Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.097
Filtrar
1.
J Colloid Interface Sci ; 596: 184-198, 2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33845226

RESUMO

HYPOTHESIS: Bulk nanobubbles are nanoscopic gaseous domains in an aqueous solution. Their surprising long-term stability remains controversial due to the widespread assumption that spherical bubbles cannot achieve stable equilibrium. To uncover the intrinsic mechanisms underlying stabilization, the thermodynamic behavior of nanobubbles in water over a wide range of temperatures is explored. EXPERIMENTS: Bulk nanobubbles with a typical radius of 50 - 200 nm are generated using acoustic cavitation. Increasing temperature significantly narrows the bubble-size distribution and their mean radius shrinks to a minimum of approx. 50 nm at 45 °C. For higher temperatures a slight increase is observed. The thermal induced shrinkage is reversible: upon cooling they return to the original state. FINDINGS: The observation can be explained with a charge-stabilization mechanism. The intricate balance of competing interactions between water self-ionization and mobility of ions on the surface gives rise to this non-monotonic dependency. Nanobubbles consequently undergo charge loss at lower temperatures and charge conservation at higher temperatures, corresponding to their shrinkage and slight expansion. With theoretical calculations, we further quantity the equilibrium properties of nanobubbles and their zeta potential under various initial conditions. The temperature-sensitive nature of bulk nanobubbles offers a vital step forward exploring and industrializing their stability.

2.
Int J Pharm ; 601: 120553, 2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33794325

RESUMO

Pancreatic cancer (PC) is an aggressive form of cancer with dense stroma and immune-suppressive microenvironment, which are the major barriers for treatment. To address such barriers, this study aimed to develop a sequential receptor-mediated mixed-charge targeted delivery system for PC based on 2-(3-((S)-5-amino-1-carboxypentyl)-ureido) pentanedioate (ACUPA-) and triphenylphosphonium (TPP+) modified nanomicelles containing ingenol-3-mebutate (I3A), which was named ACUPA-/TPP+-I3A or ACUPA/TPP-I3A. ACUPA/TPP-I3A induced immunogenic cell death (ICD), which significantly increased the number of tumor-infiltrating T lymphocytes, activated adaptive immunity, and achieved superior survival time. I3A, a novel anticancer drug, could induce PC cell necrosis to release damage-associated molecular patterns, thereby activating adaptive immunity. With certain ratios of negatively (ACUPA-) and positively (TPP+) charged ligands, ACUPA/TPP-I3A acquired a negative charge in plasma (pH 7.4, to inhibit aggregation and uptake in the circulation) and was neutral in the acidic tumor microenvironment (pH 5.0-6.0, to overcome electrostatic hindrances and facilitate transcytosis). Furthermore, neovascular endothelium-specific ACUPA enabled rapid transcytosis of ACUPA/TPP-I3A across tumor vessel walls, entering into endosome/lysosomes (pH 4.5-5.0, its charge became positive and exhibited lysosome escape). Then, ACUPA/TPP-I3A selectively targeted mitochondria, which correlated with TPP-mediated effect. Finally, I3A was released to induce ICD that activated adaptive immunity and achieved superior survival time. Therefore, reshaping of the tumor microenvironment and potentiating antitumor immunity using ACUPA-/TPP+-I3A constituted a novel strategy to prolong the survival time.

3.
Biomed Pharmacother ; : 111426, 2021 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-33762124

RESUMO

WangShiBoChiWan (WSBCW) is a commonly used Chinese herbal medicine for the treatment of functional gastrointestinal disorders. However, its preclinical efficacy and the mechanisms of action have not been adequately studied. The goals of this study were to evaluate the effects of WSBCW on gastrointestinal health and modulation of related biomarkers. Female C57BL mice were randomly assigned into one of the experimental groups consisting of the control, drug controls, and WSBCW at 40, 120, and 360 mg/kg BW. Whole gut transit, small intestinal motility, and intestinal barrier permeability were determined. The castor oil-induced diarrhea mouse model was used to determine the effect of WSBCW on the diarrhea type of irritable bowel syndrome (IBS-D). WSBCW increased whole gut transit and intestinal motility, improved intestinal permeability in healthy animals and alleviated diarrhea symptoms in IBS-D mice. WSBCW upregulated intestinal junction proteins, increased the abundance of Bifidobacterium genus, Desulfovibrio genus and inhibited Bacteroides fragillis group in the gut microbiota, increased intestinal villi lengths, and decreased blood levels of inflammatory cytokines. Our study provided preclinical evidence to verify the effectiveness of WSBCW in gastrointestinal health and elucidate mechanistic insights. The results warrant further investigations to evaluate the therapeutic efficacy of WSBCW on gastrointestinal disorders, such as IBS and IBD.

