Relationship between the Pre-ECMO and ECMO Time and Survival of Severe COVID-19 Patients: A Systematic Review and Meta-Analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is the etiology of acute respiratory distress syndrome (ARDS). Extracorporeal membrane oxygenation (ECMO) is used to support gas exchange in patients who have failed conventional mechanical ventilation. However, there is no clear consensus on the timing of ECMO use in severe COVID-19 patients. OBJECTIVE: The aim of this study is to compare the differences in pre-ECMO time and ECMO duration between COVID-19 survivors and non-survivors and to explore the association between them. METHODS: PubMed, the Cochrane Library, Embase, and other sources were searched until 21 October 2022. Studies reporting the relationship between ECMO-related time and COVID-19 survival were included. All available data were pooled using random-effects methods. Linear regression analysis was used to determine the correlation between pre-ECMO time and ECMO duration. The meta-analysis was registered with PROSPERO under registration number CRD42023403236. RESULTS: Out of the initial 2473 citations, we analyzed 318 full-text articles, and 54 studies were included, involving 13,691 patients. There were significant differences between survivors and non-survivors in the time from COVID-19 diagnosis (standardized mean difference (SMD) = -0.41, 95% confidence interval (CI): [-0.53, -0.29], p < 0.00001), hospital (SMD = -0.53, 95% CI: [-0.97, -0.09], p = 0.02) and intensive care unit (ICU) admission (SMD = -0.28, 95% CI: [-0.49, -0.08], p = 0.007), intubation or mechanical ventilation to ECMO (SMD = -0.21, 95% CI: [-0.32, -0.09], p = 0.0003) and ECMO duration (SMD = -0.18, 95% CI: [-0.30, -0.06], p = 0.003). There was no statistical association between a longer time from symptom onset to ECMO (hazard ratio (HR) = 1.05, 95% CI: [0.99, 1.12], p = 0.11) or time from intubation or mechanical ventilation (MV) and the risk of mortality (highest vs. lowest time groups odds ratio (OR) = 1.18, 95% CI: [0.78, 1.78], p = 0.42; per one-day increase OR = 1.14, 95% CI: [0.86, 1.52], p = 0.36; HR = 0.99, 95% CI: [0.95, 1.02], p = 0.39). There was no linear relationship between pre-ECMO time and ECMO duration. CONCLUSION: There are differences in pre-ECMO time between COVID-19 survivors and non-survivors, and there is insufficient evidence to conclude that longer pre-ECMO time is responsible for reduced survival in COVID-19 patients. ECMO duration differed between survivors and non-survivors, and the timing of pre-ECMO does not have an impact on ECMO duration. Further studies are needed to explore the association between pre-ECMO and ECMO time in the survival of COVID-19 patients.

The regulation of circRNA and lncRNAprotein binding in cardiovascular diseases: Emerging therapeutic targets.

Noncoding ribonucleic acids (ncRNAs) are a class of ribonucleic acids (RNAs) that carry cellular information and perform essential functions. This class encompasses various RNAs, such as small nuclear ribonucleic acids (snRNA), small interfering ribonucleic acids (siRNA) and many other kinds of RNA. Of these, circular ribonucleic acids (circRNAs) and long noncoding ribonucleic acids (lncRNAs) are two types of ncRNAs that regulate crucial physiological and pathological processes, including binding, in several organs through interactions with other RNAs or proteins. Recent studies indicate that these RNAs interact with various proteins, including protein 53, nuclear factor-kappa B, vascular endothelial growth factor, and fused in sarcoma/translocated in liposarcoma, to regulate both the histological and electrophysiological aspects of cardiac development as well as cardiovascular pathogenesis, ultimately leading to a variety of genetic heart diseases, coronary heart disease, myocardial infarction, rheumatic heart disease and cardiomyopathies. This paper presents a thorough review of recent studies on circRNA and lncRNAprotein binding within cardiac and vascular cells. It offers insight into the molecular mechanisms involved and emphasizes potential implications for treating cardiovascular diseases.

Prevalence estimates of the insulin resistance and associated prevalence of heart failure among United Status adults.

