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In the work, CdS x Se 1-x /N-GQDs composites were fabricated via a simple one-step hydrothermal process and their tunable composition, structure and photoelectric properties were characterized by various techniques. The photoelectric properties of CdS x Se 1-x /N-GQDs could be adjusted by different Se/S ratios and tunable band-gaps. CdS x Se 1-x /N-GQDs composites reached the optimal photocurrent response and the lowest interfacial impedance at the Se/S ratio of 0.75:0.25. Mott-Schottky plots and LSV spectra showed that the n-type CdS 0.25 Se 0.75 /N-GQDs presented a higher carrier density under light illumination. The excellent properties of the composites could be attributed to the mechanism involved in the excitation and electron-transfer process. On one hand, the band-gap of CdS 0.25 Se 0.75 /N-GQDs was narrowed, and more electrons were excited by the lower band-gap energy to promote a superior electron separation and transportation. On the other hand, N-GQDs acted as charge carriers and conductive way providers for electron-transfer instead of electron-hole recombination in the composites. [ABSTRACT FROM AUTHOR]

Background: The safety and efficacy parameters for bipolar radiofrequency (RF) ablation are not well defined.Objective: The purpose of this study was to investigate the safe range of power, utility of transmyocardial bipolar electrogram (EGM) amplitude, and circuit impedance in ablation monitoring.Methods: Sixteen beating ex vivo human and swine hearts were studied in a Langendorff setup. Ninety-two bipolar ablations using two 4-mm irrigated catheters were performed at settings of 20-50 W, 60 seconds, and 30 mL/min irrigation in the left ventricle.Results: For low-power ablations (20 and 30 W), transmurality was observed in 29 of 38 (76%) and 10 of 28 (36%) ablations for tissue thickness ≤17 mm and >17 mm, respectively. For high-power ablations (40 and 50 W), transmurality was observed in 5 of 7 (71%) and 7 of 19 (37%) ablations for tissue thickness ≤17 mm and >17 mm, respectively. Steam pop occurrence for low- and high-power ablations was 11 of 66 (16%) and 16 of 26 (62%), respectively (P = .0001), respectively. Lesion depth (limited by transmurality) was 12.0 ± 5.7 mm and 12.3 ± 5.8 mm, respectively (P = 1). Transmyocardial EGM amplitude decrement >60% strongly predicted transmurality (area under the curve [AUC] 0.8), and circuit impedance decrement >26% predicted steam pops (AUC 0.75). Half-normal saline did not affect transmurality or incidence of steam pops compared to normal saline irrigation.Conclusion: Bipolar RF ablation at power of 20-30 W provided an ideal balance of safety and efficacy, whereas power ≥40 W should be used with caution due to the high incidence of steam pops. Lesion transmurality monitoring and steam pop avoidance were best achieved using transmyocardial bipolar EGM voltage and circuit impedance, respectively. [ABSTRACT FROM AUTHOR]

In this study, the prepared GQDs/W 18 O 49 /WO 3 (WCW) were loaded on g-C 3 N 4 with defects (CN 1-x) under the action of hydrothermal synthesis. The structure, morphology, optical properties, functional groups and surface group properties of the CN 1-x @WCW composites were determined by XRD, TEM, UV–vis, FTIR and XPS tests. The electrochemical properties of the CN 1-x @WCW composite were studied by i-t, EIS and M − S analysis. Compared with WCW, the instantaneous photoelectric efficiency, the photon current efficiency under the applied bias voltage, interfacial electron transfer and electron lifetime of CN 1-x @WCW had been greatly improved. The results indicated that two-dimensional CN 1-x with good conductivity could transfer electrons quickly, reduce the interfacial resistance and prolong the lifetime of electrons, thus inhibiting the recombination of photogenerated electron-hole pairs in WCW semiconductor. In addition, the possible mechanism was proposed and analyzed from the point of view of electron transmission. [ABSTRACT FROM AUTHOR]

