Equimolar Ratio Research Articles

High-Entropy Oxides as Nanozymes for Non-Immunological Electrochemical Monitoring of Cortisol

High entropy oxides (HEOs) are a class of materials that have garnered significant attention in recent years due to their potential use as catalysts in energy-related applications[1]. These materials are derived from high entropy compounds, which consist of equimolar or near equimolar ratios of multiple primary elements and have configurational entropy in the formation of a single-phase structure. The cocktail effect of HEOs gives rise to various catalytically active sites due to the synergistic interaction of the different elements, and lattice distortion during the formation of a single-phase solid solution results in the generation of abundant oxygen vacancies, which enhances the adsorption activity of HEOs and improves their catalytic performance[2]. HEOs can also be cost-efficient by utilizing low-cost transition metal elements as their active centers. Despite their widespread use as catalysts, the application of HEOs in electrocatalysis for molecule monitoring and early diagnosis remains largely unexplored.Cortisol, a glucocorticoid hormone that regulates many aspects of metabolism, stress, and immune response, is closely related to various diseases and disorders[3]. Current methods for noninvasive monitoring of cortisol relies upon immunological assays and typically limited to labor-intensive and time-consuming laboratory techniques. As a consequence, detecting cortisol in a label-free manner that is low cost and offers significant sensor stability and high sensitivity is desirable for many emerging applications, particularly for on-body monitoring.Here, we present work that examines the catalytic activities of HEOs as nanozymes for the electrocatalysis of cortisol. The electrochemical cortisol sensor is based on a novel one-pot microwave-assisted reaction synthesized (Fe, Co, Mn, Ni, Cu) Ox. The catalytic mechanism of electrochemical sensors depends on the formation of various valence metal redox species pairs, where the higher valence state oxidizes cortisol species present on the electrode surface, accompanied by a reduced lower valence state. The one-pot microwave-assisted synthesized HEOs exhibited ultra-high catalytic activity towards cortisol species as measured by cyclic voltammetry and chronoamperometry. Experimental results show a superior sensing performance including a detection limit as low as 0.5 µM (s/N=3), a good linear detection range between 0.01 ~ 4.01 µM, and a sensitivity of 46.5 µA µM-1 cm-2.

A simple, fast, and cost-effective smartphone-based digital imaging method for quantification of lidocaine hydrochloride in pharmaceutical formulations

A simple, highly specific, accurate and fast method by smartphone-based digital imaging was developed for estimating lidocaine hydrochloride in pharmaceutical formulations. To obtain the images, a Galaxy A03 Core smartphone and an image acquisition device developed in the laboratory were used to control the incident factors in reproducibility of the measurements. The processing of the images was carried out with the Color Grab application. Finally, the absorbance values were calculated using the RGB intensity values of blank, standard, and sample solutions. The proposed method was compared with spectroscopic and chromatographic methods. The reaction between copper and lidocaine hydrochloride was characterized, showing better results in an equimolar ratio and maintaining the pH of the solution above 11.5. The use of the device for the capture of digital images allowed to control those sensitive parameters for reproducibility so that the analytical measurements showed adequate precision and accuracy. Validation of the main parameters of the method showed compliance with acceptance criteria. The application of the method for the analysis of injectable samples achieved reliable results, which were statistically similar to other reference instrumental methods. The proposed method presented figures of merit in relation to linearity, precision, selectivity, accuracy, and robustness; it was carried out by designing and manufacturing a device for capturing digital images on a smartphone, which were analyzed to obtain RGB intensity values. These data are finally used to calculate absorbance values of solutions. All these elements provide this work with innovative characteristics in the field of analysis for control of pharmaceutical formulations.

