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1.
Cell Death Dis ; 13(1): 29, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013107

RESUMO

Methylglyoxal (MGO) is an active metabolite of glucose and plays a prominent role in the pathogenesis of diabetic vascular complications, including endothelial cell apoptosis induced by oxidative stress. Metformin (MET), a widely prescribed antidiabetic agent, appears to reduce excessive reactive oxygen species (ROS) generation and limit cell apoptosis. However, the molecular mechanisms underlying this process are still not fully elucidated. We reported here that MET prevents MGO-induced apoptosis by suppressing oxidative stress in vitro and in vivo. Protein expression and protein phosphorylation were investigated using western blotting, ELISA, and immunohistochemical staining, respectively. Cell viability and apoptosis were assessed by the MTT assay, TUNEL staining, and Annexin V-FITC and propidium iodide double staining. ROS generation and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Our results revealed that MET prevented MGO-induced HUVEC apoptosis, inhibited apoptosis-associated biochemical changes such as loss of MMP, the elevation of the Bax/Bcl-2 ratio, and activation of cleaved caspase-3, and attenuated MGO-induced mitochondrial morphological alterations in a dose-dependent manner. MET pretreatment also significantly suppressed MGO-stimulated ROS production, increased signaling through the ROS-mediated PI3K/Akt and Nrf2/HO-1 pathways, and markedly elevated the levels of its downstream antioxidants. Finally, similar results were obtained in vivo, and we demonstrated that MET prevented MGO-induced oxidative damage, apoptosis, and inflammation. As expected, MET reversed MGO-induced downregulation of Nrf2 and p-Akt. In addition, a PI3K inhibitor (LY-294002) and a Nrf2 inhibitor (ML385) observably attenuated the protective effects of MET on MGO-induced apoptosis and ROS generation by inhibiting the Nrf2/HO-1 pathways, while a ROS scavenger (NAC) and a permeability transition pores inhibitor (CsA) completely reversed these effects. Collectively, these findings broaden our understanding of the mechanism by which MET regulates apoptosis induced by MGO under oxidative stress conditions, with important implications regarding the potential application of MET for the treatment of diabetic vascular complications.

2.
ACS Infect Dis ; 8(1): 210-226, 2022 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-34985858

RESUMO

Plasmodium falciparum causes the most lethal form of malaria. Peroxide antimalarials based on artemisinin underpin the frontline treatments for malaria, but artemisinin resistance is rapidly spreading. Synthetic peroxide antimalarials, known as ozonides, are in clinical development and offer a potential alternative. Here, we used chemoproteomics to investigate the protein alkylation targets of artemisinin and ozonide probes, including an analogue of the ozonide clinical candidate, artefenomel. We greatly expanded the list of proteins alkylated by peroxide antimalarials and identified significant enrichment of redox-related proteins for both artemisinins and ozonides. Disrupted redox homeostasis was confirmed by dynamic live imaging of the glutathione redox potential using a genetically encoded redox-sensitive fluorescence-based biosensor. Targeted liquid chromatography-mass spectrometry (LC-MS)-based thiol metabolomics also confirmed changes in cellular thiol levels. This work shows that peroxide antimalarials disproportionately alkylate proteins involved in redox homeostasis and that disrupted redox processes are involved in the mechanism of action of these important antimalarials.

3.
Comput Intell Neurosci ; 2021: 1268453, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34956342

RESUMO

With the development of machine learning, as a branch of machine learning, deep learning has been applied in many fields such as image recognition, image segmentation, video segmentation, and so on. In recent years, deep learning has also been gradually applied to food recognition. However, in the field of food recognition, the degree of complexity is high, the situation is complex, and the accuracy and speed of recognition are worrying. This paper tries to solve the above problems and proposes a food image recognition method based on neural network. Combining Tiny-YOLO and twin network, this method proposes a two-stage learning mode of YOLO-SIMM and designs two versions of YOLO-SiamV1 and YOLO-SiamV2. Through experiments, this method has a general recognition accuracy. However, there is no need for manual marking, and it has a good development prospect in practical popularization and application. In addition, a method for foreign body detection and recognition in food is proposed. This method can effectively separate foreign body from food by threshold segmentation technology. Experimental results show that this method can effectively distinguish desiccant from foreign matter and achieve the desired effect.


