Synthesis, Structure, and Solid-State Transformation Studies of Phosphonoacetate Based Hybrid Compounds of Uranium and Thorium

Three new phosphonoacetate hybrid frameworks based on the actinide elements uranium and thorium have been synthesized. The compounds [C4N2H14][(UO2)(2)(O3PCH2COO)(2)]center dot H2O, I,[C4N2H14][(UO2)(2)(C2O4)(O3PCH2COOH)(2)], II, and Th(H2O)(2)(O3PCH2COO)(C2O4)(0.5). H2O, III, are built up from the connectivity between the metal polyhedra and the phosphonoacetate/oxalate units. Compound II has been prepared using a solvent-free approach, by a solid state reaction at 150 degrees C. It has been shown that II can also be prepared through a room temperature mechanochemical (grinding) route. The layer arrangement in III closely resembles to that observed in I. The compounds have been characterized by powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and fluorescence studies.

Reactions of bis(isonitrosoethylacetoacetato)palladium(II) with straight chain aliphatic primary amines influence of concentration of the reacting amines on the nature of the products

Reactions of bis(isonitrosoethylacetoacetato)palladium(II), Pd(IEAA)2,with straight chain non-bulky alkylamines, RNH2(R = CH3, C2H5, n-C3H7or n-C4H9) in the mole ratio 1:1 gave bis (B-alkylisonitrosoethylacetoacetateimino)Palladium(II), Pd(R-IEAI)2. In this reaction the coordinated carbonyl groups of Pd(IEAA)2 undergo condensation with amines fo rming Schiff bases (>CNR). On the other hand, the reactions of Pd(IEAA)2 with a large excess of amine yielded N-alkylamido bridgedisonitrosoethylacetoacetatedipalladium(II), μ-(NHR)2[Pd(IEAA)]2 complexes. The complexes are characterized by elemental analyses, magnetic susceptib ility, i.r., p.m.r. and in some cases, nitrogen 1s X-ray photoelectron and mass spectral studies.

Resistance fluctuations, phase randomness and noise in one-dimensional conductors with a long-range correlated potential

When the size (L) of a one-dimensional metallic conductor is less than the correlation length λ-1 of the Gaussian random potential, one expects transport properties to show ballistic behaviour. Using an invariant imbedding method, we study the exact distribution of the resistance, of the phase θ of the reflection amplitude of an incident electron of wave number k0, and of dθ/dk0, for λL ll 1. The resistance is non-self-averaging and the n-th resistance moment varies periodically as (1 - cos 2k0L)n. The charge fluctuation noise, determined by the distribution of dθ/dk0, is constant at low frequencies.

Studies on LDPE-cyanoethylated lignocellulosics blends using epoxy functionalized LDPE as compatibilizer

Rubberwood flour and cellulose have been plasticized by cyanoethylation and then blended with low-density polyethylene (LDPE). A small quantity of epoxy functionalized polyethylene i.e., polyethylene-co-glycidyl methacrylate (PEGMA) has been added to further enhance the mechanical properties. The mechanical properties were measured according to the standard ASTM methods. SEM analysis was performed for both fractured and unfractured blend specimens. The mechanical properties were improved by the addition of PEGMA compatibilizer. LDPE blends with cyanoethylated wood flour (CYWF) showed higher tensile strength and modulus than cyanoethylated cellulose CYC-LDPE blends. However CYC-LDPE blends exhibited higher relative elongation at break values as compared with the former. The TGA analysis showed lowering of thermal stability as the filler content is increased and degradation temperature of LDPE is shifted slightly to lower temperature. DSC analysis showed loss of crystallinity for the LDPE phase as the filler content is increased for both types of blends. Dielectric properties of the blends were similar to LDPE, but were lowered on adding PEGMA. (c) 2006 Wiley Periodicals, Inc.

