RESUMO
In the PCB process, overcoming common-mode noise radiation is critical. In past years, most studies have focused on a common-mode noise filter (CMNF) that can solve electromagnetic interference in high-speed digital systems by blocking and absorbing common-mode noise radiation. Unfortunately, connecting with any reflective common-mode noise filter (R-CMNF) and reducing the area of an absorptive common-mode noise filter (A-CMNF) are the most troublesome tasks in the PCB process. A novel equivalent circuit is proposed in this research to minimize the complexity of the design and improve accuracy. Detailed analyses of this proposed approach are entirely depicted in this article. The experiment result shows that 9% of fractional bandwidth centered at 2.25 Hz can achieve at least 90% absorption efficiency. With our proposed method, the area of A-CMNF is smaller than in state-of-the-art research.
Assuntos
RuídoRESUMO
This paper proposes a common-mode noise suppression filter scheme for use in the servers and computer systems of high-speed buses such as SATA Express, HDMI 2.0, USB 3.2, and PCI Express 5.0. The filter uses a novel series-mushroom-defected corrugated reference plane (SMDCRP) structure. The measured results are similar to the full-wave simulation results. In the frequency domain, the measured insertion loss of the SMDCRP structure filter in differential mode (DM) can be kept below -4.838 dB from DC to 32 GHz and can maintain signal integrity characteristics. The common-mode (CM) suppression performance can suppress more than -10 dB from 8.81 GHz to 32.65 GHz. Fractional bandwidth can be increased to 115%, and CM noise can be ameliorated by 55.2%. In the time domain, using eye diagram verification, the filter shows complete differential signal transmission capability and supports a transmission rate of 32 Gb/s for high-speed buses. The SMDCRP structure filter reduces the electromagnetic interference (EMI) problem and meets the quality requirements for the controllers and sensors used in the server and computer systems of high-speed buses.
Assuntos
Agaricales , Intervenção Coronária Percutânea , Simulação por Computador , Sistemas ComputacionaisRESUMO
All-solid-state batteries (ASSBs) with alloy anodes are expected to achieve high energy density and safety. However, the stability of alloy anodes is largely impeded by their large volume changes during cycling and poor interfacial stability against solid-state electrolytes. Here, a mechanically prelithiation aluminum foil (MP-Al-H) is used as an anode to construct high-performance ASSBs with sulfide electrolyte. The dense Li-Al layer of the MP-Al-H foil acts as a prelithiated anode and forms a 2D interface with sulfide electrolyte, while the unlithiated Al layer acts as a tightly bound current collector and ensures the structural integrity of the electrode. Remarkably, the MP-Al-H anode exhibits superior lithium conduction kinetics and stable interfacial compatibility with Li6 PS5 Cl (LPSCl) and Li10 GeP2 S12 electrolytes. Consequently, the symmetrical cells using LPSCl electrolyte can work at a high current density of 7.5 mA cm-2 and endure for over 1500 h at 1 mA cm-2 . Notably, ≈100% capacity is retained for the MP-Al-H||LPSCl||LiCoO2 full cell with high area loadings of 18 mg cm-2 after 300 cycles. This work offers a pathway to improve the interfacial and performance issues for the application of ASSBs.
RESUMO
Flower color, which is determined by various chemical pigments, is a vital trait for ornamental plants, in which anthocyanin is a major component. However, the epigenetic regulation of anthocyanin biosynthesis remains poorly understood. During chrysanthemum cultivation, we found a heterochromatic chrysanthemum accession (YP) whose progeny generated by asexual reproduction contained both yellow-flowered (YP-Y) and pink-flowered (YP-P) plants. In this study, we aimed to elucidate the epigenetic mechanisms of different flower colors in the YP plant progeny. Metabolome and transcriptome analyses revealed that the difference in flower color between YP-Y and YP-P was caused by expression variation of the anthocyanin biosynthesis gene CmMYB6. Bisulfite sequencing revealed that methylation at the CmMYB6 promoter, especially in the CHH context, was higher in YP-Y than YP-P. After demethylation of the CmMYB6 promoter using the dCas9-TET1cd system, the flower color returned from yellow to pink. Furthermore, the methylation status of the CmMYB6 promoter was higher in YP-Y over three consecutive generations, indicating that this methylation status was heritable mitotically. Finally, investigation of other chrysanthemum cultivars showed that the methylation of CmMYB6 decreased gradually with the increase in anthocyanin content. These results lay an epigenetic foundation for the improvement of flower color in horticultural plants.
