Development of one-pot benzylic amination reactions of azine N-oxides

An efficient one-pot synthetic methodology has been developed for the benzylic amination reactions of methyl-substituted azine N-oxides that operate under mild conditions. The reaction was found to tolerate quinoline and isoquinoline N-oxides with electron donating and withdrawing substituents as the electrophilic reaction partners as well as a broad range of nucleophilic primary, secondary and aromatic amines, affording the benzylic amination products in up to 82% yield.     

2-pyrrolidone - capped Mn<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocrystals

Water-soluble Mn₃O₄ nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm. FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn₃O₄ nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction with neighboring particles.      

Microwave-induced combustion synthesis and characterization of NixCo1−xFe2O4 nanocrystals (x = 0.0, 0.4, 0.6, 0.8, 1.0)

A series of Ni-doped cobalt ferrites Ni_xCo1_−xFe₂O₄ (x = 0.0, 0.4, 0.6, 0.8, and 1.0) were prepared using microwave-induced combustion. Nickel, cobalt, and ferric nitrates were used as starting materials and glycine as fuel. The influence of Ni content on the lattice parameter, stretching vibrations, and magnetization was studied. XRD, FTIR, and SEM were used for structure, composition, and morphology investigation. A porous network structure was observed with average particle size 60–67 nm. All samples had a cubic spinel structure. The unit cell parameter “a” decreases linearly with nickel concentration due to the smaller ionic radius of nickel. Magnetization measurements showed that coercivity decreased as Ni content increased; it increased with decreasing temperature.      

Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution with Subnanometer Resolution

We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub‐nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi‐wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band‐gap positions of discrete species present in the CdTe mixture.     

On the Modeling of CO2 EUA and CER Prices of EU‐ETS for the 2008–2012 Period

Increased consumption of fossil fuels in industrial production has led to a significant elevation in the emission of greenhouse gases and to global warming. The most effective international action against global warming is the Kyoto Protocol, which aims to reduce carbon emissions to desired levels in a certain time span. Carbon trading is one of the mechanisms used to achieve the desired reductions. One of the most important implications of carbon trading for industrial systems is the risk of uncertainty about the prices of carbon allowance permits traded in the carbon markets. In this paper, we consider stochastic and time series modeling of carbon market prices and provide estimates of the model parameters involved, based on the European Union emissions trading scheme carbon allowances data obtained for 2008–2012 period. In particular, we consider fractional Brownian motion and autoregressive moving average–generalized autoregressive conditional heteroskedastic modeling of the European Union emissions trading scheme data and provide comparisons with benchmark models. Our analysis reveals evidence for structural changes in the underlying models in the span of the years 2008–2012. Data‐driven methods for identifying possible change‐points in the underlying models are employed, and a detailed analysis is provided. Our analysis indicated change‐points in the European Union Allowance (EUA) prices in the first half of 2009 and in the second half of 2011, whereas in the Certified Emissions Reduction (CER) prices three change‐points have appeared, in the first half of 2009, the middle of 2011, and in the second half of 2012. These change‐points seem to parallel the global economic indicators as well. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis, characterization and magnetic investigation of (NH4)0.5Mn1.25(H2O)2[BP2O8]·0.5H2O

A new borophosphate compound with the composition (NH₄) _χ Mn_((3?χ)/2)(H₂O)₂ [BP₂O₈]·(1?x)H₂O was prepared under mild hydrothermal conditions and characterized by X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) methods. The title compound was synthesized from MnCl₂·2H₂O, H₃BO₃, and (NH₄)₂HPO₄ with variable molar ratios by heating at 180 °C for 7 days in an autoclave. The X-ray diffraction data of the water insoluble polycrystalline powder was indexed using the TREOR program in hexagonal system with the unit cell parameters of a = 9.5104, c = 15.7108 Å, Z = 6 and the space group P6₅ (No.176). (NH₄) _χ Mn_((3?χ)/2)(H₂O)₂ [BP₂O₈]·(1?x)H₂O is isostructural with (NH₄) _χ M _((3?χ) ^2)/II (H₂O)₂ [BP₂O₈]·(1?x)H₂O (M^II = Co, Cd, Mg; x = 0.5–1). Its unit cell parameters and hkl values were in good agreement with the other isostructural compounds. This is the first report presenting both the synthetic details and the indexed X-ray powder diffraction pattern of this compound along with the characterization by FTIR, thermal gravimetric analysis, scanning electron microscopy and EPR.      

A green chemical route for the synthesis of Mn3O4 nanoparticles

A novel environmental friendly, room temperature route using an ionic liquid 1-n-butyl-3-methylimidazolium hydroxide ([BMIM]OH) for the synthesis of Mn₃O₄ nanoparticles is presented. The product was characterized using Fourier transform infrared spectroscopy, X-ray powder diffraction, and transmission electron microscopy. Phase purity was confirmed by XRD, and X-ray line profile fitting determined a crystallite size of 42 ± 11 nm. TEM analysis revealed various morphologies. EPR measurements have indicated the existence of long-range interactions, due to the wide range of particle sizes and morphologies observed.      

Interfacial engineering of CuO nanorod/ZnO nanowire hybrid nanostructure photoanode in dye-sensitized solar cell

Developing efficient and cost-effective photoanode plays a vital role determining the photocurrent and photovoltage in dye-sensitized solar cells (DSSCs). Here, we demonstrate DSSCs that achieve relatively high power conversion efficiencies (PCEs) by using one-dimensional (1D) zinc oxide (ZnO) nanowires and copper (II) oxide (CuO) nanorods hybrid nanostructures. CuO nanorod-based thin films were prepared by hydrothermal method and used as a blocking layer on top of the ZnO nanowires’ layer. The use of 1D ZnO nanowire/CuO nanorod hybrid nanostructures led to an exceptionally high photovoltaic performance of DSSCs with a remarkably high open-circuit voltage (0.764 V), short current density (14.76 mA/cm² under AM1.5G conditions), and relatively high solar to power conversion efficiency (6.18%) . The enhancement of the solar to power conversion efficiency can be explained in terms of the lag effect of the interfacial recombination dynamics of CuO nanorod-blocking layer on ZnO nanowires. This work shows more economically feasible method to bring down the cost of the nano-hybrid cells and promises for the growth of other important materials to further enhance the solar to power conversion efficiency.     

Double Vivaldi antenna for wireless optical networks on chip

In this paper we present a double plasmonic Vivaldi antenna for on-chip optical wireless communication. The proposed antenna is a two-element broadside array fed by a silicon waveguide. The designs of the power splitter and of the hybrid Si-plasmonic coupler used for antenna excitation are described in detail. The array radiation characteristics are optimized through Finite Difference Time Domain simulations and the performance of a point-to-point link is evaluated. The proposed double Vivaldi array increases the gain of 3 dB with respect to a single antenna, improving the received power on a link of 6 dB when the double antenna is used for both transmitting and receiving sections.