Mixture Of Phases Research Articles

Enhancing mechanical properties of surface hardness and abrasion resistance of Fe-Mn-Al alloy by using atmospheric pressure plasma jet nitriding

This study investigates the use of a N2/H2 mixture gas and an atmospheric pressure plasma jet (APPJ) for nitriding Fe-Mn-Al alloy. Pure metals, iron, manganese, and aluminum, were used as the reference metallic substrates. Various characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Vickers hardness test, and optical emission spectroscopy (OES), were employed to analyze the material properties and plasma species. XRD analysis revealed the formation of nitride compounds on metals after the nitriding process. The plasma-nitrided Fe-Mn-Al alloy showed the mixture phases of Fe4N and Al, while plasma-nitrided pure metals possessed their specific metal nitrides. After nitriding process, the surface hardness increased to approximately 596 ± 6 HV0.025 for the Fe-Mn-Al alloy, 1307 ± 9 HV0.025 for manganese, 467 ± 4 HV0.025 for aluminum, 646 ± 5 HV0.025 for iron, and, compared to the pristine values of around 346 ± 4 HV0.025, 972 ± 6 HV0.025, 145 ± 3 HV0.025, and 125 ± 3 HV0.025, respectively. After the nitriding process, the Fe-Mn-Al alloy exhibited notable enhancements in both its resistance to abrasion and its capacity to endure impact loads, as indicated by the conducted tests. The OES test results identified NH radicals generated by the atmospheric pressure plasma jet beam as the active chemicals responsible for the success of the nitriding process. Overall, this study provides valuable insights into the strengthening of metal surfaces through nitriding using an N2/H2 mixture gas and APPJ. The results demonstrate significant improvements in surface hardness and surface free energy for iron, manganese, aluminum, and Fe-Mn-Al alloy, highlighting the effectiveness of NH radicals in the nitriding process.

CuS-CuO nanoparticles for antennas collect light through their conductivity by absorbing a single photon located at the wavelength of 254 nm

CuS-CuO nanoparticles were prepared by air annealing as-made CuS nanoparticles deposited using spray pyrolysis. The optical, structural, and morphological properties of samples were investigated by UV–VIS Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The XRD analysis of as-prepared sample include two phases CuS and Cu2S, while annealed films are a mixture of CuS and CuO phases. The dimensions of the CuS crystallites were estimated by Williamson's method on the diffraction peaks (81 nm) while the dimensions of the CuO ones were statistically evaluated via the SEM image (95 nm) and corroborated by Williamson's method on the diffraction peaks (98 nm). SEM study of annealed samples reveals that nanoparticles are monocrystalline. Optical analysis shows more than 80 % transmittance through sample thickness 164 nm in the infrared region and two energy bandgaps of 1.92 and 2.50 eV in the visible region associated with CuO and CuS, respectively. In addition, we observe after several optical excitations that only the UV wavelength of 254 nm gives a tangible electrical response. We understand from the literature that this is only possible through one interpretation of the antenna effect. Optical antennas aim to freely change light rays into local energy. In fact, our sample presents nanoparticles with sizes around 80 nm that show clear absorption through the development of their reproducible resistance that increases with polarization toward saturation after 5 V. Therefore, we propose using prepared nanoparticles in a light-harvesting antenna for artificial photodetector and other optoelectronic applications.

Hydrophobic interactions described using hetero-segmented PC-SAFT: 1. Alcohol/water mixtures

The hydrophobic effect plays a central role in aqueous systems containing molecules with hydrophobic moieties. Despite the relevance of this effect for chemical processes or pharmaceutical applications, modeling remains challenging even using molecular-based models such as different versions of the Statistical Associating Fluid Theory. This work shows the feasibility of hetero-segmented PC-SAFT for this purpose. This model was used as a group contribution method to build molecules from different functional groups, namely from CH2, CH3, and CH2OH groups. Saturated-liquid densities and vapor pressures of n-alkanes and n-alcohols as well as binary mixtures of these molecules were accurately described by this approach. The description of aqueous mixtures containing n-alkanes and n-alcohols was improved compared to state-of-the-art modeling by explicitly accounting for intermolecular interactions resulting in the hydrophobic effect. The so-obtained framework describes the two liquid−liquid equilibrium phases in mixtures of n-alkanes or n-alcohols with water equally well using a single set of transferable parameters. The model was also validated for vapor–liquid equilibria, solid–liquid equilibria, infinite-dilution properties, as well as octanol/water partition coefficients and showed quantitative agreement with experimental data.

