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Shiv Nadar University

(SoNS) School of Natural Sciences

We continue the previous study on the existence of different intermediate Hamiltonians in type A N-fold supersymmetric systems and carry out an exhaustive investigation on the N=3 case. In contrast with the N=2 case, we find various patterns in the existence of intermediate Hamiltonians due to the presence of two different intermediate positions in a factorized type A 3-fold supercharge. In addition, all the N=3 models are strictly restricted to at most elliptic type, which enables us to make the complete classification of the systems which admit intermediate Hamiltonians. Finally, we show realizations of third-order parasupersymmetry and variant generalized 3-fold superalgebras by such systems. © 2010 Elsevier Inc.

Physics

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Annals of Physics

Existence of different intermediate Hamiltonians in type A N-fold supersymmetry II. The N=3 case

As NMR Investigation In An Itinerant Ferromagnet PrCoAsO

We study the dynamics of a disease under administration of a vaccine and antiviral drug, where the disease transmits directly from the parents to the offspring (vertical transmission) and also through contact with infective individuals (horizontal transmission). While vaccination to those susceptible reduces the horizontal transmission, administration of the antiviral drug to infected individuals lessens the chance of vertical transmission. Thus the vaccine and antiviral drug play different roles in controlling the disease, which has both vertical and horizontal transmission. We develop a 3D model with Susceptible-Infected-Recovered under vaccination to the susceptible and antiviral treatment to the infected and consider a control theoretic approach using the Pontryagin maximum principle to analyse the cost-effectiveness of the control process. Our results demonstrate that a mixed intervention strategy of vaccination and antiviral drug in a proper ratio is the most effective way to control the disease. We show that cost-effectiveness of both intervention strategies intimately depends on disease-related parameters, such as force of infection, probability of being infected to offspring from infected mothers, loss of immunity or reinfection and also on cost of treatment. © 2010 Taylor & Francis.

Mathematics

Computational and Mathematical Methods in Medicine

Optimal control of vertically transmitted disease: An integrated approach

Computer Physics Communications

A general purpose Fortran 90 electronic structure program for conjugated systems using Pariser--Parr--Pople model

Experimental charge density distributions in two known conformational polymorphs (orange and yellow) of coumarin 314 dye are analyzed based on multipole modeling of X-ray diffraction data collected at 100 K. The experimental results are compared with the charge densities derived from multipole modeling of theoretical structure factors obtained from periodic quantum calculation with density functional theory (DFT) method and B3LYP/6-31G(d,p) level of theory. The presence of disorder at the carbonyl oxygen atom of ethoxycarbonyl group in the yellow form, which was not identified earlier, is addressed here. The investigation of intermolecular interactions, based on Hirshfeld surface analysis and topological properties via quantum theory of atoms in molecule and total electrostatic interaction energies, revealed significant differences between the polymorphs. The differences of electrostatic nature in these two polymorphic forms were unveiled via construction of three-dimensional deformation electrostatic potential maps plotted over the molecular surfaces. The lattice energies evaluated from ab initio calculations on the two polymorphic forms indicate that the yellow form is likely to be the most favorable thermodynamically. The dipole moments derived from experimental and theoretical charge densities and also from Lorentz tensor approach are compared with the single-molecule dipole moments. In each case, the differences of dipole moments between the polymorphs are identified. © 2010 American Chemical Society.

Chemistry

Crystal Growth and Design

Experimental and theoretical charge density analysis of polymorphic structures: The case of coumarin 314 dye

The performance attained by electronic devices incorporating more than a single molecule is in part limited by weak electronic coupling between molecules. By implementing designed supramolecular interactions, chemists have begun taking control of the nanoscale ordering of the active layer in an effort to move beyond the trial and error tuning of the device morphology. This review describes current progress in solid-state devices in which the molecular components possess designed supramolecular interactions - as opposed to non-specific cohesive forces - used to instill or modify functionality. Supramolecular organic devices for applications in solar energy conversion, light-emitting diodes, field-effect transistors, storage and logic functions are covered. © 2010 Elsevier B.V.

