Synchronously enhancing thermal conductivity and dielectric properties in epoxy composites via incorporation of functionalized boron nitride.

Polymer-like dielectrics with superb thermal conductivity as well as high dielectric properties hold great promise for the modern electronic field. Nevertheless, integrating these properties into a single material simultaneously remains problematic due to their mutually limited physical connotations. In this study, we developed high-quality thermally conductive epoxy composites with excellent dielectric properties. This was achieved by incorporating surface-functionalized microscale hexagonal boron nitride (BN) along with N-[3-(Trimethoxysilyl)propyl]ethylene diamine (DN) and N-[3-(Trimethoxysilyl)propyl]aniline (PN). In the resulting epoxy composite, microscale BN serves as the primary building block for establishing the thermally conductive network, while silica particles act as bridges to regulate heat transfer and reduce interfacial phonon-scattering. The prepared composites were thoroughly examined across various filler contents (ranging from 10 to 80 wt%). Among them, the DNBN/epoxy composite exhibited higher thermal conductivity (in-plane: 47.03 W m-1 K-1) at 60 wt% filler content compared to BN/epoxy (39.40 W m-1 K-1) and PNBN/epoxy (33 W m-1 K-1) composites. These results highlight the usefulness of surface modification of BN in improving compatibility between fillers and epoxy, ultimately reducing composite viscosity. Furthermore, the DNBN/epoxy composite at 60 wt% demonstrated superb dielectric constant (∼6.15) without compromising on dissipation loss (∼0.06). The strategy adopted in this study offers significant insights into designing dielectric thermally conductive composites with superior performance outcomes.

Communication Delay Outlier Detection and Compensation for Teleoperation Using Stochastic State Estimation.

There have been numerous studies attempting to overcome the limitations of current autonomous driving technologies. However, there is no doubt that it is challenging to promise integrity of safety regarding urban driving scenarios and dynamic driving environments. Among the reported countermeasures to supplement the uncertain behavior of autonomous vehicles, teleoperation of the vehicle has been introduced to deal with the disengagement of autonomous driving. However, teleoperation can lead the vehicle to unforeseen and hazardous situations from the viewpoint of wireless communication stability. In particular, communication delay outliers that severely deviate from the passive communication delay should be highlighted because they could hamper the cognition of the circumstances monitored by the teleoperator, or the control signal could be contaminated regardless of the teleoperator's intention. In this study, communication delay outliers were detected and classified based on the stochastic approach (passive delays and outliers were estimated as 98.67% and 1.33%, respectively). Results indicate that communication delay outliers can be automatically detected, independently of the real-time quality of wireless communication stability. Moreover, the proposed framework demonstrates resilience against outliers, thereby mitigating potential performance degradation.

Construction of a uniform zeolitic imidazole framework (ZIF-8) nanocrystal through a wet chemical route towards supercapacitor application.

Exploring larger surface area electrode materials is crucial for the development of an efficient supercapacitors (SCs) with superior electrochemical performance. Herein, a cost-effective strategy was adopted to synthesize a series of ZIF8 nanocrystals, and their size effect as a function of surface area was also examined. The resultant ZIF8-4 nanocrystal exhibits a uniform hexagonal structure with a large surface area (2800 m2 g-1) and nanometre size while maintaining a yield as high as 78%. The SCs performance was explored by employing different aqueous electrolytes (0.5 M H2SO4 and 1 M KOH) in a three-electrode set-up. The SC performance using a basic electrolyte (1 M KOH) was superior owing to the high ionic mobility of K+. The optimized ZIF8-4 nanocrystal electrode showed a faradaic reaction with a highest capacitance of 1420 F g-1 at 1 A g-1 of current density compared to other as-prepared electrodes in the three-electrode assembly. In addition, the resultant ZIF8-4 was embedded into a symmetric supercapacitor (SSC), and the device offered 350 F g-1 of capacitance with a maximum energy and power density of 43.7 W h kg-1 and 900 W kg-1 at 1 A g-1 of current density, respectively. To determine the practical viewpoint and real-world applications of the ZIF8-4 SSC device, 7000 GCD cycles were performed at 10 A g-1 of current density. Significantly, the device exhibited a cycling stability around 90% compared to the initial capacitance. Therefore, these findings provide a pathway for constructing large surface area ZIF8-based electrodes for high-value-added energy storage applications, particularly supercapacitors.

