUBTITLE Doppler Processing with Ultra-Wideband (UWB) Radar...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This technical note revisits previous work performed at the US Army Research Laboratory related to...target considered previously is proportional to a delayed version of the transmitted signal, up to a complex constant factor. We write the received

Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited

DEFF Research Database (Denmark)

Miao, L.; Lomholt, Michael Andersen; Kleis, J.

2002-01-01

In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy......In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations...... of the phenomenological constants in a canonical continuum description of fluid lipid-bilayer membranes and shown the consequences of this new interpretation in terms of the characteristics of the dynamics of vesicle shape fluctuations. Moreover, we have used the systematic formulation of our theory as a framework...... against which we have discussed the previously existing theories and their discrepancies. Finally, we have made a systematic prediction about the system-dependent characteristics of the relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a view of experimental studies...

Revisiting Constructivist Teaching Methods in Ontario Colleges Preparing for Accreditation

Science.gov (United States)

Schultz, Rachel A.

2015-01-01

At the time of writing, the first community colleges in Ontario were preparing for transition to an accreditation model from an audit system. This paper revisits constructivist literature, arguing that a more pragmatic definition of constructivism effectively blends positivist and interactionist philosophies to achieve both student centred…

Thorbecke Revisited : The Role of Doctrinaire Liberalism in Dutch Politics

NARCIS (Netherlands)

Drentje, Jan

2011-01-01

Thorbecke Revisited: The Role of Doctrinaire Liberalism in Dutch Politics In the political history of the nineteenth century Thorbecke played a crucial role. As the architect of the 1848 liberal constitutional reform he led three cabinets. In many ways he dominated the political discourse during the

Effect of processing parameters on the electrochemical performance of graphene/ nickel ferrite (G-NF nanocomposite

Directory of Open Access Journals (Sweden)

Elham Kamali Heidari

2015-06-01

Full Text Available Fuel cells, secondary batteries and capacitors are among many promising energy storage devices. In particular, supercapacitors have attracted much attention because of their long life cycle and high power density. Graphene/nickel ferrite(G-NF based supercapacitors were successfully fabricated through a one-step facile solvothermal route. Effects of synthesis conditions i.e. solvothermal time and temperature, on the powder particle characteristics were evaluated using x-ray photoelectron spectroscopy (XPS, powder x-ray diffraction (XRD and high-resolution transmission electron microscopy (HRTEM. Fast Fourier transformation (FFT patterns were also recorded on the HRTEM microscope to determine the lattice and crystallinity of the nanocomposites. Structural and chemical studies proved that increasing the solvothermal duration and temperature leads to improved crystallinity of NiFe2O4phase as well as higher degree of reduction of graphene oxide to graphene. The electrochemical measurements showed that solvothermal conditions of 180°C and 10h produces the highest specific capacity of 312 and 196 F g-1 at current densities of 1 and 5 A g-1, respectively calculated from charge-discharge test. This G-NF electrode material, also showed a capacity of 105 F g-1 after 1500 cycles at current density of 10 A g-1 which makes it an outstanding supercapacitor material with promising long cycle electrochemical stability and performance.

Revisiting Cementoblastoma with a Rare Case Presentation

Directory of Open Access Journals (Sweden)

Vijayanirmala Subramani

2017-01-01

Full Text Available Cementoblastoma is a rare benign odontogenic neoplasm which is characterized by the proliferation of cellular cementum. Diagnosis of cementoblastoma is challenging because of its protracted clinical, radiographic features, and bland histological appearance; most often cementoblastoma is often confused with other cementum and bone originated lesions. The aim of this article is to overview/revisit, approach the diagnosis of cementoblastoma, and also present a unique radiographic appearance of a cementoblastoma lesion associated with an impacted tooth.

Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln==Sm, Eu, Gd) and [Ln(dien)2(1κ2-AsS4)] (Ln==Tb, Dy, Ho)

International Nuclear Information System (INIS)

Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

2013-01-01

Solvothermal reactions of Ln 2 O 3 , As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien) 2 (μ-1κ,2κ 2 -AsS 4 )] n [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien) 2 (1κ 2 -AsS 4 )] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln 2 O 3 oxides were converted to [Ln(dien) 2 ] 3+ complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS 4 unit. In 1−3, the AsS 4 units interconnect the [Ln(dien) 2 ] 3+ cations via Ln−S bonds as tridentate μ-1κ,2κ 2 -AsS 4 bridging ligands, resulting in the neutral coordination polymers [Ln(dien) 2 (μ-1κ,2κ 2 -AsS 4 )] n (Ln1). In 4−6, the AsS 4 units coordinate with the Ln 3+ ion of [Ln(dien) 2 ] 3+ as 1κ 2 -AsS 4 chelating ligands to form neutral coordination compounds [Ln(dien) 2 (1κ 2 -AsS 4 )] (Ln2). The Ln 3+ ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln 3+ ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien) 2 (μ-1κ,2κ 2 -AsS 4 )] n and [Ln(dien) 2 (1κ 2 -AsS 4 )] were prepared by solvothermal methods and the soft Lewis basic AsS 4 3– ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS 4 ligand coordinate Ln 3+ ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors with optical band gaps in the range 2.18−3.21 eV

Synthèse et caractérisation de composés fluorés pour le piégeage de fluorures gazeux

OpenAIRE

Clarenc , Romain Pierre

2010-01-01

This work deals with the synthesis and characterization of alkali, alkali-earth and rare earthbased fluorides and the reactivity of the latter with ReF6 for UF6 purification. In a first part,we focused our attention on the synthesis of KMgF3, MgF2 and CaF2 high surface area metalfluorides coupling both microwave assisted solvothermal process and a fluorination step withelemental fluorine (F2). The higher the surface area, the higher the oxygen rate. Thesenanofluorides exhibit Lewis basic char...

Microwave-assisted synthesis of CuInSe{sub 2} nanoparticles in low-absorbing solvents

Energy Technology Data Exchange (ETDEWEB)

Oleksak, Richard P.; Flynn, Brendan T.; Herman, Gregory S. [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR (United States); Schut, David M. [Voxtel Inc., Eugene, OR (United States)

2014-01-15

Copper indium diselenide (CIS) nanoparticles were synthesized using a microwave-assisted one-pot solvothermal approach. For these studies high microwave-absorbing precursors were used in combination with low microwave absorbing solvents tri-n-octylphosphine (TOP) and oleic acid (OA) to investigate the effect of selective heating of the precursors on nanoparticle synthesis. High-resolution transmission electron microscopy (TEM) results indicated that the nanoparticles were spherical, crystalline and 4-5 nm in diameter. X-ray diffraction (XRD) results indicated that the nanoparticles had a body-centered tetragonal structure with planar defects that decreased in concentration with increasing reaction temperature and reaction time. The nanoparticle compositions varied depending on the reaction conditions and the compositions were found to approach stoichiometry for increased reaction times. Fourier transform infrared (FTIR) spectroscopy indicated both solvents adsorbed to the nanoparticle surface and energy dispersive spectroscopy indicated that these ligands became chlorinated during the reaction. The uniform temperature profile offered by the microwave heating allowed for highly reproducible batch-to-batch reactions, allowing for tight control over composition and defect concentration. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Increased 30-Day Emergency Department Revisits Among Homeless Patients with Mental Health Conditions

Directory of Open Access Journals (Sweden)

Chun Nok Lam

2016-09-01

Full Text Available Introduction: Patients with mental health conditions frequently use emergency medical services. Many suffer from substance use and homelessness. If they use the emergency department (ED as their primary source of care, potentially preventable frequent ED revisits and hospital readmissions can worsen an already crowded healthcare system. However, the magnitude to which homelessness affects health service utilization among patients with mental health conditions remains unclear in the medical community. This study assessed the impact of homelessness on 30-day ED revisits and hospital readmissions among patients presenting with mental health conditions in an urban, safety-net hospital. Methods: We conducted a secondary analysis of administrative data on all adult ED visits in 2012 in an urban safety-net hospital. Patient demographics, mental health status, homelessness, insurance coverage, level of acuity, and ED disposition per ED visit were analyzed using multilevel modeling to control for multiple visits nested within patients. We performed multivariate logistic regressions to evaluate if homelessness moderated the likelihood of mental health patients’ 30-day ED revisits and hospital readmissions. Results: Study included 139,414 adult ED visits from 92,307 unique patients (43.5±15.1 years, 51.3% male, 68.2% Hispanic/Latino. Nearly 8% of patients presented with mental health conditions, while 4.6% were homeless at any time during the study period. Among patients with mental health conditions, being homeless contributed to an additional 28.0% increase in likelihood (4.28 to 5.48 odds of 30-day ED revisits and 38.2% increase in likelihood (2.04 to 2.82 odds of hospital readmission, compared to non-homeless, non-mental health (NHNM patients as the base category. Adjusted predicted probabilities showed that homeless patients presenting with mental health conditions have a 31.1% chance of returning to the ED within 30-day post discharge and a 3

Synthesis and characterization of ester and amide derivatives of titanium(IV) carboxymethylphosphonate

Czech Academy of Sciences Publication Activity Database

Melánová, Klára; Beneš, L.; Trchová, Miroslava; Svoboda, Jan; Zima, Vítězslav

2013-01-01

Roč. 202, June (2013), s. 93-98 ISSN 0022-4596 R&D Projects: GA ČR GA203/08/0208 Institutional support: RVO:61389013 Keywords : layered titanium organohphosphonates * solvothermal treatment IR spectroscopy * grafting Subject RIV: CA - Inorganic Chemistry Impact factor: 2.200, year: 2013

Solvothermal syntheses of Bi and Zn co-doped TiO_2 with enhanced electron-hole separation and efficient photodegradation of gaseous toluene under visible-light

International Nuclear Information System (INIS)

Li, Juan-Juan; Cai, Song-Cai; Xu, Zhen; Chen, Xi; Chen, Jin; Jia, Hong-Peng; Chen, Jing

2017-01-01

Highlights: • Bi-Zn co-doped TiO_2 catalysts were prepared by solvothermal route. • The incorporation of Bi doping into the TiO_2 generates intermediate energy levels. • Bi and Zn doping showed the enhanced absorption in visible-light region. • Zn dopant acts as a mediator of interfacial charge transfer. • TiBi_1_._9_%Zn_1_%O_2 exhibited high photocatalytic degradation for toluene. - Abstract: This study investigated the effects of Bi doped and Bi-Zn co-doped TiO_2 on photodegradation of gaseous toluene. The doped TiO_2 with various concentration of metal was prepared using the solvothermal route and characterized by SEM, XRD, Raman, BET, DRS, XPS, PL and EPR. Their photocatalytic activities under visible-light irradiation were drastically influenced by the dopant content. The results showed that moderate metal doping levels were obviously beneficial for the toluene degradation, while high doping levels suppressed the photocatalytic activity. The photocatalytic degradation of toluene over TiBi_1_._9_%O_2 and TiBi_1_._9_%Zn_1_%O_2 can reach to 51% and 93%, respectively, which are much higher than 25% of TiO_2. Bi doping into TiO_2 lattice generates new intermediate energy level of Bi below the CB edge of TiO_2. The electron excitation from the VB to Bi orbitals results in the decreased band gap, extended absorption of visible-light and thus enhances its photocatalytic efficiency. Zn doping not only further enhances the absorption in this visible-light region, but also Zn dopant exists as the form of ZnO crystallites located on the interfaces of TiO_2 agglomerates and acts as a mediator of interfacial charge transfer to suppress the electron-hole recombination. These synergistic effects are responsible for the enhanced photocatalytic performance.

Solvothermal synthesis of a new 3-D mixed-metal sulfide framework, (H{sub 1.33}tren)[In{sub 2.67}Sb{sub 1.33}S{sub 8}]·tren

Energy Technology Data Exchange (ETDEWEB)

Lampkin, John D., E-mail: j.lampkin@pgr.rdg.ac.uk; Powell, Anthony V., E-mail: a.v.powell@rdg.ac.uk; Chippindale, Ann M., E-mail: a.m.chippindale@rdg.ac.uk

2016-11-15

A new indium(III) antimony(V) sulfide, (H{sub 1.33}tren)[In{sub 2.67}Sb{sub 1.33}S{sub 8}]·tren, has been prepared solvothermally at 433 K. The compound crystallises in the tetragonal space group I-42d (lattice parameters, a=12.6248(5) and c=19.4387(18) Å at 150 K) and contains adamantane-like T2 supertetrahedral units comprised of corner-sharing InS{sub 4}{sup 5−} and SbS{sub 4}{sup 3−} tetrahedra. The adamantane-like units are then linked through sulfur vertices to generate an open, 3-D framework structure containing large pores in which neutral, protonated tren (tris(2-aminoethylene)amine) molecules reside. The presence of the organic components was confirmed by solid-state {sup 13}C NMR (10 kHz), combustion and thermogravimetric analysis. The band gap, obtained from UV–vis diffuse reflectance measurements, is 2.7(2) eV. Stirring with either water or alkali-metal salt solution leads to removal of the neutral tren molecules and an ~9% reduction in unit-cell volume on formation of (H{sub 1.33}tren)[In{sub 2.67}Sb{sub 1.33}S{sub 8}]·(H{sub 2}O){sub 4}. - Graphical abstract: Linking of In(III)-Sb(V)-S adamantane units to form a 3-D open framework. - Highlights: • Preparation and structural characterisation of a new mixed-metal thiometallate. • The first mixed In(III)/Sb(V) supertetrahedron. • Optical band gap of 2.7(2) eV. • Soaking in aqueous alkali-metal solutions leads to removal of ca. 50% of the organic content.

Surface tension in soap films: revisiting a classic demonstration

International Nuclear Information System (INIS)

Behroozi, F

2010-01-01

We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)

The Neutrosophic Logic View to Schrodinger's Cat Paradox, Revisited

Directory of Open Access Journals (Sweden)

Florentin Smarandache

2008-07-01

Full Text Available The present article discusses Neutrosophic logic view to Schrodinger's cat paradox. We argue that this paradox involves some degree of indeterminacy (unknown which Neutrosophic logic can take into consideration, whereas other methods including Fuzzy logic cannot. To make this proposition clear, we revisit our previous paper by offering an illustration using modified coin tossing problem, known as Parrondo's game.

Surface tension in soap films: revisiting a classic demonstration

Energy Technology Data Exchange (ETDEWEB)

Behroozi, F [Department of Physics, University of Northern Iowa, Cedar Falls, IA 50614 (United States)], E-mail: behroozi@uni.edu

2010-01-15

We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)

Revisiting the quantum harmonic oscillator via unilateral Fourier transforms

International Nuclear Information System (INIS)

Nogueira, Pedro H F; Castro, Antonio S de

2016-01-01

The literature on the exponential Fourier approach to the one-dimensional quantum harmonic oscillator problem is revised and criticized. It is shown that the solution of this problem has been built on faulty premises. The problem is revisited via the Fourier sine and cosine transform method and the stationary states are properly determined by requiring definite parity and square-integrable eigenfunctions. (paper)

Transport benchmarks for one-dimensional binary Markovian mixtures revisited

International Nuclear Information System (INIS)

Malvagi, F.

