Alveoli-Inspired Carbon Cathodes with Interconnected Porous Structure and Asymmetric Coordinated Vanadium Sites for Superior Li-S Batteries.

Accelerating sulfur conversion catalysis to alleviate the shuttle effect has become a novel paradigm for effective Li-S batteries. Although nitrogen-coordinated metal single-atom (M-N4) catalysts have been investigated, further optimizing its utilization rate and catalytic activities is urgently needed for practical applications. Inspired by the natural alveoli tissue with interconnected structure and well-distributed enzyme catalytic sites on the wall for the simultaneously fast diffusion and in situ catalytic conversion of substrates, here, we proposed the controllable synthesis of bioinspired carbon cathode with interconnected porous structure and asymmetric coordinated V-S1N3 sites for efficient and stable Li-S batteries. The enzyme-mimetic V-S1N3 shows asymmetric electronic distribution and high tunability, therefore enhancing in situ polysulfide conversion activities. Experimental and theoretical results reveal that the high charge asymmetry degree and large atom radius of S in V-S1N3 result in sloping adsorption for polysulfide, thereby exhibiting low thermodynamic energy barriers and long-range stability (0.076 % decay over 600 cycles).

Delocalization Engineering of Heme-Mimetic Artificial Enzymes for Augmented Reactive Oxygen Catalysis.

Developing artificial enzymes based on organic molecules or polymers for reactive oxygen species (ROS)-related catalysis has broad applicability. Herein, inspired by porphyrin-based heme mimics, we report the synthesis of polyphthalocyanine-based conjugated polymers (Fe-PPc-AE) as a new porphyrin-evolving structure to serve as efficient and versatile artificial enzymes for augmented reactive oxygen catalysis. Owing to the structural advantages, such as enhanced π-conjugation networks and π-electron delocalization, promoted electron transfer, and unique Fe-N coordination centers, Fe-PPc-AE showed more efficient ROS-production activity in terms of Vmax and turnover numbers as compared with porphyrin-based conjugated polymers (Fe-PPor-AE), which also surpassed reported state-of-the-art artificial enzymes in their activity. More interestingly, by changing the reaction medium and substrates, Fe-PPc-AE also revealed significantly improved activity and environmental adaptivity in many other ROS-related biocatalytic processes, validating the potential of Fe-PPc-AE to replace conventional (poly)porphyrin-based heme mimics for ROS-related catalysis, biosensors, or biotherapeutics. It is suggested that this study will offer essential guidance for designing artificial enzymes based on organic molecules or polymers.

Novel tactile bottle neck adaptor facilitates eye drop adherence in visually impaired patients.

PURPOSE: To test the use of Ring-IT, a novel 3D tactile bottle neck adaptor in topical eye drop adherence in visually impaired patients. METHODS: Bottle neck ring adaptors with either one, two or three protrusions with cube or sphere endings were designed. In phase 1, low vision was simulated in healthy subjects (n=20) with a 20/200 vision simulator; while in phase 2, visually impaired patients (n=26; 20/70 or worse) were recruited. Subjects were randomised to six combinations of varying protrusions and shapes on medication bottles and asked to identify these traits at different presentations. Responses and time to identify were recorded. RESULTS: Phase 1: 98.3% of subjects correctly identified the number of protrusions. Mean time to identify was 4.5±6.1 s. Identification success for cube and sphere end pieces were 91.7% and 73.3%, with average time for identification of 9.9±7.6 and 10.9±9.0 s. In phase 2, 92.3% of subjects correctly identified the number of protrusions. Mean time to identify was 6.0±3.0 s. Identification success for cube and sphere end pieces were 78.2% and 74.4%; with average time for identification of 7.5±4.8 and 8.5±5.6 s, respectively. CONCLUSIONS: Ring-IT was identified with accuracy and speed by both low vision simulated subjects, and by patients with true limited visual capabilities. These tactile bottle neck ring adaptors can be used as an assistive low vision aid device and may increase eye drop regimen adherence in visually impaired patients.

