the-state-of-the-art ORR catalysts but their uses are largely restricted by the prohibitive cost and limited activity/stability. [3][4][5][6][7] In this regard, the development of non-Pt group metal (non-PGM) catalysts derived from earth-abundant elements for ORR is the fundamental solution for the widespread applications of PEMFCs. [8][9][10] Among various non-PGM ORR catalysts developed in last decade, transition metalnitrogen-carbon (M-N-C) catalysts with M-N x coordination active sites embedded in the basal planes of carbon matrixes were the most promising ones due to their decent activity in both acidic and alkaline media and ease of scale-up production. [11][12][13][14][15] The ORR performance of M-N-C electrocatalysts in alkaline electrolyte has been well demonstrated notwithstanding, [9,[16][17][18][19][20] their performance in acidic environment is still deficient and often degrades rapidly due to the etching of metal species and/or decomposition of active sites. [21,22] Generally, the M-N-C catalysts are prepared via high-temperature (T > 800 °C) pyrolysis process of transition metal (e.g., Fe, Co, Ni), nitrogen, and carbon precursors, during which the metal atoms are very easy to agglomerate into large particles. The aggregated metal and metal oxide/carbide particles will hinder the accessibility of M-N x /C active sites and lower the utilization of M atoms seriously, thus compromising their ORR activity. Furthermore, metal aggregates will be easily etched away in acid, leading to The development of high-performance oxygen reduction reaction (ORR) catalysts derived from non-Pt group metals (non-PGMs) is urgent for the wide applications of proton exchange membrane fuel cells (PEMFCs). In this work, a facile and cost-efficient supramolecular route is developed for making non-PGM ORR catalyst with atomically dispersed Fe-N x /C sites through pyrolyzing the metal-organic polymer coordinative hydrogel formed between Fe 3+ and α-L-guluronate blocks of sodium alginate (SA). High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption spectroscopy (XAS) verify that Fe atoms achieve atomic-level dispersion on the obtained SA-Fe-N nanosheets and a possible fourfold coordination with N atoms. The best-performing SA-Fe-N catalyst exhibits excellentORR activity with half-wave potential (E 1/2 ) of 0.812 and 0.910 V versus the reversible hydrogen electrode (RHE) in 0.5 m H 2 SO 4 and 0.1 m KOH, respectively, along with respectable durability. Such performance surpasses that of most reported non-PGM ORR catalysts. Density functional theory calculations suggest that the relieved passivation effect of OH* on Fe-N 4 /C structure leads to its superior ORR activity to Pt/C in alkaline solution. The work demonstrates a novel strategy for developing high-performance non-PGM ORR electrocatalysts with atomically dispersed and stable M-N x coordination sites in both acidic and alkaline media.

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Nitrogen-rich quantum dots (N-dots) were serendipitously synthesized in methanol or aqueous solution at a reaction temperature as low as 50 °C. These N-dots have a small size (less than 10 nm) and contain a high percentage of the element nitrogen, and are thus a new member of quantum-dot family. These N-dots show unique and distinct photoluminescence properties with an increasing percentage of nitrogen compared to the neighboring carbon dots. The photoluminescence behavior was adjusted from blue to green simply through variation of the reaction temperature. Furthermore, the detailed mechanism of N-dot formation was also proposed with the trapped intermediate. These N-dots have also shown promising applications as fluorescent ink and biocompatible staining in C. elegans.

Nitrogen‐rich quantum dots (N‐dots) were serendipitously synthesized in methanol or aqueous solution at a reaction temperature as low as 50 °C. These N‐dots have a small size (less than 10 nm) and contain a high percentage of the element nitrogen, and are thus a new member of quantum‐dot family. These N‐dots show unique and distinct photoluminescence properties with an increasing percentage of nitrogen compared to the neighboring carbon dots. The photoluminescence behavior was adjusted from blue to green simply through variation of the reaction temperature. Furthermore, the detailed mechanism of N‐dot formation was also proposed with the trapped intermediate. These N‐dots have also shown promising applications as fluorescent ink and biocompatible staining in C. elegans.

Surgical masks (SMs) are the most commonly used personal protective equipment during the COVID-19 pandemic. Due to their vast use and inappropriate disposal worldwide, SMs could potentially cause serious microplastic (MP) pollution in coastal marine environments. This study aimed to investigate the kinetic release of MPs from polypropylene SMs (PP-SMs) in seawater and to evaluate the chronic toxicity of the released MPs to the marine copepod Tigriopus japonicus. On the basis of the results of our kinetic study and available relevant data, we estimated that SMs discarded throughout the year 2020 would lead to >1370 trillion MPs entering the coastal marine environment globally, with a release rate of 396 billion MPs per day. Our results also demonstrated that the copepods ingested the MPs released from PP-SMs, causing a significant decline in their fecundity. The results clearly suggest the MPs released from improperly discarded SMs could have a long-term domino effect on coastal marine ecosystems. To minimize the risk of this emerging threat, better environmental management, policy, and law enforcement for ensuring the proper disposal of SMs are deemed to be necessary.

