Modification Of Composition Research Articles

Laser powder bed fusion of a composition-modified IN738 alloy based on thermodynamic calculations

Defects, particularly cracking defects, severely limit the application of Ni-based alloys fabricated via the laser powder bed fusion (LPBF) additive manufacturing process. To address the processability/strength trade-off, in this study a new Ni-based alloy (IN738M) was designed via thermodynamic calculations based on the traditional IN738 alloy. The processability, microstructure, phase precipitation behaviour and mechanical properties were systematically examined. The results demonstrate that the LPBF-fabricated IN738M exhibited excellent LPBF processability, achieving crack-free fabrication even with a high γ′ phase mass fraction. The compositional modifications led to improvements in the microstructure, including the formation of a quasi-continuous carbide network at the interdendritic regions, altered grain orientation and grain refinement. This study also proposes a heat treatment strategy to achieve a bimodal distribution of the γ′ phases for IN738M; the cellular structure was eliminated, with numerous MC-type carbides observed within grains and at the grain boundaries. The IN738M alloy exhibited a superior combination of ultimate tensile strength values (1462 ± 23 MPa) and elongation values (10.2 ± 0.4 %) at room temperature compared to the IN738 alloy (932 ± 35 MPa and 2.6 ± 0.3 %, respectively). These findings will provide valuable guidance for developing Ni-based alloys with enhanced LPBF processability and mechanical properties.

Superior piezoelectric performance in holmium-substituted high-TC Bi5Ti3FeO15

High-temperature piezoelectric materials are essential for advanced sensor technologies, yet achieving both superior piezoelectric properties and a wide operating temperature range remains a persistent challenge. Bismuth titanate-ferrite (Bi5Ti3FeO15) is a promising candidate due to its notably high Curie temperature (TC) of approximately 761 °C. However, its low intrinsic piezoelectric response and limited poling efficiency, attributed to insufficient direct-current (dc) resistivity, have restricted its broader utilization. To address these issues, we explored compositional modifications by partially substituting A-site bismuth ions with holmium ions (Bi5-xHoxTi3FeO15, BTF-100xHo), aiming to enhance both piezoelectric performance and electrical resistivity. Comprehensive characterization was performed on the holmium-substituted ceramics, examining their crystal structure, microstructural attributes, and piezoelectric properties. Our findings reveal that the holmium-substituted Bi5Ti3FeO15 compositions exhibit significantly improved piezoelectric behavior in comparison to their unmodified counterparts. The optimized BTF-4Ho composition demonstrates a high piezoelectric coefficient (d33 = 23.1 pC/N) and an elevated TC of 795 °C. Moreover, the BTF-4Ho composition maintains stable electromechanical coupling across a wide temperature range, underscoring its potential for high-temperature sensor applications.

Multimodal Analysis of Corrosion for AA6016 Alloy at the Boundaries between Aluminum Matrix/Intermetallic Particles

Aluminum alloys are attracting attention as lightweight materials for automobiles, and the fact that intermetallic particles indispensable for improving strength of the alloys can be harmful to the corrosion resistance has become an issue. However, the initial corrosion behavior at the interface of intermetallic particles for aluminum alloys has been hardly examined using a comprehensive analysis method. In this study, a nano-micro scale multimodal analysis of Energy Dispersive X-ray Analysis (EDS), Electron Backscatter Diffraction (EBSD), and Kelvin Force Microscopy (KFM) was performed to clarify the initial corrosion behavior for AA6016. AA6016 specimens (20 × 20 × 1 mm) were subjected to SEM-EDS/EBSD measurements after mirror polishing, followed by continuous KFM measurements after ion milling. The specimens were then immersed in 100 mL of 0.5 wt% NaCl solution for 1 hour at a corrosion test. The surfaces of the specimens were cleaned with distilled water, dried and subjected to subsequent KFM measurements. The measurement of SEM-EDS was conducted again after the series of KFM measurements prior and post corrosion test. Fig. 1 shows SEM images of the typical specimen surface for AA6016 before corrosion tests. As shown in Fig. 1, two types of intermetallic particles: Al-Fe-Si and Mg-Si were identified by EDS measurements. The KFM measurements of the potential distribution on specimen surfaces confirmed that both intermetallic particles were noble in potential relative to the aluminum matrix. However, less significant difference in the potential was detected at the grain boundaries identified by the EBSD measurements. After the corrosion test, some trenches were formed at the boundaries of the Al-Fe-Si type particle, and the noble potential area expanded around the particle. As for the Mg-Si type particles, a dissolution of Mg was detected at the particle, and the noble potential region disappeared at the particles immediately after the corrosion test but reappeared with time. Furthermore, the formation of thick oxide films was implied after the corrosion test, especially at the boundaries of Al-Fe-Si type particle as well as at the Mg-Si type particle. Thus, the initial corrosion behaviors of AA6016 related to the compositional/electrochemical modifications at and around intermetallic particles were demonstrated by using the nano-micro scale multimodal (EDS-EBSD-KFM) analysis. Although the modifications of compositions (Mg and O) as well as noble potential distribution were restricted within the particle for Mg-Si type particle, they were expanded at the boundaries and around the particle for Al-Fe-Si type particle. The Al-Fe-Si type intermetallic particles would play more important role than those of Mg-Si type particles in promoting localized corrosion for AA6016. Figure 1