2013-01-01

The classic benchmarks for transport through a binary Markovian mixture are revisited to look at the probability distribution function of the chosen 'results': reflection, transmission and scalar flux. We argue that the knowledge of the ensemble averaged results is not sufficient for reliable predictions: a measure of the dispersion must also be obtained. An algorithm to estimate this dispersion is tested. (author)

Oriented growth of magnetite along the carbon nanotubes via covalently bonded method in a simple solvothermal system

Energy Technology Data Exchange (ETDEWEB)

Zhan Yingqing; Zhao Rui; Meng Fanbing; Lei Yajie; Zhong Jiachun; Yang Xulin [Research Branch of Functional Materials, Institute of Microelectronic and Solid State Electronic, University of Electronic Science and Technology of China, Chengdu 610054 (China); Liu Xiaobo, E-mail: liuxb@uestc.edu.cn [Research Branch of Functional Materials, Institute of Microelectronic and Solid State Electronic, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2011-06-15

Highlights: > Novel CNTs/magnetite hybrid materials were prepared via covalently bonded method. > Stable interaction between nitriles and iron ion promoted the oriented growth of magnetite. > The hybrid material exhibited higher magnetism and electromagnetic properties - Abstract: A new type of CNTs/magnetite hybrid material was prepared via covalently bonded method in a simple solvothermal system using FeCl{sub 3} as iron source, ethylene glycol as the reducing agent, and 4-aminophenoxyphthalonitrile-grafted CNTs as templates. The magnetite nanoparticles, with the diameters of 70-80 nm, were self-assembled along the CNTs. The FTIR, UV-vis and DSC revealed that a stable covalent bond between nitriles group and iron ion promoted the oriented growth of magnetite nanoparticles along the CNTs, resulting in good dispersibility and solution storage stability. The magnetic properties measurements indicated that a higher saturated magnetization (70.7 emu g{sup -1}) existed in the CNTs/magnetite hybrid material, which further enhanced the electromagnetic properties. The magnetic loss was caused mainly by natural resonance, which is in good agreement with the Kittel equation results. The novel electromagnetic hybrid material is believed to have potential applications in the microwave absorbing performances.

Oriented growth of magnetite along the carbon nanotubes via covalently bonded method in a simple solvothermal system

International Nuclear Information System (INIS)

Zhan Yingqing; Zhao Rui; Meng Fanbing; Lei Yajie; Zhong Jiachun; Yang Xulin; Liu Xiaobo

2011-01-01

Highlights: → Novel CNTs/magnetite hybrid materials were prepared via covalently bonded method. → Stable interaction between nitriles and iron ion promoted the oriented growth of magnetite. → The hybrid material exhibited higher magnetism and electromagnetic properties - Abstract: A new type of CNTs/magnetite hybrid material was prepared via covalently bonded method in a simple solvothermal system using FeCl 3 as iron source, ethylene glycol as the reducing agent, and 4-aminophenoxyphthalonitrile-grafted CNTs as templates. The magnetite nanoparticles, with the diameters of 70-80 nm, were self-assembled along the CNTs. The FTIR, UV-vis and DSC revealed that a stable covalent bond between nitriles group and iron ion promoted the oriented growth of magnetite nanoparticles along the CNTs, resulting in good dispersibility and solution storage stability. The magnetic properties measurements indicated that a higher saturated magnetization (70.7 emu g -1 ) existed in the CNTs/magnetite hybrid material, which further enhanced the electromagnetic properties. The magnetic loss was caused mainly by natural resonance, which is in good agreement with the Kittel equation results. The novel electromagnetic hybrid material is believed to have potential applications in the microwave absorbing performances.

Raman Spectroscopy of Two-Dimensional Bi2TexSe3 − x Platelets Produced by Solvothermal Method

Directory of Open Access Journals (Sweden)

Jian Yuan

2015-08-01

Full Text Available In this paper, we report a facile solvothermal method to produce both binary and ternary compounds of bismuth chalcogenides in the form of Bi2TexSe3 − x. The crystal morphology in terms of geometry and thickness as well as the stoichiometric ratio can be well controlled, which offers the opportunities to systematically investigate the relationship between microstructure and phonon scattering by Raman spectroscopy. Raman spectra of four compounds, i.e., Bi2Se3, Bi2Se2Te, Bi2SeTe2 and Bi2Te3, were collected at four different excitation photon energies (2.54, 2.41, 1.96, and 1.58 eV. It is found that the vibrational modes are shifted to higher frequency with more Se incorporation towards the replacement of Te. The dependence of Raman vibrational modes on excitation photon energy was investigated. As the excitation photon energy increases, three Raman vibrational modes (A1g1, Eg2 and A1g2 of the as-produced compounds move to low frequency. Three Infrared-active (IR-active modes were observed in thin topological insulators (TIs crystals.

Resolution of Reflection Seismic Data Revisited

DEFF Research Database (Denmark)

Hansen, Thomas Mejer; Mosegaard, Klaus; Zunino, Andrea

The Rayleigh Principle states that the minimum separation between two reflectors that allows them to be visually separated is the separation where the wavelet maxima from the two superimposed reflections combine into one maximum. This happens around Δtres = λb/8, where λb is the predominant...... lower vertical resolution of reflection seismic data. In the following we will revisit think layer model and demonstrate that there is in practice no limit to the vertical resolution using the parameterization of Widess (1973), and that the vertical resolution is limited by the noise in the data...

Solvothermal method as a green chemistry solution for micro-encapsulation of phase change materials for high temperature thermal energy storage

Directory of Open Access Journals (Sweden)

Tudor Albert Ioan

2018-01-01

Full Text Available Thermal energy storage systems using phase change materials (PCMs as latent heat storage are one of the main challenges at European level in improving the performances and efficiency of concentrated solar power energy generation due to their high energy density. PCM with high working temperatures in the temperature range 300–500 °C are required for these purposes. However their use is still limited due to the problems raised by the corrosion of the majority of high temperature PCMs and lower thermal transfer properties. Micro-encapsulation was proposed as one method to overcome these problems. Different micro-encapsulation methods proposed in the literature are presented and discussed. An original process for the micro-encapsulation of potassium nitrate as PCM in inorganic zinc oxide shells based on a solvothermal method followed by spray drying to produce microcapsules with controlled phase composition and distribution is proposed and their transformation temperatures and enthalpies measured by differential scanning calorimetry are presented.

Solvothermal method as a green chemistry solution for micro-encapsulation of phase change materials for high temperature thermal energy storage

Science.gov (United States)

Tudor, Albert Ioan; Motoc, Adrian Mihail; Ciobota, Cristina Florentina; Ciobota, Dan. Nastase; Piticescu, Radu Robert; Romero-Sanchez, Maria Dolores

2018-05-01

Thermal energy storage systems using phase change materials (PCMs) as latent heat storage are one of the main challenges at European level in improving the performances and efficiency of concentrated solar power energy generation due to their high energy density. PCM with high working temperatures in the temperature range 300-500 °C are required for these purposes. However their use is still limited due to the problems raised by the corrosion of the majority of high temperature PCMs and lower thermal transfer properties. Micro-encapsulation was proposed as one method to overcome these problems. Different micro-encapsulation methods proposed in the literature are presented and discussed. An original process for the micro-encapsulation of potassium nitrate as PCM in inorganic zinc oxide shells based on a solvothermal method followed by spray drying to produce microcapsules with controlled phase composition and distribution is proposed and their transformation temperatures and enthalpies measured by differential scanning calorimetry are presented.

Sloan Digital Sky Survey Photometric Calibration Revisited

International Nuclear Information System (INIS)

Marriner, John

2012-01-01

The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

REVISITING A CLASSIC: THE PARKER–MOFFATT PROBLEM

International Nuclear Information System (INIS)

Pezzi, O.; Servidio, S.; Valentini, F.; Malara, F.; Veltri, P.; Parashar, T. N.; Yang, Y.; Matthaeus, W. H.; Vásconez, C. L.

2017-01-01

The interaction of two colliding Alfvén wave packets is described here by means of magnetohydrodynamics (MHD) and hybrid kinetic numerical simulations. The MHD evolution revisits the theoretical insights described by Moffatt, Parker, Kraichnan, Chandrasekhar, and Elsässer in which the oppositely propagating large-amplitude wave packets interact for a finite time, initiating turbulence. However, the extension to include compressive and kinetic effects, while maintaining the gross characteristics of the simpler classic formulation, also reveals intriguing features that go beyond the pure MHD treatment.

REVISITING A CLASSIC: THE PARKER–MOFFATT PROBLEM

Energy Technology Data Exchange (ETDEWEB)

Pezzi, O.; Servidio, S.; Valentini, F.; Malara, F.; Veltri, P. [Dipartimento di Fisica, Università della Calabria, 87036 Rende (CS) (Italy); Parashar, T. N.; Yang, Y.; Matthaeus, W. H. [Department of Physics and Astronomy, University of Delaware, DE 19716 (United States); Vásconez, C. L. [Departamento de Física, Escuela Politécnica Nacional, Quito (Ecuador)

2017-01-10

The interaction of two colliding Alfvén wave packets is described here by means of magnetohydrodynamics (MHD) and hybrid kinetic numerical simulations. The MHD evolution revisits the theoretical insights described by Moffatt, Parker, Kraichnan, Chandrasekhar, and Elsässer in which the oppositely propagating large-amplitude wave packets interact for a finite time, initiating turbulence. However, the extension to include compressive and kinetic effects, while maintaining the gross characteristics of the simpler classic formulation, also reveals intriguing features that go beyond the pure MHD treatment.

Sloan Digital Sky Survey Photometric Calibration Revisited

Energy Technology Data Exchange (ETDEWEB)

Marriner, John; /Fermilab

2012-06-29

The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

Effect of electrolytes nature and concentration on the morphology and structure of MoS{sub 2} nanomaterials prepared using one-pot solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Akram, H., E-mail: akramhanane@yahoo.fr [Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, Cantoblanco, 28049 Madrid (Spain); Laboratoire de Génie Chimique et Valorisation des Ressources, Faculté des Sciences et Techniques de Tanger, Université Abdelmalek Essâadi, B.P. 416 Tangier (Morocco); Mateos-Pedrero, C., E-mail: cmpedrero@yahoo.es [Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculdade de Engenharia da Universidade do Porto Rua Roberto Frias, s/n4200-465, Porto (Portugal); Gallegos-Suárez, E.; Guerrero-Ruíz, A. [Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, Cantoblanco, 28049 Madrid (Spain); Grupo de Diseño y Aplicación de Catalizadores Heterogéneos, Unidad Asociada UNED—ICP (CSIC), Madrid (Spain); Chafik, T. [Laboratoire de Génie Chimique et Valorisation des Ressources, Faculté des Sciences et Techniques de Tanger, Université Abdelmalek Essâadi, B.P. 416 Tangier (Morocco); Rodríguez-Ramos, I. [Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, Cantoblanco, 28049 Madrid (Spain); Grupo de Diseño y Aplicación de Catalizadores Heterogéneos, Unidad Asociada UNED—ICP (CSIC), Madrid (Spain)

2014-07-01

Different MoS{sub 2} nanostructures have been obtained following an innovative one-step solvothermal method by changing the concentration and type of the electrolyte while avoiding the use of surfactant. It was found that the chemical nature of the studied electrolyte ((NH{sub 4}){sub 2}CO{sub 3} or KCl) do not significantly affect the morphology and structure of the obtained MoS{sub 2} nanomaterials. Nevertheless, increasing the electrolyte concentration yields to a remarkable modification of the morphology of the resulting MoS{sub 2} from nanospheres to worm-shaped then finally to nanotubes. All the obtained nanomaterials were characterized by X-ray diffraction, (XRD), transmission electron microscopy (TEM, HRTEM), Fourier transformation infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS).

Revisiting deforestation in Africa (1990–2010): One more lost ...

African Journals Online (AJOL)

This spotlight revisits the dynamics and prognosis outlined in the late 1980's published in Déforestation en Afrique. This book on deforestation in Africa utilized available statistical data from the 1980's and was a pioneering self - styled attempt to provide a holistic viewpoint of the ongoing trends pertaining to deforestation in ...

Revisiting Individual Creativity Assessment: Triangulation in Subjective and Objective Assessment Methods

Science.gov (United States)

Park, Namgyoo K.; Chun, Monica Youngshin; Lee, Jinju

2016-01-01

Compared to the significant development of creativity studies, individual creativity research has not reached a meaningful consensus regarding the most valid and reliable method for assessing individual creativity. This study revisited 2 of the most popular methods for assessing individual creativity: subjective and objective methods. This study…

Logistics Innovation Process Revisited

DEFF Research Database (Denmark)

Gammelgaard, Britta; Su, Shong-Iee Ivan; Yang, Su-Lan

2011-01-01

Purpose – The purpose of this paper is to learn more about logistics innovation processes and their implications for the focal organization as well as the supply chain, especially suppliers. Design/methodology/approach – The empirical basis of the study is a longitudinal action research project...... that was triggered by the practical needs of new ways of handling material flows of a hospital. This approach made it possible to revisit theory on logistics innovation process. Findings – Apart from the tangible benefits reported to the case hospital, five findings can be extracted from this study: the logistics...... innovation process model may include not just customers but also suppliers; logistics innovation in buyer-supplier relations may serve as an alternative to outsourcing; logistics innovation processes are dynamic and may improve supplier partnerships; logistics innovations in the supply chain are as dependent...

Life quality index revisited

DEFF Research Database (Denmark)

Ditlevsen, Ove Dalager

2004-01-01

The derivation of the life quality index (LQI) is revisited for a revision. This revision takes into account the unpaid but necessary work time needed to stay alive in clean and healthy conditions to be fit for effective wealth producing work and to enjoyable free time. Dimension analysis...... at birth should not vary between countries. Finally the distributional assumptions are relaxed as compared to the assumptions made in an earlier work by the author. These assumptions concern the calculation of the life expectancy change due to the removal of an accident source. Moreover a simple public...... consistency problems with the standard power function expression of the LQI are pointed out. It is emphasized that the combination coefficient in the convex differential combination between the relative differential of the gross domestic product per capita and the relative differential of the expected life...

Klein's double discontinuity revisited

DEFF Research Database (Denmark)

Winsløw, Carl; Grønbæk, Niels

2014-01-01

Much effort and research has been invested into understanding and bridging the ‘gaps’ which many students experience in terms of contents and expectations as they begin university studies with a heavy component of mathematics, typically in the form of calculus courses. We have several studies...... of bridging measures, success rates and many other aspects of these “entrance transition” problems. In this paper, we consider the inverse transition, experienced by university students as they revisit core parts of high school mathematics (in particular, calculus) after completing the undergraduate...... mathematics courses which are mandatory to become a high school teacher of mathematics. To what extent does the “advanced” experience enable them to approach the high school calculus in a deeper and more autonomous way ? To what extent can “capstone” courses support such an approach ? How could it be hindered...

Rereading Albert B. Lord's The Singer of Tales . Revisiting the ...

African Journals Online (AJOL)

Access to a fresh set of video-recordings of Sesotho praise-poetry made in the year 2000 enabled the author to revisit his adaptation of Albert Lord's definition of the formula as a dynamic compositional device that the oral poet utilizes during delivery. The basic adaptation made in 1983 pertains to heroic praises (dithoko tsa ...

