Photo-, thermally, and pH-responsive microgels

Microgels with photo-, thermally, and pH-responsive properties in aqueous suspension have been synthesized and characterized using dynamic light scattering and UV-visible spectroscopy. The new route involved first preparing poly(N-isopropylacrylamide) (PNIPAM)-allylamine copolymer microgels and a spiropyran photochrome (SP) bearing a carboxylic acid group. Then the functionalized spiropyran was coupled to the microgel via an amide bond. The dark-equilibrated gel particles feature spiropyran molecules in the polar, merocyanine form. After irradiation of visible light, the particle size becomes smaller because spiropyran changes to the relatively nonpolar, closed spiro form. The PNIPAM-SP microgels undergo a volume phase transition in water from a swollen state to a collapsed state with increasing temperature under all light conditions. However, the transition temperature range of the PNIPAM-SP is much broader than that for the PNIPAM without SP. The PNIPAM-SP microgels are monodisperse and self-assemble into a crystalline lattice while in suspension. The UV-visible spectra of an aqueous suspension of PNIPAM-SP microgel in the dark-adapted, merocyanine form showed both an absorption peak around 512 nm due to the merocyanine (giving a reddish color to the suspension) and two sharp peaks from Bragg diffraction of colloidal crystallites. Upon visible irradiation, the 512-nm band bleached significantly due to spiropyran photoisomerization. The spiropyran photoisomerization and accompanying color changes of the suspension were reversible upon alternating dark, UV, and visible light irradiation. Due to the residues of amine groups, the swelling capability of PNIPAM-SP microgels reduces as the pH value is changed from 7 to 10.     

Fluorescence Investigation of Interactions Between Novel Benzanthrone Dyes and Lysozyme Amyloid Fibrils

A series of novel fluorescent benzanthrone dyes have been tested for their ability to identify and characterize fibrillar aggregates of lysozyme prepared by protein denaturation in concentrated ethanol solution (F_eth) or acidic buffer (F_ac). Quantitative parameters of the dye association with native and fibrillar protein have been derived from the results of fluorimetric titration. The binding characteristics proved to be different for F_eth- and F_ac-bound benzanthrones, highlighting the dye sensitivity to the distinctions in fibril morphology. By comparing the dye preference to fibrillar protein aggregates, AM2, A8 and A6 were selected as the most prospective amyloid tracers. Based on the analysis of red edge excitation shifts and fluorescence lifetimes of the amyloid-bound dyes it was assumed that surface grooves or dry “steric zipper” interface are potential fibril binding sites for the novel fluorophores.     

Convective stability analysis of a micropolar fluid layer by variational method

This paper studies Rayleigh-Bénard convection of micropolar fluid layer heated from below with realistic boundary conditions. A specific approach for stability analysis of a convective problem based on variational principle is applied to characterize the Rayleigh number for quite general nature of bounding surfaces. The analysis consists of replacing the set of field equations by a variational principle and the expressions for Rayleigh number are then obtained by using trial function satisfying the essential boundary conditions. Further, the values of the Rayleigh number for particular cases of large and small values of the microrotation coefficient have been obtained. The effects of wave number and micropolar parameter on the Rayleigh numbers for onset of stationary instability for each possible combination of the bounding surfaces are discussed and illustrated graphically. The present analysis establishes that the nature of bounding surfaces combination and microrotation have significant effect on the onset of convection.     

Microwave characterization of Pb<Subscript>1−x</Subscript>Ca<Subscript>x</Subscript>Fe<Subscript>0.5</Subscript>Nb<Subscript>0.5</Subscript>O<Subscript>3</Subscript> multiferroics at X-band

The microwave characteristics of Pb_1?x Ca _x Fe_0.5Nb_0.5O₃ multiferroics (x = 0.0, 0.4, 0.45, 0.5, 0.55, 0.6), have been investigated as a function of frequency and substitution. The results depict ?13.99 dB reflection loss at 11.65 GHz in composition x = 0.6. Microwave absorption is enhanced with substitution of Ca²⁺ ions and undoped composition 0.0 behaves as electromagnetic shield. The model governing microwave absorption is discussed and different compositions for electromagnetic applications have been suggested.     

Potassium carbonate mediated unusual transformation of 2,3-dihydroquinazolinone via cascade reaction

An unusual potassium carbonate mediated transformation of 2,3-dihydroquinazolinone by a one-pot operation is reported under mild conditions. In addition, it is interesting to report the regioselective transformation of 3-(2-bromophenyl)-2-isopropyl-2,3-dihydroquinazolin-4(1H)-one from compound 16.     

