Detection mechanism for ferroelectric domain boundaries with lateral force microscopy

The contrast mechanism for the visualization of ferroelectric domain boundaries with lateral force microscopy is generally assumed to be caused by mechanical deformation of the sample due to the converse piezoelectric effect. We show, however, that electrostatic interactions between the charged tip and the electric fields arising from the surface polarization charges dominate the contrast mechanism. This explanation is sustained by quantitative analysis of the measured forces as well as by comparative measurements on different materials

Electrostatic topology of ferroelectric domains in YMnO3_3

Trimerization-polarization domains in ferroelectric hexagonal YMnO$_3$ were resolved in all three spatial dimensions by piezoresponse force microscopy. Their topology is dominated by electrostatic effects with a range of 100 unit cells and reflects the unusual electrostatic origin of the spontaneous polarization. The response of the domains to locally applied electric fields explains difficulties in transferring YMnO$_3$ into a single-domain state. Our results demonstrate that the wealth of non-displacive mechanisms driving ferroelectricity that emerged from the research on multiferroics are a rich source of alternative types of domains and domain-switching phenomena

Lateral Signals in Piezoresponse Force Microscopy at Domain Boundaries of Ferroelectric Crystals

In piezoresponse force microscopy a lateral signal at the domain boundaries is occasionally observed. In recent years, a couple of experiments have been reported and varying explanations for the origin of this lateral signal have been proposed. Additionally, elaborated theoretical modeling for this particular issue has been carried out. Here we present experimental data obtained on different crystallographic cuts of $\rm LiNbO_3$, $\rm BaTiO_3$, and $\rm KTiOPO_4$ single crystals. We could thereby rule out some of the explanations proposed so far, introduce another possible mechanism, and quantitatively compare our results to the existing modeling

ДИСКРЕТНО-ПЛАСТИЧНА МОДЕЛЬ СЕРЕДОВИЩА ПРОЦЕСУ РОЛИКОВОГО ФОРМУВАННЯ ЗАТРУБНОГО ПРОСТОРУ ТУНЕЛЮ

У статті розглянута дискретно-пластична модель середовища процесу роликового формування затру- бного простору тунелю. В статье рассмотренная дискретно-пластичная модель среды процесса роликового формирования за- трубного пространства тоннел

Construction and Characterization of T7 Bacteriophages Harboring Apidaecin-Derived Sequences

The global spread of multi- and pan-resistant bacteria has triggered research to identify novel strategies to fight these pathogens, such as antimicrobial peptides and, more recently, bacteriophages. In a proof-of-concept study, we have genetically modified lytic T7Select phages targeting Escherichia coli Rosetta by integrating DNA sequences derived from the proline-rich antimicrobial peptide, apidaecin. This allowed testing of our hypothesis that apidaecins and bacteriophages can synergistically act on phage-sensitive and phage-resistant E. coli cells and overcome the excessive cost of peptide drugs by using infected cells to express apidaecins before cell lysis. Indeed, the addition of the highly active synthetic apidaecin analogs, Api802 and Api806, to T7Select phage-infected E. coli Rosetta cultures prevented or delayed the growth of potentially phage-resistant E. coli Rosetta strains. However, high concentrations of Api802 also reduced the T7Select phage fitness. Additionally, plasmids encoding Api802, Api806, and Api810 sequences transformed into E. coli Rosetta allowed the production of satisfactory peptide quantities. When these sequences were integrated into the T7Select phage genome carrying an N-terminal green fluorescent protein (GFP-) tag to monitor the expression in infected E. coli Rosetta cells, the GFP–apidaecin analogs were produced in reasonable quantities. However, when Api802, Api806 and Api810 sequences were integrated into the T7Select phage genome, expression was below detection limits and an effect on the growth of potentially phage-resistant E. coli Rosetta strains was not observed for Api802 and Api806. In conclusion, we were able to show that apidaecins can be integrated into the T7Select phage genome to induce their expression in host cells, but further research is required to optimize the engineered T7Select phages for higher expression levels of apidaecins to achieve the expected synergistic effects that were visible when the T7Select phages and synthetic Api802 and Api806 were added to E. coli Rosetta cultures

