Manganese-doped ZnO nanobelts for spintronics

©2004 American Institute of Physics. The electronic version of this article is the complete one and can be found online at: http://link.aip.org/link/?APPLAB/84/783/1DOI:10.1063/1.1645319Zinc oxide (ZnO) nanobelts synthesized by thermal evaporation have been ion implanted with 30 keV Mn+ ions. Both transmission electron microscopy and photoluminescence investigations show highly defective material directly after the implantation process. Upon annealing to 800 °C, the implanted Mn remains in the ZnO nanobelts and the matrix recovers both in structure and luminescence. The produced high-quality ZnO:Mn nanobelts are potentially useful for spintronics

3D composite finite elements for elliptic boundary value problems with discontinuous coefficients

For scalar and vector-valued elliptic boundary value problems with discontinuous coefficients across geometrically complicated interfaces, a composite finite element approach is developed. Composite basis functions are constructed, mimicing the expected jump condition for the solution at the interface in an approximate sense. The construction is based on a suitable local interpolation on the space of admissible functions. We study the order of approximation and the convergence properties of the method numerically. As applications, heat diffusion in an aluminium foam matrix filled with polymer and linear elasticity of micro-structured materials, in particular specimens of trabecular bone, are investigated. Furthermore, a numerical homogenization approach is developed for periodic structures and real material specimens which are not strictly periodic but are considered as statistical prototypes. Thereby, effective macroscopic material properties can be computed

Robot-assisted Radical Prostatectomy Using Single-port Perineal Approach: Technique and Single-surgeon Matched-paired Comparative Outcomes

Background: Radical perineal prostatectomy (RPP) has been revived with the advent of single-port (SP) robotic surgery. However, its interest and precise role need to be evaluated and better defined. Objective: To describe in detail the technique of SP-RPP and compare initial perioperative outcomes with those of multiport robot-assisted transperitoneal radical prostatectomy (MP-RARP). Design, setting, and participants: From October 2018 to June 2020, perioperative data of 26 consecutive patients who underwent SP-RPP for localized prostate cancer (PCa) in a single institution were prospectively entered into an institutional review board-approved database. Data of 86 consecutive patients treated from September 2017 to September 2018 with MP-RARP by the same surgeon, before the beginning of the SP experience, were used as comparators. Surgical procedure: SP-RPP was performed using the SP robotic platform (Intuitive Surgical, Sunnyvale, CA, USA) according to the technique described in the supplementary video. Measurements: Demographics, and intra- and postoperative data were analyzed in a matched-paired design with a 1:1 ratio on the following factors: age at surgery, prostatespecific antigen level, preoperative Gleason score, and history of abdominal surgery. Results and limitations: After matching, baseline characteristics were comparable except for the rate of prior laparotomy, which was higher in the SP-RPP group (52% vs 8%, p < 0.001). In the SP-RPP group, 84% of the patients had a high risk and an unfavorable intermediate risk of positive surgical margins (PSMs) versus 57% in the MPRARP group (p = 0.03). While the rate of nonlimited PSMs (ie, >3 mm) was higher in the SP-RPP group (38.5% vs 7.7%, p < 0.01), the number of patients with biochemical recurrence at 1 yr was comparable between SP-RPP and MP-RARP (1 vs 3, p = 0.3). Conclusions: SP-RPP is a complex procedure for patients with a complex surgical history and high-risk localized PCa with limited alternative therapeutic options. Patient summary: Our study suggests that patients with high-risk localized prostate cancer and limited treatment options due to a complex abdominal surgical history (ie, frozen pelvis) may be suitable candidates for single-port radical perineal prostatectomy. (C) 2020 European Association of Urology. Published by Elsevier B.V. All rights reserved

Composite finite elements for 3D image based computing

We present an algorithmical concept for modeling and simulation with partial differential equations (PDEs) in image based computing where the computational geometry is defined through previously segmented image data. Such problems occur in applications from biology and medicine where the underlying image data has been acquired through, e.g. computed tomography (CT), magnetic resonance imaging (MRI) or electron microscopy (EM). Based on a level-set description of the computational domain, our approach is capable of automatically providing suitable composite finite element functions that resolve the complicated shapes in the medical/biological data set. It is efficient in the sense that the traversal of the grid (and thus assembling matrices for finite element computations) inherits the efficiency of uniform grids away from complicated structures. The method’s efficiency heavily depends on precomputed lookup tables in the vicinity of the domain boundary or interface. A suitable multigrid method is used for an efficient solution of the systems of equations resulting from the composite finite element discretization. The paper focuses on both algorithmical and implementational details. Scalar and vector valued model problems as well as real applications underline the usability of our approach