The existing power decoupling control method of modular multilevel converter (MMC) was developed from that of conventional two-level voltage source converters. Therefore, it cannot fully realize ...power decoupling due to neglecting the coupling effects from submodule capacitor voltage, dc current, circulating current as well as control strategies of circulating current, which inevitably results in inaccurate regulation of active and reactive power, deteriorated system dynamic performance, possible overload operation and eventually threatens the safety and stability of MMC. This paper analyzes the intercoupling among all electrical quantities and corresponding control strategies in MMC. An accurate control model of active and reactive power/current with four coupling paths and influence factors in the rotating frame is also established. A full power decoupling control method has been proposed based on the developed model. The proposed control method can realize accurate and completely decoupled active and reactive power regulation, avoid overload operation, and significantly improve the dynamic performance of MMC. Moreover, it facilitates the parameters selection of MMC controller with no extra cost, which is of great significance for practical projects. The effectiveness and accuracy of the proposed analysis and control methods were verified by both simulation and experimental results.
Modular multilevel converter (MMC) is believed the most competitive solution for high-voltage direct current (HVDC) transmission using voltage source converters. Circulating current suppressing ...strategies based on proportional resonant (PR) controllers are widely used in MMC. This kind of strategies can effectively eliminate all the circulating current components in MMC-HVDC. Unfortunately, it can result in dc-line voltage ripples under unbalanced grid conditions, and thus, deteriorates system performance and stability. Moreover, its existing control model may not exactly reveal the inherent characteristic of MMC, and consequently blocks the further understanding and application. To solve these two problems, first, this paper builds a new and effective control model for this strategy. Second, based on the new model, this paper studies the relationship between circulating current reference value and submodule capacitor voltage, modulation index, and arm current to correct and improve the current understanding of this control strategy. Finally, three improved strategies based on PR controllers are proposed. These improved control strategies can eliminate both circulating current and dc-line voltage ripples, which greatly enhance the fault ride-through capability of MMC-HVDC without adding extra control cost or the number of controllers.
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•The screened M-G structures are very thermodynamically stable, and the stability is even higher than that of the corresponding bulk metal surfaces.•The binding energies of ORR ...intermediates suggest that they are not linear dependence, which are different form the cases found on some metal-based catalysts.•The Au-, Co-, and Ag-G structures could be used as the ORR catalysts.
Graphene doping is a promising direction for developing effective oxygen reduction reaction (ORR) catalysts. In this paper, we computationally investigated the ORR performance of 10 kinds of metal-doped graphene (M-G) catalysts, namely, Al-, Si-, Mn-, Fe-, Co-, Ni-, Pd-, Ag-, Pt-, and Au-G. The results shown that the binding energies of the metal atoms incorporated into the graphene vacancy are higher than their bulk cohesive energies, indicating the formed M-G catalysts are even more stable than the corresponding bulk metal surfaces, and thus avoid the metals dissolution in the reaction environment. We demonstrated that the linear relation among the binding energies of the ORR intermediates that found on metal-based materials does not hold for the M-G catalysts, therefore a single binding energy of intermediate alone is not sufficient to evaluate the ORR activity of an arbitrary catalyst. By analysis of the detailed ORR processes, we predicted that the Au-, Co-, and Ag-G materials can be used as the ORR catalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Flavins are a class of organic compounds with the basic structure of 7,8-dimethy-10-alkyl isoalloxazine. They are ubiquitous in nature and participate in many biochemical reactions. Due to various ...existing forms, there is a lack of systematic research on the absorption and fluorescence spectra of flavins. In this study, employing the density functional theory (DFT) and time-dependent (TD) DFT, we calculated the pH-dependent absorption and fluorescence spectra of flavin of three redox states (quinone, semiquinone, and hydroquinone) in solvents. The chemical equilibrium of three redox states of flavins and the pH effect on the absorption spectra and fluorescence spectra of flavins were carefully discussed. The conclusion helps with identifying the existing forms of flavins in solvent with different pH values.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Gut microbiota dysbiosis has adverse health effects on human body. Multi-drug-resistant tuberculosis (MDR-TB) treatment uses a variety of antibiotics typically for more than 20 months, which may ...induce gut microbiota dysbiosis. The aim of this study is to investigate the long-term effects of MDR-TB treatment on human gut microbiota and its related health consequences. A total of 76 participants were recruited at a hospital in Linyi, China. The study included one active MDR-TB treatment group, one recovered group from MDR-TB and two treatment-naive tuberculosis groups as control. The two treatment-naïve tuberculosis groups were constructed to match the sex and the age of the active MDR-TB treatment and the recovered group, respectively. The fecal and blood samples were collected and analyzed for gut microbiota and metabolic parameters. An altered gut microbiota community and a loss of richness were observed during the MDR-TB treatment. Strikingly, 3-8 years after recovery and discontinuing the treatment, the gut microbiota still exhibited an altered taxonomic composition (
= 0.001) and a 16% decrease in richness (
= 0.018) compared to the gut microbiota before the treatment. The abundance of fifty-eight bacterial genera was significantly changed in the MDR-TB recovered group versus the untreated control group. Although there were persistent and pervasive gut microbiota alterations, no gastrointestinal symptom such as abdominal pain, diarrhea, nausea, flatulence, and constipation was observed in the recovered group. However, chronic disorders may be indicated by the elevated level of low-density lipoprotein cholesterol (LDLC) (
= 0.034) and total cholesterol (TC) (
= 0.017). These adverse lipid changes were associated with the altered gut bacterial taxa, including phylum Firmicutes and Verrucomicrobia and genera
,
,
,
,
,
,
,
,
, and
. Collectively, MDR-TB treatment induced a lasting gut microbiota dysbiosis, which was associated with unfavorable changes in lipid profile.
