Cryo-EM structures reveal the dynamic transformation of human alpha-2-macroglobulin working as a protease inhibitor.

Human alpha-2-macroglobulin is a well-known inhibitor of a broad spectrum of proteases and plays important roles in immunity, inflammation, and infections. Here, we report the cryo-EM structures of human alpha-2-macroglobulin in its native state, induced state transformed by its authentic substrate, human trypsin, and serial intermediate states between the native and fully induced states. These structures exhibit distinct conformations, which reveal the dynamic transformation of alpha-2-macro-globulin that acts as a protease inhibitor. The results shed light on the molecular mechanism of alpha-2-macroglobulin in entrapping substrates.

Porous Polymers Containing Metallocalix[4]arene for the Extraction of Tobacco-Specific Nitrosamines.

We designed porous polymers with a tungsten-calix[4]arene imido complex as the nitrosamine receptor for the efficient extraction of tobacco-specific nitrosamines (TSNAs) from water. The interaction between the metallocalix[4]arene and the TSNA, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosamine ketone, NNK) was investigated. We found that the incorporation of the nitrosamine receptor into porous polymers increased their selectivity toward NNK over nicotine. The polymer with an optimal ratio of calixarene-containing and porosity-inducing building blocks showed a high maximum adsorption capacity of up to 203 mg/g toward NNK under sonication, which was among the highest values reported. The adsorbed NNK could be removed from the polymer by soaking it in acetonitrile, enabling the adsorbent to be reused. A similar extraction efficiency to that under sonication could be achieved using the polymer-coated magnetic particles under stirring. We also proved that the material could efficiently extract TSNAs from real tobacco extract. This work not only provides an efficient material for the extraction of TSNAs but also offers a design strategy for efficient adsorbents.

NASICON type KTi2(PO4)3 decorated by NTCDA-derived carbon layer for enhanced lithium/sodium storage.

NASICON type KTi2(PO4)3 decorated by NTCDA-derived carbon layer (KTP/NC) was prepared as anode material to obtain sustainable lithium/sodium ion storage (LIBs/SIBs). Due to its prominent capacitance, good electronic conductivity and ability to constrain volume, the KTP/NC composite realizes highly electrochemical kinetics both in LIBs and SIBs. For LIBs, the KTP/NC composite delivers a superior reversible capacity of 598.1 mAh g-1 after 200 cycles at 0.5C, impressive cyclability with 225.5 mAh g-1 after 3000 cycles at an ultrahigh current density of 26.1 C and conspicuous rate performance of 160.6 mAh g-1 even at 52.2 C. In addition, the composite has a wide operation-temperature window with favorable capacities of 147.1-372.9 mAh g-1 from -10 °C to 50 °C. As for SIBs, the KTP/NC composite maintains a stable discharge capacity of 112.5 mAh g-1 after 700 cycles at a current density of 2.6 C and conspicuous rate performance of 86.7 mAh g-1 at 5.2 C. The KTP/NC anode exhibits discharge capacities of 29.9-112.6 mAh g-1 from -10 °C to 40 °C. The results demonstrate that the KTP/NC composite would be a promising electrode material for LIBs and SIBs.

Metallocalix[4]arene Polymers for Gravimetric Detection of N-Nitrosodialkylamines.

N-Nitrosamines are found in food, drugs, air, water, and soil. They pose a significant risk to human health because of their carcinogenicity; consequently, materials that can be used to selectively and sensitively detect nitrosamines are needed. In this work, we designed and synthesized two polymers bearing calix[4]arene or 4-tert-butylcalix[4]arene tungsten-imido complexes (PCalixH and PCalixtBu) as N-nitrosodimethylamine (NDMA) receptors. The interaction between metallocalix[4]arene monomers/polymers and NDMA was confirmed by 1H NMR and IR spectroscopy. Single-crystal X-ray analysis further revealed that the host-guest interaction is based on binding of the terminal oxygen of NDMA to tungsten within the calixarene cavity. Gravimetric detection of NDMA was performed on a quartz crystal microbalance (QCM) in air. Both polymers show responses to NDMA, with PCalixtBu exhibiting a low theoretical limit of detection of 5 ppb for NDMA. The sensor also shows high selectivity toward NDMA and moderate humidity tolerance. This work provides a sensitive sensor for detection of NDMA and also offers a class of new, selective, and efficient NDMA receptors for the future design of NDMA sensors and NDMA extraction materials.

