Synthesis and characterization of fluorine functionalized graphene oxide dispersed quinoline-based polyimide composites having low-k and UV shielding properties

Polyimide nanocomposites having low-k and UV shielding properties have been developed using fluorine functionalized graphene oxide and bis(quinoline amine) based polyimide. The polyimide was synthesized using bis(quinoline amine) and pyromellitic dianhydride at appropriate experimental conditions, and its molecular structure was confirmed through various spectral analysis such as FTIR and NMR. The polyimide (PI) composites were prepared using bis(quinoline amine), pyromellitic dianhydride, and separately filled with 1, 5, 10 wt% of fluorinated graphene oxide (FGO) through in situ polymerization. The polymer composites were characterized using thermo gravimetric analysis (TGA), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). In addition, the water contact angle, dielectric behavior, and UV–Vis shielding behavior of FGO/PI composites were evaluated. The value of the water contact angle of the polyimide was increased with increment of FGO in the polyimide matrix. The highest water contact angle of polyimide composites observed 108° was obtained for 15 wt% FGO reinforced polyimide composite. The value of the dielectric constant for neat, 1, 5, and 15 wt% FGO reinforced polyimide composites was obtained as 4.5, 3.7, 2.6, and 2.0, respectively. It is also observed from by UV–Vis spectroscopy analysis that the FGO reinforced polyimide composites have good UV shielding behavior.     

Synthesis of Some Novel Class of Peptides from α‐Amino Nitrones and Their Potential Biological Activities

α‐amino nitrones are found to have a great significance in the synthesis of peptides. Simple reaction methodology, high yield, and atom efficiency in these reactions have made this protocol highly attractive. The synthetic route may be extended to the synthesis of dipeptides in enantiomerically pure form. Potential biological activity of the newly synthesized peptides is the major application in this new methodology.     

Chebyshev Centers that are Not Farthest Points

In this paper, we address the question whether in a given Banach space, a Chebyshev center of a nonempty bounded subset can be a farthest point of the set. We obtain a characterization of two-dimensional real strictly convex spaces as those ones where a Chebyshev center cannot contribute to the set of farthest points of a subset. In dimension greater than two, every non-Hilbert smooth space contains a subset whose Chebyshev center is a farthest point. We explore the scenario in uniformly convex Banach spaces and further study the roles played by centerability and Mcompactness in the scheme of things to obtain a step by step characterization of strictly convex Banach spaces.     

Exploration of an arabinogalactan isolated from Odina wodier Roxb.: Physicochemical,compositional characterisations and functional attributes

Exudate gum polysaccharides have a diverse range of functionalities in food, cosmetics, textiles, biomedical, pharmaceutical and other industries for centuries. The potentiality of gum odina as tablet binder, coacervates (chitosan‐gum odina complex) for colon‐targeted drug delivery system and also as prebiotic with immunomodulating properties was reported earlier. Since no detail study of the physicochemical, functional properties of the gum has been reported, the present investigation deals with physicochemical, compositional and functional characterisations of purified gum odina (PGO) for adopting in food and pharmaceutical industry. PGO, an arabinogalactan, was obtained by ethanol precipitation from exudates (gum odina) of tropical deciduous plant Odina wodier Roxb. Colour profiling of PGO including L* (87.74 ± 0.42), a* (1.73 ± 0.65) and b* (7.79 ± 0.58) was determined. Physicochemical parameters revealed good flow ability and compressibility desired for an excipient. Concentration‐dependent surface tension was measured by du Noüy ring method. Rheological study showed pseudoplastic behaviour of PGO dispersion. Sugar analysis by gas liquid chromatography indicated presence of arabinogalactan in PGO. Size exclusion chromatography of PGO revealed two high‐molecular‐weight components PGO‐I (95%, Arabinose:Galactose :: 1:1.6) and PGO‐II (5%, Arabinose:Galactose :: 1:4). Further characterisations of PGO by means of CHNS, FTIR, differential scanning calorimetry, X‐ray diffraction, transmission electron microscopy, scanning electron microscopy and energy‐dispersive X‐ray diffraction, conductivity, pH, zeta potential analysis and antioxidant activity indicated typical polysaccharide characteristics. Collectively, this work established the fundamental properties of PGO and the results presented here will facilitate the applications of PGO as sustainable food additive, pharmaceutical excipient for commercial adoption.     