Assuntos
Aprendizado Profundo , Inocuidade dos Alimentos , Aprendizado de Máquina , Redes Neurais de Computação , Reconhecimento Psicológico
4.
Psychol Health Med ; : 1-14, 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34818948

RESUMO

The bidirectional associations between parenting styles and conduct problems in Chinese children attending preschools were rarely discussed. A study covering 171 preschools in Longhua District of Shenzhen, China was conducted among children when they first attended preschools. Parents of children reported the self-perceived parenting styles and their children's conduct problems using validated questionnaires. The bidirectional associations between parenting styles and conduct problems in children were assessed using multivariate linear or logistic regressions in both cross-sectional and cohort settings. In cross-sectional settings, the bidirectional associations were present in all dimensions of parenting styles with children's conduct problems. After 1.01 years of follow-up, increases in parenting dimensions of rejection, control attempts, and favoring subject were significantly associated with children's conduct problems at follow-up, while increases in emotional warmth of parents significantly reduced such risk. In addition, parents of children who had conduct problems at baseline but regressed to normal at follow-up showed decreased scores in negative parenting dimensions. In contrast, among children who developed conduct problems during the study period, the scores of rejection and favoring subject in their parents have increased significantly, while the scores of emotional warmth have decreased. Parent-to-child effect was similar between fathers and mothers, while child-to-parent effect was stronger in fathers than that in mothers. In order to stop the negative feedback loop between poor parenting styles and children's conduct problems, our study underscored the importance of intervention not only in parents but also in their children.

5.
Front Pharmacol ; 12: 722907, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34733156

RESUMO

Mechanical ventilation is an indispensable life-support treatment for acute respiratory failure in critically ill patients, which is generally believed to involve uncontrolled inflammatory responses. Oxytocin (OT) has been reported to be effective in animal models of acute lung injury. However, it is not clear whether Oxytocin has a protective effect on ventilator-induced lung injury (VILI). Therefore, in this study, we aimed to determine whether OT can attenuate VILI and explore the possible mechanism of this protection. To this end, a mouse VILI model was employed. Mice were pretreated with OT 30 min before the intraperitoneal injection of saline or nigericin and ventilation for 4 h, after which they were euthanized. Pathological changes, lung wet/dry (W/D) weight ratio, myeloperoxidase (MPO) activity, the levels of inflammatory cytokines [i.e., interleukin (IL)-1ß, IL-6, and IL-18] in lung tissues and bronchoalveolar lavage fluid (BALF), and expression of NLRP3, Toll-like receptor 4 (TLR4), caspase-1, nuclear factor (NF)-κB, and GSDMD in lung tissues were measured. OT treatment could reduce pathological injury, the W/D ratio, and MPO activity in VILI mice. Our data also indicated that OT administration alleviated the expression of TLR4/My-D88 and the activation of NF-κB, NLRP3, and caspase-1 in lung tissues from the VILI mice model. Furthermore, OT also decreased the levels of IL-1ß, IL-6, and IL-18 in the bronchoalveolar lavage fluid. Moreover, the OT administration may alleviate the activation of GSDMD partially through its effects on the NLRP3-mediated pathway. Collectively, OT exerted a beneficial effect on VILI by downregulating TLR4-and NLRP3-mediated inflammatory pathways.

