Nanotrap Grafted Anionic MOF for Superior Uranium Extraction from Seawater

On-demand uranium extraction from seawater (UES) can mitigate growing sustainable energy needs, while high salinity and low concentration hinder its recovery. A novel anionic metal-organic framework (iMOF-1A) is demonstrated adorned with rare Lewis basic pyrazinic sites as uranyl-specific nanotrap serving as robust ion exchange material for selective uranium extraction, rendering its intrinsic ionic characteristics to minimize leaching. Ionic adsorbents sequestrate 99.8% of the uranium in 120 mins (from 20,000 ppb to 24 ppb) and adsorb large amounts of 1336.8 mg g-1 and 625.6 mg g-1 from uranium-spiked deionized water and artificial seawater, respectively, with high distribution coefficient, Kd U ≥ 0.97 × 106  mL g-1 . The material offers a very high enrichment index of ≈5754 and it achieves the UES standard of 6.0 mg g-1 in 16 days, and harvests 9.42 mg g-1 in 30 days from natural seawater. Isothermal titration calorimetry (ITC) studies quantify thermodynamic parameters, previously uncharted in uranium sorption experiments. Infrared nearfield nanospectroscopy (nano-FTIR) and tip-force microscopy (TFM) enable chemical and mechanical elucidation of host-guest interaction at atomic level in sub-micron crystals revealing extant capture events throughout the crystal rather than surface solely. Comprehensive experimentally guided computational studies reveal ultrahigh-selectivity for uranium from seawater, marking mechanistic insight.

Ca-MOF-Derived Porous Sorbents for High-Yield Solar-Driven Atmosphere Water Harvesting

The development of high-yield, metal-organic framework (MOF)-based water harvesters in arid areas remains challenging due to the absence of effective strategies for enhancing water sorption capacity and kinetics. Herein, we presented a novel strategy for in situ fabrication of calcium chloride (CaCl2) decorated MOF-derived porous sorbents (PCC-42) through pyrolysis Ca-MOF and subsequently hydrochloric acid (HCl) vapor treatment process. The resulting PCC-42 sorbents exhibited a high water adsorption capacity of 3.04 g g-1 at 100% relative humidity (RH), outstanding photothermal performance, and rapid water uptake-release kinetics, surpassing most reported MOFs adsorbents. At 20, 30, 40, and 50% RH, PCC-42 demonstrated water uptake capacity of 0.45, 0.59, 0.76, and 0.9 g g-1, which represented an increase of 421 and 940% (at 20% RH) and 333 and 351% (at 30% RH) compared to Ca-MOF and CaCl2·2H2O, respectively. Approximately 80% of the adsorbed water in PCC-42 could be released under one sun within 50 min. Indoor water harvesting experiments demonstrated that PCC-42 is a promising adsorbent for various humidity environments. Additionally, outdoor solar-driven atmospheric water harvesting (AWH) tests revealed a high daily water production of 1.13 L/kgadsorbent under typical arid conditions (30-60% RH). The proposed strategy helps the design of high-performance adsorbents for solar-driven AWH in arid environments.

Bifunctional Localized High-Concentration Electrolyte for the Fast Kinetics of Lithium Batteries at Low Temperatures

Traditional lithium batteries cannot work well at low temperatures due to the sluggish desolvation process, which limits their applications in low-temperature fields. Among various previously reported approaches, solvation regulation of electrolytes is of great importance to overcome this obstacle. In this work, a tetrahydrofuran (THF)-based localized high-concentration electrolyte is reported, which possesses the advantages of a unique solvation structure and improved mobility, enabling a Li/lithium manganate (LMO) battery to cycle stably at room temperature (retains 85.9% after 300 cycles) and to work at a high rate (retains 69.0% at a 10C rate). Apart from that, this electrolyte demonstrates superior low-temperature performance, delivering over 70% capacity at -70 °C and maintaining 72.5 mAh g^-1 (≈77.1%) capacity for 200 cycles at a 1C rate at -40 °C. Also, even when the rate increases to 5C, the battery could still operate well at -40 °C. This work demonstrates that solvation regulation has a significant impact on the kinetics of cells at low temperatures and provides a design method for future electrolyte design.

