Uncovering Dynamic Edge-Sites in Atomic Co-N-C Electrocatalyst for Selective Hydrogen Peroxide Production.

Understanding the nature of single-atom catalytic sites and identifying their spectroscopic fingerprints are essential prerequisites for the rational design of target catalysts. Here, we apply correlated in situ X-ray absorption and infrared spectroscopy to probe the edge-site-specific chemistry of Co-N-C electrocatalyst during the oxygen reduction reaction (ORR) operation. The unique edge-hosted architecture affords single-atom Co site remarkable structural flexibility with adapted dynamic oxo adsorption and valence state shuttling between Co(2-δ)+ and Co2+ , in contrast to the rigid in-plane embedded Co1 -Nx counterpart. Theoretical calculations demonstrate that the synergistic interplay of in situ reconstructed Co1 -N2 -oxo with peripheral oxygen groups gives a rise to the near-optimal adsorption of *OOH intermediate and substantially increases the activation barrier for its dissociation, accounting for a robust acidic ORR activity and 2e- selectivity for H2 O2 production.

In-Situ Grafting of Single-Atomic Titanium-Nitrogen Moiety onto Carbon Nanostructures for Efficient Photovoltaic Devices.

Early transition metals offer promising orthogonal reactivity to catalytic processes promoted by late transition metals. Nevertheless, exploiting variable single-atomic configurations as reactive centers is hitherto not well documented owing to their oxophilic nature. Herein we report an in-situ grafting strategy that employs nitrogenated holey carbon nitrides as a scaffold and invokes the reasonably good match of temperature-dependent pyrolysis to stabilize an atomic titanium-nitrogen (Ti1N2OH) moiety onto the hierarchical porous carbon support (Ti1/NC-SAC). The Ti1/NC-SAC as the cathode in dye-sensitized solar cells assembly exhibited superior electrocatalytic activity toward the triiodine reduction reaction, comparable to the conventional Pt cathode. DFT studies theoretically identified that the intrinsic robust triiodine reduction activity is essentially governed by the unique edge-hosted Ti sites, from both aspects, near-optimal adsorption of I intermediate and electron-donating ability. This work sheds light on the rational design of Ti-based SACs and their applications in photovoltaic fields.

Synergistically Enhanced Single-Atom Nickel Catalysis for Alkaline Hydrogen Evolution Reaction.

The feature endowing atomic Ni-N-C electrocatalysts with exceptional intrinsic alkaline hydrogen evolution activity is hitherto not well-documented and remains elusive. To this end, we rationally exploited the hierarchical porous carbon microstructures as scaffolds to construct unique Ni-N2+2-S active sites to boost the sluggish Volmer reaction kinetics. Density functional theory reveals an obvious d-band center (ϵd) upshift of the edge-hosted Ni-N2+2-S sites compared with pristine Ni-N4, which translates to a more stabilized OH adsorption. Moreover, the synergetic dual-site (Ni and S atom) interplay gives rise to a decoupled regulation of the adsorption strength of intermediate species (OHad, Had) and thereby energetic water dissociation kinetics. Bearing these in mind, sodium thiosulfate was deliberately adopted as an additive in the molten salt system for controllable synthesis, considering the simultaneous catalyst morphology and active-site modulation. The target Ni-N2+2-S catalyst delivers a low working overpotential (83 mV@10 mA cm-2) and Tafel slope (100.5 mV dec-1) comparable to those of representative transition metal-based electrodes in alkaline media. The present study provides insights into the metal active-site geometry and promising synergistic effects over single-atom catalysis.

Multi-wavelength coherent random laser in bio-microfibers.

In this paper, pure silk protein was extracted from Bombyx mori silks and fabricated into a new kind of disordered bio-microfiber structure using electrospinning technology. Coherent random lasing emission with low threshold was achieved in the silk fibroin fibers. The random lasing emission wavelength can be tuned in the range of 33 nm by controlling the pump location with different scattering strengths. Therefore, the bio-microfiber random lasers can be a wide spectral light source when the system is doped with a gain or energy transfer medium with a large fluorescence emission band. Application of the random lasers of the bio-microfibers as a low-coherence light source in speckle-free imaging had also been studied.

Detection of Sleep Biosignals Using an Intelligent Mattress Based on Piezoelectric Ceramic Sensors.

