Russian Academy of Sciences

About: Russian Academy of Sciences is a government organization based out in Moscow, Russia. It is known for research contribution in the topics: Catalysis & Laser. The organization has 272615 authors who have published 417512 publications receiving 4538835 citations. The organization is also known as: RAS & RAN.

Transport of Gases and Vapors in Glassy and Rubbery Polymers

Abstract: Transport in non-porous polymeric membranes is based on the so-called ‘solution–diffusion’ concept [1,2]. This model, formulated in the 19th century, is grounded in the works of J. K. Mitchell [3], T. Graham [4] and S. von Wroblewski [5], who demonstrated that the presence of microscopic open pores or capillaries was not a prerequisite for mass transfer through polymeric films (or septa as they were referred to), such as natural rubber. First, Graham in 1829 [4], and then Mitchell in 1831 [3], noted that gases were capable of permeating through non-porous rubber films and that this process was related to gas dissolution and diffusion in the polymeric materials. The currently accepted interpretation of such experiments was given several decades later by Graham [4] (this and other articles from the early history of membrane science have been reproduced, in part, in a special issue of the Journal of Membrane Science) [6]. Because he did not find a monotonic correlation between the rates of transport and the known gas phase diffusion coefficients of the penetrant molecules, Graham concluded that the process of permeation comprised two stages: sorption of gas by the rubber ‘that must depend upon a kind of chemical affinity’ and diffusion of the sorbed gas molecules [4]. The sorbed gas, as he wrote, ‘comes to evaporate . . . . and reappears as gas on the other side of the membrane. Such evaporation is the same into vacuum and into another gas, being equally gas-diffusion in both circumstances’ [4]. Empirical observations of the pressure and thickness dependence of the steady-state gas permeation rate or flux, N, led von Wroblewski [5] to propose the following relation:

Gold nanoparticles in biology and medicine: recent advances and prospects.

Abstract: Functionalized gold nanoparticles with controlled geometrical and optical properties are the subject of intensive studies and biomedical applications, including genomics, biosensorics, immunoassays, clinical chemistry, laser phototherapy of cancer cells and tumors, the targeted delivery of drugs, DNA and antigens, optical bioimaging and the monitoring of cells and tissues with the use of state-of-the-art detection systems. This work will provide an overview of the recent advances and current challenges facing the biomedical application of gold nanoparticles of various sizes, shapes, and structures. The review is focused on the application of gold nanoparticle conjugates in biomedical diagnostics and analytics, photothermal and photodynamic therapies, as a carrier for delivering target molecules, and on the immunological and toxicological properties. Keeping in mind the huge volume and high speed of the data update rate, 2/3 of our reference list (certainly restricted to 250 Refs.) includes publications encompassing the past 5 years.

Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust

Abstract: This paper presents an overview of the polarized sky as seen by Planck HFI at 353 GHz, which is the most sensitive Planck channel for dust polarization. We construct and analyse maps of dust polarization fraction and polarization angle at 1° resolution, taking into account noise bias and possible systematic effects. The sensitivity of the Planck HFI polarization measurements allows for the first time a mapping of Galactic dust polarized emission on large scales, including low column density regions. We find that the maximum observed dust polarization fraction is high (pmax = 19.8%), in particular in some regions of moderate hydrogen column density (NH < 2 × 1021 cm-2). The polarization fraction displays a large scatter at NH below a few 1021 cm-2. There is a general decrease in the dust polarization fraction with increasing column density above NH ≃ 1 × 1021 cm-2 and in particular a sharp drop above NH ≃ 1.5 × 1022 cm-2. We characterize the spatial structure of the polarization angle using the angle dispersion function. We find that the polarization angle is ordered over extended areas of several square degrees, separated by filamentary structures of high angle dispersion function. These appear as interfaces where the sky projection of the magnetic field changes abruptly without variations in the column density. The polarization fraction is found to be anti-correlated with the dispersion of polarization angles. These results suggest that, at the resolution of 1°, depolarization is due mainly to fluctuations in the magnetic field orientation along the line of sight, rather than to the loss of grain alignment in shielded regions. We also compare the polarization of thermal dust emission with that of synchrotron measured with Planck, low-frequency radio data, and Faraday rotation measurements toward extragalactic sources. These components bear resemblance along the Galactic plane and in some regions such as the Fan and North Polar Spur regions. The poor match observed in other regions shows, however, that dust, cosmic-ray electrons, and thermal electrons generally sample different parts of the line of sight.