One Pot Synthesis of “3-(4,5-Diphenyl-1H-Imidazol-2-yl)-2-Phenoxyquinolines” and Their Potential as α-Glucosidase Inhibitors: Molecular Docking and MDS Investigation

A novel series of imidazole appended quinoline derivatives (6a–j) have been synthesized using the one-pot three-component reaction that occurred between the starting materials of substituted 2-phenoxyquinolin-3-carbaldehydes (3a-j), benzil (4), and ammonium acetate (5) by taking equimolar ratio. The newly synthesized imidazole-appended quinolines were subjected to probable inhibition against the anti-diabetic drug target maltase enzyme. The efficacy was tested using in-silico molecular docking analysis and molecular dynamics simulation. The studies revealed that the test 6f ligand (3-(4,5-diphenyl-1H-imidazol-2-yl)-2-phenoxy quinoline) is a strong inhibitor of the target protein maltase when compared with the known inhibitor acarbose and sheds new light on the medicinal chemistry research for the application of the synthesized 6f ligand in the pharmaceutical industry.

A Zwitterionic Tetrastanna(II) Cyclic Crown

AbstractA 12‐membered zwitterionic tetrastanna(II) cycle 1 having a crown ether‐like topology has been isolated from the deprotonation of 1,1′‐methylenediimidazole (B) with two equivalents of Sn[N(SiMe3)2]2 (A). The solid‐state structure and NMR analysis confirms the tetrastanna(II) cycle 1 to be comprised of two stannate(II) and two stannyliumylidene ion pairs in alternating positions of the heterocycle. Computational analysis shows greater nucleophilicity at the proximally located stannate(II) centers. Nonetheless, the tetrastanna(II) cycle 1 remains poorly reactive due to engagement of SnII lone pair electrons in intramolecular donor‐acceptor interactions. Simple deprotonation reaction between Sn[N(SiMe3)2]2 (A) and N‐(diisopropylphenyl)imidazole (C) in equimolar ratio has led to a stannylene 2, involving the formation of a Sn−C covalent bond with the anionic imidazol‐2‐yl carbon center along with the release of NH(SiMe3)2. Compound 2 exists as a dimer, where the unsubstituted ring nitrogen atom coordinated intermolecularly to the other stannylene center.

Taste-Masked Flucloxacillin Powder Part 2: Formulation Optimisation Using the Mixture Design Approach and Storage Stability.

Flucloxacillin is prescribed to treat skin infections but its highly bitter taste is poorly tolerated in children. This work describes the application of the D-optimal mixture experimental design to identify the optimal component ratio of flucloxacillin, Eudragit EPO and palmitic acid to prepare flucloxacillin taste-masked microparticles that would be stable to storage and would inhibit flucloxacillin release in the oral cavity while facilitating the total release of the flucloxacillin load in the lower gastrointestinal tract (GIT). The model predicted ratio was found to be very close to the stoichiometric equimolar component ratio, which supported our hypothesis that the ionic interactions among flucloxacillin, Eudragit EPO and palmitic acid underscore the polyelectrolyte complex formation in the flucloxacillin taste-masked microparticles. The excipient-drug interactions showed protective effects on the microparticle storage stability and minimised flucloxacillin release at 2 min in dissolution medium. These interactions had less influence on flucloxacillin release in the dissolution medium at 60 min. Storage temperature and relative humidity significantly affected the chemical stability of the microparticles. At the preferred storage conditions of ambient temperature under reduced RH of 23%, over 90% of the baseline drug load was retained in the microparticles at 12 months of storage.

Taste-Masked Flucloxacillin Powder Part 1: Optimisation of Fabrication Process Using a Mixture Design Approach.

It is extremely challenging to formulate age-appropriate flucloxacillin medicines for young children, because flucloxacillin sodium (FS) has a lingering, highly bitter taste, dissolves quickly in saliva, and requires multiple daily dosing at relatively large doses for treating skin infections. In this paper, we describe a promising taste-masked flucloxacillin ternary microparticle (FTM) formulation comprising FS, Eudragit EPO (EE), and palmitic acid (PA). To preserve the stability of the thermolabile and readily hydrolysed flucloxacillin, the fabrication process employed a non-aqueous solvent evaporation method at ambient temperature. Optimisation of the fabrication method using a mixture design approach resulted in a robust technique that generated stable and reproducible FTM products. The optimised method utilised only a single solvent evaporation step and minimal amounts of ICH class III solvents. It involved mixing two solution phases-FS dissolved in ethanol:acetone (1:4 v/v), and a combination of EE and PA dissolved in 100% ethanol-to give a ternary FS:EE:PA system in ethanol: acetone (3:1 v/v). Solvent evaporation yielded the FTMs containing an equimolar ratio of FS:EE:PA (1:0.8:0.6 w/w). The fabrication process, after optimisation, demonstrated robustness, reproducibility, and potential scalability.