WO 3 and N-GQDs were loaded in a two-dimensional graphene sheet layer by hydrothermal method, and then oxygen vacancy-rich WO 3 /N-GQDs/N-rGO composites were successfully prepared by calcination. The structures, morphologies and surface chemical states were characterized by XRD, TEM, XPS, FTIR, and the electrochemical properties were studied by EIS, i-t, LSV and M-S. The WO 3 /N-GQDs/N-rGO composites had a high carrier density of 5.88 × 1020 cm−3 and presented an instantaneous photocurrent density of 2.96 × 10−4 A/cm2 under 365 nm irradiation, which was 4.4 times larger than that of pure WO 3. The enhanced properties were mainly ascribed to the increased light absorption and carrier migration by the two-carbon modification of N-GQDs and N-rGO. Meanwhile, the presence of oxygen vacancies can improve the carrier lifetime, thus suppressing the recombination of photogenerated electron-hole pairs in the WO 3 /N-GQDs/N-rGO composites. The photoelectric properties of the composites were improved by the cooperative effect of double carbon modification and oxygen vacancies. [Display omitted] • WO 3 /N-GQDs/N-rGO with oxygen vacancies was prepared by a hydrothermal and calcination process. • Oxygen vacancies trap photoelectrons to suppress the recombination and improve the conductivity and lifetime. • The introduction of N-doped graphene provides doping atoms and defect sites for oxygen vacancies. • N-rGO acts as a transport channel to speed up the migration of photoelectrons and promote the charge carrier. • Combination of WO 3 with N-GQDs and N-rGO provides more defect sites and conductive ways for photoelectrons. [ABSTRACT FROM AUTHOR]

In this study, tin dioxide with vacancies (SnO x) was compounded with three-dimensional reduced graphene oxide (3D RGO) to obtain SnO x /3D RGO. The morphology, optical properties and structural composition of SnO x /3D RGO were analyzed by a series of techniques, and the photoconductive properties of the SnO x /3D RGO composites with different mass fractions of RGO were investigated. The photocurrent density of SnO x /3D RGO at 3D RGO mass fraction of 1.5 % reached a maximum value of 2.77 × 10−4 A/cm2, which was about twice and 1.2 times as large as that of SnO x and SnO x /2D RGO (two-dimensional reduced graphene oxide), respectively. In the linear scanning voltammetry and Mott-Schottky analysis results, SnO x /3D RGO exhibited the highest photocurrent (6.34 × 10−3 A/cm2) intensity at 1.0 V bias and the largest carrier density (2.61 × 1021cm−3). This was due to the fact that RGO played a charge transfer role in the composite material in both 2D and 3D structures. In contrast, the porous 3D RGO could connect separate lamellae, which prevented the aggregation of layers and enhanced the electron transfer, thus exhibiting superior performance than 2D graphene. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene quantum dots modified SnO 2 composites (SnO 2 /N-GQDs) were prepared by a solvothermal method, where N-GQDs were synthesized through a hydrothermal process with citric acid and urea as sources. The lattice stripes of 0.33 nm, 0.26 nm and 0.24 nm were ascribed to (110) and (101) crystal planes of SnO 2 and (1120) crystal plane of N-GQDs, respectively. The photoelectric properties of SnO 2 /N-GQDs composites with different N-GQDs contents were characterized using I-t, LSV, EIS, and Mott-Schottky. Among them, SnO 2 /N-GQDs-2 composites reached the smallest electrochemical impedance and achieved the optimal transient photocurrent value of 1.880 × 10−4 A/cm2. Compared with pure SnO 2 , SnO 2 /N-GQDs-2 presented a 5-fold increase in the photocurrent density. LSV showed that the incorporation of N-GQDs could enhance the photocurrent intensity of SnO 2. The Mott-Schottky slope of SnO 2 /N-GQDs-2 in light was smaller than that of SnO 2 and SnO 2 /N-GQDs-2 in dark, indicating that more carriers were generated under UV illumination and transferred with the doping of N-GQDs. [ABSTRACT FROM AUTHOR]