BACKGROUND: The triglyceride glucose (TyG) index, a metric for estimating insulin resistance (IR), is linked with cardiovascular disease (CVD) morbidity and mortality among the population regardless of diabetic status. However, IR prevalence and the association between the TyG index and heart failure (HF) in Americans is unclear. METHODS: The Nation Health and Nutrition Examination Survey (NHANES) (2009-2018) dataset was used. IR was defined by homeostatic model assessment of insulin resistance (HOMA-IR) > 2.0 and 1.5. The TyG index was calculated as Ln [fasting triglycerides (mg/dL) × fasting glucose (mg/dL)/2]. A weighted logistic regression was applied to evaluate the association between the TyG index and the prevalence of HF. RESULTS: This study comprised 12,388 people, including 322 (2.6%) individuals with HF. The average prevalence of IR was found to be 13.9% and 22.7% for cutoff values greater than 2.0 and 1.5, respectively. HOMA-IR and the TyG index showed a moderate correlation (r = 0.30). There is a significant positive association between the TyG index and HF prevalence (per 1-unit increment; adjusted OR [aOR]: 1.34; 95% confidence interval [CI]: 1.02-1.76). Patients with higher TyG values were associated with a prevalence of HF (OR:1.41; 95% CI: 1.01,1.95) (quartiles 4 vs 1-3). The TyG index is associated with a higher prevalence of dyslipidemia, coronary heart disease, and hypertension but not a stroke (cerebrovascular disease). CONCLUSIONS: Our results show that IR does not considerably increase from 2008 to 2018 in American adults. A moderate correlation is noted between HOMA-IR and the TyG index. TyG index is associated with the prevalence of HF, as were other cardiovascular diseases.

Is There a Sex Difference in the Prognosis of Hypertrophic Cardiomyopathy? A Systematic Review and Meta-Analysis.

Background It is still unclear whether there is a sex difference in the prognosis of patients with hypertrophic cardiomyopathy (HCM). Therefore, we performed a meta-analysis to elucidate the association between sex and adverse outcomes in patients with HCM. Methods and Results The PubMed, Cochrane Library, and Embase databases were used to search for studies on sex differences in prognosis in patients with HCM up to August 17, 2021. Summary effect sizes were calculated using a random effects model. The protocol was registered in PROSPERO (International prospective register of systematic reviews) (registration number- CRD42021262053). A total of 27 cohorts involving 42 365 patients with HCM were included. Compared with male subjects, female subjects had a higher age at onset (mean difference=5.61 [95% CI, 4.03-7.19]), a higher left ventricular ejection fraction (standard mean difference=0.09 [95% CI, 0.02-0.15]) and a higher left ventricular outflow tract gradient (standard mean difference=0.23 [95% CI, 0.18-0.29]). The results showed that compared with male subjects with HCM, female subjects had higher risks of HCM-related events (risk ratio [RR]=1.61 [95% CI, 1.33-1.94], I2=49%), major cardiovascular events (RR=3.59 [95% CI, 2.26-5.71], I2=0%), HCM-related death (RR=1.57 [95% CI, 1.34-1.82], I2=0%), cardiovascular death (RR=1.55 [95% CI, 1.05-2.28], I2=58%), noncardiovascular death (RR=1.77 [95% CI, 1.46-2.13], I2=0%) and all-cause mortality (RR=1.43 [95% CI, 1.09-1.87], I2=95%), but not atrial fibrillation (RR=1.13 [95% CI, 0.95-1.35], I2=5%), ventricular arrhythmia (RR=0.88 [95% CI, 0.71-1.10], I2=0%), sudden cardiac death (RR=1.04 [95% CI, 0.75-1.42], I2=38%) or composite end point (RR=1.24 [95% CI, 0.96-1.60], I2=85%). Conclusions Based on current evidence, our results show significant sex-specific differences in the prognosis of HCM. Future guidelines may emphasize the use of a sex-specific risk assessment for the diagnosis and management of HCM.

Depressive symptoms, anxiety and social stress are associated with diminished cardiovascular reactivity in a psychological treatment-naive population.