Operando Investigation of the Solid Electrolyte Interface in the Electrochemical Lithium-Mediated Ammonia Synthesis

Ammonia plays a crucial role in fertilizer production, but its conventional synthesis via the Haber-Bosch process is marked by high energy consumption, centralization, and dependence on non-renewable resources, resulting in considerable carbon emissions. In contrast, the lithium-mediated electrochemical nitrogen reduction reaction (Li-NRR) emerges as an innovative solution, enabling ammonia synthesis at room pressure and temperature with the potential for renewable energy integration [1]. This approach also promotes the decentralization of ammonia manufacturing. Within the Li-NRR framework, metallic lithium undergoes electrochemical deposition in an organic electrolyte and is believed to subsequently interact with inert nitrogen molecules, facilitating its protonation and the formation of ammonia [2].In recent years, significant research efforts aimed at boosting the selectivity and efficiency of the Li-NRR through the modification of electrolyte salt composition and concentration, alongside the implementation of potential cycling techniques [3-4]. These advancements are often attributed to alterations in the structure and composition of the solid electrolyte interface (SEI) formed on the cathode's surface, analogous to phenomena observed in lithium-ion batteries. Nonetheless, our current understanding of SEI properties primarily stems from ex situ analyses of the catalysts and the bulk electrolyte, leaving the behavior of this interface under reaction conditions largely unexplored.In this study, our aim is to deepen our understanding of the SEI's structure and composition under Li-NRR reaction conditions. Therefore, we employed cutting-edge operando spectroscopic techniques, such as surface-enhanced Raman spectroscopy, to closely examine the electrochemical interface during operational conditions. Taking inspiration from our expertise in lithium batteries we studied various electrolyte compositions and concentrations, including LiClO4 and LiFSI in tetrahydrofuran and ethanol to correlate the SEI’s properties with the performance of Li-NRR for ammonia production [5]. This approach enabled us to monitor the early stages of lithium plating and the subsequent formation and evolution of the SEI. Consequently, we could observe the changes and stability of various inorganic and organic SEI species, influenced by the initial composition of the electrolyte, and link them to the ammonia performance. Importantly, our investigations revealed ethanol's critical role in forming the organic SEI layer. By tracking nitrogen and hydrogen intermediates, we could further establish their correlation to the Li-NRR's efficiency, underscoring the competition with the hydrogen evolution reaction (HER). The mechanistic insights garnered from this study will aid in fine-tuning and enhancing the electrolyte composition for the improvement of Li-NRR in industrial applications.

