N-Doped MXene Nanosheet Stacks

In article number 2305247, Soon-Yong Kwon, Jae-Woo Choi, and co-workers report an N-doped MXene nanosheet stack with exceptional oxidation stability using a high-energy ball-milling technique. This innovative method offers a novel and efficient solution for the stable incorporation of MXene nanosheets in aqueous environments, particularly showcasing its ability to energy-environmentally efficient way to recovery valuable metals from diverse electronic waste.

Bismuth-Based Semiconductors

Degradable bismuth semiconductor's properties are controlled by topological synthesis, which carries ivermectin under ultrasound and light action to produce reactive oxygen species (ROS) and heat, induce tumors to realize immunogenic cell death, and further activate T cells to achieve synergistic immunotherapy. More details can be found in article number 2304032 by Yuhao Li, Lulu Zheng, Yuqing Miao, Dawei Zhang, and co-workers.

Phase-Change Heterostructure Memory

In article number 2303659, Tae Geun Kim and co-workers present phase-change heterostructure (PCH) memory devices that control vertical atomic diffusion during operation. The device performance, such as power consumption and thermal stability, is determined by the choice of transition metal dichalcogenide-based confinement materials with different cohesive energies, providing valuable insights for the further engineering and design of PCH devices.

Halide Perovskite Single Crystals

In article number 2304900, Dong Zhang, Takuya Okamoto, and Vasudevanpillai Biju show size-controlled, monodisperse cubic halide perovskite crystal formation by thermodynamically controlling the nucleation-crystal growth kinetics in inverse temperature crystallization. The concentration of N-cyclohexyl-2-pyrrolidone and the nucleation-growth temperature play central roles in the shape and size of crystals. Controlled growth with the pyrrolidone derivative suppresses the defect density of the crystals, producing uniform samples for optoelectronic and photovoltaic applications.

This comprehensive review summarizes the engineering strategies of bacteria and their biotic components for oral delivery and their applications in the biomedicine, especially research progress in the treatment of gastric, intestinal, and respiratory diseases. Finally, this review highlights the current challenges and prospects of bacterial therapeutics that will contribute to the development of next-generation orally delivered bacteriotherapy.

Thermoelectric generators (TEGs), with the ability to continuously convert heat into electricity, is one of the most effective ways to realize heat recovery. This review provides a comprehensive overview of the practical applications of TEGs, mainly in wearable devices, devices for daily life and industry. Meanwhile, the combination of TEGs with other nanogenerators to form hybrid generators is systematically presented.

Recent advances based on metal-organic frameworks and their derivatives in different dimensionalities ranging from nanopowders to nanofilms and aerogels, as well as self-supporting electrodes for supercapacitors are summarized and highlighted. Furthermore, the key challenges and perspectives of metal-organic frameworks and their derivatives-based materials for the practical and sustainable electrochemical energy conversion and storage applications are briefly discussed.

In this review, typical structures and preparation methods of covalent organic framework (COFs) are introduced. Subsequently, the essential principles of photocatalytic reactions over COFs-based materials and the latest research developments in photocatalytic hydrogen production, CO₂ reduction, and pollutant elimination are discussed. Finally, challenges and prospects for COFs-based materials applied in photocatalysis are proposed.

The metal phosphorus chalcogenide (MPX₃), has garnered attention in the field of energy storage due to its exceptional electrochemical performance. With high electrical conductivity, relatively large surface area, superb stability, and exceptional energy storage capability, MPX₃ presents itself as a promising material. By employing appropriate regulation strategies, it can be applied to energy storage devices such as alkali metal ion batteries, metal-air batteries, and solid-state batteries.

Iridium (Ir)-based materials are one of the few catalysts that can have good oxygen evolution reaction (OER) performance under acidic conditions. Here, this progress report emphasizes the importance of two-dimensional (2D) Ir-based catalysts and significant research progress in designing and synthesizing various electrocatalysts to improve acidic OER performance. Finally, the prospects and challenges of developing 2D Ir-based catalysts are discussed.

This review provides a summary of the synthesis methods and mechanisms of lignocellulosic biomass based-CDs (LC-CDs). It also covers LC-CDs' properties and advancements in various fields, including optics, energy, and biomedicine. The challenges associated with the development of LC-CDs and their potential advanced applications are also discussed, which is aimed to inspire ongoing research.