Ultrasonic synthesis of Mn-Ni-Fe tri-metallic oxide anchored on polymer-grafted conductive carbon for rechargeable zinc-air battery.

As a promising electrochemical energy device, a rechargeable zinc-air battery (RZAB) requires cost-effective cathode catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Some earth-abundant transition metal oxides have certain levels of bi-functional ORR/OER catalytic activities yet low electronic conductivities. The addition of high-electronic-conductivity material such as carbon black could result in another problem because there is low compatibility between metal oxide and carbon. In this work, polymer chains are ultrasonically prepared to act as binders to anchor metal-oxide active sites to porous domains of carbon black. The monomer N-isopropyl acrylamide is polymerized under ultrasonication instead of using conventional radical initiators which are dangerous and harmful. Reactive free radicals produced by ultrasonic irradiation can also help to form the Mn-Ni-Fe tri-metallic oxide. Thus, aided by the amide-type polymer as an adhesive, the tri-metallic oxide anchored on polymer-grafted carbon black prepared by ultrasonication possess a large number of metal-oxide active sites and hierarchical pores, contributing substantially to the enhanced ORR/OER electrocatalytic performance in the RZABs. Accordingly, this work provides interesting insight into the effective combination of inherently incompatible components for the fabrication of composite materials from an ultrasonic standpoint.

Electrocatalytic desalination with CO2 reduction and O2 evolution.

Multifunctional electrocatalytic desalination is a promising method to increase the production of additional valuable chemicals during the desalination process. In this work, a multifunctional desalination device was demonstrated to effectively desalinate brackish water (15 000 ppm) to 9 ppm while generating formate from captured CO2 at the Bi nanoparticle cathode and releasing oxygen at the Ir/C anode. The salt feed channel is sandwiched between two electrode chambers and separated by ion-exchange membranes. The electrocatalytic process accelerates the transportation of sodium ions and chloride ions in the brine to the cathode and anode chamber, respectively. The fastest salt removal rate to date was obtained, reaching up to 228.41 µg cm-2 min-1 with a removal efficiency of 99.94%. The influences of applied potential and the concentrations of salt feed and electrolyte were investigated in detail. The current research provides a new route towards an electrochemical desalination system.

Structure Recovery and Recycling of Used LiCoO2 Cathode Material.

A large number of lithium batteries have been retiring from the market of energy storage. Thus, recycling of the used electrode materials is becoming urgent. In this study, an industrial machinery processing was used to recover the crystal structure of the waste LiCoO2 materials with the combination of small-scale equipment repair technology. The results show that the crystal parameters of the repaired LiCoO2 material become small, the unit cell volume is reduced, and the crystal structure tends to be stable. The Co-O bond length of 1.9134 nm, O-Co-O bond angle of 94.72°, the (003) interplanar spacing of 0.467 nm indicate the excellent recovery level of the repaired LiCoO2 . In addition, the electrochemical performance of the repaired LiCoO2 material is greatly improved, compared with the waste material. The capacity of the repaired electrode material can be maintained at 120 mAh g-1 after 100 cycles at the current density of 0.2C. The promising rate performance of the repaired electrode material demonstrates the stable structure. This research work provides a large-scale method for the direct recovery of LiCoO2 with the reduction of unnecessary energy and reagent consumption, which will be beneficial to the environmental protection.

Achieving High-Quality Freshwater from a Self-Sustainable Integrated Solar Redox-Flow Desalination Device.