Towards a new chalcopyrite high-performance thermoelectric semiconductor Cu3InSnSe5 by entropy engineering

A new semiconductor Cu3InSnSe5 is introduced by entropy driven alloying equimolar ratio CuInSe2 and Cu2SnSe3. Cu3InSnSe5 is a p-type semiconductor (Eg ∼0.41 eV) and crystallizes in the chalcopyrite structure with I4_2 m space group. Our density functional theory calculations show that Cu3InSnSe5 exhibits an electronic band structure with multiple valance band peaks, rendering a large density of state effective mass m* of 1.8 me. Therefore, Cu3InSnSe5 has a high power factor of 7.59 μW cm−1 K−2 at 773 K. In addition, Cu3InSnSe5 also has a low lattice thermal conductivity (0.34 W m−1 K−1 at 773 K) owing to its severe lattice distortion arose by entropy enhancement. As a result, the figure of merit reaches as high as 1.08 at 773 K for Cu3InSnSe5. Furthermore, electronic band engineering is adopted to enhance the carrier concentration and m* of Cu3InSnSe5 via the substitution of In for Sn, resulting in ∼28% enhancement in power factor, ∼21% increment in ZT (1.31 at 773 K), and ∼10% enhancement in average ZT (∼ 0.67 at 473 – 773 K) for Cu3In1.01Sn0.99Se5 compared with Cu3InSnSe5 itself. Our work shows Cu3InSnSe5 should be a promising candidate for thermoelectric power generation at medium temperature.

Structure of the imine reductase from Ajellomyces dermatitidis in three crystal forms.

The NADPH-dependent imine reductase from Ajellomyces dermatitidis (AdRedAm) catalyzes the reductive amination of certain ketones with amine donors supplied in an equimolar ratio. The structure of AdRedAm has been determined in three forms. The first form, which belongs to space group P3121 and was refined to 2.01 Å resolution, features two molecules (one dimer) in the asymmetric unit in complex with the redox-inactive cofactor NADPH4. The second form, which belongs to space group C21 and was refined to 1.73 Å resolution, has nine molecules (four and a half dimers) in the asymmetric unit, each complexed with NADP+. The third form, which belongs to space group P3121 and was refined to 1.52 Å resolution, has one molecule (one half-dimer) in the asymmetric unit. This structure was again complexed with NADP+ and also with the substrate 2,2-difluoroacetophenone. The different data sets permit the analysis of AdRedAm in different conformational states and also reveal the molecular basis of stereoselectivity in the transformation of fluorinated acetophenone substrates by the enzyme.

Construction of Well-Defined Two-Dimensional Architectures of Trimetallic Metal-Organic Frameworks for High-Performance Symmetric Supercapacitors.

The high surface-to-volume ratio and extraordinarily large-surface area of two-dimensional (2D) metal-organic framework (MOF) architectures have drawn particular interest for use in supercapacitors. To achieve an excellent electrode material for supercapacitors, well-defined 2D nanostructures of novel trimetallic MOFs were developed for supercapacitor applications. Multivariate MOFs (terephthalate and trimesate MOF) with distinctive nanobrick and nanoplate-like structures were successfully synthesized using a straightforward one-step reflux condensation method by combining Ni, Co, and Zn metal species in equimolar ratios with two different ligands. Furthermore, the effects of the tricarboxylic and dicarboxylic ligands on cyclic voltammetry, charge-discharge cycling, and electrochemical impedance spectroscopy were studied. The derived terephthalate and trimesate MOFs are supported with stainless-steel mesh and provide a suitable electrolyte environment for rapid faradaic reactions with an elevated specific capacity, excellent rate capability, and exceptional cycling stability. It shows a specific capacitance of 582.8 F g-1, a good energy density of 40.47 W h kg-1, and a power density of 687.5 W kg-1 at 5 mA cm-2 with an excellent cyclic stability of 92.44% for 3000 charge-discharge cycles. A symmetric BDC-MOF//BDC-MOF supercapacitor device shows a specific capacitance of 95.22 F g-1 with low capacitance decay, high energy, and power densities which is used for electronic applications. These brand-new trimetallic MOFs display outstanding electrochemical performance and provide a novel strategy for systematically developing high-efficiency energy storage systems.

