Structure Of Precursor Research Articles

Liquid-phase synthesis of a Li3PS4 solid electrolyte using ethyl isobutyrate as a synthetic medium

A β-Li3PS4 solid electrolyte was prepared via liquid-phase synthesis using ethyl isobutyrate as a synthetic medium. The precursor and solid electrolyte structures were characterized using thermogravimetry–differential thermal analysis and X-ray diffraction techniques. The dielectric relaxation analysis showed two relaxation regions, which revealed a bulk and grain boundary ionic migration process. At a temperature lower than 90°C, the frequency dependence of the dielectric constant of the prepared sample was different from that of glassy Li3PS4, indicating that the motion of the PS4 unit enhances the ionic conductivity of the Li3PS4 solid electrolyte. The ionic conductivities of the cold-pressed and warm-pressed pellets at 25°C were 6.8 × 10−5 Scm−1 and 3.6 × 10−4 Scm−1, respectively.

Solvent Choice during Flow Assembly of Photocross-Linked Single-Chain Nanoparticles and Micelles Affects Cellular Uptake.

Polymeric micelles have widely been used as drug delivery carriers, and recently, single-chain nanoparticles (SCNPs) emerged as potential, smaller-sized, alternatives. In this work, we are comparing both NPs side by side and evaluate their ability to be internalized by breast cancer cells (MCF-7) and macrophages (RAW 264.7). To be able to generate these NPs on demand, the polymers were assembled by flow, followed by the stabilization of the structures by photocross-linking using blue light. The central aim of this work is to evaluate how the type of solvent affects self-assembly and ultimately the structure of the final NP. Therefore, a library of copolymers with different sequences, including block copolymers (AB, ABA, BAB), and statistical copolymers (rAB and rAC) was synthesized using PET-RAFT with A denoting poly(ethylene glycol) methyl ether acrylate (PEGMEA), B as 2-hydroxyethyl acrylate (HEA), and C as 4-hydroxybutyl acrylate (HBA). The polymers were conjugated with a quinoline derivative to enable the formation of cross-linked structures by photocross-linking during flow assembly. Using water as the dispersant for photocross-linking led to the preassembly of these amphiphilic polymers into compact SCNPs and cross-linked micelles, resulting in a quick photoreaction. In contrast, acetonitrile led to fully dissolved polymers but a low rate of the photoreaction. These intramolecularly cross-linked polymers were then placed in water to result in more dynamic micelles and looser SCNPs. Small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and size exclusion chromatography (SEC) coupled with a viscosity detector show that cross-linking in acetonitrile results in better-defined NPs with a shell rich in PEGMEA. Cross-linking in acetonitrile led to NPs with significantly higher cellular uptake. Interestingly, passive transport was identified as the main pathway for the delivery of our NPs on MCF-7 cells, confirmed by the uptake of NPs on cells treated with inhibitors and by red blood cells. This work underscored the importance of the polymer precursor's structure and the choice of solvent during intramolecular cross-linking in determining the drug delivery efficiency and biological behavior of SCNPs.

Investigation of Fibrillar Aggregates Formed by Pathogenic Pre-Pro-Vasopressin Mutants that Cause ADNDI.

Aggregations of unfolded or misfolded proteins, both inside and outside cells, are implicated in numerous diseases, collectively known as amyloidosis. Particularly, Autosomal dominant neurohypophyseal diabetes insipidus (ADNDI) is a rare disease caused by mutations in the AVP-NPII gene, leading to the inability to secrete arginine vasopressin (AVP). These misfolded proteins accumulate within the endoplasmic reticulum (ER), causing cellular dysfunction. This study aimed to investigate the formation of amyloid-like aggregates within the cell resulting from misfolded mutant precursor proteins, which induce disulfide-linked oligomers due to the G45C, 207_209delGGC, G88V, C98X, C104F, E108D-1, E108D-2 and R122H mutations identified by our group in the AVP-NPII gene of ADNDI patients. De-glycosylation studies were performed to analyze the glycosylation patterns of mutant protein precursors. The involvement of these precursors in the ER-related degradation pathway was studied by conducting protease inhibition experiments. Disulfide-linked oligomer analysis determined the oligomerization status of the mutant precursors. Immunofluorescence and electron microscopy studies provided evidence of aggregate structures in the ER lumen. In vitro studies involving bacterial expression and fibril formation in E. coli. Our findings demonstrated that the N-glycan structure of mutant precursors remains intact within the ER. Protease inhibition experiments indicated the involvement of these precursors in the ER-related degradation pathway. Disulfide-linked oligomer analysis revealed homo-oligomer structures in mutations. Immunofluorescence and electron microscopy studies confirmed the presence of aggregate structures in the ER lumen. In vitro studies showed that mutant precursors could form fibril structures in E. coli. Our study may support the idea that ADNDI belongs to the group of neurodegenerative diseases due to the formation of fibrillar amyloid aggregates in the cell.