Experimental and Quantum Mechanical Characterization of an Oxygen-Bridged Plutonium(IV) Dimer

We report the synthesis and characterization of K₄{[PuCl₂(NO₃)₃]₂(μ₂-O)}⋅H₂O, which contains the first known μ₂-oxo bridge between two Pu^IV metal centers. Adding to its uniqueness is the Pu−(μ₂-O) bond length of 2.04 Å, which is the shortest of other analogous compounds. The Pu−(μ₂-O)−Pu bridge is characterized by the mixing of s-, d-, and p-orbitals from Pu with the p-orbitals of O; the 5f-orbitals do not participate in bonding. Natural bond orbital analysis indicates that Pu and O interact through one 3c-2e σ_Pu-O-Pu and two 3c-2e π_Pu-O-Pu bonding orbitals and that the electron density is highly polarized on the μ₂-O. Bond topology properties analysis indicates that the Pu−(μ₂-O) bond shares both ionic and covalent character. Quantum mechanical calculations also show that the dimer has multiconfigurational ground states, where the nonet, septet, quintet, triplet, and singlet are close in energy. This work demonstrates the interplay between experimental and computational efforts that is required to understand the chemical bonding of Pu compounds.     

Synthesis of germanium encapsulated fullerene

A method has been described for encapsulating Ge in a fullerene cage using GeO₂ and a graphite composite rod as anode and graphite as cathode. Annealing in an inert atmosphere before arcing, and the amount of GeO₂ in the rod determined the yield of Ge doped metallofullerene. Solvent extraction using soxlet in inert atmosphere followed by calcination in air was used to isolate metallofullerene from the soot. The insertion of Ge inside the fullerene was proven by ultra violet–visible absorption spectroscopy, matrix assisted laser desorption ionization-time of flight mass spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.     

On the norm attainment set of a bounded linear operator

In this paper we explore the properties of a bounded linear operator defined on a Banach space, in light of operator norm attainment. Using Birkhoff–James orthogonality techniques, we give a necessary condition for a nonzero bounded linear operator to attain norm at a particular point of the unit sphere. We prove four corollaries to establish the importance of our study. As part of our exploration, we also obtain a characterization of smooth Banach spaces in terms of operator norm attainment and Birkhoff–James orthogonality. Restricting our attention to $l_p^2(p\in \mathbb{N}?\{1\})$ spaces, we obtain an upper bound for the number of points at which any linear operator, which is not a scalar multiple of an isometry, may attain norm.     

Universal quantum uncertainty relations: Minimum-uncertainty wave packet depends on measure of spread

Based on the statistical concept of the median, we propose a quantum uncertainty relation between semi-interquartile ranges of the position and momentum distributions of arbitrary quantum states. The relation is universal, unlike that based on the mean and standard deviation, as the latter may become non-existent or ineffective in certain cases. We show that the median-based one is not saturated for Gaussian distributions in position. Instead, the Cauchy-Lorentz distributions in position turn out to be the one with the minimal uncertainty, among the states inspected, implying that the minimum-uncertainty state is not unique but depends on the measure of spread used. Even the ordering of the states with respect to the distance from the minimum uncertainty state is altered by a change in the measure. We invoke the completeness of Hermite polynomials in the space of all quantum states to probe the median-based relation. The results have potential applications in a variety of studies including those on the quantum-to-classical boundary and on quantum cryptography.     

Identification of tyrosine kinase inhibitors from Panax bipinnatifidus and Panax pseudoginseng for RTK—HER2 and VEGFR2 receptors,by in silico approach

Molecular Diversity - Breast and stomach cancer is reported as a leading cause for human mortality across the world. The overexpression of receptor tyrosine kinase (RTK) proteins, namely the human...