4.
Theranostics ; 11(9): 4363-4380, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33754066

RESUMO

Rationale: An improved understanding of thyroid hormone (TH) action on cholesterol metabolism will facilitate the identification of novel therapeutic targets for hypercholesterolemia. TH-regulated microRNAs (miRNAs) have been implicated in TH-controlled biological processes; however, whether and how TH-regulated miRNAs mediate the cholesterol-lowering effect of TH remains unclear. Our aim was to identify TH-regulated microRNAs that have cholesterol-lowering effects and explore the underlying mechanism. Method: Microarray and RNA-seq were performed to identify TH-regulated microRNAs and the genes regulated by mmu-miR-378-3p (miR-378) in the liver of mice, respectively. Recombinant adenoviruses encoding miR-378, Mafg, and shRNA for Mafg, antagomiR-378, liver-specific miR-378 transgenic mice, and miR-378 knockout mice were employed to investigate the roles of hepatic miR-378 and MAFG in cholesterol and bile acid homeostasis. The levels of bile salt species were determined by using UFLC-Triple-time of flight/MS. Results: Here, we show that hepatic miR-378 is positively regulated by TH. Transient overexpression of miR-378 in the liver of mice reduces serum cholesterol levels, accompanied with an increase in the expression of key enzymes in primary bile acid synthetic pathways and corresponding increases in biliary and fecal bile acid levels. Consistently, liver-specific miR-378 transgenic mice with moderate overexpression of hepatic miR-378 display decreased serum cholesterol levels and resistance to diet-induced hypercholesterolemia, while mice lacking miR-378 exhibit defects in bile acid and cholesterol homeostasis. Mechanistically, hepatic miR-378 regulates the expression of key enzymes in both classic and alternative bile acid synthetic pathways through MAFG, a transcriptional repressor, thereby modulating bile acid and cholesterol metabolism. Conclusions: TH-responsive hepatic miR-378 is capable of modulating serum cholesterol levels by regulating both the classic and alternative BA synthetic pathways. Our study not only identifies a previously undescribed role of hepatic miR-378 but also provides new cholesterol-lowering approaches.

5.
J Mol Cell Biol ; 2021 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-33751053

RESUMO

Muscle regeneration after damage or during myopathies requires a fine cooperation between myoblast proliferation and myogenic differentiation. A growing body of evidence suggests that microRNAs play critical roles in myocyte proliferation and differentiation transcriptionally. However, the molecular mechanisms underlying the orchestration are not fully understood. Here, we showed that miR-130b is able to repress myoblast proliferation and promote myogenic differentiation via targeting Sp1 transcription factor. Importantly, overexpression of miR-130b is capable of improving the recovery of damaged muscle in a freeze injury model. Moreover, miR-130b expression is declined in the muscle of muscular dystrophy patients. Thus, these results indicated that miR-130b may play a role in skeletal muscle regeneration and myopathy progression. Together, our findings suggest that the miR-130b/Sp1 axis may serve as a potential therapeutic target for the treatment of patients with muscle damage or severe myopathies.