Synthesis of tamsulosin precursor through palladium nanocatalytic hydrogenolysis: Crystal structure, DFT analysis, and ADME studies

The present work describes a potential method for the synthesis of industrially important Tamsulosine intermediate under milder reaction conditions. The major advantages include i) nano catalytic system and ii) ammonium formate is used as greener alternative during hydrogenolysis with an overall yield of 98 %. Density functional theory (DFT) studies in combination with B3LYP exchange-correlation functional method with split valence basis set 6–311 G is used to understand molecular structure of intermediate is also described. The crystal structure of tamsulosine precursor is elucidated by using single crystal x-ray crystallography is also reported. Therefore, this study is expected to bridge the need to optimize a greener alternative process in this hydrogenolysis reaction to synthesize tamsulosin precursor. ADME studies reveals that better oral bioavailability, aqueous solubility, Gastrointerstinal absorption and option “yes” in Lipinski, Ghose, Veber, Egan and Muegge rules.

Carbon molecular sieve gas separation membranes derived from in-situ crosslinked polyimide containing bromine groups

The network polyimide (PI) precursor is a promising candidate to fabricate the advanced carbon molecular sieve (CMS) membrane since its robust crosslinked structure could prevent pore structure collapse during CMS formation. Exploring the relationship between network PI precursor structure and CMS membrane is highly significant. Herein, a novel brominated network PI precursor was fabricated via in-situ cross-linking technique firstly, and then the thermally induced bromination/debromination process was applied to tune the microporosity and gas transport properties of network PI precursor and its derived CMS membranes. After the bromination/debromination and carbonization at 550 °C, the resultant CMS membrane exhibited both high gas permeability and gas selectivities compared to its un-brominated network PI precursor derived CMS membrane. This is due to the bromination/debromination and carbonization enable the CMS membrane possesses large d-spacing values (11.06 Å), high BET surface areas (538.57 m2/g), and high percentage (∼71 %) of ultra-micropores. For instance, 6F-TA/TA-Br-550/30 membrane exhibits great CO2/CH4 separation ability, with a CO2 permeability of 6300 Barrer and a CO2/CH4 selectivity of 46.11, which is suppressed the latest 2019 trade-off curves. We anticipate that the present bromination/debromination and carbonization could provide a fresh perspective on the rational design of network PI precursor and its derived CMS membrane with excellent gas separation performance.

Cross-linking matters: Building hard carbons with enhanced sodium-ion storage plateau capacities

Hard carbon is a promising anode material for sodium-ion batteries (SIBs). However, its commercialization is hampered by its relatively low capacity. This limitation primarily arises from the insufficient closed pore structures developed within the hard carbon. In this contribution, we precisely control the crosslinking structures of phenol-formaldehyde resin precursors by adjusting the catalyst amount, producing carbon materials with varied microstructures. We explore the relationship between the microstructures of the resin-derived hard carbon and its sodium storage performance. Our findings indicate that increasing the crosslinking degree of phenol-formaldehyde resins enhances the number of closed pores formed during high-temperature carbonization, thereby improving the plateau capacity. Notably, the hard carbon exhibits superior rate performance, due to its smaller closed pore diameter. This study provides an in-depth exploration of the relationship between precursor structural characteristics and the microstructures of hard carbons. By calculating the closed pore parameters, we elucidate the structure-performance relationship, demonstrating that optimizing the closed pore structures significantly enhances the electrochemical performance of hard carbons for SIBs. This research offers valuable insights for the development of high-performance hard carbon anodes, paving the way for the commercialization of SIBs.