Re-Visit to the School Nurse and Adolescents' Medicine Use

Science.gov (United States)

Borup, Ina K.; Andersen, Anette; Holstein, Bjorn E.

2011-01-01

Objective: To examine if students who re-visit the school nurse use medicines differently than other students when exposed to aches and psychological problems. Methods: The study includes all 11-, 13- and 15-year-old students from a random sample of schools in Denmark, response rate 87 per cent, n = 5,205. The data collection followed the…

Magnetic and photocatalytic studies on Zn1-xMgxFe2O4 nanocolloids synthesized by solvothermal reflux method.

Science.gov (United States)

Manohar, A; Krishnamoorthi, C

2017-12-01

Biocompatible magnetic semiconductor Zn 1-x Mg x Fe 2 O 4 (x=0, 0.1, 0.3, 0.5 & 0.7) nanoparticles of around 10nm diameter were synthesized by solvothermal reflux method. The method produces well separated and narrow size distributed nanoparticles. Crystal structure, morphology, particles surface properties, surfactant quantity, colloidal stability, magnetic properties and photocatalytic properties of the synthesized nanoparticles were studied. Different characterizations confirmed that all compounds were single crystals and superparamagnetic at room temperature. Saturation mass magnetization (M s =57.5emu/g) enhances with substituent Mg 2+ concentration due to promotion of mixed spinel (normal and inverse) structure. Photocatalytic activity of all synthesized magnetic semiconductor nanoparticles were studied through methylene blue degradation. The degradation of 98% methylene blue was observed on 60 min irradiation of light. It is observed that photocatalytic activity slightly enhances with substituent Mg 2+ concentration. The synthesized biocompatible magnetic semiconductor nanoparticles can be utilized as photocatalysts and could also be recycled and separated by applying an external magnetic field. Copyright © 2017 Elsevier B.V. All rights reserved.

An analytic algorithm for global coverage of the revisiting orbit and its application to the CFOSAT satellite

Science.gov (United States)

Xu, Ming; Huang, Li

2014-08-01

This paper addresses a new analytic algorithm for global coverage of the revisiting orbit and its application to the mission revisiting the Earth within long periods of time, such as Chinese-French Oceanic Satellite (abbr., CFOSAT). In the first, it is presented that the traditional design methodology of the revisiting orbit for some imaging satellites only on the single (ascending or descending) pass, and the repeating orbit is employed to perform the global coverage within short periods of time. However, the selection of the repeating orbit is essentially to yield the suboptimum from the rare measure of rational numbers of passes per day, which will lose lots of available revisiting orbits. Thus, an innovative design scheme is proposed to check both rational and irrational passes per day to acquire the relationship between the coverage percentage and the altitude. To improve the traditional imaging only on the single pass, the proposed algorithm is mapping every pass into its ascending and descending nodes on the specified latitude circle, and then is accumulating the projected width on the circle by the field of view of the satellite. The ergodic geometry of coverage percentage produced from the algorithm is affecting the final scheme, such as the optimal one owning the largest percentage, and the balance one possessing the less gradient in its vicinity, and is guiding to heuristic design for the station-keeping control strategies. The application of CFOSAT validates the feasibility of the algorithm.

The Peter Effect Revisited: Reading Habits and Attitudes of College Students

Science.gov (United States)

Applegate, Anthony J.; Applegate, Mary DeKonty; Mercantini, Martha A.; McGeehan, Catherine M.; Cobb, Jeanne B.; DeBoy, Joanne R.; Modla, Virginia B.; Lewinski, Kimberly E.

2014-01-01

Certainly a primary goal of literacy education is the creation of avid, enthusiastic, and highly motivated readers. However, in this article revisiting the Peter Effect (Applegate & Applegate, 2004), researchers surveyed more than 1,000 college sophomores and found strikingly low levels of enthusiasm for reading. Only 46.6% of surveyed…

A general solution-chemistry route to the synthesis LiMPO4 (M=Mn, Fe, and Co) nanocrystals with [010] orientation for lithium ion batteries

International Nuclear Information System (INIS)

Su Jing; Wei Bingqing; Rong Jiepeng; Yin Wenyan; Ye Zhixia; Tian Xianqing; Ren Ling; Cao Minhua; Hu Changwen

2011-01-01

A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures (LiMnPO 4 , LiFePO 4 , and LiCoPO 4 ), employing ethanol as the solvent, LiI as the Li source, metal salts as the M sources, H 3 PO 4 as the phosphorus source, and poly(vinyl pyrrolidone) (PVP) as the carbon source and template. This route features low cost, environmental benign, and one-step process for the cathode material production of Li-ion batteries without any complicated experimental setups and sophisticated operations. The as-synthesized LiMPO 4 microstructures exhibit unique, well-shaped and favorable structures, which are self-assembled from microplates or microrods. The b axis is the preferred crystal growth orientation of the products, resulting in a shorter lithium ion diffusion path. The LiFePO 4 microstructures show an excellent cycling stability without capacity fading up to 50 cycles when they are used as a cathode material in lithium-ion batteries. - Graphical abstract: A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures under solvothermal conditions in the presence of PVP. Highlights: → A general and efficient solvothermal strategy has been developed for the preparation of LiMPO 4 microstructures. → This route features low cost, environmental benign, and one-step process. → The LiMPO 4 microstructures exhibit unique, well-shaped, and favorable structures. → The LiFePO 4 microstructures show an excellent cycling stability up to 50 cycles as a cathode material of lithium-ion batteries.

Ambulatory thyroidectomy: A multistate study of revisits and complications

OpenAIRE

Orosco, RK; Lin, HW; Bhattacharyya, N

2015-01-01

© 2015 American Academy of Otolaryngology - Head and Neck Surgery Foundation. Objective. Determine rates and reasons for revisits after ambulatory adult thyroidectomy. Study Design. Cross-sectional analysis of multistate ambulatory surgery and hospital databases. Setting. Ambulatory surgery data from the State Ambulatory Surgery Databases of California, Florida, Iowa, and New York for calendar years 2010 and 2011. Subjects and Methods. Ambulatory thyroidectomy cases were linked to state ambul...

Taï chimpanzees anticipate revisiting high-valued fruit trees from further distances.

Science.gov (United States)

Ban, Simone D; Boesch, Christophe; Janmaat, Karline R L

2014-11-01

The use of spatio-temporal memory has been argued to increase food-finding efficiency in rainforest primates. However, the exact content of this memory is poorly known to date. This study investigated what specific information from previous feeding visits chimpanzees (Pan troglodytes verus), in Taï National Park, Côte d'Ivoire, take into account when they revisit the same feeding trees. By following five adult females for many consecutive days, we tested from what distance the females directed their travels towards previously visited feeding trees and how previous feeding experiences and fruit tree properties influenced this distance. To exclude the influence of sensory cues, the females' approach distance was measured from their last significant change in travel direction until the moment they entered the tree's maximum detection field. We found that chimpanzees travelled longer distances to trees at which they had previously made food grunts and had rejected fewer fruits compared to other trees. In addition, the results suggest that the chimpanzees were able to anticipate the amount of fruit that they would find in the trees. Overall, our findings are consistent with the hypothesis that chimpanzees act upon a retrieved memory of their last feeding experiences long before they revisit feeding trees, which would indicate a daily use of long-term prospective memory. Further, the results are consistent with the possibility that positive emotional experiences help to trigger prospective memory retrieval in forest areas that are further away and have fewer cues associated with revisited feeding trees.

Pt nanoparticles supported over Ce-Ti-O: the solvothermal and photochemical approaches for the preparation of catalytic materials

International Nuclear Information System (INIS)

Silva, Adrian M. T.; Machado, Bruno F.; Gomes, Helder T.; Figueiredo, Jose L.; Drazic, Goran; Faria, Joaquim L.

2010-01-01

Ce-Ti-O supports with different Ce/Ti molar ratios were synthesized by the solvothermal method using hexadecyltrimethylammonium bromide. Pt nanoparticles were then supported by photochemical deposition. The shape, size, and structure of these materials were analyzed by high-resolution transmission electron microscopy. The single CeO 2 support was also prepared, consisting of agglomerated cubic particles ranging from ∼3 to 8 nm. When titania was combined with ceria, a nanostructured architecture was produced, evidencing the strong influence of Ti in the support structure. Photodeposition of Pt nanoparticles is more efficient on Ce-Ti-O supports than in pristine CeO 2 . Crystalline Pt nanoparticles (mainly of ∼2 to 4 nm) were detected. The catalytic properties of the materials were tested in the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. It was observed that Pt supported on Ce-Ti-O is more active and selective than Pt on CeO 2 or TiO 2 separately. The catalyst with 40 mol% Ce leads to total conversion of cinnamaldehyde in a few minutes; however, higher selectivity toward the desired product (cinnamyl alcohol) was obtained with higher amounts of Ce (50 mol%).

High precision mass measurements in Ψ and Υ families revisited

International Nuclear Information System (INIS)

Artamonov, A.S.; Baru, S.E.; Blinov, A.E.

2000-01-01

High precision mass measurements in Ψ and Υ families performed in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited. The corrections for the new value of the electron mass are presented. The effect of the updated radiative corrections has been calculated for the J/Ψ(1S) and Ψ(2S) mass measurements [ru

Rapid adsorption properties of flower-like BiOI nanoplates synthesized via a simple EG-assisted solvothermal process

Energy Technology Data Exchange (ETDEWEB)

Zhang, Bin; Ji, Guangbin, E-mail: gbji@nuaa.edu.cn [Nanjing University of Aeronautics and Astronautics, College of Materials Science and Technology (China); Gondal, M. A. [King Fahd University of Petroleum and Minerals, Physics Department (Saudi Arabia); Liu, Yousong; Zhang, Xingmiao; Chang, Xiaofeng; Li, Nianwu [Nanjing University of Aeronautics and Astronautics, College of Materials Science and Technology (China)

2013-07-15

Uniform well-crystallized flower-like BiOI nanoplates contained 3.7 nm mesopores, which may be attributed to the internanosheet spaces of BiOI with maximum pore diameters of about 30 nm, were successfully synthesized via a simple ethylene glycol-assisted solvothermal method. The as-prepared porous BiOI nanoplates exhibited excellent adsorption ability, and the saturated extent of adsorption of BiOI over an RhB solution was as high as 197 mg/g, which is much higher than those for BiOCl and BiOBr prepared via the same method and with a similar surface area. The probable adsorption mechanism could have originated from the interaction between the I atom in BiOI and a proton in RhB at different pH values and temperatures. With visible light irradiation ({lambda} > 420 nm), 80 % of the RhB was degraded in 4 h, while BiOI still demonstrated reasonably outstanding photocatalytic ability under green light ({lambda} = 550 {+-} 15 nm) because of its low-energy gap (1.72 eV). The degradation test for BiOI under irradiation at {lambda} = 550 {+-} 15 nm is an excellent achievement for field applications because the catalyst can be applied in solar irradiation to remove organic pollutants, which may be of great value BiOI complex.

Commentary on "Distributed Revisiting: An Analytic for Retention of Coherent Science Learning"

Science.gov (United States)

Hewitt, Jim

2015-01-01

The article, "Distributed Revisiting: An Analytic for Retention of Coherent Science Learning" is an interesting study that operates at the intersection of learning theory and learning analytics. The authors observe that the relationship between learning theory and research in the learning analytics field is constrained by several…

Double digest revisited : Complexity and Approximability in the Presence of Noisy Data

NARCIS (Netherlands)

Cieliebak, Mark; Eidenbenz, Stephan; Woeginger, Gerhard; Warnow, Tandy; Zhu, Binhai

2003-01-01

We revisit the Double Digest problem, which occurs in sequencing of large DNA strings and consists of reconstructing the relative positions of cut sites from two different enzymes: we first show that Double Digest is strongly NP-complete, improving upon previous results that only showed weak

First-principles lattice-gas Hamiltonian revisited: O-Pd(100)

OpenAIRE

Kappus, Wolfgang

2016-01-01

The methodology of deriving an adatom lattice-gas Hamiltonian (LGH) from first principles (FP) calculations is revisited. Such LGH cluster expansions compute a large set of lateral pair-, trio-, quarto interactions by solving a set of linear equations modelling regular adatom configurations and their FP energies. The basic assumption of truncating interaction terms beyond fifth nearest neighbors does not hold when adatoms show longer range interactions, e.g. substrate mediated elastic interac...

Advanced Change Theory Revisited: An Article Critique

Directory of Open Access Journals (Sweden)

R. Scott Pochron

2008-12-01

Full Text Available The complexity of life in 21st century society requires new models for leading and managing change. With that in mind, this paper revisits the model for Advanced Change Theory (ACT as presented by Quinn, Spreitzer, and Brown in their article, “Changing Others Through Changing Ourselves: The Transformation of Human Systems” (2000. The authors present ACT as a potential model for facilitating change in complex organizations. This paper presents a critique of the article and summarizes opportunities for further exploring the model in the light of current trends in developmental and integral theory.

Revisiting fifth forces in the Galileon model

Energy Technology Data Exchange (ETDEWEB)

Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Seery, David [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy

2010-05-15

A Galileon field is one which obeys a spacetime generalization of the non- relativistic Galilean invariance. Such a field may possess non-canonical kinetic terms, but ghost-free theories with a well-defined Cauchy problem exist, constructed using a finite number of relevant operators. The interactions of this scalar with matter are hidden by the Vainshtein effect, causing the Galileon to become weakly coupled near heavy sources. We revisit estimates of the fifth force mediated by a Galileon field, and show that the parameters of the model are less constrained by experiment than previously supposed. (orig.)

Large J expansion in ABJM theory revisited.

Science.gov (United States)

Dimov, H; Mladenov, S; Rashkov, R C

Recently there has been progress in the computation of the anomalous dimensions of gauge theory operators at strong coupling by making use of the AdS/CFT correspondence. On the string theory side they are given by dispersion relations in the semiclassical regime. We revisit the problem of a large-charge expansion of the dispersion relations for simple semiclassical strings in an [Formula: see text] background. We present the calculation of the corresponding anomalous dimensions of the gauge theory operators to an arbitrary order using three different methods. Although the results of the three methods look different, power series expansions show their consistency.

The power reinforcement framework revisited

DEFF Research Database (Denmark)

Nielsen, Jeppe; Andersen, Kim Normann; Danziger, James N.

2016-01-01

Whereas digital technologies are often depicted as being capable of disrupting long-standing power structures and facilitating new governance mechanisms, the power reinforcement framework suggests that information and communications technologies tend to strengthen existing power arrangements within...... public organizations. This article revisits the 30-yearold power reinforcement framework by means of an empirical analysis on the use of mobile technology in a large-scale programme in Danish public sector home care. It explores whether and to what extent administrative management has controlled decision......-making and gained most benefits from mobile technology use, relative to the effects of the technology on the street-level workers who deliver services. Current mobile technology-in-use might be less likely to be power reinforcing because it is far more decentralized and individualized than the mainly expert...