6.
Nature ; 598(7879): 76-81, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34616058

RESUMO

Platinum (Pt) has found wide use as an electrocatalyst for sustainable energy conversion systems1-3. The activity of Pt is controlled by its electronic structure (typically, the d-band centre), which depends sensitively on lattice strain4,5. This dependence can be exploited for catalyst design4,6-8, and the use of core-shell structures and elastic substrates has resulted in strain-engineered Pt catalysts with drastically improved electrocatalytic performances7,9-13. However, it is challenging to map in detail the strain-activity correlations in Pt-catalysed conversions, which can involve a number of distinct processes, and to identify the optimal strain modification for specific reactions. Here we show that when ultrathin Pt shells are deposited on palladium-based nanocubes, expansion and shrinkage of the nanocubes through phosphorization and dephosphorization induces strain in the Pt(100) lattice that can be adjusted from -5.1 per cent to 5.9 per cent. We use this strain control to tune the electrocatalytic activity of the Pt shells over a wide range, finding that the strain-activity correlation for the methanol oxidation reaction and hydrogen evolution reaction follows an M-shaped curve and a volcano-shaped curve, respectively. We anticipate that our approach can be used to screen out lattice strain that will optimize the performance of Pt catalysts-and potentially other metal catalysts-for a wide range of reactions.

7.
Cells ; 10(10)2021 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-34685726

RESUMO

Advancements in reprogramming somatic cells into induced pluripotent stem cells (iPSCs) have provided a strong framework for in vitro disease modeling, gene correction and stem cell-based regenerative medicine. In cases of skeletal muscle disorders, iPSCs can be used for the generation of skeletal muscle progenitors to study disease mechanisms, or implementation for the treatment of muscle disorders. We have recently developed an improved directed differentiation method for the derivation of skeletal myogenic progenitors from hiPSCs. This method allows for a short-term (2 weeks) and efficient skeletal myogenic induction (45-65% of the cells) in human pluripotent stem cells (ESCs/iPSCs) using small molecules to induce mesoderm and subsequently myotomal progenitors, without the need for any gene integration or modification. After initial differentiation, skeletal myogenic progenitors can be purified from unwanted cells using surface markers (CD10+CD24-). These myogenic progenitors have been extensively characterized using in vitro gene expression/differentiation profiling as well as in vivo engraftment studies in dystrophic (mdx) and muscle injury (VML) rodent models and have been proven to be able to engraft and form mature myofibers as well as seeding muscle stem cells. The current protocol describes a detailed, step-by-step guide for this method and outlines important experimental details and troubleshooting points for its application in any human pluripotent stem cells.

8.
Cell Death Discov ; 7(1): 305, 2021 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-34686659

RESUMO

ABATRACT: Obesity is known to be associated with adipose tissue inflammation and insulin resistance. Importantly, in obesity, the accumulation of proinflammatory macrophages in adipose tissue correlates with insulin resistance. We hypothesized that the receptor for advanced glycation end products (RAGE) and associated ligands are involved in adipose tissue insulin resistance, and that the activation of the AGE-RAGE axis plays an important role in obesity-associated inflammation. C57BL/6J mice (WT) and RAGE deficient (RAGE-/-) mice were fed a high fat diet (HFD) and subjected to glucose and insulin tolerance tests. Epdidymal adipose tissue (eAT) was collected and adipose stromal vascular cells isolated using flow cytometry. Visceral adipose tissue macrophage polarization was assessed by quantitative real time PCR. Immunoblotting was performed to evaluate the insulin signaling in adipose tissues. In additional studies, cell trafficking was assessed by injecting labeled blood monocytes into recipient mice. RAGE-/- mice displayed improved insulin sensitivity and glucose tolerance, accompanied by decreased body weight and eAT mass. Exogenous methylglyoxal (MGO) impaired insulin-stimulated AKT signaling in adipose tissues from WT mice fed a normal chow diet, but not in RAGE-/- mice. In contrast, in obese mice, treatment with MGO did not reduce insulin-induced phosphorylation of AKT in WT-HFD mice. Moreover, insulin-induced AKT phosphorylation was found to be impaired in adipose tissue from RAGE-/--HFD mice. RAGE-/- mice displayed improved inflammatory profiles and evidence for increased adipose tissue browning. This observation is consistent with the finding of reduced plasma levels of FFA, glycerol, IL-6, and leptin in RAGE-/- mice compared to WT mice. Collectively the data demonstrate that RAGE-mediated adipose tissue inflammation and insulin-signaling are potentially important mechanisms that contribute to the development of obesity-associated insulin resistance.