Reshifting Na+ from Shoots into Long Roots Is Associated with Salt Tolerance in Two Contrasting Inbred Maize (Zea mays L.) Lines.

Maize, as a glycophyte, is hypersensitive to salinity, but the salt response mechanism of maize remains unclear. In this study, the physiological, biochemical, and molecular responses of two contrasting inbred lines, the salt-tolerant QXH0121 and salt-sensitive QXN233 lines, were investigated in response to salt stress. Under salt stress, the tolerant QXH0121 line exhibited good performance, while in the sensitive QXN233 line, there were negative effects on the growth of the leaves and roots. The most important finding was that QXH0121 could reshift Na+ from shoots into long roots, migrate excess Na+ in shoots to alleviate salt damage to shoots, and also improve K+ retention in shoots, which were closely associated with the enhanced expression levels of ZmHAK1 and ZmNHX1 in QXH0121 compared to those in QXN233 under salt stress. Additionally, QXH0121 leaves accumulated more proline, soluble protein, and sugar contents and had higher SOD activity levels than those observed in QXN233, which correlated with the upregulation of ZmP5CR, ZmBADH, ZmTPS1, and ZmSOD4 in QXH0121 leaves. These were the main causes of the higher salt tolerance of QXH0121 in contrast to QXN233. These results broaden our knowledge about the underlying mechanism of salt tolerance in different maize varieties, providing novel insights into breeding maize with a high level of salt resistance.

Mn-Oxygen Compounds Coordinated Ruthenium Sites with Deprotonated and Low Oxophilic Microenvironments for Membrane Electrolyzer-Based H2 -Production.

Among the platinum-group metals, ruthenium (Ru), with a low water dissociation energy, is considered a promising alternative to substitute Pt for catalyzing hydrogen evolution reaction (HER). However, optimizing the adsorption-desorption energies of H* and OH* intermediates on Ru catalytic sites is extremely desirable but remains challenging. Inspired by the natural catalytic characteristics of Mn-oxygen complex, this study reports to design Mn-oxygen compounds coordinated Ru sites (MOC-Ru) with deprotonated and low oxophilic microenvironments for modulating the adsorption-desorption of H* and OH* to promote HER kinetics. Benefiting from the unique advantages of MOC structures, including weakened HOH bond at interface, electron donation ability, and deprotonation capability, the MOC-Ru exhibits extremely low overpotential and ultralong stability in both acidic and alkaline electrolytes. Experimental observations and theoretical calculations elucidate that the MOC can accelerate water dissociation kinetics and promote OH* desorption in alkaline conditions and trigger the long-range H* spillover for H2 -release in acid conditions. The outstanding activity and stability of membrane electrolyzer display that the MOC-Ru catalyst holds great potential as cathode for H2 -production. This study provides essential insights into the crucial roles of deprotonated and low oxophilic microenvironments in HER catalysis and offers a new pathway to create an efficient water-splitting cathode.

Electronic Structure-Dependent Water-Dissociation Pathways of Ruthenium-Based Catalysts in Alkaline H2 -Evolution.

Ruthenium (Ru)-based catalysts have displayed compelling hydrogen evolution activities, which hold the promising potential to substitute platinum in alkaline H2 -evolution. In the challenging alkaline electrolytes, the water-dissociation process involves multistep reactions, while the profound origin and intrinsic factors of diverse Ru species on water-dissociation pathways and reaction principles remain ambiguous. Here the fundamental origin of water-dissociation pathways of Ru-based catalysts in alkaline media to be from their unique electronic structures in complex coordination environments are disclosed. These theoretical results validate that the modulated electronic structures with delocalization-localization coexistence at their boundaries between the Ru nanocluster and single-atom site have a profound influence on water-dissociation pathways, which push H2 O* migration and binding orientation during the splitting process, thus enhancing the dissociation kinetics. By creating Ru catalysts with well-defined nanocluster, single-atom site, and also complex site, the electrocatalytic data shows that both the nanocluster and single-atom play essential roles in water-dissociation, while the complex site possesses synergistically enhanced roles in alkaline electrolytes. This study discloses a new electronic structure-dependent water-dissociation pathway and reaction principle in Ru-based catalysts, thus offering new inspiration to design efficient and durable catalysts for the practical production of H2 in alkaline electrolytes.

