Search

High breakdown strength material in the cable insulation layer is a key enabler for high voltage power transmission. In this work, we seek to design high‐performance voltage stabilizers to be compounded into polyethylene to improve its breakdown strength. We hypothesize that electron affinity (EA) and HOMO‐LUMO gap are two key factors that affect the performance of voltage stabilizers. To achieve larger EA and smaller HOMO‐LUMO gap, we propose to use aromatic molecules decorated with electron acceptors and donors. A search of an internal chemical database narrows down to 529 molecules using structure, ClogP, and H‐phrases (hazard statement) as criteria. The EA and HOMO‐LUMO gap of these molecules are then calculated and experiments are carried out to measure the performance of 20 molecules. The performance improvement does not show a significant correlation with either EA or HOMO‐LUMO gap. However, the best performers have an EA of 1.3–2.3 eV and HOMO‐LUMO gap of 3.2–5.2 eV. The experimental study shows that adding side groups to voltage stabilizers will typically degrade their performance because side groups will generally increase the distance between the HOMO‐LUMO orbitals and polyethylene backbone, and therefore decrease the electron/hole tunneling effectiveness. [ABSTRACT FROM AUTHOR]

Objective: To analyze the risk factors for gastrointestinal (GI) bleeding in congenital heart disease (CHD) patients supported with venoarterial extracorporeal membrane oxygenation (V‐A ECMO) after open‐heart surgery. Methods: A retrospective analysis was performed on children with (GI group: 26 cases) and without (control group: 122 cases) GI bleeding during ECMO at Shanghai Children's Medical Center from 2017 to 2020. Clinical data were analyzed and compared between groups to search for risk factors for GI bleeding. Results: A total of 148 cases were included in the study. The overall incidence of GI bleeding was 17.6% (26/148). The in‐hospital mortality rate in the GI group was 61.5% (16/26) versus 45.9% (56/122) in the control group. Twenty‐six patients suffered cardiac arrest before ECMO support. The GI bleeding incidence among extracorporeal cardiopulmonary resuscitation (ECPR) patients was 50.0% (13/26) versus 28.7 (35/122) among non‐ECPR patients, p = 0.035. The activated clotting time (ACT) was 201.40 s (180.47 to 247.27) in the GI group versus 177.63 s (167.79 to 203.13) (p = 0.050) in the control group. The lowest antithrombin level (Min AT) was 27.00 ± 13.07% versus 37.62 ± 15.18 (p = 0.001). The pH and lactate levels before ECMO (Pre PH and Pre Lac) were lower in the GI group than in the control group. (7.31 ± 0.23 vs. 7.35 ± 0.17, p = 0.035 and 12.2 ± 6.11 vs. 7.78 ± 6.67, p = 0.003). Liver function during ECMO support was statistically worse in the GI group than in the control group. Multivariate analysis showed that Pre Lac (OR = 1.106 [1.018–1.202], p = 0.0016) was an independent risk factor for GI bleeding. ROC analysis of Pre Lac and GI bleeding showed an area under the curve (AUC) of 0.700 (95% CI: 0.600–0.800, p = 0.002) and a cutoff value of 9.30 mmol/L (sensitivity, 73.1%; specificity, 62.7%). Conclusions: As the first study in this field, the probability of GI bleeding and related mortality was found to be high in children supported with V‐A ECMO after open‐heart surgery. A higher lactate level before ECMO was an independent risk factor for GI bleeding. [ABSTRACT FROM AUTHOR]

To improve the mechanical performances of joints in prefabricated construction, a type of connection structure with long-fiber and metal laminated bolts (referred to as a fiber-metal connector) is proposed and investigated by simulation and theoretical methods. The results include the following: (1) The fiber layer in bolts can form a second stiffness during rotation. This mechanical characteristic improves the bearing capacities and energy dissipation ability of the connector relative to the conventional metal connector, which are expected to effectively limit the elastoplastic rotational displacement of a structure. (2) For the reason, the fiber layer can bear load in the plastic phase due to its high-strength characteristic in the length direction. (3) A bilinear model for the bearing curve of the fiber-metal connector is proposed, and equations for optimization of fiber layer thickness are obtained with a target on bearing capacity and energy dissipation ability which are approximately higher 30% and 13% than that of the conventional metal connector, respectively. This research is expected to provide a theoretical basis for the application of this fiber-metal connector in engineering and improve the safety of prefabricated structures. [ABSTRACT FROM AUTHOR]

Medium to extra‐high voltage electrical cables typically comprise a semiconductive polymer composite layer to homogenize the electromagnetic field through the cables. The semiconductive layers usually contain a high content of carbon black (CB) for reduced electrical resistivity. In this study, we found that both the morphology and resistivity of a ternary polymer composite of CB/low density polyethylene (LDPE)/ethylene‐vinyl acetate (EVA) depend on CBs used and the order of addition. Three types of CB were investigated. CB‐A, which has the lowest surface energy and the most uniform surface energy profile, exhibits a strong affinity to LDPE and always segregates in the LDPE phase whether it is first added in the LDPE phase or the EVA phase. CB‐B and CB‐C, which have higher and less homogeneous surface energies, distribute differently with different orders of addition. We observe a significant reduction in the percolation threshold of CB‐A in the CB/LDPE/EVA composite, but not with CB‐B or CB‐C. Adding CB‐A in the LDPE phase first results in substantially lower resistivity than adding it in the EVA phase first, whereas adding CB‐B or CB‐C in the LDPE phase first results in higher resistivity than adding them in the EVA phase first. [ABSTRACT FROM AUTHOR]