Assuntos
Chrysanthemum , Antocianinas/metabolismo , Chrysanthemum/genética , Chrysanthemum/metabolismo , Cor , Epigênese Genética , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Pigmentação/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
Unlike modern tomato (Solanum lycopersicum) cultivars, cv. LA1996 harbors the dominant Aft allele, which is associated with anthocyanin synthesis in tomato fruit peel. However, the control of Aft anthocyanin biosynthesis remains unclear. Here, we used ethyl methanesulfonate-induced and CRISPR/Cas9-mediated mutation of LA1996 to show, respectively, that two class IIIf basic helix-loop-helix (bHLH) transcription factors, SlJAF13 and SlAN1, are involved in the control of anthocyanin synthesis. These transcription factors are key components of the MYB-bHLH-WD40 (MBW) complex, which positively regulates anthocyanin synthesis. Molecular and genetic analyses showed that SlJAF13 functions as an upstream activation factor of SlAN1 by binding directly to the G-Box motif of its promoter region. On the other hand, SlJAZ2, a JA signaling repressor, interferes with formation of the MBW complex to suppress anthocyanin synthesis by directly binding these two bHLH components. Unexpectedly, the transcript level of SlJAZ2 was in turn repressed in a SlJAF13-dependent manner. Mechanistically, SlJAF13 interacts with SlMYC2, inhibiting SlMYC2 activation of SlJAZ2 transcription, thus constituting a negative feedback loop governing anthocyanin accumulation. Taken together, our findings support a sophisticated regulatory network, in which SlJAF13 acts as an upstream dual-function regulator that fine tunes anthocyanin biosynthesis in tomato.
Assuntos
Solanum lycopersicum , Fatores de Transcrição , Antocianinas/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
BACKGROUND The purpose of this study was to evaluate the predictive values of lipid level, inflammatory biomarkers, and echocardiographic parameters in late NVAF (nonvalvular atrial fibrillation) recurrence after RFA (radiofrequency ablation). MATERIAL AND METHODS This retrospective single-center study enrolled 263 patients with paroxysmal or persistent NVAF who underwent initial RFA from Jan 2017 to Jan 2019. The patients were divided into a Recurrent group (n=70) and a Nonrecurrent group (n=193). Univariate and multivariate logistic regression analyses were used for evaluating the predictive factors of late NVAF recurrence. Receiver operating characteristic (ROC) curves were constructed to assess the predictive performance and the optimum cut-off level of variables. RESULTS Late NVAF recurrence occurred in 70 patients (26.6%) after initial RFA within 12-month follow-up. Patients in the Recurrent group had significant higher NLR (neutrophil-to-lymphocyte ratio), hs-CRP (high-sensitivity C-reactive protein), LVEDD (left ventricular end-diastolic dimension), LVESD (left ventricular end-systolic dimension), and LAD (left atrial diameter) than those in the Nonrecurrent group (P<0.05). In multivariate analysis, increased NLR (HR=1.438, 95% CI: 1.036-1.995, P<0.05), hs-CRP (HR=1.137, 95% CI: 1.029-1.257, P<0.05) and LAD (HR=1.089, 95% CI: 1.036-1.146, P<0.05) were independent predictors of NVAF recurrence. The area under the curve (AUC) of NLR and hs-CRP was 0.603 (95% CI 0.525-0.681) and 0.584 (95% CI 0.501-0.666), respectively. The combination of NLR, hs-CRP, and LAD revealed an AUC of 0.684 (95% CI 0.611-0.757), with cut-off values of 2.33, 2.025 ng/L, and 44.5 mm, respectively. CONCLUSIONS The combination of preoperative NLR, hs-CRP, and LAD can predict late NVAF recurrence.