Coordination Chemistry Reviews

Harnessing supramolecular interactions in organic solid-state devices: Current status and future potential

Steady state and time-resolved fluorescence spectroscopic techniques have been used to explore the Stokes shift dynamics and rotational relaxation of a dipolar solute probe in molten mixtures of acetamide (CH3CONH 2) with sodium and potassium thiocyanates (Na /KSCN) at T ∼ 318 K and several other higher temperatures. The dipolar solute probe employed for this study is coumarin 153 (C153). Six different fractions (f) of KSCN of the following ternary mixture composition, 0.75CH3CONH2 + 0.25[(1 - f)NaSCN + fKSCN], have been considered. The estimated experimental dynamic Stokes shift for these systems ranges between 1800 and 2200 cm -1 (±250 cm-1), which is similar to what has been observed with the same solute probe in several imidazolium cation based room temperature ionic liquids (RTIL) and in pure amide solvents. Interestingly, this range of estimated Stokes shift, even though not corresponding to the megavalue of static dielectric constant reported in the literature for a binary mixture of molten CH3CONH2 and NaSCN, exhibits a nonmonotonic KSCN concentration dependence. The magnitudes of the dynamic Stokes shift detected in the present experiments are significantly less than the estimated ones, as nearly 40-60% of the total shift is missed due to the limited time resolution employed (full-width at half-maximum of the instrument response function ∼70 ps). The solvation response function, constructed from the detected shifts in these systems, exhibits triexponential decay with the fastest time constant (τ1) in the 10-20 ps range, which might be much shorter if measured with a better time resolution. The second time constant (τ2) lies in the 70-100 ps range, and the third one (τ3) ranges between 300 and 800 ps. Both these time constants (τ2 and τ3) show alkali metal ion concentration dependence and exhibit viscosity decoupling at higher viscosity in the NaSCN-enriched region. Time dependent rotational anisotropy has been found to be biexponential at all mixture compositions studied. Both the average solvation (〈τs〉) and rotation (〈τr〉) times of C153 in these mixtures exhibit fractional power law dependence on medium viscosity (〈τx〉 ∞ νp, x being solvation or rotation). For solvation, p is found to be 0.46, which is very different from that obtained for common polar and nonpolar solvents, and RTILs (p ≈ 1). For rotation, p ≈ 0.65, which is again different from the value (p ≈ 1) obtained for common polar solvents and RTILs but very similar to that (p ≈ 0.6) found for nonpolar solvents. In addition, experimentally measured average rotation times in these mixtures are found to exhibit slip behavior in the low ν/T region, which gradually transforms to subslip as ν/T increases. Calculations using a recently developed semimolecular theory predict a total dynamic Stokes shift for C153 (dipolar solute) in these molten mixtures near ∼1600 cm-1 where the solute-solvent (dipole-dipole) and the ion-solute (ion-dipole) interactions contribute respectively ∼80% and ∼20% to the calculated total shift. Like in experiments, the theoretically predicted solvation response function in the overdamped limit at each mixture composition has been found to be triexponential. The calculations in the underdamped limit, however, suggest a biphasic decay where a composition independent subpicosecond component and a much slower component with the time constant spreading over 150-850 ps contribute equally to constitute the total decay. The calculated average solvation times in this limit are found to be in better agreement with experimental results than the predictions from the overdamped limit. © 2010 American Chemical Society.

