Dynamics of gelling liquids: a short survey

The dynamics of randomly crosslinked liquids is addressed via a Rouse- and a Zimm-type model with crosslink statistics taken either from bond percolation or Erdoes-Renyi random graphs. While the Rouse-type model isolates the effects of the random connectivity on the dynamics of molecular clusters, the Zimm-type model also accounts for hydrodynamic interactions on a preaveraged level. The incoherent intermediate scattering function is computed in thermal equilibrium, its critical behaviour near the sol-gel transition is analysed and related to the scaling of cluster diffusion constants at the critical point. Second, non-equilibrium dynamics is studied by looking at stress relaxation in a simple shear flow. Anomalous stress relaxation and critical rheological properties are derived. Some of the results contradict long-standing scaling arguments, which are shown to be flawed by inconsistencies.Comment: 21 pages, 3 figures; Dedicated to Lothar Schaefer on the occasion of his 60th birthday; Changes: added comments on the gel phase and some reference

Environmental signals rather than layered ontogeny imprint the function of type 2 conventional dendritic cells in young and adult mice

Conventional dendritic cells (cDC) are key activators of naive T cells, and can be targeted in adults to induce adaptive immunity, but in early life are considered under-developed or functionally immature. Here we show that, in early life, when the immune system develops, cDC2 exhibit a dual hematopoietic origin and, like other myeloid and lymphoid cells, develop in waves. Developmentally distinct cDC2 in early life, despite being distinguishable by fate mapping, are transcriptionally and functionally similar. cDC2 in early and adult life, however, are exposed to distinct cytokine environments that shape their transcriptional profile and alter their ability to sense pathogens, secrete cytokines and polarize T cells. We further show that cDC2 in early life, despite being distinct from cDC2 in adult life, are functionally competent and can induce T cell responses. Our results thus highlight the potential of harnessing cDC2 for boosting immunity in early life.</p

Ultra-Fast Oleophobic-Hydrophilic Switching Surfaces for Anti-Fogging, Self-Cleaning, and Oil-Water Separation

Smooth copolymer–fluorosurfactant complex film surfaces are found to exhibit fast oleophobic–hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80°) and low water contact angle (110°), which, when combined with the inherent ultrafast switching speed, yields oil–water mixture separation efficiencies exceeding 98%

Consensus structure and evolution of 5S rRNA.

A consensus structure model of 5S rRNA presenting all conserved nucleotides in fixed positions has been deduced from the primary and secondary structure of 71 eubacterial, archaebacterial, eukaryotic cytosolic and organellar molecules. Phylogenetically related groups of molecules are characterized by nucleotide deletions in helices III, IV and V, and by potential base pair interactions in helix IV. The group-specific deletions are correlated with the early branching pattern of a dendrogram calculated from nucleotide substitution data: the first major division separates the group of eubacterial and organellar molecules from a second group containing the common ancestors of archaebacterial and eukaryotic/cytosolic molecules. The earliest diverging branch of the eubacterial/organellar group includes molecules from Thermus thermophilus, T. aquaticus, Rhodospirillum rubrum, Paracoccus denitrificans and wheat mitochondria

Phylogenetic tree derived from bacterial, cytosol and organelle 5S rRNA sequences.

A phylogenetic tree was constructed by computer analysis of 47 completely determined 5S rRNA sequences. The wheat mitochondrial sequence is significantly more related to prokaryotic than to eukaryotic sequences, and its affinity to that of the thermophilic Gram-negative bacterium Thermus aquaticus is comparable to the affinity between Anacystis nidulans and chloroplastic sequences. This strongly supports the idea of an endosymbiotic origin of plant mitochondria. A comparison of the plant cytosol and chloroplast sub-trees suggests a similar rate of nucleotide substitution in nuclear genes and chloroplastic genes. Other features of the tree are a common precursor of protozoa and metazoa, which appears to be more related to the fungal than to the plant protosequence, and an early divergence of the archebacterial sequence (Halobacterium cutirubrum) from the prokaryotic branch