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1.
Medicine (Baltimore) ; 101(2): e28320, 2022 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-35029175

RESUMO

ABSTRACT: Developmental dysplasia of the hip (DDH) is common among Chinese infants, but a lack of large-scale, multi-center epidemiological studies has made it difficult to characterize the risk factors associated with this disease.This multi-center cohort study included 19,833 Chinese infants aged 14 days to 6 months. A multi-center ultrasound protocol was used to diagnose hip abnormalities, and epidemiological data of the infants were collected through questionnaires. Categorical variables were expressed as percentages and compared using χ2 test. Multivariate analysis was performed through logistic regression.Of 19,833 infants, 345 had DDH (1.7%). DDH incidence was higher in female infants (n = 279) than in male infants (n = 66) (χ2 = 95.89, P < .05), and there were more left hip cases (n = 149) than right hip cases (n = 79) (χ2 = 12.49, P < .05). DDH incidence was statistically different amongst different age groups in months (χ2 = 451.71, P < .05), and it gradually decreased with age (P < .05). The prevalence of a positive DDH family history, breech presentation, oligohydramnios, swaddling style, and other musculoskeletal deformities was higher in the positive group than in the negative group (all P < .05). No significant differences were found in terms of delivery by cesarean section, multiple births, or premature birth between both groups.Family history, breech presentation, oligohydramnios, musculoskeletal deformities, and female sex are high-risk factors for DDH in Chinese infants. The incidence of DDH gradually decreases with age. The results of this study provide evidence for the epidemiology of infant DDH in China.

2.
Sci Total Environ ; : 152813, 2022 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-34995590

RESUMO

Redox-active biochar has been regarded as an effective additive to promote heterotrophic denitrification, yet little is known about the feasibility of adding biochar for promoting anammox performance. In this study, we investigated the effects of different biochar doses (3-14 g/L; 1.5-7.1 g/g VSS) on anammox performance. Results showed that, in a short term (40 days), biochar could enhance anammox nitrogen removal rate (NRR) and nitrogen removal efficiency (NRE) by 0-18.0% and 0.2%-11.6%, respectively; this enhancement effect increased at 3-10 g biochar/L assays and reached a plateau at 10-14 g biochar/L assays. The optimal biochar dosage was identified to be 10 g/L (5.1 g/g VSS), with the NRR and NRE being 5.6%-18.0% and 4.0%-11.6% higher than those of the control, respectively. The highest specific anammox activity was simultaneously obtained at 10 g biochar/L assay, being 51% higher than that of the control. It revealed that biochar promoted the secretion of extracellular polymeric substances (increased by 30%-40% compared with that of the control) and increased the ratio of extracellular proteins to polysaccharides as well, directly enhancing the extracellular electron transfer capacity (ETC) of anammox biomass. The increased ETC of anammox biomass would further accelerate the metabolic activities of anammox bacteria, and promote the relative abundance of anammox bacteria, i.e., Ca. Brocadia was enriched by 5.8-12.6 folds than that of the control. These results demonstrate that biochar is feasible to enhance anammox activity and nitrogen removal performance, facilitating to a fast startup and enhanced nitrogen removal of anammox system.

3.
Carbohydr Polym ; 278: 118991, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34973794

RESUMO

Liver fibrosis (LF) leads to liver failure and short survival. Liver glycogen is a hyperbranched glucose polymer, comprising individual ß particles, which can bind together to form aggregated α particles. Glycogen functionality depends on its molecular structure. This study compared the molecular structure of liver glycogen from both LF and healthy rats, and explored underlying mechanisms for observed differences. Glycogen from both groups contained α and ß particles; the LF group contained a higher proportion of ß particles, with the glycogen containing fewer long chains than seen in the control group. Both glycogen branching enzyme and glycogen phosphorylase showed a significant decrease of activity in the LF group. Transcriptomics and proteomics revealed a functional deficiency of mitochondria in the LF group, which may lead to changes in glycogen structure. These results provide for the first time an understanding of how liver fibrosis affects liver glycogen metabolism and glycogen structure. HYPOTHESIS: We hypothesized that the molecular structure of liver glycogen from a rat model of liver fibrosis would be altered compared to the control group.

