Photo-Assisted Li-N2 Batteries with Enhanced Nitrogen Fixation and Energy Conversion.

Li-N2 batteries have received widespread attention for their potential to integrate N2 fixation, energy storage, and conversion. However, because of the low activity and poor stability of cathode catalysts, the electrochemical performance of Li-N2 batteries is suboptimal, and their electrochemical reversibility has rarely been proven. In this study, a novel bifunctional photo-assisted Li-N2 battery system was established by employing a plasmonic Au nanoparticles (NPs)-modified defective carbon nitride (Au-Nv -C3 N4 ) photocathode. The Au-Nv -C3 N4 exhibits strong light-harvesting, N2 adsorption, and N2 activation abilities, and the photogenerated electrons and hot electrons are remarkably beneficial for accelerating the discharge and charge reaction kinetics. These advantages enable the photo-assisted Li-N2 battery to achieve a low overpotential of 1.32 V, which is the lowest overpotential reported to date, as well as superior rate capability and prolonged cycle stability (≈500 h). Remarkably, a combination of theoretical and experimental results demonstrates the high reversibility of the photo-assisted Li-N2 battery. The proposed novel strategy for developing efficient cathode catalysts and fabricating photo-assisted battery systems breaks through the overpotential bottleneck of Li-N2 batteries, providing important insights into the mechanism underlying N2 fixation and storage.

Adsorption of rare earth elements on a magnetic geopolymer derived from rice husk: studies in batch, column, and application in real phosphogypsum leachate sample.

There is a growing need to develop new strategies for rare earth element (REE) recovery from secondary resources. Herein, a novel approach to utilize biogenic silica (from rice husk) and metakaolin was employed to fabricate magnetic geopolymer (MGP) by incorporating metallic iron. The fabricated MGP adsorbent material was used to uptake Ce3+, La3+, and Nd3+ from synthetic solutions and real phosphogypsum leachate in batch and column modes. The MGP offers a negatively charged surface at pH above 2.7, and the uptake of REEs rises from pH 3 to 6. The kinetic study validated that the kinetics was much faster for Nd3+, followed by La3+ and Ce3+. A thermodynamic investigation validated the exothermic nature of the adsorption process for all selected REEs. The desorption experiment using 2 mol L-1 H2SO4 as the eluent demonstrated approximately 100% desorption of REEs from the adsorbent. After six adsorption-desorption cycles, the MGP maintained a high adsorption performance up to cycle five before suffering a significant decrease in performance in cycle six. The effectiveness of MGP was also assessed for its applicability in recovering numerous REEs (La3+, Ce3+, Pr3+, Sm3+, and Nd3+) from real leachate from phosphogypsum wastes, and the highest recovery was achieved for Nd3+ (95.03%) followed by Ce3+ (86.33%). The operation was also feasible in the column presenting suitable values of the length of the mass transfer zone. The findings of this investigation indicate that MGP adsorbent prepared via a simple route has the potential for the recovery of REEs from synthetic and real samples in both batch and continuous operations modes.

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.

Quantitative parameters of static imaging and fast kinetics imaging in 18F-FDG total-body PET/CT for the assessment of histological feature of pulmonary lesions.

Background: To investigate the value of quantitative parameters related to static imaging and fast kinetics imaging of total-body (TB) 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in differentiating benign from malignant pulmonary lesions and squamous cell carcinoma (SCC) from adenocarcinoma (AC) and to analyze the correlation of each parameter with the Ki-67 index. Methods: A total of 108 patients with pulmonary lesions from July 2021 to May 2022 in the Henan Provincial People's Hospital, China, were consecutively recruited for TB 18F-FDG PET/CT in this prospective study. Static imaging parameters maximum standardized uptake value (SUVmax) and fast kinetics imaging parameters transport constant (K1), rate constants (k2), time delay (td), and fractional blood volume (vb) were calculated and compared. The area under the receiver operating characteristic (ROC) curve (AUC), Delong test, Logistic regression analyses, and Pearson correlation were used to assess diagnostic efficacy, find independent predictors and analyse correlations respectively. Results: Malignant lesions had higher SUVmax and K1 and lower vb than benign lesions, and SCC had higher SUVmax and K1 and lower td and vb than AC (all P<0.05). For the differentiation of benign and malignant lesions, SUVmax, K1, and vb were independent predictors, and AUC (SUVmax + K1+ vb) =0.909 (95% CI: 0.839-0.956), AUC (SUVmax) =0.883 (95% CI: 0.807-0.937), AUC (K1) =0.810 (95% CI: 0.723-0.879), and AUC (vb) =0.746 (95% CI: 0.653-0.825), where AUC (SUVmax + K1+ vb) was significantly different from AUC (K1), AUC (vb) (Z=3.006, 3.965, all P<0.05). For the differentiation of SCC and AC, SUVmax, K1, td, and vb were independent predictors, and AUC (SUVmax + K1+ td + vb) =0.946 (95% CI: 0.840-0.991), AUC (SUVmax) =0.818 (95% CI: 0.680-0.914), AUC (K1) =0.770 (95% CI: 0.626-0.879), AUC (vb) =0.737 (95% CI: 0.590-0.853), and AUC (td) =0.669 (95% CI: 0.510-0.791), where AUC (SUVmax + K1+ td + vb) was significantly different from AUC (SUVmax), AUC (K1), AUC (vb), and AUC (td) (Z=2.269, 2.821, 2.848, and 3.276, all P<0.05). SUVmax and K1 were moderately and mildly positively correlated with the Ki-67 index (r=0.541, 0.452, all P<0.05), respectively. Conclusions: Quantitative parameters of static imaging and fast kinetics imaging in 18F-FDG total-body PET/CT can be used to differentiate benign from malignant pulmonary lesions and SCC from AC and to assess Ki-67 expression.

