In situ profiling reveals spatially metabolic injury in the initiation of polystyrene nanoplastic-derived intestinal epithelial injury in mice.

Despite increasing concerns regarding the harmful effects of plastic-induced gut injury, mechanisms underlying the initiation of plastic-derived intestinal toxicity remain unelucidated. Here, mice were subjected to long-term exposure to polystyrene nanoplastics (PS-NPs) of varying sizes (80, 200, and 1000 nm) at doses relevant to human dietary exposure. PS-NPs exposure did not induce a significant inflammatory response, histopathological damage, or intestinal epithelial dysfunction in mice at a dosage of 0.5 mg/kg/day for 28 days. However, PS-NPs were detected in the mouse intestine, coupled with observed microstructural changes in enterocytes, including mild villous lodging, mitochondrial membrane rupture, and endoplasmic reticulum (ER) dysfunction, suggesting that intestinal-accumulating PS-NPs resulted in the onset of intestinal epithelial injury in mice. Mechanistically, intragastric PS-NPs induced gut microbiota dysbiosis and specific bacteria alterations, accompanied by abnormal metabolic fingerprinting in the plasma. Furthermore, integrated data from mass spectrometry imaging-based spatial metabolomics and metallomics revealed that PS-NPs exposure led to gut dysbiosis-associated host metabolic reprogramming and initiated intestinal injury. These findings provide novel insights into the critical gut microbial-host metabolic remodeling events vital to nanoplastic-derived-initiated intestinal injury.

Flaw Detection in White Porcelain Wine Bottles Based on Improved YOLOv4 Algorithm.

Aiming at the problems of low detection accuracy and slow detection speed in white porcelain wine bottle flaw detection, an improved flaw detection algorithm based on YOLOv4 was proposed. By adding Coordinate Attention to the backbone feature extraction network, the extracting ability of white porcelain bottle flaw features was improved. Deformable convolution is added to locate flaws more accurately, so as to improve the detection accuracy of flaws by the model. Efficient Intersection over Union was used to replace Complete Intersection over Union in YOLOv4 to improve the loss function and improve the model detection speed and accuracy. Experimental results on the surface flaw data set of white porcelain wine bottles show that the proposed algorithm can effectively detect white porcelain wine bottle flaws, the mean Average Precision of the model can reach 92.56%, and the detection speed can reach 37.17 frames/s.

Biotechnological production and application of epsilon-poly-L-lysine (ε-PL): biosynthesis and its metabolic regulation.

Epsilon-poly-L-lysine (ε-PL) is an unusual biopolymer composed of L-lysine produced by several microorganisms, especially by the genus Streptomyces. Due to its excellent antimicrobial activity, good water solubility, high safety, and biodegradable nature, ε-PL with a GRAS status has been widely used in food and pharmaceutical industries. In the past years, studies have focused on the biotechnological production of ɛ-PL, the biosynthetic mechanism of microbial ɛ-PL, and its application. To provide new perspectives from recent advances, the review introduced the methods for the isolation of ɛ-PL producing strains and the biosynthetic mechanism of microbial ɛ-PL. We summarized the strategies for the improvement of ɛ-PL producing strains, including physical and chemical mutagenesis, ribosome engineering and gene engineering, and compared the different metabolic regulation strategies for improving ɛ-PL production, including medium optimization, nutrient supply, pH control, and dissolved oxygen control. Then, the downstream purification methods of ɛ-PL and its recent applications in food and medicine industries were introduced. Finally, we also proposed the potential challenges and the perspectives for the production of ε-PL.

Translating potentiometric detection into non-enzymatic amperometric measurement of H2O2.

The developments of alternative signal readout strategies for the ion-selective electrodes (ISEs) are necessary in order to break through the limitation of the Nernst equation. In this work, a simple, convenient and easily operated strategy based on the non-enzymatic amperometric measurement of H2O2 is proposed to read out the potentiometric responses for the ISEs. The proposed amperometric signal readout based on H2O2 is carried out in a two compartment electrochemical cell configuration containing a detection cell and a sample cell, physically connected by a salt bridge. A glassy carbon (GC) electrode is placed in the detection cell to monitor the oxidation current of H2O2, and an ISE is placed in the sample cell to act as both the reference electrode and the potentiometric sensor for obtaining the ion activities. The oxidation of H2O2 is induced by a constant potential applied between the GC electrode and the ISE, and subsequently modulated by the potential change of the ISE in the presence of the primary ion. The proposed amperometric signal readout based on H2O2 shows the satisfied slope sensitivity and detection limit, which are better than or compared to those for the potentiometric responses for the ISEs. This work provides a general strategy for transforming the potential response of the ISEs into the amperometric readout, and is promising for detection of cations (eg., Ca2+) and anions (eg., NO3-) with high sensitivity and excellent selectivity.

Alternative coulometric signal readout based on a solid-contact ion-selective electrode for detection of nitrate.

Traditional potentiometric NO3--selective electrodes suffer from a fundamental limitation of the Nernst slope (59.1 mV/dec at 25 °C) due to the relationship between the potential and the logarithmic of ionic activity. Herein, a coulometric signal readout is proposed instead of the potentiometric response for detection of NO3- based on an ordered mesoporous carbon (OMC)-based solid-contact ion-selective electrode (ISE). The mechanism for obtaining the coulometric signal is based on the electrical double layer capacitance of OMC compensating the potential change at the ion-selective membrane/solution interface during the measurements under the control of a constant applied potential. Under the optimized conditions, the coulometric signal for the OMC-based solid-contact NO3--ISE shows two linear responses in the activity range of 1.0 × 10-6-8.0 × 10-6 M and 8.0 × 10-6-8.0 × 10-4 M, and the detection limit is 4.0 × 10-7 M (3σ/s). The proposed coulometric response also shows excellent reproducibility and stability in the presence of O2 and CO2 and light on/off. Additionally, the coulometric response shows acceptable and reliable results for detection of NO3- in mineral water as compared to the traditional potentiometric response and the ion chromatography. This work provides a promising alternative signal readout for detection of ions by using solid-contact ion-selective electrodes.

Stereoselective synthesis of all-cis boryl tetrahydroquinolines via copper-catalyzed regioselective addition/cyclization of o-aldiminyl cinnamate with B2Pin2.

A copper catalyzed intramolecular 1,2-carboboration of o-aldiminyl cinnamate has been realized in both regio- and stereoselective fashions. This reaction provides a convenient entry to highly valuable and otherwise challenging cis-2,3,4-trisubstituted tetrahydroquinolines carrying a 4-boryl group. An unusual non-Michael addition intermediate or alternatively, a cyclic enolate is proposed to account for the intriguing all-cis configuration in the final products.

Copper-Catalyzed Borylative Cyclization of Substituted N-(2-Vinylaryl)benzaldimines.

A t-BuOCu-initiated reaction sequence of styrene borometalation and intramolecular imine addition has been achieved using a Cu(OTf)2/dppf combination as catalyst. The product of this reaction cascade is a useful 2,3-disubstituted indoline bearing a versatile boryl moiety and is formed with sole cis-selectivity. To account for the observation of the exclusive formation of cis-stereoisomers, a transition state featuring copper-imine coordination is suggested. The application to the synthesis of antioxidant tetrahydroindenoindoles is described.