The growth of B cell receptor microcluster is a universal response of B cells encountering antigens with different motion features

B lymphocyte cell senses and acquires foreign anti-gens through clonal distributed B cell receptors(BCRs)expressed on the surface of plasma membrane.The presentation formats of antigens are quite diverse.Based on their Brownian diffusion mobility,there are three forms:free mobile soluble antigens,lateral mobile membrane bound antigens,and fixed immobile anti-gens.Here,using high resolution high speed live cell imaging approaches,we provide evidence that BCR microclusters are formed on the surface of B cells shortly after B cell’s encountering of antigens with each format of motion features.Through high speed live cell imaging,we determine that these BCR microclusters show dynamic growth feature and by doing so function as the basic platforms for B cells to acquire the anti-gens.We propose that the formation and dynamic growth of BCR microcluster is a universal mechanism for B cell to response to antigens with diverse motion features.

Microcluster colloidosomes for hemostat delivery into complex wounds:A platform inspired by the attack action of torpedoes

Complex yet lethal wounds with uncontrollable bleeding hinder conventional hemostats from clotting blood at the source or deep sites of injury vasculature,thereby causing massive blood loss and significantly increased mortality.Inspired by the attack action of torpedoes,we synthesized microcluster(MC)colloidosomes equipped with magnetic-mediated navigation and“blast”systems to deliver hemostats into the cavity of vase-type wounds.CaCO_(3)/Fe_(2)O_(3)(CF)microparticles functionalized with Arg-Gly-Asp(RGD)modified polyelectrolyte multilayers were co-assembled with oppositely charged zwitterionic carbon dots(CDs)to form MC colloidosomes,which were loaded with thrombin and protonated tranexamic acid(TXA-NH_(3)^(+)).The composite microparticles moved against blood flow under magnetic mediation and simultaneously disassembled for the burst release of thrombin stimulated by TXA-NH_(3)^(+).The CO_(2) bubbles generated during disassembly produced a“blast”that propelled thrombin into the wound cavity.Severe bleeding in a vase-type hemorrhage model in the rabbit liver was rapidly controlled within~60 s.Furthermore,in vivo subcutaneous muscle and liver implantation models demonstrated excellent biodegradability of MC colloidosomes.This study is the first to propose a novel strategy based on the principle of torpedoes for transporting hemostats into vase-type wounds to achieve rapid hemostasis,creating a new paradigm for combating trauma treatment.

Evolutions of Microclusters of Biodegradable Mg_3Ca_7 Potential Medical Implant Alloy

The molecular dynamics simulation calculation on the microclusters evolution properties of liquid Mg_3Ca_7 during the rapid solidifications has been performed. Results indicated that the icosahedron microcluster played key role in the glass transition which happened at about 600 K; it suggests that the formation and evolution mechanism of icosahedral order is important for the corrosion resistance of medical implant material of Mg- and Mg-Ca based alloys. It is also found that the icosahedron structure is unstable in the liquid and supercooled liquid until the glass transition occurs.

RESEARCH FROM ISOLATED TO COMPACT CLUSTERS

Structures and properties of both isolated and compacted clusters can be studied by SINS, RBS,NMR and Mossbauer effect, etc. Some important properties of these microclusters, such as magic numbers, isotopic effect, gas-like structures are discussed.

CRITICAL SIZE OF COULOMBIC EXPLOSION FOR BIVALENT CATIONS OF SILICON CLUSTERS

Ⅰ. INTRODUCTIONSmall atomic dusters ranging from two to a few hundred atoms per cluster, also referred to as microclusters, attract great interest of physists, chemists and material scientists since 1980’s because of their peculiar behaviors and potential for industrial applications. The coulombic explosion is known as one of the remarkable properties inherent in microdusters. Experiments have shown that some positively charged dusters（cluster cations）, Mnm+