Solar-assisted electrochemical desalination has offered a new energy-water nexus technology for sustainable development in recent studies. However, only a few reports have demonstrated insufficient photocurrent, a low salt removal rate, and poor stability. In this study, a high-quality freshwater level of 5-10 ppm (from an initial feed of 10 000 ppm), an enhanced salt removal rate (217.8 µg cm-2 min-1 of NaCl), and improved cycling and long-term stability are achieved by integrating dye-sensitized solar cells (DSSCs) and redox-flow desalination (RFD) under light irradiation without additional electrical energy consumption. The DSSC redox electrolyte (I- /I3- ) is circulated between the photoanode (N719/TiO2 ) and intermediate electrode (graphite paper). Two DSSCs in parallel or series connections are directly coupled to the RFD device. Overall, this hybrid system can be used to boost photo electrochemical desalination technology. The energy-water nexus technology will open a new route for dual-role devices with photodesalination functions without energy consumption and solar-to-electricity generation.

Electric-Field-Induced Chirality in Columnar Liquid Crystals.

We describe a novel class of tetraphenylbenzene-based discotic molecules with exceptional self-assembling properties. Absorption and fluorescence studies confirmed the formation of J-type aggregates in solution. The discotic mesogens also show an enhancement of the emission upon aggregation. Interestingly, these discotic molecules displayed enantiotropic hexagonal columnar liquid crystal (LC) phases that can be switched into a helical columnar organization by application of an electric field. The helical columns arise from the electric-field-induced tilt of the polar fluorobenzene ring that directs all of the peripheral phenyl groups into a propeller-like conformation with respect to the central benzene core. A cooperative assembly process of these propeller-shaped molecules resolves into a helical columnar organization, in which the preferred helical sense is obtained from the stereogenic center proximate to the polar carbon-fluorine bond. The ease of inducing chirality in columnar LCs by an electric field presents opportunities to create next-generation chiral materials for a variety of applications.

Robust hetero-MoO3/MoO2@N-doped carbon nanobelts decorated with oxygen deficiencies as high-performance anodes for potassium/sodium storage.

Hetero-MoO3/MoO2@N-doped carbon nanobelt anodes (h-MoO3/MoO2@NC) with long lifespan and superior rate capability were proposed by a simple in situ reduction tactic, in which pristine MoO3 was transformed into heterogeneous MoO3/MoO2. The hetero-MoO3/MoO2 architecture significantly improves the electronic conductivity and affords abundant oxygen deficiencies. Meanwhile, the synergistic effect of internal MoO3/MoO2 heterostructure and outer N-doped carbon layer (NC) accomplishes a balance of sustainable potassium/sodium storage and ultra-durable structure stability. In potassium ion batteries, the anodes steadily maintain a reversible capacity of 283 mAh g-1 after 6000 cycles at 0.5 A g-1 and 153 mAh g-1 after 1000 cycles under 2 A g-1, as well as an impressive rate capability of 131 mAh g-1 at 3 A g-1. In sodium ion batteries, the anodes purchase a steady capacity of 152 mAh g-1 even after 10,000 cycles at 2 A g-1, and 190 mAh g-1 after 5000 cycles at 0.5 A g-1. Moreover, the h-MoO3/MoO2@NC composite possesses a prominent pseudocapacitive effect and good thermal adaptability (-10 to 50 °C) in both KIBs and SIBs. The results indicate that the h-MoO3/MoO2@NC composite would be an auspicious material for potassium/sodium storage and other ion batteries.

A Modified Pressure Dressing to Avoid Severe Bleeding After Circumcision With a Disposable Circumcision Suture Device and a Discussion on the Mechanism of Bleeding With the Disposable Circumcision Suture Device.

INTRODUCTION: A novel type of a disposable circumcision suture device (DCSD) has been proved to be effective and safe; however, a few cases of severe bleeding took place after circumcisions. AIM: To evaluate the effectiveness of a modified double-layer pressure dressing to avoid severe bleeding after circumcision with the DCSD, in our department in a prospective randomized controlled study, and discuss the mechanism of bleeding with DCSD. METHODS: Patients with redundant foreskin or phimosis were included between September 2018 and November 2019 and divided into 2 groups: In group A, the conventional pressure dressing was performed; in group B, an modified double-layer pressure dressing was performed. MAIN OUTCOME MEASURE: The main outcomes and complications (surgical time, incidence of glans ischemia, severe bleeding rate, infection rate, pain level, total cost, and overall satisfaction) were collected and analyzed. RESULTS: A total of 624 patients were recruited for this study. There was no difference in the average age and body mass index between 2 groups. No patient suffered obvious glans ischemia. In group B, lower pain level, lower incidences of severe bleeding, and better satisfaction were recorded. CONCLUSION: The mechanism of bleeding with the DCSD was discussed in this study, and the modified pressure dressing was proved effective, safe, and easy to perform. W Jiang, J-li Fu, W-l Guo, et al. A Modified Pressure Dressing to Avoid Severe Bleeding After Circumcision With a Disposable Circumcision Suture Device and a Discussion on the Mechanism of Bleeding With the Disposable Circumcision Suture Device. Sex Med 2021;9:100288.