9.
Protein Cell ; 2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34554412

RESUMO

New threats posed by the emerging circulating variants of SARS-CoV-2 highlight the need to find conserved neutralizing epitopes for therapeutic antibodies and efficient vaccine design. Here, we identified a receptor-binding domain (RBD)-binding antibody, XG014, which potently neutralizes ß-coronavirus lineage B (ß-CoV-B), including SARS-CoV-2, its circulating variants, SARS-CoV and bat SARSr-CoV WIV1. Interestingly, antibody family members competing with XG014 binding show reduced levels of cross-reactivity and induce antibody-dependent SARS-CoV-2 spike (S) protein-mediated cell-cell fusion, suggesting a unique mode of recognition by XG014. Structural analyses reveal that XG014 recognizes a conserved epitope outside the ACE2 binding site and completely locks RBD in the non-functional "down" conformation, while its family member XG005 directly competes with ACE2 binding and position the RBD "up". Single administration of XG014 is effective in protection against and therapy of SARS-CoV-2 infection in vivo. Our findings suggest the potential to develop XG014 as pan-ß-CoV-B therapeutics and the importance of the XG014 conserved antigenic epitope for designing broadly protective vaccines against ß-CoV-B and newly emerging SARS-CoV-2 variants of concern.

10.
Mov Disord ; 2021 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-34564901

RESUMO

BACKGROUND: Despite intense efforts to develop an objective diagnostic test for Parkinson's disease, there is still no consensus on biomarkers that can accurately diagnose the disease. OBJECTIVE: Identification of biomarkers for idiopathic Parkinson's disease (PD) may enable accurate diagnosis of the disease. We tried to find molecular and cellular differences in dopaminergic (DA) neurons derived from healthy subjects and idiopathic PD patients with or without rest tremor at onset. METHODS: We measured the expression of genes controlling dopamine synthesis, sequestration, and catabolism as well as the levels of corresponding metabolites and reactive oxygen species in midbrain DA neurons differentiated from induced pluripotent stem cells (iPSCs) of healthy subjects and PD patients with or without rest tremor. RESULTS: Significant differences in DA-related gene expression, metabolites, and oxidative stress were found between midbrain DA neurons derived from healthy subjects and patients with PD. DA neurons derived from PD patients with or without rest tremor at onset exhibited significant differences in the levels of some of these transcripts, metabolites, and oxidative stress. CONCLUSION: The unique combination of these quantifiable molecular and cellular traits in iPSC-derived midbrain DA neurons can distinguish healthy subjects from idiopathic PD patients and segregate PD patients with or without rest tremor at onset. The strategy may be used to develop an objective diagnostic test for PD.

11.
Adv Mater ; 33(38): e2101511, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34346100

RESUMO

Most degradations in electrocatalysis are caused by corrosion in operation, for example the corrosion of the core in a core-shell electrocatalyst during the oxygen reduction reaction (ORR). Herein, according to the in-situ study on nanoscale corrosion kinetics via liquid cell transmission electron microscopy (LC-TEM) in the authors' previous work, they sequentially designed an optimized nanocube with the protection of more layers on the corners by adjusting the Pt atom distribution on corners and terraces. This modified nanocube (MNC) is much more corrosion resistant in the in-situ observation. Furthermore, in the practical electrochemical stability testing, the MNC catalyst also showed the best stability performance with the 0.37% and 9.01% loss in specific and mass activity after 30 000 cycles accelerated durability test (ADT). This work also demonstrates that how an in-situ study can guide the design of desired materials with improved properties and build a bridge between in-situ study and practical application.