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 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 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 (Ea 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.

Diffusional Features of a Lithium-Sulfur Battery Exploiting Highly Microporous Activated Carbon.

Diffusion processes at the electrode/electrolyte interphase drives the performance of lithium-sulfur batteries, and activated carbon (AC) can remarkably vehicle ions and polysulfide species throughout the two-side liquid/solid region of the interphase. We reveal original findings such as the values of the diffusion coefficient at various states of charge of a Li-S battery using a highly porous AC, its notable dependence on the adopted techniques, and the correlation of the diffusion trend with the reaction mechanism. X-ray photoelectron spectroscopy (XPS) and X-ray energy dispersive spectroscopy (EDS) are used to identify in the carbon derived from bioresidues heteroatoms such as N, S, O and P, which can increase the polarity of the C framework. The transport properties are measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic intermittent titration technique (GITT). The study reveals Li+ -diffusion coefficient (DLi + ) depending on the technique, and values correlated with the cell state of charge. EIS, CV, and GITT yield a DLi + within 10-7 -10-8  cm2 s-1 , 10-8 -10-9  cm2 s-1 , and 10-6 -10-12  cm2 s-1 , respectively, dropping down at the fully discharged state and increasing upon charge. GITT allows the evaluation of DLi + during the process and evidences the formation of low-conducting media upon discharge. The sulfur composite delivers in a Li-cell a specific capacity ranging from 1300 mAh g-1 at 0.1 C to 700 mAh g-1 at 2C with a S loading of 2 mg cm-2 , and from 1000 to 800 mAh g-1 at 0.2C when the S loading is raised to 6 mg cm-2 .

3D printing of fast kinetics reconciled ultra-thick cathodes for high areal energy density aqueous Li-Zn hybrid battery.

The limitation of areal energy density of rechargeable aqueous hybrid batteries (RAHBs) has been a significant longstanding problem that impedes the application of RAHBs in miniaturized energy storage. Constructing thick electrodes with optimized geometrical properties is a promising strategy for achieving high areal energy density, but the sluggish ion/electron transfer and poor mechanical stability, as well as the increased electrode thickness, itself present well-known problems. In this work, a 3D printing technique is introduced to construct an ultra-thick lithium iron phosphate (LFP)/carboxylated carbon nanotube (CNT)/carboxyl terminated cellulose nanofiber (CNF) composite electrode with uncompromised reaction kinetics for high areal energy density Li-Zn RAHBs. The uniformly dispersed CNTs and CNFs form continuous interconnected 3D networks that encapsulate LFP nanoparticles, guaranteeing fast electron transfer and efficient stress relief as the electrode thickness increases. Additionally, multistage ion diffusion channels generated from the hierarchical porous structure assure accelerated ion diffusion. As a result, LFP/Zn hybrid pouch cells assembled with 3D printed electrodes deliver a well-retained reversible gravimetric capacity of about 143.5 mAh g-1 at 0.5 C as the electrode thickness increases from 0.52 to 1.56 mm, and establish a record-high areal energy density of 5.25 mWh cm-2 with an impressive utilization of active material up to 30 mg cm-2 for an ultra-thick (2.08 mm) electrode, which outperforms almost all reported zinc-based hybrid-ion and single-ion batteries. This work opens up exciting prospects for developing high areal energy density energy storage devices using 3D printing.

Measuring Binding at the Putative Melatonin Receptor MT3.