Therapeutic drug monitoring of six contraindicated/co-administered drugs by simple and green RP-HPLC-PDA; application to spiked human plasma

Therapeutic drug monitoring is an important clinical testing of the drugs to monitor their concentrations in plasma in order to guarantee their optimal impact, and to avoid any side effects resulting from drug-drug interactions. A green reversed-phase high-performance liquid chromatographic method using a photodiode array detector (RP-HPLC-PDA) was developed for the simultaneous determination of three carbapenem antibiotics (Imipenem, ertapenem, and meropenem) with the co-formulated drug (cilastatin) and contraindicated drugs (probenecid and warfarin) in spiked human plasma. The separation was achieved at 25 °C using a gradient elution of a mixture of mobile phase A: methanol and mobile phase B: phosphate buffer (pH 3.0). The photodiode array detector was adjusted at 220 nm. Bioanalytical method validation was carried out as per the FDA guidelines, and the method showed good linearity ranges for the six drugs that included their Cmax levels along with low limits of quantification. Based on the results, the method was found to be accurate and precise; with high % recovery and good % RSD, respectively. The method was successfully applied to spiked human plasma, signifying a good potential to be implemented in future TDM studies of these drugs when co-administered together.

Structure and phase transitions in niobium and tantalum derived nanoscale transition metal perovskites, Ba(Ti,MV)O3, M=Nb,Ta.

The prospect of creating ferroelectric or high permittivity nanomaterials provides motivation for investigating complex transition metal oxides of the form Ba(Ti, MV)O3, where M = Nb or Ta. Solid state processing typically produces mixtures of crystalline phases, rarely beyond minimally doped Nb/Ta. Using a modified sol-gel method, we prepared single phase nanocrystals of Ba(Ti, M)O3. Compositional and elemental analysis puts the empirical formulas close to BaTi0.5Nb0.5O3-δ and BaTi0.5Ta0.5O3-δ. For both materials, a reversible temperature dependent phase transition (non-centrosymmetric to symmetric) is observed in the Raman spectrum in the region 533-583K (260-310°C); for Ba(Ti, Nb)O3, the onset is at 543K (270°C); and for Ba(Ti, Ta)O3, the onset is at 533K (260°C), which are comparable with 390-393K (117-120°C) for bulk BaTiO3. The crystal structure was resolved by examination of the powder x-ray diffraction and atomic pair distribution function (PDF) analysis of synchrotron total scattering data. It was postulated whether the structure adopted at the nanoscale was single or double perovskite. Double perovskites (A2B'B″O6) are characterized by the type and extent of cation ordering, which gives rise to higher symmetry crystal structures. PDF analysis was used to examine all likely candidate structures and to look for evidence of higher symmetry. The feasible phase space that evolves includes the ordered double perovskite structure Ba2(Ti, MV)O6 (M = Nb, Ta) Fm-3m, a disordered cubic structure, as a suitable high temperature analog, Ba(Ti, MV)O3Pm-3m, and an orthorhombic Ba(Ti, MV)O3Amm2, a room temperature structure that presents an unusually high level of lattice displacement, possibly due to octahedral tilting, and indication of a highly polarized crystal.

СВОЙСТВА И ФАЗОВЫЙ СОСТАВ ЦЕМЕНТНЫХ РАСТВОРОВ

Introduction of complex antifreezes based on calcium formate, calcium chloride and superplasticizer Polyplast SP-1 into cement masses leads to changes in the phase composition of cement mortars. Of great importance are the developments of complex modifiers that are used for the hardening phase of cement-crushed mixtures, especially at low temperatures (down to –20 °C). The phase and structural characteristics of cement mortars have not been sufficiently studied. In this regard, the work investigated the effect of complex antifreeze additives on the properties and phase composition during the structuring of cement masses. Compressive strength reaches its maximum value (44.8 MPa) with the addition of calcium formate, calcium chloride and superplasticizer to the composition of cement pastes. X-ray diffraction analysis was carried out using a DRON-3 diffractometer. The used methods were standard. The X-ray diffraction patterns of the samples prove the high intensity of reflections of calcium hydrosilicate d = 9.69 Å, portlandite d = 4.921 Å, d = 2.632 Å, which indicates a high degree of hydration of portland cement. The combined use of calcium formate and calcium chloride promotes the activation of hydrolysis, and the addition of superplasticizer SP-1 leads to a decrease in the water-cement ratio to 0.20, which leads to an acceleration of the hardening process. Complex antifreeze additives increase the percentage ratio of crystalline phase to amorphous phase, thus, cement pastes with complex additives of 6 % (HCOO)2Ca, 3 % CaCl2, 2 % SP-1 have the highest value of degree of hydration (0.70) due to the formation of 63 % crystalline phase. Newly formed structures are typical for portlandite and dicalcium hydrosilicates. Complex antifreezes as an additive promote the activation of hydration in cement mortars, and the level of the degree of hydrolysis and the integral value of mass loss confirm this. Synergism of structure formation processes is observed at joint use of antifreeze additives in the composition of cement masses and, as a result, increases the strength of cement mortars used in construction at low climatic temperatures.