6.
J Int Med Res ; 49(3): 300060521997718, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33752504

RESUMO

OBJECTIVE: C-X-C motif chemokine ligand 5 (CXCL5), a member of the chemokine family, is associated with remodeling of connective tissues. However, its role in formation of intrauterine adhesions (IUA) remains unclear. We aimed to investigate the expression and mechanism underlying the role of CXCL5 in IUA. METHODS: Expression of CXCL5 in IUA was detected by immunohistochemistry in a rat model of IUA and by real-time PCR and western blotting in patients with IUA. The protein levels of matrix metalloproteinase 9 (MMP9) and transcription factor p65 in human endometrial cells were assessed by western blotting after CXCL5 overexpression. RESULTS: Protein expression of CXCL5 was significantly decreased in the endometria of IUA rats compared with that of control and sham-operated rats. Real-time PCR and western blotting in patients with IUA showed similar results to those from the rat model. After overexpression, CXCL5 significantly upregulated expression of MMP9 and slightly upregulated expression of p65 in human endometrial cells. CONCLUSIONS: CXCL5 plays an important role in IUA formation after endometrial injury. We propose a molecular mechanism to explain formation of IUA, including downregulation of MMP9 by low CXCL5 expression. These findings provide valuable information for the prevention and targeted therapy of IUA.

8.
Carbohydr Polym ; 259: 117710, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33673989

RESUMO

Harmful algal blooms induce severe environmental problems. It is challenging to remove algae by the current available treatments involving complicate process and costly instruments. Here, we developed a CaO2@PEG-loaded water-soluble self-branched chitosan (CP-SBC) system, which can remove algae from water in one-step without additional instrumentation. This approach utilizes a novel flocculant (self-branched chitosan) integrated with flotation function (induced by CaO2@PEG). CP-SBC exhibited better flocculation performance than commercial flocculants, which is attributed to the enhanced bridging and sweeping effect of branched chitosan. CP-SBC demonstrated outstanding biocompatibility, which was verified by zebrafish test and algae activity test. CaO2@PEG-loaded self-branched chitosan can serve as an "Air flotation system" to spontaneous float the flocs after flocculation by sustainably released O2. Furthermore, CP-SBC can improve water quality through minimizing dissolved oxygen depletion and reducing total phosphorus concentrations.


Assuntos
Quitosana/química , Proliferação Nociva de Algas/fisiologia , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Compostos de Cálcio/química , Floculação/efeitos dos fármacos , Proliferação Nociva de Algas/efeitos dos fármacos , Cinética , Larva/efeitos dos fármacos , Óxidos/química , Oxigênio/química , Fósforo/química , Polietilenoglicóis/química , Porosidade , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/fisiologia
9.
IEEE Trans Cybern ; PP2021 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-33705335

RESUMO

We investigate a distributed time-varying formation control problem for an uncertain Euler-Lagrange system. A time-varying optimization-based approach is proposed. Based on this approach, the robots can achieve the expected formation configuration and meanwhile optimize a global objective function using only neighboring and local information. We consider the time-varying optimization where the objective functions can change in real time. In this case, the consensus-based formation tracking control issues and formation containment tracking control issues in the literature can be solved by the proposed approach. By a penalty-based method, the robots' states asymptotically converge to the estimated optimal solution to an equivalent time-varying optimization problem, whose optimal solution can achieve simultaneous formation and optimization. Furthermore, we consider two more general scenarios: 1) the local objective functions can have non-neighbor's information and 2) the optimization problems can have inequality constraints.

10.
Proc Natl Acad Sci U S A ; 118(10)2021 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-33674384

RESUMO

Convective flows coupled with solidification or melting in water bodies play a major role in shaping geophysical landscapes. Particularly in relation to the global climate warming scenario, it is essential to be able to accurately quantify how water-body environments dynamically interplay with ice formation or melting process. Previous studies have revealed the complex nature of the icing process, but have often ignored one of the most remarkable particularities of water, its density anomaly, and the induced stratification layers interacting and coupling in a complex way in the presence of turbulence. By combining experiments, numerical simulations, and theoretical modeling, we investigate solidification of freshwater, properly considering phase transition, water density anomaly, and real physical properties of ice and water phases, which we show to be essential for correctly predicting the different qualitative and quantitative behaviors. We identify, with increasing thermal driving, four distinct flow-dynamics regimes, where different levels of coupling among ice front and stably and unstably stratified water layers occur. Despite the complex interaction between the ice front and fluid motions, remarkably, the average ice thickness and growth rate can be well captured with the theoretical model. It is revealed that the thermal driving has major effects on the temporal evolution of the global icing process, which can vary from a few days to a few hours in the current parameter regime. Our model can be applied to general situations where the icing dynamics occur under different thermal and geometrical conditions.

