The anti-coagulation protocol of patients with hemorrhage risk primary disease who need extracorporeal membrane oxygenation (ECMO) supported is controversial. This study evaluated the feasibility of a new anti-coagulation strategy, that is heparin-free after 3000 IU heparin loaded in veno-venous ECMO (VV ECMO) supported acute respiratory failure patients with hemorrhage risk.A retrospective study was performed in a series of hemorrhage risk patients supported with VV ECMO at the First Affiliated Hospital of Zhengzhou University, between June 2012 to Sept 2020. A total of 70 patients received a low heparin bolus of 3000 units for cannulation but without subsequent, ongoing heparin administration. Patients were divided into survival (n = 25) and non-survival group (n = 45). Data of coagulation, hemolysis and membrane lung function were calculated and analyzed. The complications of patients were recorded. Finally, the binary Logistic regression was conducted.The longest heparin-free time was 216 h, and the mean heparin-free time was 102 h. Compared with survivors, the non-survivors were showed higher baseline SOFA score and lower platelet counts in 0.5 h, 24 h, 48 h and 96 h after ECMO applied. However, there was no significant differences between survivors and non-survivors in ACT, APTT, INR, D-dimer, fibrinogen, LDH, blood flow rate, Δp and Ppost-MLO2 (all p < 0.05) of all different time point. Moreover, only the baseline SOFA score was significantly associated with mortality (p < 0.001, OR(95%CI): 2.754 (1.486-5.103)) while the baseline levels of ACT, APTT, INR, platelet, D-dimer, fibrinogen and LDH have no association with mortality. The percentage of thrombosis complications was 54.3% (38/70) including 3 oxygenator changed but there was no significant difference of complications in survival and non-survival groups (p > 0.05).The anticoagulation protocol that no heparin after a 3000 units heparin bolus in VV ECMO supported acute respiratory failure patients with hemorrhage risk is feasible.
Abstract As a promising sustainable power source for intelligent electronics, flexible piezoelectric nanogenerators (PENGs) have gained significant attention for their potential applications in the Internet of Things. Here, the polyvinylidene fluoride (PVDF) fibers with a core-sheath hollow porous structure that consisting of the liquid metal (LM) as the inner electrode layer and the copper and silver nanoparticle (Cu@AgNP) as the external electrode layer are prepared via a coaxial wet spinning process to construct high-performance PVDF/LM/Cu@AgNP composite fibers. The PVDF fiber has stratified pore structure and the existence of arbitrarily deformable LM electrode, which significantly reduces the effective dielectric constant, thereby enhancing the piezoelectric properties. The results demonstrate that PVDF/LM/Cu@AgNP-PENG yields an optimal voltage output of 410 mV, providing a clear advantage over PENG by using alternative fibers. Moreover, the PVDF/LM/Cu@AgNP-PENG demonstrates an excellent charging capability for energy storage devices, being able to charge 1 µF capacitors to 10 V within 30 seconds and directly power commercial LEDs. This study demonstrates the significant potential for utilizing composite PVDF piezoelectric fibers in flexible wearable electronic devices.
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Target localization using a frequency diversity multiple-input multiple-output (MIMO) system is one of the hottest research directions in the radar society. In this paper, three-dimensional (3D) target localization is considered for two-dimensional MIMO radar with orthogonal frequency division multiplexing linear frequency modulated (OFDM-LFM) waveforms. To realize joint estimation for range and angle in azimuth and elevation, the range-angle-dependent beam pattern with high range resolution is produced by the OFDM-LFM waveform. Then, the 3D target localization proposal is presented and the corresponding closed-form expressions of Cramér-Rao bound (CRB) are derived. Furthermore, for mitigating the coupling of angle and range and further improving the estimation precision, a CRB optimization method is proposed. Different from the existing methods of FDA-based radar, the proposed method can provide higher range estimation because of multiple transmitted frequency bands. Numerical simulation results are provided to demonstrate the effectiveness of the proposed approach and its improved performance of target localization.