Polymer composite coatings subjected to sliding wear under simulated lunar temperature and dust conditions

Due to the detrimental effect of lunar dust on tribological components, it is imperative to develop bearing materials and surfaces which can survive and mitigate dust at the interface while operating under lunar environmental conditions. This issue is poised to become more significant in the near future, with lunar exploration evolving beyond the short probing missions of the Apollo era. Therefore, this study aims to investigate the combined effect of temperature and lunar dust on the tribological performance of aromatic thermosetting copolyester (ATSP) and polyether ether ketone (PEEK) -based polymer composite coatings from −150 to 110 °C. The experiments were conducted using a flat pin-on-disk configuration under dry sliding conditions, sliding speed of 0.25 m/s, 17.5 MPa contact pressure, and nitrogen gas environment. It was found that metal-on-polymer coating sliding results in dust embedment and accumulation on the softer material, which yields high friction and two-body abrasive wear. The chemical analysis of transfer film on the metal pin surface indicated a mixture of dust and polymer phases, which increased with increasing temperature, and thus resulted in deteriorated tribological performance. Self-mating polymer coatings yielded lower friction coefficient and wear due to a better dust mitigation resulting in three-body wear at the interface. The ATSP-based coatings showed higher wear resistance at all temperatures, particularly under self-mating sliding condition.

Influence of vanadium and dysprosium co-doping on phase stability, microstructure, and electrical properties of Bi2O3

Herein, we report the synthesis of Dy–V co-doped Bi2O3 ceramics using the solid–state processing technique under atmospheric conditions. The X-ray diffraction (XRD) patterns demonstrate the stability of the cubic fluorite δ-Bi2O3 in the V-rich ceramics. However, in Dy-rich ceramics, a mixture of phases, including α and δ, gradually diminishes with increased mutual dopant concentrations, suggesting a transition to the single fcc δ-phase with Fm-3 m space group. According to the Rietveld analysis and electron density representation, it is evident that there are no impure peaks present in α-Bi2O3, which highlights the clear transition to the δ-phase polymorphs. The DTA curves for samples M4 and M7 display a distinct endothermic peak at temperatures around 724.5 and 744.5 °C, indicating a phase transition from the monoclinic α-phase to the cubic δ-phase. These peaks are also attributed to an order-disorder transition (ODT). The FESEM micrographs consistently revealed the existence of irregular and aggregated grains, with an average grain size ranging from 0.80 to 5.57 μm. The level of aggregation became more apparent with the escalation of Dy3+ doping, as opposed to the 5–20 wt% V loading. Moreover, the as-sintered pellets M2 demonstrated the absence of any pore formation compared to other samples, confirming a remarkably high degree of densification. As a result, the as-sintered pellets have a low level of void space, with an apparent porosity of no more than 2.5%. Based on the conductivity measurements and electrochemical impedance spectroscopy (EIS), Bi0.85V0.10Dy0.05O1.5 exhibits the highest electrical conductivity of 0.965 (Ω cm)−1 and an optimal activation energy of 0.537 eV at 627 °C compared to other prepared compositions. This remarkable performance is attributed to the high polarizability and mixed valence cations, especially in V5+-rich ceramics, compared to the Dy3+-rich compositions with a reduced conductivity of 0.010 to 0.097 (Ω cm)−1. The Nyquist plots indicate that impedance decreases with vanadium doping increases until it reaches Bi0.85V0.10Dy0.05O1.5. Higher Dy3+ content increases impedance, leading to lower cell performance. The typical composition can be a solid electrolyte in SOFCs operating at moderate temperatures.

