A multifunctional copper single-atom electrocatalyst aerogel for smart sensing and producing ammonia from nitrate.

Despite modern chemistry's success in providing affordable fertilizers for feeding the population and supporting the ammonia industry, ineffective nitrogen management has led to pollution of water resources and air, contributing to climate change. Here, we report a multifunctional copper single-atom electrocatalyst-based aerogel (Cu SAA) that integrates the multiscale structure of coordinated single-atomic sites and 3D channel frameworks. The Cu SAA demonstrates an impressive faradaic efficiency of 87% for NH3 synthesis, as well as remarkable sensing performance with detection limits of 0.15 ppm for NO3- and 1.19 ppm for NH4+. These multifunctional features enable precise control and conversion of nitrate to ammonia in the catalytic process, facilitating accurate regulation of the ammonium and nitrate ratios in fertilizers. We thus designed the Cu SAA into a smart and sustainable fertilizing system (SSFS), a prototype device for on-site automatic recycling of nutrients with precisely controlled nitrate/ammonium concentrations. The SSFS represents a forward step toward sustainable nutrient/waste recycling, thus permitting efficient nitrogen utilization of crops and mitigating pollutant emissions. This contribution exemplifies how electrocatalysis and nanotechnology can be potentially leveraged to enable sustainable agriculture.

Thermal Transport Properties of Two-Dimensional Janus MoXSiN2 (X = S, Se, and Te).

The design of Janus materials offers an effective means of regulating both their physical and chemical properties, leading to their application in various fields. However, the underlying mechanism governing the modulation of the thermal transport characteristics through the construction of Janus materials remains unclear. In this work, we introduce VI-group elements into the MoSi2N4 structure, yielding two-dimensional Janus MoXSiN2 (X = S, Se, and Te) and systematically investigate their thermal transport properties based on first-principles calculation methods. Our findings reveal that the lattice thermal conductivities (κl) of MoSSiN2, MoSeSiN2, and MoTeSiN2 are 47.2, 24.3, and 40.6 W/mK at 300 K, respectively, significantly lower than that of MoSi2N4 (224 W/mK). Such low κl values mainly come from the introduction of X atoms, which enhances phonon scattering and reduces phonon vibration frequencies. In addition, MoTeSiN2 exhibits a higher κl compared to MoSeSiN2, contrary to the trend observed in most materials containing VI-group elements, where κl decreases gradually from S to Te. This anomalous behavior can be attributed to the competitive result between its lower phonon vibrational frequency and weaker phonon anharmonicity of MoTeSiN2. This work elucidates the inherent mechanism governing the modulation of thermal transport properties in Janus materials, thereby enhancing the potential application of Janus MoXSiN2 in engineering thermal management.

Effect of atomic substitution and structure on thermal conductivity in monolayers H-MN and T-MN (M = B, Al, Ga).

Finding materials with suitable thermal conductivity (κ) is crucial for improving energy efficiency, reducing carbon emissions, and achieving sustainability. Atomic substitution and structural adjustments are commonly used methods. By comparing the κ of two different structures of two-dimensional (2D) IIIA-nitrides and their corresponding carbides, we explored whether atomic substitution has the same impact on κ in different structures. All eight materials exhibit normal temperature dependence, with κ decreasing as the temperature rises. Both structures are single atomic layers of 2D materials, forming M-N bonds, with the difference being that H-MN consists of hexagonal rings, while T-MN consists of tetragonal and octagonal rings. 2D IIIA-nitrides provide a good illustration of the impact of atomic substitution and structure on κ. On a logarithmic scale of κ, it approximates two parallel lines, indicating that different structures exhibit similar trends of κ reduction under the same conditions of atomic substitution. We analyzed the mechanisms behind the decreasing trend in κ from a phonon mode perspective. The main reason for the decrease in κ is that heavier atoms lower lattice vibrations, reducing phonon frequencies. Electronegativity increases, altering bonding characteristics and increasing anharmonicity. Reduced symmetry in complex structures decreases phonon group velocities and enhances phonon anharmonicity, leading to decreased phonon lifetimes. It's noteworthy that we found that atomic substitution and structure significantly affect hydrodynamic phonon transport as well. Both complex structures and atomic substitution simultaneously reduce the effects of hydrodynamic phonon transport. By comparing the impact of κ on two different structures of 2D IIIA-nitrides and their corresponding carbides, we have deepened our understanding of phonon transport in 2D materials. Heavier atomic substitution and more complex structures result in reduced κ and decreased hydrodynamic phonon transport effects. This research is likely to have a significant impact on the study of micro- and nanoscale heat transfer, including the design of materials with specific heat transfer properties for future applications.

