Improvement of corrosion resistance of PEO coated dissimilar Ti/Mg0.6Ca couple

With the growing demand for weight reduction,the application of joint lightweight structural materials is increasing.Magnesium alloys feature low density,high specific strength and good formability,offering significant advantages for fuel efficiency and load capacity.Combined with Ti,a dissimilar Ti/Mg composite material provides great flexibility combining the properties of each material.However,because of the great differences in chemical and electrochemical properties between Mg and Ti,it is imperative to address the galvanic corrosion problem of such dissimilar Ti/Mg components.This work presents an investigation of the PEO processing of sintered Ti/Mg0.6Ca couples,aiming to improve the corrosion resistance of such dissimilar alloy combinations using a phosphate-aluminate electrolyte.The results show that uniform and continuous coatings can be formed on the dissimilar Ti/Mg0.6Ca couple.The coating mainly contains MgO and MgAl_(2)O_(4)on the Mg0.6Ca side,and Al_(2)TiO_(5)is the dominant phase on the Ti side.The work also took advantage of synchrotron X-ray computed tomography(CT)scanning to achieve 3D reconstruction of the coating morphology,which can be a fast method to assess the porosity and compactness of the coating and further predict the coating corrosion resistance.The coating effectively improved the corrosion resistance of the dissimilar Ti/Mg0.6Ca couple.

Traditional Herbal Medicines Against CNS Disorders from Bangladesh

The majority of the population in Bangladesh uses traditional plant-based medicines to manage various ailments,including central nervous system(CNS)disorders.This review presents ethnobotanical information and relevant scientific studies on plants used in traditional healthcare for the management of various CNS disorders in Bangladesh.The information on the medicinal plants of Bangladesh effective against CNS disorders published in scientific journals,books,and reports was com-piled from different electronic databases using specific key words.The present article provides comprehensive information on a total of 224 medicinal plant species belonging to 81 families used for the treatment of CNS disorders by the various peoples of Bangladesh.In total,we reviewed more than 290 relevant papers.In this study,leaves were found as the most often used plant organ,followed by roots,fruits,whole plants,barks,seeds,stems,rhizomes,and flowers.The Fabaceae family contributes the highest number of used species,followed by Rubiaceae,Lamiaceae,Cucurbitaceae,Vitaceae,Euphorbiaceae,Malvaceae,and Zingiberaceae.The most frequently used species(in decreasing order)are Asparagus racemosus,Centella asiatica,Stephania japonica,Aegle marmelos,Coccinia grandis,Tabernaemontana divaricata,Bacopa monnieri,Abroma augusta,and Scoparia dulcis.This review may serve as a starting point for a rational search for neuroactive natural products against CNS disorders within the Flora of Bangladesh.

Active Thermal Control for Delaying Maintenance of Power Electronics Converters

Several studies have reported about power semiconductors and capacitors being the most sensitive components in power converters.The lifetime of these devices is associated with the mission profile and the resulting temperature profile.For preventing failures,it is of interest to estimate the Remaining Useful Lifetime(RUL)and several condition monitoring methods have been proposed for this purpose.Moreover,modular power converters consist of a high number of components and methods have been proposed to reduce the thermal stress and therefore extend the lifetime of a system with software,referred to as active thermal control.For power converters with limited accessibility,the RUL detected by the condition monitoring system may not fit to the scheduled maintenance of the system and devices may still have a significant RUL when their replacement is scheduled.Therefore,this work proposes to control the stress of the most deteriorated components in the system such that the failure probability of multiple building blocks is equalized when the next maintenance is scheduled.Moreover,this concept is proposed to extend the time to the next maintenance and reduce the number of maintenance instances without affecting the mean lifetime of the system.

Deteriorated corrosion performance of micro-alloyed Mg-Zn alloy after heat treatment and mechanical processing

The corrosion performances of the as-cast and solution-treated Mg-0.5Zn samples were investigated in 0.9%Na Cl solution and compared.From the electrochemical measurement results and corrosion morphology observations,it is found that the corrosion resistance of Mg-0.5Zn deteriorated with the extension of solution treatment duration.The main reason was the formation of Fe-Si precipitates with higher Fe concentrations during heat treatment.The Fe-Si precipitates,especially the ones with high Fe contents influenced the corrosion initiation and propagation significantly.In regard of corrosion performance,the solution-treated and then extruded sample was also performing not as good as the cast and then directly extruded sample.