(Invited) A Study of Si-based Metallic Glass Anodes for Li-ion Batteries

Silicon has been considered a promising low-cost negative electrode material for high-energy lithium-ion batteries due to its high gravimetric (400 Wh kg–1) and volumetric energy density (> 800 Wh L–1), low operating voltage (~0.3 V) and abundance in the Earth crust. During the past decades, development of Si-based negative electrodes has been greatly accelerated by modification of morphology, size, composition, and surface engineering. Accordingly, the cycle life of Si-based cells has improved dramatically over the years and is now approaching performance targets showing > 300 Wh kg–1 even after 1,000 cycles. However, as Si is gradually adopted into commercial batteries, the calendar life of the Si-based cells with high silicon content (>40%) is identified to be insufficient (1-2 years) and thus represents a major roadblock to widespread deployment. Interfacial instability of silicon in organic carbonate carbonate electrolytes and continuous electrolyte decomposition lead to a gradual electroyte consumption and shift of active lithium inventory in the cell. A steady growth of the SEI layer accompanies is linked with active lithium loss, which causes severe cell capacity fade and impedance rise. To prevent such a Si negative electrode and cell degradation mechanism, it is essential to exercise better control over the kinetics of electrolyte reduction and SEI layer formation process.Among various approaches to improve the interfacial as well as mechanical stability of silicon, embedding metallic inactive phases into amorphous Si matrix was widely studied. Dahn et al. has demonstrated this idea through a series of studies of over 200 different Si-based amorphous alloys1-3. Amorphous Si-alloys suppress two-phase coexistence of the Li-rich and Li-poor phase which leads to lattice mismatch and crack propagation. Thus, amorphous alloy films showed better capacity retention with less swelling and particle collapse. Furthermore, the inactive metal matrix serves as a buffer for the large volume expansion of Si (~280%), thus improving cycle stability without a significant decrease in the volumetric energy density.In this study we report on the synthesis and evaluation of Silicon-Me amorphous alloys (Me: Ni, Cu, Mn, Ti, Fe) for applications as negative electrodes in high-energy density Li-ion batteries with improved calendar life. Numerous Si-Me metallic glass alloy model electrodes were synthesized, using ultra-fast laser and splat quenching techniques to screen, evaluate, and optimize their electrochemical performance with a focus on the long-term interfacial stability in Li-ion batteries. Si0.85Ni0.15 has emerged as the best performing metallic glass alloy composition and its fabrication was successfully scaled-up with melt spinning technique. The melt-spun Si0.85Ni0.15 thin ribbon was ball-milled into fine powder to be used in conventional composite electrode fabrication for Li-ion batteries. Metallic glass Si0.85Ni0.15 anode showed improved passivation behavior and outperformed a conventional nano-sized Si electrode in both cycle and calendar life tests.AcknowledgementsThis research was supported by the US Department of Energy (DOE)’s Vehicle Technologies Office under the Silicon Consortium Project directed by Brian Cunningham and managed by Anthony Burrell. The work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. This research also used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231; in particular, Beamline 2.4 was used. Melt-spinning production rates and metrics are provided from ECO FM Co. References Fleischauer, M. D.; Dahn, J. R., Combinatorial Investigations of the Si-Al-Mn System for Li-Ion Battery Applications. J. Electrochem. Soc. 2004, 151 (8), A1216.Hatchard, T. D.; Topple, J. M.; Fleischauer, M. D.; Dahn, J. R., Electrochemical Performance of SiAlSn Films Prepared by Combinatorial Sputtering. Electrochemical and Solid-State Letters 2003, 6 (7), A129.Fleischauer, M. D.; Topple, J. M.; Dahn, J. R., Combinatorial Investigations of Si-M (M = Cr + Ni, Fe, Mn) Thin Film Negative Electrode Materials. Electrochemical and Solid-State Letters 2005, 8 (2), A137.

Transition Metal Dissolution: Impacts on Cell Performance and Mitigation by Electrolyte Formulation

Layered lithium transition metal oxides with nickel, cobalt, and/or manganese are nearly ubiquitous as cathodes in lithium-ion batteries for high energy density applications. As the cells age through cycling or exposure to high temperatures, degradation mechanisms within the battery can lead to release of transition metals from the cathode lattice. The dissolution of transition metals from the cathode and deposition on the anode have been linked to increased capacity fade and poor coulombic efficiency, attributed to constant degradation of electrolyte at the anode interface and lithium inventory loss.1 Orbia’s Battery Materials Innovation Center (formerly known as Silatronix) specializes in the design, synthesis, formulation, and optimization of electrolyte components for specific applications, as well as electrolyte performance cell testing and cell post-mortem analyses. In this study, we explored modification of the electrolyte composition as a method to reduce transition metal dissolution in Gr/NMC811 multi-layer pouch cells. Battery tests under a variety of aging conditions such as high temperature cycling, low temperature cycling, calendar life, and high-rate tests were studied to understand the conditions that lead to transition metal dissolution, which was quantified by ICP-OES. The relationships between transition metal dissolution and cell performance were investigated, including correlations between capacity fade, cell impedance, voltage hysteresis, and lithium plating. Next, a wide range of electrolyte formulations were tested under the above aging conditions and the effects of electrolyte composition were assessed, including the selection and concentration of solvents, additives, and salts, on transition metal dissolution and performance impacts. Electrolyte components that consistently reduce manganese dissolution and improve cell performance under a wide range of conditions were identified and are discussed in this presentation. These results provide insights into the practical design of electrolytes for reducing transition metal dissolution in a manner that is specifically correlated with performance improvements.

