Janus hydrogel loaded with a CO2-generating chemical reaction system: Construction, characterization, and application in fruit and vegetable preservation.

In this study, we inserted a dynamic chemical reaction system that can generate CO2 into Janus hydrogel (JH) to develop a multidimensional preservation platform that integrates hygroscopicity, antibacterial activity, and modified atmospheric capacity. The double gel system developed using sodium alginate/trehalose at a 1:1 ratio effectively encapsulated 90% of citric acid. Furthermore, CO2 loss was avoided by separately embedding NaHCO3/cinnamon essential oil and citric acid microcapsules into a gelatin pad to develop JH. Freeze-dried JH exhibited a porous and asymmetric structure, very strongly absorbing moisture, conducting water, and rapidly releasing CO2 and essential oils. Furthermore, when preserving various fruits and vegetables in practical settings, JH provided several preservation effects, including color protection, microbial inhibition, and antioxidant properties. Our study findings broaden the application of JH technology for developing chemical reaction systems, with the resulting JH holding substantial promise for cold chain logistics.

Co-existence of two plasmids harboring transferable resistance-nodulation-division pump gene cluster, tmexCD1-toprJ1, and colistin resistance gene mcr-8 in Klebsiella pneumoniae.

BACKGROUND: The emergence of plasmid-mediated mobile colistin resistance (mcr) gene poses a great challenge to the clinical application of polymyxins. To date, mcr-1 to mcr-10 have been found in animals, humans, and the environment. Among them, mcr-8 was first identified in Klebsiella pneumoniae (K. pneumoniae) of swine origin, and then mcr-8.1 to mcr-8.5 were successively identified. Notably, K. pneumoniae is the major host of the mcr-8 gene in both animals and humans. This study aims to explore the characteristics of K. pneumoniae strains carrying the mcr-8 gene and tmexCD1-toprJ1 gene cluster and investigate the correlation between these two antibiotic resistance genes. METHODS: The isolates from the poultry farms and the surrounding villages were identified by mass spectrometer, and the strains positive for mcr-1 to mcr-10 were screened by polymerase chain reaction (PCR). The size of the plasmid and the antimicrobial resistance genes carried were confirmed by S1-nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern hybridization, and the transferability of the plasmid was verified by conjugation experiments. Antimicrobial susceptibility testing (AST) and whole genome sequencing (WGS) were used to characterize the strains. RESULTS: Two K. pneumoniae isolates (KP26 and KP29) displaying polymyxin resistance were identified as mcr-8 gene carriers. Besides that, tigecycline-resistant gene cluster tmexCD1-toprJ1 was also found on the other plasmid which conferred strain resistance to tigecycline. Through epidemiological analysis, we found that the mcr-8 gene has dispersed globally, circulating in the human, animals, and the environment. Furthermore, our analysis suggests that the coexistence of mcr-8 and tmexCD1-toprJ1 on a single plasmid might evolved through plasmid recombination. CONCLUSIONS: Although the mcr-8 and tmexCD1-toprJ1 gene clusters in the two strains of K. pneumoniae in this study were on two different plasmids, they still pose a potential threat to public health, requiring close monitoring and further study.

Utilization of Peptidoglycans from Lactic Acid Bacterial Cell Walls for the Mitigation of Acrylamide and 5-Hydroxymethylfurfural.

Acrylamide (AA) and 5-hydroxymethylfurfural (HMF), which are potentially carcinogenic to humans, are often produced during the hot processing of foods. This study first used a molecular docking model to simulate the binding behavior of four lactic acid bacteria peptidoglycans (PGNs) to AA/HMF, and the binding rate of LAB-based PGNs to AA/HMF was evaluated in vitro. In silico results show that interaction energy is the driving force responsible for the adsorption of LAB-derived PGNs to AA/HMF. In vitro results showed that the PGN of B. lactis B1-04 bound the most AA (28.7%) and HMF (48.0%), followed by L. acidophilus NCFM, B. breve CICC 6079, and L. plantarum CICC 22135. Moreover, an AA/HMF-bound layer on the cell surface of B. lactis B1-04 was observed via AFM and SEM due to adsorption. XPS analysis indicated the removal rate of AA/HMF by selected strains was positively correlated with the proportion of C-O, C=O, and N-H groups of PGNs. The atoms O1, O2, O3, O4, N1, N2, N3, H1, and H2 are involved in the adsorption of LAB-based PGNs to AA/HMF. Thus, the PGNs derived from these four Lactobacillus strains can be regarded as natural adsorbents for the binding of AA/HMF.