This review focuses on hydrogel electrolytes engineering for high-performance flexible aqueous zinc ion energy storage systems. From basic characteristics, anode and cathode stabilization effects, and functional properties, the corresponding mechanisms of designing desirable hydrogel electrolytes are elaborated. The application of flexible aqueous zinc ion energy storage systems in wearable electronics is also depicted with a bright future.

The most current scientific developments, difficulties, and potential applications of single-atom catalysts (SACs) in photocatalytic CO₂ reduction are outlined. In this review, the effects of support materials and active site types in SACs on the efficiency of photocatalytic CO₂ reduction are evaluated and investigated. On the development of SACs for photocatalytic CO₂ reduction, several individual opinions are presented.

Positron Emission Tomography

Polyplex nanoparticles are prepared by complexation of siRNA and polyamines aimed at gene therapy applications for cancer treatment. The radiolabeled polyplexes are injected intratumorally in lung tumor tissue, resulting in a high retention of the nanoparticles in the malignant tissue. More details can be found in article number 2304326 by Jordi Llop, Sergio E. Moya, and co-workers.

Positron emission tomography is used to study the fate of polyplexes formed by siRNA and modified polyamines. Polyplexes are prepared with either radiolabeled siRNA or radiolabeled polyamines. By comparing biodistribution patterns of labeled siRNA and labeled polyamines conclusions are driven on the stability of the polyplexes in vivo.

Magnetic Resonance Imaging

The frontispiece represents a reticular chemistry approach to optimize relaxation transfer in the inner-, second- and outer-sphere of the metal cluster underlying the fcu-type metal–organic framework (MOF) for T₁-weighted magnetic resonance imaging and indicates that the metal cluster arranged in the fcu-type MOF matrix surpasses its discrete molecular cluster for in-vitro and in-vivo magnetic resonance imaging (MRI). More details can be found in article number 2303063 by Yun Ling and co-workers.

It is not only shown the reticular chemistry approach to optimize relaxation transfer in the inner-, second- and outer-sphere of Gd(III)-doped Zr-oxo cluster underlying the fcu-type metal–organic framework (MOF) for T₁-weighted magnetic resonance imaging but also confirmed that the Gd(III)-doped cluster aggregated in the MOF matrix surpasses its discrete molecular cluster for in vitro and in vivo T₁-weighted magnetic resonance imaging (MRI).

NO₂ Sensors

In article number 2303631, Wen Zeng, Zaihua Duan, Huiling Tai, and co-workers propose an enhanced gas sensing strategy based on the synergistic effect of electron scattering and space charge transfer, and verify it by designing porous SnO₂ nanoparticles assembled from ultra-small grains, achieving unprecedented NO₂ gas sensing performance at room temperature. This work provides an innovative approach for developing high-performance and low-power gas sensors.

To develop the room temperature NO₂ sensor with high response, fast recovery, and exceptional selectivity, porous SnO₂ nanoparticles with rich oxygen vacancies are synthesized via acetylacetone-assisted solvent evaporation followed by N₂ and air calcinations. The fascinating sensing properties are mainly attributed to the unique synergistic effect of electron scattering and space charge transfer.

We describe an N-doped MXene nanosheet stack produced by a high-energy planetary ball milling under N₂-purged conditions. This process effectively stabilizes defective vacancies of MXene nanosheets while forming a macroscale MXene nanosheet stack, making it easy to recover after use in the aqueous environments. MXene nanosheet stack shows its long-term storability, selective and efficient precious metal recovery capability, and reusability.

A bismuth-based nano-semiconductor is constructed by topology synthesis strategy and loaded with ivermectin to form a sono/photo-activated bismuth nanoagonist for realizing immunogenic cell death (ICD)-mediated tumor synergistic therapy. The proposed hyperthermia/sonocatalytic therapy strategy will pay the way for the synergetic enhancement of tumor treatment efficacy and provide a feasible idea for controllable induction of ICD.

To prevent long-range atomic diffusion in phase change materials (PCMs– Sb₂Te₃), transition metal dichalcogenide-based confinement materials (TiTe₂, NiTe₂, and MoTe2) are inserted between PCMs to fabricate phase change heterostructure memory devices. The device performance is then investigated with each other and analysed based on their different electrical resistivity and cohesive energy.

