Synthesis, structures, and magnetic behavior of a series of copper(II) azide polymers of Cu4 building clusters and isolation of a new hemiaminal ether as the metal complex

Four new neutral copper azido polymers, [Cu(4)(N(3))(8)(L(1))(2)](n) (1), [Cu(4)(N(3))(8)(L(2))(2)](n) (2), [Cu(4)(N(3))(8)(L(3))(2)](n) (3), and [Cu(9)(N(3))(18)(L(4))(4)](n) (4) [L(1-4) are formed in situ by reacting pyridine-2-carboxaldehyde with 2-[2-(methylamino)ethyl]pyridine (mapy, L(1)), N,N-dimethylethylenediamine (N,N-dmen, L(2)), N,N-diethylethylenediamine (N,N-deen, L(3)), and N,N,2,2-tetramethylpropanediamine (N,N,2,2-tmpn, L(4))], have been synthesized by using 0.5 mol equiv of the chelating tridentate ligands with Cu(NO(3))(2)·3H(2)O and an excess of NaN(3). Single-crystal X-ray structures show that the basic unit of these complexes, especially 1-3, contains very similar Cu(II)(4) building blocks. The overall structure of 3 is two-dimensional, while the other three complexes are one-dimensional in nature. Complex 1 represents a unique example containing hemiaminal ether arrested by copper(II). Complexes 1 and 2 have a rare bridging azido pathway: both end-on and end-to-end bridging azides between a pair of Cu(II) centers. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in all four complexes. Density functional theory calculations (B3LYP functional) have been performed on complexes 1-3 to provide a qualitative theoretical interpretation of their overall ferromagnetic behavior.     

Synthesis of BF2 complexes of prodigiosin type oligopyrroles

We developed a simple, facile route for the synthesis of BF(2) complexes of prodigiosin type oligopyrroles and their cholesterol conjugates. This route gives an access to synthesize any desired meso-aryl-substituted 3-pyrrolyl BODIPYs which were not easily accessible earlier.     

UV-Vis, fluorescence and NMR spectroscopic investigations on inclusion properties of a designed tetrahomocalix[8]arene with fullerenes C60 and C70 in solution

The present article reports the spectroscopic investigations on non-covalent interaction of fullerenes C(60) and C(70) with a macrocyclic receptor molecule, namely, 1,3,5,7-tetrahomo-p-tert-butylcalix[8]arene (1) in toluene. Jobs method of continuous variation reveals 1:1 stoichiometry for the fullerene complexes of 1. The most fascinating feature of the present study is that 1 binds selectively C(60) compared to C(70) as obtained from binding constant (K) data of C(60)-1 (K(C60-1)) and C(70)-1 (K(C70-1)) complexes which are enumerated to be 265,000 dm(3) mol(-1) and 63,43 dm(3) mol(-1), respectively, and selectivity in binding (K(C60-1)/K(C70-1)) is estimated to be 4.18 as obtained from UV-Vis study. Steady state fluorescence studies reveal quenching of fluorescence of 1 in presence of fullerenes and the K value of the C(60)-1 and C(70)-1 complexes are estimated to be 80,760 and 68,780 dm(3) mol(-1), respectively, with selectivity in binding (K(C60-1)/K(C70-1)) ~1.18. (1)H NMR analysis provides very good support in favor of strong binding between C(60) and 1. The high value of K value for C(60)-1 complex indicates that 1 forms an inclusion complex with C(60).     

Synthesis and DNA binding studies of Ni(II), Co(II), Cu(II) and Zn(II) metal complexes of N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone Schiff-base ligand

The thiocarbohydrazone Schiff-base ligand with a nitrogen and sulphur donor was synthesized through condensation of pyridine-2-carbaldehyde and thiocarbohydrazide. Schiff-base ligands have the ability to conjugate with metal salts. A series of metal complexes with a general formula [MCl2(H2L)]·nH2O (MNi, Co, Cu and Zn) were synthesized by forming complexes of the N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone (H2L) Schiff-base ligand. These metal complexes and ligand were characterized by using ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FT-IR), 1H and 13C NMR spectroscopy and mass spectroscopy, physicochemical characterization, CHNS and conductivity. The biological activity of the synthesized ligand was investigated by using Escherichia coli DNA as target. The DNA interaction of the synthesized ligand and complexes on E. coli plasmid DNA was investigated in the aqueous medium by UV-Vis spectroscopy and the binding constant (Kb) was calculated. The DNA binding studies showed that the metal complexes had an improved interaction due to trans-geometrical isomers of the complexes than ligand isomers in cis-positions.     