A Fast Online Elastic-Spine-Based Stiffness Adjusting Mechanism for Fishlike Swimming.

Fish tunes fishtail stiffness by coordinating its tendons, muscles, and other tissues to improve swimming performance. For robotic fish, achieving a fast and online fishlike stiffness adjustment over a large-scale range is of great significance for performance improvement. This article proposes an elastic-spine-based variable stiffness robotic fish, which adopts spring steel to emulate the fish spine, and its stiffness is adjusted by tuning the effective length of the elastic spine. The stiffness can be switched in the maximum adjustable range within 0.26 s. To optimize the motion performance of robotic fish by adjusting fishtail stiffness, a Kane-based dynamic model is proposed, based on which the stiffness adjustment strategy for multistage swimming is constructed. Simulations and experiments are conducted, including performance measurements and analyses in terms of swimming speed, thrust, and so on, and online stiffness adjustment-based multistage swimming, which verifies the feasibility of the proposed variable stiffness robotic fish. The maximum speed and lowest cost of transport for robotic fish are 0.43 m/s (equivalent to 0.81 BL/s) and 7.14 J/(kg·m), respectively.

Tracing the geographical origin of endangered fungus Ophiocordyceps sinensis, especially from Nagqu, using UPLC-Q-TOF-MS.

Ophiocordyceps sinensis (OS), known as "soft gold", played an important role in local economic development. OS from different producing areas was difficult to be discriminated by the appearance. Nagqu OS, a distinguished and safeguarded geographical indication product, commands a premium price in market. The real claim of OS geographical origins is urgently required. Here, 81 OS samples were collected from Tibetan Plateau in China to explore markers for tracing origins. OS from Xigazê can be distinguished by dark color of head of caterpillar. Then 57 samples, a fully representative training-sample set, were used to set up OPLS-DA models by nontargeted metabolomics from UPLC-QTOF-MS. Certain markers were successfully identified and validation using 21 blind test samples confirmed that the markers can trace the geographical origin of OS, especially Nagqu samples. It was affirmed that UPLC-QTOF-MS-based untargeted metabolomics coupled with OPLS-DA was a reliable strategy to trace the geographical origins of OS.

Spatial Domain Image Fusion with Particle Swarm Optimization and Lightweight AlexNet for Robotic Fish Sensor Fault Diagnosis.

Safety and reliability are vital for robotic fish, which can be improved through fault diagnosis. In this study, a method for diagnosing sensor faults is proposed, which involves using Gramian angular field fusion with particle swarm optimization and lightweight AlexNet. Initially, one-dimensional time series sensor signals are converted into two-dimensional images using the Gramian angular field method with sliding window augmentation. Next, weighted fusion methods are employed to combine Gramian angular summation field images and Gramian angular difference field images, allowing for the full utilization of image information. Subsequently, a lightweight AlexNet is developed to extract features and classify fused images for fault diagnosis with fewer parameters and a shorter running time. To improve diagnosis accuracy, the particle swarm optimization algorithm is used to optimize the weighted fusion coefficient. The results indicate that the proposed method achieves a fault diagnosis accuracy of 99.72% when the weighted fusion coefficient is 0.276. These findings demonstrate the effectiveness of the proposed method for diagnosing depth sensor faults in robotic fish.

Characterization, Formation Mechanism, and Curcumin Delivery of Buckwheat Peptide-Based Emulsion Gels.