Hollow CoZnSe@CN nanocage with enzymatic activity for determination of tetracycline using smartphone platforms and virtual reality revealing.

Antibiotic residues in the environment pose a serious threat to ecosystems and human health. Therefore, it is important to develop sensitive and rapid in situ detection methods. In this work, the designed nanozymes, with excellent four enzyme activities, were proved to be constituted of unique hollow nanocage structures (CoZnSe@CN HCs). Based on the peroxidase-like enzymes, a portable colorimetric sensor was constructed for the on-site determination of tetracycline (TC) in real samples. The linear range of TC detection was 0.1-100 µM, and the detection limit was 0.02 µM. At the same time, colorimetric detection and smartphones have also been combined for on-site colorimetric detection of TC. In-depth exploration of the detection mechanism showed that TC could be bound with the material, inhibiting the production of oxidized 3,3',5,5'-tetramethylbenzidine. The sensor was also used for the detection of TC in environmental soil and water samples. This study can provide an intelligent detection method for environmental monitoring.

Robust, Healable, Self-Locomotive Integrated Robots Enabled by Noncovalent Assembled Gradient Nanostructure.

Integration, being lightweight, and intelligence are important orientations for the future advancement of soft robots. However, existing soft robots are generally hydrogels or silicone rubber, which are inherently mechanically inferior and easily damaged and difficult to integrate functions. Here, inspired by nacre, an elastomer actuator with sulfonated graphene-based gradient nanostructures is constructed via supramolecular multiscale assembly. The resulting nanocomposite possesses an ultrahigh toughness of 141.19 MJ/m3 and high room-temperature self-healing efficiency (89%). The proof-of-concept robot is demonstrated to emphasize its maximum swimming speed of 2.67 body length per second, whose speed is comparable to that of plankton, representing the outperformance of most artificial soft robots. Furthermore, the robot can stably absorb pollutants and recover its robustness and functionality even when damaged. This study breaks the mutual exclusivity of functional execution and fast locomotions, and we anticipate that our nanostructural design will offer an effective extended path to other integrated robots that required multifunction integration.

Ultrarobust Photothermal Materials via Dynamic Crosslinking for Solar Harvesting.

Highly efficient and mechanically durable photothermal materials are urgently needed for solar harvesting, but their development still remains challenging. Here, inspired by the hierarchically oriented architecture of natural spider silk, an ultrarobust liquid metals (LMs)/polymer composite is presented via dynamic crosslinking based on the unique mechanical deformable characteristic of LMs. Dynamically cross-linked core-shell structured LMs droplets can be squeezed along with the orientational crystallization of polymer chains during drawing, thus enabling LMs nanoparticles to be uniformly programmed in the rigid polyethylene nanofiber skeleton. The resultant composite exhibits an unprecedented combination of strong broad-band light absorption (96.9-99.3%), excellent photothermal conversion ability, remarkable mechanical property (tensile strength of 283.7 MPa, which can lift 200 000 times its own weight), and long-term structural reliability (bearing 100 000 bending cycles). A powerful and durable solar thermoelectric generator system for real-environmental solar-heat-electricity conversion is further demonstrated, providing a valuable guidance for the design and fabrication of high-performance solar-harvesting materials.

Mechano-Regulable and Healable Silk-Based Materials for Adaptive Applications.

