Direct numerical study of hypersonic flow about a swept parabolic body

Direct numerical simulations (DNS) of hypersonic flow about a swept parabolic body have been performed to study the global stability of flow in the leading-edge region of a swept blunt body. Previous stability investigations have been based on local models but have not fully succeeded in reproducing the established experimental findings. The current flow configuration represents a more realistic model and is thus expected to resolve some of the remaining questions. However, novel approaches like DNS-based global stability theory are necessary for such flow models and are employed in this study. As a result, boundary-layer modes have been identified by different but complementary techniques as the dominant instability mechanism. The DNS starting with small-amplitude white noise provide further evidence for the presence of non-modal effects which may be important in the subcritical regime. From a methodological point of view, the potential for quantitative flow analysis by combining numerical simulations with advanced iterative techniques represents a promising direction for investigating the governing physical processes of complex flows.     

Copper‐Catalyzed Asymmetric Conjugate Addition of Dimethylzinc to Acyl‐N‐methylimidazole Michael Acceptors: Scope,Limitations and Iterative Reactions

An efficient copper‐catalyzed enantioselective conjugate addition of dimethylzinc to unsaturated 2‐acyl‐N‐methylimidazoles has been achieved using a chiral bidentate hydroxyalkyl‐NHC ligand. The reactions proceed with excellent regioselectivity (1,4 vs. 1,6 and 1,8) in extended conjugated systems to afford the 1,4‐adducts in high enantioselectivities. This regioselectivity could be ascertained by DFT studies highlighting the crucial role of the imidazole ring. Thanks to the development of efficient protocols to regenerate the unsaturated 2‐acyl‐N‐methylimidazole moiety, an iterative process has been developed ultimately leading to 3,5,7 all‐syn or anti‐anti polydeoxypropionate stereodiads.

     

Crack depth measurements in stainless steel pipes - methods and reliability

It still is a challenging development goal to improve sizing of di discontinuities by using NDT, since essential characteristics, as for instance crack depth extension, in many cases only can be evaluated within the scope of a large scale measurement: New NDT-techniques such as specially designed UT-probes to suit the test problem, and also a substantially extended theoretical background contribute to reliable statements concerning crack depth.The development of imaging UT-reconstruction methods will help to improve this situation. Practical experience with genuine testing problems are needed to judge the evidence of these methods. Experience with manual crack depth measurements is quite useful to create a practicable and reliable instrument based on reconstruction methods.     

A parallel multigrid accelerated Poisson solver for ab initio molecular dynamics applications

In this paper we present an application for a parallel multigrid solver in 3D to solve the Coulomb problem for the charge self interaction in a quantum-chemical program used to perform ab initio molecular dynamics. Techniques such as Mehrstellendiscretization and τ-extrapolation are used to improve the discretization error. The results show that the expected convergence rates and parallel performance of the multigrid solver are achieved. Within the applied Carr–Parrinello Molecular Dynamics scheme the quality of the solution also determines the accuracy in energy conservation. All forms of discretization employed lead to energy conserving dynamics. In order to test the applicability of our code to larger systems in a massively parallel environment, we investigated a 256 atom periodic supercell of bulk gallium nitride.     

Bronchiolitis obliterans organizing pneumonia and chronic graft-versus-host disease in a child after allogeneic bone marrow transplantation

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) subtype O infections are not reliably detected by commonly used anti-HIV-1/2 screening assays. Therefore, anti-HIV-1/2 assays have been modified to increase their sensitivity in detecting antibodies to HIV-1 subtype O. STUDY DESIGN AND METHODS: Two new anti-HIV-1/2 enzyme-linked immunosorbent assays (ELISAs) (Abbott Plus and Ortho Enhanced) were compared with a currently used anti-HIV-1/2 ELISA (Abbott Recombinant) in various serum panels: 91 Western blot-confirmed anti-HIV-1-positive samples, 20 samples from Western blot-confirmed HIV-1-infected patients in log3 serial dilutions, and 1463 samples from consecutive, volunteer, nonremunerated blood donors. RESULTS: Among 91 anti-HIV-1 Western blot-positive samples, 2 (2.2%) were missed by the Abbott Recombinant ELISA, but all 91 were detected by the Abbott Plus and Ortho Enhanced ELISAs. In contrast, two discrepant samples were found to react in viral lysate-based assays. In serial dilutions, Ortho Enhanced ELISA was significantly less sensitive than the Abbott Recombinant and Abbott Plus ELISAs, with the latter two being of comparable sensitivity. The specificities of Abbott Recombinant, Abbott Plus, and Ortho Enhanced ELISAs in 1463 blood donors were 100, 99.93, and 99.86 percent, respectively. Routine testing of 29,102 donations with the enhanced Abbott Plus ELISA revealed a specificity of 99.93 percent. CONCLUSION: Two Western blot-confirmed anti-HIV-1-positive samples were missed by the Abbott Recombinant ELISA but detected by the Abbott Plus and Ortho Enhanced ELISAs. The analytic sensitivity of the Ortho Enhanced ELISA was inferior to that of both Abbott ELISAs. The specificities of the Abbott Recombinant, Abbott Plus, and Ortho Enhanced ELISAs were comparable.     

Numerical simulation and analytical description of thermallyinduced birefringence in laser rods

The results of numerical simulations based on finite-element methods for thermally induced birefringence in Nd:YAG crystal rods are compared with measurements and analytical solutions. A novel analytical solution for inhomogeneous pumping is presented. It is shown that the behavior of thermally induced birefringence is very sensitive to the pump geometry