4.
Int Heart J ; 62(6): 1348-1357, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34853227

RESUMO

Inward rectifier potassium channels (IK1, Kir) are known to play critical roles in arrhythmogenesis. Thus, how IK1 agonist affects reperfusion arrhythmias needs to be clarified, and its underlying mechanisms should be determined. Reperfusion arrhythmias were modeled by coronary ligation (ischemia, 15 minutes) and release (reperfusion, 15 minutes). Zacopride (1.5-50 µg/kg in vivo, or 0.1-10 µmol/Lex vivo) was applied in the settings of pretreatment (3 minutes before coronary ligation) and posttreatment (5 minutes after coronary ligation). Hypoxia (45 minutes) /reoxygenation (30 minutes) model was established in cultured H9c2 (2-1) cardiomyocytes. Zacopride or KN93 was applied before hypoxia (pretreatment). In the setting of pre- or posttreatment, zacopride at 15 µg/kg in vivo or 1 µmol/Lin vitro exhibited superlative protections on reperfusion arrhythmias or intracellular calcium overload. Western blot data from ex vivo hearts or H9c2 (2-1) cardiomyocytes showed that I/R (H/R) induced the inhibition of Kir2.1 (the dominant subunit of IK1 channel in ventricle), phosphorylation and oxidation of CaMKII, downregulation of SERCA2, phosphorylation of phospholamban (at Thr17), and activation of caspase-3. Zacopride treatment (1 µmol/L) was noted to strikingly restore the expression of Kir2.1 and SERCA2 and decrease the activity of CaMKII, phospholamban, and caspase-3. These effects were largely eliminated by co-application of IK1 blocker BaCl2. CaMKII inhibitor KN93 attenuated calcium overload and p-PLB (Thr17) in an IK1-independent manner. IK1-depedent inhibition of CaMKII activity is found to be a key cardiac salvage signaling under Ca2+ dyshomeostasis and reactive oxygen species (ROS) stress. IK1 might be a novel target for pharmacological conditioning of reperfusion arrhythmia, especially for the application after unpredictable ischemia.

5.
ACS Omega ; 6(47): 31810-31817, 2021 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-34870003

RESUMO

Uncariae Ramulus Cum Uncis, known as "Gou-Teng" in Chinese, is derived mainly from the dried hook-bearing stems of Uncaria rhynchophylla. Quantitative determination of monoterpenoid indole alkaloids is critical for controlling its quality. In the present study, a rapid, accurate, and precise method was developed for the simultaneous quantitation of four characteristic components, namely, rhynchophylline (1), isorhynchophylline (2), corynoxeine (3), and isocorynoxeine (4), through 1H NMR spectrometry techniques. This method was performed on a 600 MHz NMR spectrometer with optimized acquisition parameters for performing quantitative experiments within 14 min. The highly deshielded signal of NH was at δH 10-11 in the aprotic solvent DMSO-d 6, which enables satisfactory separation of the signals to be integrated. Validation of the quantitative method was also performed in terms of specificity, linearity, sensitivity, accuracy, and precision. The method is linear in the concentration range of 25-400 µg/mL. The lower limit of quantification is 25 µg/mL. The intra- and interday relative standard deviation across three validation runs over the entire concentration range is less than 2.51%. The accuracy determined at three concentrations was within ±4.4% in terms of relative error. The proposed qNMR method was demonstrated to be a powerful tool for quantifying the alkaloids in traditional Chinese medicines (TCMs) due to its unique advantages of high precision, rapid analysis, and nonrequirement of standard compounds for calibration curve preparation. Moreover, qNMR represents a feasible alternative to high-performance liquid chromatography-based methods for the quality control of TCMs.