BACKGROUND: There is now an increasing appreciation of how psychological health can contribute to cardiovascular disease, called the mind-heart connection. A blunted cardiovascular reactivity to depression and anxiety may be responsible for the potential mechanism, however, with inconsistent results. Anti-psychological drugs have an effect on the cardiovascular system and, thus, may disturb their relationship. However, in treatment-naive individuals with psychological symptoms, no research has specifically evaluated the relationship between psychological state and cardiovascular reactivity. METHODS: We included 883 treatment-naive individuals who came from a longitudinal cohort study of Midlife in the United States. Symptoms of depression, anxiety, and stress were assessed by the Center for Epidemiologic Studies Depression Scale (CES-D), Spielberger Trait Anxiety Inventory (STAI), the Liebowitz Social Anxiety scale (LSAS) and the Perceived Stress Scale (PSS), respectively. Cardiovascular reactivity was measured using standardized, laboratory-based stressful tasks. RESULTS: Treatment-naive individuals with depressive symptoms (CES-D ≥ 16), anxiety symptoms (STAI ≥ 54), and higher stress levels (PSS ≥ 27) had lower cardiovascular reactivity as assessed by systolic blood pressure (SBP) reactivity, diastolic blood pressure (DBP) reactivity and heart rate (HR) reactivity (P < 0.05). Pearson analyses showed that psychological symptoms were correlated with lower SBP reactivity, DBP reactivity, and heart rate reactivity (P < 0.05). Multivariate linear regression showed that depression and anxiety were negatively related to lower cardiovascular reactivity (SBP, DBP and HR reactivity) after full adjustments (P < 0.05). Stress was associated with reduced SBP and DBP reactivity but with a nonsignificant association with HR reactivity (P = 0.056). CONCLUSION: Depression, anxiety, and stress symptoms are associated with blunted cardiovascular reactivity in treatment-naive adult Americans. These findings suggest that blunted cardiovascular reactivity is an underlying mechanism linking psychological health and cardiovascular diseases.

Fibroblast growth factor-23 and the risk of cardiovascular diseases and mortality in the general population: A systematic review and dose-response meta-analysis.

Background: In the past decade, fibroblast growth factor 23 (FGF23) has been recognized as an important biomarker of cardiovascular diseases. This study aimed to assess the relationship between FGF23 and the risk of cardiovascular diseases (CVDs) in general populations. Methods: The protocol was registered prospectively in PROSPERO (CRD42021281837) and two authors independently searched for relevant studies in the PubMed, EMBASE, and Cochrane Library databases. The random effects model was applied. Results: In total, 29 prospective studies involving 135,576 participants were included. In the general population, the category analysis revealed that elevated FGF23 levels were related to increased risks of myocardial infarction (MI) (RR: 1.40, 95%CI: 1.03-1.89), stroke (RR: 1.20, 95%CI: 1.02-1.43), heart failure (HF) (RR: 1.37, 95%CI: 1.23-1.52), CVD events (RR: 1.22, 95%CI: 0.99-1.51), cardiovascular mortality (RR: 1.46, 95%CI: 1.29-1.65), and all-cause mortality (RR: 1.50, 95%CI: 1.29-1.74). In the continuous analysis, per doubling of FGF23 was associated with increased risks of MI (RR: 1.08, 95%CI: 0.94-1.25), stroke (RR: 1.21, 95%CI: 0.99-1.48), HF (RR: 1.24, 95%CI: 1.14-1.35), CVD events (RR: 1.12, 95%CI: 0.99-1.27), cardiovascular mortality (RR: 1.43, 95%CI: 1.09-1.88), all-cause mortality (RR: 1.37, 95%CI: 1.15-1.62). Furthermore, the dose-response analysis demonstrated a potentially non-linear relationship between FGF23 and stroke, HF, and all-cause mortality. In contrast, a potentially linear relationship between FGF23 and cardiovascular mortality was observed (p for non-linearity = 0.73). Conclusion: The present study suggests that increased serum FGF23 levels are positively related to CVD events and mortality in the general population. The clinical application of FGF23 levels to predict CVD risk requires further research.

ABO blood classification and the risk of lung cancer: A meta-analysis and trial sequential analysis.