This study aimed to construct a natural peptide-based emulsion gel (PG) using small peptides (∼2.2 kDa) by mild enzymatic hydrolysis of buckwheat proteins. The obtained PG presented a porous and tight texture and solid-gel viscoelasticity compared with its parent protein-based emulsion gel. Meanwhile, it exhibited good resistance against heating and freeze-thawing. Furthermore, peptide-oil interaction analysis revealed that the gel matrix was enhanced by the hydrophobic aggregation between peptides and oil molecules, H-bonding interaction of peptide molecules, and peptide-oil aggregate repulsion force. Finally, in vitro intestinal digestion experiments demonstrated that PG could embed and pH-responsively release curcumin in the gastrointestinal tract at a release rate of 53.9%. The findings unfold promising opportunities for using natural PG in a range of applications relying on large proteins or other synthesized molecules.

Formation of Maillard Reaction Products in Aged Sorghum Vinegar during Ageing and Protective Effects of Pure Vinegar Melanoidin Against CCl4-Induced Rat Hepatic Damage.

Research background: The processing method generally affects the toxicity and biological activity of aged sorghum vinegar. This study investigates the changes in the intermediate Maillard reaction products of sorghum vinegar during ageing and the in vivo hepatoprotective effects of pure melanoidin obtained from it. Experimental approach: High-performance liquid chromatography (HPLC) and fluorescence spectrophotometry were utilized to quantify intermediate Maillard reaction products. The CCl4-induced liver damage in rats was used to evaluate the protective role of pure melanoidin in rat liver. Results and conclusions: Compared with the initial concentration, the 18-month ageing process caused a 1.2- to 3.3-fold increase in the concentrations of intermediate Maillard reaction products, i.e. 5-hydroxymethylfurfural (HMF), 5-methylfurfural (MF), methyglyoxal (MGO), glyoxal (GO) and advanced glycation end products (AGEs). The concentrations of HMF in the aged sorghum vinegar were 6.1-fold higher than the 450 µM limit standard for honey, implying the need for shortening the ageing of the vinegar in practice for safety concerns. Pure melanoidin (Mr>3.5 kDa) demonstrated significant protective effects against CCl4-induced rat liver damage, as evidenced by normalized serum biochemical parameters (transaminases and total bilirubin), suppressing hepatic lipid peroxidation and reactive oxygen species, as well as increasing glutathione amount and restoring antioxidant enzyme activities. Histopathological analysis revealed that melanoidin in vinegar reduced cell infiltration and vacuolar hepatocyte necrosis in rat liver. The findings demonstrated that a shortened ageing process should be considered in practice to ensure the safety of aged sorghum vinegar. Vinegar melanoidin is a potential alternative for the prevention of hepatic oxidative damage. Novelty and scientific contribution: This study demonstrates that the manufacturing process had a profound influence on the generation of vinegar intermediate Maillard reaction products. In particular, it revealed the in vivo hepatoprotective effect of pure melanoidin from aged sorghum vinegar, and provides insight into the in vivo biological activity of melanoidin.

Metal coordinating-induced self-assembly of cyclic lipopeptides into high-performance antimicrobial supramolecules.

This study designed a green hydrothermally-chelating approach to generate robust antimicrobial complexes via metal-coordinated supramolecular self-assembly of cyclic lipopeptides (CLs). The metal ion (Ca2+ and Zn2+)-coordinated CL (Ca/CL or Zn/CL complex; 1 mg/mL) demonstrated potent antibacterial activity against fungi (A. niger) and bacteria (E. coli and S. aureus) respectively, and in particular, completely suppressed the microbial resistance. Further physicochemical and spectal analysis showed that this coordination approach led to CL with enhanced hydrophobic and intermolecular electrostatic interactions, forming ß-sheet-rich secondary structures allowing the complexes easily contact with and destroy the membrane of microorganisms. Practical application experiments validated that the Ca/CL and Zn/CL complexes strongly avoided table grape and fresh tomato from the contamination of pathogen. The findings of this study laid foundation for the utilization of metal ions to improve the biological activity of natural antimicrobial peptides.

A new strategy to strongly release sweet-enhancing volatiles from goji pomace using trivalent iron salts.

