Transmission Electron Microscopy Characterization Research Articles

Highly Green Fluorescent Carbon Dots from Gallic Acid: A Turn-On Sensor toward Pb2+ Ions.

Carbon dots (CDs) are emerging novel fluorescent sensing nanomaterials owing to their tunable optical properties, biocompatibility, and eco-friendliness. Herein, we report a facile one-pot hydrothermal route for the synthesis of highly green fluorescent CDs using gallic acid (GA) as a single carbon source in N,N-dimethylformamide (DMF) solvent, which serves as a nitrogen source and reaction medium. The optical properties of the synthesized GA-DMF CDs were systematically characterized by using UV-vis and photoluminescence spectroscopy, revealing strong green fluorescence. Further, to gain insights into their size and structural, elemental, and chemical composition, Fourier transform infrared, dynamic light scattering, high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction, and X-ray photoelectron spectroscopy characterization techniques were performed. HR-TEM analysis confirmed the formation of uniformly spherical GA-DMF CDs with an average particle size of 16 ± 6.1 nm. Notably, the GA-DMF CDs exhibited a highly selective and turn-on fluorescent response to Pb2+ ions in aqueous solutions, which was attributed to a chelation-enhanced fluorescence mechanism. The detection limit for Pb2+ ions was determined to be as low as 7.15 × 10-7 M, with a broad linear detection range of 30-130 μM, underscoring their sensitivity and practical application in water quality monitoring. This study introduces a novel, sustainable approach for synthesizing nitrogen-doped CDs with outstanding optical properties and highlights their unprecedented selectivity toward Pb2+ ions, advancing the development of efficient and eco-friendly sensing platforms for heavy metal detection.

Synergistic Modulation of Solid- and Cathode-Electrolyte Interphase via a Lithium Salt Additive toward Stable Sodium Metal Batteries.

Constructing feasible sodium metal batteries (SMBs) faces complex challenges in stabilizing cathodes and sodium metal anodes. It is imperative, but often underemphasized, to simultaneously regulate the solid-electrolyte interphase (SEI) to counter dendrite growth and the cathode-electrolyte interphase (CEI) to mitigate cathode deterioration. Herein, we introduce lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) as an efficacious additive in a carbonate-based electrolyte to extend cycle lifespan of full SMBs: the capacity retention reaches 77.8% after 8000 cycles at room temperature and 74.3% after 5000 cycles at 50 °C. Cryogenic transmission electron microscopy characterization reveals that LiTDI promotes formation of inorganics-condensed SEI and CEI. The former inhibits continuous electrolyte decomposition and ensures homogeneous sodium plating, while the latter shields cathode from transition metal dissolution. This study highlights the crucial role of LiTDI in stabilizing both anodes and cathodes in SMBs, and it provides insights into designing functional additives for synergistic modulation of SEI and CEI.

Modulation of RuO2 Nanocrystals with Facile Annealing Method for Enhancing the Electrocatalytic Activity on Overall Water Splitting in Acid Solution.

RuO2-based materials are considered an important kind of electrocatalysts on oxygen evolution reaction and water electrolysis, but the reported discrepancies of activities exist among RuO2 electrocatalysts prepared via different processes. Herein, a highly efficient RuO2 catalysts via a facile hydrolysis-annealing approach is reported for water electrolysis. The RuO2 catalyst dealt with at 200 °C (RuO2-200) performs the highest activities on both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acid with overpotentials of 200 mV for OER and 66 mV for HER to reach a current density of 100 mA cm-2 as well as stable operation for100 h. The high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) characterizations show that the activities of as-prepared RuO2 rely on the hydroxide group/lattice oxygen (OH-/O2-) ratio, size, and crystalline of RuO2. The density functional theory (DFT) calculation also reveal that the OH- would enhance the activities of RuO2 for HER and OER via modifying the electronic structure to facilitate intermediate adsorption, thereby reducing the energy barrier of the rate-determining step. The water electrolysis by using RuO2-200 as the catalyst on both anode and cathode demonstrates a stable generation of hydrogen and oxygen with high Faradic efficiency at a current density of ≈30 mA cm-2 and a potential of below 1.47 V.