Allylic sulfones, owning to their widespread distributions in biologically active molecules, received increasing attention in the past few years. However, the synthetic method under mild conditions ...is still a challenging task. In this paper, we report a sulfinic acids ligation with allylic alcohols via metal-free dehydrative cross-coupling. Both aliphatic and aromatic sulfinic acids react with various allylic alcohols to deliver the desired allylic sulfones in high yields with excellent selectivity. This carbon-sulfur bond formation reaction is highly efficient and practical since it works under metal-free, neutral, aqueous media and at room temperature in which the products even can be obtained by simple filtration without the need for organic extraction or column chromatography. Water is found to be essential for the success of this carbon-sulfur bond formation reaction. DFT calculations imply that water acts as promoter in this transformation via intermolecular hydrogen bonds.
Multidrug resistance (MDR) is an issue that is not only related to cancer cells but also associated with the tumor microenvironments. MDR involves the complicated cancer cellular events and the ...crosstalk between cancer cells and their surroundings. Ideally, an effective system against MDR cancer should take dual action on both cancer cells and tumor microenvironments. The authors find that both the drug‐resistant colon cancer cells and the protumor M2 macrophages highly express two nutrient transporters, i.e., secreted protein acidic and rich in cysteine (SPARC) and mannose receptors (MR). By targeting SPARC and MR, a system can act on both cancer cells and M2 macrophages. Herein the authors develop a mannosylated albumin nanoparticles with coencapsulation of different drugs, i.e., disulfiram/copper complex (DSF/Cu) and regorafenib (Rego). The results show that combination therapy of DSF/Cu and Rego efficiently inhibits the growth of drug‐resistant colon tumor, and the combination has not been reported yet for use in anticancer treatment. The system significantly improves the treatment outcomes in the animal model bearing drug‐resistant tumors. The therapeutic mechanisms involve enhanced apoptosis, upregulation of intracellular ROS, anti‐angiogenesis, and tumor‐associated macrophage “re‐education.” This strategy is characterized by dual targeting to and the simultaneous action on cancer cells and M2 macrophages, with biomimetic codelivery of a novel drug combination.