Assuntos
Fibrilação Atrial/metabolismo , Fibrilação Atrial/cirurgia , Proteína C-Reativa/metabolismo , Linfócitos/metabolismo , Neutrófilos/metabolismo , Ablação por Radiofrequência/métodos , Idoso , Feminino , Átrios do Coração/anatomia & histologia , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Recidiva , Estudos Retrospectivos , Medição de RiscoRESUMO
OBJECTIVES: The aim of this study was to explore the correlation between blood profiles and cognitive functions or mild cognitive impairment (MCI) in the Chinese population aged 35-64 years old. METHODS: A cross-sectional study was performed, which recruited 675 Chinese adults aged 35-64 years old from Beijing, China. Their cognitive performance was assessed with Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA), the serum lipids levels were measured by hexokinase method and colorimetric assay, and the plasma fatty acids profiles were analyzed by fast gas chromatography. RESULTS: Among the 675 participants, 84 (12.4%) had MCI. Age, years of education, saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were associated with MMSE scores (all P < 0.05). Age, years of education, smoking, drinking, non-esterified fatty acids (NEFAs), SFAs, MUFAs, n-3 polyunsaturated fatty acids (n-3 PUFAs) and n-6/n-3 PUFAs were associated with MoCA scores (all P < 0.05). Increased age (P = 0.002) and smoking (P = 0.028) were positively associated with the prevalence of MCI, while educational level (P = 0.005) and alcohol drinking (P = 0.003) both were negatively correlated to the prevalence of MCI. Elevated serum NEFAs (P = 0.032), high plasma SFAs (P = 0.023), and excessive polyunsaturated fatty acids (PUFAs) levels (P = 0.033) were significantly associated with increased frequency of MCI. CONCLUSION: In the Chinese population aged 35-64 years, advanced age and cigarette smoking were risk factors of MCI, whereas higher educational level and alcohol drinking were protective factors for MCI. Excessive serum or plasma levels of NEFAs, SFAs and PUFAs were associated with an increased risk of MCI.
Assuntos
Disfunção Cognitiva/sangue , Ácidos Graxos não Esterificados/sangue , Ácidos Graxos Insaturados/sangue , Ácidos Graxos/sangue , Adulto , Povo Asiático , China , Disfunção Cognitiva/epidemiologia , Estudos Transversais , Feminino , Humanos , Masculino , Testes de Estado Mental e Demência , Pessoa de Meia-IdadeRESUMO
During the pandemic of coronavirus disease-2019 (COVID-19), medical practitioners need non-contact devices to reduce the risk of spreading the virus. People with COVID-19 usually experience fever and have difficulty breathing. Unsupervised care to patients with respiratory problems will be the main reason for the rising death rate. Periodic linearly increasing frequency chirp, known as frequency-modulated continuous wave (FMCW), is one of the radar technologies with a low-power operation and high-resolution detection which can detect any tiny movement. In this study, we use FMCW to develop a non-contact medical device that monitors and classifies the breathing pattern in real time. Patients with a breathing disorder have an unusual breathing characteristic that cannot be represented using the breathing rate. Thus, we created an Xtreme Gradient Boosting (XGBoost) classification model and adopted Mel-frequency cepstral coefficient (MFCC) feature extraction to classify the breathing pattern behavior. XGBoost is an ensemble machine-learning technique with a fast execution time and good scalability for predictions. In this study, MFCC feature extraction assists machine learning in extracting the features of the breathing signal. Based on the results, the system obtained an acceptable accuracy. Thus, our proposed system could potentially be used to detect and monitor the presence of respiratory problems in patients with COVID-19, asthma, etc.
Assuntos
COVID-19 , Processamento de Sinais Assistido por Computador , Algoritmos , Humanos , Respiração , SARS-CoV-2RESUMO
Many published studies have evaluated the association between the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) polymorphism and the risk of congenital heart disease (CHD); however, the specific conclusion is still controversial.To get a more accurate conclusion, we used a meta-analysis to evaluate the association between the MTHFR gene C677T polymorphism and the risk of CHD.Based on the design-based search strategy, a comprehensive literature search was conducted on PubMed, OVID, Cochrane Library, Embase, Wanfang, CNKI, and Web of Science. We selected the Newcastle-Ottawa Scale (NOS) to assess the quality of the included studies. We performed a heterogeneity test on the results of the study and calculated the combined odds ratios (ORs) and its corresponding 95% confidence intervals (95% CIs) under a random- or fixed-effect model. Subgroup analyses were conducted by ethnicity, source of controls, sample size, and genotyping method. Sensitivity analysis was used to insure authenticity of this meta-analysis result. Egger's test and Begg's funnel plot were performed to detect publication bias.Eventually, our meta-analysis included 15 eligible studies. We observed a significant correlation between the MTHFR C677T polymorphism and the development of CHD in the recessive model (OR: 1.35, 95% CI: 1.06-1.71, P = 0.006) for the overall population. In subgroups stratified by ethnicity and source of controls, subgroup analyses indicated similar associations in Asians and hospital-based groups, but not for Caucasians and population-based groups. Egger's test and Begg's funnel plot demonstrated no significant publication bias in our study.Our analysis identified that MTHFR C677T allele is a risk genetic for CHD development, especially in Asians compared with Caucasians.