Halide perovskite) single crystals are promising for electro-optical and photovoltaic devices. The challenging size- and shape-controlled single-crystal synthesis is demonstrated by separating and optimizing the crystal nucleation-growth processe . The cuboid single-crystals with controlled size show optimal photoluminescence and minimal defects. This method offers a route to synthesize high-quality perovskite single crystals with size- and shape-control for devices.

Novel graphitic-carbon nitride/carbon (g-C₃N₄/C) composites are synthesized by one-step thermal polycondensation. The starting materials are potassium hydroxide (KOH), microplastics, and melamine mixture in air atmosphere. Under visible-light irradiation, hydrogen peroxide (H₂O₂) production-rate over CN-K5M7 reaches 6.14 mmol g-1h-1, while H₂O₂ selectivity is 99.5%. The KOH modification creates a large number of N vacancies and defects caused by cyano-groups in g-C₃N₄.

The temperature effects on electrode materials are fully revealed through intensively investigating a novel yttrium niobate (Y_0.5Nb_24.5O₆₂) model material with a large interlayer spacing and porous-microspherical morphology. It is found that the operation temperature plays vital roles in electrolyte decomposition on electrode-material surfaces (initial Coulombic efficiency), electrochemical kinetics (reversible capacity, rate capability, and working potential), and crystal-structure evolution (cyclic stability).

A three-dimensional (3D) cylindrical opened-porous aerogel is fabricated via a Pickering emulsion-mediated polymerization route. All-cold solar evaporation with zero energy loss and significantly increased extra energy harvest is achieved. Vapor diffusion is enhanced, and inner evaporation surfaces are activated via external convective flow. The evaporator can deliver stable vapor generation for highly concentrated salt solution (20 wt.% NaCl).

Tin phosphide/phosphate nanoparticles uniformly distributed within thecarbon nanofiber matrix have been designed by electrospinning with carbothermal reduction of phosphate-containing precursors. Designed material of unique nanostructure and composition exhibits outstanding electrochemical properties at low temperatures as an anode for lithium-ion batteries, retaining 580 mAh g⁻¹ capacity after 100 cycles at −20 °C using commercial electrolyte without any additives.

An open-mouthed hollow cobalt/nitrogen-doped carbon with mesoporous shells (OMH-Co/NC) is synthesized using the self-conglobation effect of metal sulfate in methanol, followed by pyrolysis. The incorporation of open holes in the structure enhances the accessibility of both the inner and outer surfaces. As a result, the OMH-Co/NC exhibits superior activity in the oxygen reduction reaction (ORR) and improve mass transfer efficiency.

A dry-spinning strategy is proposed to fabricate flexible MXene fibers (MFs) for wearable supercapacitors by engineering the rheological behavior of Ti₃C₂T_x sediment. The parameters affecting the dry spinning process, the mechanical and electrochemical properties of the as-prepared MFs are studied in detail.

A hybrid MOF-on-MOF heterostructure is first reported for the rapid detection and selective capture of gold. Due to the strong interaction between the framework and Au³⁺, an ultra-fast fluorescence response time (3.6s) and ultra-high adsorption capacity (1575 mg g⁻¹) are observed on MOF-808@ZIF-90-XE.

This study designs a programmable protein imprinted nanosphere by dynamically reversible cross-linking/de-cross-linking of the temperature- and pH-responsive polymeric surface under different wavelengths of UV light. The nanosphere can be repeatedly programmed toward a variety of proteins, thereby achieving the selective separation of different proteins from real biological samples in sequential.

The ν −ν^1/2 model and the b-value, widely used in energy storage literature, have serious shortcomings: the latter is highly subjective, while the former assumes a linear response which is often not present. Consequently, electrodes are frequently wrongly evaluated, and the deconvoluted capacitive and diffusive contributions are often in error. The corrected model proposed here seeks to remedy this state of affairs.

CoFe₂O₄@carbon@alkalized MXene composite shows high-rate performance of 318 mAh g⁻¹ at 10 A g⁻¹ for LIBs and 149 mAh g⁻¹ at 5 A g⁻¹ for SIBs. The excellent cycling performance is 807 mAh g⁻¹ at 2 A g⁻¹ after 400 cycles for LIBs and 130 mAh g⁻¹ at 1 A g⁻¹ even after 1000 cycles for SIBs.

