Solution-Processed, Surface-Engineered, Polycrystalline CdSe-SnSe Exhibiting Low Thermal Conductivity.

In recent years, solution processes have gained considerable traction as a cost-effective and scalable method to produce high-performance thermoelectric materials. The process entails a series of critical steps: synthesis, purification, thermal treatments, and consolidation, each playing a pivotal role in determining performance, stability, and reproducibility. We have noticed a need for more comprehensive details for each of the described steps in most published works. Recognizing the significance of detailed synthetic protocols, we describe here the approach used to synthesize and characterize one of the highest-performing polycrystalline p-type SnSe. In particular, we report the synthesis of SnSe particles in water and the subsequent surface treatment with CdSe molecular complexes that yields CdSe-SnSe nanocomposites upon consolidation. Moreover, the surface treatment inhibits grain growth through Zenner pinning of secondary phase CdSe nanoparticles and enhances defect formation at different length scales. The enhanced complexity in the CdSe-SnSe nanocomposite microstructure with respect to SnSe promotes phonon scattering and thereby significantly reduces the thermal conductivity. Such surface engineering provides opportunities in solution processing for introducing and controlling defects, making it possible to optimize the transport properties and attain a high thermoelectric figure of merit.

Unveiling Crucial Chemical Processing Parameters Influencing the Performance of Solution-Processed Inorganic Thermoelectric Materials.

Production of thermoelectric materials from solution-processed particles involves the synthesis of particles, their purification and densification into pelletized material. Chemical changes that occur during each one of these steps render them performance determining. Particularly the purification steps, bypassed in conventional solid-state synthesis, are the cause for large discrepancies among similar solution-processed materials. In present work, the investigation focuses on a water-based surfactant free solution synthesis of SnSe, a highly relevant thermoelectric material. We show and rationalize that the number of leaching steps, purification solvent, annealing, and annealing atmosphere have significant influence on the Sn : Se ratio and impurity content in the powder. Such compositional changes that are undetectable by conventional characterization techniques lead to distinct consolidated materials with different types and concentration of defects. Additionally, the profound effect on their transport properties is demonstrated. We emphasize that understanding the chemistry and identifying key chemical species and their role throughout the process is paramount for optimizing material performance. Furthermore, we aim to demonstrate the necessity of comprehensive reporting of these steps as a standard practice to ensure material reproducibility.

["Take a break - Time-out for me": A practice project to promote a healthy rest break]. / "Mach mal Pause ­ Time out für mich": Praxisprojekt zur Förderung einer gesunden Pause.

"Take a break - Time-out for me": A practice project to promote a healthy rest break Abstract. Background: Breaks are essential for physical and mental health. In health care professions breaks are often cancelled or interrupted. Nursing staff should be enabled to take breaks regularly and without any interruptions. They should be given alternative options to organize their breaks. Methods: A pre-post survey was carried out with one group by means of questionnaires. The two break models "Feel good manager" and "I'm away" were tested by the nursing staff, followed by a debriefing meeting. Results: Before this project none of the nurses had rated his/her satisfaction regarding the breaks as "very good" or "good". This changed during the project to 45,5% (t1) and 22,2% (t2). None of the nurses felt "very well" or "well" recovered before the project. An increase to 54,6% (t1) respectively 33,3% could be asserted. Only 7,1% (t0) indicated to take their breaks "always" or "usually" in "full-length". With the break model "Feel good manager" it changed to 100% and with the model "I am away" to 33,3%. The amount of interruptions could be reduced from 4 (t0) to 2 (t1) and 0 (t2). Discussion: These break models are not applicable arbitrarily by other wards at will. Instead, individual situation analysis should be carried out with according adjustments. These models cannot be tested in case of lack of break areas or absence of personnel. Conclusion: The described project procedure can be transferred to other wards.

Solution-Processed Inorganic Thermoelectric Materials: Opportunities and Challenges.