CoCe composite catalyst for CO2 hydrogenation: Effect of pore structure

In order to realize the dual carbon goals of “carbon peaking” and “carbon neutrality”, the design and development CO2 hydrogenation catalyst with high performances is of great significance. In this study, the CoCe composite catalysts were prepared by different methods and used to CO2 catalytic hydrogenation. The physicochemical properties of the prepared catalysts were characterized by XRD, BET, TEM/HRTEM, and H2-TPD. The characterization results indicated that the studied CoCe composite catalytsts with different pore structure can be prepared by different preparation methods. The suitable preparation method can promote Co species to be dissolved into the CeO2 lattice to form Ce-O-Co solid solution, which can promote the corresponding Co species to be reduced by H2 to form active Co0 species. The large specific surface area and developed ordered mesoporous structure of the CoCe-HT catalyst precursor, which was prepared by hard-template method, are conducive to the formation of active Co0 species and activation of H2 to produce reactive H species. The CO2 hydrogenation activity of the studied CoCe composite catalysts follows the following order: CoCe-HT > CoCe-CP > CoCe-CA > CoCe-HY. The CoCe-HT catalyst showed high CO2 hydrogenation conversion of 53.9 % and good using stability at 360 °C for 600 min. However, the CoCe-CA prepared by complex method has a poor use stability.

Tailored Permeation Through ≈1 nm Thick Carbon Nanomembranes by Subtle Changes in Their Molecular Design.

Due to their nanoscale thickness (≈1 nm) and exceptional selectivity for permeation of gases, nanomembranes made of 2D materials possess high potential for energy-efficient nanofiltration applications. In this respect, organic carbon nanomembranes (CNMs), synthesized via electron irradiation-induced crosslinking of aromatic self-assembled monolayers (SAMs), are particularly attractive, as their structure can be flexibly tuned by choice of molecular precursors. However, tailored permeation of CNMs, defined by their molecular design, has not been yet demonstrated. In this work, it is shown that the permeation of helium (He), deuterium (D2) and heavy water (D2O) for CNMs synthesized from biphenyl-based SAMs on silver (C6H5-C6H4-(CH2)n-COO/Ag, n = 2-6) can be tuned by orders of magnitude by changing the structure of the molecular precursors by just a single methylene unit. The selectivity in permeation of D2O/D2 with an unprecedented value of 200000 can be achieved in this way. The temperature-dependent study reveals a clear correlation between the molecular design and the permeation mechanisms facilitating therewith tailored synthesis of molecular 2D materials for separation technologies.

Polymer concentration adjustment for homogeneous carbon nanofibers precursors

Introduction. Carbon nanofibers CNFs have emerged as an important material in many advanced applications, especially those related to high electrical conductivity. Objectives. The primary objective of this study was to prepare a homogeneous CNFs’ precursor (Polyacrylonitrile PAN nanofibers) with improved graphitization through controlling one of the solution parameters, that is, polymer concentration. Methods. Precursors of PAN nanofibers with the addition of multi-walled carbon nanotubes MWCNTs were prepared with two concentrations of 8% and 10% w/v PAN/MWCNTs to adjust the insertion and uniform distribution of MWCNTs within the PAN nanofibers. Field emission scanning electron microscopy FESEM was used to evaluate the morphology of the electro spun nanofibers and uniformity of the MWCNTs distribution within the PAN nanofibers. Fourier transform infrared spectroscopy FTIR was also conducted to notice the interaction between MWCNTs and PAN to yield precursor with better graphitization characteristics. Results. FESEM results revealed more uniformity and homogeneity in the precursor structure with increasing PAN/MWCNTs concentration from 8% to 10% w/v. FTIR results showed increased intensity of the characteristic peaks of PAN and a new peak emerged at approximately 659 cm−1(C=C) which is potentially formed by interactions with MWCNTs and might be associated with cross-linking. Conclusion. Increased PAN/MWCNTs concentration from 8% to 10% w/v improved the insertion of MWCNTs inside PAN nanofibers and FTIR indicated the interactions between the added MWCNTs and PAN in the precursor with better graphitization characteristics.