Interlayer twist can manipulate phonon coherence in the 2D bilayers. Through extensive simulations and analysis, the distinctive phonon properties of twisted anharmonic sheets are demonstrated, particularly the pronounced response of phonon coherence to twisting in penta-NiN₂ bilayers. These findings highlight the potential applications of 2D twisted systems in phonon-based devices.

The compact micron-sized Si@G/CNF@NC composite features a tightly bonded and dual encapsulated structure, which endows it with excellent conductivity and deformation resistance, demonstrating a range of comprehensive advantages in lithium-ion batteries, including high tap density, high mass loading, outstanding areal capacity, and excellent gravimetric and volumetric energy density.

Co-induced engineering is proposed to enhance electron conduction and ion diffusion of MoSe₂ nanosheets anchored on reduced graphene oxide. The as-prepared Co-MoSe₂/reduced graphene oxide (rGO) anode possesses remarkable reversible capacity, superior rate capability, and stable long-term cyclability for potassium-ion batteries, as well as high energy/power density for potassium-ion hybrid capacitors.

This work creatively proposes to prepare industrial-grade catalytic electrodes with high efficiency and stability at high current density through carbon quantum dots (CDs) modification nickel sulfide on hydrophilic flexible filter paper via one-step mild chemical plating (denoted as CDs-Ni₃S₂@HFP), which achieves over 500 h for efficient and stable catalysis at industrial high current density (500 mA cm⁻²) in 1 m KOH, simulated seawater (1 m KOH + 0.5 m NaCl), and neutral electrolyte (0.5 m PBS).

The micro/nanostructured SiO_xC_y composites are synthesized by chemical vapor deposition strategy. The SiO_xC_y composites are not only capable of being used in lithium-ion battery anodes, but can also be employed as a substrate for lithium metal uniform deposition in Li metal anode. This work provides a new perspective for the simultaneous development of practical SiO_xC_y and dendrite-free lithium metal anodes.

A solar-triggered monolithic adsorbent is constructed from hydrophilic bimetallic metal-organic framework (BMOF) skeletons and photothermal layers on a glass fiber support to generate safe freshwater from atmospheric air. The open hybridized BMOF skeleton can efficiently capture and store moisture during the night. The polymeric photothermal layer relies on its high photothermal conversion capacity in sunlight to automatically release the adsorbed water.

The construction of 3D Co/C foam and its surface decoration with carbon microspheres are synchronously achieved by a “win–win” strategy. Both Co nanoparticles and carbon microspheres display good dispersity, which improves the graphitization degree of carbon framework and creates abundant heterogeneous interfaces. As a result, the Co/C foam decorated with carbon microspheres gains enhanced dielectric property and microwave absorption performance.

A feasible method is reported to synthesize ambient-stable molybdenum disulfide (MoS₂) with high concentration 1T phase under low magnetic fields. Owing to the synergistic effect of magnetic free energy and microstrain, the 1T phase proportion can be as high as 80% and the synthesized MoS₂ is ambient-stable for more than one year with excellent hydrogen evolution reaction（HER）performances.

Hollow nano-cage layered CoNi double hydroxides (CoNi-LDH) were obtained by Ni ion etching of ZIF-67 (Zeolitic imidazolate framework-67). By adjusting the amount of terephthalic acid, the intercalated CoNi-LDH-2 (with 0.02 mmol terephthalic acid intercalated) was not easy to collapse after 209 cycles and showed the best electrochemical performance in Li–O₂ battery.

Micro-hotplate structures composed of boron-doped polycrystalline diamond are fabricated and comprehensively characterized. Through constructing the devices from a single layer of low coefficient of thermal expansion diamond, stress issues that plague traditional multi-layered structures are averted, allowing the resulting devices to operate up to 2731 K and far beyond the current 1600 K limit of conventional structures.

A hierarchical 3D electrode design with high mass loading enables the realization of high-energy-density flexible batteries. The electrode demonstrates outstanding mechanical flexibility, while the bicontinuous network facilitates efficient Li-ion conduction, resulting in enhanced cycle stability and rate performance. As a result, the hierarchical 3D electrode allows to achieve high-energy-density of flexible LIBs in a pouch-type cell (438.6 Wh kg⁻¹/20.4 mWh cm⁻²).