Precise detection and effective treatment are crucial to prolong cancer patients' lives. Surface-enhanced Raman scattering (SERS) imaging coupled with photothermal therapy has been considered a precise and effective strategy for cancer theranostics. Nevertheless, Raman reporters employed in the literature usually possessed multiple shift peaks in the fingerprint region, which are overlapped with background signals from endogenous biological molecules. Herein, we fabricated a new kind of bioorthogonal Raman reporter and aptamer functionalized SERS nanotags. The SERS nanotags demonstrated a strong Raman signal at 2205 cm −1 in the biologically Raman-silent region and recognized MCF-7 breast cancer cells for Raman imaging with high specificity. Laser irradiation induced serious toxicity of MCF-7 cells due to the excellent photothermal capability of the SERS nanotags. After intravenous administration of the SERS nanotags, tumor Raman spectral detection and mapping in living mice were successfully achieved. Further in vivo antitumor experiments manifested that the aptamer-modified SERS nanotags significantly restrained tumor growth after laser irradiation with 99% inhibition rate and good biocompatibility. These results clearly revealed that the SERS nanotags could serve as a novel and precise theranostic platform for in vivo cancer diagnosis and photothermal therapy.P recise diagnosis and effective treatment are crucial to enhance cancer patients' survival rates and quality of life. Nevertheless, conventional detection approaches of cancer including biopsy, ultrasonography, X-ray computed tomography (CT), and magnetic resonance imaging (MRI) suffer from inherent drawbacks such as low sensitivity and specificity which restrict their clinical applications in early diagnosis. 1−3 Another emerging imaging technique known as positron emission tomography (PET) combined with CT or MRI has demonstrated higher sensitivity and accuracy than traditional imaging methods but requires high cost and radioactive materials with potential health hazards. 4,5 In recent years, surface-enhanced Raman scattering (SERS) imaging has attracted tremendous attention in biomedical fields, owing to its ultrahigh sensitivity (up to 10 −15 M), high signal-tobackground ratio, specific fingerprint signature, photostability, and excellent multiplex capability. 6−12 These advantages give SERS imaging great promise for accurate cancer detection. 13−17 In 2008, Nie's group first employed SERS nanotags for cancer targeting and spectroscopic detection in xenograft tumor models. 18 Gambhir et al. first applied spectrally unique SERS nanotags for in vivo deep-tissue multiplex imaging. 19,20 Subsequently, they designed a novel nanotag with triple modality imaging capability and utilized SERS imaging to distinguish the brain tumor margin in surgical resection. 21 Recently, they presented a small-animal Raman imaging system for rapid, wide-area, high-spatial resolution and spectroscopic imaging. 22 Kircher et al. has demonstrated that SERS nanotagguided sur...

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There is now compelling evidence that selective stimulation of Aδ nociceptors eliciting first pain evokes robust responses in the primary somatosensory cortex (S1). In contrast, whether the C-fiber nociceptive input eliciting second pain has an organized projection to S1 remains an open question. Here, we recorded the electrocortical responses elicited by nociceptive-specific laser stimulation of the four limbs in 202 humans (both males and females, using EEG) and 12 freely moving rats (all males, using ECoG). Topographical analysis and source modeling revealed in both species, a clear gross somatotopy of the unmyelinated C-fiber input within the S1 contralateral to the stimulated side. In the human EEG, S1 activity could be isolated as an early-latency negative deflection (C-N1 wave peaking at 710–730 ms) after hand stimulation, but not after foot stimulation because of the spatiotemporal overlap with the subsequent large-amplitude supramodal vertex waves (C-N2/P2). In contrast, because of the across-species difference in the representation of the body surface within S1, S1 activity could be isolated in rat ECoG as a C-N1 after both forepaw and hindpaw stimulation. Finally, we observed a functional dissociation between the generators of the somatosensory-specific lateralized waves (C-N1) and those of the supramodal vertex waves (C-N2/P2), indicating that C-fiber unmyelinated input is processed in functionally distinct somatosensory and multimodal cortical areas. These findings demonstrated that C-fiber input conveys information about the spatial location of noxious stimulation across the body surface, a prerequisite for deploying an appropriate defensive motor repertoire.SIGNIFICANCE STATEMENT Unmyelinated C-fibers are the evolutionarily oldest peripheral afferents responding to noxious environmental stimuli. Whether C-fiber input conveys information about the spatial location of the noxious stimulation to the primary somatosensory cortex (S1) remains an open issue. In this study, C-fibers were activated by radiant heat stimuli delivered to different parts of the body in both humans and rodents while electrical brain activity was recorded. In both species, the C-fiber peripheral input projects to different parts of the contralateral S1, coherently with the representation of the body surface within this brain region. These findings demonstrate that C-fiber input conveys information about the spatial location of noxious stimulation across the body surface, a prerequisite for deploying an appropriate defensive motor repertoire.