Metal-oxo Cluster Mediated Atomic Rh with High Accessibility for Efficient Hydrogen Evolution.

Achieving single-atom catalysts (SACs) with high metal content and outstanding performance as well as robust stability is critically needed for clean and sustainable energy. However, most of the synthesized SACs are undesired on the loading content of the metal due to the anchored metals and the supports as well as the synthesizing methods. Herein, a Rh-SAC with high accessibility by loading it on the metal nodes of metal-porphyrin-based PCN MOFs (PCN-224) as supporting material is reported. Significantly, the PCN-Rh15.9 /KB catalyst with a high Rh content of 15.9 wt% exhibits excellent hydrogen evolution activity with a low overpotential of 25 mV at a current density of 10 mA cm-2 and a mass activity of 7.7 A mg-1 Rh at overpotential of 150 mV, which is much better than that of the commercial Rh/C. Various characterizations reveal the Rh species is stabilized by the metal nodes bearing -O/OHx in MOFs, which is of importance for the high loading amount and the good activity. This work establishes an efficient approach to synthesize high content SACs on the nodes of MOFs for wide catalyst design.

Molybdenum Oxycarbide Supported Rh-Clusters with Modulated Interstitial C-O Microenvironments for Promoting Hydrogen Evolution.

Tuning the microenvironment and electronic structure of support materials is essential strategy to induce electron transfer between supports and active centers, which is of great importance in optimizing catalytic kinetics. In this study, the molybdenum oxycarbide supported Rh-clusters are synthesized with modulated interstitial C-O microenvironments (Rh/MoOC) for promoting efficient hydrogen evolution in water splitting. Both electronic structure characterizations and theoretical calculations uncover the apparent charge transfer from Rh to MoOC, which optimizes the d-band center, H2 O adsorption energy, and hydrogen binding energy, thus enhancing its intrinsic hydrogen-evolving activities. In addition, the co-occurrence of interstitial C and O atoms in MoOC supports plays a vital role in the dissociation reaction of water during the hydrogen-evolving process. Impressively, the Rh/MoOC exhibits excellent hydrogen-evolving activities in terms of exceptional turnover frequency values (11.4 and 39.41 H2 s-1 in alkaline and acidic media) and mass activities (21.3 and 73.87 A mg-1 in alkaline and acidic media) at an overpotential of 100 mV, which is more than 40 times higher than that of the benchmark commercial Rh/C catalysts. This work sheds new light on designing water dissociation materials that surpasses most of the reported catalysts.

Modulating Electronic Environment of Ru Nanoclusters via Local Charge Transfer for Accelerating Alkaline Water Electrolysis.

Compared to platinum catalysts, ruthenium (Ru) is disclosed as a promising alternative for alkaline water electrolysis due to its similar hydrogen adsorption energy and relatively lower water dissociation barrier. However, in the challenging alkaline media, the dissatisfied Volmer step during water dissociation of Ru metal prohibits its practical applications. Here, a new pathway to modulate the electronic environment of Ru catalysts via a local charge transfer strategy for tuning the water dissociation kinetics and accelerating the alkaline water electrolysis is proposed. The obtained catalysts are engineered by assembling and subsequently pyrolyzing the layer-stacked and 2D porphyrin-based Ru-N coordination polymers on nanocarbon supports. Benefiting from the well-defined Ru nanocluster-Nx -coordination bonds (Runc -Nx ), unique electronic environments, and local charge transfer properties, the catalysts exhibit the exceptional activity of 17 mV overpotential at 10 mA cm-2 and robust stability in water, which is more efficient than state-of-the-art Ru catalysts. The theoretical calculation suggests that the Runc -Nx sites enhance the nucleophilic attack of water and weaken the HOH bond. This study manifests that tailoring the bond environments of Ru clusters can significantly modulate their intrinsic catalytic activities and stabilities, which may open new avenues for developing high-active and durable catalysts for water electrolysis.