Ferromagnetism and structural phase transition in monoclinic FeGe film

Binary compound FeGe hosts multiple structures, from cubic and hexagonal to monoclinic. Compared to the well-known skyrmion lattice in the cubic phase and the antiferromagnetic charge–density wave in the hexagonal phase, the monoclinic FeGe is less explored. Here, we synthesized the monoclinic FeGe films on Al2O3 (001) and studied their structural, magnetic, and transport properties. X-ray diffraction and transmission electron microscopy characterizations indicate that the FeGe films are epitaxial to the substrate. Unlike the antiferromagnetic bulk, the monoclinic FeGe films are ferromagnetic with Curie temperature as high as ∼800 K, contributing to the anomalous Hall effect in the transport measurements. Similar to the hexagonal FeGe, we captured a structural phase transition in the monoclinic FeGe films at ∼100 K in real and reciprocal spaces by transmission electron microscope. Our work enriches the phase diagram of the FeGe family and suggests that FeGe offers an ideal platform for studying multiphase transitions and related device applications.

Chain assembly of Rhodococcus bacteria with O-doped g-C3N4 for photocatalysis mediated high-performance partial nitrification: From nitrite resource evolution to device application.

Nitrogen conversion via partial nitrification-anammox (PN/A), utilizing nitrite as a key intermediate, is an ideal low-carbon approach for wastewater nitrogen removal. However, the partial nitrification process, which is rate-limited and relies on less common bacteria with slow reaction kinetics, poses challenges for high-throughput PN/A implementation. Herein, we developed a microbial/photocatalysis coupling system using Rhodococcus bacterial and O-doped g-C3N4 (OCN) photocatalysts. This approach leverages photogenerated electrons and free radicals from photocatalysts to directly activate microorganisms, enhancing the redox gradient. This intensification selectively inhibits the enzymatic conversion of nitrite to nitrate and its reduction to nitrogen in Rhodococcus bacteria. Consequently, it promotes a highly selective partial nitrification process, generating ample nitrite to facilitate anammox reactions. Transmission electron microscopy and electrochemical characterization showed bacteria forming chain-like assemblies on OCN particles, with the composite exhibiting a favorable redox profile, low impedance, and high stability. Ammonia conversion to nitrite reached 96 % in 3 days, with an enriched NO2- concentration of 36.3 mg/L, 10 times higher than the raw bacterial control. Hence, this strategy of constructing bacterial-photocatalysis system achieved high selectivity and efficiency in partial nitrification. Transcriptome and qPCR analyses showed upregulation of genes linked to the short-cut denitrification metabolic pathway. Photocatalyst band structure and redox potential analysis suggest a new bio-photoelectrochemical partial nitrification pathway. Finally, the feasibility and applicability in future industrial and ecological water treatment were validated through demo H-type reactors and aquarium experiments. These findings offer innovative perspectives for controlled modulation of ammonia nitrogen conversion focus on nitrite intermediate, advancing an energy-efficient, low-carbon nitrogen cycle.

Unified transmission electron microscopy with the glovebox integrated system for investigating air-sensitive two-dimensional quantum materials.

Transmission electron microscopy (TEM) is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics, phase transitions, and nanoscale structural details. While numerous intriguing physical properties have been revealed in recently discovered two-dimensional (2D) quantum materials, many exhibit significant sensitivity to water and oxygen under ambient conditions. This inherent instability complicates sample preparation for TEM analysis and hinders accurate property measurements. This review highlights recent technical advancements to preserve the intrinsic structures of water- and oxygen-sensitive 2D materials for atomic-scale characterizations. A critical development discussed in this review is implementing an inert gas-protected glovebox integrated system (GIS) designed specifically for TEM experiments. In addition, this review emphasizes air-sensitive materials such as 2D transition metal dichalcogenides, transition metal dihalides and trihalides, and low-dimensional magnetic materials, demonstrating breakthroughs in overcoming their environmental sensitivity. Furthermore, the progress in TEM characterization enabled by the GIS is analyzed to provide a comprehensive overview of state-of-the-art methodologies in this rapidly advancing field.

Phase Separation of CuPd Alloy Nanocatalysts in CO Oxidation.