Mechanically adaptive materials responsive to environmental stimuli through changing mechanical properties are highly attractive in intelligent devices. However, it is hard to regulate the mechanical properties of most mechanically adaptive materials in a facile way. Moreover, it remains a challenge to achieve mechano-regulable materials with mechanical properties ranging from high strength to extreme toughness. Here, inspired by the reversible nanofibril network structure of skeletal muscle to achieve muscle strength regulation, we present a mechano-regulable biopolymeric silk fibroin (SF) composite through regulating dynamic metal-ligand coordination bonds by using water molecules as competitive regulators. Efficient interfacial hydrogen bonds between tannic acid-tungsten disulfide nanohybrids and the SF matrix endow the composite with high mechanical strength and self-healing ability. The resulting composite exhibits 837-fold change in Young's modulus (5.77 ± 0.61 GPa to 6.89 ± 0.64 MPa) after water vapor triggering, high mechanical properties (72.5 ± 6.3 MPa), and excellent self-healing efficiency (nearly 100%). The proof-of-concept ultraconformable iontronic skin and smart actuators are demonstrated, thereby providing a direction for future self-adaptive smart device applications.

Difference in the micro-dynamics mechanism between aromatic nylon and aliphatic nylon during water absorption: spectroscopic evidence.

The difference in the micro-dynamics mechanism between aromatic nylon and aliphatic nylon during water absorption was studied to explore the reason for the significantly smaller decline of barrier performance of poly(m-xylene adipamide) (MXD6) film than that of polyamide 6 (PA6) film under high humidity. Attenuated total reflection (ATR) FTIR, combined with scaling moving-window 2D correlation spectroscopy (scaling-MW2D) and generalized 2D correlation analysis, was used. The scaling-MW2D confirmed that the water absorption of MXD6 comprises two processes, designated process I (2.0-12.0 min) and process II (12.0-27.0 min). According to the sequential order of the functional groups' movement obtained from the generalized 2D correlation analysis, processes I and II undergo three and two steps, respectively. Process I is the process of water plasticizing MXD6, which primarily consists of hydrophilic groups forming hydrogen bonds with water molecules and the hydration of hydrophobic groups. Process II is the strong crystallization of MXD6 induced by water molecules, entailing the generation of the double hydrogen bond and the rearrangement of hydrophilic groups into the crystal lattice. However, for PA6, the results confirmed that its water absorption only had a single process with two steps, which was actually the plasticization of PA6 macromolecular chains by water molecules. Therefore, the reason for the barrier performance decline of the MXD6 film being significantly smaller than that of the PA6 film is that water molecules induced a large amount of new crystalline regions in the MXD6 matrix during plasticization.

Exploration of the unusual two-step volume phase transition of the poly(N-vinylcaprolactam-co-hydroxyethyl methacrylate) hydrogel.

It is important to investigate the phase transition mechanism of stimuli-sensitive hydrogels due to its great guiding significance for the application of stimuli-sensitive hydrogels in biomedical applications. In this work, the novel thermo-sensitive poly(N-vinylcaprolactam-co-hydroxyethyl methacrylate) (PVCL-co-HEMA) hydrogel was successfully synthesized via free radical polymerization, and then temperature-dependent FTIR spectra combined with the newly developed scaling moving-window two-dimensional (scaling-MW2D) correlation spectroscopy and generalized two-dimensional correlation analysis were utilized to investigate its volume phase transition (VPT) mechanism upon heating. Conventional 1D FTIR spectra and Boltzmann fitting results revealed that the PVCL-co-HEMA hydrogel exhibited a distinct VPT behavior from the neat PVCL hydrogel due to the incorporation of PHEMA. The essential reason is that some water molecules were still confined in the PVCL-co-HEMA network after phase transition at high temperature, rather than continuously being expelled out of the gel with the increase of temperature. Scaling-MW2D spectra revealed that the phase transition of the PVCL-co-HEMA hydrogel could be divided into two steps (I and II), and further confirmed that the transition regions of these two steps were 25.0-32.3 °C and 32.3-46.8 °C, respectively. The transition regions of both these steps were obviously lower than those of the neat PVCL hydrogel. According to the generalized 2D correlation analysis of step I, we concluded that the dissociation of the hydrogen bonds between the incorporated PHEMA moieties and water molecules is the driving force for the local hydrophobic domain formation process (step I), and its occurrence at a lower temperature is the main reason for the decrease of the VPTT of the PVCL segments. Furthermore, we found that the dissociation of the hydrogen bonds between the C[double bond, length as m-dash]OVCL groups and water molecules is the driving force for the chain collapse (step II), and the driving effect of the PVCL segments on PHEMA during the phase transition was confirmed. Combined with the obtained sequential order of steps I and II, an unusual two-step VPT mechanism for the PVCL-co-HEMA hydrogel upon heating was proposed.

