Wavelet Based Identification of Substances in Terahertz Tomography Measurements

In comparison to the X-ray computed tomography Terahertz technique significantly enhances the amount of the information acquired during the sample measurement. Not only amplitude, but also phase, time and spectral characteristics can be determined in THz time-domain spectroscopy. Thus, Terahertz tomography allows localization and identification of substances within the objects due to the characteristic fingerprints in this frequency range. Certainly, an appropriate data processing and comparison algorithms are crucial for the accurate identification of the substances in the measured sample. Therefore, we present a new wavelet-based identification method which is suitable even for the substances with broad absorption curves and small or no absorption peaks. The performance of this algorithm was evaluated with the help of a tomographic sample filled with four substances, which were previously characterized for the external database. The continuous wavelet transform was applied to every data cell of the tomographic measurement and compared to the database. Received sinograms were reconstructed into images which depict estimated similarity between the measured and database substances. Furthermore, we suggest a method for the reduction of spectral data after the continuous wavelet transform. This method is based on the extraction of the distinctive features in the form of ridge lines.     

The Distinct Role of the HDL Receptor SR-BI in Cholesterol Homeostasis of Human Placental Arterial and Venous Endothelial Cells

As opposed to adults, high-density lipoprotein (HDL) is the main cholesterol carrying lipoprotein in fetal circulation. The major HDL receptor, scavenger receptor class B type I (SR-BI), contributes to local cholesterol homeostasis. Arterial endothelial cells (ECA) from human placenta are enriched with cholesterol compared to venous endothelial cells (ECV). Moreover, umbilical venous and arterial plasma cholesterol levels differ markedly. We tested the hypothesis that the uptake of HDL-cholesteryl esters differs between ECA and ECV because of the differential expression of SR-BI. We aimed to identify the key regulators underlying these differences and the functional consequences. Immunohistochemistry was used for visualization of SR-BI in situ. ECA and ECV were isolated from the chorionic plate of human placenta and used for RT-qPCR, Western Blot, and HDL uptake assays with ³H- and ¹²⁵I-labeled HDL. DNA was extracted for the methylation profiling of the SR-BI promoter. SR-BI regulation was studied by exposing ECA and ECV to differential oxygen concentrations or shear stress. Our results show elevated SR-BI expression and protein abundance in ECA compared to ECV in situ and in vitro. Immunohistochemistry demonstrated that SR-BI is mainly expressed on the apical side of placental endothelial cells in situ, allowing interaction with mature HDL circulating in the fetal blood. This was functionally linked to a higher increase of selective cholesterol ester uptake from fetal HDL in ECA than in ECV, and resulted in increased cholesterol availability in ECA. SR-BI expression on ECV tended to decrease with shear stress, which, together with heterogeneous immunostaining, suggests that SR-BI expression is locally regulated in the placental vasculature. In addition, hypomethylation of several CpG sites within the SR-BI promoter region might contribute to differential expression of SR-BI between chorionic arteries and veins. Therefore, SR-BI contributes to a local cholesterol homeostasis in ECA and ECV of the human feto-placental vasculature.     

Printing with Satellite Droplets

Despite their specific methodologies, all current noncontact printing techniques such as inkjet printing (IJP), involve the break‐up of a liquid meniscus during the separation of the ink droplet from the bulk ink reservoir. Often, the break‐up of a liquid meniscus results in the formation of one or more satellite droplet whose volumes are several orders of magnitude smaller than the primary droplet. Many attempts are directed to suppress or control the formation of satellite droplets because they blur the printing result. For the first time, a simple mechanism by which a single satellite droplet is exclusively formed and directed to the substrate by a gas stream while the primary droplet remains attached to a metal rod used for controlling the formation and break‐up of the meniscus is reported. High printing resolution is demonstrated by satellite droplets printing (SDP) without the need for small orifices which are prone to clogging. Furthermore, the droplet generation from a large orifice enables SDP to handle viscous inks which has remained challenging for traditional IJP.     

Towards All-Solid-State Polymer Batteries: Going Beyond PEO with Hybrid Concepts

To go beyond polyethylene oxide in lithium metal batteries, a hybrid polymer/oligomer cell design is presented, where an ester oligomer provides high ionic conductivity of 0.2 mS cm⁻¹ at 40 °C within thicker composite cathodes with active mass loadings of up to 11 mg cm⁻² (LiNbO₃-coated) LiNi_0.6Mn_0.2Co_0.2 (NMC622), while a 30 µm thin scaffold-supported polymer electrolyte affords mechanical stability. Corresponding discharge capacities of the hybrid cells exceed 170 mAh g⁻¹ (11 mg cm⁻²) or 160 mAh g⁻¹ (6 mg cm⁻²) at rates of either 0.1 or 0.25 C. Multilayer pouch cells are projected to enable energy densities of 235 Wh L⁻¹ (6 mg cm⁻²) and even up to 356 Wh L⁻¹ (11 mg cm⁻²), clearly superior to other reported polymer-based cell designs. Polyester electrolytes are environmentally benign and safer compared to common liquid electrolytes, while the straightforward synthesis and affordability of precursors render hybrid polyester electrolytes suitable candidates for future application in solid-state lithium metal batteries.     

Evolution of Creep Damage of 316L Produced by Laser Powder Bed Fusion

The damage mechanisms of metallic components produced by process laser powder bed fusion differ significantly from those typically observed in conventionally manufactured variants of the same alloy. This is due to the unique microstructures of additively manufactured materials. Herein, the focus is on the study of the evolution of creep damage in stainless steel 316L specimens produced by laser powder bed fusion. X-ray computed tomography is used to unravel the influence of the process-specific microstructure from the influence of the initial void distribution on creep damage mechanisms. The void distribution of two specimens tested at 600 °C and 650 °C is analyzed before a creep test, after an interruption, and after fracture. The results indicate that the formation of damage is not connected to the initial void distribution. Instead, damage accumulation at grain boundaries resulting from intergranular cracking is observed.     

Stilbene and Azobenzene Diazonium Compounds as dye reagents for crown ethers

The change of light absorption of six coloured diazonium compounds ( 1 , 2a , 2b , 3 , 4 , 5 ) on complexation with five 18-crown-6 derivatives ( 6 – 10 ) in 1,2-dichloroethane was investigated. In the benzene, stilbene and azobenzene series complexation produces only hypsochromic shifts of the intramolecular ct-band of the diazonium ions up to 140 nm. The extend of the shift is effected by ion pairing. The ct-transition energy of the complexes diazonium ion is independent on the present anion in contrast to the uncomplexed compounds. The colour changes are not caused by host to guest charge transfer or E/Z-isomerisation of the stilbene and azobenzene derivatives. A quantitative explanation of the colour changes is given basing on an electrostatic interaction model.