Covalent Heterojunctions Enhance Bi2S3/Reduced Graphene Oxide (rGO) Nanocomposite Performance as Aqueous Zinc Ion Battery Material

The shortage of lithium resources, safety and recycling difficulty has focused attention on alternative energy storage devices in recent years. The aqueous zinc-ion battery (ZIB) stands out against such a background because of its earth abundance, safety, and environmental friendliness.1 However, the limited choice of cathode materials hinders the development of advanced high-energy-density aqueous ZIBs. At present, manganese oxide2 and vanadium oxide3 are the two most widely studied zinc-ion battery cathodes, but the migration of Zn2+ in these materials is limited by the strong electrostatic interaction with lattice oxygen ions, resulting in poor reversible capacity. Metal sulfides, instead, may effectively improve the electrochemical performance reversibility of ZIBs. Layered metal sulfides have been extensively studied in monovalent cation (Li+, Na+, K+) rechargeable batteries.4 However, although limited studies with Bi2S35,6 as ZIB cathode material exist, their detailed electrochemical charge storage and transfer mechanisms are not well understood. In this work, we explore the effect of covalent anchoring Bi2S3 on reduced graphene oxide (rGO) on the stability and cycling performance as a cathode for aqueous ZIBs. During the hydrothermal synthesis, the reduced graphene oxide serves as the nucleation substrate enabling the formation of fine and uniformly sized Bi2S3 grains, Figure 1 (a). Raman and X-ray photoelectron spectroscopy (XPS) confirm the formation of Bi-O-C heterojunctions during hydrothermal synthesis. These oxygen bridges serve as efficient electron transfer channels in the Bi2S3/rGO composite for rapid charge compensation during Zn2+ incorporation/extraction. As a result, Bi2S3/rGO composite shows notably better rate performance and cycling stability compared with pristine Bi2S3. The specific capacity of Bi2S3-rGO8 composite is ~186 mAh g-1 at the current density of 500 mA g-1 after 150 cycles, considerably higher than unsupported Bi2S3. Additionally, the Bi2S3 nucleated on GO with smaller particle sizes can shorten the transport path of zinc ions, which is beneficial for fast charge transfer. Therefore, Bi2S3-rGO8 can deliver more than 100 mAh g-1 at 10 A/g charge/discharge current density, Figure 1 (b). Also, the zinc storage mechanism was analyzed by X-ray diffraction spectroscopy (XRD) and XPS, indicating a reversible conversion reaction of Zn2+ in the Bi2S3-rGO framework. During discharging, Zn2+ is embedded in Bi2S3-rGO frame to form ZnS and Bi wrapped in rGO. The process is accompanied by the dissolution of bismuth into electrolyte and the formation of (ZnSO4)[Zn(OH)2]3·5H2O (ZHS) on the electrode surface. Inhibition of these two processes may further increase the cycle stability of Bi2S3-rGO. Rotating ring disc electrode (RRDE) measurements, in which we detect dissolved Bi, indicate that Bi dissolution in the electrolyte during charging/discharging is mitigated in Bi2S3/rGO electrode, compared to pristine Bi2S3

Study on the Method of Charge Accumulation Suppression of Electrostatic Suspended Accelerometer

Electrostatic suspended accelerometers (ESAs) are widely used in high accuracy acceleration measurement. However, there exist accumulated charges on the isolated mass which damage the accuracy and the stability of ESAs. In this paper, we propose to apply actuation voltage with a combined waveform to suppress the acceleration noise due to deposited charge. A model of the electrostatic force on the mass is established and the deviation voltage is found to be the dominant source of charge noise. Based on the analysis of disturbance electrostatic force under DC and AC signals, actuation combined with DC and AC voltage is designed and the disturbance force due to charge can be suppressed through adjustment towards the duty cycle of different compositions. Simulations and experiments are carried out and the results indicate that the disturbance due to charge can be suppressed up to 40%, which validates the efficiency of the scheme

Remote Postconditioning Alone and Combined with Hypothermia Improved Postresuscitation Cardiac and Neurological Outcomes in Swine

