Phase-controlled preparation of iron (oxyhydr)oxide nanocrystallines for heavy metal removal

Obtaining cost-effective iron (oxyhydr)oxide nanocrystallines is the essential prerequisite for their future extensive applications in environmental remediation, such as the removal of heavy metals from contaminated waters. Here, various phases of iron (oxyhydr)oxide nanocrystallines were simply synthesized from the phase-controlled transformation of amorphous hydrous ferric- or ferrous-oxide in thermal solution with a certain ethanol/water ratio and with the presence of oleic acid. According to this method, goethite nanorods in diameter of 3–4 nm, hematite nanocubes sized 20–30 nm, and magnetite nanoparticles in diameter of 6–7 nm were successfully obtained. The final products of this transformation can be conveniently controlled by adjusting the reaction parameters, such as pH, temperature, and ethanol/water ratio. Due to the enhanced specific surface area and probably the modifications of the surface structure of nanocrystallines, the as-synthesized goethite nanorods and magnetite nanoparticles demonstrated extremely strong As(III) affinity, with 5.8 and 54 times of As(III) adsorption, respectively, higher than the micron-sized relatives. The cost-effective feature of as-synthesized nanocrystallines and their remarkably enhanced affinity toward arsenic made them potentially applicable for the removal of arsenic and such like heavy metals from the contaminated environment.     

One-pot synthesis of 1,2,3-triazole linked dihydropyrimidinones via Huisgen 1,3-dipolar/Biginelli cycloaddition

The combination of the Biginelli reaction with click chemistry has been used for the one-pot synthesis of 1,2,3-triazole linked dihydropyrimidinones from azides, aromatic aldehydes containing a propargyl ether group, urea, and 1,3-dicarbonyl compounds using Cu(OAc)₂/sodium ascorbate as catalyst in acetic acid under mild reaction conditions.     

An example of dynamically induced coherent states

We consider an example where coherent states appear naturally (dynamically). We study the interaction between an arbitrary quantized matter with a quantized electromagnetic field. Using an approximation that is similar to the Hartree–Fock one and a variational principle, we demonstrate that the electromagnetic field is created by the charged matter exactly in Glauber coherent states with parameters determined by mean currents of the matter.     

Iron–cobalt nanocrystalline alloy supported on a cubic mesostructured silica matrix: FeCo/SBA-16 porous nanocomposites

A series of novel nanocomposites constituted of FeCo nanoparticles dispersed in an ordered cubic Im3m mesoporous silica matrix (SBA-16) have been successfully synthesized using the wet impregnation method. SBA-16, prepared using the non-ionic Pluronic 127 triblock copolymer as a structure-directing agent, is an excellent support for catalytic nanoparticles because of its peculiar three-dimensional cage-like structure, high surface area, thick walls, and high thermal stability. Low-angle X-ray diffraction, N₂ physisorption, and transmission electron microscopy analyses show that after metal loading, calcination at 500 °C, and reduction in H₂ flux at 800 °C, the nanocomposites retain the well-ordered structure of the matrix with cubic symmetry of pores. FeCo alloy nanoparticles with spherical shape and narrow size distribution (4–8 nm) are homogeneoulsy distributed throughout the matrix and they seem in a large extent to be allocated inside the pores.     

Synthesis and characterization of Ag-doped p-type ZnO nanowires

P-type ZnO nanowires with silver (Ag) doping were synthesized via a chemical vapor deposition process. The incorporation of Ag was confirmed by selected-area energy-dispersive x-ray spectroscopy. The formation of acceptor states was demonstrated by temperature and excitation power-dependent photoluminescence measurements. Characterization of field-effect transistors using Ag-doped ZnO nanowires as channels showed p-type conductivity of the nanowires with a hole concentration of 4.9×10¹⁷ cm⁻³ and a carrier mobility of approximately 0.18 cm² V⁻¹ s⁻¹.     