Here, the study describes an easy-to-execute strategy to fabricate magnetic heterostructure as a multifunctional delivery system. first-row transition metal copper and nitroso/amino ligand as modules to assemble around Fe₃O₄ magnetic nanoparticles by excessed mild stimuli and fabricate the magnetic heterostructure materials is utilized. The Fe₃O₄@ TACN NPs can effectively isolate Cyt-c from complex biological samples (pork heart). Importantly, the Fe₃O₄@ TACN NPs coordinated with heme-structure, induced methionine 80 disassociates from heme prosthetic group, and contributed to peroxidase-like activities increasing.

Benefiting from the spherical yolk–shell structure of Ti–doped SiO₂@Al₂O₃ (ST@Al₂O₃), Li⁺ can diffuse through the porous shell and hollow interior. Moreover, Lewis acid sites may reduce the solvation effect of Li⁺, and the bilayer shell with abundant Lewis acid sites can effectively trap anions by charge attraction, thus creating an anion shield.

Covalent organic frameworks (o-COF) for indoor humidity regulation  was constructed by adjusting the difference of water adsorption sites in positional isomers. o-COF exhibits a steep adsorption isotherm in the range of 45–65% RH with a suitable hysteresis range. Both laboratory experiment and real environment experiment confirm that o-COF is a new generation of indoor humidity regulation material.

A uniform Pt/Nb₁₄W₃O₄₄ catalyst with crystallographic shear structure is developed for the extremely efficient and selective hydrogenolysis of glycerol to 1,3-propanedio with excellent stability, reaching an exceptional 75.2% yield of 1,3-propanediol. Strong interaction between Nb₁₄W₃O₄₄ and Pt can coordinate the precise adsorption and activation of the secondary C─O bond, simultaneously triggering subsequent hydrogenation.

A sacrificial bimetallic pyrolysis strategy is applied to synthesize a Fe/N/C catalyst with excellent oxygen reduction reaction performances in acidic media. As a result, the Fe(Cd)─N─C catalyst performs with ≈8 higher site utilization efficiency than the Fe─N─C catalyst, which is also higher than most Fe/N/C catalysts prepared by wet-chemistry synthesis methods.

Three photoactive metal–organic framework systems having two different photoinduced electron transfer (PET) processes to drive photocatalytic H₂ production are reported, wherein, Co^II(bpy)₃@Zn-PDTP system using [Co(bpy)₃]Cl₂ as a cocatalyst with the intermolecular PET process extremely enhances the photocatalytic activity to 7.5 and 9.3 times the value afforded by Co^II-Zn-PDTP system and bare Co-PDTP, respectively.

Preparing MoS₂-based materials with reasonable structure and catalytic activity to enhance the lithium polysulfides conversion is significant for Li–S batteries (LSBs) but still faces challenges. Hence, hollow nanotubes composing N-doped MoS₂ nanosheets (N-MoS₂ NHTs) are fabricated as cathode for LSBs by using CdS nanorods as a sacrifice template, and the batteries with the N-MoS₂ NHTs cathode show excellent performance.

The innate immunological response of framework nucleic acids (FNAs) is primarily dependent on both dose and morphology. A low-dose FNA with minimal immune activation and higher cellular uptake is recommended as a carrier for biomolecule delivery. Moreover, the immune activity of cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) can be programmed through FNA-mediated spatial distance, which can be tuned by morphology.

This study presents a simple yet powerful approach, multi-frequency vibration cutting, to enable the high-efficiency fabrication of optical Fourier surfaces. Due to the capacity of multicomponent gratings in coupling red, green, and blue lights, the RGB true color is prepared on the metallic surface. The additive and subtractive principles of mixing the three primary colors are demonstrated.

A machine learning-based approach is demonstrated for prediction of the specific absorption rate for hyperthermia and r₁/r₂ relaxivities in magnetic resonance imagining (MRI), with descriptors including parameters of nanoparticles and experimental conditions. DiMag, an open access resource, is developed to guide the synthesis of novel nanosized magnets for MRI and hyperthermia treatment to boost the development of new biomedical agents.

An asymmetric bacterial cellulose membrane is fabricated through microbial fermentation, serving as the foundation for the development of multifunctional wound dressings. The wound dressing can provide an ideal moist environment for wound healing and inhibit the growth of bacteria on infected wounds while releasing Cur in a controlled manner, scavenging ROS, and promoting the production of epithelium and granulation.