Mixture Design-driven Statistical Optimization and Method Validation in HPTLC: Targeting Rutin, Quercetin, and Gallic Acid

Rutin (RT), Quercetin (QT), and Gallic Acid (GA) are recognized for their potent antioxidant and anticancer properties, prevalent across numerous plant species. The precise quantification of RT, QT, and GA is pivotal for evaluating the therapeutic potential of plant-based substances. In response, a new, straightforward, cost-effective, and reliable method using High-Performance Thin-Layer Chromatography (HPTLC) has been developed and validated for the quantification of these compounds. The mobile phase optimization employed a mixture design approach, achieving chromatographic separation with a mobile phase mixture of toluene, ethyl acetate, menthol, and formic acid at specific ratios (3.56:3.70:0.94:1.80 v/v/v/v/v/v/v/v). Silica gel 60 F254 HPTLC plates were utilized for the analysis. The retention factors (Rf) observed for RT, GA, and QT were 0.21, 0.58, and 0.74, respectively. This method demonstrated a robust linear relationship for concentrations ranging from 400 to 2000 ng per band, with correlation coefficients (R2) of 0.9921 for RT, 0.9936 for QT, and 0.9912 for GA. The Limits of Detection (LOD) and quantification (LOQ) were established at 100.84, 102.38, and 84.54 ng per band for LOD, and 305.58, 310.25, and 256.18 ng per band for LOQ, respectively, for RT, QT, and GA. This validated HPTLC method developed through a Design of Experiment (DoE) approach was successfully employed for the quantification of GA, QT, and RT from the fruits of Adansonia digitata and leaves of Grewia asiatica ethanolic extracts.

Deterioration Mechanism and Status Prediction of Hydrocarbon Lubricants under High Temperatures and Humid Environments

In practical engineering applications, high temperatures and water ingress seriously affect the service life of hydrocarbon lubricants. In this study, the deterioration process of hydrocarbon lubricants under high temperatures and humid environments was investigated, and a new health state prediction model was proposed. Simulation of hydrocarbon lubricant Polyalpha−olefin (PAO) molecules used the ReaxFF force field to analyse the high temperature thermal oxidation process of lubricants. The rheological properties of oil−water emulsions were determined by observing the morphology of oil−water two−phase mixtures with different water contents. A multiparameter fusion viscosity prediction model was proposed using a linear model of the viscosity of aqueous fluids, as affected by temperature and water content, and was fitted with the Andrade viscosity−temperature equation to predict lubricant viscosity changes under multiple parameters. Online validation tests were carried out on a compound planetary transmission system, and the surface topographical parameters of the transmission components were further discussed. Experimental results show that the linear correlation with the improved lubricant viscosity prediction model is 0.966, and the surface wear of transmission components is consistent with the trend of lubricant quality change. These findings provide a fundamental basis for the assessment of lubricant service life in high temperatures and humid environments.

Massive transformation in dual-laser powder bed fusion of Ti6Al4V alloys

In the present investigation, we fabricated additively manufactured Ti6Al4V parts using dual laser-powder bed fusion (DL-PBF) and identified the occurrence of a massive transformation. A detailed and systematic study of the massive transformation in the DL-PBF process by changing the energy and time offset of the lag laser beam and its effect on the microstructural and mechanical properties was undertaken. A mixture of martensite and massive phases was observed within the prior β grains in DL-PBF, and the dimensions of these massive grains increased with an increase in the lag laser beam energy, while acicular α′ martensite was present in the single Laser-PBF. The massive phase showed a featureless patch-shaped region, which consisted of thin laths, and they were associated with the prior β grain boundaries. The irregular patch-shaped regions showed inferior Vickers hardness when compared with acicular α′ martensite, and the ultimate tensile strength was lower in the DL-PBF than in the single Laser-PBF. The columnar prior-β grain was present in all the samples (both in the single- and dual-beam laser) and the dimensions of the grains varied with increasing the lag laser beam energy. These present results showed that the DL-PBF process significantly influenced the microstructural and mechanical properties of the Ti6Al4V materials, and provided a deep insight into massive phase transformation in AM titanium alloys and its effect on the mechanical properties.

