Synthesis, molecular modeling and spectroscopic characterization of nickel(II), copper(II), complexes of new 16-membered mixed-donor macrocyclic schiff base ligand incorporating a pendant alcohol function

Complexes of Cu(II) and Ni(II) of the composition [M(L)X] [where M=Ni(II), Cu(II) and X=Cl-, NO3-, CH3COO-] were synthesized with 1,5-dioxo-9,10-diaza-3,ol-tribenzo-(7,6,10,11,14,15) peptadecane, a N2O2 macrocyclic ligand. The complexes were characterized by elemental analysis, molar conductance measurements, UV-vis, IR, 1H NMR, 13C NMR, EPR and molecular modeling studies. All the complexes are non-electrolyte in nature. On the basis of spectral studies, an octahedral geometry has been assigned for Ni(II) complexes and a tetragonal geometry for Cu(II) complexes.     

Evaluation of Quantitative Sulfur Speciation in Gas Oils by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Validation by Comprehensive Two-Dimensional Gas Chromatography

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been applied for the quantitative speciation of sulfur containing compounds in gas oil (GO). For this purpose, ionization and mass spectrometric parameters have been studied and optimized with a set of standard compounds and GO samples. Comprehensive two-dimensional gas chromatography (GCxGC) was used as the reference method. To allow a quantitative comparison between FT-ICR MS and GCxGC results for GO samples, FT-ICR MS parameters were optimized and data obtained by both techniques were standardized. Response factors were established for two ionization modes: atmospheric pressure photo ionization (APPI) and electrospray after selective derivatization of sulfur compounds (MeESI). To test the validity of the developed MS methods, a third GO was analyzed and response factors were applied. Comparison with GCxGC results showed good agreement for sulfur families (deviation within 5% and 15% for MeESI and APPI data, respectively). Abundances of individual isomer groups match within 40% in most cases. These results principally demonstrate the suitability of FT-ICR MS for a quantitative analysis of sulfur compounds (by DBE and carbon number distribution pattern) in petroleum middle distillates. This approach has the potential to be extended to higher- and non-boiling petroleum fractions where quantitative speciation is presently not available.     

Gold–sulfur bond breaking in Zn(II) tetraphenylporphyrin molecular junctions

Quantized conductance measured from single tetraphenylporphyrin molecules with and without a central zinc(II) [Zn(II)] atom was measured using a molecular break junction (MBJ) method. From the conductance histograms we observed an additional 1.7 Å stretch for two-state conductance in a single Zn(II) tetraphenylporphyrin (ZnTPP) molecule as compared to single state conductance in a free tetraphenylporphyrin (TPP) molecule, i.e., no central Zn(II) atom. First-principles density functional calculations, using an electrode–molecule–electrode model, are completed to provide insight into the mechanisms attributed to bond stretching, and eventual bond breaking, to better understand the additional 1.7 Å of stretching observed with ZnTPP.     

Effects of seasonal growth on delayed prey–predator model

The dynamic behavior of a delayed predator–prey system with Holling II functional response is investigated. The stability analysis has been carried out and existence of Hopf bifurcation has been established. The complex dynamic behavior due to time delay has been explored. The effects of seasonal growth on the complex dynamics have been simulated. The model shows a rich variety of behavior, including period doubling, quasi-periodicity, chaos, transient chaos, and windows of periodicity.     

Potential profile near the virtual cathode in presence of charged dust

In this work, concept of virtual cathode and its existence in dusty plasma has been studied by theoretical and numerical analysis. Using basic equations of charge dust, ions, and electrons, the non‐monotonic behaviour of the potential in presence of charged dust has been calculated and plotted as a function of dust density. It has been found that there is a change in potential between cathode and sheath potential and subsequently changes the threshold wall temperature as compared to that of without dust conditions. The threshold wall temperature has been increased due to the ability of micro‐particles acquiring electron charge and hence, reducing potential at the wall. Further, for different values of α (depends on dust density); threshold temperature remained the same for observed virtual cathode. Hence, behaviour of potential has been plotted as a function of α with increasing wall temperatures for two dust charge values (1 and 1,000). Considering no dust charge, it has been observed that, at lower dust density, double layer like structure is formed near the emissive wall. But this double layer structure gets diminishes with increasing dust density. Hence, below a threshold dust density, virtual cathode near to the emissive wall is not possible. While for Z_d = 1,000, the formation of virtual cathode appeared even at very small dust density. However, irrespective of variation of potential difference near the wall and existence of virtual cathode at different emission regime the threshold wall temperature remains same. Effect of dust potential dependency on threshold wall temperature has also been discussed in this study.     

Lattice imaging of radiation-sensitive polymer crystals

The total end-point dose (i.e., the electron irradiation dose necessary for complete destruction of the crystal lattice) was measured at 120 kV and room temperature for poly(ethylene oxide), polyethylene, isotactic polystyrene (i-PS), poly(p-xylylene), ramie and bacterial cellulose, and lobster chitin. On the basis of the results obtained, the possibility of lattice imaging of polymer crystals is discussed. As reported in an earlier preliminary paper, 1.1- and 0.55-nm lattice fringes were resolved in i-PS single crystals by using a conventional transmission electron microscope equipped with a device for low-dose imaging. In this paper, the detailed procedure for lattice imaging of i-PS crystals is described and various features of the lattice images are discussed.     

Formulation and physicochemical characterization of microemulsion system using isopropyl myristate, medium-chain glyceride, polysorbate 80 and water

The phase behavior of the system isopropyl myristate/medium-chain glyceride/polysorbate 80/water forming both w/o and o/w microemulsions has been studied to develop microemulsion comprising of pharmaceutical excipients. The pseudo-ternary phase diagrams with large monophasic zones and gel formation were realized and several compositions were identified in the phase diagram for rheological, dynamic light scattering (DLS) and calorimetric measurements. The identified systems at different temperatures behaved as Newtonian fluid and the activation parameters for their viscous flow were evaluated. From DLS measurements, hydrodynamic diameter, polydispersity and diffusion coefficient of the microheterogeneous dispersions were determined. The free energy, enthalpy and entropy of solution of the w/o and o/w microemulsions were determined from calorimetric measurements.     

Isothermal and non-isothermal crystallization kinetics of PVA + ionic liquid [BDMIM][BF4]-based polymeric films

The effect of ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM][BF₄], on crystallization behavior of poly(vinyl alcohol) (PVA) has been studied by isothermal and non-isothermal differential scanning calorimetry techniques. The PVA + IL based polymer electrolyte films have been prepared using solution casting technique. To describe the isothermal and non-isothermal crystallization kinetics, several kinetic equations have been employed on PVA + IL based films. There is strong dependence of the peak crystallization temperature (T_c), relative degree of crystallity (X_t), half-time of crystallization (t_1/2), crystallization rate constants (Avrami K_t and Tobin A_T), and Avrami (n) and Tobin (n_T) exponents on the cooling rate and IL loading.