Fast Hydrogen Sorption Kinetics in Mg-VCl3 Produced by Cryogenic Ball-Milling

Hydrogen storage in Mg/MgH₂ materials is still an active research topic. In this work, a mixture of Mg-15wt.% VCl₃ was produced by cryogenic ball milling and tested for hydrogen storage. Short milling time (1 h), liquid N₂ cooling, and the use of VCl₃ as an additive produced micro-flaked particles approximately 2.5-5.0 µm thick. The Mg-15wt.% VCl₃ mixture demonstrated hydrogen uptake even at near room-temperature (50 °C). Mg-15wt.% VCl₃ achieved ~5 wt.% hydrogen in 1 min at 300 °C/26 bar. The fast hydriding kinetics is attributed to a reduction of the activation energy of the hydriding reaction (E_{a hydriding} = 63.8 ± 5.6 kJ/mol). The dehydriding reaction occurred at high temperatures (300-350 °C) and 0.8-1 bar hydrogen pressure. The activation energy of the dehydriding reaction is 123.11 ± 0.6 kJ/mol. Cryomilling and VCl₃ drastically improved the hydriding/dehydriding of Mg/MgH₂.

Fast Isomerization Before Isomerization-Hydroformylation: Probing the Neglected Period with A Novel Microfluidic Device

By combining the concept of flash chemistry and radial synthesis, a novel microreactor (Flashstop reactor) was designed to study isomerization process of hydroformylation by a Rh/tetraphosphite catalyst in a time scale of seconds. It was found that in the initial 313 seconds, 60~99% of 1-octene was isomerized to 2- and 3-octenes before the formation of aldehydes. Within this period, two different types of isomerization reactions were observed. It was proposed that a monohydride complex without CO ligand accounts for the ultrafast isomerization in the initial 30 seconds. The isomerization rate with such monohydride species was calculated much faster than that with the well-known H(CO)Rh(P-P) species. Both experimental and DFT computational studies were carried out to support this assumption. Fast transformations early on in catalytic cycles have been rarely studied due to the lack of proper tools. We believe that the Flashstop reactor is a powerful tool for analysis of kinetics in gas-liquid biphasic reactions within a time scale of seconds to minutes.

Fast Cysteine Bioconjugation Chemistry

Cysteine bioconjugation serves as a powerful tool in biological research and has been widely used for chemical modification of proteins, constructing antibody-drug conjugates, and enabling cell imaging studies. Cysteine conjugation reactions with fast kinetics and exquisite selectivity have been under heavy pursuit as they would allow clean protein modification with just stoichiometric amounts of reagents, which minimizes side reactions, simplifies purification and broadens functional group tolerance. In this concept, we summarize the recent advances in fast cysteine bioconjugation, and discuss the mechanism and chemical principles that underlie the high efficiencies of the newly developed cysteine reactive reagents.

Nitrogen and Sulfur Co-Doped Hierarchically Porous Carbon Nanotubes for Fast Potassium Ion Storage

Exploration of advanced carbon anode material is the key to circumventing the sluggish kinetics and poor rate capability for potassium ion storage. Herein, a synergistic synthetic strategy of engineering both surface and structure is adopted to design N, S co-doped carbon nanotubes (NS-CNTs). The as-designed NS-CNTs exhibit unique features of defective carbon surface, hollow tubular channel, and enlarged interlayer space. These features significantly contribute to a large potassium storage capacity of 307 mA h g^-1 at 1 A g^-1 and a remarkable rate performance with a capacity of 151 mA h g^-1 even at 5 A g^-1 . Furthermore, an excellent cyclability with 98% capacity retention after 500 cycles at 2 A g^-1 is also achieved. Systematic analysis by in situ Raman spectroscopy and ex situ TEM demonstrates the structural stability and reversibility in the charge-discharge process. Although the kinetics studies reveal the capacitive-dominated process for potassium storage, density functional theory calculations provide evidence that N, S co-doping contributes to expanding the interlayer space to promote the K-ion insertion, improving the electronic conductivity, and providing ample defective sites to favor the K-ion adsorption.