Visual outcome and ocular complications in patients with lacrimal gland carcinoma after eye-sparing surgery and adjuvant radiation therapy.

BACKGROUND: We report visual outcomes and ocular complications in patients with lacrimal gland carcinoma who had eye-sparing surgery followed by radiotherapy. METHODS: This review included consecutive patients with lacrimal gland carcinoma who underwent eye-sparing surgery and adjuvant radiotherapy or concurrent chemoradiation therapy between 2007 and 2018. Clinical data, including details of ophthalmological examinations and radiation treatment were reviewed. RESULTS: The study included 23 patients, 15 males and 8 females, with median age 51 years. Twenty patients (87%) received intensity-modulated proton therapy; 3 (13%) received intensity-modulated radiotherapy. Nineteen patients (83%) received concurrent chemotherapy. After a median follow-up time of 37 months (range: 8-83), 13 patients (57%) had best-corrected visual acuity 20/40 or better, 3 (13%) had moderate vision loss (between 20/40 and 20/200) and 7 (30%) had severe vision loss (20/200 or worse). The most common ocular complications were dry eye disease (21 patients; 91%), radiation retinopathy (16; 70%) and cataract progression (11; 49%). Tumour crossing the orbital midline (p=0.014) and Hispanic ethnicity (p=0.014) were associated with increased risk of severe vision loss. The risk of radiation retinopathy was significantly different among the three racial groups; Hispanic patients (n=3) had the highest rate of retinopathy (p<0.001). Tumour size, initial T category and total prescribed radiation dose were not significantly associated with severe vision loss. CONCLUSION: Eye-sparing surgery followed by adjuvant radiotherapy in patients with lacrimal gland carcinoma has a reasonable overall visual prognosis. Patients with tumours crossing the orbital midline and Hispanic patients have a higher risk of severe vision loss.

Origin and Acceleration of Insoluble Li2 S2 -Li2 S Reduction Catalysis in Ferromagnetic Atoms-based Lithium-Sulfur Battery Cathodes.

Accelerating insoluble Li2 S2 -Li2 S reduction catalysis to mitigate the shuttle effect has emerged as an innovative paradigm for high-efficient lithium-sulfur battery cathodes, such as single-atom catalysts by offering high-density active sites to realize in situ reaction with solid Li2 S2 . However, the profound origin of diverse single-atom species on solid-solid sulfur reduction catalysis and modulation principles remains ambiguous. Here we disclose the fundamental origin of Li2 S2 -Li2 S reduction catalysis in ferromagnetic elements-based single-atom materials to be from their spin density and magnetic moments. The experimental and theoretical studies disclose that the Fe-N4 -based cathodes exhibit the fastest deposition kinetics of Li2 S (226 mAh g-1 ) and the lowest thermodynamic energy barriers (0.56 eV). We believe that the accelerated Li2 S2 -Li2 S reduction catalysis enabled via spin polarization of ferromagnetic atoms provides practical opportunities towards long-life batteries.

Early Pregnancy Modulates Expression of the Nod-like Receptor Family in Lymph Nodes of Ewes.