12.
Platelets ; : 1-7, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34346843

RESUMO

Stromal cell-derived factor 1 (SDF-1, also known as CXCL12) and its receptor CXCR4 have shown to play a role in the homing and engraftment of hematopoietic stem and progenitor cells. SDF-1 is highly expressed in platelets and involved in thrombosis formation. However, the exact roles of platelet-derived SDF-1 and CXCR4 in platelet activation and mitochondrial function have not been revealed yet. Deletion of Sdf-1 and Cxcr4 specifically in platelets decreased agonist-induced platelet aggregation and dramatically impaired thrombin-induced glucose uptake. In SDF-1-deficient and CXCR4-deficient platelets, intracellular ATP secretions were reduced when activated by the addition of thrombin. SDF-1 deficiency in platelets can impair the routine respiration during resting state and maximal capacity of the electron transfer system (ETS) during activated state. Mitochondrial respiration measurements in permeabilized platelets indicated an impaired function of the oxidative phosphorylation system in -SDF-1 or CXCR4-deficient platelets. These results suggested a novel role of the SDF-1/CXCR4 axis in modulating platelet energy metabolism and activation by regulating mitochondrial respiration, glucose uptake, and ATP production.

13.
Sensors (Basel) ; 21(16)2021 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-34450864

RESUMO

Magnetic flux leakage (MFL) testing has been widely used as a non-destructive testing method for various materials. However, it is difficult to separate the influences of the defect geometrical parameters such as depth, width, and length on the received leakage signals. In this paper, a "near-field" MFL method is proposed to quantify defect widths. Both the finite element modelling (FEM) and experimental studies are carried out to investigate the performance of the proposed method. It is found that that the distance between two peaks of the "near-field" MFL is strongly related to the defect width and lift-off value, whereas it is slightly affected by the defect depth. Based on this phenomenon, a defect width assessment relying on the "near-field" MFL method is proposed. Results show that relative judging errors are less than 5%. In addition, the analytical expression of the "near-field" MFL is also developed.

14.
J Cell Mol Med ; 25(15): 7462-7471, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34240802

RESUMO

Mitsugumin 53 (MG53), which is expressed predominantly in striated muscle, has been demonstrated to be a myokine/cardiokine secreted from striated muscle under specific conditions. The important roles of MG53 in non-striated muscle tissues have also been examined in multiple disease models. However, no previous study has implicated MG53 in the control of endothelial cell function. In order to explore the effects of MG53 on endothelial cells, human umbilical vein endothelial cells (HUVECs) were stimulated with recombinant human MG53 (rhMG53). Then, rhMG53 uptake, focal adhesion kinase (FAK)/Src/Akt/ERK1/2 signalling pathway activation, cell migration and tube formation were determined in vitro. The efficacy of rhMG53 in regulating angiogenesis was also detected in postnatal mouse retinas. The results demonstrated that rhMG53 directly entered into endothelial cells in a cholesterol-dependent manner. The uptake of rhMG53 directly bound to FAK in endothelial cells, which resulted in a significant decrease in FAK phosphorylation at Y397. Accompanied by the dephosphorylation of FAK, rhMG53 uncoupled FAK-Src interaction and reduced the phosphorylation of Src at Y416. Consequently, the activation of FAK/Src downstream signalling pathways, such as Akt and ERK1/2, was also significantly inhibited by rhMG53. Furthermore, rhMG53 remarkably decreased HUVEC migration and tube formation in vitro and postnatal mouse retinal angiogenesis in vivo. Taken together, these data indicate that rhMG53 inhibits angiogenesis through regulating FAK/Src/Akt/ERK1/2 signalling pathways. This may provide a novel molecular mechanism for the impaired angiogenesis in ischaemic diseases.