Thermoelectric technology requires synthesizing complex materials where not only the crystal structure but also other structural features such as defects, grain size and orientation, and interfaces must be controlled. To date, conventional solid-state techniques are unable to provide this level of control. Herein, we present a synthetic approach in which dense inorganic thermoelectric materials are produced by the consolidation of well-defined nanoparticle powders. The idea is that controlling the characteristics of the powder allows the chemical transformations that take place during consolidation to be guided, ultimately yielding inorganic solids with targeted features. Different from conventional methods, syntheses in solution can produce particles with unprecedented control over their size, shape, crystal structure, composition, and surface chemistry. However, to date, most works have focused only on the low-cost benefits of this strategy. In this perspective, we first cover the opportunities that solution processing of the powder offers, emphasizing the potential structural features that can be controlled by precisely engineering the inorganic core of the particle, the surface, and the organization of the particles before consolidation. We then discuss the challenges of this synthetic approach and more practical matters related to solution processing. Finally, we suggest some good practices for adequate knowledge transfer and improving reproducibility among different laboratories.

Reversible Speed Regulation of Self-Propelled Janus Micromotors via Thermoresponsive Bottle-Brush Polymers.

Invited for the cover of this issue is the group of Ian Teasdale and Yolanda Salinas at the Johannes Kepler University Linz. The image depicts the self-propelled Janus micromotors reported in this work. Read the full text of the article at 10.1002/chem.202004792.

Reversible Speed Regulation of Self-Propelled Janus Micromotors via Thermoresponsive Bottle-Brush Polymers.

This work reports a reversible braking system for micromotors that can be controlled by small temperature changes (≈5 °C). To achieve this, gated-mesoporous organosilica microparticles are internally loaded with metal catalysts (to form the motor) and the exterior (partially) grafted with thermosensitive bottle-brush polyphosphazenes to form Janus particles. When placed in an aqueous solution of H2 O2 (the fuel), rapid forward propulsion of the motors ensues due to decomposition of the fuel. Conformational changes of the polymers at defined temperatures regulate the bubble formation rate and thus act as brakes with considerable deceleration/acceleration observed. As the components can be easily varied, this represents a versatile, modular platform for the exogenous velocity control of micromotors.

Serum response factor controls neuronal circuit assembly in the hippocampus.

Higher organisms rely on multiple modes of memory storage using the hippocampal network, which is built by precisely orchestrated mechanisms of axonal outgrowth, guidance and synaptic targeting. We demonstrate essential roles of the transcription factor serum response factor (SRF), a sensor of cytoskeletal actin dynamics, in all these processes. Conditional deletion of the mouse Srf gene reduced neurite outgrowth and abolished mossy fiber segregation, resulting in ectopic fiber growth inside the pyramidal layer. SRF-deficient mossy fibers aberrantly targeted CA3 somata for synapse formation. Axon guidance assays showed that SRF was a key mediator of ephrin-A and semaphorin guidance cues; in SRF-deficient neurons, these resulted in the formation of F-actin-microtubule rings rather than complete growth cone collapse. Dominant-negative variants of the SRF cofactor megakaryocytic acute leukemia (MAL) severely impeded neurite outgrowth and guidance. These data highlight essential links between SRF-mediated transcription and axon guidance and circuit formation in the hippocampus.

[Acute postoperative confusion in heart surgery patients]. / Akute postoperative Verwirrtheit kardiochirurgischer Patienten.

Unlike other countries, Germany does not have data about the incidence of acute confusion following heart surgery. However, the occurrence of acute confusion does extend the hospitalization length by up to 13 days. Thus, this phenomenon is of high relevance for the health profession. This incidence study was performed with the goal to obtain exact information on the incidence rate of acute postoperative confusion after heart surgery (bypass and valve operations) through a multi-center evaluation. The data evaluation took place in the form of a convenient sample survey in three different German clinics specialized in heart surgery. The observation period lasted from the day of surgery up to the fifth postoperative day. In the context of this prospective cohort study, suitable study participants were all patients aged 18 or older who underwent heart surgery between February 1st and April 30th, 2000. At the end, 860 patients were included in the study. A total of 152 patients showed symptoms of acute confusion, meaning a total incidence of 17.4% (confidence interval 14-20%). The occurrence of this phenomenon was not symmetrical. A wide-spread occurrence could be observed particularly at night. Patients aged 81-91 were mainly affected, with an incidence of confusion of 43.5% in this group. The results confirm the clinical importance of this issue and require interdisciplinary approaches for solution.