For industrial tail gas to be converted into high-purity hydrogen, the H2-N2 mixture needs to be separated efficiently. This work examined the adsorption characteristics and competitive mechanisms of ...H2 and N2 on LTA- and FAU-type zeolites, at 77 K, 298 K, and 0.1–10 bar by thoroughly analyzing results of adsorption capacity experiments and molecular simulations. In the Grand Canonical Monte Carlo (GCMC) simulations, the force field causing a molecular dipole of H2 and the polarization force field of N2 are first applied. The accuracy of the force field was experimentally verified. The findings indicate that N2 and H2 loading on Ca-FAU (Ca-LTA) are higher than Na-FAU (Na-LTA). On NaX at 77 K, the highest adsorption selectivity (N2/H2) is observed; on NaA at 298 K, it is the opposite. The GCMC data findings demonstrate that H2 and N2 have remarkably similar adsorption sites, with framework oxygen atoms and non-framework cations serving as the main adsorption sites for adsorbate molecules. Furthermore, the rate at which H2 diffuses is higher than that of N2. The study of redistribution charge before and after adsorption demonstrated that N2 has a greater affinity for the framework oxygen atoms than H2. This study provides a molecular theoretical foundation for the adsorption behavior of H2-N2 mixture in zeolites.
The scanning of bridge surface roughness by the test vehicle is a coupled and non-stationary problem since the bridge deflection caused by vehicles will inevitably enter into the vehicle response. To ...this end, a two-step procedure is proposed to retrieve the bridge surface profile from the noise-contaminated responses of a two-axle vehicle moving over bridges. Central to this is the elimination of the bridge deflection from the estimated unknown input to the test vehicle system. First, the extended Kalman filter with unknown inputs (EKF-UI) algorithm is extended to formulating the state-space equations for the moving vehicle over the bridge. Analytical recursive solutions are derived for the improved vehicle states and the unknown input vector consisting of the vehicle-bridge contact displacement and surface profile. Second, the correlation between the cumulated contact residuals and contact displacements for the two axles is approximately defined by using the vehicle's parameters and location on the bridge. Then, the surface profile is retrieved from the unknown input by removing the roughness-free contact (bridge) displacement, calculated with no prior knowledge of bridge properties. The efficacy of the proposed procedure was validated by the finite element method and demonstrated in the parametric study for various properties of the system. It is confirmed that the retrieved bridge surface profile is in excellent agreement with the original (assumed). For practical use, the vehicle is suggested to run at a not-too-high speed or in a too noisy environment. The proposed technique is robust with regard to vehicle mass and bridge damping.
Hydrofluorocarbons (HFCs) have important applications in different industries; however, they are environmentally unfriendly due to their high global warming potential (GWP). Hence, reclamation of ...used hydrofluorocarbons via energy-efficient adsorption-based separation will greatly contribute to reducing their impact on the environment. In particular, the separation of azeotropic refrigerants remains challenging, such as typical mixtures of CH2F2 (HFC-23) and CHF3 (HFC-32), due to a lack of adsorptive mechanisms. Metal–organic frameworks (MOFs) can provide a promising solution for the separation of CHF3–CH2F2 mixtures. In this study, the adsorption mechanism of CHF3–CH2F2 mixtures in TIFSIX-2-Cu-i was revealed at the microscopic level by combining static pure-component adsorption experiments, molecular simulations, and density-functional theory (DFT) calculations. The adsorption separation selectivity of CH2F2/CHF3 in TIFSIX-2-Cu-i is 3.17 at 3 bar under 308 K. The existence of similar TiF62− binding sites for CH2F2 or CHF3 was revealed in TIFSIX-2-Cu-i. Interactions between the fluorine atom of the framework and the hydrogen atom of the guest molecule were found to be responsible for determining the high adsorption separation selectivity of CH2F2/CHF3. This exploration is important for the design of highly selective adsorbents for the separation of azeotropic refrigerants.