Features of the Phase Formation of Cr/Mn/Fe/Co/Ni/Cu Codoped Bismuth Niobate Pyrochlore

The phase formation process of Bi2Cr1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6Nb2O9+Δ containing 3d-ions of transition elements in equimolar quantities was studied in a wide temperature range (400–1050 °C). The complex oxide crystallizes in the structural type of pyrochlore (sp. gr. Fd-3m:2, a = 10.4937(2) Å). The investigation of the multi-element pyrochlore phase formation process showed that the synthesis goes through a series of successive stages, during which the transition from Bi-rich to Bi-depleted compounds takes place. The predecessor of the pyrochlore phase is bismuth orthorhombic modification orthoniobate (α-BiNbO4) with an equimolar ratio of Bi(III)/Nb(V) ions. The pyrochlore phase is formed as a result of bismuth orthoniobate doping with transition element ions. The complex oxides Bi14CrO24, Bi25FeO40, BiNbO4, and Bi5Nb3O15 appeared as intermediate phases during the synthesis. The interaction between the initial oxide precursors is fixed at temperatures above 500 °C. The phase transition of α-Bi2O3 into β-Bi2O3 near 500 °C is observed. Varying the heat treatment duration at each synthesis step did not qualitatively change the phase composition of the sample but had an effect on the quantitative phase ratio. Phase-pure pyrochlore of the given composition by solid-phase synthesis method can be obtained at a temperature no lower than 1050 °C. Ceramics are characterized by low-porous dense microstructure with blurred outlines of grain boundaries.

RecJ3/4-aRNase J form a Ubl-associated nuclease complex functioning in survival against DNA damage in Haloferax volcanii.

Nucleases are strictly regulated and often localized in the cell to avoid the uncontrolled degradation of DNA and RNA. Here, a new type of nuclease complex, composed of RecJ3, RecJ4, and aRNase J, was identified through its ATP-dependent association with the ubiquitin-like SAMP1 and AAA-ATPase Cdc48a. The complex was discovered in Haloferax volcanii, an archaeon lacking an RNA exosome. Genetic analysis revealed aRNase J to be essential and RecJ3, RecJ4, and Cdc48a to function in the recovery from DNA damage including genotoxic agents that generate double-strand breaks. The RecJ3:RecJ4:aRNase J complex (isolated in 2:2:1 stoichiometry) functioned primarily as a 3'-5' exonuclease in hydrolyzing RNA and ssDNA, with the mechanism non-processive for ssDNA. aRNase J could also be purified as a homodimer that catalyzed endoribonuclease activity and, thus, was not restricted to the 5'-3' exonuclease activity typical of aRNase J homologs. Moreover, RecJ3 and RecJ4 could be purified as a 560-kDa subcomplex in equimolar subunit ratio with nuclease activities mirroring the full RecJ3/4-aRNase J complex. These findings prompted reconstitution assays that suggested RecJ3/4 could suppress, alter, and/or outcompete the nuclease activities of aRNase J. Based on the phenotypic results, this control mechanism of aRNase J by RecJ3/4 is not necessary for cell growth but instead appears important for DNA repair. IMPORTANCE Nucleases are critical for various cellular processes including DNA replication and repair. Here, a dynamic type of nuclease complex is newly identified in the archaeon Haloferax volcanii, which is missing the canonical RNA exosome. The complex, composed of RecJ3, RecJ4, and aRNase J, functions primarily as a 3'-5' exonuclease and was discovered through its ATP-dependent association with the ubiquitin-like SAMP1 and Cdc48a. aRNase J alone forms a homodimer that has endonuclease function and, thus, is not restricted to 5'-3' exonuclease activity typical of other aRNase J enzymes. RecJ3/4 appears to suppress, alter, and/or outcompete the nuclease activities of aRNase J. While aRNase J is essential for growth, RecJ3/4, Cdc48a, and SAMPs are important for recovery against DNA damage. These biological distinctions may correlate with the regulated nuclease activity of aRNase J in the RecJ3/4-aRNaseJ complex.