15.
Stem Cell Res Ther ; 12(1): 408, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-34266493

RESUMO

BACKGROUND: Accumulating evidence suggests that enhanced adipose tissue macrophages (ATMs) are associated with metabolic disorders in obesity and type 2 diabetes. However, therapeutic persistence and reduced homing stem cell function following cell delivery remains a critical hurdle for the clinical translation of stem cells in current approaches. METHODS: We demonstrate that the effect of a combined application of photoactivation and adipose-derived stem cells (ASCs) using transplantation into visceral epididymal adipose tissue (EAT) in obesity. Cultured ASCs were derived from subcutaneous white adipose tissue isolated from mice fed a normal diet (ND). RESULTS: In diet-induced obesity, implantation of light-treated ASCs improved glucose tolerance and ameliorated systemic insulin resistance. Intriguingly, compared with non-light-treated ASCs, light-treated ASCs reduced monocyte infiltration and the levels of ATMs in EAT. Moreover, implantation of light-treated ASCs exerts more anti-inflammatory effects by suppressing M1 polarization and enhancing macrophage M2 polarization in EAT. Mass spectrometry revealed that light-treated human obese ASCs conditioned medium retained a more complete secretome with significant downregulation of pro-inflammatory cytokines and chemokines. CONCLUSIONS: These data suggest that the combined application of photoactivation and ASCs using transplantation into dysfunctional adipose tissue contribute to selective suppression of inflammatory responses and protection from insulin resistance in obesity and type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Tecido Adiposo , Animais , Diabetes Mellitus Tipo 2/terapia , Glucose , Inflamação , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Células-Tronco
16.
Biomed Pharmacother ; 139: 111667, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34243608

RESUMO

Interactions between vascular smooth muscle cells (VSMCs), endothelial cells (ECs), pericytes (PCs) and macrophages (MФ), the major components of blood vessels, play a crucial role in maintaining vascular structural and functional homeostasis. Low-density lipoprotein (LDL) receptor-related protein-1 (LRP1), a transmembrane receptor protein belonging to the LDL receptor family, plays multifunctional roles in maintaining endocytosis, homeostasis, and signal transduction. Accumulating evidence suggests that LRP1 modulates vascular homeostasis mainly by regulating vasoactive substances and specific intracellular signaling pathways, including the plasminogen activator inhibitor 1 (PAI-1) signaling pathway, platelet-derived growth factor (PDGF) signaling pathway, transforming growth factor-ß (TGF-ß) signaling pathway and vascular endothelial growth factor (VEGF) signaling pathway. The aim of the present review is to focus on recent advances in the discovery and mechanism of vascular homeostasis regulated by LRP1-dependent signaling pathways. These recent discoveries expand our understanding of the mechanisms controlling LRP1 as a target for studies on vascular complications.


Assuntos
Homeostase/fisiologia , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Músculo Liso Vascular/metabolismo , Transdução de Sinais/fisiologia , Animais , Endocitose/fisiologia , Células Endoteliais/metabolismo , Humanos , Lipoproteínas LDL/metabolismo , Miócitos de Músculo Liso/metabolismo
17.
Nano Lett ; 21(15): 6625-6632, 2021 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-34319751

RESUMO

Developing a large-scale method to produce platinum (Pt)-based electrocatalysts for the oxygen reduction reaction (ORR) is highly desirable to propel the commercialization of the membrane electrode assembly (MEA). Here, we successfully report the large-scale production of surfactant-free ruthenium-doped Pt-cobalt octahedra grown on carbon (Ru-Pt3Co/C), which display a much higher ORR activity and stability and MEA stability than Pt3Co/C and Pt/C. Significantly, the in-situ X-ray absorption fine structure result reveals that Ru can drive the reduced Pt atoms to reverse to their initial state after the ORR by transferring a redundant electron from Pt to Ru, preventing the over-reduction of Pt active sites and boosting the chemical stability. Theory investigations further confirm that the doped Ru can accelerate the breach and desorption of oxygen intermediates, making it active and durable for the ORR. The present work sheds light on the exploration of a large-scale strategy for producing advanced Pt-based nanocatalysts, which may offer significant advantages for practical fuel cell applications in the future.