Gravitational waves from coalescences of neutron stars or stellar-mass black holes into intermediate-mass black holes (IMBHs) of ≳100 solar masses represent one of the exciting possible sources for ...advanced gravitational-wave detectors. These sources can provide definitive evidence for the existence of IMBHs, probe globular-cluster dynamics, and potentially serve as tests of general relativity. We analyse the accuracy with which we can measure the masses and spins of the IMBH and its companion in intermediate-mass-ratio coalescences. We find that we can identify an IMBH with a mass above 100 M⊙ with 95 per cent confidence provided the massive body exceeds 130 M⊙. For source masses above ∼200 M⊙, the best measured parameter is the frequency of the quasi-normal ringdown. Consequently, the total mass is measured better than the chirp mass for massive binaries, but the total mass is still partly degenerate with spin, which cannot be accurately measured. Low-frequency detector sensitivity is particularly important for massive sources, since sensitivity to the inspiral phase is critical for measuring the mass of the stellar-mass companion. We show that we can accurately infer source parameters for cosmologically redshifted signals by applying appropriate corrections. We investigate the impact of uncertainty in the model gravitational waveforms and conclude that our main results are likely robust to systematics.
With the three dimensional (3D) oblique incident waves exactly determined for the free field, the soil seismic responses in both frequency and time domains are studied by the 2.5 dimension (2.5D) ...finite/infinite element method. First, the free-field responses in frequency domain are solved exactly for 3D arbitrary incident P and SV waves, which requires no coordinate conversion or extra effort for SV waves with super-critical incident angles. Next, the earthquake spectra are incorporated by the concept of equivalent seismic forces on the near-field boundary, based only on the displacements input derived for unit ground accelerations of each frequency using the 2.5D approach. For the asymmetric 2.5D finite/infinite element model adopted, the procedure for soil seismic analysis is presented. The solutions computed by the proposed method are verified against those of Wolf’s and de Barros and Luco’s and for inversely calculated ground motions. Of interest is that abrupt variation in soil response occurs around the critical angle on the wave propagation plane for SV waves. In addition, the horizontal displacements attenuate with increasing horizontal incident angle, while the longitudinal ones increase inversely for 3D incident P and SV waves.
Objective. The effect of postdilation in patients with acute coronary syndrome is still controversial. This meta-analysis aims to analyze the clinical and angiographic outcomes of postdilation after ...percutaneous coronary intervention in patients with acute coronary syndrome. Methods. PubMed, Embase, the Cochrane Library, Web of Science, CNKI, and Wangfang databases were searched from inception to August 30, 2020. Eligible studies from acute coronary syndrome patients treated with postdilation were included. The primary clinical outcome was major adverse cardiovascular events (MACE), the secondary clinical outcomes comprised all-cause death, stent thrombosis, myocardial infarction, and target vessel revascularization, and the angiographic outcomes were no reflow and slow reflow. Results. 11 studies met inclusion criteria. In clinical outcomes, our pooled analysis demonstrated that the postdilation had a tendency of decreasing MACE (OR = 0.67, 95% CI 0.45–1.00; P = 0.05) but significantly increased all-cause death (OR = 1.49, 95% CI 1.05–2.12; P = 0.03). No significant difference existed in stent thrombosis (OR = 0.71, 95% CI 0.40–1.26; P = 0.24), myocardial infarction (OR = 1.40, 95% CI 0.51–3.83; P = 0.51), and target vessel revascularization (OR = 0.61, 95% CI 0.21–1.80; P = 0.37) between postdilation and non-postdilation groups. In angiographic outcomes, there were no significant differences in no reflow (OR = 1.19, 95% CI 0.54–2.65; P = 0.66) and slow reflow (OR = 1.12, 95% CI 0.93–1.35; P = 0.24) between two groups. Conclusions. The postdilation tends to reduce the risk of MACE but significantly increases all-cause death, without significantly affecting stent thrombosis, myocardial infarction, target vessel revascularization, and coronary TIMI flow grade. However, more randomized controlled trials are required for investigating the effect of postdilation for patients with acute coronary syndrome (registered by PROSPERO, CRD42020160748).