A comparative study of magnetic properties of MnFe2O4 nanoparticles prepared by thermal decomposition and solvothermal methods

Directory of Open Access Journals (Sweden)

B Aslibeiki

2017-09-01

Full Text Available A comparative study of magnetic properties of MnFe2O4 ferrite nanoparticles prepared by two different methods has been reported. The first sample (S1 was synthesized by thermal decomposition of metal nitrates. And the second sample (S2 was prepared by solvothermal method using Tri-ethylene glycol (TEG. Magnetic hysteresis loops at 300 and 5 K; magnetization and AC susceptibility measurements versus temperature confirmed the effective role of TEG on the magnetic properties of nanoparticles. The results showed that, at 300 K the saturation magnetization (MS of S2 sample is 46% greater than that of S1 sample. At 5 K, the difference in MS of the samples raised to 60%. AC susceptibility measurements at different frequencies and also magnetization versus temperature under field cooling and zero field cooling processes revealed that, the TEG molecules influence the surface spins order of S2 sample. The sample S1 showed strongly interacting superspin glass state, while the sample S2 consists of weakly interacting superparamagnetic nanoparticles.

Solvothermal coating LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 microspheres with nanoscale Li_2TiO_3 shell for long lifespan Li-ion battery cathode materials

International Nuclear Information System (INIS)

Wu, Naiteng; Wu, Hao; Liu, Heng; Zhang, Yun

2016-01-01

LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 (NCA) microspheres covered by a nanoscale Li_2TiO_3-based shell were synthesized by a facile strategy based on a solvothermal pre-coating treatment combined with a post-sintering lithiation process. The morphology, structure and composition of the Li_2TiO_3-coated NCA samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning scanning electron microscope (SEM) with an energy-dispersive X-ray spectroscope (EDS), and transmission electron microscopy (TEM). Owing to the complete, uniform and nanoscale Li_2TiO_3 coating shell, the resultant surface-modified NCA microspheres used as Li-ion battery cathode materials manifest remarkably enhanced cycling performances, attaining 94% and 84% capacity retention after 200 and 400 cycles at 0.5 C, respectively, which is much better than the pristine NCA counterpart (60% retention, 200 cycles). More impressively, the surface-modified NCA also shows an intriguing storage stability. After being stored at 30 °C for 50 days, the coated NCA-based cells are subjected to be cycled both at room and elevated temperatures, in which the aged cells can still remain 84% capacity retention after 200 cycles at 25 °C and 77% capacity retention after 200 cycles at 55 °C, respectively. All these results demonstrate that the Li_2TiO_3-coated LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 microsphere is a promising cathode material for Li-ion batteries with long lifespan. - Graphical abstract: Nanoscale Li_2TiO_3-based shell encapsulated LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 (NCA) microspheres are fabricated through a solvothermal pre-coating treatment combined with post-lithiation process. The surface-coated NCA as cathode materials shows a remarkably enhanced cycling performance and storage stability for long lifespan Li-ion batteries. - Highlights: • Li_2TiO_3 is used as coating materials for layer structured LiNi_0_._8Co_0_._1_5Al_0_._0_5O_2 cathode. • Solvothermal coating

Influence of Reduced Graphene Oxide on Effective Absorption Bandwidth Shift of Hybrid Absorbers.

Directory of Open Access Journals (Sweden)

Shahid Ameer

Full Text Available The magnetic nanoparticle composite NiFe2O4 has traditionally been studied for high-frequency microwave absorption with marginal performance towards low-frequency radar bands (particularly L and S bands. Here, NiFe2O4 nanoparticles and nanohybrids using large-diameter graphene oxide (GO sheets are prepared via solvothermal synthesis for low-frequency wide bandwidth shielding (L and S radar bands. The synthesized materials were characterized using XRD, SEM, FTIR and microwave magneto dielectric spectroscopy. The dimension of these solvothermally synthesized pristine particles and hybrids lies within 30-58 nm. Microwave magneto-dielectric spectroscopy was performed in the low-frequency region in the 1 MHz-3 GHz spectrum. The as-synthesized pristine nanoparticles and hybrids were found to be highly absorbing for microwaves throughout the L and S radar bands ( 4 GHz with limited selective bandwidth.

Revisit boundary conditions for the self-adjoint angular flux formulation

Energy Technology Data Exchange (ETDEWEB)

Wang, Yaqi [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gleicher, Frederick N. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-03-01

We revisit the boundary conditions for SAAF. We derived the equivalent parity variational form ready for coding up. The more rigorous approach of evaluating odd parity should be solving the odd parity equation coupled with the even parity. We proposed a symmetric reflecting boundary condition although neither positive definiteness nor even-odd decoupling is achieved. A simple numerical test verifies the validity of these boundary conditions.

Place attachment and social legitimacy: Revisiting the sustainable entrepreneurship journey

OpenAIRE

Kibler, E; Fink, M; Lang, R; Munoz, PA

2015-01-01

This paper revisits the sustainable entrepreneurship journey by introducing a ‘place- based’ sustainable venture path model. We suggest that distinguishing between emo- tional (‘caring about the place’) and instrumental (‘using the place’) place attachment of sustainable entrepreneurs deepens our understanding of how place-based challenges of sustainable venture legitimacy are managed over time. We conclude with avenues for future sustainable entrepreneurship research.

Teacher Communication Concerns Revisited: Calling into Question the Gnawing Pull towards Equilibrium

Science.gov (United States)

Dannels, Deanna P.

2015-01-01

This study revisits the long-standing teacher communication concerns framework originating over three decades ago. Analysis of 10 years of contemporary GTA teacher communication concerns reveals a typology of 10 concerns, which taken together construct teaching as a process of negotiating relationships, managing identities, and focusing attention.…

Revisiting Learning in Higher Education--Framing Notions Redefined through an Ecological Perspective

Science.gov (United States)

Damsa, Crina; Jornet, Alfredo

2016-01-01

This article employs an ecological perspective as a means of revisiting the notion of learning, with a particular focus on learning in higher education. Learning is reconceptualised as a process entailing mutually constitutive, epistemic, social and affective relations in which knowledge, identity and agency become collective achievements of whole…

A pyrazolyl-based thiolato single-source precursor for the selective synthesis of isotropic copper-deficient copper(I) sulfide nanocrystals: synthesis, optical and photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Mondal, Gopinath; Santra, Ananyakumari; Bera, Pradip; Acharjya, Moumita [Vidyasagar University, Post Graduate Department of Chemistry, Panskura Banamali College (India); Jana, Sumanta [Indian Institute of Engineering Science and Technology (IIEST), Department of Chemistry (India); Chattopadhyay, Dipankar [University of Calcutta, Department of Polymer Science and Technology (India); Mondal, Anup [Indian Institute of Engineering Science and Technology (IIEST), Department of Chemistry (India); Seok, Sang Il [Korea Research Institute of Chemical Technology, KRICT-EPFL Global Research Laboratory, Division of Advanced Materials (Korea, Republic of); Bera, Pulakesh, E-mail: pbera.pbc.chem@gmail.com [Vidyasagar University, Post Graduate Department of Chemistry, Panskura Banamali College (India)

2016-10-15

Hexagonal copper-deficient copper(I) sulfide (Cu{sub 2-x}S, x = 0.03, 0.2) nanocrystals (NCs) are synthesized from a newly prepared single-source precursor (SP), [Cu(bdpa){sub 2}][CuCl{sub 2}], where bdpa is benzyl 3,5-dimethyl-pyrazole-1-carbodithioate. The SP is crystallized with space group Pī and possesses a distorted tetrahedron structure with a CuN{sub 2}S{sub 2} chromophore where the central copper is in +1 oxidation state. Distortion in copper(I) structure and the low decomposition temperature of SP make it favorable for the low-temperature solvent-assisted selective growth of high-copper content sulfides. The nucleation and growth of Cu{sub 2-x}S (x = 0.03, 0.2) are effectively controlled by the SP and the solvent in the solvothermal decomposition process. During decomposition, fragment benzyl thiol (PhCH{sub 2}SH) from SP effectively passivates the nucleus leading to spherical nanocrystals. Further, solvent plays an important role in the selective thermochemical transformation of Cu{sup I}-complex to Cu{sub 2-x}S (x = 0.03, 0.2) NCs. The chelating binders (solvent) like ethylene diamine (EN) and ethylene glycol (EG) prefer to form spherical Cu{sub 1.97}S nanoparticles (djurleite), whereas nonchelating hydrazine hydrate (HH) shows the tendency to furnish hexagonal platelets of copper-deficient Cu{sub 1.8}S. The optical band gap values (2.25–2.50 eV) show quantum confinement effect in the structure. The synthesized NCs display excellent catalytic activity (~87 %) toward photodegradation of organic dyes like Congo Red (CR) and Methylene Blue (MB).Graphical abstractA pyrazolyl-based thiolato single-source precursor for the selective synthesis of isotropic copper-deficient copper(I) sulfide nanocrystals: Synthesis, optical and photocatalytic activity.Gopinath Mondal, Ananyakumari Santra, Pradip Bera, Moumita Acharjya, Sumanta Jana, Dipankar Chattopadhyay, Anup Mondal, Sang Il Seok, Pulakesh Bera.

Lorentz violation naturalness revisited

Energy Technology Data Exchange (ETDEWEB)

Belenchia, Alessio; Gambassi, Andrea; Liberati, Stefano [SISSA - International School for Advanced Studies, via Bonomea 265, 34136 Trieste (Italy); INFN, Sezione di Trieste, via Valerio 2, 34127 Trieste (Italy)

2016-06-08

We revisit here the naturalness problem of Lorentz invariance violations on a simple toy model of a scalar field coupled to a fermion field via a Yukawa interaction. We first review some well-known results concerning the low-energy percolation of Lorentz violation from high energies, presenting some details of the analysis not explicitly discussed in the literature and discussing some previously unnoticed subtleties. We then show how a separation between the scale of validity of the effective field theory and that one of Lorentz invariance violations can hinder this low-energy percolation. While such protection mechanism was previously considered in the literature, we provide here a simple illustration of how it works and of its general features. Finally, we consider a case in which dissipation is present, showing that the dissipative behaviour does not percolate generically to lower mass dimension operators albeit dispersion does. Moreover, we show that a scale separation can protect from unsuppressed low-energy percolation also in this case.

Rapid and facile preparation of zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

Energy Technology Data Exchange (ETDEWEB)

Anchieta, Chayene G.; Severo, Eric C.; Rigo, Caroline; Mazutti, Marcio A. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Kuhn, Raquel C., E-mail: raquelckuhn@yahoo.com.br [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Muller, Edson I.; Flores, Erico M.M. [Department of Chemistry, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Moreira, Regina F.P.M. [Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, 88040-970, Florianópolis (Brazil); Foletto, Edson L. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil)

2015-06-15

In this work zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe{sub 2}O{sub 4} oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe{sub 2}O{sub 4} oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe{sub 2}O{sub 4} particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe{sub 2}O{sub 4} was synthesized by microwave-solvothermal method. • ZnFe{sub 2}O{sub 4} was prepared by different microwave heating times and powers. • ZnFe{sub 2}O{sub 4} was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe{sub 2}O{sub 4} was highly efficient to degrade textile dye under visible light.

Synthesis of ZnO particles using water molecules generated in esterification reaction

Science.gov (United States)

Šarić, Ankica; Gotić, Marijan; Štefanić, Goran; Dražić, Goran

2017-07-01

Zinc oxide particles were synthesized without the addition of water by autoclaving (anhydrous) zinc acetate/alcohol and zinc acetate/acetic acid/alcohol solutions at 160 °C. The solvothermal synthesis was performed in ethanol or octanol. The structural, optical and morphological characteristics of ZnO particles were investigated by X-ray diffraction (XRD), UV-Vis spectroscopy, FE-SEM and TEM/STEM microscopy. 13C NMR spectroscopy revealed the presence of ester (ethyl- or octyl-acetate) in the supernatants which directly indicate the reaction mechanism. The formation of ester in this esterification reaction generated water molecule in situ, which hydrolyzed anhydrous zinc acetate and initiated nucleation and formation of ZnO. It was found that the size and shape of ZnO particles depend on the type of alcohol used as a solvent and on the presence of acetic acid in solution. The presence of ethanol in the ;pure; system without acetic acid favoured the formation of fine and uniform spherical ZnO nanoparticles (∼20 nm). With the addition of small amount of acetic acid the size of these small nanoparticles increased significantly up to a few hundred nanometers. The addition of small amount of acetic acid in the presence of octanol caused even more radical changes in the shape of ZnO particles, favouring the growth of huge rod-like particles (∼3 μm).

Quark matter revisited with non-extensive MIT bag model

Energy Technology Data Exchange (ETDEWEB)

Cardoso, Pedro H.G.; Nunes da Silva, Tiago; Menezes, Debora P. [Universidade Federal de Santa Catarina, Departamento de Fisica, CFM, Florianopolis (Brazil); Deppman, Airton [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

2017-10-15

In this work we revisit the MIT bag model to describe quark matter within both the usual Fermi-Dirac and the Tsallis statistics. We verify the effects of the non-additivity of the latter by analysing two different pictures: the first order phase transition of the QCD phase diagram and stellar matter properties. While the QCD phase diagram is visually affected by the Tsallis statistics, the resulting effects on quark star macroscopic properties are barely noticed. (orig.)

My First CMC Article Revisited: A Window on Spanish L2 Interlanguage

Science.gov (United States)

Blake, Robert

2016-01-01

The computer-assisted language learning (CALL) field seems to change overnight with new technological affordances. Blake revisits his 2000 "LLT" article on computer-mediation communication (CMC) in order to reflect on how the field has examined this topic over the past decade or so. While the Interaction Hypothesis continues to guide…

Risk prediction of emergency department revisit 30 days post discharge: a prospective study.

Directory of Open Access Journals (Sweden)

Shiying Hao

Full Text Available Among patients who are discharged from the Emergency Department (ED, about 3% return within 30 days. Revisits can be related to the nature of the disease, medical errors, and/or inadequate diagnoses and treatment during their initial ED visit. Identification of high-risk patient population can help device new strategies for improved ED care with reduced ED utilization.A decision tree based model with discriminant Electronic Medical Record (EMR features was developed and validated, estimating patient ED 30 day revisit risk. A retrospective cohort of 293,461 ED encounters from HealthInfoNet (HIN, Maine's Health Information Exchange (HIE, between January 1, 2012 and December 31, 2012, was assembled with the associated patients' demographic information and one-year clinical histories before the discharge date as the inputs. To validate, a prospective cohort of 193,886 encounters between January 1, 2013 and June 30, 2013 was constructed. The c-statistics for the retrospective and prospective predictions were 0.710 and 0.704 respectively. Clinical resource utilization, including ED use, was analyzed as a function of the ED risk score. Cluster analysis of high-risk patients identified discrete sub-populations with distinctive demographic, clinical and resource utilization patterns.Our ED 30-day revisit model was prospectively validated on the Maine State HIN secure statewide data system. Future integration of our ED predictive analytics into the ED care work flow may lead to increased opportunities for targeted care intervention to reduce ED resource burden and overall healthcare expense, and improve outcomes.

Influence of reaction time on the structural, optical and electrical performance of copper antimony sulfide nanoparticles using solvothermal method

Science.gov (United States)

John, Bincy; Genifer Silvena, G.; Leo Rajesh, A.