Physiological information such as respiratory rate and heart rate in the sleep state can be used to evaluate the health condition of the sleeper. Traditional sleep monitoring systems need body contact and are intrusive, which limits their applicability. Thus, a comfortable sleep biosignals detection system with both high accuracy and low cost is important for health care. In this paper, we design a sleep biosignals detection system based on low-cost piezoelectric ceramic sensors. 18 piezoelectric ceramic sensors are deployed under the mattress to capture the pressure data. The appropriate sensor that captures respiration and heartbeat sensitively is selected by the proposed channel-selection algorithm. Then, we propose a dynamic smoothing algorithm to extract respiratory rate and heart rate using the selected data. The dynamic smoothing can separate heartbeat signals from respiratory signals with low complexity by dynamically choosing the smooth window, and it is suitable for real-time implementation in low-cost embedded systems. For comparison, wavelet analysis and ensemble empirical mode decomposition (EEMD) are performed in a personal computer (PC). Experimental results show that data collected by piezoelectric ceramic sensors can be used for respiratory-rate and heart-rate detection with high accuracy. In addition, the dynamic smoothing can achieve high accuracy close to wavelet analysis and EEMD, while it has much lower complexity.

Ultra-small Mo2N on SBA-15 as a highly efficient promoter of low-loading Pd for catalytic hydrogenation.

Decreasing Pd usage whilst maintaining a superior performance is promising, but remains a challenge in the catalytic field. Herein, we have demonstrated the highly efficient promotion of Mo2N with a reduced amount of Pd for the liquid-phase hydrogenation reaction. The Mo2N (2-3 nm) was uniformly anchored onto mesoporous SBA-15 by using PMo12 as the Mo source. The small size and good dispersion of Mo2N is favourable for allowing their effective contact with post-loading Pd. This good contact is conducive to developing a synergistic catalyst, which was verified by studying the liquid-phase hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) with NaBH4 as the H source. The conversion ability of PNP to PAP on 1 wt% Pd-Mo2N/SBA-15 was vastly superior to 1 wt% Pd/SBA-15 and even better than 20 wt% Pd/SBA-15. The low-Pd, highly efficient catalysis is ascribed to the transfer of the electrons from Mo2N to Pd for the easy activation of H. The synergy can be affected by the type of support used. SBA-15 is superior to SiO2 and the other supports, which could be related to the large surface area and the plentiful number of pores on SBA-15, which is favourable to the dispersion of Pd and Mo2N, and the transfer/diffusion of the reactants. In particular, a highly efficient catalyst can be achieved at an even more reduced Pd loading (0.05 wt%). The current method describes the design of a highly efficient catalyst for the hydrogenation reaction using low amounts of noble metals.

Cloning, expression profiling, and acetylation identification of alpha-tubulin N-acetyltransferase 1 from Bombyx mori.

Alpha-tubulin N-acetyltransferase 1 (ATAT1) is an acetyltransferase specific to α-tubulin and performs important functions in many cellular processes. Bombyx mori is an economic insect and also known as a model lepidoptera insect. In this study, we cloned a B. mori ATAT1 gene (BmATAT1) (Gen Bank accession number: XP_004932777.1). BmATAT1 contained an open reading frame (ORF) of 1,065 bp encoding 355 amino acids (aa). Expression profiling of BmATAT1 protein showed that the expression levels of BmATAT1 at different developmental stages and different tissues in fifth-instar larvae differ. BmATAT1 was highly expressed at the egg stage and in the head of the fifth-instar larvae. Subcellular localization showed that BmATAT1 was distributed in the cytoplasm and nucleus. Furthermore, BmATAT1 may lead to time-dependent induction of cell cycle arrest in the G2/M phase by flow cytometry analysis. Interestingly, using site-specific mutation, immunoprecipitation, and Western blotting, we further found a BmATAT1 acetylated site at K156, suggesting that this acetyltransferase could be regulated by acetylation itself.

Optical amplification of Eu(TTA)3Phen solution-filled hollow optical fiber.

A liquid core optical fiber (LCOF) composed of hollow fiber and a solution of Eu(TTA)(3)Phen (TTA=2-thenoyltrifluoroacetone, Phen=1, 10-phenanthroline) in dimethyl sulfoxide (DMSO) has been fabricated, in which the concentration of Eu(TTA)(3)Phen in DMSO is 0.8 wt.%, the core diameter of the LCOF is 10 µm, and the fiber length is 8.1 cm. By the end pumping with a diode-pumped solid-state laser at 355 nm, a small optical signal at 613 nm was amplified with a gain of 8.2 dB at a pump power of 203 mW. Based on this experimental result, a liquid core optical fiber amplifier can be realized by the LCOF, which has wide potential applications in many optical devices.