18.
Nano Lett ; 21(12): 5075-5082, 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34061555

RESUMO

Platinum (Pt) catalysts play a key role in energy conversion and storage processes, but the realization of further performance enhancement remains challenging. Herein, we report a new class of Pt superstructures (SSs) with surface distortion engineering by electrochemical leaching of PtTex SSs that can largely boost the oxygen reduction reaction (ORR), the methanol oxidation reaction (MOR), and the hydrogen evolution reaction (HER). In particular, the high-distortion (H)-Pt SSs achieve a mass activity of 2.24 A mg-1 at 0.90 VRHE for the ORR and 2.89 A mg-1 for the MOR as well as a low overpotential of 25.3 mV at 10 mA cm-2 for the HER. Moreover, the distorted surface features of Pt SSs can be preserved by mitigating the detrimental effects of agglomeration/degradation during long-time electrocatalysis. A multiscale modeling demonstrates that surface compressions, defects, and nanopores act in synergy for the enhanced ORR performance. This work highlights the advances of stable superstructure and distortion engineering for realizing high-performance Pt nanostructures.

19.
Materials (Basel) ; 14(11)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071421

RESUMO

An analysis was conducted on the possibility of making an assessment of the degree of plastic deformation ε in X2CrNi18-9 steel by measuring three electromagnetic diagnostic signals: the Barkhausen noise features, the impedance components in in-series LCR circuits, and the residual magnetic field components. The impact of ε on a series of different extracted features of diagnostic signals was investigated. The occurrence of two regions of sensitivity was found for all the features of the analysed signals. The two regions were separated by the following critical deformation value: ε ~ 10% for the components of the residual magnetic field and ε ~ 15% for the normalised components of impedance. As for the Barkhausen noise signal, the values were as follows: ε ~ 20% for the mean value, ε ~ 20% for the peak value of the signal envelope, and ε ~ 5% for the total number of the signal events. Metallographic tests were performed, which revealed essential changes in the microstructure of the tested material for the established critical values. The martensite transformation occurring during the plastic deformation process of X2CrNi18-9 austenitic steel process generated a magnetic phase. This magnetic phase was strong enough to relate the strain state to the values of diagnostic signals. The changes in the material electromagnetic properties due to martensitic transformation (γ → α') began much earlier than indicated by the metallographic testing results.

20.
Colloids Surf B Biointerfaces ; 205: 111899, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34098363

RESUMO

Intracellular bacterial infection is underlying many serious human disorders, leading to high morbidity and mortality. The development of safe and efficient therapeutic agents is the most effective solutions to combat intracellular bacterial infections. Recently, ultrasmall gold nanoclusters (AuNCs) have emerged as an innovative nanoantibiotics against multidrug-resistant bacterial infections due to their inherent antibacterial activity. However, the therapeutic effects of AuNCs on intracellular bacterial infections and their effects on host cells still remain unvisited. Here, we demonstrate the therapeutic potential of 4,6-diamino-2-mercaptopyrimidine-functionalized AuNCs (AuDAMP) for intracellular multidrug-resistant infections in a co-culture model of macrophages and methicillin-resistant Staphylococcus aureus (MRSA). The AuNCs were found to show a superior intracellular antibacterial capability, which can eliminate most of the MRSA phagocytosed by macrophages, and without exhibiting obvious cytotoxicity on host RAW 264.7 macrophages at tested concentrations. More importantly, treatment of AuDAMP exerts critical roles on enhancing the innate immune response to defend against pathogens invading inside the host cells and alleviating the bacterial infection-induced inflammatory response to avoid pyroptosis by up-regulating significantly xenophagy level in macrophages. Taken together, our results suggest that AuNCs hold great potential for the treatment of intracellular bacterial infections.


Assuntos
Infecções Bacterianas , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Infecções Bacterianas/tratamento farmacológico , Farmacorresistência Bacteriana Múltipla , Ouro/farmacologia , Humanos , Imunidade Celular , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/tratamento farmacológico
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