Tuesday, August 31, 2010

Learn the Science Behind Glow Sticks by Making Your Own [DIY]

Learn the Science Behind Glow Sticks by Making Your Own [DIY]: "

It doesn't matter how old you are, glow sticks are always cool, and the science behind them is even cooler. DIY web site Instructables show us how to make our own. More »






"

Template-Free and Direct Electrochemical Deposition of Hierarchical Dendritic Gold Microstructures: Growth and Their Multiple Applications

Template-Free and Direct Electrochemical Deposition of Hierarchical Dendritic Gold Microstructures: Growth and Their Multiple Applications: "The Journal of Physical Chemistry C, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

Sunday, August 22, 2010

Thermal and optical properties of tellurite glasses doped erbium

Thermal and optical properties of tellurite glasses doped erbium: "

Abstract  
Er3+-doped tellurite glasses with molar compositions of 75TeO2–20ZnO–(5 − x) Na2O–xEr2O3 (x = 0, 0.5, 1, 2, 3, and 4 mol%) have been elaborated from the melt-quenching method. The effects of Er2O3 concentration on the thermal stability and optical properties of tellurite glasses have been discussed. From the differential
scanning calorimetry (DSC) profile, the glass transition temperature T
g, and crystallization onset temperature T
x are estimated. The thermal stability factor, defined as ∆T = T
x − T
g, was higher than 100 °C. It suggests that tellurite glass exhibits a good thermal stability and consequently is suitable
to be a potential candidate for fiber drawing. Furthermore, the stability factor increases with Er2O3 concentration up to 2 mol% then presents a continue decrease suggesting of beginning of crystallization of highly doped tellurite
glasses. The refractive index and extinction coefficient data were obtained by analyzing the experimental spectra of tanΨ
and cos∆ measured by spectroscopic ellipsometry (SE). The complex dielectric functions (ε = ε1 + iε2) of the samples were estimated from regression analysis. The fundamental absorption edge has been identified from the optical
absorption spectra and was analyzed in terms of the theory proposed by Davis and Mott. The values of optical band gap for
direct and indirect allowed transitions have been determined. An important decrease of the optical band gap was found after
Er doping. It was assigned to structural changes induced from the formation of non-bridging oxygen. The absorption coefficient
just below the absorption edge varies exponentially with photon energy indicating the presence of Urbach’s tail. The origin
of the Urbach energy is associated with the phonon-assisted indirect transitions.

  • Content Type Journal Article
  • DOI 10.1007/s10853-010-4820-x
  • Authors
    • I. Jlassi, Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif, 2050 Tunisia
    • H. Elhouichet, Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif, 2050 Tunisia
    • M. Ferid, Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif, 2050 Tunisia
"

A green method for synthesis of silver nanodendrites

A green method for synthesis of silver nanodendrites: "

Abstract  
A simple, green method was developed for the synthesis of silver nanodendrites by an aqueous chemical route. This method involves
the reduction of silver nitrate with absolute alcohol using polyvinyl pyrrolidone (PVP) as the surfactant. UV–vis absorption
spectra, X-ray diffraction patterns (XRD) and energy dispersive spectrometry (EDS) suggest the formation of Ag nanoparticles.
Transmission electron microscopy (TEM) images show the shape and sizes of the nanoparticles. During the synthesis, it was
found that the morphology and size distribution of the as-prepared silver nanoparticles varied with the concentration of the
precursor metal salts, reaction time and surfactant ratios. The formation mechanism of Ag nanodendrites was determined based
on the investigation of the above reaction parameters. Simple methods, nontoxic chemicals and environmentally benign solvents
make this synthesis ideally suited for industrial production.

