We grew ferromagnetic Fe4N films by molecular beam epitaxy on MgO(001), MgAl2O4(MAO)(001), SrTiO3(STO)(001), and CaF2(001) substrates, possessing the lattice spacing close to Si(001) plane. Highly ...oriented epitaxial growth was confirmed for the Fe4N films on the MgO, MAO, and STO by reflection high-energy electron diffraction and x-ray diffractions. The degree of orientation of the Fe4N film on the STO was the best among these samples. This was attributed to the smallest lattice mismatch of −2.8% between Fe4N(001) and STO(001). On the other hand, crystallinity of the Fe4N film on the CaF2(001) substrate was poor due to a very large lattice mismatch of −30% between Fe4N(001) and CaF2(001) arising from the unexpected epitaxial relationship as Fe4N(001)100 || CaF2(001)100. The saturation magnetization of the Fe4N films was approximately 1200emu/cm3 at room temperature for all the samples, and the magnetization easy axis was in-plane Fe4N100. We consider that STO is the suitable buffer layer for the growth of Fe4N on Si(001), hence to realize the Si-based spintronics devices using highly spin-polarized Fe4N.
•We grow Fe4N films by MBE on the insulators having lattice spacing close to Si(001).•Highly oriented epitaxial Fe4N films are grown on MgO, MAO, and STO(001) substrates.•STO might be the suitable buffer layer in order to grow Fe4N epitaxially on Si(001).•MS does not depend on the used substrates and huge MS was not observed.
•PG was transformed into α-HH in Na2SO4 solution.•Maleic acid inhibits the conversion of PG to α-HH.•α-HH evolves from whisker to short columnar crystal in the presence of maleic acid.•Maleic acid ...can preferentially adsorb on the (1 1 1) crystal plane of α-HH.
The control of crystal morphology is crucial to preparation of α-hemihydrate gypsum (α-HH). α-HH was prepared from phosphogypsum (PG) in Na2SO4 solution at different temperatures. The effect of maleic acid (C4H4O4) on the dehydration rate and growth behavior of α-HH was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the interactions of C4H4O4 molecule with the α-HH surface were studied using density functional theory (DFT) calculations. The results show that the increase in Na2SO4 concentration and solution temperature can shorten the dehydration time of PG. Maleic acid inhibits the conversion of PG to α-HH by prolonging the crystal growth period. α-HH crystals prefer to grow along the c-axis and present a long columnar crystal. With an increase in the maleic acid concentration from 0.00 to 5.76 mM, the morphology of α-HH evolves from a needle-like whisker to a short equiaxial crystal, and the corresponding aspect ratio decreases from 14.19 to 0.91. The calculation results indicate that the strong interactions between the C4H4O4 molecule and the (1 1 1) crystal plane of α-HH are largely attributable to the bonding of both the single-bond oxygen (O1) and double-bond oxygen (O2) in C4H4O4 with the Ca atoms of the (1 1 1) crystal plane and that the chemisorption of C4H4O4 can occur on the (1 1 1) crystal plane with the lowest adsorption energy of −201.65 kJ/mol. C4H4O4 adsorption on the (1 1 0) crystal plane is through a single O2Ca bond with an adsorption energy of −95.32 kJ/mol. The interaction between the (0 1 0) crystal plane and C4H4O4 is weak. It can be concluded that maleic acid can preferentially adsorb on the (1 1 1) crystal plane and retard crystal growth along the c-axis during the preparation of α-HH from PG.
The intrinsic bulk behavior of topological insulators (TI) is a key issue for their employment in future device applications. State of the art TIs predominantly suffer from large bulk charge carrier ...concentrations that mask their extraordinary surface states. In this paper we present the selective area growth of Bi2Te3 and Sb2Te3 TI thin films on prestructured Si(111) Si on insulator (SOI) substrates, paving the way to high quality TI nanostructures in which access to surface states is enhanced. Therefore high quality Bi2Te3 and Sb2Te3 thin films were deposited by means of solid source molecular beam epitaxy (MBE) and subsequently investigated by energy dispersive x-ray spectroscopy (EDX). To investigate the transport properties of the selectively grown thin films, magnetotransport measurements were performed at low temperatures. Nucleation in the SiO2 valleys next to the prepatterned Si(111) mesa structures was not observed. The structural and morphological qualities of crystals deposited on untreated Si(111) SOI wafers are completely preserved by employing the selective area growth on prepatterned substrates. The transport characteristics of the selectively-grown TI systems are comparable to those of the analogous postpatterned films.