2018-05-01

The less toxic and cost effective ternary Cu-Sb-S nanoparticles and thin films were synthesized and deposited using solvothermal and drop casting method. The reactions were carried out at different timings as 12-48 h, in steps of 12 h using ethylene glycol as solvent and polyvinylpyrrolidone (PVP) as surfactant. Systematic analysis revealed that due to the influence of different reaction time, significant and unique changes were occurring on the crystal structure, optical and electrical properties of the material. The synthesized nanopowders and deposited films were characterized by means of X-ray diffraction, Raman analysis, field emission scanning electron microscope with energy dispersive spectrometer, UV-Vis-NIR diffuse reflectance spectroscopy and hall measurement. XRD results showed that as the time increases crystallinity improves and phase transformation from chalcostibite to tetrahedrite occurs. The Optical performance revealed that the bandgap of nanoparticles were in the range of 1.21-1.49 eV. Hall measurements showed that the deposited Cu12Sb4S13 and CuSbS2 films exhibited p-type conductivity with carrier concentration ranging from 1016-1019 cm-3, indicating a promising p-type absorber material for photovoltaic applications.

The Best and the Rest: Revisiting the Norm of Normality of Individual Performance

Science.gov (United States)

O'Boyle, Ernest, Jr.; Aguinis, Herman

2012-01-01

We revisit a long-held assumption in human resource management, organizational behavior, and industrial and organizational psychology that individual performance follows a Gaussian (normal) distribution. We conducted 5 studies involving 198 samples including 633,263 researchers, entertainers, politicians, and amateur and professional athletes.…

The Levy sections theorem revisited

International Nuclear Information System (INIS)

Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Silva, Sergio Da

2007-01-01

This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets

The Levy sections theorem revisited

Science.gov (United States)

Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Da Silva, Sergio

2007-06-01

This paper revisits the Levy sections theorem. We extend the scope of the theorem to time series and apply it to historical daily returns of selected dollar exchange rates. The elevated kurtosis usually observed in such series is then explained by their volatility patterns. And the duration of exchange rate pegs explains the extra elevated kurtosis in the exchange rates of emerging markets. In the end, our extension of the theorem provides an approach that is simpler than the more common explicit modelling of fat tails and dependence. Our main purpose is to build up a technique based on the sections that allows one to artificially remove the fat tails and dependence present in a data set. By analysing data through the lenses of the Levy sections theorem one can find common patterns in otherwise very different data sets.

"Rapid Revisit" Measurements of Sea Surface Winds Using CYGNSS

Science.gov (United States)

Park, J.; Johnson, J. T.

2017-12-01

The Cyclone Global Navigation Satellite System (CYGNSS) is a space-borne GNSS-R (GNSS-Reflectometry) mission that launched December 15, 2016 for ocean surface wind speed measurements. CYGNSS includes 8 small satellites in the same LEO orbit, so that the mission provides wind speed products having unprecedented coverage both in time and space to study multi-temporal behaviors of oceanic winds. The nature of CYGNSS coverage results in some locations on Earth experiencing multiple wind speed measurements within a short period of time (a "clump" of observations in time resulting in a "rapid revisit" series of measurements). Such observations could seemingly provide indications of regions experiencing rapid changes in wind speeds, and therefore be of scientific utility. Temporally "clumped" properties of CYGNSS measurements are investigated using early CYGNSS L1/L2 measurements, and the results show that clump durations and spacing vary with latitude. For example, the duration of a clump can extend as long as a few hours at higher latitudes, with gaps between clumps ranging from 6 to as high as 12 hours depending on latitude. Examples are provided to indicate the potential of changes within a clump to produce a "rapid revisit" product for detecting convective activity. Also, we investigate detector design for identifying convective activities. Results from analyses using recent CYGNSS L2 winds will be provided in the presentation.

Gap state related blue light emitting boron-carbon core shell structures

International Nuclear Information System (INIS)

Singh, Paviter; Kaur, Manpreet; Singh, Bikramjeet; Kaur, Gurpreet; Singh, Kulwinder; Kumar, Akshay; Kumar, Manjeet; Bala, Rajni; Thakur, Anup

2016-01-01

Boron-carbon core shell structures have been synthesized by solvo-thermal synthesis route. The synthesized material is highly pure. X-ray diffraction analysis confirms the reduction of reactants in to boron and carbon. Scanning Electron Microscopy (SEM) analysis showed that the shell is uniform with average thickness of 340 nm. Photo luminescence studies showed that the material is blue light emitting with CIE color coordinates: x=0.16085, y=0.07554.

Re-visiting RHIC snakes: OPERA fields, n₀ dance

Energy Technology Data Exchange (ETDEWEB)

Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gupta, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2017-09-22

In this Tech. Note RHIC snakes and stable spin direction $\\vector{n}$₀(s) are re-visited, based on OPERA-computed field maps of the former. The numerical simulations so undertaken provide various outcomes regarding RHIC optics and spin dynamics, in relation with orbital and focusing effects resulting from the use of this realistic 3-D representation of the snakes.

Solvothermal syntheses of Bi and Zn co-doped TiO{sub 2} with enhanced electron-hole separation and efficient photodegradation of gaseous toluene under visible-light

Energy Technology Data Exchange (ETDEWEB)

Li, Juan-Juan [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Cai, Song-Cai [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Xu, Zhen [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Chen, Xi [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Chen, Jin [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Jia, Hong-Peng, E-mail: hpjia@iue.ac.cn [Center for Excellence in Regional Atmospheric Environment, and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Chen, Jing, E-mail: jing.chen@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)

2017-03-05

Highlights: • Bi-Zn co-doped TiO{sub 2} catalysts were prepared by solvothermal route. • The incorporation of Bi doping into the TiO{sub 2} generates intermediate energy levels. • Bi and Zn doping showed the enhanced absorption in visible-light region. • Zn dopant acts as a mediator of interfacial charge transfer. • TiBi{sub 1.9%}Zn{sub 1%}O{sub 2} exhibited high photocatalytic degradation for toluene. - Abstract: This study investigated the effects of Bi doped and Bi-Zn co-doped TiO{sub 2} on photodegradation of gaseous toluene. The doped TiO{sub 2} with various concentration of metal was prepared using the solvothermal route and characterized by SEM, XRD, Raman, BET, DRS, XPS, PL and EPR. Their photocatalytic activities under visible-light irradiation were drastically influenced by the dopant content. The results showed that moderate metal doping levels were obviously beneficial for the toluene degradation, while high doping levels suppressed the photocatalytic activity. The photocatalytic degradation of toluene over TiBi{sub 1.9%}O{sub 2} and TiBi{sub 1.9%}Zn{sub 1%}O{sub 2} can reach to 51% and 93%, respectively, which are much higher than 25% of TiO{sub 2}. Bi doping into TiO{sub 2} lattice generates new intermediate energy level of Bi below the CB edge of TiO{sub 2}. The electron excitation from the VB to Bi orbitals results in the decreased band gap, extended absorption of visible-light and thus enhances its photocatalytic efficiency. Zn doping not only further enhances the absorption in this visible-light region, but also Zn dopant exists as the form of ZnO crystallites located on the interfaces of TiO{sub 2} agglomerates and acts as a mediator of interfacial charge transfer to suppress the electron-hole recombination. These synergistic effects are responsible for the enhanced photocatalytic performance.

Serotype-specific mortality from invasive Streptococcus pneumoniae disease revisited

DEFF Research Database (Denmark)

Martens, Pernille; Worm, Signe Westring; Lundgren, Bettina

2004-01-01

Serotype-specific mortality from invasive Streptococcus pneumoniae disease revisited.Martens P, Worm SW, Lundgren B, Konradsen HB, Benfield T. Department of Infectious Diseases 144, Hvidovre University Hospital, DK-2650 Hvidovre, Denmark. pernillemartens@yahoo.com BACKGROUND: Invasive infection...... with Streptococcus pneumoniae (pneumococci) causes significant morbidity and mortality. Case series and experimental data have shown that the capsular serotype is involved in the pathogenesis and a determinant of disease outcome. METHODS: Retrospective review of 464 cases of invasive disease among adults diagnosed...

The Assassination of John F. Kennedy: Revisiting the Medical Data

OpenAIRE

Rohrich, Rod J.; Nagarkar, Purushottam; Stokes, Mike; Weinstein, Aaron; Mantik, David W.; Jensen, J. Arthur

2014-01-01

Thank you for publishing "The Assassination of John F. Kennedy: Revisiting the Medical Data."1 The central conclusion of this study is that the assassination remains controversial and that some of the controversy must be attributable to the "reporting and handling of the medical evidence." With the greatest respect for you and Dr. Robert McClelland, let me argue that your text and on-line interviews perpetuate the central misunderstanding of the assassination and there...

Dispute Resolution and Technology: Revisiting the Justification of Conflict Management

OpenAIRE

Koulu, Riikka

2016-01-01

This study, Dispute Resolution and Technology: Revisiting the Justification of Conflict Management, belongs to the fields of procedural law, legal theory and law and technology studies. In this study the changes in dispute resolution caused by technology are evaluated. The overarching research question of this study is how does implementing technology to dispute resolution challenge the justification of law as a legitimised mode of violence? Before answering such an abstract research question...

Deja vu: The Unified Command Plan of the Future Revisited

Science.gov (United States)

2011-05-19

Approved for Public Release; Distribution is Unlimited Déjà vu : The Unified Command Plan of the Future Revisited A Monograph by Lieutenant...DD-MM-YYYY) 19-05-2011 2. REPORT TYPE Monograph 3. DATES COVERED (From - To) JUL 2010 – MAY 2011 4. TITLE AND SUBTITLE Déjà vu : The Unified...i SCHOOL OF ADVANCED MILITARY STUDIES MONOGRAPH APPROVAL Lieutenant Colonel Edward Francis Martignetti Title of Monograph: Déjà vu : The Unified

Interpretation of transport barriers and of subneoclassical transport in the framework of the revisited neoclassical theory

International Nuclear Information System (INIS)

Rogister, A.L.

1999-01-01

'Subneoclassical' heat fluxes are predicted in the high collisionality regime by the revisited neoclassical theory, which includes the roles of Finite Larmor Radius effects and Inertia, that we published earlier. Unlike conventional neoclassical theory, the revisited theory further provides a non degenerate ambipolarity constraint which defines unambiguously the radial electric field. Together with the parallel momentum equation, the ambipolarity constraint leads, under some conditions, to radial electric field profiles with high negative shear akin to those observed in spontaneous edge transport barriers. The predictions of the theory are outlined, with emphasis laid on the interpretation of experimental results such as magnitude of the jumps, width of the shear layer, local scaling laws. Extension of the theory to triggered transitions and cold pulse propagation studies is suggested. (author)

How does the Ambience of Cafe Affect the Revisit Intention Among its Patrons? A S on the Cafes in Ipoh, Perak

Directory of Open Access Journals (Sweden)

AbuThahir Sharmeela-Banu Syed

2018-01-01

Full Text Available Food service industry is growing rapidly as a result of the changing consumer lifestyle. The food service industry is highly competitive due to the increasing number of new entrants offering inventive food products and services. In order to be outstanding in such competitive industry, retailers nowadays opt to emphasize on their store environment. Past studies discovered that store environment stimulates emotions that significantly boost customer revisit intention. As a result, retailers attempt to differentiate their store by combining various environmental stimuli to create an attractive ambience that will in turn draw in the customers. Hence, this study attempts to investigate the impact of various café ambience factors on the patrons’ revisit intention. The patrons of cafes in Ipoh, Perak were selected using purposive sampling technique to be the respondents of this study. 250 questionnaires were collected and Partial Least Square technique was used to analyse the data collected. Findings show that all the five factors of café ambience namely lighting, music, decoration, cleanliness and layouts were significantly influencing the patrons’ revisit intention. Of these five factors, lighting was most influential while music was the least influential in affecting the patrons’ revisit intention. Accordingly, this study lists several recommendations for practitioners and academics with regards to the store environment and its impact on the repurchase intention.

The synthesis and photocatalytic activity of ZnSe microspheres

International Nuclear Information System (INIS)

Cao Huaqiang; Xiao Yujiang; Zhang Sichun

2011-01-01

This paper reports the synthesis of semiconductor ZnSe microspheres composed of nanoparticles via a solvothermal route between the organic molecule selenophene (C 4 H 4 Se) and ZnCl 2 without adding any surfactant. The ZnSe microspheres were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), specific surface area measurement, and photoluminescence (PL) spectra. A strong and broad blue PL emission at 443 nm in wavelength (∼2.79 eV in photon energy) is attributed to the near-band-edge (NBE) emission of ZnSe, while the 530 nm peak is a defect-related (DL) emission. The photocatalytic activity of the as-prepared ZnSe microspheres was evaluated by photodegradation of methyl orange (MO) dye under ultraviolet (UV) light and visible light irradiation. The degradations of MO reach 94% or 95.1%, close to 100%, in the presence of the as-synthesized ZnSe microspheres or commercial ZnSe powder after 7 or 10 h under UV irradiation, respectively. Meanwhile the degradations of MO reach 94.3% or 60.6% in the presence of the as-synthesized ZnSe microspheres or commercial ZnSe powder after 12 h, respectively. The degradation rate of ZnSe microspheres is twice that of ZnSe commercial powder under UV light irradiation, and three times under visible light irradiation. The degradation process of MO dye on ZnSe microspheres under UV or visible light is also discussed.

Simple one-pot synthesis of platinum-palladium nanoflowers with enhanced catalytic activity and methanol-tolerance for oxygen reduction in acid media

International Nuclear Information System (INIS)

Zheng, Jie-Ning; He, Li-Li; Chen, Fang-Yi; Wang, Ai-Jun; Xue, Meng-Wei; Feng, Jiu-Ju

2014-01-01

Graphical abstract: PtPd nanoflowers were fabricated by one-pot solvothermal co-reduction method in oleylamine system, which exhibited the improved electrocatalytic activity and higher methanol tolerance for oxygen reduction, compared with commercial Pt and Pd black catalysts. - Highlights: • Bimetallic alloyed PtPd nanoflowers are prepared by a simple one-pot solvothermal co-reduction method. • PtPd nanoflowers display high catalytic performance for ORR dominated by a four-electron pathway. • PtPd nanoflowers show good methanol tolerance for ORR. - Abstract: In this work, bimetallic alloyed platinum-palladium (PtPd) nanoflowers are fabricated by one-pot solvothermal co-reduction of Pt (II) acetylacetonate and Pd (II) acetylacetonate in oleylamine system. The as-prepared nanostructures show the enhanced electrocatalytic activity for oxygen reduction reaction (ORR), dominated by a four-electron pathway based on the Koutecky-Levich plots, mainly owing to the inhibition of the formation of Pt–OH ad via the downshift of d-band center for Pt. Meanwhile, PtPd nanoflowers display good methanol tolerance and improved stability for ORR. The chronoamperometry test reveals that the current of PtPd nanoflowers remains 45.9% of its original value within 6000 s, much higher than those of commercial Pt (36.7%) and Pd (32.2%) black catalysts. Therefore, PtPd nanoflowers with unique interconnected structures can be used as a promising cathode catalyst in direct methanol fuel cells

Revisiting reflexology: Concept, evidence, current practice, and practitioner training

OpenAIRE

Embong, Nurul Haswani; Soh, Yee Chang; Ming, Long Chiau; Wong, Tin Wui

2015-01-01

Reflexology is basically a study of how one part of the human body relates to another part of the body. Reflexology practitioners rely on the reflexes map of the feet and hands to all the internal organs and other human body parts. They believe that by applying the appropriate pressure and massage certain spots on the feet and hands, all other body parts could be energized and rejuvenated. This review aimed to revisit the concept of reflexology and examine its effectiveness, practices, and th...