Approximate multipole coefficients of RF ion traps as functions of aperture size

In this study we present approximate analytical expressions for estimating the variation in multipole expansion coefficients as a function of the size of the apertures in the electrodes in axially symmetric (3D) and two-dimensional (2D) ion trap ion traps. Following the approach adopted in our earlier studies which focused on the role of apertures to fields within the traps, here too, the analytical expression we develop is a sum of two terms, A(n,noAperiure), the multipole expansion coefficient for a trap with no apertures and A(n,dueToAperture), the multipole expansion coefficient contributed by the aperture. A(n,noAperture) has been obtained numerically and A(n,dueToAperture) is obtained from the n th derivative of the potential within the trap. The expressions derived have been tested on two 3D geometries and two 2D geometries. These include the quadrupole ion trap (QIT) and the cylindrical ion trap (CIT) for 3D geometries and the linear ion trap (LIT) and the rectilinear ion trap (RIT) for the 2D geometries. Multipole expansion coefficients A(2) to A(12), estimated by our analytical expressions, were compared with the values obtained numerically (using the boundary element method) for aperture sizes varying up to 50% of the trap dimension. In all the plots presented, it is observed that our analytical expression for the variation of multipole expansion coefficients versus aperture size closely follows the trend of the numerical evaluations for the range of aperture sizes considered. The maximum relative percentage errors, which provide an estimate of the deviation of our values from those obtained numerically for each multipole expansion coefficient, are seen to be largely in the range of 10-15%. The leading multipole expansion coefficient, A(2), however, is seen to be estimated very well by our expressions, with most values being within 1% of the numerically determined values, with larger deviations seen for the QIT and the LIT for large aperture sizes. (C) 2010 Elsevier B.V. All rights reserved.

The role of inflammation and matrix proteins in airway remodelling

Asthma is a chronic inflammatory disorder of the airways. Remodelling in asthma is defined as the structural changes seen in the airways of asthmatics in comparison to healthy controls. Progressive loss of lung function also seen in asthma might be caused by remodelling. The research aims of this thesis were to investigate inflammation and remodelling in the airways of different types of asthmatics and smokers. The association between inflammation and remodelling was also examined in a mouse model of allergic airway inflammation. Healthy smokers showed increased numbers of macrophages in the BAL with no changes in the inflammatory cells in biopsies. Macrophages seemed to be quite quiescent, since mRNA expression for a wide variety of inflammatory mediators, especially chemokines CCL3, CCL4, CCL5 and CCL20, secreted by macrophages was significantly lower than in healthy non-smokers. Attenuated macrophage activity in the airway lumen may render smokers more susceptible to airway infections and have an impact on the development of other airway pathology. Patients with diisocyanate-induced asthma (DIA) on inhaled corticosteroids (ICS) who still had non-specific bronchial hyperreactivity (NSBHR) at the end of the follow-up showed increased expression of TNF-α, IL-6 and IL-15 mRNA in BAL cells compared to those without NSBHR. In addition to being markers for poor prognosis and possible slight glucocorticoid resistance, these cytokines might aid in guiding the treatment of DIA. The increase in the thickness of tenascin-C layer in the bronchial basement membrane (BM) was much less than usually seen in other types of asthma, which might not make tenascin-C a good marker for DIA. OVA-induced tenascin-C expression in the lung was attenuated in STAT4-/- mice with impaired Th1-type immunity compared to WT mice. Interestingly, STAT6-/- mice with impaired Th2-type immunity showed tenascin-C expression levels similar to those of WT mice. The clearest difference between these two knockout strains in response to OVA was that STAT4-/- mice exhibited no upregulation of IFN-γ and TNF-α mRNA expression. Thus, tenascin-C expression was unexpectedly more related to Th1 type reactions. In vitro studies confirmed the results. Human fibroblasts stimulated by TNF-α and IFN-γ showed increased expression of tenascin-C. Patients with newly diagnosed asthma showed increased expression of laminin α2 in the bronchial BM in comparison to patients with asthma symptoms only and healthy controls. Both patients with asthma and those with only asthma symptoms showed increased expression of the laminin β2 chain in comparison to controls. Thus, laminin α2 expression differentiated patients with clinical asthma from patients with symptoms only. Furthermore, the expression of laminin α2 and β2 was associated with NSBHR, linking very specific remodelling events to clinical findings.

Correlation of helicopter rotor aeroelastic response with HART-II wind tunnel test data