Efforts to fully utilize pomace volatiles have been obstructed by the lack of high-performance technologies to release free and bound volatiles. This study first established that ferric chloride (FeCl3) could strongly release the sweet-enhancing volatiles (SVs) from goji pomace, thus increasing the main aroma compounds [MACs; odor activity value (OAV) > 1] from 9 to 27. The underlying mechanism included the special hydrolysis to glycosides by ferric ions acting as Brønsted and Lewis acids, and the oxidation of ß-carotene and ß-ionone by electrophilic ferrite. The sweet fragrance could be reconstituted and simulated by the 27 MACs. Subsequent extraction and concentration increased MACs on average by 2.28-fold, and the extracted essence could be used as a green and safe sweet-enhancing sugar substitute for specific consumers. These study findings laid a foundation for understanding the relationship between metal salts and flavor chemistry, further providing an opportunity for the full utilization of resources.

Novel strategy to improve the bioactivity and anti-hydrolysis ability of oat peptides via zinc ion-induced assembling.

This study aims to use metal ion coordinating method to improve the bioactivity and anti-hydrolysis ability of bioactive peptides. We demonstrated that zinc (Zn) coordination (10:1 mass ratio of peptide to Zn, pH 6.8, 37 °C) induced assembly of oat peptides, improved pancreatic lipase (PL) inhibitory activity by 30.4-36.8 % and anti-hydrolysis ability against intestinal proteases by 26.5-38.2 %; meanwhile, the peptide-Zn complex drastically reduced the PL affinity to the substrate. Detailed mechanism analysis showed that the high hydrophobicity (276 of fluorescent intensity) and dense eutectic structure of peptide-Zn complexes caused the hard hydrolysis of complexed peptides by proteases; in particular, the neutralized surface charges (∼-3.6 mV) of complexes imparted the peptide-Zn complex high affinity towards PL (-22.3 mV) thus robust PL inhibitory activity. These findings deepened our understanding of the interaction of peptides with metal elements and set the groundwork for the enhancement and protection of bioactive peptides.

Effects of traditional and advanced drying techniques on the physicochemical properties of Lycium barbarum L. polysaccharides and the formation of Maillard reaction products in its dried berries.

This study explored the effect of three different industrial drying methods on the physicochemical, nutritional, and safety profile of goji berries. The hot-air (HD) and microwave drying (MD) methods yielded berries with relatively high polysaccharide content, while vacuum freeze-drying (FD) yielded dried berries with better sensory qualities but relatively less polysaccharide content. The polysaccharides obtained from the HD and MD berries had lower molecular weight, high antioxidant activity and high degrees of Maillard reaction. Further investigations revealed that all three methods, in particular HD and MD, generated high levels of intermediate Maillard reaction products (55.8-86.3 mg/kg) and advanced glycation end-products (fluorescent intensity of 26784-51712), based on significant reduction of reducing sugar and amino acids in the HD and MD berries (p < 0.05). These findings highlight the need to scrutinize the effectiveness of traditional and emerging drying technologies used to produce safe fruits.

Coupled spreading between information and epidemics on multiplex networks with simplicial complexes.

The way of information diffusion among individuals can be quite complicated, and it is not only limited to one type of communication, but also impacted by multiple channels. Meanwhile, it is easier for an agent to accept an idea once the proportion of their friends who take it goes beyond a specific threshold. Furthermore, in social networks, some higher-order structures, such as simplicial complexes and hypergraph, can describe more abundant and realistic phenomena. Therefore, based on the classical multiplex network model coupling the infectious disease with its relevant information, we propose a novel epidemic model, in which the lower layer represents the physical contact network depicting the epidemic dissemination, while the upper layer stands for the online social network picturing the diffusion of information. In particular, the upper layer is generated by random simplicial complexes, among which the herd-like threshold model is adopted to characterize the information diffusion, and the unaware-aware-unaware model is also considered simultaneously. Using the microscopic Markov chain approach, we analyze the epidemic threshold of the proposed epidemic model and further check the results with numerous Monte Carlo simulations. It is discovered that the threshold model based on the random simplicial complexes network may still cause abrupt transitions on the epidemic threshold. It is also found that simplicial complexes may greatly influence the epidemic size at a steady state.