Revisiting the Metaphor of the Island: Challenging "World Culture" from an Island Misunderstood

Science.gov (United States)

Rappleye, Jeremy

2015-01-01

This article revisits the newly "discovered" island that world culture theorists have repeatedly utilised to explain their theoretical stance, conceptual preferences and methodological approach. Yet, it seeks to (re)connect world culture with the real world by replacing their imagined atoll with a real one--the island-nation of Japan. In…

Revisiting R-invariant direct gauge mediation

Energy Technology Data Exchange (ETDEWEB)

Chiang, Cheng-Wei [Center for Mathematics and Theoretical Physics andDepartment of Physics, National Central University,Taoyuan, Taiwan 32001, R.O.C. (China); Institute of Physics, Academia Sinica,Taipei, Taiwan 11529, R.O.C. (China); Physics Division, National Center for Theoretical Sciences,Hsinchu, Taiwan 30013, R.O.C. (China); Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); Harigaya, Keisuke [Department of Physics, University of California,Berkeley, California 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, California 94720 (United States); ICRR, University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Ibe, Masahiro [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); ICRR, University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Yanagida, Tsutomu T. [Kavli IPMU (WPI), UTIAS, University of Tokyo,Kashiwa, Chiba 277-8583 (Japan)

2016-03-21

We revisit a special model of gauge mediated supersymmetry breaking, the “R-invariant direct gauge mediation.” We pay particular attention to whether the model is consistent with the minimal model of the μ-term, i.e., a simple mass term of the Higgs doublets in the superpotential. Although the incompatibility is highlighted in view of the current experimental constraints on the superparticle masses and the observed Higgs boson mass, the minimal μ-term can be consistent with the R-invariant gauge mediation model via a careful choice of model parameters. We derive an upper limit on the gluino mass from the observed Higgs boson mass. We also discuss whether the model can explain the 3σ excess of the Z+jets+E{sub T}{sup miss} events reported by the ATLAS collaboration.

Revisiting kaon physics in general Z scenario

Directory of Open Access Journals (Sweden)

Motoi Endo

2017-08-01

Full Text Available New physics contributions to the Z penguin are revisited in the light of the recently-reported discrepancy of the direct CP violation in K→ππ. Interference effects between the standard model and new physics contributions to ΔS=2 observables are taken into account. Although the effects are overlooked in the literature, they make experimental bounds significantly severer. It is shown that the new physics contributions must be tuned to enhance B(KL→π0νν¯, if the discrepancy of the direct CP violation is explained with satisfying the experimental constraints. The branching ratio can be as large as 6×10−10 when the contributions are tuned at the 10% level.

Revisiting the Decision of Death in Hurst v. Florida.

Science.gov (United States)

Cooke, Brian K; Ginory, Almari; Zedalis, Jennifer

2016-12-01

The United States Supreme Court has considered the question of whether a judge or a jury must make the findings necessary to support imposition of the death penalty in several notable cases, including Spaziano v. Florida (1984), Hildwin v. Florida (1989), and Ring v. Arizona (2002). In 2016, the U.S. Supreme Court revisited the subject in Hurst v. Florida Florida Statute § 921.141 allows the judge, after weighing aggravating and mitigating circumstances, to enter a sentence of life imprisonment or death. Before Hurst, Florida's bifurcated sentencing proceedings included an advisory sentence from jurors and a separate judicial hearing without juror involvement. In Hurst, the Court revisited the question of whether Florida's capital sentencing scheme violates the Sixth Amendment, which requires a jury, not a judge, to find each fact necessary to impose a sentence of death in light of Ring In an eight-to-one decision, the Court reversed the judgment of the Florida Supreme Court, holding that the Sixth Amendment requires a jury to find the aggravating factors necessary for imposing the death penalty. The role of Florida juries in capital sentencing proceedings was thereby elevated from advisory to determinative. We examine the Court's decision and offer commentary regarding this shift from judge to jury in the final imposition of the death penalty and the overall effect of this landmark case. © 2016 American Academy of Psychiatry and the Law.

Magnetic moments revisited

International Nuclear Information System (INIS)

Towner, I.S.; Khanna, F.C.

1984-01-01

Consideration of core polarization, isobar currents and meson-exchange processes gives a satisfactory understanding of the ground-state magnetic moments in closed-shell-plus (or minus)-one nuclei, A = 3, 15, 17, 39 and 41. Ever since the earliest days of the nuclear shell model the understanding of magnetic moments of nuclear states of supposedly simple configurations, such as doubly closed LS shells +-1 nucleon, has been a challenge for theorists. The experimental moments, which in most cases are known with extraordinary precision, show a small yet significant departure from the single-particle Schmidt values. The departure, however, is difficult to evaluate precisely since, as will be seen, it results from a sensitive cancellation between several competing corrections each of which can be as large as the observed discrepancy. This, then, is the continuing fascination of magnetic moments. In this contribution, we revisit the subjet principally to identify the role played by isobar currents, which are of much concern at this conference. But in so doing we warn quite strongly of the dangers of considering just isobar currents in isolation; equal consideration must be given to competing processes which in this context are the mundane nuclear structure effects, such as core polarization, and the more popular meson-exchange currents

Growth of the firm and foreign trade: Adrian Wood's theory revisited

OpenAIRE

Catermol, Fabrício

2006-01-01

This paper analyzes the growth of the firm by foreign trade. The theory of Adrian Wood is revisited for the analysis of growth and profit trade-off and improved to cope with growth by exports. The main outcome of this paper is that low domestic demand can be a very important factor to firm choices growth by foreign market. However, the growth of domestic demand does not necessarily reduce exports.

Revisiting the description of Protein-Protein interfaces. Part II: Experimental study

OpenAIRE

Cazals , Frédéric; Proust , Flavien

2006-01-01

This paper provides a detailed experimental study of an interface model developed in the companion article F. Cazals and F. Proust, Revisiting the description of Protein-Protein interfaces. Part I: algorithms. Our experimental study is concerned with the usual database of protein-protein complexes, split into five families (Proteases, Immune system, Enzyme Complexes, Signal transduction, Misc.) Our findings, which bear some contradictions with usual statements are the following: (i)Connectivi...

Small-angle scattering theory revisited: Photocurrent and spatial localization

DEFF Research Database (Denmark)

Basse, N.P.; Zoletnik, S.; Michelsen, Poul

2005-01-01

In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto......- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize quantities from two...

Article Review: Advanced Change Theory Revisited: An Article Critique

Directory of Open Access Journals (Sweden)

R. Scott Pochron

2008-12-01

Full Text Available The complexity of life in 21st century society requires new models for leadingand managing change. With that in mind, this paper revisits the model for AdvancedChange Theory (ACT as presented by Quinn, Spreitzer, and Brown in their article,“Changing Others Through Changing Ourselves: The Transformation of HumanSystems” (2000. The authors present ACT as a potential model for facilitating change incomplex organizations. This paper presents a critique of the article and summarizesopportunities for further exploring the model in the light of current trends indevelopmental and integral theory.

Solvent transfer of graphene oxide for synthesis of tin mono-sulfide graphene composite and application as anode of lithium-ion battery

Energy Technology Data Exchange (ETDEWEB)

Tripathi, Alok M., E-mail: alokmani@iitb.ac.in; Mitra, Sagar

2016-11-15

Graphical abstract: Destabilization of graphene oxide colloid and SnS graphene composite preparation for lithium-ion battery. - Abstract: Tin mono sulfide (SnS) graphene composite has been synthesized for anode of lithium-ion battery. For synthesis of composite, graphene oxide (GO)-water (H{sub 2}O) colloid has been destabilized and ensured the complete transfer of graphene oxide into another organic solvent N, N-dimethyl formamide (DMF). Mechanism for the destabilization of GO-H{sub 2}O colloid is established. Surface to surface attachment of SnS on graphene sheet is achieved by solvothermal solution phase assembly of graphene sheets and SnS nanoparticles in DMF solvent. Graphene plays role in nanoparticle formation in composite. Such confined composite has been cycled reversibly at current rate of 160 mA g{sup −1}, in voltage region of 0.01–2.5 V and exhibit a superior discharge capacity of 630 mAh g{sup −1} after 50th cycle. Ex situ TEM analysis of used electrode reveal that the SnS nanoparticle-graphene composite with CMC binder perform better due to proper shape retention of electroactive materials during electrochemical cycling.

Solvent transfer of graphene oxide for synthesis of tin mono-sulfide graphene composite and application as anode of lithium-ion battery

International Nuclear Information System (INIS)

Tripathi, Alok M.; Mitra, Sagar

2016-01-01

Graphical abstract: Destabilization of graphene oxide colloid and SnS graphene composite preparation for lithium-ion battery. - Abstract: Tin mono sulfide (SnS) graphene composite has been synthesized for anode of lithium-ion battery. For synthesis of composite, graphene oxide (GO)-water (H_2O) colloid has been destabilized and ensured the complete transfer of graphene oxide into another organic solvent N, N-dimethyl formamide (DMF). Mechanism for the destabilization of GO-H_2O colloid is established. Surface to surface attachment of SnS on graphene sheet is achieved by solvothermal solution phase assembly of graphene sheets and SnS nanoparticles in DMF solvent. Graphene plays role in nanoparticle formation in composite. Such confined composite has been cycled reversibly at current rate of 160 mA g"−"1, in voltage region of 0.01–2.5 V and exhibit a superior discharge capacity of 630 mAh g"−"1 after 50th cycle. Ex situ TEM analysis of used electrode reveal that the SnS nanoparticle-graphene composite with CMC binder perform better due to proper shape retention of electroactive materials during electrochemical cycling.

Creative Experience and Revisit Intention of Handmade Oriental Parasol Umbrella in Kaohsiung

OpenAIRE

Yi-Ju Lee

2015-01-01

This study identified the hypothesised relationship between creative experience, and revisit intention of handmade oriental parasol umbrella in Kaohsiung, Taiwan. A face-to-face questionnaire survey was administered in Meinong town, Kaohsiung. The components of creative experience were found as "sense of achievement", "unique learning" and "interaction with instructors" in creative tourism. The result also revealed significant positive relationships between creative exper...

Mg doped Li2FeSiO4/C nanocomposites synthesized by the solvothermal method for lithium ion batteries.

Science.gov (United States)

Kumar, Ajay; Jayakumar, O D; Jagannath; Bashiri, Parisa; Nazri, G A; Naik, Vaman M; Naik, Ratna

2017-10-14

A series of porous Li 2 Fe 1-x Mg x SiO 4 /C (x = 0, 0.01, 0.02, 0.04) nanocomposites (LFS/C, 1Mg-LFS/C, 2Mg-LFS and 4Mg-LFS/C) have been synthesized via a solvo-thermal method using the Pluronic P123 polymer as an in situ carbon source. Rietveld refinement of the X-ray diffraction data of Li 2 Fe 1-x Mg x SiO 4 /C composites confirms the formation of the monoclinic P2 1 structure of Li 2 FeSiO 4 . The addition of Mg facilitates the growth of impurity-free Li 2 FeSiO 4 with increased crystallinity and particle size. Despite having the same percentage of carbon content (∼15 wt%) in all the samples, the 1Mg-LFS/C nanocomposite delivered the highest initial discharge capacity of 278 mA h g -1 (∼84% of the theoretical capacity) at the C/30 rate and also exhibited the best rate capability and cycle stability (94% retention after 100 charge-discharge cycles at 1C). This is attributed to its large surface area with a narrow pore size distribution and a lower charge transfer resistance with enhanced Li-ion diffusion coefficient compared to other nanocomposites.

Characteristics of revisits of children at risk for serious infections in pediatric emergency care

NARCIS (Netherlands)

E. De Vos-Kerkhof (Evelien); D.H.F. Geurts (Dorien); E.W. Steyerberg (Ewout); M. Lakhanpaul (Monica); H.A. Moll (Henriëtte); R. Oostenbrink (Rianne)

2018-01-01

textabstractIn this study, we aimed to identify characteristics of (unscheduled) revisits and its optimal time frame after Emergency Department (ED) discharge. Children with fever, dyspnea, or vomiting/diarrhea (1 month–16 years) who attended the ED of Erasmus MC-Sophia, Rotterdam (2010–2013), the

Synthesis, structure and characterization of two new open-framework gallium phosphite-oxalates of varying dimensionality

International Nuclear Information System (INIS)

Li, Caixia; Huang, Liangliang; Zhou, Mingdong; Xia, Jing; Ma, Hongwei; Zang, Shuliang; Wang, Li

2013-01-01

Using N, N-dimethyl-piperazine as structure directing agent, two new gallium phosphite-oxalates [Ga 2 (HPO 3 ) 2 (H 2 PO 3 ) 2 (C 2 O 4 )](C 6 N 2 H 16 ) (I) and [Ga 2 (HPO 3 ) 2 (H 2 PO 3 )(C 2 O 4 )](C 6 N 2 H 16 ) 0.5 (II) have been synthesized under solvothermal and hydrothermal conditions, respectively and further characterized by powder X-ray diffraction, IR spectroscopy, TGA, ICP-AES and elemental analyses. Single crystal X-ray diffraction reveals that the striking feature of I and II is that they possess the same second building unit (SBU) Ga 2 P 2 constructed from two GaO 6 octahedra and two [HPO 3 2− ] pseudo-pyramids sharing oxygen atoms. However, due to the different connecting fashions of SBUs, [C 2 O 4 2− ] groups and [H 2 PO 3 − ] pseudo-pyramids, the final frameworks of them are distinctly different. Compound I shows 2D layered structures with 8-membered ring (8-MR) windows in the ab plane while compound II presents a 3D open-framework with 8-MR channels along the b axis. - Graphical abstract: Using N, N-dimethyl-piperazine as structure directing agent, two new gallium phosphite-oxalates I showing 2D layered structure and II presenting 3D open-framework have been synthesized under solvothermal and hydrothermal conditions, respectively. - Highlights: • Using N, N-dimethyl-piperazine as structure directing agent, two new gallium phosphite-oxalates have been synthesized under solvothermal and hydrothermal conditions, respectively. • The same second building unit (SBU) is displayed in both compounds. • Compound I shows 2D layered structure with 8-MR windows while compound II presents 3D open-framework with 8-MR channels. • The solvent plays an important role on the formation of microporous compounds

Post-Inflationary Gravitino Production Revisited

CERN Document Server

Ellis, John; Nanopoulos, Dimitri V.; Olive, Keith A.; Peloso, Marco

2016-01-01

We revisit gravitino production following inflation. As a first step, we review the standard calculation of gravitino production in the thermal plasma formed at the end of post-inflationary reheating when the inflaton has completely decayed. Next we consider gravitino production prior to the completion of reheating, assuming that the inflaton decay products thermalize instantaneously while they are still dilute. We then argue that instantaneous thermalization is in general a good approximation, and also show that the contribution of non-thermal gravitino production via the collisions of inflaton decay products prior to thermalization is relatively small. Our final estimate of the gravitino-to-entropy ratio is approximated well by a standard calculation of gravitino production in the post-inflationary thermal plasma assuming total instantaneous decay and thermalization at a time $t \\simeq 1.2/\\Gamma_\\phi$. Finally, in light of our calculations, we consider potential implications of upper limits on the gravitin...