Cyclopentadienone Derivative Dimers as Tunable Photoswitches.

A series of photoswitchable cyclopentadienone derivative dimers bearing bromo, thienyl, 4-(dimethylamino)phenyl, 3-pyridinyl, 4-nitrophenyl and cyano groups was designed and facilely synthesized. Photoswitching properties such as the photoconversions in the photostationary state (PSS), the thermal kinetics and thermal half-lives of photoisomers were systematically investigated. These photoswitches show high fatigue resistance and large photoconversions in the PSS. This work proves that the photoswitching properties of photoswitches based on cyclopentadienone dimers can be tuned by substitution groups and also pave the way to functionalize the cyclopentadienone derivative dimer-based photoswitch, which is important for its future applications.

3d Transition-Metal-Mediated Columbite Nanocatalysts for Decentralized Electrosynthesis of Hydrogen Peroxide.

Decentralized electrosynthesis of hydrogen peroxide (H2 O2 ) via oxygen reduction reaction (ORR) can enable applications in disinfection control, pulping and textile bleaching, wastewater treatment, and renewable energy storage. Transition metal oxides are usually not efficient catalysts because they are more selective to produce H2 O. Here, it is shown that divalent 3d transition metal cations (Mn, Fe, Co, Ni, and Cu) can control the catalytic activity and selectivity of columbite nanoparticles. They are synthesized using polyoxoniobate (K7 HNb6 O19 ·13H2 O) and divalent metal cations by a hydrothermal method. The optimal NiNb2 O6 holds an H2 O2 selectivity of 96% with the corresponding H2 O2 Faradaic efficiency of 92% in a wide potential window from 0.2 to 0.6 V in alkaline electrolyte, superior to other transition metal oxide catalysts. Ex situ X-ray photoelectron and operando Fourier-transformed infrared spectroscopic studies, together with density functional theory calculations, reveal that 3d transition metals shift the d-band center of catalytically active surface Nb atoms and change their interactions with ORR intermediates. In an application demonstration, NiNb2 O6 delivers H2 O2 productivity up to 1 molH2O2 gcat -1 h-1 in an H-shaped electrolyzer and can yield catholytes containing 300 × 10-3 m H2 O2 to efficiently decomposing several organic dyes. The low-cost 3d transition-metal-mediated columbite catalysts show excellent application potentials.

Chelating Phosphine Ligand Stabilized AuNPs in Methane Detection.

The capping reagent plays an essential role in the functional properties of gold nanoparticles (AuNPs). Multiple stimuli-responsive materials are generated via diverse surface modification. The ability of the organic ligand shell on a gold surface to create a porous shell capable of binding small molecules is demonstrated as an approach to detect molecules, such as methane, that would be otherwise difficult to sense. Thiols are the most studied capping ligands of AuNPs used in chemiresistors. Phosphine capping groups are usually seen as stabilizers in synthesis and catalysis. However, by virtue of the pyramidal shape of triarylphosphines, they are natural candidates to create intrinsic voids within the ligand shell of AuNPs. In this work, surface-functionalized (capped) AuNPs with chelating phosphine ligands are synthesized via two synthetic routes, enabling chemiresistive methane gas detection at sub-100 ppm levels. These AuNPs are compared to thiol-capped AuNPs, and studies were undertaken to evaluate structure-property relationships for their performance in the detection of hydrocarbons. Polymer overcoatings applied to the conductive networks of the functionalized AuNP arrays were shown to reduce resistivity by promoting the formation of conduction pathways with decreased core-core distance between nanoparticles. Observations made in the context of developing methane sensors provide insight relevant to applications of phosphine or phosphine-containing surface groups in functional AuNP materials.

