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2. Ultrafast carriers' separation imaging in WS2-WSe2 in plane heterojunction by transient reflectivity microscopy

Author

Zhong, Yangguang, Yue, Shuai, Liu, Huawei, Xia, Yuexing, Pan, Anlian, Chen, Shula, and Liu, Xinfeng

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Carrier transport in nanodevices plays a crucial role in determining their functionality. In the post-Moore era, the behavior of carriers near surface or interface domains the function of the whole devices. However, the femtosecond dynamics and nanometer-scale movement of carriers pose challenges for imaging their behavior. Techniques with high spatial-temporal resolution become imperative for tracking their intricate dynamics. In this study, we employed transient reflectivity microscopy to directly visualize the charge separation in the atomic interface of WS2-WSe2 in-plane heterojunctions. The carriers' drifting behavior was carefully tracked, enabling the extraction of drift velocities of 30 nm/ps and 10.6 nm/ps for electrons and holes. Additionally, the width of the depletion layer was determined to be 300 nm based on the carriers' moving trajectory. This work provides essential parameters for the potential effective utilization of these covalent in-plane heterojunctions,and demonstrates the success of transient optical imaging in unraveling the electrical behavior of nano devices, paving the way for a new avenue of electro-optical analysis.

Published
2024

46. Effects of controlled hypotension induced by sodium nitroprusside on regional cerebral blood flow and oxygenation in pigs

Author

ZUO Dukun, LI Yang, PENG Taotao, LIU Huawei, and YANG Guiying

Subjects
anesthesia, controlled hypotension, sodium nitroprusside, cerebral blood flow, cerebral oxygen saturation, Medicine (General), R5-920
Abstract

Objective To investigate the effects of controlled hypotension induced by sodium nitroprusside on regional cerebral blood flow and oxygenation in pigs. Methods Six healthy female Landrace pigs (aged 4~6 months, weighing 22~25 kg) were included in this study. Sodium nitroprusside was used for controlled hypotension under sevoflurane anesthesia (20%, 30% and 50% lower than the baseline of mean arterial pressure or mean arterial pressure (MAP), corresponding to mild, moderate and severe hypotension, respectively). Oxygen to see (O2C), a monitoring instrument, was used to measure regional cerebral blood flow (rCBF) and regional cerebral oxygen saturation (rSO2). rCBF, rSO2, regional cerebral haemoglobin (rHb), heart rate (HR), peripheral oxygen saturation (SpO2) and incidence of cerebral hypoxia events were recorded under different MAP. Results rCBF was significantly correlated with MAP (r=0.793) and also obviously correlated with rSO2 (r=0.843) in the whole hypotension process. rSO2 had a linear correlation with rHb, MAP and rCBF (R2=0.853, P < 0.05), respectively. And the order of their linear correlation with rSO2 is rHb>MAP>rCBF. During mild hypotension, rCBF and rSO2 were increased by 7.4%(P < 0.05) and 2.5%(P < 0.05), respectively compared with the baseline, and the increase of rCBF was more remarkable. During moderate hypotension, compared with the baseline, rCBF was decreased by 0.9% (P>0.05), while rSO2 was decreased by 5.8% (P < 0.05). During severe hypotension, rCBF and rSO2 were decreased by 7.6% (P < 0.05) and 12.1% (P < 0.05) respectively, and there was no cerebral hypoxia event during mild to severe hypotension. From 5 to 15 min after drug withdrawal, both rCBF and rSO2 were increased by 8.4% and 3.7%, respectively when compared with the baseline (both P < 0.05). Conclusion Controlled hypotension with sodium nitroprusside is beneficial to maintain cerebral perfusion and cerebral oxygenation, but mild hypotension can cause an increase in cerebral blood flow, which is disadvantageous to patients with increased intracranial pressure.

Published
2022
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47. Application of surgical pleth index in monitoring nociceptive stimulation in patients with total intravenous anesthesia

Author

LIU Huawei, CHEN Feng, DING Jinping, CHEN Qin, and ZUO Dukun

Subjects
surgical pleth index, nociceptive stimulation, total intravenous anesthesia, Medicine (General), R5-920
Abstract

Objective To investigate the accuracy of surgical pleth index (SPI) in monitoring patients with nociceptive stimulation and its predictability for cardiovascular response to nociceptive stimulation in total intravenous anesthesia (TIVA). Methods A total of 102 patients (aged 18 to 65 years, ASAⅠtoⅡ, and BMI of 18.5 to 30 kg/㎡) who underwent elective thyroid surgery in our hospital from February to June 2022 were enrolled in this study. Each patient was induced by intravenous anesthesia, maintained by target-controlled infusion of propofol and remifentanil, and monitored by SPI for analgesia depth. The absolute values of SPI, heart rate (HR) and mean arterical pressure (MAP) of patients 2 min before and during nociceptive stimulation and the maximum values of SPI, HR and MAP within 2 min after nociceptive stimulation were recorded. Receiver operating characteristic (ROC) curve was used to analyze the accuracy of SPI, HR and MAP in monitoring nociceptive stimulation and the predictability of SPI in cardiovascular response to nociceptive stimulation. Results ROC curve analysis indicated that SPI (AUC=0.931, Cutoff value=30) was superior to HR (AUC=0.804, Cutoff value=68) and MAP (AUC=0.759, Cutoff value=80) in monitoring accuracy of tracheal intubation stimulation, ΔSPI (AUC=0.990, Cutoff value=4) was better than ΔHR (AUC=0.972, Cutoff value=3) and ΔMAP (AUC=0.854, Cutoff value=3), ΔSPI was better than SPI, ΔHR was better than HR, and ΔMAP was better than MAP, with their AUC values statistically different (P < 0.05). In terms of monitoring the accuracy of skin incisions, SPI (AUC=0.925, Cutoff value=43) was superior to HR (AUC=0.587, Cutoff value=65) and MAP (AUC=0.804, Cutoff value=76), ΔSPI (AUC=0.998, Cutoff value=7) was better than ΔHR (AUC=0.833, Cutoff value=1) and ΔMAP (AUC=0.943, Cutoff value=3), ΔSPI was better than SPI, ΔHR was better than HR, and ΔMAP was better than MAP, and the above AUC differences were statistically significant (P < 0.05); SPI had predictive value for the cardiovascular response stimulated by tracheal intubation (AUC=0.662, Cutoff value=17, P < 0.05), but had no predictive significance for the cardiovascular response stimulated by skin incisions (P>0.05). Conclusion The absolute value and change of SPI are better than the traditional hemodynamic indexes HR and MAP in monitoring the accuracy of nociceptive stimulation, which can accurately monitor nociceptive stimulation during operation. SPI has predictive value for the cardiovascular response stimulated by intubation stimulation, and has important clinical significance for judging the appropriate timing of intubation.

Published
2022
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