First record of stable isotopes(δ^(13)C, δ^(18)O) and element ratios(Mg/Ca, Sr/Ca) of Middle to Late Jurassic belemnites from the Indian Himalayas and their potential for palaeoenvironmental reconstructions

Middle to Late Jurassic belemnites from the Spiti and Zanskar valleys in the Indian Himalayas were used for stable isotope(δ^(13)C, δ^(18)O) and element(Mg/Ca, Sr/Ca) analyses. Although the Himalayan orogeny deformed and altered a large portion of the collected fossils, cathodoluminescence and scanning electron microscopy in combination with analyses of iron and manganese contents allowed the identification of belemnites believed to still retain their original chemical composition. Results indicate a long-term temperature decrease from the Middle Callovian–Oxfordian to the Tithonian, which is proposed to have been caused by a concomitant drift of eastern Gondwana into higher palaeolatitudes. Reconstructed absolute temperatures depend on the used equation and assumed δ^(18)O value of seawater, but most likely varied between 17.6 ℃ to 27.6℃ in the Kimmeridgian and Tithonian with average values between 22 ℃ to 24 ℃. This way, temperatures were similar to slightly warmer than today at comparable latitudes. The reconstruction of absolute temperatures for the Middle Callovian–Oxfordian was hindered by a larger number of poorly preserved belemnites representing this time interval.

Conductance of a single molecule C_(60)-SnPc heterojunction

Geometries of molecule-molecule interfaces strongly influence the current passing from one molecule to another. The contact conductance of molecule-molecule junctions which consist of fullerene and tin phthalocyanine molecules is investigated with a low-temperature scanning tunneling microscope. Two types of molecules are deposited onto Cu(111). Fullerene molecules are transferred to tips through controlled contact of STM tips on molecules. The molecule-molecule junctions are formed by approaching fullereneterminated tips to tin phthalocyanine molecules on Cu(111). Our experimental method can be extended to study the intermolecular charge transport of a range of molecular junctions.

Electric-field driven stability control of skyrmions in an ultrathin transition-metal film

To realize future spintronic applications with magnetic skyrmions—topologically nontrivial swirling spin structures—it is essential to achieve efficient writing and deleting capabilities of these quasi-particles.Electric-field assisted nucleation and annihilation is a promising route,however,the understanding of the underlying microscopic mechanisms is still limited.Here,we show how the stability of individual magnetic skyrmions in an ultrathin transition-metal film can be controlled via external electric fields.We demonstrate based on density functional theory that it is important to consider the changes of all interactions with electric field,i.e.,the pair-wise exchange,the Dzyaloshinskii–Moriya interaction,the magnetocrystalline anisotropy energy,and the higher-order exchange interactions.The energy barriers for electric-field assisted skyrmion writing and deleting obtained via atomistic spin simulations vary by up to a factor of three more than the variations of the interactions calculated from first-principles.This surprising effect originates from the electric-field dependent size of metastable skyrmions at a fixed magnetic field.The large changes in lifetimes allow the possibility of electric-field assisted thermally activated writing and deleting of skyrmions.

Millimeter gap contrast as a probe for turbulence level in protoplanetary disks

Turbulent motions are believed to regulate angular momentum transport and influence dust evolution in protoplanetary disks.Measuring the strength of turbulence is challenging through gas line observations because of the requirement for high spatial and spectral resolution data,and an exquisite determination of the temperature.In this work,taking the well-known HD 163296 disk as an example,we investigated the contrast of gaps identified in high angular resolution continuum images as a probe for the level of turbulence.With self-consistent radiative transfer models,we simultaneously analyzed the radial brightness profiles along the disk major and minor axes,and the azimuthal brightness profiles of the B67 and B100 rings.By fitting all the gap contrasts measured from these profiles,we constrained the gas-to-dust scale height ratioΛto be 3.0^(+0.3)_(−0.8),1.2^(+0.1)_(−0.1),and≥6.5 for the D48,B67,and B100 regions,respectively.The varying gas-to-dust scale height ratios indicate that the degree of dust settling changes with radius.The inferred values forΛtranslate into a turbulence level of α_(turb)<3×10^(−3) in the D48 and B100 regions,which is consistent with previous upper limits set by gas line observations.However,turbulent motions in the B67 ring are strong with α_(turb)∼1.2×10^(−2).Due to the degeneracy betweenΛand the depth of dust surface density drops,the turbulence strength in the D86 gap region is not constrained.