Unlocking Stainless Steel’s Potential for the Hydrogen Evolution Reaction Using Patterned Electrodes

The world's dependence on fossil fuels for transportation and power continues to contribute to anthropogenic climate change. However, fossil fuels are depletable resources and therefore a renewable fuel and energy source is needed in the immediate future [1]. Hydrogen is an ideal candidate to replace fossil fuels. Energy can be stored in hydrogen bonds and released as electricity by hydrogen fuel cells, creating only heat and water in the process [2]. Traditionally, hydrogen is produced from steam methane reforming and coal gasification, where carbon dioxide is generated in tandem [3]. Therefore, a renewable method to produce hydrogen is needed. Hydrogen can be produced with zero carbon emissions in water electrolysis, provided the electricity used is renewable, e.g. wind, solar, hydro.Currently, the widespread application of water electrolysers is limited by the sluggish kinetics of the oxygen/hydrogen evolution reactions (OER and HER, respectively) that require large overpotentials and complex multistep proton-coupled electron transfer processes, thus limiting the overall efficiency. Efficient electrodes for water electrolysis are based on expensive and scarce platinum group metals, further limiting the widespread application of water electrolysis [4]. Ideally, water electrolysis electrodes should have high corrosion resistance, conductivity, catalytic activity, and surface area while being low-cost, widely available and scalable. Alkaline water electrolysis allows for non-noble, low-cost, transition metal oxides to be used as they are relatively stable thermodynamically compared to acidic environments [5]. Recently, Ni-Fe layered double hydroxides were shown to have high electrocatalytic activity and stability for the OER in alkaline conditions [6]. This led to a series of studies on optimising the activity of stainless steel, owing to it being an alloy predominantly composed of Fe and Ni while being low cost, widely available and having excellent corrosion resistance.In this research, we utilise laser surface texturing, a scalable, efficient and widely used technique to modify surface area and morphology [7]. We create microchannel arrays with 20 µm channels spaced 10-200 µm apart on stainless steel 304 (SS304), thus systematically increasing the electrodes’ surface area. The electrode performance for the OER/HER was evaluated by slow linear sweep voltammetry in a 3-electrode cell containing 1 M KOH. Results show that the HER performance is strongly influenced by surface area and morphology while OER is relatively unimpacted (Figure 1). Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy and cyclic voltammetry suggests the performance is not a result of modification of the surface composition. Tafel slope analysis shows that all textured electrodes have similar Tafel slopes to the planar electrodes, indicating that the texturing does not affect the rate-determining step revealing that increasing surface area is key to unlocking stainless steel’s potential for the HER.[1] S. Shafiee and E. Topal, “When will fossil fuel reserves be diminished?,” Energy Policy, vol. 37, no. 1, pp. 181–189, Jan. 2009, doi: 10.1016/j.enpol.2008.08.016.[2] W. Lubitz and W. Tumas, “Hydrogen: An Overview,” Chem. Rev., vol. 107, no. 10, pp. 3900–3903, Oct. 2007, doi: 10.1021/cr050200z.[3] M. Amin et al., “Hydrogen production through renewable and non-renewable energy processes and their impact on climate change,” International Journal of Hydrogen Energy, vol. 47, no. 77, pp. 33112–33134, Sep. 2022, doi: 10.1016/j.ijhydene.2022.07.172.[4] Y. Jiao, Y. Zheng, M. Jaroniec, and S. Zhang Qiao, “Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions,” Chemical Society Reviews, vol. 44, no. 8, pp. 2060–2086, 2015, doi: 10.1039/C4CS00470A.[5] M. Chatenet et al., “Water electrolysis: from textbook knowledge to the latest scientific strategies and industrial developments,” Chem. Soc. Rev., vol. 51, no. 11, pp. 4583–4762, Jun. 2022, doi: 10.1039/D0CS01079K.[6] M. Gong et al., “An Advanced Ni–Fe Layered Double Hydroxide Electrocatalyst for Water Oxidation,” J. Am. Chem. Soc., vol. 135, no. 23, pp. 8452–8455, Jun. 2013, doi: 10.1021/ja4027715.[7] K. M. T. Ahmmed, C. Grambow, and A.-M. Kietzig, “Fabrication of Micro/Nano Structures on Metals by Femtosecond Laser Micromachining,” Micromachines, vol. 5, no. 4, Art. no. 4, Dec. 2014, doi: 10.3390/mi5041219. Figure 1

