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Conductive metal-organic frameworks (MOFs) have received increasing attention in recent years and present high application potential as sensing elements in electronic sensors. In this study, flexible field-effect transistor (FET) sensors based on conductive MOF, i.e., Ni 3 (HHTP) 2 , have been constructed. This Ni 3 (HHTP) 2 sensor has high sensitivity (detection limit of 56 ppb) as well as superior selectivity for NO 2 detection at room temperature, which is demonstrated by accurate gas detection in a mixed gas atmosphere. Moreover, by employing six flexible substrates, i.e., polyimide (PI), tape (PET), facemask, paper cup, tablecloth, and take-out bag (textile), we successfully demonstrate the universality of the flexible sensor construction with conductive MOF as sensing film on various substrates. This study of conductive MOF-based flexible electronic sensors offers a new opportunity for a wide range of sensing applications with wearable and portable electronic devices.

Aging poses obstacles to the functionality of human mesenchymal stem cells (MSCs), resulting in a notable decline in their valuable contribution to myocardial infarction (MI). MicroRNAs (miRNAs) play a pivotal role in governing MSC aging; nonetheless, the specific mechanisms remain puzzling. This research delved into the value of miR-873-5p in the management of MSC aging and investigated whether the restraint of miR-873-5p could regenerate aged MSCs (AMSCs), thereby enhancing their healing success for MI. In this study, MSCs were isolated from both young donors (referred to as YMSCs) and aged donors (referred to as AMSCs). The senescence status of these MSCs was evaluated through the application of age-related β-galactosidase (SA-β-gal) staining. Following this assessment, the MSCs, including those treated with anti-miR-873-5p-AMSCs, were then transplanted into the hearts of Sprague-Dawley rats experiencing acute myocardial infarction. Increasing miR-873-5p levels in YMSCs resulted in elevated cellular aging, whereas reducing miR-873-5p expression decreased aging in AMSCs. Mechanistically, miR-873-5p inhibited autophagy in MSCs through the AMPK signaling pathway, leading to cellular aging by suppressing the Cab39 expression. Partial alleviation of these effects was achieved by the administration of the autophagy inhibitor 3-methyladenine. Grafting of anti-miR-873-5p-AMSCs, by enhancing angiogenesis and bolstering cell survival, led to an improvement in cardiac function in the rat model, unlike the transplantation of AMSCs. miR-873-5p which serves as a pivotal element in mediating MSC aging through its regulation of the Cab39/AMPK signaling pathway. It represents an innovative target for revitalizing AMSCs and enhancing their heart-protective abilities., Competing Interests: The authors declare no competing financial interest., (© 2024 American Chemical Society.)

Two-dimensional violet phosphorus (VP) has emerged as a new sensing material in various sensing applications due to its unique electrical properties and high stability among allotropes of phosphorus. Currently, the research of the VP-based analysis method is at the early stage. In this work, a VP nanosheet-based field-effect transistor (FET) sensor is reported for the detection of NO 2 and N 2 O gases with extraordinary sensing performance. This sensor can achieve excellent sensitivity of up to ∼50% current change/ppm and a low detection limit of 5.9 ppb and enables the NO 2 analysis in various mixed gases. Moreover, this sensor can effectively distinguish between NO 2 and N 2 O gases, which is a big challenge for current FET or chemiresistor gas sensors. The different sensing behaviors of the VP sensor to NO 2 and N 2 O gases have been investigated, and the mechanism study shows that the adsorption energy, bond length of the gas molecule on the VP surface, and the decomposition of N 2 O led to the differential responses. This work is one of the pioneer studies of VP gas sensors and presents a new sensing method for the discriminative analysis of NO 2 and N 2 O for greenhouse gas emission monitoring and air quality control.

MXenes have shown exceptional electrochemical properties and demonstrate great promise in chemiresistive gas analysis applications. However, their sensing applications still face low sensitivity and specificity, slow response, and poor stability among the many challenges. Herein, a novel synthetic approach is reported to produce single-atom Pt (Pt SA)-implanted Ti 3 C 2 T x MXene nanosheets as the sensing channel in field-effect transistor (FET) gas sensors. This is a pioneer study of single-atom catalysts loaded on MXene nanosheets for gas detection, which demonstrates that Pt SA can greatly enhance the sensing performance of pristine Ti 3 C 2 T x . The Pt SA-Ti 3 C 2 T x sensor exhibits high sensitivity and specificity toward ppb level (a low detection limit of 14 ppb) triethylamine (TEA) with good multicycle sensing performance. Moreover, the mechanism study and density functional theory (DFT) simulation show that the chemical sensitization effect and TEA adsorption enhancement from highly catalytic and uniformly distributed Pt SA lead to the enhanced sensing performances. This work presents a new prospect of single-atom catalysts for gas analysis applications, which will promote the development of cutting-edge sensing techniques for gas detection for public health and environment.

