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The paper concerns motion modeling for full-scale ships under the frame of system identification (SI) principles. Several groups of full-scale ship maneuvering experiments have been implemented to collect research data. On structure identification, as an innovation, a nonlinear integrating ship motion model is identified and established. The concerned model includes 21 parameters. Under the premise of error criterion, a batch least-squares (BLS)-based parameter estimation process is used to estimate the 21 parameters. The strategy is verified for feasibility and availability by using a pragmatic case study. The accuracy of the estimated parameter values is checked by comparing the track in simulation with the trial trajectory. Research indicates that the technical process proposed in the paper from the perspective of SI principles can be applied to the modeling of ship maneuvering motion.

There are many types of natural plants in nature that contain a variety of effective and complex chemical components. These constituents can be categorized as organic acids, volatile oils, coumarins, steroids, glycosides, alkaloids, carbohydrates, phytochromes, etc., all of which play important roles in the fields of pharmaceuticals, food, nutraceuticals, and cosmetics. The study of extraction and chemical composition analysis of natural products is important for the discovery of these active ingredients and their precursors. Therefore, the aim of this article is to review the status of research on the extraction, separation and purification, and structural identification of natural products, to provide a reference for the study of natural products.

UHPLC-HRMS (ultra-high-performance liquid chromatography-high resolution mass spectrometry) is a new technique that unifies the application of UHPLC with HRMS. Because of the high sensitivity and good separation ability of UHPLC and the sensitivity of HRMS, this technique has been widely used for structure identification, quantitative determination, fingerprint analysis, and elucidation of the mechanisms of action of traditional Chinese medicines (TCMs) in recent years. This review mainly outlines the advantages of using UHPLC-HRMS and provides a survey of the research advances on UHPLC-HRMS for the quality control of TCMs.

Five fungal endophytes, Alternaria sp., Aspergillus sp., Chaetomium sp., Rhizopus sp. and Curvularia sp., were isolated from an Egyptian herbaceous plant, Tribulus terrestris, and tested for their antibacterial activity against three phytopathogenic bacteria (Pectobacterium carotovorum subsp. carotovorum, Ralstonia solanacearum, Pseudomonas syringae pv. syringae). Chaetomium sp. showed the highest antibacterial activity. This strain was identified morphologically and molecularly as Chaetomium cochliodes MS03 (MW898133) based on the ITS1-5.8S rRNA-ITS2 genomic region. Chaetomium cochliodes caused 15 and 8 mm inhibition zones of P. carotovorum subsp. carotovorum and R. solanacearum, respectively. Chaetomium cochliodes isolate was fermented and extracted with ethyl acetate. The crude extract of C. cochliodes showed strong antibacterial activity against P. carotovorum subsp. carotovorum (inhibition zone = 27 mm). Bioassay guided isolation of the crude extract using silica gel column chromatography was conducted to isolate bioactive secondary metabolites. Minimum inhibitory concentrations (MICs) were 500, 32 and 4 mg/L for C. cochliodes extract, fraction 14 and fraction 15, respectively, against P. carotovorum subsp. carotovorum. Bioactive fractions were analyzed by GC/MS. The bioactive pure compound was identified as 9,12-octadecadienoic acid (Z,Z) and the chemical structure was confirmed by H1 NMR and C13 NMR spectral analysis. The isolated compound showed a promising antibacterial activity against P. carotovorum subsp. carotovorum with MIC value of 32 mg/L.

This study explores the antifungal properties of Agaricus blazei Murrill, a valuable medicinal and edible fungus. Six compounds (1–6) were first isolated from A. blazei using various isolation techniques and identified using spectroscopic methods. These compounds include linoleic acid, 1,1′-oxybis(2,4-di-tert-butylbenzene), glycerol monolinoleate, volemolide (17R)-17-methylincisterol, (24s)-ergosta-7-en-3-ol, and dibutyl phthalate. This study also assesses the antifungal activities of these compounds against Trichophyton mentagrophology, Trichophyton rubrum, Candida albicans, and Cryptococcus neoformans. The results demonstrate varied sensitivities against these pathogenic fungi, with compound 2 showing significant inhibition against T. mentagrophology, compound 3 showing significant inhibition against T. rubrum, and compound 6 showing significant inhibition against C. albicans. This study underscores the medicinal potential of A. blazei as an antifungal agent and sheds light on its valuable research implications.