Azulene-Pyridine-Fused Heteroaromatics.

Azulene, a nonbenzenoid bicyclic aromatic hydrocarbon with unique electronic structure, is a promising building block for constructing nonbenzenoid π-conjugated systems. However, azulene-fused (hetero)aromatics remain rare as a result of limited synthetic methods. We report herein the unexpected synthesis of azulene- and pyridine-fused heteroaromatics Az-Py-1, a seven fused ring system with 30π electrons, by reductive cyclization of a 1-nitroazulene. The structure of Az-Py-1 was unambiguously confirmed by single-crystal X-ray analysis, and analogues Az-Py-2-Az-Py-6 were also synthesized, demonstrating that this is an effective method for constructing azulene- and pyridine-fused heteroaromatics. Theoretical calculations and photophysical and electrochemical studies of Az-Py-1-Az-Py-6 suggest their potential as semiconductors, and the single-crystal ribbons of Az-Py-1 show high hole mobilities up to 0.29 cm2 V-1 s-1.

2020 Roadmap on Zinc Metal Batteries.

Metallic zinc (Zn) is considered to be a safe and low-cost anode for rechargeable batteries. Thus, several zinc metal batteries (ZMBs) have been well developed, i. e., zinc silver batteries, Zn-MnO2 batteries, nickel-zinc batteries, zinc-air batteries and other kinds of zinc ion batteries. ZMBs are strongly correlated with electrochemistry, electrodes, electrolytes and battery structures. To support the development of this field, we herein invite some famous research experts to write this roadmap for giving some guidance in future research. The roadmap will include their research status, challenge, opportunities, and the technology advance in their fields. We expect this roadmap will produce active influence in developing green, low-cost, safe ZMBs for our bright life in future.

Author Correction: Unveiling how intramolecular stacking modes of covalently linked dimers dictate photoswitching properties.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Dual-Zinc Electrode Electrochemical Desalination.

Continuous and low-energy desalination technologies are in high demand to enable sustainable water remediation. Our work introduces a continuous desalination process based on the redox reaction of a dual-zinc electrode. The system consists of two zinc foils as redox electrodes with flowing ZnCl2 electrolyte, concentrated and diluted salt streams with three anion- and cation-exchange membranes (AEM and CEM) separated configuration (AEM|CEM|AEM). If a constant current is applied, the negative zinc electrode is oxidized, and electrons are released to the external circuit, whereas the positive zinc electrode is reduced, causing salt removal in the dilution stream. The results showed that brackish water can be directly desalted to 380.6 ppm during a continuous batch-mode process. The energy consumption can be as low as 35.30 kJ mol-1 at a current density of 0.25 mA cm-2 , which is comparable to reverse osmosis. In addition, the dual-zinc electrode electrochemical desalination demonstrates excellent rate performance, reversibility, and batch cyclability through electrode exchange regeneration. Our research provides a route for continuous low-energy desalination based on metal redox mediators.

Unveiling how intramolecular stacking modes of covalently linked dimers dictate photoswitching properties.

Covalently linked π-stacked dimers represent the most significant platform for elucidating the relationship between molecular alignments and their properties. Here, we present the one-pot synthesis of two intramolecularly π-stacked dimers and disclose how intramolecular stacking modes dictate photoswitching properties. The dimer, which features cofacially stacked chromophores and geometrically favours intramolecular photochemical [2 + 2] cycloadditions, displays a nearly irreversible photoswitching behaviour. By contrast, the dimer, bearing crosswise stacked chromophores, is geometrically unfavourable for the cycloaddition and exhibits a highly reversible photoswitching process, in which the homolysis and reformation of carbon-carbon single bonds are involved. Moreover, the chiral carbon centres of both dimers endow these photoswitches with chirality and the separated enantiomers exhibit tuneable chiroptical properties by photoswitching. This work reveals that intramolecular stacking modes significantly influence the photochemical properties of π-stacked dimers and offers a design strategy toward chiral photoswitchable materials.