6.
Tree Physiol ; 2021 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-34962272

RESUMO

Plant nitrogen (N) uptake is affected by plant-plant interactions, but the mechanisms remain unknown. 15N-labeled technique was used in a pot experiment to analyze the uptake rate of ammonium (NH4+) and nitrate (NO3-) by Abies faxoniana and Picea asperata in single-plant mode, intraspecific and interspecific interactions. The results indicated that the effects of plant-plant interactions on N uptake rate depended on plant species and N forms. P. asperata had a higher N uptake rate of both N forms than A. faxoniana, and both species preferred NO3-. Compared with single-plant mode, intraspecific interaction increased NH4+ uptake for A. faxoniana but reduced that for P. asperata, while it did not change NO3- uptake for two species. The interspecific interaction enhanced N uptake of both N forms for A. faxoniana but did not affect the P. asperata, compared with single-plant mode. NH4+ and NO3- uptake rates for two species were regulated by root N concentration, root nitrate reductase activity, root vigor, soil pH, and soil N availability under plant-plant interactions. Decreased NH4+ uptake rate for P. asperata under intraspecific interaction was induced by lower root N concentration and nitrate reductase activity. The positive effects of interspecific interaction on N uptake for A. faxoniana could be determined mainly by positive rhizosphere effects, such as high soil pH. From the perspective of root-soil interactions, our study provides insight into how plant-plant interactions affect N uptake, which can help to understand species coexistence and biodiversity maintenance in forest ecosystems.

7.
Small Methods ; 5(10): e2100573, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34927938

RESUMO

Atomic-level design and construction of synergistic active centers are central to develop advanced oxygen electrocatalysts toward efficient energy conversion. Herein, an in situ construction strategy to introduce flexible redox sites of VNi centers onto Ni-based metal-organic framework (MOF) nanosheet arrays (NiV-MOF NAs) as a promising oxygen electrocatalyst is developed. The abundant redox VNi centers with flexible metal valence states of V+3/+4/+5 and Ni+3/+2 enable NiV-MOF NAs excellent oxygen evolution reaction (OER) activity and a long-term stability under high current densities, achieving current densities of 10 and 100 mA cm-2 at recorded overpotentials of 189 and 290 mV, respectively, and showing ignorable decay of initial activity at 100 mA cm-2 after 100 h OER operation. Operando synchrotron radiation Fourier transform infrared combined with quasi in situ X-ray absorption fine structure spectroscopies reveal at atomic level that the flexible V sites can continuously accept electrons from adjacent active Ni sites to accelerate OER kinetics for NiV-MOF NAs during the reaction process, accompanied by a self-optimized structural distortion of VO6 octahedron for promoting the electrochemical stability.

8.
Sleep Breath ; 2021 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-34845629

RESUMO

PURPOSE: Pregnant women are predisposed to obstructive sleep apnea (OSA). Based on the fact that OSA is an independent risk factor for hypertension among the general population, we hypothesized that chronic intermittent hypoxia (CIH), as a feature of OSA, may lead to preeclampsia. METHODS: Pregnant and non-pregnant C57BL/6 J mice were exposed to two conditions of chronic intermittent hypoxia: CIH1 (21-5% O2 alternations), CIH2 (21-10% O2 alternations), and room air until day 19. RESULTS: In non-pregnant mice, compared with their respective baseline values, systolic blood pressure (SBP) started to rise from day 14 in the CIH1 group, and SBP rose until day 19 in the CIH2 group. Compared with the pregnant mice exposed to room air, pregnant mice exposed to CIH1 maintained elevated SBP from day 14, accompanied by proteinuria, fetal and placental growth restriction, and a reduction in the number of fetuses. An imbalance between proangiogenic and antiangiogenic factors and impairment of vascular remodeling existed in the placenta of pregnant mice exposed to CIH1. Maternal serum levels of the soluble form of vascular endothelial growth factor receptor-1 were also significantly increased. Pregnant mice exposed to CIH2 seemed to have milder changes than pregnant mice exposed to CIH1. CONCLUSION: Our results demonstrated that gestational CIH may induce gestational hypertension, proteinuria, fetal and placental growth restriction as well as impairments in placental angiogenesis and vascular remodeling.