•Selective growth of Bi2Te3 and Sb2Te3 TI films on Si mesas by MBE.•Growth of Bi2Te3 and Sb2Te3 on SiO2 valleys is fully suppressed.•Weak antilocalization of TI films selectively grown on Si Hall bars.
•A practical process was proposed to produce high-strength gypsum with spent CaCl2.•α-HH precipitation by the reaction of Al2(SO4)3 and CaCl2 was investigated.•AlCl3 media plays an important role in ...growth and shape of α-HH crystal.•The high quality product of HH was produced in CSTR with no additives.
Direct production of high-strength α-calcium sulfate hemihydrate (α-HH) with no additives was accomplished by the reaction of aluminum sulfate and waste CaCl2 discarded from Solvay soda plant. For scaling-up this new process, the crystallization kinetics of α-HH was experimentally investigated under varying conditions including temperature (323–363 K), concentration of CaCl2 (4–7 mol/kg), Al2(SO4)3 (0.6–3.0 mol/kg), and seed loading. The optimal operating conditions are 7 mol/kg CaCl2 solution, 0.8 mol/kg Al2(SO4)3 solution, 5 wt% seed loading, 2 mol/kg AlCl3 existing in the reactor, T = 353 K, and equilibrium time of 3 h. The α-HH with large columnar shape, as desired in industry, was successfully obtained at optimal conditions by use of a continuous stirred tank reactor (CSTR) without the addition of any additives. The stability test of various CaSO4 phases in aqueous AlCl3, CaCl2, and their solution mixtures elucidated that Al3+ ion and total concentration of Cl− ion play an important role in the growth and shape of α-HH crystal.
•FeSiO3 formation at atmospheric pressure was established in borosilicate glass.•Low-alkali borosilicate glass was synthesized in air at 1500 °C and then heat treated.•Heat treatment caused ...crystallization of FeSiO3, magnetite and cristobalite.
FeSiO3 is a pyroxene mineral – ferrosilite. It remains unclear whether FeSiO3 can be synthesized at atmospheric pressure, as most mineral-focused research leans toward the improbability of such a phenomenon. However, in our previous studies of synthetic glasses melted under atmospheric pressure, the FeSiO3 phase was observed. In this work, FeSiO3 crystallization was studied in more detail in the low-alkali synthetic glass of the Na2O-B2O3-SiO2-Fe2O3-FeO system by XRD, DTA, SEM and Mössbauer spectroscopy depending on the duration of heat treatment (700 °C, 2–130 h). The glass was synthesized using conventional melting at atmospheric pressure at 1500 °C in air. Additional heat treatment caused the formation of magnetite (79–0416), iron metasilicate (FeSiO3, 76–1638), and cristobalite. Increasing the duration of heat treatment led to the growth of FeSiO3 spherical inclusions to more than 2000 nm, and the oxidation of magnetite to hematite. The crystallization of iron metasilicate with an anorthite (triclinic) structural type at atmospheric pressure in synthetic borosilicate glass during thermal treatment at 700 °C was established. The possible reasons for the formation of the FeSiO3 phase are discussed.
Aflatoxins, including aflatoxin B1, B2, G1, G2, M1, and M2, are one of the major types of mycotoxins that endangers food safety, human health, and contribute to the immeasurable loss of food and ...agricultural production in the world yearly. In addition, aflatoxin B1 (AFB1) mainly produced by Aspergilus sp. is the most potent of these compounds and has been well documented to cause the development of hepatocellular carcinoma in humans and animals. This paper reviewed the detoxification and degradation of AFB1, including analysis and summary of the major technologies in physics, chemistry, and biology in recent years. The chemical structure and toxicity of the transformed products, and the degradation mechanisms of AFB1 are overviewed and discussed in this presented review. In addition to the traditional techniques, we also provide a prospective study on the use of emerging detoxification methods such as natural products and photocatalysis. The purpose of this work is to provide reference for AFB1 control and detoxification, and to promote the development of follow-up research.