The variants of polymyxin susceptibility in different species of genus Aeromonas.

The aquatic environment is an important medium for the accumulation and dissemination of antibiotic-resistant bacteria as it is often closely related to human activities. Previous studies paid little attention to the prevalence and mechanism of polymyxin-resistant bacteria in the aquatic environment. As a Gram-negative opportunistic pathogen widely distributed in aquatic ecosystems, the antibiotic-resistant profile of Aeromonas spp. deserves much attention. In this study, we identified 61 Aeromonas spp. isolates from water samples in the section of the Yangtze River. The total polymyxin B (PMB) resistance rate of these strains was 49.18% (30/61), showing a high level of polymyxin resistance in Aeromonas spp. The MIC50 and MIC90 for PMB exhibited a significant discrepancy among different species (p < 0.001). The MIC50 and MIC90 for PMB in the Aeromonas hydrophila were 128 mg/L and above 128 mg/L while in Aeromonas caviae and Aeromonas veronii, the MIC50 and MIC90 value were both 2 mg/L. Only two A. veronii strains (MIC = 2 mg/L) and one A. caviae strain (MIC = 0.5 mg/L) were identified as carrying mobilized polymyxin resistant gene mcr-3.42, and mcr-3.16. All mcr genes were located in the chromosome. This is the first report that the downstream region of mcr-3.42 was the truncated mcr-3-like gene separated by the insertion sequences of ISAs20 (1,674 bp) and ISAs2 (1,084 bp). Analysis of epidemiology of mcr-positive Aeromonas genomes from GenBank database showed that the genus Aeromonas and the aquatic environment might be the potential container and reservoir of mcr-3. By the whole-genome sequencing and qRT-PCR, we inferred that the sequence differences in the AAA domain of MlaF protein and its expression level among these three species might be involved in the development of polymyxin resistance. Our study provided evidences of the possible mechanism for the variety of polymyxin susceptibility in different species of the genus Aeromonas and a theoretical basis for the surveillance of the aquatic environment.

Twisted weakly coupled relative humidity sensor coated with a graphene oxide/polyvinyl alcohol composite.

A new coupled fiber optic humidity sensor based on a double-tapered fiber twisted weakly coupled structure coated with a graphene oxide/polyvinyl alcohol (GO/PVA) film has been reported for the first time, to the best of our knowledge. The sensor adopts a 2×2 coupler structure with a waist diameter of 20 µm. The GO/PVA composite film is coated in the weakly coupled area to increase the sensitivity of the sensor. The thickness of the coating layer is about 3 µm. The sensor can realize linear sensing in the relative humidity (RH) range of 45%-85%RH with a dynamic response time of 1.9 s and a recovery time of 5.7 s. The sensitivity of the sensor is up to 0.002/%RH, and the linearity of the sensor is as high as 98.65%. Moreover, the sensor has good stability, reversibility, and low-temperature crosstalk.

Composition, anti-LDL oxidation, and non-enzymatic glycosylation inhibitory activities of the flavonoids from Mesembryanthemum crystallinum.

This study identified the constituents of purified flavonoid (PEF) isolated from Mesembryanthemum crystallinum and examined their inhibitory effects on low-density lipoprotein (LDL) oxidation and non-enzymatic glycosylation. More than 30 kinds of flavonoid compounds were identified in M. crystallinum, including tangeretin, nobiletin, farrerol, protocatechuic aldehyde, diosmin, and rutin. Moreover, tangeretin corresponds to approximately 51% of the total identified flavonoids. PEF had a low IC50 value for 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH·), hydroxyl radical (·OH), and superoxide anion free radical (O 2 - · ) scavenging. They were found to effectively delay and inhibit the production of conjugated diene (CD) and thiobarbituric acid reactive substance (TBARS) during LDL oxidation. Meanwhile, scanning electron microscopy (SEM) of the LDL oxidation incubation system with PEF showed a smooth and dense surface, with no obvious cavitation phenomenon. Furthermore, PEF effectively inhibited the production of LDL glycosylation products and showed a strong inhibitory effect in the latter stage. The electrophoresis of advanced glycosylation end products (AGEs) further confirmed that PEF can effectively prevent the cross-linking between glucose and proteins, protecting LDL from glycosylation-induced damage.