9.
Plant Cell Rep ; 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34820714

RESUMO

KEY MESSAGE: Nine RcBURPs have been identified in Rosa chinensis, and overexpression of RcBURP4 increased ABA, NaCl sensitivity, and drought tolerance in transgenic Arabidopsis. BURP proteins are unique to plants and may contribute greatly to growth, development, and stress responses of plants. Despite the vital role of BURP proteins, little is known about these proteins in rose (Rosa spp.). In the present study, nine genes belonging to the BURP family in R. chinensis were identified using multiple bioinformatic approaches against the rose genome database. The nine RcBURPs, with diverse structures, were located on all chromosomes of the rose genome, except for Chr2 and Chr3. Phylogenic analysis revealed that these RcBURPs can be classified into eight subfamilies, including BNM2-like, PG1ß-like, USP-like, RD22-like, BURP-V, BURP-VI, BURP-VII, and BURP-VIII. Conserved motif and exon-intron analyses indicated a conserved pattern within the same subfamily. The presumed cis-regulatory elements (CREs) within the promoter region of each RcBURP were analyzed and the results showed that all RcBURPs contained different types of CREs, including abiotic stress-, light response-, phytohormones response-, and plant growth and development-related CREs. Transcriptomic analysis revealed that a BURP-V member, RcBURP4, was induced in rose leaves and roots under mild and severe drought treatments. We then overexpressed RcBURP4 in Arabidopsis and examined its role under abscisic acid (ABA), NaCl, polyethylene glycol (PEG), and drought treatments. Nine stress-responsive genes expression were changed in RcBURP4-overexpressing leaves and roots. Furthermore, RcBURP4-silenced rose plants exhibited decreased tolerance to dehydration. The results obtained from this study provide the first comprehensive overview of RcBURPs and highlight the importance of RcBURP4 in rose plant.

10.
Zhongguo Ying Yong Sheng Li Xue Za Zhi ; 37(5): 534-537, 2021 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-34816668

RESUMO

Objective: To investigate the effects of Sitagliptin on myocardial remodeling and autophagy in diabetic mice and its possible mechanisms. Methods: C57 mice aged ten weeks were treated with streptozocin (STZ) at the dose of 50 mg/(kg·d) by intraperitoneal injections for five consecutive days, and the level of fasting blood glucose concentration was higher than 16.7 mmol/l after seven days indicated that the diabetic model was established successfully. Mice were divided into four groups, including control group (n=10) which was intraperitoneally injected with the same volum of saline, the model group (n=8), Sitagliptin treatment group(diabetic mice were treated with Sitagliptin at the dose of 10 mg/(kg·d)by gavage, n=8) and the inhibitor group(diabetic mice were treated with Compound C, an AMPK inhibitor, at the dose of 10 mg/(kg·d) by intraperitoneal injection, n=8). After six weeks, all the mices were weighted and then put to death and the hearts were separated to caculate ventricular /body weight ratio. Hemaloxylin-Eosin (HE) staining was used to observe the cell morphology and masson staining was used to observe interstitial fibrosis. Western blot was used to test the heart protein expressions of Connexin43(Cx43), adenosine 5'-monophosphate -activated protein kinase (AMPK), brain natriuretic peptide(BNP), transforming growth factor(TGF-ß) and LC3B. Results: After six weeks of treatment, compared with control group, the ventricular /body weight ratio was improved (P<0.05), The cardiomyocyte hypertrophy and increased fibrosis were observed in the model group. The expression levels of BNP and TGF-ß were increased, while the expression levels of Cx43,LC3B and AMPK were decreased significantly(P<0.05). However, compared with model group, treatment with Sitagliptin decreased BNP, TGF-ß protein levels and increased Cx43 and LC3B protein levels, while Compound C could inhibit the upregulation of Cx43, LC3B and AMPK protein (P<0.05). Conclusion: Sitagliptin could improve cardiac hypertrophy and decrease interstitial fibrosis and AMPK-related signaling pathways was involved in the regulation of Cx43 and autophagy.


