类风湿关节炎合并骨折患者的围手术期处理

类风湿关节炎好发于中老年人,其病情复杂、合并症多,一旦发生骨折则围手术期处理难度大且风险较高。本文就类风湿关节炎患者骨折围手术期评估、围手术期用药管理及骨折的预防进行综述,以期减少此类患者围手术期风险,保障医疗安全

动态载荷下Al—Li合金剪切变形局部化

采用Ｈｏｐｋｉｎｓｏｎ压杆装置，对４种时效处理的Ａｌ－Ｌｉ合金在冲击压缩试验时变形局部化产生的力学条件和微结构进行了研究，结果指出，４种处理的合金均产生两种类型的剪切带即形变剪切带和白剪切带，它们是在局部化过程中不同形变阶段下形的。两者无本质上的差别。白色剪切带内未发生相变。大应变和高应变率是产生力剪切带的必要条件，即材料在一定的高应变率下形变到一定程度时才能形成剪切带，电镜研究表明，剪切带内无畸

Quasi-transverse optical phonon mode in self-generated semipolar AlN grains embedded in c-oriented AlN matrix grown on sapphire using hydride vapor phase epitaxy

In this study, we present a microspectroscopic investigation on the quasi-transverse optical phonon modes Q(TO) in some self-generated aluminum nitride (AlN) grains grown on sapphire using hydride vapor phase epitaxy. Using X-ray diffraction and transmission electron microscope, these grains were confirmed to be embedded in (0001)-AlN (c-AlN) epitaxial matrix with an appearance plane of (10 (1) over bar1) (s-plane). Two beam bright field images further showed that the AlN grains were free of dislocation. In-plane phonon anisotropy of the AlN grains was discussed in detail using angular-dependent polarized Raman spectroscopy. The dependence of pure Raman phonons intensity on rotation angle agrees well with the calculation. The Q(TO) phonon intensity exhibited similar behavior to that of A(1)(TO) phonon, which can be explained by Loudon's formula. However, the observed frequency fluctuation for the Q(TO) phonon differs from that of the pure phonon modes, which cannot be directly understood from the classic Loudon's formula. A modified Loudon's formula appropriate to non-normal incidence was presented to explain the observed Q(TO) phonon frequency fluctuation. Combining with the angular-dependent Raman spectra, we proposed that a small inclination of s-plane along with the various in-plane orientations in c-AlN matrix lead to the frequency fluctuation of Q(TO) in these embedded semipolar AlN grains. Published by AIP Publishing