Optimization of a Validated Liquid Chromatographic Method with Chemometric Approach for Estimation of Eugenol from Seed Powder Extract and Perform Anti-oxidant Activity

Background:: Developed and validated a new reverse phase high-performance liquid chromatographic (RP-HPLC) method, and it is prompt, precise, sensitive and robust for the esti-mation of eugenol in seed powder extract of Myristica fragrans. Objective:: The chemometric approach was utilized to obtain a rugged and definitive chromato-graphic method for the purpose. Methods:: Method variables such as acetonitrile (%) and flow rate were investigated for robust-ness and optimization by using a face-centered cubic design (FCCD). The Design Expert 12.0.1.0 software has been employed for this optimization. Further, the effects of factors were monitored on the concentrations of eugenol recovered from seed powder extract. Chromatograms have been developed by using an optimized mobile phase mixture containing methanol-water-acetonitrile (10:40:50, v/v/v) and Symmetry® C18 column (5 μm, 3.9 ×150 mm). The mobile phase was de-rived at a flow rate of 1 mL/min, and estimation of eugenol was performed at ʎmax 272 nm. Results:: Validation of the method has been carried out to reveal its selectivity, linearity, preci-sion, accuracy, LOD, and LOQ. Linear calibration plot for eugenol was held over the concentra-tion across 6.25 and 100 μg/mL (R2 = 0.999). The coefficient of variation was less than 1%, and accurate recovery of eugenol was observed between 96.80 and 99.56 %. The LOD and LOQ have been established to be 1.97 and 6.25 μg/mL, respectively. Intraday and Inter-day coefficients of variation have 1.81-1.91 and 1.92-1.57, respectively. Antioxidant activity (AA) by DPPH assay of seed powder extract in five different solvents was performed, and % AA activity was calculat-ed against ascorbic acid. Conclusion:: The validated method has been found to be highly robust and will be applied for the analysis of eugenol in formulation. The highest % AA has been reported in hexane solvent.

On the role of vanadium in the structure and properties of calcium-bismuth-sodium oxyapatite

This study explores the possibility of obtaining solid solutions with the composition Ca8BiNa(PO4)6-x(VO4)xO (0 < x ≤ 6) and investigating their physicochemical and medicobiological properties. Using solid-state synthesis method, only the composition Ca8BiNa(PO4)5·5(VO4)0·5O was obtained, while for other values of x, mixtures of apatite and secondary phases or mixtures of various vanadates and phosphates without the target apatite structure were obtained. The study considers the dimensional crystal chemical factors influencing the possibility of forming solid solutions in a wide range of compositions. The crystal structure of Ca8BiNa(PO4)5·5(VO4)0·5O was refined by the Rietveld method (a = 9.45154(37) Å, c = 6.93659(28) Å, V = 536.638(47) Å3, R-Bragg = 3.718 %) and confirmed by group analysis of the IR spectrum. Standard MTT test showed that this substance is not cytotoxic at dilutions of 1:2 and higher. No bactericidal activity against S. aureus and E. coli cultures was observed.

Lattice Boltzmann method for particulate multiphase flow system

This study proposes a numerical model for particulate three-phase flow in microchannels based on multiphase lattice Boltzmann method (LBM). The model combines the color-gradient method to track the immiscible fluid-fluid interface and the two-fluid model (TFM) to describe particle-particle and particle-fluid interactions, which can efficiently simulate transport and displacement processes involving large amounts of particles. A mixture-rheology TFM algorithm is proposed by introducing a mixture phase with rheology properties obtained from experiments instead of the conventional TFM particle phase with artificial viscosity models. Multi-relaxation-time (MRT) collision operator and GPU computing are adopted to enhance the numerical stability and efficiency. Various theoretical benchmarks for particle transport and two-phase flow are performed respectively to verify the accuracy of the proposed model. Exceptional consistency between results from particulate three-phase flow simulation and microfluidic experiments further confirms the reliability of our model, especially in capturing the inertial lagging and accumulation phenomena under multiphase and porous flow conditions. The proposed numerical framework will benefit our understanding of multiphase displacement with microgels in microchannels with complex geometries.

Improving the performance of heat sinks through the integration of fins and the utilization of graphene-mixed latent heat energy storage

Effective thermal management is significant to ensure the safety of all operating systems. However, these systems demand innovative thermal management technology. A heat sink with improved thermal conductivity is one of the passive heat management techniques. This study focuses on enhancing thermal management in devices by evaluating the performance of a heat sink with and without fins integrated with high thermal conductivity graphene-incorporated phase change material. Paraffin wax with a melting temperature of 58 °C was used as the phase change material. The study examines how the addition of graphene nanoparticles improves heat transfer capacity and extends the heat sink's working duration. The findings revealed that the phase change material extends the heat sink's working duration while adding nanoparticles improves performance. The performance of the phase change material and mixture of the nanoparticles was examined using a finned heat sink under constant heat input. The heating and cooling cycle of the heat sink was examined. The performance of the heat sink with fins and nano PCM was increased by 30 % compared to the baseline heat sink at 15 W heat input. This performance was increased to 45 % when the heat input changed to 30 W. The results indicated that nanoparticles in the phase change material augment the heat sink's recovery time, irrespective of the influence of fins.