Unveiling the Role of Pyridinic Nitrogen and Diacetylene in the Hydrogen Evolution Reaction through Model Catalysts Prepared by On-Surface Reactions.

Metal-free carbon materials (MFCMs) have extensive applications in electrocatalysis because of their comparable catalytic activity to that of Pt/C in some cases. Understanding the structure-property relationship is crucial for the reasonable design of more efficient catalysts. To reveal the structure-property relationship of the hydrogen evolution reaction (HER), we prepared nanowire model catalysts on single-crystalline Au(111) electrodes through state-of-the-art on-surface synthesis. Temperature-dependent experiments were conducted to evaluate the HER activity of the nanoribbons functionalized with pyridinic nitrogen and diacetylene. According to our electrochemical results (overpotential, current density j0, and apparent activation energy), we demonstrate that the participation of diacetylene can promote the catalytic reaction for the HER through a synergistic effect. Based on the analysis of the activation entropy for the model catalysts, we attribute the synergistic effect of diacetylene groups to the large area of π···H-O bonding in the electric double layer, thus providing direct insight into the structural-property relationship of polymerized nanoribbons for the HER through the rational design of precursor structures. The nanoribbons prepared by on-surface synthesis can serve as prototype systems for model catalytic research on MFCMs.

CoAl composite catalysts derived from hydrotalcite-like compounds for CH4 efficient dry reforming

In this study, CoAlx-LDH hydrotalcite-like was used as the precursors to prepare the CoAlx-LD composite catalysts for the DRM reaction. The transition metal Co was the main catalytic active centers for the DRM reaction. The layered structure of the hydrotalcite-like CoAlx-LDH precursors promoted the highly dispersed Co0 active centers to be formed in the CoAlx-LD catalysts. In addition, synergistic effects between active sites, basic sites and oxygen vacancies can promote the DRM catalytic performances of CoAl composite catalysts. Meanwhile, the Co/Al mole ratio can regulate the active sites, basic sites and oxygen vacancies in the catalysts, thereby affecting its catalytic performances. The CoAl12-LD catalyst with a Co/Al mole ratio of 1/2 exhibited excellent DRM catalytic performances. The CH4 and CO2 conversions on the prepared CoAl12-LD catalyst achieved 86.8% and 53.4% at atmospheric pressure and 700 °C, respectively. In addition, the catalyst also showed excellent use stability in the DRM reaction.

Controlling the optoelectronic properties of nitrogen-doped carbon quantum dots using biomass-derived precursors in a continuous flow system

The synthesis of carbon quantum dots (CQDs) from high molecular weight biomass-derived precursors poses a significant challenge due to the complex molecular structures and low conversion efficiency. This work demonstrates a green, rapid, and sustainable continuous hydrothermal flow synthesis (CHFS) approach for nitrogen-doped carbon quantum dots (NCQDs) from various biomass-derived precursors, including high molecular weight polymeric sources like chitosan, lignin, and humic acid. We find that the precursor structure significantly impacts the size of the fabricated NCQDs and their optical properties. Citric acid, a low molecular weight precursor, yields NCQDs with excitation-independent emission, higher quantum yields, and low non-radiative losses, while NCQDs derived from polymeric precursors exhibit excitation-dependent, red-shifted, and lower efficiency emission. Theoretical calculations, performed to understand the configuration and distribution of nitrogen dopants within the NCQD structure, show that pyridinic and graphitic nitrogen atoms exhibit a strong preference to aggregate near the centre of the edge of the NCQD and not in the vertices nor in the graphitic core, thus affecting the HOMO and LUMO, bandgap, and light absorption and emission wavelengths. The life cycle assessment (LCA) analysis highlights the green and scalable advantages of the CHFS process for producing NCQDs compared to batch methods, making it a sustainable and economically viable approach for large-scale NCQD synthesis from high molecular weight biomass-derived precursors. Hence, the combination of experimental data and theoretical calculations provides a comprehensive understanding of the structure-property relationships in these NCQDs.

