SMART-Reactors: Tailoring Gas Holdup Distribution by Additively Manufactured Lattice Structures

In chemical process engineering, fast gas-liquid reactions often suffer from an inefficient distribution of gas and therefore mixing and mass transfer performance. This study deals with the possibility of influencing the local gas holdup and bubble size distribution in a gas-liquid process using additively manufactured lattice structures (AMLS). The used measuring technique to study bubble size, velocity, and the local gas holdup is a photo-optical needle probe. By using AMLS, a significant radial homogenization of the local gas holdup and the mean bubble size is achieved. Furthermore, it can be demonstrated that the bubble size can be tailored by the geometry of the inserted structure. It is illustrated that the mean bubble velocities are lowered within the lattice resulting in a higher residence time of the dispersed phase with an impact on the mass transfer performance within the AMLS.     

Effect of pasture vs. concentrate diet on CLA isomer distribution in different tissue lipids of beef cattle

This study examined the effects of feeding pasture vs. concentrate on the distribution of CLA isomers in the lipids of longissimus and semitendinosus muscle, liver and heart muscle, and subcutaneous fat in beef bulls. Sixty-four German Holstein and German Simmental bulls were randomly allocated to either an indoor concentrate system or periods of pasture feeding followed by a finishing period on a concentrate containing linseed to enhance their beef content of n−3 PUFA and CLA. The concentrations of CLA isomers in the different tissues were determined by GC and silver ion HPLC. The diet affected the distribution of individual CLA isomers in the lipids of the different tissues. The concentration (mg/100 g fresh tissue) of the most prominent isomer, cis-9,trans-11 18∶2, was increased up to 1.5 times in liver and heart tissue of bulls fed on pasture as compared with concentrate. However, no diet effect was observed for cis-9,trans-11 18∶2 in the lipids of longissimus muscle and subcutaneous fat. In all tissues, the second-most abundant CLA isomer in concentratefed bulls was trans-7,cis-9 18∶2. In contrast, trans-11,cis-13 18∶2 was the second-most abundant CLA isomer in all investigated tissue lipids of pasture-fed bulls. The concentration of the trans-11,cis-13 18∶2 isomer was up to 15 times higher in tissues of pasture-fed bulls as compared with concentrate-fed animals. Furthermone, diet affected the concentrations of the CLA trans,trans 18∶2 isomers. Pasture feeding significantly increased the concentrations of some trans,trans 18∶2 isomers as compared with concentrate, predominantly trans-12,trans-14 18∶2 and trans-11,trans-13 18∶2. Overall, pasture feeding resulted in significantly increased concentrations of the sum of CLA isomers in the lipids of longissimus, muscle, subcutaneous fat, heart and liver muscle of German Holstein and German Simmental bulls, but not in semitendinosus muscle.     

On the Relation between Morphology and FET Mobility of Poly(3‐alkylthiophene)s at the Polymer/SiO2 and Polymer/Air Interface

The influence of the interface of the dielectric SiO₂ on the performance of bottom‐contact, bottom‐gate poly(3‐alkylthiophene) (P3AT) field‐effect transistors (FETs) is investigated. In particular, the operation of transistors where the active polythiophene layer is directly spin‐coated from chlorobenzene (CB) onto the bare SiO₂ dielectric is compared to those where the active layer is first spin‐coated then laminated via a wet transfer process such that the film/air interface of this film contacts the SiO₂ surface. While an apparent alkyl side‐chain length dependent mobility is observed for films directly spin‐coated onto the SiO₂ dielectric (with mobilities of ≈10^?3 cm² V^?1 s^?1 or less) for laminated films mobilities of 0.14 ± 0.03 cm² V^?1 s^?1 independent of alkyl chain length are recorded. Surface‐sensitive near edge X‐ray absorption fine structure (NEXAFS) spectroscopy measurements indicate a strong out‐of‐plane orientation of the polymer backbone at the original air/film interface while much lower average tilt angles of the polymer backbone are observed at the SiO₂/film interface. A comparison with NEXAFS on crystalline P3AT nanofibers, as well as molecular mechanics and electronic structure calculations on ideal P3AT crystals suggest a close to crystalline polymer organization at the P3AT/air interface of films from CB. These results emphasize the negative influence of wrongly oriented polymer on charge carrier mobility and highlight the potential of the polymer/air interface in achieving excellent “out‐of‐plane” orientation and high FET mobilities.     

用微控制器或DSP电路控制开机／关机功能

在许多设备中,一个开/关按键可开启或关断电源.一般情况下,不管微控制器或DSP电路正在处理的是处理功能还是负载,在按下按键时,系统都会关断.图1所示的小型电路可用来使微控制器或DSP电路控制这一开/关功能.这样,系统就可先完成各种必需完成的作业,如数据处理、数据存储等,然后再发出指令关断电源.图2示出了它的定时图.虽然最终的设备是与电源断开的,但开关直接与直流电源或电池连接.因此,所有的电容器都会放电.最困难的工作就是使图1中的两个D触发器都进入所需的"关"状态.     

Model‐based reconstruction for T1 mapping using single‐shot inversion‐recovery radial FLASH

Quantitative parameter mapping in MRI is typically performed as a two‐step procedure where serial imaging is followed by pixelwise model fitting. In contrast, model‐based reconstructions directly reconstruct parameter maps from raw data without explicit image reconstruction. Here, we propose a method that determines T1 maps directly from multi‐channel raw data as obtained by a single‐shot inversion‐recovery radial FLASH acquisition with a Golden Angle view order. Joint reconstruction of a T1, spin‐density and flip‐angle map is formulated as a nonlinear inverse problem and solved by the iteratively regularized Gauss‐Newton method. Coil sensitivity profiles are determined from the same data in a preparatory step of the reconstruction. Validations included numerical simulations, in vitro MRI studies of an experimental T1 phantom, and in vivo studies of brain and abdomen of healthy subjects at a field strength of 3 T. The results obtained for a numerical and experimental phantom demonstrated excellent accuracy and precision of model‐based T1 mapping. In vivo studies allowed for high‐resolution T1 mapping of human brain (0.5–0.75 mm in‐plane, 4 mm section thickness) and liver (1.0 mm, 5 mm section) within 3.6–5 s. In conclusion, the proposed method for model‐based T1 mapping may become an alternative to two‐step techniques, which rely on model fitting after serial image reconstruction. More extensive clinical trials now require accelerated computation and online implementation of the algorithm. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 254–263, 2016     

Bewertung alternativer Arbeitsmittel für Wärmepumpen im Gebäudesektor

Forschung im Ingenieurwesen - Das Arbeitsmittel in Wärmepumpen unterliegt einer Vielzahl von Anforderungen, welche für einen effizienten und sicheren Betrieb eingehalten werden...     

The complex aerodynamic footprint of desert locusts revealed by large-volume tomographic particle image velocimetry

Particle image velocimetry has been the preferred experimental technique with which to study the aerodynamics of animal flight for over a decade. In that time, hardware has become more accessible and the software has progressed from the acquisition of planes through the flow field to the reconstruction of small volumetric measurements. Until now, it has not been possible to capture large volumes that incorporate the full wavelength of the aerodynamic track left behind during a complete wingbeat cycle. Here, we use a unique apparatus to acquire the first instantaneous wake volume of a flying animal''s entire wingbeat. We confirm the presence of wake deformation behind desert locusts and quantify the effect of that deformation on estimates of aerodynamic force and the efficiency of lift generation. We present previously undescribed vortex wake phenomena, including entrainment around the wing-tip vortices of a set of secondary vortices borne of Kelvin–Helmholtz instability in the shear layer behind the flapping wings.