The nonradiative recombination between hole transport layers (HTLs) and perovskites generally leads to obvious energy losses. The trap states at the HTL/perovskite interface directly influence the improvement of the power conversion efficiency (PCE) and stability. Interface regulation is a simple and commonly used method to decrease nonradiative recombination in inverted perovskite solar cells (PSCs). Here, a wide-bandgap halide was used to regulate the PTAA/MAPbI 3 interface, in which n -hexyltrimethylammonium bromide (HTAB) was used to modify the upper surface of poly[bis(4-phenyl)-(2,4,6-trimethylphenyl)amine] (PTAA). Upon introduction of the HTAB layer, the contact between PTAA and MAPbI 3 is strengthened, the defect state density in PSCs is reduced, the MAPbI 3 crystallinity is improved, and the nonradiative recombination loss is suppressed. The device with HTAB delivers the highest PCE of 21.01% with negligible hysteresis, which is significantly higher than that of the control device (17.71%), and it maintains approximately 87% of its initial PCE for 1000 h without encapsulation in air with a relative humidity of 25 ± 5%. This work reveals an effective way of using a wide-bandgap halide to regulate the PTAA/MAPbI 3 interface to simultaneously promote the PCE and stability of PSCs.

Functional polymers of nylon-6, particularly those with sustained antibacterial functions, have many practical applications. However, the development of functional ε-caprolactam monomers for the subsequent ring-opening copolymerization (ROCOP) formation of these materials remains a challenge. Here we report a t -BuP 4 -mediated ROCOP of dimethyl-protected cyclic lysine with ε-caprolactam, followed by quaternization, affording antibacterial nylon-6 polymers bearing quaternary ammonium functionality with high molecular weight (up to 77.4 kDa). The antibacterial nylon-6 polymers exhibited good physical and mechanical properties and strong antimicrobial activities. At 25 mol % quaternary ammonium group incorporation, the nylon-6 polymer demonstrated complete killing of Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). The results from this study may provide a strategy for the facile preparation of antibacterial nylon-6 polymers to addressing the public health and safety challenges.

Silver (Ag) is a widely used heavy metal, and its oxidation state (Ag + ) causes serious harm to organisms after bioaccumulation and biomagnification, posing urgent demand for the rapid, efficient, and simply operated Ag + detection techniques. In this work, a fast, portable, and label-free Ag + detection sensor based on a Ti 3 C 2 T x MXene field-effect transistor (FET) is reported. The Ti 3 C 2 T x MXene works as the sensing element in the FET sensor, which shows excellent sensing performance, i.e., fast response (few seconds) and good sensitivity and selectivity to Ag + without any detection label or probe. Utilizing the visual photograph, transmission electron microscopy image, and Ag elemental mapping analysis, the sensing mechanism of the label-free Ti 3 C 2 T x MXene FET sensor is demonstrated to be the in situ reduction of Ag + and the formation of Ag nanoparticles (AgNPs). Moreover, Ag + detection in real samples shows that the proposed FET devices have satisfactory sensing capability for Ag + in tap water and river water. This study puts forward a novel FET strategy for Ag + detection in aqueous systems, which is of essential and inspiring meaning for motivating the potential applications of MXene-based sensor devices in analytical applications and the realization of on-site environmental monitoring.

Biphasic systems have received increasing attention for acid-catalyzed dehydration of hexoses to 5-hydroxymethylfurfural (HMF) because of their high efficiency in in situ extraction and stabilization of HMF. Different organic solvents and acid catalysts were applied in these systems, but their effects on the dehydration activity and HMF yield, and the recycling of homogeneous acid catalysts remain largely unexplored. Here, we tested different solvent systems containing a wide range of organic solvents with low boiling points to study the effects of their chemical structures on fructose dehydration and provided stable H 2 O-dioxane and H 2 O-acetonitrile biphasic systems with high HMF yields of 76-79% using water-soluble sulfonic derivatives as homogeneous acid catalysts under mild conditions (383 K). By analyzing the partition coefficients of HMF and sulfonic derivatives, 94.3% of HMF and 87.1% of NH 2 SO 3 H were, respectively, restrained in the dioxane phase and aqueous phase in the H 2 O-dioxane biphasic system and easily divided by phase separation. The effects of the adjacent group in sulfonic derivatives and reaction temperature on fructose conversions and HMF yields suggest that in a specific biphasic system, the catalysts' acidity and reaction conditions significantly affect the fructose dehydration activity but hardly influence the optimal yield of HMF, and an almost constant amount of carbon loss was observed mainly due to the poor hydrothermal stability of fructose. Such developments offer a promising strategy to address the challenge in the separation and recycling of homogeneous acid catalysts in the practical HMF production., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Monolayer MoS 2 (ML-MoS 2 ) with various polymorphic phases attracts growing interests for device applications in recent years. Herein, a field-effect transistor (FET) gas sensor is developed on the basis of monolayer MoS 2 with a heterophase of a 1T metallic phase and a 2H semiconducting phase. Lithium-exfoliated MoS 2 nanosheets own a monolayer structure with rich active sites for gas adsorption. With thermal annealing from 50 to 300 °C, the initial lithium-exfoliated 1T-phase MoS 2 gradually transforms into the 2H phase, during which the 1T and 2H heterophases can be modulated. The 1T/2H heterophase MoS 2 shows p-type semiconducting properties and prominent adsorption capability for NO 2 molecules. The highest response is observed for 100 °C annealed MoS 2 of a 40% 1T phase and a 60% 2H phase, which shows a sensitivity up to 25% toward 2 ppm NO 2 at room temperature in a very short time (10 s) and a lower limit of detection down to 25 ppb. This study demonstrates that the gas detection capability of ML-MoS 2 could be boosted with the heterophase construction, which brings new insights into transition-metal dichalcogenide gas sensors.