11.
Artigo em Inglês | MEDLINE | ID: mdl-33720443

RESUMO

BACKGROUND: Liver cirrhosis is characterized by immune dysfunction contributing to malnutrition. We previously revealed neutrophil-to-lymphocyte ratio (NLR) as an indicator of disordered immune system. Herein we aimed to i) determine the optimal NLR cut-off that best predicts malnutrition risk; ii) clarify the association between NLR and nutritional status. METHODS: A total of 135 hospitalized cirrhotics were included. Immune dysfunction was evaluated by levels of serum C-reactive protein (CRP), NLR and other parameters. Malnutrition was screened by a risk score referring to Royal Free Hospital-Nutritional Prioritizing Tool (RFH-NPT). ROC curve was implemented to determine the best NLR cut-off which predicts malnutrition risk. Correlation between NLR and indicators of hepatic and physical function (handgrip strength) were also examined. Multivariable logistic regression was used to assess the association between NLR and malnutrition risk. RESULTS: ROC curve revealed that the optimum cut-off to predict malnutrition risk was NLR > 4.2 with a sensitivity of 47.2%, specificity of 81.0%, NPV of 58.0% and PPV of 74.5%, respectively. Patients with NLR > 4.2 exhibited higher RFH-NPT score, higher serum platelet-to-lymphocyte ratio, and CRP. A positive correlation was found between NLR values and CTP (r = 0.22, p = 0.010), MELD (r = 0.36, p < 0.001) and RFH-NPT score (r = 0.31, p < 0.001). NLR was a risk factor for malnutrition independently of alcoholic liver disease and presence of ascites. CONCLUSIONS: Immune dysfunction measured by NLR was associated with malnutrition risk estimated by RFH-NPT in cirrhosis. This article is protected by copyright. All rights reserved.

12.
BMC Dev Biol ; 21(1): 4, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33517884

RESUMO

BACKGROUND: Our previous study have shown that the PSMD11 protein was an important survival factor for cancer cells except for its key role in regulation of assembly and activity of the 26S proteasome. To further investigate the role of PSMD11 in carcinogenesis, we constructed a conditional exon 5 floxed allele of PSMD11 (PSMD11flx) in mice. RESULTS: It was found that homozygous PSMD11 flx/flx mice showed normal and exhibited a normal life span and fertility, and showed roughly equivalent expression of PSMD11 in various tissues, suggesting that the floxed allele maintained the wild-type function. Cre recombinase could induce efficient knockout of the floxed PSMD11 allele both in vitro and in vivo. Mice with constitutive single allele deletion of PSMD11 derived from intercrossing between PSMD11flx/flx and CMV-Cre mice were all viable and fertile, and showed apparent growth retardation, suggesting that PSMD11 played a significant role in the development of mice pre- or postnatally. No whole-body PSMD11 deficient embryos (PSMD11-/-) were identified in E7.5-8.5 embryos in uteros, indicating that double allele knockout of PSMD11 leads to early embryonic lethality. To avoid embryonic lethality produced by whole-body PSMD11 deletion, we further developed conditional PSMD11 global knockout mice with genotype Flp;FSF-R26CAG - CreERT2/+; PSMD11 flx/flx, and demonstrated that PSMD11 could be depleted in a temporal and tissue-specific manner. Meanwhile, it was found that depletion of PSMD11 could induce massive apoptosis in MEFs. CONCLUSIONS: In summary, our data demonstrated that we have successfully generated a conditional knockout allele of PSMD11 in mice, and found that PSMD11 played a key role in early and postnatal development in mice, the PSMD11 flx/flx mice will be an invaluable tool to explore the functions of PSMD11 in development and diseases.

