Experimental studies for the surgical correction and fixation of dorsal spine deformities

One of the specific features of the scoliosis operations with a posterior approach is that both the correction of the deformity and then the maintaining of the corrected situation are carried out with the help of the implants. With the currently applied systems based on the CD principle it is still difficult to control the rotational component of the scoliotic curve. To complement the systems based on the CD principle, we have developed an implant family whose application makes the correction of the dorsal deformity generally simplier and derotation more effective. Our method is based on the application of such hooks which, linked to the longitudinal rods and hooked on both transverse processes of the instrumented vertebrae, transmit the concerted forces exerting their influence in the direction of the correction. Depending on their symmetrical relations, the hooks are capable of tilting in the frontal plane and derotating in the horizontal plane simultaneously, in the direction of our choice. The stability and applicability of the hooks were tested in implants into cadavers, and then the intimate relations of the implants were examined by means of radiological tests and dissection on instrumented specimens. On the basis of our results, the implants can already be used in clinical practice.     

我的美国微软面试经历

当年我就读于UCLA（美国加州大学），从三年级下学期开始找工作。简历准备了相当长的时间，之后投了很多美国大公司，如微软、IBM，摩根士丹利、高盛及P＆G等众多知名企业。几个星期后，这些大公司陆续到学校开招聘会。招聘方比较看重的首先是你的专业和专业的平均分数（GPA，这些大公司要求学生的GPA都要3，5以上，除非你有一些过人之处），再就是你在学校里参与活动多不多。人际关系怎么样。幸运的是这几家大公司都有通知我去面试。而最让我难忘记的就是申请微软解决方案顾问工程师职位的面试。     

Exchange Energy for Two-Active-Electron Diatomic Systems Within the Surface Integral Method

We have analyzed and reduced a general (quantum-mechanical) expression for the atom-atom exchange energy formulated as a five-dimensional surface integral, which arises in studying the charge exchange processes in diatomic molecules. It is shown that this five-dimensional surface integral can be decoupled into a three-dimensional integral and a two-dimensional angular integral which can be solved analytically using a special decomposition. Exact solutions of the two-dimensional angular integrals are presented and generalized. Algebraic aspects, invariance properties and exact solutions of integrals involving Legendre and Chebyshev polynomials are also discussed.     

Therapeutic value of continuous passive motion after anterior cruciate replacement

The aim of this study is the evaluation of the therapeutic value of continuous passive motion after ACL replacement. After 41 ACL reconstruction in 13 cases only active motion, in 28 cases active motion and CPM were used postoperatively. Stability, the range of motion and complications were evaluated at the time of discharge, 3 and 6 months after the operation. The flexion-extension in the CPM group was significantly greater at the time of discharge, but this difference was practically eliminated in 6 months after the operation. There were not any other significant difference between the two groups. The CPM gives only a little advantage in the rehabilitation after the ACL replacement.     

Synthesis and study of new functionalized silica aerogel poly(methyl methacrylate) composites for biomedical use

Monolithic silica aerogels are nanostructured solids characterized with exceptionally high porosity and specific surface area. Although their strength can be improved by surface treatment with polymers, none of them has been tested yet as a filler in biocompatible polymer composites. The new aerogel–poly(methyl methacrylate) composites were prepared by free radical bulk polymerization of neat methyl methacrylate in the presence of natural and functionalized silica aerogels at 60°C, using cumene hydroperoxide initiator and 4,N,N‐trimethyl‐aniline redox pair. Synthetic conditions were set to be most similar to the setting of orthopedic bone cements. Structures, compositions, and molecular weight distributions were determined by scanning electron microscopy, combustion analysis, and gel permeation chromatography, respectively. Compressive strength, Shore D hardness and Gardner's impact strength were measured, and the fracture properties were compared to the matrices. All four aerogel fillers resulted in significant enhancement in compressive strength, reaching a maximum value of 123 MPa. Dissolution of H103PC‐1 natural and H106PB‐1 C16 modified aerogel containing specimens in simulated body fluid occurred in 20 days, leaving porous surfaces behind, which may give rise to higher tissue adhesion potential in bone cements. Heat treated silica aerogel in H112PA‐1 showed no leaching out, and its composites might be usefull in high‐load technical applications. POLYM. COMPOS., 36:348–358, 2015. © 2014 Society of Plastics Engineers