Unveiling the Mystery: How TR precursors lead to exceptional gas separation performance in CMSMs

One of the main issues with membrane-based gas separation lies in the unexplored relationship between the precursors and their derived carbon molecular sieve membranes (CMSMs). Herein, we designed a series of TR polymers with gradient PBO content as precursors to investigate the carbonization mechanisms of PBO structure. The process of transforming the polymer precursor into carbon structure throughout pyrolysis involves utilizing an array of characterization techniques along with pyrolysis simulation. Results indicated that a higher PBO content leads to stronger molecular sieving effect of the resulting CMSM. The TR-CMS-50 membrane demonstrated exceptional gas separation performance with high permeability (PH2 = 3154 and PCO2 = 1495 Barrer) as well as ultra-high H2/CH4 (384) and CO2/CH4 (166) selectivity, which far exceeded the newest Upper bound line, showing significant potential for practical applications. This may can be attributed to “delayed effect” of the PBO structure which requires pyrolysis at higher temperatures, leading to more intense pyrolysis and the release of nitrogen-containing substances. Meanwhile, PBO has a cyclic system with a strong aromatic structure that closely resembles a carbon strand, which probably facilitates aromatization and enables it to more easily integrate into CMS structure, resulting in a more orderly arrangement in the Langmuir phase and generating higher concentration of pyrrolic-N (58.7 % vs. 44.1 %) as well as graphitic-N (31.6 % vs. 17.2 %). Thus, increasing the PBO content makes the derived CMS denser and significantly enhances its molecular sieving capacity. This study offers new insights into the development of precursor structures that creates high-performance CMSMs.

Optimization of precursor structure by dispersants to promote nitrogen reduction process to prepare high-quality VN

In this study, three dispersants of polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) and citric acid (CA) are used to optimize the structure of the precursor in order to prepare high quality VN. Under optimum condition, the VN with nitrogen content of 17.94 % is prepared by adding 5 % PVP. The sequence of phase evolution from the precursor to VN is: APV → V2O5 → V6O13 → V7O13 → VO2 → V3O5 → V2O3 → (VC) → VN. The precursors of adding 5 % PVP have lower Ea of 0.17 kJ mol−1, 20.51 kJ mol−1 and 62.70 kJ mol−1 during reduction and nitration process, which is easier to be reduced and nitridated. PVP not only promotes the uniform dispersion of the carbon powders in the vanadium rich solution but also enhance the hydrogen bonding of APV ions to promote their nucleation and growth. The precursor with uniform and concentrated particle size distribution, complete and stable encapsulation of shell of APV and core of carbon powder, and uniform and moderate thickness of APV shell is successfully prepared by adding PVP. The precursor has a larger phase reaction interface and more reactive sites during the nitriding reduction process, which results in a faster reduction and nitriding rate. In comparison with the current process, the nitriding reaction temperature has been reduced from 1400 ∼ 1500 °C to 1150 ∼ 1200 °C, the reaction time has been shortened by 75 %, and the N2 consumption has been reduced by 40 %.

One-Stage Synthesis of Microporous Carbon Adsorbents from Walnut Shells—Evolution of Porosity and Structure

One-stage synthesis technology for preparing carbon adsorbents with tailored porosity from agricultural waste is worthwhile due to their extensive application value. Thermal gravimetric analysis, low-temperature N2 adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and Raman spectroscopy were used to record the structure transformations of carbon materials, namely pore development, proceeding in the course of the step-wise pyrolysis of renewable and low-cost raw materials such as walnut shells (WNSs), which was carried out within a temperature range of 240–950 °C in a CO2 flow. The minimum threshold carbonization temperature for preparing nanoporous carbon materials from WNSs, determined by the examination of the N2 adsorption data, was 500 °C. The maximum specific micropore volume and BET surface achieved in the process without holding a material at a specified temperature were only 0.19 cm3/g and 440 m2/g, respectively. The pyrolysis at 400–600 °C produced amorphous sp2 carbon. At a temperature as high as 750 °C, an increase in the X-ray reflection intensity indicated the ordering of graphite-like crystallites. At high burn-off degrees, the size of coherently scattering domains becomes smaller, and an increased background in X-ray patterns indicates the destruction of cellulose nanofibrils, the disordering of graphene stacks, and an increase in the amount of disordered carbon. At this stage, pores develop in the crystallites. They are tentatively assigned to crystallites with sizes of 15–20 nm and to micropores. According to the Raman spectra combined with the XRD and SAXS data, the structure of all the pyrolysis products is influenced by the complex structure of the walnut shell precursor, which comprises cellulose nanofibrils embedded in lignin. This structure was preserved in the initial stage of pyrolysis, and the graphitization of cellulose fibrils and lignin proceeds at different rates. Most of the pores accessible for gas molecules in the resulting carbon materials are associated with former cellulose fibrils.