Isovalent Co-Substitution of Iron and Titanium into Single-Crystal NMC622

Recently, all-dry (i.e., solvent-free) synthesis methods for Ni-rich nickel-manganese-cobalt (NMC) cathode active materials, Li(Ni a Mn b Co1-a-b )O2 (NMC, a ≥ 0.5), have enabled the use of metal oxide feedstocks to be used as precursors.1 Such all-dry methods provide new opportunities for compositional modification in NMCs. In the search for more sustainable, high-performance Ni-rich alternatives to NMC, Fe and Ti have been identified as attractive substitutes for Co and Mn, respectively.2–4 Herein, using all-dry synthesis methods, both individual and isovalent co-substitution of Fe and Ti into single-crystal (SC) NMC622, according to Li(Ni0.6Mn0.2-y Co0.2-x Fe x Ti y )O2 (0 ≤ x, y ≤ 0.2), were conducted.In these studies, it was found that Fe-substitution resulted in increased inter-site mixing, resulting in increased polarization and reduced capacity retention. However, Ti-substitution resulted in an increase in Ni3+ content, leading to improved capacity retention. These effects were found to be independent of each other, so that Ti additions could effectively offset some of the negative aspects of Fe-substitution. Such studies could point the way to enabling increased Fe-content in NMC. Additionally, layered Mn-free Li(Ni0.6Ti0.2Co0.2)O2 (NTC622) was produced as an endmember of this series with low levels of cation mixing. This is the first time to our knowledge that a fully ordered NTC622 composition has been reported. As a consequence of its ordered structure, the NTC622 made here was found to have far superior electrochemical performance in comparison to previous attempts reported in the literature.5,6 These results demonstrate the viability of Ti-rich cathode material compositions, such as NTC622, presenting an avenue for cathode materials synthesized by all-dry methods.7In this presentation the effects of Ti and Fe individual and co-substitution in single-crystal Li(Ni0.6Mn0.2-y Co0.2-x Fe x Ti y )O2 (0 ≤ x, y ≤ 0.2) made by all-dry methods will be discussed, including structural changes, changes in oxidation states as measured by X-ray absorption near-edge spectroscopy (XANES), and electrochemical performance; with special emphasis on the end-member composition of NTC622.References(1) Zheng, L.; Bennett, J. C.; Obrovac, M. N. All-Dry Synthesis of Single Crystal NMC Cathode Materials for Li-Ion Batteries. J Electrochem Soc 2020, 167 (13), 130536. https://doi.org/10.1149/1945-7111/abbcb1.(2) Lu, M.; Han, E.; Zhu, L.; Chen, S.; Zhang, G. The Effects of Ti4+-Fe3+ Co-Doping on Li[Ni1/3Co1/3Mn1/3]O2. Solid State Ion 2016, 298, 9–14. https://doi.org/10.1016/j.ssi.2016.10.014.(3) Mi, C.; Han, E.; Sun, L.; Zhu, L. Effect of Ti4+ Doping on LiNi0.35Co0.27Mn0.35Fe0.03O2. Solid State Ion 2019, 340. https://doi.org/10.1016/j.ssi.2019.05.011.(4) Meng, Y. S.; Wu, Y. W.; Hwang, B. J.; Li, Y.; Ceder, G. Combining Ab Initio Computation with Experiments for Designing New Electrode Materials for Advanced Lithium Batteries: LiNi1/3Fe1/6Co1/6Mn1/3O2. J Electrochem Soc 2004, 151 (8), A1134. https://doi.org/10.1149/1.1765032.(5) Baster, D.; Paziak, P.; Ziąbka, M.; Wazny, G.; Molenda, J. LiNi0.6Co0.4-ZTizO2 - New Cathode Materials for Li-Ion Batteries. Solid State Ion 2018, 320, 118–125. https://doi.org/10.1016/j.ssi.2018.03.002.(6) Fujimoto, K.; Ikezawa, K.; Ito, S. Charge-Discharge Properties of a Layered-Type Li(Ni,Co,Ti)O2 Powder Library. Sci Technol Adv Mater 2011, 12 (5). https://doi.org/10.1088/1468-6996/12/5/054203.(7) Tahmasebi, M. H.; Obrovac, M. N. Quantitative Measurement of Compositional Inhomogeneity in NMC Cathodes by X-Ray Diffraction. J Electrochem Soc 2023, 170 (8), 080519. https://doi.org/10.1149/1945-7111/acefff. Figure 1

Defect and Interphase Engineering in Electrode Materials for Lithium-Ion Batteries

One of the fundamental challenges in the synthesis of solid-state materials is identifying the precise range of conditions under which a desired phase will be formed. In particular, the controlled synthesis of metastable crystalline materials is especially challenging as they are, by definition, thermodynamically unfavorable relative to other phases under typical experimental conditions. At the other extreme, amorphous materials represent a high-energy phase that can be readily formed through well-established experimental techniques such as high temperatures, ball milling, and electrochemical means. Work by Aykol et al.1 in 2018 has shown that amorphous materials represent an “upper thermodynamic limit” for the synthesis of metastable inorganic materials. In this talk, we will present electrochemically-driven amorphous-to-crystalline transformations as a controllable means to introduce composition modification in metal oxides to form high performance disordered rock salt negative electrodes.2–4 The second part of the talk includes our recent progress in operando electrochemical atomic force microscopic (EC-AFM) characterizations5,6 of the solid electrolyte interphases in carbonaceous electrode materials. References M. Aykol, S. S. Dwaraknath, W. Sun, and K. A. Persson, Science Advances, 4, eaaq0148 (2018) https://www.science.org/doi/10.1126/sciadv.aaq0148.H. Xiong et al., J. Phys. Chem. C, 116, 3181–3187 (2012) https://doi.org/10.1021/jp210793u.H. Xiong et al., Phys Rev Lett, 110 (2013) ://WOS:000314870300013.P. Barnes et al., Nat. Mater., 21, 795–803 (2022) https://www.nature.com/articles/s41563-022-01242-0.H. Zhu et al., Small, 17, 2105292 (2021) https://doi.org/10.1002/smll.202105292.L. Tao et al., J. Am. Chem. Soc., 145, 16538–16547 (2023) https://doi.org/10.1021/jacs.3c03429.