13.
Gene Ther ; 2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33558692

RESUMO

CRISPR-Cas systems have emerged as a powerful tool to generate genetic models for studying normal and diseased central nervous system (CNS). Targeted gene disruption at specific loci has been demonstrated successfully in non-dividing neurons. Despite its simplicity, high specificity and low cost, the efficiency of CRISPR-mediated knockout in vivo can be substantially impacted by many parameters. Here, we used CRISPR-Cas9 to disrupt the neuronal-specific gene, NeuN, and optimized key parameters to achieve effective gene knockout broadly in the CNS in postnatal mice. Three cell lines and two primary neuron cultures were used to validate the disruption of NeuN by single-guide RNAs (sgRNA) harboring distinct spacers and scaffold sequences. This triage identified an optimal sgRNA design with the highest NeuN disruption in in vitro and in vivo systems. To enhance CRISPR efficiency, AAV-PHP.B, a vector with superior neuronal transduction, was used to deliver this sgRNA in Cas9 mice via neonatal intracerebroventricular (ICV) injection. This approach resulted in 99.4% biallelic indels rate in the transduced cells, leading to greater than 70% reduction of total NeuN proteins in the cortex, hippocampus and spinal cord. This work contributes to the optimization of CRISPR-mediated knockout and will be beneficial for fundamental and preclinical research.

14.
Phys Rev Lett ; 126(6): 064501, 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33635696

RESUMO

Emulsions are omnipresent in the food industry, health care, and chemical synthesis. In this Letter the dynamics of metastable oil-water emulsions in highly turbulent (10^{11}≤Ta≤3×10^{13}) Taylor-Couette flow, far from equilibrium, is investigated. By varying the oil-in-water void fraction, catastrophic phase inversion between oil-in-water and water-in-oil emulsions can be triggered, changing the morphology, including droplet sizes, and rheological properties of the mixture, dramatically. The manifestation of these different states is exemplified by combining global torque measurements and local in situ laser induced fluorescence microscopy imaging. Despite the turbulent state of the flow and the dynamic equilibrium of the oil-water mixture, the global torque response of the system is found to be as if the fluid were Newtonian, and the effective viscosity of the mixture was found to be several times bigger or smaller than either of its constituents.

15.
Biomed Res Int ; 2021: 1093702, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33564675

RESUMO

Several studies have demonstrated that chronic hepatitis delta virus (HDV) infection is associated with a worsening of hepatitis B virus (HBV) infection and increased risk of hepatocellular carcinoma (HCC). However, there is limited data on the role of HDV in the oncogenesis of HCC. This study is aimed at assessing the potential mechanisms of HDV-associated hepatocarcinogenesis, especially to screen and identify key genes and pathways possibly involved in the pathogenesis of HCC. We selected three microarray datasets: GSE55092 contains 39 cancer specimens and 81 paracancer specimens from 11 HBV-associated HCC patients, GSE98383 contains 11 cancer specimens and 24 paracancer specimens from 5 HDV-associated HCC patients, and 371 HCC patients with the RNA-sequencing data combined with their clinical data from the Cancer Genome Atlas (TCGA). Afterwards, 948 differentially expressed genes (DEGs) closely related to HDV-associated HCC were obtained using the R package and filtering with a Venn diagram. We then performed gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis to determine the biological processes (BP), cellular component (CC), molecular function (MF), and KEGG signaling pathways most enriched for DEGs. Additionally, we performed Weighted Gene Coexpression Network Analysis (WGCNA) and protein-to-protein interaction (PPI) network construction with 948 DEGs, from which one module was identified by WGCNA and three modules were identified by the PPI network. Subsequently, we validated the expression of 52 hub genes from the PPI network with an independent set of HCC dataset stored in the Gene Expression Profiling Interactive Analysis (GEPIA) database. Finally, seven potential key genes were identified by intersecting with key modules from WGCNA, including 3 reported genes, namely, CDCA5, CENPH, and MCM7, and 4 novel genes, namely, CDC6, CDC45, CDCA8, and MCM4, which are associated with nucleoplasm, cell cycle, DNA replication, and mitotic cell cycle. The CDCA8 and stage of HCC were the independent factors associated with overall survival of HDV-associated HCC. All the related findings of these genes can help gain a better understanding of the role of HDV in the underlying mechanism of HCC carcinogenesis.