Melatonin, (N-acetyl-5-methoxytryptamine), is a neurohormone which possesses a wide range of biological effects. The effects mediated by melatonin are in part attributed to the antioxidant properties of the molecule. For a long time, melatonin had been described as a ligand of a putative "receptor" present in mammalian brains named MT3. Several studies were thus carried out with the goal of clarifying the nature of this melatonin "receptor." The experimental setup of the binding measurements is unusual. The present chapter aims at describing this technique. This binding site was confirmed independently by several groups, and it was eventually demonstrated that MT3 was the enzyme quinone reductase 2 (NQO2).

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.

Fluorination Treatment of Conjugated Protonated Polyanilines for High-Performance Sodium Dual-Ion Batteries.

The overall performance of dual-ion batteries (DIBs) is strongly linked to anions storage properties of cathodes. Whereas high energy/power densities and stabilities for DIBs are limited by cathodes. To overcome these barriers, we have designed a novel fluoridized-polyaniline-H+ /carbon nanotubes (FPHC) as cathode for high-efficiency PF6 - storage. F- in PF6 - is easy to form covalent bond with H on -NH- in FPHC, so that PF6 - can stably coordinate with FPHC, showing a symmetrical structure. FPHC cathode shows a highly reversible capacity of 73 mAh g-1 at 2 A g-1 after 2000 cycles, which provides a solid base for the advanced sodium dual-ion batteries (SDIBs) (310 Wh kg-1 /7720 W kg-1 ). Besides, the relative pouch-type SDIB can drive a vacuum cleaner model with an electric machine. This work may shed light on an up-and-coming strategy of robust cathodes for SDIBs.

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.

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.

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.

Fast and Efficient Mouse Pluripotency Reprogramming Using a Chemically-Defined Medium.

The reprogramming of somatic cells to obtain induced pluripotent stem cells (iPSCs) is an important biological and medical breakthrough, providing important applications for fields such as regenerative medicine and disease modeling. However, this promising technology is damped due to its low efficiency and slow kinetics. Therefore, we generated a practical workflow to rapidly and efficiently induce iPSCs from mouse embryonic fibroblasts (MEFs) using iCD1 (iPS chemically-defined medium 1). This protocol can easily be implemented in a standard cell culture laboratory and be applied to cell fate research.

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.

Photosynthetic transients in Chlorella sorokiniana during phycoremediation of dairy wastewater under distinct light intensities.

The present study is aimed to understand the photosynthetic transients of Chlorella sorokiniana SVMBIOEN2 during treatment of dairy wastewater under different light intensities (100, 150, and 200 µmol m-2s-1) in mixotrophic mode. Light intensities showed marked influence on photosystem behavior, lipid profile, and organic pollutant removal. Analysis of Chlorophyll a fluorescence transient including Fv/Fm, ETo/RC, TRo/RC, and Abs/RC showed better photosystem efficiency at 100 µmol m-2s-1 operations. OJIP curve fitting depicted a positive L-band at 150 µmol m-2s-1 indicating lower kinetic energy of photosystem II (PSII) reaction centres at high light intensities. Better photosynthetic activity at 100 µmol m-2s-1 operations resulted in good assimilation of biomass (2.3 g L-1), carbohydrates (10.2 mg g-1), and proteins (14 mg g-1) with a significant reduction in chemical oxygen demand (85%). Phycoremediation of dairy wastewater accumulates predominantly monounsaturated fatty acids followed by polyunsaturated fatty acids showing the application of C. sorokiniana in nutraceutical and food industries.

Kinetic Analysis Suggests Evolution of Ribosome Specificity in Modern Elongation Factor-Tus from "Generalist" Ancestors.

It has been hypothesized that early enzymes are more promiscuous than their extant orthologs. Whether or not this hypothesis applies to the translation machinery, the oldest molecular machine of life, is not known. Efficient protein synthesis relies on a cascade of specific interactions between the ribosome and the translation factors. Here, using elongation factor-Tu (EF-Tu) as a model system, we have explored the evolution of ribosome specificity in translation factors. Employing presteady state fast kinetics using quench flow, we have quantitatively characterized the specificity of two sequence-reconstructed 1.3- to 3.3-Gy-old ancestral EF-Tus toward two unrelated bacterial ribosomes, mesophilic Escherichia coli and thermophilic Thermus thermophilus. Although the modern EF-Tus show clear preference for their respective ribosomes, the ancestral EF-Tus show similar specificity for diverse ribosomes. In addition, despite increase in the catalytic activity with temperature, the ribosome specificity of the thermophilic EF-Tus remains virtually unchanged. Our kinetic analysis thus suggests that EF-Tu proteins likely evolved from the catalytically promiscuous, "generalist" ancestors. Furthermore, compatibility of diverse ribosomes with the modern and ancestral EF-Tus suggests that the ribosomal core probably evolved before the diversification of the EF-Tus. This study thus provides important insights regarding the evolution of modern translation machinery.