NOD receptors (NLRs) mediate adaptive immune responses and immune tolerance. Nevertheless, it is not clear if gestation modulates the NLR signaling pathway in lymph nodes of ewes. In this study, lymph nodes of ewes were collected at day 16 of the estrous cycle, and at days 13, 16 and 25 of gestation (n = 6 for each group). RT-qPCR, Western blot and immunohistochemistry analysis were used to analyze the expression of the NLR family, including NOD1, NOD2, CIITA, NAIP, NLRP1, NLRP3 and NLRP7. The data showed that early gestation enhanced expression of NOD1, CIITA, NLRP1, NLRP3 and NLRP7 mRNA, as well as proteins at day 16 of gestation, and the expression levels of NOD2, CIITA, NLRP1 and NLRP7 were higher at days 13 and 25 of gestation than day 16 of the estrous cycle. However, NOD1 expression was lower on days 13 and 25 of gestation compared to day 16 of the estrous cycle, and early gestation suppressed NAIP expression. In summary, early pregnancy modulated expression of the NLR family in ovine lymph nodes, which participates in immune regulation, and this modulation may be necessary for pregnancy establishment in ewes.

Isolation, Identification and Pollution Prevention of Bacteria and Fungi during the Tissue Culture of Dwarf Hygro (Hygrophila polysperma) Explants.

Microbial contamination causes serious damage in plant tissue culture, and attention is always being paid regarding how to control and prevent the unwanted pollution. Dwarf hygro (Hygrophila polysperma) is a popular ornamental aquatic plant and its tissue culture has been reported, but the microbial pollution and the cure of microbial pollution was unknown. In this study, a number of bacteria and fungi were isolated from contaminants in MS culture media. Based on the 16S rDNA and ITS sequencing, it was identified that fifteen bacteria belong to Bacillus, Enterobacter, Pantoea, Kosakonia, Ensifer and Klebsiella, and three fungi belong to Plectosphaerella, Cladosporium and Peniophora, respectively. In addition, some drugs were further tested to be free of the bacteria and fungi pollution. The results revealed that 10 µg/mL of kanamycin, 5 µg/mL of chloramphenicol, and 0.015625% potassium sorbate could be applied jointly in MS media to prevent the microbial pollution, and the survival rate of H. polysperma explants was highly improved. This study reveals the bacteria and fungi species from the culture pollution of H. polysperma and provides a practical reference for optimizing the tissue culture media for other aquatic plants.

Modulation of Nod-like Receptor Expression in the Thymus during Early Pregnancy in Ewes.

Nucleotide-binding oligomerization domain receptors (NOD-like receptors, NLRs) are involved in modulating the innate immune responses of the trophoblast and the placenta in normal pregnancy. The thymus participates in regulation of innate and adaptive immune responses. However, it is unclear whether expression of NLR is modulated in the maternal thymus during early pregnancy. In this study, thymuses were sampled at day 16 of the estrous cycle, and at days 13, 16 and 25 of gestation (n = 6 for each group) from ewes after slaughter. Different stages were chosen because the maternal thymus was under the different effects of interferon-tau and/or progesterone or not. RT-qPCR, Western blot and immunohistochemistry analysis were used to analyze the expression of the NLR family, including NOD1; NOD2; major histocompatibility complex class II transactivator (CIITA); NLR family apoptosis inhibitory protein (NAIP); nucleotide-binding oligomerization domain and Leucine-rich repeat and Pyrin domain containing protein 1 (NLRP1), NLRP3 and NLRP7. The results showed that expression level of NOD1 was changed with the pregnancy stages, and expression levels of NOD2, CIITA, NAIP, NLRP1, NLRP3 and NLRP7 mRNA and proteins were peaked at day 13 of pregnancy. The levels of NOD2 and CIITA were increased during early pregnancy. The stainings for NOD2 and NLRP7 proteins were located in epithelial reticular cells, capillaries and thymic corpuscles. In summary, pregnancy stages changed expression of NLR family in the maternal thymus, which may be related to the modulation of maternal thymic immune responses, and beneficial for normal pregnancy in sheep.

Optimal Design of Multiple Floating Rings for 3D Large-Area Trench Electrode Silicon Detector.

