Electrodeposition of CuGaSe<Subscript>2</Subscript> and CuGaS<Subscript>2</Subscript> thin films for photovoltaic applications

CuGaSe₂ and CuGaS₂ polycrystalline thin film absorbers were prepared by one-step electrodeposition from an aqueous electrolyte containing CuCl₂, GaCl₃ and H₂SeO₃. The pH of the solution was adjusted to 2.3 by adding HCl and KOH. Annealing improved crystallinity of CuGaSe₂ and further annealing in sulphur atmosphere was required to obtain CuGaS₂ layers. The morphology, topography, chemical composition and crystal structure of the deposited thin films were analysed by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy and X-ray diffraction, respectively. X-Ray diffraction showed that the as-deposited CuGaSe₂ film exhibited poor crystallinity, but which improved dramatically when the layers were annealed in forming gas atmosphere for 40 min. Subsequent sulphurization of CuGaSe₂ films was performed at 400 °C for 10 min in presence of molecular sulphur and under forming gas atmosphere. The effect of sulphurization was the conversion of CuGaSe₂ into CuGaS₂. The formation of CuGaS₂ thin films was evidenced by the shift observed in the X-ray diffraction pattern and by the blue shift of the optical bandgap. The bandgap of CuGaSe₂ was found to be 1.66 eV, while for CuGaS₂ it raised up to 2.2 eV. A broad intermediate absorption band associated to Cr and centred at 1.63 eV was observed in Cr-doped CuGaS₂ films.     

Efficient one-pot selective reduction of esters in β-ketoesters using LiHMDS and lithium aluminium hydride

The ester functionality in β-keto esters is selectively reduced in one-pot, first by enolization using LiHMDS and then reduced with lithium aluminium hydride. This method produces β-hydroxyl ketones from the corresponding β-keto esters in high yield.     

Gracilone,a new sesquiterpene lactone from Tanacetum gracile (Tansies)

The methanolic extract of the Tanacetum gracile afforded the isolation of new sesquiterpene lactone, named gracilone (1) along with four known compounds as 14α-taraxeran-3-one (2), 14α-taraxeran-3-ol (3), apigenin (4) and β-sitosterol (5). The structure of compound 1 was elucidated on the basis of 1D, 2D NMR and MS spectroscopic analysis. Antimicrobial, antioxidant and anticancer activities of all compounds were evaluated, from which gracilone (1) showed a moderate antibacterial activity, while apigenin (4) showed comparatively more antibacterial activity against both gram­positive and gram­negative tested strains.     

Elucidating the Glucokinase Activating Potentials of Naturally Occurring Prenylated Flavonoids: An Explicit Computational Approach

Glucokinase activators are considered as new therapeutic arsenals that bind to the allosteric activator sites of glucokinase enzymes, thereby maximizing its catalytic rate and increasing its affinity to glucose. This study was designed to identify potent glucokinase activators from prenylated flavonoids isolated from medicinal plants using molecular docking, molecular dynamics simulation, density functional theory, and ADMET analysis. Virtual screening was carried out on glucokinase enzymes using 221 naturally occurring prenylated flavonoids, followed by molecular dynamics simulation (100 ns), density functional theory (B3LYP model), and ADMET (admeSar 2 online server) studies. The result obtained from the virtual screening with the glucokinase revealed arcommunol B (−10.1 kcal/mol), kuwanon S (−9.6 kcal/mol), manuifolin H (−9.5 kcal/mol), and kuwanon F (−9.4 kcal/mol) as the top-ranked molecules. Additionally, the molecular dynamics simulation and MM/GBSA calculations showed that the hit molecules were stable at the active site of the glucokinase enzyme. Furthermore, the DFT and ADMET studies revealed the hit molecules as potential glucokinase activators and drug-like candidates. Our findings suggested further evaluation of the top-ranked prenylated flavonoids for their in vitro and in vivo glucokinase activating potentials.     

Integrated Machine Learning and Chemoinformatics-Based Screening of Mycotic Compounds against Kinesin Spindle ProteinEg5 for Lung Cancer Therapy

