Accelerating the Rate-Determining Steps of Sulfur Conversion Reaction for Lithium-Sulfur Batteries Working at an Ultrawide Temperature Range.

Wide operation temperature is the crucial objective for an energy storage system that can be applied under harsh environmental conditions. For lithium-sulfur batteries, the "shuttle effect" of polysulfide intermediates will aggravate with the temperature increasing, while the reaction kinetics decreases sharply as the temperature decreasing. In particular, sulfur reaction mechanism at low temperatures seems to be quite different from that at room temperature. Here, through in situ Raman and electrochemical impedance spectroscopy studies, the newly emerged platform at cryogenic temperature corresponds to the reduction process of Li2S8 to Li2S4, which will be another rate-determining step of sulfur conversion reaction, in addition to the solid-phase conversion process of Li2S4 to Li2S2/Li2S at low temperatures. Porous bismuth vanadate (BiVO4) spheres are designed as sulfur host material, which achieve the rapid snap-transfer-catalytic process by shortening lithium-ion transport pathway and accelerating the targeted rate-determining steps. Such promoting effect greatly inhibits severe "shuttle effect" at high temperatures and simultaneously improves sulfur conversion efficiency in the cryogenic environment. The cell with the porous BiVO4 spheres as the host exhibits excellent rate capability and cycle performance under wide working temperatures.

In-situ synthesis Fe3C@C/rGO as matrix for high performance lithium-sulfur batteries at room and low temperatures.

People have been focusing on how to improve the specific capacity and cycling stability of lithium-sulfur batteries at room temperature, however, on some special occasions such as cold cities and aerospace fields, the operating temperature is low, which dramatically hinders the performance of batteries. Here, we report an iron carbide (Fe3C)/rGO composite as electrode host, the Fe3C nanoparticles in the composite have strong adsorption and high catalytic ability for polysulfide. The rGO makes the distribution of Fe3C nanoparticles more disperse, and this specific structure makes the deposition of Li2S more uniform. Therefore, it realizes the rapid transformation and high performance of lithium-sulfur batteries at both room and low temperatures. At room temperature, after 100 cycles at 1C current density, the reversible specific capacity of the battery can be stabilized at 889 ± 7.1 mAh/g. Even at -40 °C, in the first cycle battery still emits 542.9 ± 3.7 mAh/g specific capacity. This broadens the operating temperature for lithium-sulfur batteries and also provides a new idea for the selection of host materials for sulfur in low-temperature lithium-sulfur batteries.

Changes of optic nerve head microcirculation in high myopia.

AIM: To analyze the correlation of age, spherical equivalent (SE), and axial length (AL) with the microcirculation of optic nerve head (ONH) in high myopia (HM). METHODS: In this cross-sectional clinical study, 164 right eyes were included. Optical coherence tomography angiography (OCTA) was used to detect ONH vessel density. Eyes were classified based on age, SE, and AL. Groups of Age1, Age2, and Age3 were denoted for age classification (Age1<20y, 20y≤Age2<30y, Age3≥30y); Groups SE1, SE2, and SE3 for the SE classification (-9≤SE1<-6 D, -12≤SE2<-9 D, SE3<-12 D); Groups AL1, AL2, AL3, and AL4 for the AL classification (AL1<26 mm, 26≤AL2<27 mm, 27≤AL3<28 mm, AL4≥28 mm). RESULTS: No significant difference was observed in vessel density among the Age1, Age2, and Age3 groups (all P>0.05) and the SE1, SE2, and SE3 groups (all P>0.05). No significant difference was observed in the intrapapillary vascular density (IVD) among AL1, AL2, AL3, and AL4 groups (P>0.05). However, a significant decrease was found in the peripapillary vascular density (PVD) in the AL1, AL2, AL3, and AL4 groups (F=3.605, P=0.015), especially in the inferotemporal (IT; F=6.25, P<0.001), temporoinferior (TI; F=2.865, P=0.038), and temporosuperior (TS; F=6.812, P<0.001) sectors. The IVD was correlated with age (r=-0.190, P<0.05) but not with SE or AL (P>0.05). The PVD was correlated with AL (r=-0.236, P<0.01) but not with age or SE (P>0.05). CONCLUSION: With the increase of AL, the IVD remains stable while the PVD decreases, especially in the three directions of temporal (IT, TI, and TS). The main cause of microcirculation reduction may be related to AL elongation rather than an increase in age or SE.

[Relationship between beta amyloid protein 1-40 and post-operative delirium after oral and maxillofacial surgery in elderly patients].