Magnetic properties of nano(iron oxide)-decorated graphene oxide

Graphene oxide (GO) decorated with magnetic iron oxide nanoparticles is of great interest due to its potential applications in nanomedicine, electromagnetic insulation, and electro-catalysis. Herein, we studied the effect of the preparation conditions by hydrothermal synthesis on the phase composition of graphene oxide decorated with iron oxide nanoparticles. GO samples using two different amounts of a 2Fe3+/Fe2+ solution were prepared under a pH = 11, whereas hydrazine treatment was done to half the batch. Electron microscopy images show that Fe-oxide nanoparticles with an average size of 5–10 nm appeared decorating graphene platelets. Graphene oxide decorated rolls form in hydrazine-treated samples. Infrared spectra suggest a mixture of iron oxide phases with increased goethite upon hydrazine treatment. X-ray diffraction and X-ray Absorption Near Edge Structure spectroscopy (XANES) in the Fe K-edge determined the relative amount of the resulting iron oxide phases. Mixtures of magnetite, maghemite, hematite, and goethite were observed depending on the sample preparation conditions. The effect of phase composition on the magnetic properties was also studied. The saturation magnetization varied from 3.5 to ca. 50 Am2/kg at 300 K; it is proportional to the magnetite/maghemite content and reduces as the amount of goethite increases. The coercive field in the samples increases up to 1.6–2.4 mT at 300 K. The saturation magnetization has a slower decay with temperature when compared to a reference sample of magnetite nanoparticles, which suggests a magnetoelectric coupling due to the nanoparticle distribution onto the conductive graphene sheet.

Comparison of Structure and Reactivity of Hydrothermally Prepared Bi−Mo−Co−Fe−O Catalysts in Selective Propylene and Isobutene Oxidation

AbstractThe elucidation of structure‐activity correlations in selective oxidation of propylene and isobutene over mixed metal oxides (MMO) is attractive for knowledge‐based catalyst design and process optimisation. Particularly, 4‐component Bi−Mo−Co−Fe−O catalysts need to be studied since their complex metal oxide phase mixture leads to higher activity and selectivity than 2‐component Bi−Mo−O. Hence, three Bi−Mo−Co−Fe‐oxides with different metal ratios were prepared by hydrothermal synthesis and compared during selective oxidation tests with propylene and isobutene. The active phases after several days on stream were investigated by synchrotron X‐ray diffraction (XRD) and Raman spectroscopy, while the structural evolution under reaction conditions was followed by operando Raman spectroscopy, synchrotron XRD, and multi‐edge X‐ray absorption spectroscopy. Similar structural transformations were observed during selective oxidation of propylene and isobutene, with similar influence on catalytic performance. A phase mixture of β‐CoMoO4/β‐Co0.7Fe0.3MoO4, γ‐Bi2MoO6, Fe3O4 and Bi3FeMo2O12 was observed, whereby high amounts of β‐CoMoO4/β‐Co0.7Fe0.3MoO4 increased selectivity to acrolein/methacrolein. In contrast, high amounts of γ‐Bi2MoO6 and Fe3O4 favoured total oxidation to CO and CO2. The simultaneous presence of β‐CoMoO4/β‐Co0.7Fe0.3MoO4, Bi3FeMo2O12 and Fe2O3 increased selectivity to methacrolein in isobutene oxidation, whereas no comparative increase in acrolein selectivity was observed in propylene oxidation. This suggests different key active phases in both reactions.