Using Real Options in ERP-Systems for Improving Delivery Reliability

Today’s machinery and equipment industry is a highly volatile market, giving rise to frequently instable and inapprehensiblebuyer-supplier-relationships and to turbulences with respect to reliability of deliveries. With this paper we propose a minimalinvasive approach how to overcome existing capability limitations in production planning, scheduling and procurement ofERP-systems by using real options as means for coordinating the divergent interest of buyers and suppliers. Following thedesign research paradigm, we first describe how real options can be integrated in a contemporary ERP-system. In asupplemental evaluation, the attitude toward using this approach is discussed. This final discussion provides insights whethercompanies in the machinery and equipment industry are willing to adopt our real options approach, or if they prefer the use ofother, not necessarily IT-enabled, means for handling the poor delivery reliability

Impact of elasticity on the piezoresponse of adjacent ferroelectric domains investigated by scanning force microscopy

As a consequence of elasticity, mechanical deformations of crystals occur on a length scale comparable to their thickness. This is exemplified by applying a homogeneous electric field to a multi-domain ferroelectric crystal: as one domain is expanding the adjacent ones are contracting, leading to clamping at the domain boundaries. The piezomechanically driven surface corrugation of micron-sized domain patterns in thick crystals using large-area top electrodes is thus drastically suppressed, barely accessible by means of piezoresponse force microscopy

RIGHTING OF CHINESE MITTEN CRABS (ERIOCHEIR SINENSIS) AND THEIR MODELS

The usage of unmanned underwater vehicles for marine tasks is continuously growing and bioinspired stabilizing systems shall help them to gain and keep a stable position during work. Therefore the righting maneuver of E. sinensis has been studied. These crabs are able to perform a 180°-rotation with an angular velocity of 4.30 s−1 when falling underwater from a supine starting position. High-speed particle image velocimetry has shown, that propulsive forces with a peak of 0.021 ± 0.001 N were produced by the hind legs to initiate and stop the rotation. In a numerical multibody simulation a constant force of 0.009 N acting for 0.2 s leads to the same rotation. In order to prove this mechanism, it was implemented into a robotic system. Its mean density of 1.15 g/cm3 deviates not more than 4% from the biological and numerical models. It can complete a 180°-turn within 1.03 ± 0.12 s with a rotational velocity of up to 4.25 s−1

Assessing the Impact of Empirical Process Control Metrics in Agile Software Development - A Framework based on Improvement Capability

Empirical process control is an integral part of agile software development. A multitude of development metrics has been proposed to implement it. However, the efficacy of control metrics has remained unclear and empirical evidence of their impact is scarce. Methods for assessing whether and how a proposed metric stimulates the improvement of a development process are not yet available. We conduct a design science approach to develop an artifact that assesses the impact of development metrics and we identify their contribution for process improvement at a global software vendor. We draw on the theoretical construct of improvement capability to outline design principles of a measurement framework. Our evaluation of five large-scale agile development projects demonstrates that our framework facilitates to implement development metrics more effectively. The framework has the potential to improve large-scale agile software development and it serves as a useful basis for future empirical research on development metrics

Preparing for the SARS-CoV-2 pandemic: creation and implementation of new recommendations

During the SARS-CoV-2 pandemic in 2020, departments of anesthesiology worldwide have encountered new and unique challenges. In this short communication, we present and assess our recommendations for orotracheal intubation, a frequent high-risk procedure. We will point out that interdisciplinary cooperation with “non-patient care” departments like the Institute for Medical Microbiology and Hygiene tremendously helped us in creating this and other new, clear standards for anesthesiological procedures. Moreover, to reliably implement our newly created measures, we distributed incisive posters and organized comprehensive training sessions. Eventually, we summarize and analyze the occurring problems of our suggestions for intubation during their realization