Influence of Thermomechanical Treatments and Chemical Composition on the Phase Transformation of Cu-Al-Mn Shape Memory Alloy Thin Sheets

This paper investigates the interrelated effects of thermomechanical treatments and chemical composition on the phase transformation capabilities of thin sheets made from Cu-Al-Mn shape memory alloys. The transformation capacity and transition temperatures were determined using DSC and DMA testing, while composition measurements were performed using SEM/EDX analysis. The results demonstrate that applying hot-rolling treatments to alloys of reduced thickness leads to manganese oxidation and modifications in chemical composition, adversely impacting the phase transformation performance. This effect can be mitigated by the use of cold rolling. Additionally, the presence of phosphorus impurities can create inclusions that bind manganese, preventing it from remaining in the solid solution and further affecting phase transformation capabilities.

Loss of Sterol Biosynthesis in Economically Important Plant Pests and Pathogens: A Review of a Potential Target for Pest Control.

Sterol biosynthesis is a crucial metabolic pathway in plants and various plant pathogens. Their vital physiological role in multicellular organisms and their effects on growth and reproduction underline their importance as membrane compounds, hormone precursors, and signaling molecules. Insects, nematodes, and oomycetes of the Peronosporales group, which harbor important agricultural pests and pathogens, have lost the ability to synthesize their own sterols. These organisms rely on the acquisition of sterols from their host and are dependent on the sterol composition of the host. It is thought that sterol-synthesizing enzymes were lost during co-evolution with the hosts, which provided the organisms with sufficient amounts of the required sterols. To meet the essential requirements of these organisms, some sterol auxotrophs retained a few remaining sterol-modifying enzymes. Several molecular and biochemical investigations have suggested promising avenues for pest and pathogen control by targeting host sterol composition, sterol uptake, or sterol modification in organisms that have lost the ability to biosynthesize sterol de novo. This review examines the loss of sterol biosynthesis de novo in insects, nematodes, and oomycetes with the aim of investigating the sterol metabolic constraints and sterol acquisition of these organisms. This will shed light on its potential as a control target for the management of sterol-dependent organisms in a comprehensive agronomic approach.

Bayesian Learning Aided Theoretical Optimization of IrPdPtRhRu High Entropy Alloy Catalysts for the Hydrogen Evolution Reaction.

The complex compositional space of high entropy alloys (HEAs) has shown a great potential to reduce the cost and further increase the catalytic activity for hydrogen evolution reaction (HER) by compositional optimization. Without uncovering the specifics of the HER mechanism on a given HEA surface, it is unfeasible to apply compositional modifications to enhance the performance and save costs. In this work, a combination of density functional theory and Bayesian machine learning is used to demonstrate the unique catalytic mechanism of IrPdPtRhRu HEA catalysts for HER. At high coverage of underpotential-deposited hydrogen, a d-band investigation of the active sites of the HEA surface is conducted to elucidate the superior catalytic performance through electronic interactions between elements. At low coverage, a novel Bayesian learning with oversampling approach is then outlined to optimize the HEA composition for performance improvement and cost reduction. This approach proves more efficacious and efficient and yields higher-quality structures with less training set bias compared with neural-network optimization. The proposed HEA optimization theoretically outperforms benchmark Pt catalysts' overpotential by ≈40% at a 15% reduced synthesis cost comparing to the equiatomic ratio HEA.

Circumventing cracking in grading 316L stainless steel to Monel400 through compositional modifications in directed energy deposition

In joining Fe-alloys and Cu-containing alloys to access the high strength of steels and corrosion resistance of Cu-alloy, cracking is widely observed due to the significant Cu microsegregation during the solidification process, resulting in an interdendritic Cu-rich liquid film at the end of solidification. By fabricating functionally graded materials (FGMs) that incorporate additional elements like Ni in the transition region between these terminal alloy classes, the hot cracking can be reduced. In the present work, the joining of stainless steel 316L (SS316L) and Monel400 by modifying the Ni concentration in the gradient region was studied. A new hot cracking criterion based on hybrid Scheil-equilibrium approach was developed and validated with monolithic multi-layer samples within the SS316L-Ni-Monel400 three-alloy system and a SS316L to 55/45 wt% SS316L/Ni to Monel400 FGM sample fabricated by direct energy deposition (DED). The new hot cracking criterion, based on the hybrid Scheil-equilibrium approach, is expected to help design FGM paths between other Fe-alloys and Cu-containing alloys as well.

