Differential scanning calorimetry studies on aged iron(III)-chromium(III)-hydroxide coprecipitates

DSC measurements in air from 20 to 800° are reported on aged iron(III)-chromium(III) coprecipitated hydroxides (with Fe³⁺Cr³⁺ wt% ratios of 91, 73, 11, 37 and 19). A comparison of the DSC profiles of aged coprecipitates with the thermal behaviour of freshly precipitated and well characterized samples provided information on the modification occurring in the structure and reactivity of the coprecipitates on prolonged aging.

---

Zusammenfassung Es werden DSC-Messungen an gealterten kogefällten Eisen(III)Chrom(III)-hydroxiden (mit Fe³⁺Cr³⁺ Gewichtsanteilen von 91, 73, 11, 37 und 19) im Temperaturbereich von 20 bis 800° beschrieben. Ein Vergleich der DSC-Profile von gealterten Kofällungen mit dem thermischen Verhalten frisch gefällter und gut definierbarer Proben lieferte Informationen über die Veränderungen in Struktur und Reaktivität der Koniederschläge bei längerem Altern.

---

---

Dedicated to Professor Wahid U. Malik, Founder-President, Indian Council of Chemists, India, with profound regards and fond memories of his youthful enthusiasm and ceaseless and pioneering efforts towards the development of chemical education and research activities at the University of Roorkee, Roorkee, India, on the occasion of his 70th birthday.

---

Paper presented at the World Conference on Thermal Analysis, Capri (Italy), 1989.

---

We thank Professor J. Pescia, Dr.G. Ablart and N. Favillier of Laboratoire de Magnétisme et d'Electronique Quantique for their interest in this work. A. C. Vajpei expresses his gratefulness to C.N.R.S. and C.N.O.U.S., Paris, for financial support of this work.     

Fluorescence Properties of Isolated Intact Normal Human Corneas

Abstract— We have examined the fluorescence properties of excised intact normal human corneas from over a hundred donors, using synchronous excitation fluorescence spectroscopy. In some of the corneas from the donors, a fluoro-phore with an excitation band centered at 330 nm was observed. This fluorophore does not seem to correspond to the dityrosine moiety or to any photoproducts of tryptophan. Isolated corneas irradiated with light of 295 nm wavelength do not produce any fluorescent photoproducts, suggesting that the intact tissue has endogenous quenchers, radical scavengers and antioxidants that inhibit its photodamage. The non-tryptophan fluorophores that accumulate in some corneas thus appear to arise largely from the nonenzymatic glycosylation (glycation) of the constituent proteins as similar fluorophores are detected in the corneas of rats in which diabetes is induced.     

Characterisation of plasticized PMMA based solid polymer electrolytes

Polymer electrolyte films prepared from poly (methyl methacrylate) and LiAsF₆ with different concentrations of plasticizer (DBP) are described. The formation of polymer-salt complexes has been confirmed by XRD and FTIR spectral studies. The temperature dependence of the conductivity of the polymer films obeys the VTF relation. Values of conductivities of the polymer complexes are presented and discussed.     

Do Two Flavour Oscillations Explain both KamLAND Data and the Solar Neutrino Spectrum?

The recent measurement of Δ _sol by the KamLAND experiment with very small errors, makes definitive predictions for the energy dependence of the solar neutrino survival probability P _ee . We fix Δ _sol to be the KamLAND best fit value of 8×10⁻⁵ eV² and study the energy dependence of P _ee for solar neutrinos, in the framework of two flavour oscillations and also of three flavour oscillations. For the case of two flavour oscillations, P _ee has a measurable slope in the 5–8 MeV range but the solar spectrum measurements in this range find P _ee to be flat. The predicted values of P _ee , even for the best fit value of θ _sol , differ by 2–3 σ from the Super-K measured values in each of the three energy bins of the 5–8 MeV range. If future measurements of solar neutrinos by Super-K and SNO find a flat spectrum with reduced error bars (by a factor of 2), it will imply that two flavour oscillations can no longer explain both KamLAND data and the solar spectrum. However a flat solar neutrino spectrum and the Δ _sol measured by KamLAND can be reconciled in a three flavour oscillation framework with a moderate value of θ ₁₃≈13°.     

Routing and wavelength assignment algorithms for multiclass WDM optical networks

In this paper dynamic routing and wavelength assignment strategies have been proposed for multiclass WDM optical networks. Multiclass optical networks provide multiple classes of services to the subscriber according to the requirement, which in turn increase operational profitability. Each class of service could be characterized by parameters like number of wavelengths, expected call holding time and average arrival rate of request. The proposed strategies have been analyzed and compared with existing strategies on the basis of blocking probabilities for multiclass traffic scenarios. Simulation results on different network topologies demonstrate that the performance of proposed strategies “Fixed shortest/alternate shortest path routing with wavelength reservation (FSASWR)” and “Fixed alternate shortest path routing with least priority wavelength assignment (FASPL)” are much better as compared to existing strategies. Proposed strategies minimize blocking probability of the multiclass network using limited number of wavelengths.     

Synthesis,characterization, and evaluation of antimicrobial activities of a new class of macrocyclic phosphonates

A series of a new class of phosphorus analogue macrocycles was accomplished by condensation of N‐substituted‐[bis(3,5‐dimethyl‐2‐hydroxybenzyl)]‐amines with various phosphorus dichlorides in dry toluene in the presence of triethylamine at 0–50°C. All the title compounds were evaluated for antimicrobial activity to determine their efficacy and were effective in suppressing the growth of bacteria and fungi. The chemical structures of the title products were characterized by IR, ¹H, ¹³C, ³¹P‐NMR, mass spectral studies, and elemental analysis. J. Heterocyclic Chem., (2011).     

Generalized Langevin dynamics of a nanoparticle using a finite element approach: thermostating with correlated noise

A direct numerical simulation (DNS) procedure is employed to study the thermal motion of a nanoparticle in an incompressible Newtonian stationary fluid medium with the generalized Langevin approach. We consider both the Markovian (white noise) and non-Markovian (Ornstein-Uhlenbeck noise and Mittag-Leffler noise) processes. Initial locations of the particle are at various distances from the bounding wall to delineate wall effects. At thermal equilibrium, the numerical results are validated by comparing the calculated translational and rotational temperatures of the particle with those obtained from the equipartition theorem. The nature of the hydrodynamic interactions is verified by comparing the velocity autocorrelation functions and mean square displacements with analytical results. Numerical predictions of wall interactions with the particle in terms of mean square displacements are compared with analytical results. In the non-Markovian Langevin approach, an appropriate choice of colored noise is required to satisfy the power-law decay in the velocity autocorrelation function at long times. The results obtained by using non-Markovian Mittag-Leffler noise simultaneously satisfy the equipartition theorem and the long-time behavior of the hydrodynamic correlations for a range of memory correlation times. The Ornstein-Uhlenbeck process does not provide the appropriate hydrodynamic correlations. Comparing our DNS results to the solution of an one-dimensional generalized Langevin equation, it is observed that where the thermostat adheres to the equipartition theorem, the characteristic memory time in the noise is consistent with the inherent time scale of the memory kernel. The performance of the thermostat with respect to equilibrium and dynamic properties for various noise schemes is discussed.