Compact multiphoton/single photon laser scanning microscope for spectral imaging and fluorescence lifetime imaging

An inverted fluorescence microscope was upgraded into a compact three-dimensional laser scanning microscope (LSM) of 65 x 62 x 48 cm dimensions by means of a fast kHz galvoscanner unit, a piezodriven z-stage, and a picosecond (ps) 50 MHz laser diode at 405 nm. In addition, compact turn-key near infrared femtosecond lasers have been employed to perform multiphoton fluorescence and second harmonic generation (SHG) microscopy. To expand the features of the compact LSM, a time-correlated single photon counting unit as well as a Sagnac interferometer have been added to realize fluorescence lifetime imaging (FLIM) and spectral imaging. Using this unique five-dimensional microscope, TauMap, single-photon excited (SPE), and two-photon excited (TPE) cellular fluorescence as well as intratissue autofluorescence of water plant leaves have been investigated with submicron spatial resolution, <270 ps temporal resolution, and 10 nm spectral resolution.     

1H-MRS of femoral red and yellow bone marrow fat composition and water content in healthy young men and women at 3 T

Magnetic Resonance Materials in Physics, Biology and Medicine - There is a discrepancy between studies suggesting that higher bone marrow fat saturation is associated with impaired health, and...     

Impact of Processing on Structural and Compositional Evolution in Mixed Metal Halide Perovskites during Film Formation

Understanding crystallization processes and their pathways in metal‐halide perovskites is of crucial importance as this strongly affects the film microstructure, its stability, and device performance. While many approaches are developed to control perovskite formation, the mechanisms of film formation are still poorly known. Using time‐resolved in situ grazing incidence wide‐angle X‐ray scattering, the film formation of perovskites is investigated with average stoichiometry Cs_0.15FA_0.85PbI₃, where FA is formamidinium, using the popular antisolvent dropping and gas jet treatments and this is contrasted with untreated films. i) The crystallization pathways during spin coating, ii) the subsequent postdeposition thermal annealing, and iii) crystallization during blade coating are studied. The findings reveal that the formation of a nonperovskite FAPbI₃ phase during spin coating is initially dominant regardless of the processing and that the processing treatment (e.g., antisolvent dropping, gas jet) has a significant impact on the as‐cast film structure and affects the phase evolution during subsequent thermal treatment. It is shown that blade coating can be used to overcome the nonperovskite phase formation via solvothermal direct crystallization of perovskite phase. This work shows how real‐time investigation of perovskite formation can help to establish processing–microstructure–functionality relationships.     

Efficient CFD Simulation Model for a Planetary Gearbox

Planetary gears are used to transmit power at high gear ratios in limited space. Typical applications are drive trains in the automotive industry, e.?g. in cars, trucks and buses. The oil distribution in planetary gearboxes is difficult to predict. There is only basic knowledge about lubrication designs with effective oil distribution and high efficiency. Advanced methods are very helpful in improving the design of planetary gearboxes in respect of their lubrication.In recent years, CFD (computational fluid dynamics) has become a valuable tool for simulating the oil distribution in gearboxes. By comparison with experimental and empirical methods, CFD provides oil distribution simulation results and can be applied to arbitrary geometries. However, CFD simulations tend to require comparatively high computing time and capacities. Therefore, efficient CFD simulation models are required, especially for complex gearbox topologies.Within the framework of this study, a finite volume CFD model of a dip-lubricated planetary test gearbox has been developed. It includes the modelling of all gear meshes and bearings and has a very high level of detail. The element number was reduced as far as reasonable possible, resulting in little computing time with regard to the modeling depth. Moreover, the computational effort was further reduced by considering the bearings to be static. Through use of the developed simulation model, the influence of different parameters was investigated. This work will help to improve the lubrication design of planetary gearboxes.     

Improved calculation method for load-dependent gear losses

The topic of this study is to investigate the load-dependent losses of practical spur gears, for which the existing calculation method is analyzed in detail and improved.In drive technology, spur gears are frequently used for the transformation of torque and speed. Power transmission always involves power losses. Thereby, particular interest has to be given to the load-dependent gear loss as it often accounts for a large share of the total loss.According to the state of the art, the calculation of load-dependent gear loss is mainly based on (i) gear loss factors derived from simplified load distributions and (ii) a mean coefficient of friction derived from empirical equations based on spur gears without flank modifications. In practice, however, helical gears for improved NVH (Noise-Vibration-Harshness) behavior and flank modifications for uniform contact patterns are used. The modified mesh and contact conditions of modified helical gears affect the load-dependent gear losses significantly. Hence, significant deviations compared to the state of the art can occur.Comprehensive experimental investigations at the FZG efficiency test rig and FZG Bearing power loss test rig have been carried out to investigate the load-dependent gear losses of modified helical gears. The results are used to improve an existing calculation method that distinguishes between geometrical and tribological influence factors. Thereby, the local mesh and contact conditions along the plane of action are considered by the gear loss factor H_VL according to Wimmer, whereas the calculation of the mean coefficient of friction µ_mz has been enhanced by regression analyses. A comparison of the improved calculation method to the state of the art shows improved accuracy for determining the load-dependent gear losses and hence the efficiency of gear boxes.     

Alternative microstructures and their influence on mechanical properties of case-hardened gears

Forschung im Ingenieurwesen - Case hardening is one of the most common heat treatment processes for highly loaded shafts and gears. Due to numerous investigations, a&nbsp;microstructure...     

Efficiency and heat balance calculation of worm gears

Forschung im Ingenieurwesen - Worm gears enable compact gear design and high power density due to a&nbsp;high gear ratio within a&nbsp;single gear stage. However, they often show high...     

Verkürzte Lebensdauertests von Zahnradgetrieben unter Lastkollektivbeanspruchung

Forschung im Ingenieurwesen - Im Rahmen dieses Beitrags wird ein Vorgehensmodell zur Planung und Durchführung von verkürzten Lebensdauertests bei Zahnradgetrieben vorgestellt, um einen...