Phase transitions in Lu2_2Ir3_3Si5_5

We report the results of our investigations on a polycrystalline sample of Lu$_2$Ir$_3$Si$_5$ which crystallizes in the U$_2$Co$_3$Si$_5$ type structure (Ibam). These investigations comprise powder X-ray diffraction, magnetic susceptibility, electrical resistivity and high temperature (120-300 K) heat capacity studies. Our results reveal that the sample undergoes a superconducting transition below 3.5 K. It also undergoes a first order phase transition between 150-250 K as revealed by an upturn in the resistivity, a diasmagnetic drop in the magnetic susceptibility and a large anomaly (20-30 J/mol K) in the specific heat data. We observe a huge thermal hysteresis of almost 45 K between the cooling and warming data across this high temperature transition in all our measurements. Low temperature X-ray diffraction measurements at 87 K reveals that the compound undergoes a structural change at the high temperature transition. Resistivity data taken in repeated cooling and warming cycles indicate that at the high temperature transition, the system goes into a highly metastable state and successive heating/cooling curves are found to lie above the previous one and the resistance keeps increasing with every thermal cycle. The room temperature resistance of a thermaly cycled piece of the sample decays exponentialy with time with a decay time constant estimated to be about 10$^4$ secs. The anomaly (upturn) in the resistivity and the large drop (almost 45%) in the susceptibility across the high temperature transition suggest that the observed structural change is accompanied or induced by an electronic transition.Comment: 7 figures, 1 table and 18 reference

Prevalence of malnutrition and intestinal parasites in preschool slum children in Lucknow

Objective: To assess the point prevalence of intestinal parasites and their association with nutritional parameters. Setting: Anganwadi centers under the Integrated Child Development Scheme (ICDS) in Lucknow, North India. Design: Cross-sectional survey. Methods: By random draw, 32 out of 153 Anganwadi centers were selected. All eligible subjects registered with the Anganwadi worker were enrolled. These were 1061 children (48.3% girls and 51.7% boys) between the ages of 1.5 to 3.5 years. Results: Of these, 67.6% were underweight (weight for age <- 2 SD), 62.8% were stunted (height for age <-2 SD) and 26.5% were wasted (weight for height <-2 SD). Parasites were detected in 17.5% (95% CI 15.3%-19.9%) children by a single direct fecal smear examination. Of these, Ascaris lumbricoides was found in 124 (68.1%) and Giardia lamblia in 60 (32.9%). There was no association between weight or height and parasite positivity. The mean hemoglobin levels for children who were smear positive versus smear negative for ascaris or giardia were 9.1 g/dl and 9.6 g/dl, respectively (p<0.0001). Conclusion: In the urban slums the point prevalence of intestinal parasites is 17.5% in the preschool children. Malnutrition and low hemoglobin levels are also widely prevalent. Urgent remedial steps are needed on community basis to improve their nutritional status and control parasitic infestation

Study of np-scattering for S, P and D Waves using Deng-Fan Potential by Phase Function Method

In this paper, the np - scattering phase shifts and cross section for S,P and D partial waves have been obtained for energies below the pion threshold, by considering Deng-Fan potential as model of interaction. The radial time independent Schr\"odinger equation has been analytically solved using Nikiforov - Uvarov method to obtain the energy expression for ground state of np system. Utilising this, the scattering phase shifts for $^3S_1$ have been obtained using phase function method. The phase equations for various scattering states $^1S_0$, $^1P_1$, $^3P_{0,1,2}$, $^1D_2$, and $^3D_{1,2,3}$ have been numerically solved for obtaining corresponding scattering phase shifts and their respective partial cross section. The total scattering cross sections computed at various energies are found to be closely matching with experimental data. The low energy scattering parameters determined from scattering phase shifts of $^3S_1$ and $^1S_0$ are reasonably close to experimental ones. Hence, Deng-Fan potential is a good phenomenological potential to understand the np - scattering system.Comment: 11 pages, 4 figures, 2 table

Comparative Study of alpha-alpha interaction potentials constructed using various phenomenological models

