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Airglow emissions which originate from the mesospheric and thermospheric altitudes have been routinely being monitored at Kolhapur (16.8° N, 74.2° E), Maharashtra, India, using ground base remote sensing imagers. We note that the observable amplitudes of very small-scale waves during April 2020 were significantly smaller than the regular observations. We investigate the reason for these low observable amplitudes. It is noted that drastic improvement in the quality of images was due to better contrast, which is attributed to significant reduction in greenhouse gases and aerosol loading in the atmosphere by the complete shutdown of local man-made emissions. Results suggest that lockdown had an important repercussion on the visibility through the improved air quality and thus better viewing conditions, which were reflected in the remotely sensed observations made with airglow imager. [ABSTRACT FROM AUTHOR]

We discuss experimental results on the ability to significantly tune the photoluminescence decay rates of CdSe quantum dots embedded in an ordered template, using lightly doped small gold nanoparticles (nano-antennae), of relatively low optical efficiency. We observe both enhancement and quenching of photoluminescence intensity of the quantum dots varying monotonically with increasing volume fraction of added gold nanoparticles, with respect to undoped quantum dot arrays. However, the corresponding variation in lifetime of photoluminescence spectra decay shows a hitherto unobserved, non-monotonic variation with gold nanoparticle doping. We also demonstrate that Purcell effect is quite effective for the larger (5 nm) gold nano-antenna leading to more than four times enhanced radiative rate at spectral resonance, for largest doping and about 1.75 times enhancement for off-resonance. Significantly for spectral off-resonance samples, we could simultaneously engineer reduction of non-radiative decay rate along with increase of radiative decay rate. Non-radiative decay dominates the system for the smaller (2 nm) gold nano-antenna setting the limit on how small these plasmonic nano-antennae could be to be effective in engineering significant enhancement in radiative decay rate and, hence, the overall quantum efficiency of quantum dot based hybrid photonic assemblies. [ABSTRACT FROM AUTHOR]

sPLA2 is released under inflammatory conditions from neutrophils, basophils and T-cells. They cleave the cellular phospholipids leading to the release of arachidonic acid and there by provide intermediates for biosynthesis of inflammatory mediators. The focus of this study is on the interaction of hesperidin, a natural flavonoid with Group IB, IIA, and V and X isozymes of sPLA2. Affinity of hesperidin towards PLA2 isozymes was analyzed through enzymatic studies and molecular modeling. The experiments showed that hesperidin competitively inhibited PLA2 with IC50 of 5.1 µM. Molecular modeling studies revealed the association of hesperidin with the docking scores −6.90, −9.53, −5.63 and −8.29 kcal for isozymes Group IB, IIA, V and X of PLA2 respectively. Their binding energy values were calculated as −20.25, −21.63, −21.66 and −33.43 kcal for the Group IB, IIA, V and X respectively. Structural model for Group V was made by homology modeling since no structural coordinates were available. Molecular dynamics studies were carried out to evaluate the structural stability of protein ligand complex. The analyses showed that hesperidin blocked the entry of the substrate to the active site of PLA2 and it was indifferent to the differences of the isozymes. Hence, hesperidin might serve as lead for designing highly specific anti-inflammatory drugs directed to the PLA2 isozyme specific to various diseases, with IC50 value of therapeutic significance. [ABSTRACT FROM AUTHOR]

Lipoxygenase (LOX) inhibitors are considered to be important anti-inflammatory agents as it can control many inflammatory responses to some extent. Even though the marine bio-systems are not well explored, they are considered to be one of the promising repositories for drug lead molecules against variety of diseases. In the present study a new LOX inhibitor compound, 1-ethenoxy-2-methylbenzene, reported first time from a living system, Microcoleus chthonoplastes, has been isolated by activity guided fractionation and further structurally characterised by techniques such as FTIR, NMR and LC MS/MS. Further enzyme kinetics, isothermal titration calorimetry and molecular docking methods were used in order to get a better understanding of enzyme-ligand interactions. This exploration suggests its worthiness as a lead molecule for the development of a better anti-inflammatory drug. Its high structure-activity resemblance to cuminaldehyde from cumin seeds, which is earlier reported as a LOX inhibitor, is also established. [ABSTRACT FROM AUTHOR]

Head and neck malignancies have always been challenging for the clinician, both with regards to locoregional control and distant metastasis. Aggressive approaches translate to an acceptable locoregional control, but distant failures pose a dilemma. Newer, sophisticated, imaging modalities have helped in early diagnosis of solitary metastasis, and in turn have opened up an array of interventional procedures, which to some extent improve the disease-free survival and quality of life, as was seen in the present case of locoregionally controlled advanced hypopharyngeal malignancy who presented with solitary distant metastasis. Still, diligent care needs to be taken not to aggravate the scenario with these interventions. [ABSTRACT FROM AUTHOR]