Alloy nanocatalysts exhibit enhanced activity, selectivity, and stability mainly due to their versatile phases and atomic structures. However, nanocatalysts' "real" functional structures may vary from their as-synthesized status due to the structural and chemical changes during the activation and reaction conditions. Herein, we studied the activated CuPd/CeO2 nanocatalysts under the CO oxidation reaction featuring an atomic-scale phase separation process, resulting in a notable "hysteresis" in catalyst performance. Through the "identical-location" transmission electron microscopy (TEM) characterization, we found that the CuPd nanoparticles (NPs) evolve to a Cu2O/CuPd or CuPdOx phase depending on different surface planes of CeO2 supports under the reaction condition. The detailed dynamic information is obtained by in situ environmental TEM-in situ DRIFTS characterizations to further decouple the effect of pure CO and O2 gas. The interfacial binding energies between alloy nanoparticles and CeO2 supports are found to play a critical role in determining the phase separation behaviors. These atomic insights highlight the importance of both the phase separation of alloy nanocatalysts and in situ characterizations of "live" catalysts.

Biocompatible TA4 and TC4ELI with excellent mechanical properties and corrosion resistance via multiple ECAP.

Titanium (Ti), characterized by its exceptional mechanical properties, commendable corrosion resistance and biocompatibility, has emerged as the principal functional materials for implants in biomedical and clinical applications. However, the Ti-6Al-4V (TC4ELI) alloy has cytotoxicity risks, whereas the strength of the existing industrially pure titanium TA4 is marginally inadequate and will significantly limit the scenarios of medical implants. Herein, we prepared ultrafine-grained industrial-grade pure titanium TA4 and titanium alloy TC4ELI via the equal channel angular pressing method, in which the TA4-1 sample has ultrahigh strength of 1.1 GPa and elongation of 26%. In comparison with the micrometer-crystalline Ti-based materials, it showed a 35% reduction in wear depth and more than 10% reduction in wear volume, while the difference in the corrosion potential of the simulated body fluids was not significant (only ∼20 mV). XRD, electron backscatter diffraction, and transmission electron microscope characterization confirms that their superior strengths are mainly due to grain refinement strengthening.

Study on Microstructure and Corrosion Fatigue Resistance of 14Cr12Ni3Mo2VN Materials Based on the Composite Technology of High-Frequency Induction Quenching and Laser Shock Peening

This study investigated the microstructure, microhardness, and residual compressive stress of 14Cr12Ni3Mo2VN martensitic stainless steel treated with high-frequency induction quenching (HFIQ) and laser shock peening (LSP). Using rotating bending corrosion fatigue testing, the corrosion fatigue performance was analyzed. Results show that a microstructural gradient formed after HFIQ and LSP: the surface layer consisted of nanocrystals, the subsurface layer of short lath martensite, and the core of thick lath martensite. A hardness gradient was introduced, with surface hardness reaching 524 Hv0.1, 163 Hv0.1 higher than the core hardness. A residual compressive stress field was introduced near the surface, with a maximum residual compressive stress of approximately −575 MPa at a depth of 0.1 mm. Corrosion fatigue results indicate that cycle loading times of samples treated with HFIQ and LSP were 2.88, 2.04, and 1.45 times higher than untreated, HFIQ-only, and LSP-only samples, respectively. Transmission electron microscopy (TEM) characterization showed that HFIQ reduced the lath martensite size, while the ultra-high strain rate induced by LSP likely caused dynamic recrystallization, forming numerous sub-boundaries and refining grains, which increased surface hardness. The plastic strain induced by LSP introduced residual compressive stress, counteracting tensile stress and hindering the initiation and propagation of corrosion fatigue cracks.

Transmission Electron Microscope Characterizations of the Localized Corrosion Behavior of Biodegradable ZX21 Mg Alloy in Hanks’ Balanced Salt Solution