High Capacitance Performance N, O Codoped Carbon Foams Synthesized via an All-In-One Step Carbonization of Molecular Salt Strategy.

The preparation of porous carbon is constrained by the extensive use and detrimental impact of activators and dopants. Therefore, developing green and efficient strategies that leverage the intrinsic properties and pretreatment of the materials to achieve self-activation and self-doping is particularly crucial for porous carbon materials. Herein, potassium histidine was utilized as the molecular salt precursor, attaining the efficient and streamlined preparation of porous carbon through a one-step carbonization process that enables self-activation, self-doping, and self-templating. More interestingly, the carbonization temperature significantly impacts the porous structure of the molecular salt precursors, the properties of the heteroatoms, and electrochemical performance. The designed electrodes exhibit high accessibility to electrolyte ions and effective ion-electron transport channels. Therefore, the optimal carbon material (KHis800) has an excellent mass-specific capacitance of 305.2 F g-1 at 0.2 A g-1, and a high capacitance retention rate of 115.6% (50,000 cycles at 5 A g-1). Notably, KHis800 also shows a maximum energy density of 19.6 Wh kg-1. This research is dedicated to exploring a more efficient preparation method for porous carbon material via molecular salts, offering insights for the sustainable development of carbon materials.

Novel nonsymmetrically benzimidazolium salts and their silver(I)-N-heterocyclic carbene complexes: Synthesis, DFT study and Anticancer activities

A series of unsymmetrically substituted N-heterocyclic carbene (NHC) precursors were synthesized from the action of 5,6-dimethylbenzimidazole or benzimidazole with various alkyl halides in DMF at 80 °C for 72 h . These compounds were used to synthesize NHC–silver(I) complexes (3) by reacting these NHC precursors with Ag2O in DMC.The prepared compounds were structurally verified by several spectroscopic techniques including 1H NMR, 13C NMR, FT-IR, LC-MS, and C, H, N analysis. The structures of the NHC precursors and their corresponding silver(I) complexes were also investigated theoretically using density functional theory (DFT) at the BLYP/TZ2P level to optimize geometries and assess electronic properties via Voronoi Deformation Density (VDD) charge analysis. Additionally, the newly synthesized ligands and silver(I) complexes were evaluated for their in vitro anticancer activity against three human cancer cell lines including hepatocellular carcinoma (HePG2), lung adenocarcinoma (A549) and breast adenocarcinoma (MCF7). Most of the newly synthesized silver(I) complexes exhibited better activity than the ligands, and the results have been compared with Cisplatin as a reference drug.

The self-assembly mechanism of ovotransferrin fibrils induced by subtilisin A and Ca2+ ions and their application in nutrient delivery and texture optimization for liquid food