Polypyrrole is used as an electrochemically active additive to introduce hollow channels into polyacrylonitrile nanotubes, creating a free-standing Li-S cathode based on solid-phase conversion. This not only increases the sulfur loading but also significantly enhances charge transport. Consequently, the charge-transfer kinetics and interfacial compatibility are significantly enhanced for superior electrochemical properties.

A nanoparticles based benzoxazine containing a Si─O─Ti bond photocatalyst is developed for photocatalytic preparation of H₂O₂. Compared to traditional nanocatalysts for catalytic preparation of H₂O₂, the photocatalyst exhibits superior photocatalytic efficiency and excellent hydrolysis resistance, enabling its repeated use with minimal loss.

Charge transfer kinetics is discussed in −C=N− linked COFs, with high ΔkCT CR. Low ΔkCT CR is obtained for additional −N=N− linkage case, since it acts as electron trapping centers for inefficient charge transfer process. The ΔkCT CR value can be one important indicator for photocatalysts design at a molecular level.

Single-crystal truncated octahedral LiMn₂O₄ with exposed {111}, {100}, and {110} facets is proposed to decelerate the disproportionation and Jahn–Teller distortion for advanced lithium-ion batteries. The cycling stability of spinel LiMn₂O₄ cathode is remarkably enhanced, obtaining an outstanding capacity retention of 84.3% after 2000 cycles.

Polyoxometalates@Metal-Organic frameworks derived bimetallic cobalt clusters with Mo₂C nanostructures embedded in carbon nanotubes interlaced layered porous carbon (Co/Mo₂C@NCNHP) not only can effectively promote the electron transport within the cathode and confine the shuttle effect of aluminum polysulfides (AlPSs) by physical confinement and chemical adsorption, but also can catalyze the reversible kinetics of aluminum polysulfide conversion in Al–S battery (ASB).

A hollow hierarchical porous ZIF8@FePMPDA-920 catalyst with unique asymmetric Fe-N₄-OH moieties is constructed via a combined approach following the order of polymer coating, electrostatic absorption, and pyrolysis, showing superior oxygen reduction reaction and oxygen evolution reaction activities. The homemade liquid and flexible solid-state zinc-air batteries demonstrate excellent performance in terms of desirable open-circuit voltage, discharging specific capacity, and long-term durability.

Surface-enhanced Raman spectroscopy (SERS) sensing of dopamine down to nm concentration is demonstrated using self-assembled monolayers of plasmonic Au nanoparticles sensitized with Fe(III) for multiplicative SERS enhancement. Since they are deposited onto glass, this configuration allows for double-sided access, enabling simultaneous flow and optical sensing. The repeated reusability after analyte sensing is demonstrated through oxygen plasma cleaning protocols.

The orthopedic GMOS/K@M adhesive excels in splicing fracture fragments and facilitating osteoporotic fracture fixation using a non-invasive approach. GMOS/K@M adhesive, doped with mesoporous bioactive glass nanoparticles (MBGNs) and loaded with kaempferol, effectively treats osteoporotic fractures in a closed-loop management by restoring bone homeostasis through pro-osteogenic and anti-osteoclastic effects.

A biosynthesized protein-based material is fabricated by non-pathogenic Escherichia coli (E. coli). The self-assembled nanoparticles of P1 could transform into nanofibers in situ, which could lead to efficient anticancer activity. Furthermore, a spatiotemporally controllable anticancer system is constructed by coating P1-expressing E. coli with cationic conjugated polyelectrolytes to release the peptides in situ under light irradiation.

The activity of iron diselenide for the oxygen evolution reaction (OER) is significantly enhanced by the synergistic effect of surface reconstruction and electronic structure regulation, which is achieved through P doping and the induction of Se vacancies.

MW-CNTs cathodes demonstrate unique structures, superior hydrophobicity, and uniform electronic conductibility, thus benefit the gas–liquid–solid three-phase reaction interfaces in the non-alkaline electrolyte. And as a result, the non-alkaline zinc-air batteries using MW-CNTs cathodes display a high specific capacity with high zinc utilization ratio, superior rate performance, excellent cycling stability, and negligible self-discharge.