Patients with certain ABO classifications are at increased risk of certain types of malignancies. In the present study, a meta-analysis was performed to explore the association between the ABO blood group and the risk of lung cancer from an evidence-based medical perspective. The PubMed, Embase, Web of Science, Medline, China National Knowledge Infrastructure, Google Scholar, Science Direct and Wanfang databases were searched for relevant papers. Review Manger 5.4 was used to analyze the association between the ABO blood group and the risk of lung cancer. Trial Sequential Analysis (TSA) was used to determine whether the sample size of the meta-analysis was sufficient. A total of 29 studies were included in this paper. The results of the case-controlled studies showed that the proportion of patients with blood type A in patients with lung cancer was significantly higher than that in healthy individuals [odds ratio (OR), 1.10; 95% confidence interval (CI), 1.02-1.19]. Based on the subgroup analysis, type A blood showed heterogeneity in ethnicity and source of control (social or hospital). Additionally, type O blood was determined to be a protective factor for lung cancer in Caucasians (OR, 0.92; 95% CI, 0.85-0.99). TSA results suggested that there were sufficient participants in the case-controlled studies. Overall, the results of the cohort studies showed that the risk of lung cancer and blood type were weakly associated, and that the difference was not statistically significant. The case-controlled studies suggested that blood type A was associated with a higher risk of lung cancer. In addition, the analysis confirmed that Caucasians with type O blood had a lower risk of lung cancer. However, prospective cohort studies have not been able to draw this conclusion. Different experimental designs may have had a notable influence on the results obtained.

Obesity and clinical outcomes in COVID-19 patients without comorbidities, a post-hoc analysis from ORCHID trial.

Objective: Large body of studies described individuals with obesity experiencing a worse prognosis in COVID-19. However, the effects of obesity on the prognosis of COVID-19 in patients without comorbidities have not been studied. Therefore, the current study aimed to provide evidence of the relationship between obesity and clinical outcomes in COVID-19 patients without comorbidities. Methods: A total of 116 hospitalized COVID-19 patients without comorbidities from the ORCHID study (Patients with COVID-19 from the Outcomes Related to COVID-19 Treated with Hydroxychloroquine among Inpatients with Symptomatic Disease) were included. Obesity is defined as a BMI of ≥30 kg/m2. A Cox regression analysis was used to estimate the hazard ratio (HR) for discharge and death after 28 days. Results: The percentage of obesity in COVID-19 patients without comorbidities was 54.3% (63/116). Discharge at 28 days occurred in 56/63 (84.2%) obese and 51/53 (92.2%) non-obese COVID-19 patients without comorbidities. Four (3.4%) COVID-19 patients without any comorbidities died within 28 days, among whom 2/63 (3.2%) were obese and 2/53 (3.8%) were non-obese. Multivariate Cox regression analyses showed that obesity was independently associated with a decreased rate of 28-day discharge (adjusted HR: 0.55, 95% CI: 0.35-0.83) but was not significantly associated with 28-day death (adjusted HR: 0.94, 95% CI: 0.18-7.06) in COVID-19 patients without any comorbidities. Conclusions: Obesity was independently linked to prolonged hospital length of stay in COVID-19 without any comorbidity. Larger prospective trials are required to assess the role of obesity in COVID-19 related deaths.

Relationship between serum growth differentiation factor 15, fibroblast growth factor-23 and risk of atrial fibrillation: A systematic review and meta-analysis.

Background and objective: Growth differentiation factor-15 (GDF-15) and fibroblast growth factor-23 (FGF-23) are considered predictors of the incidence of cardiovascular diseases. The present meta-analysis aimed to elucidate the associations between GDF-15 and FGF-23 in the risk of atrial fibrillation (AF). Methods: An electronic search was conducted in the Cochrane Library, PubMed, and Embase databases from inception until February 27, 2021. The study protocol was registered in the PROSPERO database (CRD42020182226). Results: In total, 15 studies that enrolled 36,017 participants were included. Both serum FGF-23 and GDF-15 were elevated in patients with AF. Analysis of categorical variables showed higher serum FGF-23 levels were associated with an increased risk of AF [relative risk (RR) = 1.28, 95% confidence interval (CI): 1.05-1.56]. In contrast, this association was not found with GDF-15 (RR = 0.91, 95% CI: 0.20-4.04). In dose-response analysis, a linear positive association was noted between serum FGF-23 levels and the risk of AF (P nonlinear = 0.9507), with a RR elevation of 7% for every 20 pg/ml increase in the serum FGF-23 levels (95% CI: 1.02-1.13). No remarkable relationship was found between serum GDF-15 levels and the risk of AF, and the overall RR for the association between a 100 ng/L increment in GDF-15 levels and AF was 1.01 (95% CI: 0.998-1.02). Conclusion: Our study showed a positive linear correlation between serum FGF-23 levels and the risk of AF. However, no significant association was found between GDF-15 and the risk of AF. Further studies are warranted to clarify whether serum FGF-23 levels may be considered in predicting the risk of AF.Systematic Review Registration: http:www.york.ac.uk/inst/crd, identifier CRD42020182226.