Al-Li alloys with a high Li content have the advantages of low density and high stiffness but usually suffer from poor strength, instability of nanoprecipitates, and severe anisotropy, limiting their practical application. Here, we introduce a stable multilayer core-shell nanostructure in aluminum-lithium alloy castings to address these challenges. By quantifying the precipitates' composition and structures using atom probe tomography (APT) and small angle neutron scattering (SANS), it was found that there exists a unique type of Li-rich, coherent, nanoscale single-core double-shell particles in this alloy, which is different from the previously reported core-shell structures. First-principles calculations reveal that this complex core-shell structure possesses both the advantage of low mismatch-induced nucleation and highly stable characteristics under service conditions. Compared with traditional core-shell structures, this core-shell structure exhibits the lowest critical nucleation radius and free energy within the solidification range, enabling the cast Al-Li alloy to achieve a strength approaching 500 MPa.
Detecting and tracking low-flying targets at low-grazing angles is a difficult task due to the possible beam split and radar blind area. To alleviate this issue, we propose a frequency diverse subaperturing multiple-input multiple-output (FDS-MIMO) radar with optimized low-altitude beam coverage performance. A specular echo model is first formulated in the presence of multipath propagation together with a closed-form expression for the joint transmit-receive beampattern. Then, a perturbational echo model is developed for anomalous terrain. Moreover, a notional multipath mitigation region concept is defined together with the corresponding boundary conditions. The FDS-MIMO radar beam coverage capability is evaluated by the low observability rate. Furthermore, the FDS-MIMO radar low-altitude beam coverage is improved according to the solutions of boundary conditions, and an adaptive frequency offset design strategy is proposed for the changing environment. Both theoretical analysis and numerical results demonstrate that the optimized FDS-MIMO radar outperforms conventional phased-array radar and MIMO radar in terms of low-altitude beam coverage performance.
Minimal siphons play an important role in the development of deadlock control policies for discrete event system modeled by Petri net. A new algorithm based on depth-first search of problem decomposition process is proposed to compute all minimal siphons in an ordinary Petri net. The algorithm can reduce the number of problems in the problem list. The proposed algorithm can solve the problem of high requirement for computer memory in computing all minimal siphons and decrease the memory consumption because the computer memory size is closely related to the number of problems in the problem list. Some examples are used to illustrate the superiority of the proposed algorithm.
Background The incidence of cardiac arrest (CA) during percutaneous coronary intervention (PCI) is relatively rare. However, when it does occur, the mortality rate is extremely high. Extracorporeal cardiopulmonary resuscitation (ECPR) has shown promising survival rates for in-hospital cardiac arrests (IHCA), with low-flow time being an independent prognostic factor for CA. However, there is no definitive answer on how to reduce low-flow time. Methods This retrospective study, conducted at a single center, included 39 patients who underwent ECPR during PCI between January 2016 and December 2022. The patients were divided into two cohorts based on whether standby extracorporeal membrane oxygenation (ECMO) was utilized during PCI: standby ECPR (SBE) ( n = 13) and extemporaneous ECPR (EE) ( n = 26). We compared the 30-day mortality rates between these two cohorts and investigated factors associated with survival. Results Compared to the EE cohort, the SBE cohort showed significantly lower low-flow time ( P < 0.01), ECMO operation time ( P < 0.01), and a lower incidence of acute kidney injury (AKI) ( P = 0.017), as well as peak lactate ( P < 0.01). Stand-by ECMO was associated with improved 30-day survival ( p = 0.036), while prolonged low-flow time ( p = 0.004) and a higher SYNTAX II score ( p = 0.062) predicted death at 30 days. Conclusions Standby ECMO can provide significant benefits for patients who undergo ECPR for CA during PCI. It is a viable option for high-risk PCI cases and may enhance the overall prognosis. The low-flow time remains a critical determinant of survival.
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