Although a high-quality homoepitaxial layer of 4H‑silicon carbide (4H-SiC) can be obtained on a 4° off-axis substrate using chemical vapor deposition, the reduction of defects is still a focus of ...research. In this study, several kinds of surface defects in the 4H-SiC homoepitaxial layer are systemically investigated, including triangles, carrots, surface pits, basal plane dislocations, and step bunching. The morphologies and structures of surface defects are further discussed via optical microscopy and potassium hydroxide-based defect selective etching analysis. Through research and analysis, we found that the origin of surface defects in the 4H-SiC homoepitaxial layer can be attributed to two aspects: the propagation of substrate defects, such as scratches, dislocation, and inclusion, and improper process parameters during epitaxial growth, such as in-situ etch, C/Si ratio, and growth temperature. It is believed that the surface defects in the 4H-SiC homoepitaxial layer can be significantly decreased by precisely controlling the chemistry on the deposition surface during the growth process.
•The growth process of the 4H-SiC homoepitaxial layer is introduced.•Surface defects in the 4H-SiC homoepitaxial layer are discussed, including the origin, mechanism, and characterization.•The controlling methods of surface defects in the 4H-SiC growth process are detailed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Reactive oxygen species (ROS) are important oxidizing species that play arious roles within ecosystems, inducing oxidative stress and causing damage to organisms while also effectively scavenging ...pollutants from the natural environment. Therefore, it is highly important to monitor the concentration or relative level of ROS in the environment. To date, various ROS detection methods have been reported, among which the chemiluminescence (CL) method has attracted much attention because of its unique advantages such as high sensitivity, instantaneity and simplicity of operation. This review extensively summarizes the CL methods for ROS detection developed in the past five years, comparing different CL systems and evaluating their current advances and limitations. Furthermore, the potential environmental applications of ROS are also discussed.
•Reactive oxygen species (ROS) as important oxidizing species have received a great deal of interest.•Chemiluminescence methods for the detection and quantification of various ROS were summarized.•Different CL methods were compared and summarized, and their status and limitations were evaluated in detail.•ROS generation and their environmental application were referred.•The challenges and prospects of CL methods for the detection of ROS and their environmental applications were also addressed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•The sorption of four perfluoroalkyl acids (PFAAs) on three minerals was studied.•Sorption of PFOS was greatly affected by solution chemistry while others were not.•PFOS may form outer-sphere ...complexation and hydrogen-bonds at the mineral surface.•Perfluorohexane sulfonate (PFHxS) might complex with the inner OH of minerals.
The sorption of four perfluoroalkyl acids (PFAAs) perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA) on three typical minerals montmorillonite (MM), kaolinite (KL) and hematite (HM) was studied. The sorption of PFOS and PFHxS was much stronger than PFOA and PFHxA. The sorption of each PFAA on the minerals followed an order of HM>KL>MM, even though MM was positively while KL and HM were negatively charged, implying that the sorption is driven by some other interactions besides electrostatic attraction. The sorption decreased with an increase in pH and a decrease in ionic strength of the solution, and their impacts on PFOS were much stronger than other three PFAAs. Surface complexing and hydrogen-bonding could make great contributions to the sorption of PFOS on the minerals. The results are important for understanding the transport and fate of PFAAs in sediment and ground water.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Despite many studies on the toxicity of nanoplastic particles (NPPs) to aquatic invertebrates, the effects of ecological constituents such as humic substances (HSs) are often neglected. In our study, ...Daphnia magna was used to evaluate the effects of three HSs, natural organic matter (NOM), fulvic acid (FA), and humic acid (HA), on NPP toxicity and corona formation. Acute toxicities of NPPs were reduced by all HSs at environmentally relevant concentrations. NPPs elicited the upregulation of all genes related to detoxification, oxidative stress, and endocrine activity after 7 days of exposure. The presence of NOM or HA resulted in the mitigation of gene expression, whereas significantly higher upregulation of all of the genes was observed with FA. The presence of FA led to increased protein adsorption on NPPs in D. magna culture medium (eco-corona, EC) and homogenates (protein corona, PC), while there was less adsorption in the presence of HA. The highly abundant proteins identified in EC are involved in immune defense, cell maintenance, and antipredator response, while those in PC are responsible for lipid transport, antioxidant effects, and estrogen mediation. Our findings revealed the key influence of HSs on the toxicity of NPPs and provide an analytical and conceptual foundation for future study.