The design of hydrophilic polyvinylidene fluoride (PVDF) membranes with anti-fouling properties has been explored for decades. Surface modification and blending are typical strategies to tailor the ...hydrophilicity of PVDF membranes. Herein, cyclodextrin was used to improve the antifouling performance of PVDF membranes. Cyclodextrin-modified PVDF membranes were prepared by coupling PVDF amination (blending with branched polyethyleneimine) and activated cyclodextrin grafting. The blending of PEI in the PVDF casting solution preliminarily aminated the PVDF, resulting in PEI-crosslinked/grafted PVDF membranes after phase inversion. Aldehydes groups on cyclodextrin, introduced by oxidation, endow cyclodextrin to be grafted on the aminated PVDF membrane by the formation of imines. Borch reduction performed on the activated cyclodextrin-grafted PVDF membrane converted the imine bonds to secondary amines, ensuring the membrane stability. The resulting membranes possess excellent antifouling performance, with a lower protein adsorption capacity (5.7 μg/cm2, indicated by Bovine Serum Albumin (BSA)), and a higher water flux recovery rate (FRR = 96%). The proposed method provides a facial strategy to prepare anti-fouling PVDF membranes.
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•The PEI-aminated PVDF membrane was modified by activated β-cyclodextrin.•The β-cyclodextrin was oxidized by NaIO4 to introduce aldehyde groups.•The β-cyclodextrin grafted membrane was stabilized by Borch reduction.•The modified PVDF showed excellent hydrophilicity and anti-protein fouling performance.
Previous researches have reported the controversial results regarding the gender difference in clinical outcomes of patients with coronary artery disease after percutaneous coronary intervention. ...Hence, this systematic review and meta-analysis was designed to investigate whether gender difference existed in patients with coronary artery disease after percutaneous coronary intervention.
PubMed, Embase, and the Cochrane Library database were searched up to February 10, 2018. Studies comparing the gender-specific effect on clinical outcomes of patients with coronary artery disease after percutaneous coronary intervention were identified, to analyze mortality, major adverse cardiovascular events (MACE) and revascularization. Statistical software RevMan was utilized in this meta-analysis.
A total of 49 studies, involving 1,032,828 patients (774,115 males and 258,713 females) reporting gender-specific outcomes, were included in this study. The in-hospital mortality, 30-day mortality, 1-year mortality, and at least 2-years mortality in male patients with coronary artery disease after percutaneous coronary intervention were significantly lower than those of females (odds ratio OR 0.58 95% confidence interval CI 0.52-0.63, P < .001; OR 0.64, 95% CI 0.61-0.66, P = .04; OR 0.67, 95% CI 0.60-0.75, P < .001 and OR 0.71, 95% CI 0.63-0.79, P = .005, respectively). The MACE was significantly decreased in male subjects after initial percutaneous coronary intervention compared with females in <1-year or at least 1-year (OR 0.67, 95% CI 0.56-0.80, P < .001 and OR 0.84, 95% CI 0.76-0.93, P < .001). The male patients after percutaneous coronary intervention harbored higher rate of revascularization compared with females for at least 1-year (OR 1.17, 95% CI 1.00-1.36, P < .001), while the rate of revascularization in male patients for < 1-year was lower than that of females (OR 0.93, 95% CI 0.69-1.26, P < .001).
The systematic review and meta-analysis suggests that the prognosis of male patients with coronary artery disease after percutaneous coronary intervention is better than that of females, except for long-term revascularization.
...no significant differences were found between the two groups in the rate of mark blood pressureOR=0.99, 95%CI(0.89, 1.09), P=0.78, the c-hange of systolic blood pressure(SBP)MD=-0.25,95%CI(-0.82, ...0.32), P=0.39, total cholesterol(TC)MD=-0.04, 95%CI(-0.20, 0.12), P=0.65, high density lipo-proteincholesterol(HDL-C)MD=0.24, 95%CI(-0.02, 0.50), P=0.07, low dens-ity lipoproteincholesterol(LDL-C)MD=-0.14, 95% CI(-0.44, 0.15), P=0.34, haemoglobinA1c(HbA1c) MD=-0.09, 95%CI(-0.21, 0.04), P=0.19, fasting plasma glucose(FPG)MD=-0.05, 95% CI(-0.18, 0.09), P=0.52, serum potas-siumMD=0.02, 95% CI(-0.04, 0.08), P=0.43and serum creatinine level of hy-pertension without obvious abnormal kidney function or diabetes mellitus groupMD=-0.02, 95% CI(-0.26, 0.21), P=0.85.
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