  • Content Type Journal Article
  • DOI 10.1007/s10853-010-4826-4
  • Authors
    • Lei Sun, Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng, 475004 People’s Republic of China
    • Aixin Liu, Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng, 475004 People’s Republic of China
    • Xiaojun Tao, Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng, 475004 People’s Republic of China
    • Yanbao Zhao, Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng, 475004 People’s Republic of China
"

Tuesday, August 17, 2010

Dipicolinate Sensitization of Europium Luminescence in Dispersible 5%Eu:LaF3 Nanoparticles

Dipicolinate Sensitization of Europium Luminescence in Dispersible 5%Eu:LaF3 Nanoparticles: "The Journal of Physical Chemistry C, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

A “Neck-Formation” Strategy for an Antiquenching Magnetic/Upconversion Fluorescent Bimodal Cancer Probe

A “Neck-Formation” Strategy for an Antiquenching Magnetic/Upconversion Fluorescent Bimodal Cancer Probe: "Thumbnail image of graphical abstract

Up to the neck! Bio-safe upconversion fluorescent nanocrystals (NaYF4: Er,Yb) and biocompatible superparamagnetic iron oxide nanocrystals (SPION) were effectively combined by means of a general “neck-formation” strategy, forming a size-controlled, Cd2+- and Gd3+-free, silica-shielded, magnetic upconversion fluorescent oligomer (SMUFO), bimodal cancer probe that offers high resistance to photoquenching as well as a synergistic T2-weighted magnetic resonance enhanced effect (see graphic).

"

Friday, August 06, 2010

Controllable growth of silver-seeded PbS nanostructures

Controllable growth of silver-seeded PbS nanostructures: "

Abstract  
A surfactant-assisted colloidal chemistry technique for the controllable growth of various PbS architectural nanostructures
catalyzed by Ag nanocrystal seeds was reported. The sizes and morphologies of the obtained PbS nanostructures were dependent
on the amount of Ag nanocrystal seeds and the ratio of Pb to S precursors. By varying the amount of Ag seed, sphere-, cube-
and rod-shaped PbS nanostructures were obtained; while the morphologies changed from nano-scaled sphere to small cube and
then to large truncated-cube when decreasing the precursors’ ratio of Pb to S from 5:1 to 2:1 and then to 1:2 with the fixation
of the amount of Ag seed. Control of morphology under different conditions has been systematically studied and the mechanism
of morphology formation was also primarily discussed.

  • Content Type Journal Article
  • DOI 10.1007/s10853-010-4789-5
  • Authors
    • Yan Li, East China University of Science and Technology Key Laboratory for Advanced Materials Research, Department of Chemistry 200237 Shanghai China
    • Feifei Du, East China University of Science and Technology Key Laboratory for Advanced Materials Research, Department of Chemistry 200237 Shanghai China
    • Hua Zhang, East China University of Science and Technology Key Laboratory for Advanced Materials Research, Department of Chemistry 200237 Shanghai China
    • Xiling Du, Tongji University School of Life Science and Technology 200092 Shanghai China
    • Jian Zhu, Tongji University School of Life Science and Technology 200092 Shanghai China
    • Xinhua Zhong, East China University of Science and Technology Key Laboratory for Advanced Materials Research, Department of Chemistry 200237 Shanghai China
"

Thursday, August 05, 2010

Core−Shell Nanoarchitectures: A Strategy To Improve the Efficiency of Luminescence Resonance Energy Transfer

Core−Shell Nanoarchitectures: A Strategy To Improve the Efficiency of Luminescence Resonance Energy Transfer: "ACS Nano, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

Magnetite hollow spheres: solution synthesis, phase formation and magnetic property

Magnetite hollow spheres: solution synthesis, phase formation and magnetic property: "

Abstract  
Polycrystalline magnetite hollow spheres with diameter of about 200 nm and shell thickness of 30–60 nm were prepared via a
facile solution route. For the reaction, ethylene glycol (EG) served as the reducing agent and soldium acetate played the
role of precipitator. In addition, polyvinylpyrrolidone (PVP) served as a surface stabilizer. The morphologies and structures
were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The intermediate
products at different stages were also studied to shed light on the evolution of phase formation. It revealed that the hollow
structure formed via self-assembly of nanocrystallites (about 15 nm) using sodium acetate as mild precipitator. Evidences
further pointed out that the Ostwald ripening process well explained the growth mechanism of the hollow structure. Magnetization
measurements showed that the coercivity of magnetite hollow spheres at low temperature is about 200 Oe and the saturation
magnetization is about 83 emu g−1, roughly 85% that of the bulk phase, close to the value of its solid counterpart. In addition, a freezing transition was
observed at 25 K.