16.
Artigo em Inglês | MEDLINE | ID: mdl-33624527

RESUMO

OBJECTIVES: This study was designed to investigate whether transcutaneous auricular vagal nerve stimulation (taVNS) would be able to improve major pathophysiologies of functional dyspepsia (FD) in patients with FD. METHODS: Acute: Thirty-six FD patients (21F) were studied in two sessions (taVNS and sham-ES). Physiological measurements, including gastric slow waves, gastric accommodation and autonomic functions, were assessed by the electrogastrogram (EGG), a nutrient drink test and the spectral analysis of heart rate variability derived from the electrocardiogram (ECG), respectively. Chronic: Thirty-six FD patients (25F) were randomized to receive 2-week taVNS or sham-ES. The dyspeptic symptom scales, anxiety and depression scores and the same physiological measurements were assessed at the beginning and the end of the 2-week treatment. RESULTS: Acute: In comparison with sham-ES, acute taVNS improved gastric accommodation (p=0.008), increased the percentage of normal gastric slow waves (%NSW, fasting: p=0.010; fed: p=0.007) and vagal activity (fasting: p=0.056; fed: p=0.026). Chronic:In comparison with baseline, 2-week taVNS but not sham-ES reduced symptoms of dyspepsia (p=0.010), decreased the scores of anxiety (p=0.002) and depression (p<0.001), improved gastric accommodation (p<0.001) and the %NSW (fasting: p<0.05; fed: p<0.05) by enhancing vagal efferent activity (fasting: p=0.015; fed: p=0.048). Compared with the HC, the patients showed increased anxiety (p<0.001) and depression (p<0.001), and decreased gastric accommodation (p<0.001) and %NSW (p<0.001) as well as decreased vagal activity (fasting: p=0.047). CONCLUSIONS: The noninvasive taVNS has a therapeutic potential for treating non-severe FD by improving gastric accommodation and gastric pace-making activity via enhancing vagal activity.

17.
Cell Death Dis ; 12(2): 215, 2021 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-33637686

RESUMO

Mitochondria are essential cellular organelles that are involved in regulating cellular energy, metabolism, survival, and proliferation. To some extent, cancer is a genetic and metabolic disease that is closely associated with mitochondrial dysfunction. Hypoxia-inducible factors (HIFs), which are major molecules that respond to hypoxia, play important roles in cancer development by participating in multiple processes, such as metabolism, proliferation, and angiogenesis. The Warburg phenomenon reflects a pseudo-hypoxic state that activates HIF-1α. In addition, a product of the Warburg effect, lactate, also induces HIF-1α. However, Warburg proposed that aerobic glycolysis occurs due to a defect in mitochondria. Moreover, both HIFs and mitochondrial dysfunction can lead to complex reprogramming of energy metabolism, including reduced mitochondrial oxidative metabolism, increased glucose uptake, and enhanced anaerobic glycolysis. Thus, there may be a connection between HIFs and mitochondrial dysfunction. In this review, we systematically discuss the crosstalk between HIFs and mitochondrial dysfunctions in cancer development. Above all, the stability and activity of HIFs are closely influenced by mitochondrial dysfunction related to tricarboxylic acid cycle, electron transport chain components, mitochondrial respiration, and mitochondrial-related proteins. Furthermore, activation of HIFs can lead to mitochondrial dysfunction by affecting multiple mitochondrial functions, including mitochondrial oxidative capacity, biogenesis, apoptosis, fission, and autophagy. In general, the regulation of tumorigenesis and development by HIFs and mitochondrial dysfunction are part of an extensive and cooperative network.

