Identification and Structure Elucidation of a Novel Antifungal Compound Produced by Pseudomonas aeruginosa PGPR2 Against Macrophomina phaseolina

Pseudomonas aeruginosa PGPR2 was found to protect mungbean plants from charcoal rot disease caused by Macrophomina phaseolina. Secondary metabolites from the culture supernatant of P. aeruginosa PGPR2 were extracted with ethyl acetate and the antifungal compound was purified by preparative HPLC using reverse phase chromatography. The purified compound showed antifungal activity against M. phaseolina and other phytopathogenic fungi (Fusarium sp., Rhizoctonia sp. Alternaria sp., and Aspergillus sp.). The structure of the purified compound was determined using ¹H, ¹³C, 2D NMR spectra and liquid chromatography-mass spectrometry (LC-MS). Spectral data suggest that the antifungal compound is 3,4-dihydroxy-N-methyl-4-(4-oxochroman-2-yl)butanamide, with the chemical formula C₁₄H₁₇NO₅ and a molecular mass of 279. Though chemically synthesized chromanone derivatives have been shown to have antifungal activity, we report for the first time, the microbial production of a chromanone derivative with antifungal activity. This ability of P. aeruginosa PGPR2 makes it a suitable strain for biocontrol.     

Influence of fluorine substitution on the properties of CdO nanocluster : a DFT approach

Fluorine substituted cadmium oxide (Cd _n O _n?1F) cluster for n = 2–6 of linear, ring and three dimensional structures were studied using B3LYP exchange correlation function with LanL2DZ as basis set. Different isomers were optimized to obtain structural stability and various parameters such as dipole moment, HOMO–LUMO gap, ionization potential, electron affinity, stability factor, binding energy, vibrational studies and optical absorption were studied and reported. The stability of the cluster depends on the binding energy and vibrational intensity.     

30pi aromatic meso-substituted heptaphyrin isomers: syntheses,characterization, and spectroscopic studies

The syntheses of new aromatic 30pi heptaphyrins either through a [5 + 2] or a [4 + 3] acid-catalyzed condensation and oxidative coupling reactions of easily available and air-stable precursors are reported. The methodology followed is not only simple and efficient but also allows synthesis of a range of heptaphyrins with different heteroatoms in the core. The oxidative coupling reactions of modified tripyrranes 11 and tetrapyrranes 12 were found to be dependent on the acid concentration used and as well as the substituents present on the meso position. The change of meso aryl substituents in 11 and 12 to meso mesityl substituents gave a new heptaphyrin 18. The structural characterization has been done with extensive 1H and 2D NMR studies. The heptaphyrins reported here show rich structural diversity when the connections of the heterocyclic rings are altered, and accordingly, one ring and two ring inversions have been observed. By a judicious choice of the precursors it has been possible to control the site of ring inversion either in the bithiophene unit or in the tripyrrane unit. Theoretical calculations performed on three different heptaphyrins, 4, 5, and 17, also reveal that the inverted structures are approximately 35-40 kJ lower in energy relative to the corresponding noninverted structures. Furthermore, one of the heptaphyrins 10c shows the presence of two conformers in solution in the ratio 1:2 and no interconversion between the conformers have been observed in the temperature range of 343-228 K. On protonation, the aromaticity and the ring inversions are retained and the deltadelta values vary in the range 10.07-20.59 ppm. The energies of the Soret maxima and the HOMO-LUMO gap vary linearly with the increase in pi electrons further justifying the aromatic nature of the heptaphyrins.     

Bioactive mono/bis (carboxyamide) based Co (II), Ni (II) and Cu (II) complexes: Synthesis,Characterization, DNA binding and Anticancer Potentials

Bioactive carboxyamide ligated Cu^II ( 1 ), Co^II ( 2 ) and Ni^II ( 3 ) complexes have been synthesized and characterized using various physico‐chemical techniques. In particular, the occurred slightly distorted square planar geometry in complex 1 was confirmed by single X‐ray crystal structure. Their ( 1 , 2 and 3 ) potential interactions with herring sperm DNA (HS‐DNA) have been investigated using spectral and electrochemical techniques. All these studies suggested that the complex 1 could partially penetrated in the sugar phosphate backbone and stacked in between the DNA base pairs, while the other complexes 2 & 3 could bound only on the grooves of HS‐DNA due to their bi‐ligated architecture around the metal centre. The potent cytotoxicity of L and its complexes 1–3 was also evaluated against AGS human gastric cancer cells. Hoechst 33342/PI double staining images revealed that the complexes significantly induced cell death through apoptosis. In vivo administration of complex 1 remarkably inhibits the tumor growth in male Swiss albino mice, moreover it did not show any hepatotoxicity in mice. All these observed results suggested that these complexes may utilized as good conventional therapeutic agents in the near feature after a series of biological assessments.     

Nanostructured ZnO thin film for hydrogen peroxide sensing

A thin film of zinc oxide (ZnO) was deposited over the surface of a glass substrate by spray pyrolysis technique. To obtain ZnO thin film with nano-grains in this process, the substrate temperature was optimized and fixed at 503 K. Zinc acetate dihydrate was used as a precursor at an optimal concentration of 0.05 M. The structural and morphological properties of the film were investigated using X-ray Diffraction (XRD) and Field Emission–Scanning Electron Microscopy (FE–SEM), respectively. The peaks in the XRD pattern, confirmed the polycrystalline nature of the film with hexagonal wurtzite structure. Purity of the film has been confirmed through Energy Dispersive X-ray analysis (EDAX). Further the sensing behavior of the film was studied for various concentrations of hydrogen peroxide (H₂O₂) at optimized operating temperatures of 323 and 373 K. The nanostructured ZnO film exhibited good sensitivity in the range of 500 and rapid response–recovery time of 30–60 s, respectively, towards lower concentrations of H₂O₂.     

An Efficient DenseNet-Based Deep Learning Model for Malware Detection

Recently, there has been a huge rise in malware growth, which creates a significant security threat to organizations and individuals. Despite the incessant efforts of cybersecurity research to defend against malware threats, malware developers discover new ways to evade these defense techniques. Traditional static and dynamic analysis methods are ineffective in identifying new malware and pose high overhead in terms of memory and time. Typical machine learning approaches that train a classifier based on handcrafted features are also not sufficiently potent against these evasive techniques and require more efforts due to feature-engineering. Recent malware detectors indicate performance degradation due to class imbalance in malware datasets. To resolve these challenges, this work adopts a visualization-based method, where malware binaries are depicted as two-dimensional images and classified by a deep learning model. We propose an efficient malware detection system based on deep learning. The system uses a reweighted class-balanced loss function in the final classification layer of the DenseNet model to achieve significant performance improvements in classifying malware by handling imbalanced data issues. Comprehensive experiments performed on four benchmark malware datasets show that the proposed approach can detect new malware samples with higher accuracy (98.23% for the Malimg dataset, 98.46% for the BIG 2015 dataset, 98.21% for the MaleVis dataset, and 89.48% for the unseen Malicia dataset) and reduced false-positive rates when compared with conventional malware mitigation techniques while maintaining low computational time. The proposed malware detection solution is also reliable and effective against obfuscation attacks.