Bistable perpendicular switching with in-plane spin polarization and without external fields

To-date, all experiments switching perpendicular magnetic anisotropy (PMA) materials with in-plane spin polarization require external B-fields. Here, in two approaches, it is shown that with Rashba-type in-plane spin polarization and PMA, bistable switching is achievable without external B  -fields, and at currents on the order of 10⁷ A/cm²${10}^7\text{A}/{\text{cm}}^2$, consistent with recent experiments. Utilization of PMA is primarily discussed, demonstrating the potential for two possibilities: (1) in-plane polarization as a ‘natural’ candidate for precessional switching and (2) bistable switching using a tilted anisotropy axis. Both are shown to lead to stable perpendicular switching without an external B-field, even though spin polarization is in-plane.     

Generation of sulfate radicals by supported ruthenium catalyst for phenol oxidation in water

In this study we report the preparation of RuO₂/Fe₃O₄@nSiO₂@mSiO₂ core–shell powder mesoporous catalyst for heterogeneous oxidation of phenol by peroxymonosulfate (PMS) as oxidant. The properties of this supported catalyst were characterized by SEM–EDS (scanning electron microscopy–energy dispersive X-ray spectroscopy), XRD (powder X-ray diffraction), TEM (transmission electron microscopy), and nitrogen adsorption–desorption. It is found that using ruthenium oxide-based catalyst is highly effective in activating PMS for related sulfate radicals. The effects of catalyst loading, phenol concentration, PMS concentration, reaction temperature, and reusability of the as-prepared catalyst on phenol degradation were investigated. In RuO₂/Fe₃O₄@nSiO₂@mSiO₂ mesoporous catalyst, Oxone (PMS) was effectively activated and 100 % phenol degradation occurred in 40 min. The magnetic RuO₂/Fe₃O₄@nSiO₂@mSiO₂ catalyst was facility separated from the solution by an external magnetic field. To regenerate the deactivated catalyst and improve its catalytic properties, three different methods involving annealing in air, washing with water, and applying ultrasonics were used. The catalyst was recovered thoroughly by heat treatment.     

Ab initio calculations of pKa values of some organic acids in aqueous solution

The acidity of different classes of organic compounds in aqueous solution has been calculated. The calculations are carried out at the SCF level with inclusion of entropic and thermochemical correction to yield free energies of dissociations.

The polarized continuum model is used to describe the solvent. The model furnishes pK_a values in relatively good agreement with experimental data. Scaling different parts of solvation energies provides a significant improvement in results and signifies the importance of balance of individual contributions from electrostatic, cavity, dispersion and repulsion interactions.     

A soluble polymer-supported triflating reagent: a high-throughput synthetic approach to aryl and enol triflates

[reaction: see text] The high-yielding synthesis and application of the first example of a polymer-supported reagent for the preparation of trifluoromethanesulfonates (triflates) is described. This new reagent efficiently triflates aryl alcohols and lithium enolates in high yield (>90%). A simple precipitation and filtration to remove the excess reagent and byproduct facilitate purification of the triflate products. The PEG-supported approach is highly efficient, as the PEG-supported byproduct can be quantitatively recovered and recycled into reagent 1.     

Calculations of pKa values of carboxylic acids in aqueous solution using density functional theory

With the specific aim of calculating the acidity equilibrium constant (K_a) of carboxylic acids in aqueous solution we investigated the solute-solvent interactions of these acids and their corresponding anions. The pK_a (−lg K_a) values have been calculated using density functional theory (DFT). The polarized continuum model (PCM) is used to describe the solvent. Using these methods, we successfully predicted the pK_as of 66 carboxylic acids in aqueous with the average error of 0.5 in pK_a units. Two different thermodynamic cycles have been studied. The theoretical values are in better agreement with the experimental results for those acids with moderate strength of acidity with the pK_a value higher than 3.     

Chemical synthesis of zinc oxide nanorods for enhanced hydrogen gas sensing

Zinc oxide(ZnO) nanorods are prepared using equimolar solution of zinc nitrate((Zn(NO3)2) and hexamethylenetetramine(C6H12N4) by the hydrothermal technique at 80 C for 12 h. Epitaxial growth is explored by X-ray diffraction(XRD) patterns, revealing that the ZnO nanorods have a hexagonal(wurtzite) structure. Absorption spectra of ZnO are measured by UV–visible spectrometer. The surface morphology is investigated by field emission scanning electron microscopy(FESEM). The synthesized ZnO nanorods are used for detecting the 150 C hydrogen gas with a concentration over 1000 ppm. The obtained results show a reversible response. The influence of operating temperature on hydrogen gas detecting characteristic of ZnO nanorods is also investigated.     

Adsorption of phenolic compounds from aqueous solutions using carbon nanoporous adsorbent coated with polymer

Phenolic compounds are a widespread class of water pollutants that are known to cause serious human health problems; and the demand for effective adsorbents for the removal of toxic compounds is increasing.In this work adsorption of phenol, resorcinol and p-cresol on mesoporous carbon material (CMK-1) and modified with polyaniline polymer (CMK-1/PANI) has been investigated in attempt to explore the possibility of using nanoporous carbon as an efficient adsorbent for pollutants. It was found that CMK-1/PANI exhibits significant adsorption for phenolic derivatives. Batch adsorption studies were carried out to study the effect of various parameters like adsorbent dose, pH, initial concentration and contact time. From the sorption studies it was observed that the uptake of resorcinol was higher than other phenolic derivatives. Freundlich and Langmuir adsorption isotherms were used to model the equilibrium adsorption data for phenolic compounds.     

Removal of naphthalene from petrochemical wastewater streams using carbon nanoporous adsorbent

Ordered mesoporous carbon, OMC, was synthesized using ordered mesoporous silica MCM-48 as hard template, the structural order and textural properties of the synthesized materials were studied by XRD, SEM, and nitrogen adsorption-desorption analysis. Adsorption of naphthalene over various porous adsorbents such as OMC, MCM-48, and commercial activated carbon was studied from solutions with different concentration at ambient temperature (25 ± 2 °C) and pH 7. The adsorption isotherms of naphthalene were in agreement with a Langmuir model, moreover, the uptake capacity of naphthalene followed the order: OMC > commercial activated carbon > mesoporous silica (MCM-48).     

Functionalization of silicon nanowires by iron oxide and copper for degradation of phenol

Research on Chemical Intermediates - Iron oxide (Fe3O4) and copper-functionalized silicon nanowires (SiNWs) from silicon powder mesh?<?500 with a spherical structure have been...