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IJS, KILJ, NUK, PNG, UL, UM
Bone marrow-derived mesenchymal stem cells (BMSCs) exhibit multi-lineage differentiation potential and robust proliferative capacity. The late stage of differentiation signifies the functional ...maturation and characterization of specific cell lineages, which is crucial for studying lineage-specific differentiation mechanisms. However, the molecular processes governing late-stage BMSC differentiation remain poorly understood. This study aimed to elucidate the key biological processes involved in late-stage BMSC differentiation. Publicly available transcriptomic data from human BMSCs were analyzed after approximately 14 days of osteogenic, adipogenic, and chondrogenic differentiation. Thirty-one differentially expressed genes (DEGs) associated with differentiation were identified. Pathway enrichment analysis indicated that the DEGs were involved in extracellular matrix (ECM)-receptor interactions, focal adhesion, and glycolipid biosynthesis, a ganglion series process. Subsequently, the target genes were validated using publicly available single-cell RNA-seq data from mouse BMSCs. Lamc1 exhibited predominant distribution in adipocytes and osteoblasts, primarily during the G2/M phase. Tln2 and Hexb were expressed in chondroblasts, osteoblasts, and adipocytes, while St3gal5 was abundantly distributed in stem cells. Cell communication analysis identified two receptors that interact with LAMCI. q-PCR results confirmed the upregulation of Lamc1, Tln2, Hexb, and St3gal5 during osteogenic differentiation and their downregulation during adipogenic differentiation. Knockdown of Lamc1 inhibited adipogenic and osteogenic differentiation. In conclusion, this study identified four genes, Lamc1, Tln2, Hexb, and St3gal5, that may play important roles in the late-stage differentiation of BMSCs. It elucidated their interactions and the pathways they influence, providing a foundation for further research on BMSC differentiation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The selectivity of molecular oxygen activation on the exfoliated graphitic carbon nitride (g-C3N4) and its influence on the photocatalytic phenol degradation process were demonstrated. Compared with ...bulk g-C3N4, the exfoliated nanosheet yielded a 3-fold enhancement in photocatalytic phenol degradation. ROS trapping experiments demonstrated that although the direct hole oxidation was mainly responsible for phenol photodegradation on both g-C3N4 catalysts, molecular oxygen activation processes on their surface greatly influenced the whole phenol degradation efficiency. Reactive oxygen species and Raman spectroscopy measurements revealed that oxygen was preferentially reduced to ·O2 – by one-electron transfer on bulk g-C3N4, while on g-C3N4 nanosheet the production of H2O2 via a two-electron transfer process was favored due to the rapid formation of surface-stabilized 1,4-endoperoxide. The latter process not only promotes the separation of photogenerated electron–hole pairs but also greatly facilitates reactive oxygen species formation and subsequently enhances phenol degradation.
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IJS, KILJ, NUK, PNG, UL, UM
We report a highly efficient photocatalyst comprised of Cu7S4@Pd heteronanostructures with plasmonic absorption in the near-infrared (NIR)-range. Our results indicated that the strong NIR plasmonic ...absorption of Cu7S4@Pd facilitated hot carrier transfer from Cu7S4 to Pd, which subsequently promoted the catalytic reactions on Pd metallic surface. We confirmed such enhancement mechanism could effectively boost the sunlight utilization in a wide range of photocatalytic reactions, including the Suzuki coupling reaction, hydrogenation of nitrobenzene, and oxidation of benzyl alcohol. Even under irradiation at 1500 nm with low power density (0.45 W/cm2), these heteronanostructures demonstrated excellent catalytic activities. Under solar illumination with power density as low as 40 mW/cm2, nearly 80–100% of conversion was achieved within 2 h for all three types of organic reactions. Furthermore, recycling experiments showed the Cu7S4@Pd were stable and could retain their structures and high activity after five cycles. The reported synthetic protocol can be easily extended to other Cu7S4@M (M = Pt, Ag, Au) catalysts, offering a new solution to design and fabricate highly effective photocatalysts with broad material choices for efficient conversion of solar energy to chemical energy in an environmentally friendly manner.
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A graphene-based two-dimensional (2D) nanoplatform provides new opportunities for fabricating 2D heterojunction interfaces to fortify charge transfer in semiconductor assemblies. In this report, TiO2 ...nanosheet/graphene composite based 2D–2D heterojunctions were fabricated by a solvothermal process. Microscopic and spectroscopic characterization revealed a homogeneous sheetlike morphology with intimate interfacial contact between the TiO2 nanosheet and graphene due to chemical interactions. Compared with 0D–2D Degussa P25 (TiO2)/graphene and 1D–2D TiO2 nanotube/graphene composites, the 2D–2D TiO2 nanosheet/graphene hybrid demonstrated higher photocatalytic activity toward the degradation of rhodamine B and 2,4-dichlorophenol under UV irradiation. Radical trapping and ESR experiments revealed the enhanced generation of ·OH and O2 •– in the 2D–2D heterojunction system. By analyzing TiO2 excited state deactivation lifetime, the interfacial electron transfer rates determined for 0D–2D, 1D–2D, and 2D–2D TiO2/graphene composites were 1.15 × 108 s–1, 3.47 × 108 s–1, and 1.06 × 109 s–1, respectively. It was therefore proposed that the fast charge separation in the TiO2 nanosheet/graphene photocatalyst promoted the generation of reactive oxygen species and enhanced the photodegradation reactions. The results underscore the key role of nanomaterial dimensionality in interfacial charge transfer processes.
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IJS, KILJ, NUK, PNG, UL, UM
Chemiluminescence immunoassay (CLIA) offers several potential advantages and has applications in clinical chemistry, bioanalysis and environmental analysis. This review covers recent developments and ...applications of CLIA in immunorecognition, CL markers and related techniques, and solid-phase materials. We describe automation, integration and miniaturization of CLIA. We evaluate different CLIA systems and give some pointers as to the likely directions of future developments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An efficient photocatalytic process involves two closely related steps: charge separation and the subsequent surface redox reaction. Herein, a ternary hybrid photocatalytic system was designed and ...fabricated by anchoring Cu(II) clusters onto a TiO2/reduced graphene oxide (RGO) composite. Microscopic and spectroscopic characterization revealed that both TiO2 nanoparticles and Cu(II) clusters were highly dispersed on a graphene sheet with intimate interfacial contact. Compared with pristine TiO2, the TiO2/RGO/Cu(II) composite yielded an almost 3-fold enhancement in the photodegradation rate toward phenol degradation under UV irradiation. Electron spin resonance (ESR) spectra and electrochemical measurements demonstrated that the improved photocatalytic activity of this ternary system benefitted from the synergetic effect between RGO and Cu(II), which facilitates the interfacial charge transfer and simultaneously achieves in situ generation of H2O2 via two-electron reduction of O2. These results highlight the importance to harmonize the charge separation and surface reaction process in achieving high photocatalytic efficiency for practical application.
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IJS, KILJ, NUK, PNG, UL, UM
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