Assuntos
Cardiopatias Congênitas/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Predisposição Genética para Doença , HumanosRESUMO
Two-dimensional (2D) mesoporous heterostructures combining ultrathin nanosheet morphology, periodic porous surface structures, and diverse hybrid compositions have become increasingly important for renewable energy storage and electronics. However, it remains a great challenge to develop a universal method to prepare 2D mesoporous heterostructures. Herein, we report a composite-micelle-directed interfacial assembly method to synthesize heterostructures of an ultrathin 2D material covered with mesoporous monolayers assembled on both sides. To demonstrate the concept, we first fabricated a new sandwichlike carbon@MXene@carbon mesoporous heterostructure through the self-assembly of exfoliated MXene nanosheets and block copolymer F127/melamine-formaldehyde resin composite micelles and subsequent thermal treatment. Finally, we demonstrate that the carbon@MXene@carbon mesoporous heterostructured nanosheets manifest remarkably enhanced electrochemical performance as a cathode material for lithium-sulfur batteries.
RESUMO
Sodium (Na) metal anodes stand out with their remarkable capacity and natural abundance. However, the dendritic Na growth, infinite dimensional changes, and low Coulombic efficiency (CE) present key bottlenecks plaguing practical applications. Here, heteroatom-doped (nitrogen, sulfur) hollow carbon fibers (D-HCF) are rationally synthesized as a nucleation-assisting host to enable a highly reversible Na metal. The "sodiophilic" functional groups introduced by the heteroatom-doping and large surface area (≈1052 m2 g-1 ) synchronously contribute to a homogenous plating morphology with dissipated local current density. High "sodiophilicity" of the D-HCF is confirmed by first-principle calculations and experimental results, where strong adsorption energy of -3.52 eV with low Na+ nucleation overpotential of 3.2 mV at 0.2 mA cm-2 is realized. As such, highly reversible plating/stripping is achieved at 1.0 mA cm-2 with average CE approximating 99.52% over 600 cycles. The as-assembled Na@D-HCF symmetric cells exhibit a prolonged lifetime for 1000 h. A full-cell paired with Na3 V2 (PO4 )3 cathode further demonstrates stable electrochemical behavior for 200 cycles at 1 C along with excellent rate performance (102 mAh g-1 at 5 C). The results clearly show the effectiveness of the D-HCF in manipulating Na+ deposition and thus the significance of nucleation control in realizing dendrite-free metal anodes.
RESUMO
Solid polymer electrolytes (SPEs)-based all-solid-state lithium-sulfur batteries (ASSLSBs) have attracted extensive research attention due to their high energy density and safe operation, which provide potential solutions to the increasing need for harnessing higher energy densities. There is little progress made, however, in the development of ASSLSBs to improve simultaneously energy density and long-term cycling life, mostly due to the "shuttle effect" of lithium polysulfide intermediates in the SPEs and the low interfacial compatibility between the metal lithium anode and the SPE. In this work, the issues of solid/solid interfacial architecturing through atomic layer deposition of Al2 O3 on poly(ethylene oxide)-lithium bis(trifluoromethanesulfonyl)imide SPE surface are effectively addressed. The Al2 O3 coating promotes the suppression of lithium dendrite formation for over 500 h. ASSLSBs fabricated with two layers of Al2 O3 -coated SPE deliver high gravimetric/areal capacity and Coulombic efficiency, as well as excellent cycling stability and extremely low self-discharge rate. This work provides not only a simple and effective approach to boost the electrochemical performances of SPE-based ASSLSBs, but also enriches the fundamental understanding regarding the underlying mechanism responsible for their performance.
RESUMO
Lithium-sulfur (Li-S) batteries are considered to be one of the most promising energy storage systems owing to their high energy density and low cost. However, their wide application is still limited by the rapid capacity fading. Herein, polydopamine (PDA)-coated N-doped hierarchical porous carbon spheres (NPC@PDA) are reported as sulfur hosts for high-performance Li-S batteries. The NPC core with abundant and interconnected pores provides fast electron/ion transport pathways and strong trapping ability towards lithium polysulfide intermediates. The PDA shell could further suppress the loss of lithium polysulfide intermediates through polar-polar interactions. Benefiting from the dual function design, the NPC/S@PDA composite cathode exhibits an initial capacity of 1331â mAh g-1 and remains at 720â mAh g-1 after 200 cycles at 0.5â C. At the pouch cell level with a high sulfur mass loading, the NPC/S@PDA composite cathode still exhibits a high capacity of 1062â mAh g-1 at a current density of 0.4â mA cm-2 .