The present investigation entails the fabrication and characterization of nanometric emulsion of eugenol (Nm-eugenol) encompassed into chitosan for assessing bio-efficacy in terms of in vitro ...antifungal actions, antiaflatoxigenic potential, and in situ preservative efficacy against Aspergillus flavus infestation and aflatoxin B
(AFB
) mediated loss of dietary minerals, lipid triglycerides and alterations in composition of important macronutrients in stored rice. Nm-eugenol characterized by SEM, XRD, and FTIR exhibited biphasic burst release of eugenol. Reduction in ergosterol and methylglyoxal (AFB
-inducer) content after Nm-eugenol fumigation depicted biochemical mechanism of antifungal and antiaflatoxigenic activities. In silico 3D homology docking of eugenol with Ver-1 gene validated molecular mechanism of AFB
inhibition. Further, significant protection of rice seeds from fungi, AFB
contamination and preservation against loss of rice minerals, macronutrients and lipids during storage suggested deployment of chitosan as a biocompatible wall material for eugenol encapsulation and application as novel green preservative for food protection.
•Fe4−xMnxN films were grown on MgO(0 0 1) by molecular beam epitaxy.•In-plane tensile strain was present at x ≥ 2.•Perpendicular magnetic anisotropy of 0.75 and 0.22 Merg/cm3 was obtained for Mn4N ...and Mn3FeN, respectively.•The saturation magnetization decreased non-linearly with Mn content.
Epitaxial Fe4−xMnxN (x = 0, 1, 2, 3, and 4) thin films were successfully grown on MgO(0 0 1) single-crystal substrates by molecular beam epitaxy, and their crystalline qualities and magnetic properties were investigated. It was found that the lattice constants of Fe4−xMnxN obtained from X-ray diffraction measurement increased with the Mn content. The ratio of the perpendicular lattice constant c to the in-plane lattice constant a of Fe4−xMnxN was found to be about 0.99 at x⩾2. The magnetic properties evaluated using a vibrating sample magnetometer at room temperature revealed that all of the Fe4−xMnxN films exhibited ferromagnetic behavior regardless of the value of x. In addition, the saturation magnetization decreased non-linearly as the Mn content increased. Finally, FeMn3N and Mn4N exhibited perpendicular anisotropy and their uniaxial magnetic anisotropy energies were 2.2 × 105 and 7.5 × 105 erg/cm3, respectively.
In early mitosis, the duplicated chromosomes are held together by the ring-shaped cohesin complex
. Separation of chromosomes during anaphase is triggered by separase-a large cysteine endopeptidase ...that cleaves the cohesin subunit SCC1 (also known as RAD21
). Separase is activated by degradation of its inhibitors, securin
and cyclin B
, but the molecular mechanisms of separase regulation are not clear. Here we used cryogenic electron microscopy to determine the structures of human separase in complex with either securin or CDK1-cyclin B1-CKS1. In both complexes, separase is inhibited by pseudosubstrate motifs that block substrate binding at the catalytic site and at nearby docking sites. As in Caenorhabditis elegans
and yeast
, human securin contains its own pseudosubstrate motifs. By contrast, CDK1-cyclin B1 inhibits separase by deploying pseudosubstrate motifs from intrinsically disordered loops in separase itself. One autoinhibitory loop is oriented by CDK1-cyclin B1 to block the catalytic sites of both separase and CDK1
. Another autoinhibitory loop blocks substrate docking in a cleft adjacent to the separase catalytic site. A third separase loop contains a phosphoserine
that promotes complex assembly by binding to a conserved phosphate-binding pocket in cyclin B1. Our study reveals the diverse array of mechanisms by which securin and CDK1-cyclin B1 bind and inhibit separase, providing the molecular basis for the robust control of chromosome segregation.
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