Relationship between the triglyceride-glucose index and risk of cardiovascular diseases and mortality in the general population: a systematic review and meta-analysis.

BACKGROUND: The triglyceride-glucose (TyG) index is a new alternative measure for insulin resistance. This meta-analysis was conducted to assess the associations of the TyG index with the risks of cardiovascular diseases and mortality in the general population. METHODS: The PubMed, Cochrane Library and Embase databases were searched for randomized controlled trials or observational cohort studies reporting associations of the TyG index with cardiovascular diseases and mortality from inception to April 16, 2022. Effect sizes were pooled using random-effects models. Robust error meta-regression methods were applied to fit nonlinear dose-response associations. Evidence quality levels and recommendations were assessed using the Grading of Recommendations Assessment, Development and Evaluation system (GRADE). RESULTS: Twelve cohort studies (6 prospective and 6 retrospective cohorts) involving 6,354,990 participants were included in this meta-analysis. Compared with the lowest TyG index category, the highest TyG index was related to a higher incidence of coronary artery disease (CAD) (3 studies; hazard ratio [HR] = 2.01; 95% confidence interval [CI] 1.68-2.40; I2 = 0%), myocardial infarction (MI) (2 studies; HR = 1.36; 95% CI 1.18-1.56; I2 = 35%), and composite cardiovascular disease (CVD) (5 studies; HR = 1.46; 95% CI 1.23-1.74; I2 = 82%). However, there was no association between the TyG index and mortality (cardiovascular mortality [3 studies; HR = 1.10; 95% CI 0.82-1.47; I2 = 76%] or all-cause mortality [4 studies; HR = 1.08; 95% CI 0.92-1.27; I2 = 87%]). In the dose-response analysis, there was a linear association of the TyG index with the risk of CAD (Pnonlinear = 0.3807) or CVD (Pnonlinear = 0.0612). GRADE assessment indicated very low certainty for CVD, MI, cardiovascular mortality and all-cause mortality, and moderate certainty for CAD. CONCLUSIONS: Based on our current evidence, a higher TyG index may be associated with an increased incidence of CAD (moderate certainty), MI (very low certainty) and CVD (very low certainty) in the general population. There is a potential linear association of the TyG index with CAD and the composite CVD incidence. Further prospective studies (especially in non-Asians) are needed to confirm our findings.

Liver Fibrosis Scores and Hospitalization, Mechanical Ventilation, Severity, and Death in Patients with COVID-19: A Systematic Review and Dose-Response Meta-Analysis.

Methods: We identified relevant cohort studies that assessed the relationship between liver fibrosis scores (e.g., FIB-4, NAFLD fibrosis score (NFS), and aspartate aminotransferase to platelet ratio index (APRI)) and associated prognosis outcomes by searching the PubMed, EMBASE, and medRxiv databases. The potential dose-response effect was performed using a stage robust error meta-regression. Results: Sixteen studies with 8,736 hospitalized patients with COVID-19 were included. One-point score in FIB-4 increase was significantly associated with increased mechanical ventilation (RR: 2.23, 95% CI: 1.37-3.65, P=0.001), severe COVID-19 (RR: 1.82, 95% CI: 1.53-2.16, P < 0.001), and death (RR: 1.47, 95% CI: 1.31-1.65, P < 0.001), rather than hospitalization (RR: 1.35, 95% CI: 0.72-2.56, P=0.35). Furthermore, there is a significant positive linear relationship between FIB-4 and severe COVID-19 (P nonlinearity=0.12) and mortality (P nonlinearity=0.18). Regarding other liver scores, one unit elevation in APRI increased the risk of death by 178% (RR: 2.78, 95% CI: 1.10-6.99, P=0.03). Higher NFS (≥-1.5) and Forns index were associated with increased risk of severe COVID-19 and COVID-19-associated death. Conclusion: Our dose-response meta-analysis suggests high liver fibrosis scores are associated with worse prognosis in patients with COVID-19. For patients with COVID-19 at admission, especially for those with coexisting chronic liver diseases, assessment of liver fibrosis scores might be useful for identifying high risk of developing severe COVID-19 cases and worse outcomes.