Purpose - This paper aims to validate a comprehensive aeroelastic analysis for a helicopter rotor with the higher harmonic control aeroacoustic rotor test (HART-II) wind tunnel test data. Design/methodology/approach - Aeroelastic analysis of helicopter rotor with elastic blades based on finite element method in space and time and capable of considering higher harmonic control inputs is carried out. Moderate deflection and coriolis nonlinearities are included in the analysis. The rotor aerodynamics are represented using free wake and unsteady aerodynamic models. Findings - Good correlation between analysis and HART-II wind tunnel test data is obtained for blade natural frequencies across a range of rotating speeds. The basic physics of the blade mode shapes are also well captured. In particular, the fundamental flap, lag and torsion modes compare very well. The blade response compares well with HART-II result and other high-fidelity aeroelastic code predictions for flap and torsion mode. For the lead-lag response, the present analysis prediction is somewhat better than other aeroelastic analyses. Research limitations/implications - Predicted blade response trend with higher harmonic pitch control agreed well with the wind tunnel test data, but usually contained a constant offset in the mean values of lead-lag and elastic torsion response. Improvements in the modeling of the aerodynamic environment around the rotor can help reduce this gap between the experimental and numerical results. Practical implications - Correlation of predicted aeroelastic response with wind tunnel test data is a vital step towards validating any helicopter aeroelastic analysis. Such efforts lend confidence in using the numerical analysis to understand the actual physical behavior of the helicopter system. Also, validated numerical analyses can take the place of time-consuming and expensive wind tunnel tests during the initial stage of the design process. Originality/value - While the basic physics appears to be well captured by the aeroelastic analysis, there is need for improvement in the aerodynamic modeling which appears to be the source of the gap between numerical predictions and HART-II wind tunnel experiments.

A rationalisation of fatigue thresholds in pearlitic steels using a theoretical model

From a detailed re-examination of results in the literature, the effects of microstructure sizes, namely interlamellar spacing, pearlitic colony size and the prior austentitic grain size on the thresholds for fatigue crack growth (ΔKth) and crack closure (Kcl, th) have been illustrated. It is shown that while interlamellar spacing explicitly controls yield strength, a similar effect on ΔKth cannot be expected. On the other hand, the pearlitic colony size is shown to strongly influence ΔKth and Kcl, th through the deflection and retardation of cracks at colony boundaries. Consequently, an increase in ΔKth and Kcl, th with colony size has been found. The development of a theoretical model to illustrate the effects of colony size, shear flow stress in the slip band and macroscopic yield strength on Kcl, th and ΔKth is presented. the model assumes colony boundaries as potential sites for slip band pile-up formation and subsequent crack deflection finally leading to zig-zag crack growth. Using the concepts of roughness induced crack closure, the magnitude of Kcl, th is quantified as a function of colony size. In deriving the model, the flow stress in the slip band has been considered to represent the work hardened state in pearlite. Comparison of the theoretically predicted trend with the experimental data demonstrates very good agreement. Further, the intrinsic or closure free component of the fatigue threshold, ΔKeff, th is found to be insensitive to colony size and interlamellar spacing. Using a criterion for intrinsic fatigue threshold which considers the attainment of a critical fracture stress over a characteristic distance corresponding to interlamellar spacing, ΔKth values at high R values can be estimated with reasonable accuracy. The magnitude of ΔKth as a function of colony size is then obtained by summing up the average value of experimentally obtained ΔKeff, th values and the predicted Kcl, th values as a function of colony size. Again, very good agreement of the theoretically predicted ΔKth values with those experimentally obtained has been demonstrated.

Thermodynamic properties of the system toluene — 1, 1, 1-trichloroethane

Data on molar excess enthalpy on mixing at 298.15 K and 308.15 K, vapor-liquid equilibrium, latent heats of vaporization at 91.444 kPa and vapor pressures for the system toluene – 1, 1, 1-trichloroethane are presented. A simple adiabatic calorimeter designed for molar excess enthalpy measurements is described, tested and used. On présente, dans le cas du système toluène – 1, 1, 1-trichloréthane, des résultats relatifs aux grandeurs suivantes: a) enthalpie molaire d'excès à 298.15 K et 308.15 K; b) équilibre liquid-vapeur; c) chaleurs latentes de vaporisation à une pression absolue de 91.444 kP; d) pressions de vapeur. On décrit un calorimètre adiabatique simple, conçu pour mesurer l'enthalpie molaire d'excès, dont on a fait l'essai.

Structural Investigations on Poly(4-hydroxy-L-proline). 1. Theoretical Studies

Model building studies on poly(hydroxypro1ine) indicate that in addition to the well-known helical structure of form A, a left-handed helical structure with trans peptide units and with h = 2.86 A and n = 2.67 (i.e., 8 residues in 3 turns) is also possible. In this structure which is shown to be in agreement with X-ray data of the form B in the next paper, the y-hydroxyl group of an (i + 1)th Hyp residue is hydrogen bonded to the carbonyl oxygen of an (i - 1)th residue. The possibility of a structure with cis peptide units is ruled out. It is shown that both forms A and B are equally favorable from considerations of intramolecular energies. Since form B is further stabilized by intrachain hydrogen bonds, we believe that this is likely to be the ordered conformation for poly(hydroxypro1ine) in water.