Assuntos
Diabetes Mellitus Experimental , Fosfato de Sitagliptina , Animais , Autofagia , Diabetes Mellitus Experimental/tratamento farmacológico , Camundongos , Miocárdio , Fosfato de Sitagliptina/farmacologia , Estreptozocina
11.
Int J Biol Sci ; 17(15): 4426-4441, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34803508

RESUMO

As a promising biotechnology, fish germ cell transplantation shows potentials in conservation germplasm resource, propagation of elite species, and generation of transgenic individuals. In this study, we successfully transplanted the Japanese flounder (P. olivaceus), summer flounder (P. dentatus), and turbot (S. maximus) spermatogonia into triploid Japanese flounder larvae, and achieved high transplantation efficiency of 100%, 75-95% and 33-50% by fluorescence tracking and molecular analysis, respectively. Eventually, donor-derived spermatozoa produced offspring by artificial insemination. We only found male and intersex chimeras in inter-family transplantations, while male and female chimeras in both intra-species and intra-genus transplantations. Moreover, the intersex chimeras could mature and produce turbot functional spermatozoa. We firstly realized inter-family transplantation in marine fish species. These results demonstrated successful spermatogonial stem cells transplantation within Pleuronectiformes, suggesting the germ cells migration, incorporation and maturation within order were conserved across a wide range of teleost species.

12.
Planta ; 254(6): 118, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34757465

RESUMO

MAIN CONCLUSION: A total of 27 rose thaumatin-like protein (TLP) genes were identified from the rose genome through bioinformatics analyses. RcTLP6 was found to confer salinity stress tolerance in rose. Thaumatin-like proteins (TLPs) play critical roles in regulating many biological processes, including abiotic and biotic stress responses in plants. Here, we conducted a genome-wide screen of TLPs in rose (Rosa chinensis) and identified 27 RcTLPs. The identified RcTLPs, as well as other TLPs from six different plant species, were placed into nine groups based on a phylogenetic analysis. An analysis of the intron-exon structures of the TLPs revealed a high degree of similarity. RcTLP genes were found on all chromosomes except for chromosome four. Cis-regulatory elements (CEs) were identified in the promoters of all RcTLPs, including CEs associated with growth, development and hormone-responsiveness, as well as abiotic and biotic responses, indicating they play diverse roles in rose. Transcriptomics analysis revealed that RcTLPs had tissue-specific expression patterns, and several root-preferential RcTLPs were responsive to drought and salinity stress. Quantitative PCR analysis of six RcTLPs under ABA, PEG and NaCl treatment confirmed the differentially expressed genes identified in the transcriptomics experiment. In addition, silencing RcTLP6 in rose leaves led to decreased tolerance to salinity stress. We also screened proteins which may interact with RcTLP6 to understand its biological roles. This study represents the first report of the TLP gene family in rose and expands the current understanding of the role that RcTLP6 plays in salt tolerance. These findings lay a foundation for future utilization of RcTLPs to improve rose abiotic stress tolerance.


Assuntos
Rosa , Secas , Regulação da Expressão Gênica de Plantas , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Rosa/genética , Tolerância ao Sal/genética , Estresse Fisiológico/genética
13.
J Xray Sci Technol ; 2021 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-34719471

RESUMO

High-energy, high-dose, microfocus X-ray computed tomography (HHM CT) is one of the most effective methods for high-resolution X-ray radiography inspection of high-density samples with fine structures. Minimizing the effective focal spot size of the X-ray source can significantly improve the spatial resolution and the quality of the sample images, which is critical and important for the performance of HHM CT. The objective of this study is to present a 9 MeV HHM CT prototype based on a high-average-current photo-injector in which X-rays with about 70µm focal spot size are produced via using tightly focused electron beams with 65/66µm beam size to hit an optimized tungsten target. In digital radiography (DR) experiment using this HHM CT, clear imaging of a standard 0.1 mm lead DR resolution phantom reveals a resolution of 6 lp/mm (line pairs per mm), while a 5 lp/mm resolution is obtained in CT mode using another resolution phantom made of 10 mm ferrum. Moreover, comparing with the common CT systems, a better turbine blade prototype image was obtained with this HHM CT system, which also indicates the promising application potentials of HHM CT in non-destructive inspection or testing for high-density fine-structure samples.