Magnesium (Mg) alloys attract a lot of attention as next-generation biodegradable implant materials due to their excellent biocompatibility and unique biodegradability. By utilizing Mg alloys as implants, Mg alloys can be degraded naturally in the human body, avoiding the second removal surgery. In addition, Mg alloys are promising for orthopedic applications because of their similar density and mechanical properties to bones, which mitigate the stress shielding effect. Among various Mg alloy systems, the ZX-series Mg alloys, which contain zinc (Zn) and calcium (Ca), show great potential for orthopedic applications since Zn and Ca are essential for metabolism and bone regeneration and improve the mechanical strength of the alloys. However, localized corrosion of a ZX-series Mg alloy was reported in our previous study [1], leading to a faster degradation rate and possible premature failure of the implant.To further study the origin and detailed mechanism of the localized corrosion behavior of ZX-series Mg alloys in simulated physiological environments, transmission electron microscope (TEM) characterizations were performed on a ZX21 (Mg-2.15 wt%Zn-0.97 wt%Ca) Mg alloy before and after corrosion in a Hanks’ balanced salt solution (HBSS) at 37°C. Two second phases, Ca2Mg6Zn3 and Mg2Ca, were found adjacent to each other in the cast ZX21 alloy. The potential difference between the two second phases leads to microgalvanic corrosion and the preferential dissolution of the lower-potential Mg2Ca, initiating localized corrosion on the alloy surface. The localized corrosion propagates a few micrometers deep in the alloy and underneath the surface corrosion film. By selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS) analysis in TEM, the corrosion products in the propagating localized corrosion regions are primarily composed of Mg(OH)2, which is different from the surface corrosion film (Mg(OH)2 + CaHPO4·2H2O) formed on the alloy surface [1]. Furthermore, the presence of Cl signal in the localized corrosion regions indicates that the Cl- ions in HBSS promote the propagation of localized corrosion.[1] P.W. Chu et al., Corrosion Behavior and Microstructure of the Surface Corrosion Film of Biodegradable WE43 and ZX21 Mg Alloys in Hanks’ Balanced Salt Solution, Materials Chemistry and Physics, vol. 312, pp. 128609-128620, 2024.

Growth of High-Quality Non-Polar Materials through Graphene via Anchor Point Nucleation

The application of 2D-assisted epitaxy in the growth of freestanding membranes, hybrid 2D/3D heterostructures, and direct integration of highly mismatched materials has sparked significant interest in fields such as electronics, optoelectronics, and quantum devices. This method has been utilized for the growth of variety of materials, including III-N and III-V semiconductor compounds, various oxide compounds, perovskites, metals, and 2D materials, demonstrating its tremendous potential. However, one of its major challenges remains the growth of non-polar materials like Ge. This is mainly due to the minimal interaction between non-polar materials and 2D interface or underlying bulk substrate. This makes the nucleation and crystal orientation of epilayers very difficult, resulting in polycrystalline structures.In this study, we unravel the key mechanisms governing the nucleation and growth of 3D non-polar materials on suspended single-layer graphene (SLG) from real-time observations of the growth by using in-situ Transmission electron microscopy (TEM)[1]. This powerful technique provides a unique opportunity to observe new and yet unexplored phenomena, which are not accessible to the standard ex-situ characterizations. Through direct observations, remote interactions are elucidated between Ge crystals through the graphene layer in double heterostructures of Ge/graphene/Ge. Based on these findings, we implemented a novel approach for growth of non-polar materials by 2D-assisted epitaxy, called “anchor point nucleation”[2]. This method involves the engineering of the SLG substrate, by introducing defects that act as preferential nucleation sited for the epitaxial growth and aid orienting the epilayer by the underlying substrate. Figure 1 illustrates this approach.The engineering of the SLG was achieved through plasma treatment, and the effects of the treatment duration were analyzed by using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Experimental data confirmed the introduction of defects after the treatment, leading to an increase in nucleation sites shown by the increasing number of Ge nuclei on the treated SLG. These observations corroborate the pivotal role of induced defects in the nucleation process, enhancing surface energy and the reactivity of graphene. The high quality of the resulting epitaxial layers is demonstrated through TEM and electron backscatter diffraction (EBSD) characterizations. These findings mark the first demonstration of anchor point nucleation enabling high-quality growth of non-polar semiconductors through 2D-assisted epitaxy.[1] T.M. Diallo et al., Small (2022), 18, 2101890. (https://doi.org/10.1002/smll.202101890)[2] T.M. Diallo, T. Hanuš et al., Small (2023), 20, 2306038 (https://doi.org/10.1002/smll.202306038) Figure 1

Direct Mechanical and Electrochemical Analysis of Dendrites in Solid-State Electrolytes