Two-step volume phase transition mechanism of poly(N-vinylcaprolactam) hydrogel online-tracked by two-dimensional correlation spectroscopy.

In this study, temperature-dependent FTIR spectroscopy in combination with the perturbation-correlation moving-window (PCMW2D) technique and generalized two-dimensional (2D) correlation analysis was applied to investigate the phase transition mechanism of poly(N-vinylcaprolactam) (PVCL) hydrogel upon heating. In the conventional 1D FTIR spectra, the gradual dehydration of C-H groups, as well as the gradual dissociation of hydrogen bonds between C[double bond, length as m-dash]O groups and water molecules, was observed during phase transition. Moreover, we found that the rate at which water molecules were expelled out of the gel network during phase transition was changed to a sigmoid mode, rather than increasing linearly with increasing temperature. PCMW2D FTIR spectra revealed that the phase transition of PVCL hydrogel can be divided into two steps (named as I and II) upon heating, and we further determined the temperature regions of steps I and II to be 29.0-35.7 °C and 35.7-47.5 °C, respectively. Step I is the formation of hydrophobic domains in the gel, and step II is the chain collapse of the gel. Finally, with the help of generalized 2D correlation analysis, it was confirmed that the transformation of hydrogen bonds was the driving force of the hydrophobic domain formation process, while the hydrophobic interaction of C-H groups was the driving force for the chain collapse process. Combined with the obtained sequential orders of step I and step II, an integrated two-step phase transition mechanism of PVCL hydrogel upon heating was proposed.

Microdynamics mechanism of D2O absorption of the poly(2-hydroxyethyl methacrylate)-based contact lens hydrogel studied by two-dimensional correlation ATR-FTIR spectroscopy.

A good understanding of the microdynamics of the water absorption of poly(2-hydroxyethyl methacrylate) (PHEMA)-based contact lens is significant for scientific investigation and commercial applications. In this study, time-dependent ATR-FTIR spectroscopy combined with the perturbation correlation moving-window two-dimensional (PCMW2D) technique and 2D correlation analysis was used to study the microdynamics mechanism. PCMW2D revealed that D2O took 3.4 min to penetrate into the contact lens. PCMW2D also found the PHEMA-based contact lens underwent two processes (I and II) during D2O absorption, and the time regions of processes I and II are 3.4-12.4 min and 12.4-57.0 min. According to 2D correlation analysis, it was proved that process I has 5 steps, and process II has 3 steps. For process I, the first step is D2O hydrogen-bonding with "free" C[double bond, length as m-dash]O in the side chains. The second step is the hydrogen bond generation of the O-HO-D structure between D2O and "free" O-H groups in the side chain ends. The third step is the hydrogen bond generation of D2O and the "free" C[double bond, length as m-dash]O groups close to the crosslinking points in the contact lens. The fourth and the fifth steps are the hydration of -CH3 and -CH2- groups by D2O, respectively. For process II, the first step is the same as that of process I. The second step is the hydrogen bonds breaking of bonded O-H groups and the deuterium exchange between D2O and O-H groups in the side chain ends. The third step is also related to the deuterium exchange, which is the hydrogen bonds regeneration between the dissociated C[double bond, length as m-dash]O groups and the new O-D.

Real-time intelligent detection of ethephon based on a high-throughput ratiometric fluorescent probe.