Magnesium nanoparticles with transition metal decoration for hydrogen storage

We report on the hydrogen storage behaviour of Mg nanoparticles (NPs) (size range 100 nm–1 μm) with metal-oxide core–shell morphology synthesized by inert gas condensation and decorated by transition metal (TM) (Pd or Ti) clusters via in situ vacuum deposition. The structure and morphology of the as-prepared and hydrogenated NPs is studied by electron microscopy, X-ray diffraction including in situ experiments and X-ray absorption spectroscopy, in order to investigate the relationships with the hydrogen storage kinetics measured by the volumetric Sieverts method. With both Pd and Ti, the decoration deeply improves the hydrogen sorption properties: previously inert NPs exhibit complete hydrogenation with fast transformation kinetics, good stability and reversible gravimetric capacity that can attain 6 wt%. In the case of Pd-decoration, the occurrence of Mg–Pd alloying is observed at high temperatures and in dependence of the hydrogen pressure conditions. These structural transformations modify both the kinetics and thermodynamics of hydride formation, while Ti-decoration has an effect only on the kinetics. The experimental results are discussed in relation with key issues such as the amount of decoration, the heat of mixing between TM and Mg and the binding energy between TM and hydrogen.     

Investigation of Δ(3,3) resonance effects on the properties of neutron-rich double magic spherical finite nucleus, <Superscript>132</Superscript>Sn,in the ground state and under compression

Within the framework of the radially constrained spherical Hartree–Fock (CSHF) approximation, the resonance effects of delta on the properties of neutron-rich double magic spherical nucleus ¹³²Sn were studied. It was found that most of the increase in the nuclear energy generated under compression was used to create massive Δ particles. For ¹³²Sn nucleus under compression at 3.19 times density of the normal nuclear density, the excited nucleons to Δs were increased sharply up to 16% of the total number of constituents. This result is consistent with the values extracted from relativistic heavy-ion collisions. The single particle energy levels were calculated and their behaviours under compression were examined. A meaningful agreement was obtained between the results with effective Hamiltonian and that with the phenomenological shell model for the low-lying single-particle spectra. The results suggest considerable reduction in compressibility for the nucleus, and softening of the equation of state with the inclusion of Δs in the nuclear dynamics.     

Evaluating Quasilocal Energy and Solving Optimal Embedding Equation at Null Infinity

We study the limit of quasilocal energy defined in Wang and Yau (Phys Rev Lett 102(2):021101, 2009; Commun Math Phys 288(3):919–942, 2009) for a family of spacelike 2-surfaces approaching null infinity of an asymptotically flat spacetime. It is shown that Lorentzian symmetry is recovered and an energy-momentum 4-vector is obtained. In particular, the result is consistent with the Bondi–Sachs energy-momentum at a retarded time. The quasilocal mass in Wang and Yau (Phys Rev Lett 102(2):021101, 2009; Commun Math Phys 288(3):919–942, 2009) is defined by minimizing quasilocal energy among admissible isometric embeddings and observers. The solvability of the Euler-Lagrange equation for this variational problem is also discussed in both the asymptotically flat and asymptotically null cases. Assuming analyticity, the equation can be solved and the solution is locally minimizing in all orders. In particular, this produces an optimal reference hypersurface in the Minkowski space for the spatial or null exterior region of an asymptotically flat spacetime.     

Journal information flow in nanotechnology

The nanotechnology development is accompanied by an intensive growth of information flow which is specially noticeable as applied to journal information flow. Now over the world there are the 69 nano-titled journals with the impact factor and/or a settled periodicity as well as the 70 those which lack stability periodicity and are in an organization stage. Only 49 nano-titled have the impact factor with the comparatively high mean value of about 3.44. The domestic nano-titled journals published in Russia, India, China, and other countries are also considered. The attention is taken that in the 2006–2010 period the 95 new nano-titled journals were organized and in 2011 this process is continuing and seems to be the most impressive. Many nano-related journals (including classical physical, chemical and materials science ones) are also described and discussed.     

TEM characterization of chemically synthesized copper–gold nanoparticles

Dodecanethiol-capped Cu–Au nanoparticles, synthesized via a successive two-phase (water/toluene) and galvanic-exchange procedure, were characterized using transmission electron microscopy (TEM). The size range of the particles is around 1–7 nm. Electron-induced morphological evolution was observed under high resolution (HR) TEM. Cuboctahedral morphology was found to be thermodynamically stable. Electron-induced aggregation of two particles was also observed. Chemical ordering of cuboctahedral particles was studied by atomic-resolution high angle annular dark field (HAADF) imaging in scanning TEM (STEM) mode and energy dispersive X-ray (EDX) element mapping using a silicon drift detector (SDD). The particles were found to be Cu–Au mixed, and to be stable in air. Surface plasmon resonance (SPR), which is dependent on local structure and morphology, was investigated by electron energy loss spectroscopy (EELS).