Critical Role of Molecular Packing in Lo Phase Membrane Solubilization.

Membrane solubilization induced by Triton X-100 (TX-100) was investigated. Different membrane compositions and phase states were studied along the detergent titration. Expected solubilization profiles were obtained but new information is provided. The fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids indicates that the liquid-ordered (Lo)/liquid-disordered (Ld) phase coexistence is barely unaffected at sub-solubilizing detergent concentrations and highlights the vesicle-to-micelle transition. Moreover, the location of the NBD group in the bilayer emphasizes a detergent-membrane interaction in the case of the insoluble Lo phase membrane. It has also been shown that the molecular packing of the membrane loosens in the presence of TX-100, regardless of the solubilization profile. Motivated by studies on GPMVs, the solubilization of less ordered Lo phase membranes was considered in order to improve the effect of molecular packing on the extent of solubilization. Membranes composed of SM and Chol in an equimolar ratio doped with different amounts of PC were studied. The more ordered the Lo phase membrane is in the absence of detergent, the less likely it is to be solubilized. Furthermore, and in contrast to what is observed for membranes exhibiting an Lo/Ld phase coexistence, a very small decrease in the molecular packing of the Lo phase membrane radically modifies the extent of solubilization. These results have implications for the reliability of TX-100 insolubility as a method to detect ordered domains.

Consecutive Four-Component Coupling-Addition Aza-Anellation Pictet–Spengler Synthesis of Tetrahydro-β-Carbolines: An Optimized Michael Addition and Computational Study on the Aza-Anellation Step

Starting from acid chlorides, alkynes, tryptamines, and acryloyl chloride, 21 densely substituted tetrahydro-β-carbolines were prepared in a four-component, one-pot reaction. In this study, the aza-Michael addition step to generate intermediate enaminones was optimized in the presence of ytterbium triflate. Moreover, apart from acryloyl chloride, all reactants could be deployed in almost equimolar ratios, which increases the atom economy of the sequence. For mechanistic rationalization, the concluding aza-anellation was investigated by DFT calculations on potential intermediates and corresponding activation energies, revealing that the aza-anellation proceeds via ene reaction rather than via electrocyclization.

Folic acid-decorated calix[4]resorcinol: Synthesis, dissolution in water and delivery of doxorubicin

Selective internalization in cancer cells has great potential to reduce the side effects of cancer therapy. One effective approach to increase targeting to cancer cells is modification of nanocarrier with folate groups, providing interaction with folic acid alpha receptors, which are overexpressed in some types of tumors. In this work, the folic acid-modified calix[4]resorcinol was synthesized. The choice of calix[4]resorcinol as a modified molecule is due to the possibility of simultaneous attachment of four folic groups. However, this synthetic modification did not improve the water solubility of the calixarene skeleton; therefore, its water-soluble form was further prepared in the presence of N-methyl-D-glucamine and the ability of the resulting form to bind doxorubicin hydrochloride was studied. When studying a mixed system of folic acid-based calix[4]resorcinol with doxorubicin, the smallest particles were found at their equimolar ratio. The equimolar complex of the synthesized macrocycle with doxorubicin exhibits folic acid-receptor mediated selective uptake by M-HeLa cells and induces selective cancer death.

