Mathematical modelling of influence functions in computer-controlled polishing: Part I

Computer-controlled polishing (CCP) is commonly used to finish high-quality surfaces, such as optical lenses. Based on magnetorheological finishing (MRF), a mathematical model to calculate the polishing tool characteristic (influence function) was developed and verified experimentally. The first part of this paper introduces the model to predict the size and shape of an influence function. The second part of this paper describes the calculation of the distribution of material removal within the size of an influence function. The model supersedes the current cumbersome procedure for determining an influence function and thus results in considerably improved and more economical manufacture. Furthermore, the model enables the quality of the final surface to be enhanced when polishing complex, for example aspherical or free-form, workpiece geometries and provides the first step in the application of time-variant influence functions.     

Effect of alcohol consumption on whole-body protein turnover in healthy adults

The aim of the study was to investigate the whole-body protein turnover, either before or after continuous, moderate ethanol-induced oxidative stress by red wine consumption over a relatively short period in healthy volunteers. Ten healthy adults received an individual regular diet over 20 days. After 10 days, the subjects consumed 0.4 ml ethanol kg(-1) day(-1) as red wine together with dinner over a 10-day period. After 8 and 18 days, respectively, a (15)N-labelled yeast protein was administered in a dosage of 4.2 mg kg(-1) body weight. Urine and faeces were collected over 48 h, respectively. The (15)N-enrichment was measured by isotope ratio mass spectrometry, whereas the protein flux rates were calculated by a three-compartment model. The whole-body protein turnover without/with red wine consumption amounted to 3.73±0.6 and 3.49±0.6 g kg(-1) day(-1) (not significant), respectively. Moderate alcohol consumption does not induce significant short-term changes in the whole-body protein turnover of healthy adults.     

Spectral narrowing and manipulation in an optical parametric oscillator using periodically poled lithium niobate electro-optic polarization-mode converters

We report a unique spectral narrowing and manipulation technique in an optical parametric oscillator (OPO) realized by an integrated periodically poled lithium niobate comprising an optical parametric gain medium sandwiched by two electro-optic polarization-mode converters (EO PMCs). We achieved a manipulation of the gain spectrum of the OPO via EO and/or temperature control of the EO PMCs, in which we obtained single to multiple signal spectral peaks from the OPO with a spectral width reduced by up to 10 times and peak intensity increased by up to 6 times in comparison with the original signal. Fast EO tuning of the narrowed signal spectral peak has also been demonstrated.     

On the full holonomy group of Lorentzian manifolds

The classification of restricted holonomy groups of \(n\) -dimensional Lorentzian manifolds was obtained about ten years ago. However, up to now, not much is known about the structure of the full holonomy group. In this paper we study the full holonomy group of Lorentzian manifolds with a parallel null line bundle. Based on the classification of the restricted holonomy groups of such manifolds, we prove several structure results about the full holonomy. We establish a construction method for manifolds with disconnected holonomy starting from a Riemannian manifold and a properly discontinuous group of isometries. This leads to a variety of examples, most of them being quotients of pp-waves with disconnected holonomy, including a non-flat Lorentzian manifold with infinitely generated holonomy group. Furthermore, we classify the full holonomy groups of solvable Lorentzian symmetric spaces and of Lorentzian manifolds with a parallel null spinor. Finally, we construct examples of globally hyperbolic manifolds with complete spacelike Cauchy hypersurfaces, disconnected full holonomy and a parallel spinor.     

Investigation of turbulence modification in a non-reactive two-phase flow

In a two-phase flow the influence of a dispersed phase on the turbulence properties of a continuous phase, known as turbulence modification, is investigated. An experimental approach is discussed that is suitable for studying the decay of grid-generated turbulence in a vertically orientated wind tunnel with a cross-section large enough to avoid influences from walls. Phase Doppler anemometry is used to characterize both single and two-phase flow by measuring mean axial and radial velocity components, velocity fluctuations, turbulent kinetic energy, and integral time scales. By direct comparison of results from single- and two-phase flows, the feedback of the dispersed phase on the continuous phase can be isolated. The data is used to deduce a source term for particle-induced turbulence production appropriate for a numerical simulation of the flow, based on the Reynolds-averaged Navier-Stokes equations. Although of special importance for a detailed understanding of turbulent two-phase combustion, additional complexity introduced by evaporation and chemical reactions is avoided by using glass beads as dispersed phase.     

Utilizing Paper-Based Devices for Antimicrobial-Resistant Bacteria Detection

Antimicrobial resistance (AMR), the ability of a bacterial species to resist the action of an antimicrobial drug, has been on the rise due to the widespread use of antimicrobial agents. Per the World Health Organization, AMR has an estimated annual cost of USD 34 billion in the US and is predicted to be the number one cause of death worldwide by 2050. One way AMR bacteria can spread, and by which individuals can contract AMR infections, is through contaminated water. Monitoring AMR bacteria in the environment currently requires that samples be transported to a central laboratory for slow and labor intensive tests. We have developed an inexpensive assay using paper-based analytical devices (PADs) that can test for the presence of β-lactamase-mediated resistance. To demonstrate viability, the PAD was used to detect β-lactam resistance in wastewater and sewage and identified resistance in individual bacterial species isolated from environmental water sources.     

Bis(dibenzo[c.e][1,2]oxaphosphorino)dichloroplatinum Complexes

Reaction of a series of P-amino and P-cycloalkoxy dibenzo[c.e][1,2]oxaphosphorines (1), (3) and (5) with cis-bis(benzonitrile)dichloroplatinum(II) afforded the title bis(dibenzooxaphosphorino) complexes (2), (4) and (6), respectively. In the case of chiral P-substituents, the complexes (4) and (6) were obtained in homo and heterochiral forms. Stereospecific ¹J(¹⁹⁵Pt–P) couplings found in the ³¹P-n.m.r. spectra of the products (2), (4) and (6) suggested the cis orientation of the identical substituents.     

Die Methode zur chromatographischen Trennung von Gallenfarbstoffen

Ohne Zusammenfassung     

Steroide

Ohne Zusammenfassung