Microencapsulation technology by nature: Cell derived extracellular vesicles with therapeutic potential

Cell derived extracellular vesicles are submicron structures surrounded by phospholipid bilayer and released by both prokaryotic and eukaryotic cells. The sizes of these vesicles roughly fall into the size ranges of microbes, and they represent efficient delivery platforms targeting complex molecular information to professional antigen presenting cells. Critical roles of these naturally formulated units of information have been described in many physiological and pathological processes. Extracellular vesicles are not only potential biomarkers and possible pathogenic factors in numerous diseases, but they are also considered as emerging therapeutic targets and therapeutic vehicles. Strikingly, current drug delivery systems, designed to convey therapeutic proteins and peptides (such as liposomes), show many similarities to extracellular vesicles. Here we review some aspects of therapeutic implementation of natural, cell-derived extracellular vesicles in human diseases. Exploration of molecular and functional details of extracellular vesicle release and action may provide important lessons for the design of future drug delivery systems

Design considerations for a HE-3 refrigerator for space applications

The low temperature provided by He-3 refrigerators (0.3 to 3 K) have useful space applications. However, the low temperatures and the low surface tension of He-3 require special design considerations. The considerations include the need for small pores to contain the liquid in a matrix; the effects of bubble nucleation and growth; and the effects of the thermal conductivity within the matrix. These design considerations are discussed and a possible confinement system is analyzed

Hopping and clustering of oxygen vacancies in SrTiO3 by anelastic relaxation

The complex elastic compliance s11(w,T) of SrTiO3-d has been measured as a function of the O deficiency d < 0.01. The two main relaxation peaks in the absorption are identified with hopping of isolated O vacancies over a barrier of 0.60 eV and reorientation of pairs of vacancies involving a barrier of 1 eV. The pair binding energy is ~0.2 eV and indications for additional clustering, possibly into chains, is found already at d ~0.004. The anistropic component of the elastic dipole of an O vacancy is Deltalambda = 0.026.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

Heavy Fermion Quantum Criticality

During the last few years, investigations of Rare-Earth materials have made clear that not only the heavy fermion phase in these systems provides interesting physics, but the quantum criticality where such a phase dies exhibits novel phase transition physics not fully understood. Moreover, attempts to study the critical point numerically face the infamous fermion sign problem, which limits their accuracy. Effective action techniques and Callan-Symanzik equations have been very popular in high energy physics, where they enjoy a good record of success. Yet, they have been little exploited for fermionic systems in condensed matter physics. In this work, we apply the RG effective action and Callan-Symanzik techiques to the heavy fermion problem. We write for the first time the effective action describing the low energy physics of the system. The f-fermions are replaced by a dynamical scalar field whose nonzero expected value corresponds to the heavy fermion phase. This removes the fermion sign problem, making the effective action amenable to numerical studies as the effective theory is bosonic. Renormalization group studies of the effective action can be performed to extract approximations to nonperturbative effects at the transition. By performing one-loop renormalizations, resummed via Callan-Symanzik methods, we describe the heavy fermion criticality and predict the heavy fermion critical dynamical susceptibility and critical specific heat. The specific heat coefficient exponent we obtain (0.39) is in excellent agreement with the experimental result at low temperatures (0.4).Comment: 5 pages. In the replacement, the numerical value for the specific heat coefficient exponent has been included explicitly in decimal form, and has been compared with the experimental result

Supersolid phases of dipolar bosons in optical lattices with a staggered flux

We present the theoretical mean-field zero-temperature phase diagram of a Bose-Einstein condensate (BEC) with dipolar interactions loaded into an optical lattice with a staggered flux. Apart from uniform superfluid, checkerboard supersolid and striped supersolid phases, we identify several supersolid phases with staggered vortices, which can be seen as combinations of supersolid phases found in earlier work on dipolar BECs and a staggered-vortex phase found for bosons in optical lattices with staggered flux. By allowing for different phases and densities on each of the four sites of the elementary plaquette, more complex phase patterns are found.Comment: 11 pages; added references, minor changes in tex

Distribution of Ca-ATPases in the Medial Habenula in Mouse

The aim of this study was to investigate the distribution of the ecto-Ca,Mg-adenosine-triphosphatases (ecto-Ca,Mg-ATPases) in the medial habenular nucleus. Nerve terminals that seemed to be similar in morphological terms showed a different distribution of enzyme activity. Also, synapses showed a different distribution of enzyme activity. This could be related to the involvement of different neurotransmitters and modulators

Hexagonal spiral growth in the absence of a substrate

Experiments on the formation of spiraling hexagons (350 - 1000 nm in width) from a solution of nanoparticles are presented. Transmission electron microscopy images of the reaction products of chemically synthesized cadmium nanocrystals indicate that the birth of the hexagons proceeds without assistance from static screw or edge dislocatons, that is, they spiral without constraints provided by an underlying substrate. Instead, the apparent growth mechanism relies on what we believe is a dynamical dislocation identified as a dense aggregate of small nanocrystals that straddles the spiraling hexagon at the crystal surface. This nanocrystal bundle, which we term the "feeder", also appears to release nanocrystals into the spiral during the growth process.Comment: 4 pages, 5 figure

Formation and Stability of Cellular Carbon Foam Structures:An {\em Ab Initio} Study

We use ab initio density functional calculations to study the formation and structural as well as thermal stability of cellular foam-like carbon nanostructures. These systems with a mixed $sp^2/sp^3$ bonding character may be viewed as bundles of carbon nanotubes fused to a rigid contiguous 3D honeycomb structure that can be compressed more easily by reducing the symmetry of the honeycombs. The foam may accommodate the same type of defects as graphene, and its surface may be be stabilized by terminating caps. We postulate that the foam may form under non-equilibrium conditions near grain boundaries of a carbon-saturated metal surface

Unidimensional model of the ad-atom diffusion on a substrate submitted to a standing acoustic wave I. Derivation of the ad-atom motion equation

The effect of a standing acoustic wave on the diffusion of an ad-atom on a crystalline surface is theoretically studied. We used an unidimensional space model to study the ad-atom+substrate system. The dynamic equation of the ad-atom, a Generalized Langevin equation, is analytically derived from the full Hamiltonian of the ad-atom+substrate system submitted to the acoustic wave. A detailed analysis of each term of this equation, as well as of their properties, is presented. Special attention is devoted to the expression of the effective force induced by the wave on the ad-atom. It has essentially the same spatial and time dependences as its parent standing acoustic wave