Pseudocapacitive Vanadium Nitride Quantum Dots Modified One-Dimensional Carbon Cages Enable Highly Kinetics-Compatible Sodium Ion Capacitors

The kinetics incompatibility between battery-type anode and capacitive-type cathode for sodium ion hybrid capacitors (SIHCs) seriously hinders their overall performance output. Herein, we construct a SIHCs device by coupling with quantum grade vanadium nitride (VN) nanodots anchored in one-dimensional N/F co-doped carbon nanofiber cages hybrids (VNQDs@PCNFs-N/F) as the freestanding anode and the corresponding activated N/F co-doped carbon nanofiber cages (APCNFs-N/F) as cathode. The strong coupling of VN quantum dots with N/F co-doped 1D conductive carbon cages effectively facilitates the ion/electron transport and intercalation-conversion-deintercalation reactions, ensuring fast sodium storage to surmount aforesaid kinetics incompatibility. Additionally, density functional theory calculations cogently manifest that the abundant active sites in the VNQDs@PCNFs-N/F configuration boost the Na⁺ adsorption/reaction activity well which will promote both "intrinsic" and "extrinsic" pseudocapacitance and further improve anode kinetics. Consequently, the assembled SIHCs device can achieve high energy densities of 157.1 and 95.0 Wh kg^-1 at power densities of 198.8 and 9100.5 W kg^-1, respectively, with an ultralong cycling life over 8000 cycles. This work further verified the feasibility of kinetics-compatible electrode design strategy toward metal ion hybrid capacitors.

Rose-like VS2 Nanosheets Chemically Anchored on Carbon Nanotubes for Flexible Zinc-Ion Batteries with Enhanced Properties

Rechargeable aqueous zinc-ion batteries (ZIBs) are an attractive alternative for flexible energy storage devices due to their excellent safety and low cost. One of the main challenges that plagues their practical applications is the restricted variety of cathode materials with fast reaction kinetics and good mechanical properties. Herein, we prepared rose-like VS₂ nanosheets which have decent specific capacities, metallic conductivity, and open-enough channels and further incorporated them into a single-walled carbon nanotube (SWCNT) network, achieving a C-V chemical-bonded freestanding VS₂@SWCNT (C-VS₂) composite. Such chemical bonding in the composites builds a bridge for rapid electron transfer and ion diffusion in the longitudinal direction from one layer to another layer. As a result, the reversible Zn/C-VS₂ system in core cells exhibits a high specific capacity (205.3 mA h g^-1 at 0.1 A g^-1), an excellent cyclic stability (115.4 mA h g^-1 was obtained after 1500 cycles at 5 A g^-1), and a remarkable rate capability (135.4 mA h g^-1 at 10 A g^-1). Furthermore, the freestanding C-VS₂ films with good flexibility and conductivity can serve as a flexible cathode to assemble soft-packaged ZIBs. Meanwhile, the soft-packaged ZIB has good electrochemical stability even under different bending conditions (the discharge capacity dropped by only 2.1 mA h g^-1 after bending). This work offers insights into the rational design of zinc-ion hosts throughout chemical bond engineering.

A Desolvation-Free Sodium Dual-Ion Chemistry for High Power Density and Extremely Low Temperature

The development of conventional rechargeable batteries based on intercalation chemistry in the fields of fast charge and low temperature is generally hindered by the sluggish cation-desolvation process at the electrolyte/electrode interphase. To address this issue, a novel desolvation-free sodium dual-ion battery (SDIB) has been proposed by using artificial graphite (AG) as anode and polytriphenylamine (PTPAn) as cathode. Combining the cation solvent co-intercalation and anion storage chemistry, such a SDIB operated with ether-based electrolyte can intrinsically eliminate the sluggish desolvation process. Hence, it can exhibit an extremely fast kinetics of 10 Ag^-1 (corresponding to 100C-rate) with a high capacity retention of 45 %. Moreover, the desolvation-free mechanism endows the battery with 61 % of its room-temperature capacity at an ultra-low temperature of -70 °C. This advanced battery system will open a door for designing energy storage devices that require high power density and a wide operational temperature range.

Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H2O2 but Slowly with O2

Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo-EcBfr, pre-loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di-Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di-Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2-unreactive di-Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.

Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H2 O2 but Slowly with O2

Both O₂ and H₂O₂ can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo‐EcBfr, pre‐loaded anaerobically with Fe²⁺, was exposed to O₂ or H₂O₂. We show that O₂ binds di‐Fe²⁺ FC reversibly, two Fe²⁺ ions are oxidized in concert and a H₂O₂ molecule is formed and released to the solution. This peroxide molecule further oxidizes another di‐Fe²⁺ FC, at a rate circa 1000 faster than O₂, ensuring an overall 1:4 stoichiometry of iron oxidation by O₂. Initially formed Fe³⁺ can further react with H₂O₂ (producing protein bound radicals) but relaxes within seconds to an H₂O₂‐unreactive di‐Fe³⁺ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H₂O₂ rather than sequester iron.

V2O3 Nanoparticles Confined in High-Conductivity and High-Throughput Carbon Nanofiber Nanohybrids for Advanced Sodium-Ion Capacitors

Electrode materials with high conductivity and high mass transport rate are highly desirable for a variety of electrochemical energy devices but face a grand challenge to be readily prepared yet. Here, we propose the design and preparation of a nanohybrid of V₂O₃ nanoparticles embedded in a multichannel carbon nanofiber (V₂O₃@MCNF) network with high conductivity and high mass transport. We demonstrate the V₂O₃@MCNF shows superior capability for sodium storage with an excellent capacity of 214.3 mA h g^-1 even at 5 A g^-1, thanks to its high conductivity for electron transfer and facilitated mass transportation endowed by the one-dimensional conductive multichannel fiber structure. Such favorable structures and properties in V₂O₃@MCNFs enable them to be applied as high-performance anodes of sodium-ion hybrid capacitors (SIHCs), successfully addressing the critical kinetics imbalance between Faradaic anodes and capacitive cathodes for application of SIHCs, which show impressively high energy/power densities along with impressive cycling performance over 10,000 cycles.

Pseudocapacitive Ti-Doped Niobium Pentoxide Nanoflake Structure Design for a Fast Kinetics Anode toward a High-Performance Mg-Ion-Based Dual-Ion Battery

Magnesium-ion batteries (MIBs) have received increasing attention for next-generation energy storage recently because of the natural abundance, high capacity, and dendrite-free deposition of Mg. However, their applications are hindered by irreversible Mg anode plating in conventional electrolytes and the lack of cathode materials, demonstrating high working voltage, satisfactory Mg²⁺ diffusivity, and long cycling life. In this work, we first developed a novel magnesium-ion based dual-ion battery (Mg-DIB) by utilizing expanded graphite as the cathode and Ti-doped niobium pentoxide nanoflakes (Ti-Nb₂O₅ NFs) as the anode. The Ti-Nb₂O₅ NFs showed hierarchical structures of microspheres with diameters of 4-5 μm assembled by nanoflakes. For the first time, the Mg-ion storage mechanism in Ti-Nb₂O₅ NFs was investigated. Benefiting from the hierarchical structure design and pseudocapacitive intercalation behavior of Mg ions, the Ti-Nb₂O₅ NF anode exhibited fast Mg-ion diffusion. Consequently, the Mg-DIB exhibited a high discharge capacity of 93 mA h g^-1 at 1 C (1 C corresponding to 100 mA g^-1), along with good long-term cycling performance with a capacity retention of 79% at 3 C after 500 cycles. The Mg-DIB also demonstrated a capacity retention of 77% at 5C, indicating its good rate performance. Moreover, the Mg-DIB exhibited a high discharge medium voltage of ∼1.83 V, thus enabling a high energy density of 174 W h kg^-1 at 183 W kg^-1 and 122 W h kg^-1 at a high power density of 845 W kg^-1, among the best of the reported magnesium-ion full batteries. Our work provides a new strategy to improve the performance of MIBs and other rechargeable batteries.

Joint Cationic and Anionic Redox Chemistry for Advanced Mg Batteries

Lack of appropriate cathodes severely restrains the development of high-energy Mg batteries. In this work, we proposed joint cationic and anionic redox chemistry of transition-metal (TM) sulfides as the most promising way out. A series of solid-solution pyrite Fe_xCo_1-xS₂ (0 ≤ x ≤ 1) was specially designed, in which S 3p electrons pour into the d bands of Fe and Co, generating redox-active dimerized (S₂)^2-. The Fe_0.5Co_0.5S₂ sample is highlighted to deliver a high specific energy of 240 Wh/kg at room temperature involving both cationic (Fe and Co) and anionic (S) redox. The highly delocalized electronic clouds in pyrite structures comfortably accommodate the charge of Mg²⁺, contributing to the fast kinetics and the superior cycling stability of the Fe_0.5Co_0.5S₂. It is anticipated that the joint cationic and anionic redox chemistry proposed in this work would be the ultimate answer for designing high-energy cathodes for advanced Mg batteries.

