MFF-YOLO: An Accurate Model for Detecting Tunnel Defects Based on Multi-Scale Feature Fusion.

Tunnel linings require routine inspection as they have a big impact on a tunnel's safety and longevity. In this study, the convolutional neural network was utilized to develop the MFF-YOLO model. To improve feature learning efficiency, a multi-scale feature fusion network was constructed within the neck network. Additionally, a reweighted screening method was devised at the prediction stage to address the problem of duplicate detection frames. Moreover, the loss function was adjusted to maximize the effectiveness of model training and improve its overall performance. The results show that the model has a recall and accuracy that are 7.1% and 6.0% greater than those of the YOLOv5 model, reaching 89.5% and 89.4%, respectively, as well as the ability to reliably identify targets that the previous model error detection and miss detection. The MFF-YOLO model improves tunnel lining detection performance generally.

Valorization of Gelidium amansii for dual production of D-galactonic acid and 5-hydroxymethyl-2-furancarboxylic acid by chemo-biological approach.

BACKGROUND: Marine macroalgae Gelidium amansii is a promising feedstock for production of sustainable biochemicals to replace petroleum and edible biomass. Different from terrestrial lignocellulosic biomass, G. amansii is comprised of high carbohydrate content and has no lignin. In previous studies, G. amansii biomass has been exploited to obtain fermentable sugars along with suppressing 5-hydroxymethylfurfural (HMF) formation for bioethanol production. In this study, a different strategy was addressed and verified for dual production of D-galactose and HMF, which were subsequently oxidized to D-galactonic acid and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) respectively via Pseudomonas putida. RESULTS: G. amansii biomass was hydrolyzed by dilute acid to form D-galactose and HMF. The best result was attained after pretreatment with 2% (w/w) HCl at 120 °C for 40 min. Five different Pseudomonas sp. strains including P. putida ATCC 47054, P. fragi ATCC 4973, P. stutzeri CICC 10402, P. rhodesiae CICC 21960, and P. aeruginosa CGMCC 1.10712, were screened for highly selective oxidation of D-galactose and HMF. Among them, P. putida ATCC 47054 was the outstanding suitable biocatalyst converting D-galactose and HMF to the corresponding acids without reduced or over-oxidized products. It was plausible that the pyrroloquinoline quinone-dependent glucose dehydrogenase and undiscovered molybdate-dependent enzyme(s) in P. putida ATCC 47054 individually played pivotal role for D-galactose and HMF oxidation. Taking advantage of its excellent efficiency and high selectivity, a maximum of 55.30 g/L D-galactonic acid and 11.09 g/L HMFCA were obtained with yields of 91.1% and 98.7% using G. amansii hydrolysates as substrate. CONCLUSIONS: Valorization of G. amansii biomass for dual production of D-galactonic acid and HMFCA can enrich the product varieties and improve the economic benefits. This study also demonstrates the perspective of making full use of marine feedstocks to produce other value-added products.

A novel thermostable ß-galactosidase from Bacillus coagulans with excellent hydrolysis ability for lactose in whey.

ß-Galactosidase is one of the most important enzymes used in dairy industry. Here, a novel thermostable ß-galactosidase was cloned and overexpressed from Bacillus coagulans NL01 in Escherichia coli. The phylogenetic trees were constructed using neighbor-joining methods. Phylogeny and amino acid analysis indicated that this enzyme belonged to family 42 of glycoside hydrolases. The optimal pH and temperature were, respectively, 6.0 and 55 to 60°C. The purified enzyme had a 3.5-h half-life at 60°C. Enzyme activity was enhanced by Mn2+. Compared with other ß-galactosidases from glycoside hydrolase family 42, B. coagulans ß-galactosidase exhibited excellent hydrolysis activity. The Michaelis constant (Km) and maximum rate of enzymatic reaction (Vmax) values for p-nitrophenyl-ß-d-galactopyranoside and o-nitrophenyl-ß-d-galactopyranoside were 1.06 mM, 19,383.60 U/mg, and 2.73 mM, 5,978.00 U/mg, respectively. More importantly, the enzyme showed lactose hydrolysis ability superior to that of the commercial enzyme. The specific enzyme activity for lactose was 27.18 U/mg. A total of 104.02 g/L lactose in whey was completely hydrolyzed in 3 h with addition of 2.38 mg of pure enzyme per gram of lactose. In view of the high price of commercial ß-galactosidase, B. coagulans ß-galactosidase could be a promising prototype for development of commercial enzymes aimed at lactose treatment in the dairy industry.

Elegant and Efficient Biotransformation for Dual Production of d-Tagatose and Bioethanol from Cheese Whey Powder.

In this study, the dual production of valuable d-tagatose and bioethanol from lactose and cheese whey powder is presented. First, a one-pot biosynthesis involving lactose hydrolysis and d-galactose isomerization for d-tagatose production was established using crude enzymes of recombinant Escherichia coli with l-arabinose isomerase (L-AI) at 50 °C. Compared to the current enzymatic system, only L-AI was overexpressed, because of the unexpectedly thermotolerant ß-galactosidase in E. coli BL21(DE3). Moreover, this high temperature rendered the d-glucose catabolism of E. coli inactive, while retaining all fermentable sugars for bioethanol fermentation. Thereafter, the mixed sugar syrup was fermented by Saccharomyces cerevisiae NL22. A total of 23.5 g/L d-tagatose and 26.9 g/L bioethanol was achieved from cheese whey powder containing 100 g/L lactose. This bioprocess not only provides an efficient method for the functionalization of byproduct whey, but also offsets the high production cost of d-tagatose and bioethanol.