Ultra-soft magnetic properties and giant magneto-impedance of Co68Fe4.5Si12·5B15

We have prepared an amorphous Co₆₈Fe_4.5Si_l2·₅B₁₅ alloy, annealed it in the temperature range of 200-580 °C and carried out a detailed study of the effect of crystallization on its magnetic properties. When annealed in an optimized condition, a very high value of initial permeability of the order of ~ 10⁴ has been attained in association with a drastic decrease of the relative loss factor. This change of properties has been attributed due to the formation of nanograins of fcc Co and Co₃B, as identified by X-ray diffraction and differential thermal analysis. The activation energy of crystallization is 4.18 eV. Hysteresis loop parameters were then extensively studied for the samples annealed at various temperatures. Finally, a very high value of giant magneto-impedance (GMI)—which is a characteristic property of Co-based amorphous alloys derived from well defined anisotropy axis (around 375) has been observed for a sample annealed at 380 °C.     

Oxidation of primary aliphatic and aromatic aldehydes with difluoro(aryl)-λ3-bromane

Oxidation of primary aliphatic aldehydes with p-trifluoromethylphenyl(difluoro)-λ(3)-bromane in dichloromethane at 0 °C afforded acid fluorides selectively in good yields, while that of aromatic aldehydes in chloroform at room temperature produced aryl difluoromethyl ethers. A larger migratory aptitude of aryl groups compared to primary alkyl groups during a 1,2-shift from carbon to an electron-deficient oxygen atom in bromane(III) Criegee-type intermediates will result in these differences in the reaction courses.     

Data analysis and prediction of the COVID-19 outbreak in the first and second waves for top 5 affected countries in the world

Nonlinear Dynamics - In this paper, we introduce a SEIATR compartmental model to analyze and predict the COVID-19 outbreak in the Top 5 affected countries in the world, namely the USA, India,...     

Electron-Transfer Reactions of Organosulfur Cation Radicals

Abstract

The thianthrene cation radical (Th^˙+) undergoes electron transfer in reactions with a number of azoalkanes. The oxidized azoalkanes then enter primarily into carbocation reaction pathways rather than the free radical pathways with which they are commonly associated. Examples are given with 1,1′-azoadamantane, phenylazotriphenylmethane, azotoluene, and azo-tertiary-butane. Reactions of Th^˙+ with Grignard agents also result, to varying extents, in electron transfer from the Grignard to Th^˙+. Here again carbocation chemistry is seen but particularly with solvent tetrahydrofuran, which polymerizes. The Grignard group may end up primarily as alkane (e.g., with t-butyl) or may also be trapped by Th^˙+ in the form of a 5-alkylthianthre-niumyl ion (e.g. with butyl). Possible mechanisms of reactions are discussed     

Structural insight into the anion–water cluster: stabilised by alcohol and carboxylic acid containing tripodal ligand

A new flexible N-bridged, unsymmetrical, water-soluble tripodal ligand (L) bearing alcohol and carboxylic acid groups has been synthesised and its solid-state interaction with anions has been investigated. The fully deprotonated ligand encapsulates a sodium cation in a half cryptand bowl-shaped cavity (1). The chloride complex 2, contains a cyclohexane-like water cluster incorporating ligand OH groups. However, complexes with bromide and nitrate (3 and 4) are dimeric. Tetrahedral clusters containing two water molecules and two anions were found in complexes 3 and 4. Perchlorate complex 5 forms perchlorate–methanol adducts. Complex 1 forms a hydrophilic cation–water channel and complexes 2–4 form anion–water channels between the hydrophobic layers of the naphthalene moieties. Complexes 2, 5 and 3, 4 are isostructural in nature having similar packing structures.     

Novel localized waves and interaction solutions for a dimensionally reduced (2 + 1)-dimensional Boussinesq equation from N-soliton solutions

Nonlinear Dynamics - The Boussinesq equation has been of considerable interest in coastal and ocean engineering models for simulating surface water waves in shallow seas and harbors, tsunami wave...     

A six-axis hybrid vibration isolation system using active zero-power control supported by passive weight support mechanism

This paper presents a six-degree-of-freedom hybrid vibration isolation system integrated with an active negative suspension, an active-passive positive suspension and a passive weight support mechanism. The aim of the research consists in maximizing the system and control performances, and minimizing the system development and maintenance costs. The vibration isolation system is, fundamentally, developed by connecting an active negative suspension realized by zero-power control in series with an active-passive positive suspension. The system could effectively isolate ground vibrations in addition to suppress the effect of on-board generated direct disturbances of the six-axis motions, associated with vertical and horizontal directions. The system is further reinforced by introducing a passive weight support mechanism in parallel with the basic system. The modified system with zero-power control allows simplified design of the isolation table without power consumption. It also offers enhanced performance on direct disturbance suppression and large payload supporting capabilities, without degrading transmissibility characteristics. A mathematical model of the system is presented and, therefore, analyzed to demonstrate that zero-compliance to direct disturbance could be generated by the developed system. Experimental demonstrations validate the proposed concept that exhibits high stiffness of the isolation table to static and dynamic direct disturbances, and good transmissibility characteristics against ground vibration. Further improvements of the vibration isolation system and the control system are discussed as well.     

Ligand-Enabled Double γ-C(sp3)−H Functionalization of Aliphatic Acids: One-Step Synthesis of γ-Arylated γ-Lactones

γ-methylene C(sp³)−H functionalization of linear free carboxylic acids remains a significant challenge. Here in we report a Pd(II)-catalyzed tandem γ-arylation and γ-lactonization of aliphatic acids enabled by a L,X-type CarboxPyridone ligand. A wide range of γ-arylated γ-lactones are synthesized in a single step from aliphatic acids in moderate to good yield. Arylated lactones can readily be converted into disubstituted tetrahydrofurans, a prominent scaffold amongst bioactive molecules.