Active responsive colloids driven by intrinsic dichotomous noise

We study the influence of intrinsic noise on the structure and dynamics of responsive colloids (RCs) which actively change their size and mutual interactions. The colloidal size is explicitly resolved in our RC model as an internal degree of freedom (DOF) in addition to the particle translation. A Hertzian pair potential between the RCs leads to repulsion and shrinking of the particles, resulting in an explicit responsiveness of the system to self-crowding. To render the colloids active, their size is internally driven by a dichotomous noise, randomly switching ('breathing') between growing and shrinking states with a predefined rate, as motivated by recent experiments on synthetic active colloids. The polydispersity of this dichotomous active responsive colloid (D-ARC) model can be tuned by the parameters of the noise. Utilizing stochastic computer simulations, we study crowding effects on the spatial distributions, relaxation times, and self-diffusion of dense suspensions of the D-ARCs. We find a substantial influence of the 'built-in' intrinsic noise on the system's behavior, in particular, transitions from unimodal to bimodal size distributions for an increasing colloid density as well as intrinsic noise-modified diffusive translational dynamics. We conclude that controlling the noise of internal DOFs of a macromolecule or cell is a powerful tool for active colloidal materials to enable autonomous changes in the system's collective structure and dynamics towards the adaption of macroscopic properties to external perturbations.Comment: 13 pages with 6 figure

Machining of shaft for hybrid car drive

Tato bakalářská práce se zabývá výrobou hřídele pro pohon hybridního automobilu. Celý proces je znázorněn pomocí výrobního postupu, který má za úkol provést pracovníka od prvního úkonu až po poslední. Práce je též zaměřena na problematiku hybridních vozidel, a to především na podstatu hybridního motoru a jejich typů.This bachelor thesis deals with the production of a shaft for driving a hybrid motor. The whole proces is illustrated by a production process, which has the task of executing the worker from the first task to the last. The work is also focused on the issue of hybrid vehicles, especially the nature of the hybrid engine and their types.

Liquid structure of bistable responsive macromolecules using mean-field density-functional theory

Macromolecular crowding typically applies to biomolecular and polymer-based systems in which the individual particles often feature a two-state folded/unfolded or coil-to-globule transition, such as found for proteins and peptides, DNA and RNA, or supramolecular polymers. Here, we employ a mean-field density functional theory (DFT) of a model of soft and bistable responsive colloids (RCs) in which the size of the macromolecule is explicitly resolved as a degree of freedom living in a bimodal ‘Landau’ energy landscape (exhibiting big and small states), thus directly responding to the crowding environment. Using this RC-DFT we study the effects of self-crowding on the liquid bulk structure and thermodynamics for different energy barriers and softnesses of the bimodal energy landscape, in conditions close to the coil-to-globule transition. We find substantial crowding effects on the internal distributions, a complex polydispersity behavior, and quasi-universal compression curves for increasing (generalized) packing fractions. Moreover, we uncover distinct signatures of bimodal versus unimodal behavior in the particle compression. Finally, the analysis of the pair structure – derived from the test particle route – reveals that the microstructure of the liquid is quite inhomogeneous due to local depletion effects, tuneable by particle softness.Junta de AndaluciaEuropean Regional Development Fund - Consejeria de Conocimiento, Investigacion y Universidad, Junta de Andalucia PY20-00241 A-FQM-90-UGR20Plan Propio of the University of Granada PPVS2018-0

Synergistic chemomechanical dynamics of feedback-controlled microreactors

The experimental control of synergistic chemomechanical dynamics of catalytically active microgels (microreactors) is a key prerequisite for the design of adaptive and biomimetic materials. Here, we report a minimalistic model of feedback-controlled microreactors based on the coupling between the hysteretic polymer volume phase transition and a volume-controlled permeability for the internal chemical conversion. We categorize regimes of mono- and bistability, excitability, damped oscillations, as well as sustained oscillatory states with tunable amplitude, as indicated by experiments and representable by the FitzHugh-Nagumo dynamics for neurons. We summarize the features of such a colloidal neuron in bifurcation diagrams with respect to microgel design parameters, such as permeability and relaxation times, as a guide for experimental synthesis.Comment: 6 pages, 3 figure

Gas-phase microsolvation of ubiquitin: investigation of crown ether complexation sites using ion mobility-mass spectrometry.

