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Novel insights into the “superglue” of velvet worms The biological “superglue” of velvet worms provides inspiration towards circular processing of advanced polymers. In nature, velvet worms employ a fluid, protein‐rich secretion for hunting and defense, which forms rapidly into stiff fibers. The fluid‐to‐fiber transition occurs outside the body without regulations, indicating that the “instructions” for assembly are programmed into the protein building blocks. Electrostatic interactions between oppositely charged protein domains and free ions drive protein folding, self‐organization (coacervation) and stabilization of the building blocks into nanoscale droplets. Yet, nanodroplets can be instantly transformed via simple mechanical stimulus as proteins partially unfold, merge together and form a strong network, which solidifies into a fiber. The mechanism is based on basic physico‐chemical principles. Thus, by extracting these principles, new methods of synthesizing sustainable polymer‐based materials can be developed.  相似文献   

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Intraosseous line In cases of emergency an intravenous line is necessary to administer live‐saving infusions and drugs. In hemorrhagic shock, hypothermia or circulatory arrest it can be difficult to get access to systemic circulation. An alternative is an intraosseous line by inserting a needle into the medullary cavitiy in the epiphysis of a long bone. With a system working with a cordless screw‐driver the canula can be administered save and in a few seconds. Via the osteons drugs and infusions reach the circulation. Pharmacokinetics are comparable to an intravenous line. Anatomical basics of the technique are 300, first practical work nearly 100 years old. New technologies facilitate the easily application of intraosseous lines in medicine.  相似文献   

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“Inflammatory” Cytokines   总被引:4,自引:0,他引:4  
If cytokines are constitutively expressed by and act on neurons in normal adult brain, then we may have to modify our current view that they are predominantly inflammatory mediators. We critically reviewed the literature to determine whether we could find experimental basis for such a modification. We focused on two "proinflammatory" cytokines, interleukin (IL)-1 and tumor necrosis factor-alpha (TNFalpha) because they have been most thoroughly investigated in shaping our current thinking. Evidence, although equivocal, indicates that the genes coding for these cytokines and their accessory proteins are expressed by neurons, in addition to glial cells, in normal brain. Their expression is region- and cell type-specific. Furthermore, bioactive cytokines have been extracted from various regions of normal brain. The cytokines' receptors selectively are present on all neural cell types, rendering them responsive to cytokine signaling. Blocking their action modifies multiple neural "housekeeping" functions. For example, blocking IL-1 or TNFalpha by several independent means alters regulation of sleep. This indicates that these cytokines likely modulate in the brain behavior of a normal organism. In addition, these cytokines are likely involved in synaptic plasticity, neural transmission, and Ca2+ signaling. Thus, the evidence strongly suggests that these cytokines perform neural functions in normal brain. We therefore propose that they should be thought of as neuromodulators in addition to inflammatory mediators.  相似文献   

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One of the means of creating a more robust methodology for ecological restoration involves reducing the gap between ecological theory and restoration practices. A common strategy to do so is using meta‐analysis to understand key drivers of restoration outcomes. “Active” and “passive” is a dichotomy often used to separate restoration strategies in such meta‐analyses. We investigate previously raised concerns about selection bias and subjective categorization of strategies. We promote a paired experimental design in future empirical research and propose the use of three categories of restoration strategy in lieu of “passive” and “active” to alleviate inconsistency in definitions and categorization.  相似文献   

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There is an intensive search for heterogeneous single atom catalysts (SACs) of high activity, efficiency, durability, and selectivity for a wide variety of electrocatalytic conversion and chemical reactions, such as the hydrogen evolution reaction (HER), oxygen evolution/reduction reaction (OER and ORR), CO2 reduction reaction (CO2 RR), and nitrogen reduction reaction (NRR). With the downsizing from nanoparticles and clusters to single atoms, there are steady changes in the bond and coordination environment for each and every atom involved. Indeed, the single atoms in these electrocatalysts are not “singles”; they are “married” to the supporting surfaces, and their performance is controlled by the bonding and coordination with the substrate surfaces. Herein, an overview is presented on the brief history leading to the rapid development of SACs and their current status, by focusing on their synthesis, control of composition, strategies to realize single atoms with the desired bonds and coordination, and targeted performance in selected reactions. Their applications in the selected spectrum of energy conversion and chemical reactions are discussed, in relation to their structures at varying length scales down to the atomic level. A particular emphasis is placed on on‐going research activities, together with the future perspectives and particular challenges for SACs.  相似文献   

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The possibility of learning time intervals was examined. 7 male BDE-rats (70 days old at the beginning of the experiments) were trained (shock avoidance learning) in a modified test chamber to learn bar-pressing only in distinguished time periods (LD 12: 12). In a second part of the experiment it was examined with 5 rats what effect an extension of the light phase has. The results show that there is a possibility of learning time intervals and of maintaining this behaviour under these specific conditions of training.  相似文献   

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