OBJECTIVE: To determine the incidence of post-operative delirium after oral and maxillofacial surgery under general anesthesia in elderly patients, and to examine its association with plasma concentrations of beta amyloid protein 1-40 (Abeta1-40). METHODS: Fifty patients underwent elective oral and maxillofacial surgery were divided into two groups: Group C (n=20) aged from 20 to 60 years old, and Group T (n=30) aged from 62 to 78 years old. The two group received the same general anesthesia. Delirium rating scale-revised-98 (DRS-R-98) was used as an instrument to diagnose and access the postoperative delirium of the two groups. The scores of DRS-R-98 were recorded before operation (T0) and at 24 h (T1), 48 h (T2), 72 h(T3) and 96 h(T4) after the operation. Serial measurements of serum concentrations of Abeta1-40 were also performed at the same time. RESULTS: The incidence of post-operative delirium after oral and maxillofacial surgery in Group T was 20.0%. The concentrations of plasma Abeta1-40 in group T were much higher than group C at TO, T1, T2 and T3 significantly (P < 0.01). The concentrations of plasma Abeta1-40 at T1 and T2 were higher than those at TO in the same group (P < 0.05). The scores of DRS-R-98 in Group T at T3 and T4 were much higher than those at T1 and Group C significantly (P < 0.01). CONCLUSION: The constant increase of plasma Abeta1-40 may be one of the important factors related to post-operative delirium in elderly patients underwent oral and maxillofacial surgery.

[Influence of propofol and isoflurane on cytokines response to cancer surgery during perioperative period].

OBJECTIVE: To compare the influence of propofol and isoflurane on pro-inflammatory and anti-inflammatory cytokine response to perioperative period of tongue cancer surgery. METHODS: Twenty-four adult patients undergone the operation of tongue cancer were assigned to two groups randomly, propofol group (Group P) and isoflurane group (Group I). In group P, anesthesia was induced with fentanyl 2-3 microg/kg, propofol 2 mg/kg, atracurium 0.6 mg/kg and maintained with propofol 5-8 mg x kg(-1) x h(-1) and inhalation of 50% nirous oxide (N2O:O2=50%:50%). In group I, anesthesia was induced with 3%-4% isoflurane, fentanyl 2-3 microg/kg, diazepam 0.06-0.1 mg/kg, atracurium 0.6 mg/kg and maintained with inhalation of 50% N2O and isoflurane (ended-tidal isoflurane was maintained at 0.6%), in two groups atracurium was given intermittently. Blood samples were taken from peripheral vein before anesthesia (TO), at the end of operation (T1), 24 h (T2) and 48 h (T3) after operation for determination of serum IL-6 and IL-10 concentrations. The mean arterial pressure (MAP) and body temperature in two groups were recorded. RESULTS: IL-6 and IL-10 levels increased significantly in two groups at T1, T2 and T3 compared with T0 (P < 0.01). The increasing trend of IL-6 and IL-10 levels were similar in both groups, whereas the level of IL-6 at T1 in propofol group was lower than that of isoflurane group significantly (P < 0.01), however the level of IL-10 was much higher in propofol group than that of isoflurane group at T1 and T2 (P < 0.05). CONCLUSION: The influence of total intravenous anesthesia of propofol on post-operation inflammatory response is much gentler than isoflurane.

[Comparison of the suppressive effects of tramadol and low-dose ketamine on the patients with postoperative hyperalgesia after remifentanil-based anaesthesia].

OBJECTIVE: To compare the suppressive effects of tramadol and low-dose ketamine on postoperative hyperalgesia after remifentanil-based anaesthesia. METHODS: A total number of sixty ASA I - II adult patients who undergone the operation of cranio-cervical region were assigned to three groups randomly, controlled group (Group C), tramadol group (Group T) and low-dose ketamine group (Group K). Before the end of surgery, Group T was given tramadol 0.3 mg/kg, Group K was given ketamine 0.5 mg/kg and Group C wasn't given any medicine. When the visual analogue scale (VAS) score of the group C was over five, tramadol 0.3 mg/kg was given to the patients. The four-level verbal rating scale after trachea extubation, VAS score, the time of requiring analgesia again by patients and adverse drug reactions such as nausea, vomit, diplopia and hallucination were recorded for 24 hours after surgery. RESULTS: After operation, the VAS score of Group C was much higher than that of Group K in the first 4 hours and Group T was higher than Group K during 2, 3 and 4 hours (P < 0.05). The time of requiring analgesia by patients in Group C and Group T was earlier than Group K. The adverse drug reaction showed no significant difference in three groups. CONCLUSION: Low-dose ketamine had significant suppressive effect on patients with postoperative hyperalgesia and acute opioid tolerance after remifentanil-based anaesthesia.