Empagliflozin (EMPA) reduces heart failure hospitalization and mortality. The benefit in terms of ventricular arrhythmia and contractility has not been explored. To determine the direct effects of EMPA on ventricular arrhythmia and cardiac contractility in an ex-vivo model of global ischemia-reperfusion (I/R). Langendorff-perfused rabbit hearts were subjected to 30 min of complete perfusion arrest and reperfusion. Either EMPA (1 μM) or normal saline (controls) was then infused into the perfusate in a randomized fashion. Ten minutes following drug infusion, calcium imaging was performed. At the end of each experiment, the heart was electrically stimulated 5 times to assess the inducibility of ventricular fibrillation (VF). In a separate series of experiments, left ventricular (LV) pressure and epicardial NADH fluorescence were simultaneously recorded. LV specimens were then collected for western blotting. Post-ischemia, EMPA treatment was associated with reduction in the induction of VF >10s (rate of induction: 16.7 ± 3.3% vs. 60 ± 8.7% in control hearts, p = 0.003), improvement of LV developed pressure (LVDP; 68.10 ± 9.02% vs. 47.61 ± 5.15% in controls, p = 0.03) and reduction of NADH fluorescence (87.42 ± 2.79% vs. 112.88 ± 2.27% in control hearts, p = 0.04) along with an increase in NAD+/NADH ratio (2.75 ± 0.55 vs. 1.09 ± 0.32 in the control group, p = 0.04) A higher calcium amplitude alternans threshold was also observed with EMPA-treatment (5.42 ± 0.1 Hz vs. 4.75 ± 0.1 Hz in controls, p = 0.006). Sodium-glucose co-transporter-2 (SGLT2) expression was not detected in LV tissues. EMPA treatment reduced ventricular arrhythmia vulnerability and mitigated contractile dysfunction in the global I/R model while improving calcium cycling and mitochondrial redox by SGLT2-independent mechanisms. In normoxic conditions, NADH is generated by the reduction of NAD+ in metabolic pathways by glucose oxidation and Krebs cycle. NADH is oxidized to NAD+ by ETC to produce ATP. ETC dysfunction during hypoxia (Red dotted arrow) is associated with the accumulation of NADH. Improvement of ETC function by EMPA (Blue solid arrow) leads to increase in NAD+/NADH ratio, improvement of contractile function, improvement of cytosolic calcium dynamics, and reduction of vulnerability to ventricular arrhythmias. Glu: Glucose, Pyr: Pyruvate, TCA cycle: Tricarboxylic acid cycle (Krebs cycle), ETC: Electron transport chain, EMPA: Empagliflozin, I/R: Ischemia-reperfusion, SR: Sarcoplasmic reticulum. [Display omitted] • Cardioprotective effects of Empagliflozin were evaluated in a model of global ischemia-reperfusion (I/R) • Empagliflozin increased contractility and decreased ventricular arrhythmia vulnerability • Improvements in mitochondrial redox state and cytosolic calcium dynamics were also noted with Empagliflozin treatment • In our Langendorff model, the cardioprotective effects of Empagliflozin were independent of SGLT2 inhibitory actions • These cardioprotective actions may explain the favorable effects of SGLT2i agents in heart failure which is independent of blood sugar control [ABSTRACT FROM AUTHOR]

The COVID-19 virus has infected more than 38 million people and resulted in more than one million deaths worldwide as of October 14, 2020. By using the logistic regression model, we identified novel critical factors associated with COVID19 cases, death, and case fatality rates in 154 countries and in the 50 U.S. states. Among numerous factors associated with COVID-19 risk, economic inequality enhanced the risk of COVID-19 transmission. The per capita hospital beds correlated negatively with COVID-19 deaths. Blood types B and AB were protective factors for COVID-19 risk, while blood type A was a risk factor. The prevalence of HIV and influenza and pneumonia was associated with reduced COVID-19 risk. Increased intake of vegetables, edible oil, protein, vitamin D, and vitamin K was associated with reduced COVID-19 risk, while increased intake of alcohol was associated with increased COVID-19 risk. Other factors included age, sex, temperature, humidity, social distancing, smoking, health investment, urbanization level, and race. High temperature is a more compelling factor mitigating COVID-19 transmission than low temperature. Our comprehensive identification of the factors affecting COVID-19 transmission and fatality may provide new insights into the COVID-19 pandemic and advise effective strategies for preventing and migrating COVID-19 spread. Unlabelled Image • High temperature is more compelling in mitigating COVID-19 than low temperature. • Economic inequality promotes the risk of COVID-19 transmission. • Major sports events facilitate COVID-19 transmission in European countries. • Blood types B and AB are protective factors for COVID-19. • The per capita hospital beds correlate inversely with COVID-19 deaths. [ABSTRACT FROM AUTHOR]