•The engineering of acetyl-CoA metabolism was based on genome-scale metabolic reaction network analysis.•Metabolically engineered Yarrowia lipolytica exhibited significant improvement in squalene ...production.•10 mg/g DCW of squalene was achieved in engineered Yarrowia lipolytica in YPD medium supplemented with citrate.
As a bioactive triterpenoid, squalene is widely used in the food industry, cosmetics, and pharmacology. Squalene’s major commercial sources are the liver oil of deep-sea sharks and plant oils. In this study, we focused on the enhancement of squalene biosynthesis in Yarrowia lipolytica, with particular attention to the engineering of acetyl-CoA metabolism based on genome-scale metabolic reaction network analysis. Although the overexpression of the rate-limiting endogenous ylHMG1 (3-hydroxy-3-methylglutaryl-CoA reductase gene) could improve squalene synthesis by 3.2-fold over that by the control strain, the availability of the key intracellular precursor, acetyl-CoA, was found to play a more significant role in elevating squalene production. Analysis of metabolic networks with the newly constructed genome-scale metabolic model of Y. lipolytica iYL_2.0 showed that the acetyl-CoA pool size could be increased by redirecting carbon flux of pyruvate dehydrogenation towards the ligation of acetate and CoA or the cleavage of citrate to form oxaloacetate and acetyl-CoA. The overexpression of either acetyl-CoA synthetase gene from Salmonella enterica (acs*) or the endogenous ATP citrate lyase gene (ylACL1) resulted in a more than 50% increase in the cytosolic acetyl-CoA level. Moreover, iterative chromosomal integration of the ylHMG1, asc*, and ylACL1 genes resulted in a significant improvement in squalene production (16.4-fold increase in squalene content over that in the control strain). We also found that supplementation with 10 mM citrate in a flask culture further enhanced squalene production to 10 mg/g DCW. The information obtained in this study demonstrates that rationally engineering acetyl-CoA metabolism to ensure the supply of this key metabolic precursor is an efficient strategy for the enhancement of squalene biosynthesis.
The 3D reconstruction of forests provides a strong basis for scientific regulation of tree growth and fine survey of forest resources. Depth estimation is the key to the 3D reconstruction of ...inter-forest scene, which directly determines the effect of digital stereo reproduction. In order to solve the problem that the existing stereo matching methods lack the ability to use environmental information to find the consistency of ill-posed regions, resulting in poor matching effect in regions with weak texture, occlusion and other inconspicuous features, LANet, a stereo matching network based on Linear-Attention mechanism is proposed, which improves the stereo matching accuracy by effectively utilizing the global and local information of the environment, thereby optimizing the depth estimation effect. An AM attention module including a spatial attention module (SAM) and a channel attention module (CAM) is designed to model the semantic relevance of inter-forest scenes from the spatial and channel dimensions. The linear-attention mechanism proposed in SAM reduces the overall complexity of Self-Attention from O(
n
2
) to O(n), and selectively aggregates the features of each position by weighted summation of all positions, so as to learn rich contextual relations to capture long-range dependencies. The Self-Attention mechanism used in CAM selectively emphasizes interdependent channel maps by learning the associated features between different channels. A 3D CNN module is optimized to adjust the matching cost volume by combining multiple stacked hourglass networks with intermediate supervision, which further improves the speed of the model while reducing the cost of inferential calculation. The proposed LANet is tested on the SceneFlow dataset with EPE of 0.82 and three-pixel-error of 2.31%, and tested on the Forest dataset with EPE of 0.68 and D1-all of 2.15% both of which outperform some state-of-the-art methods, and the comprehensive performance is very competitive. LANet can obtain high-precision disparity values of the inter-forest scene, which can be converted to obtain depth information, thus providing key data for high-quality 3D reconstruction of the forest.
Whether symptomatic unruptured intracranial aneurysms (UIAs) lead to change in circulating inflammation remains unclear. This study aims to evaluate the role of hematological inflammatory indicators ...in predicting symptomatic UIA.