In this study the gas-phase structure of ubiquitin and its lysine-to-arginine mutants was investigated using ion mobility-mass spectrometry (IM-MS) and electron transfer dissociation-mass spectrometry (ETD-MS). Crown ether molecules were attached to positive charge sites of the proteins and the resulting non-covalent complexes were analysed. Collision induced dissociation (CID) experiments revealed relative energy differences between the wild type and the mutant crown-ether complexes. ETD-MS experiments were performed to identify the crown ether binding sites. Although not all of the binding sites could be revealed, the data confirm that the first crown ether is able to bind to the N-terminus. IM-MS experiments show a more compact structure for specific charge states of wild type ubiquitin when crown ethers are attached. However, data on ubiquitin mutants reveal that only specific lysine residues contribute to the effect of charge microsolvation. A compaction is only observed for one of the investigated mutants, in which the lysine has no proximate interaction partner. On the other hand when the lysine residues are involved in salt bridges, attachment of crown ethers has little effect on the structure

First Evidence of Reproductive Adaptation to “Island Effect” of a Dwarf Cretaceous Romanian Titanosaur, with Embryonic Integument In Ovo

<div><h3>Background</h3><p>The Cretaceous vertebrate assemblages of Romania are famous for geographically endemic dwarfed dinosaur taxa. We report the first complete egg clutches of a dwarf lithostrotian titanosaur, from Toteşti, Romania, and its reproductive adaptation to the “island effect”.</p> <h3>Methodology/Findings</h3><p>The egg clutches were discovered in sequential sedimentary layers of the Maastrichtian Sânpetru Formation, Toteşti. The occurrence of 11 homogenous clutches in successive strata suggests philopatry by the same dinosaur species, which laid clutches averaging four ∼12 cm diameters eggs. The eggs and eggshells display numerous characters shared with the positively identified material from egg-bearing level 4 of the Auca Mahuevo (Patagonia, Argentina) nemegtosaurid lithostrotian nesting site. Microscopic embryonic integument with bacterial evidences was recovered in one egg. The millimeter-size embryonic integument displays micron size dermal papillae implying an early embryological stage at the time of death, likely corresponding to early organogenesis before the skeleton formation.</p> <h3>Conclusions/Significance</h3><p>The shared oological characters between the Haţeg specimens and their mainland relatives suggest a highly conservative reproductive template, while the nest decrease in egg numbers per clutch may reflect an adaptive trait to a smaller body size due to the “island effect”. The combined presence of the lithostrotian egg and its embryo in the Early Cretaceous Gobi coupled with the oological similarities between the Haţeg and Auca Mahuevo oological material evidence that several titanosaur species migrated from Gondwana through the Haţeg Island before or during the Aptian/Albian. It also suggests that this island might have had episodic land bridges with the rest of the European archipelago and Asia deep into the Cretaceous.</p> </div

Ein mobiles Spiel wird zum Eventmarketinginstrument

Der mExplorer ist ein an der Universität Zürich entwickeltes mobiles Lernspiel, welches Erstsemestrigen den Campus einer Universität auf spielerische Art und Weise näher bringen soll. In diesem Beitrag wird gezeigt, wie das Spiel für das Eventmarketing eingesetzt werden kann und welche Wirkungen es dabei hat. Bei einem Feldtest wird gezeigt, dass ähnliche Probleme wie beim mobilen Lernen auftreten, aber auch ähnliche emotionale Wirkungen erzielt werden. Aus den unübersehbaren Ähnlichkeiten zwischen mobilem Lernen und Eventmarketing schliessen wir auf eine Konvergenz unterschiedlicher Lebensbereiche durch mobile Anwendungen

Navigation Support for Mobile Learning

Mobile learning exposes learning to the natural environment. If this environment is large, the learners have to navigate to find the learning objects or to explore the environment. Current mobile learning systems provide only minimal navigational support. Prior studies report that conventional pedestrian information systems are not suited to mobile learning, as the learners focus too much on the navigation system. In this paper we analyze issues in navigational support and provide evidence for the lack of support in current systems. Then we propose and evaluate how mobile learning systems can not only provide better navigation support, but also prevent the focus problem. The tested concepts include using an aura to visualize the accuracy, using history visualization for orientation and browsing support, and using information pull to focus more on the environment. Recommendations for further research conclude the paper

Designing tasks for engaging mobile learning

Many mobile learning projects aim to support new learning forms like situated learning in a real world environment. Situated and explorative learning should be active learning, engaging students in the environment. We tested four different tasks designs in two large field tests with the mExplorer system. Two kinds of engaging tasks were observed. Interactive tasks with high context integration led to knowledge about specific aspects of an environment. Creative tasks led to a familiarization with the environment. We also analyzed other projects with situated real world learning scenarios to see what types of tasks they were using. We found that instead of sup-porting active learning, many of these projects still focus on transmissive elements and do not use the full potential of situated and explorative learning. To optimize this, we propose four design recommendations for tasks and de-scribe the circumstances under which specific types of m-learning tasks should be used