Inhibitory effects of oat peptides on lipolysis: A physicochemical perspective.

Studies on the control of lipid digestion by food-derived active substances have prioritized the direct inhibition of lipase, ignoring the influence of these substances on the stability of bile salt (BS)-stabilized oil emulsions, which are essential for the hydrolysis of triglycerides by lipase. This study aimed to demonstrate the inhibitory potential of oat peptides (OPs) on lipolysis due to lipase inhibition, in particular, the physicochemical destruction of BS-stabilized emulsions. OPs were characterized by an enterostatin-like X-Pro-Y-Pro-Arg terminal sequence, competitively and/or noncompetitively inhibited lipase, and even caused lipase conformational changes. Interestingly, OPs destabilized BS-stabilized emulsions by weakening the rheological cross-linking structure of the emulsions through competitive hydrophobic binding to BS. Further analysis revealed that the H-bond binding of OP to BS significantly destroyed the hydrophilic and lipophilic balance of BS by increasing the surface hydrophobicity. These findings provided novel insights into the action mechanism of bioactive peptides on lipid digestion.

Improving emulsifying properties of carboxylated microcrystalline cellulose by calcium bridging to hydrophobic peptides.

This study aimed to improve the emulsifying properties of microcrystalline cellulose by carboxylating (CC) and bridging to hydrophobic oat globule peptides (HP) via Ca2+ (CC-Ca-HP). FTIR and XRD spectra analysis proved the successful attachment of HP to CC through a salt bridge. The Ca2+-bridging significantly changed the particle characteristics of CC-Ca-HP, including particle size, ζ-potential, and wettability. The Ca2+-bridged composite CC-Ca-HP demonstrated remarkable emulsifying stability compared with the nonbridged blend (CC-HP). Further analysis of the steady flow characteristics and dynamic viscoelastic properties revealed a network structure formed in the CC-Ca-HP emulsion. Moreover, the CC-Ca-HP emulsion showed a marked release of free fatty acids, increased bioaccessibility of zeaxanthin in the simulated gastrointestinal digestion, and less oil oxidation under the accelerated oxidation condition, indicating that the stable structure of CC-Ca-HP imparted by Ca2+-bridging prevented the aggregation of oil droplets as collision occurred under the harsh gastric conditions.

The In Vitro Adsorption Ability of Lactobacillus acidophilus NCFM to Benzo(a)pyrene in PM2.5.

The objective of this work was to explore the ability of lactic acid bacteria strains to bind benzo(a)pyrene (B(a)P) existing in PM2.5. In this study, we examined the ability of Lactobacillus acidophilus NCFM to bind B(a)P in the simulated PM2.5 environment. Among the tested 5 strains, Lactobacillus acidophilus NCFM exhibited the best capacity to bind B(a)P, and its B(a)P binding percentage was 60.00%. Simulations of organic and inorganic systems which represent PM2.5 indicated that B(a)P could be absorbed by strain L. acidophilus NCFM. For the inorganic system of pH 5, L. acidophilus NCFM bound 92.74% B(a)P with a cell concentration of 1 × 1010 cfu/mL at 37°C for 8 hr. Regarding the organic system with pH 6, 73.00% B(a)P was bound by strain L. acidophilus NCFM after this bacterium was incubated at 37°C for 10 min. A quick B(a)P binding by this probiotic bacterium took place in the organic system. The removal of B(a)P from PM2.5 was significantly related to incubation time, cultivation temperature, pH, and cell concentration. Thus, our finding shows that long-term consumption of L. acidophilus NCFM is beneficial for the reduction of B(a)P towards the population who are exposed to PM2.5, although the ability of this bacterium to adsorb B(a)P is partly affected by the differences in the origin of PM2.5.