MXenes, a group of emerging two-dimensional (2D) transition metal carbides or nitrides, have attracted wide interest due to their unique structures and properties. Their stability and applicability in different media especially in an alkaline environment are directly associated with their potential applications and are not yet explored. Herein, a field-effect transistor (FET) is fabricated with single/double-layer Ti 3 C 2 T x MXene. The Ti 3 C 2 T x FET indicator shows a fast (∼1 s), sensitive, and selective response to alkali. Moreover, the device can work even in a high-salinity (2 M NaCl) environment, suggesting its high anti-interference ability for alkali in a high-ionic-strength environment. Using an in situ morphological image evolution study, it is demonstrated that the response signal results from alkali-induced denaturation of Ti 3 C 2 T x nanosheets. The Ti 3 C 2 T x -based alkali FET indicator and systematic evaluation on alkali-induced structure evolution of Ti 3 C 2 T x provide essential insights into MXene-based FETs and future applications of MXene in alkaline environments.

We devised iron-based catalysts with honeycomb-structured graphene (HSG) as the support and potassium as the promoter for CO 2 direct hydrogenation to light olefins (CO 2 -FTO). Over the optimal FeK1.5/HSG catalyst, the iron time yield of light olefins amounted to 73 μmol CO2 g Fe -1 s -1 with high selectivity of 59%. No obvious deactivation occurred within 120 h on stream. The excellent catalytic performance is attributed to the confinement effect of the porous HSG on the sintering of the active sites and the promotion effect of potassium on the activation of inert CO 2 and the formation of iron carbide active for CO 2 -FTO.

We demonstrate a one-pot hydrothermal cohydrolysis-carbonization process using glucose and iron nitrate as starting materials for the fabrication of carbonaceous spheres embedded with iron oxide nanoparticles. It is verified by TEM, (57)Fe Mossbauer, and Fe K-edge XAS that iron oxide nanoparticles are highly dispersed in the carbonaceous spheres, leading to a unique microstructure. A formation mechanism is also proposed. This route is also applicable to a range of other naturally occurring saccharides and metal nitrates. A catalytic study revealed the remarkable stability and selectivity of the reduced Fe(x)O(y)@C spheres in the Fischer-Tropsch synthesis, which clearly exemplifies the promising application of such materials.

The desulfurization of thiophene on Raney Ni and rapidly quenched skeletal Ni (RQ Ni) has been studied in ultrahigh vacuum (UHV) by X-ray photoelectron spectroscopy (XPS). The Raney Ni or RQ Ni can be approximated as a hydrogen-preadsorbed polycrystalline Ni-alumina composite. It is found that thiophene molecularly adsorbs on Raney Ni or RQ Ni at 103 K. At 173 K, thiophene on alumina is desorbed, while thiophene in direct contact with the metallic Ni in Raney Ni undergoes C-S bond scission, leading to carbonaceous species most probably in the metallocycle-like configuration and atomic sulfur. On RQ Ni, the temperature for thiophene dissociation is about 100 K higher than that on Raney Ni. The lower reactivity of RQ Ni toward thiophene is tentatively attributed to lattice expansion of Ni crystallites in RQ Ni due to rapid quenching. The existence of alumina and hydrogen may block the further cracking of the metallocycle-like species on Raney Ni and RQ Ni at higher temperatures, which has been the dominant reaction pathway on Ni single crystals. By 473 K, the C 1s peak has disappeared, leaving nickel sulfide on the surface.