Novel peptide–calcium chelates have been successfully developed using ultrasound technology from Nannochloropsis oceanica ( N. oceanica ), and they have been found to be superior calcium supplements as natural bioactive peptide–calcium chelates. The study has provided a comprehensive understanding of the interaction between Ca 2+ ions and peptides or amino acids. Under optimal conditions, a calcium chelation rate of 61.89 ± 0.12%, a calcium chelation activity of 9.08 ± 0.15%, and a calcium chelation yield of 65.57 ± 0.19% were achieved. Most peptides and peptide–calcium chelate have a molecular weight below 1500 Da. Characterization tests confirmed the production of new complexes as chelates, and different spectral and signal analyses by FTIR, fluorescence, UV, XRD analysis, and zeta potential, collaboratively, confirmed that metal ions combined with amino, carboxyl, and other active chelating groups in N. oceanica peptides form metal chelates and generate new crystal structure interactions within the chelates. In addition, morphological analysis the peptide–calcium chelate was depicted through SEM and AFM images implied that folded, aggregated, and tightly packed structures were formed in the peptide–calcium chelate. The calcium content in chelates up to 4.48% (0.58% in peptides) suggested the interaction of calcium with peptides to form chelates. Besides, peptide–calcium chelates are relatively stable under high temperature, pH, and digestive conditions in stage of gastric digestion tract, indicating that they can serve as an efficient calcium supplement. These findings underscore the potential development of functional foods from N. oceanica peptides, offering an alternative to conventional calcium supplements. Furthermore, the results of this study can provide new directions for the high-value utilization and development of N. oceanica protein and provide a theoretical basis for N. oceanica peptide as a functional component of calcium supplements.

Karst reservoir Computed Tomography (CT) images exhibit blurred boundaries, scale variations, and complex structures. Existing 3D U-Net-based segmentation methods are inadequate in both detail recognition and overall structural representation. Therefore, this paper proposes an improved 3D U-Net architecture to adapt to the multi-scale and low-contrast characteristics of karst reservoirs. This paper introduces a multi-scale input path at the encoder end, extracting volumetric features at different resolutions in parallel to capture both fine-grained holes and large-scale channels. A spatial attention module is embedded in the skip connections to weight the encoded features to highlight boundaries and key regions. Multi-scale features are fused during the decoding phase to gradually reconstruct the three-dimensional space. Furthermore, the Dice loss is combined with the gradient-based boundary-aware loss during training. The latter enhances boundary sensitivity by calculating the 3D gradient difference between the predicted image and the label image. Experimental results show that the improved complete model achieves an 87.8% Dice coefficient and a 1.9-pixel boundary error in karst reservoir CT image segmentation, improving both regional overlap and boundary accuracy. This method effectively identifies karst structures at different scales, providing reliable data support for complex reservoir modeling and analysis.

Four pairs of novel dopamine enantiomer trimers, (±)-cryptamides A–D (1–4), and 10 pairs of previously described dopamine enantiomer dimers (5–14) were isolated from the Periostracum cicadae, the cast-off shell of the insect Cryptotympana pustulata. Aside from being pairs of enantiomers, the eight trimers were also elucidated to be regioisomers, most likely resulting from their mechanism of formation, [4 + 2] cycloaddition. The discovery of dopamine trimers is rarely reported when it comes to natural products derived from insects.

Plant-derived phytochemicals have recently drawn interest in the prevention and treatment of diabetes mellitus (DM). The seeds of Moringa oleifera Lam. are widely used in food and herbal medicine for their health-promoting properties against various diseases, including DM, but many of their effective constituents are still unknown. In this study, 6 new phenolic glycosides, moringaside B–G (1–6), together with 10 known phenolic glycosides (7–16) were isolated from M. oleifera seeds. The structures were elucidated by 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data analysis. The absolute configurations of compounds 2 and 3 were determined by electronic circular dichroism (ECD) calculations. Compounds 2 and 3 especially are combined with a 1,3-dioxocyclopentane moiety at the rhamnose group, which are rarely reported in phenolic glycoside backbones. A biosynthetic pathway of 2 and 3 was assumed. Moreover, all the isolated compounds were evaluated for their inhibitory activities against α-glucosidase. Compounds 4 and 16 exhibited marked activities with IC50 values of 382.8 ± 1.42 and 301.4 ± 6.22 μM, and the acarbose was the positive control with an IC50 value of 324.1 ± 4.99 μM. Compound 16 revealed better activity than acarbose.

Ketamine analogues have been emerging in recent years and are causing severe health and social problems worldwide. Ketamine analogues use 2-phenyl-2-aminocyclohexanone as the basic structure and achieve physiological reactions similar to or even more robust than the prototype of ketamine by changing the substituents on the benzene ring (R1 and R2) and amine group (RN1). Therefore, the mass spectrometry (MS) fragmentation pathways and fragments of ketamine analogues have certain regularity. Eight ketamine analogues are systematically investigated by GC-QTOF/MS and LC-Q-Orbitrap MS/MS with the positive mode of electrospray ionization. The MS fragmentation patterns of ketamine analogues are summarized according to high-resolution MS data. The α-cleavage of carbon bond C1-C2 in the cyclohexanone moiety and further losses of CO, methyl radical, ethyl radical and propyl radical are the characteristic fragmentation pathways of ketamine analogues in EI-MS mode. The loss of H2O or the sequential loss of RN1NH2, CO and C4H6 are the distinctive fragmentation pathways of ketamine analogues in ESI-MS/MS mode. Moreover, these MS fragmentation patterns are first introduced for the rapid screening of ketamine analogues in suspicious powder. Furthermore, the structure of the ketamine analogue in suspicious powder is 2-(Methylamino)-2-(o-tolyl)cyclohexan-1-one, which is further confirmed by NMR. This study contributes to the identification of the chemical structure of ketamine analogues, which can be used for the rapid screening of ketamine analogues in seized chemicals.