Loss of a single methylation in 23S rRNA delays 50S assembly at multiple late stages and impairs translation initiation and elongation

Ribosome biogenesis is a complex process, and dozens of factors are required to facilitate and regulate the subunit assembly in bacteria. The 2'-O-methylation of U2552 in 23S rRNA by methyltransferase RrmJ is a crucial step in late-stage assembly of the 50S subunit. Its absence results in severe growth defect and marked accumulation of pre50S assembly intermediates. In the present work, we employed cryoelectron microscopy to characterize a set of late-stage pre50S particles isolated from an Escherichia coli ΔrrmJ strain. These assembly intermediates (solved at 3.2 to 3.8 Å resolution) define a collection of late-stage particles on a progressive assembly pathway. Apart from the absence of L16, L35, and L36, major structural differences between these intermediates and the mature 50S subunit are clustered near the peptidyl transferase center, such as H38, H68-71, and H89-93. In addition, the ribosomal A-loop of the mature 50S subunit from ΔrrmJ strain displays large local flexibility on nucleotides next to unmethylated U2552. Fast kinetics-based biochemical assays demonstrate that the ΔrrmJ 50S subunit is only 50% active and two times slower than the WT 50S subunit in rapid subunit association. While the ΔrrmJ 70S ribosomes show no defect in peptide bond formation, peptide release, and ribosome recycling, they translocate with 20% slower rate than the WT ribosomes in each round of elongation. These defects amplify during synthesis of the full-length proteins and cause overall defect in protein synthesis. In conclusion, our data reveal the molecular roles of U2552 methylation in both ribosome biogenesis and protein translation.

Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C Electrode Material for Lithium Ion Batteries Exhibiting Faster Kinetics and Enhanced Stability

Natrium super ionic conductor (NASICON) materials providing attractive properties such as high ionic conductivity and good structural stability are considered as very promising materials for use as electrodes for lithium- and sodium-ion batteries. Herein, a new high-performance electrode material, Li_0.5Ni_0.5Ti_1.5Fe_0.5(PO₄)₃/C, was synthesized via the sol-gel method and was electrochemically tested as an anode for lithium ion batteries, providing enhanced electrochemical performance as a result of nickel substitution into the lithium site in the LiTi₂(PO₄)₃ family of materials. The synthesized material showed good ionic conductivity, excellent structural stability, stable long-term cycling performance, and improved high rate cycling performance compared to LiTi₂(PO₄)₃. The Li_0.5Ni_0.5Ti_1.5Fe_0.5(PO₄)₃/C electrode delivered reversible capacities of about 93 and 68% of its theoretical one at current rates of 0.1 C (6.42 mA·g^-1) after 100 cycles and 5 C (320.93 mA·g^-1) after 1000 cycles, respectively. Theoretically, three Li⁺ ions can be inserted into the vacancies of the Li_0.5Ni_0.5Ti_1.5Fe_0.5(PO₄)₃/C structure. However, when the electrode is discharged to 0.5 V, more than three Li⁺ ions are inserted into the NASICON structure, leading to its structural transformation, and thus to an irreversible electrochemical behavior after the first discharge process.

Iodine Vapor Transport-Triggered Preferential Growth of Chevrel Mo6S8 Nanosheets for Advanced Multivalent Batteries

Owing to its unique structure, Chevrel phase (CP) is a promising candidate for applications in rechargeable multivalent (Mg and Al) batteries. However, its wide applications are severely limited by time-consuming and complex synthesis processes, accompanied by uncontrollable growth and large particle sizes, which will magnify the charge trapping effect and lower the electrochemical performance. Here, an iodine vapor transport reaction (IVT) is proposed to obtain large-scale and highly pure Mo₆S₈ nanosheets, in which iodine helps to regulate the growth kinetics and induce the preferential growth of Mo₆S₈, as a typical three-dimensional material, to form nanosheets. When applied in rechargeable multivalent (Mg and Al) batteries, Mo₆S₈ nanosheets show very fast kinetics owing to the short diffusion distance, thereby exhibiting lower polarization, higher capacities, and better low-temperature performance (up to -40 °C) compared to that of microparticles obtained via the conventional method. It is anticipated that Mo₆S₈ nanosheets would boost the application of Chevrel phase, especially in areas of energy storage and catalysis, and the IVT reaction would be generalized to a wide range of inorganic compound nanosheets.