The 3D electrode silicon detector eliminates the limit of chip thickness, so it can reduce the electrode spacing (small area) and effectively improve the radiation hardness. In order to expand the application range of the 3D electrode detector, we first propose a 3D large-area silicon detector with a large sensitive volume, and realize multiple floating rings on the upper and lower surfaces of the detector. Due to the influence of different charge states and energy levels in the Si-SiO2 interface system, the top and bottom of the 3D P+ electrode are more prone to avalanche breakdown in the 3D large-area detector before the detector is completely depleted or the carrier saturation drift velocity is reached. Moreover, the electric field distribution becomes very uneven under the influence of the oxide charge, resulting in non-equilibrium carriers that cannot drift in the optimal path parallel to the detector surface. In this paper, the effect of floating rings on the performance of a 3D large-area silicon detector is studied by TCAD simulation. It can increase avalanche breakdown voltage by 14 times in a non-irradiated environment, and can work safely in a moderate irradiated environment. The charge collection efficiency can be effectively improved by optimizing the drift path.

3D Simulation, Electrical Characteristics and Customized Manufacturing Method for a Hemispherical Electrode Detector.

The theoretical basis of a hypothetical spherical electrode detector was investigated in our previous work. It was found that the proposed detector has very good electrical characteristics, such as greatly reduced full depletion voltage, small capacitance and ultra-fast collection time. However, due to the limitations of current technology, spherical electrode detectors cannot be made. Therefore, in order to use existing CMOS technology to realize the fabrication of the detector, a hemispherical electrode detector is proposed. In this work, 3D modeling and simulation including potential and electric field distribution and hole concentration distribution are carried out using the TCAD simulation tools. In addition, the electrical characteristics, such as I-V, C-V, induced current and charge collection efficiency (CCE) with different radiation fluences, are studied to predict the radiation hardness property of the device. Furthermore, a customized manufacturing method is proposed and simulated with the TCAD-SPROCESS simulation tool. The key is to reasonably set the aspect ratio of the deep trench in the multi-step repetitive process and optimize parameters such as the angle, energy, and dose of ion implantation to realize the connection of the heavily doped region of the near-hemispherical electrode. Finally, the electrical characteristics of the process simulation are compared with the device simulation results to verify its feasibility.

PERIVASCULAR FLOWER-BUD-LIKE LESIONS ON EN FACE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN PATIENTS WITH VITREORETINAL LYMPHOMA.

PURPOSE: To describe perivascular flower-bud-like lesions (PFBLs) as novel characteristics of vitreoretinal lymphoma on en face optical coherence tomography (OCT) angiography. METHODS: A retrospective chart review was performed on 23 consecutive patients (35 eyes), who had biopsy-proven vitreoretinal lymphoma between January 2018 and March 2021. En face OCT angiography images were analyzed before and after intervention. PFBLs were initially identified on midretinal slabs of en face OCT angiography, and were further characterized by other imaging modalities. RESULTS: Perivascular flower-bud-like lesions were detected in 12 eyes (34.3%) of 8 patients, of which 8 eyes had best-corrected visual acuity of 20/40 or better. In 10 of the 12 eyes, PFBLs were detected within 6 months of symptom onset. On en face OCT angiography, PFBLs presented as punctate points or confluent bands surrounding retinal vessels, with arterial and venous involvement. In 4 of the 12 eyes, arteries were mainly affected. On OCT B-scans, PFBLs commonly appeared as hyperreflective full-thickness intraretinal lesions that colocalized with subretinal pigment epithelium deposits (3 eyes, 25%) and retinal pigment epithelium irregularities (4 eyes, 33.3%). However, PFBLs could not always be identified on other imaging modalities such as fundus photographs and fundus fluorescein angiography. In all eyes with follow-up, PFBLs attenuated or resolved months after receiving chemotherapy or diagnostic vitrectomy. CONCLUSION: PFBLs are characteristic imaging findings of vitreoretinal lymphoma and may facilitate an early diagnosis of vitreoretinal lymphoma, which would in turn lead to more timely and effective treatment.

Crystalline Lattice-Confined Atomic Pt in Metal Carbides to Match Electronic Structures and Hydrogen Evolution Behaviors of Platinum.