Although solid-state batteries with metal anodes promise to enable safer, higher energy density batteries, metal protrusions (dendrites) short-circuit the cell when charging faster than a critical current density.1,2It is generally believed that dendrites grow when the strain energy available for crack extension (the strain energy release rate, ) exceeds that required for fracture of the solid-electrolyte..2-4 We test this hypothesis using operando birefringence microscopy5 to directly observe dendrite-induced stresses. The strain energy release rate is determined by fitting the experimentally measured stress distribution to that which is expected in the vicinity of an internally loaded crack (detailed in Fig. 1).6 These operando experiments, combined with cryogenic scanning transmission electron microscopy (STEM) characterization of the dendrite tip, enable studies of electrochemical and mechanical phenomena underlying dendrite growth in ceramic electrolytes. All experiments were conducted on the most electrochemically stable Li-ion conducting solid electrolyte (tantalum-doped lithium lanthanum zirconium oxide).

Monometallic, Bimetallic, and Trimetallic Oxyphosphides for OER Catalysis in Alkaline Electrolyte

The development of efficient and durable catalysts for the kinetically sluggish oxygen evolution reaction (OER) is paramount for advancing various electrochemical processes including water splitting, CO2 electroreduction, and metal air batteries. In this presentation, the synthesis, characterization, and electrochemical evaluation of monometallic, bimetallic, and trimetallic transition metal OER catalysts will be discussed. We employed a colloidal synthesis approach to fabricate mesoporous oxyphosphide catalysts with varying compositions. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization revealed the formation of a distinct core@shell structure comprising a zero-valent metallic core enveloped by a porous oxygen-rich shell. An OER potential of <1.5 V versus RHE at 10 mA cm-2 and a low Tafel slope of 32 mV decade-1 were measured, surpassing other catalyst configurations including commercial platinum-group-metal-free (PGM-free) catalysts in alkaline media. Furthermore, excellent OER durability at 10 mA cm-2 was demonstrated, with a potential increase of <0.5 mV/h after 100 hours of testing. These findings underscore the potential of TM oxyphosphide catalysts as promising candidates for efficient and durable OER electrocatalysts, paving the way for sustainable energy conversion and storage technologies.AcknowledgmentsThis work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). Argonne is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, under Contract DE-AC-02-06CH11357. Khalafallah D, Farghaly AA, Ouyang C, Huang W, Hong Z. Atomically dispersed Pt single sites and nanoengineered structural defects enable a high electrocatalytic activity and durability for hydrogen evolution reaction and overall urea electrolysis. Journal of Power Sources. 2023, 558, 232563.Onajah S, Sarkar R, Islam MS, Lalley M, Khan K, Demir M, Abdelhamid HN, Farghaly AA. Silica‐Derived Nanostructured Electrode Materials for ORR, OER, HER, CO2RR Electrocatalysis, and Energy Storage Applications: A Review. The Chemical Record. 2024, e202300234.Sarkar R, Farghaly AA, Arachchige IU. Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation. Chemistry of Materials. 2022, 34(13), 5874-87.

Structural Regulation and Advanced Transmission Electron Microscopy Characterization of the Oxygen Reduction Reaction Electrocatalysts

Fuel cells (FCs) are regarded as the most promising green energy conversion technology in the 21st century because of their advantages. However, the industrialization process of FCs is restricted by several key problems, one of which is the cathode catalyst. The Oxygen Reduction Reaction (ORR) of FCs is a complex process involving 4 electrons, which has sluggish kinetics and high over-potential. Therefore, it is usually necessary to use a large number of precious metal platinum (Pt) catalysts to improve the reaction efficiency, but the characteristics of small reserves of Pt, high price, and easy to be poisoned and deactivated increase the operating cost of the whole system. It is imperative to develop substitutes for non-Pt-based ORR catalysts and reveal their structure-activity relationship with advanced characterization techniques.There are two ways to solve this problem: one is to improve the utilization rate of platinum-based catalyst, the other is to develop non-platinum-based catalysts. In terms of improving the utilization rate of Pt, our research group mainly constructed new Pt-based ordered intermetallic compound catalytic materials, and improved the surface structure, alloying degree and electronic structure of Pt-based catalysts by changing the atomic types, proportions and post-treatment temperatures of Pt and transition metals, so as to regulate their electrocatalytic properties. On the other hand, the morphology control of ordered intermetallic compounds has always been a major challenge in this field, and we have made a preliminary attempt in the morphology control. At the same time, with the help of modern characterization techniques, it is of great significance to study the changes of structure and components during the service of Pd-based catalysts, and to understand their failure behavior and performance attenuation mechanism for the subsequent optimization and commercialization of Pd-based catalysts. Among them, visualization technology based on transmission electron microscopy (TEM) has become a research hotspot because it can directly observe the failure process of catalysts in service.

