The geometry, electronic structure and magnetic property of the hexagonal AlN (h-AlN) sheet doped by 5d atoms (Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au and Hg) are investigated by first-principles calculations based on the density functional theory. The influence of symmetry and symmetry-breaking is also studied. There are two types of local symmetries of the doped systems: C 3v and D 3h . The symmetry will deviate from exact C 3v and D 3h for some particular dopants after optimization. The total magnetic moments of the doped systems are 0µ B for Lu, Ta and Ir; 1µ B for Hf, W, Pt and Hg; 2µ B for Re and Au; and 3µ B for Os and Al-vacancy. The total densities of state are presented, where impurity energy levels exist. The impurity energy levels and total magnetic moments can be explained by the splitting of 5d orbitals or molecular orbitals under different symmetries.
The technique of stent-assisted coil embolization has been widely used in the clinic, while its efficacy and safety have yet to be evaluated. This study investigates the values of computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA) in evaluating the Enterprise stent-assisted coil embolization in the treatment of intracranial wide-necked aneurysm.A total of 578 intracranial wide-necked aneurysm patients confirmed by MRA + CTA + DSA examinations were included and treated with Enterprise stent-assisted coil embolization in this study. All patients were assigned into complete embolization (CE) group and incomplete embolization (IE) group according to the results of postoperative MRA + CTA + DSA examinations and Raymond grades. Hunt-Hess grades, incidence of complication and Glasgow Outcome Scale (GOS) grades of patients were investigated to assess the therapeutic effect of Enterprise stent-assisted coil embolization in intracranial wide-necked treatment. Multivariate logistic regression analysis was performed to assess risk factors for the therapeutic effect of Enterprise stent-assisted coil embolization in intracranial wide-necked aneurysm.CTA images offered a better and clearer view than MRA and DSA images in both the CE and IE groups. Both the sensitivity and specificity of CTA were apparently higher than those of MRA. Patients in the CE group enjoyed a higher good GOS rate but a lower incidence of complication than those in the IE group. In Enterprise stent-assisted coil embolization treatment, the Hunt-Hess grade, hypertension, and size of artery aneurysm were independent factors affecting the therapeutic effect of Enterprise stent-assisted coil embolization in intracranial wide-necked aneurysm.Compared with MRA, CTA shows a higher value in evaluating the therapeutic effect of Enterprise stent-assisted coil embolization for the treatment of intracranial wide-necked aneurysm, and can thus serve as an important means of predicting the therapeutic effect of endovascular intervention in treating patients with intracranial wide-necked aneurysm.
The traditional wind-induced response analysis of high-rise buildings conventionally considers the wind load as a stationary stochastic process. That is, for a certain wind direction angle, the reference wind speed (usually refers to the mean wind speed at the building height) is assumed to be a constant corresponding to a certain return period. Combined with the recorded data in wind tunnel test, the structural response can be computed using the random vibration theory. However, in the actual typhoon process, the average wind speed is usually time-variant. This paper combines the interval process model and the nonrandom vibration analysis method with the wind tunnel test and proposes a method for estimating the response boundary of the high-rise buildings under nonstationary wind loads. With the given upper and lower bounds of time-variant wind excitation, this method can provide an effective calculation tool for estimating wind-induced vibration bounds for high-rise buildings under nonstationary wind load. The Guangzhou East tower, which is 530 m high and the highest supertall building in Guangzhou, China, was taken as an example to show the effectiveness of the method. The obtained boundary response can help disaster prevention and control during the passage of typhoons.
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