18.
Nanoscale ; 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33538290

RESUMO

Only a few studies have described the use of H+-attacking S-EDA in nucleophilic substitution reactions to bind frameworks and sulfur in cathode materials, which is also known as the ion-exchange method. The pros and cons of this method are still unclear in relation to lithium-sulfur battery applications. Here, the influences of two synthetic routes, a melt-diffusion method and H+ reacting with S-EDA via nucleophilic substitution, on the morphologies and electrochemical properties of cathode materials are discussed in detail based on in situ XRD and other advanced technologies. Accordingly, high S-loading is achieved when H+ reacts with S-EDA via ion exchange on the surface of acetylene black, and capacities of 693.8, 644.5, and 638.9 mA h g-1 are obtained over the first three cycles when the C/S composite is used as a cathode in coin cells without the conductive additive Super P. In situ XRD data confirm that poor electrochemical properties can mainly be attributed to the conversion rate of S species being too rapid to thoroughly utilize the S molecules that are immobilized, which means that more fixed sulfur can form during the charge/discharge process when using the ion-exchange method to make the C/S composite. In addition, a long-chain polysulfide shuttling effect is directly noticed via AFM in tapping-KPFM mode in the C/S composite that was synthesized via the melt-diffusion method, even though polar S-O bonds exist in the composite. The increase in the cathodic surface potential from 102.8 to 141.1 mV and the increase in the morphological height from 547.7 to 829.7 nm during the discharge/charge process can be attributed to the process of S loss.

19.
J Nurs Res ; 29(2): e139, 2021 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-33534354

RESUMO

BACKGROUND: The COVID-19 pandemic has affected China and other countries since December 2019. The effects of this pandemic on nursing students in terms of their professional identity, intention to leave the nursing profession, and perception of clinical nursing work remain unclear. PURPOSE: The aims of this study were, first, to investigate nursing students' professional identity, intention to leave the nursing profession, and perception of clinical nursing work during the COVID-19 pandemic and, second, to explore factors influencing professional identity to help develop effective strategies to enrich and strengthen this factor in the future. METHODS: This cross-sectional, descriptive survey study was conducted on 150 nursing students in China in February 2020. RESULTS: The 14 (9.3%) participants who reported intending to leave the nursing profession earned lower scores for professional identity than their peers who reported intending to remain. The participants who believed that the COVID-19 pandemic had made them "more passionate about clinical nursing work" earned the highest scores, followed by those who believed the pandemic had "no effect." The lowest scores were earned by those who believed clinical nursing work to be "too dangerous to engage in." COVID-19 knowledge scores, the perceived effectiveness of preventive and control measures, the number of cases seen on the day the study survey was taken, and time spent daily on COVID-19 events were the variables found to influence professional identity. CONCLUSIONS: COVID-19 outbreak is not merely a time of crisis but also an opportunity to reconstruct the professional identity of nursing students.


Assuntos
Intenção , Identificação Social , Estudantes de Enfermagem/psicologia , China/epidemiologia , Estudos Transversais , Feminino , Humanos , Masculino , Estudantes de Enfermagem/estatística & dados numéricos , Inquéritos e Questionários
20.
Immunobiology ; 226(2): 152060, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33529803

RESUMO

Staphylococcus aureus is an infectious pathogen that is relatively common, but that can cause severe disease in pregnant women and their fetus. We previously demonstrated that exposing pregnant rats to staphylococcal enterotoxin B (SEB) altered splenic CD4/CD8 T cell frequencies in their offspring. Whether prenatal SEB exposure impacts Tregs in these offspring, however, remains to be determined. As such, in this study, we intravenously injected pregnant rats with 15 µg of SEB on gestational day 16. Splenic tissue was then harvested from 1-, 3-, and 5-day-old neonatal rats and analyzed via flow cytometry to assess Treg numbers. In addition, FoxP3 expression levels were assessed via qPCR and western blotting, while FoxP3 methylation status was evaluated via methyl-DNA immunoprecipitation qPCR. Immunosuppression assays were additionally used to gauge Treg suppressive functionality. We found that exposing pregnant rats to SEB resulted in a significant increase in Treg numbers, FoxP3 expression, and Treg suppressive capacity in the spleens of both neonatal and adult offspring. In addition, total T cell, CD4+T cell, and non-Treg CD4+ T cell numbers were elevated in the spleens of offspring following prenatal SEB exposure. We additionally determined that SEB exposure resulted in a significant reduction in FoxP3 DNA methylation. Together, our results indicate that prenatal SEB exposure can markedly enhance offspring splenic Treg numbers and functionality at least in part by decreasing FoxP3 methylation.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...