Study of ionomer blends based on a polyurethane cationomer and an acrylic anionomer

Polyurethane and polyurethane cationomers were synthesized using 2,3-dihydroxypyridine and 2,3-dihydroxypyridine hydrochloride as chain extenders. Poly(butyl methacrylate-co-methacrylic acid) was synthesized by free radical solution polymerization and was converted into its sodium salt. The polyurethane cationomer and the acrylic anionomer were blended in different proportions in N,N-dimethylformamide. Simple blends without ionic groups were also prepared. Miscibility enhancement in these systems was studied by means of differential scanning calorimetry and scanning electron microscopy.     

Phase synchronization and collective interaction of multiple flamelets in a laboratory scale spray combustor

In this paper, we investigate the coupled behvior of the acoustic field in the confinement and the unsteady flame dynamics in a laboratory scale spray combustor. We study this interaction during the intermittency route to thermoacoustic instability when the location of the flame is varied inside the combustor. As the flame location is changed, the synchronization properties of the coupled acoustic pressure and heat release rate signals change from desynchronized aperiodicity (combustion noise) to phase synchronized periodicity (thermoacoustic instability) through intermittent phase synchronization (intermittency). We also characterize the collective interaction between the multiple flamelets anchored at the flame holder and the acoustic field in the system, during different dynamical states observed in the combustor operation. When the signals are desynchronized, we notice that the flamelets exhibit a steady combustion without the exhibition of a prominent feedback with the acoustic field. In a state of intermittent phase synchronization, we observe the existence of a short-term coupling between the heat release rate and the acoustic field. We notice that the onset of collective synchronization in the oscillations of multiple flamelets and the acoustic field leads to the simultaneous emergence of periodicity in the global dynamics of the system. This collective periodicity in both the subsystems causes enhancement of oscillations during epochs of amplitude growth in the intermittency signal. On the contrary, the weakening of the coupling induces suppression of periodic oscillations during epochs of amplitude decay in the intermittency signal. During phase synchronization, we notice a sustained synchronized movement of all flamelets with the periodicity of the acoustic cycle in the system.     

Effect of Polymer Strengtheners on the Local Environment of Biocompatible Glass as Probed by Fluorescence

Mixed silica–calcite matrices were prepared by developing a “low” temperature (sol–gel) method in presence of several biocompatible polymers, thus providing samples with adequate porosity for the flow of biological fluids and also mechanically robust. In order to analyse and characterise the sample’s microenvironments, the highly solvatochromic probe Nile red was used, which enabled the role of polymer addition upon local environmental effects in the host media to be elucidated. The polymers used were polyethylene glycol, polymethylmethacrylate and polyethylene. Each matrix was also characterized with respect to microstructure, morphology and pore size via the use of X-ray diffractometry and scanning electron microscopy. The results show that is was possible to obtain, in a controlled way, mixed silica–calcite matrices with a wide range of porosities (important if the material is to be used for scaffold or drug release applications, for example). The spectroscopic behaviour of Nile red when incorporated has confirmed the existence of distinct and specific local polarities within each type of matrix that may determine to a large extent the mechanism of interaction between these matrices and biological molecules. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Transient entropy analysis of the magnetohydrodynamics flow of a Jeffrey fluid past an isothermal vertical flat plate

In this work, we derive analytical solutions for static structure factor for homogeneous and isotropic solution composed of two components interacting with each other via simple van der Waals potential which is inversely proportional to the sixth power of the distance between the two components. We assume that the first component is the solvent and the second component is the dissolved material which has low concentration or density in comparison to the concentration of the solvent, i.e. dilute solution, which is common for macromolecular fluids. The presented solution is obtained using direct and inverse Fourier transforms in solving Ornstein–Zernike equations (OZE) for multicomponent systems. We calculated isothermal compressibilities as a function of concentration and comparison with other simulation and theoretical results are presented. We believe that the presented solution can be useful in studying biomolecular fluids and other soft matter fluids.     

Density functional theory study of ω phase in steel with varied alloying elements

The presence of a long-abandoned hexagonal omega (ω) phase in steel samples is recently gaining momentum owing to the advances in transmission electron microscopy (TEM) measurements, even though it is already reported in other transition-metal alloys. The stabilization of this metastable phase is mainly investigated in presence of C, even though the formation of the ω phase is attributed to the combined effect of many factors, one among which is the enrichment of solute elements such as Al, Mn, Si, C, and Cr in the nanometer-sized regimes. The present study investigates the effect of the above alloying elements in ω-Fe using density functional theory (DFT) calculations. It is seen that the magnetic states of the atoms play a major role in the stability of ω-Fe. Cohesive energy calculations show that the alloying elements affect the energetics and stabilization of ω-Fe. Further, density of states calculations reveal the variation in d-band occupancy in the presence of alloying elements, which in turn affects the cohesive energy. Phonon band structure calculations show that only ω-Fe with substitutional C shows positive frequencies and hence possess thermodynamic stability. Finally, we confirm the existence of ω-Fe using TEM measurements of a steel sample containing the same alloying elements. Our results can shed light on the stabilization of the ω in other transition-metal alloys as well, in the presence of minor alloying elements.     

Synthesis of isoniazid-1,2,3-triazole conjugates: Antitubercular,antimicrobial evaluation and molecular docking study

In the present study, a series of new isoniazid-1,2,3-triazole conjugates ( 5a-k ) was synthesized via click chemistry approach. The newly synthesized compounds were assessed for their in vitro antitubercular and antimicrobial activities. The compound 5g has displayed potent antitubercular activity against Mycobacterium tuberculosis H37Rv (Mtb) with MIC value 1.56 μg/mL. The active compounds were screened for their cytotoxicity profile by MTT assay against RAW 264.7 cell line. The four compounds have shown good in vitro antimicrobial activities against both antibacterial and antifungal pathogens. A molecular docking study was accomplished to identify the probable mode of action of synthesized derivatives. These compounds have shown excellent binding affinity toward Enoyl-acp reductase (INHA) and DNA gyrase.     

Determination of Solifenacin Succinate in Pure and Pharmaceutical Dosage forms by Spectrophotometry

Journal of Analytical Chemistry - Four simple, precise and sensitive visible spectrophotometric methods were developed for the determination of solifenacin succinate in pure and pharmaceutical...