Body mass index and atrial fibrillation recurrence post ablation: A systematic review and dose-response meta-analysis.

Objectives: The aim of this study was to evaluate the shape of the dose-response relationship between body mass index (BMI) and atrial fibrillation (AF) recurrence in patients who have undergone radiofrequency ablation. Methods: Studies investigating BMI and AF recurrence in patients with AF after ablation were identified through electronic searches in the PubMed, EMBASE, and Cochrane Library databases. The potential non-linear relationship was fitted using robust error meta-regression. Our study was registered with PROSPERO (CRD42019121373). Results: Twenty-six cohort studies with 7,878 cases/26,450 individuals were included, and a linear dose-response relationship between BMI and AF recurrence (P non-linearity = 0.12) was found. The risk of AF recurrence in patients with a BMI over 28 was significantly increased. Specifically, for each 5 kg/m2 increase in BMI, the risk of AF recurrence increased by 15% (95% CI: 1.08-1.22) with moderate heterogeneity (I 2 = 53%). Subgroup analyses showed that the pooled risk ratio was not significantly changed in subgroup analysis adjustment for the following important potential intermediate factors: left atrial diameter and obstructive sleep apnea. Conclusion: This study showed that there is a borderline positive linear association between BMI and AF recurrence post ablation. Overweight and obesity are significantly associated with AF recurrence. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42019128770.

The Prevalence and Associated Death of Ventricular Arrhythmia and Sudden Cardiac Death in Hospitalized Patients With COVID-19: A Systematic Review and Meta-Analysis.

BACKGROUND: Arrhythmia is a very common complication of coronavirus disease 2019 (COVID-19); however, the prevalence of ventricular arrhythmia and associated outcomes are not well-explored. Here, we conducted a systematic review and meta-analysis to determine the prevalence and associated death of ventricular arrhythmia and sudden cardiac death (SCD) in patients with COVID-19. METHODS: Databases of PubMed, Cochrane Library, Embase, and MdeRxiv were searched. Studies that could calculate the prevalence of ventricular arrhythmia/SCD during hospital admission or associated death in patients with COVID-19 were included. The study was registered with the PROSPERO (CRD42021271328). RESULTS: A total of 21 studies with 13,790 patients were included. The pooled prevalence of ventricular arrhythmia was 5% (95% CI: 4-6%), with a relatively high-SCD prevalence (1.8% in hospitalized COVID-19 and 10% in deceased cases of COVID-19). Subgroup analysis showed that ventricular arrhythmia was more common in patients with elevated cardiac troponin T [ES (effect size): 10%, 95% CI: -0.2 to 22%] and in European (ES: 20%, 95% CI: 11-29%) populations. Besides, ventricular arrhythmia was independently associated with an increased risk of death in patients with COVID-19 [odds ratio (OR) = 2.83; 95% CI: 1.78-4.51]. CONCLUSION: Ventricular arrhythmia and SCD resulted as a common occurrence with a high prevalence in patients with COVID-19 admitted to the hospital. Furthermore, ventricular arrhythmia significantly contributed to an increased risk of death in hospitalized patients with COVID-19. Clinicians might be vigilant of ventricular arrhythmias for patients with COVID-19, especially for severe cases. SYSTEMATIC REVIEW REGISTRATION: www.york.ac.uk/inst/crd, identifier: CRD42021271328.

In Operando Probing of Lithium-Ion Storage on Single-Layer Graphene.

Despite high-surface area carbons, e.g., graphene-based materials, being investigated as anodes for lithium (Li)-ion batteries, the fundamental mechanism of Li-ion storage on such carbons is insufficiently understood. In this work, the evolution of the electrode/electrolyte interface is probed on a single-layer graphene (SLG) film by performing Raman spectroscopy and Fourier transform infrared spectroscopy when the SLG film is electrochemically cycled as the anode in a half cell. The utilization of SLG eliminates the inevitable intercalation of Li ions in graphite or few-layer graphene, which may have complicated the discussion in previous work. Combining the in situ studies with ex situ observations and ab initio simulations, the formation of solid electrolyte interphase and the structural evolution of SLG are discussed when the SLG is biased in an electrolyte. This study provides new insights into the understanding of Li-ion storage on SLG and suggests how high-surface-area carbons could play proper roles in anodes for Li-ion batteries.