  • Content Type Journal Article
  • Category Research Paper
  • DOI 10.1007/s11051-010-0020-5
  • Authors
    • Qian Sun, Beijing University of Aeronautics and Astronautics Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Department of Physics Beijing 100191 People’s Republic of China
    • Zheng Ren, Beijing University of Aeronautics and Astronautics Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Department of Physics Beijing 100191 People’s Republic of China
    • Rongming Wang, Beijing University of Aeronautics and Astronautics Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Department of Physics Beijing 100191 People’s Republic of China
    • Weimeng Chen, Peking University Department of Physics Beijing 100871 People’s Republic of China
    • Chinping Chen, Peking University Department of Physics Beijing 100871 People’s Republic of China
"

Tuesday, August 03, 2010

CdS Hierarchical Nanostructures with Tunable Morphologies: Preparation and Photocatalytic Properties

CdS Hierarchical Nanostructures with Tunable Morphologies: Preparation and Photocatalytic Properties: "The Journal of Physical Chemistry C, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

Controllable Synthesis and Size-Dependent Luminescent Properties of YVO4:Eu3+ Nanospheres and Microspheres

Controllable Synthesis and Size-Dependent Luminescent Properties of YVO4:Eu3+ Nanospheres and Microspheres: "The Journal of Physical Chemistry C, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

Controllable Self-Assembly of PbS Nanostars into Ordered Structures: Close-Packed Arrays and Patterned Arrays

Controllable Self-Assembly of PbS Nanostars into Ordered Structures: Close-Packed Arrays and Patterned Arrays: "ACS Nano, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

Fabrication of hierarchical CdS microspheres assembled by nanowires: solid state electro-chemiluminescence in H2O2 solution

Fabrication of hierarchical CdS microspheres assembled by nanowires: solid state electro-chemiluminescence in H2O2 solution: "

Abstract  
Hierarchical CdS microspheres self-assembled by nanowires were synthesized via an ethylenediamine tetraacetate assisted solvothermal
approach using cadmium chloride and l-cysteine as reaction agents. The phase structure, morphology, and optical properties of the products were investigated by
X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and electro-chemiluminescence, respectively.
Studies showed that the final morphology of the products was strongly influenced by the concentration of ethylenediamine tetraacetate
and reaction temperature. The as-prepared hierarchical CdS spheres could be a good candidate for a detective technology due
to its high electro-chemiluminescence intensity.

  • Content Type Journal Article
  • DOI 10.1007/s10853-010-4778-8
  • Authors
    • Zhen Fang, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
    • Xiu Lin, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
    • Yufeng Liu, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
    • Yueting Fan, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
    • Yinggui Zhu, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
    • Yonghong Ni, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
    • Xianwen Wei, Anhui Normal University Anhui Key Laboratory of Functional Molecular Solids and College of Chemistry and Materials Science Wuhu 241000 People’s Republic of China
"

Growth kinetics and long-term stability of CdS nanoparticles in aqueous solution under ambient conditions

Growth kinetics and long-term stability of CdS nanoparticles in aqueous solution under ambient conditions: "