Identification of Interaction Pressure Between Structure and Explosive with Inverse Approach

An inverse approach for the identification of the time-dependent localized interaction pressure between a structure and an explosive has been proposed and developed. In this approach, surface measurements of structural response (displacement and velocity) are integrated with numerical simulations to identify the spatial and time-dependent interaction pressure (i.e. the normal traction) on a structure surface. For verification and validation purposes, numerical simulations are used to (a) generate the time-dependent displacement and velocity fields on the free surface of the specimen at specified time intervals, (b) form a blast wave and compute the resulting interaction traction field between the structure and blast wave on the interaction interface for comparison to inverse predictions. In particular, validation of the proposed approach was performed using numerical simulation results for an underwater explosion, with excellent agreement between the identified interaction traction and the simulation generated interaction traction up to and including the maximum traction condition. To demonstrate the potential of the method, the proposed inverse procedure was employed to estimate the interaction traction field on a thin aluminum specimen subjected to transient pressure loading through detonation of explosive buried in sand.     

Experimental investigation into vortex structure and pressure drop across microcavities in 3D integrated electronics

Hydrodynamics in microcavities with cylindrical micropin fin arrays simulating a single layer of a water-cooled electronic chip stack is investigated experimentally. Both inline and staggered pin arrangements are investigated using pressure drop and microparticle image velocimetry (μPIV) measurements. The pressure drop across the cavity shows a flow transition at pin diameter–based Reynolds numbers (Re _d ) ~200. Instantaneous μPIV, performed using a pH-controlled high seeding density of tracer microspheres, helps visualize vortex structure unreported till date in microscale geometries. The post-transition flow field shows vortex shedding and flow impingement onto the pins explaining the pressure drop increase. The flow fluctuations start at the chip outlet and shift upstream with increasing Re _d . No fluctuations are observed for a cavity with pin height-to-diameter ratio h/d = 1 up to Re _d ~330; however, its pressure drop was higher than for a cavity with h/d = 2 due to pronounced influence of cavity walls.     

Performance limit for base-excited energy harvesting,and comparison with experiments

Nonlinear Dynamics - We consider the theoretical maximum extractable average power from an energy harvesting device attached to a vibrating table which provides a unidirectional displacement...     

Can trimethylamine-N-oxide act to influence the self-aggregation of tert-butyl alcohol?

We report classical molecular dynamics simulation studies of aqueous solution consisting of water, tert-butyl alcohol (TBA) and trimethylamine-N-oxide (TMAO). In spite of the fact that both TBA and TMAO molecules have very similar geometry with hydrophobic and hydrophilic groups, they behave very differently in aqueous solutions. Our aim is to see the role of TMAO on the self-aggregation (or association) of TBA molecules. We observe that, TMAO acts to postpone the aggregation of TBA molecules (takes place via the hydrophobic ends) to some extent. Addition of 0.10 mole fraction of TMAO shifts the aggregation concentration of TBA from x_tba = 0.025 to x_tba = 0.06. From the excess coordination number, calculation it is noticed that up to x_tba = 0.06, TBA molecules are favourably solvated by TMAO by replacing water molecules from TBA solvation shell but above this concentration, TBA–TMAO interaction decreases. This is further confirmed by water–TMAO interactions which shows a shift above x_tba = 0.06 indicating more preferred interactions between them. We also observe a noticeable increase in the water–water hydrogen bond life time in presence of TBA molecules indicating more structuring of water molecules.     

Hilbert Space Methods in Quantum Mechanics,by Werner O. Amrein

This article, which is in two parts, surveys the wide application of scattering experiments to studies of the structures of solids and liquids. Part 1 outlines the general principles, and shows how the angular distribution of a scattered radiation is related by Fourier transform to correlations in the distributions of electrons and nuclei in the scattering target, citing the use of X-rays and of neutrons in determining time-averaged density distributions. Part 2 (to appear in the next issue) discusses the time-dependent aspects of the distributions for solids and liquids, including superfluid helium, and also of dynamical distributions of magnetization (or angular momentum) density, and examines the present limitations and future possibilities of scattering experiments.     

Investigation of optimum pulse shape for 112 Gbps DP-DQPSK in DWDM transmission

This paper reports the simulative analyses to investigate the impact of different pulse shapes on DP-DQPSK modulation for high-spectral efficient DWDM transmission at 112 Gbps per channel. In the simulation model we have considered three different pulse shapes viz. NRZ, 50% duty cycle RZ (RZ50) and 67% duty cycle RZ (RZ67) in symbol-aligned and symbol-interleaved format. The analysis has been carried out for various linear and nonlinear system impairments where the pulse is subjected to degradation under the influence of amplified spontaneous emission (ASE) noise, group velocity dispersion (GVD), cross-phase modulation (XPM) and polarization mode dispersion (PMD) and thus, limiting the system performance. Results show that the RZ50 pulse shape for DP-DQPSK with symbol interleaving shows the maximum tolerance for the various system degradations in long haul DWDM transmission. Even the system based on the NRZ pulse shape can gain significant improvement from the symbol-interleaving.