RESUMO
BACKGROUND: There is currently no classification for acute myocardial infarction (AMI) according to left ventricular ejection fraction (LVEF). We aimed to perform a retrospective analysis of patients undergoing emergency percutaneous coronary intervention (PCI), comparing the clinical characteristics, in-hospital acute heart failure and all-cause death events of AMI patients with mid-range ejection fraction (mrEF), preserved ejection fraction (pEF) and reduced ejection fraction (rEF). MATERIAL AND METHODS: Totally 1270 patients were stratified according to their LVEF immediately after emergency PCI into pEF group (LVEF 50% or higher), mrEF group (LVEF 40%-49%) and rEF group (LVEF <40%). Kaplan-Meier curves and log rank tests were used to assess the effects of mrEF, rEF and pEF on the occurrence of acute heart failure and all-cause death during hospitalisation. The Cox proportional hazards model was used for multivariate correction. RESULTS: Compared with mrEF, rEF was an independent risk factor for acute heart failure events during hospitalisation (HR 5.01, 95% CI 3.53 to 7.11, p<0.001), and it was also an independent risk factor for all-cause mortality during hospitalisation (HR 7.05, 95% CI 4.12 to 12.1, p<0.001); Compared with mrEF, pEF was an independent protective factor for acute heart failure during hospitalisation (HR 0.49, 95% CI 0.30 to 0.82, p=0.01), and it was also an independent protective factor for all-cause death during hospitalisation (HR 0.33, 95% CI 0.11 to 0.96, p=0.04). CONCLUSIONS: mrEF patients with AMI undergoing emergency PCI share many similarities with pEF patients in terms of clinical features, but the prognosis is significantly worse than that of pEF patients, suggesting that we need to pay attention to the management of mrEF patients with AMI.
Assuntos
Causas de Morte , Mortalidade Hospitalar , Infarto do Miocárdio/terapia , Intervenção Coronária Percutânea/métodos , Volume Sistólico/fisiologia , Disfunção Ventricular Esquerda/diagnóstico por imagem , Idoso , China , Estudos de Coortes , Angiografia Coronária/métodos , Emergências , Feminino , Hospitais Universitários , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/mortalidade , Intervenção Coronária Percutânea/mortalidade , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Análise de Sobrevida , Disfunção Ventricular Esquerda/mortalidade , Disfunção Ventricular Esquerda/fisiopatologiaRESUMO
Metal-organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self-template strategy is developed to prepare MOF networks. In this work, layered double-metal hydroxide (LDH) and other layered metal hydroxides are used not only as a scaffold but also as a self-sacrificed metal source. After capturing the abundant metal cations identically from the LDH by the organic linkers, MOF networks are in situ formed. It is interesting that the MOF network-derived carbon materials retain the flake morphology and exhibit a unique honeycomb-like macroporous structure due to the confined shrinkage of the polyhedral facets. The overall properties of the carbon networks are adjustable according to the tailored metal compositions in LDH and the derived MOFs, which are desirable for target-oriented applications as exemplified by the electrochemical application in supercapacitors.
RESUMO
Whilst WRKY transcription factors are known to be involved in diverse plant responses to biotic stresses, their involvement in abiotic stress tolerance is poorly understood. OsFRDL4, encoding a citrate transporter, has been reported to be regulated by ALUMINUM (Al) RESISTANCE TRANSCRIPTION FACTOR 1 (ART1) in rice, but whether it is also regulated by other transcription factors is unknown. We define the role of OsWRKY22 in response to Al stress in rice by using mutation and transgenic complementation assays, and characterize the regulation of OsFRDL4 by OsWRKY22 via yeas one-hybrid, electrophoretic mobility shift assay and ChIP-quantitative PCR. We demonstrate that loss of OsWRKY22 function conferred by the oswrky22 T-DNA insertion allele causes enhanced sensitivity to Al stress, and a reduction in Al-induced citrate secretion. We next show that OsWRKY22 is localized in the nucleus, functions as a transcriptional activator and is able to bind to the promoter of OsFRDL4 via W-box elements. Finally, we find that both OsFRDL4 expression and Al-induced citrate secretion are significantly lower in art1 oswrky22 double mutants than in the respective single mutants. We conclude that OsWRKY22 promotes Al-induced increases in OsFRDL4 expression, thus enhancing Al-induced citrate secretion and Al tolerance in rice.