Objective. Previously, we demonstrated that remote ischemic postconditioning (RIpostC) improved postresuscitation myocardial and cerebral functions in rat. Here, we investigated the effects of RIpostC alone and combined with therapeutic hypothermia (TH) on cardiac and neurological outcomes after CPR in swine. Methods. Twenty-one pigs were subjected to 10 mins of VF and then 5 mins of CPR. The animals were randomized to receive RIpostC alone, or its combination with TH, or sham control. RIpostC was induced by 4 cycles of limb ischemia followed by reperfusion. TH was implemented by surface cooling to reach a temperature of 32–34°C. Results. During 72 hrs after resuscitation, lower level of cardiac troponin I and greater stroke volume and global ejection fraction were observed in animals that received RIpostC when compared to the control. RIpostC also decreased serum levels of neuron-specific enolase and S100B and increased neurologic alertness score after resuscitation. The combination of RIpostC and TH resulted in greater improvement in cardiac and neurological outcomes than RIpostC alone. Conclusion. RIpostC was conducive to improving postresuscitation myocardial and cerebral functions and reducing their organ injuries. Its combination with TH further enhanced its protective effects

CT Analysis of a Potential Safe Zone for Placing External Fixator Pins in the Humerus

Background Iatrogenic radial nerve injures are a common complication during the placement of external fixator pins at the lateral aspect of the humeral shaft. This study uses a three-dimensional measurement technique to locate a safe entry point for humeral pins when externally fixating the elbow. Methods: We fixed a guide wire to the radial nerve by a suture string, and used computed tomography (CT) to scan the upper limbs of cadaver specimens. Then, we measured the deviation angles of the radial nerve on the CT scans, and the distance from the radial nerve to the “elbow rotation center” (ERC). Result: The average distance from the radial nerve to the ERC was 87.3 ± 8.5 mm (range: 68–100 mm), 58.3 ± 11.3 mm (range: 32.12–82.84 mm), 106.3 ± 5.8 mm (range: 86.93–115.08 mm), and 113.9 ± 4.8 mm (range: 97.93–120.22 mm) at radial nerve deviation angles of 0°, –30°, 30°, and 45°, respectively. The average radial nerve deviation angle was –37.7° ± 7.7° and 123.9° ± 19.9° at 50 and 150 mm, respectively. Relative to 0°, the distance between the radial nerve and the ERC at radial nerve deviation angles of –30°, 30°, and 45° showed a significant difference (t = 18.20, p < 0.05; Z = 6.07, p < 0.001; Z = 6.40, p < 0.001, respectively). Conclusions: Pins inserted into the proximal humerus should be about 150 mm from the ERC with a radial nerve deviation angle of 30° anteriorly, and 50 mm from the ERC with a deviation angle of 30°–45° posteriorly

Limb Ischemic Postconditioning Alleviates Postcardiac Arrest Syndrome through the Inhibition of Mitochondrial Permeability Transition Pore Opening in a Porcine Model

Objective. Previously, the opening of mitochondrial permeability transition pore (mPTP) was confirmed to play a key role in the pathophysiology of postcardiac arrest syndrome (PCAS). Recently, we demonstrated that limb ischemic postconditioning (LIpostC) alleviated cardiac and cerebral injuries after cardiac arrest and resuscitation. In this study, we investigated whether LIpostC would alleviate the severity of PCAS through inhibiting mPTP opening. Methods. Twenty-four male domestic pigs weighing 37±2 kg were randomly divided into three groups: control, LIpostC, and LIpostC+atractyloside (Atr, the mPTP opener). Atr (10 mg/kg) was intravenously injected 30 mins prior to the induction of cardiac arrest. The animals were subjected to 10 mins of untreated ventricular fibrillation and 5 mins of cardiopulmonary resuscitation. Coincident with the beginning of cardiopulmonary resuscitation, LIpostC was induced by four cycles of 5 mins of limb ischemia and then 5 mins of reperfusion. The resuscitated animals were monitored for 4 hrs and observed for an additional 68 hrs. Results. After resuscitation, systemic inflammation and multiple organ injuries were observed in all resuscitated animals. However, postresuscitation systemic inflammation was significantly milder in the LIpostC group than in the control group. Myocardial, lung, and brain injuries after resuscitation were significantly improved in the LIpostC group compared to the control group. Nevertheless, pretreatment with Atr abolished all the protective effects induced by LIpostC. Conclusion. LIpostC significantly alleviated the severity of PCAS, in which the protective mechanism was associated with the inhibition of mPTP opening