Multidrug resistance (MDR) is a complex of various events involving not only the cancer cells but also their surroundings (tumor microenvironments). The authors develop the “one stone two birds” strategy to overcome MDR by using a mannosylated albumin nanoparticulate codelivery system to dual‐target the cancer cells and M2 macrophages, both of which overexpress mannose receptors and the albumin‐binding protein—secreted protein acidic and rich in cysteine.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
With the aim of improving the image quality of the crucial components of transmission lines taken by unmanned aerial vehicles (UAV), a priori work on the defective fault location of high-voltage ...transmission lines has attracted great attention from researchers in the UAV field. In recent years, generative adversarial nets (GAN) have achieved good results in image generation tasks. However, the generation of high-resolution images with rich semantic details from complex backgrounds is still challenging. Therefore, we propose a novel GANs-based image generation model to be used for the critical components of power lines. However, to solve the problems related to image backgrounds in public data sets, considering that the image background of the common data set CPLID (Chinese Power Line Insulator Dataset) is simple. However, it cannot fully reflect the complex environments of transmission line images; therefore, we established an image data set named “KCIGD” (The Key Component Image Generation Dataset), which can be used for model training. CFM-GAN (GAN networks based on coarse–fine-grained generators and multiscale discriminators) can generate the images of the critical components of transmission lines with rich semantic details and high resolutions. CFM-GAN can provide high-quality image inputs for transmission line fault detection and line inspection models to guarantee the safe operation of power systems. Additionally, we can use these high-quality images to expand the data set. In addition, CFM-GAN consists of two generators and multiple discriminators, which can be flexibly applied to image generation tasks in other scenarios. We introduce a penalty mechanism-related Monte Carlo search (MCS) approach in the CFM-GAN model to introduce more semantic details in the generated images. Moreover, we presented a multiscale discriminator structure according to the multitask learning mechanisms to effectively enhance the quality of the generated images. Eventually, the experiments using the CFM-GAN model on the KCIGD dataset and the publicly available CPLID indicated that the model used in this work outperformed existing mainstream models in improving image resolution and quality.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The early growth pattern, especially the age of peak growth, of broilers affects the time to market and slaughter weight, which in turn affect the profitability of the poultry industry. However, the ...underlying mechanisms regulating chicken growth and development have rarely been studied. This study aimed to identify candidate genes involved in chicken growth and investigated the potential regulatory mechanisms of early growth in chicken. RNA sequencing was applied to compare the transcriptomes of chicken muscle tissues at three developmental stages during early growth. In total, 978 differentially expressed genes (DEGs) (fold change ≥ 2; false discovery rate < 0.05) were detected by pairwise comparison. Functional analysis showed that the DEGs are mainly involved in the processes of cell growth, muscle development, and cellular activities (such as junction, migration, assembly, differentiation, and proliferation). Many of the DEGs are well known to be related to chicken growth, such as MYOD1, GH, IGF2BP2, IGFBP3, SMYD1, CEBPB, FGF2, and IGFBP5. KEGG pathway analysis identified that the DEGs were significantly enriched in five pathways (P < 0.1) related to growth and development: extracellular matrix-receptor interaction, focal adhesion, tight junction, insulin signaling pathway, and regulation of the actin cytoskeleton. A total of 42 DEGs assigned to these pathways are potential candidate genes inducing the difference in growth among the three developmental stages, such as MYH10, FGF2, FGF16, FN1, CFL2, MAPK9, IRS1, PHKA1, PHKB, and PHKG1. Thus, our study identified a series of genes and several pathways that may participate in the regulation of early growth in chicken. These results should serve as an important resource revealing the molecular basis of chicken growth and development.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Corn protein hydrolysate with glutamine-rich peptides protects intestinal epithelial cell barrier function via inhibiting the activation of the MLCK and NF-κB signaling pathways, reducing ...inflammatory response, and regulating tight junction.
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•A hydrolysate named APH with 12.53% glutamine content was prepared from corn protein.•APH protected intestinal barrier function by reducing inflammation and regulating tight junctions.•APH inhibited the activation of MLCK and NF-κB signaling pathways.•374 corn glutamine peptides were identified from APH.
Intestinal barrier is an important basis for intestinal function, which can strictly control the exchange of substances between the host and the external environment. An intact intestianl barrier is also the guardian of human health. In this study, the protective effect of corn protein hydrolysate with glutamine-rich peptides (APH) on intestinal epithelial cell barrier was evaluated in Caco-2 cell inflammatory damage model induced by lipopolysaccharide (LPS). Then, the sequences of glutamine peptides in APH were identified by Nano LC-MS/MS, and the structural characteristics of the identified glutamine peptides were analyzed. The results showed that the hydrolysate effectively alleviated LPS-induced cell damage and decreased the inflammatory response by down-regulating the levels of pro-inflammatory cytokines (TNF-α, IL-8, and IL-1β) and up-regulating the levels of anti-inflammatory cytokine (IL-10). Moreover, the hydrolysate also up-regulated the gene expression of three tight junction proteins (ZO-1, Occludin, Claudin-1) to maintain the integrity of the intestinal epithelial barrier. More importantly, the hydrolysate protected the intestinal barrier function via down-regulating the key genes expression (TLR4, MyD88, NF-κB) in the NF-κB signaling pathway and inhibiting the overexpression of MLCK gene in the MLCK signaling pathway. Finally, 374 corn glutamine peptides were identified from APH, and their structural characteristics showed that corn glutamine peptides had high affinity with membrane proteins. Taken together, these results indicated that APH has excellent potential to protect intestinal barrier function and can be developed into a functional health food.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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