Ethephon (ETH) is a common pesticide, and its overuse has resulted in a variety of health problems for humans. However, the existing ETH detection methods are tedious and time-consuming, and real-time ETH identification remains a significant difficulty. To mitigate this concern, a dual-emission ratiometric fluorescent probe Ru@ZrMOF was rationally synthesized for the detection of ETH. In the presence of ETH, the emission peak at 435 nm gradually increased, while the peak at 600 nm remained constant, accompanied by the fluorescence color change from red, pink, blue-violet to blue. The fluorescence intensity ratio (F435/F600) demonstrated two linear relations with the ETH concentration ranges at 3 - 50 µM and 50 - 500 µM, with a lowest detection limit at 1 µM. This was attributed to the formation of Zr-O-P bonds which attenuated the ligand-metal charge transfer (LMCT) process, resulting in the recovery of blue fluorescence of the ligand 2-Aminoterephthalic acid (2-APDC). To validate the practical application of the developed platform, a YOLO v5x-based WeChat applet "96 Speckles" was developed, and a 96-well plate and smartphone-embedded 3D-printed portable toolbox was designed for the real-time intelligent detection of ETH. This smart platform allows for real-time and efficient ETH analysis in various real samples including apples, pears and tomatoes.

Sulfur vacancy defects mediated CdZnTeS@BC heterojunction: Artificial intelligence-assisted self-enhanced electrochemiluminescence molecularly imprinted sensing of CTC.

Environmental pollution caused by tetracycline antibiotics is a major concern of global public health. Here, a novel and portable molecularly imprinted electrochemiluminescence (MIECL) sensor based on smartphones for highly sensitive detection of chlortetracycline (CTC) has been successfully established. The high-performance ECL emitter of biomass carbon (BC) encapsulated CdZnTeS (CdZnTeS@BC) was successfully synthesized by hydrothermal. The enhanced ECL performance was ascribed to the introduction of the BC and increased the overall electrical conductivity of the nanoemitter, as well as increased the number of sulfur vacancies and doping on the surface of the emitter based on density functional theory calculations. An aniline-CTC molecular imprinted polymer was synthesized on the surface of the CdZnTeS@BC modified electrode by in-situ electropolymerization. The decrease in MIECL signal was attributed to the increase in impedance effect. The MIECL nanoplatform enabled a wide linear relationship in the range of 0.05-100 µmol/L with a detection limit of 0.029 µmol/L for spectrometer sensors. Interestingly, the light emitted during the MIECL reaction can be captured by a smartphone. Thus, machine learning was used to screen the photos that were taken, and color analysis was carried out on the screened photos by self-developed software, thus achieving a portable, convenient, and intelligent sensing mode. Finally, the sensor obtains satisfactory results in the detection of actual samples, with no significant differences from those of liquid chromatography.

Multiple H-Bonding Cross-Linked Supramolecular Solid-Solid Phase Change Materials for Thermal Energy Storage and Management.

Solid-solid phase change materials (SSPCMs) are considered among the most promising candidates for thermal energy storage and management. However, the application of SSPCMs is consistently hindered by the canonical trade-off between high TES capacity and mechanical robustness. In addition, they suffer from poor recyclability due to chemical cross-linking. Herein, a straightforward but effective strategy for fabricating supramolecular SSPCMs with high latent heat and mechanical strength is proposed. The supramolecular polymer employs multiple H-bonding interactions as robust physical cross-links. This enables SSPCM with a high enthalpy of phase transition (142.5 J g-1 ), strong mechanical strength (36.9 MPa), and sound shape stability (maintaining shape integrity at 120 °C) even with a high content of phase change component (97 wt%). When SSPCM is utilized to regulate the operating temperature of lithium-ion batteries, it significantly diminishes the battery working temperature by 23 °C at a discharge rate of 3 C. The robust thermal management capability enabled through solid-solid phase change provides practical opportunities for applications in fast discharging and high-power batteries. Overall, this study presents a feasible strategy for designing linear SSPCMs with high latent heat and exceptional mechanical strength for thermal management.