Buffalo Colostrum β-lactoglobulin Inhibits VEGF-Induced Angiogenesis by Interacting with G protein-Coupled Receptor Kinase

β-lactoglobulin (β-lg), a major whey protein was purified and characterised from buffalo colostrum. The in silico analysis of the tryptic peptides based on LC-CID-MS/MS facilitated the identification of protein as β-lg. The sequences IIVTQ f[1–5] and LSFNPTQLEEQCHV f(149–162) of m/z 933⁺ and 851²⁺ were found to match N- and C-extreme of β-lg while IDALNENK f(84–91) and TPEVDDEALEKFDK f(125–138) sequences deduced for m/z 916⁺ and 818²⁺ were in compliance to buffalo milk β-lg. Considering the sequence similarity of β-lg to glycodelin, a proven angiogenic protein, similar role for β-lg from buffalo colostrum (BLG-col) was examined. Interestingly, BLG-col exhibited anti-angiogenic activity by potently inhibiting cell proliferation, micro-vessel sprouting, cell migration and tube formation of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner but having varied effect on Ehrlich ascites tumor cells, MCF-7, MDA-MB 435 and MDA-MB 231 cell lines. The anti-angiogenic potential of BLG-col was found to be vascular endothelial growth factor mediated. The immunolocalisation of BLG-col on the cell surface of HUVECs evidenced using FITC-labelled β-lg antibody indicated its extra-cellular binding. Furthermore, BLG-col interacting HUVEC membrane protein (64 kDa) was detected by immunoblot and its identity was established by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry analysis, which showed peptide sequence homology to G protein-coupled receptor kinase 4.     

Enhancement of the stability and temperature range of the mesophases in the binary mixtures of cholesteryl myristate and 4-n-decyloxy benzoic acid

Thermodynamical, optical, and electrical properties of the binary mixtures of cholesteryl myristate (ChM) and 4-n-decyloxybenzoic acid (DOBA) have been carried out by the differential scanning calorimeter, polarized optical microscopy (POM), and impedance spectroscopy. Through thermodynamic study, various phase transition temperatures, transition enthalpies, and transition entropies have been determined to investigate temperature range and stability of the mesophases of the mixtures. Phase diagrams in the heating and cooling cycles have been drawn for the ChM–DOBA binary system. Optical textures of different mesophases have identified with the help of POM. Dielectric permittivity has been determined in planar and homeotropic alignments of the mixtures having DOBA concentrations 30.0 and 92.3 mol %. The experimental dielectric data in the frequency range of 1 Hz to 35 MHz do not show any relaxation mode in both the alignments of these mixtures. Dielectric anisotropy has been determined for the various observed phases of the mixtures.     

Evaluation of Glycosyl Hydrolases in the Secretome of <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> and Saccharification of Alkali-Treated Rice Straw

A thermotolerant Aspergillus fumigatus strain isolated from composting pile of mixed industrial waste was found to produce a spectrum of cellulase and hemicellulases when cultured on rice straw solidified substrate. The two-dimensional electrophoresis (2DE) resolved the secretome into 57 distinct protein spots. The zymograms developed against 2DE gels identified the presence of three β-glucosidases and five CBHI/EGI isoforms in the secretome. The peptide mass fingerprinting of 17 protein spots by liquid chromatography mass spectrometry characterized the secretome into different glycosyl hydrolase families. The enzyme cocktail produced by A. fumigatus was capable of efficient hydrolysis of alkali pretreated rice straw (at 7% and 10% w/v) resulting in 95% and 91% saccharification, respectively.     

Preliminary estimate of branching ratios of weak hadronic decays of bottom baryons emitting charmless scalar mesons

In this paper we study one-dimensional static self-dual non-topological solitons in an Abelian-Higgs Chern–Simons model with a non-canonical kinetic term. We choose a scalar potential with a single minimum and present an analytical soliton solution which corresponds to an electrically charged lump-like soliton without total momentum and located in a region where the scalar field gets maximum. The solitonic boundary conditions impose a discontinuity on the electric field across the soliton line where, then, there is a linear charge density.     

Identifying structural–functional analogue of GRL0617, the only well-established inhibitor for papain-like protease (PLpro) of SARS-CoV2 from the pool of fungal metabolites using docking and molecular dynamics simulation

Molecular Diversity - The non-structural protein (nsp)-3 of SARS-CoV2 coronavirus is sought to be an essential target protein which is also named as papain-like protease (PLpro). This protease...