Journal of Physical Chemistry B

Fluorescence spectroscopic studies of (acetamide + sodium/potassium thiocyanates) molten mixtures: Composition and temperature dependence

Detailed 27Al and 63Cu nuclear magnetic resonance (NMR) experiments have been performed in between 4.5 and 295 K on a polycrystalline sample of CeCu3Al2 which has a Kondo temperature ∼11K. The NMR spectral features and Knight shift measurements show that in this compound, Cu occupy both c and g lattice sites, while Al occupy only the g sites. From the temperature dependence of Knight shift (K), the hyperfine fields for 63Cu and 27Al at the g sites have been estimated as 2.02(5) and 1.67(5)kOe/$\mu$B, respectively and that for 63Cu at c sites as -3.83(5)kOe/$\mu$B. Nuclear spin-lattice relaxation time (T1) measurements indicate that though the relaxation process is governed by fluctuations of magnetic interaction, nuclear quadrupolar interaction also has a significant contribution, especially towards relaxation of 63Cu in both c and g sites. For 27Al, K and T 1 have yielded the effective 4f-spin correlation rate 1/$\tau$4f. The behavior of its temperature dependence indicates that at low temperatures in CeCu3Al2, the valence state of cerium might not be stable. {\textcopyright} 2010 Elsevier B.V. All rights reserved.

Physica B: Condensed Matter

27Al and 63Cu NMR studies on intermetallic Kondo compound CeCu3Al2

Research on structure and magnetic properties of polynuclear metal complexes to understand the structural and chemical factors governing the electronic exchange coupling mediated by multi-atom bridging ligands is of growing interest. Hydrothermal treatment of Ni(NO3) 2{\textperiodcentered}6H2O with N-(4-carboxyphenyl)iminodiacetic acid [N-4(H3CPIDA)] at 150 °C yielded a 3D coordination polymer of general formula [Ni3{N-4(CPIDA)}2(H2O) 3]{\textperiodcentered}6H2O (1). An analogous network of general formula [Co3{N-3(CPIDA)}2(H2O) 3]{\textperiodcentered}3H2O (2) was synthesized using N-(3-carboxyphenyl)iminodiacetic acid [N-3(H3CPIDA)] in combination with Co(NO3)2{\textperiodcentered}6H2O under identical reaction condition. Both the complexes contain trinuclear secondary building unit and crystallized in monoclinic system with space groups C2/c (1) and P21/c (2), respectively. Variable temperature magnetic characterization of these complexes in the temperature range of 2-300 K indicated the presence of overall ferromagnetic and antiferromagnetic behavior for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) were performed for further insight on the trinuclear units to provide a qualitative theoretical interpretation on the overall magnetic behavior of the complexes 1 and 2. {\textcopyright} 2010 Elsevier B.V. All rights reserved.

Inorganica Chimica Acta

Synthesis, crystal structures and magnetic behavior of two 3D coordination polymers using N-(4/3-carboxyphenyl)iminodiacetic acids as bridging ligands

The effect of interfacial hydrogen bonding on the behavior of the freezing/melting processes in two organic liquids, namely, ethylene glycol [(CH2OH)2] and isopropanol [CH3CH(OH)CH 3], confined in nanopores of ZSM-5 zeolite has been investigated using the positron annihilation spectroscopy (PAS) and nuclear magnetic resonance (NMR) techniques. Both liquids have intermolecular hydrogen bonding and feel attractive interaction toward the surface of the confining wall, resulting in an increase in the freezing/melting temperature while confined in nanopores. This observation differs from our earlier report on the behavior of benzene confined in ZSM-5 as well as in silica pores wherein a depression in freezing temperature was seen due to a weakly attractive/repulsive interaction between benzene and the pore surface. The measured S parameter, o-Ps lifetime and intensity profiles across the freezing point of ethylene glycol confined in ZSM-5 are seen to be different from those of isopropanol, signifying the difference in the behavior of phase transition in these two liquids under confinement. It is to be noted that, unlike isopropanol, ethylene glycol has strong intramolecular hydrogen bonding. This causes the difference in the fluid-wall interfacial interaction between ethylene glycol and isopropanol within the confinement. The phase-transition behavior of these two confined liquids was also investigated using the NMR technique by studying the spin-spin relaxation time (T2). The T2 process in ethylene glycol is expressed as a sum of at least two distinct components exhibiting Gaussian decay, whereas in isopropanol, T2 is expressed as a sum of three components showing Lorentzian decay. The transitions from one component to another were seen to be consistent with the positron annihilation spectroscopic observation. {\textcopyright} 2010 American Chemical Society.