Diameter-Sensitive Breakdown of Single-Walled Carbon Nanotubes upon KOH Activation.

While potassium hydroxide (KOH) activation has been used to create pores in carbon nanotubes (CNTs) for improved energy-storage performance, the KOH activation mechanism of CNTs has been rarely investigated. In this work, the reaction between single-walled CNTs (SWCNTs) and KOH is studied in situ by thermogravimetric analysis coupled to infrared (IR) spectroscopy and gas chromatography/mass spectrometry (MS). The IR and MS results clearly demonstrate the sequential evolution of CO, hydrocarbons, CO2 , and H2 O in the activation process. By using the radial breathing mode of Raman spectroscopy, a diameter-sensitive selectivity is observed in the reaction between SWCNTs and KOH, leading to a preferential distribution of SWCNTs with diameters larger than 1 nm after activation at 900 °C and a preferential removal of SWCNTs with diameters below 1 nm upon activation.

Incorporating Pyrrolic and Pyridinic Nitrogen into a Porous Carbon made from C60 Molecules to Obtain Superior Energy Storage.

Nitrogen-doped porous carbon is obtained by KOH activation of C60 in an ammonia atmosphere. As an anode for Li-ion batteries, it shows a reversible capacity of up to ≈1900 mA h g-1 at 100 mA g-1 . Simulations suggest that the superior Li-ion storage may be related to the curvature of the graphenes and the presence of pyrrolic/pyridinic group dopants.

Supercapacitors: A Hierarchical Carbon Derived from Sponge-Templated Activation of Graphene Oxide for High-Performance Supercapacitor Electrodes (Adv. Mater. 26/2016).

H. Ji, Y. Zhu, and co-workers demonstrate a 3D hierarchically porous carbon by introducing a polyurethane sponge to template graphene oxide into a 3D interconnected structure while KOH activation generates abundant micropores in its backbone. As described on page 5222, a supercapacitor assembled with this carbon material achieves a high energy density of 89 W h kg(-1) (64 W h L(-1) ) and outstanding power density due to its shortened ion transport distance in three dimensions.

A Hierarchical Carbon Derived from Sponge-Templated Activation of Graphene Oxide for High-Performance Supercapacitor Electrodes.

A hierarchical porous carbon is fabricated by introducing a polyurethane sponge to a template graphene oxide into a 3D interconnected structure, while KOH activation generates abundant micropores in its backbone. Supercapacitors assembled with this carbon achieve a high energy density of 89 W h kg(-1) (64 W h L(-1) ) and outstanding power density due to the shortened ion-transport distance in 3D.

Assembling carbon quantum dots to a layered carbon for high-density supercapacitor electrodes.

It is found that carbon quantum dots (CQDs) self-assemble to a layer structure at ice crystals-water interface with freeze- drying. Such layers interconnect with each other, forming a free-standing CQD assembly, which has an interlayer distance of about 0.366 nm, due to the existence of curved carbon rings other than hexagons in the assembly. CQDs are fabricated by rupturing C60 by KOH activation with a production yield of ~15 wt.%. The CQDs obtained have an average height of 1.14 nm and an average lateral size of 7.48 nm, and are highly soluble in water. By packaging annealed CQD assembly to high density (1.23 g cm(-3)) electrodes in supercapacitors, a high volumetric capacitance of 157.4 F cm(-3) and a high areal capacitance of 0.66 F cm(-2) (normalized to the loading area of electrodes) are demonstrated in 6 M KOH aqueous electrolyte with a good rate capability.

Infrared biosensors based on graphene plasmonics: modeling.

We propose a biosensor by exploiting localized plasmons in graphene and biomolecule adsorption on it. Numerical simulations demonstrate that the sensitivity of such a device can achieve a high value of up to 1697 nm/RIU (refractive index unit) when the wavelength shift at the plasmon resonance is detected. The transparent substrate supporting graphene can be chosen potentially from a wide range of materials including insulators, semiconductors, polymers, and gels. The plasmon resonance wavelength can be tuned with electrostatic doping and/or structure modulation of graphene. Furthermore, the device works in a wide angle range of incident light since the transverse magnetic (TM) polarization is independent of incident angles.