The self-assembly behavior of proteins and peptides has been widely studied due to their ability to construct various nanostructures, such as nanotubes and nanofibrils. Understanding the self-assembly mechanism is of great significance for developing functional nanomaterials. Herein, we adopt a novel method to construct ovotransferrin (OVT) fibrils by subtilisin A hydrolysis and Ca2+ ions induced self-assembly with mild reaction conditions. The kinetic process of OVT fibrils formation contains lag, growth, and plateau stage. During the growth stage, OVT peptides self-assemble into precursor structures, which undergo morphological changes of twisted ribbons, helical ribbons, and nanotubes, ultimately closing to form mature fibrils. Ca2+ ions likely coordinate with the carboxyl groups of OVT peptides, aiding in the self-assembly process. And the secondary conformation is manifested as a β-sheet stacking. The mature OVT fibrils have distinct hollow and left-handed structures. Then OVT fibrils successfully encapsulate zeaxanthin (Zea) and improve its solubility and stability. Besides, OVT fibrils exhibit no in vitro cytotoxicity, and significantly reduce allergenicity to egg allergy patients compared to OVT. OVT fibrils delivery Zea into milk to develop Zea fortified dairy beverage and improve the viscosity of dairy beverage. OVT fibrils show a great potential as nutrient delivery and texture optimization for food application.

Enhancing strength and ductility of Al–Cu–Li alloys by microalloying both Er and Zr to promote complete transformation from δ′ (Al3Li) to T1 (Al2CuLi) precipitates

The impact of erbium (Er) on grain refinement in Al–Cu–Li alloys is limited by the thermodynamic instability of Al3Er inoculants. Nevertheless, the concurrent addition of both Er and Zr to Al–Cu–Li alloys results in a marked refinement of the average grain size. Er exerts a significant influence on the precipitation sequence within Al–Cu–Li alloys, promoting a complete transition from δ′ (Al3Li) and θ′ (Al2Cu) to T1 (Al2CuLi) precipitates during aging at 120 °C, thereby substantially enhancing both strength and ductility. Through high-resolution transmission electron microscopy (HRTEM), the underlying mechanism of the T1 nucleation by Er microalloying has been elucidated. It has been demonstrated that the presence of Er leads to the formation of solute enrichment regions (SERs) comprising Cu, Zn, Mg and Er. These SERs serve as catalysts for the development of Cu-rich atomic planes along the {111}Al, providing a direct precursor structure for T1 nucleation. Consequently, the synergistic microalloying of Zr and Er not only effectively refines the grain structure but also facilitates the elimination of the δ′ phase. The addition of Er facilitates the complete transformation of the δ′ phase into the strong and ductile T1 phase, resulting in a significant enhancement of the alloy's strength and ductility. Following 100 h of aging at 120 °C, the ultimate tensile strength has increased from 373 to 457 MPa, and the elongation after fracture has risen from 2.8% to 4.9%.

In Situ growth of high-crystallinity MOF@CTF core-shell hybrid heterostructures and their application in photoelectrochemical sensing of vancomycin

Vancomycin is a first-line drug for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant bacterial infections. It is of great significance to develop rapid detection methods for vancomycin in different matrices. In this work, a novel method for the in-situ preparation of MOF@CTF core-shell hybrid heterogeneous structures was proposed and applied to the photoelectrochemical detection of vancomycin. The insolubility of the imine precursor structure in homogeneous solvents and the Lewis acidic centers in the MOF structure induced the initial arrangement of CTF on the surface of PCN-224. By encapsulating a layer of highly crystalline CTF structure onto the initial morphology of PCN-224, a MOF@CTF heterogeneous structure was formed. Importantly, the introduction of anthracene-based electron-donating groups into the CTF structure and the formation of a donor-acceptor system with triazine rings enhanced the photoconversion efficiency of the heterogeneous structure by establishing a continuous separated built-in electric field within the core-shell structure. The successful in-situ synthesis of the core-shell hybrid heterogeneous structure was confirmed through microscopic morphology, PXRD, XPS, and FT-IR. Furthermore, investigations into the semiconductor properties of the heterogeneous structure, including semiconductor type, bandgap, and photo-voltage, were conducted. Results showed that the heterogeneous structure exhibited a doubled photocurrent density compared to the original PCN-224. Additionally, a molecularly imprinted photoelectrochemical sensor (MIPECS) for vancomycin was constructed. Under optimized conditions, the sensor demonstrated a superior concentration response range (0.1 nM - 1 μM) and detection limit (0.031 nM, 3σ/S, n = 11). Simultaneously, the potential applicability of the sensor in animal-derived foods, serum, and environmental water samples was evaluated, yielding satisfactory results.