Superior Mechanical and Magnetic Performance of Highly Anisotropic Sendust-Flake Composites Freeze Cast in a Uniform Magnetic Field

Despite extensive research, the manufacture in the bulk of high-performance flake-based magnetic composites with a highly aligned, nacre-like structure remains challenging. Many challenges can be overcome by freeze casting in an externally applied, uniform magnetic field, which causes both the flakes and the composite walls of the cellular solid to align parallel to the B-field lines. When appropriately sized, the flakes experience a second alignment parallel to the freezing direction because of a shear flow that occurs due to both the volumetric expansion of the ice phase and mold contraction during the directional solidification. The resulting orthotropic structure of the freeze-cast magnetic composite is reflected in orthotropic mechanical and magnetic properties of the material. The magnetic composites manufactured by magnetic-field assisted freeze casting outperform by a factor of 2–4 in terms of stiffness, strength, and toughness materials that are processed in the absence of a magnetic field and do not exhibit a monodomain architecture. Because of the highly aligned microstructure, it is possible to compact the initially lamellar composite with 90% porosity to at least 80% strain. The results presented in this study illustrate the tremendous potential for magnetic freeze casting of magnetic composites for use in power conversion.     

Roadmap to Gigahertz Organic Transistors

Despite the large body of research conducted on organic transistors, the transit frequency of organic field‐effect transistors has seen virtually no improvement for a decade and remains far below 1 GHz. One reason is that most of the research is still focused on improving the charge‐carrier mobility, a parameter that has little influence on the transit frequency of short‐channel transistors. By examining the fundamental equations for the transit frequency of field‐effect transistors and by extrapolating recent progress on the relevant device parameters, a roadmap to gigahertz organic transistors is derived.     

Explaining authors’ contribution to pivotal artifacts during mass collaboration in the Wikipedia’s knowledge base

This article discusses the relevance of large-scale mass collaboration for computer-supported collaborative learning (CSCL) research, adhering to a theoretical perspective that views collective knowledge both as substance and as participatory activity. In an empirical study using the German Wikipedia as a data source, we explored collective knowledge as manifested in the structure of artifacts that were created through the collaborative activity of authors with different levels of contribution experience. Wikipedia’s interconnected articles were considered at the macro level as a network and analyzed using a network analysis approach. The focus of this investigation was the relation between the authors’ experience and their contribution to two types of articles: central pivotal articles within the artifact network of a single knowledge domain and boundary-crossing pivotal articles within the artifact network of two adjacent knowledge domains. Both types of pivotal articles were identified by measuring the network position of artifacts based on network analysis indices of topological centrality. The results showed that authors with specialized contribution experience in one domain predominantly contributed to central pivotal articles within that domain. Authors with generalized contribution experience in two domains predominantly contributed to boundary-crossing pivotal articles between the knowledge domains. Moreover, article experience (i.e., the number of articles in both domains an author had contributed to) was positively related to the contribution to both types of pivotal articles, regardless of whether an author had specialized or generalized domain experience. We discuss the implications of our findings for future studies in the field of CSCL.     

Sensory and molecular characterisation of human milk odour profiles after maternal fish oil supplementation during pregnancy and breastfeeding

The odourant profile of human milk has been proposed to be modulated by the composition of the maternal diet via the transference of specific food aromas to the milk, such that neonates are exposed to these aromas and are prepared for latter acceptance of specific diets. For that reason the aim of the present study was to investigate whether specific fish oil odour constituents translate into human milk. To achieve this goal, human sensory analyses and qualitative and quantitative instrumental determination of fish oil odourants were performed on the fish oil, as well as on human milk obtained from mothers after long-term fish oil supplementation in comparison to a control group. Sensory and analytical data showed that no statistically significant modification occurred from fish oil intervention.     

α‐Keto Phenylamides as P1′‐Extended Proteasome Inhibitors

The major challenge for proteasome inhibitor design lies in achieving high selectivity for, and activity against, the target, which requires specific interactions with the active site. Novel ligands aim to overcome off‐target‐related side effects such as peripheral neuropathy, which is frequently observed in cancer patients treated with the FDA‐approved proteasome inhibitors bortezomib ( 1 ) or carfilzomib ( 2 ). A systematic comparison of electrophilic headgroups recently identified the class of α‐keto amides as promising for next generation drug development. On the basis of crystallographic knowledge, we were able to develop a structure–activity relationship (SAR)‐based approach for rational ligand design using an electronic parameter (Hammett’s σ) and in silico molecular modeling. This resulted in the tripeptidic α‐keto phenylamide BSc4999 [(S)‐3‐(benzyloxycarbonyl‐(S)‐leucyl‐(S)‐leucylamino)‐5‐methyl‐2‐oxo‐N‐(2,4‐dimethylphenyl)hexanamide, 6 a ], a highly potent (IC₅₀=38 nM ), cell‐permeable, and slowly reversible covalent inhibitor which targets both the primed and non‐primed sites of the proteasome’s substrate binding channel as a special criterion for selectivity. The improved inhibition potency and selectivity of this new α‐keto phenylamide makes it a promising candidate for targeting a wider range of tumor subtypes than commercially available proteasome inhibitors and presents a new candidate for future studies.     

Glucose and Glucose Esters in the Larval Secretion of Chrysomela Lapponica; Selectivity of the Glucoside Import System from Host Plant Leaves

Larvae of Chrysomela lapponica (Coleoptera: Chrysomelidae) sequester characteristic O-glucosides from the leaves of their food plants, namely Betula and/or Salix The present study focuses on birch-feeding larvae of C. lapponica from the Altai region in East Kazakhstan. As in other sequestering leaf beetle larvae, the compounds are transported intact via different membrane barriers into the defensive system, followed by glucoside cleavage and subsequent transformations of the plant-derived aglycones. Unlike previous studies with model compounds, we studied the sequestration of phytogenic precursors by analyzing the complex pattern of glucosides present in food plant Betula rotundifolia (39 compounds) and compared this composition with the aglycones present as butyrate esters in the defensive secretion. In addition to the analytic approach, the insect's ability, to transport individual glucosides was tested by using hydrolysis-resistant thioglucoside analogs, applied onto the leaf surface. The test compounds reach the defensive system intact and without intermediate transformation. No significant difference of the transport capacity and selectivity was observed between larvae of birch-feeding population from Kazakhstan, and previous results for larvae of birch-feeding population from the Czech Republic or willow-feeding populations. Overall, the transport of the phytogenic glucosides is highly selective and highly efficient, since only minor compounds of the spectrum of phytogenic glucoside precursors contribute to the limited number of aglycones utilized in the defensive secretion. Interestingly, salicortin 44 and tremulacin 60 were found in the leaves, but no aldehyde or esters of salicylalcohol. Surprisingly, we observed large amounts of free glucose, together with small amounts of 6-O-butyrate esters of glucose (27a/b and 28a/b).