Metal- and Peroxide-Free Silicone Rubbers with Antibacterial Properties Obtained at Room Temperature

Metal- and peroxide-free silicone rubbers were obtained via a reaction between amino-containing poly(dimethylsiloxanes) (amino-terminated (APDMS-1) or a copolymer with pendant amino groups (APDMS-2)) and iodine-containing polysiloxanes (PIMSs) (Menshutkin reaction). Simple mixing of functional polymers at room temperature resulted in forming silicone materials. The formation of ammonium cross-links was confirmed using solid-state 1H and 13C NMR spectroscopy. The equimolar ratio of NH2 groups to the I-containing moiety (1:1) was the most optimal among other ratios (2:1 and 1:2) to carry out cross-linking and led to the highest cross-linking density according to the swelling measurements. PIMS/APDMS-1 (1:1) rubbers had the lowest average molecular weight of segments between cross-links Mc = 250 compared to PIMSs/APDMS-1 (1:2) and (2:1) with Mc = 1110 and 390, respectively. The obtained silicone rubbers showed antibacterial activity against Escherichia coli and Staphylococcus aureus and thereby could be applied in biomedicine and the food industry as antibacterial coatings and materials.

Edible Cutlery – A Prototype to Combat Malnutrition and Plastic Waste Management

Background: Edible cutlery is a natural and bio-degradable commodity which can be concocted to be nutritious and replace the usage of plastic cutlery. This study aims at sustainable development, elimination of plastics as cutlery from the food sector, ecological waste management, maintenance of optimal nutritional status and prevention of non-communicable diseases. These edible cutleries, which are made by combining all the five food groups given in the MyPlate, will prodigiously influence the intake of complex carbohydrates, protein, fibre, micronutrients and nutraceuticals on a routine basis. Materials and Methods: This report is targeted at the fabrication of edible cutleries using composite flour blends of whole wheat, foxtail millet, and roasted bengal gram, along with enrichment of skimmed milk powder, orange fruit powder and beetroot extract in proportions as suggested in a balanced diet, in order to evaluate its ability to meet the recommended daily allowances, phytochemical profile, functionality and economic competence. Three variations were baked at 180°C for 17 min. Results: According to the results of the analysis, variation 2, with an equimolar ratio of whole wheat flour and foxtail millet flour along with other ingredients, proved to be the most proficient alternative to plastic cutlery. Conclusion: The accepted cutlery indicated to considerably meet the RDA in terms of certain nutrients majorly lacking in the Indian diet, along with catering to the nutraceutical needs of the body. Economically, the cost of these cutleries was found to be lower than those present in the market.

A novel strategy for rapid fabrication of continuous carbon fiber reinforced (TiZrHfNbTa)C high-entropy ceramic composites: High-entropy alloy in-situ reactive melt infiltration

For the first time, dense continuous carbon fiber (Cf) reinforced (TiZrHfNbTa)C high-entropy ceramic (Cf/HEC) composites were rapidly prepared via in-situ reactive melt infiltration (RMI). A TiZrHfNbTa high-entropy alloy served as the cation source and carbon in Cf reinforced carbon matrix (Cf/C) preforms served as the anion source, and a (TiZrHfNbTa)C high-entropy ceramic phase with a near equimolar ratio was successfully formed. The results revealed that most of the TiZrHfNbTa high-entropy alloy reacted with the carbon matrix, and the harvested Cf/HEC composites exhibited an excellent bending strength (612.6 MPa) and low ablation rates. High reaction rates caused by ultra-high temperature and homogeneous distribution of elements in the high-entropy TiZrHfNbTa alloy significantly reduced the difference in reactivity with C among Ti, Zr, Hf, Nb, and Ta are considered to be the reasons for successful formation of (TiZrHfNbTa)C high-entropy ceramic with a near equimolar ratio in Cf/HEC composites.