Multicolor upconversion emission of dispersed ultrasmall cubic Sr2LuF7 nanocrystals synthesized by a solvothermal process

International Nuclear Information System (INIS)

Gong, Lunjun; Ma, Mo; Xu, Changfu; Li, Xujun; Wang, Suiping; Lin, Jianguo; Yang, Qibin

2013-01-01

Lanthanide (Ln 3+ ) doped Sr 2 LuF 7 (Ln 3+ =Er 3+ /Tm 3+ /Yb 3+ ) nanocrystals (NCs) were synthesized via a solvothermal process using oleate as stabilizing agent. The as-synthesized NCs with a mean diameter of sub-20 nm can be well dispersed in cyclohexane and show a pure cubic phase structure with space group Fm3 ¯ m. Following appropriate lanthanide ion doping, the NCs show intense red, green, blue and white-color upconversion emission (UC) under the excitation of a 980 nm laser. Predominant near-infrared UC can also be obtained in the Yb 3+ /Tm 3+ doped Sr 2 LuF 7 NCs. The energy transfer UC mechanisms for the fluorescent intensity were also investigated. The desirable property of the ultrasmall dispersed NCs makes them promising materials for the applications in miniaturized solid-state light sources, multicolor three-dimensional display devices and fluorescent labels for biomedical imaging. - Highlights: ► Cubic-structure (Fm3 ¯ m) Sr 2 LuF 7 nanocrystals were synthesized for the first time. ► Nanocrystals (sub-20 nm) with cubic or spherical shape can be well dispersed. ► By doping properly, the nanocrystals show intense multicolor upconversion. ► Predominant near-infrared upconversion can be obtained in Sr 2 LuF 7 nanocrystals. ► Upconversion mechanism for the fluorescent intensity is mainly energy transfer.

Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln==Sm, Eu, Gd) and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln==Tb, Dy, Ho)

Energy Technology Data Exchange (ETDEWEB)

Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian, E-mail: jiadingxian@suda.edu.cn

2013-10-15

Solvothermal reactions of Ln{sub 2}O{sub 3}, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln{sub 2}O{sub 3} oxides were converted to [Ln(dien){sub 2}]{sup 3+} complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS{sub 4} unit. In 1−3, the AsS{sub 4} units interconnect the [Ln(dien){sub 2}]{sup 3+} cations via Ln−S bonds as tridentate μ-1κ,2κ{sup 2}-AsS{sub 4} bridging ligands, resulting in the neutral coordination polymers [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln1). In 4−6, the AsS{sub 4} units coordinate with the Ln{sup 3+} ion of [Ln(dien){sub 2}]{sup 3+} as 1κ{sup 2}-AsS{sub 4} chelating ligands to form neutral coordination compounds [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln2). The Ln{sup 3+} ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln{sup 3+} ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] were prepared by solvothermal methods and the soft Lewis basic AsS{sub 4}{sup 3–} ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS{sub 4} ligand coordinate Ln{sup 3+} ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors

Revisiting the Gun Ownership and Violence Link; a multi- level analysis of victimisation survey data.

NARCIS (Netherlands)

van Kesteren, J.N.

2014-01-01

The link between gun ownership victimisation by violent crime remains one of the most contested issues in criminology. Some authors claim that high gun availability facilitates serious violence. Others claim that gun ownership prevents crime. This article revisits these issues using individual and

NP-hardness of the cluster minimization problem revisited

Science.gov (United States)

Adib, Artur B.

2005-10-01

The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested.

NP-hardness of the cluster minimization problem revisited

International Nuclear Information System (INIS)

Adib, Artur B

2005-01-01

The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested

NP-hardness of the cluster minimization problem revisited

Energy Technology Data Exchange (ETDEWEB)

Adib, Artur B [Physics Department, Brown University, Providence, RI 02912 (United States)

2005-10-07

The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested.

Rural-Nonrural Disparities in Postsecondary Educational Attainment Revisited

Science.gov (United States)

Byun, Soo-yong; Meece, Judith L.; Irvin, Matthew J.

2013-01-01

Using data from the National Educational Longitudinal Study, this study revisited rural-nonrural disparities in educational attainment by considering a comprehensive set of factors that constrain and support youth's college enrollment and degree completion. Results showed that rural students were more advantaged in community social resources compared to nonrural students, and these resources were associated with a significant increase in the likelihood of bachelor's degree attainment. Yet results confirmed that rural students lagged behind nonrural students in attaining a bachelor's degree largely due to their lower socioeconomic background. The findings present a more comprehensive picture of the complexity of geographic residence in shaping college enrollment and degree attainment. PMID:24285873

Effects of fish farm waste on Posidonia oceanica meadows: Synthesis and provision of monitoring and management tools

Energy Technology Data Exchange (ETDEWEB)

Holmer, Marianne [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)], E-mail: holmer@biology.sdu.dk; Argyrou, Marina [Marine Environment Division, Department of Fisheries and Marine Research, Ministry of Agriculture, Natural Resources and Environment, 101 Bethleem Street, 1416 Nicosia (Cyprus); Dalsgaard, Tage [Department of Marine Ecology, National Environmental Research Institute, Aarhus University, Vejlsovej 25, P.O. Box 314, DK-8600 Silkeborg (Denmark); Danovaro, Roberto [Department of Marine Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Diaz-Almela, Elena; Duarte, Carlos M. [IMEDEA (CSIC-UIB), Miquel Marques 21, 07190 Esporles (Illes Balears) (Spain); Frederiksen, Morten [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Grau, Antoni [Direccio General de Pesca, Conselleria d' Agricultura i Pesca, Govern de les Illes Balears, Foners 10, 07006 Palma de Mallorca (Illes Balears) (Spain); Karakassis, Ioannis [Marine Ecology Laboratory, Biology Department, University of Crete, Heraklion, 71409 Crete (Greece); Marba, Nuria [IMEDEA (CSIC-UIB), Miquel Marques 21, 07190 Esporles (Illes Balears) (Spain); Mirto, Simone [Institute for the Marine Coastal Environment, National Council of Research, Spianata S. Raineri, 86, 98122 Messina (Italy); Perez, Marta [Departament d' Ecologia, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona (Spain); Pusceddu, Antonio [Department of Marine Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Tsapakis, Manolis [Institute of Oceanography, Hellenic Center for Marine Research, P.O. Box 2214, GR 71003 Heraklion, Crete (Greece)

2008-09-15

This paper provides a synthesis of the EU project MedVeg addressing the fate of nutrients released from fish farming in the Mediterranean with particular focus on the endemic seagrass Posidonia oceanica habitat. The objectives were to identify the main drivers of seagrass decline linked to fish farming and to provide sensitive indicators of environmental change, which can be used for monitoring purposes. The sedimentation of waste particles in the farm vicinities emerges as the main driver of benthic deterioration, such as accumulation of organic matter, sediment anoxia as well as seagrass decline. The effects of fish farming on P. oceanica meadows are diverse and complex and detected through various metrics and indicators. A safety distance of 400 m is suggested for management of P. oceanica near fish farms followed by establishment of permanent seagrass plots revisited annually for monitoring the health of the meadows.

Effects of fish farm waste on Posidonia oceanica meadows: Synthesis and provision of monitoring and management tools

International Nuclear Information System (INIS)

Holmer, Marianne; Argyrou, Marina; Dalsgaard, Tage; Danovaro, Roberto; Diaz-Almela, Elena; Duarte, Carlos M.; Frederiksen, Morten; Grau, Antoni; Karakassis, Ioannis; Marba, Nuria; Mirto, Simone; Perez, Marta; Pusceddu, Antonio; Tsapakis, Manolis

2008-01-01

This paper provides a synthesis of the EU project MedVeg addressing the fate of nutrients released from fish farming in the Mediterranean with particular focus on the endemic seagrass Posidonia oceanica habitat. The objectives were to identify the main drivers of seagrass decline linked to fish farming and to provide sensitive indicators of environmental change, which can be used for monitoring purposes. The sedimentation of waste particles in the farm vicinities emerges as the main driver of benthic deterioration, such as accumulation of organic matter, sediment anoxia as well as seagrass decline. The effects of fish farming on P. oceanica meadows are diverse and complex and detected through various metrics and indicators. A safety distance of 400 m is suggested for management of P. oceanica near fish farms followed by establishment of permanent seagrass plots revisited annually for monitoring the health of the meadows

Synthesis of Zn-Cu-Cd sulfide nanospheres with controlled copper locations and their effects on photocatalytic activities for H{sub 2} production

Energy Technology Data Exchange (ETDEWEB)

Wang, Yabo; Xu, Rong [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Wang, Yongsheng [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2010-06-15

In this work, a two-step solvothermal method was used to synthesize Zn-Cu-Cd sulfide nanospheres with controlled copper locations. The structural and other physical properties of the nanospheres were investigated by XRD, FESEM, TEM, energy-filtered TEM, XPS, ICP and UV-vis DRS methods. By varying the addition of the copper precursor during the two synthesis steps, Zn-Cu-Cd sulfide nanospheres with three distinctive copper distribution patterns can be obtained with copper (i) only in the core, (ii) only on the surface shell, and (iii) both in the core and on the surface shell. The influence of the location and concentration of copper on the photocatalytic activity for hydrogen production from water under visible light was investigated. It was found that the activity of the sample with copper only on the surface shell is about two times of that with copper only in the core. The highest hydrogen production rate was obtained on the nanosphere sample with copper both in the core and on the surface shell. The possible mechanism was discussed. The findings from this study are important for the development of efficient photocatalysts based on ternary or multinary systems. (author)

An Improvement on LSB Matching and LSB Matching Revisited Steganography Methods

OpenAIRE

Qazanfari, Kazem; Safabakhsh, Reza

2017-01-01

The aim of the steganography methods is to communicate securely in a completely undetectable manner. LSB Matching and LSB Matching Revisited steganography methods are two general and esiest methods to achieve this aim. Being secured against first order steganalysis methods is the most important feature of these methods. On the other hand, these methods don't consider inter pixel dependency. Therefore, recently, several steganalysis methods are proposed that by using co-occurrence matrix detec...

Forecasting of Satisfaction and Revisit Intention of Indonesia Shoppers in Shopping Malls

OpenAIRE

Ayuni, Risca Fitri

2017-01-01

. Due to tight competition, changing value proposition of customer and shiftingof mall functions become center for leisure purposes, shopping mall developer mustfocus on create shopper satisfaction to influence their post-transaction behaviors. Thisstudy investigates the relationship between mall personality, self-congruity, perceivedquality, shopping value, shopper satisfaction and revisit intention. Two hundredrespondents participated in this study. In order to achieve the aim of this study...

Sparse random matrices: The eigenvalue spectrum revisited

International Nuclear Information System (INIS)

Semerjian, Guilhem; Cugliandolo, Leticia F.

2003-08-01

We revisit the derivation of the density of states of sparse random matrices. We derive a recursion relation that allows one to compute the spectrum of the matrix of incidence for finite trees that determines completely the low concentration limit. Using the iterative scheme introduced by Biroli and Monasson [J. Phys. A 32, L255 (1999)] we find an approximate expression for the density of states expected to hold exactly in the opposite limit of large but finite concentration. The combination of the two methods yields a very simple geometric interpretation of the tails of the spectrum. We test the analytic results with numerical simulations and we suggest an indirect numerical method to explore the tails of the spectrum. (author)

Highway 61 Revisited: Bob Dilan i francuski poststrukturalizam / Highway 61 Revisited: Bob Dilan and French Poststructuralism

Directory of Open Access Journals (Sweden)

Nikola Dedić

2013-06-01

Full Text Available The main aim of this text is to show parallels between rock music and poststructuralist philosophy. As a case study one of the most celebrated rock albums of all times – Bob Dylan’s Highway 61 Revisited from 1965 is taken. It is one of the crucial albums in the history of popular culture which influenced further development of rock music within American counter culture of the 60s. Dylan’s turn from the politics of American New Left and folk movement, his relation towards the notions of the author and intertextuality, and his connection with experimental usage of language in the manner of avant-garde and neoavant-garde poetry, are juxtaposed with the main philosophical standpoints of Jean-François Lyotard, Jean Baudrillard, Roland Barthes and Julia Kristeva which historically and chronologically coincide with the appearance of Dylan’s album.

Structuralism's Relevance in a Post-Structural Era: Re-Visiting Research on Multicultural Curricular Studies

Science.gov (United States)

Shim, Jenna Min

2011-01-01

At the current historical juncture in which differences and inequalities are surfacing greater than ever in the world, societies, and schools, the main goal of this essay is to revisit the aspects of structuralism that can potentially contribute productively to understanding the invisible structures and forces that everyone carries (mostly…

Solvothermal modification of BiOCl nanosheets with Bi nanoparticles using ascorbic acid as reductant and the superoxide radicals dominated photocatalytic performance

Science.gov (United States)

Cui, Zhankui; Gao, Keke; Ge, Suxiang; Fa, Wenjun

2017-11-01

BiOCl nanosheets were solvothermally modified with Bi nanoparticles (NPs) using ascorbic acid as the reductant. The structures of Bi/BiOCl composites were characterized by XRD, Raman spectroscopy, FTIR spectroscopy and SEM. The light absorption properties were measured by UV-vis-NIR spectroscopy. The photocatalytic performances were evaluated by photodegrading methyl orange (MO) and the photocatalytic mechanism was investigated using trapping experiments and a fluorescent probe method. The results show that Bi NPs are uniformly distributed on the surfaces of BiOCl nanosheets and the modification amount of Bi NPs could be well controlled because of the mild property of ascorbic acid as reducing agent. The photocatalytic activities for the composites are improved obviously and the best photocatalytic performance is obtained when the weight ratio of Bi and BiOCl is1:10 and the photochemical reaction rate is 3.5 times that of pure BiOCl nanosheets and 19.7 times of Bi powders. The enhanced photocatalytic efficiency is ascribed to the favorable formation of dominant \\cdot O2- radicals caused by the increased photoinduced electrons from both Bi NPs and BiOCl nanosheets.

The skeptical green consumer revisited: testing the relationship between green consumerism and skepticism toward advertising

NARCIS (Netherlands)

Matthes, J.; Wonneberger, A.