14.
Allergy ; 2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34735742

RESUMO

BACKGROUND: Recent studies have revealed that the nasal microbiota in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) is profoundly altered and is correlated with systemic inflammation. However, little is known regarding whether the microbiota can be utilized to predict nasal polyp recurrence. This study is aimed to determine whether altered nasal microbiota constituents could be used as biomarkers to predict CRSwNP recurrence. METHODS: Nasal microbiota constituents were quantified and characterized using bacterial 16S ribosomal RNA gene sequencing. Selected features for least absolute shrinkage and selection operator regression-based predictors were the nasal microbiota community composition and CRSwNP patient clinical characteristics. The primary outcome was recurrence, which was determined post-admission. RESULTS: By distinguishing recurrence-associated nasal microbiota taxa and exploiting the distinct nasal microbiota abundance between patients with recurrent and non-recurrent CRSwNP, we developed a predictive classifier for the diagnosis of nasal polyps' recurrence with 91.4% accuracy. CONCLUSIONS: Key taxonomical features of the nasal microbiome could predict recurrence in CRSwNP patients. The nasal microbiome is an understudied source of clinical variation in CRSwNP and represents a novel therapeutic target for future prevention and treatment.

15.
BMC Pediatr ; 21(1): 429, 2021 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-34592941

RESUMO

BACKGROUND: Z score utility is emphasized in classifying coronary artery lesions in Kawasaki disease patients. The present study is the largest such multicenter Chinese pediatric study about coronary artery diameter reference values and Z score regression equation to date. It is useful in Chinese pediatric echocardiography. METHODS: A multicenter cohort was assembled, which consisted of 852 healthy children between 1 month and 17 years of age, ten children were excluded because their ultrasound images were not clear, or lost in following up. Diameters of the right coronary artery, left coronary artery, and left anterior descending coronary artery were assessed using echocardiography. Data were body surface area (BSA)-corrected using BSA calculated via either the Stevenson BSA formula or the Haycock BSA formula. Coronary artery diameter reference values and Z score regression equations were established for use in the Chinese pediatric population. RESULTS: No difference was observed between coronary artery diameter data corrected using BSAste or BSAhay. Of the five assessed regression models, the exponential model exhibited the best fit and was therefore selected as the basis for derivation of the SZ method. When comparing Z scores, those produced by the SZ method conformed to the standard normal distribution, while those produced by the D method did not. In addition, there was a statistically significant difference between Z scores produced by the SZ and D methods (P < 0.05). CONCLUSIONS: Coronary artery diameter reference values for echocardiography were successfully established for use in the Chinese pediatric population, and a Z score regression equation more suitable for clinical use in this population was successfully developed.


Assuntos
Vasos Coronários , Ecocardiografia , Criança , China , Estudos de Coortes , Vasos Coronários/diagnóstico por imagem , Humanos , Lactente , Estudos Prospectivos , Valores de Referência
16.
Sleep Breath ; 2021 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-34657273

RESUMO

PURPOSE: Many studies have shown that chitinase-3-like protein 1 (CHI3L1), also known as YKL-40, is associated with asthma. The purpose of this meta-analysis was to evaluate the role of serum YKL-40 in the diagnosis and differential diagnosis of asthma, severity grading, and determination of disease state. METHODS: The PubMed, Ovid, and Cochrane databases were searched. A total of 17 articles involving 5696 subjects were included in this meta-analysis. RESULTS: The results showed that the level of YKL-40 was significantly higher in asthmatic patients than in the normal group regardless of age and residential location, and increased with severity and acute exacerbation (p < 0.05). YKL-40 levels were significantly different between chronic obstructive pulmonary disease (COPD) and asthma, and also between asthma-COPD overlap syndrome (ACO) and asthma (p < 0.05). CONCLUSION: YKL-40 may act as a potential serological marker for the diagnosis of asthma, assessment of severity, indicator of the disease state, and differential diagnosis of COPD, ACO, and asthma.