In this paper, we have made a comparative study of alpha-alpha scattering using different phenomenological models like Morse, double Gaussian, double Hulthen, Malfliet-Tjon and double exponential for the nuclear interaction and atomic Hulthen as screened coulomb potential. The phase equations for S, D and G channels have been numerically solved using 5th order Runge-Kutta Method to compute scattering phase shifts for elastic scattering region consisting of energies up to 25.5 MeV. The model parameters in each of the chosen potentials were varied in an iterative fashion to minimize the mean absolute percentage error between simulated and expected scattering phase shifts. A comparative analysis revealed that, all the phenomenological models result in exactly similar inverse potentials with closely matching mean absolute percentage error values for S, D and G state. One can conclude that any mathematical function that can capture the basic features of two body interaction would always guide correctly in construction of inverse potentials.Comment: 11 pages, 3 figures, 4 Table

Uplift of Himalaya and it’s implications on the evolution of Indian monsoon

Abstract HKT-ISTP 2013 A

Constructing Inverse Scattering Potentials for {\alpha}-{\alpha} System using Reference Potential Approach

Background: An accurate way to incorporate long range Coulomb interaction alongside short-range nuclear interaction has been a challenge for theoretical physicists. Purpose: In this paper, we propose a methodology based on the reference potential approach for constructing inverse potentials of alpha-alpha scattering. Methods: Two smoothly joined Morse potentials, regular for short-range nuclear interaction and inverted for long range Coulomb, are used in tandem as a reference potential in the phase function method to obtain the scattering phase shifts for the S, D and G states of alpha-alpha scattering. The model parameters are optimized by choosing to minimize the mean absolute percentage error between the obtained and experimental scattering phase shift values. Results: The constructed inverse potentials for S, D and G states have resulted in mean absolute percentage errors of 0.8, 0.5, and 0.4 respectively. The obtained resonances for D and G states closely match the experimental ones. Conclusion: The reference potential approach using a combination of smoothly joined Morse functions is successful in accurately accounting for the Coulomb interaction between charged particles in nuclear scattering studies.Comment: 10 pages, 4 figures, 2 Table

Modulated structure in the martensite phase of Ni1.8Pt0.2MnGa: a neutron diffraction study

7M orthorhombic modulated structure in the martensite phase of Ni1.8Pt0.2MnGa is reported by powder neutron diffraction study, which indicates that it is likely to exhibit magnetic field induced strain. The change in the unit cell volume is less than 0.5% between the austenite and martensite phases, as expected for a volume conserving martensite transformation. The magnetic structure analysis shows that the magnetic moment in the martensite phase is higher compared to Ni2MnGa, which is in good agreement with magnetization measurement

Complexes of Organotin(IV) Halides with Neutral Schiff Bases of Salicylaldehyde & 2-Hydroxy-l-naphthaldehyde with 2-Aminopyridine

1023-102

Solvent-induced β-hairpin to helix conformational transition in a designed peptide

An octapeptide containing a central Aib-Gly- segment capable of adopting β-turn conformations compatible with both hairpin (βII' or βI′) and helical (βI) structures has been designed. The effect of solvent on the conformation of the peptide Boc-Leu-Val-Val-Aib-Gly-Leu-Val-Val-OMe (VIII; Boc: t-butyloxycarbonyl; OMe: methyl ester) has been investigated by NMR and CD spectroscopy. Peptide VIII adopts a well-defined β-hairpin conformation in solvents capable of hydrogen bonding like (CD3)2SO and CD3OH. In solvents that have a lower tendency to interact with backbone peptide groups, like CDCl3 and CD3CN, helical conformations predominate. Nuclear Overhauser effects between the backbone protons and solvent shielding of NH groups involved in cross-strand hydrogen bonding, backbone chemical shifts, and vicinal coupling constants provide further support for the conformational assignments in different solvents. Truncated peptides Boc-Val-Val-Aib-Gly-Leu-Val-Val-OMe (VII), Boc-Val-Val-Aib-Gly-Leu-Val-OMe (VI), and Boc-Val-Aib-Gly-Leu-OMe (IV) were studied in CDCl3 and (CD3)2SO by 500 MHz 1H-NMR spectroscopy. Peptides IV and VI show no evidence for hairpin conformation in both the solvents. The three truncated peptides show a well-defined helical conformation in CDCl3. In (CD3)2SO, peptide VII adopts a β-hairpin conformation. The results establish that peptides may be designed, which are poised to undergo a dramatic conformational transition