Impurity assessment, development and validation of an RP-HPLC method for the determination of eleven potential impurities of eltrombopag precursor

Eltrombopag is an oral non-peptide thrombopoietin receptor (TPO-R) agonist indicated for the treatment of thrombocytopenia in patients with persistent or chronic immune thrombocytopenia (idiopathic thrombocytopenic purpura, ITP) or chronic hepatitis C infection and the treatment of severe aplastic anemia. The purpose of this research was to assess the possible impurities that may carry over to eltrombopag from its precursor Eltro-1 (3′-amino-2′-hydroxy-[1,1′-biphenyl]-3-carboxylic acid) and to develop a specific analytical method for the determination of these impurities. Eltro-1 samples synthesized by two different synthesis routes were investigated during the evaluation and method development studies. Besides the expected process-related impurities (Eltro-1A – Eltro‐1J), e.g., starting materials, intermediates, and/or compounds formed from their further reactions, an unknown impurity detected above 0.10% was identified by LC-MS, synthesized and fully characterized by NMR, MS and FTIR (Eltro‐1K). Accordingly, an HPLC-RP method for the determination of eleven impurities (Eltro-1A – Eltro‐1K) in Eltro-1 was developed and validated according to ICH Q2. The control limits for impurities in Eltro-1 were set at ≤ 0.15% for Eltro-1A – Eltro‐1J and ≤ 1.0% for Eltro‐1K based on fate, spike-purge and carryover studies and in accordance with the ICH M7 classification for impurities in drug substance. Eltro-1 and eleven impurities at the specification limit were separated from each other and the diluent peaks with sufficient resolution without interference. Separation was performed on a Waters XBridge C18 column (150 × 4.6 mm, 3.5 μm) at 40 °C with a 10 µL injection volume at a detection wavelength of 220 nm and 15 °C sample temperature. The gradient elution is performed at a flow rate of 1.0 mL/min for 40 min with mobile phase A (0.1% orthophosphoric acid in water) and B (acetonitrile) according to the following program: Time (min) / Acetonitrile (%): 0/0, 35/70, 36/0, 40/0. Test and standard solutions were prepared at a concentration of 1.0 mg/mL and 1.0 µg/mL, respectively, using a mixture of mobile phase A and acetonitrile (75/25) as diluent. This is the first specific, selective, sensitive, linear, precise, accurate, and robust HPLC method for the determination of Eltro-1A – Eltro‐1K in Eltro-1, which showed no significant degradation under thermal stress, photostability (UV and VIS), and standard accelerated and long-term stability conditions.

Three-dimensional electron diffraction on clinkers: the belite α'H incommensurate modulated structure.

Traditional X-ray methods are extensively applied to commercial cement samples in order to determine their physical and chemical properties. Powder patterns are routinely used to quantify the composition of these phase mixtures, but structure determination becomes difficult because of reflection overlapping caused by the high number of different crystal structures. The fast-growing 3D electron diffraction technique and its related automated acquisition protocols arise as a potentially very interesting tool for the cement industry, since they enable the fast and systematic acquisition of diffraction data from individual particles. In this context, electron diffraction has been used in the investigation of the different crystalline phases present in various commercial clinkers for cement. Automated data collection procedures and subsequent data processing have enabled the structural characterization of the different crystal structures from which the α'H polymorph of Ca2SiO4 (belite) exhibited satellite reflections. Its average crystal structure has been known since 1971 and satellite reflections have been reported previously, yet the modulation was never fully described by means of the superspace formalism. Here, the incommensurately modulated structure is solved and refined using harmonic and crenel functions in the superspace group Pnma(α00)0ss, showing the potential of 3D electron diffraction for systematic crystallographic characterizations of cement. A full description of the different belite polymorphs is provided considering this modulated structure.

Mechanical and Microstructural Behavior of Sintered NiAl-Based High Entropy Alloy

A high entropy Ni-Al-Ti-Mn-Co-Fe-Cr alloy (HEA) system was fabricated using spark plasma sintering (SPS). The alloys at different elemental compositions were developed at a sintering temperature of 850 °C, a heating rate of 90 °C/min, a pressure of 50 MPa, and a dwelling time of 5 min. The sintered alloys' mechanical characteristics, microstructure, phase evolution, and density were assessed. The evolved microstructure of the sintered HEAs shows a homogenous dispersion of the alloying metals. The sintered microstructures showed a mixture of simple and complex phases. The phase refinement shows that the sintered HEAs exhibited a lower and the least grain size of 2.28 µm compared to the Ni50Al50 alloy having 8.26 µm. Likewise, a higher micro-strain value of 1.25E-1 was attained by the non-equal atomic HEA, while the unalloyed has 1.87E-3. The microhardness value of the sintered alloys varied from 103.5 HV to 139.2 HV, while their measured density varied from 5.23 g/cm3 to 6.44 g/cm3.