Impact of processing and storage on citrus fiber functionality: Insights from spectroscopic techniques

To deliver their functionality when used in applications, citrus fibers need to be rehydrated. Factors such as chemical composition, structural organization as well as chemical surface composition are known to influence this functionality. Processing and storage conditions can affect these parameters, making it challenging to maintain stable functionality. This study used Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) to evaluate the effects of preparation and storage on citrus fibers. Samples dried at different scales and stored for 360 days under room and accelerated conditions were assessed for water holding capacity (WHC), water swelling capacity (WSC), and gel rigidity (G′). The results showed a decline in WHC, WSC, and G′ over time, confirming that aging negatively impacts moisture retention, particularly under higher water content or temperature. Drying scale had no effect on chemical composition or structure, but changes in the elemental surface composition of carbon and oxygen were noted. While prolonged storage altered the polysaccharides' chemical composition and structure, leading to functionality loss, XPS analysis revealed no changes in surface composition. Loss of functionality cannot be explained by chemical surface composition modifications.

Effects of combining ultrasound and dual enzymolysis with hydroxypropylation, acrylate grafting, or phosphate grafting on the physicochemical and functional properties of oil palm mesocarp expeller dietary fiber

Oil palm mesocarp expeller is an abundant and low-cost dietary fiber resource, but its poor hydration and adsorption properties limit its utilization in foods. Therefore, ultrasound and enzymolysis combined with hydroxypropylation, acrylate grafting, or phosphate grafting were used to improve the adsorption properties of oil palm mesocarp expeller fiber (OPMEDF) for the first time. The results revealed that these composite modifications made the microstructure of OPMEDF more porous, and significantly increased its soluble fiber content, surface area, hydration properties, and sorption abilities of glucose, nitrite, copper, and lead ions but decreased its brightness. OPMEDF modified by ultrasound, enzymolysis, and acrylate grafting had the highest content of extractable polyphenol and sorption abilities on oil and nitrite ion. OPMEDF subjected to ultrasound, enzymolysis, and phosphate grafting showed the highest water-swelling volume (3.84 mL g−1) and sorption abilities of copper (II) and lead (II) ions. Notably, OPMEDF modified by ultrasound, enzymolysis, and hydroxypropylation exhibited the highest soluble fiber content (14.72 g∙100 g−1), water-retention ability (5.22 g g−1), viscosity (13.90 cp), and glucose adsorption capacity (38.18 g∙100 g−1). These results indicated that these composite modifications are good options to improve the adsorption capacities of OPMEDF and can expand its potential hypoglycemic and hypolipidemic effects.

Characterization of porosity and permeability in Nata De Soya porous membranes with composition modifications

Characterization of porosity and permeability in Nata De Soya porous membranes with composition modifications

Fabrication of functionally graded cemented carbide via carbon-induced shell structure binder jet 3D printing

Functionally graded (FG) WC-Co cemented carbide overcomes the trade-off in hardness and toughness, simultaneously achieving high hardness and high toughness. It is mainly fabricated by creating a difference in carbon content between the surface and the interior. This drives the migration of liquid-phase cobalt from the surface to the core, forming a gradient structure with a cobalt-deficient surface and cobalt-rich core. Inspired by the recent advancements in shell structure binder jetting (BJ) 3D printing, which selectively deposits binder around the model's outline to form a shell encasing the loose powder at the core, it is possible to achieve different carbon contents in the shell and core regions by adjusting the carbon content in the binder solution. In this study, a phenolic resin-based binder, yielding high carbon residue post-sintering, was prepared to investigate the impact of the carbon gradient formed by shell printing in the WC-12Co cemented carbide green part on fabricating FG WC-12Co. The effects of shell thickness and sintering temperature on the fabrication of FG WC-12Co were investigated. The results demonstrate that the binder residual carbon within the shell facilitates cobalt migration towards the core region when Co(solid)-Co(liquid)-WC three-phase coexists (1275°C-1325°C). This process results in the formation of the gradient structure with a cobalt-deficient shell and cobalt-rich core. The FG WC-12Co produced through carbon-induced shell printing yielded an increase in both surface hardness (1347.8 HV10) and transverse rupture strength (1542.91 MPa). It is feasible to fabricate FG WC-Co with adjustable Co-deficient layer thickness by controlling the shell thickness during the printing process. This study investigated the viability of fabricating FG materials through the modification of binder chemical composition in conjunction with shell structure BJ 3D printing.

