Biologically active metabolites from fungi, 19: new isocoumarins and highly substituted benzoic acids from the endophytic fungus, Scytalidium sp

Six known metabolites, two new isocoumarins 4 and 8, and one new highly substituted benzoic acid derivative 9 were isolated from the ethyl acetate culture extract of a fungal endophyte, Scytalidium sp. In addition, another new benzoic acid 10 with an unusual 1,2-dicarbonyl side chain was indirectly identified from its methylated derivatives 10a-10d.     

Relativistic electronic structures of the Ag2 and Au2 molecules

The relativistic electronic structures of the Ag₂ and Au₂ molecules have been calculated using the recently developed self-consistent-field Xα Dirac-scattered-wave programs. Calculations have been carried out for transition energies and ionization potentials for selected molecular orbitals. The results indicate a large degree of s-d hybridization in the ground state of the Au₂ molecule. The calculations are in good agreement with other theoretical work and with existing experimental results.     

A Comprehensive Review with Updated Future Perspectives on the Ethnomedicinal and Pharmacological Aspects of Moringa oleifera

Moringa oleifera is an ancient remedy plant, known as the miraculous plant due to its many prominent uses and significant health benefits. It is a nutrient-rich plant, with exceptional bioactive compounds, such as polyphenols that possess several medicinal properties. Many significant studies have been carried out to evaluate the ethnomedicinal and pharmacological properties of M. oleifera in various applications. Therefore, this comprehensive review compiles and summarizes important findings from recent studies on the potential properties of different parts of M. oleifera. The pharmacological properties of M. oleifera have been studied for various potential biological properties, such as cardio-protective, anti-oxidative, antiviral, antibacterial, anti-diabetic and anti-carcinogenic effects. Therefore, the potential of this plant is even more anticipated. This review also highlights the safety and toxicity effects of M. oleifera treatment at various doses, including in vitro, in vivo and clinical trials from human studies.     

Increasing the hydrophilicity of star‐shaped amphiphilic co‐networks by using of PEG and dendritic s‐PCL cross‐linkers

New hyperbranched hydrophobic cross‐linkers with peripheral azide groups were synthesized as follows: First, star‐shaped polycaprolactones (sPCL) were synthesized by ring‐opening polymerization of caprolactone in the presence of pentaerythritol and tin (II) octoate. In the next step, sequential acrylation, Micheal addition, tosylation, and azidation by acryloyl chloride, diethanol amine, tosyl chloride, and sodium azide were respectively exploited to synthesize azide‐functionalized hyperbranched star‐shaped polycaprolactones which were named sPCL‐acrylate‐diethanolamine‐azide (sPCL‐AC‐DEA‐N₃) and sPCL‐acrylate‐diethanolamine‐acrylate‐diethanolamine‐azide (sPCL‐AC‐DEA‐AC‐N₃). All steps were thoroughly characterized by FT‐IR and ¹H NMR spectroscopy. The GPC analysis showed that the molecular weight of sPCL increased after two azide functionalizations. Amphiphilic hydrogels based on sPCL‐AC‐DEA‐N₃ (M_n = 8130 g/mol) and sPCL‐AC‐DEA‐AC‐N₃ (M_n = 10112 g/mol) with linear alkyne‐terminated polyethylene glycols (PEG) (M_n = 2000, 4000, and 6000 g/mol) were synthesized through click coupling between azide and alkyne groups. In both hydrogels, the swelling ratio increased by increasing the molecular weight of PEG. The obtained results showed that the branching of the cross‐linker, significantly affected the swelling ratio of hydrogels. For instance, the swelling ratio of sPCL‐AC‐DEA‐AC‐N₃ and PEG‐6000 (Q = 900) was higher than sPCL‐AC‐DEA‐N₃ and PEG‐6000 (Q = 600). Despite the high cross‐linking density of sPCL‐AC‐DEA‐AC‐DEA‐N₃–based hydrogels, the amount of released theophylline was higher than sPCL‐AC‐DEA‐N₃–based hydrogels, due to the high content of PEG in these hydrogels.     

High Speed Video Camera and Electrical Signal Analyses of Arcs Behavior in a 3-Phase AC Arc Plasma Torch

A 3-phase AC plasma torch has been developed and aims at overcoming some limits of the classical DC torches in terms of efficiency, cost and reliability. However, the arc behavior in 3-phase plasma torch remains poorly explored. This paper is dedicated to the high speed video camera at 100,000 frames per second and electrical signal analyses of arcs behavior in a 3-phase AC arc plasma torch. First, a reference case at 150 A, in nitrogen as working gas, has been deeply analyzed. Afterwards, a parametric study based on current and inter-electrode gap has been carried out. Results show that only one arc can exist at a given time and arcs rotate by switching from a pair of electrodes to another one, following the maximal electrical gap potential. However, a particular “abnormal” arc behavior was sometimes observed. Indeed, the arc motion within the inter-electrode gap increases the heat exchange and stabilizes the 3-phase discharge whereas the system is unbalanced when the arc is in the periphery. The analysis highlights that the arc motion is strongly influenced by the electrode jet velocity and repulsive Lorentz forces. The parametric study shows that the current increases both jet velocity and arc discharge stability. Elsewhere, the increase of the inter-electrode gap can also stabilizes the electrical 3-phase arc discharge. Furthermore, the correlation between arc motion and current waveform is highlighted. This work is likely to open the way toward a better understanding of 3-phase discharges in the perspective of their further optimization.     

Novel precursors for boron nanotubes: the competition of two-center and three-center bonding in boron sheets

We present a new class of boron sheets, composed of triangular and hexagonal motifs, that are more stable than structures considered to date and thus are likely to be the precursors of boron nanotubes. We describe a simple and clear picture of electronic bonding in boron sheets and highlight the importance of three-center bonding and its competition with two-center bonding, which can also explain the stability of recently discovered boron fullerenes. Our findings call for reconsideration of the literature on boron sheets, nanotubes, and clusters.     

A neural network to solve quadratic programming problems with fuzzy parameters

In this paper, a representation of a recurrent neural network to solve quadratic programming problems with fuzzy parameters (FQP) is given. The motivation of the paper is to design a new effective one-layer structure neural network model for solving the FQP. As far as we know, there is not a study for the neural network on the FQP. Here, we change the FQP to a bi-objective problem. Furthermore, the bi-objective problem is reduced to a weighting problem and then the Lagrangian dual is constructed. In addition, we consider a neural network model to solve the FQP. Finally, some illustrative examples are given to show the effectiveness of our proposed approach.     

Self-trapped excitons in silicon dioxide: mechanism and properties

Irradiating silica produces self-trapped excitons (STEs) that spontaneously create atomic-scale distortions on which they localize themselves. Despite enduring interest in STEs and subsequent defects in this key technological material, the trapping mechanism and geometry remain a mystery. Our ab initio study of STEs in alpha-quartz using a many-electron Green's function approach answers both questions. The STE comprises a broken O-Si bond with the hole localized on the defected oxygen and the electron on the defected silicon atom in a planar sp2 conformation. The results further explain quantitatively the measured STE spectra.