Interchain-Expanded Vanadium Tetrasulfide with Fast Kinetics for Rechargeable Magnesium Batteries

Magnesium batteries are promising energy storage systems because of the advantages of low raw material cost, high theoretical capacity, and high operational safety properties. However, the divalent Mg²⁺ has a sluggish kinetic in the cathode materials which resulted in poor electrochemical performance. Many strategies were adopted to improve the mobility of Mg²⁺ in the host structures. In this paper, we report on the optimization of chain-like structure VS₄@reduced graphene oxide (VS₄@rGO) through expanding interchain distance to increase the ion diffusivity. By combining theoretical calculations and experimental investigations, the expansion of interchain distance and reversible intercalation of MgCl⁺ are revealed. With the fast kinetics of MgCl⁺ (instead of Mg²⁺) intercalation into expanded VS₄@rGO, higher capacity of 268.3 mA h g^-1 at 50 mA g^-1 and better rate capability of 85.9 mA h g^-1 at 2000 mA g^-1 have been obtained. In addition, the expanded VS₄@rGO framework shows a high specific capacity of 147.2 mA h g^-1 after 100 cycles and a very wide operating temperature range (-35 to 55 °C). The high discharge capacity, excellent rate capability, and broad temperature adaptability demonstrate promising application of VS₄@rGO in magnesium batteries.

Fast Electrochemical Storage Process in Sputtered Nb2O5 Porous Thin Films

The formation of a thin film electrode exhibiting high capacity and high rate capabilities is challenging in the field of miniaturized electrochemical energy storage. Here, we present an elegant strategy to tune the morphology and the properties of sputtered porous Nb₂O₅ thin films deposited on Si-based substrates via the magnetron sputtering deposition technique. Kinetic analysis of the redox reactions is studied to qualify the charge storage process, where we observe a non-diffusion-controlled mechanism within the porous niobium pentoxide thin film. To improve the surface capacity of the Nb₂O₅ porous electrode, the thickness is progressively increased up to 0.94 μm, providing a surface capacity close to 60 μAh·cm^-2 at 1 mV·s^-1. The fabrication of high energy density miniaturized power sources based on the optimized T-Nb₂O₅ films could be achieved for Internet of Things applications requiring high rate capability.

Homologous Hierarchical Porous Hollow Carbon Spheres Anode and Bowls Cathode Enabling High-Energy Sodium-Ion Hybrid Capacitors

It is a highly expected avenue to construct dual-carbon sodium-ion hybrid capacitors (SIHCs) using hierarchical porous carbon with interconnected pores, high accessible surface area, and disordered carbon frameworks for ameliorating the sluggish kinetics of SIHCs. In this work, a novel dual-carbon SIHCs system with homologous enhanced kinetics hierarchical porous hollow carbon spheres (HPCS) and hierarchical porous hollow carbon bowls (HPCB) as the anode and cathode is constructed for the first time. In a Na half-cell configuration, the HPCS anode synthesized through a facile one-pot in-situ template route demonstrates a superior reversible capacity as well as outstanding rate capability and cycleability, and the HPCB cathode fabricated by chemical activation of HPCS exhibits excellent capacitive behaviors. Thanks to superior properties and structures of the anode and cathode, the constructed novel dual-carbon SIHCs present an exceptionally high energy/power density (128.5 Wh kg^-1 and 11.9 kW kg^-1), along with a long cycling lifespan with retained morphology. This study on the kinetics of enhanced dual-carbon SIHCs opens a new avenue for optimizing the microstructure of hierarchical porous carbon and constructing new type of high-performance SIHCs systems.

