Effects of an Oscillating Flap on the Main Airfoil Unsteady Lift in Grid Turbulence

A wing of NACA 0015 profile and Aspect Ratio 2.4 fitted with a Trailing Edge Flap was tested in a wind tunnel for both smooth and turbulent flow conditions at a Re number 108000. The unsteady lift on the wing was measured with and without the flap. Two types of flap excitation were tried: One was of the “open loop” type in which the flap was subjected to sinusoidal pitching oscillations while the wing was set to a constant angle of attack. In the second, “closed loop” mode, the excitation signal fed into the flap originated from the unsteady lift of the wing itself. The phase lag between those signals was changed and it was found that it played a significant role in the suppression of the main wing unsteady lift. © 2021, Springer Nature Switzerland AG

Power quality analysis of a pilot microgrid supplied by a CHP system in Greece

The cooperation of Dispersed Generation (DG) units with storage devices to meet controllable loads constitutes a Microgrid. Microgrids are Low Voltages (LV) or in some cases Medium Voltages (MV) networks. The unique feature of Microgrids is that although they operate mostly interconnected to the upper level voltage distribution network, they can be automatically transferred to islanded mode, in case of faults in the upstream network. Microgrid structure is able to unlock the full potential of Distributed Energy Resources (DER) and allows the full exploitation of their advantages. The purpose of this paper is to study the power quality of the Combined Heat and Power (CHP) system installed in the frame of EU-DEEP project inside the premises of the National Technical University of Athens (NTUA). The Microgrid system also contains batteries with inverters and critical loads. The power quality is studied by taking into consideration voltage magnitude variations, frequency variations, voltage unbalance, voltage fluctuations, as well as light flicker and harmonic distortion. Furthermore, the transitions between the islanded operation mode and the connected one are studied. The measurements are compared with the limits given by power quality Standards, especially ΕΝ 50160. The power quality analysis came to the conclusion that the current harmonic distortion is the main disturbance, because a high current Total Harmonic Distortion (THD) factor was observed. In addition, it was observed that the flicker exceeds the Standards' limits in the islanded mode. At last, it should be noted that distributed power units like the one examined can improve continuity and support the main power supply in the event of a supply outage.Peer reviewe

An aspartyl protease directs malaria effector proteins to the host cell

Plasmodium falciparum causes the virulent form of malaria and disease manifestations are linked to growth inside infected erythrocytes. To survive and evade host responses the parasite remodels the erythrocyte by exporting several hundred effector proteins beyond the surrounding parasitophorous vacuole membrane. A feature of exported proteins is a pentameric motif (RxLxE/Q/D) that is a substrate for an unknown protease. Here we show that the protein responsible for cleavage of this motif is plasmepsin V (PMV), an aspartic acid protease located in the endoplasmic reticulum. PMV cleavage reveals the export signal (xE/Q/D) at the amino terminus of cargo proteins. Expression of an identical mature protein with xQ at the N terminus generated by signal peptidase was not exported, demonstrating that PMV activity is essential and linked with other key export events. Identification of the protease responsible for export into erythrocytes provides a novel target for therapeutic intervention against this devastating disease.<br /

A HUPO test sample study reveals common problems in mass spectrometry-based proteomics

We performed a test sample study to try to identify errors leading to irreproducibility, including incompleteness of peptide sampling, in liquid chromatography-mass spectrometry-based proteomics. We distributed an equimolar test sample, comprising 20 highly purified recombinant human proteins, to 27 laboratories. Each protein contained one or more unique tryptic peptides of 1,250 Da to test for ion selection and sampling in the mass spectrometer. Of the 27 labs, members of only 7 labs initially reported all 20 proteins correctly, and members of only 1 lab reported all tryptic peptides of 1,250 Da. Centralized analysis of the raw data, however, revealed that all 20 proteins and most of the 1,250 Da peptides had been detected in all 27 labs. Our centralized analysis determined missed identifications (false negatives), environmental contamination, database matching and curation of protein identifications as sources of problems. Improved search engines and databases are needed for mass spectrometry-based proteomics.8 page(s