17.
Artigo em Inglês | MEDLINE | ID: mdl-34716639

RESUMO

Accurately regulating the selectivity of the oxygen reduction reaction (ORR) is crucial to renewable energy storage and utilization, but challenging. A flexible alteration of ORR pathways on atomically dispersed Zn sites towards high selectivity ORR can be achieved by tailoring the coordination environment of the catalytic centers. The atomically dispersed Zn catalysts with unique O- and C-coordination structure (ZnO3 C) or N-coordination structure (ZnN4 ) can be prepared by varying the functional groups of corresponding MOF precursors. The coordination environment of as-prepared atomically dispersed Zn catalysts was confirmed by X-ray absorption fine structure (XAFs). Notably, the ZnN4 catalyst processes a 4 e- ORR pathway to generate H2 O. However, controllably tailoring the coordination environment of atomically dispersed Zn sites, ZnO3 C catalyst processes a 2 e- ORR pathway to generate H2 O2 with a near zero overpotential and high selectivity in 0.1 M KOH. Calculations reveal that decreased electron density around Zn in ZnO3 C lowers the d-band center of Zn, thus changing the intermediate adsorption and contributing to the high selectivity towards 2 e- ORR.

18.
Small ; 17(49): e2105231, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34713574

RESUMO

Accurately manipulating the electronic structure of metal active sites under working conditions is central to developing efficient and stable electrocatalysts in industrial water-alkali electrolyzers. However, the lack of an intuitive means to capture the evolution of metal sites during the reaction state inhibits the manipulation of its electronic structure. Here, atomically dispersed Ru single-sites on cobalt nanoparticles confined onto macro-microporous frameworks (M-Co NPs@Ru SAs/NC) with tunable electron coupling effect for efficient catalysis of alkaline hydrogen evolution reaction (HER) are constructed. Using operando X-ray absorption and infrared spectroscopies, a dynamic CoRu bond shrinkage with strong electron coupling effect under working conditions is identified, which significantly promotes the adsorption of water molecules and then accelerates its dissociation to form the key H* over Ru sites for high HER activity. The well-designed M-Co NPs@Ru SAs/NC delivers efficient HER performance with a small overpotential of 34 mV at 10 mA cm-2 and a high turnover frequency of ≈4284 H2  h-1 at -0.05 V, 40 times higher than that of the benchmark Pt/C. This work provides a new point of view to manipulate the electronic structure of the metal active sites for highly effective electrocatalysis processes.

19.
Nat Commun ; 12(1): 6118, 2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34675195

RESUMO

Uncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N4 structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H2O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A gmetal-1 and a large turnover frequency of 5110 h-1 at a low overpotential of 216 mV (10 mA cm-2), 480-510 times larger than those of the commercial IrO2. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium.

20.
PeerJ ; 9: e12086, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34567842

RESUMO

Background: Kidney renal clear cell carcinoma (KIRC) is the most common subtype of kidney cancer. Inorganic pyrophosphatase (PPA2) is an enzyme that catalyzes the hydrolysis of pyrophosphate to inorganic phosphate; few studies have reported its significance in cancers. Therefore, we aimed to explore the prognostic value of PPA2 in KIRC. Methods: PPA2 expression was detected via immunohistochemistry in a tissue chip containing specimens from 150 patients with KIRC. We evaluated the correlation between PPA2 expression, clinicopathological characteristics, and survival. Data from online databases and another cohort (paraffin-embedded specimens from 10 patients with KIRC) were used for external validation. Results: PPA2 expression was significantly lower in KIRC tissues than in normal renal tissues (p < 0.0001). Low expression of PPA2 was significantly associated with a high histologic grade and poor prognosis. The differential expression of PPA2 was validated at the gene and protein levels. Multivariate Cox regression analysis showed that PPA2 expression was an independent prognostic factor in patients with KIRC. Gene set enrichment analysis suggested that decreased expression of PPA2 might be related to the epithelial-mesenchymal transition in KIRC. Conclusions: Our study demonstrated that PPA2 is an important energy metabolism-associated biomarker correlated with a favorable prognosis in KIRC.

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