Corrosion behaviour of medium entropy alloy deposited on low carbon steel substrate by innovative welding method

In recent decades, thanks to the advancements within materials science and engineering, a novel class of metallic compounds, named high and medium-entropy alloys, has begun to capture the attention of researchers worldwide. Despite their excellent mechanical and anticorrosive properties, the widespread usage of these materials in industrial applications still remains a challenge and a subject worthy of investigation. In the present work, an innovative concept of developing high and medium-entropy alloys by deposition welding technique is presented and analysed in detail. Melting a bundle of rods by the Gas Tungsten Arc Welding (GTAW) method, in the same molten pool, a medium-entropy alloy (MEA) from the AlCrFeNi system is deposited on a low carbon steel substrate. In order to increase the chemical homogenization of the deposited material and to eliminate or reduce the eventual defects that may occur, electric arc remelting without using filler metal was performed in transverse, longitudinal, or combined (transverse and longitudinal) direction relative to the initial deposition welding direction. The assessment of the resistance to corrosion, modifications of microstructure, chemical composition and hardness have revealed that the medium-entropy alloy, obtained by melting in the same welding pool of several common welding rods with various chemical compositions, is an innovative, sustainable, and advantageous alternative to stainless steel materials.

Study of the Structure and Properties of Concrete Modified with Nanofibrils and Nanospheres

The application of modifying nanoadditives in the technology of cement composites is currently a relevant and widely researched topic in global materials science. The purpose of this study was to investigate new nanoadditives—nanofibrils made from synthesized wollastonite (NF) and nanospheres from corundum (NS)—produced by LLC NPK Nanosystems (Rostov-on-Don, Russia) as a modifying additive. During the experimental investigations, the mechanical properties of cement pastes and concrete were examined. This included an analysis of the density, compressive and bending strength, as well as water absorption of concrete that had been modified with NF and NS additives. X-ray phase and microstructural analyses of concrete were performed. It was established that modification of cement composites with NF and NS additives had a beneficial effect on their properties, and the optimal amount for both types of additives was 0.3% by binder weight. The highest recorded enhancements in compressive and flexural strength of concrete with 0.3% NF were 7.22% and 7.04%, respectively, accompanied by a decrease in water absorption by 4.70%. When modifying concrete with 0.3% NS, the increases in compressive and flexural strength were 2.71% and 2.48%, and water absorption decreased by 1.96%. Modification of concrete with NF and NS additives did not have a significant effect on the change in concrete density, which was no more than 1%. Based on the results of phase analysis, it was established that concrete with NF and NS additives were characterized by the presence of five main phases: quartz, portlandite, calcite, larnite, and olivine-Ca. It was found that compositions with 0.3% NF and NS differed from the control composition by the presence of such a phase as olivine-Ca. Microstructural analysis confirmed the effectiveness of NF and NS additives. The microstructure of the modified concretes was distinguished by the extensive occurrence of clusters composed of calcium silicate hydrate zones. The conducted studies prove the possibility of using NF and NS as modifying nanoadditives in the technology of cement composites. The addition of nanofibrils from synthesized wollastonite is the most effective and promising and is recommended for use in real construction practice.

Defect-controlled confined growth of nano-MOFs to prepare materials with hierarchical micro/mesoporous structures for efficient CO2 capture

In recent years, nanoporous materials with special structure have been widely used in various fields. In view of the poor stability of MOFs materials and the poor mass transfer ability, in this study, we developed a simple method to restrict the growth of UiO-66-NH2 crystals in hollow silica by “vacuum evaporation” strategy, different kinds of acid regulators were introduced, to obtain a composite material with hierarchical pore structure. By characterizing the physical chemistry and microstructure of the composite adsorbent, and calculating the structural defects under different acid regulation, the adsorption and desorption performance and stability of the adsorbent for CO2 were comprehensively investigated. The mechanism of action on CO2 was further analyzed by in-situ infrared and other techniques. The results show that the change of coordination environment and coordination rate caused by the competition of organic acids, which increases the defects and reduces the nucleation and aggregation effect of UiO-66-NH2, promotes the formation of hierarchical pore structure of the composites. Among them, benzoic acid is the best regulating monocarboxylic acid, which makes UiO-66-NH2 have good dispersion in the cavity and suitable crystal size. The specific surface area of the composite material is 717.96 m2 g−1. At the same time, due to its excellent CO2 adsorption capacity (3.35 mmol g−1) at 298 K and 1.06 bar, it is 48.07 % higher than the original UiO-66-NH2. In order to accomplish the goal of effective CO2 adsorption performance of composites, this study offers a novel approach for the synthesis and modification of MOFs-based composites.