Nanozyme-induced deep learning-assisted smartphone integrated colorimetric and fluorometric dual-mode for detection of tetracycline analogs.

In this work, a colorimetric and fluorescent dual-mode probe controlled by NH2-MIL-88 B (Fe, Ni) nanozymes was developed to visually detect tetracycline antibiotics (TCs) residues quantitatively, as well as accurately distinguish the four most widely used tetracycline analogs (tetracycline (TC), chrycline (CTC), oxytetracycline (OTC), and doxycycline (DC)). Colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) may be oxidized to blue oxidized TMB by the Fe Fenton reaction, which was catalyzed by the NH2-MIL-88 B (Fe, Ni) nanozyme with POD-like activity. The colorimetric detection system allows TCs to interact with NH2-MIL-88 B (Fe, Ni). This inhibits the production of ·OH, weakens the oxidation process of TMB, and ultimately lightens the blue color in the system by blocking the electron transfer between NH2-MIL-88 B (Fe, Ni) and H2O2. Furthermore, TCs can interact with NH2-MIL-88 B (Fe, Ni) as a result of the internal filtering effect, which causes the fluorescence intensity to decrease as TCs concentration increases. Additionally, a portable instrument that combines a smartphone sensing platform with colorimetric and fluorescent signals was created for the quick, visual quantitative detection of TCs. The colorimetric and fluorescent dual-mode nano platform enables color change, with detection limits (LODs) of 0.182 µM and 0.0668 µM for the spectrometer and smartphone sensor, respectively, based on the inhibition of fluorescence and enzyme-like activities by TCs. Overall, the colorimetric and fluorescence dual-mode sensor has good stability, high specificity, and an efficient way to eliminate false-positive issues associated with a single detection mode.

Portable, intelligent MIECL sensing platform for ciprofloxacin detection using a fast convolutional neural networks-assisted Tb@Lu2O3 nanoemitter.

Environmental pollution caused by ciprofloxacin is a major problem of global public health. A machine learning-assisted portable smartphone-based visualized molecularly imprinted electrochemiluminescence (MIECL) sensor was developed for the highly selective and sensitive detection of ciprofloxacin (CFX) in food. To boost the efficiency of electrochemiluminescence (ECL), oxygen vacancies (OVs) enrichment was introduced into the flower-like Tb@Lu2O3 nanoemitter. With the specific recognition reaction between MIP as capture probes and CFX as detection target, the ECL signal significantly decreased. According to, CFX analysis was determined by traditional ECL analyzer detector in the concentration range from 5 × 10-4 to 5 × 102 µmol L-1 with the detection limit (LOD) of 0.095 nmol L-1 (S/N = 3). Analysis of luminescence images using fast electrochemiluminescence judgment network (FEJ-Net) models, achieving portable and intelligent quick analysis of CFX. The proposed MIECL sensor was used for CFX analysis in real meat samples and satisfactory results, as well as efficient selectivity and good stability.

Deep learning assisted logic gates for real-time identification of natural tetracycline antibiotics.

The overuse and misuse of tetracycline (TCs) antibiotics, including tetracycline (TTC), oxytetracycline (OTC), doxycycline (DC), and chlortetracycline (CTC), pose a serious threat to human health. However, current rapid sensing platforms for tetracyclines can only quantify the total amount of TCs mixture, lacking real-time identification of individual components. To address this challenge, we integrated a deep learning strategy with fluorescence and colorimetry-based multi-mode logic gates in our self-designed smartphone-integrated toolbox for the real-time identification of natural TCs. Our ratiometric fluorescent probe (CD-Au NCs@ZIF-8) encapsulated carbon dots and Au NCs in ZIF-8 to prevent false negative or positive results. Additionally, our independently developed WeChat app enabled linear quantification of the four natural TCs using the fluorescence channels. The colorimetric channels were also utilized as outputs of logic gates to achieve real-time identification of the four individual natural tetracyclines. We anticipate this strategy could provide a new perspective for effective control of antibiotics.

Enhanced heat tolerance of freeze-dried Enterococcus faecium NRRL B-2354 as valid Salmonella surrogate in low-moisture foods.