The effects of morin and nordihydroguaiaretic acid (NDGA), two plant secondary metabolites, on porcine pancreatic phospholipase A2(PLA2) were investigated by isothermal titration calorimetry (ITC) andin silicodocking analyses. The binding energies obtained for NDGA and morin from the ITC studies are − 6.36 and − 5.91 kcal mol− 1, respectively. Similarly, the glide scores obtained for NDGA and morin towards PLA2were − 7.32 and − 7.23 kcal mol− 1, respectively. Further the docked complexes were subjected to MD simulation in the presence of explicit water molecules to check the binding stability of the ligands in the active site of PLA2. The bound ligands make hydrogen bonds with the active site residues of the enzyme and coordinate bonds with catalytically important Ca2+ion. The binding of ligands at the active site of PLA2may also contribute to the reported anti-inflammatory properties of NDGA and morin. [ABSTRACT FROM AUTHOR]

Inhibition of leukotriene biosynthesis is considered to be one of the potential treatment strategies for controlling inflammation, respiratory diseases and many neurodegenerative disorders. Designing of specific functional inhibitors against Lipoxygenases (LOX) has got considerable attention due to its ability to block leukotriene biosynthesis. Molecular docking analysis of two indole derivatives such as indoleacetic acid (IAA) and indolebutyric acid (IBA) are reported here. Both compounds give glide scores better than that of protocatechuic acid and nitro catechol, the two known LOX inhibitors. From the enzyme kinetic analysis, it was revealed that IAA and IBA inhibit competitively. The IC50values determined for both IAA and IBA were 42.98 μM and 17.82 μM, respectively. The binding free energy of these compounds was determined using isothermal titration calorimetric assay and was found to be − 6.12 kcal/mol for IAA and − 7.84 kcal/mol for IBA. From the analysis, it can be concluded that both IAA and IBA might be useful as anti-inflammatory agents. [ABSTRACT FROM PUBLISHER]

Flavoenzymes have been extensively studied for their structural and mechanistic properties because they find potential application as industrial biocatalysts. They are attractive for biocatalysis because of the selectivity, controllability and efficiency of their reactions. Some of these enzymes catalyse the oxidative modification of protein substrates. Among them oxygenases (monoxoygenases and dioxygenases) are of special interest because they are highly entantio as well as regio-selective and can be used for oxyfunctionalisation. Dioxygenase enzymes catalyse oxygenation reactions in which both di-oxygen atoms are incorporated into the product. A dioxygenase enzyme purified from Aspergillus fumigatus MC8 was subjected to protein digestion followed by peptide sequencing. The sequence analysis of the peptide fragments resulted in identifying its match with that of an extracellular dioxygenase sequence from the same species of fungus existing in the protein database. The sequence was submitted to protein homology/analogy recognition engine online server for homology modelling and the 3D structure was predicted. Subsequently, the in silico studies of the enzyme–substrate (protein–ligand) interaction were carried out by using the method of molecular docking simulations wherein the modelled dioxygenase enzyme (protein) was docked with the substrates (ligands), catechin and epicatechin. [ABSTRACT FROM PUBLISHER]

Effect of shape and density on the energy transfer between metallic nanoparticles and semi conducting nanostructures was studied by observing the photoluminescence spectra using near field scanning optical microscope. The monolayers of gold nanoparticles, CdSe nanorods and composite with different number ratios were prepared using Langmuir Blodgett method. The spectra collected from the films with different number ratios of CdSe and gold shows a systematic variation of peak position and intensity as a function of number density of CdSe. The photoluminescence spectra collected from composite monolayer is blue shifted compared to the spectra from CdSe nanorods monolayer. Further we observed a blue shift in peak position and reduction emission intensity with respect to increase in the fraction of gold nanoparticles and surface density. We have provided explanation for the observed behavior in terms of strong exciton-plasmon interactions in the compact hybrid monolayers. [ABSTRACT FROM AUTHOR]

Arrays of quantum dots and hybrid arrays of semiconducting quantum dots and metallic nanoparticles have wide range of potential applications from nanophotonics to quantum information processing. Creating such arrays with well-defined morphology and order over a large area is a challenge. We present a reliable method for constructing such arrays using simple self assembly technique. The reliability of the method is verified using AFM. The emission properties of such system are studied using high resolution imaging techniques and we have given the possible explanation for the observed phenomena. [ABSTRACT FROM AUTHOR]

Optical properties of polymer capped gold nanoparticles of various sizes (diameter 3–6 nm) have been studied. We present a new scheme to extract size dependent variation of total dielectric function of gold nanoparticles from measured UV-Vis absorption data. The new scheme can also be used, in principle, for other related systems as well. We show how quantum effect, surface atomic co-ordination and polymer-nanoparticle interface morphology leads to a systematic variation in interband part of the dielectric function of gold nanoparticles, obtained from the analysis using our new scheme. Careful analysis enables identification of the possible changes to the electronic band structure in such nanoparticles. [ABSTRACT FROM AUTHOR]

The galactose-specific lectin from the seeds of Butea monosperma has been crystallized by the hanging-drop vapour-diffusion technique. The crystals belonged to space group P1, with unit-cell parameters a = 78.45, b = 78.91, c = 101.85 Å, α = 74.30, β = 76.65, γ = 86.88°. X-ray diffraction data were collected to a resolution of 2.44 Å under cryoconditions (100 K) using a MAR image-plate detector system mounted on a rotating-anode X-ray generator. Molecular-replacement calculations carried out using the coordinates of several structures of legume lectins as search models indicate that the galactose-specific lectin from B. monosperma forms an octamer. [ABSTRACT FROM AUTHOR]