Comparative effectiveness of pharmacological interventions to prevent postoperative delirium: a network meta-analysis.

Many pharmacologic agents were investigated for the effect to prevent delirium. We aimed to comprehensively compare the effect of the pharmacological interventions to prevent postoperative delirium. A Bayesian network meta-analysis of randomized trials was performed using random effects model. PubMed, the Cochrane Central Register of Controlled Trials, and Embase were searched on 20 January 2021. Randomized trials comparing the effect of a drug to prevent postoperative delirium with another drug or placebo in adult patients undergoing any kind of surgery were included. Primary outcome was the postoperative incidence of delirium. Eighty-six trials with 26,992 participants were included. Dexmedetomidine, haloperidol, and atypical antipsychotics significantly decreased the incidence of delirium than placebo [dexmedetomidine: odds ratio 0.51, 95% credible interval (CrI) 0.40-0.66, moderate quality of evidence (QOE); haloperidol: odds ratio 0.59, 95% CrI 0.37-0.95, moderate QOE; atypical antipsychotics: odds ratio 0.27, 95% CrI 0.14-0.51, moderate QOE]. Dexmedetomidine and atypical antipsychotics had the highest-ranking probabilities to be the best. However, significant heterogeneity regarding diagnostic time window as well as small study effects precludes firm conclusion.

Adult lung transplantation case-volume and in-hospital and long-term mortality in Korea.

BACKGROUND: The inverse relationship between case-volume and surgical mortality has been reported in complex surgical procedures. The aim of this study was to evaluate the effect of case-volume on mortality after lung transplantation in Korea. METHODS: The National Health Insurance Service data was used to analyse all adult lung transplantations in Korea between 2007 and 2016. Institutions were categorized into low-volume (< 5 lung transplantations/year) centers or high-volume (≥ 5 lung transplantations/year) centers. Risk-adjusted in-hospital mortality and long-term survival according to case-volume was evaluated. RESULTS: A total of 315 adult recipients underwent lung transplantation at 7 centers. The odds ratio for in-hospital mortality in low-volume centers was similar to high-volume centers (OR, 1.496; 95% CI, 0.81-2.76; p = 0.197). Log-rank analysis of Kaplan-Meier curves according to case-volume also did not show a difference in long-term survival between high- and low-volume centers (p = 0.052). CONCLUSIONS: There was no association between case-volume and in-hospital mortality after lung transplantation in Korea, although there was a tendency towards better long-term survival associated with high-volume centers.

Deep vs. moderate neuromuscular blockade during laparoscopic surgery: A systematic review and meta-analysis.

BACKGROUND: Previous studies have reported that deep neuromuscular block (posttetanic-count 1 to 2 twitches) improves surgical conditions during laparoscopy compared with moderate block (train-of-four count: 1 to 2 twitches). However, comparisons of surgical conditions were made using different scales and assessment intervals with variable results. OBJECTIVE: To explore the heterogeneity of previous comparisons between deep and moderate neuromuscular block. DESIGN: Systematic review and meta-analysis of randomised controlled trials (RCTs). DATA SOURCES: Medline, EMBASE and Cochrane Central Register of Controlled Trials were searched from inception to October 2017. ELIGIBILITY CRITERIA: Our meta-analysis included RCTs comparing the effects of deep with moderate neuromuscular block on surgical field conditions during laparoscopic surgery. The frequency of excellent or good operating conditions on a surgical rating scale was compared. Heterogeneity was assessed by subgroup analyses. RESULTS: Eleven RCTs involving 844 patients were included. On the surgical rating scale, the frequency of excellent or good operating conditions was higher with deep block compared with a moderate block (odds ratio 2.83, 95% confidence interval 1.34 to 5.99, P = 0.007, I = 59%). We analysed surgical rating according to the number of assessments made. There was a significant difference in surgical rating with multiple assessments, but no difference when the assessment was made on only one occasion. A significant difference in rating was noted with variable abdominal pressures; there was no significant difference with the same fixed abdominal pressure. Trial sequential analysis demonstrated that the cumulative z-curve crossed the O'Brien-Fleming significance boundary. However, required information size was not achieved. CONCLUSION: Deep block was associated with excellent or good surgical rating more frequently than moderate block. However, this finding was not consistent on subgroup analyses based on frequencies of assessment of surgical conditions and abdominal pressure. Further studies are required to address the heterogeneity and power shortage demonstrated by the trial sequential analysis.