Hollow-structured Zn-doped CeO2 mesoporous spheres boost enhanced antioxidant activity and synergistic bactericidal effect

The increasing prevalence of antibiotic-resistant bacteria is regarded as one of the worst threats to the environment and global health, and antimicrobial nanomaterials have been increasingly explored to provide solutions for antimicrobial resistance problems. In this paper, mesostructured Zn-doped CeO2 hollow spheres (ZDCHS) with various Zn/Ce ratios were successfully prepared by a conventional one-pot hydrothermal synthesis method. The ingenious incorporation of Zn playing a vital role in the fabrication of hollow structure of ZDCHS with high specific surface area, and detailed transmission electron microscopy (TEM) characterization confirmed the homogeneous distribution of Zn element across the ZDCHS. The X-ray photoelectron spectroscopy (XPS) and Raman results indicated that a higher concentration of oxygen vacancies was obtained on the ZDCHS compared to the undoped CeO2 counterparts. In addition, the in vitro antioxidant properties evaluated toward scavenging DPPH radicals, hydroxyl radicals and superoxide radicals further revealed the enhanced antioxidant activity of ZDCHS derived from the doping with Zn ions. Furthermore, the bacteriostatic assay against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria showed that the ZDCHS possessed synergistically improved bacteriostatic performance and were more susceptible to S. aureus with a maximal antimicrobial ratio of 99.5 %, which is higher than that of the undoped CeO2 samples (80.7 %). These results represent a new paradigm to the design of novel hollow-structured materials, highlighting the doping of Zn ions in the lattice structure of CeO2 provides a feasible means for the preparation of effective antioxidants and antimicrobial agents.

Trastuzumab-functionalized SK-BR-3 cell membrane-wrapped mesoporous silica nanoparticles loaded with pyrotinib for the targeted therapy of HER-2-positive breast cancer

In this study, the trastuzumab-functionalized SK-BR-3 cell membrane-wrapped mesoporous silica nanoparticles loaded with pyrotinib (Tra-CM-MSN-PYR) were prepared for targeted therapy of HER2-positive breast cancer. Transmission electron microscopy (TEM) characterization showed that MSN had a spherical morphology with mesoporous channels and that the structure of Tra-CM-MSN was a cell membrane (CM) layer successfully coated on the surface of MSN. A cellular uptake assay demonstrated that FITC-labeled Tra-CM-MSN were taken up by SK-BR-3 breast cancer cells, which illustrated that Tra-CM-MSN had good targeting ability compared with CM-MSN and MSN. In vivo imaging experiments demonstrated significant accumulation of FITC-labeled Tra-CM-MSN in tumor tissues, further proving that Tra-CM-MSN have superior targeting properties. Cell apoptosis experiments suggested that Tra-CM-MSN-PYR significantly inhibited the proliferation of SK-BR-3 breast cancer cells. The results of in vivo animal experiments also showed that Tra-CM-MSN-PYR significantly inhibited tumor growth. These results indicate that Tra-CM-MSN-PYR has potential application as a targeted therapy for HER2-positive breast cancer in the future.

Mitigating coherent loss in superconducting circuits using molecular self-assembled monolayers

In planar superconducting circuits, decoherence due to materials imperfections, especially two-level-system (TLS) defects at different interfaces, is a primary hurdle for advancing quantum computing and sensing applications. Traditional methods for mitigating TLS loss, such as etching oxide layers at metal and substrate interfaces, have proven to be inadequate due to the persistent challenge of oxide regrowth. In this work, we introduce a novel approach that employs molecular self-assembled monolayers (SAMs) to chemically bind at different interfaces of superconducting circuits. This technique is specifically tested here on coplanar waveguide (CPW) resonators, in which this method not only impedes oxide regrowth after surface etching but can also tailors the dielectric properties at different resonators interfaces. The deployment of SAMs results in a consistent improvement in the measured quality factors across multiple resonators, surpassing those with only oxide-etched resonators. The efficiency of our approach is supported by microwave measurements of multiple devices conducted at millikelvin temperatures and correlated with detailed X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) characterizations of SAM-passivated resonators. The compatibility of SAMs materials with the established fabrication techniques offers a promising route to improve the performance of superconducting quantum devices.