2014-01-01

This article revisits the widely believed notion of the skeptical green consumer, in other words, that green consumers tend to distrust green advertising. Study 1, a survey of U.S. consumers, found no positive relationship between green consumerism and general ad skepticism. However, green

A Cooperative Search and Coverage Algorithm with Controllable Revisit and Connectivity Maintenance for Multiple Unmanned Aerial Vehicles

Directory of Open Access Journals (Sweden)

Zhong Liu

2018-05-01

Full Text Available In this paper, we mainly study a cooperative search and coverage algorithm for a given bounded rectangle region, which contains several unknown stationary targets, by a team of unmanned aerial vehicles (UAVs with non-ideal sensors and limited communication ranges. Our goal is to minimize the search time, while gathering more information about the environment and finding more targets. For this purpose, a novel cooperative search and coverage algorithm with controllable revisit mechanism is presented. Firstly, as the representation of the environment, the cognitive maps that included the target probability map (TPM, the uncertain map (UM, and the digital pheromone map (DPM are constituted. We also design a distributed update and fusion scheme for the cognitive map. This update and fusion scheme can guarantee that each one of the cognitive maps converges to the same one, which reflects the targets’ true existence or absence in each cell of the search region. Secondly, we develop a controllable revisit mechanism based on the DPM. This mechanism can concentrate the UAVs to revisit sub-areas that have a large target probability or high uncertainty. Thirdly, in the frame of distributed receding horizon optimizing, a path planning algorithm for the multi-UAVs cooperative search and coverage is designed. In the path planning algorithm, the movement of the UAVs is restricted by the potential fields to meet the requirements of avoiding collision and maintaining connectivity constraints. Moreover, using the minimum spanning tree (MST topology optimization strategy, we can obtain a tradeoff between the search coverage enhancement and the connectivity maintenance. The feasibility of the proposed algorithm is demonstrated by comparison simulations by way of analyzing the effects of the controllable revisit mechanism and the connectivity maintenance scheme. The Monte Carlo method is employed to validate the influence of the number of UAVs, the sensing radius

A Robust Solution of the Spherical Burmester Problem

DEFF Research Database (Denmark)

Angeles, Jorge; Bai, Shaoping

2010-01-01

The problem of spherical four-bar linkage synthesis is revisited in this paper. The work is aimed at developing a robust synthesis method by taking into account both the formulation and the solution method. In addition, the synthesis of linkages with spherical prismatic joints is considered...... by treating them as a special case of the linkages under study. A two-step synthesis method is developed, which sequentially deals with equation-solving by a semigraphical approach and branching-detection. Examples are included to demonstrate the proposed method....

The role of brand destination experience in determining revisit intention

DEFF Research Database (Denmark)

Mattsson, Jan; Barnes, Stuart; Sørensen, Flemming

Destination branding has developed considerably as a topic area in the last decade with numerous conceptualizations focusing on different aspects of the brand. However, a unified view has not yet emerged. This paper examines destination branding via a new conceptualization, brand destination...... experience, which provides a more holistic and unified view of the brand destination. The research uses a logistic regression model to determine the role of satisfaction and brand experience in determining revisit intentions. The study also examines differences among subgroups and four brand experience sub...

2,4,6-Triamino-1,3,5-triazine-1,3-diium aquapentafluoridoaluminate

Directory of Open Access Journals (Sweden)

V. Maisonneuve

2008-04-01

Full Text Available The title compound, (C3H8N6[AlF5(H2O], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, 1,3,5-triazine-2,4,6-triamine (melamine, aqueous HF and water at 323 K for 48 h. The structure consists of [AlF5(H2O]2− octahedra and diprotonated melaminium cations. Cohesion is ensured by a three-dimensional network of hydrogen bonds.

Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.

Science.gov (United States)

Lemaire, Paul C; Zhao, Junjie; Williams, Philip S; Walls, Howard J; Shepherd, Sarah D; Losego, Mark D; Peterson, Gregory W; Parsons, Gregory N

2016-04-13

Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.

Controlled fabrication and tunable photoluminescence properties of Mn2+ doped graphene–ZnO composite

International Nuclear Information System (INIS)

Luan, Xinglong; Zhang, Yihe; Tong, Wangshu; Shang, Jiwu; An, Qi; Huang, Hongwei

2014-01-01

Highlights: • Graphene–ZnO composites were synthesized by a mixed solvothermal method. • ZnO quantum dots are distributed uniformly on the graphene sheets. • A possible hypothesis is raised for the influence of graphene oxide on the nucleation of ZnO. • Mn 2+ doped graphene–ZnO composites were fabricated and the emission spectra can be tuned by doping. - Abstract: Graphene–ZnO composites (G–ZnO) with controlled morphology and photoluminescence property were synthesized by a mixed solvothermal method. Mixed solvent were composed by dimethyl sulfoxide and ethylene glycol. Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectra were used to characterize G–ZnO. Graphene as a substrate can help the distribution and the dispersity of ZnO, and a possible model of the interaction between graphene oxide and ZnO particles is proposed. At the same time, graphene also reduce the size of ZnO particles to about 5 nm. Furthermore, Mn 2+ ions dopes G–ZnO successfully by the mixed solvothermal synthesis and the doping of Mn 2+ makes G–ZnO shift red from 465 nm to 548 nm and 554 nm in the emission spectrum. The changes of the emission spectrum by the adding of Mn 2+ make G–ZnO have tunable photoluminescence spectrum which is desirable for practical applications

Synthesis, deposition and crystal growth of CZTS nanoparticles onto ceramic tiles

Directory of Open Access Journals (Sweden)

Ivan Calvet

2015-09-01

Full Text Available The work presents a simple solvothermal method for CZTS nanoparticles preparation using hexadecylamine (HDA as a capping agent. The as-prepared CZTS powder was deposited as ink using Doctor Blade technique onto ceramic tile, as a substrate substituting the typical soda-lime glass. The as-prepared film was thermal treated at different temperatures in order to enhance the thin film crystallinity. CZTS crystal growth onto ceramic tile was obtained successfully for the first time.

Explaining tourists satisfaction and intention to revisit Nha Trang, Viet Nam

OpenAIRE

Tran, Thi Ai Cam

2011-01-01

The first purpose of the thesis is to find how visitors evaluate the quality of different facets or attributes of a destination image of Nha Trang, how satisfied they are with Nha Trang, loyalty intention to revisit and willingness to recommend Nha Trang to others. The second is to investigate what “image” is most important to explain global satisfaction with visiting Nha Trang. The third is to investigate how perceived quality, satisfaction and other motivational or dismotivational factors ...

Solvothermal synthesis and characterization of acicular α-Fe2O3 ...

Indian Academy of Sciences (India)

Administrator

dispersive X-ray microanalysis (EDAX), X-ray photoelectron spectroscopy (XPS), scanning electron micro- ... acicular shaped nanoparticles are seen in TEM images with an aspect ratio ~ 12; typically 8–12 nm wide and .... no impurity signal.

Green Synthesis of Boron Carbonitride with High Capacitance

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Dongping Chen

2018-03-01

Full Text Available Boron carbonitrides (BCN have attracted great interest in superhard or energy storage materials. In this work, thin BCN sheets were synthesized at 250 °C by a facile and green solvothermal method. The structure and morphology were characterized by X-ray diffraction (XRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Based on the results of electrochemical experiments, the thin BCN sheet exhibited excellent capacitance performance (343.1 F/g at a current density of 0.5 A/g and cycling stability (90%, which showed high potential applications in supercapacitors.

Revisiting Organizational Credibility and Organizational Reputation – A Situational Crisis Communication Approach

OpenAIRE

Jamal Jamilah; Abu Bakar Hassan

2017-01-01

Organizational credibility, the extent of which an organization as the source of messages is perceived as trustworthy and reliable, is one important aspect to determine organization’s survival. The perceived credibility of the messages will either strengthen or worsen an organization reputation. The primary objective of this paper is to revisit the concept of organizational credibility and its interaction with organizational outcomes such as organizational reputation. Based on the situational...

Service-Learning in Crisis Communication Education: Revisiting Coombs' Objectives for the Crisis Communication Course

Science.gov (United States)

Maresh-Fuehrer, Michelle M.

2015-01-01

The purpose of this study was to revisit Coombs' suggestions for teaching the crisis communication course using service-learning as a framework. The author sought to assess the effectiveness of using this method in terms of the benefits to both students and the partnering organization and students' perceptions of whether they met the learning…

Revisiting coupled Shukla-Varma and convective cell mode in classical and quantum dusty magnetoplasmas

Science.gov (United States)

Masood, W.; Mirza, Arshad M.; Nargis, Shahida

2010-08-01

The coupled Shukla-Varma (SV) and convective cell mode is revisited in classical and quantum dusty magnetoplasmas. It is shown that the inclusion of electron thermal effects modifies the original coupled SV and convective cell mode. It is also discussed how the quantum effects can be incorporated in the coupled SV and convective cell mode.

The Faraday effect revisited General theory

CERN Document Server

Cornean, H D; Pedersen, T G

2005-01-01

This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse conductivity can be explicitly computed and coincides with the classical result. In the general case, using magnetic perturbation theory, the conductivity tensor is expanded in powers of the strength of the magnetic field $B$. Then the linear term in $B$ of this expansion is written down in terms of the zero magnetic field Green function and the zero field current operator. In the periodic case, the linear term in $B$ of the conductivity tensor is expressed in terms of zero magnetic field Bloch functions and energies. No derivatives with respect to the quasimomentum appear and thereby all ambiguities are removed, in contrast to earlier work.

Re-visiting the electrophysiology of language.

Science.gov (United States)

Obleser, Jonas

2015-09-01

This editorial accompanies a special issue of Brain and Language re-visiting old themes and new leads in the electrophysiology of language. The event-related potential (ERP) as a series of characteristic deflections ("components") over time and their distribution on the scalp has been exploited by speech and language researchers over decades to find support for diverse psycholinguistic models. Fortunately, methodological and statistical advances have allowed human neuroscience to move beyond some of the limitations imposed when looking at the ERP only. Most importantly, we currently witness a refined and refreshed look at "event-related" (in the literal sense) brain activity that relates itself more closely to the actual neurobiology of speech and language processes. It is this imminent change in handling and interpreting electrophysiological data of speech and language experiments that this special issue intends to capture. Copyright © 2015 Elsevier Inc. All rights reserved.

Revisiting the Performance of MACD and RSI Oscillators

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Terence Tai-Leung Chong

2014-02-01

Full Text Available Chong and Ng (2008 find that the Moving Average Convergence–Divergence (MACD and Relative Strength Index (RSI rules can generate excess return in the London Stock Exchange. This paper revisits the performance of the two trading rules in the stock markets of five other OECD countries. It is found that the MACD(12,26,0 and RSI(21,50 rules consistently generate significant abnormal returns in the Milan Comit General and the S&P/TSX Composite Index. In addition, the RSI(14,30/70 rule is also profitable in the Dow Jones Industrials Index. The results shed some light on investors’ belief in these two technical indicators in different developed markets.

Revisiting the level scheme of the proton emitter 151Lu

International Nuclear Information System (INIS)

Wang, F.; Sun, B.H.; Liu, Z.; Scholey, C.; Eeckhaudt, S.; Grahn, T.; Greenlees, P.T.; Jones, P.; Julin, R.; Juutinen, S.; Kettelhut, S.; Leino, M.; Nyman, M.; Rahkila, P.; Saren, J.; Sorri, J.; Uusitalo, J.; Ashley, S.F.; Cullen, I.J.; Garnsworthy, A.B.; Gelletly, W.; Jones, G.A.; Pietri, S.; Podolyak, Z.; Steer, S.; Thompson, N.J.; Walker, P.M.; Williams, S.; Bianco, L.; Darby, I.G.; Joss, D.T.; Page, R.D.; Pakarinen, J.; Rigby, S.; Cullen, D.M.; Khan, S.; Kishada, A.; Gomez-Hornillos, M.B.; Simpson, J.; Jenkins, D.G.; Niikura, M.; Seweryniak, D.; Shizuma, Toshiyuki

2015-01-01

An experiment aiming to search for new isomers in the region of proton emitter 151 Lu was performed at the Accelerator Laboratory of the University of Jyväskylä (JYFL), by combining the high resolution γ-ray array JUROGAM, gas-filled RITU separator and GREAT detectors with the triggerless total data readout acquisition (TDR) system. In this proceeding, we revisit the level scheme of 151 Lu by using the proton-tagging technique. A level scheme consistent with the latest experimental results is obtained, and 3 additional levels are identified at high excitation energies. (author)

The importance of jet bending in gamma-ray AGNs—revisited

Energy Technology Data Exchange (ETDEWEB)

Graham, P. J. [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Tingay, S. J. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA (Australia)

2014-04-01

We investigate the hypothesis that γ-ray-quiet active galactic nuclei (AGNs) have a greater tendency for jet bending than γ-ray-loud AGNs, revisiting the analysis of Tingay et al. We perform a statistical analysis using a large sample of 351 radio-loud AGNs along with γ-ray identifications from the Fermi Large Area Telescope (LAT). Our results show no statistically significant differences in jet-bending properties between γ-ray-loud and γ-ray-quiet populations, indicating that jet bending is not a significant factor for γ-ray detection in AGNs.

Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO2 thin films as efficient electron transport layer

Institute of Scientific and Technical Information of China (English)

Mehdi Ahmadi; Sajjad Rashidi Dafeh; Samaneh Ghazanfarpour; Mohammad Khanzadeh

2017-01-01

We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly (3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester (PCBM).1％ vanadium-doped TiO2 nanoparticles were synthesized via the solvothermal method.Crystalline structure,morphology,and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction,scanning electron microscopy,transmittance electron microscopy,and UV-visible transmission spectrum.The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm.The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm.The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm2 compared with its pure counterpart.In the cells using 60 nm pure and vanadium-doped TiO2 layers,the cell using the doped layer showed much higher efficiency.It is remarkable that the extemal quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.

Simulation of Two-Way Pushdown Automata Revisited

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Robert Glück

2013-09-01

Full Text Available The linear-time simulation of 2-way deterministic pushdown automata (2DPDA by the Cook and Jones constructions is revisited. Following the semantics-based approach by Jones, an interpreter is given which, when extended with random-access memory, performs a linear-time simulation of 2DPDA. The recursive interpreter works without the dump list of the original constructions, which makes Cook's insight into linear-time simulation of exponential-time automata more intuitive and the complexity argument clearer. The simulation is then extended to 2-way nondeterministic pushdown automata (2NPDA to provide for a cubic-time recognition of context-free languages. The time required to run the final construction depends on the degree of nondeterminism. The key mechanism that enables the polynomial-time simulations is the sharing of computations by memoization.

Distractor dwelling, skipping, and revisiting determine target absent performance in difficult visual search

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Gernot Horstmann

2016-08-01

Full Text Available Some targets in visual search are more difficult to find than others. In particular, a target that is similar to the distractors is more difficult to find than a target that is dissimilar to the distractors. Efficiency differences between easy and difficult searches are manifest not only in target-present trials but also in target-absent trials. In fact, even physically identical displays are searched through with different efficiency depending on the searched-for target. Here, we monitored eye movements in search for a target similar to the distractors (difficult search versus a target dissimilar to the distractors (easy search. We aimed to examine three hypotheses concerning the causes of differential search efficiencies in target-absent trials: (a distractor dwelling (b distractor skipping, and (c distractor revisiting. Reaction times increased with target similarity which is consistent with existing theories and replicates earlier results. Eye movement data indicated guidance in target trials, even though search was very slow. Dwelling, skipping, and revisiting contributed to low search efficiency in difficult search, with dwelling being the strongest factor. It is argued that differences in dwell time account for a large amount of total search time differences.