Al–SrTiO3/Au/CdS Z-schemes for the efficient photocatalytic H2 production under visible light

Development of sustainable solar fuels to meet the continued increase in the energy need worldwide is of particular importance. In addition, reducing carbon emissions could be the last hope to solve global challenges such as global warming and climate change. For this endeavor, different Al–SrTiO 3/Au/CdS Z-Scheme samples were developed by changing the weight percentage (wt. %) of gold nanoparticles (Au NPs) and the wt% ratio of Al–SrTiO3 to CdS NPs using post annealing of mixed powders method. The prepared samples were characterized using several physicochemical techniques to reveal their properties, then their photocatalytic H2 evolution performance was evaluated under visible light using photodeposited RhCr2O3 as H2 evolution cocatalyst. Our results showed that, Al–SrTiO3 particles possessed high crystallinity and cubic perovskite phase, Au NPs exhibited face-centered cubic (FCC) structure, and CdS NPs had cubic Zinc Blende phase as confirmed by XRD analysis. Our UV–Vis. diffuse reflectance analysis revealed that all prepared Z-scheme samples obtained a strong absorption in both UV and visible regions. SEM analysis confirmed the cubic morphology of the perovskite Al–SrTiO3 particles which were randomly deposited by Au NPs of relatively smaller size. While CdS NPs showed semi-spherical shape and were conjugated with Al–SrTiO3 directly to form the proposed Z-Schemes as proposed by our STEM mapping analysis. The highest amount of H2 (656.7 μ mole) was evolved by Al–SrTiO3/4 wt% Au/CdS (1:1) Z-scheme sample after 3 h of visible light irradiation. This sample had 4 wt % of Au NPs and equimolar ratio of Al–SrTiO3 and CdS NPs. This relatively higher activity might be because of the efficient light absorption, prolonged lifetime of the photogenerated charge carriers and improved charge separation as revealed by the PL analysis. Our study can promote the ongoing efforts toward more carbon neutral societies.

Phase and microstructural analysis of novel refractory high entropy alloy Y-doped Al-Hf-Nb-Ti-V system

A new Y-doped Al-Hf-Nb-Ti-V refractory high-entropy alloy (RHEA) system was developed as a candidate material for high-temperature structural applications. Microstructural investigation and X-ray diffraction (XRD) characterization results indicated that the as-cast alloy exhibits a non-homogeneous microstructure with distinct dendritic and interdendritic regions. The addition of the equimolar ratio of Al to the HfNbTiV RHEA resulted in an amorphous phase and a small amount of intermetallic phase formation. The enthalpy calculation revealed that this alloy has ∆Hmix = -16.2 kJ.mol−1 and a δ parameter of 5.8%, which are considerably lower and negative for the former and lower for the latter compared with the conventional high entropy alloys. The addition of the minor Y element slightly increases the value of δ and ∆Hmix which suppresses the occurrence of the amorphous phase and contributes to the intermetallic compound formation by increasing the amount of strongly chemically attracted atomic pairs (SCAAPs) Al-Hf and Al-Y beyond a critical value.

Nickel-Passivating element selection in FCC process and mechanistic study on the passivation of nickel by lanthanum and phosphorus

Motivated by the dehydrogenation activity of nickel (Ni) and the toxicity of free nickel oxide (NiO) in the fluid catalytic cracking (FCC) catalysts, this study aims to reveal the appropriate elements to in-situ passivate nickel during the cracking reactions of oil by conducting hydrocarbon dehydrogenation tests of Y-zeolite loaded with Ni and passivating elements in a Pyro-probe micro-reactor coupled with GC-TCD and MS. The conditions were chosen as 550 °C with a catalyst-to-hydrocarbon mass ratio of 5:1. Additionally, hydrogen-temperature programmed reduction (H2-TPR) was conducted. In supporting the experimental observation, thermodynamic calculations were also performed to assist the selection of possible Ni-passivating elements in terms of the free Gibbs energy for their reactions with NiO. Lanthanum (La) and phosphorus (P) were found to exert the most effective effects on nickel passivation. The use of twice the quantity of La or P more than Ni, or the combined use of La and P each in equimolar ratio to Ni is able to decrease the dehydrogenation extent by 97%. La can passivate the free NiO species by chemically bonding with NiO which, otherwise, would bond with alumina in zeolite. Instead, P is preferentially coated on the Ni-bearing particles, which leads to the formation of phosphate that is inactive in the dehydrogenation of the model organic compounds when compared to the free NiO.