Prussian Blue Analogue with Fast Kinetics Through Electronic Coupling for Sodium Ion Batteries

Alternative battery systems based on the chemistry of sodium are being considered to offer sustainability and cost-effectiveness. Herein, a simple and new method is demonstrated to enable nickel hexacyanoferrate (NiHCF) Prussian blue analogues (PBA) nanocrystals to be an excellent host for sodium ion storage by functionalization with redox guest molecule. The method is achieved by using NiHCF PBA powders infiltrated with the 7,7,8,8-tetracyanoquinododimethane (TCNQ) solution. Experimental and ab initio calculations results suggest that TCNQ molecule bridging with Fe atoms in NiHCF Prussian blue analogue leads to electronic coupling between TCNQ molecules and NiHCF open-framework, which functions as an electrical highway for electron motion and conductivity enhancement. Combining the merits including high electronic conductivity, open framework structure, nanocrystal, and interconnected mesopores, the NiHCF/TCNQ shows high specific capacity, fast kinetics and good cycling stability, delivering a high specific capacity of 35 mAh g^-1 after 2000 cycles, corresponding a capacity loss of 0.035% decay per cycle.

On the pH dependence of class-1 RF-dependent termination of mRNA translation

We have studied the pH dependence of the rate of termination of bacterial protein synthesis catalyzed by a class-1 release factor (RF1 or RF2). We used a classical quench-flow technique and a newly developed stopped-flow technique that relies on the use of fluorescently labeled peptides. We found the termination rate to increase with increasing pH and, eventually, to saturate at about 70 s(-1) with an apparent pKa value of about 7.6. From our data, we suggest that class-1 RF termination is rate limited by the chemistry of ester bond hydrolysis at low pH and by a stop-codon-dependent and pH-independent conformational change of RFs at high pH. We propose that RF-dependent termination depends on the participation of a hydroxide ion rather than a water molecule in the hydrolysis of the ester bond between the P-site tRNA and its peptide chain. We provide a simple explanation for why the rate of termination saturated at high pH in our experiments but not in those of others.

Kinetic and thermodynamic studies of peptidyltransferase in ribosomes from the extreme thermophile Thermus thermophilus

Throughout evolution, emerging organisms survived by adapting existing biochemical processes to new reaction conditions. Simple protein enzymes balanced changes in structural stability with changes that permitted optimal catalysis by adjustments in both entropic and enthalpic contributions to the free energy of activation for the reaction. Study of adaptive mechanisms by large multicomponent enzymes such as the ribosome has been largely unexplored. Here we have determined the kinetic and thermodynamic parameters of peptidyltransferase in ribosomes from the extreme thermophile Thermus thermophilus. Activity of thermophilic enzymes can be assayed over a wide range of temperatures, enabling one to measure accurate catalytic rates and determine enthalpic and entropic contributions to the free energy of activation of the reaction. Differences in the reaction conditions used here and in published studies on mesophilic ribosomes prevent direct comparison, but our data on Thermus ribosomes suggest that these ribosomes have adapted to changing environments using the same strategies as simple protein enzymes, balancing stability and flexibility without loss of catalytic rate. This strategy must be a very ancient process, perhaps first used by primitive ribosomes in the RNA World.

The nucleotide-binding site of bacterial translation initiation factor 2 (IF2) as a metabolic sensor

Translational initiation factor 2 (IF2) is a guanine nucleotide-binding protein that can bind guanosine 3',5'-(bis) diphosphate (ppGpp), an alarmone involved in stringent response in bacteria. In cells growing under optimal conditions, the GTP concentration is very high, and that of ppGpp very low. However, under stress conditions, the GTP concentration may decline by as much as 50%, and that of ppGpp can attain levels comparable to those of GTP. Here we show that IF2 binds ppGpp at the same nucleotide-binding site and with similar affinity as GTP. Thus, GTP and the alarmone ppGpp can be considered two alternative physiologically relevant IF2 ligands. ppGpp interferes with IF2-dependent initiation complex formation, severely inhibits initiation dipeptide formation, and blocks the initiation step of translation. Our data suggest that IF2 has the properties of a cellular metabolic sensor and regulator that oscillates between an active GTP-bound form under conditions allowing active protein syntheses and an inactive ppGpp-bound form when shortage of nutrients would be detrimental, if not accompanied by slackening of this synthesis.