N, S-Codoped Carbon Quantum Dots with High Inhibition Efficiency: Implications for Corrosion Mitigation of Carbon Steel in Acidic Environments.

The environmental friendliness, economic feasibility, and high efficiency of carbon quantum dots (CQDs) render them as highly promising candidates for corrosion inhibitors. The present study proposed the fabrication of nitrogen- and sulfur-codoped CQDs via an one-step hydrothermal method using l-cysteine and 4-aminosalicylic acid as precursors. The structure, particle size, and surface ligands of the prepared CQDs were determined through spectroscopy and transmission electron microscopy characterization. Subsequently, the inhibition performance of the CQDs on carbon steel in a 0.5 M sulfuric acid solution was evaluated through weight loss measurement, electrochemical methods, and surface analysis. The CQDs exhibited remarkable inhibition efficiencies of 97.9% at 293 K and 98.9% at 313 K, with a concentration of 150 ppm. In addition, the obtained CQDs demonstrated a combined physisorption and chemisorption adsorption behavior, which complied with the Langmuir adsorption isotherm. These findings provide insight into the inhibition mechanism and highlight the potential of codoped CQDs for corrosion mitigation applications in acidic environments.

Underlying mechanisms for the effect of Nb micro-alloying on the elemental distribution and precipitation behavior in the X70 weld metal

Niobium (Nb) is a widely recognized micro-alloying element due to its low cost and substantial impact on steel properties. While the effect of Nb in processed steels has been well investigated, studies on its elemental distribution and precipitation behavior in weld metal remain scarce. This study focuses on the weld metal of specially designed Nb-rich X70 pipeline steel by scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDS) characterization, complemented with thermodynamic and kinetics modeling analysis. In the majority of the weld, Nb was essentially uniformly distributed. This suggests that Nb primarily exists in the solid solution form in the weld metal, which is also supported by precipitation kinetics modeling results. This is primarily due to the short thermal history associated with the welding process, which leads to insufficient time for the uniform precipitation of Nb. Two instances of Nb precipitates were observed at the weld centerline and reinforcement region. The low partition coefficient of Nb results in an elevated local concentration along the weld centerline. However, precipitation kinetics calculations suggest that this enhancement alone is not adequate to induce precipitate formation. The occurrence of MnS and the prior formation of Ti precipitates may provide heterogeneous nucleation sites for Nb, facilitating the nucleation of Nb precipitates in the weld centerline and reinforcement region.

Microstructure and wear resistance of laser cladding AlCoCrFeNiSiB high-entropy alloy with high boron content

In this study, a wear-resistant coating of high boron content Al1.5CoCr2Fe1.5NiSi0.5B2 high-entropy alloy (HEA) was prepared on X65 pipeline steel by laser cladding. The coating underwent microhardness testing, wear performance testing, and analyses including scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The results revealed a dual-phase structure of body-centered cube (BCC) and face-entered cube (FCC) in the coating, with the presence of Fe1.1Cr0.9B0.9 phase distributed within the BCC. Utilizing high-resolution transmission electron microscopy (HRTEM) characterization, irregular atomic arrangement regions within the BCC structure were observed. Through the calculation of the α2 and ε parameters of the coating, the degree of lattice distortion in the BCC and FCC phases was quantitatively described. The results suggested that the addition of a substantial amount of boron could strengthen the lattice distortion effect, leading to improved hardness and wear resistance of the coating. The average microhardness of the coating was 912 HV, about 5 times higher than X65 substrate, improved by more than 10 % compared with other AlCoCrFeNi-based high-entropy alloys and B-containing high-entropy alloys. The wear rate was 4.78 × 10−6 mm/N·m, wear performance is nearly 10 times higher than other AlCoCrFeNi HEA without boron, 2 times higher than HEA with born. The wear mechanism of the coating was identified as abrasive and oxidative wear.