Assuntos
Alumínio/toxicidade , Proteínas de Transporte/metabolismo , Ácido Cítrico/metabolismo , Oryza/genética , Fatores de Transcrição/metabolismo , Proteínas de Transporte/genética , Oryza/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Estresse Fisiológico , Fatores de Transcrição/genéticaRESUMO
As one of the most promising energy storage devices, the practical application of lithium-sulfur batteries is limited by the low electrical conductivity of sulfur and the notable "shuttle effects" of sulfur-based electrodes. In this work, we describe a hierarchically porous N-doped zeolitic imidazolate framework-8 (ZIF-8)-derived carbon nanosphere (N-ZDC) with an outer shell and an inner honeycomb-like interconnected nanosheet network as sulfur host material for high-performance and long-term lithium-sulfur batteries. The N-ZDC serves as multilayered barrier against the dissolution of lithium polysulfides. The porously inner interconnected carbon network of the N-ZDC facilitates the electron and ion transportation, ensures a high sulfur loading, and accommodates a volume expansion of the sulfur species. As a result, the optimized N-ZDC4 /S electrodes displayed high initial specific capacities of 1343, 1182, and 698â mAh g-1 at 0.5, 1, and 2â C, respectively, and an ultraslow capacity decay of only 0.048 % per cycle at 2â C over 800 cycles. Even with a high sulfur loading of 3.1â mg cm-2 , N-ZDC4 /S still delivered a reversible capacity of 956â mAh g-1 and stabilizes at 544â mAh g-1 after 500 cycles at 0.5â C, revealing the great potential of the novel carbon nanospheres for energy storage application.
RESUMO
Mesoporous carbon can be synthesized with good control of surface area, pore-size distribution, and porous architecture. Although the relationship between porosity and supercapacitor performance is well known, there are no thorough reports that compare the performance of numerous types of carbon samples side by side. In this manuscript, we describe the performance of 13 porous carbon samples in supercapacitor devices. We suggest that there is a "critical pore size" at which guest molecules can pass through the pores effectively. In this context, the specific surface area (SSA) and pore-size distribution (PSD) are used to show the point at which the pore size crosses the threshold of critical size. These measurements provide a guide for the development of new kinds of carbon materials for supercapacitor devices.
RESUMO
Although two-dimensional (2D) carbon materials are widely investigated, a well-defined 2D carbon nanosheet with an ordered mesostructure has rarely been realized. Monolayer-ordered mesoporous carbon nanosheets (OMCNS) were prepared through confinement assembly of resol and F127 in the interlayer of montmorillonite (MONT). The nanoscale distance of the interlayer space of MONT only allow the assembly of resol and F127 in the same plane, leading to ordered mesopores perpendicular to carbon nanosheets, and favor the formation of sp2 carbon, resulting in a high degree of graphitization. The mesopores on the carbon nanosheets provide efficient ion diffusion, and the high degree of graphitization provides a fast electron-transport route, enabling OMCNS as excellent electrode materials for electric double layer capacitors.
RESUMO
Porous carbon with high specific surface area (SSA), a reasonable pore size distribution, and modified surface chemistry is highly desirable for application in energy storage devices. Herein, we report the synthesis of nitrogen-containing mesoporous carbon with high SSA (1390 m(2) g(-1)), a suitable pore size distribution (1.5-8.1 nm), and a nitrogen content of 4.7 wt % through a facile one-step self-assembly process. Owing to its unique physical characteristics and nitrogen doping, this material demonstrates great promise for application in both supercapacitors and encapsulating sulfur as a superior cathode material for lithium-sulfur batteries. When deployed as a supercapacitor electrode, it exhibited a high specific capacitance of 238.4 F g(-1) at 1 A g(-1) and an excellent rate capability (180 F g(-1), 10 A g(-1)). Furthermore, when an NMC/S electrode was evaluated as the cathode material for lithium-sulfur batteries, it showed a high initial discharge capacity of 1143.6 mA h g(-1) at 837.5 mA g(-1) and an extraordinary cycling stability with 70.3% capacity retention after 100 cycles.