We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy group at z = 4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El Gordo) at z = 0.87, associated with a 1.2 mm source that is at a 2.07 ± 0.88 kpc projected distance from one of the group galaxies. Three images of the whole system appear in the image plane. The 1.2 mm source has been detected within the Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey (ALCS). As this ALMA source is undetected at wavelengths λ < 2 μm, its redshift cannot be independently determined, however, the three lensing components indicate that it belongs to the same galaxy group at z = 4.32. The four members of the MUSE galaxy group have low to intermediate stellar masses (∼10 7 -10 10 M e ) and star formation rates (SFRs) of 0.4-24 M e yr −1 , resulting in high specific SFRs (sSFRs) for two of them, which suggest that these galaxies are growing fast (with stellar mass doubling times of only ∼2 × 10 7 yr). This high incidence of starburst galaxies is likely a consequence of interactions within the galaxy group, which is compact and has high velocity dispersion. Based on the magnification-corrected sub-/ millimeter continuum flux density and estimated stellar mass, we infer that the ALMA source is classified as an ordinary ultra-luminous infrared galaxy (with associated dust-obscured SFR ∼ 200-300 M e yr −1 ) and lies on the star formation main sequence. This reported case of an ALMA/MUSE group association suggests that some presumably isolated ALMA sources are in fact signposts of richer star-forming environments at high redshifts.

In recent years, carbon nanodots (CNDs)-based hybrid nanomaterials with enzyme-like properties have received considerable attention because of the simplicity of their preparation, storage, and separation, as well as cost-effectiveness compared with natural enzymes. Here, Fe3O4/CNDs hybrid nanoparticles (NPs) are prepared via a hydrothermal method, and they possess excellent peroxidase-like catalytic activity. During the synthesis, the formation and surface state of Fe3O4 NPs were extremely affected by solutions of CNDs, which served as solvents. Fe3O4/CNDs hybrid NPs with abundant hydroxyl and carboxyl groups exhibit better catalytic kinetics than natural horseradish peroxidase (HRP) to produce a rapid chromogenic reaction. Such characteristics from Fe3O4/CNDs hybrid NPs led us to develop a colorimetric method for rapid and selective determination of glutathione with the detection limit of 0.058 μM. Our approach offers a simple and novel method to prepare Fe3O4/CNDs hybrid NPs with modified CNDs, and their applications may be extended to biosensors, medical diagnostics, and environmental monitoring.

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http://weballergen.bii.a-star.edu.sg/

Gold nanoclusters (AuNCs) are one of metal nanoclusters, which play a pivotal role in the recent advances in the research of fluorescent probes for their fluorescence effect. They are favored by most researchers due to their strong stability in fluorescence and adjustability in fluorescence wavelength when compared to traditional organic fluorescent dyes. In this review, we introduce various synthesis strategies of gold-nanocluster-based fluorescent probes and summarize their application for environmental analysis and biological sensing. The use of gold-nanocluster-based fluorescent probes for the analysis of heavy metals and inorganic and organic pollutants is covered in the environmental analysis while biological labeling, imaging, and detection are presented in biological sensing.