Background Extracorporeal membrane oxygenation (ECMO) provides circulatory support in children with congenital heart disease, particularly in the setting of cardiopulmonary failure and inability to wean from cardiopulmonary bypass. This study summarized the clinical application of ECMO in the treatment of heart failure after cardiac surgery in neonates. Materials and Methods Clinical data of 23 neonates who received ECMO support in our center from January 2017 to June 2019 were retrospectively analyzed. Results Twenty-three neonates, aged from 0 to 25 days and weight between 2,300 and 4,500 g, with heart failure postcardiotomy were supported with ECMO. The successful weaning rate was 78.26% and discharge rate was 52.17%. Bleeding and residual malformation were the most common complications. The univariate analysis showed that nonsurvivors were related to the factors such as higher lactate value of ECMO 12 and 24 hours (p = 0.008 and 0.001, respectively), longer time to lactate normalization (p = 0.001), lactate > 10 mmol/L before ECMO (p = 0.01), lower weight (p = 0.01), longer ECMO duration (p = 0.005), lower platelet count (p = 0.001), more surgical site bleeding (p = 0.001), and surgical residual malformation (p = 0.04). Further logistic regression analysis revealed that higher lactate value of ECMO 24 hours (p = 0.003), longer ECMO duration (p = 0.015), and surgical site bleeding (p = 0.025) were independent risk factors. Conclusion ECMO was an effective technology to support the neonates with cardiopulmonary failure after open heart surgery. Control the lactate acidosis and surgical site bleeding event may be helpful for patients' recovery. [ABSTRACT FROM AUTHOR]

For the development of new types of lightweight sandwich structures, the compressive properties and strengthening mechanism of the middle-trabecular beetle elytron plate were investigated for various values of η (the ratio of the trabecular radius to the honeycomb wall length). The results are as follows: (1) When η = 0.1, the increases in the compressive strength and standard energy absorption capacity of the middle-trabecular beetle elytron plate compared with the honeycomb plate exceed those of the end-trabecular beetle elytron plate; with an increase to η = 0.15, the compressive strength remains nearly the same, the energy absorption capacity undergoes a significant further increase, and the trabeculae exhibit Φ-type failure. (2) The strengthening mechanism that gives rise to the compressive properties of the middle-trabecular beetle elytron plate is proposed as follows: the trabeculae are located at the center of the honeycomb walls, where the maximum deformations would otherwise occur; they constrain the deformation of the honeycomb walls; and the number of trabeculae in the middle-trabecular beetle elytron plate also exceeds that in the end-trabecular beetle elytron plate. (3) Middle-trabecular beetle elytron plates have the advantage of facile manufacturing, which will establish a basis for promoting the application of beetle elytron plates. [ABSTRACT FROM AUTHOR]

Extracorporeal membrane oxygenation (ECMO) provides cardiorespiratory support during cardiopulmonary resuscitation unresponsive to conventional methods. Here, we analyzed the extracorporeal cardiopulmonary resuscitation (ECPR) results of children in a cardiac arrest setting after cardiac surgery. Of 3119 cases of pediatric open‐heart surgery, 31 required postoperative ECMO. Among the 31 patients, 11 experienced cardiac arrest and ECPR in the early postoperative period. These 11 patients' median age is 1.5 [range, 0.1‐19] months and median weight is 3.9 [range, 2.9‐10.3] kg. The medical records of ECPR cases were analyzed. The median ECMO‐assisted time was 68 (range, 13‐456) hours and 4 cases (36.4%) survived. The ECMO‐assisted times were ≤2 days in 4 patients (all eventually died), ≥6 days in 3 patients (all also died), and all 4 cases supported for 2‐6 days were discharged successfully (P = 0.006). In the survivors and nonsurvivors, peak lactate levels were 10.8 ± 7.04 and 22.8 ± 6.98 mmol/L (P = 0.023) and peak creatinine levels were 47.50 ± 25.9 and 153.7 ± 73.9 mg/dL (P = 0.035), respectively. In these 11 ECPR cases, the most common complications were bleeding requiring re‐exploration (n = 6, 54.5%) and renal failure (n = 6, 54.5%). The incidence of renal failure was significantly correlated with hypoperfusion time (P = 0.015). ECPR is valuable in children with postoperative cardiac arrest. The higher peak lactate level, higher peak creatinine level, and prolonged ECMO duration were associated with higher mortality. Early diagnosis and intervention of residual anatomical problems could improve survival. Bleeding and renal failure were the most common complications and the incidence of renal failure may be correlated with longer hypoperfusion duration. [ABSTRACT FROM AUTHOR]

To explore the characteristics of the core structure of ladybug ( Harmonia axyridis ) forewings, their microstructure was studied using microscopes. The results suggest that trabeculae exist in the frame of the beetle (ladybug) forewing for the first time; this study represents the first determination of the parameters N, the total number of trabeculae in each forewing, and λ t , the ratio of the cross-sectional area of the trabeculae to the effective area of trabecular distribution. The cross-sectional area of a single trabecula in the ladybug forewing is smaller than those in two other kinds of beetles, Allomyrina dichotoma and Prosopocoilus inclinatus . However, the average trabecular density of the ladybug forewing is 84 per square millimeter, which is the highest among these three kinds of beetles. The λ t values are 1.0%, 1.5% and 10.5% for H. axyridis , A. dichotoma and P. inclinatus , respectively, and the corresponding N values are approximately 1.4, 1.7 and 3.7 thousand, respectively. Based on these findings, a biomimetic model of the ladybug forewing is proposed, which is characterized by a core structure with a high-density distribution of thin trabeculae surrounded by a foam-like material. [ABSTRACT FROM AUTHOR]