Among the various types of cancer, lung cancer is the second most-diagnosed cancer worldwide. The kinesin spindle protein, Eg5, is a vital protein behind bipolar mitotic spindle establishment and maintenance during mitosis. Eg5 has been reported to contribute to cancer cell migration and angiogenesis impairment and has no role in resting, non-dividing cells. Thus, it could be considered as a vital target against several cancers, such as renal cancer, lung cancer, urothelial carcinoma, prostate cancer, squamous cell carcinoma, etc. In recent years, fungal secondary metabolites from the Indian Himalayan Region (IHR) have been identified as an important lead source in the drug development pipeline. Therefore, the present study aims to identify potential mycotic secondary metabolites against the Eg5 protein by applying integrated machine learning, chemoinformatics based in silico-screening methods and molecular dynamic simulation targeting lung cancer. Initially, a library of 1830 mycotic secondary metabolites was screened by a predictive machine-learning model developed based on the random forest algorithm with high sensitivity (1) and an ROC area of 0.99. Further, 319 out of 1830 compounds screened with active potential by the model were evaluated for their drug-likeness properties by applying four filters simultaneously, viz., Lipinski’s rule, CMC-50 like rule, Veber rule, and Ghose filter. A total of 13 compounds passed from all the above filters were considered for molecular docking, functional group analysis, and cell line cytotoxicity prediction. Finally, four hit mycotic secondary metabolites found in fungi from the IHR were screened viz., (−)-Cochlactone-A, Phelligridin C, Sterenin E, and Cyathusal A. All compounds have efficient binding potential with Eg5, containing functional groups like aromatic rings, rings, carboxylic acid esters, and carbonyl and with cell line cytotoxicity against lung cancer cell lines, namely, MCF-7, NCI-H226, NCI-H522, A549, and NCI H187. Further, the molecular dynamics simulation study confirms the docked complex rigidity and stability by exploring root mean square deviations, root mean square fluctuations, and radius of gyration analysis from 100 ns simulation trajectories. The screened compounds could be used further to develop effective drugs against lung and other types of cancer.     

Inverse seesaw in NMSSM and 126 GeV Higgs boson

We consider extensions of the next-to-minimal supersymmetric model (NMSSM) in which the observed neutrino masses are generated through a TeV scale inverse seesaw mechanism. The new particles associated with this mechanism can have sizable couplings to the Higgs field which can yield a large contribution to the mass of the lightest CP-even Higgs boson. With this new contribution, a 126 GeV Higgs is possible along with order of 200 GeV masses for the stop quarks for a broad range of tan β. The Higgs production and decay in the diphoton channel can be enhanced due to this new contribution. It is also possible to solve the little hierarchy problem in this model without invoking a maximal value for the NMSSM trilinear coupling and without severe restrictions on the value of tan β.     

Induced-gravity GUT-scale Higgs inflation in supergravity

Models of induced-gravity inflation are formulated within Supergravity employing as inflaton the Higgs field which leads to a spontaneous breaking of a \(U(1)_{B-L}\) symmetry at \(M_\mathrm{GUT}=2\cdot 10^{16}~{\mathrm{GeV}}\). We use a renormalizable superpotential, fixed by a U(1) R symmetry, and Kähler potentials which exhibit a quadratic non-minimal coupling to gravity with or without an independent kinetic mixing in the inflaton sector. In both cases we find inflationary solutions of Starobinsky type whereas in the latter case, others (more marginal) which resemble those of linear inflation arise too. In all cases the inflaton mass is predicted to be of the order of \(10^{13}~{\mathrm{GeV}}\). Extending the superpotential of the model with suitable terms, we show how the MSSM \(\mu \) parameter can be generated. Also, non-thermal leptogenesis can be successfully realized, provided that the gravitino is heavier than about \(10~{\mathrm{TeV}}\).     

Surface chemistry of Fe2O3 nanoparticles on ultrathin oxide layers on Si and Ge

In this paper, we report on a comparative study of the effect of Fe₂O₃ nanoparticles (NP), introduced onto a thin oxide layer formed on silicon and germanium surfaces, on the thermal decomposition pathway of the individual oxide layers. On both the surfaces, NP of Fe₂O₃ undergo a reduction reaction through a bonding partner change reaction, where the oxygen atoms change from Fe to Si or Ge. On both the surfaces, annealing results in the conversion of the suboxide-like species to dioxide-like species (SiO_x to SiO₂ and GeO_x to GeO₂ respectively for Si and Ge surfaces), until the oxide layer decomposes following the desorption of the respective monoxide species (SiO and GeO). Both the Si and Ge corelevels show a larger chemical shift (4.1 and 3.51 eV in Si 2p and Ge 3d corelevels, respectively) for the as-prepared oxide samples with the NP, at room temperature compared to that without the NP (3.7 and 3.4 eV), indicating a catalytic enhancement of the dioxide formation. Selective formation of silicon oxides leads to encapsulation of the nanoparticles and acts like a protective layer, preventing the oxidation of Fe.     

Anisotropy of the Reynolds stresses in a turbulent boundary layer on a rough wall

The measured anisotropy invariants of the Reynolds stress tensor in a self-preserving rough wall turbulent boundary layer indicate that the anisotropy is significantly smaller than in a smooth wall layer.RAA is grateful to Dr. P. Spalart for the DNS data. The support of the Australian Research Council is acknowledged.