Adult patients diagnosed with saccular intracranial aneurysm from March 2019 to September 2023 were recruited retrospectively. Clinical and laboratory data, including the white blood cells (WBC), neutral counts (NEUT), lymphocyte counts (LYM), and monocyte counts (MONO) of each patient, were collected. The neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) were calculated as NLR = NEUT/LYM, LMR = LYM/MONO, SII = PLT*NEUT/LYM. The hematological inflammatory indicators were compared in symptomatic saccular and asymptomatic UIA patients. Multivariable logistic regression analyses were performed to explore the factors predicting symptomatic UIA.
One hundred and fifty UIA patients with a mean age of 58.5 ± 12.4 were included, of which 68% were females. The NLR and LMR were significantly associated with symptomatic UIA, and the association remained in small UIAs (< 7 mm). The multiple logistic regression analysis showed that NLR was independently associated with symptomatic UIA. On ROC curve analysis, the optimal cutoff value of NLR to differentiate symptomatic from asymptomatic was 2.38. In addition, LMR was significantly associated with symptomatic UIA smaller than 7 mm.
There was a significant correlation between NLR and symptomatic UIA. The NLR was independently associated with symptomatic UIA.
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•Experiments of methane hydrate formation is executed in Cubic Hydrate Simulator.•A new kinetic model integrates hydrate pore-scale distribution and reaction area.•We quantify the ...pore-scale characteristics of different water environments.•We achieve excellent performances in matching the history of kinetic behaviors.•This work provides a novel fundamental theory to develop hydrate technology.
Hydrate technology has a bright future for innovations in water, energy, and environmental applications. A reliable and applicable kinetic model of gas hydrate formation is essential for developing hydrate technology. In this work, the experiments of methane hydrate formation with different water saturation SA are conducted in the Cubic Hydrate Simulator (CHS), where the pressure profile and temperature distribution are measured. A new kinetic model integrating hydrate pore-scale distribution is established, assuming that the reaction area AS is controlled by the aqueous phase surface area along the gas-soluble direction. This new model is employed to replicate the experimental process numerically by the history-matching method, and the intrinsic reaction rate constant K0 is determined to be 850.0 mol/m2/Pa/s. In addition, we quantitatively distinguish the characteristics of the water pore-scale distribution in the excess-water, cementing-water, and excess-gas environments. The new model has been validated to be more excellent than those with four currently available models for the hydrate formation, and the sensitivities of the kinetic parameters are discussed in detail. The results show that the spatial distributions of the temperature T and hydrate saturation SH spatial distribution are heterogeneous in CHS due to the phase change and heat transfer effect. The excellent performance of the hydrate formation kinetics gives us strong confidence in the reliability and accuracy of the new model. This provides reliable predictions and mechanistic understandings of hydrate formation kinetics in the porous media.
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•Secondary hydrate formation (SHF) are studied both experimentally and numerically.•A new kinetic model integrates hydrate pore-scale morphology and the SHF ...characteristics.•Heterogeneous manner of hydrate formation are quantified in Cubic Hydrate Simulator.•The SHF significantly exacerbates the hydrate formation heterogeneity.
The challenge of secondary hydrate formation (SHF) is frequently encountered in hydrate formation and dissociation experiments. However, there is currently a lack of modeling theory of SHF kinetics in the field and laboratory tests. In this work, the hydrate formation experiments concerning the SHF are carried out in a cubic hydrate simulator (CHS), where the pressure profiles and temperature spatial distributions are measured. A new kinetic model of hydrate formation integrating hydrate pore-scale morphology and SHF characteristics is developed. The newly developed model with unified kinetic parameters is employed in the Tough+hydrate (T+H) simulator to duplicate the experiment processes numerically, which achieves excellent agreement with the experimental data. The results show that the evolutions of the spatial distributions of the temperature and hydrate saturation behave in heterogeneous manners in the hydrate formation processes. This also reveals that the SHF can significantly exacerbate the hydrate heterogeneity in the CHS. Two additional experiments and comparisons with currently available models have validated the feasibility and accuracy of the new model. This work provides a reliable and adaptable model for describing the entire lifecycle of the hydrate formation kinetics in the porous media.
