Dalian Polytechnic University

A rapidly growing field is piezoresistive sensor for accurate respiration rate monitoring to suppress the worldwide respiratory illness. However, a large neglected issue is the sensing durability and accuracy without interference since the expiratory pressure always coupled with external humidity and temperature variations, as well as mechanical motion artifacts. Herein, a robust and biodegradable piezoresistive sensor is reported that consists of heterogeneous MXene/cellulose-gelation sensing layer and Ag-based interdigital electrode, featuring customizable cylindrical interface arrangement and compact hierarchical laminated architecture for collectively regulating the piezoresistive response and mechanical robustness, thereby realizing the long-term breath-induced pressure detection. Notably, molecular dynamics simulations reveal the frequent angle inversion and reorientation of MXene/cellulose in vacuum filtration, driven by shear forces and interfacial interactions, which facilitate the establishment of hydrogen bonds and optimize the architecture design in sensing layer. The resultant sensor delivers unprecedented collection features of superior stability for off-axis deformation (0–120°, ~ 2.8 × 10–3 A) and sensing accuracy without crosstalk (humidity 50%–100% and temperature 30–80 °C). Besides, the sensor-embedded mask together with machine learning models is achieved to train and classify the respiration status for volunteers with different ages (average prediction accuracy ~ 90%). It is envisioned that the customizable architecture design and sensor paradigm will shed light on the advanced stability of sustainable electronics and pave the way for the commercial application in respiratory monitory.

The loss of the stationary phase is one of the key factors limiting the consecutive separation capability of high-speed countercurrent chromatography (HSCCC). Inspired by aerial refueling, this study proposes and establishes a strategy for real-time replenishment of the stationary phase during the separation process. This approach has been demonstrated to significantly enhance the consecutive separation capability of HSCCC in a case study involving the separation of quercetin 3-O-β-d-glucopyranoside from the flower of Rosa rugosa. Measurement of stationary phase retention before and after separation revealed that approximately 30 mL of the stationary phase is lost per single separation run when isolating the target compound from a 200 mg crude sample. Therefore, during consecutive separation, a 30 mL replenishment of stationary phase was completed prior to each sample loading. By utilizing either a dual-pump switching system or an injection valve, consecutive isolation of the target compound from ten successive 200 mg crude samples was achieved without degradation in separation performance, demonstrating a trend toward unlimited separation capability. The establishment of this method addresses the issue of reduced continuous operational endurance in HSCCC and provides an effective solution for its scalable preparative applications.

Vitamin B₆ refers to a family of water-soluble B vitamin, which is essential for various physiological functions, including amino acid metabolism, neurotransmitter synthesis, and hemoglobin synthesis. The biosynthesis of pyridoxine (PN), a commercial form of vitamin B₆, through microbial fermentation has garnered widespread attention owing to its environmentally friendly and safe production methods, as well as its mild reaction conditions. However, the low yield of natural strains limits their application. This study focused on constructing a high-yielding strain of PN through pathway engineering and process optimization. Firstly, five key deoxyxylulose-5-phosphate-dependent pathway genes (epd, pdxB, serC, pdxA, and pdxJ) were overexpressed in Bacillus subtilis ARTP, which improved the PN titer by 3.2-fold to 2.9 mg/L. Subsequently, pdxST genes involved in the DXP-independent pathway were screened from various strains. Ribosome binding site (RBS) sequences were optimized to regulate their expression, which further increased the PN titer to 24.6 mg/L. Finally, systematic medium optimization was identified as a critical strategy for enhancing PN biosynthesis, leading to a remarkable 1.8-fold improvement in PN production. Under optimized fermentation conditions, the engineered strain achieved a PN titer of 174.6 mg/L in fed-batch fermentation, which represents the highest level reported to date in B. subtilis. Overall, this study presents an effective strategy combining pathway engineering and medium optimization for significantly improving PN production, offering valuable insights for the industrial development of PN biosynthesis.