Platinum-based catalysts occupy a pivotal position in diverse catalytic applications in hydrogen chemistry and electrochemistry, for instance, the hydrogen evolution reactions (HER). While adsorbed Pt atoms on supports often cause severe mismatching on electronic structures and HER behaviors from metallic Pt due to the different energy level distribution of electron orbitals. Here, the design of crystalline lattice-confined atomic Pt in metal carbides using the Pt-centered polyoxometalate frameworks with strong PtO-metal covalent bonds is reported. Remarkably, the lattice-confined atomic Pt in the tungsten carbides (Ptdoped @WCx , both Pt and W have atomic radii of 1.3 Å) exhibit near-zero valence states and similar electronic structures as metallic Pt, thus delivering matched energy level distributions of the Pt 5dz 2 and H 1s orbitals and similar acidic hydrogen evolution behaviors. In alkaline conditions, the Ptdoped @WCx exhibits 40 times greater mass activity (49.5 A mgPt -1 at η = 150 mV) than the Pt@C because of the favorable water dissociation and H* transport. These findings offer a universal pathway to construct urgently needed atomic-scale catalysts for broad catalytic reactions.

Biodegradation of quinolinic acid by a newly isolated bacterium Alcaligenes faecalis strain JQ191.

Quinolinic acid (QA) is a pyridine derivative that can be found in many organisms and is widely used in the chemical industry. However, QA possesses excitotoxic properties. To date, the catabolism of QA mediated by microorganisms has rarely been reported. In this study, a QA-degrading strain (JQ191) was isolated from sewage sludge. Based on phenotypic and 16S rRNA gene phylogenetic analysis, the strain was identified as Alcaligenes faecalis. Strain JQ191 was able to utilize QA as the sole source of carbon and nitrogen for growth. QA-cultured cells of JQ191 completely degrade 200 mg/L QA within 2 days in a mineral salt medium, whereas the LB-cultured cells experienced a 2-day lag period before degrading QA, indicating that the catabolic enzymes involved in QA degradation were induced by QA. 6-Hydroxypicolinic acid (6HPA) was identified as an intermediate of QA degradation by strain JQ191. A 6HPA monooxygenase gene picB was cloned, genetically disrupted, and heterologously expressed, and the results show that picB was responsible for catalyzing 6HPA to 3,6DHPA in JQ191. A new QA mineralization pathway was proposed. This study identifies a new bacterium candidate that has a potential application prospect in the bioremediation of QA-polluted environment, as well as provides new insights into the bacterial catabolism of QA.

A Library of ROS-Catalytic Metalloenzyme Mimics with Atomic Metal Centers.

MetalN-coordinated centers supported by carbonaceous substrates have emerged as promising artificial metalloenzymes (AMEs) to mimic the biocatalytic effects of their natural counterparts. However, the synthesis of well-defined AMEs that contain different atomic metalN centers but present similar physicochemical and coordination structures remains a substantial challenge. Here, 20 different types of AMEs with similar geometries and well-defined atomic metalN-coordinated centers are synthesized to compare and disclose the catalytic activities, substrate selectivities, kinetics, and reactive oxygen species (ROS) products. Their oxidase (OXD)-, peroxidase (POD)-, and halogen peroxidase (HPO)-mimetic catalytic behaviors are systematically explored. The Fe-AME shows the highest OXD- and HPO-mimetic activities compared to the other AMEs due to its high vmax (0.927 × 10-6 m s-1 ) and low Km (1.070 × 10-3 m), while the Cu-AME displays the best POD-like performance. Furthermore, theoretical calculation reveals that the ROS-catalytic paths and activities are highly related to the electronic structures of the metal centers. Benefiting from its facile adsorption of H2 O2 molecule and lower energy barrier to generating •O2 - , the Fe-AME displays higher ROS-catalytic performances than the Mn-AME. The engineered AMEs show not only remarkably high ROS-catalytic performances but also provide new guidance toward developing metalN-coordinated biocatalysts for broad application fields.