Abstract  
The ubiquity of naturally occurring nanoparticles in the aquatic environment is now widely accepted, but a better understanding
of the conditions that promote their formation and persistence is needed. Using cadmium sulfide (CdS) as a model metal sulfide
species, thiolate-capped CdS nanoparticles were prepared in the laboratory to evaluate how aquatic conditions influence metal
sulfide nanoparticle growth and stability. This work examines CdS nanoparticle growth directly in aqueous solution at room
temperature by utilizing the size-dependent spectroscopic properties of semiconductors detectable by UV/vis. CdS nanoparticle
growth was governed by oriented attachment, a non-classical mechanism of crystallization in which small precursor nanoparticles
coalesce to form larger nanoparticle products. Nanoparticle growth was slowed with increasing capping agent and decreasing
ionic strength. In addition to examining the short-term (hours) growth of the nanoparticles, a long-term study was conducted
in which cysteine-capped CdS nanoparticles were monitored over 3 weeks in solutions of various ionic strengths. The long-term
study revealed an apparent shift from small nanoparticles to nanoparticles twice their original size, suggesting nanoparticle
growth may continue through oriented attachment over longer time scales. High-ionic strength solutions resulted in salt-induced
aggregation and eventual settling of nanoparticles within days, whereas low-ionic strength solutions were stable against settling
over the course of the experiment. Sulfide recovery from cysteine-capped CdS nanoparticles as acid volatile sulfide was nearly
quantitative after 2 weeks in fully oxygenated water, demonstrating significantly slowed oxidation of sulfide when complexed
to Cd(II) within CdS nanoparticles. The nanoparticles were also shown to be resistant to oxidation by Fe(III) (hydr)oxide.
This study illustrates that aggregation, rather than chemical oxidation, is likely more important to the lifetime of many
metal sulfide nanoparticles in the aquatic environment.

  • Content Type Journal Article
  • Category Research Paper
  • DOI 10.1007/s11051-010-0045-9
  • Authors
    • Katherine M. Mullaugh, University of North Carolina Wilmington Wilmington NC 28403 USA
    • George W. Luther, University of Delaware Department of Chemistry and Biochemistry Newark DE 19716 USA
"

Fabrication of rare-earth/quantum-dot nanocomposites for color-tunable sensing applications

Fabrication of rare-earth/quantum-dot nanocomposites for color-tunable sensing applications: "

Abstract  
We developed a new fluorescent nanocomposite by using a layer-by-layer approach to link NaYF4:Ce,Tb rare-earth (RE) nanocrystals and CdSe/ZnSe semiconductor quantum dots (QDs) with opposite charges. Under ultraviolet
light excitation, the nanocomposites exhibited both the green Tb emission centered at 550 nm, and the red QD emission at 650 nm.
Sensing applications showed that the red QD emission was quenched by trace amount of Cu2+ (or Ag+) ions due to the ion displacement mechanism, while the green RE emission kept constant. Thus, the nanocomposites with the
decreased QD/RE emission intensity ratio and changed fluorescence output color provided a visible “indicator” to detect metal
ions quantificationally. In comparison with single emission materials, the dual emission nanocomposites can be a more reliable
probe for various sensing applications.

  • Content Type Journal Article
  • Category Research Paper
  • DOI 10.1007/s11051-010-0042-z
  • Authors
    • Yang Xiang, Wuhan University Department of Physics, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology 430072 Wuhan People’s Republic of China
    • Xu-Yang Xu, Wuhan University Department of Physics, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology 430072 Wuhan People’s Republic of China
    • Ding-Fei He, Wuhan University Department of Physics, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology 430072 Wuhan People’s Republic of China
    • Min Li, Wuhan University Department of Physics, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology 430072 Wuhan People’s Republic of China
    • Liang-Bo Liang, Wuhan University Department of Physics, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology 430072 Wuhan People’s Republic of China
    • Xue-Feng Yu, Wuhan University Department of Physics, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology 430072 Wuhan People’s Republic of China
"

Fe2O3@BaTiO3 Core−Shell Particles as Reactive Precursors for the Preparation of Multifunctional Composites Containing Different Magnetic Phases

Fe2O3@BaTiO3 Core−Shell Particles as Reactive Precursors for the Preparation of Multifunctional Composites Containing Different Magnetic Phases: "Chemistry of Materials, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."

Large-Scale Aqueous Synthesis and Growth Mechanism of Single-Crystalline Metal Nanoscrolls at Room Temperature: The Case of Nickel

Large-Scale Aqueous Synthesis and Growth Mechanism of Single-Crystalline Metal Nanoscrolls at Room Temperature: The Case of Nickel: "Chemistry of Materials, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable)."