In microbial studies of low-moisture foods (LMFs, water activity less than 0.85), freeze-dried bacteria benefit us to inoculate LMFs without introducing extra water or altering food physiochemical properties. However, the freeze-drying process would bring unavoidable damage to bacterial cells and results in less-resistant inoculum that are unlikely to be qualified in microbial studies. Herein, we enhanced bacterial heat tolerance by subjecting the cells to mild heat (42-50 °C) to counteract the reduced heat tolerance and survivability of freeze-dried bacteria. Enterococcus faecium NRRL B-2354 (E. faecium), a Salmonella surrogate in LMFs, was used as the target microorganism because it was widely accepted in microbial validation of thermal pasteurizing LMFs. Three types of LMFs (peanut powder, protein powder, and onion powder) were used as LMFs models to validate the freeze-dried E. faecium in comparison with Salmonella enterica Enteritidis PT 30 (S. Enteritidis) prepared by the traditional aqueous method. The heat tolerance (D65℃ value) of E. faecium increased at all treatments and peaked (+31.48 ± 0.13%) at temperature-time combinations of 45 °C-60 min and 50 °C-5 min. Survivability of freeze-dried inoculum and its heat tolerance retained well within 50 d storage. The freeze-dried E. faecium was prepared in this study brought equal or higher heat tolerance (D85℃ or D75℃) than S. Enteritidis in tested LMFs models. For instance, the D85℃ of freeze-dried E. faecium (heat-treated at 50 °C for 5 min) and S. Enteritidis in whole egg powder are 35.56 ± 1.52 min and 28.41 ± 0.41 min, respectively. The freeze-dried E. faecium with enhanced heat tolerance appears to be a suitable Salmonella surrogate for dry-inoculating LMFs. Our protocol also enables industry-scale production of freeze-dried inoculum by broth-cultivation method combined with mild-heat treatment.

Multi-Physically Cross-Linked Hydrogels for Flexible Sensors with High Strength and Self-Healing Properties.

Excellent mechanical properties and self-healing properties are very important for the practical application of hydrogel flexible sensors. In this study, acrylic acid and stearyl methyl acrylate were selected as monomers to synthesize hydrophobic association hydrogels, and multi-physically cross-linked hydrogels were synthesized by adding ferric chloride and polyvinyl alcohol to introduce ion interaction and a hydrogen bond cross-linking network. The hydrogels were characterized by FTIR, XRD and SEM, and the mechanical properties and self-healing properties were tested using a universal testing machine. It was confirmed that the strength of the hydrogel was significantly improved with the addition of ferric chloride and polyvinyl alcohol, and the hydrogel still showed good self-healing properties. Further testing of its application as a conductive sensor has demonstrated sensitive and stable motion sensing capabilities. This provides an important reference for high-performance hydrogel sensors with both high strength and self-healing properties.

Dual-channel MIRECL portable devices with impedance effect coupled smartphone and machine learning system for tyramine identification and quantification.

We designed a novel, portable, and visual dual-potential molecularly imprinted ratiometric electrochemiluminescence (MIRECL) sensor for tyramine (TYM) detection based on smartphone and deep learning-assisted optical devices. Molecularly imprinted polymer-Ce2Sn2O7 (MIP-Ce2Sn2O7) layers were fabricated by in-situ electropolymerization method as the capture and signal amplification probe. Oxygen vacancies in Ce2Sn2O7 not only enhance the electrochemical redox capability but also accelerate the energy transfer, thereby enhancing the luminescence of cathode ECL. Under optimal conditions, the ECL signals of MIP-Ce2Sn2O7 at the cathode and the anode response of Ru(bpy)32+ was reduced, thus a wide linear range from 0.01 µM to 1000 µM with the detection limit as low as 0.005 µM. Interestingly, combined with an artificial intelligence image recognition algorithm and the principle of optical signal reading by smartphone, the developed MIRECL sensor has been applied to the portable and visual determination of TYM in aquatic samples, and its practicability has been satisfactorily verified.